东非裂谷Albertine地堑石油地质条件和成藏规律

Petroleum Geology and Hydrocarbon Accumulation in the Albertine Graben, East Africa Rift

Albertine地堑位于东非裂谷西支北段,是典型陆内裂谷盆地,具有优越的石油地质条件。盆地主要发育中新统湖相烃源岩,I-II1型干酪根为主,成熟范围广,生烃规模大;盆地具有轴向和侧向多物源注入,主要储层为晚中新统到早上新统时期沉积的三角洲和扇三角洲砂体,储层物性好,分布广泛;在盆地转换带和陡断带分布发育较大规模的断块和断背斜圈闭,圈闭形成时间与生排烃时间匹配关系较好,后期保存条件较好;油气运聚成藏,形成三种典型成藏模式。此外,在盆地转换带、盆地陡断带和深洼区还存在较大的勘探潜力。

The Albertine graben located in the northern part of the western branch of the East Africa Rift is a typical continental rift basin. Significant oil discovery means the excellent geological conditions in this basin. Miocene mudstone is main hydrocarbon resource with the kerogen type of I to II1. Multi-provenance from axial and lateral orientation can afford sufficient coarse-grained clastic sediments which can be the efficient reservoir for the oil and gas. Main reservoirs are Upper Miocene to Lower Pliocene delta and fan delta sand bodies with great porosity and permeability. Faulted block traps in basin transition zone and faulted anticline traps in the steep fault zone are the best traps. This paper has a discussion on three kinds of accumulation models in different parts in this basin. There are still some large potential for the further exploration in basin transition zone and faulted anticline traps.