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Sequential Methods for Coupled Geomechanics and Multiphase Flow

Sequential Methods for Coupled Geomechanics and Multiphase Flow

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Chapter 6<br />

<strong>Coupled</strong> <strong>Multiphase</strong> <strong>Flow</strong> <strong>and</strong><br />

<strong>Geomechanics</strong><br />

6.1 <strong>Sequential</strong> <strong>Methods</strong> <strong>for</strong> <strong>Multiphase</strong> <strong>Flow</strong><br />

Here, we analyze the stability <strong>and</strong> convergence of sequential implicit methods <strong>for</strong> multiphase<br />

flow. Let us denote by A m the original operator of coupled multiphase flow <strong>and</strong> mechanics,<br />

shown in Equations 2.1 <strong>and</strong> 2.2 in Chapter 2. The superscript m in the operators, (·) m ,<br />

means multiphase. Using the fully coupled method, the discrete approximation of A m is<br />

written as:<br />

⎡<br />

⎤<br />

⎡<br />

⎣ un<br />

pn ⎦<br />

J<br />

Am fc<br />

−→ ⎣ un+1<br />

p n+1<br />

J<br />

⎤<br />

⎦, where A m fc :<br />

⎧<br />

⎪⎨ Div σ + ρbg = 0,<br />

⎪⎩ ˙<br />

mJ + Div wJ = (ρf)J,<br />

(6.1)<br />

where we solve the coupled problem simultaneously using the Newton-Raphson method.<br />

Then the fully coupled method leads to the following system of Equations:<br />

⎡<br />

⎣ Km −LT ⎤⎡<br />

m<br />

⎦⎣<br />

Lm<br />

<br />

F m<br />

<br />

δu<br />

⎤<br />

⎦<br />

δpJ Jfc,m<br />

163<br />

n+1,k<br />

= −<br />

⎡<br />

⎣ Ru<br />

R p<br />

J<br />

⎤<br />

⎦<br />

n+1,k<br />

, (6.2)

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