Abstract:

There exist extensively oil and gas dispaly in Eogene of Xiangcheng Depression.The crude oil is characterized by high density,high viscosity,high bearing-sulphur and high bearing-wax,which indicates that it is immature to low-mature.Based on the main geologic conditions of regional tectonic setting,organic geochemistry characteristics of source rocks and crude oil,sediment environment and the abundance and type of organic matters in source rocks were analyzed using the organic maceral analysis,biomarkers and organic petrography in Xiangcheng Depression.The main geological conditions for forming immature to low-mature oil in Hetaoyuan Group of Xiangcheng Depression were discussed.The result showed that sedimentary environment of Hetaoyuan Group were brackish to saline water lake facies belonging to deoxidize to strong deoxidize,and the main hydrocarbon-generating material was alga,cortical tissue and cutinite of organic matter from continent and some kinds of bacterium.The result also showed that Eh₂ was the main target sequences,and oil and gas reservoirs with the features of short oil-migration and handy accumulation,self-generating and self-preserving were the main explored target.

Key words: Xiangcheng Depression, geological condition of source rocks, maceral, immature to low-mature oil, organic geochemistry features

摘要：

襄城凹陷下第三系油气显示较为广泛,原油性质呈高密度、高黏度、高含硫、高含蜡的特点,为典型的未熟—低熟油。根据襄城凹陷所处的区域构造背景及烃源岩和原油的有机地球化学特征,采用有机显微组分分析、生物标志物检测、有机岩石学研究等方法,对源岩的沉积环境、烃源岩特征以及生烃母质来源进行了深入分析,探讨了未熟—低熟油油藏形成的主要地质条件。研究结果表明,核桃园组多为半咸水—咸水湖相和盐湖相沉积,属于还原—强还原环境; 形成未熟—低熟油的主要成烃母质是藻类,陆源有机质中的木栓质体、角质体和各种细菌;应以核二段为主要目的层,以寻找短距离运移、聚集及自生自储油气藏为主。

关键词: 襄城凹陷, 烃源岩地质条件, 显微组分, 未熟—低熟油, 有机地球化学特征