GR SP Dens Log Neu Interpretationpages.geo.wvu.edu/~tcarr/pttc/Schlumberger_chartbook.pdf · Resistivity of NaCl Water Solutions ... Apparent Log Density to True Bulk Density

LogInterpretationCharts2009 Edition

Cem

Perm

SatCH

SatOH

Por

Lith

Rt

REm

RInd

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NMR

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Intro ◀ ▶ Contents

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Schlumberger225 Schlumberger DriveSugar Land, Texas 77478www.slb.com

© 2009 Schlumberger. All rights reserved.

No part of this book may be reproduced, stored in a retrieval system, or transcribed in any form or by any means, electronic or mechanical, including photocopying and recording, without the prior written permission of the publisher. While the information presented herein is believed to be accurate, it is provided “as is” without express or implied warranty.

Specifications are current at the time of printing.

09-FE-0058

An asterisk (*) is used throughout this document todenote a mark of Schlumberger.



Contents

iii

FFoorreewwoorrdd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

GGeenneerraall

Symbols Used in Log Interpretation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--11 . . . . . . . . . . . . . . . . . . . . . . 1

Estimation of Formation Temperature with Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--22 . . . . . . . . . . . . . . . . . . . . . . 3

Estimation of Rmf and Rmc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--33 . . . . . . . . . . . . . . . . . . . . . . 4

Equivalent NaCl Salinity of Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--44 . . . . . . . . . . . . . . . . . . . . . . 5

Concentration of NaCl Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--55 . . . . . . . . . . . . . . . . . . . . . . 6

Resistivity of NaCl Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--66 . . . . . . . . . . . . . . . . . . . . . . 8

Density of Water and Hydrogen Index of Water and Hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--77 . . . . . . . . . . . . . . . . . . . . . . 9

Density and Hydrogen Index of Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--88 . . . . . . . . . . . . . . . . . . . . . 10

Sound Velocity of Hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--99 . . . . . . . . . . . . . . . . . . . . . 11

Gas Effect on Compressional Slowness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--99aa . . . . . . . . . . . . . . . . . . . 12

Gas Effect on Acoustic Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--99bb . . . . . . . . . . . . . . . . . . . 13

Nuclear Magnetic Resonance Relaxation Times of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1100 . . . . . . . . . . . . . . . . . . . 14

Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1111aa . . . . . . . . . . . . . . . . . . 15

Nuclear Magnetic Resonance Relaxation Times of Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1111bb . . . . . . . . . . . . . . . . . . 16

Capture Cross Section of NaCl Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1122 . . . . . . . . . . . . . . . . . . . 18

Capture Cross Section of NaCl Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1133 . . . . . . . . . . . . . . . . . . . 19

Capture Cross Section of Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1144 . . . . . . . . . . . . . . . . . . . 21

EPT* Propagation Time of NaCl Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1155 . . . . . . . . . . . . . . . . . . . 22

EPT Attenuation of NaCl Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1166 . . . . . . . . . . . . . . . . . . . 23

EPT Propagation Time–Attenuation Crossplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGeenn--1166aa . . . . . . . . . . . . . . . . . . 24

GGaammmmaa RRaayy

Scintillation Gamma Ray—33⁄8- and 111⁄16-in. Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--11 . . . . . . . . . . . . . . . . . . . . . . 25



SlimPulse* and E-Pulse* Gamma Ray Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--66 . . . . . . . . . . . . . . . . . . . . . . 28

ImPulse* Gamma Ray—4.75-in. Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--77 . . . . . . . . . . . . . . . . . . . . . . 29

PowerPulse* and TeleScope* Gamma Ray—6.75-in. Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--99 . . . . . . . . . . . . . . . . . . . . . . 30

PowerPulse Gamma Ray—8.25-in. Normal-Flow Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1100 . . . . . . . . . . . . . . . . . . . . 31

PowerPulse Gamma Ray—8.25-in. High-Flow Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1111 . . . . . . . . . . . . . . . . . . . . 32

PowerPulse Gamma Ray—9-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1122 . . . . . . . . . . . . . . . . . . . . 33

PowerPulse Gamma Ray—9.5-in. Normal-Flow Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1133 . . . . . . . . . . . . . . . . . . . . 34

PowerPulse Gamma Ray—9.5-in. High-Flow Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1144 . . . . . . . . . . . . . . . . . . . . 35

geoVISION675* GVR* Gamma Ray—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1155 . . . . . . . . . . . . . . . . . . . . 36

RAB* Gamma Ray—8.25-in. Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1166 . . . . . . . . . . . . . . . . . . . . 37

arcVISION475* Gamma Ray—4.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--1199 . . . . . . . . . . . . . . . . . . . . 38

Contents

Intro ◀ ▶




arcVISION900* Gamma Ray—9-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--2222 . . . . . . . . . . . . . . . . . . . . 41

arcVISION475 Gamma Ray—4.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--2233 . . . . . . . . . . . . . . . . . . . . 42



arcVISION900 Gamma Ray—9-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--2266 . . . . . . . . . . . . . . . . . . . . 45

EcoScope* Integrated LWD Gamma Ray—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--2277 . . . . . . . . . . . . . . . . . . . . 46

EcoScope Integrated LWD Gamma Ray—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GGRR--2288 . . . . . . . . . . . . . . . . . . . . 47

SSppoonnttaanneeoouuss PPootteennttiiaall

Rweq Determination from ESSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--11 . . . . . . . . . . . . . . . . . . . . . . 49

Rweq versus Rw and Formation Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--22 . . . . . . . . . . . . . . . . . . . . . . 50

Rweq versus Rw and Formation Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--33 . . . . . . . . . . . . . . . . . . . . . . 51

Bed Thickness Correction—Open Hole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--44 . . . . . . . . . . . . . . . . . . . . . . 53

Bed Thickness Correction—Open Hole (Empirical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--55 . . . . . . . . . . . . . . . . . . . . . . 54

Bed Thickness Correction—Open Hole (Empirical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSPP--66 . . . . . . . . . . . . . . . . . . . . . . 55

DDeennssiittyy

Porosity Effect on Photoelectric Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DDeennss--11. . . . . . . . . . . . . . . . . . . . 56

Apparent Log Density to True Bulk Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DDeennss--22. . . . . . . . . . . . . . . . . . . . 57

NNeeuuttrroonn

Dual-Spacing Compensated Neutron Tool Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Compensated Neutron Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--11 . . . . . . . . . . . . . . . . . . . . . 60









APS* Accelerator Porosity Sonde. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--1100 . . . . . . . . . . . . . . . . . . . 75

APS Accelerator Porosity Sonde Without Environmental Corrections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--1111 . . . . . . . . . . . . . . . . . . . 76

CDN* Compensated Density Neutron, adnVISION* Azimuthal Density Neutron, and EcoScope* Integrated LWD Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3300 . . . . . . . . . . . . . . . . . . . 78

adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3311 . . . . . . . . . . . . . . . . . . . 80

adnVISION475 BIP Neutron—4.75-in. Tool and 6-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3322 . . . . . . . . . . . . . . . . . . . 81

adnVISION475 Azimuthal Density Neutron—4.75-in. Tool and 8-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3333 . . . . . . . . . . . . . . . . . . . 82


Contents

iv

Intro ◀ ▶


Contents

v

adnVISION675* Azimuthal Density Neutron—6.75-in. Tool and 8-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3355 . . . . . . . . . . . . . . . . . . . 84


adnVISION675 Azimuthal Density Neutron—6.75-in. Tool and 10-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3377 . . . . . . . . . . . . . . . . . . . 86

adnVISION675 BIP Neutron—6.75-in. Tool and 10-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3388 . . . . . . . . . . . . . . . . . . . 87

adnVISION825* Azimuthal Density Neutron—8.25-in. Tool and 12.25-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--3399 . . . . . . . . . . . . . . . . . . . 88

CDN Compensated Density Neutron and adnVISION825s* Azimuthal Density Neutron—8-in. Tool and 12-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4400 . . . . . . . . . . . . . . . . . . . 89

CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron—8-in. Tool and 14-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4411 . . . . . . . . . . . . . . . . . . . 90

CDN Compensated Density Neutron and adnVISION825s Azimuthal Density Neutron—8-in. Tool and 16-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4422 . . . . . . . . . . . . . . . . . . . 91

EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 8.5-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4433 . . . . . . . . . . . . . . . . . . . 93

EcoScope Integrated LWD BPHI Porosity—6.75-in. Tool and 9.5-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4444 . . . . . . . . . . . . . . . . . . . 94

EcoScope Integrated LWD TNPH Porosity—6.75-in. Tool and 8.5-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4455 . . . . . . . . . . . . . . . . . . . 95

EcoScope Integrated LWD TNPH Porosity—6.75-in. Tool and 9.5-in. Borehole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4466 . . . . . . . . . . . . . . . . . . . 96

EcoScope Integrated LWD—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NNeeuu--4477 . . . . . . . . . . . . . . . . . . . 98

NNuucclleeaarr MMaaggnneettiicc RReessoonnaannccee

CMR* Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CCMMRR--11. . . . . . . . . . . . . . . . . . . . 99

RReessiissttiivviittyy LLaatteerroolloogg

ARI* Azimuthal Resistivity Imager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--11 . . . . . . . . . . . . . . . . . . . . 101

High-Resolution Azimuthal Laterolog Sonde (HALS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--22 . . . . . . . . . . . . . . . . . . . . 102








HRLA* High-Resolution Laterolog Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--1100. . . . . . . . . . . . . . . . . . . 110

HRLA High-Resolution Laterolog Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--1111. . . . . . . . . . . . . . . . . . . 111




GeoSteering* Bit Resistivity—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2200. . . . . . . . . . . . . . . . . . . 115

GeoSteering arcVISION675 Resistivity—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2211. . . . . . . . . . . . . . . . . . . 116

GeoSteering Bit Resistivity in Reaming Mode—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2222. . . . . . . . . . . . . . . . . . . 117

geoVISION* Resistivity Sub—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2233. . . . . . . . . . . . . . . . . . . 118

geoVISION Resistivity Sub—8.25-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2244. . . . . . . . . . . . . . . . . . . 119

GeoSteering Bit Resistivity—6.75-in. Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--2255. . . . . . . . . . . . . . . . . . . 120

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CHFR* Cased Hole Formation Resistivity Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--5500. . . . . . . . . . . . . . . . . . . 121

CHFR Cased Hole Formation Resistivity Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--5511. . . . . . . . . . . . . . . . . . . 122

CHFR Cased Hole Formation Resistivity Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRLLll--5522. . . . . . . . . . . . . . . . . . . 123

RReessiissttiivviittyy IInndduuccttiioonn

AIT* Array Induction Imager Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRIInndd--11 . . . . . . . . . . . . . . . . . . 125

AIT Array Induction Imager Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

RReessiissttiivviittyy EElleeccttrroommaaggnneettiicc

arcVISION475 and ImPulse 43⁄4-in. Array Resistivity Compensated Tools—2 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--1111 . . . . . . . . . . . . . . . . . 131




arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—400 kHz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--1155 . . . . . . . . . . . . . . . . . 135




arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--1199 . . . . . . . . . . . . . . . . . 139

arcVISION675 63⁄4-in. Array Resistivity Compensated Tool—2 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--2200 . . . . . . . . . . . . . . . . . 140



arcVISION825 81⁄4-in. Array Resistivity Compensated Tool—400 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--2233 . . . . . . . . . . . . . . . . . 143








arcVISION900 9-in. Array Resistivity Compensated Tool—400 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--3311 . . . . . . . . . . . . . . . . . 151




arcVISION900 9-in. Array Resistivity Compensated Tool—2 MHz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--3355 . . . . . . . . . . . . . . . . . 155



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vii


arcVISION675, arcVISION825, and arcVISION900 Array Resistivity Compensated Tools—400 kHz . . . . . . . . . . . . . . . . RREEmm--5555 . . . . . . . . . . . . . . . . . 160

arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RREEmm--5566 . . . . . . . . . . . . . . . . . 161

arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz and 16-in. Spacing . . . . . . . . . . . . . . . . . . . . . RREEmm--5588 . . . . . . . . . . . . . . . . . 162





arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz with Dielectric Assumption . . . . . . . . . . . RREEmm--6633 . . . . . . . . . . . . . . . . . 167

FFoorrmmaattiioonn RReessiissttiivviittyy

Resistivity Galvanic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--11 . . . . . . . . . . . . . . . . . . . . . 168

High-Resolution Azimuthal Laterlog Sonde (HALS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--22 . . . . . . . . . . . . . . . . . . . . . 169

High-Resolution Azimuthal Laterlog Sonde (HALS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--33 . . . . . . . . . . . . . . . . . . . . . 170

geoVISION675* Resistivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--1100 . . . . . . . . . . . . . . . . . . . . 171

geoVISION675 Resistivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--1111 . . . . . . . . . . . . . . . . . . . . 172



geoVISION825* 81⁄4-in. Resistivity-at-the-Bit Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--1144 . . . . . . . . . . . . . . . . . . . . 175

geoVISION825 81⁄4-in. Resistivity-at-the-Bit Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--1155 . . . . . . . . . . . . . . . . . . . . 176



arcVISION Array Resistivity Compensated Tool—400 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--3311 . . . . . . . . . . . . . . . . . . . . 179

arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--3322 . . . . . . . . . . . . . . . . . . . . 180





arcVISION675 Array Resistivity Compensated Tool—400 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--3377 . . . . . . . . . . . . . . . . . . . . 185

arcVISION675 and ImPulse Array Resistivity Compensated Tools—2 MHz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--3388 . . . . . . . . . . . . . . . . . . . . 186



arcVISION Array Resistivity Compensated Tool—400 kHz in Horizontal Well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--4411 . . . . . . . . . . . . . . . . . . . . 190

arcVISION and ImPulse Array Resistivity Compensated Tools—2 MHz in Horizontal Well . . . . . . . . . . . . . . . . . . . . . . . . . RRtt--4422 . . . . . . . . . . . . . . . . . . . . 191

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viii

LLiitthhoollooggyy

Density and NGS* Natural Gamma Ray Spectrometry Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--11 . . . . . . . . . . . . . . . . . . . 193

NGS Natural Gamma Ray Spectrometry Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--22 . . . . . . . . . . . . . . . . . . . 194

Platform Express* Three-Detector Lithology Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--33 . . . . . . . . . . . . . . . . . . . 196

Platform Express Three-Detector Lithology Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--44 . . . . . . . . . . . . . . . . . . . 197

Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--55 . . . . . . . . . . . . . . . . . . . 198

Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--66 . . . . . . . . . . . . . . . . . . . 200

Environmentally Corrected Neutron Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--77 . . . . . . . . . . . . . . . . . . . 202

Environmentally Corrected APS Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--88 . . . . . . . . . . . . . . . . . . . 204

Bulk Density or Interval Transit Time and Apparent Total Porosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--99 . . . . . . . . . . . . . . . . . . . 206

Bulk Density or Interval Transit Time and Apparent Total Porosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--1100 . . . . . . . . . . . . . . . . . . 207

Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--1111 . . . . . . . . . . . . . . . . . . 209

Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LLiitthh--1122 . . . . . . . . . . . . . . . . . . 210

PPoorroossiittyy

Sonic Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--11 . . . . . . . . . . . . . . . . . . . . 212

Sonic Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--22 . . . . . . . . . . . . . . . . . . . . 213

Density Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--33 . . . . . . . . . . . . . . . . . . . . 214

APS Near-to-Array (APLC) and Near-to-Far (FPLC) Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--44 . . . . . . . . . . . . . . . . . . . . 216

Thermal Neutron Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--55 . . . . . . . . . . . . . . . . . . . . 217

Thermal Neutron Tool—CNT-D and CNT-S 21⁄2-in. Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--66 . . . . . . . . . . . . . . . . . . . . 218

adnVISION475 4.75-in. Azimuthal Density Neutron Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--77 . . . . . . . . . . . . . . . . . . . . 219



EcoScope* 6.75-in. Integrated LWD Tool, BPHI Porosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1100. . . . . . . . . . . . . . . . . . . 222

EcoScope 6.75-in. Integrated LWD Tool, TNPH Porosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1100aa . . . . . . . . . . . . . . . . . 223

CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone) . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1111. . . . . . . . . . . . . . . . . . . 225

CNL Compensated Neutron Log and Litho-Density Tool (salt water in invaded zone) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1122. . . . . . . . . . . . . . . . . . . 226

APS and Litho-Density Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1133. . . . . . . . . . . . . . . . . . . 227

APS and Litho-Density Tools (saltwater formation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1144. . . . . . . . . . . . . . . . . . . 228

adnVISION475 4.75-in. Azimuthal Density Neutron Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1155. . . . . . . . . . . . . . . . . . . 229



EcoScope 6.75-in. Integrated LWD Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1188. . . . . . . . . . . . . . . . . . . 232

EcoScope 6.75-in. Integrated LWD Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--1199. . . . . . . . . . . . . . . . . . . 233

Sonic and Thermal Neutron Crossplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2200. . . . . . . . . . . . . . . . . . . 235

Sonic and Thermal Neutron Crossplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2211. . . . . . . . . . . . . . . . . . . 236

Density and Sonic Crossplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2222. . . . . . . . . . . . . . . . . . . 238

Density and Sonic Crossplot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2233. . . . . . . . . . . . . . . . . . . 239

Density and Neutron Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2244. . . . . . . . . . . . . . . . . . . 241

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ix

Density and APS Epithermal Neutron Tool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2255. . . . . . . . . . . . . . . . . . . 243

Density, Neutron, and Rxo Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2266. . . . . . . . . . . . . . . . . . . 245

Hydrocarbon Density Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPoorr--2277. . . . . . . . . . . . . . . . . . . 246

SSaattuurraattiioonn

Porosity Versus Formation Resistivity Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--11. . . . . . . . . . . . . . . . . 247

Spherical and Fracture Porosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--22. . . . . . . . . . . . . . . . . 248

Saturation Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--33. . . . . . . . . . . . . . . . . 250

Saturation Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--44. . . . . . . . . . . . . . . . . 252

Graphical Determination of Sw from Swt and Swb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--55. . . . . . . . . . . . . . . . . 253

Porosity and Gas Saturation in Empty Hole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--66. . . . . . . . . . . . . . . . . 254

EPT Propagation Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--77. . . . . . . . . . . . . . . . . 255

EPT Attenuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattOOHH--88. . . . . . . . . . . . . . . . . 256

Capture Cross Section Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattCCHH--11. . . . . . . . . . . . . . . . . 258

Capture Cross Section Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattCCHH--22. . . . . . . . . . . . . . . . . 260

RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 6.125-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattCCHH--33. . . . . . . . . . . . . . . . . 262

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SSaattCCHH--44. . . . . . . . . . . . . . . . . 263

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.125-in. Borehole with 4.5-in. Casing at 11.6 lbm/ft . . . . SSaattCCHH--55. . . . . . . . . . . . . . . . . 264

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 7.875-in. Borehole with 5.5-in. Casing at 17 lbm/ft . . . . . . SSaattCCHH--66. . . . . . . . . . . . . . . . . 265

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.5-in. Borehole with 7-in. Casing at 29 lbm/ft. . . . . . . . . . . SSaattCCHH--77. . . . . . . . . . . . . . . . . 266

RST Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole with 7-in. Casing at 29 lbm/ft . . . . . . . . SSaattCCHH--88. . . . . . . . . . . . . . . . . 267

PPeerrmmeeaabbiilliittyy

Permeability from Porosity and Water Saturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPeerrmm--11 . . . . . . . . . . . . . . . . . . 269

Permeability from Porosity and Water Saturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPeerrmm--22 . . . . . . . . . . . . . . . . . . 270

Fluid Mobility Effect on Stoneley Slowness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PPeerrmm--33 . . . . . . . . . . . . . . . . . . 271

CCeemmeenntt EEvvaalluuaattiioonn

Cement Bond Log—Casing Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CCeemm--11 . . . . . . . . . . . . . . . . . . . 274

AAppppeennddiixxeess

Appendix A Linear Grid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

Log-Linear Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276

Water Saturation Grid for Resistivity Versus Porosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

Appendix B Logging Tool Response in Sedimentary Minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

Appendix C Acoustic Characteristics of Common Formations and Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

Appendix D Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

Appendix E Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

Appendix F Subscripts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

Appendix G Unit Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

Appendix H References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292

Intro ◀ ▶



Porosity

xi

Foreword

This edition of the Schlumberger “chartbook” presents several innovations.

First, the charts were developed to achieve two purposes:■ Correct raw measurements to account for environmental effects

Early downhole measurements were performed in rather uniformconditions (vertical wells drilled through quasi-horizontal thickbeds, muds made of water with a narrow selection of additives,and limited range of hole sizes), but today wells can be highlydeviated or horizontal, mud contents are diverse, and hole sizesrange from 2 to 40 in. Environmental effects may be large. Inaddition, they compound. It is essential to correct for these effectsbefore the measurements are used.

■ Use environmentally corrected measurements for interpretation

Charts related to measurements that are no longer performed are not included in this chartbook. However, because many oil andgas companies use logs acquired years or even decades ago, the second chartbook, Historical Log Interpretation Charts, containsthese old charts.

Why publish charts on paper in our electronic age? It is true thatsoftware may be more effective than pencil to derive results. Evenmore so, this chartbook cannot cope with the complex well situationsthat are encountered. Using software is the only way to proceed.

Thus, the chartbook has two primary functions:■ Training

The chartbook is essential for educating junior petrophysicistsabout the different effects on the measurements. In the interpre-tation process, the chartbook unveils the relationships betweenthe different parameters.

■ Sensitivity analysisA chart gives the user a graphical idea of the sensitivity of an out-put to the various inputs (see Chart Gen-1). The visual presenta-tion is helpful for determining if an input parameter is critical.The user can then focus on the most sensitive inputs.

Foreword

◀ ▶ Back to Contents


Gen

General

Symbols Used in Log InterpretationGen-1

(former Gen-3)

1

dhHole

diameter

di

dj

h

Δrj

(Invasion diameters)

Adjacent bed

Zone of transition

or annulus

Flushed zone

Adjacent bed

(Bedthickness)

Mud

hmc

dh

Rm

Rs

Rs

Resistivity of the zoneResistivity of the water in the zoneWater saturation in the zone

Rmc

Mudcake

Rmf

Sxo

Rxo

Rw

Sw

Rt

Ri

Uninvadedzone

PurposeThis diagram presents the symbols and their descriptions and rela-tions as used in the charts. See Appendixes D and E for identifica-tion of the symbols.

DescriptionThe wellbore is shown traversing adjacent beds above and below thezone of interest. The symbols and descriptions provide a graphicalrepresentation of the location of the various symbols within the well-bore and formations.

© Schlumberger


General

2

Gen

Estimation of Formation Temperature with Depth

PurposeThis chart has a twofold purpose. First, a geothermal gradient can be assumed by entering the depth and a recorded temperature atthat depth. Second, for an assumed geothermal gradient, if the tem-perature is known at one depth in the well, the temperature atanother depth in the well can be determined.

DescriptionDepth is on the y-axis and has the shallowest at the top and thedeepest at the bottom. Both feet and meters are used, on the leftand right axes, respectively. Temperature is plotted on the x-axis,with Fahrenheit on the bottom and Celsius on the top of the chart.The annual mean surface temperature is also presented inFahrenheit and Celsius.

ExampleGiven: Bottomhole depth = 11,000 ft and bottomhole tempera-

ture = 200°F (annual mean surface temperature = 80°F).

Find: Temperature at 8,000 ft.

Answer: The intersection of 11,000 ft on the y-axis and 200°F on the x-axis is a geothermal gradient of approximately1.1°F/100 ft (Point A on the chart).

Move upward along an imaginary line parallel to the con-structed gradient lines until the depth line for 8,000 ft isintersected. This is Point B, for which the temperatureon the x-axis is approximately 167°F.


General

3

Gen

General

Estimation of Formation Temperature with DepthGen-2

(former Gen-6)

80 100 150 200 250 300 350 60 100 150 200 250 300 350

27 50 75 100 125 150 175

16 25 50 75 100 125 150 175

Temperature (°F)

Temperature (°C)

Temperature gradient conversions: 1°F/100 ft = 1.823°C/100 m 1°C/100 m = 0.5486°F/100 ft

Depth(thousands

of feet)

Depth(thousandsof meters)

Annual meansurface temperature

Annual meansurface temperature

5

10

15

20

25

1

2

3

4

5

6

7

8

0.6 0.8 1.0 1.2 1.4 1.6°F/100 ft

1.09 1.46 1.82 2.19 2.55 2.92°C/100 m

B

A

Geothermal gradient

© Schlumberger


General

4

Gen

Estimation of Rmf and RmcFluid Properties Gen-3

(former Gen-7)

PurposeDirect measurements of filtrate and mudcake samples are preferred.When these are not available, the mud filtrate resistivity (Rmf) andmudcake resistivity (Rmc) can be estimated with the following methods.

DescriptionMethod 1: Lowe and DunlapFor freshwater muds with measured values of mud resistivity (Rm)between 0.1 and 2.0 ohm-m at 75°F [24°C] and measured values ofmud density (ρm) (also called mud weight) in pounds per gallon:

Method 2: Overton and LipsonFor drilling muds with measured values of Rm between 0.1 and 10.0 ohm-m at 75°F [24°C] and the coefficient of mud (Km) given as a function of mud weight from the table:

ExampleGiven: Rm = 3.5 ohm-m at 75°F and mud weight = 12 lbm/gal

[1,440 kg/m3].

Find: Estimated values of Rmf and Rmc.

Answer: From the table, Km = 0.584.

Rmf = (0.584)(3.5)1.07 = 2.23 ohm-m at 75°F.

Rmc = 0.69(2.23)(3.5/2.23)2.65 = 5.07 ohm-m at 75°F.

log . = . .R

Rmf

mm

⎛

⎝⎜⎞

⎠⎟− ×( )0 396 0 0475 ρ

R K R

R RR

R

mf m m

mc mfm

mf

= ( )

= ( )⎛

⎝⎜⎞

⎠⎟

1 07

2 65

0 69

.

.

. .

Mud Weight

lbm/gal kg/m3 Km

10 1,200 0.84711 1,320 0.70812 1,440 0.58413 1,560 0.48814 1,680 0.41216 1,920 0.380

18 2,160 0.350


10 20 50 100 200 500 1,000 2,000 5,000 10,000 20,000 50,000 100,000 300,000

2.0

1.5

1.0

0.5

0

–0.5

2.0

1.0

0

Total solids concentration (ppm or mg/kg)

Multiplier

† Multipliers that do not vary appreciably for low concentrations (less than about 10,000 ppm) are shown at the left margin of the chart

Li (2.5)†

NH4 (1.9)†

Na and CI (1.0)

NO3 (0.55)†

Br (0.44)†

I (0.28)†

OH (5.5)†

Mg

Mg

K

K

Ca

Ca

CO3

CO3

SO4

SO4

HCO3

HCO3

General

5

Gen

PurposeThis chart is used to approximate the parts-per-million (ppm) con-centration of a sodium chloride (NaCl) solution for which the totalsolids concentration of the solution is known. Once the equivalentconcentration of the solution is known, the resistivity of the solutionfor a given temperature can be estimated with Chart Gen-6.

DescriptionThe x-axis of the semilog chart is scaled in total solids concentrationand the y-axis is the weighting multiplier. The curve set representsthe various multipliers for the solids typically in formation water.

ExampleGiven: Formation water sample with solids concentrations

of calcium (Ca) = 460 ppm, sulfate (SO4) = 1,400 ppm,and Na plus Cl = 19,000 ppm. Total solids concentration= 460 + 1,400 + 19,000 = 20,860 ppm.

Find: Equivalent NaCl solution in ppm.

Answer: Enter the x-axis at 20,860 ppm and read the multipliervalue for each of the solids curves from the y-axis: Ca = 0.81, SO4 = 0.45, and NaCl = 1.0. Multiply each concentration by its multiplier:

(460 × 0.81) + (1,400 × 0.45) + (19,000 × 1.0) = 20,000 ppm.

Equivalent NaCl Salinity of SaltsGen-4

(former Gen-8)

© Schlumberger


Gen

General

6

Concentration of NaCl SolutionsGen-5

° =°

−API141 5

131 5.

.sg at 60 F

g/L at77°F

ppm grains/galat 77°F °F/100 ft °C/100 ft °API

Oil GravityConcentrations of NaCl Solutions

Temperature GradientConversion

Specificgravity (sg) at 60°F

Density of NaClsolution at77°F [25°C]

0.15 150

200

300

400

500600

8001,000

1,500

2,000

3,000

4,000

5,0006,000

8,000

10,000

15,000

20,000

30,000

40,000

60,000

80,000

100,000

150,000

200,000250,000

101.00

1.005

1.01

1.02

1.03

1.041.051.061.071.081.091.101.121.141.161.181.20

1.0

1.5

2.0

2.5

3.0

0.60

0.62

0.64

0.66

0.68

0.70

0.72

0.74

0.76

0.780.800.820.840.860.880.900.920.940.960.981.001.021.041.061.08

3.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

100

90

80

70

60

50

40

30

20

10

0

1.8

1.9

2.0

12.515

20

2530

40

5060708090100125150

200

250300

400

5006007008009001,0001,2501,500

2,000

2,5003,000

4,0005,0006,0007,0008,0009,00010,00012,50015,00017,500

0.2

0.3

0.4

0.50.6

0.81.0

1.5

2

3

456

8

10

15

20

30

405060

80100125150

200250300

1°F/100 ft = 1.822°C/100 m1°C/100 m = 0.5488°F/100 ft

© Schlumberger


Gen

General

7

Resistivity of NaCl Water Solutions

PurposeThis chart has a twofold purpose. The first is to determine the resis-tivity of an equivalent NaCl concentration (from Chart Gen-4) at aspecific temperature. The second is to provide a transition of resis-tivity at a specific temperature to another temperature. The solutionresistivity value and temperature at which the value was determinedare used to approximate the NaCl ppm concentration.

DescriptionThe two-cycle log scale on the x-axis presents two temperaturescales for Fahrenheit and Celsius. Resistivity values are on the leftfour-cycle log scale y-axis. The NaCl concentration in ppm andgrains/gal at 75°F [24°C] is on the right y-axis. The conversion approximation equation for the temperature (T) effect on the resistivity (R) value at the top of the chart is valid only for thetemperature range of 68° to 212°F [20° to 100°C].

Example OneGiven: NaCl equivalent concentration = 20,000 ppm.

Temperature of concentration = 75°F.

Find: Resistivity of the solution.

Answer: Enter the ppm concentration on the y-axis and the tem-perature on the x-axis to locate their point of intersec-tion on the chart. The value of this point on the lefty-axis is 0.3 ohm-m at 75°F.

Example TwoGiven: Solution resistivity = 0.3 ohm-m at 75°F.

Find: Solution resistivity at 200°F [93°C].

Answer 1: Enter 0.3 ohm-m and 75°F and find their intersection on the 20,000-ppm concentration line. Follow the line tothe right to intersect the 200°F vertical line (interpolatebetween existing lines if necessary). The resistivity valuefor this point on the left y-axis is 0.115 ohm-m.

Answer 2: Resistivity at 200°F = resistivity at 75°F × [(75 + 6.77)/(200 + 6.77)] = 0.3 × (81.77/206.77) = 0.1186 ohm-m.

continued on next page


General

8

Gen

Resistivity of NaCl Water SolutionsGen-6

(former Gen-9)

°F 50 75 100 125 150 200 250 300 350 400°C 10 20 30 40 50 60 70 80 90 100 120 140 160 180 200

Temperature

Resistivityof solution(ohm-m)

ppm

10

8

6

5

4

3

2

1

0.8

0.60.5

0.4

0.3

0.2

0.1

0.08

0.060.05

0.04

0.03

0.02

0.01

200

300

400

5006007008001,0001,2001,4001,7002,000

3,0004,0005,0006,0007,0008,00010,00012,00014,00017,00020,000

30,00040,00050,00060,00070,00080,000100,000120,000140,000170,000200,000250,000280,000

Conversion approximated by R2 = R1 [(T1 + 6.77)/(T2 + 6.77)]°F or R2 = R1 [(T1 + 21.5) /(T2 + 21.5)]°C

300,000

NaClconcentration

(ppm orgrains/gal)

grains/galat 75°F

10

15

20

2530

40

50

100

150

200

250300

400

500

1,000

1,500

2,0002,5003,000

4,0005,000

10,000

15,00020,000

© Schlumberger


General

9

Gen

Density of Water and Hydrogen Index of Water and HydrocarbonsGen-7

PurposeThese charts are for determination of the density (g/cm3) and hydro-gen index of water for known values of temperature, pressure, andsalinity of the water. From a known hydrocarbon density of oil, adetermination of the hydrogen index of the oil can be obtained.

Description: Density of WaterTo obtain the density of the water, enter the desired temperature (°Fat the bottom x-axis or °C at the top) and intersect the pressure andsalinity in the chart. From that point read the density on the y-axis.

Example: Density of WaterGiven: Temperature = 200°F [93°C], pressure = 7,000 psi, and

salinity = 250,000 ppm.

Answer: Density of water = 1.15 g/cm3.

Example: Hydrogen Index of Salt WaterGiven: Salinity of saltwater = 125,000 ppm.

Answer: Hydrogen index = 0.95.

Example: Hydrogen Index of HydrocarbonsGiven: Oil density = 0.60 g/cm3.

Answer: Hydrocarbon index = approximately 0.91.

1.20

Pressure NaCl

14.7 psi1,000 psi7,000 psi

25 50 100

Temperature (°C)

Temperature (°F)

Hydrogen Index of Salt Water

Hydrogen Index of Live Hydrocarbons and Gas

Salinity (kppm or g/kg)

Hydrocarbon density (g/cm3)

150 200

0.85440400 30020010040

Hydrocarbons

Water

0.90

0.95

1.00

1.05

1.10

1.15

1.05

1.2

1.2

1.0

1.00

0

0.2

0.2

0.4

0.4

0.6

0.6

0.8

0.8

1.00

0.95

0.90

0.850 50 100 150 200 250

Water density (g/cm3)

Hydrogenindex

Hydrogenindex

250,000 ppm

200,000 ppm

150,000 ppm

100,000 ppm

50,000 ppm

Distilled water

© Schlumberger


General

10

Gen

PurposeThis chart can be used to determine more than one characteristic of natural gas under different conditions. The characteristics are gas density (ρg), gas pressure, and hydrogen index (Hgas).

DescriptionFor known values of gas density, pressure, and temperature, the valueof Hgas can be determined. If only the gas pressure and temperatureare known, then the gas density and Hgas can be determined. If thegas density and temperature are known, then the gas pressure andHgas can be determined.

ExampleGiven: Gas density = 0.2 g/cm3 and temperature = 200°F.

Find: Gas pressure and hydrogen index.

Answer: Gas pressure = approximately 5,200 psi and Hgas = 0.44.

Density and Hydrogen Index of Natural GasGen-8

0

0.1

0.2

0.3

0.4

0.5

100 200 400300

17,50015,00012,50010,000

7,500

5,000

2,500

Temperature (°F)

Pressure (psi)

Gas gravity = 0.65

Gas density (g/cm3)

Gas pressure × 1,000 (psia)

0

0.1

0.2

0.3 0.7

Hgas

Gastemperature

(°F)

Gas gravity = 0.6(Air = 1.0)

0.6 100

150200250300350

0.5

0.4

0.3

0.2

0.1

0 0 2 4 6 8 10

Gas density (g/cm3)

14.7

© Schlumberger


General

11

PurposeThis chart is used to determine the sound velocity (ft/s) and soundslowness (μs/ft) of gas in the formation. These values are helpful insonic and seismic interpretations.

DescriptionEnter the chart with the temperature (Celsius along the top x-axisand Fahrenheit along the bottom) to intersect the formation pore pressure.

Gen

General

Sound Velocity of HydrocarbonsGen-9

Gas gravity = 0.65

Natural Gas

50 100 150 200 250 300 3500

1,000

2,000

3,000

4,000

5,000 200

250

30017,500

15,000

12,500

10,000

7,500

5,000

2,500

14.7

400

500

1,000

2,000

Temperature (°C)

Pressure (psi)

Temperature (°F)

Soundvelocity

(ft /s)

Soundslowness

(μs/ft)

0 50 100 150 200

© Schlumberger


Gas Effect on Compressional Slowness

General

Gen-9a

12

Gen

PurposeThis chart illustrates the effect that gas in the formation has on theslowness time of sound from the sonic tool to anticipate the slownessof a formation that contains gas and liquid.

DescriptionEnter the chart with the compressional slowness time (Δtc) from thesonic log on the y-axis and the liquid saturation of the formation onthe x-axis. The curves are used to determine the gas effect on thebasis of which correlation (Wood’s law or Power law) is applied. Theslowing effect begins sooner for the Power law correlation. TheWood’s law correlation slightly increases Δtc values as the formationliquid saturation increases whereas the Power law correlationdecreases Δtc values from about 20% liquid saturation.

1000

200

100

200 μs/ft

110 μs/ft

90 μs/ft

70 μs/ft

50

Δtc(μs/ft)

Wetsand

Sandstone

80604020

Wood’s law (e = 5) Power law (e = 3)

Liquid saturation (%)

© Schlumberger


General

Gas Effect on Acoustic VelocitySandstone and Limestone Gen-9b

13

Limestone

Sandstone

0 10 20 30 40

25

00

5

10

10

15

20

20

25

30 40

20

15

10

5

0

Porosity (p.u.)

Porosity (p.u.)

Velocity(1,000 × ft /s)

Velocity(1,000 × ft /s) Vp

Vs

Vs

Vp

No gasGas bearing

No gasGas bearing

Gen

PurposeThis chart is used to determine porosity from the compressionalwave or shear wave velocity (Vp and Vs, respectively).

DescriptionEnter Vp or Vs on the y-axis to intersect the appropriate curve. Readthe porosity for the sandstone or limestone formation on the x-axis.

© Schlumberger


General

14

Gen

PurposeLongitudinal (Bulk) Relaxation Time of Pure WaterThis chart provides an approximation of the bulk relaxation time(T1) of pure water depending on the temperature of the water.

Transverse (Bulk and Diffusion) Relaxation Time of Water in the FormationDetermining the bulk and diffusion relaxation time (T2) from thischart requires knowledge of both the formation temperature and the echo spacing (TE) used to acquire the data. These data are pre-sented graphically on the log and are the basis of the water or hydrocarbon interpretation of the zone of interest.

DescriptionLongitudinal Relaxation TimeThe chart relation is for pure water—the additives in drilling fluidsreduce the relaxation time (T1) of water in the invaded zone. Thetwo major contributors to the reduction are surfactants added to thedrilling fluid and the molecular interactions of the mud filtrate con-tained in the pore spaces and matrix minerals of the formation.

Transverse Relaxation TimeThe relaxation time (T2) determination is based on the formationtemperature and echo spacing used to acquire the measurement.The TE value is listed in the parameter section of the log. Using the T2 measurement from a known water sand or based on localexperience further aids in determining whether a zone of interest contains hydrocarbons, water, or both.

Nuclear Magnetic Resonance Relaxation Times of WaterGen-10

Longitudinal (Bulk) RelaxationTime of Water

Temperature (°C)

Relaxationtime (s)

100

10

1.0

0.1

0.0120 60 100 140 180

T1

Transverse (Bulk and Diffusion) Relaxation Time of Water

Temperature (°C)

Relaxationtime (s)

100

10

1.0

0.1

0.0120 60 100 140 180

T2 (TE = 0.2 ms)

T2 (TE = 0.32 ms)

T2 (TE = 1 ms)

T2 (TE = 2 ms)

© Schlumberger


General

15

Gen

Nuclear Magnetic Resonance Relaxation Times of HydrocarbonsGen-11a

PurposeLongitudinal (Bulk) Relaxation Time of Crude OilThis chart is used to predict the T1 of crude oils with various viscosi-ties and densities or specific gravities to assist in interpretation ofthe fluid content of the formation of interest.

Transverse (Bulk and Diffusion) Relaxation TimeKnown values of T2 and TE can be used to approximate the viscosityby using this chart.

Diffusion Coefficients for Hydrocarbon and WaterThese charts are used to predict the diffusion coefficient of hydro-carbon as a function of formation temperature and viscosity and of water as a function of formation temperature.

DescriptionLongitudinal (Bulk) Relaxation TimeThis chart is divided into three distinct sections based on the compo-sition of the oil measured. The type of oil contained in the formationcan be determined from the measured T1 and viscosity determinedfrom the transverse relaxation time chart.

Transverse (Bulk and Diffusion) Relaxation TimeThe viscosity can be determined with values of the measured T2 andTE for input to the longitudinal relaxation time chart to identify thetype of oil in the formation.

Transverse (Bulk and Diffusion) Relaxation Time of Crude Oil

T1 (s)

Longitudinal (Bulk) Relaxation Time of Crude Oil

Viscosity (cp)

0.1 1 10 100 1,000 10,000 100,000

0.001

0.01

0.1

1

10

0.0001

T2 (s)

Viscosity (cp)

0.1 1 10 100 1,000 10,000 100,000

0.001

0.01

0.1

1

10

0.0001

Diffusion (cm2/s)

Hydrocarbon Diffusion Coefficient10–3

10–4

10–5

10–6

10–7

1500 50 100 200

Temperature (°C)

Oil (9° at 20°C)

Oil (40° at 20°C)

Diffusion (10–5 cm2/s)

Water Diffusion Coefficient

Temperature (°C)

0 50 100 150 2000

5

10

15

20

Light oil: 45°–60° API 0.65–0.75 g/cm3

Medium oil: 25°–40° API 0.75–0.85 g/cm3

Heavy oil: 10°–20° API 0.85–0.95 g/cm3

TE = 0.2 ms TE = 0.32 ms TE = 1 ms TE = 2 ms

T1

© Schlumberger


General

Nuclear Magnetic Resonance Relaxation Times of HydrocarbonsGen-11b

16

0 0.2 0.4 0.6 0.8 1.0 1.20

0.2

0.4

0.6

0.8

1.0

1.2

Hydrocarbon density (g/cm3)

Hydrogen index

Hydrogen Index of Live Hydrocarbons and Gas

0

2

4

6

0 6,000 9,000

25°C75°C125°C175°C

Longitudinal (Bulk) Relaxation Time of Methane

Pressure (psi)

3,000 12,000

10

8

Diffusion (cm2/s)

10–20.001

Transverse (Bulk and Diffusion) Relaxation Time of Methane

TE = 2 ms

100

10–4

0.01

0.1

1

10

10–3

T2 (s)

TE = 1 ms

TE = 0.32 ms

TE = 0.2 ms

T1 (s)

10

15

20

25

30

35

50 100 150 200

Methane Diffusion Coefficient

Diffusion (10–4 cm2/s)

Temperature (°C)

1,600 psi

3,000

00

5

8,300

15,500

22,800

3,900

4,500

00

Gen

General

PurposeMethane Diffusion CoefficientThis chart is used to determine the diffusion coefficient of methaneat a known formation temperature and pressure.

Longitudinal and Transverse Relaxation Times of MethaneThese charts are used to determine the longitudinal relaxation time(T1) of methane by using the formation temperature and pressure(see Reference 48) and the transverse relaxation time (T2) ofmethane by using the diffusion and echo spacing (TE), respectively.

Hydrogen Index of Live Hydrocarbons and GasThis chart is used to determine the hydrogen index from the hydro-carbon density.

© Schlumberger


General

Capture Cross Section of NaCl Water Solutions

17

GenPurposeThe sigma value (Σw) of a saltwater solution can be determined fromthis chart. The sigma water value is used to calculate the water satu-ration of a formation.

DescriptionCharts Gen-12 and Gen-13 define sigma water for pressure condi-tions of ambient through 20,000 psi [138 MPa] and temperaturesfrom 68° to 500°F [20° to 260°C]. Enter the appropriate chart forthe pressure value with the known water salinity on the y-axis andmove horizontally to intersect the formation temperature. The sigmaof the formation water for the intersection point is on the x-axis.

ExampleGiven: Water salinity = 125,000 ppm, temperature = 68°F at

ambient pressure, and formation temperature = 190°Fat 5,000 psi.

Find: Σw at ambient conditions and Σw of the formation.

Answer: Σw = 69 c.u. and Σw of the formation = 67 c.u.

If the sigma water apparent (Σwa) is known from a clean watersand, then the salinity of the formation can be determined by enter-ing the chart from the sigma water value on the x-axis to intersectthe pressure and temperature values.



General

18

Gen

Ambient

200°F

[93°C

]

68°F [

20°C]

400°F

[205°C

]

300°F

[150°C

]

200°F

[93°C

]

68°F [

20°C]

400°F

[205°C

]

300°F

[150°C

]

200°F

[93°C

]

68°F [

20°C]

1,000

psi [6.

9 MPa]

5,000

psi [34

MPa]

300

275

250

225

200

175

150

125

100

75

50

25

0

100

75

50

25

0

100

75

50

25

0

300

275

250

225

200

300

275

250

225

200

300

275

250

225

200

175

150

125

100

75

50

25

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

125

150

175175

150

125

Equivalent water salinity(1,000 × ppm NaCl)

Capture Cross Section of NaCl Water SolutionsGen-12

(former Tcor-2a)

© Schlumberger


General

Capture Cross Section of NaCl Water SolutionsGen-13

(former Tcor-2b)

19

Gen

10,00

0 psi

[69 M

Pa]500

°F [26

0°C]

400°F

[205°C

]

300°F

[150°C

]

200°F

[93°C

]

68°F [

20°C]

400°F

[205°C

]

300°F

[150°C

]

200°F

[93°C

]

68°F [

20°C]

400°F

[205°C

]

300°F

[150°C

]

200°F

[93°C

]

68°F [

20°C]

15,00

0 psi

[103 M

Pa]

20,00

0 psi

[138 M

Pa]

300

275

250

225

200

175

150

125

100

75

50

25

0

100

75

50

25

0

100

75

50

25

0

300

275

250

225

200

300

275

250

225

200

300

275

250

225

200

175

150

125

100

75

50

25

0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Equivalent water salinity(1,000 × ppm NaCl)

125

150

175175

150

125

PurposeChart Gen-13 continues Chart Gen-12 at higher pressure values forthe determination of Σw of a saltwater solution.

© Schlumberger


PurposeSigma hydrocarbon (Σh) for gas or oil can be determined by usingthis chart. Sigma hydrocarbon is used to calculate the water satura-tion of a formation.

DescriptionOne set of charts is for measurement in metric units and the other is for measurements in “customary” oilfield units.

For gas, enter the background chart of a chart set with the reser-voir pressure and temperature. At that intersection point move leftto the y-axis and read the sigma of methane gas.

For oil, use the foreground chart and enter the solution gas/oilratio (GOR) of the oil on the x-axis. Move upward to intersect theappropriate API gravity curve for the oil. From this intersectionpoint, move horizontally left and read the sigma of the oil on the y-axis.

ExampleGiven: Reservoir pressure = 8,000 psi, reservoir temperature =

300°F, gravity of reservoir oil = 30°API, and solution GOR = 200.

Find: Sigma gas and sigma oil.

Answer: Sigma gas = 10 c.u. and sigma oil = 21.6 c.u.

General

20

Gen

Capture Cross Section of Hydrocarbons


General

21

Gen

Capture Cross Section of HydrocarbonsGen-14

(former Tcor-1)

20.0

17.5

15.0

12.5

10.0

7.5

5.0

2.5

0

68

125

200

300400500

Reservoir pressure (psia)

0 4,000 8,000 12,000 16,000 20,000

Methane

Temperature (°F)Σh (c.u.)

Customary

10 100 1,000 10,000

Solution GOR (ft3/bbl)

Liquid hydrocarbons

Condensate

30°, 40°, and 50°API

20° and 60°API

16

18

20

22

Σh (c.u.)

Metric

20.0

17.5

15.0

12.5

10.0

7.5

5.0

2.5

0

20

52

93

150

260

Reservoir pressure (mPa)

0 14 28 41 55 69 83 97 110 124 138

Methane

Temperature (°C)Σh (c.u.)

2 10 100 1,000 2,000

Solution GOR (m3/m3)

205

Condensate

Liquid hydrocarbons

0.78 to 0.88 mg/m3

0.74 or 0.94 mg/m3

16

18

20

22

Σh (c.u.)

© Schlumberger


General

EPT* Propagation Time of NaCl Water SolutionsGen-15

(former EPTcor-1)

22

PurposeThis chart is designed to determine the propagation time (tpw) ofsaltwater solutions. The value of tpw of a water zone is used to deter-mine the temperature variation of the salinity of the formation water.

DescriptionEnter the chart with the known salinity of the zone of interest andmove upward to the formation temperature curve. From that inter-section point move horizontally left and read the propagation time of the water in the formation on the y-axis. Conversely, enter thechart with a known value of tpw from the EPT ElectromagneticPropagation Tool log to intersect the formation temperature curveand read the water salinity at the bottom of the chart.

90

80

70

60

50

40

30

20 0 50 100 150 200 250

Equivalent water salinity (1,000 × ppm or g/kg NaCl)

tpw (ns/m)

120°C250°F

100°C200°F

80°C175°F

40°C100°F

150°F 60°C

75°F 20°C

125°F

Gen

*Mark of Schlumberger© Schlumberger


General

23

Gen

EPT* Attenuation of NaCl Water SolutionsGen-16

(former EPTcor-2)

PurposeThis chart is designed to estimate the attenuation of saltwater solu-tions. The attenuation (Aw) value of a water zone is used in conjunc-tion with the spreading loss determined from the EPT propagationtime measurement (tpl) to determine the saturation of the flushedzone by using Chart SatOH-8.

DescriptionEnter the chart with the known salinity of the zone of interest andmove upward to the formation temperature curve. From that intersec-tion point move horizontally left and read the attenuation of the waterin the formation on the y-axis. Conversely, enter the chart with a knownEATT attenuation value of Aw from the EPT ElectromagneticPropagation Tool log to intersect the formation temperature curveand read the water salinity at the bottom of the chart.

0 5 10 15 20 25 30

Uncorrected tpl (ns/m)

0 50 100 150 200 250

Equivalent water salinity (kppm or g/kg NaCl)

Correctionto EATT(dB/m)

–40

–60

–80

–100

–120

–140

–160

–180

–200

120°C250°F100°C200°F 80°C175°F

40°C100°F

150°F 60°C

75°F 20°C

125°F

5,000

4,000

3,000

2,000

1,000

0

Attenuation,Aw

(dB/m)

EPT-D Spreading Loss



General

24

Gen

EPT* Propagation Time–Attenuation CrossplotSandstone Formation at 150°F [60°C] Gen-16a

PurposeThis chart is used to determine the apparent resistivity of the mudfiltrate (Rmfa) from measurements from the EPT ElectromagneticPropagation Tool. The porosity of the formation (φEPT) can also beestimated. Porosity and mud filtrate resistivity values are used indetermining the water saturation.

DescriptionEnter the chart with the known attenuation and propagation time(tpl). The intersection of those values identifies Rmfa and φEPT fromthe two sets of curves. This chart is characterized for a sandstoneformation at a temperature of 150°F [60°C].

ExampleGiven: Attenuation = 300 dB/m and tpl = 13 ns/m.

Find: Apparent resistivity of the mud filtrate and EPT porosity.

Answer: Rmfa = 0.1 ohm-m and φEPT = 20 p.u.

1,000

900

800

700

600

500

400

300

200

100

07 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

1.0

40 50302010

2.05.0

10.050.0

Attenuation(dB/m)

tpl (ns/m)

Sandstone at 150°F [60°C]

Rmfa from EPT log (ohm-m)

EPT

poro

sity (φ EP

T)

0.02 0.05

0.1

0.2

0.5



Gamma Ray—Wireline

Scintillation Gamma Ray—33⁄8- and 111⁄16-in. ToolsGamma Ray Correction for Hole Size and Barite Mud Weight GR–1

(former GR-1)

25

PurposeThis chart provides a correction factor for measured values of forma-tion gamma ray (GR) in gAPI units. The corrected GR values can beused to determine shale volume corrections for calculating water saturation in shaly sands.

DescriptionThe semilog chart has the t factor on the x-axis and the correctionfactor on the y-axis.

The input parameter, t, in g/cm2, is calculated as follows:

where

Wmud = mud weight (lbm/gal)

dh = diameter of wellbore (in.)

dsonde = outside diameter (OD) of tool (in.).

ExampleGiven: GR = 36 API units (gAPI), dh = 12 in., mud weight =

12 lbm/gal, tool OD = 33⁄8 in., and the tool is centered.

Find: Corrected GR value.

Answer:

Enter the chart at 15.8 on the x-axis and move upward tointersect the 33⁄8-in. centered curve. The correspondingcorrection factor is 1.6.

1.6 × 36 gAPI = 58 gAPI.

10.0

7.0

5.0

3.0

2.0

1.0

0.7

0.5

0.3

Correction factor

t (g/cm2)

0 5 10 15 20 25 30 35 40

Scintillation Gamma Ray

33⁄8-in. tool, centered


33⁄8-in. tool, eccentered


GR

tW d dmud h sonde=

( )−

( )⎛

⎝⎜⎜

⎞

⎠⎟⎟8 345

2 54

2

2 54

2.

. .,

t =( )

−( )⎛

⎝⎜⎜

⎞

⎠⎟⎟

=128 345

2 54 12

2

2 54 3 375

215

.

. . ..88 2g cm/ .

© Schlumberger


PurposeThese charts are used to further correct the GR reading for variousborehole sizes.

DescriptionTwo components needed to complete correction of the GR readingare determined with these charts: barite mud factor (Bmud) andborehole function factor (Fbh).

Example Given: Borehole diameter = 6.0 in., tool OD = 33⁄8 in., the tool

is centered, mud weight = 12 lbm/gal, measured GR = 36 gAPI.

Find: Corrected GR value.

Answer: Enter the upper chart for Bmud versus mud weight at 12 lbm/gal on the x-axis. The intersection point with the33⁄8-in. centered curve is Bmud < 0.15 on the y-axis.

Determine (dh – dsonde) as 6 – 3.375 = 2.625 in. and enter

that value on the lower chart for Fbh versus (dh – dsonde) on the x-axis. Move upward to intersect the 33⁄8-in. curve, at which Fbh = 0.81.

Determine the new value of t using the equation fromChart GR-1:

The correction factor determined from Chart GR-1 is 0.95.

The complete correction factor is

(Chart GR-1 correction factor) × [1 + (Bmud × Fbh)]= 1.12 × [1 + (0.15 × 0.81)] = 1.26.

Corrected GR = 36 × 1.26 = 45.4 gAPI.


Scintillation Gamma Ray—33⁄8- and 111⁄16-in. ToolsGamma Ray Correction for Barite Mud in Various-Size Boreholes GR-2

(former GR-2)

26

1.2

1.0

0.8

0.6

0.4

0.2

0

Mud weight (lbm/gal)

7 8 9 10 11 12 13 14 15 16 17 18 19 20

1.2

1.0

0.8

0.6

0.4

0.2

0

Fbh

0 1 2 3 4 5 6 7 8 9 10

dh – dsonde (in.)

Bmud





33⁄8-in. tool

111⁄16-in. tool

GR

tW d d

mud h sonde=( )

−( )⎛

⎝⎜⎜

⎞

⎠⎟⎟8 345

2 54

2

2 54

2.

. .

=( )

−( )⎛

⎝⎜⎜

⎞

⎠⎟⎟

=128 345

2 54 6

2

2 54 3 375

24 8

.

. . .. /g ccm2.

© Schlumberger



Scintillation Gamma Ray—33⁄8- and 111⁄16-in. ToolsBorehole Correction for Cased Hole GR-3

(former GR-3)

27

PurposeThis chart is used to compensate for the effects of the casing,cement sheath, and borehole fluid on the GR count rate in casedholes for conditions of an eccentered 33⁄8-in. tool in an 8-in. boreholewith 10-lbm/gal mud.

DescriptionIn small boreholes the count rate can be too large, and in largerboreholes the count rate can be too small. The chart is based onopenhole Chart GR-1, modified by laboratory and Monte Carlo calculations to provide a correction factor for application to the measured GR count rate in cased hole environments:

ExampleGiven: GR = 19 gAPI, hole diameter (dh) = 12 in., casing OD

(dODcsg) = 95⁄8 in. and 43.5 lbm/ft, casing ID (dIDcsg) =8.755 in., casing density (ρcsg) = 7.96 g/cm3, tool OD(dsonde) = 33⁄8 in., cement density (ρcement) = 2.0 g/cm3,and mud weight (Wm) = 8.345 lbm/gal.

Find: Corrected cased hole GR value.

Answer: The chart input factor calculated with the equation ist = 21.7 g/cm2. Enter the chart at 21.7 on the x-axis. Atthe intersection point with the 33⁄8-in. curve, the value ofthe correction factor on the y-axis is 2.0. The GR value iscorrected by multiplying by the correction factor:

19 gAPI × 2.0 = 38 gAPI.

10.0

7.0

5.0

3.0

2.0

1.0

0.7

0.5

0.3

Correction factor

0 5 10 15 20 25 30 35 40

Scintillation Gamma Ray

33⁄8-in. tool

111⁄16-in. tool

t (g/cm2)

GR

© Schlumberger

tW

d d d dmIDcsg sonde csg ODcsg I= −( )+ −2 54

2 8 345.

.ρ DDcsg cement h ODcsgd d( )+ −( )⎡

⎣⎢

⎤

⎦⎥ρ .


PurposeThis chart is used to provide a correction factor for gamma ray values measured with the SlimPulse third-generation slim measure-ments-while-drilling (MWD) tool or the E-Pulse electromagnetictelemetry tool. These environmental corrections for mud weightand bit size are already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and moveupward to intersect the appropriate openhole size. Interpolatebetween lines as necessary. At the intersection point, move horizontally left to the y-axis to read the correction factor that the SlimPulse or E-Pulse gamma ray value was multiplied by toobtain the corrected gamma ray value in gAPI units.

Gamma Ray—LWD

SlimPulse* and E-Pulse* Gamma Ray ToolsBorehole Correction for Open Hole GR-6

28

11

10

9

8

7

6

5

4

3

2

1

0

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

6-in. bit7-in. bit

8.5-in. bit9.875-in. bit

12.25-in. bit

13.5-in. bit

17.5-in. bit

GR



Gamma Ray—LWD

ImPulse* Gamma Ray— 4.75-in. ToolBorehole Correction for Open Hole GR-7

29

PurposeThis chart is used to provide a correction factor for gamma ray values measured with the ImPulse integrated MWD platform. Theseenvironmental corrections for mud weight and bit size are alreadyapplied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and moveupward to intersect the appropriate bit size. Interpolate betweenlines as necessary. At the intersection point, move horizontally leftto the y-axis to read the correction factor that the ImPulse gammaray value was multiplied by to obtain the corrected gamma rayvalue in gAPI units.

1.75

1.50

1.25

1.00

0.75

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

8.5-in. bit

7-in. bit

6-in. bit

GR



PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the PowerPulse 6.75-in. MWD telemetry system andTeleScope 6.75-in. high-speed telemetry-while-drilling service.These environmental corrections for mud weight and bit size arealready applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the PowerPulse orTeleScope gamma ray value was multiplied by to obtain the cor-rected gamma ray value in gAPI units.

Gamma Ray—LWD

PowerPulse* and TeleScope* Gamma Ray—6.75-in. ToolsBorehole Correction for Open Hole GR-9

30

3.00

2.75

2.50

2.25

2.00

1.75

1.50

1.25

1.00

Correctionfactor


8 9 10 11 12 13 14 15 16 17 18 19

PowerPulse and TeleScope Gamma Ray


10.625-in. bit

9.875-in. bit

12.25-in. bit

GR



Gamma Ray—LWD

PowerPulse* Gamma Ray—8.25-in. Normal-Flow ToolBorehole Correction for Open Hole GR-10

31

PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the PowerPulse 8.25-in. normal-flow MWD telemetrysystem. These environmental corrections for mud weight and bitsize are already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to the y-axisto read the appropriate correction factor that the PowerPulse gammaray value was multiplied by to obtain the corrected GR value in gAPIunits.

5.00

4.75

4.50

4.25

4.00

3.75

3.50

3.25

3.00

2.75

2.50

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

9.875-in. bit

12.25-in. bit

13.5-in. bit

17.5-in. bit

10.625-in. bit

14.75-in. bit

GR



PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the PowerPulse 8.25-in. high-flow MWD telemetrysystem. These environmental corrections for mud weight and bitsize are already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to the y-axis to read the correction factor that the PowerPulse gamma rayvalue was multiplied by to obtain the corrected gamma ray value ingAPI units.

Gamma Ray—LWD

PowerPulse* Gamma Ray—8.25-in. High-Flow ToolBorehole Correction for Open Hole GR-11

32

4.25

4.00

3.75

3.50

3.25

3.00

2.75

2.50

2.25

2.00

1.75

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

17.5-in. bit

14.75-in. bit

13.5-in. bit

12.25-in. bit

10.625-in. bit

9.875-in. bit

GR



Gamma Ray—LWD

PowerPulse* Gamma Ray—9-in. ToolBorehole Correction for Open Hole GR-12

33

PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the PowerPulse 9-in. MWD telemetry system. Theseenvironmental corrections for mud weight and bit size are alreadyapplied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the PowerPulse gamma rayvalue was multiplied by to obtain the corrected gamma ray value ingAPI units.

7.50

7.00

6.50

6.00

5.50

5.00

4.50

4.00

3.50

3.00

2.50

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

17.5-in. bit

14.75-in. bit

13.5-in. bit

12.25-in. bit

10.625-in. bit

22-in. bit

GR



PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the PowerPulse 9.5-in. normal-flow MWD telemetrysystem. These environmental corrections for mud weight and bitsize are already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the PowerPulse gammma rayvalue was multiplied by to obtain the corrected gamma ray value ingAPI units.

Gamma Ray—LWD

PowerPulse* Gamma Ray—9.5-in. Normal-Flow ToolBorehole Correction for Open Hole GR-13

34

8.00

7.50

7.00

6.50

6.00

5.50

5.00

4.50

4.00

3.50

3.00

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

17.5-in. bit

14.75-in. bit

13.5-in. bit

12.25-in. bit

10.625-in. bit

22-in. bit

GR



Gamma Ray—LWD

PowerPulse* Gamma Ray—9.5-in. High-Flow ToolBorehole Correction for Open Hole GR-14

35

PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured by the PowerPulse 9.5-in. high-flow MWD telemetry sys-tem. These environmental corrections for mud weight and bit sizeare already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the PowerPulse gamma rayvalue was multiplied by to obtain the corrected gamma ray value ingAPI units.

8.00

7.50

7.00

6.50

6.00

5.50

5.00

4.50

4.00

3.50

3.00

2.50

2.00

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

10.625-in. bit

12.25-in. bit

13.5-in. bit

14.75-in. bit

17.5-in. bit

22-in. bitGR



PurposeThis chart is used to provide a correction factor for gamma ray values measured with the GVR resistivity sub of the geoVISION 63⁄4-in.MWD/LWD imaging system. These environmental corrections formud weight and bit size are already applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the GVR gamma ray value wasmultiplied by to obtain the corrected gamma ray value in gAPI units.

Gamma Ray—LWD

geoVISION675* GVR* Gamma Ray—6.75-in. ToolBorehole Correction for Open Hole GR-15

36

2.75

2.50

2.25

2.00

1.75

1.50

1.25

1.00

0.75

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19


9.875-in. bit

10.625-in. bit

12.25-in. bit

GR



Gamma Ray—LWD

RAB* Gamma Ray—8.25-in. ToolBorehole Correction for Open Hole GR-16

37

PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the RAB Resistivity-at-the-Bit 8.25-in. tool. These envi-ronmental corrections for mud weight and bit size are alreadyapplied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upward to intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the RAB gamma ray valuewas multiplied by to obtain the corrected gamma ray value in gAPIunits.

3.00

2.75

2.50

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

9.875-in. bit10.625-in. bit

12.25-in. bit

13.5-in. bit

14.75-in. bit

17.5-in. bit

GR



PurposeThis chart is used to provide a correction factor for gamma ray valuesmeasured with the arcVISION475 43⁄4-in. drill collar resistivity tool.These environmental corrections for mud weight and bit size arealready applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the correction factor that the arcVISION475 gammaray value was multiplied by to obtain the corrected gamma ray valuein gAPI units.

Gamma Ray—LWD

arcVISION475* Gamma Ray—4.75-in. ToolBorehole Correction for Open Hole GR-19

38

1.75

1.50

1.25

1.00

0.75

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

8.5-in. bit

7-in. bit

6-in. bit

GR



Gamma Ray—LWD


39


DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between linesas necessary. At the intersection point, move horizontally left tothe y-axis to read the appropriate correction factor that thearcVISION675 gamma ray value was multiplied by to obtainthe corrected gamma ray value in gAPI units.

3.50

3.25

3.00

2.75

2.50

2.25

1.75

2.00

1.50

1.25

1.00

0.75

0.50

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19


9.875-in. bit

10.625-in. bit

12.25-in. bit

GR




DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left tothe y-axis and read the appropriate correction factor that thearcVISION825 gamma ray value was multiplied by to obtain the corrected gamma ray value in gAPI units.

Gamma Ray—LWD


40

3.00

2.75

2.50

2.25

2.00

1.50

1.75

1.25

1.00

0.75

0.50

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

9.875-in. bit

10.625-in. bit

12.25-in. bit

13.5-in. bit

14.75-in. bit

17.5-in. bit

GR



Gamma Ray—LWD

arcVISION900* Gamma Ray—9-in. ToolBorehole Correction for Open Hole GR-22

41

PurposeThis chart is used to provide a correction factor for gamma ray values measured with the arcVISION900 9-in. drill collar resistivity tool.These environmental corrections for mud weight and bit size arealready applied to the gamma ray presented on the logs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left tothe y-axis and read the appropriate correction factor that thearcVISION900 gamma ray value was multiplied by to obtain the corrected gamma ray value in gAPI units.

5.5

5.0

4.5

4.0

3.5

2.5

3.0

2.0

1.5

1.0

0.5

Correction factor


8 9 10 11 12 13 14 15 16 17 18 19

10.625-in. bit12.25-in. bit

13.5-in. bit

14.75-in. bit

17.5-in. bit

22-in. bit

GR



PurposeThis chart is used to provide a correction that is subtracted from the borehole-corrected gamma ray from the arcVISION475 43⁄4-in.tool. Environmental corrections for mud weight and bit size arealready applied to the gamma ray presented on the logs.

DescriptionThis chart is for illustrative purposes only. The indicated correctionis already applied to the gamma ray log.

To determine the correction that was applied to the log output,enter the chart with the borehole size on the x-axis and move upwardto intersect the downhole mud weight. From the intersection pointmove horizontally left to read the correction in gAPI units that wassubtracted from the borehole-corrected data.

Charts GR-24 through GR-26 are similar to Chart GR-23 for different arcVISION tool sizes.

Gamma Ray—LWD

arcVISION475* Gamma Ray—4.75-in. ToolPotassium Correction for Open Hole GR-23

42

100

90

80

70

60

40

50

30

20

10

6 8 10 12 14 16 180

Correctionsubtracted for 5-wt% potassium

(gAPI)

Hole size (in.)

8.3 ppg

9 ppg10 ppg

12 ppg14 ppg

16 ppg18 ppg

20 ppg

GR



Gamma Ray—LWD


43


DescriptionThis chart is for illustrative purposes only. The indicated correctionis already applied on the gamma ray log.

To determine the correction that was applied to the log output,enter the chart with the borehole size on the x-axis and moveupward to intersect the downhole mud weight. From the intersectionpoint move horizontally left to read the correction in gAPI units thatwas subtracted from the borehole-corrected data.

50

45

40

35

30

20

25

15

10

5

0

Correctionsubtracted for 5-wt%potassium

(gAPI)

Hole size (in.)

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 13.012.5

9 ppg

8.3 ppg

10 ppg

12 ppg

14 ppg

16 ppg

18 ppg

20 ppg

GR





To determine the correction that was applied to the log output,enter the chart with the borehole size on the x-axis and move upwardto intersect the downhole mud weight. From the intersection pointmove horizontally left to read the correction in gAPI units that wassubtracted from the borehole-corrected data.

Gamma Ray—LWD


44

100

90

80

70

60

40

50

30

20

10

0

Correction subtracted for 5-wt%potassium

(gAPI)

Hole size (in.)

0 10 12 14 16 18 2220

10 ppg

9 ppg

8.3 ppg

12 ppg

14 ppg

16 ppg

18 ppg

20 ppg

GR



Gamma Ray—LWD

arcVISION900* Gamma Ray—9-in. toolPotassium Correction for Open Hole GR-26

45

PurposeThis chart is used to provide a correction that is subtracted from the borehole-corrected gamma ray from the arcVISION900 9-in. tool.Environmental corrections for mud weight and bit size are alreadyapplied to the gamma ray presented on the logs.


To determine the correction that was applied to the log output,enter the chart with the borehole size on the x-axis and move upwardto intersect the downhole mud weight. From the intersection pointmove horizontally left to read the correction curve in gAPI units thatwas subtracted from the borehole-corrected data.

120

100

80

60

40

20

0

Correction subtracted for 5-wt% potassium

(gAPI)

Hole size (in.)

109 1211 1413 15 1716 2018 19

10 ppg

9 ppg

8.3 ppg

12 ppg

14 ppg

16 ppg

18 ppg

20 ppg

GR



PurposeThis chart is used to provide a correction factor for gamma ray values measured with the EcoScope 6.75-in. Integrated LWD tool.These environmental corrections for mud weight and bit size arenormally already applied to the gamma ray presented on the fieldlogs.

DescriptionEnter the chart with the mud weight on the x-axis and move upwardto intersect the appropriate bit size. Interpolate between lines asnecessary. At the intersection point, move horizontally left to they-axis to read the appropriate correction factor that the EcoScope6.75-in. gamma ray value was multiplied by to obtain the correctedgamma ray value in gAPI units.

Gamma Ray—LWD

EcoScope* Integrated LWD Gamma Ray—6.75-in. ToolBorehole Correction for Open Hole GR-27

46

3.00

2.75

2.50

2.25

2.00

1.50

1.75

1.25

1.00

0.75

0.50

Correctionfactor


8 9 10 11 12 13 14 15 16 17 18 19

9.875-in. bit

10.625-in. bit

12.25-in. bit

8.5-in. bit

8.75-in. bit


GR


50

45

40

35

30

20

25

15

10

5

0

Correctionsubtracted for 5-wt%potassium

(gAPI)

Hole size (in.)

8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 13.012.5

9 ppg

8.3 ppg

10 ppg

12 ppg

14 ppg

16 ppg

18 ppg

20 ppg

Gamma Ray–Wireline

47

PurposeThis chart is used to illustrate the potassium correction that is sub-tracted from the borehole-corrected gamma ray from the EcoScope6.75-in. Integrated LWD tool. Environmental corrections for mudweight, bit size, and potassium are normally already applied to thegamma ray presented on the field logs.

DescriptionThis chart is for illustrative purposes only. The indicated correctionis already applied on the gamma ray log. The chart shows the correc-tion for a typical 5-wt% potassium concentration.

To determine the correction that was applied to the log output,enter the chart with the borehole size on the x-axis and move upwardto intersect the downhole mud weight. From the intersection pointmove horizontally left to read the correction curve in gAPI units thatwas subtracted from the borehole-corrected data.


GR

Gamma Ray—LWD

EcoScope* Integrated LWD Gamma Ray—6.75-in. ToolPotassium Correction for Open Hole GR-28


Spontaneous Potential—Wireline

48

SP

Rweq Determination from ESSP

PurposeThis chart and nomograph are used to calculate the equivalent for-mation water resistivity (Rweq) from the static spontaneous potential(ESSP) measured in clean formations. The value of Rweq is used inChart SP-2 to determine the resistivity of the formation water (Rw).Rw is used in Archie’s water saturation equation.

DescriptionEnter the chart with ESSP in millivolts on the x-axis and moveupward to intersect the appropriate temperature line. From theintersection point move horizontally to intersect the right y-axis forRmfeq/Rweq. From this point, draw a straight line through the equiva-lent mud filtrate resistivity (Rmfeq) point on the Rmfeq nomograph tointersect the value of Rweq on the far-right nomograph.

The spontaneous potential (SP) reading corrected for the effectof bed thickness (ESPcor) from Chart SP-4 can be substituted for ESSP.

ExampleFirst determine the value of Rmfeq:

■ If Rmf at 75°F is greater than 0.1 ohm-m, correct Rmf

to the formation temperature by using Chart Gen-6, and use Rmfeq = 0.85Rmf.

■ If Rmf at 75°F is less than 0.1 ohm-m, use Chart SP-2 to derive a value of Rmfeq at formation temperature.

Given: ESSP = –100 mV at 250°F and resistivity of the mud filtrate (Rmf) = 0.7 ohm-m at 100°F, converted to 0.33 at 250°F.

Find: Rweq at 250°F.

Answer: Rmfeq = 0.85Rmf = 0.85 × 0.33 = 0.28 ohm-m.

Draw a straight line from the point on the Rmfeq/Rweq linethat corresponds to the intersection of ESSP = –100 mVand the interpolated 250°F temperature curve throughthe value of 0.28 ohm-m on the Rmfeq line to the Rweq lineto determine that the value of Rweq is 0.025 ohm-m.

The value of Rmfeq/Rweq can also be determined from theequation

ESSP = Kc log (Rmfeq/Rweq),

where Kc is the electrochemical spontaneous potentialcoefficient:

Kc = 61 + (0.133 × Temp°F)

Kc = 65 + (0.24 × Temp°C).



49

SP

Rweq Determination from ESSPSP-1

(former SP-1)

0.01

0.02

0.040.06

0.1

0.2

0.4

0.6

1

2

4

6

10

20

40

60

100

0.001

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1.0

2.0

Rmfeq(ohm-m)

Rmfeq/Rweq

Rmf /Rw

Rweq(ohm-m)

+50 0 –50 –100 –150 –200

Static spontaneous potential, ESSP (mV)

250°C200°C150°C

100°C

50°C0°C

500°F400°F300°F

200°F

Formationtemperature

0.3

0.4

0.6

0.8

1

2

4

6

8

10

20

40

0.3

0.4

0.50.6

0.8

1

2

3

4

6

8

10

20

30

40

50

5

100°F

© Schlumberger


PurposeThis chart is used to convert equivalent water resistivity (Rweq) fromChart SP-1 to actual water resistivity (Rw). It can also be used to con-vert the mud filtrate resistivity (Rmf) to the equivalent mud filtrateresistivity (Rmfeq) in saline mud. The metric version of this chart isChart SP-3 on page 49.

DescriptionThe solid lines are used for predominantly NaCl waters. The dashedlines are approximations for “average” fresh formation waters (forwhich the effects of salts other than NaCl become significant).

The dashed lines can also be used for gypsum-base mud filtrates.

ExampleGiven: From Chart SP-1, Rweq = 0.025 ohm-m at 250°F in

predominantly NaCl water.

Find: Rw at 250°F.

Answer: Enter the chart at the Rweq value on the y-axis and movehorizontally right to intersect the solid 250°F line. Fromthe intersection point, move down to find the Rw valueon the x-axis. Rw = 0.03 ohm-m at 250°F.

Rweq versus Rw and Formation TemperatureSP-2

(customary, former SP-2)

0.005 0.01 0.02 0.03 0.05 0.1 0.2 0.3 0.5 1.0 2 3 4 5

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1.0

2.0

Rw or Rmf (ohm-m)

Rweq or Rmfeq

(ohm-m)

500°F400°F

300°F

200°F

150°F

100°F

75°F

Saturation

400°F300°F200°F150°F100°F75°F

500°F

NaCl at 75°F


50

SP

© Schlumberger


Spontaneous Potential—WirelineSpontaneous Potential—Wireline

51

SP

Rweq versus Rw and Formation TemperatureSP-3

(metric, former SP-2m)

PurposeThis chart is the metric version of Chart SP-2 for converting equiva-lent water resistivity (Rweq) from Chart SP-1 to actual water resistiv-ity (Rw). It can also be used to convert the mud filtrate resistivity (Rmf)to the equivalent mud filtrate resistivity (Rmfeq) in saline mud.

DescriptionThe solid lines are used for predominantly NaCl waters. The dashedlines are approximations for “average” fresh formation waters

(for which the effects of salts other than NaCl become significant).The dashed lines can also be used for gypsum-base mud filtrates.

ExampleGiven: From Chart SP-1, Rweq = 0.025 ohm-m at 121°C in

predominantly NaCl water.

Find: Rw at 121°C.

Answer: Rw = 0.03 ohm-m at 121°C.

0.005 0.01 0.02 0.03 0.05 0.1 0.2 0.3 0.5 1.0 2 3 4 5

0.001

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1.0

2.0

Rw or Rmf (ohm-m)

Rweq or Rmfeq

(ohm-m)

250°C200°C

150°C

100°C

75°C

50°C

25°C

Saturation

200°C150°C100°C75°C50°C25°C

250°C

NaCl at 25°C

© Schlumberger


Bed Thickness Correction—Open Hole


52

SP

PurposeChart SP-4 is used to correct the SP reading from the well log for the effect of bed thickness. Generally, water sands greater than 20 ft in thickness require no or only a small correction.

DescriptionChart SP-4 incorporates correction factors for a number of condi-tions that can affect the value of the SP in water sands.

The appropriate chart is selected on the basis of resistivity, inva-sion, hole diameter, and bed thickness. First, select the row of chartswith the most appropriate value of the ratio of the resistivity of shale(Rs) to the resistivity of mud (Rm). On that row, select a chart for noinvasion or for invasion for which the ratio of the diameter of invasion to the diameter of the wellbore (di/dh) is 5. Enter the x-axis with the value of the ratio of bed thickness to wellbore diameter (h/dh).Move upward to intersect the appropriate curve of the ratio of thetrue formation resistivity to the resistivity of the mud (Rt /Rm) forno invasion or the ratio of the resistivity of the flushed zone to theresistivity of the mud (Rxo /Rm) for invaded zones, interpolatingbetween the curves as necessary. Read the ratio of the SP read fromthe log to the corrected SP (ESP/ESPcor) on the y-axis for the point ofintersection. Calculate ESPcor = ESP/(ESP/ESPcor). The value of ESPcor

can be used in Chart SP-1 for ESSP.


Spontaneous Potential-Wireline

53

SP


Bed Thickness Correction—Open HoleSP-4

(former SP-3)

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

40 30 20 15 10 7.5 5

1.0

0.8

0.6

0.4

0.2

ESP/ESPcor

ESP/ESPcor

ESP/ESPcor

Rs

Rm= 1

Rs

Rm= 5

Rs

Rm= 20

Rxo = 0.2Rt Rxo = Rt

h/dh h/dh

h/dh h/dh h/dh

h/dh h/dh

Rxo = 5Rt

Invasion, di/dh = 5No Invasion

105 2

20

50

100

200

500

105 2

20

50

100

200

5001,000

10

5

21

20

50

100200500

10

52 1

20

50

100

200

5001,000

105 2

20

50

100

200

5001,000

10

5

210.5

20

50

100

200500

10

52

1

20

50

100

200

500

10

5

210.5

20

50

100

200

10

52 10.5

20

50

100

200Rxo/Rm Rxo/Rm Rxo/Rm

Rxo/Rm Rxo/Rm Rxo/Rm

Rxo/Rm Rxo/Rm Rxo/Rm

Rt/Rm

Rt/Rm

Rt/Rm

21

1

2

50

1020

5

0.5

0.2

0.1

100

10

20

50

100

200

5

10

5

2

1

0.5

0.2

20

50100200

h/dh h/dh

h/dh

h/dh h/dh

© Schlumberger


Bed Thickness Correction—Open Hole (Empirical)SP-5

(customary, former SP-4)

PurposeThis chart is used to provide an empirical correction to the SP for the effects of invasion and bed thickness. The correction was obtainedby averaging a series of thin-bed corrections in Reference 4. Theresulting value of static spontaneous potential (ESSP) can be used in Chart SP-1.

DescriptionThis chart considers bed thickness (h) as a variable, and the ratio ofthe resistivity of the invaded zone to the resistivity of the mud (Ri/Rm)and the diameter of invasion (di) as parameters of fixed value. Theborehole diameter is fixed at 8 in. and the tool size at 33⁄8 in.

To obtain the correction factor, enter the chart on the x-axis withthe value of h. Move upward to the appropriate di curve for the range of Ri/Rm. The correction factor on the y-axis corresponding to theintersection point is multiplied by the SP from the log to obtain thecorrected SP.


54

70 50 40 30 20 15 10 9 8 7 6 5 4 3

Bed thickness, h (ft)

ESSP

(%)Correction

factor

1.0

1.5

2.0

2.5

3.0

3.5

4.0

5.0

5

20

50

100

200

di (in.)

30

3535

4040

3030

3030

20

8-in. Hole; 33⁄8-in. Tool, Centered

Ri

Rm

100

90

80

70

60

50

40

30

20

SP

© Schlumberger


Spontaneous Potential—WirelineSpontaneous Potential—Wireline

55

SP

PurposeThis chart is the metric version of Chart SP-5 for providing an empir-ical correction to the SP for the effects of invasion and bed thick-ness. The correction was obtained by averaging a series of thin-bedcorrections in Reference 4. The resulting value of ESSP can be usedin Chart SP-1.

DescriptionThis chart considers bed thickness (h) as a variable, and Ri/Rm and di as parameters of fixed value. The borehole diameter is fixed at 203 mm and the tool size at 86 mm.

Bed Thickness Correction—Open Hole (Empirical)SP-6

(metric, former SP-4m)

0.5

200-mm Hole; 86-mm Tool, Centered

Bed thickness, h (m)

ESSP

(%)Correction

factor

100

90

80

70

60

50

40

30

20

1.0

20 15 10 5 3 2 1

1.5

2.020

5

50

100

200

2.5

3.0

3.54.0

5.0

di (m)

Ri

Rm

0.75

0.750.75

0.750.75

0.80.881.0

1.0

© Schlumberger


56

1 2 3

Quartz Dolomite Calcite

GasWater

4 5 0.5 0.4 0.3 0.2 0.1 06

Pe φtPorosity Effect on Pe

Matrix φφ t 100% H2O 100% CH4

Quartz0.00 1.81 1.810.35 1.54 1.76

Calcite0.00 5.08 5.080.35 4.23 4.96

Dolomite0.00 3.14 3.140.35 2.66 3.07

Specific — 1.00 0.10gravity

General

Porosity Effect on Photoelectric Cross SectionDens-1

PurposeThis chart and accompanying table illustrate the effect that porosity,matrix, formation water, and methane (CH4) have on the recordedphotoelectric cross section (Pe).

DescriptionThe table lists the data from which the chart was made. As theporosity increases the effect is greater for each mineral. Calcite hasthe largest effect in the presence of gas or water as the porosityincreases.

Enter the chart with the total porosity (φt) from the log and movedownward to intersect the angled line. From this point move to the left and intersect the line representing the appropriate matrixmaterial: quartz, dolomite, or calcite minerals. From this intersectionmove upward to read the correct Pe.

Density—Wireline, LWD

Dens

© Schlumberger


57

Dens

PurposeThis chart is used to determine the true bulk density (ρb) from the“apparent” recorded log value (ρlog).

DescriptionEnter the chart with the log density reading on the x-axis and moveupward to intersect the mineral line that best represents the forma-tion. At this point, move horizontally left to read the value to be addedto the log density. The individual mineral points reflect the log-deriveddensity and the correction factor to be added or subtracted from thelog value to obtain the true density of that mineral.

The long diagonal lines representing zero porosity at the lowerright and 40% porosity at the upper left are for dry gas in the forma-tion. The three points at the lower right of the diagonal lines rep-resent zero dry gas in the formation and are the endpoints for

sandstone, limestone, and dolomite with water in the pores. Thisshows that there is a slight correction for water-filled formationsfrom the log density value.

ExampleGiven: Log density = 2.40 g/cm3 in a sandstone formation

(dry gas).

Find: Corrected bulk density.

Answer: Enter the x-axis at 2.4 g/cm3 and move upward to inter-sect the sandstone line. The correction from the y-axis is0.02 g/cm3. The correction value is added to the log den-sity to obtain the true value of the bulk density:

2.40 + 0.02 = 2.42 g/cm3.

Density—Wireline, LWD

Apparent Log Density to True Bulk DensityDens-2

Magnesium

Dolomite

Sandstone + water

Low-pressure gasor air in pores

Sandstone

Sylvite (KCI)

Aluminum

Salt (NaCI)Add correction

from y-axis to ρlog

to obtain truebulk density, ρb

0.14

0.12

0.10

0.08

0.06

0.04

0.02

–0.02

–0.04

1 2 3

0

ρlog (g/cm3)

ρb – ρlog (g/cm3)

φ = 40%

φ = 0

φ = 40%

Limestone

AnthraciteCoalBituminous

Gypsum

Limestone + waterDolomite + water

© Schlumberger


58

Neu

Neutron—Wireline

Dual-Spacing Compensated Neutron Tool Charts

This section contains interpretation charts to cover developments incompensated neutron tool (CNT) porosity transforms, environmentalcorrections, and porosity and lithology determination.

CSU* software (versions CP-30 and later) and MAXIS* softwarecompute three thermal porosities: NPHI, TNPH, and NPOR.

NPHI is the “classic NPHI,” computed from instantaneous nearand far count rates, using “Mod-8” ratio-to-porosity transform with a caliper correction.

TNPH is computed from deadtime-corrected, depth- andresolution-matched count rates, using an improved ratio-to-porositytransform and performing a complete set of environmental correctionsin real time. These corrections may be turned on or off by the fieldengineer at the wellsite. For more information see Reference 32.

NPOR is computed from the near-detector count rate and TNPHto give an enhanced resolution porosity. The accuracy of NPOR isequivalent to the accuracy of TNPH if the environmental effects onthe near detector change less rapidly than the formation porosity.For more information on enhanced resolution processing, seeReference 35.

Cased hole CNT logs are recorded on NPHI, computed frominstantaneous near and far count rates, with a cased hole ratio-to-porosity transform.

Using the Neutron Correction ChartsFor logs labeled NPHI:1. Enter Chart Neu-5 with NPHI and caliper reading to convert to

uncorrected neutron porosity.

2. Enter Charts Neu-1 and Neu-3 to obtain corrections for eachenvironmental effect. Corrections are summed with the uncor-rected porosity to give a corrected value.

3. Use crossplot Charts Por-11 and Por-12 for porosity and lithologydetermination.

For logs labeled TNPH or NPOR, the CSU wellsite surface instru-mentation and MAXIS software have applied environmental correc-tions as indicated on the log heading. If the CSU and MAXISsoftware has applied all corrections, TNPH or NPOR can be useddirectly with the crossplot charts. In this case:

1. Use crossplot Charts Por-11 and Por-12 to determine porosityand lithology.



59

Neutron—Wireline

Neu

Compensated Neutron ToolEnvironmental Correction—Open Hole

PurposeChart Neu-1 is used to correct the compensated neutron log porosityindex if the caliper correction was not applied. If the caliper correc-tion is applied, it must be “backed out” to use this chart.

DescriptionThis chart is used only if the caliper correction was not applied to the logged data. The parameter section of the log heading listswhether correction was applied.

Example 1: Backed-Out Correction of TNPH PorosityGiven: Thermal neutron porosity (TNPH) from the log = 32 p.u.

(apparent limestone units) and borehole size = 12 in.

Find: Uncorrected TNPH with the correction backed out.

Answer: Enter the top chart for actual borehole size at the inter-section point of the standard conditions 8-in. horizontalline and 32 p.u. on the scale above the chart.

From this point, follow the closest trend line to intersectthe 12-in. line for the borehole size.

The intersection is the uncorrected TNPH value of 34 p.u.

To use the uncorrected value on Chart Neu-1, draw a ver-tical line from this intersection through the remainder ofthe charts, as shown by the red line.

Example 2: Environmentally Corrected THPHGiven: Neutron porosity of 32 p.u. (apparent limestone units),

without environmental correction, 12-in. borehole, 1⁄4-in.thick mudcake, 100,000-ppm borehole salinity, 11-lbm/galnatural mud weight (water-base mud [WBM]), 150°Fborehole temperature, 5,000-psi pressure (WBM), and100,000-ppm formation salinity.

Find: Environmentally corrected TNPH porosity.

Answer: If there is standoff (which is not uncommon), use ChartNeu-3. Then use Chart Neu-1 by drawing a vertical linethrough the charts for the previously determinedbacked-out (uncorrected) 34-p.u. neutron porosityvalue.

On each environmental correction chart, enter the y-axisat the given value and move horizontally left to intersectthe porosity value vertical line.

For example, on the mudcake thickness chart the lineextends from 1⁄4 in. on the y-axis.

At the intersection point, move parallel to the closestblue trend line to intersect the standard conditions, asindicated by the bullet.

The point of intersection with the standard conditionsfor the chart is the value of porosity corrected for theparticular environment. The change in porosity value(either positive or negative) is summed for the chartsand referred to as delta porosity (Δφ).

The Δφ net correction applied to the uncorrected log neutronporosity is listed in the table for the two examples.

CNT Neutron Porosity Correction Examples

Correction

Example 1 Example 2 Δφ

Log porosity 32 p.u.Borehole size 12 in. –2Mudcake thickness 1⁄4 in. 0Borehole salinity 100,000 ppm +1Mud weight 11 lbm/gal +2Borehole temperature 150°F +4Wellbore pressure 5,000 psi –1Formation salinity 100,000 ppm –3Standoff (from Chart Neu-3) 1 in. –4Net environmental correction –1Backed-out corrected porosity 34 p.u.Environmentally corrected porosity 33 p.u.Net correction –3Backed-out, environmentally corrected porosity 31 p.u.


Neutron—Wireline

Compensated Neutron ToolEnvironmental Correction—Open Hole Neu-1

(customary, former Por-14c)

60

0 10 20 30 40 50

0 10 20 30 40 50

• Standard conditions

Actual borehole size(in.)

1.0

0.5

0

Mudcake thickness(in.)

250

0

Borehole salinity(1,000 × ppm)

Mud weight(lbm/gal)

Natural

300

50

Borehole temperature(°F)

25

0

Pressure(1,000 × psi)

18161412108

Barite

Water-base mudOil-base mud

250

0

Limestoneformation salinity

(1,000 × ppm)

Neutron log porosity index (apparent limestone porosity in p.u.)

2420161284 •

•

•

•

•

•

•

•

1312111098

© Schlumberger

Neu


61

Neu

Neutron—Wireline

PurposeThis chart is the metric version of Chart Neu-1 for correcting thecompensated neutron tool porosity index.

Compensated Neutron ToolEnvironmental Correction—Open Hole Neu-2

(metric, former Por-14cm)

0 10 20 30 40 50

0 10 20 30 40 50

600500400300200100

Actual borehole size(mm)

25

12.5

0

Mudcake thickness(mm)

250

0

Borehole salinity(g/kg)

14912193663810

Borehole temperature(°C)

250

0

Limestoneformation salinity

(g/kg)

17213810369340

Pressure(MPa)

Water-base mudOil-base mud

1.5

1.0Mud density(g/cm3)

Nat

ural

2.0

1.0

Barit

e


Neutron log porosity index (apparent limestone porosity)

•

•

•

•

•

•

•

•

© Schlumberger


Neutron—Wireline

62

Neu

PurposeChart Neu-3 is used to determine the porosity change caused bystandoff to the uncorrected thermal neutron porosity TNPH fromChart Neu-1.

DescriptionEnter the appropriate borehole size chart at the estimated neutrontool standoff on the y-axis. Move horizontally to intersect the uncor-rected porosity. At the intersection point, move along the closesttrend line to the standard conditions line defined by the bullet to the right of the chart. This point is the porosity value corrected fortool standoff. The difference between the standoff-corrected porosityand the uncorrected porosity is the correction itself.

ExampleGiven: TNPH = 34 p.u., borehole size = 12 in., and

standoff = 0.5 in.

Find: Porosity corrected for standoff.

Answer: Draw a vertical line from the uncorrected neutron logporosity of 34 p.u. Enter the 12-in. borehole chart at 0.5-in. standoff and move horizontally right to intersectthe vertical porosity line. From the point of intersectionmove parallel to the closest trend line to intersect thestandard conditions line (standoff = 0 in.). The standoff-corrected porosity is 32 p.u. The correction is –2 p.u.

Compensated Neutron ToolStandoff Correction—Open Hole


63

Neu

Neutron—Wireline

Compensated Neutron ToolStandoff Correction—Open Hole Neu-3

(customary, former Por-14d)

0 10 20 30 40 50

0 10 20 30 40 50

10

9

8

7

6

5

4

3

2

1

0

7

6

5

4

3

2

1

0

4

3

2

1

0

3

2

1

0

2

1

0

1

0

Actual borehole size

6 in.

8 in.

10 in.

12 in.

18 in.

24 in.

Standoff (in.)


Neutron log porosity index (apparent limestone porosity in p.u.)

•

•

•

•

•

•

© Schlumberger


Neutron—Wireline

64

Neu

Compensated Neutron ToolStandoff Correction—Open Hole Neu-4

(metric, former Por-14dm)

0 10 20 30 40 50

0 10 20 30 40 50

250

225

200

175

150

125

100

75

50

25

0

175

150

125

100

75

50

25

0

100

75

50

25

0

75

50

25

0

50

25

0

25

0

Actual borehole size

150 mm

200 mm

250 mm

300 mm

450 mm

600 mm

Standoff (mm)


Neutron log porosity index (apparent limestone porosity)

•

•

•

•

•

•

PurposeThis chart is the metric version of Chart Neu-3 for determining theporosity change caused by standoff.

© Schlumberger


65

Neu

Neutron—Wireline

Compensated Neutron ToolConversion of NPHI to TNPH—Open Hole Neu-5

(former Por-14e)

PurposeThis chart is used to determine the porosity change caused by theborehole size to the neutron porosity NPHI and convert the porosityto thermal neutron porosity (TNPH). This chart corrects NPHI onlyfor the borehole sizes that differ from the standard condition of 8 in.Refer to Chart Neu-1 to complete the environmental corrections forthe TPNH value obtained.

DescriptionEnter the scale at the top of the chart with the NPHI porosity.

ExampleGiven: NPHI porosity = 12.5% and borehole size = 16 in.

Find: Porosity correction for nonstandard borehole size.

Answer: Enter the chart with the uncorrected porosity value of 12.5 at the scale at the top. Move down vertically to intersect the standard conditions line indicated by the bullet to the right. Enter the chart on the y-axis withthe actual borehole size at the zone of interest and movehorizontally right across the chart.

At the point of intersection of the vertical line and thestandard conditions line, move parallel to the closesttrend line to intersect the actual borehole size line.

At that intersection point move vertically down to thebottom scale to determine the TNPH porosity correctedonly for borehole size. This value is also used to deter-mine the change in porosity as a result of tool standoff.

TNPH = 12.5 + 5 = 17.5 p.u.

TNPH porosity index (apparent limestone porosity in p.u.)

2420161284

Borehole size(in.)

–5 0 10 20 30 40 50

0 10 20 30 40 50

NPHI porosity index (apparent limestone porosity in p.u.)

•


© Schlumberger


66

Neu

Neutron—Wireline

Compensated Neutron ToolFormation Σ Correction for Environmentally Corrected TNPH—Open Hole

PurposeThis chart is used to further correct the environmentally correctedTNPH porosity from Chart Neu-1 for the effect of the total forma-tion capture cross section, or sigma (Σ), of the formation of inter-est. This correction is applied after all environmental correctionsdetermined with Chart Neu-1 have been applied.

DescriptionEnter the chart with Σ for the appropriate formation along the y-axisand the corrected TNPH porosity along the x-axis. Where the linesdrawn from these points intersect, move parallel to the closest trendline to intersect the appropriate fresh- or saltwater line to read thecorrected porosity.

The chart at the bottom of the page is used to correct the Σ-corrected porosity for salt displacement if the formation Σ is due tosalinity. However, this correction is not made if the borehole salinitycorrection from Chart Neu-1 has been applied.

ExampleGiven: Corrected TNPH from Chart Neu-1 = 38 p.u., Σ of the

sandstone formation = 33 c.u., and formation salinity =150,000 ppm (indicating a freshwater formation).

Find: TNPH porosity corrected with Chart Neu-1 and for Σ ofthe formation.

Answer: Enter the appropriate chart with the Σ value on the y-axisand the corrected TNPH value on the x-axis. At the inter-section of the sigma and porosity lines, parallel the clos-est trend line to intersect the freshwater line. (If thewater in the formation is salty, the 250,000-ppm lineshould be used.)

Move straight down from the intersection point to theformation salinity chart at the bottom.

From the point where the straight line intersects the topof the salinity correction chart, parallel the closest trendline to intersect the formation salinity line.

Draw a vertical line to the bottom scale to read the cor-rected formation sigma TNPH porosity, which is 35 p.u.


67

Neu

0 10 20 30 40 50

0 10 20 30 40 50

0

100

250

70

60

50

40

30

20

10

0

70

60

50

40

30

20

10

0

Neutron log porosity index

Sandstone formationFormation Σ (c.u.)

Fresh water

250,000-ppm water

Limestone formationFormation Σ (c.u.)

Fresh water

250,000-ppm water

Dolomite formationFormation Σ (c.u.)

Formation salinity(1,000 × ppm)

Fresh water

250,000-ppm water

70

60

50

40

30

20

10

0

Neutron—Wireline

Compensated Neutron ToolFormation Σ Correction for Environmentally Corrected TNPH—Open Hole Neu-6

(former Por-16)

© Schlumberger


68

Neu

Neutron—Wireline

Compensated Neutron ToolMineral Σ Correction for Environmentally Corrected TNPH—Open Hole

PurposeThis chart is used to further correct the environmentally correctedTNPH porosity from Chart Neu-1 for the effect of the mineral sigma(Σ). This correction is applied after all environmental correctionsdetermined with Chart Neu-1 have been applied.

DescriptionEnter the chart for the formation type with the mineral Σ value alongthe y-axis and the Chart Neu-1 corrected TNPH porosity along the x-axis. Where lines drawn from these points intersect, move parallel tothe closest trend line to intersect the freshwater line to read thecorrected porosity on the scale at the bottom. The choice of chartdepends on the type of mineral in the formation.

ExampleGiven: Corrected TNPH from Chart Neu-1 = 38 p.u., sandstone

formation Σ = 35 c.u., and formation salinity = 150,000 ppm (indicating a freshwater formation).

Find: TNPH porosity corrected with Chart Neu-1 and for themineral Σ.

Answer: At the intersection of the Σ and porosity value linesmove parallel to the closest trend line to intersect thefreshwater line. Move straight down to intersect the bot-tom prosity scale to read the TNPH porosity correctedfor mineral Σ, which is 33 p.u.


69

Neu

Neutron—Wireline

Compensated Neutron ToolMineral Σ Correction for Environmentally Corrected TNPH—Open Hole

0 10 20 30 40 50

0 10 20 30 40 50


Sandstone formationMineral Σ (c.u.)

Fresh water

Fresh water

Fresh water

70

60

50

40

30

20

10

0

Limestone formationMineral Σ (c.u.)

70

60

50

40

30

20

10

0

Dolomite formationMineral Σ (c.u.)

70

60

50

40

30

20

10

0

Neu-7(former Por-17)

© Schlumberger


70

Neu

GeneralNeutron—Wireline

Compensated Neutron ToolFluid Σ Correction for Environmentally Corrected TNPH—Open Hole

PurposeThis chart is used to correct the environmentally corrected TNPHporosity from Chart Neu-1 for the effect of the fluid sigma (Σ) inthe formation. This correction is applied after all environmental corrections determined with Chart Neu-1 have been applied.

DescriptionEnter the appropriate formation chart with the formation fluid Σvalue on the y-axis and the Chart Neu-1 corrected TNPH porosity onthe x-axis. Where the lines drawn from these points intersect, moveparallel to the closest trend line to intersect the appropriate fresh-or saltwater line. If the borehole salinity correction from Chart Neu-1has not been applied, from this point extend a line down to intersectthe formation salinity chart at the bottom. Move parallel to theclosest trend line to intersect the formation salinity line. Movestraight down to read the corrected porosity on the scale below the chart.

ExampleGiven: Corrected TNPH from Chart Neu-1 = 30 p.u. (without

borehole salinity correction), fluid Σ = 80 c.u., fluidsalinity = 150,000 ppm, and sandstone formation.

Find: TNPH corrected with Chart Neu-1 and for fluid Σ.

Answer: At the intersection of the fluid Σ and Chart Neu-1 corrected TNPH porosity (30-p.u.) line, move parallel to the closest trend line to intersect the freshwater line.

From that point go straight down to the formation salinitycorrection chart at the bottom.

Move parallel to the closest trend line to intersect theformation salinity line (150,000 ppm), and then draw avertical line to the bottom scale to read the correctedTNPH value (26 p.u.).


71

Neu

0 10 20 30 40 50

0 10 20 30 40 50


Sandstone formationFluid Σ (c.u.)

Limestone formationFluid Σ (c.u.)

Dolomite formationFluid Σ (c.u.)

Formation salinity(1,000 × ppm)

160

140

120

100

80

60

40

20160

140

120

100

80

60

40

20160

140

120

100

80

60

40

200

250

Fresh water

250,000-ppm water

Fresh water

250,000-ppm water

Fresh water

250,000-ppm water

Neutron—Wireline

Compensated Neutron ToolFluid Σ Correction for Environmentally Corrected TNPH—Open Hole Neu-8

(former Por-18)

© Schlumberger


72

Neu

Neutron—Wireline

Compensated Neutron ToolEnvironmental Correction—Cased Hole

PurposeThis chart is used to obtain the correct porosity from the neutronporosity index logged with the compensated neutron tool in casing,where the effects of the borehole size, casing thickness, and cementsheath thickness influence the true value of formation porosity.

DescriptionEnter the scale at the top of the chart with a whole-number (notfractional) porosity value. Draw a straight line vertically through the three charts representing borehole size, casing thickness, andcement thickness. Draw a horizontal line on each chart from theappropriate value on the y-axis. At the intersection point of the verti-cal line and the horizontal line on each chart proceed to the bluedashed horizontal line by following the slope of the blue solid lineson each chart. At that point read the change in porosity index. Thecumulative change in porosity is added to the logged porosity to obtainthe corrected value. As can be seen, the major influences to the casing-derived porosity are the borehole size and the cement thickness. Thesame procedure applies to the metric chart.

The blue dashed lines represent the standard conditions fromwhich the charts were developed: 83⁄4-in. open hole, 51⁄2-in. 17-lbmcasing, and 1.62-in. annular cement thickness.

The neutron porosity equivalence nomographs at the bottom areused to convert from the log standard of limestone porosity to poros-ity for other matrix materials.

The porosity value corrected with Chart Neu-9 is entered intoChart Neu-1 to provide environmental corrections necessary fordetermining the correct cased hole porosity value.

ExampleGiven: Log porosity index = 27%, borehole diameter = 11 in.,

casing thickness = 0.304 in., and cement thickness =1.62 in.

Cement thickness is defined as the annular spacebetween the outside wall of the casing and the boreholewall. The value is determined by subtracting the casingoutside diameter from the borehole diameter and divid-ing by 2.

Find: Porosity corrected for borehole size, casing thickness,and cement thickness.

Answer: Draw a vertical line (shown in red) though the threecharts at 27 p.u.

Borehole-diameter correction chart: From the intersec-tion of the vertical line and the 11-in. borehole-diameterline (shown in red dashes) move upward along thecurved blue line as shown on the chart.

The porosity is reduced to 26% by –1 p.u.

Casing thickness chart: The porosity index is changed by 0.3 p.u.

Cement thickness chart: The porosity index is changedby 0.5 p.u.

The resulting corrected porosity for borehole, casing,and cement is 27 – 1 + 0.3 + 0.5 = 26.8 p.u.


73

Neu

Neutron—Wireline

Compensated Neutron ToolEnvironmental Correction—Cased Hole

0 10 20 30 40 50

468

101214160.2

0.3

0.4

0.5

0

1

2

3

+0.3

+0.5Borehole, casing, and cement correction = –1.0 + 0.3 + 0.5

–1.0

1.62 in.

0.304 in.

83⁄4 in.

Neutron log porosity index (p.u.)

Diameter of boreholebefore running casing

(in.)

Cement thickness(in.)

Casing thickness (in.)9.5

11.613.515.1

14172023

20

26

32

29

40

47

41⁄2 51⁄2 7 95⁄8OD (in.)

Casingweight(lbm/ft)

Customary

•

•

•

0 10 20 30 40 50

0 10 20 30 40 50

0 10 20 30 40 50

0 10 20 30 40 50

0 10 20 30

100

200

300

400579

1113

0

25

50

75

41 mm

7.7 mm

222 mm

Neutron log porosity index (p.u.)

Diameter of boreholebefore running casing

(mm)

Cement thickness(mm)

Casing thickness (mm)14172023

21.025.530.034.5

30

39

48

43

60

70

114 140 178 245OD (mm)

Casingweight(kg/m)

Metric


Calcite (limestone)

Quartz sandstone

Dolomite

Neutron porosity equivalence

•

•

•

Neu-9(former Por-14a)

© Schlumberger


74

Neu

Neutron—Wireline

APS* Accelerator Porosity SondeEnvironmental Correction—Open Hole

PurposeThe Neu-10 charts pair is used to correct the APS Accelerator PorositySonde apparent limestone porosity for mud weight and actual bore-hole size. The charts are for the near-to-array and near-to-far poros-ity measurements. The design of the APS sonde resulted in asignificant reduction in environmental correction. The answer deter-mined with this chart is used in conjunction with the correctionfrom Chart Neu-11.

DescriptionEnter the appropriate chart pair (mud weight and actual boreholesize) for the APS near-to-array apparent limestone porosity (APLU)or APS near-to-far apparent limestone porosity (FPLU) with theuncorrected porosity from the APS log by drawing a straight verticalline (shown in red) through both of the charts. At the intersectionwith the mud weight value, move parallel to the closest trend line tointersect the standard conditions line. This point represents a changein porosity resulting from the correction for mud weight. Follow thesame procedure for the borehole size chart to determine that correc-tion change. Because the borehole size correction has a dependencyon mud weight, even with natural muds, there are two sets of curveson the borehole size chart—solid for light muds (8.345 lbm/gal) anddashed for heavy muds (16 lbm/gal). Intermediate mud weights areinterpolated. The two differences are summed for the total correc-tion to the APS log value.

This answer is used in Chart Neu-11 to complete the environ-mental corrections for corrected APLU or FPLU porosity.

ExampleGiven: APS neutron APLU uncorrected porosity = 34 p.u.,

mud weight = 10 lbm/gal, and borehole size = 12 in.

Find: Corrected APLU porosity.

Answer: Draw a vertical line on the APLU mud weight chart from34 p.u. on the scale above. At the intersection with the10-lbm/gal mud weight line, move parallel to the trendline to intersect the standard conditions line. This pointrepresents a change in porosity of –0.75 p.u.

On the actual borehole size chart, move parallel to theclosest trend line from the intersection of the 34-p.u.line and the actual borehole size (12 in.) to intersect the 8-in. standard conditions line. This point represents a change in porosity of –1.0 p.u.

The total correction is –0.75 + –1.0 = –1.75 p.u., which results in a corrected APLU porosity of34 – 1.75 = 32.25 p.u.


75

Neu

Neutron—Wireline

APS near-to-far apparent limestone porosity uncorrected, FPLU (p.u.)

0 10 20 30 40 50


Actualborehole size

(in.)

18161412108

1614121086

2.01.81.61.41.21.0

400350300250200

(g/cm3)

(mm)

•

•

APS near-to-array apparent limestone porosity uncorrected, APLU (p.u.)

0 10 20 30 40 50

Mud weight(lbm/gal)

Actualborehole size

(in.)

18161412108

1614121086

2.01.81.61.41.21.0

400350300250200

(g/cm3)

(mm)

•

•


APS* Accelerator Porosity SondeEnvironmental Correction—Open Hole Neu-10

(former Por-23a)



76

Neu

Neutron—Wireline

PurposeThis chart is used to complete the environmental correction forAPLU and FPLU porosities from the APS log.

DescriptionEnter the left-hand chart on the x-axis with the temperature of theformation of interest. Move vertically to intersect the appropriateformation pressure line. From that point, move horizontally right tointersect the left edge of the formation salinity chart. Move parallelto the trend lines to intersect the formation salinity value. From thatpoint move horizontally to intersect the left edge of the formationporosity chart. Move parallel to the trend lines to intersect theuncorrected APLU or FPLU porosity. At that intersection, move horizontally right to read the apparent porosity correction.

ExampleGiven: APLU or FPLU porosity = 34 p.u., formation tempera-

ture = 150°F, formation pressure = 5,000 psi, and for-mation salinity = 150,000 ppm.

Find: Environmentally corrected APLU or FPLU porosity.

Answer: Enter the formation temperature chart at 150°F to inter-sect the 5,000-psi curve. From that point move horizon-tally right to intersect the left edge of the formationsalinity chart. Move parallel to the trend lines to inter-sect the formation temperature of 150°F. At this point,again move horizontally to the left edge of the nextchart. Move parallel to the trend lines to intersect the34-p.u. porosity line. At that point on the y-axis, thechange in porosity is +1.6 p.u.

The total correction for a corrected APLU or FPLU from Charts Neu-10 and Neu-11 is 34 + (–0.75 + –1) + 1.6 = 33.85 p.u.

50 100 150 200 250 300 350 10 38 66 93 121 149 177

50 150 250

Formation salinity(ppt or g/kg)

Formation porosity (p.u.)

50 30 10 0

Formation temperature

(°F) (°C)

1211109876543210

–1

Apparent porosity

correction(p.u.)

(psi) (MPa) 0 0 2,500 5,000 34 7,500 10,000 69 12,500 15,000 103 17,500 20,000 138

Pressure

APS* Accelerator Porosity Sonde Without Environmental Corrections Environmental Correction—Open Hole Neu-11

(former Por-23b)



77

Neu

Neutron—LWD

PurposeThis chart is used to determine one of several environmental corrections for neutron porosity values recorded with the CDNCompensated Density Neutron, adnVISION Azimuthal DensityNeutron, and EcoScope Integrated LWD tools. The value of hydrogenindex (Hm) is used in the following porosity correction charts.

DescriptionTo determine the Hm of the drilling mud, the mud weight, tempera-ture, and hydrostatic mud pressure at the zone of interest must be known.

ExampleGiven: Barite mud weight = 14 lbm/gal, mud temperature = 150°F,

and hydrostatic mud pressure = 5,000 psi.

Find: Hydrogen index of the drilling mud.

Answer: Enter the bottom chart for mud weight at 14 lbm/gal onthe y-axis. Move horizontally to intersect the barite line.

Move vertically to the bottom of the mud temperaturechart and move upward parallel to the closest trend lineto intersect the formation temperature. From the inter-section point move vertically to the bottom of the mudpressure chart.

Move parallel to the closest trend line to intersect theformation pressure. Draw a line vertically to intersectthe mud hydrogen index scale and read the result.

Mud hydrogen index = 0.78.

CDN* Compensated Density Neutron, adnVISION* Azimuthal Density Neutron, and EcoScope* Integrated LWD ToolsMud Hydrogen Index Determination



78

Neu

Neutron—LWD

CDN* Compensated Density Neutron, adnVISION* Azimuthal DensityNeutron, and EcoScope* Integrated LWD ToolsMud Hydrogen Index Determination

Neu-30(former Por-19)

0.70 0.75 0.80 0.85 0.90 0.95 1

0.70 0.75 0.80 0.85 0.90 0.95 1

25

20

10

0

Mudpressure

(1,000 × psi)

300

200

100

50

Mudtemperature

(°F)

16

14

12

10

8

Mudweight

(lbm/gal)

Mud hydrogen index, Hm

Barite

Bentonite



79

Neu

Neutron—LWD

PurposeThis is one of a series of charts used to correct adnVISION475 4.75-in. Azimuthal Density Neutron tool porosity for several environ-mental effects by using the mud hydrogen index (Hm) determinedfrom Chart Neu-30 in conjunction with the parameters on the chart.

DescriptionThis chart incorporates the parameters of borehole size, mud tem-perature, mud hydrogen index (from Chart Neu-30), mud salinity,and formation salinity for the correction of adnVISION475 porosity.

The following charts are used with the same interpretation procedure as Chart Neu-31. The charts differ for tool size and borehole size.

ExampleGiven: adnVISION475 uncorrected porosity = 34 p.u., borehole

size = 10 in., mud temperature = 150°F, hydrogen index = 0.78, borehole salinity = 100,000 ppm, and forma-tion salinity = 100,000 ppm.

Find: Corrected adnVISION475 porosity.

Answer: From the adnVISION475 porosity of 34 p.u. on the topscale, enter the borehole size chart to intersect the bore-hole size of 10 in. From the point of intersection moveparallel to the closest trend line to intersect the stan-dard conditions line.

From this intersection point move straight down to enter the mud temperature chart and intersect the mudtemperature of 150°F. From the point of intersectionmove parallel to the closest trend line to intersect thestandard conditions line.

Continue this pattern through the charts to read the corrected porosity from the scale at the bottom of thecharts.

The corrected adnVISION475 porosity is 17 p.u.

adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. BoreholeEnvironmental Correction—Open Hole



80

Neu

Neutron—LWD

adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 6-in. BoreholeEnvironmental Correction—Open Hole Neu-31

Boreholesize(in.)

0 10 20 30 40 50

Mudhydrogenindex, Hm

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


Mudtemperature

(°F)

•

•

•

•

•

6

8

10

100

0.7

0.8

0.9

1.0

200

300

0

100

200

adnVISION475 neutron porosity index (apparent limestone porosity) in 6-in. borehole

0

100

200



81

Neu

Neutron—LWD

adnVISION475* BIP Neutron—4.75-in. Tool and 6-in. BoreholeEnvironmental Correction—Open Hole Neu-32

0 10 20 30 40 50


0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)

Mudtemperature

(°F)


100

0.7

0.8

0.9

1.0

200

300

100

200

0

0

100

200

PurposeThis chart is used similarly to Chart Neu-31 to correctadnVISION475 borehole-invariant porosity (BIP) measurements.

DescriptionEnter the top scale with the BIP neutron porosity (BNPH) to incor-porate corrections for mud temperature, mud hydrogen index, andmud and formation salinity.



82

Neu

Neutron—LWD

adnVISION475* Azimuthal Density Neutron—4.75-in. Tool and 8-in. BoreholeEnvironmental Correction—Open Hole

Neu-33

Boreholesize(in.)

0 10 20 30 40 50


0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


Mudtemperature

(°F)

•

•

•

•

•

6

8

10

100

0.7

0.8

0.9

1.0

200

300

0

100

200


0

100

200

PurposeThis chart is used similarly to Chart Neu-31 to correctadnVISION475 porosity.



83

Neu

Neutron—LWD

adnVISION475* BIP Neutron—4.75-in. Tool and 8-in. BoreholeEnvironmental Correction—Open Hole Neu-34

0 10 20 30 40 50


0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)

Mudtemperature

(°F)


100

0.7

0.8

0.9

1.0

200

300

100

200

0

0

100

200




84

Neu

Neutron—LWD

250

200

100

0

Formationsalinity

(1,000 × ppm)

•

250

200

100

0

Mudsalinity

(1,000 × ppm)

•

300

200

100

50

Mudtemperature

(°F)

•

0.7

0.8

0.9

1.0


•


adnVISION675 neutron porosity index (apparent limestone porosity in p.u.)

0 10 20 30 40 50

0 10 20 30 40 50

16

14

12

10

8

Boreholesize(in.)

•


(former Por-26a)

PurposeThis chart is used similarly to Chart Neu-31 to correct adnVISION675porosity.



adnVISION675* BIP Neutron—6.75-in. Tool and 8-in. BoreholeEnvironmental Correction—Open Hole

0 10 20 30 40 50


0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)

Mudtemperature

(°F)


100

0.7

0.8

0.9

1.0

200

300

100

200

0

0

100

200


85

Neu

Neutron—LWD

Neu-36



86

Neu

Neutron—LWD


(former Por-26b)

250

200

100

0

Formationsalinity

(1,000 × ppm)

•

250

200

100

0

Mudsalinity

(1,000 × ppm)

•

300

200

100

50

Mudtemperature

(°F)

•

0.7

0.8

0.9

1.0


•

adnVISION675 neutron porosity index (apparent limestone porosity in p.u.)

0 10 20 30 40 50

0 10 20 30 40 50

16

14

12

10

8

Boreholesize(in.)

•


PurposeThis chart is used similarly to Chart Neu-31 to correct adnVISION675 porosity.



87

Neu

Neutron—LWD

adnVISION675* BIP Neutron—6.75-in. Tool and 10-in. BoreholeEnvironmental Correction—Open Hole

0 10 20 30 40 50


0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)

Mudtemperature

(°F)


100

0.7

0.8

0.9

1.0

200

300

100

200

0

0

100

200


Neu-38



Neu

Neutron—LWD

88

adnVISION825* Azimuthal Density Neutron—8.25-in. Tool and 12.25-in. BoreholeEnvironmental Correction—Open Hole

Neu-39

Standoff(in.)

0 10 20 30 40 50

Mudtemperature

(°F)


Pressure(1,000 × psi)

Boreholesize(°F)

1.5

0.5

0

1.0

12

10

300

200

100

14

16

1

0.7

0.8

0.9

adnVISION825 neutron porosity index (apparent limestone porosity) in 12.25-in. borehole

Standoff = 0.25 in.

0

10

20

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)

0

100

200

0

100

200


•

•

•

•

•

•

•

PurposeThis chart is used similarly to Chart Neu-31 to correct adnVISION825 porosity.



Neutron—LWD

89

Neu

CDN* Compensated Density Neutron and adnVISION825s* Azimuthal Density Neutron—8-in. Tool and 12-in. BoreholeEnvironmental Correction—Open Hole

Neu-40(former Por-24c)

18

16

14

12

Boreholesize(in.)

Neutron porosity index (apparent limestone porosity) in 12-in. borehole

0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

100

0

250

200

100

0

0.7

0.8

0.9

1.0


350300

200

10050

Mudtemperature

(°F)

PurposeThis chart is used similarly to Chart Neu-31 to correct CDN Compensated Density Neutron tool and adnVISION825sAzimuthal Density Neutron porosity.



90

Neu

Neutron—LWD


Neu-41(former Por-24d)

350

300

200

100

50

Mudtemperature

(°F)

18

16

14

12

Boreholesize(in.)


0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

100

0

250

200

100

0

A

B

C

G

H

I

J

K

0.7

0.8

0.9

1.0


D

E

F



91

Neu

Neutron—LWD


18

16

14

12

Boreholesize(in.)

0.7

0.8

0.9

1.0



0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

100

0

250

200

100

0

350

300

200

100

50

Mudtemperature

(°F)

Neu-42(former Por-24e)



PurposeCharts Neu-43 through Neu-46 show the environmental correctionsthat are applied to EcoScope 6.75-in. Integrated LWD Tool neutronporosity measurements. These charts can be used to estimate thecorrection that is normally already applied to the field logs.

DescriptionThe charts incorporate the parameters of borehole size, mud tem-perature, mud hydrogen index (from Chart Neu-30), mud salinity,and formation salinity for the correction of EcoScope 6.75-in. neutron porosity.

Select the appropriate chart based on both the hole size and the measurement type: thermal neutron porosity (TNPH) or bestthermal neutron porosity (BPHI).

Enter the charts with the uncorrected neutron porosity data.Charts Neu-43 and Neu-44 are for use with BPHI_UNC, and ChartsNeu-45 and Neu-46 are for use with TNPH_UNC. Because the bore-hole size correction is applied to the field logs, including the _UNCchannels, do not include the borehole size correction, which is in thecharts for illustrative purposes only.

A correction for eccentricity effects is normally also applied tothe field BPHI measurement. Because this correction is not includedin these charts, there may be a small difference between the correc-tion estimated from the charts and that actually applied to the fielddata, depending on the tool position in the borehole.

The charts are used with a similar procedure to that describedfor Chart Neu-31.

Neutron—LWD

EcoScope* Integrated LWD Neutron Porosity—6.75-in. ToolEnvironmental Correction—Open Hole

92

Neu


Neutron—LWD

EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 8.5-in. BoreholeEnvironmental Correction—Open Hole Neu-43

93

PurposeThis chart is used similarly to Chart Neu-31 to estimate the correc-tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermalneutron porosity (BPHI) measurements.

Use this chart only with EcoScope BPHI neutron porosity; useChart Neu-45 with EcoScope thermal neutron porosity (TNPH) measurements.

141312111098

Boreholesize(in.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00


EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole

0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

150

100

50

0

250

200

150

100

50

0

260

210

160

110

60

Temperature(°F)


Neu


PurposeThis chart is used similarly to Chart Neu-31 to estimate the correc-tion applied to EcoScope 6.75-in. Integrated LWD Tool best thermalneutron porosity (BPHI) measurements.

Use this chart only with EcoScope BPHI neutron porosity; useChart Neu-46 with EcoScope thermal neutron porosity (TNPH) measurements.

Neutron—LWD

EcoScope* Integrated LWD BPHI Porosity—6.75-in. Tool and 9.5-in. BoreholeEnvironmental Correction—Open Hole Neu-44

94

141312111098

Boreholesize(in.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00


EcoScope uncorrected BPHI porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole

0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

150

100

50

0

250

200

150

100

50

0

260

210

160

110

60

Temperature(°F)


Neu


Neutron—LWD

EcoScope* Integrated LWD TNPH Porosity—6.75-in. Tool and 8.5-in. BoreholeEnvironmental Correction—Open Hole Neu-45

95

PurposeThis chart is used similarly to Chart Neu-31 to estimate the correc-tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu-tron porosity (TNPH) measurements.

Use this chart only with EcoScope TNPH measurements. UseChart Neu-43 with EcoScope best thermal neutron porosity (BPHI)measurements.

141312111098

Boreholesize(in.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00


EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 8.5-in. borehole

0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

150

100

50

0

250

200

150

100

50

0

260

210

160

110

60

Temperature(°F)


Neu


PurposeThis chart is used similarly to Chart Neu-31 to estimate the correc-tion applied to EcoScope 6.75-in. Integrated LWD Tool thermal neu-tron porosity (TNPH) measurements.

Use this chart only with EcoScope TNPH neutron porosity; useChart Neu-44 with EcoScope best thermal neutron porosity (BPHI)measurements.

Neutron—LWD

EcoScope* Integrated LWD TNPH Porosity—6.75-in. Tool and 9.5-in. BoreholeEnvironmental Correction—Open Hole Neu-46

96

141312111098

Boreholesize(in.)

0.70

0.75

0.80

0.85

0.90

0.95

1.00


EcoScope uncorrected TNPH porosity (apparent limestone porosity in p.u.) in 9.5-in. borehole

0 10 20 30 40 50

0 10 20 30 40 50

Mudsalinity

(1,000 × ppm)

Formationsalinity

(1,000 × ppm)


•

•

•

•

•

250

200

150

100

50

0

250

200

150

100

50

0

260

210

160

110

60

Temperature(°F)


Neu


Neutron—LWD

EcoScope* Integrated LWD—6.75-in. ToolFormation Sigma Environmental Correction—Open Hole

97

PurposeThis chart is used to environmentally correct the raw sigma (RFSA)measurement for porosity, borehole size, and mud salinity. The fullycorrected sigma (SIFA) measurement is normally presented on thelogs.

DescriptionChart Neu-47 includes (from top to bottom) the moments sigmatransform, diffusion correction based on porosity, and borehole correction.

ExampleGiven: Raw sigma (24 c.u.), porosity (30 p.u.), borehole size

(10 in.), and mud salinity (200,000 ppm).Find: Corrected sigma (SIFA).Answer: Enter the chart from the scale at the top with the raw

sigma value of 24 c.u.

Moments Sigma TransformMove parallel to the closest trend line to intersect the x-axis of themoments sigma transform chart. The difference between the x-axisvalue and the raw sigma value is the moments sigma transform correction (19.8 – 24 = –4.2 c.u.).

Diffusion CorrectionMove down vertically from the scale at the top to intersect the30-p.u. line on the porosity chart. At the intersection point, moveparallel to the closest trend line to intersect the x-axis of the porosity chart.

The difference between the x-axis value and the raw sigma valueis the diffusion correction (25.3 – 24 = +1.3 c.u.).

Borehole CorrectionMove down vertically from the scale at the top to intersect the 10-in.borehole size line. At the intersection point, move parallel to theclosest trend line corresponding to the mud salinity to intersect the x-axis of the borehole correction chart.

The difference between the x-axis value and the raw sigma valueis the borehole correction (22.8 – 24 = –1.2 c.u.).

Net CorrectionThe net correction to apply to the raw sigma value is the sum thethree corrections (–4.2 + 1.3 + –1.2 = –4.1 c.u.). The environmentallycorrected sigma is the sum of the net correction and the raw sigmavalue (24 + –4.1 = 19.9 c.u.).

Neu

EcoScope Sigma Correction Example

Correction

Raw sigma 24 c.u.Porosity 30 p.u.Borehole size 10 in.Mud salinity 200,000 ppmMoments sigma transform –4.2 c.u.Porosity correction +1.3 c.u.Borehole correction –1.2 c.u.Net correction –4.1 c.u.Environmentally corrected sigma 19.9 c.u.



Neutron—LWD

EcoScope* Integrated LWD—6.75-in. ToolFormation Sigma Environmental Correction—Open Hole Neu-47

98

11

10

9

8

50

40

30

20

10

0


0 10 20 30 40 50 60

0 10 20 30 40 50 60

Mud salinity 0 ppm 50,000 ppm 100,000 ppm 150,000 ppm 200,000 ppm

Raw sigma (c.u.)

Momentssigma

transform

Porosity(p.u.)

Boreholesize (in.)


Neu


99

NMR

General


Nuclear Magnetic Resonance–—Wireline

CMR* ToolHydrocarbon Effect on NMR/Density Porosity Ratio CMR-1

PurposeThis chart is used to determine the saturation of the flushed zone(Sxo) and hydrocarbon density (ρh) by using density (ρ) and CMRCombinable Magnetic Resonance data.

DescriptionThe top chart has three components: ratio of total CMR porosity to density porosity (φtCMR/φD) on the y-axis, (1 – Sxo) values on the x-axis, and ρh defined by the radiating lines from the value of unityon the y-axis. Enter the chart with the values for (1 – Sxo) and theφtCMR/φD ratio. The intersection point indicates the hydrocarbon

density value. The bottom charts are used to determine the Sxo valuein sandstone (left) and limestone (right).

ExampleGiven: CMR porosity = 25 p.u., φD = 30 p.u., and Sxo = 80%.

Find: Hydrocarbon density of the fluid in the formation.

Answer: φtCMR/φD ratio = 25/30 = 0.83.

1 – Sxo = 1 – 0.8 = 0.20 or 20%.

For these values, ρh = 0.40.

1.0

1.0

0.80.7

0.6

0.5

0.4

0.3

0.2

0.1

0.8

0.4

0.4

0.2

0.20

0

0.6

0.6

1 – Sxo

1.4

1.6

1.8

2.0

0

10 p.u.

0

10 p.u.

20 p.u. 20 p.u.

Gas Gas30 p.u. 30 p.u.

40 p.u. 40 p.u.

0%20%

40%60%

80%

0%

20%40%

60%80%

Sxo = 100% Sxo = 100%

WaterWater

Porosity = 50 p.u. Porosity = 50 p.u.

2.2

2.4

2.6

0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0 0.05 0.10 0.15 0.20 0.25

φtCMR

0.30 0.35 0.40 0.45 0.50

1.4

1.6

1.8

2.0

2.2

2.4

2.6

ρb (g/cm3)

ρb (g/cm3)

ρma = 2.65, ρf = 1, If = 1, ρgas = 0.25, PT = 4, T1 gas = 4, IH = 0.5

Fresh Mud and Dry Gas at 700 psi Fresh Mud and Dry Gas at 700 psi

ρma = 2.71, ρf = 1, If = 1, ρgas = 0.25, PT = 4, T1 gas = 4, Igas = 0.5

φtCMRφD

φtCMR

ρh = 0.8



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Resistivity Laterolog—Wireline

101

ARI* Azimuthal Resistivity ImagerEnvironmental Correction—Open Hole RLl-1

(former Rcor-14)

PurposeThis chart is used to environmentally correct the ARI AzimuthalResistivity Imager high-resolution resistivity (LLhr) curve for theeffect of borehole size.

DescriptionFor a known value of resistivity of the borehole mud (Rm) at the zoneof interest, a correction for the recorded log azimuthal resistivity (Ra)is determined by using this chart. The resistivity measured by theARI tool is equal to or higher than the corrected resistivity (Rt) forborehole sizes of 8 to 12 in. However, the measured ARI resistivity is lower than Rt in 6-in. boreholes and for values of Ra/ Rm between 6 and 600.

ExampleGiven: ARI LLhr resistivity (Ra) = 20 ohm-m, mud resistivity

(Rm) = 0.02 ohm-m, and borehole size at the zone ofinterest = 10 in.

Find: True resistivity (Rt).

Answer: Enter the chart at the x-axis with the ratio Ra/Rm =20/0.02 = 1,000.

Move vertically upward to intersect the 10-in. line. Movehorizontally left to read the Rt/Ra value on the y-axis of 0.86.

Multiply the ratio by Ra to obtain the corrected LLhr

resistivity: Rt = 0.86 × 20 = 17.2 ohm-m.

1 10 100 1,000 10,000

1.5

1.0

0.5

Ra/Rm

Rt/Ra

35⁄8-in. Tool Centered, Active Mode, Thick Beds

68

1012

Hole diameter (in.)

RLl*Mark of Schlumberger© Schlumberger



RLl

102

PurposeThis chart is used to correct the HALS laterolog deep resistivity(HLLD) for borehole and drilling mud effects.

DescriptionEnter the chart on the x-axis with the value of HLLD divided by the mud resistivity (Rm) at formation temperature. Move upward to intersect the curve representing the borehole diameter (dh), andthen move horizontally left to read the value of the ratio Rt/HLLD onthe y-axis. Multiply this value by the HLLD value to obtain Rt. Charts

RLl-3 through RLl-14 are similar to Chart RLl-2 for different resistivitymeasurements and values of tool standoff.

ExampleGiven: HLLD = 100 ohm-m, Rm = 0.02 ohm-m at formation

temperature, and borehole size = 10 in.

Find: Rt.

Answer: Ratio of HLLD/Rm = 100/0.02 = 5,000.

Rt = 0.80 × 100 = 80 ohm-m.

High-Resolution Azimuthal Laterolog Sonde (HALS)HLLD Borehole Correction—Open Hole RLl-2

10–1 100 101 102 103 104 1050.6

0.7

0.8

0.9

1.0

1.1

1.2

HLLD/Rm

R t /HLLD

HLLD Tool Centered (Rm = 0.1 ohm-m)

100 101 102 103 104 1050.5

0.7

0.9

1.1

1.3

1.5

HLLD/Rm

R t /HLLD

Borehole Effect, HLLD Tool Centered (Rm = 0.1 ohm-m)

dh

5 in.6 in.8 in.10 in.12 in.14 in.16 in.

dh6 in.8 in.10 in.12 in.14 in.16 in.18 in.20 in.

© Schlumberger


103

RLl


High-Resolution Azimuthal Laterolog Sonde (HALS)HLLS Borehole Correction—Open Hole RLl-3

PurposeThis chart is used similarly to Chart RLl-2 to correct HALS laterologshallow resistivity (HLLS) for borehole and drilling mud effects.

Borehole Effect, HLLS Tool Centered (Rm = 0.1 ohm-m)


10–1 100 101 102 103 104 105 0

0.5

1.0

1.5

2.0

2.5

3.0

HLLS/Rm

Rt /HLLS

HLLS Tool Centered (Rm = 0.1 ohm-m)

100 101 102 103 104 105 0

1.0

0.5

1.5

2.0

2.5

3.0

HLLS/Rm

Rt/HLLS

dh5 in.6 in.8 in.10 in.12 in.14 in.16 in.

© Schlumberger



104

RLl

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALShigh-resolution deep resistivity (HRLD) for borehole and drillingmud effects.

High-Resolution Azimuthal Laterolog Sonde (HALS)HRLD Borehole Correction—Open Hole RLl-4

HRLD Tool Centered (R m = 0.1 ohm-m)

dh5 in. 6 in.8 in.10 in. 12 in.14 in.16 in.

100 101 102 103 104 105

Borehole Effect, HRLD Tool Centered (Rm = 0.1 ohm-m)

10–1 100 101 102 103 104 1050.4

0.5

0.6

0.7

0.8

1.0

0.9

1.1

R t/HRLD

HRLD/Rm

0.4

0.6

0.8

1.0

1.2

1.4

HRLD/Rm

Rt/HRLD


© Schlumberger


105

RLl


High-Resolution Azimuthal Laterolog Sonde (HALS)HRLS Borehole Correction—Open Hole RLl-5

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALShigh-resolution shallow resistivity (HRLS) for borehole and drillingmud effects.

HRLS Tool Centered (Rm = 0.1 ohm-m)

dh5 in. 6 in. 8 in.10 in.12 in. 14 in.16 in.

HRLS/Rm

Borehole Effect, HRLS Tool Centered (Rm = 0.1 ohm-m)

10–1 100 101 102 103 104 105 0

0.5

1.0

1.5

2.0

2.5

3.0

HRLS/Rm

R t /HRLS

100 101 102 103 104 105 0

1.0

0.5

1.5

2.0

2.5

3.0

Rt/HRLS

dh6 in.8 in. 10 in.12 in. 14 in.16 in. 18 in. 20 in.

© Schlumberger



106

RLl

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALS laterolog deep resistivity (HLLD) for borehole and drilling mud effectsat 0.5- and 1.5-in. standoffs.

High-Resolution Azimuthal Laterolog Sonde (HALS)HLLD Borehole Correction—Eccentered in Open Hole RLl-6

dh5 in.6 in.8 in. 10 in.12 in.14 in. 16 in.

HLLD Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)

HLLD Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)

10–1 100 101 102 103 104 1050.6

0.8

0.7

0.9

1.0

1.1

1.2

Rt/HLLD

10–1 100 101 102 103 104 1050.6

0.7

0.8

0.9

1.0

1.1

1.2

HLLD/Rm

HLLD/Rm

Rt/HLLD

dh8 in. 10 in.12 in.14 in. 16 in.

© Schlumberger


107

RLl


High-Resolution Azimuthal Laterolog Sonde (HALS)HLLS Borehole Correction—Eccentered in Open Hole RLl-7

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALS laterolog shallow resistivity (HLLS) for borehole and drilling mud effects at 0.5- and 1.5-in. standoffs.

0

0.5

1.0

1.5

2.0

2.5

3.0

Rt/HLLS

0

0.5

1.0

1.5

2.0

2.5

3.0

Rt/HLLS

10–1 100 101 102 103 104 105

10–1 100 101 102 103 104 105

HLLS/Rm

HLLS/Rm

dh5 in.6 in.8 in.10 in.12 in.14 in.16 in.

HLLS Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)

dh8 in.10 in.12 in.14 in.16 in.

HLLS Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)

© Schlumberger



108

RLl

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALShigh-resolution deep resistivity (HRLD) for borehole and drillingmud effects at 0.5- and 1.5-in. standoffs.

High-Resolution Azimuthal Laterolog Sonde (HALS)HRLD Borehole Correction—Eccentered in Open Hole RLl-8

dh5 in. 6 in. 8 in.10 in. 12 in.14 in.16 in.

HRLD Tool Eccentered at Standoff = 0.5 in. (Rm = 0.1 ohm-m)

10–1 100 101 102 103 104 105

0.4

0.6

0.5

0.7

0.9

0.8

1.0

1.1

HRLD/Rm

Rt/HRLD

10–1 100 101 102 103 104 1050.4

0.6

0.5

0.7

0.8

0.9

1.0

1.1

HRLD/Rm

Rt/HRLD

dh8 in. 10 in.12 in.14 in.16 in.

HRLD Tool Eccentered at Standoff = 1.5 in. (Rm = 0.1 ohm-m)

© Schlumberger


109

RLl


High-Resolution Azimuthal Laterolog Sonde (HALS)HRLS Borehole Correction—Eccentered in Open Hole RLl-9

0

0.5

1.0

1.5

2.0

2.5

3.0

Rt/HRLS

10–1 100 101 102 103 104 105

HRLS/Rm

0

1.0

0.5

1.5

2.0

2.5

3.0

Rt/HRLS

10–1 100 101 102 103 104 105

HRLS/Rm

HRLS Tool Eccentered Standoff = 0.5 in. (Rm = 0.1 ohm-m)

HRLS Tool Eccentered Standoff = 1.5 in. (Rm = 0.1 ohm-m)

dh5 in.6 in.8 in. 10 in.12 in.14 in. 16 in.

dh8 in. 10 in.12 in.14 in. 16 in.

PurposeThis chart is used to similarly to Chart RLl-2 to correct the HALShigh-resolution shallow resistivity (HRLS) for borehole and drillingmud effects at 0.5- and 1.5-in. standoffs.

© Schlumberger



110

RLl

PurposeThis chart is used to similarly to Chart RLl-2 to correct HRLA High-Resolution Laterolog Array resistivity for borehole and drilling mud

effects. RLA1 is the apparent resistivity from computed focusingmode 1.

HRLA* High-Resolution Laterolog ArrayBorehole Correction—Open Hole RLl-10

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA1

Tool Centered

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA1

Standoff = 1.5 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA1

Standoff = 0.5 in.

dh5 in.6 in.8 in.9 in.10 in.12 in.14 in.16 in.18 in.20 in.22 in.

RLA1/Rm

RLA1/Rm

RLA1/Rm



111

RLl

GeneralResistivity Laterolog—Wireline


dh5 in.6 in.8 in.9 in.10 in.12 in.14 in.16 in.18 in.20 in.22 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA2

Tool Centered

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA2

Standoff = 1.5 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA2

Standoff = 0.5 in.

RLA2/Rm

RLA2/Rm

RLA2/Rm






RLl

112


dh 5 in.6 in.8 in.9 in.10 in.12 in.14 in.16 in.18 in.20 in.22 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA3

Tool Centered

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA3

Standoff = 1.5 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA3

Standoff = 0.5 in.

RLA3/Rm

RLA3/Rm

RLA3/Rm





113

RLl




10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA4

Tool Centered

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA4

Standoff = 1.5 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA4

Standoff = 0.5 in.

RLA4/Rm

RLA4/Rm

RLA4/Rm






114

RLl



10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA5

Tool Centered

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA5

Standoff = 1.5 in.

10–1 100 101 102 103 104 105 106

2.0

2.5

3.0

1.5

1.0

0.5

0

Rt/RLA5

Standoff = 0.5 in.

RLA5/Rm

RLA5/Rm

RLA5/Rm





115

RLl

Resistivity Laterolog—LWD

GeoSteering* Bit Resistivity—6.75-in. ToolBorehole Correction—Open Hole RLl-20

PurposeThis chart is used to derive the borehole correction for the GeoSteeringbit-measured resistivity. The bit resistivity corrected to the trueresistivity (Rt) is then used in the calculation of water saturation.

DescriptionEnter the chart on the x-axis with the ratio of the bit resistivity andmud resistivity (Ra/Rm) at formation temperature. Move upward to

intersect the appropriate bit size. Move horizontally left to intersectthe correction factor on the y-axis. Multiply the correction factor bythe Ra value to obtain Rt. Charts RLl-21, RLl-23, and RLl-24 are simi-lar to Chart RLl-20 for different tools and bit sizes.

Chart RLl-22 differs in that it is for reaming-down mode asopposed to drilling mode.

0

0.5

0.7

0.8

0.9

1.1

1.2

1.0

10–2 10–1 100 101 102 103 104 105

Ra/Rm

Ra/Rm

24-in. bit18-in. bit12-in. bit

0.5

0.6

0.7

0.8

0.9

1.2

1.0

1.1

10–2 10–1 100 101 102 103 104 105

Rt/Ra

Rt/Ra




Resistivity Galvanic—DrillpipeResistivity Laterolog–LWD

116

RLl

GeoSteering* arcVISION675* Resistivity—6.75-in. ToolBorehole Correction—Open Hole RLl-21

10–2 10–1 100 101 102 103 104 105

Ra/Rm

0

0.5

0.7

0.8

0.9

1.1

1.2

1.0

0.5

0.6

0.7

0.8

0.9

1.2

1.0

1.1

10–2 10–1 100 101 102 103 104 105

Rt/Ra

Rt/Ra

Ra/Rm



PurposeThis chart is used similarly to Chart RLl-20 to derive the boreholecorrection for the GeoSteering bit-measured arcVISION675 resistivity.



117

RLl


GeoSteering* Bit Resistivity in Reaming Mode—6.75-in. ToolBorehole Correction—Open Hole RLl-22

PurposeThis chart is used similarly to Chart RLl-20 to derive the boreholecorrection for the GeoSteering bit-measured resistivity while ream-ing down.

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

10–2 10–1 100 101 102 103 104 105

Rt/Ra

Ra/Rm

arcVISION* tool

Bit




118

RLl

geoVISION* Resistivity Sub—6.75-in. ToolBorehole Correction—Open Hole RLl-23

2

1

Rt/Ra

100 101 102 103 104 105

Ra/Rm

Ring Resistivity (with 81⁄2-in. bit)2

1

Rt/Ra

100 101 102 103 104 105

Ra/Rm

Deep Button Resistivity (with 81⁄2-in. bit)

2

1

Rt/Ra

100 101 102 103 104 105

Ra/Rm Ra/Rm

Ra/Rm Ra/Rm

Medium Button Resistivity (with 81⁄2-in. bit)2

1

Rt/Ra

100 101 102 103 104 105

Shallow Button Resistivity (with 81⁄2-in. bit)

1

2

Rt/Ra

100 101 102 103 104 105

Bit Resistivity (with 81⁄2-in. bit) ROP to Bit Face = 4 ft 2

1

Rt/Ra

100 101 102 103 104 105

Bit Resistivity (with 81⁄2-in. bit) ROP to Bit Face = 35 ft

Borehole diameter (in.)

12

16

18

15

8.510

14

13

8.510

11

12

13

14

15

Borehole diameter (in.)

8.59.5

10.5

11

12

13

10

9.5

9.25

98.5

8.510

1214

16

18

2022

8.51012

1416

18

2022

Borehole diameter (in.)Borehole diameter (in.)

Borehole diameter (in.) Borehole diameter (in.)

PurposeThis chart is used similarly to Chart RLl-20 to derive the boreholecorrection for the bit-measured resistivity from the GVR* resistivity

sub of the geoVISION 6.75-in. tool. The bottom row of charts specifies the bit readout point (ROP) to the bit face.



119

RLl


geoVISION* Resistivity Sub—8.25-in. ToolBorehole Correction—Open Hole RLl-24

2

1

Rt/Ra

100 100

100 100

100 100

101 102 103 104 105

Ra/Rm

Ring Resistivity (with 121⁄4-in. bit)2

1

Rt /Ra

101 102 103 104 105

Ra/Rm

Deep Button Resistivity (with 121⁄4-in. bit)

2

1

Rt/Ra

101 102 103 104 105

Ra/Rm

Medium Button Resistivity (with 121⁄4-in. bit)2

1

Rt/Ra

101 102 103 104 105

Ra/Rm

Shallow Button Resistivity (with 121⁄4-in. bit)

1

2

Rt/Ra

101 102 103 104 105

Ra/Rm

Bit Resistivity (with 121⁄4-in. bit) ROP to Bit Face = 4 ft 2

1

Rt/Ra

101 102 103 104 105

Ra/Rm

Bit Resistivity (with 121⁄4-in. bit) ROP to Bit Face = 35 ft

22

12.2516

17

18

19

20

12.2514

15

16

1718

2019

12.2513.5

14

15

1617

12.25

12.75

13

13.5

14

12.2514

1618

20

2224

26

12.25141618

2022

2426




PurposeThis chart is used similarly to Chart RLl-20 to derive the boreholecorrection for the bit-measured resistivity from the GVR* resistivity

sub of the geoVISION 8.25-in. tool. The bottom row of chartsspecifies the bit readout point (ROP) to the bit face.



Resistivity Laterlog—LWD

120

RLl

GeoSteering* Bit Resistivity—6.75-in. ToolDistance Out of Formation—Open Hole RLl-25

10 ohm-m/4° BUR

100 ohm-m/4° BUR

10 ohm-m/5° BUR

100 ohm-m/5° BUR

10 ohm-m/10° BUR

600

500

400

300

200

100

0 0 2 4 6 8 10 12

Dip angle (°)

Distance (ft)

PurposeThis chart is used to calculate the distance the GeoSteering bit musttravel to return to the target formation.

DescriptionWhen drilling is at very high angles from vertical, the bit may wanderout of formation. If this occurs, how far the bit must travel to getback into the formation must be determined.

Enter the chart with the known dip angle of the formation on the x-axis. Move upward to intersect the appropriate “buildup rate”(BUR) curve. Move horizontally left from the intersection point tothe y-axis and read the distance back into the formation.

ExampleGiven: Formation dip angle = 6°, formation resistivity during

drilling = 10 ohm-m, and buildup rate = 4°.

Find: Distance to return to the target formation.

Answer: Enter the chart at 6° on the x-axis. Move upward to the10 ohm-m/4° BUR curve. Move horizontally left to the y-axis to read approximately 290 ft.



121

RLl

GeneralResistivity Laterolog—Wireline

CHFR* Cased Hole Formation Resistivity ToolCement Correction—Cased Hole

RLl-50

PurposeThis chart is used to correct the raw cased hole resistivity measure-ment of the CHFR Cased Hole Formation Resistivity tool (Rchfr) forthe thickness of the cement sheath. The resulting value of true resis-tivity (Rt) is used to calculate the water saturation.

DescriptionEnter the chart on the x-axis with the ratio of Rchfr and the resistivityof the cement sheath (Rcem). The value of Rcem is obtained with labo-ratory measurements. Move upward to the appropriate cementsheath thickness curve, which represents the annular space betweenthe outside of the casing and the borehole wall. Move horizontallyleft to the y-axis and read the Rt/Rchfr value. Multiply this value byRchfr to obtain Rt.

Charts RLl-51 and RLl-52 are for making the correction in largercasing sizes.

No cement

0.5 in.

0.75 in.

1.5 in.

3 in.

5 in.

0

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.0

CHFR Cement Correction Chart (4.5-in.-OD casing)

10–2 10–1 100

Rchfr /Rcem

Rt /Rchfr

101 102



General

122

RLl


0

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.0

CHFR Cement Correction Chart (7-in.-OD casing)

10–2 10–1 100

Rchfr/Rcem

Rt /Rchfr

101 102

No cement

0.5 in.

0.75 in.

1.5 in.

3 in.

5 in.

CHFR* Cased Hole Formation Resistivity ToolCement Correction—Cased Hole RLl-51

PurposeThis chart is used similarly to Chart RLl-50 to obtain the cased holeresistivity of the CHFR Cased Hole Formation Resistivity tool cor-rected for the thickness of the cement sheath in 7-in.-OD casing.



123

RLl


CHFR* Cased Hole Formation Resistivity ToolCement Correction—Cased Hole RLl-52

No cement

0.5 in.

0.75 in.

1.5 in.

3 in.

5 in.

0

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.0

CHFR Cement Correction Chart (9.625-in.-OD casing)

10–2 10–1 100

Rchfr/Rcem

Rt/Rchfr

101 102

PurposeThis chart is used similarly to Chart RLl-50 to obtain the cased holeresistivity of the CHFR Cased Hole Formation Resistivity tool cor-rected for the thickness of the cement sheath in 9.625-in.-OD casing.



Resistivity Galvanic—WirelineResistivity Induction—Wireline

124

RInd

AIT* Array Induction Imager ToolOperating Range—Open Hole

PurposeThis chart is used to determine the limit of application for the AITArray Induction Imager Tool measurement in a salt-saturated borehole.

DescriptionWhen the AIT tool logs a large salt-saturated borehole, the 10- and20-in. induction curves may well be unusable because of the largeconductive borehole. In a borehole with a diameter (dh) of 8 in., the 10- and 20-in. curve data are usable if Rt < 300Rm. The ratio of the true resistivity to the mud resistivity (Rt /Rm) is proportional to (dh/8)2.

A general rule is that a 12-in. borehole must have a ratio of Rt/Rm

≤ 133 to have usable shallow log data. Additional requirements arethat the borehole must be round and the AIT tool standoff is 2.5 in.The value of Rt/Rm is further reduced if the borehole is irregular orthe standoff requirement is not met.

Chart RInd-1 summarizes these requirements. The expected values of Rt, Rm, borehole size, and standoff size are entered to accurately determine the usable resolution in a smooth hole. Thelower chart summarizes which AIT resistivity tools typically providethe most accurate deep resistivity data.

Example: Salt-Saturated BoreholeGiven: Borehole size = 10 in., Rt = 5 ohm-m, Rm =

0.0135 ohm-m, and standoff (so) = 2.5 in.

Find: Which, if any, of the AIT curves are valid.

Answer: From the x-axis equation:

Enter the chart on the x-axis at 346 and move upward to intersect Rt = 5 ohm-m on the y-axis. The intersectionpoint is in an error zone for which the shallow inductioncurves are not valid even in a round borehole. Thedeeper induction curves are valid only with a 2-ft orlarger vertical resolution.

The limits for the 1-, 2-, and 4-ft curves are integral to the chart.As illustrated, a 1-ft 90-in. curve is not usable in a large salt-saturatedborehole. Also, under these conditions, the 1-, 2-, and 4-ft curves can-not have the same resistivity response.

Example: Freshwater Mud BoreholeGiven: Borehole size = 10 in., Rt = 5 ohm-m, Rm = 0.135 ohm-m,

and standoff (so) = 1.5 in.

Find: Which, if any, of the AIT curves are valid.

Answer: Rt/Rm = 37.0, (dh/8)2 = (10/8)2 = 1.5625, and (1.5/so) =1.5/1.5 = 1. The resulting value from the x-axis equationis 37.0 × 1.5625 × 1 = 57.9.

Enter the chart at 57.9 on the x-axis and intersect Rt = 5 ohm-m on the y-axis. The intersection point iswithin the limit of the 1-ft vertical resolution boundary.All the AIT induction curves are usable.

R

R

d

sot

m

h⎛

⎝⎜⎞

⎠⎟⎛

⎝⎜⎞

⎠⎟⎛⎝⎜

⎞⎠⎟

=8

1 52

.

50 0135

108

1 52 5

2

...

⎛⎝⎜

⎞⎠⎟

⎛⎝⎜

⎞⎠⎟

⎛⎝⎜

⎞⎠⎟

=

370 1 5625 0 6 346( )( )( ) =. . .


125

RInd

Resistivity Induction—Wireline

AIT* Array Induction Imager ToolOperating Range—Open Hole RInd-1

1,000

100

10

1

0.01 0.1 1 10 100 1,000 10,000 100,000

Limit of 4-ft logs

Possible large errors on all logs

Limit of 1-ft logs

Possible large errors on shallow logs and 2-ft limit

Recommended AIT operatingrange (compute standoffmethod for smooth holes)

RR

dht

m

⎛⎝⎜

⎞⎠⎟⎛⎝⎜

⎞⎠⎟

⎛⎝⎜

⎞⎠⎟8

1 52 .so

Rt(ohm-m)

Rt(ohm-m)

Salt-saturated boreholeexample

Freshwater mud example

10,000

1,000

100

1

0.01 0.1 1 10 100 1,000 10,000 100,000

Rt/Rm

AIT 2-ft limitAIT 4-ft limit

AIT 1-ft limit

AIT and HRLA*tools

AITtools

HRLAtools



RInd


126

AIT* Array Induction Imager ToolBorehole Correction—Open Hole

IntroductionThe AIT tools (AIT-B, AIT-C, AIT-H, AIT-M, Slim Array InductionImager Tool [SAIT], Hostile Environment Induction Imager Tool[HIT], and SlimXtreme* Array Induction Imager Tool [QAIT]) do nothave chartbook corrections for environmental effects. The normaleffects that required correction charts in the past (borehole correc-tion, shoulder effect, and invasion interpretation) are now all madeusing real-time algorithms for the AIT tools. In reality, the charts forthe older dual induction tools were inadequate for the complexity ofenvironmental effects on induction tools. The very large volume ofinvestigation required to obtain an adequate radial depth of investiga-tion to overcome invasion makes the resulting set of charts too exten-sive for a book of this size. The volume that affects the logs can be tensof feet above and below the tool. To make useful logs, the effects of thevolume above and below the layer of interest must be carefully removed.This can be done only by either signal processing or inversion-basedprocessing. This section briefly describes the wellsite processing andadvanced processing available at computing centers.

Wellsite ProcessingBorehole CorrectionThe first step of AIT log processing is to correct the raw data from all eight arrays for borehole effects. Borehole corrections for the AITtools are based on inversion through an iterative forward model tofind the borehole parameters that best reproduce the logs from thefour shortest arrays—the 6-, 9-, 12-, and 15-in. arrays (Grove andMinerbo, 1991). The borehole forward model is based on a solutionto Maxwell’s equations in a cylindrical borehole of radius r with themud resistivity (Rm) surrounded by a homogeneous formation ofresistivity Rf. The tool can be located anywhere in the borehole, butis parallel to the borehole axis at a certain tool standoff (so). Theborehole is characterized by its radius (r). In this model, the signalin a given AIT array is a function of only these four parameters.

The four short arrays overlap considerably in their investigationdepth, so only two of the borehole parameters can be uniquely deter-mined in an inversion. The others must be supplied by outside mea-surements or estimates. Because the greatest sensitivity to theformation resistivity is in the contrast between Rm and Rf, no externalmeasurement is satisfactory for fitting to Rf. Therefore, Rf is alwayssolved for. This leaves one other parameter that can be determined.The three modes of the borehole correction operation depend onwhich parameter is being determined:■ compute mud resistivity: requires hole diameter and standoff

■ compute hole diameter: requires a mud resistivity measurementand standoff

■ compute standoff: requires hole diameter and mud resistivitymeasurement.

Because the AIT borehole model is a circular hole, either axisfrom a multiaxis caliper can be used. If the tool standoff is adequate,the process finds the circular borehole parameters that best matchthe input logs. Control of adequate standoff is important becausethe changes in the tool reading are very large for small changes intool position when the tool is very close to the borehole wall. Nearthe center of the hole the changes are very small. A table of rec-ommended standoff sizes is as follows.

Each type of AIT tool requires a slightly different approach tothe borehole correction method. For example, the AIT-B tool requiresthe use of an auxiliary Rm measurement (EnvironmentalMeasurement Sonde [EMS]) to compute Rm or to compute holesize by using a recalibration of the mud resistivity method internalto the borehole correction algorithm. The Platform Express*,SlimAccess*, and Xtreme* AIT tools have integral Rm sensors thatmeet the accuracy requirements for the compute standoff mode.

Log FormationAIT tools are designed to produce a high-resolution log responsewith reduced cave effect in comparison with the induction log deep(ILD) in most formations. The log processing (Barber and Rosthal,1991) is a weighted sum of the raw array data:

where σlog (z) is the output log conductivity in mS/m, σa(n) is the

skin-effect-corrected conductivity from the nth array, and theweights (w) represent a deconvolution filter applied to each of theraw array measurements. The log depth is z, and z′ refers to the distance above or below the log depth to where the weights areapplied. The skin effect correction consists of fitting the X-signal to the skin-effect-error signal (Moran, 1964; Barber, 1984) at highconductivities and the R-signal to the error signal at low conductivi-

σ σlogmin

max

z w z z zn

N

z z

z z

n an( ) = ′( ) − ′( )

= =

= ( )Σ Σ1

,,

AIT Tool Recommended StandoffHole Size (in.) Recommended Standoff (in.)

AIT-B, AIT-C, AIT-H, AIT-M, HIT SAIT, QAIT<5.0 – 0.55.0 to 5.5 – 1.0 5.5 to 6.5 0.5 1.5 6.5 to 7.75 1.0 2.0 7.75 to 9.5 1.5 2.5 9.5 to 11.5 2.0 + bowspring† 2.5 >11.5 2.5 + bowspring† 2.5 Note: Do not run AIT tools slick.

† Only for AIT-H tool


127

RInd


ties, with the crossover occurring between 100 and 200 mS/m. Theuse of the R-signal at low conductivities overcomes the errors inthe X-signal associated with the normal magnetic susceptibilities of sedimentary rock layers (Barber et al., 1995).

The weights w in the equation can profit from further refine-ment. The method used to compute the weights introduces a smallamount of noise in the matrix inversion, so the fit is about ±1% to±2% to the defined target response. A second refinement filter isused to correct for this error. The AIT wellsite processing sequence,from raw, calibrated data to corrected logs, is shown in Fig. 1.

There are only two versions of this processing—one for AIT-B,AIT-C, and AIT-D tools and one for all other AIT tools (AIT-H, AIT-M,SAIT, HIT, and QAIT) (Anderson and Barber, 1995). Only two ver-sions are required because the tools were carefully designed withthe same coil spacings to produce the same two-dimensional (2D)response to the formation.

Advanced ProcessingLogs in Deviated Wells or Dipping FormationsThe interpretation of induction logs is complicated by the large vol-ume of investigation of these tools. The AIT series of induction toolsis carefully focused to limit the contributions from outside a rela-tively thin layer of response (Barber and Rosthal, 1991). In beds at high relative dip, the focused response cuts across several beds,and the focusing developed for vertical wells no longer isolates theresponse to a single layer. The effect of the high relative dip angle is to blur the response and to introduce horns at the bed boundaries.

Maximum Entropy Inversion: MERLIN ProcessingThe maximum entropy inversion method was first applied by Dyos(1987) to induction log data. For beds at zero dip angle, it has beenshown to give well-controlled results when applied to deep induction(ID) and medium induction (IM) from the dual induction tool

(Freedman and Minerbo, 1991, 1993; Zhang et al., 1994). Maximum-Entropy Resistivity Log Inversion (MERLIN) processing (Barber etal., 1999) follows Freedman and Minerbo (1991) closely, and thatpaper is the basic reference for the mathematical formulation. Theproblem is set up as the simplest parametric model that can fit thedata: a thinly layered formation with each layer the same thickness(Fig. 2). The inversion problem is to solve for the conductivity ofeach layer so that the computed logs from the layered formation are the closest match to the measured logs.


Rn

R1

yxφ

ρ

z

θ

Well path

∆z

Figure 2. The parametric model used in MERLIN inversion. All layers are thesame thickness, and the inversion solves for the conductivity of each layerwith maximum-entropy constraints.

10 in.20 in.30 in.60 in.90 in.

28 channels(AIT-B, -C, and -D)16 channels(all others)

Skineffect

correction

Multichannelsignal

processingand 2D

processing

14or8

28or16

Boreholecorrection

Caliper

Rm

Standoff

A(H)IFC

R-signals only

R-signalsX-signals

28or16

Five depths(10 to 90 in.)

Five depths(10 to 90 in.)

Exceptionhandling and

environmentallycompensatedlog processing

Rm

Caliper

Raw BHC signals

+

Figure 1. Block diagram of the real-time log processing chain from raw, calibrated array data to finished logs.


Rxo

Rxo

Rt

Rt

ri

Formationresistivity

profile

Distance from wellbore

Step Profile

Distance from wellbore

Slope Profile

Annulus Profile

Rt

Rann

Rxo

r1

r2

r1

r2

128

RInd



Figure 4. Parametric models used in AIT invasion processing. The slopeprofile model is used for real-time processing; the others are available at the computing centers. Rxo = resistivity of the flushed zone, Rt = trueresistivity, ri = radius of invasion, Rann = resistivity of the annulus.

Borehole-corrected R- and X-signals

Model parameters

Sensitivitymatrix

Update modelparameters

Yes

No

ExitWrite modelparameters

as log

28 or 16 channels

Computedlog within 1% of measured

log?

Computed log

Forward model

Initial guess

ComputeLagrangian

Figure 3. Data flow in the MERLIN inversion algorithm. The output is thefinal set of model parameters after the iterations converge.

The flow of MERLIN processing is shown in Fig. 3. The borehole-corrected raw resistive and reactive (R- and X-) signals are used as a starting point. The conductivity of a set of layers is estimated fromthe log values, and the iterative modeling is continued until the logsconverge. The set of formation layer conductivity values is then con-verted to resistivity and output as logs.

Invasion ProcessingThe wellsite interpretation for invasion is a one-dimensional (1D)inversion of the processed logs into a four-parameter invasion model(Rxo, Rt, r1, and r2, shown in Fig. 4). The forward model is based onthe Born model of the radial response of the tools and is accurate formost radial contrasts in which induction logs should be used. Theinversion can be run in real time. The model is also available in theInvasion Correction module of the GeoFrame* Invasion 2 application,which also includes the step-invasion model and annulus model (Fig. 4).


129

RInd



Rt0

∞

∞

Rt1

Rt2

Rxo1

Rxo2

Rm

Rm

Another approach is also used in the Invasion 2 application mod-ule. If the invaded zone is more conductive than the noninvadedzone, some 2D effects on the induction response can complicatethe 1D inversion. Invasion 2 conducts a full 2D inversion using a2D forward model (Fig. 5) to produce a more accurate answer forsituations of conductive invasion and in thin beds.

ReferencesAnderson, B., and Barber, T.: Induction Logging, Sugar Land, TX,USA, Schlumberger SMP-7056 (1995).

Barber, T.D.: “Phasor Processing of Induction Logs IncludingShoulder and Skin Effect Correction,” US Patent No. 4,513,376(September 11, 1984).

Barber, T., et al.: “Interpretation of Multiarray Induction Logs inInvaded Formations at High Relative Dip Angles,” The Log Analyst,(May–June 1999) 40, No. 3, 202–217.

Barber, T., Anderson, B., and Mowat, G.: “Using Induction Tools toIdentify Magnetic Formations and to Determine Relative MagneticSusceptibility and Dielectric Constant,” The Log Analyst(July–August 1995) 36, No. 4, 16–26.

Barber, T., and Rosthal, R.: “Using a Multiarray Induction Tool toAchieve Logs with Minimum Environmental Effects,” paper SPE 22725presented at the SPE Annual Technical Conference and Exhibition,Dallas, Texas, USA (October 6–9, 1991).

Dyos, C.J.: “Inversion of the Induction Log by the Method of MaximumEntropy,” Transactions of the SPWLA 28th Annual LoggingSymposium, London, UK (June 29–July 2, 1987), paper T.

Freedman, R., and Minerbo, G.: “Maximum Entropy Inversion of theInduction Log,” SPE Formation Evaluation (1991), 259–267; alsopaper SPE 19608 presented at the SPE Annual Technical Conferenceand Exhibition, San Antonio, TX, USA (October 8–11, 1989).

Freedman, R., and Minerbo, G.: “Method and Apparatus forProducing a More Accurate Resistivity Log from Data Recorded by anInduction Sonde in a Borehole,” US Patent 5,210,691 (January 1993).

Grove, G.P., and Minerbo, G.N.: “An Adaptive Borehole CorrectionScheme for Array Induction Tools,” Transactions of the SPWLA 32ndAnnual Logging Symposium, Midland, Texas, USA (June 16–19,1991), paper P.

Moran, J.H.: “Induction Method and Apparatus for InvestigatingEarth Formations Utilizing Two Quadrature Phase Components of a Detected Signal,” US Patent No. 3,147,429 (September 1, 1964).

Zhang, Y-C., Shen, L., and Liu, C.: “Inversion of Induction Logs Basedon Maximum Flatness, Maximum Oil, and Minimum Oil Algorithms,”Geophysics (September 1994), 59, No. 9, 1320–1326.

Figure 5. The parametric 2D formation model used in Invasion 2.


arcVISION475* and ImPulse* 43⁄4-in. Array Resistivity Compensated Tools—2 MHzBorehole Correction—Open Hole

Resistivity Electromagnetic—LWD

PurposeThis chart is used to determine the borehole correction applied by the surface acquisition system to arcVISION475 and ImPulsephase-shift (Rps) and attenuation resistivity (Rad) curves on the log. The value of Rt is used in the calculation of water saturation.

DescriptionEnter the appropriate chart for the borehole environmental condi-tions and tool used to measure the various formation resistivitieswith the either the uncorrected phase-shift or attenuation resistivityvalue (not the resistivity shown on the log) on the x-axis. Move upwardto intersect the appropriate resistivity spacing line, and then movehorizontally left to read the ratio value on the y-axis. Multiply theratio value by the resistivity value entered on the x-axis to obtain Rt.

Charts REm-12 through REm-38 are used similarly to ChartREm-11 for different borehole conditions and arcVISION* andImPulse tool combinations.

ExampleGiven: Rps = 400 ohm-m (uncorrected) from arcVISION475

(2-MHz) phase-shift 10-in. resistivity, borehole size = 6 in., and mud resistivity (Rm) = 0.02 ohm-m at forma-tion temperature.

Find: Formation resistivity (Rt).

Answer: Enter the top left chart at 400 ohm-m on the x-axis and move upward to intersect the 10-in. resistivity curve (green).

Move left and read approximately 1.075 on the y-axis.

Rt = 1.075 × 400 = 430 ohm-m.

REm

130


131


REm


REm–11

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

arcVISION475 and ImPulse Borehole Correction for 2 MHz, dh = 6 in., Rm = 0.02 ohm-m

10–1

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad



10 2816 3422Resistivity spacing (in.)




REm-12

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad



281610 3422Resistivity spacing (in.)


132

REm

PurposeThis chart is used similarly to Chart REm-11 to determine the borehole correction applied by the surface acquisition system

to arcVISION475 and ImPulse resistivity measurements. Uncorrectedresistivity is entered on the x-axis, not the resistivity shown on the log.




133

REm


REm-13

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt /Rps Rt /Rad

Rt /Rps Rt /Rad

Rt /Rps Rt /Rad









134

REm


REm-14

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad









135

REm

arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—400 kHzBorehole Correction—Open Hole REm-15

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

arcVISION675 Borehole Correction for 400 kHz, dh = 8 in., Rm = 0.02 ohm-m

10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad





to arcVISION675 resistivity measurements. Uncorrected resistivity is entered on the x-axis, not the resistivity shown on the log.




136

REm

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad



Resistivity spacing (in.) 342216 4028






General

137

REm


1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad









138

REm


1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad









139


REm

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

arcVISION675 Borehole Correction for 2 MHz, dh = 8 in., Rm = 0.02 ohm-m

10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad




arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHzBorehole Correction—Open Hole REm-19





140

REm



1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad



arcVISION675* 63⁄4-in. Array Resistivity Compensated Tool—2 MHzBed Thickness Correction—Open Hole REm-20





141

REm


1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad










142

REm

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5

1.0

2.0

1.5

0.5


10–1

10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103

100 101 102 103 10–1 100 101 102 103

Rps (ohm-m)

Rps (ohm-m)

Rps (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rad (ohm-m)

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad

Rt/Rps Rt/Rad









143

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

arcVISION825 Borehole Correction for 400 kHz, dh = 10 in., Rm = 1.0 ohm-m2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 101 102 103 10–1 100 101 102 103 100






144

REm


arcVISION825* 81⁄4-in. Array Resistivity Compensated Tool—400 kHzBed Thickness Correction—Open Hole REm-24



10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






145

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






146

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






147

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

arcVISION825 Borehole Correction for 2 MHz, dh = 10 in., Rm = 1.0 ohm-m2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






148

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






149

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






150

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






151

REm


arcVISION900* 9-in. Array Resistivity Compensated Tool—400 kHzBorehole Correction—Open Hole REm-31



10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






152

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






153

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






154

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






155

REm


arcVISION900* 9-in.Array Resistivity Compensated Tool—2 MHzBorehole Correction—Open Hole REm-35



10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 103 10–1 100 101 102 103






156

REm


arcVISION900* 9-in. Array Resistivity Compensated Tool—2 MHzBorehole Correction—Open Hole REm-36



10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






157

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






158

REm





10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

10–1 100 101 102 103

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)


1.5

1.0

0.5

Rt/Rps

Rps (ohm-m)

2.0

1.5

1.0

0.5

Rt/Rad

Rad (ohm-m)

10–1 100 101 102 103 10–1 100 101 102 103

10–1 100 101 102 10310–1 100 101 102 103






159

REm


PurposeThis chart is used to determine the correction factor applied by thesurface acquisition system for bed thickness to the phase-shift andattenuation resistivity on the logs of arcVISION675, arcVISION825,and arcVISION900 tools.

DescriptionThe six bed thickness correction charts on this page are paired forphase-shift and attenuation resistivity at different values of true (Rt)and shoulder bed (Rs) resistivity. Only uncorrected resistivity valuesare entered on the chart, not the resistivity shown on the log.

Chart REm-56 is also used to find the bed thickness correctionapplied by the surface acquisition system for 2-MHz arcVISION* andImPulse* logs.

ExampleGiven: Rt/Rs = 10/1, Rps uncorrected = 20 ohm-m (34 in.), and

bed thickness = 6 ft.

Find: Rt.

Answer: The appropriate chart to use is the phase-shift resistivitychart in the first row, for Rt = 10 ohm-m and Rs = 1 ohm-m.

Enter the chart on the x-axis at 6 ft and move upward to intersect the 34-in. spacing line. The correspondingvalue of Rt/Rps is 1.6; Rt = 20 × 1.6 = 32 ohm-m.

arcVISION675*, arcVISION825*, and arcVISION900* Array Resistivity Compensated Tools—400 kHzBed Thickness Correction—Open Hole



arcVISION675*, arcVISION825*, and arcVISION900* Array Resistivity Compensated Tools—400 kHzBed Thickness Correction—Open Hole

REm-55

Phase-Shift Resistivity Attenuation Resistivity

Attenuation Resistivity

arcVISION675, arcVISION825, and arcVISION900 400-kHz Bed Thickness Correction for Rt = 10 ohm-m and Rs = 1 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps Rt/Rad

Bed thickness (ft)

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Bed thickness (ft)

Phase-Shift Resistivity

arcVISION675, arcVISION825, and arcVISION900 400-kHz Bed Thickness Correction for Rt = 1 ohm-m and Rs =10 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps Rt/Rad

Bed thickness (ft)

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Bed thickness (ft)


arcVISION675, arcVISION825, and arcVISION900 400-kHz Bed Thickness Correction for Rt = 100 ohm-m and Rs =10 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps

Bed thickness (ft)


160

REm




161

REm


arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHzBed Thickness Correction—Open Hole REm-56

Phase-Shift Resistivity Attenuation Resistivity


arcVISION and ImPulse 2-MHz Bed Thickness Correction for Rt = 10 ohm-m and Rs =1 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps Rt/Rad

Bed thickness (ft)

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Bed thickness (ft)


arcVISION and ImPulse 2-MHz Bed Thickness Correction forRt = 1 ohm-m and Rs =10 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps Rt/Rad

Bed thickness (ft)

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Bed thickness (ft)

Attenuation ResistivityPhase-Shift Resistivity

arcVISION and ImPulse 2-MHz Bed Thickness Correction forRt = 100 ohm-m and Rs =10 ohm-m at Center of Bed

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Rt/Rps Rt/Rad

Bed thickness (ft)

0 2 4 6 8 10 12 14 16

2.0

1.5

1.0

0.5

0

Bed thickness (ft)

Resistivity spacing (in.) 342216 4028*Mark of Schlumberger© Schlumberger



162

REm

arcVISION675* and ImPulse* Array Resistivity Compensated Tools—2 MHz and 16-in. SpacingDielectric Correction—Open Hole

REm-58

PurposeThis chart is used to estimate the true resistivity (Rt) and dielectriccorrection (εr). Rt is used in water saturation calculation.

DescriptionEnter the chart with the uncorrected (not those shown on the log)phase-shift and attenuation values from the arcVISION675 orImPulse resistivity tool. The intersection point of the two values isused to determine Rt and the dielectric correction. Rt is interpolatedfrom the subvertical lines described by the dots originating at the

listed Rt values. The εr is interpolated from the radial lines originatingfrom the εr values listed on the left-hand side of the chart. ChartsREm-59 through REm-62 are used to determine Rt and εr at largerspacings.

ExampleGiven: Phase shift = 2° and attenuation = 8.45 dB for 16-in.

spacing.

Find: Rt and εr.

Answer: Rt = 26 ohm-m and εr = 70 dB.

–1 0 1 2 3 4 5 6 7 8 98.10

8.15

8.20

8.25

8.30

8.35

8.40

8.45

8.50

8.55

8.60

Phase shift (°)

Attenuation(dB)

1102030405060708090100

125

150

175

200

225

250

275

300

30

50

7010

0

15

20

1,00

010

,000

R to



163

REm


PurposeCharts REm-59 through REm-62 are identical to Chart REm-58 for determining Rt and εr at larger spacings of the arcVISION675 and ImPulse 2-MHz tools.


REm-59

–1 0 1 2 3 4 5 6 7 8 96.3

6.4

6.5

6.6

6.7

6.8

6.9

Phase shift (°)

Attenuation(dB)

1

10

20

30

40

50

60

70

80

90

100

125

150

175

200

225

250

275

300

30

50

70

100

15

20

1,00

010

,000

o

R t



PurposeCharts REm-59 through REm-62 are identical to Chart REm-58 for determining Rt and εr at larger spacings of the arcVISION675and ImPulse 2-MHz tools.

164

REm



REm-60

o

–1 0 1 2 3 4 5 6 7 8 9

4.9

4.8

5.0

5.1

5.2

5.3

5.4

5.5

Phase shift (°)

Attenuation(dB)

1

10

20

30

40

50

60

70

80

90

100

125

150

175

200

225

250

275

300

30

50

70

100

20

1,00

010

,000

R to



165

REm



REm-61

–1 0 1 2 3 4 5 6 7 8 9

4.0

3.9

4.2

4.1

4.3

4.4

4.5

4.6

4.7

Phase shift (°)

Attenuation(dB)

1

10

20

30

40

50

60

70

80

90

100

125

150

175

200

225

250

275

300

30

50

70

100

15

20

1,00

010

,000

o

R t

PurposeCharts REm-59 through REm-62 are identical to Chart REm-58 for determining Rt and εr at larger spacings of the arcVISION675and ImPulse 2-MHz tools.



166

REm



REm-62

–1 0 1 2 3 4 5 6 7 8 93.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

Phase shift (°)

Attenuation(dB)

1

10

20

30

40

50

60

70

80

90

100

125

150

175

200

225

250

275

300

30

50

70

100

15

20

1,00

010

,000

R to

PurposeCharts REm-59 through REm-62 are identical to Chart REm-58 fordetermining Rt and εr at larger spacings of the arcVISION675 andImPulse 2-MHz tools.



167

REm


arcVISION675* and ImPulse* Array Resistivity Compensated Tools—2 MHz with Dielectric AssumptionDielectric Correction—Open Hole

REm-63

10–1

1.0

1.5

2.0

2.5

3.0

3.5

Dielectric Effects of Standard Processed arcVISION675 or ImPulse Logat 2 MHz with Dielectric Assumption

100 101 102 103 104

Rt/Rps

Rps (ohm-m)

10–1

1.0

1.5

2.0

2.5

3.0

3.5

100 101 102 103 104

Rt/Rad

Rad (ohm-m)

0.5

0.5

16 in.22 in.28 in.34 in.40 in.

Resistivityspacing

16 in.22 in.28 in.34 in.40 in.

Resistivityspacing

Dielectric assumptionεr = 5 + 108.5R–0.35

ε1 = 2εr

Dielectric assumptionεr = 5 + 108.5R–0.35

ε2 = 0.5εr

ε2 = 0.5εr

ε1 = 2εr

oo



General

168

Formation Resistivity—Wireline

Resistivity GalvanicInvasion Correction—Open Hole Rt-1

(former Rint-1)

Rt

PurposeThe charts in this chapter are used to determine the correction forinvasion effects on the following parameters:

■ diameter of invasion (di)■ ratio of flushed zone to true resistivity (Rxo/Rt)■ Rt from laterolog resistivity tools.

The Rxo/Rt and Rt values are used in the calculation of water saturation.

DescriptionThe invasion correction charts, also referred to as “tornado” or “but-terfly” charts, assume a step-contact profile of invasion and that allresistivity measurements have already been corrected as necessaryfor borehole effect and bed thickness by using the appropriate chartfrom the “Resistivity Laterolog” chapter.

To use any of these charts, enter the y-axis and x-axis with therequired resistivity ratios. The point of intersection defines di,Rxo/Rt, and Rt as a function of one resistivity measurement.

Saturation Determination in Clean FormationsEither of the chart-derived values of Rt and Rxo/Rt are used to findvalues for the water saturation of the formation (Sw). The first of twoapproaches is the Sw-Archie (SwA), which is found using the Archiesaturation formula (or Chart SatOH-3) with the derived Rt value andknown values of the formation resistivity factor (FR) and the resistiv-ity of the water (Rw). The Sw-ratio (SwR) is found by using Rxo/Rt andRmf/Rw as in Chart SatOH-4.

If SwA and SwR are equal, the assumption of a step-contact inva-sion profile is indicated to be correct, and all values determined (Sw, Rt, Rxo, and di) are considered good.

If SwA > SwR, either invasion is very shallow or a transition-type invasion profile is indicated, and SwA is considered a good value for Sw.

If SwA < SwR, an annulus-type invasion profile may be indicated,and a more accurate value of water saturation may be estimated by using

The correction factor of (SwA /SwR)1 ⁄4 is readily determined fromthe scale.

For more information, see Reference 9.

(SwA/SwR) 1⁄4

0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.0

0.80 0.85 0.90 0.95 1.0

SwA/SwR

S SS

Swcor wAwA

wR

=⎛

⎝⎜⎞

⎠⎟

14

© Schlumberger



169

Rt

PurposeThe resistivity values of HALS laterolog deep resistivity (HLLD),HALS laterolog shallow resistivity (HLLS), and resistivity of theflushed zone (Rxo) measured by the High-Resolution AzimuthalLaterolog Sonde (HALS) are used with this chart to determine values for diameter of invasion (di) and true resistivity (Rt).

DescriptionThe conditions for which this chart is used are listed at the top. Thechart is entered with the ratios of HLLD/HLLS on the x-axis andHLLD/Rxo on the y-axis. The intersection point defines di on thedashed curves and the ratio of Rt/Rxo on the solid curves.

ExampleGiven: HLLD = 50 ohm-m, HLLS = 15 ohm-m, Rxo = 2.0 ohm-m,

and Rm = 0.2 ohm-m.

Find: Rt and diameter of invasion.

Answer: Enter the chart with the values of HLLD/HLLS = 50/15 =3.33 and HLLD/Rxo = 50/2 = 25.

The resulting point of intersection on the chart indicatesthat Rt/Rxo = 35 and di = 34 in.

Rt = 35 × 2.0 = 70 ohm-m.

High-Resolution Azimuthal Laterolog Sonde (HALS)Formation Resistivity and Diameter of Invasion—Open Hole

Rt-2

0.2

0.5

5

10

20

50

100

200

500

1,000

8 15 18 20 22 24 28 32 3640

4550

60

80

100

120

di (in.)

2

103

102

101

100

10–1

100 101 102

HLLD/Rxo

Thick Beds, 8-in. Hole, Rxo/Rm = 10

HLLD/HLLS

Rt/Rxo

© Schlumberger



High-Resolution Azimuthal Laterolog Sonde (HALS)Formation Resistivity and Diameter of Invasion—Open Hole Rt-3

170

PurposeThe resistivity values of high-resolution deep resistivity (HRLD), high-resolution shallow resistivity (HRLS), and Rxo measured by the HALSare used similarly to Chart Rt-2 to determine values for di and Rt.

DescriptionThe conditions for which this chart is used are listed at the top. Thechart is entered with the ratios of HRLD/HRLS on the x-axis andHRLD/Rxo on the y-axis. The intersection point defines di on thedashed curves and the ratio of Rt/Rxo on the solid curves.

Thick Beds, 8-in. Hole, Rxo/Rm = 10

HRLD/HRLS

HRLD/Rxo

di (in.)

1,000

8 15 18 20 22 24 28 32 3640

4550

60

80

100

120

0.2

0.5

2

103

102

101

100

10–1

500

200

100

50

20

10

5

100 101 102

Rt/Rxo

Rt

© Schlumberger


Formation Resistivity—LWD

171

Rt

PurposeThis chart is used to determine the correction applied to the log presentation of Rt and di determined from geoVISION675 ring (Rring)and deep (Rbd) and medium button (Rbm) resistivity values.

DescriptionEnter the chart with the ratios of Rring/Rbd on the x-axis andRring/Rbm on the y-axis. The intersection point defines di on the bluedashed curves, Rt/Rring on the red curves, and Rt/Rxo on the blackcurves. Charts Rt-11 through Rt-17 are similar to Chart Rt-10 for different tool sizes, configurations, and resistivity terms.

ExampleGiven: Rring = 30 ohm-m, Rxo/Rm = 50, Rbd = 15 ohm-m, and

Rbm = 6 ohm-m.

Find: Rt, di, and Rxo.

Answer: Enter the chart with values of Rring/Rbd = 30/15 = 2 onthe x-axis and Rring/Rbm = 30/6 = 5 on the y-axis to find di = 22.5 in., Rt/Rring = 3.1, and Rt/Rxo = 50. From theseratios, Rt = 3.1 × 30 = 93 ohm-m and Rxo = 93/50 = 1.86 ohm-m.

geoVISION675* ResistivityFormation Resistivity and Diameter of Invasion—Open Hole Rt-10

Ring, Deep, and Medium Button Resistivity (6.75-in. tool)

1 3

10

1

2

3

5

6

7

89

4

2

Rring/Rbd

Rring/Rbm

10070

50

30

20

15

10

7

5

3

2

24

22

20

1817

16

15

14

13

12

di

3.0

2.42.01.81.61.5

1.4

1.3

1.2

Rt/Rring

Rt/Rxo

Rxo/Rm = 50dh = 8.5 in.



PurposeThis chart is used similarly to Chart Rt-10 to determine the correction applied to the log presentation of Rt and di determinedfrom geoVISION675 deep (Rbd), medium (Rbm), and shallow button (Rbs) resistivity values.



172

Deep, Medium, and Shallow Button Resistivity (6.75-in. tool)

1

30

1

3

5

6

87

910

20

4

Rbd/Rbm

Rbd/Rbs

2

2 3 4 5 6

10070

50

30

20

15

10

7

5

3

18

17

16

151413

12

11

1.6

1.51.41.31.2

1.1

di

2

1

Rt/Rbd

Rt/Rxo

Rxo/Rm = 50dh = 8.5 in.

Rt




173

Rt


Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 4 ft

1

10

1

2

3

5

6

7

89

4

2

Rbit/Rring

Rbit/Rbd

3 4 5 6 7 8

24

10070

50

30

2015

10

7

5

3

2

1

50

40

34

28

22

20

18

16

4.03.02.5

2.0

1.8

1.6

1.4

di

Rt/Rbit

Rt/Rxo

Rxo/Rm = 50dh = 8.5 in.

PurposeThis chart is used similarly to Chart Rt-10 to determine the correc-tion applied to the log presentation of Rt and di determined fromgeoVISION675 Rring, bit (Rbit), and Rbd resistivity values.





174

Bit, Ring, and Deep Button Resistivity (6.75-in. tool) with ROP to Bit Face = 35 ft

1

1

3

5

6

87

910

20

4

Rbit/Rring

Rbit/Rbd

2

2 9876543 10 20

24

22

1.4

1.3

10070

50

30

20

15

10

7

5

3

2

1

70

5034

28

20

18

16

2.42.0

1.6

1.2

Rxo/Rm = 50dh = 8.5 in.

di

Rt/Rbit

Rt/Rxo

Rt

PurposeThis chart is used similarly to Chart Rt-10 to determine the correc-tion applied to the log presentation of Rt and di determined fromgeoVISION675 Rring, Rbit, and Rbd resistivity values.




175

Rt

geoVISION825* 81⁄4-in. Resistivity-at-the-Bit ToolFormation Resistivity and Diameter of Invasion—Open Hole Rt-14

Ring, Deep, and Medium Button Resistivity (81⁄4-in. tool)

1

10

1

2

3

5

6

7

8

9

4

2

Rring/Rbd

Rring/Rbm

1.2

17

10070

50

30

2015

10

7

5

3

2

1

30

26

242322

21

20

19

18

16

3.0

2.41.8

1.6

1.4

1.3

Rt/Rring

di

Rt/Rxo

Rxo/Rm = 50dh = 12.25 in.

PurposeThis chart is used similarly to Chart Rt-10 to determine the correc-tion applied to the log presentation of Rt and di determined fromgeoVISION825 Rring, Rbd, and Rbm resistivity values.





176

Deep, Medium, and Shallow Button Resistivity (81⁄4-in. tool)

1

1

3

5

6

87

910

20

4

Rbd/Rbm

Rbd/Rbs

2

32 4 5

10070

50

30

20

15

10

7

5

3

2

1

24

22

2019

18

17

16

14

2.42.0

1.61.41.3

1.2

1.1

di

Rt/Rbd

Rt/Rxo

Rxo/Rm = 50dh = 12.25 in.

Rt

PurposeThis chart is used similarly to Chart Rt-10 to determine the correc-tion applied to the log presentation of Rt and di determined fromgeoVISION825 Rbd, Rbm, and Rbs resistivity values.




177

Rt


10

1

2

3

5

6

7

8

9

4Rbit/Rbd

Bit, Ring, and Deep Button Resistivity (81⁄4-in. tool) with ROP to Bit Face = 4 ft

1

2

Rbit/Rring

3 4 5 6 7 8

10070

50

30

20

15

10

7

5

3

2

60

50

4035

30

28

26

24

22

20

5.0

3.02.4

2.01.8

1.6

1.5

1.4

1.3

1

di

Rt/Rbit

Rt/Rxo

Rxo/Rm = 50dh = 12.25 in.






178

Bit, Ring, and Deep Button Resistivity (81⁄4-in. tool) with ROP to Bit Face = 35 ft

1

1

3

5

6

87

910

20

4

Rbit/Rring

Rbit/Rbd

2

1098765432 20

Rt/Rxo = 50dh = 12.25 in.

di

Rt/Rbit

Rt/Rxo

10070

50

30

20

15

10

7

5

3

2

1

70

5040

35

30

28

26

24

22

20

3.02.0

1.6

1.4

1.3

1.2

Rt




179

Rt

arcVISION* Array Resistivity Compensated Tool—400 kHzResistivity Anisotropy Versus Shale Volume—Open Hole Rt-31

PurposeThis chart illustrates the resistivity response, as affected by sand and shale layers, of the arcVISION tool in horizontal wellbores. The chart is used to determine the values of Rh and Rv. These corrections are already applied to the log presentation.

DescriptionThe chart is constructed for shale layers at 90° relative dip to theaxis of the arcVISION tool. That is, both the layers of shale and thetool are horizontal to the vertical. Other requirements for use of thischart are that the shale resistivity (Rsh) is 1 ohm-m and the sandresistivity is 5 or 20 ohm-m.

Select the appropriate chart for the attenuation (Rad) or phase-shift (Rps) resistivity and values of resistivity of the shale (Rsh) andsand (Rsand). Enter the chart with the volume of shale (Vsh) on the x-axis and the resistivity on the y-axis. At the intersection point ofthese two values move straight downward to the dashed blue curveto read the value of Rh. Move upward to the solid green curve to readthe value of Rv.

Chart Rt-32 is used to determine Rh and Rv values for the 2-MHzresistivity.

101Attenuation Resistivity

0 0.2 0.4 0.6 0.8 1.0100

101Phase-Shift Resistivity

Rps (ohm-m)

Vsh

Response Through Sand and Shale Layers at 90° Relative Dip for Rsh = 1 ohm-m and Rsand = 5 ohm-m

100

Rad (ohm-m)

0 0.2 0.4 0.6 0.8 1.0

Vsh




101

100

0

Rps (ohm-m)

0.2 0.4 0.6 0.8 1.0

Vsh

102

101

100

0

Rad (ohm-m)

0.2 0.4 0.6 0.8 1.0

Vsh

Rh Rv

102

16 in. 22 in. 28 in. 34 in. 40 in.Resistivity spacing





180

Rt

arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHzResistivity Anisotropy Versus Shale Volume—Open Hole Rt-32



101

100

102

101

100

102Phase-Shift Resistivity


101

100

102

101

100

102

0 0.2 0.4 0.6 0.8 1.0

Vsh

Rps(ohm-m)

0

Rps(ohm-m)

0.2 0.4 0.6 0.8 1.0

Vsh

Attenuation ResistivityAttenuation Resistivity

Rad(ohm-m)

0 0.2 0.4 0.6 0.8 1.0

Vsh

0

Rad(ohm-m)

0.2 0.4 0.6 0.8 1.0

Vsh

Rh Rv


PurposeThis chart is used similarly to Chart Rt-31 for arcVISION andImPulse 2-MHz resistivity. These corrections are already applied to the log presentation.



181

Rt

arcVISION* Array Resistivity Compensated Tool—400 kHzResistivity Anisotropy Versus Dip—Open Hole Rt-33


Aniostropy Response for Rh = 1 ohm-m and (Rv/Rh) = 5

101

100

0 2010 40 60 80 90

Relative dip angle (°)

103

102

30 50 70 0 2010 40 60 80 90


30 50 70

0 2010 40 60 80 9030 50 70


0 2010 40 60 80 9030 50 70


Attenuation Resistivity Attenuation Resistivity103

101

100

102



100

101

100

101

Rps(ohm-m)

Rad(ohm-m)

Rps(ohm-m)

Rad(ohm-m)



PurposeThis chart is used to determine arcVISION Rps and Rad for relativedip angles from 0 to 90°. These corrections are already applied to the log presentation.

DescriptionEnter the appropriate chart with the value of relative dip angle andmove to intersect the known resistivity spacing. Move horizontallyleft to read Rps or Rad for the conditions of the horizontal resistivity(Rh) = 1 ohm-m and the square root of the Rv/Rh ratio.




182

Rt

PurposeThis chart is used similarly to Chart Rt-33 for arcVISION andImPulse 2-MHz resistivity. These corrections are already applied to the log presentation.

arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHzResistivity Anisotropy Versus Dip—Open Hole Rt-34





101

100

103

102

103

101

100

102

Rps(ohm-m)

Rad(ohm-m)

0 2010 40 60 80 90


30 50 70

0 2010 40 60 80 9030 50 70


100

101

100

101

Rps(ohm-m)

Rad(ohm-m)

0 2010 40 60 80 90


30 50 70

0 2010 40 60 80 9030 50 70


Attenuation Resistivity Attenuation Resistivity




183

Rt


arcVISION* Array Resistivity Compensated Tool—400 kHzResistivity Anisotropy Versus Square Root of Rv/Rh—Open Hole Rt-35

PurposeThis chart and Chart Rt-36 reflect the effect of anisotropy on thearcVISION resistivity response. These corrections are already applied to the log presentation. As the square root of the Rv/Rh

ratio increases, the effect on the resistivity significantly increases.

DescriptionEnter the appropriate chart with the value of the phase-shift orattenuation resistivity on the y-axis. Move horizontally to intersectthe resistivity spacing curve. At the intersection point read the valueof the square root of the Rv/Rh ratio on the x-axis.


Aniostropy Response at 85° dip for Rh = 1 ohm-m

101

100

1.0

Rps(ohm-m)

2.01.5 3.0 4.0 5.0

(Rv/Rh)

103

102

101

100

Rad(ohm-m)

103

102

2.5 3.5 4.5 1.0 2.01.5 3.0 4.0 5.02.5 3.5 4.5

1.0 2.01.5 3.0 4.0 5.02.5 3.5 4.51.0 2.01.5 3.0 4.0 5.0

(Rv/Rh)

2.5 3.5 4.5




100

Rps(ohm-m)

101

101

100

Rad(ohm-m)


(Rv/Rh)

(Rv/Rh)




184

Rt

PurposeThis chart is used similarly to Chart Rt-35 for arcVISION andImPulse for 2-MHz resistivity. These corrections are already applied to the log presentation.

arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHzResistivity Anisotropy Versus Square Root of Rv/Rh—Open Hole Rt-36





1.0 2.01.5 3.0 4.0 5.02.5 3.5 4.5 1.0 2.01.5 3.0 4.0 5.0

(Rv/Rh)

2.5 3.5 4.5

1.0 2.01.5 3.0 4.0 5.0

(Rv/Rh)

2.5 3.5 4.51.0 2.01.5 3.0 4.0 5.0

(Rv/Rh)

2.5 3.5 4.5


101

100

Rps(ohm-m)

103

102

101

100

Rad(ohm-m)

103

102

100

Rps(ohm-m)

101

101

100

Rad(ohm-m)


(Rv/Rh)



185

Rt


arcVISION675* Array Resistivity Compensated Tool—400 kHzConductive Invasion—Open Hole Rt-37

PurposeThis log-log chart is used to determine the correction applied to the log presentation of the 40-in. arcVISION675 resistivity measure-ments, diameter of invasion (di), and resistivity of the flushed zone(Rxo). These data are used to evaluate a formation for hydrocarbons.

DescriptionEnter the chart with the ratio of the 16-in. Rps /40-in. Rad on the y-axisand 28-in. Rps /40-in. Rad on the x-axis. The intersection point definesthe following:

■ di

■ Rxo

■ correction factor for 40-in. attenuation resistivity.

Chart Rt-38 is used for 2-MHz resistivity values. The correspondingcharts for resistive invasion are Charts Rt-39 and Rt-40.

ExampleGiven: 16-in. Rps/40-in. Rad = 0.2 and 28-in. Rps/40-in. Rad = 0.4.

Find: Rxo, di, and correction factor for 40-in. Rad.

Answer: At the intersection point of 0.2 on the y-axis and 0.4 onthe x-axis, di = 31.9 in., Rxo = 1.1 ohm-m, and correctionfactor = 0.955.

The value of the 40-in. Rad is reduced by the correctionfactor: 40-in. Rad × 0.955.

28-in. Rps/40-in. Rad


0.010.01

0.1

0.1

1.0

1.0

Rxo and di for Rt ~ 10 ohm-m

16

20

2428

32

36404448

52

56

60

64

0.15

0.20.3

0.5

0.71

1.5

2

3

5

7

0.95

0.9

0.80.85

0.750.7

0.650.6

0.55

40-in. Rad/Rt = 1

di (in.)

Rxo = 0.1 ohm−m




186

Rt

arcVISION675* and ImPulse* Array Resistivity Compensated Tools—2 MHzConductive Invasion—Open Hole Rt-38

28-in. Rps /40-in. Rad


0.010.01

0.1 1.0

1.0Rxo and di for Rt ~ 10 ohm-m

0.3

0.5

0.15

7

0.7

1

1.5

2

3

5

16

20

24283236

40

44

48 52

di (in.)

56

0.2

40-in. Rad/Rt = 1

0.9

0.8

0.7

0.3

0.60.5

0.2

0.1

0.4

Rxo = 0.1 ohm-m

PurposeThis chart is used similarly to Chart Rt-37 for arcVISION675 andImPulse 2-MHz resistivity. The corrections are already applied to the log presentation.



187

Rt


arcVISION* Array Resistivity Compensated Tool—400 kHzResistive Invasion—Open Hole Rt-39

30

35

40

45

50

55

60

65

70

75

80

90

100

125

200

150

100

70

50

30

20

15

di (in.)

Rxo = 300 ohm-m



11

10

10 Rxo and di for Rt ~ 10 ohm-m

Rt /40-in. Rad = 1

0.95

0.9

0.85

0.8

0.75

0.7

0.65

0.6

0.55

PurposeThis chart is used similarly to Chart Rt-37 to determine the correc-tion applied to the arcVISION log presentation of di, Rxo, and 40-in.Rad for resistive invasion.




188

Rt

arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHzResistive Invasion—Open Hole Rt-40



Rxo and di for Rt ~ 10 ohm-m

1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.41.0

1.2

1.4

1.6

2.0

2.2

2.4

1.840

55

60

di (in.)

30

200

150

100

70

50

30

20

15

35

45

0.95

0.9

0.85

0.8

0.75

0.7

0.65

0.55

0.6

Rt/40-in. Rad = 1

50

65

Rxo = 300 ohm-m

PurposeThis chart is used similarly to Chart Rt-39 to determine the correc-tion applied to the arcVISION and ImPulse log presentation for 2-MHz resistivity.



189

Rt

arcVISION* Array Resistivity Compensated Tool—400 kHz in Horizontal WellBed Proximity Effect—Open Hole


PurposeCharts Rt-41 and Rt-42 are used to calculate the correction appliedto the log presentation of Rt from the arcVISION tool at theapproach to a bed boundary. The value of Rt is used to calculatewater saturation.

DescriptionThere are two sets of charts for differing conditions:

■ shoulder bed resistivity (Rshoulder) = 10 ohm-m and Rt = 1 ohm-m■ Rshoulder = 10 ohm-m and Rt =100 ohm-m.

Example

Given: Rshoulder = 10 ohm-m, Rt = 1 ohm-m, and 16-in. Rps = 1.5 ohm-m.

Find: Bed proximity effect.

Answer: The top set of charts is appropriate for these resistivityvalues. The ratio Rps/Rt = 1.5/1 = 1.5.

Enter the y-axis of the left-hand chart at 1.5 and movehorizontally to intersect the 16-in. curve. The corre-sponding value on the x-axis is 1 ft, which is the distanceof the surrounding bed from the tool. At 2 ft from thebed boundary, the value of 16-in. Rps = 1 ohm-m.



Formation Resistivity–Drill PipeFormation Resistivity—LWD

190

Rt

arcVISION* Array Resistivity Compensated Tool—400 kHz in Horizontal WellBed Proximity Effect—Open Hole Rt-41

0 1 2 3 4 5 6 7 8 9 100

1

2

3

Distance to bed boundary (ft)

0 1 2 3 4 5 6 7 8 9 10Distance to bed boundary (ft)

Rps/Rt

Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m and Rt = 1 ohm-m

0 1 2 3 4 5 6 7 8 9 100

1

2

3


Rad/Rt


0

1

2

3

Rps/Rt

0

1

2

3

Rad/Rt

Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m and Rt = 100 ohm-m




191

Rt


arcVISION* and ImPulse* Array Resistivity Compensated Tools—2 MHz in Horizontal WellBed Proximity Effect—Open Hole

Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m, Rt = 1 ohm-m

Bed Proximity Effect for Horizontal Well: Rshoulder = 10 ohm-m, Rt = 100 ohm-m

0

1

2

3

Rps/Rt

0 1 2 3 4 5 6 7 8 9 10


0

1

2

3

Rps/Rt



0

1

2

3

Rad/Rt

0 1 2 3 4 5 6 7 8 9 10


0

1

2

3

Rad/Rt


Rt-42

PurposeThis chart is used similarly to Chart Rt-41 for arcVISION andImPulse 2-MHz resistivity. The correction is already applied to the log presentation.



General

192

GeneralLithology—Wireline

Density and NGS* Natural Gamma Ray Spectrometry ToolMineral Identification—Open Hole

PurposeThis chart is a method for identifying the type of clay in the wellbore.The values of the photoelectric factor (Pe) from the Litho-Density*log and the concentration of potassium (K) from the NGS NaturalGamma Ray Spectrometry tool are entered on the chart.

DescriptionEnter the upper chart with the values of Pe and K to determine thepoint of intersection. On the lower chart, plotting Pe and the ratio of thorium and potassium (Th/K) provides a similar mineral evalua-tion. The intersection points are not unique but are in general areasdefined by a range of values.

ExampleGiven: Environmentally corrected thorium concentration

(ThNGScorr) = 10.6 ppm, environmentally correctedpotassium concentration (KNGScorr) = 3.9%, and Pe = 3.2.

Find: Mineral concentration of the logged clay.

Answer: The intersection points from plotting values of Pe and Kon the upper chart and Pe and Th/K ratio = 10.6/3.9 = 2.7on the lower chart suggest that the clay mineral is illite.

Lith


193

Lith

Lithology—Wireline

Density and NGS* Natural Gamma Ray Spectrometry ToolMineral Identification—Open Hole Lith-1

(former CP-18)

Potassium concentration, K (%)

Thorium/potassium ratio, Th/K

Photoelectricfactor, Pe

Photoelectricfactor, Pe

Glauconite

Glauconite

Chlorite

Chlorite

Biotite

Biotite

Illite

Illite

Muscovite

Muscovite

Montmorillonite

Montmorillonite

Kaolinite

Kaolinite

Mixed layer

0 2 4 6 8 10

0.1 0.2 0.3 0.6 1 2 3 6 10 20 30 60 100

10

8

6

4

2

0

10

8

6

4

2

0




NGS* Natural Gamma Ray Spectrometry ToolMineral Identification—Open Hole Lith-2

(former CP-19)

194

PurposeThis chart is used to determine the type of minerals in a shale formation from concentrations measured by the NGS NaturalGamma Ray Spectrometry tool.

DescriptionEntering the chart with the values of thorium and potassium locatesthe intersection point used to determine the type of radioactive min-erals that compose the majority of the clay in the formation.

A sandstone reservoir with varying amounts of shaliness andillite as the principal clay mineral usually plots in the illite segmentof the chart with Th/K between 2.0 and 3.5. Less shaly parts of thereservoir plot closer to the origin, and shaly parts plot closer to the70% illite area.

0 1 2 3 4 5

Potassium (%)

25

20

15

10

5

0

Thorium(ppm)

Mixed-layer clay

IlliteMicas

Glauconite

Potassium evaporites, ~30% feldspar

~30% glauconite

~70% illite

100% illite point

~40%mica

Mon

tmor

illonit

e

Chlorite

Kaolinite

Possible 100% kaolinite,montmorillonite,illite “clay line”

Th/K

= 2

5

Th/K

= 12

Th/K = 3.5

Th/K = 2.0

Th/K = 0.6

Th/K = 0.3Feldspar

Heav

y th

oriu

m-b

earin

g m

iner

als

Lith



Lith

PurposeThis chart is used to determine the lithology and porosity of a forma-tion. The porosity is used for the water saturation determination andthe lithology helps to determine the makeup of the logged formation.

DescriptionNote that this chart is designed for fresh water (fluid density [ρf] = 1.0 g/cm3) in the borehole. Chart Lith-4 is used for saltwater(ρf = 1.1 g/cm3) formations.

Values of photoelectric factor (Pe) and bulk density (ρb) from thePlatform Express Three-Detector Lithology Density (TLD) tool areentered into the chart. At the point of intersection, porosity andlithology values can be determined.

ExampleGiven: Freshwater drilling mud, Pe = 3.0, and bulk density =

2.73 g/cm3.

Freshwater drilling mud, Pe = 1.6, and bulk density =2.24 g/cm3.

Find: Porosity and lithology.

Answer: For the first set of conditions, the formation is adolomite with 8% porosity.

The second set is for a quartz sandstone formation with 30% porosity.


Platform Express* Three-Detector Lithology Density ToolPorosity and Lithology—Open Hole


195



Platform Express* Three-Detector Lithology Density ToolPorosity and Lithology—Open Hole Lith-3

(former CP-16)

196

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0 0 1 2 3 4 5 6

Photoelectric factor, Pe

Bulk density, ρb(g/cm3)

4030

2010

0

4030

2010

0

0

40

30

2010

0

0

Quar

tz s

ands

tone

Dolo

mite

Calc

ite (l

imes

tone

)Sa

lt

Anhy

drite

Fresh Water (ρf = 1.0 g/cm3), Liquid-Filled Borehole

Lith



197

Lith


Platform Express* Three-Detector Lithology Density ToolPorosity and Lithology—Open Hole Lith-4

(former CP-17)

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0 0 1 2 3 4 5 6


Bulk density, ρb(g/cm3)

4030

2010

0

4030

2010

0

0

Quar

tz s

ands

tone

Dolo

mite

Anhy

drite

40

30

2010

0

Calc

ite (l

imes

tone

)

0Salt

Salt Water (ρf = 1.1 g/cm3), Liquid-Filled Borehole

This chart is used similarly to Chart Lith-3 for lithology and poros-ity determination with values of photoelectric factor (Pe) and

bulk density (ρb) from the Platform Express TLD tool in saltwaterborehole fluid.



GeneralLithology—Wireline, Drillpipe

Density ToolApparent Matrix Volumetric Photoelectric Factor—Open Hole Lith-5

(former CP-20)

PurposeThis chart is used to determine the apparent matrix volumetric photoelectric factor (Umaa) for the Chart Lith-6 percent lithologydetermination.

DescriptionThis chart is entered with the values of bulk density (ρb) and Pe froma density log. The value of the apparent total porosity (φta) must alsobe known. The appropriate solid lines on the right-hand side of thechart that indicate a freshwater borehole fluid or dotted lines thatrepresent saltwater borehole fluid are used depending on the salinityof the borehole fluid. Uf is the fluid photoelectric factor.

ExampleGiven: Pe = 4.0, ρb = 2.5 g/cm3, φta = 25%, and freshwater

borehole fluid.

Find: Apparent matrix volumetric photoelectric factor (Umaa).

Answer: Enter the chart with the Pe value (4.0) on the left-handx-axis, and move upward to intersect the curve for ρb = 2.5 g/cm3.

From that intersection point, move horizontally right tointersect the φta value of 25%, using the blue freshwatercurve.

Move vertically downward to determine the Umaa valueon the right-hand x-axis scale: Umaa = 13.

Lithology—Wireline, LWD

198

6 5 4 3 2 1 4 6 8 10 12 14

3.0

2.5

2.0

0

10

20

30

40


Bulk density, ρb

(g/cm3)

Apparent total porosity, φta (%)

Apparent matrixvolumetric photoelectric factor, Umaa

Fresh water (0 ppm), ρf = 1.0 g/cm3, Uf = 0.398Salt water (200,000 ppm), ρf = 1.11 g/cm3, Uf = 1.36

Lith

© Schlumberger



199

Lith

GeneralGeneralGeneralLithology—Wireline, LWD

PurposeThis chart is used to identify the rock mineralogy through comparisonof the apparent matrix grain density (ρmaa) and apparent matrix volu-metric photoelectric factor (Umaa).

DescriptionThe values of ρmaa and Umaa are entered on the y- and x-axis, respec-tively. The rock mineralogy is identified by the proximity of the pointof intersection of the two values to the labeled points on the plot.The effect of gas, salt, etc., is to shift data points in the directionsshown by the arrows.

ExampleGiven: ρmaa = 2.74 g/cm3 (from Chart Lith-9 or Lith-10) and

Umaa = 13 (from Chart Lith-5).

Find: Matrix composition of the formation.

Answer: Enter the chart with ρmaa = 2.74 g/cm3 on the y-axis andUmaa = 13 on the x-axis. The intersection point indicatesa matrix mixture of 20% dolomite and 80% calcite.

Density ToolLithology Identification—Open Hole


General

200

Lith

GeneralLithology—Wireline, LWD

Apparent matrix volumetric photoelectric factor, Umaa

Apparent matrixgrain density,ρmaa (g/cm3)

2 4 6 8 10 12 14 16

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

Salt

K-feldspar

Quartz

Dolomite

Kaolinite

Illite

Anhydrite

Heavy minerals

Barite

Calcite

Gas

dire

ctio

n

% calcite

% dolomite

% quartz

2060

8040

60

40

20

80

60

40

20

80

Density ToolLithology Identification—Open Hole Lith-6

(former CP-21)

© Schlumberger



201

Lith

PurposeThis chart is used to help identify mineral mixtures from sonic, density, and neutron logs.

DescriptionBecause M and N slope values are practically independent of porosityexcept in gas zones, the porosity values they indicate can be corre-lated with the mineralogy. (See Appendix E for the formulas to calcu-late M and N from sonic, density, and neutron logs.)

Enter the chart with M on the y-axis and N on the x-axis. Theintersection point indicates the makeup of the formation. Points forbinary mixtures plot along a line connecting the two mineral points.Ternary mixtures plot within the triangle defined by the three con-stituent minerals. The effect of gas, shaliness, secondary porosity,etc., is to shift data points in the directions shown by the arrows.

The lines on the chart are divided into numbered groups by poros-ity range as follows:

1. φ = 0 (tight formation)2. φ = 0 to 12 p.u.3. φ = 12 to 27 p.u.4. φ = 27 to 40 p.u.

ExampleGiven: M = 0.79 and N = 0.51.

Find: Mineral composition of the formation.

Answer: The intersection of the M and N values indicates dolomitein group 2, which has a porosity between 0 to 12 p.u.


Environmentally Corrected Neutron CurvesM–N Plot for Mineral Identification—Open Hole



Environmentally Corrected Neutron CurvesM–N Plot for Mineral Identification—Open Hole Lith-7

(former CP-8)

202

1.1

1.0

0.9

0.8

0.7

0.6

0.5

Approximate shale region

Anhydrite

Dolomite

Gypsum

Calcite (limestone)

vma = 5943 m/s = 19,500 ft/s

vma = 5486 m/s = 18,000 ft/s

Sulfur

Quartz sandstone

324 1

1 2 34

Secondaryporosity

Gas or

salt

N

M

0.3 0.4 0.5 0.6 0.7 0.8

Freshwater mudρf = 1.0 Mg/m3, t f = 620 μs/mρf = 1.0 g/cm3, t f = 189 μs/ft

Saltwater mudρf = 1.1 Mg/m3, t f = 607 μs/mρf = 1.1 g/cm3, t f = 185 μs/ft

Lith

© Schlumberger



203

Lith

GeneralGeneralGeneralLithology—Wireline

PurposeThis chart is used to help identify mineral mixtures from APSAccelerator Porosity Sonde neutron logs.

DescriptionBecause M and N values are practically independent of porosityexcept in gas zones, the porosity values they indicate can be corre-lated with the mineralogy. (See Appendix E for the formulas to cal-culate M and N from sonic, density, and neutron logs.)

Enter the chart with M on the y-axis and N on the x-axis. Theintersection point indicates the makeup of the formation. Points forbinary mixtures plot along a line connecting the two mineral points.Ternary mixtures plot within the triangle defined by the three con-stituent minerals. The effect of gas, shaliness, secondary porosity,etc., is to shift data points in the directions shown by the arrows.

The lines on the chart are divided into numbered groups by poros-ity range as follows:

1. φ = 0 (tight formation)2. φ = 0 to 12 p.u.3. φ = 12 to 27 p.u.4. φ = 27 to 40 p.u.

Because the dolomite spread is negligible, a single dolomite pointis plotted for each mud.

ExampleGiven: M = 0.80 and N = 0.55.

Find: Mineral composition of the formation.

Answer: Dolomite.

Environmentally Corrected APS* CurvesM–N Plot for Mineral Identification—Open Hole


General

204

1.1

1.0

0.9

0.8

0.7

0.6

0.5

Approximate shale region

Anhydrite

Dolomite

Gypsum

Calcite (limestone)

vma = 5943 m/s = 19,500 ft/s

vma = 5486 m/s = 18,000 ft/s

Sulfur

Quartz sandstone

12 3,4

Secondaryporosity

Gas or

salt

N

M

0.3 0.4 0.5 0.6 0.7 0.8

Freshwater mudρf = 1.0 Mg/m3, t f = 620 μs/mρf = 1.0 g/cm3, t f = 189 μs/ft

Saltwater mudρf = 1.1 Mg/m3, t f = 607 μs/mρf = 1.1 g/cm3, t f = 185 μs/ft

Lith

GeneralLithology—Wireline

Environmentally Corrected APS* CurvesM–N Plot for Mineral Identification—Open Hole Lith-8

(former CP-8a)




205

Lith

PurposeCharts Lith-9 (customary units) and Lith-10 (metric units) providevalues of the apparent matrix internal transit time (tmaa) and appar-ent matrix grain density (ρmaa) for the matrix identification (MID)Charts Lith-11 and Lith-12. With these parameters the identificationof rock mineralogy or lithology through a comparison of neutron,density, and sonic measurements is possible.

DescriptionDetermining the values of tmaa and ρmaa to use in the MID ChartsLith-11 and Lith-12 requires three steps.

First, apparent crossplot porosity is determined using the appro-priate neutron-density and neutron-sonic crossplot charts in the“Porosity” section of this book. For data that plot above the sand-stone curve on the charts, the apparent crossplot porosity is definedby a vertical projection to the sandstone curve.

Second, enter Chart Lith-9 or Lith-10 with the interval transit time (t) to intersect the previously determined apparent crossplotporosity. This point defines tmaa.

Third, enter Chart Lith-9 or Lith-10 with the bulk density (ρb) to again intersect the apparent crossplot porosity and define ρmaa.

The values determined from Charts Lith-9 and Lith-10 for tmaa andρmaa are cross plotted on the appropriate MID plot (Charts Lith-11and Lith-12) to identify the rock mineralogy by its proximity to thelabeled points on the plot.

ExampleGiven: Apparent crossplot porosity from density-neutron = 20%,

ρb = 2.4 g /cm3, apparent crossplot porosity from neutron-sonic = 30%, and t = 82 μs/ft.

Find: ρmaa and tmaa.

Answer: ρmaa = 2.75 g/cm3 and tmaa = 46 μs/ft.


Bulk Density or Interval Transit Time and Apparent Total PorosityApparent Matrix Parameters—Open Hole



Bulk Density or Interval Transit Time and Apparent Total PorosityApparent Matrix Parameters—Open Hole Lith-9

(customary, former CP-14)

206

3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0

130 120 110 100 90 80 70 60 50 40 303.0

2.9

2.8

2.7

2.6

2.5

2.4

2.3

2.2

2.1

2.0

130

120

110

100

90

80

70

60

50

40

30

Fluid Density = 1.0 g/cm3

Apparent matrix density, ρmaa (g/cm3)

Bulk density,ρb (g/cm3)

Intervaltransittime,

t (μs/ft)

Apparent matrix transit time, tmaa (μs/ft)

40

30

20

10

10

20

30

40

Apparentcrossplotporosity

Density-n

eutron

Neutron-so

nic

Lith

© Schlumberger


207

Lith

PurposeCharts Lith-9 (customary units) and Lith-10 (metric units) providevalues of the apparent matrix internal transit time (tmaa) and appar-ent matrix grain density (ρmaa) for the matrix identification (MID)Charts Lith-11 and Lith-12. With these parameters the identificationof rock mineralogy or lithology through a comparison of neutron,density, and sonic measurements is possible.

GeneralGeneralGeneral

3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0

350 325 300 275 250 225 200 175 150 125 100 3.0

2.9

2.8

2.7

2.6

2.5

2.4

2.3

2.2

2.1

2.0

350

325

300

275

250

225

200

175

150

125

100

Fluid Density = 1.0 g/cm3

Apparent matrix density, ρmaa (g/cm3)


Intervaltransittime,

t (μs/m)

Apparent matrix transit time, tmaa (μs/m)

40

30

20

10

10

20

30

40

Apparentcrossplotporosity

Density-n

eutron

Neutron-so

nic


Bulk Density or Interval Transit Time and Apparent Total PorosityApparent Matrix Parameters—Open Hole Lith-10

(metric, former CP-14m)

© Schlumberger


General

208

PurposeCharts Lith-11 and Lith-12 are used to establish the type of mineralpredominant in the formation.

DescriptionEnter the appropriate (customary or metric units) chart with the values established from Charts Lith-9 or Lith-10 to identify thepredominant mineral in the formation. Salt points are defined fortwo tools, the sidewall neutron porosity (SNP) and the CNL*Compensated Neutron Log. The presence of secondary porosity in the form of vugs or fractures displaces the data points parallel to the apparent matrix internal transit time (tmaa) axis. The presence of gas displaces points to the right on the chart. Plotting some shalepoints to establish the shale trend lines helps in the identificationof shaliness. For fluid density (ρf) other than 1.0 g/cm3 use the tableto determine the multiplier to correct the apparent total densityporosity before entering Chart Lith-11 or Lith-12.

ExampleGiven: ρmaa = 2.75 g/cm3, tmaa = 56 μs/ft (from Chart Lith-9),

and ρf = 1.0 g/cm3.

Find: The predominant mineral.

Answer: The formation consists of both dolomite and calcite,which indicates a dolomitized limestone. The formationused in this example is from northwest Florida in the Jay field. The vugs (secondary porosity) created by thedolomitization process displace the data point parallel to the dolomite and calcite points.

Lith

GeneralLithology—Wireline, LWD

Density ToolMatrix Identification (MID)—Open Hole

ρf Multiplier

1.00 1.001.05 0.981.10 0.951.15 0.93


209

Lith

GeneralGeneralGeneral

30 40 50 60 70

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

tmaa (μs/ft)

ρmaa(g/cm3)

Calcite

Dolomite

Anhydrite

Quartz

Gas direction

Salt (CNL* log)

Salt (SNP)


Density ToolMatrix Identification (MID)—Open Hole Lith-11





Density ToolMatrix Identification (MID)—Open Hole Lith-12


210

PurposeChart Lith-12 is used similarly to Chart Lith-11 to establish the mineraltype of the formation.

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

100 120 140 160 180 200 220 240

tmaa (μs/m)

ρmaa(g/cm3)

Calcite

Dolomite

Anhydrite

Quartz

Gas direction

Salt (SNP)

Salt (CNL* log)

Lith




211

Por

GeneralPorosity—Wireline, LWD

Sonic ToolPorosity Evaluation—Open Hole

PurposeThis chart is used to convert sonic log slowness time (Δt) values into those for porosity (φ).

DescriptionThere are two sets of curves on the chart. The blue set for matrixvelocity (vma) employs a weighted-average transform. The red set is based on the empirical observation of lithology (see Reference20). For both, the saturating fluid is assumed to be water with a velocity (vf) of 5,300 ft/s (1,615 m/s).

Enter the chart with the slowness time from the sonic log on the x-axis. Move vertically to intersect the appropriate matrix velocityor lithology curve and read the porosity value on the y-axis. For rockmixtures such as limy sandstones or cherty dolomites, intermediatematrix lines may be interpolated.

To use the weighted-average transform for an unconsolidated sand,a lack-of-compaction correction (Bcp) must be made. Enter the chartwith the slowness time and intersect the appropriate compactioncorrection line to read the porosity on the y-axis. If the compactioncorrection is not known, it can be determined by working backwardfrom a nearby clean water sand for which the porosity is known.

Example: Consolidated FormationGiven: Δt = 76 μs/ft in a consolidated formation with

vma = 18,000 ft/s.

Find: Porosity and the formation lithology (sandstone,dolomite, or limestone).

Answer: 15% porosity and consolidated sandstone.

Example: Unconsolidated FormationGiven: Unconsolidated formation with Δt = 100 μs/ft in

a nearby water sand with a porosity of 28%.

Find: Porosity of the formation for Δt = 110 μs/ft.

Answer: Enter the chart with 100 μs/ft on the x-axis and movevertically upward to intersect 28-p.u. porosity. Thisintersection point indicates the correction factor curveof 1.2. Use the 1.2 correction value to find the porosity forthe other slowness time. The porosity of an unconsoli-dated formation with Δt = 110 μs/ft is 34 p.u.

Lithology vma (ft/s) Δtma (μs/ft) vma (m/s) Δtma (μs/m)

Sandstone 18,000–19,500 55.5–51.3 5,486–5,944 182–168Limestone 21,000–23,000 47.6–43.5 6,400–7,010 156–143Dolomite 23,000–26,000 43.5–38.5 7,010–7,925 143–126


Porosity—Wireline, LWD

Sonic ToolPorosity Evaluation—Open Hole Por-1

(customary, former Por-3)

30 40 50 60 70 80 90 100 110 120 130

Interval transit time, Δt (μs/ft)

vf = 5,300 ft/s50

40

30

20

10

0

50

40

30

20

10

0

Porosity, φ (p.u.)

Porosity, φ (p.u.)

Time averageField observation

1.1

1.2

1.3

1.4

1.5

1.6

Dolomite

26,00

021

,000

18,00

0

vma(ft/s)

Bcp

23,00

019

,500

Calcite(lim

estone)

Quartzsandstone

212

Por

© Schlumberger


Por

213


Sonic ToolPorosity Evaluation—Open Hole Por-2

(metric, former Por-3m)

100 150 200 250 300 350 400

Interval transit time, Δt (μs/m)

vf = 1,615 m/s50

40

30

20

10

0

50

40

30

20

10

0

Porosity, φ (p.u.)

Porosity, φ (p.u.)

1.1

1.2

1.3

1.4

1.5

1.6

Dolomite

8,000

6,400

5,500

5,950

vma(m/s)

Bcp


7,000

Calcite

Quartzsandstone

Dolomite

Calci

teQua

rtzsa

ndsto

ne

Cemen

ted qu

artz

sand

stone

PurposeThis chart is used similarly to Chart Por-1 with metric units.

© Schlumberger


214

Por

Por-3(former Por-5)

Density ToolPorosity Determination—Open Hole

PurposeThis chart is used to convert grain density (g/cm3) to density porosity.

DescriptionValues of log-derived bulk density (ρb) corrected for borehole size,matrix density of the formation (ρma), and fluid density (ρf) are usedto determine the density porosity (φD) of the logged formation. Theρf is the density of the fluid saturating the rock immediately sur-rounding the borehole—usually mud filtrate.

Enter the borehole-corrected value of ρb on the x-axis and movevertically to intersect the appropriate matrix density curve. From theintersection point move horizontally to the fluid density line. Followthe porosity trend line to the porosity scale to read the formation

porosity as determined by the density tool. This porosity in combina-tion with CNL* Compensated Neutron Log, sonic, or both values ofporosity can help determine the rock type of the formation.

ExampleGiven: ρb = 2.31 g/cm3 (log reading corrected for borehole

effect), ρma = 2.71 g/cm3 (calcite mineral), and ρf = 1.1 g/cm3 (salt mud).

Find: Density porosity.

Answer: φD = 25 p.u.

2.8 2.6 2.4 2.2 2.02.31

1.0 0.9 0.8

1.1

1.2

Porosity, φ (p.u.)

Bulk density, ρb (g/cm3)

ρ ma= 2.8

7 (dolomite)

ρ ma= 2.7

1 (calci

te)

ρ ma= 2.6

5 (quar

tzsa

ndsto

ne)

ρ ma= 2.8

3ρ ma

= 2.68

ρma – ρb

ρma – ρfφ =

ρf (g/cm3)

40

30

20

10

0





215

Por

PurposeThis chart is used for the apparent limestone porosity recorded by theAPS Accelerator Porosity Sonde or sidewall neutron porosity (SNP)tool to provide the equivalent porosity in sandstone or dolomite for-mations. It can also be used to obtain the apparent limestone poros-ity (used for the various crossplot porosity charts) for a log recordedin sandstone or dolomite porosity units.

DescriptionEnter the x-axis with the corrected near-to-array apparent limestoneporosity (APLC) or near-to-far apparent limestone porosity (FPLC)and move vertically to the appropriate lithology curve. Then read theequivalent porosity on the y-axis. For APS porosity recorded in sand-stone or dolomite porosity units enter that value on the y-axis andmove horizontally to the recorded lithology curve. Then read theapparent limestone neutron porosity for that point on the x-axis.

The APLC is the epithermal short-spacing apparent limestoneneutron porosity from the near-to-array detectors. The log is auto-matically corrected for standoff during acquisition. Because it isepithermal this measurement does not need environmental correc-tions for temperature or chlorine effect. However, corrections formud weight and actual borehole size should be applied (see ChartNeu-10). The short spacing means that the effect of density andtherefore the lithology on this curve is minimal.

The FPLC is the epithermal long-spacing apparent limestone neu-tron porosity acquired from the near-to-far detectors. Because it isepithermal this measurement does not need environmental correc-tions for temperature or chlorine effect. However, corrections formud weight and actual borehole size should be applied (see ChartNeu-10). The long spacing means that the density and thereforelithology effect on this curve is pronounced, as seen on Charts Por-13and Por-14.

The HPLC curve is the high-resolution version of the APLC curve.The same corrections apply.

Example: Equivalent PorosityGiven: APLC = 25 p.u. and FPLC = 25 p.u.

Find: Porosity for sandstone and for dolomite.

Answer: Sandstone porosity from APLC = 28.5 p.u. and sandstoneporosity from FPLC = 30 p.u.

Dolomite porosity = 24 and 20 p.u., respectively.

Example: Apparent PorosityGiven: Clean sandstone porosity = 20 p.u.

Find: Apparent limestone neutron porosity.

Answer: Enter the y-axis at 20 p.u. and move horizontally to the quartz sandstone matrix curves. Move verticallyfrom the points of intersection to the x-axis and readthe apparent limestone neutron porosity values. APLC = 16.8 p.u. and FPLC = 14.5 p.u.

APS* Near-to-Array (APLC) and Near-to-Far (FPLC) LogsEpithermal Neutron Porosity Equivalence—Open Hole

Resolution Short Spacing Long Spacing

Normal APLCFPLCEpithermal neutron porosity (ENPI)†

Enhanced HPLCHFLCHNPI†

† Not formation-salinity corrected.

Porosity—Wireline


216

Por

Porosity—Wireline

APS* Near-to-Array (APLC) and Near-to-Far (FPLC) LogsEpithermal Neutron Porosity Equivalence—Open Hole Por-4

(former Por-13a)

40

30

20

10

0 0 10 20 30 40

Apparent limestone neutron porosity, φSNPcor (p.u.) Apparent limestone neutron porosity, φAPScor (p.u.)

True porosity for indicated

matrix material, φ (p.u.)

Calcite(lim

estone)

Dolomite

APLCFPLCSNP

Quartzsa

ndstone



Thermal Neutron ToolPorosity Equivalence—Open Hole

217

Por

GeneralPorosity—Wireline

PurposeThis chart is used to convert CNL* Compensated Neutron Log porositycurves (TNPH or NPHI) from one lithology to another. It can also beused to obtain the apparent limestone porosity (used for the variouscrossplot porosity charts) from a log recorded in sandstone or dolomiteporosity units.

DescriptionTo determine the porosity of either quartz sandstone or dolomiteenter the chart with the either the TNPH or NPHI corrected apparent limestone neutron porosity (φCNLcor) on the x-axis. Movevertically to intersect the appropriate curve and read the porosity for quartz sandstone or dolomite on the y-axis. The chart has a built-in salinity correction for TNPH values.

ExampleGiven: Quartz sandstone formation, TNPH = 18 p.u. (apparent

limestone neutron porosity), and formation salinity =250,000 ppm.

Find: Porosity in sandstone.

Answer: From the TNPH porosity reading of 18 p.u. on the x-axis,project a vertical line to intersect the quartz sandstonedashed red curve. From the y-axis, the porosity of thesandstone is 24 p.u.

40

30

20

10

0 0 10 20 30 40

Apparent limestone neutron porosity, φCNLcor (p.u.)

True porosityfor indicated

matrix material,φ (p.u.)

Quartz

sand

stone

Calcite(lim

estone)

Dolomite

Formation salinity

TNPH

NPHI

0 ppm

250,000 ppm

NPHI Thermal neutron porosity (ratio method)NPOR Neutron porosity (environmentally corrected and

enhanced vertical resolution processed)TNPH Thermal neutron porosity (environmentally corrected)

Por-5(former Por-13b)



218

Por

PurposeThis chart is used similarly to Chart Por-5 to convert 21⁄2-in. compen-sated neutron tool (CNT) porosity values (TNPH) from one lithologyto another. Fresh formation water is assumed.

Porosity—Wireline

Thermal Neutron Tool—CNT-D and CNT-S 21⁄2-in. ToolsPorosity Equivalence—Open Hole

40

30

20

10

0 –10 0 10 20 30 40

Sands

tone

DolomiteLim

estone

Apparent limestone neutron porosity (p.u.)



Por-6

© Schlumberger


219

Por

GeneralPorosity—LWD

adnVISION475* 4.75-in. Azimuthal Density Neutron ToolPorosity Equivalence—Open Hole Por-7

PurposeThis chart is used to determine the porosity of sandstone, limestone,or dolomite from the corrected apparent limestone porosity measuredwith the adnVISION475 4.75-in. tool.

DescriptionEnter the chart on the x-axis with the corrected apparent limestoneporosity from Chart Neu-31 to intersect the curve for the appropriateformation material. Read the porosity on the y-axis.

–5 0 5 10 15 20 25 30 35 40

40

35

30

25

20

15

10

5

0

Corrected apparent limestone neutron porosity, φADNcor (p.u.)



Quartz sandstone

Calcite (lim

estone)

Dolomite



220

Por

PurposeChart Por-8 is used similarly to Chart Por-7 for determining porosity from the corrected apparent limestone porosity from the adnVISION675 6.75-in. tool.

Porosity—LWD


–5 0 5 10 15 20 25 30 35 40

40

35

30

25

20

15

10

5

0


True porosity for indicated

matrix material, φ (p.u.)

Quartz sandstone

Calcite (lim

estone)

Dolomite



221

Por

PurposeChart Por-9 is used similarly to Chart Por-7 for determining porosity from the corrected apparent limestone porosity from the adnVISION825 8.25-in. tool.

Porosity—LWD


–5 0 5 10 15 20 25 30 35 40

40

35

30

25

20

15

10

5

0


True porosity (p.u.)

Sandstone

Limestone

Dolomite



Porosity—LWD

EcoScope* 6.75-in. Integrated LWD Tool, BPHI PorosityPorosity Equivalence—Open Hole Por-10

222

PorPurposeThis chart is used to determine the porosity of sandstone, limestone,or dolomite from the corrected apparent limestone BPHI porositymeasured with the EcoScope 6.75-in. LWD tool.

Use this chart only with EcoScope best thermal neutron porosity(BPHI) measurements; use Chart Por-10a with EcoScope thermalneutron porosity (TNPH) measurements.

DescriptionEnter the chart on the x-axis with the corrected apparent limestoneBPHI porosity from Chart Neu-43 or Neu-44 to intersect the curve forthe appropriate formation material. Read the porosity on the y-axis.

–5 0 5 10 15 20 25 30 35 40

40

35

30

25

20

15

10

5

0

Corrected apparent limestone BPHI porosity (p.u.)



Sandstone

Limestone

Dolomite



Porosity—LWD

EcoScope* 6.75-in. Integrated LWD Tool, TNPH PorosityPorosity Equivalence—Open Hole Por-10a

223

Por

–5 0 5 10 15 20 25 30 35 40

40

35

30

25

20

15

10

5

0

Corrected apparent limestone TNPH porosity (p.u.)



Sandstone

Limestone

Dolomite


PurposeThis chart is used to determine the porosity of sandstone, limestone,or dolomite from the corrected apparent limestone TNPH porositymeasured with the EcoScope 6.75-in. LWD tool.

Use this chart only with EcoScope thermal neutron porosity(TNPH) measurements; use Chart Por-10 with EcoScope best thermal neutron porosity, average (BPHI) measurements.

DescriptionEnter the chart on the x-axis with the corrected apparent limestoneTNPH porosity from Chart Neu-45 or Neu-46 to intersect the curve forthe appropriate formation material. Read the porosity on the y-axis.


224

Por

Porosity—Wireline

CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone)Porosity and Lithology—Open Hole

PurposeThis chart is used with the bulk density and apparent limestoneporosity from the CNL Compensated Neutron Log and Litho-Densitytools, respectively, to approximate the lithology and determine thecrossplot porosity.

DescriptionEnter the chart with the environmentally corrected apparent neu-tron limestone porosity on the x-axis and bulk density on the y-axis.The intersection of the two values describes the crossplot porosityand lithology.

If the point is on a lithology curve, that indicates that the forma-tion is primarily that lithology. If the point is between the lithologycurves, then the formation is a mixture of those lithologies. The posi-tion of the point in relation to the two lithology curves as composi-tion endpoints indicates the mineral percentages of the formation.

The porosity for a point between lithology curves is determinedby scaling the crossplot porosity by connecting similar numbers onthe two lithology curves (e.g., 20 on the quartz sandstone curve to 20 on the limestone curve). The scale line closest to the point repre-sents the crossplot porosity.

Chart Por-12 is used for the same purpose as this chart for salt-water-invaded zones.

ExampleGiven: Corrected apparent neutron limestone porosity =

16.5 p.u. and bulk density = 2.38 g/cm3.

Find: Crossplot porosity and lithology.

Answer: Crossplot porosity = 18 p.u. The lithology is approxi-mately 40% quartz and 60% limestone.


225

Por


CNL* Compensated Neutron Log and Litho-Density* Tool (fresh water in invaded zone)Porosity and Lithology—Open Hole

Por-11(former CP-1e)

0 10 20 30 40Corrected apparent limestone neutron porosity, φCNLcor (p.u.)

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Bulkdensity,

ρb (g/cm3)

Densityporosity,φD (p.u.)

(ρma = 2.71 g/cm3,ρf = 1.0 g/cm3)

45

40

35

30

25

20

15

10

5

0

–5

–10

–15Anhydrite

SulfurSalt

ApproximategascorrectionPorosity

Calcite (lim

estone)

0

5

10

15

20

25

30

35

40

45

Quartz sandstone

0

5

10

15

20

25

30

35

40

Dolomite

0

5

10

15

20

25

30

35

Liquid-Filled Borehole (ρf = 1.000 g/cm3 and Cf = 0 ppm)



226

Por


PurposeThis chart is used similarly to Chart Por-11 with CNL CompensatedNeutron Log and Litho-Density values to approximate the lithologyand determine the crossplot porosity in the saltwater-invaded zone.

ExampleGiven: Corrected apparent neutron limestone porosity =

16.5 p.u. and bulk density = 2.38 g/cm3.


Answer: Crossplot porosity = 20 p.u. The lithology is approxi-mately 55% quartz and 45% limestone.

CNL* Compensated Neutron Log and Litho-Density* Tool (salt water in invaded zone)Porosity and Lithology—Open Hole

Por-12(former CP-11)

0 10 20 30 40

Corrected apparent limestone neutron porosity, φCNLcor (p.u.)

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Bulkdensity,

ρb (g/cm3)

Densityporosity,φD (p.u.)

(ρma = 2.71 g/cm3,ρf = 1.19 g/cm3)

45

40

35

30

25

20

15

10

5

0

–5

–10

–15

Liquid-filled borehole (ρf = 1.190 g/cm3 and Cf = 250,000 ppm)

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

35

40

45

Approximategascorrection

Porosity

Quartz sandstone

Calcite (limestone)

SulfurSalt

Dolomite

Anhydrite



227

Por


APS* and Litho-Density* ToolsPorosity and Lithology—Open Hole Por-13

(former CP-1g)

PurposeThis chart is used to determine the lithology and porosity from theLitho-Density bulk density and APS Accelerator Porosity Sonde porositylog curves (APLC or FPLC). This chart applies to boreholes filledwith freshwater drilling fluid; Chart Por-14 is used for saltwater fluids.

DescriptionEnter either the APLC or FPLC porosity on the x-axis and the bulkdensity on the y-axis. Use the blue matrix curves for APLC porosityvalues and the red curves for FPLC porosity values. Anhydrite plotson separate curves. The gas correction direction is indicated for for-mations containing gas. Move parallel to the blue correction line ifthe APLC porosity is used or to the red correction line if the FPLCporosity is used.

ExampleGiven: APLC porosity = 8 p.u. and bulk density = 2.2 g/cm3.

Find: Approximate quartz sandstone porosity.

Answer: Enter at 8 p.u. on the x-axis and 2.2 g/cm3 on the y-axisto find the intersection point is in the gas-in-formationcorrection region. Because the APLC porosity value wasused, move parallel to the blue gas correction line untilthe blue quartz sandstone curve is intersected at approx-imately 19 p.u.

Liquid-Filled Borehole (ρf = 1.000 g/cm3 and Cf = 0 ppm)


Corrected APS apparent limestone neutron porosity, φAPScor (p.u.)

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0 0 10 20 30 40

APLCFPLC

Anhydrite

DolomiteCalcite (lim

estone)

Quartz sandstone

Porosity


0

5

5

10

10

15

15

20

20

25

25

35

3530

30

40

40

45

0

5

40

35

30

25

20

15

10

0

35

30

25

20

15 15

10

5

0

0

10

20

30

35

40

5

25



228

Por


PurposeThis chart is used similarly to Chart Por-13 to determine the lithologyand porosity from Litho-Density* bulk density and APS* porosity logcurves (APLC or FPLC) in saltwater boreholes.

EExxaammpplleeGiven: APLC porosity = 8 p.u. and bulk density = 2.2 g/cm3.

Find: Approximate quartz sandstone porosity.

Answer: Enter 8 p.u. on the x-axis and 2.2 g/cm3 on the y-axis tofind the intersection point is in the gas-in-formation cor-rection region. Because the APLC porosity value wasused, move parallel to the blue gas correction line untilthe blue quartz sandstone curve is intersected at approx-imately 20 p.u.

APS* and Litho-Density* Tools (saltwater formation)Porosity and Lithology—Open Hole Por-14

(former CP-1h)

Liquid-Filled Borehole (ρf = 1.190 g/cm3 and Cf = 250,000 ppm)


Corrected APS apparent limestone neutron porosity, φAPScor (p.u.)

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.00 10 20 30 40

Anhydrite

Porosity


0

0

5

5

10

10

15

15

20

20

25

25

35

3530

30

40

40

45

0

5

40

35

30

25

20

15

10

0

40

35

30

25

20

15

10

5

0

4545

APLCFPLC

5

10

15

20

25

30

35

40

Quartz sandstone

DolomiteCalcite (limestone)



229

Por


adnVISION475* 4.75-in. Azimuthal Density Neutron ToolPorosity and Lithology—Open Hole Por-15

PurposeThis chart is used to determine the crossplot porosity and lithologyfrom the adnVISION475 4.75-in. density and neutron porosity.

DescriptionEnter the chart with the adnVISION475 corrected apparent lime-stone neutron porosity (from Chart Neu-31) and bulk density. Theintersection of the two values is the crossplot porosity. The positionof the point of intersection between the matrix curves represents therelative percentage of each matrix material.

ExampleGiven: φADNcor = 20 p.u. and ρb = 2.24 g/cm3.

Find: Crossplot porosity and matrix material.

Answer: 25 p.u. in sandstone.


1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Anhydrite

Salt


–5 0 5 10 15 20 25 30 35 40 45

Fresh Water, Liquid-Filled Borehole (ρf = 1.0 g/cm3)

DolomiteCalcite (lim

estone)Quartz

sandstone

Porosity

0

0

5

10

10

15

15

20

20

25

25

35

3530

30

40

40

40

35

30

25

20

15

10

5

05



Por

230


PurposeThis chart uses the bulk density and apparent limestone porosity fromthe adnVISION 6.75-in. Azimuthal Density Neutron tool to determinethe lithology of the logged formation and the crossplot porosity.

DescriptionThis chart is applicable for logs obtained in freshwater drilling fluid. Enter the corrected apparent limestone porosity and the bulkdensity on the x- and y-axis, respectively. Their intersection pointdetermines the lithology and crossplot porosity.

ExampleGiven: Corrected adnVISION675 apparent limestone porosity =

20 p.u. and bulk density = 2.3 g /cm3.

Find: Porosity and lithology type.

Answer: Entering the chart at 20 p.u. on the x-axis and 2.3 g /cm3

on the y-axis corresponds to a crossplot porosity of 21.5 p.u. and formation comprising approximately 60% quartz sandstone and 40% limestone.




1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0–5 0 5 10 15 20 25 30 35 40 45


DolomiteCalcite

(limestone)

Quartz sandstone

0

0

10

10

15

20

25

5

5

5

10

15

20

0

25

35

30

15

20

25

35

30

30

35

4 0

40

Porosity



231

Por


PurposeThis chart is used similarly to Chart Por-15 to determine the lithologyand crossplot porosity from adnVISION825 8.25-in. Azimuthal DensityNeutron values.




1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0–5 0 5 10 15 20 25 30 35 40 45


Calcite (lim

estone)

Quartz sandstone

0

10

5

Dolomite

5

10

15

20

0

25

35

30

15

20

25

35

30

40

0

10

15

20

5

30

35

40

25

Porosity 40



Porosity—LWD

EcoScope* 6.75-in. Integrated LWD ToolPorosity and Lithology—Open Hole Por-18

232

PorPurposeThis chart is used similarly to Chart Por-15 to determine the lithol-ogy and crossplot porosity from EcoScope 6.75-in. density and bestthermal neutron porosity (BPHI) values.

Use this chart only with EcoScope BPHI neutron porosity; useChart Por-19 with EcoScope thermal neutron porosity (TNPH) measurements.


1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Corrected apparent limestone BPHI porosity (p.u.)

–5 0 5 10 15 20 25 30 35 40 45


Anhydrite

Salt

0

10

15

20

25

35

30

40

5

0

10

15

20

25

35

30

40

45

5

DolomiteLimestone

Sandstone

0

10

15

20

25

35

30

40

5



Porosity—LWD

EcoScope* 6.75-in. Integrated LWD ToolPorosity and Lithology—Open Hole Por-19

233

Por


1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Corrected apparent limestone TNPH porosity (p.u.)

–5 0 5 10 15 20 25 30 35 40 45


0

0

5

10

15

20

25

30

35

40

5

10

15

20

25

30

35

40

45

Salt

Anhydrite

Dolomite

LimestoneSandstone

0

5

10

15

20

25

30

35

40


PurposeThis chart is used similarly to Chart Por-15 to determine the lithol-ogy and crossplot porosity from EcoScope 6.75-in. density and ther-mal neutron porosity (TNPH) values.

Use this chart only with EcoScope TNPH neutron porosity; useChart Por-18 with EcoScope best thermal neutron porosity (BPHI)measurements.


234

Por


Sonic and Thermal Neutron CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded

PurposeThis chart is used to determine crossplot porosity and an approxi-mation of lithology for sonic and thermal neutron logs in freshwaterdrilling fluid.

DescriptionEnter the corrected neutron porosity (apparent limestone porosity)on the x-axis and the sonic slowness time (Δt) on the y-axis to findtheir intersection point, which describes the crossplot porosity andlithology composition of the formation. Two sets of curves are drawnon the chart. The blue set of curves represents the crossplot porosityvalues using the sonic time-average algorithm. The red set of curvesrepresents the field observation algorithm.

ExampleGiven: Thermal neutron apparent limestone porosity = 20 p.u.

and sonic slowness time = 89 μs/ft in freshwater drilling fluid.


Answer: Enter the neutron porosity on the x-axis and the sonicslowness time on the y-axis. The intersection point is atabout 25 p.u. on the field observation line and 24.5 p.u.on the time-average line. The matrix is quartz sandstone.


235

Por

GeneralGeneralPorosity—Wireline

Sonic and Thermal Neutron CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded Por-20

(customary, former CP-2c)

0 10 20 30 40

110

100

90

80

70

60

50

40

Corrected CNL* apparent limestone neutron porosity, φCNLcor (p.u.)

Sonic transit time,Δt (μs/ft)

tf = 190 μs/ft and Cf = 0 ppm

Salt

Anhydrite

Dolomite

Calci

te (li

mesto

ne)

Quartz

sand

stone


Poros

ity

0

5

55

00

10

15

20

25

35

40

40

3535

30

3535

30

20

15

25

20

15

10

10

15

20

25

3030

0

5

10

10

15

15

20

2025

2530

30

0

5

0

5

25

10



236

Por


Sonic and Thermal Neutron CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded

Por-21(metric, former CP-2cm)

0 10 20 30 40

360

340

320

300

280

260

240

220

200

180

160

140

Corrected CNL* apparent limestone neutron porosity, φCNLcor (p.u.)

Sonic transit time,Δt (μs/m)

tf = 620 μs/m and Cf = 0 ppm

Salt

Anhyd

rite

Dolomite

Calci

te (li

mesto

ne)

Quartz

sand

stone


Poros

ity

0

5

55

00

10

15

20

35

40

40

35

30

353530

20

15

10

25

20

15

10

10

15

20

3030

0

5

10

10

15

15

20

20

25

2530

30

0

5

0

5

2525

35

25

PurposeThis chart is used similarly to Chart Por-20 for metric units.




237

Por

GeneralGeneralPorosity—Wireline, LWD

Density and Sonic CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded

PurposeThis chart is used to determine porosity and lithology for sonic anddensity logs in freshwater-invaded zones.

DescriptionEnter the chart with the bulk density on the y-axis and sonic slow-ness time on the x-axis. The point of intersection indicates the typeof formation and its porosity.

ExampleGiven: Bulk density = 2.3 g /cm3 and sonic slowness

time = 82 μs/ft.


Answer: Limestone with a crossplot porosity = 24 p.u.


238

Por


Density and Sonic CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded Por-22


40 50 60 70 80 90 100 110 120

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Sonic transit time, Δt (μs/ft)


tf = 189 μs/ft and ρf = 1.0 g/cm3

Dolomite

Calcite

(limes

tone)

Anhydrite

Polyhalite

Gypsum

Trona

Salt

Sylvite

Sulfur

0

10

10

10 20

30

4040 40 40

40

3030

20

0

0

0

0

10

0

Porosity


30

30

30

2020

20

1020

10

Quartz

sand

stone

© Schlumberger


239

Por

General

PurposeThis chart is used similarly to Chart Por-22 for metric units.


Density and Sonic CrossplotPorosity and Lithology—Open Hole, Freshwater Invaded Por-23


150 200 250 300 350 400

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

Sonic transit time, Δt (μs/m)


tf = 620 μs/m and ρf = 1.0 g/cm3

Dolomite

Calcite

(limes

tone)

Anhydrite

Polyhalite

Gypsum

Trona

Salt

Sylvite

Sulfur

0

10

10

10 20

20

20

30

40

30

40 40

40

3030

20

0

0

10

0

Porosity

30

0

0

10


30

10

Quartz

sand

stone

20

20

40

© Schlumberger


240

Por


Density and Neutron ToolPorosity Identification—Gas-Bearing Formation

PurposeThis chart is used to determine the porosity and average water satu-ration in the flushed zone (Sxo) for freshwater invasion and gas com-position of C1.1H4.2 (natural gas).

DescriptionEnter the chart with the neutron- and density-derived porosity values(φN and φD, respectively). On the basis of the table, use the blue curvesfor shallow reservoirs and the red curves for deep reservoirs.

ExampleGiven: φD = 25 p.u. and φN = 10 p.u. in a low-pressure, shallow

(4,000-ft) reservoir.

Find: Porosity and Sxo.

Answer: Enter the chart at 25 p.u. on the y-axis and 10 p.u. on thex-axis. The point of intersection identifies (on the bluecurves for a shallow reservoir) φ = 20 p.u. and Sxo = 62%.

Depth Pressure Temperature ρw (g/cm3) IHw ρg (g/cm3) IHg

Shallow reservoir ~2,000 psi [~14,000 kPa] ~120°F [~50°C] 1.00 1.00 0 0Deep reservoir ~7,000 psi [~48,000 kPa] ~240°F [~120°C] 1.00 1.00 0.25 0.54

ρw = density of water, ρg = density of gas, IHw = hydrogen index of water, and IHg = hydrogen index of gas


241

Por

GeneralGeneralGeneralPorosity—Wireline, LWD

Density and Neutron ToolPorosity Identification—Gas-Bearing Formation Por-24

(former CP-5)

Neutron-derived porosity, φN (p.u.)

Density-derived porosity,φD (p.u.)

50

40

30

20

10

0 0 10 20 30 40

Sxo

Sxo

15

20

Porosity

30

80

35

025

40

55

15

10

20

100

30

25

60

40

60

20

100

80

35

40

20

0

10

For shallow reservoirs, use blue curves.For deep reservoirs, use red curves.

© Schlumberger


242

Por

General

PurposeThis chart is used to determine the porosity and average water satu-ration in the flushed zone (Sxo) for freshwater invasion and gas com-position of CH4 (methane).

DescriptionEnter the chart with the APS Accelerator Porosity Sonde neutron- anddensity-derived porosity values (φN and φD, respectively). On the basisof the table, use the blue curves for shallow reservoirs and the redcurves for deep reservoirs.

ExampleGiven: φD = 15 p.u. and APS φN = 8 p.u. in a normally pressured

deep (14,000-ft) reservoir.

Find: Porosity and Sxo.

Answer: φ = 11 p.u. and Sxo = 39%.

Porosity—Wireline

Density and APS* Epithermal Neutron ToolPorosity Identification—Gas-Bearing Formation

Depth Pressure Temperature ρw IHw ρg IHg

Shallow reservoir ~2,000 psi [~14,000 kPa] ~120°F [~50°C] 1.00 1.00 0.10 0.23Deep reservoir ~7,000 psi [~48,000 kPa] ~240°F [~120°C] 1.00 1.00 0.25 0.54

ρw = density of water, ρg = density of gas, IHw = hydrogen index of water, and IHg = hydrogen index of gas


243

Por

GeneralGeneralGeneralPorosity—Wireline

Density and APS* Epithermal Neutron ToolPorosity Identification—Gas-Bearing Formation Por-25

(former CP-5a)

Density-derived porosity,φD (p.u.)

For shallow reservoirs, use blue curves.For deep reservoirs, use red curves.

0 10 20 30 40

APS epithermal neutron-derived porosity, φN (p.u.)

50

40

30

20

10

0

55

1515

2020

40

3030

40

80

35

35

2525

40

20

0

100Sxo

Sxo

80100

200

6040

60

Porosity

1010



244

Por

General

PurposeThis nomograph is used to estimate porosity in hydrocarbon-bearingformations by using density, neutron, and resistivity in the flushedzone (Rxo) logs. The density and neutron logs must be corrected forenvironmental effects and lithology before entry to the nomograph.The chart includes an approximate correction for excavation effect,but if hydrocarbon density (ρh) is <0.25 g /cm3 (gas), the chart maynot be accurate in some extreme cases:

■ very high values of porosity (>35 p.u.) coupled with medium to high values of hydrocarbon saturation (Shr)

■ Shr = 100% for medium to high values of porosity.

DescriptionConnect the apparent neutron porosity value on the appropriateneutron porosity scale (CNL* Compensated Neutron Log or sidewallneutron porosity [SNP] log) with the corrected apparent densityporosity on the density scale with a straight line. The intersectionpoint on the φ1 scale indicates the value of φ1.

Draw a line from the φ1 value to the origin (lower right corner) of the chart for Δφ versus Shr.

Enter the chart with Shr from (Shr = 1 – Sxo) and move verticallyupward to determine the porosity correction factor (Δφ) at the inter-section with the line from the φ1 scale.

This correction factor algebraically added to the porosity φ1 givesthe corrected porosity.

ExampleGiven: Corrected CNL apparent neutron porosity = 12 p.u.,

corrected apparent density porosity = 38 p.u., and Shr = 50%.

Find: Hydrocarbon-corrected porosity.

Answer: Enter the 12-p.u. φcor value on the CNL scale. A line fromthis value to 38 p.u. on the φDcor scale intersects the φ1

scale at 32.2 p.u. The intersection of a line from thisvalue to the graph origin and Shr = 50% is Δφ = –1.6 p.u.Hydrocarbon-corrected porosity: 32.2 – 1.6 = 30.6 p.u.

GeneralGeneralPorosity—Wireline

Density, Neutron, and Rxo LogsPorosity Identification in Hydrocarbon-Bearing Formation—Open Hole


245

Por

GeneralGeneralGeneralPorosity—Wireline

Density, Neutron, and Rxo LogsPorosity Identification in Hydrocarbon-Bearing Formation—Open Hole Por-26

(former CP-9)

–5

–4

–3

–2

–1

0100 80 60 40 20 0

Shr (%)

Δφ (p.u.)

φDcor

50

40

30

20

10

0

φ1

50

40

30

20

10

0

φcor

(SNP)

50

40

30

20

10

0

φcor

(CNL*)

50

40

30

20

10

0

(p.u.)



246

Por


Hydrocarbon Density EstimationPor-27

(former CP-10)

1.0

0.8

0.6

0.4

0.2

0

φCNLcor

φDcor

0 20 40 60 80 100

0.8ρh

0.7

0.6

0.5

0.40.3

0.20.10

Shr (%)

1.0

0.8

0.6

0.4

0.2

0 0 20 40 60 80 100

0.8ρh

0.7

0.6

0.5

0.4

0.3

0.20.10

Shr (%)

φSNPcor

φDcor


PurposeThis chart is used to estimate the hydrocarbon density (ρh) within a formation from corrected neutron and density porosity values.

DescriptionEnter the ratio of the sidewall neutron porosity (SNP) or CNL* Compensated Neutron Log neutron porosity and density porosity corrected for lithology and environmental effects (φSNPcor or φCNLcor /φDcor, respectively) on the y-axis and the

hydrocarbon saturation on the x-axis. The intersection point of thetwo values defines the density of the hydrocarbon.

ExampleGiven: Corrected CNL porosity = 15 p.u., corrected density

porosity = 25 p.u., and Shr = 30% (residual hydrocarbon).

Find: Hydrocarbon density.

Answer: Porosity ratio = 15/25 = 0.6. ρh = 0.29 g /cm3.


247

SatOH

GeneralSaturation—Wireline, LWD

Porosity Versus Formation Resistivity FactorOpen Hole SatOH-1

(former Por-1)

PurposeThis chart is used for a variety of conversions of the formation resistivity factor (FR) to porosity.

DescriptionThe most appropriate conversion is best determined by laboratorymeasurement or experience in the area. In the absence of thisknowledge, recommended relationships are the following:

■ Soft formations (Humble formula): FR = 0.62/φ2.51 or Fr = 0.81/φ2

■ Hard formations: FR = 1/φm with the appropriate cementationfactor (m).

ExampleGiven: Soft formation with Hard formation (m = 2) with

φ = 25 p.u. φ = 8 p.u.

Find: FR. FR.

Answer: FR = 13 (from chart). FR = 160 (from chart).

FR = 12.96 (calculated). FR = 156 (calculated).

2.5 5 10 20 50 100 200 500 1,000 2,000 5,000 10,000

2.5 5 10 20 50 100 200 500 1,000 2,000 5,000 10,00050

40

30

25

20

15

10987

6

5

4

3

2

1

Formation resistivity factor, FR

Porosity,φ (p.u.)

1.4

1.6

1.82.0

2.2

2.5

2.8

FR = 0.81φ2

FR = 1φ2

FR = 0.62φ2.15

FR = 1φmm

Fractures

Vugs orspherical pores

© Schlumberger


PurposeThis chart is used to identify how much of the measured porosity is isolated (vugs or moldic) or fractured porosity.

DescriptionThis chart is based on a simplified model that assumes no contribu-tion to formation conductivity from vugs and moldic porosity and thecementation exponent (m) of fractures is 1.0.

When the pores of a porous formation have an aspect ratio closeto 1 (vugs or moldic porosity), the value of m of the formation is usu-ally greater than 2. Fractured formations typically have a cementa-tion exponent less than 2.

Enter the chart with the porosity (φ) on the x-axis and m on the y-axis. The intersection point gives an estimate of either the amountof isolated porosity (φiso) or the amount of porosity resulting fromfractures (φfr).

ExampleGiven: φ = 10 p.u. and cementation exponent = 2.5.

Find: Intergranular (matrix) porosity.

Answer: Entering the chart with 10 p.u. and 2.5 gives an intersec-tion point of φiso = approximately 4.5 p.u. Intergranular porosity = 10 – 4.5 = 5.5 p.u.

Saturation—Wireline, LWD

Spherical and Fracture PorosityOpen Hole SatOH-2

(former Por-1a)

0.5 0.8 1 2 4 6 8 10 20 30 40 50Porosity, φ (p.u.)

3.0

2.5

2.0

1.5

1.0

Cementationexponent, m

Fractures

φ fr = 0.1

0.2

2.5

10.0

0.5

1.0

1.5 2.0

5.0

φiso = 0.5

1.01.5

2.55.0

7.510.0

12.5

2.0Isolated

pores

248

SatOH

© Schlumberger


SatOH

249


Saturation DeterminationOpen Hole

PurposeThis nomograph is used to solve the Archie water saturation equation:

whereSw = water saturation

Ro = resistivity of clean-water formation

Rt = true resistivity of the formation

FR = formation resistivity factor

Rw = formation water resistivity.

It should be used in clean (nonshaly) formations only.

DescriptionIf Ro is known, a straight line from the known Ro value through themeasured Rt value indicates the value of Sw. If Ro is unknown, it maybe determined by connecting Rw with FR or porosity (φ).

ExampleGiven: Rw = 0.05 ohm-m at formation temperature, φ = 20 p.u.

(FR = 25), and Rt = 10 ohm-m.

Find: Water saturation.

Answer: Enter the nomograph on the Rw scale at Rw = 0.05 ohm-m.

Draw a straight line from 0.05 through the porosity scaleat 20 p.u. to intersect the Ro scale.

From the intersection point of Ro = 1, draw a straight linethrough Rt = 10 ohm-m to intersect the Sw scale.

Sw = 31.5%.

SR

R

F R

Rwo

t

R w

t

= = ,



250

SatOH


Saturation DeterminationOpen Hole SatOH-3

(former Sw-1)

Rw(ohm-m)

Ro(ohm-m)

Ro = FRRw

Rt(ohm-m)

Sw(%)

φ(%)

FR

2,000

1,000800600400300200

100806050403020

108654

2.53

4

56789

10

15

20

253035404550

FR = 1φ2.0

m = 2.0

0.01

0.02

0.03

0.04

0.050.060.070.080.090.1

0.2

0.3

0.4

0.50.60.70.80.91

1.5

2

5

6

7

8

9

10111213141516

1820

25

30

40

50

60

70

80

90100

10,0008,0006,0005,0004,0003,0002,000

1,000800600500400300200

100806050403020

10865432

1.00.80.60.50.40.30.2

0.1

30

20181614121098765

4

3

21.81.61.41.21.00.90.80.70.60.5

0.4

0.3

0.20.180.160.140.120.10

Clean Formations, m = 2

Sw = RoRt

© Schlumberger


251

SatOH


Saturation DeterminationOpen Hole

PurposeThis chart is used to determine water saturation (Sw) in shaly orclean formations when knowledge of the porosity is unavailable. Itmay also be used to verify the water saturation determination fromanother interpretation method. The large chart assumes that themud filtrate saturation is

The small chart provides an Sxo correction when Sxo is known.However, water activity correction is not provided for the SP portionof the chart (see Chart SP-2).

Description Clean SandsEnter the large chart with the ratio of the resistivity of the flushedzone to the true formation resistivity (Rxo /Rt) on the y-axis and theratio of the resistivity of the mud filtrate to the resistivity of the for-mation water (Rmf /Rw) on the x-axis to find the water saturation ataverage residual oil saturation (Swa). If Rmf/Rw is unknown, the chartmay be entered with the spontaneous potential (SP) value and theformation temperature. If Sxo is known, move diagonally upward,parallel to the constant-Swa curves, to the right edge of the chart.Then, move horizontally to the known Sxo (or residual oil saturation[ROS], Sor) value to obtain the corrected value of Sw.

ExampleGiven: Rxo = 12 ohm-m, Rt = 2 ohm-m, Rmf/Rw = 20, and

Sor = 20%.

Find: Sw (after correction for ROS).

Answer: Enter the large chart at Rxo/Rt = 12/2 = 6 on the y-axis and Rmf/Rw = 20 on the x-axis. From the point ofintersection (labeled A), move diagonally to the right tointersect the chart edge and directly across to enter thesmall chart and intersect Sor = 20%.

Sw = 43%.

Description Shaly SandsEnter the chart with Rxo/Rt and the SP in the shaly sand (EPSP). Thepoint of intersection gives the Swa value. Draw a line from the chart’sorigin (the small circle located at Rxo/Rt = Rmf/Rm = 1) through thispoint to intersect with the value of static spontaneous potential (ESSP)to obtain a value of Rxo/Rt corrected for shaliness. This value of Rxo/Rt

versus Rmf/Rw is plotted to find Sw if Rmf/Rw is unknown because thepoint defined by Rxo/Rt and ESSP is a reasonable approximation of Sw.The small chart to the right can be used to further refine Sw if Sor isknown.

ExampleGiven: Rxo/Rt = 2.8, Rmf/Rw = 25, EPSP = –75 mV, ESSP = –120 mV,

and electrochemical SP coefficient (Kc) = 80 (formationtemperature = 150ºF).

Find: Sw and corrected value for Sor = 10%.

Answer: Enter the large chart at Rxo/Rt = 2.8 and the intersectionof EPSP = –75 mV at Kc = 80 from the chart below. A linefrom the origin through the intersection point (labeled B)intersects the –120-mV value of ESSP at Point C. Movehorizontally to the left to intersect Rmf/Rw = 25 at Point D.Then move diagonally to the right to intersect the righty-axis of the chart. Move horizontally to the small chart todetermine Sxo = 0.9%, Sw = 38%, and corrected Sw = 40%.


S SXO W= 5 .



252

SatOH


Saturation DeterminationOpen Hole SatOH-4

(former Sw-2)

50

40

30

20

10

8

65

4

3

2

1

0.8

0.60.5

0.4

0.3

0.2

0.1

0.08

75100150200

300

0.80.6 1.0 1.5 2.52 3 4 5 6 8 10 15 20 25 30 40 50 60

20 10 0 –20 –40 –60 –80 –100 –120 –140

0.80.6 1.0 1.5 2.52 3 4 5 6 8 10 15 20 25 40 50 6030

255075100150

80

0 10 20 30 40

1.0 0.9 0.8 0.7 0.6

80

70

60

50

40

30

25

20

15

10

60

50

40

25

30

20

15

70

90100

Rmf/Rw

Rxo

Rt

Rmf/RwKc

Temperature(°F)

Temperature(°C)

EPSP or ESSP (mV)

Sxo

Sw = Sxo (Swa)0.8

Sor (%)

Sw (%)

A

B

CD

10%

15%

20%

25%30%

40%

50%60%70%

S wa = 10

0%

EPSP = –Kc log – 2Kc log Rxo

Rt

Sxo

Sw

Sxo = S w5

Sxo = S w5

© Schlumberger


253

SatOH


Graphical Determination of Sw from Swt and SwbOpen Hole SatOH-5

(former Sw-14)

PurposeThis chart is used to drive a value of water saturation (Sw) correctedfor the bound-water volume in shale.

DescriptionThis is a graphical determination of Sw from the total water satura-tion (Swt) and the saturation of bound water (Swb):

Enter the y-axis with Swt and move horizontally to intersect the appropriate Swb curve. Read the value of Sw on the x-axis.

ExampleGiven: Swt = 45% and Swb = 10%.

Find: Sw.

Answer: Sw = 39.5%.

100

90

80

70

60

50

40

30

20

10

00 10 20 30 40 50 60 70 80 90 100

Sw (%)

Swt (%)

Swb

70%

60%

50%

40%

30%

20%

10%

0

SS S

Swwt wb

wb

=−

−1.

© Schlumberger


254

SatOH


Porosity and Gas Saturation in Empty HoleOpen Hole SatOH-6

(former Sw-11)

2.65

2.70

2.75

2.80

2.85

2.90

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

Neutronporosity

index(corrected

for lithology)

Matrix density,ρma (g/cm3)

2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

SandstoneLimy sandstoneLimestone

Dolomite

2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9

Apparent bulk density from density log, ρb (g/cm3)

Porosity, φ (p.u.)

Density and Hydrogen Index of Gas Assumed ZeroUse if noshale present

Use if nooil present

100

90

80

70

60

50

40

30

20

10

0Ga

s sat

urat

ion,

Sg (

%)

10,0004,0002,0001,000400300200150

100

706050

40

30

20

1514131211

Rt

Rw

PurposeThis chart is used to determine porosity (φ) and gas saturation (Sg)from the combination of density and neutron or from density andresistivity measurements.

DescriptionEnter from the point of intersection of the matrix density (ρma) andapparent bulk density (ρb). Move vertically upward to intersecteither neutron porosity (φN, corrected for lithology) or the ratio oftrue resistivity to connate water resistivity (Rt/Rw). This point definesthe actual porosity and Sg on the curves.

Oil saturation (So) can also be determined if all three measure-ments (density, neutron, and resistivity) are available. Find the valuesof φ and Sg as before, and then find the intersection of Rt/Rw with φto read the value of the total hydrocarbon saturation (Sh) on the saturation scale for use in the following equations:

So = Sh – Sg

Sw = 100 – Sh.

ExampleGiven: Limy sandstone (ρma = 2.68 g /cm3), ρb = 2.44 g /cm3,

φN = 9 p.u., Rt = 74 ohm-m, and Rw = 0.1 ohm-m.

Find: φ, Sg, Sh, So, and Sw.

Answer: First, find Rt/Rw = 74/0.1 = 740.

φ = 12 p.u. and Sg = 25%.

Sh = 70% (total hydrocarbon saturation).

So = 70 – 25 = 45%.

Sw = 100 – 70 = 30%.

© Schlumberger


255

SatOH

PurposeThis nomograph is used to define flushed zone saturation (Sxo) in the rock immediately adjacent to the borehole by using the EPTElectromagnetic Propagation Tool time measurement (tpl).

DescriptionUse of this chart requires knowledge of the reservoir lithology ormatrix propagation time (tpma), saturating water propagation time(tpw), porosity (φ), and expected hydrocarbon type. Enter the far-leftscale with tpl and move parallel to the diagonal lines to intersect theappropriate tpma value. From this point move horizontally to the right

edge of the scale grid. From this point, extend a straight line throughthe porosity scale to the center scale grid; again, move parallel to thediagonal lines to the appropriate tpma value and then horizontally tothe right edge of the grid scale. From this point, extend a straightline through the intersection of tpw and the hydrocarbon type pointto intersect the Sxo scale. For more information, see Reference 25.

Saturation—Wireline

EPT* Propagation TimeOpen Hole SatOH-7

(former Sxo-1)

7 8 9 10tpma (ns/m)

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

7 8 9 10tpma (ns/m)

Sxo(%)

Sandstone

50454035

3025

2015

105

tpl (ns/m)

10.9

100

90

80

70

60

50

40

30

20

10

0

53%

tpw (ns/m)21

25

30

3540

50

6070

8090

GasOilFo

rmat

ion po

rosit

y (%

)

Limestone

Dolomite

Sandstone Limestone

Dolomite*Mark of Schlumberger© Schlumberger


256

SatOH


EPT* AttenuationOpen Hole SatOH-8

(former Sxo-2)

Aw(dB/m)

AEPTcor(dB/m)

Sxo(%)

φ(p.u.)

6,000

5,000

4,000

3,000

2,000

1,000900800700600

500

400

300

200

1009080

2

34

68

1

10

20

3040

6080100

200

300400

6008001,000

5

6

7

8910

20

30

40

50

60

70

8090100

1

2

345

10

1520

3040

PurposeThis nomograph is used to determine the flushed zone saturation(Sxo) in the rock immediately adjacent to the borehole by using theEPT Electromagnetic Propagation Tool attenuation measurement. Itrequires knowledge of the saturating fluid (usually mud filtrate)attenuation (Aw), porosity (φ), and the EPT EATT attenuation(AEPTcor) corrected for spreading loss.

DescriptionThe value of Aw must first be determined. Chart Gen-16 is used toestimate Aw by using the equivalent water salinity and formationtemperature. EPT-D spreading loss is determined from the inset onChart Gen-16 based on the uncorrected EPT propagation time (tpl)measurement. The spreading loss correction algebraically added tothe EPT-D EATT attenuation measurement gives the corrected EPTattenuation (AEPTcor). These values are used with porosity on thenomograph to determine Sxo.

ExampleGiven: EATT = 250 dB/m, tpl = 10.9 ns/m, φ = 28 p.u., water salin-

ity = 20,000 ppm, and bottomhole temperature = 150ºF.

Find: Spreading loss (from Chart Gen-16 inset) and Sxo.

Answer: The spreading loss determined from the inset on Chart Gen-16 is –82 dB/m.

AEPTcor = 250 – 82 = 168 dB/m.

Aw (from Chart Gen-16) = 1,100 dB/m.

Enter the far-left scale at Aw = 1,100 dB/m and draw a straight line through φ = 28 p.u. on the next scale tointersect the median line. From this intersection point,draw a straight line through AEPTcor = 168 dB/m on thenext scale to intersect the Sxo value on the far-rightscale. Sxo = 56 p.u.



SatCH

PurposeThis chart is used to determine water saturation (Sw) from capturecross section, or sigma (Σ), measurements from the TDT* ThermalDecay Time pulsed neutron log.

DescriptionThis chart uses sigma water (Σw), matrix capture cross section (Σma),and porosity (φ) to determine water saturation in clean formations.The chart may be used in shaly formations if sigma shale (Σsh), thevolume fraction of shale in the formation (Vsh), and the porosity cor-rected for shale are known.

Thermal decay time (t and tsh in shale) is also shown on some of the chart scales because it is related to Σ.

ProcedureClean FormationThe Sw determination for a clean formation requires values knownfor Σma (based on lithology), φ, Σw from the NaCl salinity (see ChartGen-12 or Gen-13), and sigma hydrocarbon (Σh) (see Chart Gen-14).Enter the value of Σma on Scale B and draw a line to Pivot Point B.Enter Σlog on Scale B and draw Line b through the intersection ofLine a and the value of φ to intersect the sigma of the formationfluid (Σf) on Scale C. Draw Line 5 from Σf through the intersectionof Σh and Σw to determine the value of Sw on Scale D.

Example: Clean FormationGiven: Σlog = 20 c.u., Σma = 8 c.u. (sandstone) from TDT tool,

Σh = 18 c.u., Σw = 80 c.u. (150,000 ppm or mg/kg), and φ = 30 p.u.

Find: Sw.

Answer: Following the procedure for a clean formation, Sw = 43%.

ProcedureShaly FormationThe Sw determination in a shaly formation requires additional infor-mation: sigma shale (Σsh) read from the TDT log in adjacent shale,Vsh from porosity-log crossplot or gamma ray, shale porosity (φsh) readfrom a porosity log in adjacent shale, and the porosity corrected forshaliness (φshcor) with the relation for neutron and density logs in liquid-filled formations of φshcor = φlog – Vshφsh.

Enter the value of Σma on Scale B and draw Line 1 to intersectwith Pivot Point A. From the value of Σsh on Scale A, draw Line 2through the intersection of Line 1 and Vsh to determine the shale-corrected Σcor on Scale B. Draw Line 3 from Σcor to the value of Σma

on the scale to the left of Scale C. Enter Σlog on Scale B and drawLine 4 through the intersection of Line 3 and the value of φ to deter-mine Σf on Scale C. From Σf on Scale C, draw Line 5 through theintersection of Σh and Σw to determine Sw on Scale D.

ExampleGiven: Σlog = 25 c.u.

Σma = 8 c.u.

Σh = 18 c.u.

Σw = 80 c.u.

Σsh = 45 c.u.

φlog = 33 p.u.

φsh = 45 p.u.

Vsh = 0.2.

Find: φshcor and Sw.

Answer: First find the porosity corrected for shaliness, φshcor = 33 p.u. – (0.2 × 45 p.u.) = 24 p.u. This value is used for the φ point between Scales B and C.

Sw = 43%.


Capture Cross Section ToolCased Hole


257


258


Capture Cross Section ToolCased Hole SatCH-1

(former Sw-12)

2

4

100 90 80 70 60 50 40 30 20 10 0

3040

5060 70 80

90120

20

60

100

200

250 0 10 15 21

20 30 40 50 60 70 80 90 100 110 120

50 40 30 20 10 0

100 120 140 160 200 300 400

20 30 40 50 60

200 150 120 100 90 80

5

1015

2025

303540

45

0.1

0.5

Pivot point A

0.40.3

0.2

40

sh

sh (c.u.)

tsh ( s)

macor (c.u.)

t ( s)

ma (c.u.) f (c.u.)

h (c.u.)

Sw (%)

Formation watersalinity (ppm 1,000)

Sw = ( – ) – ( h – ) – sh ( sh – )

( w – h)

p.u.

a b

A

B

C

D

Pivot point B

1

5

3

0 5 10 15

© Schlumberger

SatCH


SatCH

PurposeThis chart is used to graphically interpret the TDT* Thermal DecayTime log. In one technique, applicable in shaly as well as cleansands, the apparent water capture cross section (Σwa) is plottedversus bound-water saturation (Swb) on a specially constructed grid todetermine the total water saturation (Swt).

DescriptionTo construct the grid, refer to the example chart on this page. Threefluid points must be located: free-water point (Σwf), hydrocarbonpoint (Σh), and a bound-water point (Σwb). The free- (or connate for-mation) water point is located on the left y-axis and can be obtainedfrom measurement of a formation water sample, from Charts Gen-12and Gen-13 if the water salinity is known, or from the TDT log ina clean water-bearing sand by using the following equation:

The hydrocarbon point is also located on the left y-axis of the grid.It can be determined from Chart Gen-14 based on the known orexpected hydrocarbon type.

The bound-water point (Swb) can be obtained from the TDT log in shale intervals also by using the Σwa equation. It is located on theright y-axis of the grid.

The distance between the free-water and hydrocarbon points islinearly divided into lines of constant water saturation drawn parallelto a straight line connecting the free-water and bound-water points.The Swt = 0% line originates from the hydrocarbon point, and the Swt = 100% line originates from the free-water point.

The value of Σwa from the equation is plotted versus Swb to giveSwt. The value of Swb can be estimated from the gamma ray or otherbound-water saturation estimator.

Once Swt and Swb are known, the water saturation of the reservoirrock exclusive of shale can be determined using

ExampleGiven: Σwf = 61 c.u. and Σh = 21 c.u. (medium-gravity oil with

modest GOR from Chart Gen-14), and Σwb = 76 c.u.(from TDT log in a shale interval and the preceding Eq. 1).

Find: Swt and Sw for Point 4.

Answer: Σwa = 54 c.u. (from Eq. 1) and Swb = 25% (from gamma ray).

Swt = 72% and Sw = 63% (from the preceding Sw

equation).

The grid can also be used to graphically determine watersaturation (Sw) in clean formations by crossplotting Σlog on the y-axis and porosity (φ) on the x-axis. The values of Σma and Sw neednot be known but must be constant over the interval studied. Theremust be some points from 100% water zones and a good variation inporosity. These water points define the Sw = 100% line; when extrap-olated, this line intersects the zero-porosity axis at Σma. The Sw = 0%line is drawn from Σma at φ = 0 p.u. to Σ = Σh at φ = 100 p.u. (or Σ = 1⁄2(Σma + Σh) at φ = 50 p.u.). The vertical distance from Sw = 0%to Sw = 100% is divided linearly to define lines of constant water saturation. The water saturation of any plotted point can thereby be determined.


Capture Cross Section Tool Cased Hole

0 20 40 60 80 100Swb (%)

40 44 48 52 56 60 64 68 72 76 80Gamma Ray

(gAPI)

wa (c.u.)

90

85

80

75

70

65

60

55

50

45

40

35

30

25

20

15

10

5

Free-waterpointwf = 61

Bound-waterpointwb = 76

100% water line

Hydrocarbonpointh = 21

86 5

4

3

2

1

7

S wt = S wb

80

70

60

50

40

30

20

0

10

90%

SS S

Swwt vb

wb

=−

−1.

∑ =∑ −∑

+ ∑wama

malog .

φ(1)

(2)



259


260

SatCH



Capture Cross Section ToolCased Hole SatCH-2

(former Sw-17)

or Swb

logor

wa

© Schlumberger


SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. Carbon/Oxygen Ratio—Open Hole

PurposeCharts SatCH-3 through SatCH-8 are presented for illustrative purposes only. They are used to ensure that the measured near- andfar-detector carbon/oxygen (C/O) ratio data are consistent with theinterpretation model. These example charts are drawn for specificcased and open holes and tool sizes to provide trapezoids for the to determination of oil saturation (So) and oil holdup (yo).

DescriptionKnown formation and borehole data define the expected C/O ratiovalues, which are determined in water saturation and boreholeholdup values ranging from 0 to 1. All log data for formations withporosity (φ) greater than 10 p.u. should be within the trapezoidalarea bounded by the limits of the So and yo values. If data plot

consistently outside the trapezoid, the interpretation model mayrequire revision.

The rectangle within each chart is constructed from four distinctpoints determined by the intersection of the near- and far-detectorC/O ratios: WW = water/water point

WO = water/oil point

OW = oil/water point

OO = oil/oil point.

RST Reservoir Saturation Tool processing then determines the watersaturation (Sw) of the formation.


261


262

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 6.125-in. BoreholeCarbon/Oxygen Ratio—Open Hole

φ = 30%, 6.125-in. Open Hole

Near-detector carbon/oxygen ratio

Far-detectorcarbon/oxygen

ratio

φ = 20%, 6.125-in. Open Hole

0.8

0.6

0.4

0.2

0

0 0.5 1.0

RST-A and RST-C, limestoneRST-A, quartz sandstoneRST-B and RST-D, limestoneRST-B, quartz sandstone



ratio

0.8

0.6

0.4

0.2

0

0 0.5 1.0


OO

OW

WO

WW

OO

OW

WO

OO

OW

WO

WO

OW

OO

WW

OW

OO

WO

WW

OW

OO

WO

WW

OO

OW

WO

WW

OO

OW

WO

WW

WWWW

SatCH-3(former RST-3)



263

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. BoreholeCarbon/Oxygen Ratio—Open Hole

SatCH-4

φ = 30%, 9.875-in. Open Hole

φ = 20%, 9.875-in. Open Hole1.5

1.0

0.5

0

0 1.5

RST-A and RST-C, limestoneRST-A, quartz sandstoneRST-Band RST-D, limestoneRST-B, quartz sandstone



ratio

0.5 1.0

1.5

1.0

0.5

0

0 1.5




ratio

0.5 1.0

OWWO

WW

WO

WW

OW

OW

OW

WO

WW

OW

OO

OO

OW

WW

WWWO

WO

WW

OO

OW

WW

OO

OW

WW

WO



264

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.125-in. Borehole with 4.5-in. Casing at 11.6 lbm/ftCarbon/Oxygen Ratio—Cased Hole


φ = 30%, 6.125-in. Borehole, 4.5-in. Casing at 11.6 lbm/ft



ratio

φ = 20%, 6.125-in. Borehole, 4.5-in. Casing at 11.6 lbm/ft

0.8

0.6

0.4

0.2

0

0 0.5 1.0




ratio

0.8

0.6

0.4

0.2

0

0 0.5 1.0


OO

OW

WO

WW

OW

OW

OW

WOWO

WOWW

WW

OO

OO

OO

OW

WO

WWWO

OWOO

OWWO

WW

WW

OWWO

WW

OO

OO

OO



265

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 7.875-in. Borehole with 5.5-in. Casing at 17 lbm/ftCarbon/Oxygen Ratio—Cased Hole

SatCH-6

φ = 30%, 7.875-in. Borehole, 5.5-in. Casing at 17 lbm/ft



ratio

φ = 20%, 7.875-in. Borehole, 5.5-in. Casing at 17 lbm/ft

0.8

0.6

0.4

0.2

0

0 0.5 1.0




ratio

0.8

0.6

0.4

0.2

0

0 0.5 1.0


WO

OO

OW

OO

OW

WO

WW

WW

OW

OO

WO

WW

WW

WO

OW

OO

OO

WWOO

OW

OW

WO

WW

WO

OO

OW

WO

WW

WWWO

OW

OO



266

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 8.5-in. Borehole with 7-in. Casing at 29 lbm/ftCarbon/Oxygen Ratio—Cased Hole




ratio

φ = 20%, 8.5-in. Borehole, 7-in. Casing at 29 lbm/ft

0.8

0.6

0.4

0.2

0

0 0.5 1.0




ratio


0.8

0.6

0.4

0.2

0

0 0.5 1.0

WO

WW

OW

OO


OW

OO

WO

WO

OO

OW

WW

WW

OO

OW

OO

OWWO

WW

OO

OW

WO

WW WO

WW

OW

OO

OW

OO

WW



267

SatCH


RST* Reservoir Saturation Tool—1.6875 in. and 2.5 in. in 9.875-in. Borehole with 7-in. Casing at 29 lbm/ftCarbon/Oxygen Ratio—Cased Hole





ratio


0.8

0.6

0.4

0.2

0

0 0.5 1.0




ratio

0.8

0.6

0.4

0.2

0

0 0.5 1.0


OO

OWWO

WW

OO

OWWO

WW

OO

OW

WO

WW

OO

OW

WW

WO

OW

OO

WW

WO

OW

OO

WO

WW

OO

OW

WWWW

WO

OW

OO

WO



268

Perm

GeneralGeneralPermeability

Permeability from Porosity and Water SaturationOpen Hole

Purpose Charts Perm-1 and Perm-2 are used to estimate the permeability ofshales, shaly sands, or other hydrocarbon-saturated intergranularrocks at irreducible water saturation (Swi).

DescriptionThe charts are based on empirical observations and are similar inform to a general expression proposed by Wyllie and Rose (1950)(see Reference 49):

Chart Perm-1 presents the results of one study for which theobserved relation was

Chart Perm-2 presents the results of another study:

The charts are valid only for zones at irreducible water saturation.Enter porosity (φ) and Swi on a chart. Their intersection defines

the intrinsic (absolute) rock permeability (k). Medium-gravity oil isassumed. If the saturating hydrocarbon is other than medium-gravityoil, a correction factor (C′) based on the fluid densities of water andhydrocarbons (ρw and ρh, respectively) and elevation above the free-water level (h) should be applied to the Swi value before it is enteredon the chart. The chart on this page provides the correction factorbased on the capillary pressure:

Charts Perm-1 and Perm-2 can be used to recognize zones at irre-ducible water saturation, for which the product φSwi from levels withinthe zone is generally constant and plots parallel to the φSwi lines.

ExampleGiven: φ = 23 p.u., Swi = 30%, gas saturation with ρh = 0.3 g/cm3

and ρw = 1.1 g/cm3, and h = 120 ft.

Find: Correction factor and k.

Answer: First, find pc to determine the correction factor if thezone of interest is not at irreducible water saturation:

Enter the correction factor chart with Swi = 30% to inter-sect the curve for pc = 40 (nearest to 42), for which thecorrection factor is 1.08. The corrected Swi value is Swi =1.08 × 30% = 32.4%.

Chart Perm-1: φS wi = 0.072% and k = 130 mD.

Chart Perm-2: φS wi = 0.072% and k = 65 mD.

ph

cw h=

−( )ρ ρ2 3.

.

kCS

Cwi

1 2/ .=⎛

⎝⎜⎞

⎠⎟+ ′φ

kSwi

1 22 25100/.

.=⎛

⎝⎜

⎞

⎠⎟

φ

kS

Sewi

wi

1 2 2701/ .φ =

−⎛

⎝⎜⎞

⎠⎟

ph

cw h=

−( )=

−( )=

ρ ρ2 3

120 1 1 0 3

2 342

.

. .

..

2.0

1.8

1.6

1.4

1.2

1.0

0.8 0 20 40 60 80 100

Irreducible water saturation, Swi (%)

Correction factor, C′

pc = 200

pc = 100

pc = 10pc = 0

pc = 40

pc =h(ρw – ρo)

2.3

(1)

(2)

(3)

(4)

© Schlumberger


269

Perm

General

Permeability from Porosity and Water SaturationOpen Hole

GeneralPermeability

Perm-1(former K-3)

60

50

40

30

20

10

0 0 5 10 15 20 25 30 35 40

Porosity, φ (p.u.)

Irreducible water

saturationabove

transitionzone,

Swi (%)

φSwi

0.12

0.10

0.08

0.06

0.04

0.02

0.01

5,0002,000

1,000500

200100

50

20

10

5

2

1.0

0.5

0.2

0.10.01

Permeability, k (mD)

© Schlumberger


270

Perm

General

This chart is used similarly to Chart Perm-1 for the relation

Permeability

Permeability from Porosity and Water SaturationOpen Hole Perm-2

(former K-4)

40

35

30

25

20

15

10

5

0 0 10 20 30 40 50 60 70 80 90 100

Irreducible water saturation above transition zone, Swi (%)

Porosity,φ (p.u.)

φSwi

Permeability, k (m

D)

5,000

1,000

2,000

500

200

5020

10

100

5

1

0.01

0.02

0.04

0.06

0.08

0.10

0.12

0.100.01

kS

Sewi

wi

1 2 2701/ .φ

−⎛

⎝⎜⎞

⎠⎟

© Schlumberger


271

Perm

PurposeThis chart is used to estimate ease of movement through a formationby a fluid.

DescriptionThe mobility-added slowness, which is the difference between theStoneley slowness and the calculated elastic Stoneley slowness, isplotted on the x-axis and the mobility of the fluid is on the y-axis. Themembrane impedance curves represent the effect that the mudcakehas on the determination of the mobility of the fluid in the formation.The membrane impedance is scaled in gigapascal per centimeter.

GeneralPermeability

Fluid Mobility Effect on Stoneley SlownessOpen Hole Perm-3

0.1

10

100

1,000 50 10 5 1

10,000

0.1 1 10 100

Membrane impedance

0 GPa/cm(no mudcake)

Fresh Mud at 600 Hz

Mobility-added slowness, S – Se (μs/ft)

Mobility(mD/cp)

© Schlumberger


General

272

Cement Bond Log—Casing Strength Interpretation—Cased Hole

PPuurrppoosseeThis chart is used to determine the decibel attenuation of casingfrom the measured cement bond log (CBL) amplitude and convert it to the compressive strength of bonded cement (either standard or foamed).

DDeessccrriippttiioonnThe amplitude of the first casing arrival is recorded by an acousticsignal-measuring device such as a sonic or cement bond tool. Thisamplitude value is a measure of decibel attenuation that can betranslated into a bond index (an indication of the percent of casingcement bonding) and the compressive strength (psi) of the cementat the time of logging.

Enter the chart on the y-axis with the log value of CBL amplitudeand move upward parallel to the 45° lines to intersect the appropri-ate casing size. At that point, move horizontally right to the attenua-tion scale on the right-hand y-axis. From this point, draw a linethrough the appropriate casing thickness value to intersect the com-pressive strength scale. The casing wall thickness is calculated bysubtracting the nominal inside diameter (ID) from the outsidediameter (OD) listed on the table for threaded nonupset casing and dividing the difference by 2.

EExxaammpplleeGiven: Log amplitude reading = 3.5 mV in zone of interest

and 1.0 mV in a well-bonded section (usually the lowestmillivolt value on the log), casing size = 7 in. at 29 lbm/ft, casing thickness = 0.41 in., and neat cement(not foamed).

Find: Compressive strength and bond index of the cement atthe time of logging.

Answer: Enter the 3.5-mV reading on the left y-axis of Chart Cem-1 and proceed to the 7-in. casing line.

Move horizontally to intersect the right-hand y-axis at 8.9 dB/ft.

Determine the casing thickness as (7 – 6.184)/2 = 0.816/2= 0.41 in. Draw a line from 8.9 dB/ft through the 0.41-in.casing thickness point to the compressive strength scale.

Cement compressive strength = 2,100 psi.

To find the bond index, determine the decibel attenuation of the lowest recorded log value by entering 1.0 mV on the left-hand y-axisand proceeding to the 7-in. casing line. Move horizontally to intersectthe right-hand y-axis at 12.3 dB/ft.

Divide the precisely determined decibel attenuation for the CBLamplitude in the zone of interest by this value for the lowest millivoltvalue: 8.9/12.3 = 72% bond index.

A 72% bond index means that 72% of the casing is bonded. This is not a well-bonded zone because a value of 80% bonding over a 10-ftinterval is historically considered well bonded. Although the loggingscale is a linear millivolts scale, the decibel attenuation scale is loga-rithmic. The millivolts log scale for the CBL value cannot rescaled in percent of bonding. If it were, the apparent percent bondingwould be 65% because most bond log scales are from 0 to 100 mVreading from left to right, over 10 divisions of track 1, or conversely100% to 0% cement bonding for 0 mV = 100% bonding and 100 mV = 0% bonding.

Cem

Cement Evaluation—Wireline


OD Weight Nominal Drift(in.) per ft† ID Diameter‡

(lbm) (in.) (in.)

10 33.00 9.384 9.228

103⁄4 32.75 10.192 10.03640.00 10.054 9.89840.50 10.050 9.89445.00 9.960 9.80445.50 9.950 9.79448.00 9.902 9.74651.00 9.850 9.69454.00 9.784 9.62855.50 9.760 9.604

113⁄4 38.00 11.150 10.99442.00 11.084 10.92847.00 11.000 10.84454.00 10.880 10.72460.00 10.772 10.616

12 40.00 11.384 11.228

13 40.00 12.438 12.282

133⁄8 48.00 12.715 12.559

16 55.00 15.375 15.187

185⁄8 78.00 17.855 17.667

20 90.00 19.190 19.002

211⁄2 92.50 20.710 20.522103.00 20.610 20.422114.00 20.510 20.322

241⁄2 100.50 23.750 23.562113.00 23.650 23.462

† Weight per foot in pounds is given for plain pipe (no threads or coupling).

‡ Drift diameter is the guaranteed minimum inside diameter of any part of the casing. Use drift diameter to determine the largest-diameter equipment that can be safely run inside the casing. Use inside diameter for volume capacity calculations.

273

Cem


Cement Bond Log—Casing StrengthInterpretation—Cased Hole


(lbm) (in.) (in.)

4 11.60 3.428 3.303

41⁄2 9.50 4.090 3.96511.60 4.000 3.87513.50 3.920 3.795

43⁄4 16.00 4.082 3.957

5 11.50 4.560 4.43513.00 4.494 4.36915.00 4.408 4.28317.70 4.300 4.17518.00 4.276 4.15121.00 4.154 4.029

51⁄2 13.00 5.044 4.91914.00 5.012 4.88715.00 4.974 4.84915.50 4.950 4.82517.00 4.892 4.76720.00 4.778 4.65323.00 4.670 4.545

53⁄4 14.00 5.290 5.16517.00 5.190 5.06519.50 5.090 4.96522.50 4.990 4.865

6 15.00 5.524 5.39916.00 5.500 5.37518.00 5.424 5.29920.00 5.352 5.22723.00 5.240 5.115

65⁄8 17.00 6.135 6.01020.00 6.049 5.92422.00 5.989 5.86424.00 5.921 5.79626.00 5.855 5.73026.80 5.837 5.71228.00 5.791 5.66629.00 5.761 5.63632.00 5.675 5.550



(lbm) (in.) (in.)

7 17.00 6.538 6.41320.00 6.456 6.33122.00 6.398 6.27323.00 6.366 6.24124.00 6.336 6.21126.00 6.276 6.15128.00 6.214 6.08929.00 6.184 6.05930.00 6.154 6.02932.00 6.094 5.96935.00 6.004 5.87938.00 5.920 5.79540.00 5.836 5.711

75⁄8 20.00 7.125 7.00024.00 7.025 6.90026.40 6.969 6.84429.70 6.875 6.75033.70 6.765 6.64039.00 6.625 6.500

85⁄8 24.00 8.097 7.97228.00 8.017 7.89232.00 7.921 7.79636.00 7.825 7.70038.00 7.775 7.65040.00 7.725 7.60043.00 7.651 7.52644.00 7.625 7.50049.00 7.511 7.386

9 34.00 8.290 8.16538.00 8.196 8.07140.00 8.150 8.02545.00 8.032 7.90755.00 7.812 7.687

95⁄8 29.30 9.063 8.90732.30 9.001 8.84536.00 8.921 8.76540.00 8.835 8.67943.50 8.755 8.59947.00 8.681 8.52553.50 8.535 8.379

Threaded Nonupset Casing


274

Cem

General

Cement Bond Log—Casing StrengthInterpretation—Cased Hole Cem-1

(former M-1)


Casing size (mm) Centered tool only, 3-ft [0.914-m] spacing

Casing size (in.)

(dB/ft)

Casing thickness(mm) (in.)

CBL amplitude(mV)

Attenuation(dB/m)

115

41/2 7

51/2 75/8

103/4

133/8

15

10

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

4

8

12

16

20

24

28

32

36

40

44

48

52

56

70

50

40

30

20

15

109876

5

4

3

2

1

0.5

0.2

8

7

6

5 0.2

0.3

0.4

0.5

0.6

7 in. at 29 lbm

140194

176273

340

Compressive strength(psi)

(mPa)

Standardcement

Foamed cement

6

5

4

3

2

1

1,000

800

500

300

200

100

30

25

20

15

10

5

3

2

1

0.5

0.3

4,000

3,000

2,000

1,000

500

250

100

50

© Schlumberger


Appendix A

275

Linear Grid


276

Appendix AAppendix A

9

8

7

6

5

4

3

2

1

9

8

7

6

5

4

3

2

1

Log-Linear Grid


Appendix A

277

Appendix A

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.60

0.70

0.80

0.901.0

1.2

1.41.61.82.0

2.5

3.0

4.05.06.0

8.010

1520304050100200

∞

5,000

4,000

3,000

2,500

2,000

1,500

1,000

500

400

300

200

150

100

50

25

10

0

Resistivity scale may bemultiplied by 10 for usein a higher range

Conductivity (mmho/m)

Resistivity(ohm-m)

ρb

φ

FR

For FR = 0.62φ2.15

Water Saturation Grid for Resistivity Versus Porosity


278

Appendix AAppendix A

2

2.5

3

3.5

4

4.5

5

6

7

8

910

12

14

16

20

2530

40

50

100

200

5001,0002,000

∞

500

400

300

250

200

150

100

50

40

30

20

10

5

0

Resistivity scale may bemultiplied by 10 for usein a higher range

Conductivity (mmho/m)

Resistivity(ohm-m)

ρb

φ

FR

For FR =1φ2

Water Saturation Grid for Resistivity Versus Porosity


Appendix B Logging Tool Response in Sedimentary Minerals

Name Formula ρlog φSNP φCNL φAPS† Δtc Δts Pe U ε tp Gamma Ray Σ(g/cm3) (p.u.) (p.u.) (p.u.) (μs/ft) (μs/ft) (farad/m) (ns/m) (gAPI Units) (c.u.)

Silicates

Quartz SiO2 2.64 –1 –2 –1 56.0 88.0 1.8 4.8 4.65 7.2 4.3

β-cristobalite SiO2 2.15 –2 –3 1.8 3.9 3.5

Opal (3.5% H2O) SiO2 (H2O)0.1209 2.13 4 2 58 1.8 3.7 5.0

Garnet‡ Fe3Al2(SiO4)3 4.31 3 7 11 48 45

Hornblende‡Ca2NaMg2Fe2

AlSi8O22(O,OH)23.20 4 8 43.8 81.5 6.0 19 18

Tourmaline NaMg3Al6B3Si6O2(OH)4 3.02 16 22 2.1 6.5 7450

Zircon ZrSiO4 4.50 –1 –3 69 311 6.9

Carbonates

Calcite CaCO3 2.71 0 0 0 49.0 88.4 5.1 13.8 7.5 9.1 7.1

Dolomite CaCO3MgCO3 2.85 2 1 1 44.0 72 3.1 9.0 6.8 8.7 4.7

Ankerite Ca(Mg,Fe)(CO3)2 2.86 0 1 9.3 27 22

Siderite FeCO3 3.89 5 12 3 47 15 57 6.8–7.5 8.8–9.1 52

Oxidates

Hematite Fe2O3 5.18 4 11 42.9 79.3 21 111 101

Magnetite Fe3O4 5.08 3 9 73 22 113 103

Goethite FeO(OH) 4.34 50+ 60+ 19 83 85

Limonite‡ FeO(OH)(H2O)2.05 3.59 50+ 60+ 56.9 102.6 13 47 9.9–10.9 10.5–11.0 71

Gibbsite Al(OH)3 2.49 50+ 60+ 1.1 23

Phosphates

Hydroxyapatite Ca5(PO4)3OH 3.17 5 8 42 5.8 18 9.6

Chlorapatite Ca5(PO4)3Cl 3.18 –1 –1 42 6.1 19 130

Fluorapatite Ca5(PO4)3F 3.21 –1 –2 42 5.8 19 8.5

Carbonapatite (Ca5(PO4)3)2CO3H2O 3.13 5 8 5.6 17 9.1

Feldspars—Alkali‡

Orthoclase KAlSi3O8 2.52 –2 –3 69 2.9 7.2 4.4–6.0 7.0–8.2 ~220 16

Anorthoclase KAlSi3O8 2.59 –2 –2 2.9 7.4 4.4–6.0 7.0–8.2 ~220 16

Microcline KAlSi3O8 2.53 –2 –3 2.9 7.2 4.4–6.0 7.0–8.2 ~220 16

Feldspars—Plagioclase‡

Albite NaAlSi3O8 2.59 –1 –2 –2 49 85 1.7 4.4 4.4–6.0 7.0–8.2 7.5

Anorthite CaAl2Si2O8 2.74 –1 –2 45 3.1 8.6 4.4–6.0 7.0–8.2 7.2

Micas‡

Muscovite KAl2(Si3AlO10)(OH)2 2.82 12 ~20 ~13 49 149 2.4 6.7 6.2–7.9 8.3–9.4 ~270 17

GlauconiteK0.7(Mg,Fe2,Al)

2.86 ~38 ~15 4.8 14 21(Si4,Al10)O2(OH)

Biotite K(Mg,Fe)3(AlSi3O10)(OH)2 ~2.99 ~11 ~21 ~11 50.8 224 6.3 19 4.8–6.0 7.2–8.1 ~275 30

Phlogopite KMg3(AlSi3O10)(OH)2 50 207 33

†APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLC)‡Mean value, which may vary for individual samples


279


280

Appendix B Logging Tool Response in Sedimentary Minerals

Name Formula ρlog φSNP φCNL φAPS† Δtc Δts Pe U ε tp Gamma Ray Σ(g/cm3) (p.u.) (p.u.) (p.u.) (μs/ft) (μs/ft) (farad/m) (ns/m) (gAPI Units) (c.u.)

Clays‡

Kaolinite Al4Si4O10(OH)8 2.41 34 ~37 ~34 1.8 4.4 ~5.8 ~8.0 80–130 14

Chlorite(Mg,Fe,Al)6(Si,Al)4

2.76 37 ~52 ~35 6.3 17 ~5.8 ~8.0 180–250 25O10(OH)8

IlliteK1–1.5Al4(Si7–6.5,Al1–1.5)

2.52 20 ~30 ~17 3.5 8.7 ~5.8 ~8.0 250–300 18O20(OH)4

Montmorillonite(Ca,Na)7(Al,Mg,Fe)4

2.12 ~60 ~60 2.0 4.0 ~5.8 ~8.0 150–200 14(Si,Al)8O20(OH)4(H2O)n

Evaporites

Halite NaCl 2.04 –2 –3 21 67.0 120 4.7 9.5 5.6–6.3 7.9–8.4 754

Anhydrite CaSO4 2.98 –1 –2 2 50 5.1 15 6.3 8.4 12

Gypsum CaSO4(H2O)2 2.35 50+ 60+ 60 52 4.0 9.4 4.1 6.8 19

Trona Na2CO3NaHCO3H2O 2.08 24 35 65 0.71 1.5 16

Tachhydrite CaCl2(MgCl2)2(H2O)12 1.66 50+ 60+ 92 3.8 6.4 406

Sylvite KCl 1.86 –2 –3 8.5 16 4.6–4.8 7.2–7.3 500+ 565

Carnalite KClMgCl2(H2O)6 1.57 41 60+ 4.1 6.4 ~220 369

Langbeinite K2SO4(MgSO4)2 2.82 –1 –2 3.6 10 ~290 24

PolyhaliteK2SO4Mg

2.79 14 25 4.3 12 ~200 24SO4(CaSO4)2(H2O)2

Kainite MgSO4KCl(H2O)3 2.12 40 60+ 3.5 7.4 ~245 195

Kieserite MgSO4(H2O) 2.59 38 43 1.8 4.7 14

Epsomite MgSO4(H2O)7 1.71 50+ 60+ 1.2 2.0 21

Bischofite MgCl2(H2O)6 1.54 50+ 60+ 100 2.6 4.0 323

Barite BaSO4 4.09 –1 –2 267 1090 6.8

Celestite SrSO4 3.79 –1 –1 55 209 7.9

Sulfides

Pyrite FeS2 4.99 –2 –3 39.2 62.1 17 85 90

Marcasite FeS2 4.87 –2 –3 17 83 88

Pyrrhotite Fe7S8 4.53 –2 –3 21 93 94

Sphalerite ZnS 3.85 –3 –3 36 138 7.8–8.1 9.3–9.5 25

Chalcopyrite CuFeS2 4.07 –2 –3 27 109 102

Galena PbS 6.39 –3 –3 1,630 10,400 13

Sulfur S 2.02 –2 –3 122 5.4 11 20

Coals

Anthracite CH0.358N0.009O0.022 1.47 37 38 105 0.16 0.23 8.7

Bituminous CH0.793N0.015O0.078 1.24 50+ 60+ 120 0.17 0.21 14

Lignite CH0.849N0.015O0.211 1.19 47 52 160 0.20 0.24 13

†APS* Accelerator Porosity Sonde porosity derived from near-to-array ratio (APLC)‡Mean value, which may vary for individual samples



Appendix C

281

Appendix C Acoustic Characteristics of Common Formations and Fluids

Nonporous Solids

Material Δt Sound Velocity Acoustic Impedance(µs/ft) (ft/s) (m/s) (MRayl)

Casing 57.0 17,500 5,334 41.60

Dolomite 43.5 23,000 7,010 20.19

Anhydrite 50.0 20,000 6,096 18.17

Limestone 47.6 21,000 6,400 17.34

Calcite 49.7 20,100 6,126 16.60

Quartz 52.9 18,900 5,760 15.21

Gypsum 52.6 19,000 5,791 13.61

Halite 66.6 15,000 4,572 9.33

Water-Saturated Porous Rock

Material Porosity Δt Sound Velocity Acoustic Impedance(%) (µs/ft) (ft/s) (m/s) (MRayl)

Dolomite 5–20 50.0–66.6 20,000–15,000 6,096–4,572 16.95–11.52

Limestone 5–20 54.0–76.9 18,500–13,000 5,639–3,962 14.83–9.43

Sandstone 5–20 62.5–86.9 16,000–11,500 4,877–3,505 12.58–8.20

Sand 20–35 86.9–111.1 11,500–9,000 3,505–2,743 8.20–6.0

Shale 58.8–143.0 17,000–7,000 5,181–2,133 12.0–4.3

Nonporous Solids

Material Δt Sound Velocity Acoustic Impedance(µs/ft) (ft/s) (m/s) (MRayl)

Water 208 4,800 1,463 1.46

Water + 10% NaCl 192.3 5,200 1,585 1.66

Water + 20% NaCl 181.8 5,500 1,676 1.84

Seawater 199 5,020 1,531 1.57

Kerosene 230 4,340 1,324 1.07

Air at 15 psi, 32°F [0°C] 920 1,088 331 0.0004

Air at 3,000 psi, 212°F [100°C] 780 1,280 390 0.1


282

Appendix D Conversions

Length

Multiply Centimeters Feet Inches Kilometers Nautical Meters Mils Miles Millimeters YardsNumber Miles

oftoObtain by

Centimeters 1 30.48 2.540 105 1.853 × 105 100 2.540 × 10–3 1.609 × 105 0.1 91.44

Feet 3.281 × 10–2 1 8.333 × 10–2 3281 6080.27 3.281 8.333 ×10–5 5280 3.281 × 10–3 3

Inches 0.3937 12 1 3.937 × 104 7.296 × 104 39.37 0.001 6.336 ×104 3.937 × 10–2 36

Kilometers 10–5 3.048 × 10–4 2.540 × 10–5 1 1.853 0.001 2.540 × 10–8 1.609 10–6 9.144 × 10–4

Nautical miles 1.645 × 10–4 0.5396 1 5.396 ×10–4 0.8684 4.934 ×10–4

Meters 0.01 0.3048 2.540 × 10–2 1000 1853 1 1609 0.001 0.9144

Mils 393.7 1.2 × 104 1000 3.937 × 107 3.937 × 104 1 39.37 3.6 × 104

Miles 6.214 × 10–6 1.894 × 10–4 1.578 × 10–5 0.6214 1.1516 6.214 × 10–4 1 6.214 × 10–7 5.682 × 10–4

Millimeters 10 304.8 25.40 105 1000 2.540 × 10–2 1 914.4

Yards 1.094 × 10–2 0.3333 2.778 × 10–2 1094 2027 1.094 2.778 × 10–5 1760 1.094 × 10–3 1

Area

Multiply Acres Circular Square Square Square Square Square Square Square SquareNumber Mils Centimeters Feet Inches Kilometers Meters Miles Millimeters Yards

oftoObtain by

Acres 1 2.296 × 10–5 247.1 2.471 × 10–4 640 2.066 × 10–4

Circular mils 1 1.973 × 105 1.833 × 108 1.273 × 106 1.973 ×109 1973

Squarecentimeters 5.067 × 10–6 1 929.0 6.452 1010 104 2.590 × 1010 0.01 8361

Square feet 4.356 × 104 1.076 × 10–3 1 6.944 × 10–3 1.076 × 107 10.76 2.788 × 107 1.076 × 10–5 9

Square inches 6,272,640 7.854 × 10–7 0.1550 144 1 1.550 × 109 1550 4.015 × 109 1.550 × 10–3 1296

Squarekilometers 4.047 × 10–3 10–10 9.290 × 10–8 6.452 × 10–10 1 10–6 2.590 10–12 8.361 × 10–7

Square meters 4047 0.0001 9.290 × 10–2 6.452 × 10–4 106 1 2.590 × 106 10–6 0.8361

Square miles 1.562 × 10–3 3.861 × 10–11 3.587 × 10–8 0.3861 3.861 × 10–7 1 3.861 × 10–13 3.228 × 10–7

Squaremillimeters 5.067 × 10–4 100 9.290 × 104 645.2 1012 106 1 8.361 × 105

Square yards 4840 1.196 × 10–4 0.1111 7.716 × 10–4 1.196 × 106 1.196 3.098 × 106 1.196 × 10–6 1


283


Volume

Multiply Bushels Cubic Cubic Cubic Cubic Cubic Gallons Liters Pints QuartsNumber (Dry) Centimeters Feet Inches Meters Yards (Liquid) (Liquid) (Liquid)

oftoObtain by

Bushels (dry) 1 0.8036 4.651 × 10–4 28.38 2.838 × 10–2

Cubiccentimeters 3.524 × 104 1 2.832 × 104 16.39 106 7.646 × 105 3785 1000 473.2 946.4

Cubic feet 1.2445 3.531 × 10–5 1 5.787 × 10–4 35.31 27 0.1337 3.531 × 10–2 1.671 × 10–2 3.342 × 10–2

Cubic inches 2150.4 6.102 × 10–2 1728 1 6.102 × 104 46,656 231 61.02 28.87 57.75

Cubic meters 3.524 × 10–2 10–6 2.832 × 10–2 1.639 × 10–5 1 0.7646 3.785 × 10–3 0.001 4.732 × 10–4 9.464 × 10–4

Cubic yards 1.308 × 10–6 3.704 × 10–2 2.143 × 10–5 1.308 1 4.951 × 10–3 1.308 × 10–3 6.189 × 10–4 1.238 × 10–3

Gallons(liquid) 2.642 × 10–4 7.481 4.329 × 10–3 264.2 202.0 1 0.2642 0.125 0.25

Liters 35.24 0.001 28.32 1.639 × 10–2 1000 764.6 3.785 1 0.4732 0.9464

Pints (liquid) 2.113 × 10–3 59.84 3.463 × 10–2 2113 1616 8 2.113 1 2

Quarts (liquid) 1.057 × 10–3 29.92 1.732 × 10–2 1057 807.9 4 1.057 0.5 1

Mass and Weight

Multiply Grains Grams Kilograms Milligrams Ounces† Pounds† Tons Tons TonsNumber (Long) (Metric) (Short)

oftoObtain by

Grains 1 15.43 1.543 × 104 1.543 × 10–2 437.5 7000

Grams 6.481 × 10–2 1 1000 0.001 28.35 453.6 1.016 × 106 106 9.072 × 105

Kilograms 6.481 × 10–5 0.001 1 10–6 2.835 × 10–2 0.4536 1016 1000 907.2

Milligrams 64.81 1000 106 1 2.835 × 104 4.536 × 105 1.016 × 109 109 9.072 × 108

Ounces† 2.286 × 10–3 3.527 × 10–2 35.27 3.527 × 10–5 1 16 3.584 × 104 3.527 × 104 3.2 × 104

Pounds† 1.429 × 10–4 2.205 × 10–3 2.205 2.205 × 10–6 6.250 × 10–2 1 2240 2205 2000

Tons (long) 9.842 × 10–7 9.842 × 10–4 9.842 × 10–10 2.790 × 10–5 4.464 × 10–4 1 0.9842 0.8929

Tons (metric) 10–6 0.001 10–9 2.835 × 10–5 4.536 × 10–4 1.016 1 0.9072

Tons (short) 1.102 × 10–6 1.102 × 10–3 1.102 × 10–9 3.125 × 10–5 0.0005 1.120 1.102 1

†Avoirdupois pounds and ounces


284


Density or Mass per Unit Volume

Multiply Grams per Kilograms Pounds per Pounds per Pounds perNumber Cubic per Cubic Foot Cubic Inch Gallon

of Centimeter Cubic MetertoObtain by

Grams per cubic centimeter 1 0.001 1.602 × 10–2 27.68 0.1198

Kilograms per cubic meter 1000 1 16.02 2.768 × 104 119.8

Pounds per cubic foot 62.43 6.243 × 10–2 1 1728 7.479

Pounds per cubic inch 3.613 × 10–2 3.613 × 10–5 5.787 × 10–4 1 4.329 × 10–3

Pounds per gallon 8.347 8.3 × 10–3 13.37 × 10–2 231.0 1

Pressure or Force per Unit Area

Multiply Atmospheres† Bayres or Centimeters Inches Inches Kilograms Pounds Pounds Tons (short) PascalsNumber Dynes per of Mercury of Mercury of Water per per per per

of Square at 0°C§ at 0°C§ at 4°C Square Square Foot Square Square Footto Centimeter‡ Meter†† Inch‡‡

Obtain by

Atmospheres† 1 9.869 × 10–7 1.316 × 10–2 3.342 × 10–2 2.458 × 10–3 9.678 × 10–5 4.725 × 10–4 6.804 × 10–2 0.9450 9.869 × 10–6

Bayres or dynesper square 1.013 × 106 1 1.333 × 104 3.386 × 104 2.491 × 10–3 98.07 478.8 6.895 × 104 9.576 × 105 10centimeter‡

Centimetersof mercury 76.00 7.501 × 10–5 1 2.540 0.1868 7.356 × 10–3 3.591 × 10–2 5.171 71.83 7.501 × 10–4

at 0°C§

Inchesof mercury 29.92 2.953 × 10–5 0.3937 1 7.355 × 10–2 2.896 × 10–3 1.414 × 10–2 2.036 28.28 2.953 × 10–4

at 0°C§

Inches of 406.8 4.015 × 10–4 5.354 13.60 1 3.937 × 10–2 0.1922 27.68 384.5 4.015 × 10–3

water at 4°C

Kilogramsper square 1.033 × 104 1.020 × 10–2 136.0 345.3 25.40 1 4.882 703.1 9765 0.1020meter††

Poundsper square 2117 2.089 × 10–3 27.85 70.73 5.204 0.2048 1 144 2000 2.089 × 10–2

foot

Pounds per 14.70 1.450 × 10–5 0.1934 0.4912 3.613 × 10–2 1.422 × 10–3 6.944 × 10–3 1 13.89 1.450 × 10–4

square inch‡‡

Tons (short) per 1.058 1.044 × 10–5 1.392 × 10–2 3.536 × 10–2 2.601 × 10–3 1.024 × 10–4 0.0005 0.072 1 1.044 × 10–5

square foot

Pascals 1.013 × 105 10–1 1.333 × 103 3.386 × 103 2.491 × 10–4 9.807 47.88 6.895 × 103 9.576 × 104 1

† One atmosphere (standard) = 76 cm of mercury at 0°C‡ Bar§ To convert height h of a column of mercury at t °C to the equivalent height h0 at 0°C, use h0 = h {1 – [(m – l) t / 1 + mt]}, where m = 0.0001818 and l = 18.4 × 10–6 if the

scale is engraved on brass; l = 8.5 × 10–6 if on glass. This assumes the scale is correct at 0°C; for other cases (any liquid) see International Critical Tables, Vol. 1, 68.†† 1 gram per square centimeter = 10 kilograms per square meter‡‡ psi = MPa × 145.038

psi/ft = 0.433 × g/cm3 = lbf/ft3/144 = lbf/gal/19.27

Temperature

°F 1.8°C + 32

°C 5⁄9 (°F – 32)

°R °F + 459.69

K °C + 273.16


Appendix E Symbols

Traditional Standard Standard Description Customary Unit or Relation StandardSymbol SPE Computer Reserve

and Symbol† Symbol‡

SPWLA†

a a ACT electrochemical activity equivalents/liter, moles/liter

a KR COER coefficient in FR – φ relation FR = KR/φm MR, a, C

A A AWT atomic weight amu

C C ECN conductivity (electrical logging) millimho per meter (mmho/m) σ

Cp Bcp CORCP sonic compaction correction factor φSVcor = BcpφSV Ccp

D D DPH depth ft, m y, H

d d DIA diameter in. D

E E EMF electromotive force mV V

F FR FACHR formation resistivity factor FR = KR/φm

G G GMF geometrical factor (multiplier) fG

H IH HYX hydrogen index iH

h h THK bed thickness, individual ft, m, in. d, e

I I –X index i

FFI IFf FFX free fluid index iFf

SI Isl SLX silt index Islt, isl, islt

Iφ PRX porosity index iφ

SPI Iφ2 PRXSE secondary porosity index iφ2

J Gp GMFP pseudogeometrical factor fGp

K Kc COEC electrochemical SP coefficient Ec = Kclog(aw/amf) Mc, Kec

k k PRM permeability, absolute (fluid flow) mD K

L L LTH length, path length ft, m, in. s, l

M M SAD slope, sonic interval transit time versus M = [(τf – τLOG)/(ρb – ρf)] × 0.01 mθDdensity × 0.01, in M–N plot

m m MXP porosity (cementation) exponent FR = KR/φm

N N SND slope, neutron porosity versus N = (φNf – φN)/(ρb – ρf) mφNDdensity, in M-N Plot

n n SXP saturation exponent Swn = FRRw/Rt

P C CNC salinity g/g, ppm c, n

p p PRS pressure psi, kg/cm2§, atm P

Pc Pc PRSCP capillary pressure psi, kg/cm2§, atm Pc, pc

Pe photoelectric cross section† SPE Letter and Computer Symbols Standard (1986).‡ Used only if conflict arises between standard symbols used in the same paper§ The unit of kilograms per square centimeter to be replaced in use by the SI metric unit of the pascal

†† “DEL” in the operator field and “RAD” in the main-quantity field‡‡ Suggested computer symbol

285


Appendix E Symbols

286

Traditional Standard Standard Description Customary Unit or Relation StandardSymbol SPE Computer Reserve

and Symbol† Symbol‡

SPWLA†

Qv shaliness (CEC per mL water) meq/mL

q fφ shd FIMSHD dispersed-shale volume fraction of φ imfshd, qintermatrix porosity

R R RES resistivity (electrical) ohm-m ρ, r

r r RAD radial distance from hole axis in. R

S S SAT saturation fraction or percent ρ, sof pore volume

T T TEM temperature °F, °C, K θ

BHT, Tbh Tbh TEMBH bottomhole temperature °F, °C, K θBH

FT, Tfm Tf TEMF formation temperature °F, °C, K

t t TIM time μs, s, min t

t t TAC interval transit time Δt

U volumetric cross section barns/cm3

v v VAC velocity (acoustic) ft /s, m/s V, u

V V VOL volume cm3, ft3, etc. v

V V VLF volume fraction fv, Fv

Z Z ANM atomic number

α αSP REDSP SP reduction factor

γ γ SPG specific gravity (ρ/ρw or ρg/ρair) s, Fs

φ φ POR porosity fraction or percentage f, εof bulk volume, p.u.

φ1 PORPR primary porosity fraction or percentage f1, e1of bulk volume, p.u.

φ2 PORSE secondary porosity fraction or percentage f2, e2of bulk volume, p.u.

φig PORIG intergranular porosity φig = (Vb – Vgr)/Vb fig, εig

φz, φim φim PORIM intermatrix porosity φim = (Vb – Vma)/Vb fim, εim

Δr Δr DELRAD†† radial distance (increment) in. ΔR

Δt t TAC sonic interval transit time μs/ft Δt

ΔφNex DELPORNX‡‡ excavation effect p.u.

λ Kani COEANI coefficient of anisotropy Mani

ρ ρ DEN density g/cm3 D

Σ Σ XST neutron capture cross section c.u., cm–1 SXSTMAC macroscopic

τ τdN TIMDN thermal neutron decay time μs tdn† SPE Letter and Computer Symbols Standard (1986).‡ Used only if conflict arises between standard symbols used in the same paper§ The unit of kilograms per square centimeter is to be replaced in use by the SI metric unit of the pascal.

†† “DEL” in the operator field and “RAD” in the main-quantity field‡‡ Suggested computer symbol


Appendix E

287

Appendix F Subscripts

Traditional Standard Standard Explanation Example StandardSubscript SPE Computer Reserve

and Subscript† Subscript‡

SPWLA†

a LOG L apparent from log reading RLOG, RLL log(or use tool description subscript)

a a A apparent (general) Ra ap

abs cap C absorption, capture Σcap

anh anh AH anhydrite

b b B bulk ρb B, t

bh bh BH bottomhole Tbh w, BH

clay cl CL clay Vcl cla

cor, c cor COR corrected tcor

c c C electrochemical Ec ec

cp cp CP compaction Bcp

D D D density log d

dis shd SHD dispersed shale Vshd

dol dol DL dolomite tdol

e, eq eq EV equivalent Rweq, Rmfeq EV

f, fluid f F fluid ρf fl

fm f F formation (rock) Tf fm

g, gas g G gas Sg G

gr GR grain ρgr

gxo gxo GXO gas in flushed zone Sgxo GXO

gyp gyp GY gypsum ρgyp

h h H hole dh H

h h H hydrocarbon ρh H

hr hr HR residual hydrocarbon Shr

i i I invaded zone (inner boundary) di I

ig ig IG intergranular (incl. disp. and str. shale) φ ig

im, z im IM intermatrix (incl. disp. shale) φ im

int int I intrinsic (as opposed to log value) Σ int

irr i IR irreducible Swi ir, i

J j J liquid junction Ej ι

k k K electrokinetic Ek ek

l L log tpl log

lam l LAM lamination, laminated Vshl L

lim lim LM limiting value φ lim

liq L L liquid ρL l† SPE Letter and Computer Symbols Standard (1986).‡ Used only if conflict arises between standard symbols used in the same paper


Appendix E

288




SPWLA†

log LOG L log values tLOG log

ls ls LS limestone t ls lst

m m M mud Rm

max max MX maximum φmax

ma ma MA matrix tma

mc mc MC mudcake Rmc

mf mf MF mud filtrate Rmf

mfa mfa MFA mud filtrate, apparent Rmfa

min min MN minimum value

ni noninvaded zone Rni

o o O oil (except with resistivity) So N

or or OR residual oil Sor

o, 0 (zero) 0 (zero) ZR 100-percent water saturated F0 zr

p propagation tpw

PSP pSP PSP pseudostatic SP EpSP

pri 1 (one) PR primary φ1 p, pri

r r R relative kr o, krw R

r r R residual Sor, Shr R

s s S adjacent (surrounding) formation Rs

sd sd SD sand sa

ss ss SS sandstone sst

sec 2 SE secondary φ2 s, sec

sh sh SH shale Vsh sha

silt sl SL silt Isl slt

SP SP SP spontaneous potential ESP sp

SSP SSP SSP static spontaneous potential ESSP

str sh st SH ST structural shale Vshst s

t, ni t T true (as opposed to apparent) Rt tr

T t T total Ct T

w w W water, formation water Sw W

wa wa WA formation water, apparent Rwa Wap

wf wf WF well flowing conditions pwf f

ws ws WS well static conditions pws s

xo xo XO flushed zone Rxo

z, im im IM intermatrix φ im† SPE Letter and Computer Symbols Standard (1986).‡ Used only if conflict arises between standard symbols used in the same paper


Appendix E

289




SPWLA†

0 (zero) 0 (zero) ZR 100 percent water saturated R0 zr

AD RAD from CDR attenuation deep RAD

D D D from density log φD d

GG GG from gamma-gamma log φGG gg

IL I I from induction log RI i

ILD ID ID from deep induction log RID id

ILM IM IM from medium induction log RIM im

LL LL (also LL3, LL from laterolog RLL ll

LL8, etc.) (also LL3, LL7, LL8, LLD, LLS)

N N N from normal resistivity log RN n

N N N from neutron log φN n

PS RPS from CDR phase-shift shallow RPS

16", 16"N from 16-in. normal Log R16"

1" × 1" from 1-in. by 1-in. microinverse (MI) R1" × 1"

2" from 2-in. micronormal (MN) R2"† SPE Letter and Computer Symbols Standard (1986).‡ Used only if conflict arises between standard symbols used in the same paper


Appendix F

290

Appendix G Unit Abbreviations

These unit abbreviations, which are based on those adopted by theSociety of Petroleum Engineers (SPE), are appropriate for most publi-cations. However, an accepted industry standard may be used instead.For instance, in the drilling field, ppg may be more common thanlbm/gal when referring to pounds per gallon.

In some instances, two abbreviations are given: customary andmetric. When using the International System of Units (SI), or metric,abbreviations, use the one designated for metric (e.g., m3/h instead ofm3/hr). The use of SI prefix symbols and prefix names with customaryunit abbreviations and names, although common, is not preferred(e.g., 1,000 lbf instead of klbf).

Unit abbreviations are followed by a period only when the abbrevia-tion forms a word (for example, in. for inch).

acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spell out

acre-foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . acre-ft

ampere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A

ampere-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-hr

angstrom unit (10–8 cm). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A

atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . atm

atomic mass unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . amu

barrel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bbl

barrels of fluid per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BFPD

barrels of liquid per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BLPD

barrels of oil per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BOPD

barrels of water per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BWPD

barrels per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B/D

barrels per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bbl/min

billion cubic feet (billion = 109) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bcf

billion cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bcf/D

billion standard cubic feet per day . . . . . . . . . . . Use Bcf/D instead of Bscf/D (see “standard cubic foot”)

bits per inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bpi

bits per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bps

brake horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . bhp

British thermal unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Btu

capture unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c.u.

centimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm

centipoise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cp

centistoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cSt

coulomb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C

counts per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cps

cubic centimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm3

cubic foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3

cubic feet per barrel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/bbl

cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/D

cubic feet per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/min

cubic feet per pound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/lbm

cubic feet per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft3/s

cubic inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.3

cubic meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m3

cubic millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm3

cubic yard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yd3

curie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ci

dalton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Da

darcy, darcies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D

day (customary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D

day (metric). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . d

dead-weight ton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DWT

decibel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dB

degree (American Petroleum Institute). . . . . . . . . . . . . . . . . . . . . . . . . . . °API

degree Celsius . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °C

degree Fahrenheit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °F

degree Kelvin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See “kelvin”

degree Rankine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . °R

dots per inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dpi

electromotive force. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . emf

electron volt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . eV

farad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F

feet per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/min

feet per second. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft/s

foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft

foot-pound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft-lbf

gallon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal

gallons per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal/D

gallons per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gal/min

gigabyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gbyte

gigahertz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GHz

gigapascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GPa

gigawatt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GW

gram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . g

hertz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hz

horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hp

horsepower-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hp-hr

hour (customary). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hr

hour (metric). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . h

hydraulic horsepower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hhp

inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.

inches per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in./s

joule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J

kelvin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K

kilobyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kB

kilogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kg

kilogram-meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kg-m

kilohertz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kHz

kilojoule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kJ

kilometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . km

kilopascal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kPa

kilopound (force) (1,000 lbf) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . klbf

kilovolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kV

kilowatt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kW

kilowatt-hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kW-hr

kips per square inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ksi


Appendix G

lines per inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lpi

lines per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lpm

lines per second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lps

liter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L

megabyte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MB

megagram (metric ton) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mg

megahertz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MHz

megajoule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MJ

meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m

metric ton (tonne) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t or Mg

mho per meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ω/m

microsecond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . µs

mile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spell out

miles per hour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mph

milliamperes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mA

millicurie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mCi

millidarcy, millidarcies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mD

milliequivalent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . meq

milligram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mg

milliliter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mL

millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm

millimho . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mmho

million cubic feet (million = 106) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MMcf

million cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MMcf/D

million electron volts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MeV

million standard cubic feet per day . . . . . . . Use MMcf/D instead of MMscf/D(see “standard cubic foot”)

milliPascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mPa

millisecond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ms

millisiemens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mS

millivolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mV

mils per year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mil/yr

minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . min

mole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mol

nanosecond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ns

newton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N

ohm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm

ohm-centimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm-cm

ohm-meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ohm-m

ounce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . oz

parts per million . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ppm

pascal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pa

picofarad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pF

pint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . pt

porosity unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . p.u.

pound (force) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbf

pound (mass) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm

pound per cubic foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm/ft3

pound per gallon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lbm/gal

pounds of proppant added . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ppa

pounds per square inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psi

pounds per square inch absolute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psia

pounds per square inch gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . psig

pounds per thousand barrels (salt content). . . . . . . . . . . . . . . . . . . . . . . . . ptb

quart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . qt

reservoir barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . res bbl

reservoir barrel per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RB/D

revolutions per minute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . rpm

saturation unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s.u.

second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s

shots per foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . spf

specific gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sg

square . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sq

square centimeter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cm2

square foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ft2

square inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . in.2

square meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m2

square mile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . sq mile

square millimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . mm2

standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . std

standard cubic feet per day. . . . . . . . . . . . . . . . . . . . Use ft3/D instead of scf/D(see “standard cubic foot”)

standard cubic foot . . . . . . . . . . . . . . . . . Use ft3 or cf as specified on this list.Do not use scf unless the standard

conditions at which the measurement was made are specified.

The straight volumetric conversion factoris 1 ft3 = 0.02831685 m3

stock-tank barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STB

stock-tank barrels per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . STB/D

stoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . St

teragram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tg

thousand cubic feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mcf

thousand cubic feet per day. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mcf/D

thousand pounds per square inch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . kpsi

thousand standard cubic feet per day . . . . . . . . Use Mcf/D instead of Mscf/D (see “standard cubic foot”)

tonne (metric ton). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . t

trillion cubic feet (trillion = 1012) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tcf

trillion cubic feet per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tcf/D

volt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V

volume percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vol%

volume per volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vol/vol

watt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W

weight percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . wt%

yard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yd

year (customary) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . yr

year (metric) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a

Ω

Appendix G

291

Unit Abbreviations


Appendix G

292

Appendix H References

1. Overton HL and Lipson LB: “A Correlation of the ElectricalProperties of Drilling Fluids with Solids Content,” Transactions,AIME (1958) ��

2. Desai KP and Moore EJ: “Equivalent NaCl Concentrations fromIonic Concentrations,” The Log Analyst (May–June 1969).

3. Gondouin M, Tixier MP, and Simard GL: “An Experimental Studyon the Influence of the Chemical Composition of Electrolytes onthe SP Curve,” JPT (February 1957).

4. Segesman FF: “New SP Correction Charts,” Geophysics(December 1962) �� No. 6, PI.

5. Alger RP, Locke S, Nagel WA, and Sherman H: “The Dual SpacingNeutron Log–CNL,” paper SPE 3565, presented at the 46th SPEAnnual Meeting, New Orleans, Louisiana, USA (1971).

6. Segesman FF and Liu OYH: “The Excavation Effect,”Transactions of the SPWLA 12th Annual Logging Symposium(1971).

7. Burke JA, Campbell RL Jr, and Schmidt AW: “The Litho-PorosityCrossplot,” Transactions of the SPWLA 10th Annual LoggingSymposium (1969), paper Y.

8. Clavier C and Rust DH: “MID-PLOT: A New LithologyTechnique,” The Log Analyst (November–December 1976).

9. Tixier MP, Alger RP, Biggs WP, and Carpenter BN: “DualInduction-Laterolog: A New Tool for Resistivity Analysis,” paper713, presented at the 38th SPE Annual Meeting, New Orleans,Louisiana, USA (1963).

10. Wahl JS, Nelligan WB, Frentrop AH, Johnstone CW, andSchwartz RJ: “The Thermal Neutron Decay Time Log,” SPEJ(December 1970).

11. Clavier C, Hoyle WR, and Meunier D: “QuantitativeInterpretation of Thermal Neutron Decay Time Logs, Part I andII,” JPT (June 1971).

12. Poupon A, Loy ME, and Tixier MP: “A Contribution to ElectricalLog Interpretation in Shaly Sands,” JPT (June 1954).

13. Tixier MP, Alger RP, and Tanguy DR: “New Developments inInduction and Sonic Logging,” paper 1300G, presented at the34th SPE Annual Meeting, Dallas, Texas, USA (1959).

14. Rodermund CG, Alger RP, and Tittman J: “Logging EmptyHoles,” OGJ (June 1961).

15. Tixier MP: “Evaluation of Permeability from Electric LogResistivity Gradients,” OGJ (June 1949).

16. Morris RL and Biggs WP: “Using Log-Derived Values of WaterSaturation and Porosity,” Transactions of the SPWLA 8thAnnual Logging Symposium (1967).

17. Timur A: “An Investigation of Permeability, Porosity, andResidual Water Saturation Relationships for SandstoneReservoirs,” The Log Analyst (July–August 1968).

18. Wyllie MRJ, Gregory AR, and Gardner GHF: “Elastic WaveVelocities in Heterogeneous and Porous Media,” Geophysics(January 1956) �� No. 1.

19. Tixier MP, Alger RP, and Doh CA: “Sonic Logging,” JPT (May1959) �� No. 5.

20. Raymer LL, Hunt ER, and Gardner JS: “An Improved SonicTransit Time-to-Porosity Transform,” Transactions of theSPWLA 21st Annual Logging Symposium (1980).

21. Coates GR and Dumanoir JR: “A New Approach to ImprovedLog-Derived Permeability,” The Log Analyst (January–February1974).

22. Raymer LL: “Elevation and Hydrocarbon Density Correction forLog-Derived Permeability Relationships,” The Log Analyst(May–June 1981).

23. Westaway P, Hertzog R, and Plasic RE: “The GammaSpectrometer Tool, Inelastic and Capture Gamma RaySpectroscopy for Reservoir Analysis,” paper SPE 9461,presented at the 55th SPE Annual Technical Conferenceand Exhibition, Dallas, Texas, USA (1980).

24. Quirein JA, Gardner JS, and Watson JT: “Combined NaturalGamma Ray Spectral/Litho-Density Measurements Applied toComplex Lithologies,” paper SPE 11143, presented at the 57thSPE Annual Technical Conference and Exhibition, New Orleans,Louisiana, USA (1982).

25. Harton RP, Hazen GA, Rau RN, and Best DL: “ElectromagneticPropagation Logging: Advances in Technique andInterpretation,” paper SPE 9267, presented at the 55th SPEAnnual Technical Conference and Exhibition, Dallas, Texas,USA (1980).

26. Serra O, Baldwin JL, and Quirein JA: “Theory and PracticalApplication of Natural Gamma Ray Spectrometry,” Transactionsof the SPWLA 21st Annual Logging Symposium (1980).

27. Gardner JS and Dumanoir JL: “Litho-Density LogInterpretation,” Transactions of the SPWLA 21st AnnualLogging Symposium (1980).

28. Edmondson H and Raymer LL: “Radioactivity LoggingParameters for Common Minerals,” Transactions of the SPWLA20th Annual Logging Symposium (1979).

29. Barber TD: “Real-Time Environmental Corrections for thePhasor Dual Induction Tool,” Transactions of the SPWLA 26thAnnual Logging Symposium (1985).

30. Roscoe BA and Grau J: “Response of the Carbon-OxygenMeasurement for an Inelastic Gamma Ray Spectroscopy Tool,”paper SPE 14460, presented at the 60th SPE Annual TechnicalConference and Exhibition, Las Vegas, Nevada, USA (1985).


Appendix H

31. Freedman R and Grove G: “Interpretation of EPT-G Logs in thePresence of Mudcakes,” paper presented at the 63rd SPEAnnual Technical Conference and Exhibition, Houston, Texas,USA (1988).

32. Gilchrist WA Jr, Galford JE, Flaum C, Soran PD, and Gardner JS:“Improved Environmental Corrections for CompensatedNeutron Logs,” paper SPE 15540, presented at the 61st SPEAnnual Technical Conference and Exhibition, New Orleans,Louisiana, USA (1986).

33. Tabanou JR, Glowinski R, and Rouault GF: “SP Deconvolutionand Quantitative Interpretation in Shaly Sands,” Transactionsof the SPWLA 28th Annual Logging Symposium (1987).

34. Kienitz C, Flaum C, Olesen J-R, and Barber T: “Accurate Loggingin Large Boreholes,” Transactions of the SPWLA 27th AnnualLogging Symposium (1986).

35. Galford JE, Flaum C, Gilchrist WA Jr, and Duckett SW:“Enhanced Resolution Processing of Compensated NeutronLogs, paper SPE 15541, presented at the 61st SPE AnnualTechnical Conference and Exhibition, New Orleans, Louisiana,USA (1986).

36. Lowe TA and Dunlap HF: “Estimation of Mud Filtrate Resistivityin Fresh Water Drilling Muds,” The Log Analyst (March–April1986).

37. Clark B, Luling MG, Jundt J, Ross M, and Best D: “A Dual DepthResistivity for FEWD,” Transactions of the SPWLA 29th AnnualLogging Symposium (1988).

38. Ellis DV, Flaum C, Galford JE, and Scott HD: “The Effect ofFormation Absorption on the Thermal Neutron PorosityMeasurement,” paper presented at the 62nd SPE AnnualTechnical Conference and Exhibition, Dallas, Texas, USA (1987).

39. Watfa M and Nurmi R: “Calculation of Saturation, SecondaryPorosity and Producibility in Complex Middle East CarbonateReservoirs,” Transactions of the SPWLA 28th Annual LoggingSymposium (1987).

40. Brie A, Johnson DL, and Nurmi RD: “Effect of Spherical Poreson Sonic and Resistivity Measurements,” Transactions of theSPWLA 26th Annual Logging Symposium (1985).

41. Serra O: Element Mineral Rock Catalog, Schlumberger (1990).

42. Grove GP and Minerbo GN: “An Adaptive Borehole CorrectionScheme for Array Induction Tools,” Transactions of the SPWLA32nd Annual Logging Symposium, Midland, Texas, USA, June16–19, 1991, paper F.

43. Barber T and Rosthal R: “Using a Multiarray Induction Tool toAchieve Logs with Minimum Environmental Effects,” paper SPE22725, presented at SPE Annual Technical Conference andExhibition, Dallas, Texas, USA, October 6–9, 1991.

44. Moran JH: “Induction Method and Apparatus for InvestigatingEarth Formations Utilizing Two Quadrature Phase Components ofa Detected Signal,” US Patent No. 3,147,429 (September 1, 1964).

45. Barber TD: “Phasor Processing of Induction Logs IncludingShoulder and Skin Effect Correction,” US Patent No. 4,513,376(September 11, 1984).

46. Barber T et al.: “Interpretation of Multiarray Induction Logs in Invaded Formations at High Relative Dip Angles,” The LogAnalyst 40, no. 3 (May–June 1990): 202–217.

47. Anderson BI and Barber TD: Induction Logging, Sugar Land,Texas, USA: Schlumberger Wireline & Testing, 1995 (SMP-7056).

48. Gerritsma CJ, Oosting PH, and Trappeniers NJ: “Proton Spin-Lattice Relaxation and Self Diffusion in Methanes, II,” Physica51 (1971), 381–394.

49. Wyllie MRJ and Rose WD: “Some Theoretical ConsiderationsRelated to the Quantitative Evaluation of the PhysicalCharacteristics of Reservoir Rock from Electrical Log Data,”JPT 2 (1950), 189.

Appendix H

293

References



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