【摘要】 前人对塔里木盆地以及英买力地区个别井区的油气地球化学特征已经进行过研究,但对于整个英买力地区天然气的地球化学特征却还未作系统研究。英买力地区位于塔北隆起西部,该区天然气组分以烃类气体为主,烃类气体中甲烷含量占绝对优势,非烃气体主要为N2和CO2;天然气干燥系数整体较低,属于典型的湿气。对其天然气成因、来源进行分析表明,该区天然气大部分为来自库车坳陷的煤型气,部分为典型油型气与煤型气的混合气。该区大部分天然气烃类碳同位素特征为正序分布,部分天然气甲烷系列同位素组成存在"倒转"现象。造成这种"倒转"的主要原因有:①天然气逸散造成的同位素分馏效应;②不同类型天然气混合。此外,根据δ13C1值计算的镜质体反射率结果得出,该区天然气为烃源岩处于成熟—高成熟演化阶段的产物。更多还原

【Abstract】 There are many research achievements in respect of the geochemical behaviors of oil and gas in the Tarim basin,and some in respect of that in specific wellblocks in the Yingmaili area,but none in respect of that in the Yingmaili area as a whole.The Yingmaili area is located in the western part of the Tabei uplift,where the major components of natural gas are gaseous hydrocarbons dominated by methane,while its minor components are non-hydrocarbon gases dominated by N2 and CO2.The dryness of the natural gas is relatively low as a whole,indicating typical wet gas.Analysis on the genesis and sources of the natural gas reveals that most of them are coaliferous gas sourced from Kuqa depression and some are typical mixture of oil-type gas and coaliferous gas.The carbon isotope of hydrocarbons in most natural gas in the study area show normal distribution,i.e.,δ13C1<δ13C2<δ13C3,while that of some methane series of the natural gas show "reverse" distribution,the main causes of which include isotope fractional distillation resulted from gas effusion and mixing of different types of gases.Moreover,the vitrinite reflectance calculated by using δ13C1 values show that the natural gas in the study area is generated by the source rocks in mature to highly mature evolutionary phases.更多还原