湘西北地区下寒武统牛蹄塘组页岩有机地球化学与矿物组成特征
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摘要
文章以湘西北地区下寒武统牛蹄塘组页岩为研究对象,分析其有机地球化学及无机矿物特征,重点对其烃源岩生物标志化合物特征进行分析。结果表明:该套页岩残余有机碳(TOC)含量高、氯仿沥青"A"含量低、生烃潜量"S_1+S_2"较小,镜质组反射率R_o在2.3%～3.19%之间,达到了过成熟阶段,以生成干气为主。分子生物标志化合物结果显示正构烷烃呈双峰型,碳数大于C_(22)的中—高碳数烃占优势;Pr/Ph平均值为0.31,植烷优势明显,指示强还原的海相沉积环境;萜烷丰度顺序为五环三萜烷>三环萜烷>四环萜烷,γ-环蜡烷与C_(30)霍烷的比值普遍大于0.3,指示其沉积母质以浮游生物及海洋性自养菌为主,含有部分藻类;Ts/(Ts+Tm)在0.35～0.38之间,与镜质组反射率对成熟度的检测结果相互印证;规则甾烷C_(27)>C_(29)>C_(28),指示其母质来源以浅海生物来源为主,所有样品中均检测出孕甾烷、升孕甾烷、重排甾烷及4-甲基甾烷,表明其经历过微生物降解作用。全岩矿物组分分析显示该套页岩具备较好的开发物性条件和较强的吸附性能。综合以上分析结果,提出研究区牛蹄塘组页岩具备较好的页岩气成烃成藏的物质条件,并为该区深入开展页岩气勘探目标区优选奠定了很好的工作基础。
The article aims to analyze the organic geochemistry and inorganic mineral characteristics of the Lower Cambrian Niutitang Formation shale in northwestern Hunan Province. The main research methods include carbon-sulfur measurement method, rock pyrolysis method, chloroform asphalt "A" measurement method, clay mineral, and whole rock X-ray diffraction analysis method. The results show that the content of TOC in the Niutitang Formation is high, the content of "A" in chloroform asphalt is low, and the potential of generating hydrocarbon "S1+S2" is low. Most of the vitrinite reflectances Ro range from 2.3% to 3.19%, which have reached the mature stage and mainly generate dry gas. The results of biomarkers show that the n-alkane presents bimodal pattern and the medium-and high-carbon number hydrocarbons with carbon number more than C_(22) are dominant. With Pr/Ph average value of 0.31, the advantage of phytate is obvious, indicating the strong reduced marine sedimentary environment. The right angle diagram of Pr/nC_(17) and Ph/nC_(18) shows that the organic matter types of shale are mainly type I and II1; The terpene abundance order is pentacyclic triterpeneane>tricyclic terpane>tetracyclic terpene. The ratio of γ-alkane to C_(30) Hopane is generally greater than 0.3, indicating that its sedimentary parent materials are dominated by plankton and marine autotrophic bacteria, with part of algae; Ts/(Ts+Tm) range from 0.53 to 0.60, which is consistent with the detection results of vitrinite reflectance on maturity. The mass chromatogram of saturated hydrocarbon m/z 217 is C_(27)>C_(29)>C_(28) and the ratio of C_(27)/C_(29) is more than 1, indicating that its parent materials are dominated by the shallow sea creatures. Pregnane, homo-pregnane, diasterane, and 4-methyl sterane were detected in all samples, indicating that they had undergone microbial degradation. Based on the above analysis results, it is proposed that shales of the Niutitang Formation in the study area have good material conditions for shale gas hydrocarbon accumulation. This research work has laid a good working foundation to carry out the shale gas exploration in the target area.
The article aims to analyze the organic geochemistry and inorganic mineral characteristics of the Lower Cambrian Niutitang Formation shale in northwestern Hunan Province. The main research methods include carbon-sulfur measurement method, rock pyrolysis method, chloroform asphalt "A" measurement method, clay mineral, and whole rock X-ray diffraction analysis method. The results show that the content of TOC in the Niutitang Formation is high, the content of "A" in chloroform asphalt is low, and the potential of generating hydrocarbon "S1+S2" is low. Most of the vitrinite reflectances Ro range from 2.3% to 3.19%, which have reached the mature stage and mainly generate dry gas. The results of biomarkers show that the n-alkane presents bimodal pattern and the medium-and high-carbon number hydrocarbons with carbon number more than C_(22) are dominant. With Pr/Ph average value of 0.31, the advantage of phytate is obvious, indicating the strong reduced marine sedimentary environment. The right angle diagram of Pr/nC_(17) and Ph/nC_(18) shows that the organic matter types of shale are mainly type I and II1; The terpene abundance order is pentacyclic triterpeneane>tricyclic terpane>tetracyclic terpene. The ratio of γ-alkane to C_(30) Hopane is generally greater than 0.3, indicating that its sedimentary parent materials are dominated by plankton and marine autotrophic bacteria, with part of algae; Ts/(Ts+Tm) range from 0.53 to 0.60, which is consistent with the detection results of vitrinite reflectance on maturity. The mass chromatogram of saturated hydrocarbon m/z 217 is C_(27)>C_(29)>C_(28) and the ratio of C_(27)/C_(29) is more than 1, indicating that its parent materials are dominated by the shallow sea creatures. Pregnane, homo-pregnane, diasterane, and 4-methyl sterane were detected in all samples, indicating that they had undergone microbial degradation. Based on the above analysis results, it is proposed that shales of the Niutitang Formation in the study area have good material conditions for shale gas hydrocarbon accumulation. This research work has laid a good working foundation to carry out the shale gas exploration in the target area.
引文
[1] 刘洪林,王红岩,刘人和,等.中国页岩气资源及其勘探潜力分析[J].地质学报,2010,84(9):1374-1378.LIU Honglin,WANG Hongyan,LIU Renhe,et al.China shale gas resources and prospect potential[J].Acta Geologica Sinica,2010,84(9):1374-1378.(in Chinese with English abstract)
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[4] 王光凯,焦鹏.湘西北地区下寒武统牛蹄塘组页岩气成藏条件[J].能源与节能,2013,(1):35-36,51.WANG Guangkai,JIAO Peng.Accumulation condition of Niutitang Formation of lower Cambrian shale gas resource in northwestern Hunan Region[J].Energy and Energy Conservation,2013,(1):35-36,51.(in Chinese with English abstract)
[5] 肖正辉,杨荣丰,冯涛,等.湘西北下寒武统牛蹄塘组页岩气成藏条件及其勘探潜力分析[J].湖南科技大学学报(自然科学版),2012,27(1):50-54.XIAO Zhenghui,YANG Rongfeng,FENG Tao,et al.Reservoir-forming conditions and exploration potential of shale gas in Lower Cambrian Niutitang Formation,Northwestern Hunan[J].Journal of Hunan University of Science & Technology (Natural Science Edition),2012,27(1):50-54.(in Chinese with English abstract)
[6] 马超,宁宁,王红岩,等.湘西—黔东地区牛蹄塘组页岩气勘探前景[J].特种油气藏,2014,21(1):38-41.MA Chao,NING Ning,WANG Hongyan,et al.Exploration prospect of the lower Cambrian Niutitang Formation shale gas in Xiangxi Qiandong area[J].Special Oil & Gas Reservoirs,2014,21(1):38-41.(in Chinese)
[7] 张琳婷,郭建华,焦鹏,等.湘西北地区牛蹄塘组页岩气有利地质条件及成藏区带优选[J].中南大学学报(自然科学版),2015,46(5):1715-1722.ZHANG Linting,GUO Jianhua,JIAO Peng,et al.Geological conditions and favorable exploration zones of shale gas in Niutitang Formation at northwest Hunan[J].Journal of Central South University (Science and Technology),2015,46(5):1715-1722.(in Chinese with English abstract)
[8] 张慧,吴静,晋香兰,等.牛蹄塘组页岩矿物的成因类型及其地质指示意义[J].煤田地质与勘探,2018,46(2):61-67.ZHANG Hui,WU Jing,JIN Xianglan,et al.The genetic type and its geological indication significance of shale minerals in Niutitang Formation[J].Coal Geology & Exploration,2018,46(2):61-67.(in Chinese with English abstract)
[9] 肖正辉,王朝晖,杨荣丰,等.湘西北下寒武统牛蹄塘组页岩气储集条件研究[J].地质学报,2013,87(10):1612-1623.XIAO Zhenghui,WANG Zhaohui,YANG Rongfeng,et al.Reservoir conditions of shale gas in the lower Cambrian Niutitang Formation,northwestern Hunan[J].Acta Geologica Sinica,2013,87(10):1612-1623.(in Chinese with English abstract)
[10] JACOB H.Disperse solid bitumens as an indicator for migration and maturity in prospecting for oil and gas[J].Erdol and Kohgle,1985,38(3):365.
[11] 丰国秀,陈盛吉.岩石中沥青反射率与镜质体反射率之间的关系[J].天然气工业,1988,8(3):20-25.FENG Guoxiu,CHEN Shengji.Relationship between the reflectance of bitumen and vitrinite in rock[J].Natural Gas Industry,1988,8(3):20-25.(in Chinese with English abstract)
[12] 刘德汉,周中毅,贾蓉芬,等.碳酸岩生油岩中沥青变质程度和沥青热变质实验[J].地球化学,1982,(3):237-243.LIU Dehan,ZHOU Zhongyi,JIA Rongfen,et al.The extent of asphalt alteration in oil-generating carbonate rocks and thermal alteration experiments on asphalt[J].Geochimica,1982,(3):237-243.(in Chinese with English abstract)
[13] 周磊,王宗秀,李会军,等.川东—武陵山地区下寒武统牛蹄塘组页岩有机质富集模式[J].地质力学学报,2018,24(5):617-626.ZHOU Lei,WANG Zongxiu,LI Huijun,et al.Accumulation pattern of organic matter in shales of the lower Cambrian Niutitang formation,Chuandong-Wulingshan area[J].Journal of Geomechanics,2018,24(5):617-626.(in Chinese with English abstract)
[14] WANG J G,CHEN D Z,WANG D,et al.Petrology and geochemistry of chert on the marginal zone of Yangtze Platform,western Hunan,South China,during the Ediacaran-Cambrian transition[J].Sedimentology,2012,59(3):809-829.
[15] CHEN D Z,WANG J G,QING H R,et al.Hydrothermal venting activities in the Early Cambrian,South China:Petrological,geochronological and stable isotopic constraints[J].Chemical Geology,2009,258(3-4):168-181.
[16] 游先军,戴塔根,息朝庄,等.湘西北下寒武统黑色岩系地球化学特征[J].大地构造与成矿学,2009,33(2):304-312.YOU Xianjun,DAI Tagen,XI Chaozhuang,et al.Geochemical characteristics of lower Cambrian black rock series in northwestern Hunan,China[J].Geotectonica et Metallogenia,2009,33(2):304-312.(in Chinese with English abstract)
[17] PETERS K E,MOLDOWAN J M.Effects of source,thermal maturity,and biodegradation on the distribution and isomerization of homohopanes in petroleum[J].Organic Geochemistry,1991,17(1):47-61.
[18] PETERS K E.Petroleum tricyclic terpanes:predicted physicochemical behavior from molecular mechanics calculations[J].Organic Geochemistry,2000,31(6):497-507.
[19] 孟凡巍,周传明,燕夔,等.通过C27/C29甾烷和有机碳同位素来判断早古生代和前寒武纪的烃源岩的生物来源[J].微体古生物学报,2006,23(1):51-56.MENG Fanwei,ZHOU Chuanming,YAN Kui,et al.Biological origin of early Palaeozoic and Precambrian hydrocarbon source rocks based on C27/C29 Sterane ratio and organic carbon isotope[J].Acta Micropalaeontologica Sinica,2006,23(1):51-56.(in Chinese with English abstract)
[20] 孙涛,段毅.煤系有机质生成烃类中甾烷系列化合物地球化学特征——以高温封闭体系下热模拟实验为例[J].天然气地球科学,2011,22(6):1082-1087.SUN Tao,DUAN Yi.Geochemical characteristics of steranes of coal generated hydrocarbons:a case of high temperature and fined simulated experiment[J].Natural Gas Geoscience,2011,22(6):1082-1087.(in Chinese with English abstract)
[21] 王玉芳,翟刚毅,王劲铸,等.四川盆地及周缘龙马溪组页岩产气效果影响因素[J].地质力学学报,2017,23(4):540-547.WANG Yufang,ZHAI Gangyi,WANG Jingzhu,et al.Factors influencing gas production effectiveness of Longmaxi Formation shale in Sichuan Basin and Adjacent Areas[J].Journal of Geomechanics,2017,23(4):540-547.(in Chinese with English abstract)
[22] 熊金红,梁明亮,曹占元,等.准噶尔盆地南缘柴窝堡凹陷泥页岩地球化学和矿物学特征研究[J].地质力学学报,2017,23(4):585-593.XIONG Jinhong,LIANG Mingliang,CAO Zhanyuan,et al.The geochemical and mineralogical characteristics of Shales in Chaiwobu Depression,southern margin of Junggar Basin[J].Journal of Geomechanics,2017,23(4):585-593.(in Chinese with English abstract)
[23] 李新景,胡素云,程克明.北美裂缝性页岩气勘探开发的启示[J].石油勘探与开发,2007,34(4):392-400.LI Xinjing,HU Suyun,CHENG Keming.Suggestions from the development of fractured shale gas in North America[J].Petroleum Exploration and Development,2007,34(4):392-400.(in Chinese with English abstract)
[2] 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):288-299,308.DONG Dazhong,CHENG Keming,WANG Yuman,et al.Forming conditions and characteristics of shale gas in the Lower Paleozoic of the Upper Yangtze region,China[J].Oil & Gas Geology,2010,31(3):288-299,308.(in Chinese with English abstract)
[3] 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[J].地质通报,2011,30(2-3):349-356.LI Yanxia,LIN Juanhua,LONG Youkang,et al.Exploration prospect of gas-bearing marine mudstone-shale in Lower Palaeozoic in the central Yangtze area,China[J].Geological Bulletin of China,2011,30(2-3):349-356.(in Chinese with English abstract)
[4] 王光凯,焦鹏.湘西北地区下寒武统牛蹄塘组页岩气成藏条件[J].能源与节能,2013,(1):35-36,51.WANG Guangkai,JIAO Peng.Accumulation condition of Niutitang Formation of lower Cambrian shale gas resource in northwestern Hunan Region[J].Energy and Energy Conservation,2013,(1):35-36,51.(in Chinese with English abstract)
[5] 肖正辉,杨荣丰,冯涛,等.湘西北下寒武统牛蹄塘组页岩气成藏条件及其勘探潜力分析[J].湖南科技大学学报(自然科学版),2012,27(1):50-54.XIAO Zhenghui,YANG Rongfeng,FENG Tao,et al.Reservoir-forming conditions and exploration potential of shale gas in Lower Cambrian Niutitang Formation,Northwestern Hunan[J].Journal of Hunan University of Science & Technology (Natural Science Edition),2012,27(1):50-54.(in Chinese with English abstract)
[6] 马超,宁宁,王红岩,等.湘西—黔东地区牛蹄塘组页岩气勘探前景[J].特种油气藏,2014,21(1):38-41.MA Chao,NING Ning,WANG Hongyan,et al.Exploration prospect of the lower Cambrian Niutitang Formation shale gas in Xiangxi Qiandong area[J].Special Oil & Gas Reservoirs,2014,21(1):38-41.(in Chinese)
[7] 张琳婷,郭建华,焦鹏,等.湘西北地区牛蹄塘组页岩气有利地质条件及成藏区带优选[J].中南大学学报(自然科学版),2015,46(5):1715-1722.ZHANG Linting,GUO Jianhua,JIAO Peng,et al.Geological conditions and favorable exploration zones of shale gas in Niutitang Formation at northwest Hunan[J].Journal of Central South University (Science and Technology),2015,46(5):1715-1722.(in Chinese with English abstract)
[8] 张慧,吴静,晋香兰,等.牛蹄塘组页岩矿物的成因类型及其地质指示意义[J].煤田地质与勘探,2018,46(2):61-67.ZHANG Hui,WU Jing,JIN Xianglan,et al.The genetic type and its geological indication significance of shale minerals in Niutitang Formation[J].Coal Geology & Exploration,2018,46(2):61-67.(in Chinese with English abstract)
[9] 肖正辉,王朝晖,杨荣丰,等.湘西北下寒武统牛蹄塘组页岩气储集条件研究[J].地质学报,2013,87(10):1612-1623.XIAO Zhenghui,WANG Zhaohui,YANG Rongfeng,et al.Reservoir conditions of shale gas in the lower Cambrian Niutitang Formation,northwestern Hunan[J].Acta Geologica Sinica,2013,87(10):1612-1623.(in Chinese with English abstract)
[10] JACOB H.Disperse solid bitumens as an indicator for migration and maturity in prospecting for oil and gas[J].Erdol and Kohgle,1985,38(3):365.
[11] 丰国秀,陈盛吉.岩石中沥青反射率与镜质体反射率之间的关系[J].天然气工业,1988,8(3):20-25.FENG Guoxiu,CHEN Shengji.Relationship between the reflectance of bitumen and vitrinite in rock[J].Natural Gas Industry,1988,8(3):20-25.(in Chinese with English abstract)
[12] 刘德汉,周中毅,贾蓉芬,等.碳酸岩生油岩中沥青变质程度和沥青热变质实验[J].地球化学,1982,(3):237-243.LIU Dehan,ZHOU Zhongyi,JIA Rongfen,et al.The extent of asphalt alteration in oil-generating carbonate rocks and thermal alteration experiments on asphalt[J].Geochimica,1982,(3):237-243.(in Chinese with English abstract)
[13] 周磊,王宗秀,李会军,等.川东—武陵山地区下寒武统牛蹄塘组页岩有机质富集模式[J].地质力学学报,2018,24(5):617-626.ZHOU Lei,WANG Zongxiu,LI Huijun,et al.Accumulation pattern of organic matter in shales of the lower Cambrian Niutitang formation,Chuandong-Wulingshan area[J].Journal of Geomechanics,2018,24(5):617-626.(in Chinese with English abstract)
[14] WANG J G,CHEN D Z,WANG D,et al.Petrology and geochemistry of chert on the marginal zone of Yangtze Platform,western Hunan,South China,during the Ediacaran-Cambrian transition[J].Sedimentology,2012,59(3):809-829.
[15] CHEN D Z,WANG J G,QING H R,et al.Hydrothermal venting activities in the Early Cambrian,South China:Petrological,geochronological and stable isotopic constraints[J].Chemical Geology,2009,258(3-4):168-181.
[16] 游先军,戴塔根,息朝庄,等.湘西北下寒武统黑色岩系地球化学特征[J].大地构造与成矿学,2009,33(2):304-312.YOU Xianjun,DAI Tagen,XI Chaozhuang,et al.Geochemical characteristics of lower Cambrian black rock series in northwestern Hunan,China[J].Geotectonica et Metallogenia,2009,33(2):304-312.(in Chinese with English abstract)
[17] PETERS K E,MOLDOWAN J M.Effects of source,thermal maturity,and biodegradation on the distribution and isomerization of homohopanes in petroleum[J].Organic Geochemistry,1991,17(1):47-61.
[18] PETERS K E.Petroleum tricyclic terpanes:predicted physicochemical behavior from molecular mechanics calculations[J].Organic Geochemistry,2000,31(6):497-507.
[19] 孟凡巍,周传明,燕夔,等.通过C27/C29甾烷和有机碳同位素来判断早古生代和前寒武纪的烃源岩的生物来源[J].微体古生物学报,2006,23(1):51-56.MENG Fanwei,ZHOU Chuanming,YAN Kui,et al.Biological origin of early Palaeozoic and Precambrian hydrocarbon source rocks based on C27/C29 Sterane ratio and organic carbon isotope[J].Acta Micropalaeontologica Sinica,2006,23(1):51-56.(in Chinese with English abstract)
[20] 孙涛,段毅.煤系有机质生成烃类中甾烷系列化合物地球化学特征——以高温封闭体系下热模拟实验为例[J].天然气地球科学,2011,22(6):1082-1087.SUN Tao,DUAN Yi.Geochemical characteristics of steranes of coal generated hydrocarbons:a case of high temperature and fined simulated experiment[J].Natural Gas Geoscience,2011,22(6):1082-1087.(in Chinese with English abstract)
[21] 王玉芳,翟刚毅,王劲铸,等.四川盆地及周缘龙马溪组页岩产气效果影响因素[J].地质力学学报,2017,23(4):540-547.WANG Yufang,ZHAI Gangyi,WANG Jingzhu,et al.Factors influencing gas production effectiveness of Longmaxi Formation shale in Sichuan Basin and Adjacent Areas[J].Journal of Geomechanics,2017,23(4):540-547.(in Chinese with English abstract)
[22] 熊金红,梁明亮,曹占元,等.准噶尔盆地南缘柴窝堡凹陷泥页岩地球化学和矿物学特征研究[J].地质力学学报,2017,23(4):585-593.XIONG Jinhong,LIANG Mingliang,CAO Zhanyuan,et al.The geochemical and mineralogical characteristics of Shales in Chaiwobu Depression,southern margin of Junggar Basin[J].Journal of Geomechanics,2017,23(4):585-593.(in Chinese with English abstract)
[23] 李新景,胡素云,程克明.北美裂缝性页岩气勘探开发的启示[J].石油勘探与开发,2007,34(4):392-400.LI Xinjing,HU Suyun,CHENG Keming.Suggestions from the development of fractured shale gas in North America[J].Petroleum Exploration and Development,2007,34(4):392-400.(in Chinese with English abstract)