Title: Research on gas percolation and catastrophe behaviour of gas-bearing coal under low index

Authors: Tie Li; Xianwei Hu; Zongzhi Wu

Addresses: State Key Laboratory of High-efficiency Mining and Safety of Metal Mines under Ministry of Education; School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing, 100083, China ' State Key Laboratory of High-efficiency Mining and Safety of Metal Mines under Ministry of Education; School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing, 100083, China; China National Oil and Gas Exploration and Development Corporation, No. 6-1, Beidajie, Xicheng District, Beijing, China ' School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing, 100083, China; State Administration of Work Safety, No. 21, Hepinglibeijie, Dongcheng District, Beijing, China

Abstract: Abnormal gas emission, coal and gas outburst may occur on the coal seam whose gas pressure and content are below catastrophe threshold, when the mine is deeply exploited. In order to study this catastrophe mechanism, solidfluid coupling experimental system with single degree of freedom and bidirectional loading is proposed. Gas percolation and catastrophe behaviour are studied through low pressure loading in this experiment, obtaining the following conclusions: 1) gas flow curve of gas-bearing coal shows asymmetric U shape; 2) coal sample suffers catastrophe gas emission after its rupture and instability under low pressure of 0.4 MPa and 0.15 MPa; 3) stress threshold of catastrophe gas-bearing coal sample is negatively related with coal gas pressure; 4) primary fracture of gas-bearing coal sample is consolidated when elastic deformation reaches 50% ~ 60% of elastic process, blocking gas percolation. However, gas percolation channel will be reopened after one yield or several yields. [Received: March 3, 2018; Accepted: November 18, 2018]

Keywords: gas-bearing coal sample; solid-fluid coupling; gas percolation; low index; coal catastrophe.

DOI: 10.1504/IJOGCT.2020.108850

International Journal of Oil, Gas and Coal Technology, 2020 Vol.25 No.1, pp.41 - 54

Received: 03 Mar 2018
Accepted: 18 Nov 2018
Published online: 05 Aug 2020 *

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