CBM well drainage data-based dynamic inversion study of reservoir gas content

Authors

MA Dongmin, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China; State Key Laboratory of Coal and Coalbed Methane Co-Mining Technology, Jincheng 048012, China
JI Yusong, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
CHEN Yue, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
ZHENG Chao, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
TENG Jinxiang, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
MA Zhuoyuan, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China
XIAO Jialong, College of Geology and Environment, Xi'an University of Science and Technology, Xi'an 710054, China

Abstract

The gas content of coal reservoir is the core parameter of coalbed methane production. There is an error between the measured gas content and the real gas content of coal reservoir. In this paper, based on the gas production of Haishiwan coalbed methane wells in different periods and the decrease of the "constant volume" of the gas content of coal reservoirs, the real-time gas content of coal reservoirs is inverted, and the change rule of the real-time gas content in the process of coalbed methane well drainage is explored. The results show that: (1) The gas content of coal reservoir decreases linearly with the drainage time t. the gas production of different long coalbed methane wells is consistent with the decrease of coal reservoir gas content, and follows the characteristics of "constant volume" gas production, that is, the gas production of single coalbed methane well is the "constant volume" production of coal matrix; (2) The gas production of coalbed methane wells has nothing to do with the original gas content of coal reservoir, but is related to the reduction of gas content; (3) The coal reservoir is a water-resistant layer, and hydraulic fracturing is difficult to change the combined water state of coal-based micropore channels. The CH₄ production process is controlled by the water-coal interface. Coalbed methane production is the result of mass transfer at the three-phase interface of "CH₄, coal and water", in which water turbulence provides and transfers energy to stimulate the desorption and production of CH₄ in block coal.

Keywords

Yaojie mining area, Haishiwan Coal Mine, coalbed methane, constant volume, dynamic inversion of drainage data

DOI

10.3969/j.issn.1001-1986.2021.06.007

Recommended Citation

MA Dongmin, JI Yusong, CHEN Yue, et al. (2021) "CBM well drainage data-based dynamic inversion study of reservoir gas content," Coal Geology & Exploration: Vol. 49: Iss. 6, Article 8.
DOI: 10.3969/j.issn.1001-1986.2021.06.007
Available at: https://cge.researchcommons.org/journal/vol49/iss6/8

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