安哥拉宽扎盆地白垩系油气成藏条件及勘探潜力

Hydrocarbon Accumulation Conditions and Exploration Potential of Cretaceous in Kwanza Basin,Angola

以安哥拉宽扎盆地的构造演化、沉积充填特征研究为基础,重点开展宽扎盆地的盐上和盐下构造单元划分及盆地油气成藏基本条件研究,系统总结宽扎盆地的白垩系油气成藏模式,指出有利勘探区。宽扎盆地经历了裂谷阶段、过渡阶段和被动陆缘阶段的构造沉积演化阶段,不同的构造演化控制着宽扎盆地的盐上、盐下构造单元变化及生储盖条件的变化,形成盐下自生自储运聚成藏模式和盐上下生上储跨越式运聚成藏模式。宽扎盆地临近大西洋枢纽带以西及附近深海的盐下地垒(高地)与盐岩分布厚盐区的叠置区域是盐下油气聚集的有利区带,其勘探潜力大。宽扎盆地盐上Albian阶碳酸盐岩及砂岩发育的盆地近海区域是盐上有利勘探区。

Based on the structural evolution and sedimentary filling characteristics of Kwanza Basin in Angola,the post-salt and pre-salt tectonic units were divided and the basic hydrocarbon accumulation conditions were studied.The hydrocarbon accumulation model of Cretaceous in the basin was summarized systematically and the favorable exploration areas were pointed out.Tectonic sedimentary evolution stages were developed in rift stage,transitional stage and passive margin stage.The changes of tectonic units above and below salt and the changes of source,reservoir and capping conditions in Kwanza Basin were controlled by these three different tectonic evolution stages.Model of self-generation,self-storage,transportation and accumulation under salt and model of leaping migration accumulation and accumulation of upper and lower generation and upper salt were formed in Kwanza Basin.The overlapping area of the deepsea basement(plateau)near the west of the Atlantic Junction and the thick salt area with salt rock distribution are the favorable areas with great exploration potential of oil and gas accumulation under salt.The offshore areas,where the Albian carbonate rocks and sandstones develope,are the favorable exploration area above salt.