巴西海上坎波斯与桑托斯盆地油气成藏特征对比研究

Petroleum accumulation characteristics in Campos and Santos Basins,offshore Brazil

坎波斯与桑托斯盆地油气资源非常丰富。2个盆地均经历了裂谷、过渡、被动大陆边缘3个构造阶段,发育盐下陆相层序、盐岩层序、盐上海相层序,形成盐下、盐上2套成藏组合。由于盆地构造格架不同,导致盐岩分布、盐下储层发育程度的差异,加之盐上储层分布的不同,造成2个盆地油气分布特征的巨大差异。桑托斯盆地油气主要分布在外部高地带的盐下领域,而坎波斯盆地油气主要富集在中部低凸带的盐上储层中。通过分析2个盆地的构造演化及地层发育特征、成藏条件及主控因素,优选了盐下、盐上成藏组合的有利区,剖析了2个盆地成藏条件的异同,可指导我国石油公司在这2个盆地新项目评价和在执行区块的勘探部署。

The Campos and Santos Basins are rich in petroleum. Both of the 2 basins have experienced 3 phases of tectonic evolution （ rift, transition and passive continental margin） , depositing 3 corresponding sedimentary mega-sequences （pre-salt continental sequence, salt sequence and post-salt marine sequence）, and forming 2 plays （pre-sah play and post-salt play）. Due to different tectonic frameworks, salt distribution and pre-sah reservoir development patterns are dift^rent in the 2 basins. Combining with different post-salt reservoir distribution, obvious difference exists in petroleum distribution between the 2 basins. Petroleum in the Santos Basin mainly distributes in pre-salt sequences of the outer basement plateau while petroleum in the Campos Basin accumulates in post-sah reservoirs of the central low uplift. Based on the analyses of tectonic evolution, sedimentation characteristics and major controlling factors, the thvorable exploration zones for pre- and post-salt reservoirs are defined. The differences of accumulation condition between the 2 basins are discussed. The studies may provide Chinese companies a guide for new business development and executing blocks＇ exploration activities in the 2 basins.