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Fault property Fault property modellingmodelling: recent : recent

advances and future directions advances and future directions

Quentin Fisher

Centre for Integrated Petroleum Engineering and Geoscience

School of Earth and Environment

University of Leeds

E-mail: q.fisher@see.leeds.ac.uk

www.see.leeds.ac.uk/cipeg

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Fault transmissibility multipliersFault transmissibility multipliers

−++

−=

j

fj

f

f

i

fiij

k

tL

k

t

k

tLTrans

2

2

TM =

+

=

j

j

i

i

ij

k

L

k

LTrans

2

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Fault permeability databasesFault permeability databases

0.00001

0.0001

0.001

0.01

0.1

1

1 0

100

1000

10000

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

Clay content of host sediment (%)

Pe

rme

ab

ilit

y (

mD

)

Increasing burial depth

Rotliegend

Brent 2500 m

Brent 3500 m

>1000 measurements

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Mapping clay distributions along faultsMapping clay distributions along faults

Shale gouge ratio

used to estimate the

clay content of the

fault gouge along

each part of the fault

%100)(×

∆×=∑

t

zVSGR cl

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Fault thicknessFault thickness

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Is the fault rock property database helpful?Is the fault rock property database helpful?

Do the analysis of the properties of small faults

found in core really help predict the properties of

seismic-scale faults?

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Is the fault rock property database helpful?Is the fault rock property database helpful?

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Uncertainty in structural modelUncertainty in structural model

(From Sutier et al., 2005)

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Seismic analysis

StructuralLogging

Microstructuralanalysis

PetrophysicalProperty analysis

Flow Modelling

Fault plane map

Forward and inverse Forward and inverse modellingmodelling

Measurement Prediction Calibration

Dynamic data

Static data

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EvidenceEvidence--based practisebased practise

• New types of information are being constantly generated, which should, when we know and understand them, create frequent, major

changes in the advice that we give and the research that we conduct

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Simulation model using singleSimulation model using single--phase fault phase fault

permeabilitiespermeabilities

van der Molen et al., 2003)

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SorbySorby FacilitiesFacilities

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Gas relative permeability Gas relative permeability –– Hopeman Hopeman

faultfault

0.00

100.00

200.00

300.00

400.00

500.00

600.00

0.00 0.20 0.40 0.60 0.80 1.00

Water saturation

Cap

illa

ry p

ressu

re (

psi)

Al-Hinai et al, 2008

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History match achieved with twoHistory match achieved with two--

phase propertiesphase properties

Eclipse model

created in which a

local grid refinement

was used so we

could give fault its

own capillary

pressure and relative

permeability curves

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Transmissibilitymultiplier Water relative

permeability

Oil relative permeability0.0

1

0.5

BADLEY GEOSCIENCE LIMITED

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Stress dependence of relative Stress dependence of relative

permeabilitypermeability

Stress dependence of relative permeability during

loading

0.01

0.1

1

10

0 500 1000 1500 2000 2500

Effective stress (psi)

Krg

Sw = 44.4%

Sw = 40.5%

Sw = 66%

Dry Mam Tor samples

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0 500 1000 1500 2000

Effective stress (psi)

Pe

rme

ab

ilit

y (

mD

)

K1

D1

A11

0

2

4

6

8

10

12

14

16

900 1100 1300 1500

Difference in effective stress (mD)

Perm

eab

ilit

y r

ati

o

Partially saturated

Dry

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Coupled fluid flow Coupled fluid flow -- geomechanicsgeomechanics

Synthetic seismic Coupled geomechanical

– production simulation

models

MP

I inte

rface

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Pore pressure

Effective Stress

MORE

ELFEN

Flow through Sealing faultCoupled fluid flow Coupled fluid flow -- geomechanicsgeomechanics

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B1 Pressure Main

4000

4200

4400

4600

4800

5000

5200

5400

5600

5800

6000

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Time [year]

Pre

ss

ure

[p

si]

Alpha B1 Simulated

Bravo B1 Simulated

Charlie B1 Simulated

Alpha B1 Data

Bravo B1 Data

Charlie B1 Data

History match without fault propertiesHistory match without fault properties

From Jolley et al., Petroleum From Jolley et al., Petroleum GeoscienceGeoscience, 2007, 2007

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B1 Pressure Main

4000

4200

4400

4600

4800

5000

5200

5400

5600

5800

6000

1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Time [year]

Pre

ss

ure

[p

si]

Alpha B1 Simulated

Bravo B1 Simulated

Charlie B1 Simulated

Alpha B1 Data

Bravo B1 Data

Charlie B1 Data

History match with singleHistory match with single--phase fault phase fault

propertiesproperties

From Jolley et al., Petroleum From Jolley et al., Petroleum GeoscienceGeoscience, 2007, 2007

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Fault heterogeneityFault heterogeneity

Small windows with Small windows with

deformation products of deformation products of

clean sands will occur clean sands will occur

along most faults and along most faults and

control flow control flow –– particularly particularly

over geological timeover geological time--

scalesscales

Chances of barrier increases as permeability of

such windows decreases and threshold pressure

increases

BADLEY GEOSCIENCE LIMITED

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• Surprisingly similar, even though large faults are expected to

be more heterogeneous. Why?

• Childs et al (2007) have produced stochastic models of

disrupted shale smears (“PSSF”). With throws >> bed

thickness, the effective permeability of the fault zone is

equivalent to a simple log-linear relationship between SGR

and permeability.

Comparison of in-situ & lab calibrations

BADLEY GEOSCIENCE LIMITED

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SGR SGR –– different correlations for different different correlations for different

analyses?analyses?

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Discussion/ConclusionsDiscussion/Conclusions

• Signifcant advances being made on understanding fault rock properties

– Relative permeabilities

– Stress sensitivities

• Significant advances made in software for incorporating fault rock properties in simulation models (both relative

permeability and stress dependence)

– Far more work needed on calibrating databases (i.e.

putting properties into simulation models)

– Thorough fault seal analysis for production is still quite

rare

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Discussion/ConclusionsDiscussion/Conclusions

• Two-phase properties seem far more important when cataclastic fault rocks are present

– Are PFFRs really as important as previous studies have suggested?

– Probablistic clay smear method explains why SGR

often provides good results for production-fault seal analysis?

– What does this mean for fault rock seal over geological time?

• Multidisciplinary approach to fault seal appears to be making a step change in our understanding of

how faults affect flow in petroleum reservoirs

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Last wordsLast words

“I know that most men (sic), including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it

be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining

to colleagues, which they have woven, thread by thread, into the fabric of their lives.” Leo Tolstoy