天2井原油生物标记化合物与油源研究

Biomarker characteristics and Origin of Crude Oils from Well Tian 2

采用定量气相色谱质谱技术，剖析了天2井原油的生物标志物组合特征并追踪了其油源。研究结果表明，天2井原油中C31-C35藿烷丰度依次降低，含有较高丰度的伽马蜡烷，无重排藿烷和重排甾烷，C27-C29规则甾烷呈反“L”型分布，C28甾烷丰度较高。甾烷的异构化成熟度参数、甲基菲指数均暗示原油成熟度低。在对本区可能烃源岩生物标志物组合特征广泛调查的基础上，从生物标志物指纹和绝对浓度特征确认了天2井原油与下白垩统巴音戈壁组下段烃源岩有成因联系，指出巴音戈壁组下段烃源岩为天草凹陷主力烃源岩。

The biomarker assemblage characteristics and origin of crude oils in Well Tian 2 in Tiancao Sag were studied by using quantitative gas chromatography-mass spectrometry analysis.The geochemical characteristics were described as follows: abundance of hopanes from C31 hopane to C35 hopane decline gradually, gammacerane with higher abundance, the absence of rearranged hopane and rearranged sterane, reverses shape of 'L' in the distribution of C27~C29 sterane and higher abundance of C28 sterane.Sterane isomerization parameters and alkyphenanthrene index l indicate that the maturity of crude oil is low.On the basis of comprehensive analysis of the biomarker assemblage characteristics of possible source rocks in this region, and from the characteristics of biomarker fingerprints and their absolute concentrations, it is affirmed that there is a genetic relationship between crude oil of Well Tian 2 and the lower part of source rocks in Bayingobi Formation of lower Cretaceous.It is pointed out that source rocks of lower part of Bayingebi Formation are the main source rocks of Tiancao Sag.