Ground development technology and engineering application of CBM in coal mine goafs： A case study of Jincheng mining area in Qinshui Basin

Authors

ZHOU Xianjun, State Key Laboratory of Coal and Coalbed Methane Co-mining, Jincheng 048012, China; Yi’an Lanyan Coal and Coalbed Methane Co-mining Technology Co., Ltd., Taiyuan 030031, ChinaFollow
LI Guofu, State Key Laboratory of Coal and Coalbed Methane Co-mining, Jincheng 048012, China; Yi’an Lanyan Coal and Coalbed Methane Co-mining Technology Co., Ltd., Taiyuan 030031, ChinaFollow
LI Chao, State Key Laboratory of Coal and Coalbed Methane Co-mining, Jincheng 048012, China; Yi’an Lanyan Coal and Coalbed Methane Co-mining Technology Co., Ltd., Taiyuan 030031, China
WANG Zheng, State Key Laboratory of Coal and Coalbed Methane Co-mining, Jincheng 048012, China; Yi’an Lanyan Coal and Coalbed Methane Co-mining Technology Co., Ltd., Taiyuan 030031, China
LI Jiangbiao, Shanxi Lanyan Coalbed Methane Group Co., Ltd., Jincheng 048006, China

Abstract

There are still rich CBM resources in goafs after coal mining, and the resource evaluation, development and utilization have dual significance of environmental protection and resources. In recent years, ground drilling has been actively explored in Jincheng, Xishan and Yangquan mining areas in Shanxi Province to extract CBM in the goafs. However, in the process of ground development of CBM, due to water accumulation in the goafs, confined water gushing from overlying strata and other reasons, there is no gas production or low gas extraction from ground drilling. Taking Yuecheng Coal Mine in Jincheng, Shanxi as an example, this paper studies the occurrence characteristics of coal-bed methane in goafs under different coal mining technologies, the influence of goaf water accumulation and rock permeability in goaf fracture zones on the ground development of coal-bed methane in the goafs, and puts forward the layout principle and extraction technology of goaf wells. To solve the problem that rock powder enters the fracture zones blocking the migration channel of coal-bed methane in goafs during the three-open air drilling, the application of hydraulic punching method is explored to improve the rock permeability in goaf fracture zones. The research shows that the well layout principle of the coal mine goafs is as follows: (1) The goaf wells should be arranged outside the goaf water accumulation area; (2) For the spatial form of goafs formed by room-and-pillar mining, the goaf wells should avoid the protective coal pillar and finally complete drilling into the goaf space. In view of the spatial form of goaf formed by long arm caving method, the optimal drilling area of goaf well is the “O” circle boundary connection line and the stope boundary near the terminal line. An integrated drainage and gas extraction system for goaf wells in coal mines was developed. The drainage system realized the simultaneous drainage of accumulated water at the bottom of goaf wells and the extraction of CBM, and solved the problem of CBM production decline caused by the pressure water inflow of the overlying strata in goafs. The CBM extraction amount of goaf wells increased by 33.3% after the optimization of the drainage system. The hydraulic punching is applied to solve the problem of permeability decline in fractured zones of the goaf caused by drilling cuttings. The engineering test results show that the maximum increase rate of daily average extraction of goaf wells before and after hydraulic punching transformation is 11.30%. The suggestion of using foam under-balanced drilling technology to solve the problem of drilling rock powder invading into fractured zones of the goaf is put forward.

Keywords

coal mine goaf, coalbed methane, surface extraction, well location arrangement, well bore configuration

DOI

10.12363/issn.1001-1986.21.09.0533

Recommended Citation

ZHOU Xianjun, LI Guofu, LI Chao, et al. (2022) "Ground development technology and engineering application of CBM in coal mine goafs： A case study of Jincheng mining area in Qinshui Basin," Coal Geology & Exploration: Vol. 50: Iss. 5, Article 9.
DOI: 10.12363/issn.1001-1986.21.09.0533
Available at: https://cge.researchcommons.org/journal/vol50/iss5/9

Reference

[1] 袁亮. 我国煤炭资源高效回收及节能战略研究[M]. 北京：科学出版社，2017.

[2] 袁亮,杨科. 再论废弃矿井利用面临的科学问题与对策[J]. 煤炭学报,2021,46(1):16−24. YUAN Liang,YANG Ke. Further discussion on the scientific problems and countermeasures in the utilization of abandoned mines[J]. Journal of China Coal Society,2021,46(1):16−24.

[3] 孟召平,李国富,杨宇,等. 晋城寺河井区煤矿采空区煤层气地面抽采关键技术研究[J]. 煤炭科学技术,2021,49(1):240−247. MENG Zhaoping,LI Guofu,YANG Yu,et al. Study on key technology for surface extraction of coalbed methane in coal mine goaf from Sihe wells area,Jincheng[J]. Coal Science and Technology,2021,49(1):240−247.

[4] 刘天泉. 矿山岩体采动影响与控制工程学及其应用[J]. 煤炭学报,1995,20(1):1−5. LIU Tianquan. Influence of mining activities on mine rock mass and control engineering[J]. Journal of China Coal Society,1995,20(1):1−5.

[5] 钱鸣高,缪协兴,许家林. 岩层控制中的关键层理论研究[J]. 煤炭学报,1996,21(3):225−230. QIAN Minggao,MIAO Xiexing,XU Jialin. Theoretical study of key stratum in ground control[J]. Journal of China Coal Society,1996,21(3):225−230.

[6] 钱鸣高,许家林. 覆岩采动裂隙分布的“O”形圈特征研究[J]. 煤炭学报,1998,23(5):466−469. QIAN Minggao,XU Jialin. Study on the“O shape”circle distribution characteristics of mining induced fractures in the overlaying strata[J]. Journal of China Coal Society,1998,23(5):466−469.

[7] 许家林,钱鸣高. 地面钻井抽放上覆远距离卸压煤层气试验研究[J]. 中国矿业大学学报,2000,29(1):78−81. XU Jialin,QIAN Minggao. Study on drainage of relieved methane from overlying coal seam far away from the protective seam by surface well[J]. Journal of China University of Mining & Technology,2000,29(1):78−81.

[8] 韩丹丹,胡胜勇,张奡,等. 采空区垮落岩体空隙率分布规律及其形成机理研究[J]. 煤炭科学技术,2020,48(11):113−120. HAN Dandan,HU Shengyong,ZHANG Ao,et al. Study on voidage distribution regulation and formation mechanism of crushed rock mass in gob[J]. Coal Science and Technology,2020,48(11):113−120.

[9] 屠世浩,张村,杨冠宇,等. 采空区渗透率演化规律及卸压开采效果研究[J]. 采矿与安全工程学报,2016,33(4):571−577. TU Shihao,ZHANG Cun,YANG Guanyu,et al. Research on permeability evolution law of goaf and pressure–relief mining effect[J]. Journal of Mining & Safety Engineering,2016,33(4):571−577.

[10] 郇恒飞,高铁,赵海卿,等. 高精度重力测量在抚顺煤矿采空区探测中的应用[J]. 煤田地质与勘探,2019,47(6):194−200. HUAN Hengfei,GAO Tie,ZHAO Haiqing,et al. Application of high precision gravity survey in detecting mined−out areas of Fushun coal mine[J]. Coal Geology & Exploration,2019,47(6):194−200.

[11] 林井祥,张立明,张继忠. 基于瞬变电磁法和大地电磁法的煤矿积水采空区探测[J]. 煤炭工程,2021,53(6):152−156. LIN Jingxiang,ZHANG Liming,ZHANG Jizhong. Detection of goaf hydrops in coal mine based on transient electromagnetic method and magnetotelluric method[J]. Coal Engineering,2021,53(6):152−156.

[12] 孟召平,师修昌,刘珊珊,等. 废弃煤矿采空区煤层气资源评价模型及应用[J]. 煤炭学报,2016,41(3):537−544. MENG Zhaoping,SHI Xiuchang,LIU Shanshan,et al. Evaluation model of CBM resources in abandoned coal mine and its application[J]. Journal of China Coal Society,2016,41(3):537−544.

[13] 袁亮,郭华,李平,等. 大直径地面钻井采空区采动区瓦斯抽采理论与技术[J]. 煤炭学报,2013,38(1):1−8. YUAN Liang,GUO Hua,LI Ping,et al. Theory and technology of goaf gas drainage with large−diameter surface boreholes[J]. Journal of China Coal Society,2013,38(1):1−8.

[14] 秦伟,许家林,彭小亚,等. 老采空区瓦斯抽采地面钻井的井网布置方法[J]. 采矿与安全工程学报,2013,30(2):289−295. QIN Wei,XU Jialin,PENG Xiaoya,et al. Optimal layout of surface borehole network for gas drainage from abandoned gob[J]. Journal of Mining & Safety Engineering,2013,30(2):289−295.

[15] GAO Qiang,FENG Guorui,HU Shengyong,et al. Optimization of the surface vertical well of abandoned mine goafs based on gas seepage characteristics[J]. Journal of Engineering Science and Technology Review,2018,11(2):54−62.

[16] 李军军,李国富,郝海金,等. 过采空区抽采下组煤煤层气技术及工程应用初探:以晋城寺河井田为例[J]. 煤田地质与勘探,2021,49(4):96−104. LI Junjun,LI Guofu,HAO Haijin,et al. Technology of across–goaf drainage of coalbed methane from a lower coal seam group and its primary application:Taking Sihe mine field as an example[J]. Coal Geology & Exploration,2021,49(4):96−104.

[17] 李日富. 地面钻井抽采负压对采空区气体流场分布影响[J]. 煤炭科学技术,2012,40(7):38−40. LI Rifu. Negative pressure of gas drainage well at surface affected to distribution of gas flow filed in goaf[J]. Coal Science and Technology,2012,40(7):38−40.

[18] KOZENY J. Uber Kapillare Leitung des Wasser in Boden[J]. Akad Wiss Wien,1927,136:271−306.

[19] CARMAN P C. Fluid flow through granular beds[J]. Chemical Engineering Research and Design,1997,75(Sup.1):S32−S48.

[20] CARMAN P C. Flow of gases through porous media[M]. London：Butterworths，1956.

[21] 李国富,付军辉,李超,等. 山西重点煤矿采动区煤层气地面抽采技术及应用[J]. 煤炭科学技术,2019,47(12):83−89. LI Guofu,FU Junhui,LI Chao,et al. Surface drainage technology and application of CBM in key mining areas of Shanxi Province[J]. Coal Science and Technology,2019,47(12):83−89.

[22] 张书林,刘永茜,孟涛. 不同矿化度水对煤的甲烷解吸影响的试验研究[J]. 煤炭科学技术,2021,49(7):110−117. ZHANG Shulin,LIU Yongqian,MENG Tao. Experimental study on influence of water with different salinity on methane desorption performance of coal seam[J]. Coal Science and Technology,2021,49(7):110−117.

[23] 王争,李国富,周显俊,等. 山西省废弃矿井煤层气地面钻井开发关键问题与对策[J]. 煤田地质与勘探,2021,49(4):86−95. WANG Zheng,LI Guofu,ZHOU Xianjun,et al. Key problems and countermeasures of CBM development through surface boreholes in abandoned coal mines of Shanxi Province[J]. Coal Geology & Exploration,2021,49(4):86−95.