New Permeability Test Based on Falling Head Method in Rock Core

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 3.510 super(-10) to 2.610 super(-4) cm/s. The error in hydraulic conductivity obtained from repeated measurements is plus or minus similar to 10%, and the difference in conductivity between this method and the standpipe method is similar to 25%. For a rock with a hydraulic conductivity of 3.010 super(-9) cm/s, measurement takes at least 800 s.