Geomechanics in Reservoir Simulation: Overview of Coupling Methods and Field Case Study

Abstract : The paper addresses the modeling of geomechanical effects induced by reservoir production and their influence on fluid flow in the reservoir. Geomechanical effects induced by reservoir production can be particularly pronounced in stress sensitive reservoirs, such as poorly compacted reservoirs and fractured reservoirs. The authors review the main coupled mechanisms associated with the production of these reservoirs, and describe the different approaches that can be used to solve the coupling between fluid flow and geomechanical problems. A field case study is then presented. A stress dependent reservoir simulator-ATH2VIS-was used to quantify effects associated with the production of a highly heterogeneous and compartmentalized limestone reservoir. This simulator relies on a partial coupling approach with different time steps for reservoir and geomechanical simulations and manages data exchanges at given time intervals between the ATHOSTM reservoir simulator developed at IFP and the VISAGETM geomechanical simulator (VIPS Ltd. , 2001). The results of the coupled reservoir geomechanical simulations indicate that perturbation of the reservoir mechanical equilibrium specifically leads to progressive strain localization on a limited number of faults. Only specific parts of these faults are critically stressed, depending on pore pressure variations in their vicinity, temperature variations, and fault strikes compared with stress orientation. The normal strains resulting from geomechanical computations are interpreted in terms of permeability variations using a fracture and fault permeability model to improve the dynamic description of fluid flow and history matching.