四川盆地北部及周缘地区震旦系灯影组二段、四段储集层特征及成因差异
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摘要
基于野外露头、钻井岩心的宏观与微观研究,结合相关地球化学分析资料,对四川盆地北部及周缘地区震旦系灯影组二、四段储集层特征及成因进行了探讨与对比。研究认为:区内灯影组二段储集层分布于地层中部,主要受丘滩复合体和表生期岩溶作用的共同控制,近顺层分布的拉长状孤立藻格架溶洞和残余"葡萄花边"洞构成其储集空间主体,其中部分空间被多期亮晶白云石半充填,未见有沥青分布,连通性较差,多属于低孔、低渗型储集层;灯影组四段储集层在地层中上部—顶部发育,受丘滩集合体和埋藏溶蚀作用控制明显,近顺层分布的藻格架溶孔、溶洞、晶间孔和晶间溶孔构成其主要储集空间,其中部分空间被较多沥青和少量石英半充填,几乎未见亮晶白云石分布,连通性相对较好,多属于中—低孔、低渗型储集层,局部为中高孔、中渗型。受丘滩复合体发育程度与溶蚀作用差异的共同影响,沿宁强—广元—剑阁—阆中一线分布的台地边缘是最有利于优质储集层发育的区带,深埋地表之下的广元—阆中一带则是今后该领域油气勘探的主要地区。
This study investigated the characteristics and genesis of reservoirs in the 2nd and 4th members of Sinian Dengying Formation in northern Sichuan and its surrounding areas, on the basis of outcrop, drilling cores and thin section observation and geochemical analysis. The reservoirs of 2nd member are distributed in the middle part of the stratum. The reservoir quality is controlled by supergene karst and the distribution of mound-shoal complex. The bedded elongated isolated algal framework solution-cave and the residual "grape-lace" cave, which are partially filled with multi-stage dolosparite, constituted the main reservoir space of the 2nd member. There is no asphalt distribution in the pores. The pore connectivity is poor, and the porosity and permeability of the reservoir is relatively low. The reservoirs of 4th member were distributed in the upper and top part of the stratum. The reservoir quality is controlled by burial dissolution and the distribution of mound-shoal complex. The bedded algal framework solution-pores or caves, intercrystalline pores and intercrystalline dissolved pores constituted the main reservoir space of the 4th member. It's partially filled with asphalt and quartz, without any dolosparite fillings in the pores and caves. The pore connectivity is good. Most of the 4th member reservoirs had medium-low porosity and low permeability, and, locally, medium-high porosity and medium permeability. Affected by the development of mound-shoal complex and heterogeneous dissolution, the platform margin along Ningqiang, Guangyuan, Jiange and Langzhong is the most favorable region for reservoir development. Deep buried Dengying Formation in the guangyuan and langzhong areas should be the most important hydrocarbon target for the future exploration.
This study investigated the characteristics and genesis of reservoirs in the 2nd and 4th members of Sinian Dengying Formation in northern Sichuan and its surrounding areas, on the basis of outcrop, drilling cores and thin section observation and geochemical analysis. The reservoirs of 2nd member are distributed in the middle part of the stratum. The reservoir quality is controlled by supergene karst and the distribution of mound-shoal complex. The bedded elongated isolated algal framework solution-cave and the residual "grape-lace" cave, which are partially filled with multi-stage dolosparite, constituted the main reservoir space of the 2nd member. There is no asphalt distribution in the pores. The pore connectivity is poor, and the porosity and permeability of the reservoir is relatively low. The reservoirs of 4th member were distributed in the upper and top part of the stratum. The reservoir quality is controlled by burial dissolution and the distribution of mound-shoal complex. The bedded algal framework solution-pores or caves, intercrystalline pores and intercrystalline dissolved pores constituted the main reservoir space of the 4th member. It's partially filled with asphalt and quartz, without any dolosparite fillings in the pores and caves. The pore connectivity is good. Most of the 4th member reservoirs had medium-low porosity and low permeability, and, locally, medium-high porosity and medium permeability. Affected by the development of mound-shoal complex and heterogeneous dissolution, the platform margin along Ningqiang, Guangyuan, Jiange and Langzhong is the most favorable region for reservoir development. Deep buried Dengying Formation in the guangyuan and langzhong areas should be the most important hydrocarbon target for the future exploration.
引文
[1]魏国齐,沈平,杨威,等.四川盆地震旦系大气田形成条件与勘探远景区[J].石油勘探与开发,2013,40(2):129-138.WEI Guoqi,SHEN Ping,YANG Wei,et al.Formation conditions and exploration prospects of Sinian large gas fields,Sichuan Basin[J].Petroleum Exploration and Development,2013,40(2):129-138.
[2]徐春春,沈平,杨跃明,等.乐山-龙女寺古隆起震旦系-下寒武统龙王庙组天然气成藏条件与富集规律[J].天然气工业,2014,34(3):1-7.XU Chunchun,SHEN Ping,YANG Yueming,et al.Accumulation conditions and enrichment patterns of natural gas in the Lower Cambrian Longwangmiao Fm reservoirs of the Leshan-Longnüsi Paleohigh,Sichuan Basin[J].Natural Gas Industry,2014,34(3):1-7.
[3]邹才能,杜金虎,徐春春,等.四川盆地震旦系-寒武系特大型气田形成分布、资源潜力及勘探发现[J].石油勘探与开发,2014,41(3):278-293.ZOU Caineng,DU Jinhu,XU Chunchun,et al.Formation,distribution,resource potential and discovery of the Sinian-Cambrian giant gas field,Sichuan Basin,SW China[J].Petroleum Exploration and Development,2014,41(3):278-293.
[4]莫静,王兴志,冷胜远,等.川中地区震旦系灯影组储层特征及其主控因素[J].中国地质,2013,40(5):1505-1514.MO Jing,WANG Xingzhi,LENG Shengyuan,et al.Reservoir characteristics and control factors of Sinian Dengying Formation in central Sichuan[J].Geology in China,2013,40(5):1505-1514.
[5]罗冰,杨跃明,罗文军,等.川中古隆起灯影组储层发育控制因素及展布[J].石油学报,2015,36(4):416-426.LUO Bing,YANG Yueming,LUO Wenjun,et al.Controlling factors and distribution of reservoir development in Dengying Formation of paleo-uplift in central Sichuan Basin[J].Acta Petrolei Sinica,2015,36(4):416-426.
[6]陈娅娜,沈安江,潘立银,等.微生物白云岩储集层特征、成因和分布:以四川盆地震旦系灯影组四段为例[J].石油勘探与开发,2017,44(5):704-715.CHEN Yana,SHEN Anjiang,Pan Liyin,et al.Origin and distribution of microbial dolomite reservoirs:A case study of 4th Member of Sinian Dengying Formation in the Sichuan Basin,SW China[J].Petroleum Exploration and Development,2017,44(5):704-715.
[7]宋金民,刘树根,李智武,等.四川盆地上震旦统灯影组微生物碳酸盐岩储层特征与主控因素[J].石油与天然气地质,2017,38(4):741-752.SONG Jinmin,LIU Shugen,Li Zhiwu,et al.Characteristics and controlling factors of microbial carbonate reservoirs in the Upper Sinian Dengying Formation in the Sichuan Basin,China[J].Oil&Gas Geology,2017,38(4):741-752.
[8]李英强,何登发,文竹.四川盆地及邻区晚震旦世古地理与构造-沉积环境演化[J].古地理学报,2013,15(2):231-245.LI Yingqiang,HE Dengfa,WEN Zhu.Palaeogeography and tectonicdepositional environment evolution of the Late Sinian in Sichuan Basin and adjacent areas[J].Journal of Palaeogeography,2013,15(2):231-245.
[9]邓胜徽,樊茹,李鑫,等.四川盆地及周缘地区震旦(埃迪卡拉)系划分与对比[J].地层学杂志,2015,39(3):239-254.DENG Shenghui,FAN Ru,LI Xin,et al.Subdivision and correlation of the Sinian(Ediacaran)system in the Sichuan Basin and its adjacent area[J].Journal of Stratigraphy,2015,39(3):239-254.
[10]魏国齐,杨威,杜金虎,等.四川盆地震旦纪-早寒武世克拉通内裂陷地质特征[J].天然气工业,2015,35(1):24-35.WEI Guoqi,YANG Wei,DU Jinhu,et al.Geological characteristics of the Sinian-Early Cambrian intracratonic rift,Sichuan Basin[J].Natural Gas Industry,2015,35(1):24-35.
[11]钟勇,李亚林,张晓斌,等.川中古隆起构造演化特征及其与早寒武世绵阳-长宁拉张槽的关系[J].成都理工大学学报(自然科学版),2014,41(6):703-712.ZHONG Yong,LI Yalin,ZHANG Xiaobin,et al.Evolution characteristics of Central Sichuan palaeouplift and its relationship with Early Cambrian Mianyang-Changning intracratonic sag[J].Journal of Chengdu University of Technology(Science&Technology Edition),2014,41(6):703-712.
[12]周进高,张建勇,邓红婴,等.四川盆地震旦系灯影组岩相古地理与沉积模式[J].天然气工业,2017,37(1):24-31.ZHOU Jingao,ZHANG Jianyong,DENG Hongying,et al.Lithofacies paleogeography and sedimentary model of Sinian Dengying Fm in the Sichuan Basin[J].Natural Gas Industry,2017,37(1):24-31.
[13]张荫本.震旦纪白云岩中的葡萄状构造成因初探[J].石油实验地质,1980,2(4):40-43.ZHANG Yinben.Origin of the grape-like texture in rocks of Sinian age[J].Petroleum Geology&Expeximent,1980,2(4):40-43.
[14]王兴志,黄继祥,侯方浩,等.四川资阳及邻区灯影组古岩溶特征与储集空间[J].矿物岩石,1996,16(2):47-54.WANG Xingzhi,HUANG Jixiang,HOU Fanghao,et al.The relations between paleokarst and reservoir porosity in Dengying Formation,Sinian of Ziyang and neighboring area,Sichuan[J].Journal of Mineralogy and Petrology,1996,16(2):47-54.
[15]施泽进,梁平,王勇,等.川东南地区灯影组葡萄石地球化学特征及成因分析[J].岩石学报,2011,27(8):2263-2271.SHI Zejin,LIANG Ping,WANG Yong,et al.Geochemical characteristics and genesis of grapestone in Sinian Dengying Formation in south-eastern Sichuan Basin[J].Acta Petrologica Sinica,2011,27(8):2263-2271.
[16]郝毅,周进高,陈旭,等.四川盆地灯影组“葡萄花边”状白云岩成因及地质意义[J].海相油气地质,2015,20(4):57-64.HAO Yi,ZHOU Jingao,CHEN Xu,et al.Genesis and geological significance of upper Sinian Dengying dolostone with grape-lace shaped cement,Sichuan Basin[J].Marine Origin Petroleum Geology,2015,20(4):57-64.
[17]王兴志,侯方浩,刘仲宣.资阳地区灯影组层状白云岩储集层研究[J].石油勘探与开发,1997,24(2):37-40.WANG Xingzhi,HOU Fanghao,LIU Zhongxuan.Stratified dolomite reservoirs in Dengying Formation of Ziyang Region[J].Petroleum Exploration and Development,1997,24(2):37-40.
[18]赵雪凤,朱光有,刘钦甫,等.深部海相碳酸盐岩储层孔隙发育的主控因素研究[J].天然气地球科学,2007,18(4):514-521.ZHAO Xuefeng,ZHU Guangyou,LIU Qinfu,et al.Main control factors of pore development in deep marine carbonate reservoirs[J].Natural Gas Geoscience,2007,18(4):514-521.
[19]JIN Z,ZHU D,HU W,et al.Mesogenetic dissolution of the middle Ordovician limestone in the Tahe oilfield of Tarim basin,NWChina[J].Marine&Petroleum Geology,2009,26(6):753-763.
[20]金振奎,余宽宏.白云岩储集层埋藏溶蚀作用特征及意义:以塔里木盆地东部下古生界为例[J].石油勘探与开发,2011,38(4):428-434.JIN Zhenkui,YU Kuanhong.Characteristics and significance of the burial dissolution of dolomite reservoirs:Taking the Lower Paleozoic in eastern Tarim Basin as an example[J].Petroleum Exploration and Development,2011,38(4):428-434.
[21]雷川,陈红汉,苏奥,等.碳酸盐岩埋藏溶蚀研究进展[J].断块油气田,2014,21(2):165-170.LEI Chuan,CHEN Honghan,SU Ao,et al.Study progress on buried dissolution in carbonate rock[J].Fault-Block Oil&Gas Field,2014,21(2):165-170.
[22]沈安江,佘敏,胡安平,等.海相碳酸盐岩埋藏溶孔规模与分布规律初探[J].天然气地球科学,2015,26(10):1823-1830.SHEN Anjiang,SHE Min,HU Anping,et al.Scale and distribution of marine carbonate burial dissolutional pores[J].Natural Gas Geoscience,2015,26(10):1823-1830
[23]MAZZULLO S J.Overview of porosity evolution in carbonate reservoirs[J].Kansas Geological Society Bulletin,2004,79:20-28.
[24]佘敏,寿建峰,沈安江,等.埋藏有机酸性流体对白云岩储层溶蚀作用的模拟实验[J].中国石油大学学报(自然科学版),2014,38(3):10-17.SHE Min,SHOU Jianfeng,SHEN Anjiang,et al.Experimental simulation of dissolution and alteration of burial organic acid fluid on dolomite reservoir[J].Journal of China University of Petroleum(Natural Science Edition),2014,38(3):10-17.
[25]宋文海.乐山-龙女寺古隆起大中型气田成藏条件研究[J].天然气工业,1996(S1):13-26.SONG Wenhai.Research on reservoir-formed conditions of largemedium gas fields of Leshan-Longnvsi palaeohigh[J].Natural Gas Industry,1996(S1):13-26.
[26]魏国齐,王志宏,李剑,等.四川盆地震旦系、寒武系烃源岩特征、资源潜力与勘探方向[J].天然气地球科学,2017,28(1):1-13.WEI Guoqi,WANG Zhihong,LI Jian,et al.Characteristics of source rocks,resource potential and exploration direction of Sinian and Cambrian in Sichuan Basin[J].Natural Gas Geoscience,2017,28(1):1-13.
[27]魏国齐,杨威,谢武仁,等.四川盆地震旦系-寒武系大气田形成条件、成藏模式与勘探方向[J].天然气地球科学,2015,26(5):785-795.WEI Guoqi,YANG Wei,XIE Wuren,et al.Formation conditions,accumulation models and exploration direction of large gas fields in Sinian-Cambrian,Sichuan Basin[J].Natural Gas Geoscience,2015,26(5):785-795.
[28]TEINTURIER S,ELIE M,PIRONON J.Oil-cracking processes evidence from synthetic petroleum inclusions[J].Journal of Geochemical Exploration,2003,78(3):421-425.
[2]徐春春,沈平,杨跃明,等.乐山-龙女寺古隆起震旦系-下寒武统龙王庙组天然气成藏条件与富集规律[J].天然气工业,2014,34(3):1-7.XU Chunchun,SHEN Ping,YANG Yueming,et al.Accumulation conditions and enrichment patterns of natural gas in the Lower Cambrian Longwangmiao Fm reservoirs of the Leshan-Longnüsi Paleohigh,Sichuan Basin[J].Natural Gas Industry,2014,34(3):1-7.
[3]邹才能,杜金虎,徐春春,等.四川盆地震旦系-寒武系特大型气田形成分布、资源潜力及勘探发现[J].石油勘探与开发,2014,41(3):278-293.ZOU Caineng,DU Jinhu,XU Chunchun,et al.Formation,distribution,resource potential and discovery of the Sinian-Cambrian giant gas field,Sichuan Basin,SW China[J].Petroleum Exploration and Development,2014,41(3):278-293.
[4]莫静,王兴志,冷胜远,等.川中地区震旦系灯影组储层特征及其主控因素[J].中国地质,2013,40(5):1505-1514.MO Jing,WANG Xingzhi,LENG Shengyuan,et al.Reservoir characteristics and control factors of Sinian Dengying Formation in central Sichuan[J].Geology in China,2013,40(5):1505-1514.
[5]罗冰,杨跃明,罗文军,等.川中古隆起灯影组储层发育控制因素及展布[J].石油学报,2015,36(4):416-426.LUO Bing,YANG Yueming,LUO Wenjun,et al.Controlling factors and distribution of reservoir development in Dengying Formation of paleo-uplift in central Sichuan Basin[J].Acta Petrolei Sinica,2015,36(4):416-426.
[6]陈娅娜,沈安江,潘立银,等.微生物白云岩储集层特征、成因和分布:以四川盆地震旦系灯影组四段为例[J].石油勘探与开发,2017,44(5):704-715.CHEN Yana,SHEN Anjiang,Pan Liyin,et al.Origin and distribution of microbial dolomite reservoirs:A case study of 4th Member of Sinian Dengying Formation in the Sichuan Basin,SW China[J].Petroleum Exploration and Development,2017,44(5):704-715.
[7]宋金民,刘树根,李智武,等.四川盆地上震旦统灯影组微生物碳酸盐岩储层特征与主控因素[J].石油与天然气地质,2017,38(4):741-752.SONG Jinmin,LIU Shugen,Li Zhiwu,et al.Characteristics and controlling factors of microbial carbonate reservoirs in the Upper Sinian Dengying Formation in the Sichuan Basin,China[J].Oil&Gas Geology,2017,38(4):741-752.
[8]李英强,何登发,文竹.四川盆地及邻区晚震旦世古地理与构造-沉积环境演化[J].古地理学报,2013,15(2):231-245.LI Yingqiang,HE Dengfa,WEN Zhu.Palaeogeography and tectonicdepositional environment evolution of the Late Sinian in Sichuan Basin and adjacent areas[J].Journal of Palaeogeography,2013,15(2):231-245.
[9]邓胜徽,樊茹,李鑫,等.四川盆地及周缘地区震旦(埃迪卡拉)系划分与对比[J].地层学杂志,2015,39(3):239-254.DENG Shenghui,FAN Ru,LI Xin,et al.Subdivision and correlation of the Sinian(Ediacaran)system in the Sichuan Basin and its adjacent area[J].Journal of Stratigraphy,2015,39(3):239-254.
[10]魏国齐,杨威,杜金虎,等.四川盆地震旦纪-早寒武世克拉通内裂陷地质特征[J].天然气工业,2015,35(1):24-35.WEI Guoqi,YANG Wei,DU Jinhu,et al.Geological characteristics of the Sinian-Early Cambrian intracratonic rift,Sichuan Basin[J].Natural Gas Industry,2015,35(1):24-35.
[11]钟勇,李亚林,张晓斌,等.川中古隆起构造演化特征及其与早寒武世绵阳-长宁拉张槽的关系[J].成都理工大学学报(自然科学版),2014,41(6):703-712.ZHONG Yong,LI Yalin,ZHANG Xiaobin,et al.Evolution characteristics of Central Sichuan palaeouplift and its relationship with Early Cambrian Mianyang-Changning intracratonic sag[J].Journal of Chengdu University of Technology(Science&Technology Edition),2014,41(6):703-712.
[12]周进高,张建勇,邓红婴,等.四川盆地震旦系灯影组岩相古地理与沉积模式[J].天然气工业,2017,37(1):24-31.ZHOU Jingao,ZHANG Jianyong,DENG Hongying,et al.Lithofacies paleogeography and sedimentary model of Sinian Dengying Fm in the Sichuan Basin[J].Natural Gas Industry,2017,37(1):24-31.
[13]张荫本.震旦纪白云岩中的葡萄状构造成因初探[J].石油实验地质,1980,2(4):40-43.ZHANG Yinben.Origin of the grape-like texture in rocks of Sinian age[J].Petroleum Geology&Expeximent,1980,2(4):40-43.
[14]王兴志,黄继祥,侯方浩,等.四川资阳及邻区灯影组古岩溶特征与储集空间[J].矿物岩石,1996,16(2):47-54.WANG Xingzhi,HUANG Jixiang,HOU Fanghao,et al.The relations between paleokarst and reservoir porosity in Dengying Formation,Sinian of Ziyang and neighboring area,Sichuan[J].Journal of Mineralogy and Petrology,1996,16(2):47-54.
[15]施泽进,梁平,王勇,等.川东南地区灯影组葡萄石地球化学特征及成因分析[J].岩石学报,2011,27(8):2263-2271.SHI Zejin,LIANG Ping,WANG Yong,et al.Geochemical characteristics and genesis of grapestone in Sinian Dengying Formation in south-eastern Sichuan Basin[J].Acta Petrologica Sinica,2011,27(8):2263-2271.
[16]郝毅,周进高,陈旭,等.四川盆地灯影组“葡萄花边”状白云岩成因及地质意义[J].海相油气地质,2015,20(4):57-64.HAO Yi,ZHOU Jingao,CHEN Xu,et al.Genesis and geological significance of upper Sinian Dengying dolostone with grape-lace shaped cement,Sichuan Basin[J].Marine Origin Petroleum Geology,2015,20(4):57-64.
[17]王兴志,侯方浩,刘仲宣.资阳地区灯影组层状白云岩储集层研究[J].石油勘探与开发,1997,24(2):37-40.WANG Xingzhi,HOU Fanghao,LIU Zhongxuan.Stratified dolomite reservoirs in Dengying Formation of Ziyang Region[J].Petroleum Exploration and Development,1997,24(2):37-40.
[18]赵雪凤,朱光有,刘钦甫,等.深部海相碳酸盐岩储层孔隙发育的主控因素研究[J].天然气地球科学,2007,18(4):514-521.ZHAO Xuefeng,ZHU Guangyou,LIU Qinfu,et al.Main control factors of pore development in deep marine carbonate reservoirs[J].Natural Gas Geoscience,2007,18(4):514-521.
[19]JIN Z,ZHU D,HU W,et al.Mesogenetic dissolution of the middle Ordovician limestone in the Tahe oilfield of Tarim basin,NWChina[J].Marine&Petroleum Geology,2009,26(6):753-763.
[20]金振奎,余宽宏.白云岩储集层埋藏溶蚀作用特征及意义:以塔里木盆地东部下古生界为例[J].石油勘探与开发,2011,38(4):428-434.JIN Zhenkui,YU Kuanhong.Characteristics and significance of the burial dissolution of dolomite reservoirs:Taking the Lower Paleozoic in eastern Tarim Basin as an example[J].Petroleum Exploration and Development,2011,38(4):428-434.
[21]雷川,陈红汉,苏奥,等.碳酸盐岩埋藏溶蚀研究进展[J].断块油气田,2014,21(2):165-170.LEI Chuan,CHEN Honghan,SU Ao,et al.Study progress on buried dissolution in carbonate rock[J].Fault-Block Oil&Gas Field,2014,21(2):165-170.
[22]沈安江,佘敏,胡安平,等.海相碳酸盐岩埋藏溶孔规模与分布规律初探[J].天然气地球科学,2015,26(10):1823-1830.SHEN Anjiang,SHE Min,HU Anping,et al.Scale and distribution of marine carbonate burial dissolutional pores[J].Natural Gas Geoscience,2015,26(10):1823-1830
[23]MAZZULLO S J.Overview of porosity evolution in carbonate reservoirs[J].Kansas Geological Society Bulletin,2004,79:20-28.
[24]佘敏,寿建峰,沈安江,等.埋藏有机酸性流体对白云岩储层溶蚀作用的模拟实验[J].中国石油大学学报(自然科学版),2014,38(3):10-17.SHE Min,SHOU Jianfeng,SHEN Anjiang,et al.Experimental simulation of dissolution and alteration of burial organic acid fluid on dolomite reservoir[J].Journal of China University of Petroleum(Natural Science Edition),2014,38(3):10-17.
[25]宋文海.乐山-龙女寺古隆起大中型气田成藏条件研究[J].天然气工业,1996(S1):13-26.SONG Wenhai.Research on reservoir-formed conditions of largemedium gas fields of Leshan-Longnvsi palaeohigh[J].Natural Gas Industry,1996(S1):13-26.
[26]魏国齐,王志宏,李剑,等.四川盆地震旦系、寒武系烃源岩特征、资源潜力与勘探方向[J].天然气地球科学,2017,28(1):1-13.WEI Guoqi,WANG Zhihong,LI Jian,et al.Characteristics of source rocks,resource potential and exploration direction of Sinian and Cambrian in Sichuan Basin[J].Natural Gas Geoscience,2017,28(1):1-13.
[27]魏国齐,杨威,谢武仁,等.四川盆地震旦系-寒武系大气田形成条件、成藏模式与勘探方向[J].天然气地球科学,2015,26(5):785-795.WEI Guoqi,YANG Wei,XIE Wuren,et al.Formation conditions,accumulation models and exploration direction of large gas fields in Sinian-Cambrian,Sichuan Basin[J].Natural Gas Geoscience,2015,26(5):785-795.
[28]TEINTURIER S,ELIE M,PIRONON J.Oil-cracking processes evidence from synthetic petroleum inclusions[J].Journal of Geochemical Exploration,2003,78(3):421-425.