Abstract
We investigate the coupled flow/geomechanics behavior of naturally fractured permeable rocks. Model and simulation of these processes is very challenging due to the multi-scale nature of the problems and the strong coupling that exists between flow and mechanical behaviors. We present a numerical procedure for the simulation of two-phase immiscible and compressible flow coupled to mechanical deformation in two-dimensional discrete-fractured porous media. To achive this coupling, we implemented an iterative procedure between the flow and the mechanical deformation simulations in which the fluid pressure in the fracture is used as boundary condition at fracture walls. The deformation problem is solved by discretizing the poroelastic equilibrium equations following a Galerkin Finite Element approach, while the flow part was solved using the discrete fracture control volume method. For the flow simulation fractures are assumed to be n-1 dimensional elements where n is the dimension of the overall problem. We considered continuity in capillary pressure and the implied discontinuity in saturation. The model introduces a coupling between mechanical behavior and flow properties by relating absolute permeabilities to the fracture deformation. This approach allows us to study the effects of the coupling on the oil recovery in stress sensitive fractured porous media. We present results for the simulation of synthetic cases to illustrate some of the geomechanical effects that may arise during oil recovery in fractured reservoirs.
