西非宽扎盆地盐下构造特征及成藏条件分析

Pre-salt structure characteristics and reservoir conditions of Kwanza Basin, West Africa

刘亚雷¹ 柳永杰² 李梅¹ 李斐² 聂志勐²

北京博达瑞恒科技有限公司，北京 100101 中国海洋石油国际有限公司，北京 100027

PST Service, Corp., Beijing 100101, China CNOOC International Ltd., Beijing 100027, China

为理清宽扎盆地盐下构造格局，进一步指导该盆地盐下勘探，文中通过对不同构造部位地震剖面的解释，总结了宽扎盆地的盐下构造特征，认为宽扎盆地裂陷期存在一中央隆起带，该隆起带将宽扎盆地分隔为内宽扎次盆和外宽扎次盆，大西洋枢纽断裂是中央隆起带和外宽扎次盆的分界线。在外宽扎次盆，发育多个受断裂控制的次级凸起，已有钻井证实这些凸起为有利的油气聚集区。宽扎盆地的成藏研究结果表明：宽扎盆地盐下成藏条件优越，烃源岩发育在深湖￣半深湖相凹陷内，主要为巴列姆阶湖相泥页岩；储层为Cuvo组碳酸盐岩和砂岩，主要发育在次级凸起和斜坡带上；盖层为阿普特阶盐岩。综合分析认为，紧邻大西洋枢纽断裂西侧的凸起带为宽扎盆地盐下最有利的勘探区带。

In order to get the pre-salt structure framework of Kwanza Basin and guide the pre-salt exploration, the pre-salt structure characteristics of the Kwanza Basin were studied and summarized by the seismic interpretation of different structural profiles. This basin can be divided into two sub basins, the inner and the outer Kwanza sub-basins, by a central uplift developed in rift stage, and the Atlantic hinge fault is the boundary between the central uplift and the outer sub-basin. In outer Kwanza sub-basin, some rises controlled by faults developed, which were proved favorable traps. Based on the recent structure research, we conclude that the Kwanza Basin has better reservoir conditions, and the source rocks developed in sags are mainly lacustrine shale in Barremian stage; the reservoir rocks are mainly carbonate and sandstone in Cuvo Formation, which developed on the horsts and slope areas; the cap rocks are mainly Aptian salt. Based on the above-mentioned research, this paper points out that the clear goal for the next exploration of the pre-salt layer in Kwanza Basin is the rises adjoined the west of the Atlantic hinge fault.

10.6056/dkyqt201701001