Geomechanically Coupled Simulation of Flow in Fractured Reservoirs

Abstract

Capturing the necessary and sufficient detail of reservoir hydraulics to accurately evaluate reservoir behavior remains a significant challenge to the exploitation and management of fracture-dominated reservoirs. In low matrix permeability reservoirs, stimulation response is controlled largely by the properties of natural and induced fracture networks, which are in turn controlled by the in situ stresses, the fracture distribution and connectivity and the hydraulic behavior of the fractures. This complex interaction of fracture flow systems with the present-day stress field compounds the problem of developing an effective and efficient simulation to characterize, model and predict fractured reservoir performance.

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. Flow through the individual fractures which form the connected network was explicitly modeled. Fracture stress sensitivity was coupled to the flow simulation through the DFN with dynamic adjustment of aperture to effective normal and shear stresses (after Moos and Barton 2008) and calibrated with microseismic data (positions and times of events) and injection data (rates and pressures). The results highlight the importance of combining all available data, including microseismic, wellbore image, and flow and stimulation test data, to determine reservoir flow behavior and its response to stimulation.