A Method To Implement Permeability Anisotropy Associated With Fault Damage Zones in Reservoir Simulation

Abstract

SummaryIn this study, we present a method to incorporate the effects of fault damage zones (DZs) in a reservoir-simulation model. Permeability anisotropy associated with fault DZs depends on many factors, including the geometry of the faults in the reservoir and the associated dimension and density of fractures in the DZs. To model permeability anisotropy caused by fault DZs, we start by using geomechanically constrained discrete fracture models of DZs. Then, we use the orientation and size of the faults with reference to the grid axes to incorporate the effect of permeability anisotropy in the simulation grid. In this case study, in which faults are formed in an extensional regime, DZs show increased permeability along the strike of the fault and in the vertical direction, but there is no significant change in the permeability perpendicular to the faults. Inclusion of DZs in the simulation model shows significant improvement in the history matching in comparison to a base reservoir-simulation model with no DZs. Further, we analyze the uncertainty of the DZ modeling in the reservoir simulation by simulating multiple equiprobable models.