Title: Experimental study of gas pressure and effective stress influencing on gas seepage characteristics of bituminous coal in both axial and radial directions

Authors: Lei Zhang; Dingyi Hao; Zhiwei Ye; Cun Zhang; Shuai Chen

Addresses: State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China; Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China; Key Laboratory of Coal-based CO2 Capture and Geological Storage, China University of Mining and Technology, Xuzhou 221116, China ' State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China; Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China; Key Laboratory of Coal-based CO2 Capture and Geological Storage, China University of Mining and Technology, Xuzhou 221116, China ' State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China; Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China; Key Laboratory of Coal-based CO2 Capture and Geological Storage, China University of Mining and Technology, Xuzhou 221116, China ' State Key Laboratory of Coal Resources and Safe Mining, School of Resource and Safety Engineering, China University of Mining and Technology, Beijing 100083, China ' State Key Laboratory of Coal Resources and Safe Mining, School of Mines, China; Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China; Key Laboratory of Coal-based CO2 Capture and Geological Storage, China University of Mining and Technology, Xuzhou 221116, China

Abstract: The effects of factors including effective stress, gas pressure, and Klinkenberg effect on the axial and radial gas seepage characteristics of bituminous coal, and the strain of the coal in the radial seepage process, are investigated with self-built GFDTA system. The concept of effective stress sensitivity coefficient is proposed, and the sensitivity of the permeability to the effective stress is negligible when the effective stress sensitivity coefficient is 0.01. It is concluded that the effective stress sensitivity coefficient decreases with increasing effective stress, and increases with increasing gas pressure. With the confining pressure and gas pressure increasing, the effect of unloading on the decrease degree of coal axial permeability decreases. In the axial seepage process, the sensitivity of permeability to confining stress is higher than that of axial pressure. In the radial seepage process, the influence of gas pressure on permeability is larger than that of axial pressure. [Received: September 21, 2017; Accepted: December 1, 2017]

Keywords: bituminous coal; gas pressure; effective stress; axial seepage; radial seepage.

DOI: 10.1504/IJOGCT.2019.103505

International Journal of Oil, Gas and Coal Technology, 2019 Vol.22 No.4, pp.527 - 553

Received: 21 Sep 2017
Accepted: 01 Dec 2017
Published online: 08 Nov 2019 *

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