基于CO_(2)相变致裂技术的低渗透煤层钻孔参数优化研究  

Research on Optimization of Drilling Parameters in Low Permeability Coal Seam Based on CO_(2) Phase Change Fracturing

作　　者：李青松 付金磊 衡献伟 孙英豪 马曙 LI Qing-song;FU Jin-lei;HENG Xian-wei;SUN Ying-hao;MA Shu(Guizhou Coal Mine Design Research Institute Co.,Ltd.,Guiyang 550025,China;Guizhou Mine Safety Scientific Research Institute,Guiyang 550025,China;School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]贵州省煤矿设计研究院有限公司,贵阳550025 [2]贵州省矿山安全科学研究院,贵阳550025 [3]中国矿业大学安全学院,江苏徐州221116

出　　处：《煤炭技术》2021年第11期118-123,共6页Coal Technology

基　　金：贵州省科学技术基金资助项目(黔科合基础[2019]1189号,黔科合基础[2019]1426号),黔科合平台人才[2019]5675,黔科合支撑([2020]2Y056号,[2020]4Y049号)。

摘　　要：液态CO_(2)相变致裂钻孔参数的合理选取是避免大面积致裂空白区域及提高增透效果的关键。通过CO_(2)相变致裂p-T曲线,探究了液态CO_(2)致裂增透过程,采用有限差分数值模拟软件,建立了单孔、双孔数值模型,分析了致裂后煤体塑性区特征,确定了最优的钻孔参数。结果表明:(1)随着煤层地应力增加,液态CO_(2)致裂塑性区域范围呈先增加后减小变化趋势,随着致裂孔直径增加,孔径在φ100 mm左右时致裂效果较好;(2)采用数值模拟、理论计算2种方法确定最优致裂孔参数直径为φ94 mm、钻孔间距为3 m;(3)CO_(2)相变致裂井下试验后,致裂孔抽采孔平均瓦斯抽采纯量是普通抽采孔的4.76倍,瓦斯抽采浓度平均提高2.8倍,抽采达标时间缩短65%左右。合理选择液态CO_(2)致裂钻孔参数,能够为井下达到最优致裂增透效果及成本节约提供一定参考。The reasonable selection of CO_(2)phase change fracturing drilling parameters is the key to avoid large-scale fracturing blank areas,make full use of the CO_(2)phase change fracturing energy and improve the effect of anti-reflection.Through the CO_(2)phase change fracturing p-T curve,the mechanism of liquid CO_(2)fracturing and permeability enhancement was studied.Using finite-difference numerical simulation software,a single-hole and double-hole numerical model was established.The characteristics of the plastic zone of the coal after fracturing were analyzed,and the most Excellent drilling parameters.The results show that:(1)As the in-situ stress of the coal seam increases,the range of liquid CO_(2)fracturing plasticity shows a trend of first increasing and then decreasing.As the diameter of the fracturing hole increases,the fracturing effect is better when the diameter of the hole is about 100 mm;(2)Two methods of numerical simulation and theoretical calculation are used to determine the optimal fracture hole parameter diameter is 94 mm,and the drill hole spacing is 3 m;(3)After the CO_(2)fracturing downhole test,the fracturing hole is pumped the average gas drainage scalar volume of the mining holes is 4.76 times that of the ordinary drainage holes,the gas drainage concentration is increased by an average of 2.8 times,and the drainage time to reach the standard is reduced by about 65%.Reasonable selection of liquid CO_(2)fracturing drilling parameters provides a reference for achieving the best downhole fracturing and anti-reflection effect and saving costs.

关 键 词：CO_(2)相变致裂 增透 钻孔参数 数值模拟 瓦斯抽采 

分 类 号：TD713[矿业工程—矿井通风与安全]