Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

5.3. NUMERICAL MODELLING
MORE FLUID FLOW
SIMULATION
Fluid-flow iteration
loop (i=1,ni)
MORELF MESSAGE
PASSING INTERFACE
k=k+1
ELFEN GEOMECHANICAL
SIMULATION
Geomechanical iteration
loop (j=1,ng)
Solve for pore
pressure field
Pass pore
pressures to
ELFEN
Solve for displacement
No
Converged
Yes
Converged
No
Yes
Compute convergence of
coupled system
(Φk - Φk-1/Φk ~ 0)
Update pore volume (Φk)
Update permeability
Continue iterations
No
Converged
Yes
Move on to
next time step
Figure 5.4: Iteration algorithm for coupled geomechanical modelling. At each timestep, MORE
(green) computes the pore pressure field, which is passed via the MPI (blue) to ELFEN (red),
which computes the geomechanical deformation. The MPI assesses whether the solution has
converged - if it hasn’t then the iteration is repeated, if it has then the MPI moves on to the next
timestep.
simulator are passed to the geomechanical simulation at user-defined timesteps. The results of the
geomechanical simulation are not passed back to the fluid flow simulation. As a result, this method
will only be appropriate where deformation is not large enough to significantly affect porosity and
permeability.
For the explicit coupling method, the fluid flow simulator is again run until a user-defined time
step, where the pore pressure is passed to the geomechanical simulation. However, unlike the one-way
coupling method, the changes in porosity and permeability are returned to the fluid flow simulator
for use in subsequent time steps. As a result, the explicit method is more accurate than the one-way
method, but as it requires the passing of data in two directions, is more computationally expensive
(Dean et al., 2003). The iterative method is similar to the explicit method, except for at each time
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