Fault Seal Analysis

FAULT SEAL ANALYSISFAULT SEAL ANALYSIS

Fault Seal Analysis

FSA PROJECT OBJECTIVES

1. Calculate and Evaluate Sealing Potential For all Faults in Area-9 DURI SBU

2. Fault Seal Analysis Using FAPS 4.2

3. Evaluate Faults Kinematics and Slip History/Potential

4. QC Sealing Potential Using Available FE and Production History Data

5. Predict Probable Area of Fault Sealing or Fault Leaking Potential

Fault Seal Analysis

Why are we need evaluating FSA?• Faulting in granular materials such as siliciclastic strata generally causes cataclasis and changes in permeability and porosity or even it can act as impermeable barrier to hydrocarbons and creates a trap (i.e. fault sealing and compartmentalization)

• Faults can act as pressure barrier to subsurface fluids or steam during the production life of a field or as differential migration barrier to hydrocarbons over geologic time

• Seals can be considered as membrane or hydraulic seals depending on their likely failure mode (Watts, 1987), for example eruption problem

• Faults and fault zones are sealing membrane in which their properties are related to capillary entry pressure of the membrane

• The capillary entry pressure of the membrane is defined as the pressure required to initially enter the largest connected pore throat

• Membrane seals will trap hydrocarbon column height until the net buoyancy pressure exceeds the capillary displacement pressure of the seal

Fault Seal Analysis

Fault Seal Mechanisms

• Juxtaposition where reservoir sands are juxtaposed against a low-permeability unit (i.e. shale) with high entry pressure

• Clay Smear into fault plane, therefore generating the fault itself a high entry pressure

• Cataclasis, which is the crushing of sand grains to produce a fault gouge of finer grained material, giving the fault a high entry pressure

• Diagenesis, where cementation of original permeable fault plane may partially or completely remove porosity, finally creating a hydraulic seal

(Yielding and others, 1997)

Fault Seal Analysis

Fault Gouge

Fault Seal Analysis

Fault Seal Analysis

CONTRIBUTING FACTOR TO FAULT SEAL ANALYSIS

• Fault Types and Orientation• Burial Depth (i.e. Diagenesis)• Displacement Mode• Connectivity• Composition (sand/shale ratio)• Timing

Modified from Knot (1993)

Fault Seal Analysis

ThrowFault Throw and Displacement Field

Juxtaposition

Fault Seal Analysis

Sst

Sh

Sh

Sst

4

3

3

3

LITHOLOGY JUXTAPOSITION

Th

row

1 = Shale on Shale2 = Sand on Sand3 = Shale on Sand4 = Sand on Shale

1

2

1

2

1

2

Fault Seal Analysis

A) B) C)

D) E)

Smear Gouge Analysis (SGA)

Smear Factor AlgorithmsA) Bouvier et al., 1989B) Fulljames et al., 1996C) Lindsay et al., 1993

Gouge Ratio AlgorithmsD and E

by Yielding et al., 1997

Fault Seal Analysis

ALLAN MAP

• Strike Projection(FAPS 4.2)

Fault surface is viewedhorizontally from

hangingwall

Fault Seal Analysis

ALLAN Map/Diagram

Yielding (1999), FAPS 4.2

Fault surfaces from polygon data

Fault Seal Analysis

ALLAN MAP

FAULT: 3st_wr_sfd

Fault Seal Analysis

FSA WORK FLOW3D-SEISMIC

- Mapped horizon- Interpreted fault

Well Log Data- Zonation Stratigraphy

- Markers picks- GR curves

- Calculated V-Shale

Survey DataX, Y, Z

TWT, TVD

FAPS 4.2

Juxtaposition/Allan Map Fault Seal Analysis

Slip and DilationTendency

Other Data- ProductionPressure/RFT

GWC,OWC

- Stress Shmax,

Sv,Shmin

Fault Seal Analysis

FS5_240T

FS4_RT

SB_INTRN

FS3_PT

FS2_PT

FS1_KT

3st_wr_sfd

3S-56A3S-66A

3S-46B

3T-68A3T-67A

3T-36A

3S-25A

3T-27A3T-57A3T-56A

3T-78A

3S-35A

3S-76A

3T-47A

Fault Seal Analysis

FAULT: 3st_wr_sfd

3 4

21

SHALE GOUGE RATIO SEALNO SEAL

Fault Seal Analysis

SGR Vs. DEPTHSGR Vs. THROW

Empirical Approach

Seal ?

No Seal ?

No Seal ?

Seal ?

• Problem in determining critical SGR

Fault Seal Analysis

FS5_240TFS4_RT

SB_INTRNFS3_PT

FS2_PTFS1_KT

3T-68A

3T-48A

3T-57A3T-57A

Fault Seal Steam flow direction

Injector Well