Predicting pre- and post-failure stress conditions and deformation patterns in fault zones by the FRAP numerical tool

Faults show strongly variable lateral permeability, largely dependent from the variability of amount of deformation along them. Several well-exposed examples confirm the difficulty in the task of predicting fault permeability. The development of fault deformation zones and fault cores, including fault gauge and cataclastic bands, is a function of several variables, including rock rheology, stress and strength conditions along the fault surface, fluid pressures, and the fault kinematics. Once you know the appropriate boundary conditions, analytical equations allow to compute an index of fault gauge formation at any point, as well as the geometry and type of expected (brittle) deformations. Due to the variability of the aforementioned values, a critical parameter is the displacement (amount and path) on the fault surface. This was be numerically integrated to properly predict the zones where higher deformation is expected. These computations were included in the FRAP numerical tool, including multiple event and multiple fault settings. External structural data can also be integrated in the computation, allowing to properly tune the prediction. Examples of applications includes the study of the variation of fault permeability in geothermal environment, as well as the modelling of the expected permeability in a grid of extensional faults in oil reservoirs.