Influence of driving stress on cataclastic deformation and permeability in well cemented sandstones

Although many mechanisms for fault sealing have been identified, the microscale processes involved are still not well understood. This paper reports continuous steady-state permeability on core plugs deformed triaxially at effective confining pressures from 6.9 MPa to 55.2 MPa and with slip displacements of up to 3 mm in order to better understand the coupling between mechanical deformation and fluid flow response. The results also experimentally quantify the influence of in-situ remote driving stress on cataclastic deformation associated with varying degrees of fault slip displacement. The permeability response is seen to vary systematically from a linear to an exponential decrease with increasing effective stress. This behaviour is related to microstructural textures and in particular to grain size of comminuted gouge material. An empirical law relating fault sealing and deformation is presented. © 2001 Elsevier Science Ltd. All rights reserved.