New permeability test based on falling head method in rock core

Abstract

The permeability of rock matrices is not routinely measured because the equipment is expensive and the measurements are time-consuming. We designed a new laboratory permeability test using low-cost apparatus and investigated its performance. The method is a variation of the falling head method, in which the standpipe used as the pressure source is replaced with a pressure accumulator. High pressure is applied to a rock specimen, making it possible to measure permeability within an hour. The apparatus produces radial flow from the surface to a central hole drilled in a cylindrical specimen. We determined that the apparatus measures hydraulic conductivity in the range of 3.5×10 -10 to 2.6×10-4 cm/s. The error in hydraulic conductivity obtained from repeated measurements is ±~10%, and the difference in conductivity between this method and the standpipe method is ~25%. For a rock with a hydraulic conductivity of 3.0×10-9 cm/s, measurement takes at least 800 s.