柴达木盆地西部南区第三系原油成熟度特征

The Characteristics of Thermal Maturity of Crude Oils from Tertiary System in the Southwestern Part of Qaidam Basin

原油成熟度特征是原油地球化学研究的重要组成部分。通过对柴达木盆地西部南区第三系原油的色谱-质谱分析,在饱和烃和芳烃成熟度参数、生物标志物绝对浓度和热不稳定化合物的定量与定性分析基础上,详细剖析了该区原油的成熟度特征。研究结果表明:柴达木盆地西部南区第三系原油主体为未熟-低熟油,不存在混源造成未熟-低熟假象的可能性。成熟原油仅出现在花土沟、狮子沟和砂西地区。柴达木盆地西部南区有效烃源岩的发育特征,佐证了大量未熟-低熟原油存在的可能性。

Thermal maturity characteristics of crude oil was important composition of geochemistry of crude oil. Based on analysis of GC-MS in crude oils from the Tertiary system in the southwest of Qaidam Basin, the qualitative and quantitative characteristics of maturity parameters in saturate and aromatic fraction, absolute concentration of biomarkers and thermal unstable compounds were investigated to understand thermal maturity of crude oils. The results show that crude oils in the study area are mainly immature or low-mature oils. The mature oils are only found in Huatugou, Shizigou and Shaxi Oilfields. In addition, it is demonstrated that there are large quantity of immature or low-mature oils in the Tertiary system of the southwestern part of the Qaidam Basin with the characteristics of source rocks in the study area.