Numerical Simulation of Fully Coupled Fluid-Flow/Geomechanical Deformation in Hydraulically Fractured Reservoirs

TLDR: In this article, a fully coupled geomechanics/fluid-flow simulation model was developed to study the behavior of the pore pressure and stress distribution in a hydraulically fractured well-reservoir system.

Abstract: A fully-coupled geomechanics/fluid-flow simulation model has been developed to study the behavior of the pore pressure and stress distribution in a hydraulically fractured wellreservoir system. The 3D finite difference, fully implicit model takes into account the non-linear poroelastic deformation of the reservoir rock. The numerical model incorporates a local grid refinement around the perforation depth. Equations that govern fluid flow are coupled with the equations that govern rock deformation in the fracture and the reservoir, then the resulting equations are solved numerically under different reservoir-fracture conditions. The initial and boundary conditions used in the solution of the equations are defined as follows: (i) Zero incremental pressure and displacements at initial conditions and (ii) Closed system for the fluid flow model, non-deformable boundaries. A laboratory-derived stress-dependent permeability correlation is introduced to compute the permeability in both the rock without fracture and the fractured rock. The use of this correlation avoids the need to have initial permeability values and these values are computed using the effective stress acting on the rock. Simulator is applied to selected simulation examples to show the effects of isotropic and anisotropic stress states on the fracture shape and distributions of fluid pressure and vertical and horizontal stresses.