中大西洋被动陆缘盆地结构特征与勘探领域

中大西洋被动陆缘盆地油气资源丰富，而对盆地结构特征和成藏条件认识不足制约着区内深水油气勘探工作。综合分析地震、钻井和重磁异常等资料，以塞内加尔盆地和斯科舍盆地为重点解剖对象，研究了中大西洋被动陆缘盆地结构特征及其深水油气成藏条件并预测勘探领域。中大西洋被动陆缘盆地经历了断陷期、过渡期和漂移期三期演化，相应发育断陷层、坳陷层和陆缘层，基底性质和转换断层联合作用控制了被动陆缘盆地的结构。三叠纪—早侏罗世断陷期，发育垒堑结构，以河流、湖泊和三角洲等陆相沉积为主；中晚侏罗世过渡期，转换断裂活动形成边缘脊或海底隆起带，加之研究区古生界弱基底易拉伸减薄而沉降，与向陆方向高地势构成局限环境，为坳陷层烃源岩发育提供了有利条件；白垩纪漂移期，发育台缘礁、三角洲—坡底扇两类储集体。斯科舍盆地坡底扇和塞内加尔盆地台缘礁勘探前景广阔。

Structural characteristics and exploration fields in passive continental margin basins of Central Atlantic

The petroleum resources of the passive continental margin basins in the Central Atlantic are rich, but the insufficient knowledge of basin structural characteristics and accumulation conditions in the area restricts the exploration of deepwater oil and gas. Based on the integral analysis of seismic, drilling, gravity anomalies and magnetic anomalies data, the basin structural characteristics and hydrocarbon accumulation conditions in deepwater area of the passive continental margin basins of the Central Atlantic are studied and the exploration fields are predicted with the Senegal and Scotia basins as key anatomical objects. It can be concluded that the passive continental margin basins of the Central Atlantic have experienced three evolution stages: the rift period, the transition period and the drift period, with corresponding development of three tectonic layers: the rift layer, the depression layer and the continental margin layer, and the basin structures are controlled by transform faults and basement properties. From Triassic to Early Jurassic rift period, a series of horst-graben structures were formed, and the sediments were mainly continental ones such as rivers, lakes and deltas. From Middle to Late Jurassic transition period, the marginal ridge or submarine uplift zone were developed due to the activity of transform faults, and a landward high terrain limited environment was formed due to the stretch, thinning and subsidence of the Paleozoic weak basement, providing a favorable condition for the development of source rocks in the depression layer. During Cretaceous drift period, platform margin reef and delta-slope floor fan reservoirs were developed. Both the deepwater slope floor fan in the Scotia Basin and the platform margin reef in the Senegal Basin have great exploration potential.