四川盆地长宁龙马溪组页岩赋存空间及含气规律
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摘要
四川盆地长宁地区下志留统龙马溪组页岩广泛发育,该地区页岩储层的微观孔隙结构及全尺度孔径分布特征尚不明确,运用聚焦离子束扫描电镜、高压压汞、低温氮吸附及低温CO_2吸附等实验技术,以宁203井为例,研究了龙马溪组下部页岩储层的孔隙结构特征,并建立了一套页岩纳—微米全尺度孔径分布测试分析方法。该方法利用气体吸附法和高压压汞法获得第1孔径分布数据和第2孔径分布数据,通过对2种方法获得的重复部分孔径分布数据进行差异性分析,并根据分析判断结果获取处理后的孔径为3.7~200.0 nm的分布数据,再结合2种方法获得的不重复部分的孔径分布数据,从而可以计算微孔、介孔和宏孔在整个岩石样品中的占比,获得岩石样品全尺度孔径分布数据。结果表明:该区龙马溪组下部页岩孔隙结构复杂,"墨水瓶"状细颈孔隙大量存在,微孔与中孔、大孔相互连通,但孔喉细小,连通性较差;介孔和微孔占比超过80%。直径>15 nm的孔喉中主要为游离气,直径<2 nm的孔喉中主要为吸附气。
The shales of the lower Silurian Longmaxi are widely developed in Changning area of Sichuan Basin.The micro pore structure and full-scale pore size distribution characteristics of shale reservoirs in this area are not yet clear. The pore structure of lower Longmaxi shale reservoir was researched by field emission scanning electron microscope(FE-SEM),high pressure mercury intrusion,low temperature nitrogen adsorption and low temperature CO_2 adsorption. Taking the Ning 203 well as an example,a set of analysis method about nanometer-micrometerfull scale pore size distribution was established. The first pore size distribution was obtained by gas adsorption,and the second pore size distribution was obtained by high pressure mercury intrusion in this method. The difference between the data of the pore size distribution obtained by the two kinds of tests was judged. According to the result of the judgment,the pore size distribution data of 3.7-200.0 nm were obtained after treatment. The pore size distribution data of the non-repeated pore size were obtained by the two methods combined. The micropores,mesopores and macropores for core samples in proportion were calculated,so the full-scale pore size distribution data of core samples were obtained. Results show the lower part of Longmaxi shale pore structure is very complex. Micropores are connected in series with mesopores and macropores. The pore throat is small,so the connectivity is poor. Mesoporous and microporous accounted for the percentage of pore volume is more than 80%. Pore throats of the diameter above 15 nm mainly contain free gas,and the ones below 2 nm mainly contain adsorbed gas.
The shales of the lower Silurian Longmaxi are widely developed in Changning area of Sichuan Basin.The micro pore structure and full-scale pore size distribution characteristics of shale reservoirs in this area are not yet clear. The pore structure of lower Longmaxi shale reservoir was researched by field emission scanning electron microscope(FE-SEM),high pressure mercury intrusion,low temperature nitrogen adsorption and low temperature CO_2 adsorption. Taking the Ning 203 well as an example,a set of analysis method about nanometer-micrometerfull scale pore size distribution was established. The first pore size distribution was obtained by gas adsorption,and the second pore size distribution was obtained by high pressure mercury intrusion in this method. The difference between the data of the pore size distribution obtained by the two kinds of tests was judged. According to the result of the judgment,the pore size distribution data of 3.7-200.0 nm were obtained after treatment. The pore size distribution data of the non-repeated pore size were obtained by the two methods combined. The micropores,mesopores and macropores for core samples in proportion were calculated,so the full-scale pore size distribution data of core samples were obtained. Results show the lower part of Longmaxi shale pore structure is very complex. Micropores are connected in series with mesopores and macropores. The pore throat is small,so the connectivity is poor. Mesoporous and microporous accounted for the percentage of pore volume is more than 80%. Pore throats of the diameter above 15 nm mainly contain free gas,and the ones below 2 nm mainly contain adsorbed gas.
引文
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[7]徐祖新.基于CT扫描图像的页岩储层非均质性研究.岩性油气藏,2014,26(6):46-49.XU Z X.Heterogeneity of shale reservoirs based on CT images.Lithologic Reservoirs,2014,26(6):46-49.
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[13]LI T,TIAN H,CHEN J,et al.Application of low pressure gas adsorption to the characterization of pore size distribution of shales:an example from Southeastern Chongqing area,China.Journal of Natural Gas Geoscience,2016,1(3):221-230.
[14]HAN H,CAO Y,CHEN S,et al.Influence of particle size on gasadsorption experiments of shales:an example from a Longmaxi Shale sample from the Sichuan Basin,China.Fuel,2016,186:750-757.
[15]徐勇,吕成福,陈国俊,等.川东南龙马溪组页岩孔隙分形特征.岩性油气藏,2015,27(4):32-39.XU Y,LYU C F,CHEN G J,et al.Fractal characteristics of shale pores of Longmaxi Formation in southeast Sichuan Basin.Lithologic Reservoirs,2015,27(4):32-39.
[16]WASHBURN E W.Note on the method of determining the distribution of pore sizes in a porous material.Proceedings of the National Academy of Sciences,1921,7(4):115-116.
[17]胡容泽.粉末颗粒和孔隙的测量.北京:冶金工业出版社,1982:23-33.HU R Z.Measurement of powder particles and pores.Beijing:Metallurgical Industry Press,1982:23-33.
[18]刘玉新.颗粒材料孔结构形态的测量和表征.中国粉体技术,2000,6(4):21-23.LIU Y X.Measurement and expression of pore structure of particle material.China Powder Science and Technology,2000,6(4):21-23.
[19]谢晓永,唐洪明,王春华,等.氮气吸附法和压汞法在测试泥页岩孔径分布中的对比.天然气工业,2006,26(12):100-102.XIE X Y,TANG H M,WANG C H,et al.Contrast of nitrogen adsorption method and mercury porosimetry method in analysis of shales pores size distribution.Natural Gas Industry,2006,26(12):100-102.
[20]杨峰,宁正福,胡昌蓬,等.页岩储层微观孔隙结构特征.石油学报,2013,34(2):301-311.YANG F,NING Z F,HU C P,et al.Characterization of microscopic pore structures in shale reservoirs.Acta Petrolei Sinica,2013,34(2):301-311.
[21]LOWELL S,SHIELDS J ETHOMAS M A,et al.Characterization of porous solids and powders:surface area,pore size and density.Dordrecht:Kluwer Academic Publishers,2004:58-71.
[22]SCHNEIDER P.Adsorption-isotherms of microporous mesoporous solids revisited.Applied Catalysis A:General,1995,129(2):157-165.
[23]邵晓红,张现仁,汪文川.密度泛函与分子模拟计算介孔孔径分布比较.物理化学学报,2003,19(6):538-542.SHAO X H,ZHANG X R,WANG W C.Comparison of density functional theory and molecular simulation methods for pore size distribution of mesoporous materials.Acta Physico-Chimica.Sinica,2003,19(6):538-542.
[24]张超,高才,鲁雪生,等.多孔活性炭孔径分布的表征.离子交换与吸附,2006,22(1):187-192.ZHANG C,GAO C,LU X S,et al.Characterization of pore size distribution of porous activated carbons.Ion Exchange and Adsorption,2006,22(1):187-192.
[25]蔚德磊,张双全,王壬峰,等.活性炭孔径分布与CO2吸附量关系的研究.煤炭转化,2014,37(3):68-71.WEI D L,ZHANG S Q,WANG R F,et al.Study on relationship between pore size distribution of active carbon and CO2adsorptive capacity.Coal Conversion,2014,37(3):68-71.
[26]盛骤,谢式千,潘承毅.概率论与数理统计(第三版).北京:高等教育出版社,2001:213-224.SHENG Z,XIE S Q,PAN C Y.Probability theory and mathematical statistics.3rd ed.Beijing:Higher Education Press,2001:213-224.
[27]FITZGERALD J E,SUDIBANDRIYO M,PAN Z,et al.Modeling the adsorption of pure gases on coals with the SLD model.Carbon,2003,41(12):2203-2216.
[28]SOULE A D,SMITH C A,YANG X,et al.Adsorption modeling with the ESD equation of state.Langmuir,2001,17(10):2950-2957.
[29]BHARATH R,CARL T,LIRA R S.Simplified local density model for adsorption over large pressure ranges.AICh E Journal,1995,41(4):838-845.
[2]何建华,丁文龙,付景龙,等.页岩微观孔隙成因类型研究.岩性油气藏,2014,26(5):30-35.HE J H,DING W L,FU J L,et al.Quantitative characterization of pore structure in shale reservoir of Longmaxi Formation in Sichuan Basin.Lithologic Reservoirs,2014,26(5):30-35.
[3]黄文明,刘树根,马文辛,等.川东南-鄂西渝东地区下古生界页岩气勘探前景.地质通报,2011,30(2/3):364-371.HUANG W M,LIU S G,MA W X,et al.Shale gas exploration prospect of Lower Paleozoic in southeastern Sichuan and western Hubei-eastern Chongqing areas,China.Geological Bulletin of China,2011,30(2/3):364-371.
[4]李艳霞,林娟华,龙幼康,等.中扬子地区下古生界海相泥-页岩含气勘探远景.地质通报,2011,30(2/3):349-356.LI Y X,LIN J H,LONG Y K,et al.Exploration prospect of gasbearing marine mudstone-shale in Lower Palaeozoic in the central Yangtze area,China.Geological Bulletin of China,2011,30(2/3):349-356.
[5]熊健,罗丹序,刘向君,等.鄂尔多斯盆地延长组页岩孔隙结构特征及其控制因素.岩性油气藏,2016,28(2):16-23.XIONG J,LUO D X,LIU X J,et al.Characteristics and controlling factors of shale pore structure of Yanchang Formation in Ordos Basin.Lithologic Reservoirs,2016,28(2):16-23.
[6]LIANG L,XIONG J,LIU X.An investigation of the fractal characteristics of the Upper Ordovician Wufeng Formation shale using nitrogen adsorption analysis.Journal of Natural Gas Science and Engineering,2015,27:402-409.
[7]徐祖新.基于CT扫描图像的页岩储层非均质性研究.岩性油气藏,2014,26(6):46-49.XU Z X.Heterogeneity of shale reservoirs based on CT images.Lithologic Reservoirs,2014,26(6):46-49.
[8]孙文峰,李玮,董智煜,等.页岩孔隙结构表征方法新探索.岩性油气藏,2017,29(2):125-130.SUN W F,LI W,DONG Z Y,et al.A new approach to the characterization of shale pore structure.Lithologic Reservoirs,2017,29(2):125-130.
[9]王淑芳,董大忠,王玉满,等.四川盆地南部志留系龙马溪组富有机质页岩沉积环境的元素地球化学判别指标.海相油气地质,2014,19(3):27-34.WANG S F,DONG D Z,WANG Y M,et al.Geochemistry evaluation index of redox-sensitive elements for depositional environments of Silurian Longmaxi organic-rich shale in the south of Sichuan Basin.Marine Origin Petroleum Geology,2014,19(3):27-34.
[10]陈波,皮定成.中上扬子地区志留系龙马溪组页岩气资源潜力评价.中国石油勘探,2009,14(3):15-19.CHEN B,PI D C.Silurian Longmaxi shale gas potential analysis in Middle&Upper Yangtze region.China Petroleum Exploration,2009,14(3):15-19.
[11]SING K S W,EVERETT D H,HAUL R A W,et al.Reporting physisorption data for gas solid systems with special reference to the determination of surface-area and porosity.Pure and Applied Chemistry,1985,57(4):603-619.
[12]龚小平,唐洪明,赵峰,等.四川盆地龙马溪组页岩储层孔隙结构的定量表征.岩性油气藏,2016,28(3):48-57.GONG X P,TANG H M,ZHAO F,et al.Quantitative characterization of pore structure in shale reservoir of Longmaxi Formation in Sichuan Basin.Lithologic reservoir,2016,28(3):48-57.
[13]LI T,TIAN H,CHEN J,et al.Application of low pressure gas adsorption to the characterization of pore size distribution of shales:an example from Southeastern Chongqing area,China.Journal of Natural Gas Geoscience,2016,1(3):221-230.
[14]HAN H,CAO Y,CHEN S,et al.Influence of particle size on gasadsorption experiments of shales:an example from a Longmaxi Shale sample from the Sichuan Basin,China.Fuel,2016,186:750-757.
[15]徐勇,吕成福,陈国俊,等.川东南龙马溪组页岩孔隙分形特征.岩性油气藏,2015,27(4):32-39.XU Y,LYU C F,CHEN G J,et al.Fractal characteristics of shale pores of Longmaxi Formation in southeast Sichuan Basin.Lithologic Reservoirs,2015,27(4):32-39.
[16]WASHBURN E W.Note on the method of determining the distribution of pore sizes in a porous material.Proceedings of the National Academy of Sciences,1921,7(4):115-116.
[17]胡容泽.粉末颗粒和孔隙的测量.北京:冶金工业出版社,1982:23-33.HU R Z.Measurement of powder particles and pores.Beijing:Metallurgical Industry Press,1982:23-33.
[18]刘玉新.颗粒材料孔结构形态的测量和表征.中国粉体技术,2000,6(4):21-23.LIU Y X.Measurement and expression of pore structure of particle material.China Powder Science and Technology,2000,6(4):21-23.
[19]谢晓永,唐洪明,王春华,等.氮气吸附法和压汞法在测试泥页岩孔径分布中的对比.天然气工业,2006,26(12):100-102.XIE X Y,TANG H M,WANG C H,et al.Contrast of nitrogen adsorption method and mercury porosimetry method in analysis of shales pores size distribution.Natural Gas Industry,2006,26(12):100-102.
[20]杨峰,宁正福,胡昌蓬,等.页岩储层微观孔隙结构特征.石油学报,2013,34(2):301-311.YANG F,NING Z F,HU C P,et al.Characterization of microscopic pore structures in shale reservoirs.Acta Petrolei Sinica,2013,34(2):301-311.
[21]LOWELL S,SHIELDS J ETHOMAS M A,et al.Characterization of porous solids and powders:surface area,pore size and density.Dordrecht:Kluwer Academic Publishers,2004:58-71.
[22]SCHNEIDER P.Adsorption-isotherms of microporous mesoporous solids revisited.Applied Catalysis A:General,1995,129(2):157-165.
[23]邵晓红,张现仁,汪文川.密度泛函与分子模拟计算介孔孔径分布比较.物理化学学报,2003,19(6):538-542.SHAO X H,ZHANG X R,WANG W C.Comparison of density functional theory and molecular simulation methods for pore size distribution of mesoporous materials.Acta Physico-Chimica.Sinica,2003,19(6):538-542.
[24]张超,高才,鲁雪生,等.多孔活性炭孔径分布的表征.离子交换与吸附,2006,22(1):187-192.ZHANG C,GAO C,LU X S,et al.Characterization of pore size distribution of porous activated carbons.Ion Exchange and Adsorption,2006,22(1):187-192.
[25]蔚德磊,张双全,王壬峰,等.活性炭孔径分布与CO2吸附量关系的研究.煤炭转化,2014,37(3):68-71.WEI D L,ZHANG S Q,WANG R F,et al.Study on relationship between pore size distribution of active carbon and CO2adsorptive capacity.Coal Conversion,2014,37(3):68-71.
[26]盛骤,谢式千,潘承毅.概率论与数理统计(第三版).北京:高等教育出版社,2001:213-224.SHENG Z,XIE S Q,PAN C Y.Probability theory and mathematical statistics.3rd ed.Beijing:Higher Education Press,2001:213-224.
[27]FITZGERALD J E,SUDIBANDRIYO M,PAN Z,et al.Modeling the adsorption of pure gases on coals with the SLD model.Carbon,2003,41(12):2203-2216.
[28]SOULE A D,SMITH C A,YANG X,et al.Adsorption modeling with the ESD equation of state.Langmuir,2001,17(10):2950-2957.
[29]BHARATH R,CARL T,LIRA R S.Simplified local density model for adsorption over large pressure ranges.AICh E Journal,1995,41(4):838-845.