Investigation on the Gas Drainage Effectiveness from Coal Seams by Parallel Boreholes

Chuantian Li (), Yingfeng Sun, Shiyue Wu and Xiaoyuan Sun
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Chuantian Li: School of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Yingfeng Sun: Research Institute of Macro-Safety Science, University of Science and Technology Beijing, Beijing 100083, China
Shiyue Wu: School of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Xiaoyuan Sun: College of Safety and Emergency Management Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China

Sustainability, 2023, vol. 15, issue 2, 1-11

Abstract: Gas drainage is an important technology to prevent coal and gas outburst, and the drained gas is a kind of clean energy. The gas pressure can characterize gas drainage effectiveness. In this paper, we investigated the effectiveness of gas drainage by gas pressure. Determined by the space shape of the gas flow field, the gas flow state surrounding the drainage boreholes is radial flow. According to the basic equations of radial flow, discrete equations were achieved by the implicit difference scheme, and then we obtained the gas pressure surrounding the drainage boreholes. Results showed that the midpoint between two holes presents the highest gas pressure, and gas pressure declined from the midpoint of two boreholes to both sides. The midpoint gas pressure of the two holes reflects gas drainage effectiveness in a certain degree. Gas pressure declined with segmented characteristics in the first period decline curve in the form of a cubic curve, and the second period decline curve in the form of a straight line. When the drainage pressure reaches a certain value, the decline rate of gas pressure had little relationship with the drainage negative pressure, mainly influenced by the permeability coefficient. To improve the drainage effectiveness, anti-reflection measures are feasible, instead of increasing the drainage negative pressure. Moreover, the conclusion was verified by field data.

Keywords: radial flow; implicit difference scheme; decline rate; segmented characteristics; negative pressure; permeability coefficient (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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