Evaluating Fracture Roughness and its Effect on Fluid Flow

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The PIs propose to measure hydraulic conductivities, apertures, and roughnesses in a suite of fractures from rocks of varying petrology with and without fracture skins. High-resolution X-ray computed tomography (HRXCT; 250micron resolution) will be used define the fracture geometry and surface roughness of natural rock fractures. In many natural fractures of hydraulic significance, the scale of the asperities will equal or exceed the scale of the aperture (i.e., the asperity heights exceed the mean aperture). In this situation, the classical fluid-mechanics concept of surface roughness simply doesn't apply. The hypotheses are: 1. Fracture roughness is a controlling factor for fluid flow and transport of solutes and colloids. 2. Improvements can be made upon the empirical laws for fluid flow in rough fractures. 3. Roughness and its effects are inferable from geological factors, including petrology, grain size, and fracture skin compositions. The project includes Hydraulic tests, roughness analysis, petrographic assessment on Granites, Sandstones, tuffs and carbonates.