Genetic Characteristics of Crude Oils from Yakela Oilfield in Tabei Uplift
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摘要: 针对雅克拉油气田多个含油气层位的原油,进行了一系列的地球化学测试分析,对雅克拉油气田原油的地球化学特征、成因特征进行了解剖。研究结果表明,雅克拉油气田深浅不同层位原油轻烃组成与轻烃单体烃碳同位素、类异戊二烯烷烃组成以及原油与馏分碳同位素组成具有明显的海相原油特征;深浅层原油三环萜烷、C28甾烷、三芳甾烷和甲基三芳甾烷以及原油与馏分碳同位素组成皆具有典型上奥陶统来源油的特征,与寒武—下奥陶统来源油特征差异明显,暗示雅克拉油气田原油来源于上奥陶统烃源层。Abstract: Geochemical analysis was completed for crude oils from Yakela oilfield to investigate geochemical characteristics and genetic type of crude oils. The heptane value, isoheptane value and MCYC6 index of crude oils in Yakela oilfield provided excellent evidence for marine oils characteristics. Compoundspecific carbon isotope of light hydrocarbons indicated that oils in Yakela oilfield were marine oils with relative high maturity for lower oils. C21/C23 tricyclic diterpane and C28 steranes relative content in C27~C29steranes were consistent with oils derived from O3source rock in Tarim Basin. Characteristics of triaromatic steroids and methyl triaromatic steroids further proved the O3 source rock was the source of oils in Yakela oilfield. A significant difference was found in carbon isotope composition of whole oil and fractions of TD2 well ,T904 well and Yakela oilfield,which suggested the crude oils among deeper and shallower layers in Yakela oilfield were marine oils and had obvious diffrences with crude oils derived from ∈—O1. Based on the ight hydrocarbons, tricyclic terpanes, C28steranes, triaromatic steranes and methyl triaromatic steranes, and carbon isotope composition of whole oil and fractions, it is suggested that the crude oils of Yakela oilfield in deeper and shallower layers had the common source and derived from O3 source rock.
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Key words:
- Tabei Uplift
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