顺层钻孔预抽煤层瓦斯精准布孔模式及工程实践  

Precise borehole placement model and engineering practice for pre-draining coal seam gas by drilling along seam

作　　者：林海飞 季鹏飞[1] 孔祥国 李树刚 窦桂东[4] 李可 LIN Haifei;JI Pengfei;KONG Xiangguo;LI Shugang;DOU Guidong;LI Ke(College of Safety Science and Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;Key Laboratory of Western Mine Exploitation and Hazard Prevention Ministry of Education,Xi’an University of Science and Technology,Xi’an 710054,China;Western Engineering Research Center of Mine Gas Intelligent Drainage for Coal Industry,Xi’an 710054,China;Shaanxi Binchang Xiaozhuang Mining Co.,Ltd.,Xianyang 713500,China)

机构地区：[1]西安科技大学安全科学与工程学院,陕西西安710054 [2]西部矿井开采及灾害防治教育部重点实验室,陕西西安710054 [3]煤炭行业西部矿井瓦斯智能抽采工程研究中心,陕西西安710054 [4]陕西彬长小庄矿业有限公司,陕西咸阳710054

出　　处：《煤炭学报》2022年第3期1220-1234,共15页Journal of China Coal Society

基　　金：国家自然科学基金重点资助项目(51734007);陕西省杰出青年科学基金资助项目(2020JC-48);国家自然科学基金青年基金资助项目(51904236)。

摘　　要：顺层钻孔预抽瓦斯技术是降低煤层瓦斯含量的有效方法之一,合理的布孔参数是提高煤层瓦斯预抽效果的关键。为提高顺层钻孔布孔精准性和科学性,建立了含瓦斯煤体流固耦合抽采模型,基于响应面法设计布孔参数优化方案,运用COMSOL Multiphysics模拟软件分析了地质因素(煤层瓦斯含量、透气性系数)和工程因素(抽采负压、钻孔直径、布孔间距)交互作用对钻孔预抽煤层瓦斯的影响规律,提出钻孔间最大瓦斯压力与达标压力比(P_(max)/P_(b))的布孔参数判定指标,创新了煤层“分时分区”式顺层钻孔预抽煤层瓦斯精准布孔方法,得到适用于不同煤层瓦斯赋存特征的最优钻孔布置参数,并进行现场试验。结果表明:预抽初期,相邻钻孔间抽采叠加效应不明显;随着预抽时间延长,抽采叠加效应越发显著,垂直钻孔方向的抽采达标区域逐渐由孤立向复合转变。不同预抽时间下,P_(max)/P_(b)对各因素的敏感性依次为:布孔间距>煤层瓦斯含量>透气性系数>钻孔直径>抽采负压。不同预抽时间下,煤层瓦斯含量和透气性系数的交互作用响应等值线分布密集,2者对P_(max)/P_(b)影响非常显著,并且对P_(max)/P_(b)数值影响较大;工程因素中抽采负压与钻孔直径的交互作用响应等值线呈圆形分布,说明二者交互作用不明显;在布孔间距与地质因素交互作用下,响应等值线沿布孔间距方向更为密集,布孔间距对P_(max)/P_(b)影响仍然是显著的,与单因素分析结果相互佐证。试验工作面采用“分时分区”式顺层钻孔精准布孔方法确定的合理布孔参数依次为:抽采负压24.0 kPa、钻孔直径113 mm、布孔间距6.0 m;经优化预抽钻孔参数后,现场瓦斯预抽效果良好且预抽达标检验合格,实现了煤层瓦斯精准预抽。One of the most effective methods to reduce the gas content of coal seam is to pre-drain gas by drilling along the seam.Rational borehole layout parameters are the key to improve the effectiveness of coal seam gas pre-drainage.In order to improve the accuracy and scientificity of borehole layout in seam drilling,a fluid-solid coupling model of gas-containing coal was established.Based on the response surface method,an optimization scheme of borehole arrangement parameters was designed.The COMSOL Multi-physics simulation software was used to analyze the influence of the interaction between geological factors(coal seam gas content,gas permeability coefficient)and engineering factors(drainage negative pressure,borehole diameter,borehole spacing)on the pre-drainage of coal seam gas by drilling.The determination index of the ratio of the maximum gas pressure between boreholes to the standard pressure(P_(max)/P_(b))was proposed.The precise distribution method for pre-draining coal seam gas by“time-sharing partition”type of boreholes was developed.The optimal borehole layout parameters suitable for different coal seam gas occurrence characteristics were obtained.Finally,the field test of gas pre-drainage was carried out.The results show that the superimposition effect of drainage between adjacent boreholes was not obvious at the initial stage of pre-drainage.As the pre-drainage time was extended,the superimposing effect of draining became more and more significant,and the drainage standard area in the vertical borehole direction gradually changed from isolated to composite.Under different pre-draining times,the sensitivity of P_(max)/P_(b) to various factors was as follows:borehole spacing>coal seam gas content>gas permeability coefficient>borehole diameter>drainage negative pressure.The interaction response contours of coal seam gas content and permeability coefficient were densely distributed,which indicated that both have a very significant effect on P_(max)/P_(b) and greater impact on the value of P_(max)/P_(b).

关 键 词：瓦斯精准抽采 顺层钻孔 交互作用 布孔优化 分时分区 

分 类 号：TD712[矿业工程—矿井通风与安全]