富有机质页岩有机质孔隙度研究——以黔西北下志留统五峰—龙马溪组为例
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摘要
黔西北下志留统五峰—龙马溪组是我国南方海相页岩气勘探的重要目的层,其孔隙类型除了与常规储层相似的粒间孔、粒内孔、溶蚀孔等孔隙外,还发育了大量的有机质孔。近年来,越来越多的研究发现,页岩气储层中有机质孔占有十分重要的地位。本次研究中发现页岩岩石样品中占主要体积的孔隙类型是中孔(2 nm～50 nm)占比44.16%～82.39%,其次是微孔(<2 nm)占比8.57%～41.23%,宏孔(>50 nm)最少,占比4.02%～16.41%;从场发射扫描电子显微镜照片中可以看出,许多宏孔、中孔有明显的挤压变形现象,说明岩石经历了较长时间的压实作用,并可能伴随着部分孔隙被其他矿物充填的过程。由回归分析可以看出:总有机碳(TOC)含量强烈影响微孔和中孔的发育和演化,尤其是对中孔的影响明显,TOC与这两种孔隙体积之间都存在着明显的正相关关系;石英对中孔发育有一定影响,但不如前者明显,同时石英与微孔之间存在一定的负相关关系;黏土矿物与中孔发育之间存在负相关关系;Ro与微孔、中孔占总孔隙体积的百分比有着良好的正相关关系,而与宏孔占总孔隙百分比有着良好的负相关关系。
The lower Silurian Wufeng-Longmaxi Formation marine shale with high organic matter abundance and high thermal maturity are regarded as the main shale gas reservoir in southern China.Pore types in the shale not only include the pores of the conventional reservoir(interparticle pore,intraparticle pore,and dissolution pore) but also the occurrence of a large amount of organic matter pore(OM pore),which plays an important role in the formation of shale gas reservoir.Study shows that the pores in the samples from the lower Silurian Wufeng-Longmaxi Formation marine shale are characterized by mesoscopic pores(2 nm～50 nm in diameter,accounting for 44.16%～82.39%),followed by microscopic pore(<2 nm,accounting for 8.57%～41.23%)and macroscopic pores(>50 nm,accounting for 4.02%～16.41%).Field Emission Scanning Electron Microscopy(FESEM) analysis shows that many macroscopic pores and mesoscopic pores are deformed and resulted from the long-time compaction,accompanied by some pore filling process.Linear-regression analysis indicates that the TOC content strongly influences the development and evolution of the microscopic pores and mesoscopic pores,especially for the mesoscopic pores.TOC content has positive relation with the volume of the above mentioned two pore types.Meanwhile,quartz also has certain influence on the microscopic pore volume,but there is negative correlation between quartz content and microscopic pore volume.It reveals that there is also a negative correlation between mesoscopic pore development and clay mineral content.Ro(vitrinite reflectance) of the shale has positive correlation with the percentage of microscopic pore and mesoscopic pore accounting for the total pore volume.With the increase of the Ro,the percentage of the microscopic pore and macroscopic pore rises,while the percentage of mesoscopic pore declines.
The lower Silurian Wufeng-Longmaxi Formation marine shale with high organic matter abundance and high thermal maturity are regarded as the main shale gas reservoir in southern China.Pore types in the shale not only include the pores of the conventional reservoir(interparticle pore,intraparticle pore,and dissolution pore) but also the occurrence of a large amount of organic matter pore(OM pore),which plays an important role in the formation of shale gas reservoir.Study shows that the pores in the samples from the lower Silurian Wufeng-Longmaxi Formation marine shale are characterized by mesoscopic pores(2 nm～50 nm in diameter,accounting for 44.16%～82.39%),followed by microscopic pore(<2 nm,accounting for 8.57%～41.23%)and macroscopic pores(>50 nm,accounting for 4.02%～16.41%).Field Emission Scanning Electron Microscopy(FESEM) analysis shows that many macroscopic pores and mesoscopic pores are deformed and resulted from the long-time compaction,accompanied by some pore filling process.Linear-regression analysis indicates that the TOC content strongly influences the development and evolution of the microscopic pores and mesoscopic pores,especially for the mesoscopic pores.TOC content has positive relation with the volume of the above mentioned two pore types.Meanwhile,quartz also has certain influence on the microscopic pore volume,but there is negative correlation between quartz content and microscopic pore volume.It reveals that there is also a negative correlation between mesoscopic pore development and clay mineral content.Ro(vitrinite reflectance) of the shale has positive correlation with the percentage of microscopic pore and mesoscopic pore accounting for the total pore volume.With the increase of the Ro,the percentage of the microscopic pore and macroscopic pore rises,while the percentage of mesoscopic pore declines.
引文
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[22] Fu D L,Liu M Y,Zhang K,Zuo J X.Organic carbon density and storage in different soils on the Loess Plateau[J].Arid Zone Res,2014,31 (1),44-50.
[23] Loucks R G,Reed R M,Ruppel S C, et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett Shale[J].J Sediment Res,2009,79:848-861.
[24] Mastalerz M,Schimmelmann A,Drobniak A,Chen,Y.Porosity of Devonian and Mississippian New Albany Shale across a maturation gradient:insights from organic petrology,gas adsorption,and mercury intrusion[J].AAPG Bull,2013,97:1 621–1 643.
[25] 付小东,秦建中,腾格尔.四川盆地东南部海相层系优质烃源层评价—以丁山1井为例[J].石油实验地质,2008,30(6):621-628,642.
[26] 黄籍中.四川盆地页岩气与煤层气勘探前景分析[J].岩性油气藏,2009,21(2):116-120.
[27] 龙鹏宇,张金川.重庆及其周缘地区下古生界页岩气资源勘探潜力[J].天然气工业,2009,12:125-129.
[28] 刘树根,汪华,孙玮,等.四川盆地海相领域油气地质条件专属性问题分析[J].石油与天然气地质,2008,29(6):781-792,818.
[29] 聂海宽,张金川,等.四川盆地及其周缘下寒武统页岩气聚集条件[J].石油学报,2011,32(6):959-967.
[30] 夏威.黔北龙马溪组和牛蹄塘组沉积环境及有机质富集机理以——以RY1和XY1井为例[J].矿物岩石,2017,37(3),77-89.
[31] 陈兰,钟宏,胡瑞忠,等.湘黔地区早寒武世黑色页岩有机碳同位素组成变化及其意义[J].矿物岩石,2006,26(1),81-85.
[2] Curtis M E,Songdergeld C H,Ambrose R J, et al.Microstructural investigation of gas shales in two and three dimensions using nanometer-scale resolution imaging[J].AAPG Bulletin,2012,96(4):665-677.
[3] 崔景伟,邹才能,朱如凯,等.页岩孔隙研究新进展[J].地球科学进展,2012,27(12):1 319-1 325.
[4] 于炳松.页岩气储层孔隙分类与表征[J].地学前缘,2013,20(4):211-220.
[5] 马永,钟宁宁,黄小艳,等.聚焦离子束扫描电镜(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.
[6] 伍岳,樊太亮,蒋恕,等.海相页岩储层微观孔隙体系表征技术及分类方案[J].地质科技情报,2014,33(4):91-97.
[7] Loucks R G,Reed R M,Ruppel S C, et al.Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrocks pores[J].AAPG Bulletin,2012,96(6):1 071-1 098.
[8] Curtis J B.Fractured shale-gas systems[J].AAPG Bulletin,2002,86(11):1921-1938.
[9] Rouquerol J,Avnir D,Fairbridge C W, et al.Recommendations for the characterization of porous solids [J].Pure and Applied Chemistry,1994,66(8):1 739-1 758.
[10] Slatt M R,O′Brien N R.Pore types in the Barnett and Woodford gas shales: Contribution to understanding gas storage and migration pathways in fine -grained rocks [J].AAPG Bulletin,2007,97(4):579-601.
[11] Roger S,Prerna S,Gariel B, et al.Reservoir characterization of unconventional gas shales: Example from the Barnett shale[C]//Proceeding of AAPG Annual Convention,Texas.2008:20-30.
[12] 张金川,聂海宽,徐波,等.四川盆地页岩气成藏地质条件[J].天然气工业,2008,28(2):151-156.
[13] 董大忠,程克明,王玉满,等.中国上扬子区下古生界页岩气形成条件及特征[J].石油与天然气地质,2010,31(3):288-299.
[14] 范二平,唐书恒,张成龙,等.湘西北下古生界黑色页岩扫描电镜孔隙特征[J].古地理学报,2014,16(1):133-142.
[15] 李娟.渝东南地区龙马溪组黑色页岩储层特征———以鹿角剖面和YY1 井为例[D].北京:中国地质大学,2013.
[16] 武景淑,于炳松,张金川,等.渝东南YY1井下志留统龙马溪组页岩孔隙特征及其主控因素[J].地学前缘,2013,20(3):260-269.
[17] 聂海宽,边瑞康,张培先,等.川东南地区下古生界页岩储层微观类型与特征及其对含气量的影响[J].地学前缘,2014,21(4):331-343.
[18] 郭旭升,李宇平,刘若冰,等.四川盆地焦石坝地区龙马溪组页岩微观孔隙结构特征及其控制因素[J].天然气工业,2014,34(6):9-16.
[19] 陈丽华,缪昕,魏宝和.扫描电镜在石油地质上的应用[M].北京:石油工业出版社,1990:12-30.
[20] 焦淑静,韩辉,翁庆萍,等.页岩孔隙结构扫描电镜分析方法研究[J].电子显微学报,2012,31(5):432-436.
[21] Shi M,Yu B S,Xue Z P, et al.Pore characteristics of organic-rich shales with high thermal maturity:A case study of the Longmaxi gas shale reservoirs from well Yuye-1 in southeastern Chongqing,China[J].Journal of Natural Gas Science and Engineering,2015,26:948-959.
[22] Fu D L,Liu M Y,Zhang K,Zuo J X.Organic carbon density and storage in different soils on the Loess Plateau[J].Arid Zone Res,2014,31 (1),44-50.
[23] Loucks R G,Reed R M,Ruppel S C, et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett Shale[J].J Sediment Res,2009,79:848-861.
[24] Mastalerz M,Schimmelmann A,Drobniak A,Chen,Y.Porosity of Devonian and Mississippian New Albany Shale across a maturation gradient:insights from organic petrology,gas adsorption,and mercury intrusion[J].AAPG Bull,2013,97:1 621–1 643.
[25] 付小东,秦建中,腾格尔.四川盆地东南部海相层系优质烃源层评价—以丁山1井为例[J].石油实验地质,2008,30(6):621-628,642.
[26] 黄籍中.四川盆地页岩气与煤层气勘探前景分析[J].岩性油气藏,2009,21(2):116-120.
[27] 龙鹏宇,张金川.重庆及其周缘地区下古生界页岩气资源勘探潜力[J].天然气工业,2009,12:125-129.
[28] 刘树根,汪华,孙玮,等.四川盆地海相领域油气地质条件专属性问题分析[J].石油与天然气地质,2008,29(6):781-792,818.
[29] 聂海宽,张金川,等.四川盆地及其周缘下寒武统页岩气聚集条件[J].石油学报,2011,32(6):959-967.
[30] 夏威.黔北龙马溪组和牛蹄塘组沉积环境及有机质富集机理以——以RY1和XY1井为例[J].矿物岩石,2017,37(3),77-89.
[31] 陈兰,钟宏,胡瑞忠,等.湘黔地区早寒武世黑色页岩有机碳同位素组成变化及其意义[J].矿物岩石,2006,26(1),81-85.