Based on the Langmuir adsorption isotherm, we have determined coalbed methane desorption efficiency. Three key pressure points are observed on the desorption efficiency curves: turning pressure, transition pressure, and sensitive pressure. Based on data for the key pressure points and the critical desorption pressure for the isothermal desorption process at reduced pressure (depressurization/desorption), we can divide the process into 5 stages: the zero desorption stage, the slow desorption stage, the transitional desorption stage, the quick desorption stage, and the sensitive desorption stage. We use an example to show that during coalbed methane production the zero desorption stage does not contribute to the productivity, the slow and transitional desorption stages make a small contribution, and the major contribution comes from the quick and sensitive desorption stages. A higher sensitive pressure means peak methane production is achieved faster. Higher desorption efficiency obviously means a faster rate of increase in production volume.
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This study was supported by the National Grand Science and Technology Special Project of China (Project No. 2011ZX05042-002-001). We would like to thank Professor Chuanliang Li for valuable advice during preparation of the paper.
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Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 48– 52, July – August, 2014.
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Ma, F., Wang, Y., Li, H. et al. Staged Coalbed Methane Desorption and the Contribution of Each Stage to Productivity. Chem Technol Fuels Oils 50, 344–353 (2014). https://doi.org/10.1007/s10553-014-0531-3
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DOI: https://doi.org/10.1007/s10553-014-0531-3