彩南油田多源混合原油油源(三)——油源的地质、地球化学分析

Oil-source correlation of mixed oils derived from multiple source rocks in the Cainan Oilfield, Junggar Basin, Northwest China. Part III: Geological and geochemical analysis of possible oil sources in the Cainan Oilfield

彩南油田原油属特殊类型,原油碳同位素和生物标志物分布研究以及地质分析表明它们属于二叠系、三叠系和侏罗系原油的混合原油。原油全油稳定碳同位素计算表明,无论是侏罗系原油与二叠系原油混合还是与三叠系原油混合,在彩南油田原油中侏罗系烃源岩的贡献均为50%～65%。生物标志物绝对含量拟合计算表明,侏罗系烃源岩的贡献平均为62%,三叠系为15%,二叠系为23%。与彩南油田原油类似的原油仅分布于阜康凹陷侏罗系三工河组以上地层中。因此,该类原油主要来源于阜康凹陷侏罗系烃源岩,其次为二叠系和三叠系烃源岩。

The crude oils in the Cainan Oilfield are mixtures of hydrocarbons from Permian, Triassic and Jurassic source rocks, based on their distribution in the reservoirs, and their carbon isotopic and biomarker compositions. A calculation using whole-oil stable carbon isotope ratios of typical end-member crude oils suggests that the contribution of Jurassic source rocks to the Cainan crude oils averages 50%～65%. A matching calculation with absolute concentrations of biomarkers indicates that the Jurassic contribution averages 62%, while those of the Triassic and Permian source rocks average 15% and 23%, respectively. The oils with similar features to the Cainan oils, occur only above the Jurassic Sangonghe Formation around the Fukang sag. Hence they are derived from the Fukang sag.