The use of reservoir simulation coupled with geomechanics to model physical phenomena such as compaction, subsidence, induced fracturing, enhancement of natural fractures and/or fault activation, SAGD recovery etc.., has been increasing. Different methods of coupling have been investigated by numerous researchers: fully implicit coupling, iterative coupling and one way coupling. So far, the iterative explicit method appears to be the prefered method for field-scale simulation.

This method is a loose coupled approach between a reservoir simulator (finite volumes) and a geomechanical simulator (finite elements). At user-defined steps, the fluid pressures calculated by the reservoir simulator are transmitted to the geomechanical tool which computes the actual stresses and reports the modifications of the petrophysical properties (porosities and permeabilities) back to the reservoir simulator. In the classical iterative scheme, at each stress equilibration step, the reservoir simulation needs to be restarted from the previous converged step. This restart based scheme can be difficult to implement in practice within an industrial IT environment.

This paper presents a new iterative scheme which allows:

  • any reservoir simulator,

  • to be coupled with any nonlinear FEM package for the stress analysis, with no limitations on the functionality of either simulator.

This is achieved by performing the pressure/stress iterations at the end of a complete reservoir simulation. Porosity and permeability modifications at various times are calculated, and the complete reservoir simulation is then repeated. Iterations are continued until convergence is achieved.

The convergence of this new scheme is discussed and results are presented for two cases described below.

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