珠江口盆地白云凹陷储层沥青成因及其对油藏调整改造的启示
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摘要
在珠江口盆地白云凹陷多个层系都发现了储层沥青。储层沥青丰度自上部的珠海组、珠江组至深部的恩平组、文昌组逐渐增加。储层沥青在物性较好的粗粒砂岩中多为零星状出现,而在细粒的粉砂岩和泥岩中主要呈脉状分布而且含量明显增加。几乎所有的储层沥青均没有显示出明显的各向异性,而且沥青反射率均小于2. 0%,表明高温热裂解不是储层沥青形成的主要原因。沥青抽提物的分子地球化学组成特征显示,白云凹陷储层沥青抽提物中缺乏25-降霍烷系列,色谱基线没有明显的"UCM"鼓包、单井地层埋藏史显示储层也未遭受大幅度的抬升剥蚀,因此储层沥青也非生物降解成因。结合地质背景和油气藏特征分析认为,白云凹陷储层沥青的成因为:恩平组-文昌组烃源岩早期生成的原油聚集成藏以后,深部主要遭受了后期天然气的气洗作用。不同层位烃源岩、储层热演化的时间差异是导致白云凹陷油气藏发生调整,并转变为轻质油、挥发油等特殊油藏类型的重要原因。
Reservoir bitumen has been discovered in multiple Paleogene series of strata in the Baiyun Sag,Pearl River Mouth Basin. The abundance of reservoir bitumen gradually increases from the shallower Zhuhai and Zhujiang formations to deeply buried Enping and Wenchang Formations. The reservoir bitumen only sporadically occurs in coarse-grained sandstones with better permeability and porosity,while occurs in siltstones and mudstones in the form of veins. Almost all reservoir bitumen samples do not show apparent anisotropy with bitumen reflectance lower than 2. 0%,suggesting that the reservoir bitumen in the Baiyun Sag doesn't mainly result from high-temperature cracking. All bitumen extracts lack 25-norhopane series according to the analysis of molecular geochemical composition. No gas chromatogram base-line"hump"was discovered in all saturated hydrocarbon of reservoir bitumen. The reconstructed burial history of representative individual wells shows that the reservoir strata have not experienced large-scale uplifting and denudation. Therefore,the reservoir bitumen in the Baiyun Sag is not of biodegradation origin. Based on the analyses of the geological setting and characteristics of oil and gas reservoirs,the origin of reservoir bitumen could be attributed to later"gas washing"for deeply buried hydrocarbon-accumulation generated by source rocks of Enping and Wenchang Formations during the early thermal maturity stage. The time differences of thermal evolution for source rocks and reservoirs of various stratigraphic horizons leads to the adjustment and altering of oil and gas reservoirs in the Baiyun Sag,subsequently resulting in the formation of light and volatile oil reservoirs.
Reservoir bitumen has been discovered in multiple Paleogene series of strata in the Baiyun Sag,Pearl River Mouth Basin. The abundance of reservoir bitumen gradually increases from the shallower Zhuhai and Zhujiang formations to deeply buried Enping and Wenchang Formations. The reservoir bitumen only sporadically occurs in coarse-grained sandstones with better permeability and porosity,while occurs in siltstones and mudstones in the form of veins. Almost all reservoir bitumen samples do not show apparent anisotropy with bitumen reflectance lower than 2. 0%,suggesting that the reservoir bitumen in the Baiyun Sag doesn't mainly result from high-temperature cracking. All bitumen extracts lack 25-norhopane series according to the analysis of molecular geochemical composition. No gas chromatogram base-line"hump"was discovered in all saturated hydrocarbon of reservoir bitumen. The reconstructed burial history of representative individual wells shows that the reservoir strata have not experienced large-scale uplifting and denudation. Therefore,the reservoir bitumen in the Baiyun Sag is not of biodegradation origin. Based on the analyses of the geological setting and characteristics of oil and gas reservoirs,the origin of reservoir bitumen could be attributed to later"gas washing"for deeply buried hydrocarbon-accumulation generated by source rocks of Enping and Wenchang Formations during the early thermal maturity stage. The time differences of thermal evolution for source rocks and reservoirs of various stratigraphic horizons leads to the adjustment and altering of oil and gas reservoirs in the Baiyun Sag,subsequently resulting in the formation of light and volatile oil reservoirs.
引文
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[14]胡守志,付晓文,王廷栋,等.储层中的沥青沉淀带及其对油气勘探的意义[J].天然气地球科学,2007,18(1):99-103.Hu Shouzhi,Fu Xiaowen,Wang Tingdong,et al. Bitumen-sealed belt in reservoirs and its implication to petroleum exploration[J]. Natural Gas Geoscience,2007,18(1):99-103.
[15]吴景富,杨树春,张功成,等.南海北部深水区盆地热历史及烃源岩热演化研究[J].地球物理学报,2013,56(1):170-180.Wu Jingfu,Yang Shuchun,Zhang Gongcheng,et al. Geothermal history and themal evolution of the source rocks in the deep-water area of the northern South China Sea[J]. Chinese Journal of Geophysics,2013,56(1):170-180.
[16]杨海长,陈莹,纪沫,等.珠江口盆地深水区域构造演化差异性与油气勘探意义[J].中国石油勘探,2017,22(6):59-67.Yang Haichang,Chen Ying,Ji Mo,et al. Structural evolution difference and the significance for oil and gas exploration in the deep water area of the Pearl River Mouth Basin[J]. China Petroleum Exploration,2017,22(6):59-67.
[17]刘岩,钟宁宁,田永晶,等.中国最老古油藏—中元古界下马岭组沥青砂岩古油藏[J].石油勘探与开发,2011,38(4):503-512.Liu Yan,Zhong Ningning,Tian Yongjing,et al. The oldest oil accumulation in China:Meso-proterozoic Xiamaling Formation bituminous sandstone reservoirs[J]. Petroleum Exploration and Development,2011,38(4):503-512.
[18]秦建中,付小东,刘效曾.四川盆地东北部气田海相碳酸盐岩储层固体沥青研究[J].地质学报,2007,(8):1065-1071,1161.Qin Jianzhong,Fu Xiaodong,Liu Xiaozeng. Solid bitumens in the marine carbonate reservoir of gas field in the northeast area of the Sichuan Basin[J]. Acta Geologica Sinica,2007,81(8):1065-1071,1161.
[19]田兴旺,胡国艺,李伟,等.四川盆地乐山—龙女寺古隆起地区震旦系储层沥青地球化学特征及意义[J].天然气地球科学,2013,24(5):982-990.Tian Xingwang,Hu Guoyi,Li Wei,et al. Geochemical characteristics and significance of sinian reservoir bitumen in Leshan-Longnvsi paleo-uplift area,Sichun Basin[J]. Natural Gas Geoscience,2013,24(5):982-990.
[20] Waples D W. The kinetics of in-reservoir oil destruction and gas formation:Constraints from experimental and empirical data,and from thermodynamics[J]. Organic Geochemistry,2000,31(6):553-575.
[21] Yang C,Ni Z,Li M,et al. Pyrobitumen in south china:Organic petrology,chemical composition and geological significance[J]. International Journal of Coal Geology,2018,188:51-63.
[22]王铁冠,钟宁宁,侯读杰,等.低熟油气形成机理与分析[M].石油工业出版社,1995.Wang Tieguan,Zhong NingNing,Hou Dujie,et al. Formation mechanism and analysis of low-mature oil and gas[M]. Petroleum Industry Press,1995.
[23] Lewan M D,Spiro B,Illich H,et al. Evaluation of petroleum generation by hydrous pyrolysis experimentation and discussion[J]. Philosophical Transactions of the Royal Society of London,1985,315(1531):123-34.
[24]卢双舫.油气地球化学[M].石油工业出版社,2008.Lu Shuangfang. Petroleum geochemistry[M]. Petroleum Industry Press,2008.
[25] Losh S,Cathles L. Phase fractionation and oil-condensate mass balance in the South Marsh Island Block 208-239 area,offshore Louisiana[J]. Marine and Petroleum Geology,2010,27(2):467-475.
[26]卓勤功,赵孟军,谢会文,等.库车前陆盆地大北地区储层沥青与油气运聚关系[J].石油实验地质,2011,33(2):193-196.Zhuo Qinggong,Zhao Mengjun,Xie Hui wen,et al. Relationship between reser Voir bitumen and hydrocarbon migration in Dabei region,Kuqa Foreland Basin[J]. Petroleum Geology&Experiment,2011,33(2):193-196.
[27]张斌,黄凌,吴英,等.强烈气洗作用导致原油成分变化的定量计算:以库车坳陷天然气藏为例[J].地学前缘,2010,17(4):270-279.Zhang Bin,Huang Ling,Wu Ying,et al. Quantitative evaluation of crude oil composition changes caused by strong gas washing:A case study of natural gas pool in Kuqa Depression[J]. Earth Science Frontiers,2010,17(4):270-279.
[28] Yang C P,geng A S,Liao Z W,et al. Quantitative assessment of gas washing of oils in the Tazhong area of the Tarim Basin,Northwest China[J]. Science in China,2009,52(1):12-21.
[29]陈世加,姚泾利,路俊刚,等.储层沥青成因及其对油气运聚的影响—以鄂尔多斯盆地华庆地区长8油层组1砂组为例[J].石油与天然气地质,2012,33(1):37-44.Chen Shijia,Yao Jingli,Lu Jungang,et al. Reservoir bitumen genesis and its impacts on hydrocarbon migration and accumulation:A case study from Chang 81 of Yangchang Fomation in Huaqing area,the Ordos Basin[J]. Oil&Gas Geology,2012,33(1):37-44.
[30]陈涛,侯读杰,米巨磊,等.白云凹陷原油气洗作用[J].东北石油大学学报,2015,390(3):60-66.Chen Tao,Hou Dujie,Mi Julei,et al. Study on gas washing of crude oils in Baiyun sag[J]. Journal of Northeast Petroleum University,2015,39(3):60-66.
[31] Liu Q,Zhu D,Jin Z,et al. Coupled alteration of hydrothermal fluids and thermal sulfate reduction(tsr)in ancient dolomite reservoirs-an example from sinian dengying formation in sichuan basin,southern china[J]. Precambrian Research. 2016,285:39-57.
[32] Li Y,Jiang Z,Jiang S,et al. Heat flow and thermal evolution of a passive continental margin from shelf to slope-a case study on the Pearl River Mouth Basin,Northern South China Sea[J]. Journal of Asian Earth Sciences,2017,doi. org/10. 1016/j. jseaes. 2017. 12. 011
[33] Tang X,Yang S,Hu S. Thermal-history reconstruction of the Baiyun Sag in the deep-water area of the Pearl River Mouth Basin,northern South China Sea[J]. Frontiers of Earth Science,2018,12(3):532-544.
[2]赵中贤,周蒂,廖杰.珠江口盆地第三纪古地理及沉积演化[J].热带海洋学报,2009,28(6):52-60.Zhao Zhongxian,Zhou Di,Liao Jie. Tertiary paleogeography and depositional evolution in the Pearl River Mouth Basin of the northern South China Sea[J]. Journal of Tropical Oceanography,2009,28(6):52-60.
[3] Jacob H. Classification,structure,genesis and practical importance of natural solid oil bitumen(“migrabitumen”)[J]. International Journal of Coal Geology,1989,11(1):65-79.
[4] Lomando A J. The influence of solid reservoir bitumen on reservoir quality[J]. AAPG Bulletin,1992,76(8):1137-1152.
[5] Schoenherr J,Littke R,Urai J L,et al. Polyphase thermal evolution in the infra-cambrian ara group(south oman salt basin)as deduced by maturity of solid reservoir bitumen[J]. Organic Geochemistry,2007,38(8):1293-1318.
[6] Barton D. Evolution of gulf coast crude oil[J]. AAPG Bulletin,1937,(7):914-946.
[7] Landis C R,Casta1o J R. Maturation and bulk chemical properties of a suite of solid hydrocarbons[J]. Organic Geochemistry,1995,22(1):137-149.
[8] Gentzis T,Goodarzi F. A review of the use of bitumen in hydrocarbon exploration with examples from melville island,arctic canada[J].Rocky Mountain,1990,23-36.
[9] Milner C W D. Petroleum transformations in reservoirs[J]. Journal of Geochemical Exploration,1977,7(2):101-153.
[10] Rogers M A,Mcalary J D,Bailey N J L. Significance of reservoir bitumens to thermal-maturation studies,western canada basin[J]. AAPG Bulletin,1974,58(9):1806-1824.
[11] Mcauliffe C. Solubility in water of paraffin,cycloparaffin,olefin,acetylene,cycloolefin,and aromatic hydrocarbons[J]. Journal of Physical Chemistry,1966,70(4):1267-1275.
[12] Price LC. Crude oil degradation as an explanation of the depth rule[J]. Chemical Geology,1980,28(3):1-30.
[13]凡元芳.储层沥青的研究进展及存在问题[J].石油地质与工程,2009,23(6):35-38.Fang Yuanfang. Advances and main problems in reservoir bitumen research[J]. Petroleum Geology and Engineering,2009,23(6):35-38.
[14]胡守志,付晓文,王廷栋,等.储层中的沥青沉淀带及其对油气勘探的意义[J].天然气地球科学,2007,18(1):99-103.Hu Shouzhi,Fu Xiaowen,Wang Tingdong,et al. Bitumen-sealed belt in reservoirs and its implication to petroleum exploration[J]. Natural Gas Geoscience,2007,18(1):99-103.
[15]吴景富,杨树春,张功成,等.南海北部深水区盆地热历史及烃源岩热演化研究[J].地球物理学报,2013,56(1):170-180.Wu Jingfu,Yang Shuchun,Zhang Gongcheng,et al. Geothermal history and themal evolution of the source rocks in the deep-water area of the northern South China Sea[J]. Chinese Journal of Geophysics,2013,56(1):170-180.
[16]杨海长,陈莹,纪沫,等.珠江口盆地深水区域构造演化差异性与油气勘探意义[J].中国石油勘探,2017,22(6):59-67.Yang Haichang,Chen Ying,Ji Mo,et al. Structural evolution difference and the significance for oil and gas exploration in the deep water area of the Pearl River Mouth Basin[J]. China Petroleum Exploration,2017,22(6):59-67.
[17]刘岩,钟宁宁,田永晶,等.中国最老古油藏—中元古界下马岭组沥青砂岩古油藏[J].石油勘探与开发,2011,38(4):503-512.Liu Yan,Zhong Ningning,Tian Yongjing,et al. The oldest oil accumulation in China:Meso-proterozoic Xiamaling Formation bituminous sandstone reservoirs[J]. Petroleum Exploration and Development,2011,38(4):503-512.
[18]秦建中,付小东,刘效曾.四川盆地东北部气田海相碳酸盐岩储层固体沥青研究[J].地质学报,2007,(8):1065-1071,1161.Qin Jianzhong,Fu Xiaodong,Liu Xiaozeng. Solid bitumens in the marine carbonate reservoir of gas field in the northeast area of the Sichuan Basin[J]. Acta Geologica Sinica,2007,81(8):1065-1071,1161.
[19]田兴旺,胡国艺,李伟,等.四川盆地乐山—龙女寺古隆起地区震旦系储层沥青地球化学特征及意义[J].天然气地球科学,2013,24(5):982-990.Tian Xingwang,Hu Guoyi,Li Wei,et al. Geochemical characteristics and significance of sinian reservoir bitumen in Leshan-Longnvsi paleo-uplift area,Sichun Basin[J]. Natural Gas Geoscience,2013,24(5):982-990.
[20] Waples D W. The kinetics of in-reservoir oil destruction and gas formation:Constraints from experimental and empirical data,and from thermodynamics[J]. Organic Geochemistry,2000,31(6):553-575.
[21] Yang C,Ni Z,Li M,et al. Pyrobitumen in south china:Organic petrology,chemical composition and geological significance[J]. International Journal of Coal Geology,2018,188:51-63.
[22]王铁冠,钟宁宁,侯读杰,等.低熟油气形成机理与分析[M].石油工业出版社,1995.Wang Tieguan,Zhong NingNing,Hou Dujie,et al. Formation mechanism and analysis of low-mature oil and gas[M]. Petroleum Industry Press,1995.
[23] Lewan M D,Spiro B,Illich H,et al. Evaluation of petroleum generation by hydrous pyrolysis experimentation and discussion[J]. Philosophical Transactions of the Royal Society of London,1985,315(1531):123-34.
[24]卢双舫.油气地球化学[M].石油工业出版社,2008.Lu Shuangfang. Petroleum geochemistry[M]. Petroleum Industry Press,2008.
[25] Losh S,Cathles L. Phase fractionation and oil-condensate mass balance in the South Marsh Island Block 208-239 area,offshore Louisiana[J]. Marine and Petroleum Geology,2010,27(2):467-475.
[26]卓勤功,赵孟军,谢会文,等.库车前陆盆地大北地区储层沥青与油气运聚关系[J].石油实验地质,2011,33(2):193-196.Zhuo Qinggong,Zhao Mengjun,Xie Hui wen,et al. Relationship between reser Voir bitumen and hydrocarbon migration in Dabei region,Kuqa Foreland Basin[J]. Petroleum Geology&Experiment,2011,33(2):193-196.
[27]张斌,黄凌,吴英,等.强烈气洗作用导致原油成分变化的定量计算:以库车坳陷天然气藏为例[J].地学前缘,2010,17(4):270-279.Zhang Bin,Huang Ling,Wu Ying,et al. Quantitative evaluation of crude oil composition changes caused by strong gas washing:A case study of natural gas pool in Kuqa Depression[J]. Earth Science Frontiers,2010,17(4):270-279.
[28] Yang C P,geng A S,Liao Z W,et al. Quantitative assessment of gas washing of oils in the Tazhong area of the Tarim Basin,Northwest China[J]. Science in China,2009,52(1):12-21.
[29]陈世加,姚泾利,路俊刚,等.储层沥青成因及其对油气运聚的影响—以鄂尔多斯盆地华庆地区长8油层组1砂组为例[J].石油与天然气地质,2012,33(1):37-44.Chen Shijia,Yao Jingli,Lu Jungang,et al. Reservoir bitumen genesis and its impacts on hydrocarbon migration and accumulation:A case study from Chang 81 of Yangchang Fomation in Huaqing area,the Ordos Basin[J]. Oil&Gas Geology,2012,33(1):37-44.
[30]陈涛,侯读杰,米巨磊,等.白云凹陷原油气洗作用[J].东北石油大学学报,2015,390(3):60-66.Chen Tao,Hou Dujie,Mi Julei,et al. Study on gas washing of crude oils in Baiyun sag[J]. Journal of Northeast Petroleum University,2015,39(3):60-66.
[31] Liu Q,Zhu D,Jin Z,et al. Coupled alteration of hydrothermal fluids and thermal sulfate reduction(tsr)in ancient dolomite reservoirs-an example from sinian dengying formation in sichuan basin,southern china[J]. Precambrian Research. 2016,285:39-57.
[32] Li Y,Jiang Z,Jiang S,et al. Heat flow and thermal evolution of a passive continental margin from shelf to slope-a case study on the Pearl River Mouth Basin,Northern South China Sea[J]. Journal of Asian Earth Sciences,2017,doi. org/10. 1016/j. jseaes. 2017. 12. 011
[33] Tang X,Yang S,Hu S. Thermal-history reconstruction of the Baiyun Sag in the deep-water area of the Pearl River Mouth Basin,northern South China Sea[J]. Frontiers of Earth Science,2018,12(3):532-544.
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