LAUSR

Diffusion coefficient is usually used to evaluate the methane (CH4) diffusion properties in the coal matrix and is vital to coalbed methane (CBM) development. Although extensive literature on the CH4 diffusion coefficient can be obtained, most of them aim at the whole coal or coal rank instead of the macrolithotype. Additionally, the primary structure of coal was destroyed with the common determination technologies (e.g., the particle, steady-state, and inverse diffusion methods) which could result in great errors. In this work, to avoid the shortcomings of the above methods, nine flake coal samples from six coal mines in the Qinshui and Ordos Basins were prepared to determine the CH4 diffusion coefficient with the slab calculation model. Meanwhile, the effects on the diffusion from the gas pressure, temperature, water saturability, and coal pore structure, and the gas adsorption capacity controlled by the coal rank and macrolithotype, were analyzed to reveal the diffusion mechanism (mode) at the CBM rese...