Field-Scale Geomechanical Modeling of an Intensely Faulted Gas Reservoir

The optimal exploitation of conventional and unconventional reservoirs is strongly dependent on the local tectonic stress field. Amongst others, wellbore stability, orientation of hydraulically induced fractures and - especially in fractured reservoirs - permeability anisotropies depend on the recent in situ stress. The workflow presented in this paper can be used to build 3D geomechanical models based on the Finite Element Method (FEM) and ranging from field-scale models to smaller, highly detailed submodels of specific fault blocks. This approach is successfully applied to an intensely faulted gas reservoir in the North German Basin, for which a field-scale model was built. The stresses predicted by the geomechanical FE model are calibrated against well data actually observed, like borehole breakouts and extended leak-off tests. Finally, the validated model can provide insights into the stress perturbations in the inter-well space and undrilled parts of the reservoir. In addition, the tendency of the existing fault network to slip or dilate in the present-day stress regime can be addressed.