东非裂谷阿尔伯特盆地石油地质特征及成藏模式

基于地质、地震和钻井资料，对东非阿尔伯特盆地（Lake Albert Basin）的形成演化及构造-沉积地层特征进行了研究，深入分析了盆地石油地质特征，总结其成藏模式及油气富集条件。盆地主要受东非裂谷期构造运动的影响，形成两侧以深大断裂为界、狭长（半）地堑的构造格局。沉积地层以新近系碎屑岩为主，岩性多为泥岩、砂岩和砾岩。河流-（扇）三角洲-湖泊沉积体系发育，主要烃源岩为中新统上部富有机质页岩，中新统-上新统河流相、（扇）三角洲相砂岩为主要储层，与细粒湖相泥岩在纵向上形成良好的生储盖匹配。盆地发育大量断块、断背斜等构造圈闭。盆地成藏模式为"凹陷供烃、侧向与垂向复合运移、下生上储"，生储盖匹配良好控制垂向上形成多套成藏组合，优质砂体与垂向断层控制油气有效运移，断层控制的构造圈闭是油气聚集的主要场所。

Petroleum geology and hydrocarbon accumulation pattern in the Lake Albert Basin of East African rift system

The evolution and tectonic-sedimentary stratigraphic features of the Lake Albert Basin in the East Africa were studied using geological, seismic and drilling data. The petroleum geology features and the accumulation pattern and enrichment conditions were summarized. The basin was mainly affected by the tectonic movement of the East Africa rift system, forming a long and narrow (semi-) graben with deep faults on both sides. The sedimentary strata are dominated by Neogene clastic rocks, including mudstone, sandstone and conglomerate. Depositional fill is characterized by a river-(fan) delta-lacustrine sedimentary system. The Upper Miocene organic-rich shale, Miocene-Pliocene fluvial-(fan) delta sandstone and fine lacustrine mudstone formed a favorable source-reservoir-cap assemblage vertically. There are a large number of structural traps. Hydrocarbon generated in depressions, migrated vertically and laterally, and finally accumulated in upper formations, resulting in multiple sets of stacked reservoirs. High-quality sand bodies and vertical faults controlled the effective migration of oil and gas, and structural traps developed by fault control are the main sites for oil and gas accumulation.