Practice of enhanced gas extraction by staged fracturing with comb-shaped long hole in coal mine roof

Authors

JIA Bingyi, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
CHEN Dongdong, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, ChinaFollow
WU Jie, Hancheng Mining Co. Ltd., Hancheng 715400, China
SUN Siqing, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
WANG Jianli, Hancheng Mining Co. Ltd., Hancheng 715400, China
ZHAO Jizhan, Xi'an Research Institute Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
ZHANG Jie, Hancheng Mining Co. Ltd., Hancheng 715400, China

Abstract

In order to solve the problems of drilling construction difficulty, low gas drainage concentration, poor drainage effect and inability to realize the predrainage of large area, based on the existing directional drilling technology and hydraulic fracturing technology in coal mines, combined with the previous research results, the staged hydraulic fracturing technology of comb-shaped long borehole in roof was proposed, and the field test was carried out in Sangshuping No.2 well in Hancheng mining area.The test results show that the main hole length of comb-shaped hole in roof was 588 m, including 8 branch holes, the total drilling footage was 1 188 m, the distance between main hole and coal seam was 0-3.28 m, and the plane coverage was about 12.5 m. The hole was divided into 4 stages with staged hydraulic fracturing technology of immovable pipe string. The cumulative injected water volume was 2 012 m³ and the maximum pumping pressure was 8.74 MPa. After fracturing, the maximum influence radius was more than 30m, and the fractures were mainly located under the borehole and extended to the coal seam. During the stable drainage stage of fracturing borehole, the pure gas drainage volume was 1.18 m³/min, and the average drainage concentration was 43.54%. The pure gas drainage quantity of segmented hydraulic fracturing borehole with comb-shaped long borehole in the roof was 1.2 times of that of hydraulic slotting borehole and 4.0 times of that of bedding borehole in this coal seam. The test results show that the staged hydraulic fracturing technology of comb-shaped long borehole in roof can effectively avoid the problems such as collapsed hole, stuck hole, spray hole, etc in the conventional drilling process of this coal seam, and realize the pre-drainage of gas in a large area of broken soft coal seams of low permeability. It provides a new idea and new method for gas pre-drainage in the area of broken soft coal seams of low permeability.

Keywords

enhanced gas extraction, comb-shaped hole in roof, staged hydraulic fracturing, underground coal mine, Sangshuping No.2 well in Hancheng

DOI

10.3969/j.issn.1001-1986.2021.02.009

Recommended Citation

JIA Bingyi, CHEN Dongdong, WU Jie, et al. (2021) "Practice of enhanced gas extraction by staged fracturing with comb-shaped long hole in coal mine roof," Coal Geology & Exploration: Vol. 49: Iss. 2, Article 10.
DOI: 10.3969/j.issn.1001-1986.2021.02.009
Available at: https://cge.researchcommons.org/journal/vol49/iss2/10

Reference

[1] 程远平,付建华,俞启香. 中国煤矿瓦斯抽采技术的发展[J]. 采矿与安全工程学报,2009,26(2):127-139. CHENG Yuanping,FU Jianhua,YU Qixiang. Development of gas extraction technology in coal mines of China[J]. Journal of Mining & Safety Engineering,2009,26(2):127-139.

[2] 袁亮,张平松. 煤炭精准开采地质保障技术的发展现状及展望[J]. 煤炭学报,2019,44(8):2277-2284. YUAN Liang,ZHANG Pingsong. Development status and prospect of geological guarantee technology for precise coal mining[J]. Journal of China Coal Society,2019,44(8):2277-2284.

[3] 方俊,李泉新,许超,等. 松软突出煤层瓦斯抽采钻孔施工技术及发展趋势[J]. 煤炭科学技术,2018,46(5):130-137. FANG Jun,LI Quanxin,XU Chao,et al. Construction technology and development tendency of gas drainage borehole in soft and outburst seam[J]. Coal Science and Technology,2018,46(5):130-137.

[4] 王永龙,孙玉宁,王振锋,等. 松软突出煤层钻进钻孔堵塞力学特征[J]. 煤炭学报,2015,40(增刊1):119-125. WANG Yonglong,SUN Yuning,WANG Zhenfeng,et al. Mechanical characteristic of borehole clogging drilling in soft and outburst coal seam[J]. Journal of China Coal Society,2015,40(Sup.1):119-125.

[5] 王广宏. 底板定向长钻孔技术预抽煤巷条带瓦斯应用试验[J]. 能源与环保,2019,41(5):1-4. WANG Guanghong. Application test on pre-drainage strip gas in coal roadway based on floor directional long borehole technology[J]. China Energy and Environmental Protection,2019,41(5):1-4.

[6] 王宏图,江记记,王再清,等. 本煤层单一顺层瓦斯抽采钻孔的渗流场数值模拟[J]. 重庆大学学报,2011,34(4):24-29. WANG Hongtu,JIANG Jiji,WANG Zaiqing,et al. Numerical simulation of seepage field of gas extraction drilling of single bedding of mining-coal bed[J]. Journal of Chongqing University,2011,34(4):24-29.

[7] 蒋恒. 三软煤层顺层瓦斯预抽钻孔变形规律研究及其控制[J]. 能源与环保,2019,41(8):15-18. JIANG Heng. Study on deformation law and control of pre-drainage borehole of bedding gas of Three Soft and thick coal seam[J]. China Energy and Environmental Protection,2019,41(8):15-18.

[8] 张杰,姚宁平,李乔乔. 煤矿井下定向钻进技术在矿井地质勘探中的应用[J]. 煤矿安全,2013,44(10):131-134. ZHANG Jie,YAO Ningping,LI Qiaoqiao. Application of directional drilling technology in mines geological exploration[J]. Safety in Coal Mines,2013,44(10):131-134.

[9] 孙阳,赵永哲,朱昌淮,等. 定向钻进工艺技术在探查疏放灰岩水中的应用[J]. 煤田地质与勘探,2019,47(增刊1):117-121. SUN Yang,ZHAO Yongzhe,ZHU Changhuai,et al. Application of long directional borehole technology for exploration and drainage in limestone aquifer[J]. Coal Geology & Exploration,2019,47(Sup.1):117-121.

[10] 张群,葛春贵,李伟,等. 碎软低渗煤层顶板水平井分段压裂煤层气高效抽采模式[J]. 煤炭学报,2018,43(1):150-159. ZHANG Qun,GE Chungui,LI Wei,et al. A new model and application of coalbed methane high efficiency production from broken soft and low permeable coal seam by roof strata-in horizontal well and staged hydraulic fracture[J]. Journal of China Coal Society,2018,43(1):150-159.

[11] 王建利,陈冬冬,贾秉义. 韩城矿区碎软煤层顶板梳状孔水力压裂瓦斯抽采工程实践[J]. 煤田地质与勘探,2018,46(4):17-21. WANG Jianli,CHEN Dongdong,JIA Bingyi. Practice of gas drainage by hydraulic fracturing of roof pectination boreholes in broken soft coal seam in Hancheng mining area[J]. Coal Geology & Exploration,2018,46(4):17-21.

[12] 郭春生,徐超,葛勇,等.阳泉矿区松软低透煤层底板穿层钻孔抽采时间优化[J]. 西安科技大学学报,2019,39(5):875-881. GUO Chunsheng,XU Chao,GE Yong,et al. Time optimization of gas drainage from floor crossing boreholes in soft low-permeability coal seams of Yangquan mining area[J]. Journal of Xi'an University of Science and Technology,2019,39(5):875-881.

[13] 王林征,谭志宏. 底板穿层钻孔水力压裂破裂压力影响因素研究[J]. 煤矿安全,2016,47(3):1-4. WANG Linzheng,TAN Zhihong. Study on hydraulic fracturing breakdown pressure influencing factors for floor crossing borehole[J]. Safety in Coal Mines,2016,47(3):1-4.

[14] 李国栋,郑凯歌,陈冬冬. 赵固二矿本煤层定向长钻孔水力压裂增透技术研究[J]. 煤炭工程,2019,51(7):53-57. LI Guodong,ZHENG Kaige,CHEN Dongdong. Study on permeability enhancement technology through overall hydraulic fracturing of long directional hole in Zhaogu No.2 coal mine mining coal seam[J]. Coal Engineering,2019,51(7):53-57.

[15] 龙威成,赵乐凯,陈冬冬,等. 顺煤层定向长钻孔水力压裂煤层增透技术及试验研究[J]. 河南理工大学学报(自然科学版),2019,38(3):10-15. LONG Weicheng,ZHAO Lekai,CHEN Dongdong,et al. Experimental study on coal seam permeability enhancement by directional long borehole hydraulic fracturing along seam direction[J]. Journal of Henan Polytechnic University(Natural Science),2019,38(3):10-15.

[16] 张俭. 碎软低透突出煤层定向长钻孔整体水力压裂高效增透技术[J]. 中国煤炭,2018,44(7):101-105. ZHANG Jian. High effective technology through overall hydraulic fracturing of long directional borehole in crushed and soft coal seam with low permeability and outburst potential[J]. China Coal,2018,44(7):101-105.

[17] 孙四清,张群,闫志铭,等. 碎软低渗高突煤层井下长钻孔整体水力压裂增透工程实践[J]. 煤炭学报,2017,42(9):2337-2344. SUN Siqing,ZHANG Qun,YAN Zhiming,et al. Practice of permeability enhancement through overall hydraulic fracturing of long hole in outburst-prone soft crushed coal seam with low permeability[J]. Journal of China Coal Society,2017,42(9):2337-2344.

[18] 付江伟,王公忠,李鹏,等. 顶板水力致裂抽采瓦斯技术研究[J]. 中国安全科学学报,2016,26(1):109-115. FU Jiangwei,WANG Gongzhong,LI Peng,et al. Research on technique for gas frainage based on roof hydraulic fracturing[J]. China Safety Science Journal,2016,26(1):109-115.

[19] 许耀波,郭盛强. 软硬煤复合的煤层气水平井分段压裂技术及应用[J]. 煤炭学报,2019,44(4):1169-1177. XU Yaobo,GUO Shengqiang. Technology and application of staged fracturing in coalbed methane horizontal well of soft and hard coal composite coal seam[J]. Journal of China Coal Society,2019,44(4):1169-1177

[20] 刘永茜,张书林,舒龙勇. 吸附-解吸状态下煤层气运移机制[J]. 煤田地质与勘探,2019,47(4):12-18. LIU Yongqian,ZHANG Shulin,SHU Longyong. Coalbed methane migration mechanism under adsorption-desorption condition in coal[J]. Coal Geology & Exploration,2019,47(4):12-18.

[21] 黄炳香,陈树亮,程庆迎. 煤层压裂开采与治理区域瓦斯的基本问题[J]. 煤炭学报,2016,41(1):128-137. HUANG Bingxiang,CHEN Shuliang,CHENG Qingying. Basic problems of hydraulic fracturing for mining and control zone gas in coal seams[J]. Journal of China Coal Society,2016,41(1):128-137.

[22] 李浩哲,姜在炳,舒建生,等. 水力裂缝在煤岩界面处穿层扩展规律的数值模拟[J]. 煤田地质与勘探,2020,48(2):106-113. LI Haozhe,JIANG Zaibing,SHU Jiansheng,et al. Numerical simulation of layer-crossing propagation behavior of hydraulic fractures at coal-rock interface[J]. Coal Geology & Exploration,2020,48(2):106-113.

[23] 孙四清,郑凯歌. 井下高压水射流切割煤层增透效果数值模拟[J]. 煤田地质与勘探,2017,45(2):45-49. SUN Siqing,ZHENG Kaige. Numerical simulation study on permeability enhancement effect of high pressure water cutting coal seam[J]. Coal Geology & Exploration,2017,45(2):45-49.

[24] 范涛,程建远,王保利,等. 应用瞬变电磁虚拟波场成像方法检测井下煤层气水力压裂效果的试验研究[J]. 煤炭学报,2016,41(7):1762-1768. FAN Tao,CHENG Jianyuan,WANG Baoli,et al. Experimental study on imaging method of TEM pseudo wave-field to detect the effect of underground coal-bed gas hydraulic fracturing[J]. Journal of China Coal Society,2016,41(7):1762-1768.

[25] 于景邨,苏本玉,薛国强,等. 煤层顶板致灾水体井上下双磁源瞬变电磁响应及应用[J]. 煤炭学报,2019,44(8):2356-2360. YU Jingcun,SU Benyu,XUE Guoqiang,et al. Transient electromagnetic response of double magnetic source in coalseam roof disaster caused by water and its application[J]. Journal of China Coal Society,2019,44(8):2356-2360.

[26] 陈同刚,汪启年,朱将波,等. 煤层及其顶底板岩石力学性质对水力压裂裂缝延伸的控制[J]. 华东地质,2018,39(3):212-217. CHEN Tonggang,WANG Qinian,ZHU Jiangbo,et al. Controlof mechanical properties of coal seam and its roof and floor rocks over the crack extension during hydraulic fracturing[J]. East China Geology,2018,39(3):212-217.