气相压裂增透技术强化煤层瓦斯抽采效果的研究
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摘要
针对高瓦斯低透煤层瓦斯抽采效果差、抽采成本高、抽采时间长等问题,通过应用气相压裂增透技术来强化煤层的瓦斯抽采效果,实验和现场测试分析压裂前后煤样的孔隙裂隙基本参数变化情况,明确增透强化的机理。结果表明:气相压裂煤层孔容和比表面积均以大孔为主;在不同吸附平衡压力和粒径下,压裂煤层的扩散系数随着时间的延长减小的幅度存在差异;气相压裂后煤层孔隙裂隙基本参数都呈现增大的趋势,有利于缩短瓦斯扩散路径,提高瓦斯扩散系数;气相压裂后,钻孔有效抽采半径、煤层透气性系数和渗透率分别提高了2.1～4.3倍、54～96倍和7.54～30.40倍,从而判定压裂煤层由原始难抽采煤层转化为易抽采煤层,气相压裂增透强化瓦斯抽采效果明显。
In view of the problems of poor gas extraction effect,high extraction cost and long extraction time in high gas and low permeability coal seam,gas phase fracturing technology was applied to strengthen gas extraction effect in coal seam.The basic parameters of pore and fracture of coal samples before and after fracturing were analyzed by experiment and field test,and the mechanism of permeability enhancement was clarified.The results showed that the pore volume and specific surface area of fractured coal seam were mainly macroporous;the diffusion coefficient of fractured coal seam decreases with time at different adsorption equilibrium pressures and particle sizes;after gas fracturing,the basic parameters of coal seam pore and fracture showed an increasing trend,which was conducive to shortening gas diffusion path.After gas phase fracturing,the effective extraction radius of borehole,permeability coefficient and permeability of coal seam were increased by 2.1～4.3 times,54～96 times and 7.54～30.40 times,respectively,so that it can be judged that fractured coal seam was transformed from original difficult-to-extract coal seam to easy-to-extract coal seam,and the effect of gas phase fracturing was obvious.
In view of the problems of poor gas extraction effect,high extraction cost and long extraction time in high gas and low permeability coal seam,gas phase fracturing technology was applied to strengthen gas extraction effect in coal seam.The basic parameters of pore and fracture of coal samples before and after fracturing were analyzed by experiment and field test,and the mechanism of permeability enhancement was clarified.The results showed that the pore volume and specific surface area of fractured coal seam were mainly macroporous;the diffusion coefficient of fractured coal seam decreases with time at different adsorption equilibrium pressures and particle sizes;after gas fracturing,the basic parameters of coal seam pore and fracture showed an increasing trend,which was conducive to shortening gas diffusion path.After gas phase fracturing,the effective extraction radius of borehole,permeability coefficient and permeability of coal seam were increased by 2.1～4.3 times,54～96 times and 7.54～30.40 times,respectively,so that it can be judged that fractured coal seam was transformed from original difficult-to-extract coal seam to easy-to-extract coal seam,and the effect of gas phase fracturing was obvious.
引文
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[2] 袁佳.浅谈当前我国能源形势与能源安全战略[J].中国国土资源经济,2014(3):49-51.Yuan Jia.Brief introduction of the current energy situation and energy security strategy of China[J].Natural Resource Economics of China,2014(3):49-51.
[3] 程明俊.煤渗透性能及煤与瓦斯突出过程模拟实验研究[D].重庆:重庆大学,2008.
[4] 张永松.煤矿瓦斯治理现状及改善对策分析[J].科学技术创新,2016(25):63.Zhang Yongsong.Current situation of coal mine gas control and analysis of improvement countermeasures[J].Scientific and Technological Innovation,2016(25):63.
[5] 徐建金.张维煤矿瓦斯地质与煤与瓦斯突出防治技术研究[D].湘潭:湖南科技大学,2015.
[6] 谢和平,王金华,申宝宏,等.煤炭开采新理念—科学开采与科学产能[J].煤炭学报,2012,37(7):1069-1079.Xie Heping,Wang Jinhua,Shen Baohong,et al.New idea of coal mining:scientific mining and sustainable mining capacity[J].Journal of China Coal Society,2012,37(7):1069-1079.
[7] 吴建亭,石宪群,钱高峰.保护层开采瓦斯综合治理与利用技术[J].煤矿安全,2011,42(2):23-26.Wu Jianting,Shi Xianqun,Qian Gaofeng.Comprehensive gas control and utilization technology in protective seam mining[J].Safety in Coal Mines,2011,42(2):23-26.
[8] 张守仁.深煤层煤层气开发有效途径展望[J].中国煤层气,2011,8(4):18-21.Zhang Shouren.Proposed effective developing method for the deep coalbed methane[J].China Coalbed Methane,2011,8(4):18-21.
[9] 宋兆祥.开采解放层和矿井瓦斯抽放[J].煤矿安全,1981(7):37-43.Song Zhaoxiang.Liberation layer mining and mine gas drainage[J].Safety in Coal Mines,1981(7):37-43.
[10] 王轶波,李红涛,赵启峰.上解放层底板下向钻孔抽放被解放层瓦斯技术研究[J].矿业工程研究,2011,26(2):18-21.Wang Yibo,Li Hongtao,Zhao Qifeng.On gas drainage technology of liberated seam in the floor of the upper protective seams through down ward-boreholes[J].Mineral Engineering Research,2011,26(2):18-21.
[11] 戎立帆,柏发松,车志飞.下向穿层瓦斯抽采钻孔新型封孔方法及应用[J].中国安全生产科学技术,2014,10(8):64-68.Rong Lifan,Bai Fasong,Che Zhifei.New hole sealing method and application for gas extraction by downward cross-layer drilling[J].Journal of Safety Science and Technology,2014,10(8):64-68.
[12] 张兴华.利用深孔控制预裂爆破强化瓦斯抽放消除回采工作面突出危险性[J].煤矿安全,2006,37(2):22-24.Zhang Xinghua.Using deep hole controlled pre-splitting blasting to strengthen gas drainage to eliminate outburst danger in mining face[J].Safety in Coal Mines,2006,37(2):22-24.
[13] 周西华,周丽君,范超军,等.低透煤层水力压裂促进瓦斯抽采模拟与试验研究[J].中国安全科学学报,2017,27(10):81-86.Zhou Xihua,Zhou Lijun,Fan Chaojun,et al.Simulating and experimental study on enhancing gas drainage from low permeability coal seam by hydraulic fracturing[J].China Safety Science Journal,2017,27(10):81-86.
[14] 李宗福,孙大发,陈久福,等.水力压裂—水力割缝联合增透技术应用[J].煤炭科学技术,2015,43(10):72-76.Li Zongfu,Sun Dafa,Chen Jiufu,et al.Application of permeability improving technology combined with hydraulic pressure fracturing and hydraulic slotting[J].Coal Science and Technology,2015,43(10):72-76.
[15] 张军胜.高河煤矿气相压裂强化增透瓦斯快速抽采技术研究[D].焦作:河南理工大学,2014.
[16] 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 CO2 gas fracturing for gas control in low permeability coal seams[J].Journal of China Coal Society,2017,42(10):2631-2641.安全与环境