Influence of driving stress on cataclastic deformation and permeability inwell cemented sandstones

Although many mechanisms for fault sealing have been identified, the micros cale processes involved are still not well understood. This paper reports c ontinuous steady-state permeability on core plugs deformed triaxially at ef fective confining pressures from 6.9 MPa to 55.2 MPa and with slip displace ments of up to 3 mm in order to better understand the coupling between mech anical deformation and fluid flow response. The results also experimentally quantify the influence of in-situ remote driving stress on cataclastic def ormation associated with varying degrees of fault slip displacement. The pe rmeability response is seen to vary systematically from a linear to an expo nential decrease with increasing effective stress. This behaviour is relate d to microstructural textures and in particular to grain size of comminuted gouge material. An empirical law relating fault sealing and deformation is presented. (C) 2001 Elsevier Science Ltd. All rights reserved.