柴达木盆地南翼山构造油气成因及成藏分析

Oil-Gas Origin and Accumulation Model of Nanyishan Structural Reservoir in Qaidam Basin

南翼山构造油气藏是目前柴西北区发现的最大油气藏。其深层E32是凝析气藏,浅层N22是正常密度的油藏,这种分布格局在柴西北区是唯一的,对它进行成藏解剖对整个柴西北区的油气勘探具有重要的意义。结合原油轻烃、天然气碳同位素和生物标志化合物综合判识油源,认为南翼山构造的N22与E32储集层原油来源不同,深层E32油气来自E32烃源岩,浅层N22的油来自N1烃源岩;南翼山构造的油气是就近捕获的产物,不是从南边长距离运移而来,深部凝析气藏的形成受有机质类型和成熟度共同控制。

Nanyishan structural reservoir is the biggest reservoir in northwestern Qaidam basin at present. The deep E3^2 is a condensate gas reservoir and the shallow N2^2 is a conventional oil reservoir. Study and anatomy of such reservoirs with a unique distribution in this area is of significance to its petroleum exploration. It is suggested from comprehensive recognition of oil source in terms of the light hydrocarbon, gas carbon isotopes and biomarkers that the crude oil in the shallow N2^2 is different from that in the deep E3^2. The former comes from the N1 source rocks, while the latter from the E3^2 source rocks, and pointed out that the oil and gas of Nanyishan structural reservoir are captured from the source rocks in the vicinity, not migrated from the south of Qaidam basin. The shape of deep condensate gas reservoir is controlled by the kerogen type and the maturity.