New developments of the Gas Research Institute method for the permeability measurement of porous media

This work reports on new developments of an unsteady-state method to measure the permeability and porosity of permeable porous materials, extending the so-called Gas Research Institute method beyond its classical use. These extensions allow one to carry out measurements on samples having a cylindrical shape in the case of one- or three-dimensional (or axisymmetric) flows. They rely on the derivation of the quasi-analytical solutions that are required to interpret the experimental data by solving an inverse problem. The only simplifying assumption is that the compressibility of the probing gas can be treated as a constant over the range of pressure variations during measurement. The relevance of the method, together with the validity of this hypothesis, is checked over a wide range of porosity and permeability values through a sensitivity analysis and a comparison with direct numerical simulations of the complete initial boundary value problem. The efficiency of the method is further illustrated with experiments performed on four different porous materials in one-dimension and axisymmetric configurations for permeabilities ranging between 10^-14 and 10^-19 m². The potential capability of diagnosing heterogeneous and/or anisotropic materials is highlighted. These new developments open the way for further extensions to samples of arbitrary shapes or partially saturated by a trapped fluid.