碳同位素分馏效应与准噶尔盆地车排子地区轻质油来源分析

Carbon Isotope Fractionation and Its Application in Studying the Light Oil Origin of Chepaizi Uplift in Junggar Basin

摘要: 本文通过对烃源岩物理模拟排出产物族组成碳同位素分析，发现成熟过程中原油饱和烃、芳烃δ¹³C会发生明显分馏，结合准噶尔盆地原油饱和烃、芳烃δ13C与族组成的相关关系分析认为：原油组分及其碳同位素特征在成熟演化过程中会因分馏效应发生明显变化，在以轻质烃类为主要成分的轻质油中，不能有效确定其成熟度的情况下，碳同位素组成不能作为油源对比的主要指标。因此，对车排子轻质油来说，不能以碳同位素值确定其来源于侏罗系煤系烃源岩或以其为主的混原油，其来源为二叠系高过成熟烃源岩可能性大。

Abstract: Based on the isotope data of group components of source rock’s physical simulation product, it was found that the δ13Cvalue of saturated and aromatic hydrocarbons showed obvious fractionation. Meanwhile, according to the δ¹³Cvalue of saturated and aromatic hydrocarbons as well as the group composition data of the oil in Junggar Basin, it was also found that the value and data changed visibly with the fractionation effect in evolution process. So, carbon isotope data cannot serve as a main index in oil and source rock correlation for the light oil mainly with light hydrocarbons in the case of not determining the oil’s maturity. As for the light oil in Chepaizi Uplift, its carbon isotope data cannot be as a proof to determine that it was totally or mainly derived from the Jurassic coal-bearing source rocks. On the contrary, the light oil was more likely from the Permian source rocks than from post maturity.