南大西洋下刚果盆地烃源岩特征与成藏贡献  

Source Rock Characteristics and Its Accumulation Contribution in the Lower Congo Basin,South Atlantic

作　　者：杨雄兵 王宏语[1] 苏玉山[2] 关超 YANG Xiongbing;WANG Hongyu;SU Yushan;GUAN Chao(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Research Institute of Petroleum Exploration and Development,SINOPEC,Beijing 100083,China;Tianjin Branch,CNOOC China Limited,Tianjin 300452,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]中国石化勘探开发研究院,北京100083 [3]中海石油(中国)有限公司天津分公司,天津300452

出　　处：《现代地质》2023年第5期1369-1384,共16页Geoscience

基　　金：国家重大油气专项(2016ZX05033-001-003)。

摘　　要：下刚果盆地位于南大西洋的非洲沿岸,由中生代裂谷盆地与新生代被动陆缘盆地叠合而成,是以岩盐构造发育为特色的富油气盆地。本文以二维地震、测井与地球化学资料为基础,结合前人勘探与研究成果,明确了该盆地烃源岩的类型与沉积环境,并通过烃源岩的热演化模拟、典型油气藏解剖、油气藏时空分布特征分析,揭示烃源岩发育特征及其在油气成藏中的贡献。研究表明,下刚果盆地在岩盐层之下的Bucomazi组发育湖相烃源岩,在岩盐层系之上的Iabe组、Landana组发育海相烃源岩。湖相烃源岩发育于干燥偏还原的湖盆环境中,有机质含量高;海相烃源岩发育于半深海-深海环境,累计厚度较大。在中新世后,Bucomazi组烃源岩进入生气阶段,Iabe组烃源岩进入生油阶段,为区内提供主要的油气供应。下刚果盆地油气藏类型及分布受烃源岩、断裂与盐构造等多重因素的影响,其中烃源岩的成熟、分布是关键要素。盐下油气藏多由近岸湖相烃源岩晚期供藏形成,而盐上油气藏则由多套烃源岩的多期供烃形成。The Lower Congo Basin,located along the African coast of the South Atlantic,is a petroliferous basin characterized by the salt tectonic development,which is composed of the Mesozoic rift basin and the Cenozoic passive continental margin basin.Based on two-dimensional seismic,well logging and geochemical data,combined with previous exploration and research results,we defined the types and sedimentary environments of source rocks in this basin,and clarified the source rock development characteristics and revealed their contributions to hydrocarbon accumulation.The study was conducted through thermal evolution simulation of source rocks,anatomy of typical hydrocarbon reservoirs,and analysis of the temporal-spatial distribution characteristics of hydrocarbon reservoirs.The results show that lacustrine source rocks are developed in the Bucomazi Formation under the salt layer,and marine source rocks are developed in the Iabe and Landana Formations above the salt layer.Lacustrine source rocks are developed in dry and reducing lacustrine basin environment with high organic matter content.Marine source rocks have large cumulative thickness,and developed in(semi-)abyssal environment.After the Miocene,the Bucomazi Formation source rocks entered the gas generation stage,and the Iabe Formation source rocks entered the oil generation stage,providing the main hydrocarbons in the region.The type and distribution of hydrocarbon reservoirs in the Lower Congo Basin are affected by multiple factors,such as the source rocks,faults and salt tectonics,among which the maturity and distribution of source rocks are the key ones.The subsalt oil and gas reservoirs are mostly formed by the late supply of lacustrine source rocks near the shore,while the soil and gas reservoirs above the salt were formed by the multi-stage supply of hydrocarbon from multiple source rocks.

关 键 词：下刚果盆地 盐岩 烃源岩 热演化模拟 成藏特征 

分 类 号：P618.13[天文地球—矿床学]