Relationships of the iC_4/n C_4 and iC_5/nC_5 ratios with maturity of coal-derived gases of Triassic Xujiahe Formation in central Sichuan Basin, SW China
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摘要
The original gas reservoirs in different areas and different layers of the Triassic Xujiahe Formation in the central Sichuan Basin are studied to reveal the relationships of iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas components with maturity using conventional natural gas geochemical research methods. The testing results of 73 gas samples from 8 gas fields show that the iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas have a good positive correlation, and the correlation coefficient is above 0.8. Both the iC_4/n C_4 and iC_5/n C_5 ratios become higher with the increase of natural gas dryness coefficient(C_1/C_(1+)) and the methane carbon isotope becoming less negative. These parameters are highly correlated. This study not only reveals characteristics of heavy hydrocarbon isomers generated by coal formation,but also puts forward new identification indicators reflecting the maturity of coal-derived gas, the regression between iC_4/n C_4, iC_5/n C_5 and R_o, which can provide an important reference for maturity, migration and accumulation of coal-derived gas, and late stage reformation of coal-derived gas reservoirs.
The original gas reservoirs in different areas and different layers of the Triassic Xujiahe Formation in the central Sichuan Basin are studied to reveal the relationships of iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas components with maturity using conventional natural gas geochemical research methods. The testing results of 73 gas samples from 8 gas fields show that the iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas have a good positive correlation, and the correlation coefficient is above 0.8. Both the iC_4/n C_4 and iC_5/n C_5 ratios become higher with the increase of natural gas dryness coefficient(C_1/C_(1+)) and the methane carbon isotope becoming less negative. These parameters are highly correlated. This study not only reveals characteristics of heavy hydrocarbon isomers generated by coal formation,but also puts forward new identification indicators reflecting the maturity of coal-derived gas, the regression between iC_4/n C_4, iC_5/n C_5 and R_o, which can provide an important reference for maturity, migration and accumulation of coal-derived gas, and late stage reformation of coal-derived gas reservoirs.
The original gas reservoirs in different areas and different layers of the Triassic Xujiahe Formation in the central Sichuan Basin are studied to reveal the relationships of iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas components with maturity using conventional natural gas geochemical research methods. The testing results of 73 gas samples from 8 gas fields show that the iC_4/n C_4 and iC_5/n C_5 ratios in coal-derived gas have a good positive correlation, and the correlation coefficient is above 0.8. Both the iC_4/n C_4 and iC_5/n C_5 ratios become higher with the increase of natural gas dryness coefficient(C_1/C_(1+)) and the methane carbon isotope becoming less negative. These parameters are highly correlated. This study not only reveals characteristics of heavy hydrocarbon isomers generated by coal formation,but also puts forward new identification indicators reflecting the maturity of coal-derived gas, the regression between iC_4/n C_4, iC_5/n C_5 and R_o, which can provide an important reference for maturity, migration and accumulation of coal-derived gas, and late stage reformation of coal-derived gas reservoirs.
引文
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[7]LIU Wenhui,XU Yongchang.A two stage model of carbon isotopic fractionation in coal gas.Geochimica,1999,28(4):359-366.
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[9]QIN Shengfei,DAI Jinxing,WANG Lansheng.Different origins of natural gas in secondary gas pool in Western Sichuan foreland basin.Geochimica,2007,36(4):368-374.
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[12]WANG Peng,SHEN Zhongmin,HE Chongkang,et al.The geochemical characteristics of butane and its application.Natural Gas Geoscience,2017,28(4):529-538.
[13]LI Guangzhi,WU Xianghua.The petroleum geological significance of somerization rates?i C4/?nC4 and?i C5/?n C5.Geophysical&Geochemical Exploration,2002,26(2):135-139.
[14]QIN S F,ZHANG Y H,ZHAO C Y,et al.Geochemical evidence for in situ accumulation of tight gas in the Xujiahe Formation coal measures in the central Sichuan Basin,China.International Journal of Coal Geology,2018,196:173-184.
[15]XU Zhangyou,SONG Li,WU Xinsong,et al.Typical gas reservoir and main controlling factors of reservoir-forming of Upper Triassic Xujiahe Formation in central Sichuan Basin.Lithologic Reservoirs,2009,21(2):7-11.
[16]WANG Wei,XU Guosheng,YONG Ziquan,et al.Distribution rule and formation mechanism of gas and water in Layer 4 of Xiangxi Group of the central area in Sichuan,China.Journal of Chengdu University of Technology(Science&Technology Edition),2005,32(4):378-382.
[17]YANG Wei,XIE Zengye,JIN Hui,et al.Reservoir evaluation and pooling mechanism of the Xujiahe formation in the Sichuan Basin.Natural Gas Industry,2010,30(12):10-15.
[18]ZHANG Xiangxiang,ZOU Caineng,ZHU Rukai,et al.Reservoir diagenetic facies of the Upper Triassic Xujiahe Formation in the central Sichuan Basin.Acta Petrolei Sinica,2011,32(2):257-264.
[19]DAI Jinxing.Giant coal-derived gas fields and their gas sources in China.Beijing:Science Press,2016.
[20]DAI Jinxing,ZHONG Ningning,LIU Dehan,et al.Geological basis and controlling factors of large and medium gas fields in China.Beijing:Petroleum Industry Press,2000.
[21]DAI J X,NI Y Y,ZOU C N.Stable carbon and hydrogen isotopes of natural gases sourced from the Xujiahe Formation in the Sichuan Basin,China.Natural Gas Geoscience,2012,43:103-111.
[22]LI Denghua,LI Wei,WANG Zecheng,et al.Genetic type and source of gas in the Guang’an gas field,central Sichuan.Geology in China,2007,34(4):829-836.
[23]TAO Shizhen,ZOU Caineng,TAO Xiaowan,et al.Study on fluid and gas accumulation mechanism of Xujiahe Formation of Upper Triassic in the Sichuan Basin.Bulletin of Mineralogy,Petrology and Geochemistry,2009,28(1):2-11.
[24]QIN S F,LI F,LI W,et al.Formation mechanism of tight coal-derived-gas reservoirs with medium-low abundance in Xujiahe Formation,central Sichuan Basin,China.Marine and Petroleum Geology,2018,89:144-154.
[25]DAI Jinxing,NI Yunyan,HU Guoyi,et al.Stable carbon and hydrogen isotopes of gases from the large tight gas fields in China.SCIENCE CHINA Earth Sciences,2014,57(1):88-103.
[26]WHITICAR M J.Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane.Chemical Geology,1999,161(1/2/3):291-314.
[27]LIN Renzi.Application of light hydrocarbon technology in oil and gas exploration.Wuhan:China Geological University Press,1992.
[28]GAO Gang,GANG Wenzhe,HAO Shisheng,et al.The evolution characteristics of gaseous products of humic coal and its geological significance.Acta Sedimentologica Sinica,1998,16(2):30-33,41.
[29]ZUMBERGE J,FERWORN K,BROWN S.Isotopic reversal(‘rollover’)in shale gases produced from the Mississippian Barnett and Fayetteville formations.Marine and Petroleum Geology,2012,31(1):43-52.
[2]DAI Jinxing,NI Yunyan,HUANG Shipeng,et al.Significant function of coal-derived gas study for natural gas industry in China.Natural Gas Geoscience,2014,25(1):1-22.
[3]ZHAO Wenzhi,WANG Hongjun,QIAN Kai.Progress of coal-formed gas geological theory and its status in natural gas industry in China.Petroleum Exploration and Development,2009,36(3):280-288.
[4]ZHANG Fudong,LI Jun,WEI Guoqi,et al.Formation mechanism of tight sandstone gas in areas of low hydrocarbon generation intensity:A case study of the Upper Paleozoic in North Tianhuan Depression in Ordos Basin,NW China.Petroleum Exploration and Development,2018,45(1):73-81.
[5]STAHL W J,GARE B D.Source-rock identification by isotope analyses of natural gases from field in the Val Verde and Delaware Basins,West Texas.Chemical Geology,1975,16(4):257-267.
[6]DAI Jinxing,QI Houfa.δ13C-Ro relationship of coal derived gas in China.Chinese Science Bulletin,1989,34(9):690-692.
[7]LIU Wenhui,XU Yongchang.A two stage model of carbon isotopic fractionation in coal gas.Geochimica,1999,28(4):359-366.
[8]DAI Jinxing,NI Yunyan,ZHANG Wenzheng,et al.Relationships between wetness and maturity of coal-derived gas in China.Petroleum Exploration and Development,2016,43(5):675-678.
[9]QIN Shengfei,DAI Jinxing,WANG Lansheng.Different origins of natural gas in secondary gas pool in Western Sichuan foreland basin.Geochimica,2007,36(4):368-374.
[10]YE Sujuan,ZHU Hongquan,LI Rong,et al.Tracing natural gas migration by integrating organic and inorganic geochemical data:A case study of the Jurassic gas fields in western Sichuan Basin,SW China.Petroleum Exploration and Development,2017,44(4):549-560.
[11]HAO Shisheng,HUANG Zhilong,YANG Jiaqi.The migrationaccumulation equilibrium theory and application of natural gas.Beijing:Petroleum Industry Press,1994:12-13.
[12]WANG Peng,SHEN Zhongmin,HE Chongkang,et al.The geochemical characteristics of butane and its application.Natural Gas Geoscience,2017,28(4):529-538.
[13]LI Guangzhi,WU Xianghua.The petroleum geological significance of somerization rates?i C4/?nC4 and?i C5/?n C5.Geophysical&Geochemical Exploration,2002,26(2):135-139.
[14]QIN S F,ZHANG Y H,ZHAO C Y,et al.Geochemical evidence for in situ accumulation of tight gas in the Xujiahe Formation coal measures in the central Sichuan Basin,China.International Journal of Coal Geology,2018,196:173-184.
[15]XU Zhangyou,SONG Li,WU Xinsong,et al.Typical gas reservoir and main controlling factors of reservoir-forming of Upper Triassic Xujiahe Formation in central Sichuan Basin.Lithologic Reservoirs,2009,21(2):7-11.
[16]WANG Wei,XU Guosheng,YONG Ziquan,et al.Distribution rule and formation mechanism of gas and water in Layer 4 of Xiangxi Group of the central area in Sichuan,China.Journal of Chengdu University of Technology(Science&Technology Edition),2005,32(4):378-382.
[17]YANG Wei,XIE Zengye,JIN Hui,et al.Reservoir evaluation and pooling mechanism of the Xujiahe formation in the Sichuan Basin.Natural Gas Industry,2010,30(12):10-15.
[18]ZHANG Xiangxiang,ZOU Caineng,ZHU Rukai,et al.Reservoir diagenetic facies of the Upper Triassic Xujiahe Formation in the central Sichuan Basin.Acta Petrolei Sinica,2011,32(2):257-264.
[19]DAI Jinxing.Giant coal-derived gas fields and their gas sources in China.Beijing:Science Press,2016.
[20]DAI Jinxing,ZHONG Ningning,LIU Dehan,et al.Geological basis and controlling factors of large and medium gas fields in China.Beijing:Petroleum Industry Press,2000.
[21]DAI J X,NI Y Y,ZOU C N.Stable carbon and hydrogen isotopes of natural gases sourced from the Xujiahe Formation in the Sichuan Basin,China.Natural Gas Geoscience,2012,43:103-111.
[22]LI Denghua,LI Wei,WANG Zecheng,et al.Genetic type and source of gas in the Guang’an gas field,central Sichuan.Geology in China,2007,34(4):829-836.
[23]TAO Shizhen,ZOU Caineng,TAO Xiaowan,et al.Study on fluid and gas accumulation mechanism of Xujiahe Formation of Upper Triassic in the Sichuan Basin.Bulletin of Mineralogy,Petrology and Geochemistry,2009,28(1):2-11.
[24]QIN S F,LI F,LI W,et al.Formation mechanism of tight coal-derived-gas reservoirs with medium-low abundance in Xujiahe Formation,central Sichuan Basin,China.Marine and Petroleum Geology,2018,89:144-154.
[25]DAI Jinxing,NI Yunyan,HU Guoyi,et al.Stable carbon and hydrogen isotopes of gases from the large tight gas fields in China.SCIENCE CHINA Earth Sciences,2014,57(1):88-103.
[26]WHITICAR M J.Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane.Chemical Geology,1999,161(1/2/3):291-314.
[27]LIN Renzi.Application of light hydrocarbon technology in oil and gas exploration.Wuhan:China Geological University Press,1992.
[28]GAO Gang,GANG Wenzhe,HAO Shisheng,et al.The evolution characteristics of gaseous products of humic coal and its geological significance.Acta Sedimentologica Sinica,1998,16(2):30-33,41.
[29]ZUMBERGE J,FERWORN K,BROWN S.Isotopic reversal(‘rollover’)in shale gases produced from the Mississippian Barnett and Fayetteville formations.Marine and Petroleum Geology,2012,31(1):43-52.