Coupling of Stress Dependent Relative Permeability and Reservoir Simulation

Abstract

Abstract Geomechanics is increasingly being considered for inclusion in reservoir simulation, since conventional simulators do not honor deformation resulting from the interaction between stress and fluid flow response in a porous medium. When a reservoir responds to changes in effective stress, the bulk volume adjusts, changing the pore geometry and dependent parameters like porosity, absolute permeability and effective permeability, and phase saturations. Most of the recently developed sequentially coupled approaches for coupling flow and geomechanics have focused on updating porosity and absolute permeability while changes in relative permeability (due to geomechanics) is ignored. For multiphase flow systems, relative permeability functions are one of the most influential parameters controlling fluid movement and distribution. To examine how geomechanically-influenced relative permeability may impact flow, a sequentially coupled reservoir geomechanical simulation study was conducted. The simulation workflow incorporated automatic updates of the relative permeability table for each grid block in the model at every time-step. Data for populating the geomechanical relative permeability tables was extracted from recent experimental test results reported in the literature. Results from the simulation studies showed a significant difference in recovery factors when the impact of geomechanics on relative permeability functions was integrated into coupled simulation compared to when only changes in porosity and absolute permeability were used. Coupled models which incorporate not only the change in permeability and porosity but also the changes in relative permeability can lead to more realistic production forecast especially for reservoirs under improved or enhanced oil recovery scheme as found in heavy oil and oil sands projects.