西非塞内加尔盆地重油成藏条件及富集规律

塞内加尔盆地是西非面积最大的被动大陆边缘型盆地,已发现具有一定储量规模的重油油田,但只进行了有限的勘探开发活动。研究区以白垩系森诺曼阶-土仑阶海相页岩为烃源岩,渐新统有孔虫灰岩和下中新统三角洲砂岩作为储层,中新统页岩和黏土作为盖层,生储盖配置较好。盐底辟活动形成一系列运移通道和构造-岩性圈闭,因此成藏条件好。通过对典型重油油田Dome Flore的分析,总结研究区具有盐底辟控运移、控圈闭,埋藏较浅的有利储层控藏的特征,并且呈现出盐底辟周围聚集的轻质油藏上方,即盐隆顶部的渐新统和中新统储层形成重油富集的规律。在此基础上预测了重油成藏有利区,为该区的重油资源勘探提供基础。

Heavy oil accumulation condition and enrichment regularity of Senegal Basin in West Africa

Senegal basin is the largest passive continental margin basin in West Africa,which has been found a certain scale of heavy oil reserves, but only a limited number of exploration and development activities have been done.In the study area,the source rocks are the Cretaceous Cenomanian- Turonian marine shales, the reserviors are the Oligocene foraminiferal limestones and Lower Miocene delta sandstones, then the Miocene shales and clays are the cover rocks. The souce-reservoir-seal configuration is very good.A series of migration pathways and structural-stratigraphic traps are formed by salt diapirs activity.So the accumulation condition of heavy oil is good. According to the analysis of a typical heavy oil field named Dome Flore, We have summarize that the study area has following characteristics: salt diapirs control migration and traps, the shallow favorable reservoirs control the oil accumulation,and the reservoirs above the light oil reservoirs which gathered around the salt dispairs accumulate heavy oil,that is to say, heavy oil enriched in the Oligocene and Miocene reservoirs on top of the salt uplift. Then we predict the heavy oil accumulation advantage areas,and this research can provide the basis for heavy oil exploration in Senegal basin.