Using a fully coupled flow and geomechanical simulator to model injection into heavy oil reservoirs

In this paper, the geomechanical factors that may affect injection processes in heavy oil recovery are investigated. To accurately capture the geomechanical effects, we employed a numerical formulation that allows fully coupling of nonlinear geomechanical deformation and multicomponent porous media flows. Two salient features of this new coupling formulation are the following: (1) all flow and geomechanical equations are solved implicitly in one single matrix equation, and (2) it allows reuse of matrices from both a traditional fully implicit multicomponent reservoir simulator and a nonlinear geomechanics simulator. The former feature ensures stable coupling between the reservoir flow and geomechanics, and the latter significantly reduces the programming work. Numerical examples are given to demonstrate the accuracy and convergence performance of the new formulation. The proposed formulation is then applied to model injection into heavy oil reservoirs. The numerical investigation revealed that geomechanical factors, such as in situ stress anisotropy and the uneven deformation of reservoir rock and attached impermeable rock, can result in skewed or nonuniform plastic strain and, hence, alter the sweep of the injected fluid. Coupled geomechanics simulation also gives rather different transient pressure response from that of uncoupled simulation. Copyright (C) 2012 John Wiley & Sons, Ltd.