页岩储层微观裂缝三维精细表征方法
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摘要
裂缝在非常规油气开发中具有重要意义,但高精度观察裂缝三维空间分布特征较为困难。微观层析成像技术(微米CT)使得在微观尺度上观测裂缝的三维结构成为可能。对准噶尔盆地二叠系芦草沟组烃源岩的多个泥页岩样品进行了微米CT扫描;利用Avizo软件对微米CT图像进行处理和分割,获得岩心内部三维裂缝结构模型;使用自主开发的CTSTA程序对岩心内部微裂缝进行定量描述,包括裂缝大小、延伸方向和延伸尺度等参数,同时统计裂缝分类特征、各向异性分布;在统计分析的基础上提取裂缝分布的分形维数。研究表明:裂缝的几何特征在大尺度和小尺度上具有相似性,并可以通过指数律进行描述,分形维数是一个较典型的指数;通过对微观尺度上三维裂缝的定量描述或精细表征,可以获得裂缝在大尺度上分布特征的认知。
Fractures are crucial for unconventional hydrocarbon exploitation,but it is difficult to accurately observe the 3 D spatial distribution characteristics of fractures.Microtomography(micro-CT)technology makes it possible to observe the 3 D structures of fractures at micro-scale.In this study,micro-CT scanning is conducted on multiple mud-shale samples of source rocks in the Permian Lucaogou Formation,Junggar Basin.The Avizo software is applied to process and segment the micro-CT images,so as to obtain the 3 D fracture structure model inside rock core.Therefore,the independently-developed CTSTA program is adopted to quantitatively describe the micro-fractures inside rock core,including fracture dimension,extension direction and extension scale.Meanwhile,this study summarizes the classification characteristics of fractures and their anisotropy.On this basis,the fractal dimensions of fractures can also be extracted.Previous studies have shown that the geometric features of fractures have self-similarity at a large or small scales,which can be described by exponential laws;and the fractal dimension is a typical exponent.Through the quantitative description or characterization of 3 D fractures at micro-scale,the distribution characteristics of fractures on a large scale could be known.
Fractures are crucial for unconventional hydrocarbon exploitation,but it is difficult to accurately observe the 3 D spatial distribution characteristics of fractures.Microtomography(micro-CT)technology makes it possible to observe the 3 D structures of fractures at micro-scale.In this study,micro-CT scanning is conducted on multiple mud-shale samples of source rocks in the Permian Lucaogou Formation,Junggar Basin.The Avizo software is applied to process and segment the micro-CT images,so as to obtain the 3 D fracture structure model inside rock core.Therefore,the independently-developed CTSTA program is adopted to quantitatively describe the micro-fractures inside rock core,including fracture dimension,extension direction and extension scale.Meanwhile,this study summarizes the classification characteristics of fractures and their anisotropy.On this basis,the fractal dimensions of fractures can also be extracted.Previous studies have shown that the geometric features of fractures have self-similarity at a large or small scales,which can be described by exponential laws;and the fractal dimension is a typical exponent.Through the quantitative description or characterization of 3 D fractures at micro-scale,the distribution characteristics of fractures on a large scale could be known.
引文
[1] SCHMOKER J W.Resource-assessment perspectives for unconventional gas systems[J].AAPG Bulletin,2002,86(11):1993-1999.
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[5]王香增.延长石油集团非常规天然气勘探开发进展[J].石油学报,2016,37(1):137-144.WANG Xiangzeng.Advances in unconventional gas exploration and development of Yanchang petroleum group[J].Acta Petrolei Sinica,2016,37(1):137-144.
[6]赵靖舟,曹青,白玉彬,等.油气藏形成与分布:从连续到不连续——兼论油气藏概念及分类[J].石油学报,2016,37(2):145-159.ZHAO Jingzhou,CAO Qing,BAI Yubin,et al.Petroleum accumulation from continuous to discontinuous:concept,classification and distribution[J].Acta Petrolei Sinica,2016,37(2):145-159.
[7]李武广,钟兵,杨洪志,等.页岩储层基质气体扩散能力评价新方法[J].石油学报,2016,37(1):88-96.LI Wuguang,ZHONG Bing,YANG Hongzhi,et al.A new method for gas diffusivity evaluation in matrix rocks of shale reservoir[J].Acta Petrolei Sinica,2016,37(1):88-96.
[8]刘奎,王宴滨,高德利,等.页岩气水平井压裂对井筒完整性的影响[J].石油学报,2016,37(3):406-414.LIU Kui,WANG Yanbin,GAO Deli,et al.Effects of hydraulic fracturing on horizontal wellbore for shale gas[J].Acta Petrolei Sinica,2016,37(3):406-414.
[9] CLARKSON C R,WOOD J,BURGIS S,et al.Nanopore-structure analysis and permeability predictions for a tight gas siltstone reservoir by use of low-pressure adsorption and mercury-intrusion techniques[J].SPE Reservoir Evaluation&Engineering,2012,15(6):648-661.
[10]杨峰,宁正福,胡昌蓬,等.页岩储层微观孔隙结构特征[J].石油学报,2013,34(2):301-311.YANG Feng,NING Zhengfu,HU Changpeng,et al.Characterization of microscopic pore structures in shale reservoirs[J].Acta Petrolei Sinica,2013,34(2):301-311.
[11]苑丹丹,卢双舫,陈方文,等.渝东南地区彭页1井泥页岩微观孔隙结构特征[J].特种油气藏,2016,23(1):49-53.YUAN Dandan,LU Shuangfang,CHEN Fangwan,et al.Shale microscopic pore structure characterization in well pengye 1 of southeast Chongqing[J].Special Oil&Gas Reservoirs,2016,23(1):49-53.
[12]曹涛涛,宋之光,王思波,等.皖南地区二叠系页岩储层微观孔隙特征及影响因素[J].地球科学与环境学报,2016,38(5):668-684.CAO Taotao,SONG Zhiguang,WANG Sibo,et al.Micro pore characteristics and their controlling factors of permian shale reservoir in southern Anhui[J].Journal of Earch Sciences and Environment,2016,38(5):668-684.
[13]张琴,庞正炼,刘人和,等.辽河东部凸起太原组页岩孔隙结构特征研究[J].西南石油大学学报:自然科学版,2017,39(2):35-42.ZHANG Qin,PANG Zhenglian,LIU Renhe,et al.Pore structure characteristics of Taiyuan Formation(C3t)in eastern uplift of Liaohe depression[J].Journal of Southwest Petroleum University:Science&Technology Edition,2017,39(2):35-42.
[14]代全齐,罗群,张晨,等.基于核磁共振新参数的致密油砂岩储层孔隙结构特征——以鄂尔多斯盆地延长组7段为例[J].石油学报,2016,37(7):887-897.DAI Quanqi,LUO Qun,ZHANG Chen,et al.Pore structure characteristics of tight-oil sandstone reservoir based on a new parameter measured by NMR experiment:a case study of seventh member in Yanchang Formation,Ordos Basin[J].Acta Petrolei Sinica,2016,37(7):887-897.
[15]白斌,朱如凯,吴松涛,等.利用多尺度CT成像表征致密砂岩微观孔喉结构[J].石油勘探与开发,2013,40(3):329-333.BAI Bin,ZHU Rukai,WU Songtao,et al.Multi-scale method of Nano(Micro)-CT study on microscopic pore structure of tight sandstone of Yanchang Formation,Ordos Basin[J].Petroleum Exploration and Development,2013,40(3):329-333.
[16] AMBROSE R J,HARTMAN R C,CAMPOS M D,et al.New pore-scale considerations for shale gas in place calculations[R].SPE131772,2010.
[17]马勇,钟宁宁,黄小艳,等.聚集离子束扫描电镜(FIB-SEM)在页岩纳米级孔隙结构研究中的应用[J].电子显微学报,2014,33(3):251-256.MA Yong,ZHONG Ningning,HUANG Xiaoyan,et al.The application of focused ion beam scanning electron microscope(FIBSEM)to the nanometer-sized pores in shales[J].Journal of Chinese Electron Microscopy Society,2014,33(3):251-256.
[18]郭印同,杨春和,贾长贵,等.页岩水力压裂物理模拟与裂缝表征方法研究[J].岩石力学与工程学报,2014,33(1):52-59.GUO Yintong,YANG Chunhe,JIA Changgui,et al.Research on hydraulic fracturing physical simulation of shale and fracture characterization methods[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(1):52-59.
[19] LEE B Y,KIM Y Y,YI S T,et al.Automated image processing technique for detecting and analysing concrete surface cracks[J].Structure and Infrastructure Engineering,2013,9(6):567-577.
[20] ARENA A,PIANE C D,SAROUT J.A new computational approach to cracks quantification from2D image analysis:application to micro-cracks description in rocks[J].Computers&Geosciences,2014,66:106-120.
[21]王平让,黄宏伟,薛亚东.基于图像局部网格特征的隧道衬砌裂缝自动识别[J].岩石力学与工程学报,2012,31(5):991-999.WANG Pingrang,HUANG Hongwei,XUE Yadong.Automatic recognition of cracks in tunnel lining based on characteristics of local grids in images[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(5):991-999.
[22]宋佳.基于数字化方法的微裂缝特征研究[D].成都:成都理工大学,2011.SONG Jia.The research on micro-fracture characteristics based on digital analysis method[D].Chengdu:Chengdu University of Technology,2011.
[23]周英杰,张敬轩,杜玉山,等.埕北30潜山岩心裂缝的分维数及与裂缝密度的关系[J].油气地质与采收率,2004,11(3):19-21.ZHOU Yingjie,ZHANG Jingxuan,DU Yushan,et al.Fractal dimension of core fractures in Chengbei 30 buried-hill reservoir and its relation to fracture density[J].Petroleum Geology and Recovery Efficiency,2004,11(3):19-21.
[24] BORODICH F M.Fractals and fractal scaling in fracture mechanics[J].International Journal of Fracture,1999,95(1/4):239-259.
[25] BOUR O,DAVY P.Connectivity of random fault networks following apower law fault length distribution[J].Water Resources Research,1997,33(7):1567-1583.
[26] DAVY P,LE GOC R,DARCEL C.A model of fracture nucleation,growth and arrest,and consequences for fracture density and scaling[J].Journal of Geophysical Research:Solid Earth,2013,118(4):1393-1407.
[27] BAANT Z P.Scaling of quasibrittle fracture:asymptotic analysis[J].International Journal of Fracture,1997,83:19-40.
[28] LIU Jie,REGENAUER-LIEB K,HINES C,et al.Applications of microtomography to multiscale system dynamics:visualisation,characterisation and high performance computation[M]∥YUEN D A,WANG Long,CHI Xuebin,et al.GPU Solutions to Multiscale Problems in Science and Engineering.Berlin,Heidelberg:Springer,2013:653-674.
[29] LIU Jie,PEREIRA G G,LIU Qingbin,et al.Computational challenges in the analyses of petrophysics using microtomography and upscaling:a review[J].Computers&Geosciences,2016,89:107-117.
[30] WILCOX R D.Surface area approach key to borehole stability[J].Oil and Gas Journal,1990,88:9(9).
[31]邱正松,丁锐,于连香.泥页岩比表面积测定方法研究[J].钻井液与完井液,1999,16(1):9-11.QIU Zhengsong,DING Rui,YU Lianxiang.The determing method researching of specific surface area for mud shale[J].Drilling Fluid&Completion Fluid,1999,16(1):9-11.
[32] GRIFFITH A A.The phenomena of rupture and flow in solids[J].Philosophical Transactions of the Royal Society of London,1921,221:163-198.
[33] RUSSELL D A,HANSON J D,OTT E.Dimension of strange attractors[J].Physical Review Letters,1980,45(14):1175-1178.
[34] LIU Jie,REGENAUER-LIEB K,HINES C,et al.Improved estimates of percolation and anisotropic permeability from3-D X-ray microtomography using stochastic analyses and visualization[J].Geochemistry,Geophysics,Geosystems,2009,10(5).doi:10.1029/2008GC002358
[35] ZINGG T.Beitrag zur schotteranalyse[J].Schweiz Mineral Petrogr Mitt,1935,15:39-140.
[2] LAW B E.Basin-centered gas systems[J].AAPG Bulletin,2002,86(11):1891-1919.
[3]贾承造,郑民,张永峰.中国非常规油气资源与勘探开发前景[J].石油勘探与开发,2012,39(2):129-136.JIA Chengzao,ZHENG Min,ZHANG Yongfeng.Unconventional hydrocarbon resources in China and the prospect of exploration and development[J].Petroleum Exploration and Development,2012,39(2):129-136.
[4]邹才能,翟光明,张光亚,等.全球常规-非常规油气形成分布、资源潜力及趋势预测[J].石油勘探与开发,2015,42(1):13-25.ZOU Caineng,ZHAI Guangming,ZHANG Guangya,et al.Formation,distribution,potential and prediction of global conventional and unconventional hydrocarbon resources[J].Petroleum Exploration and Development,2015,42(1):13-25.
[5]王香增.延长石油集团非常规天然气勘探开发进展[J].石油学报,2016,37(1):137-144.WANG Xiangzeng.Advances in unconventional gas exploration and development of Yanchang petroleum group[J].Acta Petrolei Sinica,2016,37(1):137-144.
[6]赵靖舟,曹青,白玉彬,等.油气藏形成与分布:从连续到不连续——兼论油气藏概念及分类[J].石油学报,2016,37(2):145-159.ZHAO Jingzhou,CAO Qing,BAI Yubin,et al.Petroleum accumulation from continuous to discontinuous:concept,classification and distribution[J].Acta Petrolei Sinica,2016,37(2):145-159.
[7]李武广,钟兵,杨洪志,等.页岩储层基质气体扩散能力评价新方法[J].石油学报,2016,37(1):88-96.LI Wuguang,ZHONG Bing,YANG Hongzhi,et al.A new method for gas diffusivity evaluation in matrix rocks of shale reservoir[J].Acta Petrolei Sinica,2016,37(1):88-96.
[8]刘奎,王宴滨,高德利,等.页岩气水平井压裂对井筒完整性的影响[J].石油学报,2016,37(3):406-414.LIU Kui,WANG Yanbin,GAO Deli,et al.Effects of hydraulic fracturing on horizontal wellbore for shale gas[J].Acta Petrolei Sinica,2016,37(3):406-414.
[9] CLARKSON C R,WOOD J,BURGIS S,et al.Nanopore-structure analysis and permeability predictions for a tight gas siltstone reservoir by use of low-pressure adsorption and mercury-intrusion techniques[J].SPE Reservoir Evaluation&Engineering,2012,15(6):648-661.
[10]杨峰,宁正福,胡昌蓬,等.页岩储层微观孔隙结构特征[J].石油学报,2013,34(2):301-311.YANG Feng,NING Zhengfu,HU Changpeng,et al.Characterization of microscopic pore structures in shale reservoirs[J].Acta Petrolei Sinica,2013,34(2):301-311.
[11]苑丹丹,卢双舫,陈方文,等.渝东南地区彭页1井泥页岩微观孔隙结构特征[J].特种油气藏,2016,23(1):49-53.YUAN Dandan,LU Shuangfang,CHEN Fangwan,et al.Shale microscopic pore structure characterization in well pengye 1 of southeast Chongqing[J].Special Oil&Gas Reservoirs,2016,23(1):49-53.
[12]曹涛涛,宋之光,王思波,等.皖南地区二叠系页岩储层微观孔隙特征及影响因素[J].地球科学与环境学报,2016,38(5):668-684.CAO Taotao,SONG Zhiguang,WANG Sibo,et al.Micro pore characteristics and their controlling factors of permian shale reservoir in southern Anhui[J].Journal of Earch Sciences and Environment,2016,38(5):668-684.
[13]张琴,庞正炼,刘人和,等.辽河东部凸起太原组页岩孔隙结构特征研究[J].西南石油大学学报:自然科学版,2017,39(2):35-42.ZHANG Qin,PANG Zhenglian,LIU Renhe,et al.Pore structure characteristics of Taiyuan Formation(C3t)in eastern uplift of Liaohe depression[J].Journal of Southwest Petroleum University:Science&Technology Edition,2017,39(2):35-42.
[14]代全齐,罗群,张晨,等.基于核磁共振新参数的致密油砂岩储层孔隙结构特征——以鄂尔多斯盆地延长组7段为例[J].石油学报,2016,37(7):887-897.DAI Quanqi,LUO Qun,ZHANG Chen,et al.Pore structure characteristics of tight-oil sandstone reservoir based on a new parameter measured by NMR experiment:a case study of seventh member in Yanchang Formation,Ordos Basin[J].Acta Petrolei Sinica,2016,37(7):887-897.
[15]白斌,朱如凯,吴松涛,等.利用多尺度CT成像表征致密砂岩微观孔喉结构[J].石油勘探与开发,2013,40(3):329-333.BAI Bin,ZHU Rukai,WU Songtao,et al.Multi-scale method of Nano(Micro)-CT study on microscopic pore structure of tight sandstone of Yanchang Formation,Ordos Basin[J].Petroleum Exploration and Development,2013,40(3):329-333.
[16] AMBROSE R J,HARTMAN R C,CAMPOS M D,et al.New pore-scale considerations for shale gas in place calculations[R].SPE131772,2010.
[17]马勇,钟宁宁,黄小艳,等.聚集离子束扫描电镜(FIB-SEM)在页岩纳米级孔隙结构研究中的应用[J].电子显微学报,2014,33(3):251-256.MA Yong,ZHONG Ningning,HUANG Xiaoyan,et al.The application of focused ion beam scanning electron microscope(FIBSEM)to the nanometer-sized pores in shales[J].Journal of Chinese Electron Microscopy Society,2014,33(3):251-256.
[18]郭印同,杨春和,贾长贵,等.页岩水力压裂物理模拟与裂缝表征方法研究[J].岩石力学与工程学报,2014,33(1):52-59.GUO Yintong,YANG Chunhe,JIA Changgui,et al.Research on hydraulic fracturing physical simulation of shale and fracture characterization methods[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(1):52-59.
[19] LEE B Y,KIM Y Y,YI S T,et al.Automated image processing technique for detecting and analysing concrete surface cracks[J].Structure and Infrastructure Engineering,2013,9(6):567-577.
[20] ARENA A,PIANE C D,SAROUT J.A new computational approach to cracks quantification from2D image analysis:application to micro-cracks description in rocks[J].Computers&Geosciences,2014,66:106-120.
[21]王平让,黄宏伟,薛亚东.基于图像局部网格特征的隧道衬砌裂缝自动识别[J].岩石力学与工程学报,2012,31(5):991-999.WANG Pingrang,HUANG Hongwei,XUE Yadong.Automatic recognition of cracks in tunnel lining based on characteristics of local grids in images[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(5):991-999.
[22]宋佳.基于数字化方法的微裂缝特征研究[D].成都:成都理工大学,2011.SONG Jia.The research on micro-fracture characteristics based on digital analysis method[D].Chengdu:Chengdu University of Technology,2011.
[23]周英杰,张敬轩,杜玉山,等.埕北30潜山岩心裂缝的分维数及与裂缝密度的关系[J].油气地质与采收率,2004,11(3):19-21.ZHOU Yingjie,ZHANG Jingxuan,DU Yushan,et al.Fractal dimension of core fractures in Chengbei 30 buried-hill reservoir and its relation to fracture density[J].Petroleum Geology and Recovery Efficiency,2004,11(3):19-21.
[24] BORODICH F M.Fractals and fractal scaling in fracture mechanics[J].International Journal of Fracture,1999,95(1/4):239-259.
[25] BOUR O,DAVY P.Connectivity of random fault networks following apower law fault length distribution[J].Water Resources Research,1997,33(7):1567-1583.
[26] DAVY P,LE GOC R,DARCEL C.A model of fracture nucleation,growth and arrest,and consequences for fracture density and scaling[J].Journal of Geophysical Research:Solid Earth,2013,118(4):1393-1407.
[27] BAANT Z P.Scaling of quasibrittle fracture:asymptotic analysis[J].International Journal of Fracture,1997,83:19-40.
[28] LIU Jie,REGENAUER-LIEB K,HINES C,et al.Applications of microtomography to multiscale system dynamics:visualisation,characterisation and high performance computation[M]∥YUEN D A,WANG Long,CHI Xuebin,et al.GPU Solutions to Multiscale Problems in Science and Engineering.Berlin,Heidelberg:Springer,2013:653-674.
[29] LIU Jie,PEREIRA G G,LIU Qingbin,et al.Computational challenges in the analyses of petrophysics using microtomography and upscaling:a review[J].Computers&Geosciences,2016,89:107-117.
[30] WILCOX R D.Surface area approach key to borehole stability[J].Oil and Gas Journal,1990,88:9(9).
[31]邱正松,丁锐,于连香.泥页岩比表面积测定方法研究[J].钻井液与完井液,1999,16(1):9-11.QIU Zhengsong,DING Rui,YU Lianxiang.The determing method researching of specific surface area for mud shale[J].Drilling Fluid&Completion Fluid,1999,16(1):9-11.
[32] GRIFFITH A A.The phenomena of rupture and flow in solids[J].Philosophical Transactions of the Royal Society of London,1921,221:163-198.
[33] RUSSELL D A,HANSON J D,OTT E.Dimension of strange attractors[J].Physical Review Letters,1980,45(14):1175-1178.
[34] LIU Jie,REGENAUER-LIEB K,HINES C,et al.Improved estimates of percolation and anisotropic permeability from3-D X-ray microtomography using stochastic analyses and visualization[J].Geochemistry,Geophysics,Geosystems,2009,10(5).doi:10.1029/2008GC002358
[35] ZINGG T.Beitrag zur schotteranalyse[J].Schweiz Mineral Petrogr Mitt,1935,15:39-140.