Numerical Investigation on Potential Influencing Factors Affecting Drainage Effective Radius of Crossing Borehole

Wu Xiao, Ke Li (), Chuanjie Zhu (), Ziwen Li, Baiquan Lin, Cong Ma and Mingkai Si
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Wu Xiao: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Ke Li: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Chuanjie Zhu: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Ziwen Li: College of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Baiquan Lin: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Cong Ma: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Mingkai Si: Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China

Sustainability, 2023, vol. 15, issue 3, 1-14

Abstract: Crossing borehole is an effective means to eliminate the outburst risk of coal and gas. The influence of borehole inclination angle, borehole diameter, and drainage time on the effective radius of gas drainage are studied by numerical simulation and engineering example verification. The study shows that the effective radius changes in a “U” shape with the increase in borehole inclination angle. When the angle α of the borehole and coal seam plane decreases, the effective radius increases. Furthermore, the coal mass around the borehole is broken by shear deformation, which is consistent with the results of the inner peephole. The effective radiuses are different in coal seam dip X and strike Y. When α is small, the effective radius in the X direction is generally wider. When α is large ( α ≤ 90°), the effective radiuses in the X and Y directions are close. The effective radius is positively correlated with the borehole diameter and is more significantly influenced by increasing borehole diameter when α is small. The effective radius increases as a negative exponential function with time and eventually converges to a constant. The study has practical implications for the design of crossing borehole in the coal seam floor.

Keywords: crossing borehole; borehole inclination angle; borehole diameter; drainage effective radius; residual gas pressure (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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