苏北盆地油藏类型与成因机制探讨

Feature and genesis of reservoir fluid distribution in Subei epigenetic-faulted basin

苏北盆地存在大量断层和复杂局部构造。断层作为圈闭的有机组成部分是油气运聚成藏的关键因素之一,主要形成断鼻、断块圈闭油藏。按圈闭中油水分布特点,该区可归结为2大类6种油藏类型;研究了层状砂岩油藏的4种油水分布样式及其成因机制。结果表明,层状砂岩油藏4种不同样式的油水分布,主要是由圈闭生储盖组合性质、断层侧向遮挡质量和封通双重作用、油气运移路径、充注方式和断层调节油气等因素决定的。明确上述认识,有助于加深该区对油气富集规律的认识以及勘探挖潜和开发部署工作的进一步展开。

Subei epigenetic-faulted basin develops three structural layers which occur in large stretch depression,small rift and faded depression.There are three regional source-reservoir-cap combinations in depression layer,and several local combinations in rift which result in four oil systems.Variations of faults and complex local structures are presented with evolution of the basin. Fault,an indivisible part of closure,is one of the key factors in hydrocarbon migration and accumulation.According to the origin of traps,structural,stratigraphic and structural-stratigraphic traps(including 6 subtypes and 15 subclasses) are classified,the former of which is dominant.Two types and six kinds of oil traps are classified by oil/water distribution,one of which is bedded sandstone oil traps which has four oil/water distribution patterns including uniform,grading,comb-like and irregular patterns. The distribution of oil-water is controlled by character of source-reservoir-cap combination,double actions from capacity of lateral seal and block-communication of fault,hydrocarbon migration path,hydrocarbon filling pattern and fault adjustment,and so on.