CAN MUDLOGGING SHOWS BE QUANTIFIED? - …wyogeo.org/contents/plugins/innovaeditor/assets/Bill Donovan Can... · • The basic mud log records: 1) drilling ... gases for the mudlogging

24/January/2014 © Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 1 0f 58

CAN MUDLOGGING

SHOWS BE QUANTIFIED?

Bill Donovan, PE Donovan Brothers Incorporated

Automated Mudlogging Systems

Our Corporate Motto

“WE DON’T PASS GAS”


Can Mudlogging Shows be Quantified?

• Field study results

• Definitions and theory

• Resource comparison

• Mudlogging gas content

• Factors influencing mudlogging

• Calibrating the system

OVERVIEW



PRB CBM Field Study Results 55 wells with Mudlog GC (green)


Common form of volumetric gas in place for shale and coal

G = gas in place (MCF)

A = drainage area (acres)

H = thickness (feet)

ρb = bulk density (gm/cc)

GC = gas content (scf/ton)


PRB CBM Field Study Results

GCHA3597.1G b




bHA3597.1GGC

Back calculated gas content is based on cumulative production and/or estimated ultimate recovery (EUR) G is cumulative production or EUR A is the spacing unit H and ρb are from logs




55 wells with Mudlog GC (green)

Cumulative Production GC (blue)






Estimated Ultimate Recovery GC (red)






Estimated Ultimate Recovery GC (red)

Isotherm Estimated GC (purple)



OHIO

WESTMORELAND

WEST

VIRGINIA MARYLAND

PENNSYLVANIA

Marcellus Shale HZ Well Results Ty Taylor’s

Clemson

MS Thesis



MAHANTANGO SH

MARCELLUS

SH

Marcellus Shale HZ Well Results

Ty Taylor’s

Clemson

MS Thesis



Marcellus Shale HZ Well Results Ty Taylor’s

Clemson

MS Thesis



0

100

200

300

400

500

600

1 2 3 4 5 6 7 8 9 10 11 12

TG

(g

as

un

its)

Well

TG Mean

TG (TRAP) Mean

NORMALIZE MUDLOGS

ON MATAHANGO SH


Ty Taylor’s

Clemson

MS Thesis



R² = 0.87

400,000

800,000

1,200,000

1,600,000

2,000,000

0 2,000,000 4,000,000 6,000,000

18

Mo

nth

Pro

du

ctio

n

(MC

F)

TG(TRAP) sum (gas units)


Ty Taylor’s

Clemson

MS Thesis

24/January/201

4

© Donovan Brothers Inc. Automated Mudlogging Systems SM Slide ‹#› 0f 58

24/January/201

4

© Donovan Brothers Inc. Automated Mudlogging Systems SM Slide ‹#› 0f 58

• Define mudlogging

• Define mudlogging gas measurements

Percent Equivalent Methane in Air

(% EMA) and “Units EMA”

• Explain why mudlogging is effective

• Compare resources for different

reservoirs



Definitions and Theory

Define mudlogging and a mudlog

• A mudlog is a record over time of rig functions, gas and cuttings

• The basic mud log records: 1) drilling rate, 2) gas measured at the mudlogging unit and 3) cutting properties such as lithology and the presence of oil

• A mudlog presents the above properties and others as a function of depth






• EQUIVALENT METHANE IN AIR (% EMA) is a measure of methane in air at the measurement point (the mudlogging unit) expressed as a percent of methane in the air sample or expressed differently as10,000 parts per million methane by volume

• Calibrated and measured at the mudlogging unit, the whole system is not calibrated

• Although related to mudlogging gas content, % EMA is not a measure of gas in the formation or drilling mud

• Other hydrocarbon gases are presented as methane

• Typically 100 “Units EMA” equals 1% EMA



Definitions and Theory Can Mudlogging Shows be Quantified?

MUDLOGGING IS EFFECTIVE BECAUSE:

•Gas is measured at the surface under STP

•Gas is insoluble in water and drilling mud

•Gas expands as it travels to the surface

•Mudlogging is independent of theories and models



•Gas is measured at the surface under STP






Surface gas volume for one

cubic foot of gas or gas

saturated water at certain depths



MUDLOGGING IS

EFFECTIVE BECAUSE:

•Gas is measured at the

surface at STP

•Gas is insoluble in

water and drilling mud

•Gas expands as it

travels to the surface

•Mudlogging is

independent of theories

and models





•Gas is measured at the surface at STP







Fruitland Coal



3’ Perfed

Pictured Cliff SS

Perfed

3’

1,124’-

1,127’

Foam fraced

w/18K#

10-20 sand



The next five slide present the amount of gas liberated and brought to the surface for coal, shale, oil and gas reservoirs.

The and colored bars to the left show and values relative to the

reservoirs.

All slides have the same format and vertical scales

Again the conclusion reached is that both conventional and unconventional hydrocarbon reservoirs liberate gas in quantities significantly higher than reservoirs containing water

Resource Comparison



Resource Comparison



Resource Comparison



Resource Comparison



Resource Comparison



Resource Comparison



The requirements to calibrate mudlogging show

are:

1) The cubic feet of acetylene generate per

pound of calcium carbide (yield)

2) Calibrate the mudlogging gas sensor with

both acetylene and methane

3) The peak gas reading of a carbide lag

using a measured amount of carbide

Mudlogging Gas Content Methodology



The requirements to calibrate mudlogging show

are:

4) The gas units during a mudlog show

5) The bit diameter

6) The drilling rate during a mudlog show

7) Simple mathematical computations to

calculate gas liberated per minute and

rock volume drilled per minute


• A measured amount of Calcium Carbide reacts with

water to make known amount of acetylene gas: CaC2 +

H20 = C2H2 +CaO

• Before mudlogging a calibration using both acetylene

and methane establishes a relationship between the

gases for the mudlogging unit’s gas sensors

• Before and after the zone of interest is drilled a known

amount of Calcium Carbide (acetylene) is put in the drill

string during connections and pumped to the surface.

The peak gas value is recorded

• Using this data, a gas show in units EMA can be

converted to SCF of gas liberated while drilling




• The hole volume is known, therefore, SCF/formation bulk

volume (ft3) can be calculated along with BCF/section or

MCF/acre-foot . These are the standard measures of

used in volumetric reservoir calculations

• If the formation density is known, gas content (SCF/Ton)

can be calculated

• If Bg or Bo, the gas expansion factor or the oil shrinkage

factor, is known reservoir hydrocarbon foot (SoPhieH or

HCF) along with Bvg or reservoir gas porosity can be

calculated




• 0.5 cup of calcium carbide yields

1.268 SCF acetylene

• 125 “units” of acetylene reads 250

units EMA in the mudlogging unit

• 0.5 cup of calcium carbide in a

connection before the zone yields

200 “units” of acetylene

• Calculate a conversion factor from

the above data and Avogadro's Law

• Conversion factor

0.01268 SCF CH4 /1 UNIT EMA







Calculate a conversion factor from data on the

last slide and Avogadro's Law

22

422

22

2

2

22

1

1

125

250

250

5.0

5.0

268.1

HCSCF

CHSCF

EMAUnits

HCUnits

HCUnits

CaCCUPS

CaCCUPS

HCSCF

From Carbide Manufacturer

From Carbide Lag

From Different %’s of CH4 and

C2H2 Gas Tested on Sensors




Calculate a conversion factor from data on

the last slide and Avogadro's Law.

Conversion factor =

Conversion factor =

0.01268 SCF CH4 /1 UNIT EMA

4

22

4

4

22

22

22

2

22

4

2

22

%25.1

%25.1

125

%25.1

%25.1

250

250

5.0

268.1

268.1

5.0

268.1

CH

HC

CHEMA

CH

HC

HCUnits

HCUnits

CaCCUPS

HCSCF

CHSCF

CaCCUPS

HCSCF

• Gas reading in the zone 570

UNITS EMA/minute

• Calculate gas liberated per

minute in the zone by

multiplying gas reading by the

conversion factor

• 570 UNITS EMA /minute X

0.01268 SCF/UNIT EMA=

7.23 SCF/Minute






• Penetration rate in the zone is

0.5 minutes/foot

• Hole diameter is 8.5 inches

• Calculate the hole bulk volume

(BV) drilled per minute

• Hole Volume/Minute =

0.78813 BV Cubic Feet/Minute




• Divide the gas liberated per

minute by the hole volume

drilled per minute

• 7.23(SCF/Minute) /

0.78813(BV CF/Minute) =

9.17 SCF/BV CF

• Conversion factors can be

used to calculate BCF/Section

foot or MCF/Acre foot




• Zone density is 1.4 gms/cc

• Convert hole BV CF to Tons by

using density

• Gas content 210 SCF/Ton

• Zone depth 1,000’, Bg = 36.4

• Convert SCF to Reservoir CF

by using Bg

• Bulk Volume Mudlog Gas

0.25 CF/BV or 25%




The factors which influence mudlogging can be grouped into two general categories:

• Deterministic factors

(hole size, drilling rate, etc.)

• Indeterminate factors

(flushing, background gas, surface losses, gas trap performance)

Carbide calibration accounts for all factors

Factors Influencing Mudlogging



Deterministic factors affecting mudlog gas are:

• Gas in the formation

• Hole size

• Drilling rate

• Mud pump rate

• Gas expansion




If all other factors are equal, doubling

the gas in the formation doubles the

gas show




If all other factors are equal, doubling the hole diameter, quadruples the gas show




If all other factors are equal, doubling the drilling rate, doubles the gas show




If all other factors are equal, doubling mud pump rate, decreased by one half the gas show




If all other factors are equal, doubling

the depth of the formation doubles the

gas show in conventional reservoirs


Indeterminate factors are:

• Recycled gas (minor)

• Contaminated mud (seldom)

• Formation flushing (minor)

• Loses while drilling (seldom)

• A kick while drilling (seldom)

• Uphole kicks or loses (seldom)




More indeterminate factors are:

• Cuttings not fully releasing gas (minor)

• Surface losses (major)

• Gas trap design (major)

• Temperature (major)

• Wind (seldom)

• Miscalibrated sensors (seldom)






Gas trap efficiency and measurement stability is the largest cause of mudlogging error. See the SPE, Williams and Ewing article.

GAS IN THE MUD GA

S A

T T

HE

MU

DL

OG

GIN

G U

NIT




“Improved Methods for Samplings Gas

and Drill Cuttings”, Williams and Ewing,

SPE FE, June 1989




GRI

Gas Measurements During

Mud Logging Operations




EFFECT OF TEMPERATURE ON THE

SOLUBILITY OF GAS IN WATER

0

2

4

6

8

10

0 50 100 150 200 250

TEMPERATURE (DEGREE F)

SO

LU

BIL

ITY

AT

TE

MP

ER

AT

UR

E/S

OL

UB

ILIT

Y

AT

180 D

EG

RE

ES

FA

HR

EN

HE

IT

CH4 @ T/ CH4 @ 180 F

C2H2 @ T/ C2H2 @ 180 F




GRI

Gas Measurements During

Mud Logging Operations


24/January/201

4

© Donovan Brothers Inc. Automated Mudlogging Systems SM Slide 56 0f 58

Notice all the potential errors:

• 100 units of gas in the mud could read as high as 200 units or as low as 3 units due to gas trap design

• Gas losses as much as 40% due to loss in the flow line

• Gas losses as much as 50% due to wind

• A six fold change in methane solubility in water from 40ºF to 180ºF

All of these losses can be normalized or compensated for by the use of calibrated carbide lagging. The next slide shows that acetylene behaves like methane over a wide range of conditions. If carbide lag results are consistent, it indicates good quality mudlogging





SOLUBILITY OF GAS IN WATER

0

10

20

30

40

50

60

70

80

0 50 100 150 200 250

TEMPERATURE (DEGREE F)

SO

LU

BIL

ITY

RA

TIO

(C

2H

2/C

H4)

RATIO

Calibrating the System


Mudlogging is an effective evaluation tool

If you have questions or comments contact me

Bill Donovan

(303) 794-7470

[email protected]

www.mudlogger.com


mailto:[email protected]



School for

Gifted

MUDLOGGERS

After

Gary

Larson



Walt

Kelly

Documents

CAN MUDLOGGING SHOWS BE QUANTIFIED? - …wyogeo.org/contents/plugins/innovaeditor/assets/Bill Donovan Can... · • The basic mud log records: 1) drilling ... gases for the mudlogging