西非科特迪瓦盆地深水区油气地质特征及成藏主控因素

Petroleum Geological Features and Main Controlling Factors of Hydrocarbon Accumulation in Deepwater Areas of Cote D′Ivoire Basin,West Africa

科特迪瓦盆地位于西非几内亚湾北部,为典型的转换型大陆边缘盆地,是目前世界深水油气勘探的热点区域。以科特迪瓦盆地的构造演化、油气地质条件以及油气田最新发现为基础,采用油气地质综合分析方法,明确了盆地深水油气成藏的主控因素,可以为进一步明确勘探目标提供帮助,并为同类型盆地的油气勘探提供借鉴。研究表明,目前盆地共发育3套烃源岩,3套储层及多套盖层。盆地内最主要的深水成藏组合为上白垩统自生自储式和下生上储式成藏组合,其烃源岩为上白垩统森诺曼阶-土伦阶厚层海相页岩;储层主要是土伦阶-森纳阶深水浊积扇砂体;盖层主要是上覆新生界厚层海相页岩。盆地深水油气成藏主控因素为深水浊积扇和断层,二者相匹配共同控制油气成藏。

Located in the north of Guinea Bay in West Africa, Cote D＇Ivoire Basin is a typical transformed passive continental margin basin, which is now a hot spot of deepwater oil and gas exploration in the world. Based on the structural evolution, petroleum geological conditions of the basin and latest database of oil and gas fields, this paper discusses the main controlling factors of reservoir formation of basin deepwater oil and gas by applying multidisciplinary analysis of hydrocarbon geology to help further clarify exploration targets and also provide guidance for some basins of the same type. The study has found that there are three sets of hydrocarbon source rocks and reservoirs and multiple cap rocks in this basin. Upper Cretaceous reservoir forming combinations of ＂self-generation and self-preservation＂ and ＂down-generation and up-preservation＂ make up the main reservoir forming combinations in deepwater of Cote D＇Ivoire Basin, where hydrocarbon source rocks are thick marine shale of Cenomanian-Turonian, and reservoirs are mainly deepwater turbidity sand of Turonian-Santonian and cap rocks are overlying Cenozoic thick marine shale. In addition, the main controlling factors of deepwater hydrocarbon accumulation are the deepwater turbidity fans and faults, and the two factors control oil and gas accumulation collectively.