万安盆地沉积发育史及其与油气生储盖层的关系

万安盆地是南海西南部陆架上的大型新生代沉积盆地。晚始新世以来,受盆地东界断裂——万安断裂的多期活动及全球海平面控制,盆地经历了从晚始新世—早渐新世的内陆湖泊到晚渐新世的海湾及早中新世以来的滨、浅海—半深海环境的发育历程。盆地内有丰富的油气资源。油气的生成、运移与聚集都受沉积特征的强烈控制。内陆湖泊环境中的湖相泥岩段和海湾环境的海湾相泥岩段有机质含量高,是重要的烃源岩。三角洲砂体,浊积砂体,扇三角洲砂体,深切河谷内的河道砂体,碳酸盐台地及其斜坡脚的塌积岩是有利的储集岩体。上新世早期的海进和高水位期间形成的凝缩段是区域稳定的盖层,其各阶段发育的凝缩段多为局部性盖层。

DEPOSI-TIONAL HISTORY AND ITS RELATIONSHIP TO HYDROCARBON OF WAN'AN BASIN

Wan'an basin is a large scale Cenozoic sedimentary basin which is located on southwest shelf of the South China Sea. It has been controlled by the activities in multiple stages of eastern boundary fault and Wan'an fault and eustatic change since late Eocene,and the basin was experienced with several depositional stages: lacustrine in Eocene-early Pliocene, bay in late Pliocene and coastal, shallow marine in early Miocene to present. The basin is rich with hydrocarbon resource. The hydrocarbon generation, migration and accumulation are strongly controlled by depositional features. The lacustrine shale and shale of bay facies have a high organic content,which are important source rocks. The deltic sand body ,turbidites and fan delta sands,river channel sands. Carbonate platform and its collapsed materials are favorable reservoir. The condensed section formed during sea agression and high water stage of early Pleistocene is a regional cover,and the condensed sections formed in other stages are mostly local seals.