古生界干酪根热演化模拟实验
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摘要
我国南方下古生界页岩中有着丰富的页岩气资源,但因其时代老,成熟度高,且缺乏镜质体,其有机质热演化程度评价成为一个技术难题,对相关页岩气地质研究造成困扰。已有研究表明,干酪根H/C原子比和O/C原子比会随着有机质热演化程度的增加呈现规律性变化,但是对于缺乏镜质体的下古生界干酪根,以及高过成熟阶段干酪根却鲜有研究,其元素演化规律如何?其元素组成与镜质体反射率之间是否存在明确的定量关系?值得研究。为此,针对二叠系大隆组的泥岩和蓟县系洪水庄组页岩,在350～550℃温度范围内开展了系列干酪根热演化模拟实验,测定了各模拟实验温度下所得干酪根的镜质体反射率(R_O)和C、H、O元素组成,发现干酪根H/C原子比和O/C原子比与有机质成熟度之间具有高度的统计学相关关系。结果显示:①在开展烃源岩演化热模拟实验时,对于在泥盆纪以前沉积缺乏镜质体的烃源岩样品而言,利用与烃源岩样品镜质体反射率R_O值相近的煤样来标定样品热演化进程的方法是可行的;②在热演化进程中,干酪根的H/C、O/C原子比值均会随着有机质成熟度的增加发生规律性的变化,不同类型干酪根的H/C原子比值表现出沿相同路径不断降低的演化特征,而O/C原子比值表现出沿不同路径不断降低但最终趋同的演化特征;③实验中涉及的3种类型干酪根的H/C、O/C原子比(R_(H/C)和R_(O/C))与用镜质体反射率R_O(%)所表征的有机质热演化程度之间均体现同一规律,并存在良好的数学相关关系,可以表达为LgR_O=-0.133 1-1.190 5 LgR_(H/C)-0.054 4LgR_(O/C),适用于该实验中涉及的3种类型干酪根,适用RO值范围为0.6%～3.5%。
Shale gas resources are abundant in the Lower Paleozoic shales in southern China,which are of very old age,high maturity and are lack of vitrinite,and thus lead to a technical problem for evaluating the thermal evolution degree of organic matter in them.Previous studies have shown that the H/C and O/C atomic ratios of kerogen decrease regularly with the increase of its maturity,but there is little research on high maturity stage kerogens,or kerogens lack of virinite,therefore,it remains unclear that how their element evolves and does the evolution of element composition quantitatively reflect to R_O value?These are worthy of study.For this purpose,a series of simulation experiments of thermal evolution of kerogen have been carried out at temperatures ranging from 350℃to 550℃ with Paleozoic source rocks,and the R_O value and C,H,O composition of the kerogens were determined.The results show that:(1)to calibrate thermal evolution degree of kerogen of the Middle-Upper Proterozoic and Lower Paleozoic source rocks lack of vitrinite,coal with similar maturity to the source rock can be used by reacting together with the source rock throughout the thermal simulation experiment process,and it is efficient;(2)H/C and O/C atomic ratios of kerogen correlate highly to its maturity by exhibiting a consistent decrease of H/C atomic ratio with the increase of thermal maturity for all types of kerogens,whereas O/C atomic ratio decreases separately along individual paths for typesⅠ,Ⅱand Ⅲ kerogens with the increase of thermal maturity that meets at last at a high maturity with R_O value around 3.5%;(3)there is a mathematical correlation betwe en H/C and O/C atomic ratios of kerogen(R_(H/C) and R_(O/C))and the thermal maturity of organic matter characterized by vitrinite reflectance(R_O)can be expressed as LgR_O=0.133 1-1.190 5 LgR_(H/C)-0.054 4 LgR_(O/C),which is suitable for all types of kerogens.
Shale gas resources are abundant in the Lower Paleozoic shales in southern China,which are of very old age,high maturity and are lack of vitrinite,and thus lead to a technical problem for evaluating the thermal evolution degree of organic matter in them.Previous studies have shown that the H/C and O/C atomic ratios of kerogen decrease regularly with the increase of its maturity,but there is little research on high maturity stage kerogens,or kerogens lack of virinite,therefore,it remains unclear that how their element evolves and does the evolution of element composition quantitatively reflect to R_O value?These are worthy of study.For this purpose,a series of simulation experiments of thermal evolution of kerogen have been carried out at temperatures ranging from 350℃to 550℃ with Paleozoic source rocks,and the R_O value and C,H,O composition of the kerogens were determined.The results show that:(1)to calibrate thermal evolution degree of kerogen of the Middle-Upper Proterozoic and Lower Paleozoic source rocks lack of vitrinite,coal with similar maturity to the source rock can be used by reacting together with the source rock throughout the thermal simulation experiment process,and it is efficient;(2)H/C and O/C atomic ratios of kerogen correlate highly to its maturity by exhibiting a consistent decrease of H/C atomic ratio with the increase of thermal maturity for all types of kerogens,whereas O/C atomic ratio decreases separately along individual paths for typesⅠ,Ⅱand Ⅲ kerogens with the increase of thermal maturity that meets at last at a high maturity with R_O value around 3.5%;(3)there is a mathematical correlation betwe en H/C and O/C atomic ratios of kerogen(R_(H/C) and R_(O/C))and the thermal maturity of organic matter characterized by vitrinite reflectance(R_O)can be expressed as LgR_O=0.133 1-1.190 5 LgR_(H/C)-0.054 4 LgR_(O/C),which is suitable for all types of kerogens.
引文
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[12]Tissot B P,Welte D H.Petroleum Formation and Occurrence[M].New York:Springer-Verlag,1984.
[13]Basking D K.Evaluation of thermal maturity and hydrocarbon generation potential of source rocks by kerogen H/C ratio[J].Liu Quanyou,Translation.Natural Gas Geoscience,2002,13(5):41-49.Basking D K.利用干酪根H/C比评价烃源岩热成熟度与生烃潜力[J].刘全有译.天然气地球科学,2002,13(5):41-49.
[14]Yi Junjie,Tang Shuhuan,Zhang Songhang.Geochemical characteristics of coal rocks in the hydrous thermal simulation experiment of Beizao Coal Mine[J].Science Technology and Engineering,2015,15(15):118-122.衣骏杰,唐书恒,张松航.北皂煤矿煤岩含水热模拟产物地球化学特征[J].科学技术与工程,2015,15(15):118-122.
[15]Ye Jinhua,Zhu Meiqian,Ding Xiaochen,et al.Study on the preparation of kerogen[J].Petroleum Geology&Experiment,1983,(4):84-89.叶金华,朱美茜,丁晓晨,等.干酪根制备方法的研究[J].石油实验地质,1983(4):84-89.
[16]Hu Xiong,Li Yangbing,Lai Jianbin,et al.Measurement of oxygen in kerogen by the vario micro cube element analyzer[J].Chemical Industry Times,2010,24(4):42-45.胡雄,李洋冰,来建宾,等.用Vario micro cube元素分析仪测定干酪根样品中的氧元素[J].化工时刊,2010,24(4):42-45.
[17]Zhao Junfeng,Liu Chiyang,Wang Xiaomei.The factors influencing the measurement results of vitrinite reflectance[J].Coal Geology&Exploration,2004,32(6):15-18.赵俊峰,刘池洋,王晓梅.镜质体反射率测定结果的影响因素[J].煤田地质与勘探.2004,32(6):15-18.
[18]Tissot B P,Welte D H.Petroleum Formation and Occurrence[M].Berlin,Heidelberg:Springer,1984:1-643.
[19]Chen Ruiyin,Mi Jingkui,Chen Jianping.Maturity of coal-derived hydrocarbon in pyrolysis experiments[J].Natural Gas Geoscience,2018,29(1):96-102.陈瑞银,米敬奎,陈建平.煤热压实验成熟度的地质标定[J].天然气地球科学,2018,29(1):96-102.
[20]Huo Zhipeng,Pang Xiongqi,Jiang Tao.Discussion on the bottom line of hydrocarbon generation of carbonate source rocks in Tarim Basin[J].Natural Gas Geoscience,2014,25(9):1403-1415.霍志鹏,庞雄奇,姜涛.塔里木盆地碳酸盐岩层系烃源岩生烃底限探讨[J].天然气地球科学,2014,25(9):1403-1415.
[2]Gao Yuan,Zou Yanrong,Peng Ping’an.Discussion on the effectiveness of 13C NMR aromaticity as a maturity indicator[J].Geochimica,2018,47(1):102-110.高苑,邹艳荣,彭平安.核磁共振芳碳率作为成熟度指标的有效性讨论[J].地球化学,2018,47(1):102-110.
[3]Ye Danian.Structural Optical Mineralogy[M].Beijing:Geological Publishing House,1988:92-103.叶大年.结构光性矿物学[M].北京:地质出版社,1988:92-103.
[4]Armagnac C,Bucci J,Kendall G S C,et al.Estimating the thickness of sediment removed at an unconformity using vitrinite reflectance data[M]//Naeser N D,McCulloh T H.Thermal History of Sedimentary Basins.New York:Springer,1989:217-238.
[5]Zeng Fangang,Cheng Keming.The method of studying Lower Paleozoic marine carbonate kerogen maturity[J].Earth Science Frontiers,2000,7(8):249-255.曾凡刚,程克明.下古生界海相碳酸盐岩干酪根成熟度研究方法[J].地学前缘,2000,7(8):249-255.
[6]Shuai Qin,Huang Ruicheng,Gao Qiang,et al.Research development of analytical techniques for shale gas[J].Rock and Mineral Analysis,2012,31(6):931-938.帅琴,黄瑞成,高强,等.页岩气实验测试技术现状与研究进展[J].岩矿测试,2012,31(6):931-938.
[7]Tissot B P.Thermal history of sedimentary basins,maturation indices,and kinetics of oil and gas generation[J].AAPG Bulletin,1987,71(12):1445-66.
[8]Mackenzie A S,Hoffmann C F,Maxwell J R.Molecular parameters of maturation in the Toarcian shales,Paris Basin,France-Ⅲ.Changes in aromatic steroid hydrocarbons[J].Geochimica et Cosmochimica Acta,1981,45(8):1345-1355.
[9]Zhao Lei.Biomarker maturity index[J].Qinghai Shiyou,1992,10(3):43-48.赵磊.生物标志物成熟度指标[J].青海石油,1992,10(3):43-48.
[10]Zhang Jinchuan,Yang Chao,Chen Qian,et al.Deposition and distribution of potential shales in China[J].Earth Science Frontiers,2016,23(1):74-86.张金川,杨超,陈前,等.中国潜质页岩形成和分布[J].地学前缘,2016,23(1):74-86.
[11]Wang Yang.An overview on the maturation indicators of organic matter[EB/OL].Beijing:Sciencepaper Online[2008-04-15].http://www.paper.edu.cn/releasepaper/content/200804-531.汪洋.关于有机质成熟度指标的评述[EB/OL].北京:中国科技论文在线[2008-04-15].http://www.paper.edu.cn/releasepaper/content/200804-531.
[12]Tissot B P,Welte D H.Petroleum Formation and Occurrence[M].New York:Springer-Verlag,1984.
[13]Basking D K.Evaluation of thermal maturity and hydrocarbon generation potential of source rocks by kerogen H/C ratio[J].Liu Quanyou,Translation.Natural Gas Geoscience,2002,13(5):41-49.Basking D K.利用干酪根H/C比评价烃源岩热成熟度与生烃潜力[J].刘全有译.天然气地球科学,2002,13(5):41-49.
[14]Yi Junjie,Tang Shuhuan,Zhang Songhang.Geochemical characteristics of coal rocks in the hydrous thermal simulation experiment of Beizao Coal Mine[J].Science Technology and Engineering,2015,15(15):118-122.衣骏杰,唐书恒,张松航.北皂煤矿煤岩含水热模拟产物地球化学特征[J].科学技术与工程,2015,15(15):118-122.
[15]Ye Jinhua,Zhu Meiqian,Ding Xiaochen,et al.Study on the preparation of kerogen[J].Petroleum Geology&Experiment,1983,(4):84-89.叶金华,朱美茜,丁晓晨,等.干酪根制备方法的研究[J].石油实验地质,1983(4):84-89.
[16]Hu Xiong,Li Yangbing,Lai Jianbin,et al.Measurement of oxygen in kerogen by the vario micro cube element analyzer[J].Chemical Industry Times,2010,24(4):42-45.胡雄,李洋冰,来建宾,等.用Vario micro cube元素分析仪测定干酪根样品中的氧元素[J].化工时刊,2010,24(4):42-45.
[17]Zhao Junfeng,Liu Chiyang,Wang Xiaomei.The factors influencing the measurement results of vitrinite reflectance[J].Coal Geology&Exploration,2004,32(6):15-18.赵俊峰,刘池洋,王晓梅.镜质体反射率测定结果的影响因素[J].煤田地质与勘探.2004,32(6):15-18.
[18]Tissot B P,Welte D H.Petroleum Formation and Occurrence[M].Berlin,Heidelberg:Springer,1984:1-643.
[19]Chen Ruiyin,Mi Jingkui,Chen Jianping.Maturity of coal-derived hydrocarbon in pyrolysis experiments[J].Natural Gas Geoscience,2018,29(1):96-102.陈瑞银,米敬奎,陈建平.煤热压实验成熟度的地质标定[J].天然气地球科学,2018,29(1):96-102.
[20]Huo Zhipeng,Pang Xiongqi,Jiang Tao.Discussion on the bottom line of hydrocarbon generation of carbonate source rocks in Tarim Basin[J].Natural Gas Geoscience,2014,25(9):1403-1415.霍志鹏,庞雄奇,姜涛.塔里木盆地碳酸盐岩层系烃源岩生烃底限探讨[J].天然气地球科学,2014,25(9):1403-1415.