Application of X-ray CT Method to Permeability Tests of Rock under Low Pressure Condition

X-ray Computed Tomography (CT) is successfully applied to the visualization of water infiltration into dry rock, and to the quantitative determination of the permeability in rock. A multi-stage pressurization procedure is applied to a one-dimensional horizontal water infiltration test under low pressure conditions, and in which the volumetric water content at each point within a rock specimen is precisely monitored by means of X-ray CT. Case examples make clear that the subtraction of X-ray CT images is an effective procedure available for the flow field analysis dependent on the pore structure. Applying the Green-Ampt model, the coefficient of permeability and water entry pressure was evaluated. The result was consistent with the pore size distribution obtained by the mercury intrusion porosimeter.