Gas diffusion in a cylindrical coal sample – A general solution, approximation and error analyses

A new laboratory method for accurate measurement of the methane diffusion coefficient and its influencing factors in the coal matrix

“…The production rate of coalbed methane (CBM) is mainly controlled by diffusion in the matrix and the permeability within the cleat system [10]. Thus, the understanding of methane diffusion mechanism in coal matrix and the accurate determination the methane diffusion coefficients are of great significance for CBM production planning and economical reserve estimation [11].…”

“…diffusion coefficient determination methods include the particle method, the steady state method and the inverse diffusion method [10,11,[13][14][15]. Many scholars have extensively reviewed the influencing parameters on the diffusion coefficient.…”

Novel Dynamic Multiscale Model of Apparent Diffusion Permeability of Methane through Low-Permeability Coal Seams

“…42 Li derived an approximate solution of a cylindrical radial model without the consideration of the change of gas diffusion properties during the diffusion process from microscale pores to fractures. 43 Li put forward a radial diffusion equation of gas in a cylindrical coal core and conducted radial diffusion experiments. The gas diffusion coefficient in a large-scale coal core was obtained, and the gas flow characteristics were analyzed.…”

A Mercury Intrusion Porosimetry Method for Methane Diffusivity and Permeability Evaluation in Coals: A Comparative Analysis

“…However, in two coals with the same particle size and coal rank but different maceral composition, the previous research indicates that the coal with high inertinites shows a fast diffusivity [9][10][11][12][13]. For gas diffusivity, the determination methods may include the particle method, the steady state method and the inverse diffusion method [14][15][16]. The effective diffusivity strongly depends on pore size when the average pore size is less than 1 µm [17][18][19].…”

“…Consequently, permeability to gas results in higher values compared with permeability to liquid for a given porous medium including coals and shales. Many techniques can be used to measure the diffusivity and permeability in coals [14][15][16][20][21][22]. However, some scholars proposed some theoretical models to evaluate the diffusivity and permeability in porous media from the perspective of pore structure in coals.…”