The mechanics of clay smearing along faults

Abstract

A clay- or shale-rich fault gouge can significantly reduce fault permeability. Therefore, predictions of the volume of clay or shale that may be smeared along a fault trace are important for estimating the fluid connectivity of groundwater and hydrocarbon reservoir systems. Here, we show how fault smears develop spontaneously in layered soil systems with varying friction coefficients, and we present a quantitative dynamic model for such behavior. The model is based on Mohr-Coulomb failure theory, and using discrete element computations, we demonstrate how the model framework can predict the fault smear potential from soil friction angles and layer thicknesses.