numerical coupling of geomechanics and fluid flow...

IEA Symposium & Workshop – Vienna 17-19 Oct. 2011

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Renewable energies | Eco-friendly production | Innovative transport | Eco-efficient processes | Sustainable resources

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Numerical Coupling of Geomechanics and Fluid Flow during Steam Injection in SAGD

S. Zandi (IFP, ENSMP)G. Renard, J.F. Nauroy, N. Guy, (IFP)

M.Tijani, (ENSMP)


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OutlineIntroduction

Thermal RecoverySAGD ProcessSAGD Geomechanical Effects

SAGD Modeling & Reservoir SimulationReservoir-Geomechanics Coupling ApproachesApplied Coupling Approaches

Application & ResultsModeled Reservoir DescriptionComparison of Coupled Simulation Results

Conclusions


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IntroductionThermal RecoverySAGD ProcessSAGD Geomechanical Effects



Conclusions


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0,1

1

10

100

1000

10000

100000

1000000

10000000

0 100 200 300 400 500 600

Temperature (°C)

Visc

osity

(cP)

Thermal RecoveryBitumen & Heavy Oil

High viscosityEOR

20Water


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Steam Assisted Gravity Drainage

overburden

underburden

Steam chamberDraining oil +

condensed water

Steam injection well

Oil production well


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Shear, dilation and heave associated with SAGD (Collins ,2005)

Geomechanical effectsof steam injection

Stress changesDilationShear

ConsequencesPermeability increaseAffect the steam chamber developmentCap rock integrity ...

SAGD Geomechanical Effects

(Dussault , 2008)


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Problem Statement Necessity of Geomechanics in Reservoir EngineeringQuantification of Strain and Stress State in Reservoir

Reservoir productivityCap-Rock integrityHydro fracturingWell failureInterpretation of 4D seismicSteam chamber monitoring


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Problem Statement Necessity of Geomechanics in Reservoir Engineering

Prevention of the risks (Cap rock integrity)Joslyn Steam Release (2006) – SAGD

Induced over pressure

Source : Total E & P Canada -2007

ERCB Staff Review & Analysis - 2010


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Conclusions


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SAGD Reservoir SimulationConventional Reservoir Simulator

Can solve thermal multiphase flowCannot solve the mechanical equilibrium equationGeomechanics is taken in account just through a simplified relationship between porosity and pore pressure/temperature

Not a rigorous framework to represent the evolution of high porous rock strains !

For SAGD Modeling Coupled Thermo-Hydro-Mechanical modelingNot possible by conventional reservoir simulatorsSo the coupling methods are used


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Thermo-Hydro-Mechanical Coupling

Fully-Coupled Sequentially-Coupled

Explicit Iterative

Solving the Equations simultaneously

Time Consuming

Solving the Equations Separately

One Way

Reservoir–Geomechanics Coupling Approaches


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Reservoir–Geomechanics Coupling Approaches

One-wayReservoir simulator result is transferred to geomechanical simulatorNo feed back of geomechanical simulator into reservoir simulator.

ExplicitExchange between two simulators is performed only once per each coupling period.

IterativeExchange between two simulators is repeated until convergence under a given criterion.

Sequentially-Coupled Approaches

Geomechanics

Geomechanics

Geomechanics

Reservoir

Reservoir

Reservoir


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One-way Coupling Approach

Reservoir Simulator(PUMA FLOW)

Geomechanical Simulator

(ABAQUS)

PUMA2ABAIFP Coupling Module developed in Python + Fortran

Compute P, T


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Reservoir Simulator(PUMA FLOW)

Compute

Geomechanical Simulator

(ABAQUS)

vε

Explicit Coupling Approach

vc

kk ε

φ00ln =

PUMA2ABA

Permeability update by empirical formulation (from Touhidi-Baghini 1998)

Compute εσ ,,u

Compute P, T

Updating of Permeability


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Iterative Coupling Approach

Reservoir Simulator

(PUMAFLOW)

Porous volume correction

& Update Permeability

Compute

Compute

Geomechanical Simulator (ABAQUS)

PUMA2ABA

Yes

i = 0

i = i+1

No

Compute P & T

εσ ,,u

vε

Check Convergence


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Conclusions


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Modeled Reservoir Description


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Reservoir – Geomechanics CouplingGeomechanical Simulator

Discretization of geomechanical model:x : 65y : 1 z : 46Linear poro thermo elasticity

Reservoir SimulatorDiscretization of reservoir model:x : 65y : 1 z : 40

Triphasic flow (water, oil, steam)

Reservoir

Geomechanics

XY

Z

Total 3055 grid blocks

Total 2600 grid blocks

730 m

20 m

147 m


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Reservoir – Geomechanics CouplingBoundary Conditions:

Reservoir Simulator:No flow at the boundariesNo heat transfer at the lateral boundariesHeat transfer through the upper and lower boundaries

Geomechanical Simulator: Lower boundary is blockedUpper boundary is freeNo normal displacement on the lateral boundaries


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Comparison of Coupled Simulation

Applied coupling methods

One-way

Explicit coupling

5-step

12-step

Reservoir

Geomechanics

0 150 300 1000 2000 days

Reservoir

Geomechanics

1200 1500400200 600

500 800

Geomechanics

0 150 300 1000 2000 days

Reservoir

0 150 300 1000 2000 days


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Evolution of Temperature in Deformed Reservoir

150 days 300 days

1000 days 2000 dayshorizontal wells

5-step explicit coupling result:


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Evolution of Volumetric Strain in Reservoir

150 days 300 days

1000 days 2000 days

5-step explicit coupling result:

vc

kk ε

φ00ln =


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00.5

11.5

22.5

33.5

4

0 5 10 15

ABC

00.5

11.5

22.5

33.5

4

0 5 10 15

ABC

00.5

11.5

22.5

33.5

4

0 5 10 15

ABCq

(MPa

)

p' (MPa)

initialstate

A CB

Stress Path & Impact of the number of coupling periods

12-step coupling

one-way 5-step couplingp' (MPa)

p' (MPa)


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05

101520253035

0 50 100 150Vert

ical

dis

plac

emen

t (cm

)

Reservoir interface (m)

2000 days

1000 days

300 days150 days

Vertical displacement profile of reservoir interface

One-way simulation result:

Reservoir cap-rock interface (m)


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25

2526272829303132

0 50 100 150

one way5 steps12 steps

Vert

ical

dis

plac

emen

t (cm

)

Reservoir interface (m)

Vertical displacement profile of reservoir cap-rock interface


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ConclusionsModeling of SAGD geomechanical effects are necessaryReservoir – geomechanical coupled simulations are requiredSimulation results depend on the chosen coupled approachThe one-way approach, can indicate the most mechanically stressed areasThe explicit coupling approach is more accurate but also more time consuming

Current work :Reduction of CPU time by using a distinct grid methodApply the proposed approach to a heterogeneous mediaImplement the iterative coupling approach

numerical coupling of geomechanics and fluid flow...

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