Cement Evaluation with the UltraSonic Imager Andrew Hayman Dominique Guillot Sean Harrera Bernard Piot Gilles Rouault Bob Butsch Charles Morris Matteo

Cement Evaluation with the UltraSonic

Imager

Andrew Hayman Dominique Guillot Sean Harrera Bernard Piot Gilles Rouault Bob Butsch Charles Morris Matteo Loizzo

Jan. 2000

2/SRPC/


Imager

• Introduction

• Acoustic methods basics

• USI tool basics

• USI QC

• USI and CBL/VDL interpretation

• Integrating logs and cementing data

3/SRPC/


Imager

• Introduction

– Cementing Problems

– Evaluation methods


• USI tool basics

• USI QC



4/SRPC/

Objectives of cementing

• Provide complete isolation of zones (Hydraulic isolation)

• Support the casing and protect it from corrosion

5/SRPC/

The ideal wellbore

Thin, impermeable mud filter cake (not gelled or unconsolidated)

BHST at top ofcement>BHCT at TD

Annular gapMinimum: 3/4-in.Ideal: 1 1/2-in.

Properly conditioned hole and mud

Gaugediameter

No sloughing

Uniform as possible( no washouts or restrictions)

NO FLOWNO LOSSES

Casing centered in borehole

Accurate BHST and BHCT

6/SRPC/

Cementing Problems• Placement (mud removal)

– Poor centralization -> channel

– Incorrect flow regime -> channel, mud film, fluid contamination

• After placement before setting– Slurry segregation: free water and/or

settling

– Formation fluid invasion: gas or water

– Debonding (microannulus)

– Water loss

– Permeable formation interactions

• After placement once set– Debonding

– Mechanical failure (Pressure, temperature, drilling, tectonics,..)

7/SRPC/

Cement Evaluation Methods

• Hydraulic testing

• Temperature, nuclear (cement top)

• Acoustic

– Sonic (CBL/VDL, CBT): omnidirectional

– Ultrasonic (USI): high resolution image

• Analysis of cement job data

8/SRPC/


Imager

• Introduction


– Acoustic impedance

– CBL/VDL

– USI

• USI tool basics

• USI QC



9/SRPC/

Acoustic impedance

Z MRayl

0

2

4

6

8

Heavymud

Water

Oil

Gas

Neat

Light

Cement Contaminated

Cement

Setting

slurry

Liquid

Materials

• Acoustic tools respond to acoustic impedance (acoustic hardness) Z

• Z = density x acoustic velocity• Z is expressed in MRayl (106 kg.m-2.s-1)

10/SRPC/

Lightweight cements

• Generally speaking they are more difficult to evaluate– Lower acoustic impedance

– Slower setting (longer waiting time)

• For a given density all lightweight cements are not alike– Dowell LiteCRETE systems exhibit:

• Low porosity (low water content) and hence a relatively high ultimate acoustic impedance

• Fast strength development and hence a fast acoustic impedance development (can be logged earlier)

• For a given density they are easier to log than any other lightweight cement

11/SRPC/

Sonic (CBL/VDL) principle

20 kHz

Transmitter

3 ft Receiver

5 ft Receiver

Casing

Formation

t

t

Bonded cement

Mud

Cement

VDL

CBL amplitude

0 100 CBL amp

12/SRPC/

CBL amplitude interpretation

• What is needed? – Expected cement impedance -->

amplitude for 100% bond: E100%

– Free pipe amplitude: EFree

– Measured amplitude: EMeas

• Bond index:

BI = log10(Emeas/Efree)

log10 (E100%/Efree)

• Conventionally:– 80% < BI < 100%: Good cement

– 80% > BI: ?

13/SRPC/

Sonic (CBL/CBT)

Strengths• Most well fluids, tolerates corrosion

• Responds to solidity (shear coupling)

• Qualitative cement-formation bond from VDL

Weaknesses• High CBL amplitude is ambiguous

– liquid microannulus (shear coupling lost)

– channel

– contaminated cement

– light cement mixed with neat

– Fast formation arrivals

– reflections from double string or hard formation

• Low amplitude doesn’t ensure 100% bond

14/SRPC/

UltraSonic Imager Principle

The USI evaluates cement with•An ultrasonic

transducer • The

resonance technique

Free pipe

Good cement

(0.2-0.7 MHz)

15/SRPC/

Ultrasonics (USI) advantages over sonics

(CBL)

• Tolerates liquid microannulus (vibrations normal to surface)

• Full coverage, 30 mm resolution image– Detailed picture of material

distribution: solid, liquid, gas, debonded cement

– Detects narrow channels

• Easier interpretation and less uncertainty than sonics (CBL/CBT)

• Casing inspection in same pass

16/SRPC/

The USI view

Mud channel

WashoutEccentered casing

Gas microannulus

Well centered casing

Perfs

Casing weld

17/SRPC/

Acoustic Evaluation Summary

• Acoustic logs are sensitive to the acoustic properties (especially impedance) of the material in contact with the casing.

• The USI is the primary evaluation tool: the image is easier to interpret and much less ambiguous than the CBL log.

• USI and CBL are sensitive to the cement/casing bond but in different ways- complementary evaluation.

• Acoustic methods are limited in very light cements (low acoustic contrast from mud).

• For optimum evaluation, cement job data must be included in the evaluation because cement does not disappear.

18/SRPC/


Imager • Introduction

• Acoustics basics

• USI tool basics

– Measurements and processing

– Tool and specifications

– Logging procedure

– Images

• USI QC



19/SRPC/

UltraSonic Imager

• Ultrasonic tool operating between 200 and 700 kHz.

• Full casing coverage at 1.2 in. (30 mm) resolution using rotating transducer

• Measurements

• Cement evaluation

• Casing corrosion and wear

20/SRPC/

USI Measurements

Echo amplitude

(Internal casing condition)

Transit time

Internal radius

Thickness Cement Impedance

21/SRPC/

USI si

gnal pro

cess

ing

22/SRPC/

USI signal processing

Fluid properties measurement (FPM)

Zmud mudV

T3 processing:

Echo amplitude

Travel time

Resonant frequency:

Fractional bandwith:

f0

f0

f

Internalrugosity

Casingthickness

Internalradius

Waveform

Cementimpedance

Fit plane wave model

Correct for cylindrical casing geometry

Casingthickness

Cementimpedance

23/SRPC/

USI tool

Electronics

Sonde

Rotating sub

24/SRPC/

Rotating subs

Assembly Sub O.D.

USRS-A

USRS-B

USRS-C

USRS-D

3.58”

4.64”

6.69”

8.70”

4 1/2” - 5 1/2”

5 5/8” - 7 5/8”

8 5/8” - 9 5/8”

10 3/4” - 13 3/8”

25/SRPC/

USI General Specifications

Length (sonde and cartridge only) 248 in. [6.3 m]

Diameter 3.6 to 11.2 in.

Weight

-Sonde 188 to 210 lb

-Cartridge 153 lb

Maximum temperature rating 350oF [175oC]

Maximum operating pressure 20,000 psi

Recommended logging speed 400 to 3200 ft/hr

Combinable with CBL-VDL, CBT, GPIT, Gamma Ray. CCL

26/SRPC/

USI Measurement Specifications

Casing OD 4.5 - 13.375 in.

Casing thickness 0.17 - 0.59 in. (4.5-15 mm)

Acoustic Impedance 0-10 MRayl

Max. deviation No limit

Logging speed 400 to 3200 ft/hr

Sampling

- Azimuthal 5-10 deg.

- Vertical 0.6-6 in.

Maximum mud weight

-Water-base mud ~16 lbm/gal

-Oil-base mud ~11.6 lbm/gal*

* Depends on composition, temperature and pressure. Good logs are usually obtained up to 13 lb/gal and sometimes up to 16 lb/gal

27/SRPC/

USI Cement Evaluation

Specifications

Acoustic impedance

Range 0-10 MRayl

Resolution 0.2 MRayl

Accuracy

0-3.3 MRayl +/-0.5 MRayl

> 3.3 MRayl +/- 15%

Min. quantifiable channel width

1.2 in. (30 mm)

28/SRPC/

USI logging procedure

1. Measure fluid properties using reference plate while running into well:

- velocity FVEL

- acoustic impedance ZMUD

2. Enter ZMUD and FVEL parameters. Flip transducer to face casing and log up.

29/SRPC/

USI cement image settings

Raw image

Interpreted Image

Cement

Liquid

Gas or dry micro-annulus

Sta

nd

ard

Lig

ht

0

2

4

6

8

Z MRayl

Solid/liquid threshold

ZTCM

Maximum impedance

Gas/liquid threshold

+/- 0.5

The USI discriminates between solid, liquid and gas/dry microannulus using acoustic impedance thresholds.

30/SRPC/

Mud impedance inside casing Zmud

• From FPM (after Q-check versus theoretical value). 0.1 MRayl change in Zmud changes Zcem by ~ 0.5 MRayl.

Cement impedance scale

• Adapt upper limit to cement impedance

USI Parameters

Cement type Density (ppg) Upper Z value(MRayl)

Neat > 13 8Light bentonitic 14 < density < 11.5 5Very light bentonitic < 11.5 4LiteCRETE 14 < density < 11.5 6LiteCRETE < 11.5 5

Liquid/solid threshold ZTCM

• About 0.5 MRayl above impedance of mud in annulus. Typical values:

Slurry density(ppg)

ZTCM (MRayl)

<12.5 *12.5 2.116 2.619 3.1

31/SRPC/

USI combined casing + cement

presentation Casing CementQC

Process flags, Eccentering, CCL, gamma

Processing flags

Amplitude

Casing cross-section

Internal radius

Thickness

Thickness

Cement raw

Cement interpreted

Bond index

Channel

32/SRPC/

USI + CBL/VDL cement presentation

USI VDLQC

Acoustic impedance

Cement image interpreted

VDL

Bond index

CBL, gamma

Process flags, eccentering

CBL

CBL

33/SRPC/

Image orientation

• In deviated wells, interpretation of channels etc. is aided by orienting images upper/lower side of casing

• Orientation tools such as GPIT can be run in combination with the USI and CBL.

• If no orientation tool is run the USI eccentering azimuth curve AZEC is usually a good indication of higher side except in near-vertical wells and S-bends. It is not sufficiently reliable for automatic image orientation.

34/SRPC/

New USI presentations

• Available in OP9.1• Dowell cement header• USI cement with Dowell

cement data • USI and CBL cement with

Dowell cement data• USI combined QC + casing +

cement

35/SRPC/

Dowell cement header

Well

Time

Caliper

original DF

Fluid

Post job events

Logging fluid

Casing

Collars

Set cement properties

36/SRPC/

USI presentation with Dowell cement data

USI

Calipers

Casing standoff

Average USI impedance

37/SRPC/

USI/CBL presentation with Dowell

cementing data

Casing standoff

Calipers

Average USI

impedance

USI

CBL

Predicted CBL for 80% and

100% bond

VDL

38/SRPC/

USI/CBL presentation with Dowell

cementing data Casing standoff

G ray

USI cement CBL

Predicted CBL for 80% and 100% bond

VDLUSI amp

USI ecc

39/SRPC/

Standard USI presentation

Client Log

Dowell Cement Header (if cementing by Dowell)

Standard API Header

SLB Composite/LQC log

Repeat section (Client log)

ZMUD and FVEL plots

Standard API Tail

40/SRPC/




• USI tool basics

• USI QC

– FPM check

– QC presentations

– Factors affecting USI response



41/SRPC/

USI QC Procedure

• Check fluid properties log (FPM)

• Check QC log for correct echo acquisition

• Check no processing flags

• Eccentering inside spec

• Casing radius and thickness close to nominal in uncorroded areas

• Casing must be in good condition and radius and thickness accurate for a good cement log

42/SRPC/

Fluid Properties Measurement QC

Fluid velocity curve is smooth and consistent with fluid type

Mud impedance is inside theoretical limits with small dispersion

43/SRPC/

Zmud calculation

Clear FluidsZ_FLUID (MRayl) = Rho (g/cm3) * 304.8/Velocity (US/ft)

Rho=downhole density

Check measured Impedance = theory ± 10%

Weighted MudsZ_FLUID (MRayl) =

K * Rho (G/C3) * 304.8 /

Velocity (US/ft )

K - Factor is in the range of 0.85 -1.0. An empirical formula exists for K.

Check measured impedance= theory ± 10%

or +10% - 25% if K not known.

Excel spreadsheet available to check Zmud.

44/SRPC/

USI QC log

Travel Time histogram

Time

Echoes centred in window

Eccentering inside tolerance.

Gain below max

Casing ID close to nominal

Detection window

45/SRPC/

QC of combined casing + cement

images Casing CementQC

Mean casing diameter and thickness agree with nominal, curves don’t straight-line

Processing flags clean

Eccentering inside tolerance

Casing must be in good conditon for good cement log

Amplitude image clean (no rugosity or eccentering)

46/SRPC/

New QC+casing+cement

presentation Casing CementQC

Processing flags clean

Eccentering inside tolerance

Casing must be in good conditon for good cement log

Amplitude image clean (no rugosity or eccentering)

QC

Echoes centred in window

TT histogram

Mean casing diameter and thickness agree with nominal, no straight-lining

47/SRPC/

USI Processing flags

0

1

2

3

4-6

7-10

No problem.

Casing thickness error (thickness and cement impedance invalid).Error fitting model (cement impedance invalid).

Telemetry.

Echo not detected (all data invalid).

Signal too short for processing (thickness and cement impedance invalid).

Flags indicate problems during processing of echo waveforms that may invalidate the data

48/SRPC/

Factors affecting USI response

• Casing shape and rugosity– Normal manufacturing patterns

affect cement image slightly– Wear and corrosion and

extreme manufacturing patterns create artefacts that can be diagnosed by correlations with casing images

• Tool eccentering – < 2 to 4% of casing diameter

(depending on thickness) for < 0.5 MRayl error

• Third interface reflections (outer casing or hard formation)

49/SRPC/

Casing shape effects

Internal manufacturing patterns often affect cement image slightly but do not usually affect interpretationAmp Int rad. Cement

Formation reflections

50/SRPC/

Poor casing condition affects cement

evaluation

Red “Gas” indications

Processing flags

Echo amplitude shows rugosity

Processing flags and amplitude image show that gas indications are an artifact of internal rugosity

QC Casing Cement

51/SRPC/

Casing wear can affect cement image

Drill pipe wear creates false “channel”

QC Casing Cement

False channe

lWear

groove

52/SRPC/

Deformed casing

QC Casing Cement

Deformed casing can cause lost echoes and tool eccentering. Even the eccentering curve becomes false. The log must be repeated with a wider acquisition window.

Max/min TT TT histogram

Echoes outside acquisition

window

Window

Lost echoes

Eccentering

53/SRPC/

Third interface reflections

Int. radius

Thickness Cement

Typical “galaxy” patterns created by interference between casing resonance and reflections from outer casing (here) or hard formation. The patterns indicate good cement except when the casing touches the formation in free pipe.

Narrow side of annulus

Galaxy pattern

Channel

54/SRPC/

Third interface reflections

Casing Cement

No centralizers, 4.5 in. liner inside 7 in. casing

Galaxy patterns on narrow side of annulus

3 centralizers/joint, 7 in. casing in open hole

Tigerskin pattern all round

Collar

Collar

Centralizers

55/SRPC/




• USI tool basics

• USI QC

• USI and USI/CBL Interpretation– USI response– USI and CBL/VDL

– Typical images and logs

– Interpretation summary

– Limitations of ultrasonics


56/SRPC/

USI response to materials in annulus

Good cement +/- 15%impedance(+25% if shear bond)

Liquids/gas +/-0.5 MRayl

Gas microannulus/ drydebond

Reads gas

Liquid layer- < 0.2 mm microannulus

- Mud layer > 0.5 mm

Tolerates 0.1 to 0.2 mm(50% reading with 6 to12 mm casingthickness)

Reads mud

Thin cement Reflections fromsecond casing or hardformation createinterference patterns

57/SRPC/

USI In

terp

reta

tion

58/SRPC/

BP Test well (1)

Channel and contaminated cement

Contaminated cement

Good cement

Channel

Heavily contam. cement

59/SRPC/

BP Test well (2)

Mud cake

Good cement

Mud cake

Outer casing

reflections

60/SRPC/

USI and CBL/VDL

• In simple cases (good well-bonded cement, free pipe, mud channel) the tools agree.

• In more complicated real-life situations the tools have different responses which can aid interpretation:– Contaminated cement– Wet microannulus– Dry microannulus

61/SRPC/

USI and CBL/VDL guide

USI CBL/VDL

Resolution 1.2 in. 360 deg. x 3 ft

Well bondedcement

Cement Cement

Very lightcement

Low contrast[special processingif debonded]

Low contrast frommud

Dry microann.Debondedcement

Dry microann. /gas(special processing)

Good/fair bond

Wet microann. Slightly affected AmbiguousMud layer Channel AmbiguousContaminatedcement

Low-Z cement Ambiguous

Mixed lead/tailcement

Mixed lead/tail Ambiguous

Mud channel Channel Ambiguous

Gas channel Gas channel Cement/ambiguous

Formation bond Not seen VDL qualitative

Outer casing/hard formation

Slightly affected Strongly affected

Casing condition Very sensitive Slightly sensitive

Mud attenuation < 12 dB/cm/MHZ No limit

62/SRPC/

Good cement

USI VDLQC CBL

CBL flat, low

Strong formation

arrival

Weak casing arrival

Mean Z 8 MRayl

63/SRPC/

Mud channel and contaminated cement

USI VDLQC CBL

CBL variable,

high

Weak formation arrival

Strong casing arrival

Channel

Low-Z cement

64/SRPC/

Cement top

USI VDLQC CBL

CBL flat, high

Weak formation arrival

Strong casing arrival

Traces of contaminated

cement

65/SRPC/

Channel and Squeeze

USI BI VDL USI BI VDL

Channel

After squeeze

Perfs

USI

CBL

66/SRPC/

Light cement top

•Light cement has low impedance

•0-4 MRayl scale shows contrast between light cement and liquid

•Liquid/solid threshold set low (2.1) for light cement

•CBL agrees with USI

0-4 MRayl

0 100 Threshold 2.1 MRayl

67/SRPC/

Contaminated cement

Contaminated (low Z) cement: USI image clear, CBL ambiguous

Mud channels: CBL, USI agree

Casing CBLBI

VDL Cement

CBL BI

Weld

CBL BI

USI BI

68/SRPC/

Contaminated medium-weight

cement 0-4 MRayl USI scale brings out small contrasts

Contaminated cement

Liquid

Gas

Liquid

Gas

69/SRPC/

Microannulus/ debond

• A small gap (< 0.2 mm) between casing and cement formed by pressure and temperature changes, or a mud film left on the casing

• USI and CBL respond in different waysMicroannulus USI CBL

Wet Weaklyaffected forgaps <0.1 to0.2 mm

Stronglyaffected

Dry Reads gas.Specialmicro-debondingprocessing

Weaklyaffected forvery small gaps(microns)VDL "bitty"

70/SRPC/

Wet microannulus

USI BI VDL

High CBL

Uniform medium-Z USI

Strong, regular casing arrival

• USI is weakly affected

• CBL reads near free pipe

71/SRPC/

Dry microannulus/ debond

Dry microannulus

Gas microannulus

Dry debond

Micro debond

• Mean the same thing

• Indicate solid cement

• Often occur without gas entry even in double casing strings due to pressure or temperature changes

• Act as a barrier to ultrasound

• Gas entry should only be suspected if in known gas zone, gas injector well near, or gas at surface

72/SRPC/

Gas channel and microannulus

Gas coming to surface of old storage well

Old CBL showed almost 100% bond

New USI showed narrow gas channel plus areas of debond (gas microannulus)

Narrow gas channel

Gas microannulus

Good cement

Raw BI Interp

73/SRPC/

Micro-debonded cement

Patchy “gas”/ cement indicates micro-debonded cement (patchy dry micro-annulus)

Raw BI Interp

74/SRPC/

Extended dry microannulus

(debonded cement)

Debonding can be extensive with low impedance variability and not associated with gas entry

Raw BI Interp

75/SRPC/

Micro-debonding: USI and CBL are

complementary • CBL less affected than USI without

pressure

• USI and CBL improve with pressure

USI BI VDL USI BI VDL

With pressure Without pressure

USI

CBL

76/SRPC/

USI micro-debond logic

Micro-debond presentation Conventional

BI BIMap Map

Automatically classifies patchy low-impedance material as micro-debonded cement

Helps interpretation of light and foam cement

Low CBL

Formation arrivals

CBL VDL

77/SRPC/

Micro-debonded cement processing

HorizontalDeviation

Diagonal 1

Diagonal 2

VerticalDeviation

Transducer“spot” size

If all 4 standard deviations are higher than set thresholds, the current data point is considered to be locally debonded.

78/SRPC/

Micro-debond logic

AI ThresholdsPixel ZMicro-debonding

algorithm Cement

OR

Liquid

Micro-D

OR

Gas

Micro-D

< Thresh

<Thresh

> Thresh

> Thresh

79/SRPC/

Micro-debond logic example

BI Map

Automatically classifies patchy low-impedance material as micro-debonded cement

CBL

CBL VDL

80/SRPC/

Litecrete 12 ppg cement

Debond logic

Threshold map

BI

CBTBI

• Gas entry from known gas zone

• Micro-debond logic shows cement is present

VDL

81/SRPC/

Cement/formation interaction

GR USICBL VDL

GR

• Acoustic logs dependent on lithology

• Cement present throughout

• Contamination ? Microannulus?

82/SRPC/

USI image interpretation

Squeeze

Mud channel

Liquid

?

Narrow

Gas channel

Cement

Dry micro-annulus (Debond)

Extended

No Squeeze

Patchy

High Z

Medium

Light or contam. Cement

Micro-debondedCement

Mud layer + cement

Gas

Cement data

Gas entry if gas zone

Localised

83/SRPC/

Good interpretation

Ambiguous

Very ambiguous or not detectable

Acoustic evaluation at a glance

Cement USI CBL

Heavy, medium, good bond

Very light, good bond

Debonded, drymicroannulus

Liquid microannulus

Mud layer

Mud channel

Contaminated

Gas channel

84/SRPC/


Imager

• Introduction


• USI tool basics

• USI QC

• USI Interpretation


– Well and cementing data needed

– Is cement present?

– Are the logs consistent with the data?

– Schlumberger integrated evaluation

85/SRPC/

Integrated analysis

Acoustic logs have limitations. To make the best evaluation the logs must be analyzed together with the well data and cement job data.

86/SRPC/

Well and cement job data needed

• Well data:– Caliper, GR, sonic, directional survey,

temperature, frac pressures– Casings and centralization

• Cement job data:– Density, rheology, pump rates, well

head pressure, mud rheology– Volumes and returns– >> Predictions of cement placement

• Expected cement acoustic impedance– Measured in lab (e.g. UCA)

– From density and database (CBL adviser)

87/SRPC/

Q1: Is cement likely to be present?

• Where is the expected top of cement?– Is the cement log depth far away from

this depth?

• What could have gone wrong?– Were caliper data used to determine

top of cement?– Was the cement volume pumped as

designed?– Did the top plug bump?– Were losses encountered during the

job?– How does the measured wellhead

pressure compare with the predicted one (Job Signature)?

88/SRPC/

Q2: Is the log consistent with the well and cementing

data? (1)• Channel

– Poor pipe centralization?– Poor mud condition before cement

job?• Yield point or gel strength too high?

– Flow rate too low?• Mini. circulation rate to mobilise

mud on narrow side not achieved?

– Washout (caliper)?

• Thick mud film– Good pipe centralization?– Poor mud condition before the

cement job? • Yield point or gel strength too high?

– Flow rate too low?

89/SRPC/


data? (2) • Contaminated cement / Poorly

set cement:– Not enough bottom plugs?

– Did formation fluid enter during/after the job? (OH logs)

– Cement/permeable formation interactions? (OH logs)

– Temperatures overestimated?

90/SRPC/


data? (3) • Microannulus / Debonding:

– Did log improve with pressure?

– Is it due to a post job event ?

• Pressure testing of the pipe

• Change of fluid density

• Drilling of next section

– Thin layer of mud/spacer left at the pipe wall (mud condition and flow rate incorrect)?

• Gas entry or gas channel– Is there a known gas zone (OH

logs)?– Is there a gas injection well

near?

91/SRPC/

Schlumberger integrated cementing

and evaluation • Integrating Dowell

cementing and cement job analysis with USI and CBL/VDL wireline logs provides the optimum evaluation.

• In the past cement job analysis was separate from wireline logs.

• Now key well and cementing data can be integrated in the USI/CBL log for a complete evaluation.

92/SRPC/

CBL adviser

Light lead slurry 1200 kg/m3

Tail 1 1900 kg/m3

Tail 2 2000 kg/m3

Fill Impedance CBL amplitude

Attenuation

• Accounts for all well parameters and slurry properties

• Computes expected cement properties and flags misleading situations

93/SRPC/

Schlumberger integrated evaluation

New USI wellsite software allows:

• Automatic inclusion of detailed Dowell cement header

• Inclusion of Dowell well and cementing data:

– Cement density histogram

– Caliper logs

– Calculated pipe standoffs

– Expected cement impedances

– Predicted CBL reading for 100% and 80% bond

94/SRPC/

Dowell cement density histogram

Can be included in USI log

95/SRPC/

Conclusion • The USI provides the most

detailed view of the distribution of cement in the annulus available today.

• The combination with the CBL/VDL is recommended for added confidence, especially when microannulus is present.

• Acoustic logs have limitations.

• Cement evaluation must combine cement job analysis and acoustic logs

• Schlumberger integrated cementing and evaluation is the optimum solution.

Documents

Cement Evaluation with the UltraSonic Imager Andrew Hayman Dominique Guillot Sean Harrera Bernard Piot Gilles Rouault Bob Butsch Charles Morris Matteo