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采用动力学模拟实验对Ⅰ型干酪根的生烃过程进行了模拟,并对热解产物中的正烷烃组分进行了GC-IRMS分析。分析结果表明,当Ro<1.6%时,C8+正烷烃的碳同位素组成主要继承了母质的特征,而随热演化程度的变化不显著,因此可用于油(气)/源对比。当Ro在1.6%～2.0%之间时,C8+正烷烃迅速裂解,其δ13C显著增重。Ro>2.0%之后,C1—C4气态烃随热演化程度的增加,逐渐富集13C,其δ13C与Ro之间的关系明显受升温速率的影响,所以由模拟实验获得的δ13C1-Ro关系式不适用于高—过成熟的气源岩研究;而δ13C1-F(甲烷生成率)的关系则不受升温速率的影响,适用范围较宽,故可用于高演化阶段的有效气源岩的判识。
Kinetic simulation experiments were used to simulate the hydrocarbon generation process of Type I kerogen. GC-IRMS analysis of n-alkane in the pyrolysis products was carried out. The results show that when Ro <1.6%, the carbon isotope composition of C8 + n-alkane mainly inherits the characteristics of the parent material, but does not change with the extent of thermal evolution. Therefore, it can be used for oil / gas / source comparison. When Ro is between 1.6% and 2.0%, the C8 + n-alkane rapidly cleaves with a significant increase in δ13C. After Ro> 2.0%, the C1-C4 gaseous hydrocarbons gradually enriched with the increase of thermal evolution 13C, and the relationship between δ13C and Ro was significantly affected by the heating rate. Therefore, the δ13C1-Ro relation Which is suitable for the study of high-mature gas source rocks. However, the relationship between δ13C1-F (methane formation rate) and that of δ13C1-F (methane generation rate) is not affected by the heating rate and has a wide range of application. .