Inversion of gas permeability coefficient of coal particle based on Darcy's permeation model

Permeability is an important indicator for predicting gas drainage yield and preventing mine gas disasters. Gas permeability coefficient derived from the permeability is introduced in this work to develop a model of methane adsorption of coal particle based on Darcy's permeation, which is solved by our self-developed software, and then the methane isothermal adsorption of six granular coal samples are measured by quasi-constant pressure adsorption experiments. A new inversion approach for gas permeability coefficient of coal particle is performed by matching simulation results with experiment data. Meanwhile, the impacts of adsorption pressure and coal rank on gas permeability coefficient are also analyzed quantitatively. The results show that (i) a suitable gas permeability coefficient of coal particle can be determined by adjusting simulated curve to match with experimental data, which verifies the feasibility and effectiveness of the inversions; (ii) the gas permeability coefficient of coal particle decreases exponentially as the adsorption pressure or volatile matter content grows. This research provides an alternative approach to determine the permeability of granular coal samples and we hope it will bring some references to researchers.