大陆边缘三角洲盆地油气成藏特征类比研究

大陆边缘三角洲盆地一直是油气最为富集的地区之一，世界上很多大的油气区均是分布在三角洲盆地，如西非尼日尔三角洲盆地，东非鲁伍玛盆地三角洲和印尼库泰盆地马哈坎三角洲等。通过对不同类型大陆边缘三角洲盆地油气地质条件的差异性对比研究，明确在不同构造演化阶段发育的三角洲盆地的盆地结构、内部构造样式、烃源岩特征及成藏模式均存在明显差异。其中，漂移期发育的尼日尔三角洲和鲁伍玛盆地三角洲重力滑脱推覆构造体系发育。在裂陷期拗陷阶段发育的库泰盆地马哈坎三角洲重力滑脱推覆构造体系不发育。马哈坎三角洲和尼日尔三角洲盆地的主力烃源岩均来自三角洲体系，以生油为主，具有自生自储，近源成藏的特点。东非鲁伍玛盆地烃源岩为下侏罗统海湾环境海相烃源岩，主要生裂解气，具有阶梯式长距离运移，远源成藏的特点。

Characteristics of Analog Hydrocarbon Reservoir Formation in Continental Margin Delta Basins

Continental margin delta basins tend to be rich in hydrocarbon resources and contain many hydrocarbon reservoirs; for example, the Niger Delta Basin in West Africa, the Ruvuma Basin Delta in East Africa, and the Mahakam Delta in the Kutai Basin, Indonesia. An analog study was conducted to examine the different petroleum-geological characteristics of different types of continental margin delta basin. Our results reveal that delta basins that formed during different stages of tectonic evolution exhibit very different basin structures, internal structural styles, source rock characteristics, and hydrocarbon reservoir formation patterns. For example, the Niger Delta and Ruvuma Basin Delta developed during the drift stage and their gravitational nappe structures are well developed. Conversely, the Mahakam Delta in the Kutai Basin developed during the depression phase of rifting and its gravitational nappe structures are poorly developed. The reservoirs in both the Mahakam Delta and Niger Delta Basin essentially consist of oil source rocks originating mainly from the delta system and are characterized by self-generation, self-preservation, and near-source formation. Conversely, reservoirs in the Ruvuma Basin in East Africa consist of cracked gas marine source rocks originating from the lower-Jurassic gulf environment and are characterized by stepped long-distance migration and far-source formation.