Method for designing the optimal sealing depth in methane drainage boreholes to realize efficient drainage

International Journal of Coal Science & Technology

Minghao Yi¹  Zhenyang Wang¹  Qingquan Liu¹  Liang Wang¹  Congmeng Hao¹ 

[1] Key Laboratory of Coal Methane and Fire Control, Ministry of Education, China University of Mining and Technology, 221116, Xuzhou, Jiangsu, China;National Engineering Research Center for Coal Gas Control, China University of Mining and Technology, 221116, Xuzhou, Jiangsu, China;School of Safety Engineering, China University of Mining and Technology, 221116, Xuzhou, Jiangsu, China;

关键词: Coal mine methane;    Methane drainage;    Borehole sealing;    Mining safety;    Methane utilization;   

DOI  :  10.1007/s40789-021-00448-y

来源: Springer

【 摘 要 】

The purpose of underground methane drainage technology is to prevent methane disasters and enable the efficient use of coal mine methane (CMM), and the sealing depth is a key factor that affects the performance of underground methane drainage. In this work, the layouts of in-seam and crossing boreholes are considered to analyze the stress distribution and failure characteristics of roadway surrounding rock through a numerical simulation and field stress investigation to determine a reasonable sealing depth. The results show that the depths of the plastic and elastic zones in two experimental coal mines are 16 and 20 m respectively. Borehole sealing minimizes the air leakage through the fractures around the roadway when the sealing material covers the failure and plastic zones, and the field test results for CMM drainage at different sealing depths indicate that the CMM drainage efficiency increases with increasing sealing depth but does not change once the sealing depth exceeds the plastic zone. Moreover, sealing in the high-permeability roadway surrounding rock does not have a strong influence on the borehole sealing performance. Considering these findings, a new CMM drainage system for key sealing in the low-permeability zone was developed that is effective for improving the CMM drainage efficiency and prolonging the high-concentration CMM drainage period. The proposed approach offers a valuable quantitative analysis method for selecting the optimum sealing parameters for underground methane drainage, thereby improving considerably the drainage and utilization rates of CMM.

【 授权许可】

CC BY