Flow channeling in a single fracture induced by shear displacement

The effect on the transport properties of a fracture of a shear displacement (u) over right arrow between its complementary surfaces is investigated experimentally and numerically. The shear displacement (u) over right arrow induces an anisotropy of the fracture aperture field with a correlation length scaling of vertical bar(u) over right arrow vertical bar, which is significantly larger in the direction perpendicular to (u) over right arrow. This reflects the presence of long fluid flow channels perpendicular to the shear displacement, resulting in a higher effective permeability in that direction. Such channels will have a strong influence on the transport characteristics of a fracture, such as, for instance, its thermal exchange area, crucial for geothermal applications. Miscible displacement fronts in shear-displaced fractures obtained experimentally display a self-affine geometry with a characteristic exponent directly related to that of the fracture surfaces. We present a simple model, based on the channeling of the aperture field, which reproduces the front geometry when the mean flow is parallel to the channels created by the shear displacement. (c) 2006 CNR. Published by Elsevier Ltd. All rights reserved.