盐间非砂岩油藏中原油的均质性与非均质性研究

STUDY ON THE HOMOGENEITY AND HETEROGENEITY OF CRUDE OIL IN INTER-SALT NON-SANDSTONE RESERVOIRS

江汉盆地潜江凹陷潜江组盐间非砂岩油藏中 ,生储同层 ,烃源层品质好 ,成烃转化率高 ,且封盖条件极佳 ,但储集层渗透能力极低 ,油气运移条件差。纵向上各段盐间原油自成体系 ,分异性弱 ,但原油的成熟度、生标物等非均质性 ,表明韵律层内盐间原油普遍具有混源特征。盐间原油多为原地自生自储油与异地排驱的成熟油的混源油 ,这暗示了生烃次洼中生成的成熟油气可以在低渗透的盐间层中顺层侧向向构造高部位等低势区聚集 ,从而扩展了盐间油藏的油气来源。盐间原油的均质性集中展示了盐间原油的菌藻类母源和高盐度。

In the exceptional inter salt non sandstone reservoirs in the Qianjiang Depression of the Jianghan Basin, source rock is also reservoir rock. In the sequence, the source rock′s quality is good, the HC generation ratio is high, and the seal is completed, too; but the reservoir bed's permeability is very low, so the conditions of oil migration are poor. Inter salt crude oil in each reservoir is independent in non fractured areas, but many evidences of oil maturity and biomarks all show that inter salt crude oil generally has mixture source characteristics. The crude oil in place has always been mixed with mature oil migrated from other areas. This implies that mature crude oil can migrate from generation depressions to high structural areas through low permeability reservoir beds. The homogeneity of inter salt crude oil obviously reveals that inter salt crude oil is derived from bacteria and algae in high salinity, high sulfureous and strong reduction environment.