Coalbed methane migration mechanism under adsorption-desorption condition in coal

Authors

LIU Yongqian, Mine Safety Technology Branch, China Coal Research Institute, Beijing 100013, China; National Key Lab of Coal High Efficient Mining and Clean Utilization(China Coal Research Institute), Beijing 100013, China
ZHANG Shulin, Mine Safety Technology Branch, China Coal Research Institute, Beijing 100013, China; National Key Lab of Coal High Efficient Mining and Clean Utilization(China Coal Research Institute), Beijing 100013, China
SHU Longyong, Mine Safety Technology Branch, China Coal Research Institute, Beijing 100013, China; National Key Lab of Coal High Efficient Mining and Clean Utilization(China Coal Research Institute), Beijing 100013, China

Abstract

The migration law of coalbed methane(CBM) with adsorption has always been the focus of attention in the field of coalbed methane geology. In order to study the mechanism of CBM migration under adsorption-desorption state, the deduction of gas adsorption-desorption equation and theoretical analysis of gas diffusion-seepage in porous media were carried out, and new viewpoints were put forward by means of experimental analysis of CBM migration. The results identified that:(1) for the CBM migration, pore structure of coal body has the storage-resistance effect, the dual functions of gas storage and gas pressure drop form the basic feature of coal matrix, (2) adsorption reaction time, adsorption rate, growth rate, adsorption equilibrium time and the maximum adsorption capacity are 4 key indexes of the different gases, (3) diffusion and seepage coexist in the process of CBM migration. When the gas pressure in fracture and macropore is higher than that in medium-micropore system, the gas migration velocity is dominated by seepage, otherwise diffusion is dominant.

Keywords

the migration mechanism of CBM, adsorption and desorption, capacitive resistance effect, dynamic adsorption, binary medium, molecular polarity

DOI

10.3969/j.issn.1001-1986.2019.04.003

Recommended Citation

LIU Yongqian, ZHANG Shulin, SHU Longyong, et al. (2019) "Coalbed methane migration mechanism under adsorption-desorption condition in coal," Coal Geology & Exploration: Vol. 47: Iss. 4, Article 4.
DOI: 10.3969/j.issn.1001-1986.2019.04.003
Available at: https://cge.researchcommons.org/journal/vol47/iss4/4

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