准噶尔盆地西北缘油气运移的地球化学研究

GEOCHEMICAL STUDY OF OIL/GAS MIGRATION ON THE NORTHWEST EDGE OF JUNGGAR BASIN

王屿涛 惠荣跃

Wang Yutao Hui Rongyue

新疆石油勘探开发研究院 克拉玛依 834000 2. 中国科学院兰州地质所 兰州 731111

Xinjiang Institute of Petroleum Exploration and Development 2. Lanzhou Institute of Getdtigy, Academia Sinica

本文以准噶尔盆地西北缘克-乌断裂上、下盘八区—六区油藏剖面为例,系统采集了二叠系—侏罗系13个原油样品,进行原油物性和地化性质分析。研究表明,沿油藏剖面八区—六区原油密度逐渐增大,极性化合物和低分子异构烃以及生标物组成中妊甾烷等化合物逐渐富集,运移过程中可能存在多种体制,即低碳数烃类由温度、压力的降低及系统的相对开启发生分子扩散,高碳数多环烷烃由于地层层析作用而发生化合物分馏以及浅部储层发生微生物降解作用。油气运移的地球化学特征,排除了油区内存在源区的可能性。进一步佐证了玛湖凹陷是克一乌断阶带的油源区。

Taking the oil pool profiles of No.8-No.6 regions on the upper and lower plates of Ke-Wu Fracture on the northwest edge of Junggar Basin for example.thirteen Permian-Jurassic crude oils are sysematically sampled in this paper,and the physical and geochemical properties of crude oils are analysed, it is revealed that the crude oil density of No.8-No.6 regions gradually increases and polar compounds, low-molecular isohydrocarbons and pregnanes in the components of biomarkers are gradually enriched along the oil pool profiles ;besides.varied systems could exist during migration,that is to say.low carbonate hydrocarbons are caused molecular diffusion by decreases in temperature and pressure and the relative openness of systems,high carbonate polycyclic naphthenes are led to the frac tional distiolation of compounds due to stratiform segregation, and microbial degradation occurs in shallow reservoirs. The geochemical characteristics of oil/gas migration rule out the possibility that there are sourcelands within oil areas and further evidence that Lake Ma Depression is the oil source area of Ke-Wu Fault Terrace zone.

https://doi.org/10.11781/sysydz199503265