Answers to Some Questions About the Coupling Between Fluid Flow and Rock Deformation in Oil Reservoirs

Abstract

AbstractIn recent years operators have shown great interest in the coupling between the multiphase fluid flow and the rock deformation in oil reservoirs and surrounding rocks. Frequently, the geomechanical effects are approximated in a conventional reservoir simulation through only the rock compressibility. This means that the stresses in the reservoir and surrounding rocks may not be in equilibrium with the pore pressure, since the geomechanical behavior is not considered. The ideal solution for this coupled problem is to introduce the geomechanical effects through the stress analysis solution and to implement a scheme that assures that the governing laws of the flow simulation and stress analysis are obeyed simultaneously in each time step. It was developed one methodology to couple a conventional reservoir simulator (ECLIPSE) and a stress analysis program (Abaqus/CAE) that employs the pseudo-compressibility and the porosity as coupling parameters. It was implemented a C++ source code that manages all the work flow of the partial coupling in a fully automated manner. Two schemes of partial coupling were implemented: a) an iteratively two way coupled scheme and b) a one way coupled scheme. In this paper, it was examined the hydromechanical interaction results of these coupling schemes evaluating a problem of the soft reservoir and its surrounding stiff rock that was presented in others works. The results of average pore pressure in the reservoir, pore pressure field, subsidence and compaction were calculated. The results of the simulations using pseudo-compressibility as a coupling parameter in an iteratively two way coupled scheme are showed and compared with a fully coupled scheme.