库车坳陷却勒1油藏原油地球化学特征与来源研究

Geochemical Characteristics and Origins of Crude Oil from Quele-1 Reservoir in Kuqa Depression

研究了库车坳陷却勒1油藏原油生物标志化合物组成特征,在此基础上分析了原油成因类型,认为其属于＂煤系原油＂,主要来源于煤系泥岩。原油三环萜烷系列含量低且呈C19-C26阶梯状依次降低,C24四环萜烷含量远高于C26三环萜烷,甾烷以C29为主,C27含量也较高,甾/藿比值低,这些特征表明其母质主要由高等植物及细菌类组成,但低等水生藻类也有一定贡献。原油姥植比较高、伽马蜡烷含量低、重排生物标志物含量丰富,说明其有机质沉积于富含粘土矿物的弱氧化淡水湖沼相环境。油源对比分析认为,下侏罗统阳霞组煤系泥岩生物标志物组成与却勒1油藏原油相似,是其主要烃源岩,油源来自于库车坳陷中西部。

Based on the distribution and composition of the biomarkers and the analysis of genetic type of the oil from Quele-1 Reservoir,it was proved that the oil was coal-type and was generated mainly from coal-mudstones.It was of lower tricyclic terpane series with step style(C19>C20>C21>C23>C24>C25>C26),higher content of C24 tetracyclic terpane,higher ratio of C27 toC29 steranes(0.62) and lower ratio of steranes to hopanes(0.2).These features indicated that its organic matters of source were composed mainly of higher plant and bacterial and little of lower algae.The lower content of gammacerane,higher ratio of Pr to Ph and content of various biomarkers with rearranged configuration in the oil indicated that its source rock was deposited under sub-reduced and clay-rich limnetic facies environment.The results of analysis and correlation between oil and source rocks show that the oil originated dominantly from the Jurassic coal-mudstones(J1y) of Yangxia Formation located in the mid-west of Kuqa Depression.