ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    西非Termit盆地石油地质特征及成藏主控因素

    Petroleum Geological Characteristics and Main Control Factors of Hydrocarbon Accumulation in Termit Basin, West Africa

    • 摘要: 西非Termit盆地是中国石油在非洲极为重要的勘探开发区块。在充分利用钻井、分析化验和地震资料基础上,开展了Termit盆地石油地质特征和成藏主控因素研究,研究表明:①Termit盆地历经前裂谷期、同裂谷期、后裂谷期三大构造演化阶段,同裂谷期发育早晚两期裂谷作用形成中生代—新生代叠置裂谷盆地,宏观具有“东西分带、南北分块”的构造结构特征,控制圈闭的形成与分布。②发育上白垩统Yogou组分布广(18000 km2)、厚度大(600~1400 m)、成熟度适中(Ro值为0.7%~1.3%)的海相烃源岩,配置上白垩统Yogou组顶部发育的海相三角洲、古近系Sokor 1组辫状河三角洲砂体,及古近系Sokor 2 组区域性分布的泥岩盖层,形成了上、下两套成藏组合;③明确古近系、白垩系成藏主控因素,古近系为“下生上储”的次生油气藏,油气平面和垂向分布受生烃灶、区域盖层、油源断层和优势沉积相控制,白垩系为“自生自储”原生油藏,油气富集受区域构造活动强度和白垩系内幕构造控制。④构建了基于海相广覆式烃源岩的跨世代油气成藏模式,明确Dinga断阶带、Fana凸起和Araga地堑是古近系油气勘探的有利区带,造活动相对较弱的Moul凹陷及Dinga断阶带南部是白垩系油气勘探的有利区带。地质认识指导勘探部署,在尼日尔Termit盆地获得了重大勘探突破,累计探明石油地质储量超7亿t,为中国石油海外油气增储上产奠定了坚实的基础。

       

      Abstract: The Termit basin is a very important exploration and development block of CNPC in Africa. The petroleum geological characteristics and main controlling factors of hydrocarbon accumulation have been studied base on the drilling, analysis and seismic data ,in the Termit basin. The research shows that: ① The Termit basin has undergone three tectonic evolution stages: pre-rift period, synrift period and post-rift period, and the meso-Cenozoic superimposed rift basin was formed by two stages of early and late rifting during synrift period. The macrostructure features of "east-west zoning and north-south segmentation" control the formation and distribution of traps. ② The Upper Cretaceous Yogou Formation is widely distributed (18000 km2), with a large thickness (600~1400 m) and moderate maturity (Ro: 0.7%~1.3%) Marine source rocks, with Marine delta developed at the top of Upper Cretaceous Yogou Formation, braid river delta sand body of Paleogene Sokor1 member, and mudstone cover of Paleogene overlying Sokor2 formation regionally distributed, formed a good reservoir-cap association. ③ The main controlling factors of hydrocarbon accumulation in Paleogene and Cretaceous are identified. Paleogene is a secondary hydrocarbon reservoir with "lower generation and upper reservoir", the plane and vertical distribution of oil and gas is controlled by hydrocarbon generation focus, regional cap layer, oil source fault and dominant sedimentary facies, while Cretaceous is a "self-generated and self-storage" primary reservoir, and oil and gas enrichment is controlled by regional tectonic activity intensity and Cretaceous insider structure. ④ A cross-generation hydrocarbon accumulation model based on widely covered Marine source rocks is constructed, and the Dinga fault-step belt, Fana uplift and Araga Graben are identified as favorable zones for hydrocarbon exploration in Paleogene, while the Moul sag and the southern part of Dinga fault-step belt are favorable zones for hydrocarbon exploration in Cretaceous. Geological knowledge guided exploration and deployment, achieved a major exploration breakthrough in the Termit Basin in Niger, and accumulated proved oil geological reserves exceeded 700 million tons, laying a solid foundation for CNPC to increase overseas oil and gas reserves and production.

       

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