Deformation and collapse patterns of gas drainage boreholes and a precise monitoring technology

Authors

XIAO Peng, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, ChinaFollow
HUANG Xiaosheng, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, ChinaFollow
LIU Xiaoxiao, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
LI Bingkun, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
CHEN Liping, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
CHEN Zixi, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
ZHANG Chao, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
CHENG Renhui, School of Safety Science and Engineering, Xi’an University of Science and Technology, Xi’an 710054, China
ZHAO Yajie, Institute for Hygiene of Ordnance Industry, Xi’an 710065, China

Abstract

This study aims to promote the precise and intelligent monitoring of gas drainage boreholes. In the engineering background of a coal mine in Shanxi Province, this study conducted simulation experiments on the plugging of gas extraction boreholes under varying particle size ratios of simulated coal samples using distributed optical fiber monitoring and the Brillouin Optical Time-Domain Analysis (BOTDA). Then, this study established a mathematical model for calculating the borehole plugging rate of the test mine, revealing the deformation and collapse patterns of gas drainage boreholes. Furthermore, this study proposed a precise in-situ monitoring technology for the gas drainage boreholes in the test mine and verified its feasibility and accuracy through field tests. Key findings are as follows: (1) There existed a linear correlation between the strain measured by fiber couplers, the mass of simulated coal samples, and the deformation and collapse of the boreholes. With an increase in the coal sample mass, the strain exhibited similar variation trends, increasing sharply, generally, and sharply in sequence. A mathematical model for calculating the borehole plugging rate was established through segmented fitting. (2) The error analysis revealed that with an increase in the strain, the maximum absolute error between the actual and theoretical borehole plugging rates manifested a trend of initial increase, followed by decrease and then increase, equaling 19.48% in the middle collapse stage. Under complete borehole plugging in the late collapse stage, the local maximum of the coal sample mass closer to the average local maximum of the mass of coal samples with different particle size ratios corresponded to a smaller error. (3) Based on calculations using the mathematical model, this study revealed the boreholes’ collapse pattern during the borehole plugging simulation. Specifically, coal blocks first accumulated in a convex shape at the bottom of a borehole, then slid toward both sides, and finally accumulated at the borehole’s top. With strain values of 0, 45.95×10⁻⁶, and 72.19×10⁻⁶ as critical values, this study determined the early, middle, and late stages of borehole collapse, developing the precise monitoring technology for the gas drainage boreholes in the test mine. As indicated by the analysis of in-situ strain monitoring results, fractures are prone to form around the boreholes in their unstable segments under the action of factors such as stress and disturbance, with borehole collapse intensifying over time. By combining the calculated plugging rates along the boreholes, this study determined the deformation and collapse along the boreholes. Comparison with the boreholes’ inside images reveals that the results obtained using the precise monitoring technology are roughly consistent with actual observations. Therefore, the precise borehole monitoring technology based on the distributed fiber optic coupler and the BOTDA is feasible and reliable, serving as a reference for advancing the precise and intelligent monitoring of gas drainage boreholes.

Keywords

distributed optical fiber monitoring, borehole collapse, mathematical model, precise borehole monitoring, gas drainage

DOI

10.12363/issn.1001-1986.23.09.0585

Recommended Citation

XIAO Peng, HUANG Xiaosheng, LIU Xiaoxiao, et al. (2024) "Deformation and collapse patterns of gas drainage boreholes and a precise monitoring technology," Coal Geology & Exploration: Vol. 52: Iss. 3, Article 3.
DOI: 10.12363/issn.1001-1986.23.09.0585
Available at: https://cge.researchcommons.org/journal/vol52/iss3/3

Reference

[1] 王双明，耿济世，李鹏飞，等. 煤炭绿色开发地质保障体系的构建[J]. 煤田地质与勘探，2023，51(1)：33−43.

WANG Shuangming，GENG Jishi，LI Pengfei，et al. Construction of geological guarantee system for green coal mining[J]. Coal Geology & Exploration，2023，51(1)：33−43.

[2] 徐超平，李贺，鲁义，等. 软煤瓦斯抽采钻孔失稳特性及控制技术研究现状[J]. 矿业安全与环保，2022，49(3)：131−135.

XU Chaoping，LI He，LU Yi，et al. Research status of borehole instability characteristics and control technology for gas extraction in soft coal seam[J]. Mining Safety & Environmental Protection，2022，49(3)：131−135.

[3] HE Shengquan，OU Shengnan，HUANG Fengxiang，et al. Borehole protection technology of screen pipes for gas drainage boreholes in soft coal seams[J]. Energies，2022，15(15)：5657.

[4] 王力，姚宁平，姚亚峰，等. 煤矿井下碎软煤层顺层钻完孔技术研究进展[J]. 煤田地质与勘探，2021，49(1)：285−296.

WANG Li，YAO Ningping，YAO Yafeng，et al. Research progress of drilling and borehole completion technologies in broken soft coal seam in underground coal mine[J]. Coal Geology & Exploration，2021，49(1)：285−296.

[5] FELLGETT M W，KINGDON A，WATERS C N，et al. Lithological constraints on borehole wall failure：A study on the Pennine coal measures of the United Kingdom[J]. Frontiers in Earth Science，2019，7：163.

[6] ZHANG Yuezheng，JI Hongguang，LI Wenguang，et al. Research on rapid evaluation of rock mass quality based on ultrasonic borehole imaging technology and fractal method[J]. Advances in Materials Science and Engineering，2021，2021：8063665.

[7] ZONG Chang，LIU Juntao，LIU Zhiyi，et al. A fast forward algorithm of azimuthal gamma imaging logging while drilling[J]. Applied Radiation and Isotopes，2023，194：110659.

[8] 朱丽媛，李忠华，徐连满. 钻屑扭矩法测定煤体应力与煤体强度研究[J]. 岩土工程学报，2014，36(11)：2096−2102.

ZHU Liyuan，LI Zhonghua，XU Lianman. Measuring stress and strength of coal by drilling cutting torque method[J]. Chinese Journal of Geotechnical Engineering，2014，36(11)：2096−2102.

[9] LI Wei，REN Tianwei，BUSCH A，et al. Architecture，stress state and permeability of a fault zone in Jiulishan coal mine，China：Implication for coal and gas outbursts[J]. International Journal of Coal Geology，2018，198：1−13.

[10] WANG Jinchao，WANG Chuanying，HUANG Junfeng，et al. In situ stress measurement method of deep borehole based on multi–array ultrasonic scanning technology[J]. Frontiers in Earth Science，2022，10：933286.

[11] HUANG Dan，LIU Zaibin，WANG Wenke，et al. The identification of fault zones in deep karst aquifer of North China coal mine using parallel directional well logs[J]. Environmental Earth Sciences，2018，77(22)：761.

[12] LIU Du，WANG Yanbin，NI Xiaoming，et al. Classification of coal structure combinations and their influence on hydraulic fracturing：A case study from the Qinshui Basin，China[J]. Energies，2020，13(17)：4559.

[13] ZHENG Yahua，ZHAO Zhigang，ZHAO Tongbin，et al. A new method for monitoring coal stress while drilling process：Theoretical and experimental study[J]. Energy Sources，Part A：Recovery，Utilization，and Environmental Effects，2023，45(2)：3980–3993.

[14] 岳立新，杨全春，郝志勇. 基于钻杆转速和钻屑量测定煤体应力实验研究[J]. 机械设计与研究，2018，34(4)：127−132.

YUE Lixin，YANG Quanchun，HAO Zhiyong. Experimental study on measuring the stress of coal based on the speed of drilling rod and the amount of drilling chip[J]. Machine Design & Research，2018，34(4)：127−132.

[15] QI Qingjie，JIA Xinlei，ZHOU Xinhua，et al. Instability–negative pressure loss model of gas drainage borehole and prevention technique：A case study[J]. PLOS ONE，2020，15(11)：e0242719.

[16] 张鹏飞，赵同彬，马兴印，等. 矸石充填开采顶板裂隙分布及演化特征分析[J]. 岩石力学与工程学报，2022，41(5)：969−978.

ZHANG Pengfei，ZHAO Tongbin，MA Xingyin，et al. Analysis on crack distribution and evolution characteristics of gangue backfilled working face roof[J]. Chinese Journal of Rock Mechanics and Engineering，2022，41(5)：969−978.

[17] ZHANG Xuebo，SHEN Shuaishuai，FENG Xiaojun，et al. Influence of deformation and instability of borehole on gas extraction in deep mining soft coal seam[J]. Advances in Civil Engineering，2021，2021：6689277.

[18] PRENSKY S E. Advances in borehole imaging technology and applications[J]. Geological Society，London，Special Publications，1999，159：1−43.

[19] BOYER R，JACOBS A M. Borehole television for geotechnical investigations[J]. International Water Power & Dam Construction，1986，38(9)：16−18.

[20] AL–SIT W，AL–NUAIMY W，MARELLI M，et al. Visual texture for automated characterisation of geological features in borehole televiewer imagery[J]. Journal of Applied Geophysics，2015，119：139−146.

[21] 刘小雄，王海军. 薄煤层智能开采工作面煤层透明化地质勘查技术[J]. 煤炭科学技术，2022，50(7)：67−74.

LIU Xiaoxiong，WANG Haijun. Transparent geological exploration technology of coal seam on the working surface of intelligent mining of thin coal seam[J]. Coal Science and Technology，2022，50(7)：67−74.

[22] 张玉军，张风达，张志巍，等. 采动煤层底板层次性破坏特征全空间多参量协同监测[J]. 煤炭科学技术，2022，50(2)：86−94.

ZHANG Yujun，ZHANG Fengda，ZHANG Zhiwei，et al. Full–space multi–parameter cooperative monitoring of failure hierarchy characteristics of mining coal seam floor[J]. Coal Science and Technology，2022，50(2)：86−94.

[23] 杨宏民，任发科，王兆丰，等. 瓦斯抽采钻孔封孔质量检测及定量评价方法[J]. 煤炭学报，2019，44(增刊1)：164−170.

YANG Hongmin，REN Fake，WANG Zhaofeng，et al. Quality inspection and quantitative evaluation method for borehole sealing in gas drainage[J]. Journal of China Coal Society，2019，44(Sup.1)：164−170.

[24] 张学博，王豪，杨明，等. 抽采钻孔失稳坍塌对瓦斯抽采的影响机制研究及应用[J]. 煤炭学报，2023，48(8)：3102−3115.

ZHANG Xuebo，WANG Hao，YANG Ming，et al. Study and application on influence mechanism of instability and collapse of drainage borehole on gas drainage[J]. Journal of China Coal Society，2023，48(8)：3102−3115.

[25] 柴敬，周余，欧阳一博，等. 基于光纤监测的注浆浆液扩散范围试验研究[J]. 中国矿业大学学报，2022，51(6)：1045−1055.

CHAI Jing，ZHOU Yu，OUYANG Yibo，et al. Experimental study of diffusion range of grouting slurry based on optical fiber monitoring[J]. Journal of China University of Mining & Technology，2022，51(6)：1045−1055.

[26] HU Yanbo，LI Wenping，CHEN Xinmin，et al. Application of brillouin optical time domain reflection technology for monitoring deformation and failure of the coal seam floor rock mass in deep underground mines[J]. Mine Water and the Environment，2022，41(4)：1082−1095.

[27] HU Tao，BU Su，HU Ziyi，et al. Experimental study on the displacement sensor of coal roadways roof settlement based on distributed fiber optic sensing[J]. IEEE Sensors Journal，2021，21(12)：13870−13876.

[28] 傅芸. 光纤分布式应变传感新方法与新技术的研究[D]. 成都：电子科技大学，2020.

FU Yun. Researches on novel methods and technologies of distributed fiber strain sensors[D]. Chengdu：University of Electronic Science and Technology of China，2020.

[29] XIAO Peng，HUANG Xiaosheng，ZHANG Chao，et al. Research on the construction and verification of evaluation model for borehole collapse in gas extraction[J]. Fuel，2024，362：130800.

[30] 张孟喜，褚静尘，陈强，等. 基于FBG传感技术循环荷载下的路堤模型试验[J]. 上海大学学报(自然科学版)，2022，28(4)：645−655.

ZHANG Mengxi，CHU Jingchen，CHEN Qiang，et al. Model test on embankment reinforcement under cyclic loads using FBG sensing technology[J]. Journal of Shanghai University (Natural Science Edition)，2022，28(4)：645−655.

[31] 孙义杰，张强，程刚，等. 基于光频域反射技术的表面粘贴分布式光纤传感器应变传递特性分析与试验[J]. 科学技术与工程，2018，18(33)：46−52.

SUN Yijie，ZHANG Qiang，CHENG Gang，et al. Optical frequency domain reflectometry technology based theoretical analysis and experiment on strain transferring of surface–attached optical fiber sensor[J]. Science Technology and Engineering，2018，18(33)：46−52.

[32] 孟上九，张书荣，程有坤，等. 光纤布拉格光栅在季节冻土路基应变检测中的应用[J]. 岩土力学，2016，37(2)：601−608.

MENG Shangjiu，ZHANG Shurong，CHENG Youkun，et al. Application of fiber Bragg grating sensors to strain detection of seasonally frozen subgrade[J]. Rock and Soil Mechanics，2016，37(2)：601−608.

[33] 李景涛. 深部构造煤钻孔塌孔机制及防塌技术研究[D]. 焦作：河南理工大学，2022.

LI Jingtao. Research on collapse mechanism and anti–collapse technology of borehole in deep tectonic coal[D]. Jiaozuo：Henan Polytechnic University，2022.

[34] 孙浩翔. 唐山矿5煤层卸压钻孔破坏演化规律研究[D]. 阜新：辽宁工程技术大学，2022.

SUN Haoxiang. Destress drilling failed evolution law of No.5 coal seam in Tangshan Mine[D]. Fuxin：Liaoning Technical University，2022.

[35] 国家市场监督管理总局，国家标准化管理委员会. 煤炭产品品种和等级划分：GB/T 17608—2022[S]. 北京：中国标准出版社，2022.

[36] 邓军，王津睿，任帅京，等. 声波探测技术在矿井领域中的应用及展望[J]. 煤田地质与勘探，2023，51(6)：149−162.

DENG Jun，WANG Jinrui，REN Shuaijing，et al. Application and prospect of acoustic detection in the mining sector[J]. Coal Geology & Exploration，2023，51(6)：149−162.

[37] 张锦旺，王家臣，魏炜杰，等. 块度级配对散体顶煤流动特性影响的试验研究[J]. 煤炭学报，2019，44(4)：985−994.

ZHANG Jinwang，WANG Jiachen，WEI Weijie，et al. Experimental investigation on the effect of size distribution on the flow characteristics of loose top coal[J]. Journal of China Coal Society，2019，44(4)：985−994.

[38] 施卫星，何斌，李晓玮，等. 一种新型调谐质量阻尼器的试验研究[J]. 振动与冲击，2015，34(12)：207−211.

SHI Weixing，HE Bin，LI Xiaowei，et al. Experimental study on a new type of tuned mass damper[J]. Journal of Vibration and Shock，2015，34(12)：207−211.

[39] LYU Wenyu，GUO Kai，WU Yongping，et al. Compression characteristics of local filling gangue in steeply dipping coal seam[J]. Energy Exploration & Exploitation，2022，40(4)：1131−1150.

[40] 马德，赵育云，郭德龙，等. 孔周煤岩体渐进性破坏过程裂隙和应变能演化特征[J]. 煤矿安全，2022，53(3)：16−23.

MA De，ZHAO Yuyun，GUO Delong，et al. Evolution characteristics of cracks and strain energy during progressive failure of coal and rock masses around the hole[J]. Safety in Coal Mines，2022，53(3)：16−23.

[41] SUN Xiaoyan，RAN Qican，LIU Hao，et al. Characteristics of stress–displacement–fracture multi–field evolution around gas extraction borehole[J]. Energies，2023，16(6)：2896.