西南石油大学学报(自然科学版) ›› 2017, Vol. 39 ›› Issue (4): 104-112.DOI: 10.11885/j.issn.16745086.2015.11.12.05

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The Adsorption and Desorption of Coal Bed Methane: A Review

ZHU Suyang, DU Zhimin, LI Chuanliang, PENG Xiaolong, WANG Chaowen   

  1. State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2015-11-12 Revised:2017-05-14 Online:2017-08-01 Published:2017-08-01

Abstract: In this study, we investigated progress in the following three aspects of coal bed methane(CBM) research:adsorption theory and experiments, the effects of water on adsorption and desorption, and liquid-solid adsorption theory. We summarized the achievements of gas phase adsorption theory in studying CBM adsorption, and, in particular, the influence of water. In addition, existing complications in gas phase adsorption theory with regards to CBM adsorption were analyzed, and the new liquid phase adsorption theory and CBM compound desorption model built on its basis were introduced. Different water phases have a variable impact on CBM adsorption. When water saturation is low in the coal sample, equilibrium moisture in the gas phase can significantly reduce the amount of CBM adsorbed. As water saturation reaches critical levels, water content has little effect on the amount of CBM adsorbed. Upon further increase in water content in the coal sample, liquid-state water in the injected coal sample increases the quantity of CBM adsorbed. The occurrence of CBM is not in agreement with the existing gas phase adsorption model. In contrast, the liquid phase adsorption model explains both the hydrocarbon generation condition of coal in an aqueous environment and the absence of critical desorption pressure in gas phase adsorption. Under the conditions of liquid phase adsorption, the desorption of CBM is a compound desorption process controlled by both gas phase and liquid phase desorption.

Key words: coal bed methane, adsorption process, water, desorption process, liquid phase adsorption, compound desorption

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