Abstract

Because of the gas compressive storage effect, permeability as a critical parameter describing the flow efficiency for liquid might not apply to gas, but gas pressure diffusivity that takes into account of gas compressive effect might do. In this study, pulse-decay experiments were performed on one shale core under different pore pressures with different pressure pulse magnitudes. A novel approach was put forward to determining the intrinsic permeability and gas slippage factor through a single pulse-decay experiment, which is significantly more efficient than the conventional method that requires multiple operations. We verify that gas pressure diffusivity instead of the permeability is the appropriate measure of the efficiency of gas flow, given the fact that the ratio of pulse size over diffusivity is roughly proportional to the experiment duration. We obtain consistent results using different empirical models to capture the intrinsic permeability, gas slippage factor, and pressure-dependent apparent gas permeability simultaneously.