GEOMECHANICALLY COUPLED SIMULATION OF FLOW IN FRACTURED RESERVOIRS

Abstract

The vast majority of geothermal reservoirs are naturally fractured at various intensities and scales. These fractures are usually the main pathways for fluid flow and thus their properties control to a large degree both the production profile from producing wells and the well injectivity. Because most fractures are stress-sensitive, their hydraulic conductivities will change with changes in bottom-hole-flowing and reservoir pressures causing variations in production profiles between wells. More specifically, fractures can hydraulically (partially) open or close due to a decrease (caused by injection) or increase (caused by production) in the effective stress. Because flow properties are a function of effective fracture aperture it is possible to predict reservoir behavior using the relationship between the mechanical behavior of natural fractures (in response to in situ stress and pore pressure changes) and their hydraulic properties. We discuss here a case study of the integration of geological, geophysical, geomechanical, and reservoir engineering data to characterize the in situ stresses, the natural fracture network and the controls on fracture permeability in geothermal reservoirs.