二连盆地乌里雅斯太凹陷油气成藏模式及分布特征

Forming pattern and distribution features of hydrocarbon reservoir in Wuliyasitai Sag of Erlian Basin

乌里雅斯太凹陷独特的地质特征和成藏特点决定其斜坡带是主要的聚油单元,岩性地层油藏是其主要的油藏类型。对油气分布聚集富集规律的研究表明,油气主要赋存在2个湖泛面之间,且主要沿不整合面、湖泛面和断面分布。快速沉降的不整合面有利于形成地层油藏,控层控相的坡折带对油气的分布具有明显的控制作用;油气的分布严格受控于沉积体系,油气的聚集对砂体的成因类型具有选择性,而油气的富集则受控于有利的沉积相带和储集相带。

Wuliyasitai Sag in Erlian Basin is the Cretaceous fault-through sag and has the single-fault overlap structure. The particular geologic features and reservoir-forming characteristics of Wuliyasitai Sag show that the slope break zone in this sag is the main oil accumulation unit. The litho-stratigraphic reservoir is the main reservoir pattern of the sag. The hydrocarbon distribution, accumulation and enrichment laws indicate that oil and gas mainly exist between two lacustrine flood surfaces and mainly distributed along unconformity surface, lacustrine flood surface and fault surface. The rapidly subsided unconformity surface is favorable to form the stratigraphic reservoir. The slope break zone controlling the strata and facies of this sag plays obvious role in the distribution of oil and gas which is strictly controlled by sedimentary system. The hydrocarbon accumulation has selectivity on genetic type of sand body, while oil and gas enrichment is controlled by favorable sedimentary facies belt and reservoir facies belt.