渤海海域辽西凹陷中央反转带原油成因类型及成藏特征  

Genetic Types and Accumulation of Crude Oil in the Central Inversion Zone in the Liaoxi Depression,Bohai Sea

作　　者：田德瑞 牛成民 王德英 郭涛 潘文静 郭龙龙 TIAN Derui;NIU Chengmin;WANG Deying;GUO Tao;PAN Wenjing;GUO Longlong(Tianjin Branch of China National Offshore Oil Company Ltd,Tianjin 300459,China)

机构地区：[1]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《高校地质学报》2021年第4期444-458,共15页Geological Journal of China Universities

基　　金：十三五国家科技重大专项(2016ZX05024-002-006);中海石油(中国)有限公司“七年行动计划”重大科技专项课题(CNOOCKJ135ZDXM36TJ08TJ);中海石油(中国)有限公司综合科研项目(YXKY-2017-JJ-01)联合资助。

摘　　要：辽西凹陷中央反转带是辽东湾探区优质轻质原油的富集区,但关于该地区原油成因类型、分布规律及成藏特征尚未开展系统研究。文章通过系统的生物标志化合物分析及对比,识别出辽西凹陷沙河街组发育沙一段、沙三段、沙四段3套有效烃源岩,但有机质来源及沉积环境差异明显。研究证实3套烃源岩的有机质组成均以浮游生物为主,其中沙一段浮游生物含量最高,陆源输入最少,沙四段有机质组成中沟鞭藻含量明显高于沙一段和沙三段。此外,沙三段和沙四段烃源岩均沉积于淡水—微咸水弱碱性还原环境,沙一段烃源岩沉积于半咸水—咸水碱性强还原环境。通过聚类分析方法将中央反转带发现的原油划分为3种类型,结合油源对比研究表明第Ⅰ类原油为沙三段和沙一段烃源岩生成的混源油,主要分布在中央反转带的中块和东块中部地区;第Ⅱ类原油来自沙四段烃源岩,仅分布在中央反转带东块南部地区;第Ⅲ类原油为沙四段和沙三段烃源岩生成的混源油,主要分布在中央反转带西块以及东块北部地区。在此基础之上对辽西凹陷中央反转带成藏主控因素进行分析,明确辽西凹陷中央反转带油气藏受“源—断—砂”三因素耦合控制,即有效烃源岩分布、油源断裂与砂体匹配程度控制了油气的空间分布。The central inversion zone of the Liaoxi Depression is the enrichment area of high quality light crude oil in the Liaodong Bay exploration area.However,the genetic types,source and accumulation of crude oil have not been systematically studied.Based on the analysis and comparison of the biomarkers,three sets of effective source rocks of the Shahejie Formation were distinguished.The first,third and fourth members of the Shahejie Formation,are obviously different in the source of organic matter and sedimentary environment.It is confirmed that plankton is the main component of organic matter in the three sets of source rocks.The first member of the Shahejie Formation(E2s1)has the highest plankton content and the least terrestrial organic matter input.The content of dinoflagellate in the fourth member of the Shahejie Formation(E2s4)was significantly higher than that in the first and third members of the Shahejie Formation(E2s1,E2s3).Both E2s3 and E2s4 source rocks were deposited in the freshwater and weakly alkaline reducing environment,and the E2s1 source rock was deposited in the brackish to saline alkaline strongly reducing environment.The crude oil found in the central inversion zone can be divided into three source-related types through hierarchical cluster analysis(HCA).The oil-source correlation results show that the typeⅠcrude oil is the mixed oil originated from the E2s3 and E2s1 source rocks,which is mainly distributed in the middle block and the middle area of the east block on the central inversion zone.The typeⅡcrude oil is originated from the E2s4 source rocks,which is distributed in the southern area of the east block on the central inversion zone.The typeⅢcrude oil is the mixed oil originated from the E2s3 and E2s4 source rocks,which is mainly distributed in the west block and the northern area of the east block on the central inversion zone.On this basis,the main controlling factors of hydrocarbon accumulation in the central inversion zone of the Liaoxi sag were analyzed.Oil and gas reservoirs

关 键 词：聚类分析 生物标志化合物 沙河街组 三芳甾烷 油源对比 辽西凹陷 

分 类 号：P618.13[天文地球—矿床学]