Mt. Simon Geomechanics Modeling Review Illinois Basin...

North America Geomechanics Opera2ng Integrity North America Geomechanics | Opera2ng Integrity

Mt Simon Geomechanics Modeling Review Illinois Basin – Decatur Project Donald Lee Joe Adachi

Nov 8, 2011

North America Geomechanics Opera2ng Integrity

© 2011 Schlumberger. All rights reserved. An asterisk is used throughout this presentation to denote a mark of Schlumberger. Other company, product, and service names are the properties of their respective owners.


PresentationTopics

!   Introduction to Geomechanics !   What answers can Geomechanics provide? !   What is a Mechanical Earth Model (MEM)

and VISAGE* reservoir geomechanics modeling software ? !   Mt Simon Geomechanics Workflow ! Geomechanics of a rock sample

!   Building the 3D MEM !   VISAGE Modeling results !   Tracking the Stress Path !   Conclusions and Forward Plan


What answers can we get from Geomechanical analysis?

!   In general, geomechanics provides answers for: !   Drilling, completion, reservoir

!   For CO2 sequestration !   Model rock property change with pressure increase !   Caprock integrity with CO2 injection !   Fault reactivation !   Rock property change with pressure cycling


Mechanical simulator

ti ti+1 Time Reservoir simulator

ti ti+1

Explicit

Displacements, strains, stresses, etc.

Pressure, temperature,

and saturation variations

Mechanical properties

update

Implicit Porosity variation

Permability and transmissibilities

updates

Till convergenc

e

What is a MEM and VISAGE?

!   MEM - Mechanical Earth Model !   1D, 3D, simple or complex depending upon the problem to solve

!   VISAGE – Finite Element Modeling for stress and failure !   Coupled or non-coupled to ECLIPSE* reservoir simulation software model


Mt Simon Geomechanics Model Workflow

6

FEM simulations with time

steps

Reservoir Simulation

MDT* pressure

Core test results

Stress test Petrophysics

Geological model

Seismic Inversion

3D MEM 1D MEM

Embed reservoir

model

Single material model

Pre-injection stress

calibration

Analysis of results


Reservoir simulation of a rock sample

7

storage/flow properties

porosity, permeability, Sw

Core cat scan at 5504.8’

Permeability vs porosity


Geomechanics of a rock sample

8

rock properties

porosity, density, mineralogy, acoustic

Vertical resolution of data



9

mechanical properties

PR, shear modulus Young’s modulus, UCS,

tensile strength, friction angle

Stress-Strain Curves

0

5000

10000

15000

20000

-0.015 -0.010 -0.005 0.000 0.005 0.010 0.015 0.020Di

ffere

ntia

l Stre

ss (p

si)

Axial StrainRadial Strain

Triaxial test at 5478.5’



10





0

5000

10000

15000

20000

-0.015 -0.010 -0.005 0.000 0.005 0.010 0.015 0.020Di

ffere

ntia

l Stre

ss (p

si)





11





0

5000

10000

15000

20000

-0.015 -0.010 -0.005 0.000 0.005 0.010 0.015 0.020Di

ffere

ntia

l Stre

ss (p

si)





12




pp σ3

σ1

σ2

Tensile failure Shear failure Compaction failure

Shear failure Compaction failure

Tensile failure


Mt Simon Model Grid construction and embedding

13

Grid properties 976,752 cells 76x68x189 (I,J,K) ~13 miles - cube

3D seismic volume

Reservoir simulation model extent


Property Propagation Using Seismic Inversion

14


Failure indicators examined

!   Effective stress !   Tensile failure when effective stress < 0

!   Total volumetric Strain !   Total strain = elastic strain + plastic strain !   Large plastic strain indicate injection driven dilation

!   q/p’ ratio !   High q/p’ ratio values indicates shear failure

!   Dimensionless failure F !   UCS normalized Mohr-Coulomb failure envelope

!   Stress path consolidation plot


Volumetric Strain

16


Location of 3 cells examined for stress path

17

Eau Claire cell

Mt Simon middle cell

Injection cell


Stress Path Plot for Selected Cells

18

0

1 2

32

Injection cell stress path

Shear failure lines

Eau Claire cell stress path

Mt Simon middle cell stress path

Normalized Shear Failure Envelope (σ

1-pp

)/UC

S

(σ3-pp)/UCS


Rock displacement with Injection

19


Mt Simon Geomechanical Model Summary

!   Constructed and calibrated a 3D MEM for the Mt Simon base injection test

!   Examined 4 failure modes - results show no failure in the cap rock or injection interval for the base injection case

!   Stress path for three selected cells show rock is far from shear failure or tensile failure

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Forward Plan

!   Use new core test results to update rock property correlations !   Compare microseismic events (if present) to FEM stress

!   Model Eau Claire sensitivity to higher injection pressure !   Update model with new seismic results

21

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