In situ visualization of fluid flow image within deformed rock by X-ray CT

Abstract

We applied an X-ray computed tomography (CT) imaging method to study fluid advection in a laboratory permeameter in order to visualize the advecting fluid image during permeability testing under atmospheric pressure and to elucidate the relationship between fluid flow properties within fault-related rocks and their deformation mechanism. The X-ray CT images show high-resolution, three-dimensional fluid flow distribution in the fault-related rocks. A fault zone without grain cataclasis enables fluid flow, whereas cataclastic fault zones act as barriers. The fluid flow properties of the deformation bands are strongly dependent on the cataclastic fabrics. In sheared rock, including some cracks, only connected cracks can function as fluid conduits. The localized permeabilities along permeable fault zones and fractures, calculated using fluid front rates, are two orders higher than averaged bulk permeability derived from the pressure or volume difference between inflow and outflow in the permeameter.