寺河矿区压裂煤储层中裂缝与流动通道模型
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摘要
为阐明流体在压裂煤储层中的流动路径,确立流体的流动通道几何模型,对寺河矿区多口压裂煤层气井进行了跟踪开挖解剖研究,认为压裂煤储层中不同成因裂隙因各自空间尺度、密度、分布特征以及与煤基质的接触面积差异,对流体流动的影响各不相同,裂隙的组合方式控制了压降的传递.研究结果表明:在绝大多数水平铺砂压裂裂缝的最前端,存在一段压开未铺砂的压裂裂缝;在单一煤岩分层中,发育线密度8～11条/5cm的内生裂隙局部密集发育带,线密度3～5条/5cm的气胀节理局部密集发育带,不同煤岩分层内的内生裂隙常被外生裂隙或者气胀节理串联;与压裂裂缝连接的天然裂隙存在明显的压裂液挤压、扩张痕迹.根据裂缝空间分布与组合关系,发现存在由内生裂隙、气胀节理、外生裂隙、压裂裂缝组成的2种基本通道类型.煤基质块中的流体通过内生裂隙密集发育带进入流动通道,气胀节理密集发育带和外生裂隙以及压裂裂缝是流体流动的通道;煤基质块对通道的流体补给速率与通道自身的导流能力,决定了通道内的压降传递效率.
To clarify the flow path of underground fluid in fractured coal reservoir,and establish a flow channel model,an observation was carried out on the wall surface of underground tunnels near the fractured CBM wells at different locations in Sihe mining area.Because of spatial scale,density,distribution characteristics and contact area with the coal matrix,different types of fractures have different effects on fluid flow in fractured coal reservoir.The combination of fractures controls the transfer of pressure drop.Observation results show that at the front end of the horizontal fracturing fractures supported by fracturing sand,there is a fracturing fracture that is not supported by fracturing sand.There are local dense growth segments of cleats and gas expanding fractures in a single layer of coal rock.Their linear densities are respectively 8—11 strips per five centimetres and 3—5 strips per five centimetres.Cleats in dif-ferent layers of coal are often connected by fractures or gas expanding fractures.Natural fractures connected with fracturing fractures are washed and expanded by fracturing fluid.According to the spatial distribution and combination of fractures,two basic channel models consisting of cleats,gas expanding fractures,fractures and fracturing fractures were proposed.Studies indicate that the dense development of gas expanding fractures,fractures,fracturing fractures are the channel for fluid flow.Fluid replenishment rate from the coal matrix block into the channel and the conductivity of channel itself determine the rate of pressure drop in the channel.
To clarify the flow path of underground fluid in fractured coal reservoir,and establish a flow channel model,an observation was carried out on the wall surface of underground tunnels near the fractured CBM wells at different locations in Sihe mining area.Because of spatial scale,density,distribution characteristics and contact area with the coal matrix,different types of fractures have different effects on fluid flow in fractured coal reservoir.The combination of fractures controls the transfer of pressure drop.Observation results show that at the front end of the horizontal fracturing fractures supported by fracturing sand,there is a fracturing fracture that is not supported by fracturing sand.There are local dense growth segments of cleats and gas expanding fractures in a single layer of coal rock.Their linear densities are respectively 8—11 strips per five centimetres and 3—5 strips per five centimetres.Cleats in dif-ferent layers of coal are often connected by fractures or gas expanding fractures.Natural fractures connected with fracturing fractures are washed and expanded by fracturing fluid.According to the spatial distribution and combination of fractures,two basic channel models consisting of cleats,gas expanding fractures,fractures and fracturing fractures were proposed.Studies indicate that the dense development of gas expanding fractures,fractures,fracturing fractures are the channel for fluid flow.Fluid replenishment rate from the coal matrix block into the channel and the conductivity of channel itself determine the rate of pressure drop in the channel.
引文
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[19]王生维,张明.煤储层裂隙形成机理及其研究意义[J].地球科学(中国地质大学学报),1996,21(6):637-640.WANG Shengwei,ZHANG Ming.The mechanism of micro-fractures and cleats of coal reservoirs and their implication for methane recovery[J].Earth Science(Journal of China University of Geosciences),1996,21(6):637-640.
[20]王生维,侯光久,张明,等.晋城成庄矿煤层大裂隙系统研究[J].科学通报,2005,50(b10):38-44.WANG Shengwei,HOU Guangjiu,ZHANG Ming,et al.Analysis of the visible fracture system of coal seam in Chengzhuang coalmine of Jincheng,Shanxi province[J].Chinese Science Bulletin,2005,50(b10):38-44.
[21]刘洪林,王红岩,张建博.煤储层割理评价方法[J].天然气工业,2000,20(4):27-29.LIU Honglin,WANG Hongyan,ZHANG Jianbo.E-valuation mention of cleats in coal reservoir bed[J].Natural Gas Industry,2000,20(4):27-29.
[22]LAUBACH S E,MARRETT R A,OLSON J E,et al.Characteristics and origins of coal cleat:A review[J].International Journal of Coal Geology,1998,35(1-4):175-207.
[23]王生维.煤储层评价原理技术方法及应用[M].武汉:中国地质大学出版社,2012:11-21.WANG Shengwei.Principle,method and application of coal reservoir evaluation[M].Wuhan:China University of Geosciences Press,2012:11-21.
[24]陈立超.沁水盆地南部煤储层压裂裂缝延展机制及充填模式[D].武汉:中国地质大学(武汉),2016:19-47.CHEN Lichao.Propagation mechanisms and filling patterns of hydraulic fracturing cracks of Coalbed methane reservoir in southern Qinshui basin[D].Wuhan:China University of Geosciences(Wuhan),2016:19-47.
[25]陈立超,王生维,何俊铧,等.煤层气井近井压裂裂缝充填特征与堵塞机制[J].中国石油大学学报(自然科学版),2017,41(6):117-122.CHEN Lichao,WANG Shengwei,HE Junhua,et al.Filling characteristics and plugging mechanisms of hydraulic fractures near CBM vertical wells[J].Journal of China University of Petroleum(Edition of Natural Science),2017,41(6):117-122.
[26]王保玉.晋城矿区煤体结构及其对煤层气井产能的影响[D].北京:中国矿业大学(北京),2015:12-25.WANG Baoyu.Coal body structures and its impact on production capacity of coalbed methane wells in Jincheng[D].Beijing:China University of Mining&Technology(Beijing),2015:12-25.
[27]仵彦卿.岩土水力学[M].北京:科学出版社,2009:49-68.WU Yanqin.Geotechnical hydraulics[M].Beijing:Science Press,2009:49-68.
[28]葛家理,宁万福,刘月田,等.现代油藏渗流力学原理[M].北京:石油工业出版社,2001:39-52.GE Jiali,NING Wanfu,LIU yuetian,et al.The mechanics principle of reservoir percolation[M].Beijing:Petroleum Industry Press,2001:39-52.
[29]姚艳斌,刘大锰,汤达祯,等.沁水盆地煤储层微裂隙发育的煤岩学控制机理[J].中国矿业大学学报,2010,39(1):6-13.YAO Yanbin,LIU Dameng,TAGN Dazhen,,et al.Influence and control of coal petrological composition on the development of micro-fracture of coal reservoir in the Qinshui basin[J].Journal of China University of Mining&Technology,2010,39(1):6-13.
[2]RUPPEL T C,GREIN C T,BIENSTOCK D.Adsorption of methane/ethane mixtures on dry coal at elevated pressure[J].Fuel,1972,51(4):297-303.
[3]秦勇,袁亮,胡千庭,等.我国煤层气勘探与开发技术现状及发展方向[J].煤炭科学技术,2012,40(10):1-6.QIN Yong,YUAN Liang,HU Qianting,et al.Status and development orientation of coal bed methane exploration and development technology in China[J].Coal Science and Technology,2012,40(10):1-6.
[4]宋岩,张新民,柳少波.中国煤层气基础研究和勘探开发技术新进展[J].天然气工业,2005,25(1):1-7.SONG Yan,ZHANG Xinmin,LIU Shaobo.Progress in the basic studies and exploration&development techniques of coalbed methane in China[J].Natural Gas Industry,2005,25(1):1-7.
[5]李璗,陈军斌.油气渗流力学[M].北京:石油工业出版社,2009:9-12.LI Tang,CHEN Junbing.Percolation mechanics of gas and oil[M].Beijing:Petroleum Industry Press,2009:9-12.
[6]陈刚,秦勇,杨青,等.不同煤阶煤储层应力敏感性差异及其对煤层气产出的影响[J].煤炭学报,2014,39(3):504-509.CHEN Gang,QIN Yong,YANG Qing,et al.Different stress sensitivity of different coal rank reservoir permeability and its effect on the coalbed methane output[J].Journal of China Coal Society,2014,39(3):504-509.
[7]张小东,杜志刚,李朋朋.不同煤体结构的高阶煤储层物性特征及煤层气产出机理[J].中国科学:地球科学,2017,47(1):72-81.ZHANG Xiaodong,DU Zhigang,LI Pengpeng.Physical characteristics of high-rank coal reservoirs in different coal-body structures and the mechanism of coalbed methane production[J].Science China Earth Sciences,2017,47(1):72-81.
[8]傅雪海,秦勇.多相介质煤层气储层渗透率预测理论与方法[M].徐州:中国矿业大学出版社,2006:19-46.FU Xuehai,QIN Yong.Theory and method of permeability prediction for multiphase medium in coal reservoirs[M].Xuzhou:China University of Mining and Technology Press,2006:19-46.
[9]陈立超,王生维,何俊铧,等.煤粉源集合体对水力压裂效果的影响[J].中国矿业大学学报,2015,44(3):526-531.CHEN Lichao,WANG Shengwei,HE Junhua,et al.study of the impact of coal fines source collection on hydraulic fracturing effect[J].Journal of China University of Mining&Technology,2015,44(3):526-531.
[10]段连秀,王生维,张明.煤储层中裂隙充填物的特征及其研究意义[J].煤田地质与勘探,1999,27(3):33-35.DUANG Lianxiu,WANG Shengwei,ZHANGMing.The characteristics of the fracture fillings in coal reservoirs and its study significance[J].Coal Geology&Exploration,1999,27(3):33-35.
[11]孟召平,蓝强,刘翠丽,等.鄂尔多斯盆地东南缘地应力、储层压力及其耦合关系[J].煤炭学报,2013,38(1):122-128.MENG Zhaoping,LAN Qiang,LIU Guili,et al.Insitu stress and coal reservoir pressure in Southeast margin of Ordos basin and their coupling relations[J].Journal of China Coal Society,2013,38(1):122-128.
[12]张芬娜,綦耀光,徐春成,等.煤粉对煤层气井产气通道的影响分析[J].中国矿业大学学报,2013,42(3):428-435.ZHANG Fenna,QI Yaoguang,XU Chuncheng,et al.Analysis of the impact of gas production channel for coalbed methane well by pulverized coal[J].Journal of China University of Mining&Technology,2013,42(3):428-435.
[13]孙培德,凌志仪.三轴应力作用下煤渗透率变化规律实验[J].重庆大学学报,2000,23(增刊1):28-31.SUN Peide,LING Zhiyi.Experimental study of the law for permeability of coal under Action of 3-triaxial compression[J].Journal of Chongqing University,2000,23(Sup1):28-31.
[14]张慧,王晓刚,员争荣,等.煤中显微裂隙的成因类型及其研究意义[J].岩石矿物学杂志,2002,21(3):278-284.ZHANG Hui,WANG Xiaogang,YUAN Zhengrong,et al.Genetic types of microfractures in coal and their significance[J].Acta Petrologica et Mineralogica,2002,21(3):278-284.
[15]张慧.煤孔隙的成因类型及其研究[J].煤炭学报,2001,26(1):40-44.ZHANG Hui.Genetical type of pores in coal reservoir and its research significance[J].Journal of China Coal Society,2001,26(1):40-44.
[16]GAMSON P,BEAMISH B,JOHNSON D.Coal microstructure and secondary mineralization:their effect on methane recovery[J].Geological Society,London,Special Publications,1996,109(1):165-179.
[17]傅雪海,秦勇,李贵中.储层渗透率研究的新进展[J].辽宁工程技术大学学报,2001,20(6):739-743.FU Xuehai,QIN Yong,LI Guizhong.Advance in study of coal reservoir permeability[J]Journal of Liaoning Technical University,2001,20(6):739-743.
[18]傅雪海,秦勇,薛秀谦,等.煤储层孔、裂隙系统分形研究[J].中国矿业大学学报,2001,30(3):225-228.FU Xuehai,QIN Yong,XUE Xiuqian,et al.Research on fractals of pore and fracture structure of coal reservoirs[J].Journal of China University of Mining&Technology,2001,30(3):225-228.
[19]王生维,张明.煤储层裂隙形成机理及其研究意义[J].地球科学(中国地质大学学报),1996,21(6):637-640.WANG Shengwei,ZHANG Ming.The mechanism of micro-fractures and cleats of coal reservoirs and their implication for methane recovery[J].Earth Science(Journal of China University of Geosciences),1996,21(6):637-640.
[20]王生维,侯光久,张明,等.晋城成庄矿煤层大裂隙系统研究[J].科学通报,2005,50(b10):38-44.WANG Shengwei,HOU Guangjiu,ZHANG Ming,et al.Analysis of the visible fracture system of coal seam in Chengzhuang coalmine of Jincheng,Shanxi province[J].Chinese Science Bulletin,2005,50(b10):38-44.
[21]刘洪林,王红岩,张建博.煤储层割理评价方法[J].天然气工业,2000,20(4):27-29.LIU Honglin,WANG Hongyan,ZHANG Jianbo.E-valuation mention of cleats in coal reservoir bed[J].Natural Gas Industry,2000,20(4):27-29.
[22]LAUBACH S E,MARRETT R A,OLSON J E,et al.Characteristics and origins of coal cleat:A review[J].International Journal of Coal Geology,1998,35(1-4):175-207.
[23]王生维.煤储层评价原理技术方法及应用[M].武汉:中国地质大学出版社,2012:11-21.WANG Shengwei.Principle,method and application of coal reservoir evaluation[M].Wuhan:China University of Geosciences Press,2012:11-21.
[24]陈立超.沁水盆地南部煤储层压裂裂缝延展机制及充填模式[D].武汉:中国地质大学(武汉),2016:19-47.CHEN Lichao.Propagation mechanisms and filling patterns of hydraulic fracturing cracks of Coalbed methane reservoir in southern Qinshui basin[D].Wuhan:China University of Geosciences(Wuhan),2016:19-47.
[25]陈立超,王生维,何俊铧,等.煤层气井近井压裂裂缝充填特征与堵塞机制[J].中国石油大学学报(自然科学版),2017,41(6):117-122.CHEN Lichao,WANG Shengwei,HE Junhua,et al.Filling characteristics and plugging mechanisms of hydraulic fractures near CBM vertical wells[J].Journal of China University of Petroleum(Edition of Natural Science),2017,41(6):117-122.
[26]王保玉.晋城矿区煤体结构及其对煤层气井产能的影响[D].北京:中国矿业大学(北京),2015:12-25.WANG Baoyu.Coal body structures and its impact on production capacity of coalbed methane wells in Jincheng[D].Beijing:China University of Mining&Technology(Beijing),2015:12-25.
[27]仵彦卿.岩土水力学[M].北京:科学出版社,2009:49-68.WU Yanqin.Geotechnical hydraulics[M].Beijing:Science Press,2009:49-68.
[28]葛家理,宁万福,刘月田,等.现代油藏渗流力学原理[M].北京:石油工业出版社,2001:39-52.GE Jiali,NING Wanfu,LIU yuetian,et al.The mechanics principle of reservoir percolation[M].Beijing:Petroleum Industry Press,2001:39-52.
[29]姚艳斌,刘大锰,汤达祯,等.沁水盆地煤储层微裂隙发育的煤岩学控制机理[J].中国矿业大学学报,2010,39(1):6-13.YAO Yanbin,LIU Dameng,TAGN Dazhen,,et al.Influence and control of coal petrological composition on the development of micro-fracture of coal reservoir in the Qinshui basin[J].Journal of China University of Mining&Technology,2010,39(1):6-13.