柴达木盆地北缘原油中单体正构烷烃的碳、氢同位素组成研究

以柴达木盆地北缘不同构造带代表性原油作为研究对象,采用GC—TC—IRMS技术对原油中正构烷烃单体碳、氢同位素进行测定。利用样品正构烷烃单体碳、氢同位素组成特征及分布模式,进行原油成因类型划分和对比分析。研究结果表明,正构烷烃可溶有机质的δ13C分布在-36‰～-25‰,δD分布在-180‰～-110‰。对比发现,不同构造带原油中正构烷烃单体碳、氢同位素组成特征上存在着比较明显的差别。以-30‰（δ13C）和-140‰（δD）作为分界,结合同位素曲线的分布型式,可以划分为不同的分布模式判识生烃母质和沉积环境。

Carbon and Hydrogen Isotopic Composition of Individual n-Alkanes for Crude Oil from North Margin of Qaidam Basin

Using GC/C/MS on-line carbon isotope analysis technique,we obtained the carbon and hydrogen isotopic composition of individual n-alkanes for crude oil from different tectonic belts of the north margin of Qaidam Basin.The carbon and hydrogen isotopic composition of n-alkanes for crude oil samples can be used to analyze genetic type of crude oil and oil-source correlation.The analytical results indicate that the δ13C and δD values of n-alkanes in soluble organic matter ranging between-36‰～-25‰ and-180‰～-110‰,respectively.Through comparing,it is found that there exist significant differences between the carbon and hydrogen isotopic composition of n-alkanes for crude oil from different tectonic belts.By the combination of δ13Cn-alkanes(-30‰),δDn-alkanes(-140‰),and distribution pattern isotopic curve,the carbon and hydrogen isotopic composition can be divided into different distribution patterns.Using these patterns can discriminate hydrocarbon generation material and sedimentary environment.