Study on density of the supercritical methane

Authors

ZHANG Xinbin, School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454003, China; Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454003, ChinaFollow
SONG Dangyu, School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454003, China; Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454003, China
LI Yunbo, School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454003, China; Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454003, China
QI Yong'an, School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454003, China; Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454003, China
FAN Shunli, School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454003, China; Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Jiaozuo 454003, China

Abstract

The density of supercritical methane is not only an important parameter for calculation of unconventional natural gas resources and adsorption capacity of methane in coal, but also a main indicator for measurement of the diffusion efficiency of supercritical methane and the ability to dissolve organic matter. Through analysis and comparison of the applicability of various gas state equations, it is realized that the Helmholtz energy state equation can accurately calculate the density of methane under the conditions of 0-30 MPa and 270-360 K. A calculation program for methane density was written using Microsoft Office Excel, and the error was less than 0.05% compared with NIST commercial software. Finally, the changing of methane density was analyzed. In the range of 0-100 MPa and 270-360 K, the density of methane increases with the increase of pressure. The increase rate is greater before 30 MPa and the sensitivity to temperature is strong. Afterwards, the growth rate gradually slows down, while the sensitivity decreases. Under the in-situ condition of the coal seam, with the increase of buried depth, the density increases with temperature and decreases with pressure. Under the combined action of temperature and pressure, the density of methane first increases approximately linearly, and the growth rate gradually decreases. The results provide basic parameters for the occurrence and potential prediction of deep CBM.

Keywords

supercritical methane, methane density, gas state equation, Helmholtz energy, CBM resources

DOI

10.3969/j.issn.1001-1986.2021.01.014

Recommended Citation

ZHANG Xinbin, SONG Dangyu, LI Yunbo, et al. (2021) "Study on density of the supercritical methane," Coal Geology & Exploration: Vol. 49: Iss. 1, Article 15.
DOI: 10.3969/j.issn.1001-1986.2021.01.014
Available at: https://cge.researchcommons.org/journal/vol49/iss1/15

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