南大西洋被动大陆边缘盆地深水盐下油气藏特征分析

摘要

Deep water pre-salt exploration of the South Atlantic passive continental margin basin has been the focus of the global exploration all along. On February, 2012, Angola’s deepwater oil and gas discovery made it become one of the hot spots all around the world again. Through the integrated studies on the representative basins along both sides of the South Atlantic, and focusing on the typical reservoirs which had been found, four main characteristics of deep water pre-salt reservoirs were summarized to guide for finding fields and the exploration in this area. The research suggests that pre-salt lacustrine shale in the Rift is the main source rock and the development degree of the lake basin decides the enrichment degree of the pre-salt hydrocarbon. The thick seam and the continuous distributed salt rock are the effective capping formation. Lacustrine carbonate of high quality is the important pre-salt accumulation reservoir. The high position of structure in the Rift is the favorable position of developing the structure-lithology trap with other relatively advanced hydrocarbon accumulation conditions, which is believed to be the best position of the hydrocar⁃bon accumulation of the deep water pre-salt area in the passive continental margin basin of the South Atlantic.%　　南大西洋被动大陆边缘盆地的深水盐下油气勘探一直是全球油气勘探的重点[1，2]，2012年2月安哥拉深水油气的发现使该领域再次成为全世界关注的热点区域[3]，通过对南大西洋两岸具有代表性盆地的综合研究，对已发现的典型油气藏进行重点解剖，总结了深水盐下油气藏的四个主要特征，对在该领域寻找油气田与进行油气勘探有一定的指导意义。研究认为盐下裂谷期湖相泥页岩是主要烃源岩，并且湖盆的发育程度控制了盐下油气的富集程度；厚层、连续分布的盐岩层是有效盖层；优质的湖相碳酸盐岩是盐下成藏的重要储层；裂谷期的构造高部位是构造—岩性圈闭发育的有利位置，并且其它油气成藏条件均较为优越，是南大西洋被动大陆边缘盆地深水盐下油气成藏的最佳位置。