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Sequential Methods for Coupled Geomechanics and Multiphase Flow

Sequential Methods for Coupled Geomechanics and Multiphase Flow

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5.3 Case 5.2 (1D injection–production problem). Evolution of the dimensionless<br />

pressure as a function of dimensionless time (pore volume produced). Shown<br />

are the results <strong>for</strong> the fully coupled method, the fixed-strain, <strong>and</strong> fixed-stress<br />

splits. Top: coupling strength τ = 0.83. Bottom: coupling strength τ = 1.21. 142<br />

5.4 Case 5.2 (1D injection–production problem). Results are shown <strong>for</strong> the fixed-<br />

strain split, with two different coupling strengths: τ = 0.95 (top), <strong>and</strong> τ =<br />

1.05 (bottom), <strong>and</strong> two very different time step sizes. The stability of the<br />

fixed-strain split is independent of time step size. The fixed-strain split is<br />

stable if τ < 1 <strong>and</strong> unstable if τ > 1, regardless of time step size. . . . . . . 144<br />

5.5 1D problem with injection <strong>and</strong> production (Case 5.2). Kdr = 1 GPa. α = 0.5<br />

<strong>for</strong> both flow <strong>and</strong> mechanics is considered. Top: τ = 0.83. Bottom: τ = 1.11. 145<br />

5.6 Stability behaviors of different η’s <strong>and</strong> τ’s. Top: pressure history at the<br />

observation well when τ = 3.33. Bottom: pressure history at the observation<br />

well when τ = ∞. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146<br />

5.7 Behavior of the undrained <strong>and</strong> fixed-stress splits <strong>for</strong> cases with high coupling<br />

strength. Top: Case 5.1 with τ = 16.67. Bottom: Case 5.2 with τ = 12.12.<br />

In both cases, the fixed-stress split requires one single iteration per time step<br />

to match the fully coupled solution, while many iterations are required <strong>for</strong><br />

the undrained split. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148<br />

5.8 Case 5.3 (the M<strong>and</strong>el problem). Evolution of the pressure at the observation<br />

well as a function of dimensionless time. Shown are the results <strong>for</strong> the fully<br />

coupled, fixed-strain, <strong>and</strong> fixed-stress split methods. Top: τ = 0.90. Bottom:<br />

τ = 1.10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150<br />

5.9 Case 5.3 (the M<strong>and</strong>el problem). Evolution of the dimensionless vertical dis-<br />

placement on the top as a function of dimensionless time. Shown are the<br />

results <strong>for</strong> the fully coupled, fixed-strain, <strong>and</strong> fixed-stress split methods. Top:<br />

τ = 0.90. Bottom: τ = 1.10. . . . . . . . . . . . . . . . . . . . . . . . . . . . 151<br />

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