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利用气相色谱和气相色谱-质谱联用仪对采自塔河油田白垩系油藏的12件原油进行了生物标志物分析,系统研究了原油的地球化学和原油及族组成碳同位素特征.结果表明:白垩系原油中正构烷烃系列的碳数分布范围为nC10~nC35且呈前峰型单峰态分布,以nC15或nC16为主峰碳数、C21TT/C23TT值分布范围为0.51~0.56、甾烷质量分数C27>C28<1.4,西部原油Pr/Ph<1.2;东部原油二苯并噻吩质量分数为50%~70%,西部原油二苯并噻吩质量分数>80%;东部原油C30重排藿烷/C30藿烷值为0.20~0.23,西部原油C30重排藿烷/C30藿烷值为0.08~0.11.因此,白垩系原油与奥陶系原油具有共同的特征,即低密度、低含硫量、完整的正烷烃系列且以低分子量轻烃为主、C21/C23三环萜烷值<1、规则甾烷呈不对称“V”型分布、高C29/C30藿烷值、高二苯并噻吩含量、低碳同位素值,两者具有统一的油源,为同一成因类型.塔河油田白垩系东部6口井的原油与西部6口井原油分别属于不同的组群,造成东西部原油细微分子地球化学差异的原因可能是地层浸染或者气侵等次生作用.
The biomarkers of 12 crude oils collected from the Cretaceous reservoir in Tahe Oilfield were analyzed by gas chromatography and gas chromatography-mass spectrometry, and the geochemical characteristics of crude oil and the carbon isotope composition of crude oil and its components were systematically studied. : The carbon number distribution of n-alkanes series in Cretaceous crude oil is nC10 ~ nC35 and presents the pre-peak monomodal distribution, nC15 or nC16 is the main peak carbon number, C21TT / C23TT is 0.51 ~ 0.56, the mass of sterane The values of fraction C27> C28 << C29, C29 / C30 were from 0.55 to 0.69, and the distribution of carbon isotope values of crude oil was from -31.94 ‰ to -30.00 ‰. The Cretaceous crude oils from the east and west were found on some molecular geochemical indicators The difference is that Pr / Ph> 1.4 for eastern crude oil, Pr / Ph <1.2 for western crude oil, 50% -70% for dibenzothiophene in the eastern crude oil and> 80% Hopane / C30 hopane has a value of 0.20-0.23, and the C30 rearranged hopane / C30 hopane value in the western region has a value of 0.08-0.11. Therefore, the Cretaceous crude oil and Ordovician crude oil have the common characteristics of low density, low content Sulfur content, complete n-alkane series and low molecular weight light hydrocarbons, C21 / C23 Cyclotane has a value of <1, and the regular sterane has an asymmetric “V” distribution, a high C29 / C30 hopane number, a high dibenzothiophene content, and a low carbon isotope value, both of which have the same oil source, Genetic type.The crude oil from 6 wells in the eastern Cretaceous of the Tahe oilfield and the 6 crude oil from the west belong to different groups respectively, which may be due to the secondary effect of strata dip or gas invasion.