Gas diffusion in coal powders is a multi-rate process

Mathias, Simon; Dentz, Marco; Liu, Qingquan

doi:10.1007/s11242-019-01376-x

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Authors

Professor Simon Mathias s.a.mathias@durham.ac.uk
Professor

Marco Dentz

Qingquan Liu

Abstract

Gas migration in coal is strongly controlled by surface diffusion of adsorbed gas within the coal matrix. Surface diffusion coefficients are obtained by inverse modelling of transient gas desorption data from powdered coals. The diffusion coefficient is frequently considered to be dependent on time and initial pressure. In this article, it is shown that the pressure dependence can be eliminated by performing a joint inversion of both the diffusion coefficient and adsorption isotherm. A study of the log–log slope of desorbed gas production rate against time reveals that diffusion within the individual coal particles is a multi-rate process. The application of a power-law probability density function of diffusion rates enables the determination of a single gas diffusion coefficient that is constant in both time and initial pressure.

Citation

Mathias, S., Dentz, M., & Liu, Q. (2020). Gas diffusion in coal powders is a multi-rate process. Transport in Porous Media, 131, 1037-1051. https://doi.org/10.1007/s11242-019-01376-x

Journal Article Type	Article
Acceptance Date	Dec 2, 2019
Online Publication Date	Dec 10, 2019
Publication Date	2020
Deposit Date	Dec 3, 2019
Publicly Available Date	Dec 10, 2020
Journal	Transport in Porous Media
Print ISSN	0169-3913
Electronic ISSN	1573-1634
Publisher	Springer
Peer Reviewed	Peer Reviewed
Volume	131
Pages	1037-1051
DOI	https://doi.org/10.1007/s11242-019-01376-x

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