高突低渗透煤层超高压水力割缝卸压增透研究
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摘要
为了解决五轮山煤矿8号高突低渗透煤层1809工作面瓦斯治理难题,提出了超高水力割缝煤层卸压增透技术,以有效改造强化瓦斯抽采。采用理论分析、FLAC~(3D)数值模拟方法研究了不同缝槽间距条件下缝槽周围煤体塑性破坏特征和应力演化规律,然后基于含瓦斯煤体渗透率与三向应力和瓦斯压力之间的关系,分析了不同缝槽间距时周围煤体的渗透率分布规律。研究结果表明:缝槽自由面能够卸除围压,集中应力向缝槽外侧和缝槽间煤体转移;煤体渗透率明显提高,促进瓦斯解吸和流动。经现场实践验证,超高压水力割缝增大了煤层暴露面积、煤体扰动体积,高负压抽采支管瓦斯流量和浓度明显提升,瓦斯抽采纯量在0.7～1.1 m~3/min内波动,瓦斯体积分数在50%以上,对本矿其他工作面瓦斯治理具有一定借鉴意义。
Aiming at solving the problem of gas control in high outburst and low permeability coal seam of No. 8 coal seam in Wulunshan Coal Mine No. 1809 coal mining face,this paper proposes a gas extraction technology using ultra-high hydraulic slotting in coal seams. The plastic failure characteristics and stress evolution of coal around the hydraulic slots under different slot spacings are analyzed theoretically and numerically.The numerical simulation is conducted using FLAC~(3D). Then,based on the relationship between gas permeability and triaxial stress and gas pressure,the permeability distributions of coal around the hydraulic slots are analyzed. It is found that the free surface of hydraulic slots can reduce the confining pressure around the slots,which results from the concentrated stress transferring to the area outside of the slots and the coal between the slots. Coal permeability is significantly increased,followed by the increase of gas desorption and gas flow. The field practice shows that the ultra-high pressure hydraulic cutting increases coal exposed area and coal disturbance volume.The gas flow rate and gas concentration of high negative pressure extraction pipes are then significantly increased. The field measurement data shows that the pure quantity of drainage is between 0.7 and 1.1 m~3/min and the gas concentration is above 50%. This paper provides reference for gas control in other working faces of the mine.
Aiming at solving the problem of gas control in high outburst and low permeability coal seam of No. 8 coal seam in Wulunshan Coal Mine No. 1809 coal mining face,this paper proposes a gas extraction technology using ultra-high hydraulic slotting in coal seams. The plastic failure characteristics and stress evolution of coal around the hydraulic slots under different slot spacings are analyzed theoretically and numerically.The numerical simulation is conducted using FLAC~(3D). Then,based on the relationship between gas permeability and triaxial stress and gas pressure,the permeability distributions of coal around the hydraulic slots are analyzed. It is found that the free surface of hydraulic slots can reduce the confining pressure around the slots,which results from the concentrated stress transferring to the area outside of the slots and the coal between the slots. Coal permeability is significantly increased,followed by the increase of gas desorption and gas flow. The field practice shows that the ultra-high pressure hydraulic cutting increases coal exposed area and coal disturbance volume.The gas flow rate and gas concentration of high negative pressure extraction pipes are then significantly increased. The field measurement data shows that the pure quantity of drainage is between 0.7 and 1.1 m~3/min and the gas concentration is above 50%. This paper provides reference for gas control in other working faces of the mine.
引文
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[8]罗朝义,江泽标,郑昌盛,等.CO2相变致裂技术在顺煤层钻孔增透中的应用[J].煤炭科学技术,2017,45(11):138-143.LUO Zhaoyi,JIANG Zebiao,ZHENG Changsheng,et al.Application on permeability improvement technology with CO2phase change to borehole drilling along coal seam[J].Coal Science and Technology,2017,45(11):138-143.
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[10]娄亚北,冯利民,刘健,等.穿层深孔爆破在突出坚硬煤层瓦斯抽采中的应用[J].煤炭科学技术,2015,43(12):66-71.LOU Yabei,FENG Limin,LIU Jian,et al.Through strata deep borehole blasting applied to gas drainage in hard outburst seam[J].Coal Science and Technology,2015,43(12):66-71.
[11]林柏泉,邹全乐,沈春明,等.双动力协同钻进高效卸压特性研究及应用[J].煤炭学报,2013,38(6):911-917.LIN Baiquan,ZOU Quanle,SHEN Chunming,et al.Investigation on highly effective depressurization property of dual-power drilling and its application[J].Journal of China Coal Society,2013,38(6):911-917.
[12]刘厅,林柏泉,邹全乐,等.杨柳煤矿割缝预抽后煤体孔隙结构变化特征[J].天然气地球科学,2015,26(10):1999-2008.LIU Ting,LIN Baiquan,ZOU Quanle,et al.Pore characterristics of coal with the treatment of hydraulic slotting and gas pre-drainage in Yangliu coal mine[J].Natural Gas Geoscience,2015,26(10):1999-2008.
[13]薛王龙.掘进工作面水力割缝抽采瓦斯的数值模拟研究[D].太原:太原理工大学,2016.
[14]闫发志,朱传杰,郭畅,等.割缝与压裂协同增透技术参数数值模拟与试验[J].煤炭学报,2015,40(4):823-829.YAN Fazhi,ZHU Chuanjie,GUO Chang,et al.Numerical simulation parameters and test of cutting and fracturing collaboration permeability-increasing technology[J].Journal of China Coal Society,2015,40(4):823-829.
[15]林柏泉,刘厅,邹全乐,等.割缝扰动区裂纹扩展模式及能量演化规律[J].煤炭学报,2015,40(4):719-727.LIN Baiquan,LIU Ting,ZOU Quanle,et al.Crack propagation modes and energy evolution within slotting disturbed zone[J].Journal of China Coal Society,2015,40(4):719-727.
[16]顾北方.高压水射流割缝煤体损伤演化规律研究与应用[D].北京:中国矿业大学(北京),2016.
[17]刘志伟,张帅.高瓦斯突出煤层底抽巷合理布置研究[J].煤炭科学技术,2018,46(10):155-160.LIU Zhiwei,ZHANG Shuai.Study on rational layout of floor gas drainage gateway in high gassy-outburst seam[J].Coal Science and Technology,2018,46(10):155-160.
[18]赵阳升.多孔介质多场耦合作用及其工程响应[M].北京:科学出版社,2010.
[2]蓝航,陈东科,毛德兵.我国煤矿深部开采现状及灾害防治分析[J].煤炭科学技术,2016,44(1):39-46.LAN Hang,CHEN Dongke,MAO Debing.Current status of deep mining and disaster prevention in China[J].Coal Science and Technology,2016,44(1):39-46.
[3]孙四清,张群,闫志铭,等.碎软低渗高突煤层井下长钻孔整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.
[4]张春华,张勇志,李江涛,等.深部煤层单段/多段水力压裂增透效果对比[J].煤炭科学技术,2017,45(6):50-54.ZHANG Chunhua,ZHANG Zhiyong,LI Jiangtao,et al.Comparison analysis on permeability improved effect of single and multisection hydraulic fracturing in deep depth seam[J].Coal Science and Technology,2017,45(6):50-54.
[5]袁志刚,任梅清,沈永红,等.穿层钻孔煤巷条带水力压裂防突技术及应用[J].重庆大学学报,2016,39(1):72-78.YUAN Zhigang,REN Meiqing,SHEN Yonghong,et al.Hydraulic fracturing technology by drilling through strata for outburst prevention in coal roadway stripes and its application[J].Journal of Chongqing University,2016,39(1):72-78.
[6]陶云奇,冯丹,马耕,等.水力冲孔物理模拟试验及其卸压增透效果研究[J].煤炭科学技术,2017,45(6):55-60.TAO Yunqi,FENG Dan,MA Geng,et al.Study on physical simulation experiment of hydraulic borehole flushing and pressure released and permeability improved effect[J].Coal Science and Technology,2017,45(6):55-60.
[7]冯丹,许江,陶云奇,等.水力冲孔物理模拟试验系统研制及其应用[J].采矿与安全工程学报,2017,34(4):782-788.FENG Dan,XU Jiang,TAO Yunqi,et al.Development of hydraulic punching test system and its application[J].Journal of Mining&Safety Engineering,2017,34(4):782-788.
[8]罗朝义,江泽标,郑昌盛,等.CO2相变致裂技术在顺煤层钻孔增透中的应用[J].煤炭科学技术,2017,45(11):138-143.LUO Zhaoyi,JIANG Zebiao,ZHENG Changsheng,et al.Application on permeability improvement technology with CO2phase change to borehole drilling along coal seam[J].Coal Science and Technology,2017,45(11):138-143.
[9]曹运兴,张军胜,田林,等.低渗煤层定向多簇气相压裂瓦斯治理技术研究与实践[J].煤炭学报,2017,42(10):2631-2641.CAO Yunxing,ZHANG Junsheng,TIAN Lin,et al.Research and application of CO2gas fracturing for gas control in low permeability coal seams[J].Journal of China Coal Society,2017,42(10):2631-2641.
[10]娄亚北,冯利民,刘健,等.穿层深孔爆破在突出坚硬煤层瓦斯抽采中的应用[J].煤炭科学技术,2015,43(12):66-71.LOU Yabei,FENG Limin,LIU Jian,et al.Through strata deep borehole blasting applied to gas drainage in hard outburst seam[J].Coal Science and Technology,2015,43(12):66-71.
[11]林柏泉,邹全乐,沈春明,等.双动力协同钻进高效卸压特性研究及应用[J].煤炭学报,2013,38(6):911-917.LIN Baiquan,ZOU Quanle,SHEN Chunming,et al.Investigation on highly effective depressurization property of dual-power drilling and its application[J].Journal of China Coal Society,2013,38(6):911-917.
[12]刘厅,林柏泉,邹全乐,等.杨柳煤矿割缝预抽后煤体孔隙结构变化特征[J].天然气地球科学,2015,26(10):1999-2008.LIU Ting,LIN Baiquan,ZOU Quanle,et al.Pore characterristics of coal with the treatment of hydraulic slotting and gas pre-drainage in Yangliu coal mine[J].Natural Gas Geoscience,2015,26(10):1999-2008.
[13]薛王龙.掘进工作面水力割缝抽采瓦斯的数值模拟研究[D].太原:太原理工大学,2016.
[14]闫发志,朱传杰,郭畅,等.割缝与压裂协同增透技术参数数值模拟与试验[J].煤炭学报,2015,40(4):823-829.YAN Fazhi,ZHU Chuanjie,GUO Chang,et al.Numerical simulation parameters and test of cutting and fracturing collaboration permeability-increasing technology[J].Journal of China Coal Society,2015,40(4):823-829.
[15]林柏泉,刘厅,邹全乐,等.割缝扰动区裂纹扩展模式及能量演化规律[J].煤炭学报,2015,40(4):719-727.LIN Baiquan,LIU Ting,ZOU Quanle,et al.Crack propagation modes and energy evolution within slotting disturbed zone[J].Journal of China Coal Society,2015,40(4):719-727.
[16]顾北方.高压水射流割缝煤体损伤演化规律研究与应用[D].北京:中国矿业大学(北京),2016.
[17]刘志伟,张帅.高瓦斯突出煤层底抽巷合理布置研究[J].煤炭科学技术,2018,46(10):155-160.LIU Zhiwei,ZHANG Shuai.Study on rational layout of floor gas drainage gateway in high gassy-outburst seam[J].Coal Science and Technology,2018,46(10):155-160.
[18]赵阳升.多孔介质多场耦合作用及其工程响应[M].北京:科学出版社,2010.
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