Numerical Modeling of Flow Induced Shear Failure in Fractured Reservoirs

Abstract

Fluid pressure induced shear failure in fractured domains is coupled to the flow due to changes in permeability, aperture and pore volume. Flow inside the fractures is governed by mass balance and flow resistance, and the key variables are fluid pressure and fracture aperture. A time dependent model based on aperture relaxation was implemented and coupled with the mechanics of failure. This approach accounts for the slow fluid mechanical timescale compared to the fast ones typical for failures. Numerically, such a relaxation scheme improves stability and provides a suitable timescale for the flow calculation. Note that this model well reflects the flow physics, where the fluid cannot immediately occupy the newly created volume. The slip along fracture, however, occurs very fast, that is, it is in the order of the failure timescale.