煤岩显微组分模拟实验气态产物碳氢同位素特征

Carbon and Hydrogen Isotopes of Gaseous Products from Coal Maceral in Simulation Experiments

碳氢同位素研究是油气地球化学研究的一个重要方面。通过对神山褐煤镜质组与丝质组中碳氢同位素的分析得出:同一温阶,镜质组和丝质组气体产物中甲烷及其同系物具有与天然气相似的碳同位素分布特征,随烷烃分子碳数增加而逐渐增高,即δ13C1<δ13C2<δ13C3;不同温阶时,气体产物中甲烷及其同系物的δ13C具有明显的同位素分馏特征,即随温度的增加δ13C1、δ13C2、δ13C3值相应增高。而对镜质组与丝质组气体产物中的δD而言:同一温阶,具有δDH2<δD1<δD2<δD3<δD4的规律;不同温阶,随温度的增加,δDH2、δD1、δD2、δD3、δD4值相应增高,也表现出明显的同位素分馏特征。

Carbon and hydrogen isotope is an important tool for gas geochemistry. In this paper, carbon and hydrogen isotopes of gas products from vitrinite and fusinite isolated from lignite coal in Shenshan were measured. The result showed that δ^13C values of methane and its homologues in gaseous products have a similar tendency of carbon isotope of alkane gases in natural gas at the same temperature, in which δ^31C values become heavier with carbon number, i.e. δ^13C1 〈δ^13C2〈δ^13C3. Meanwhile, δ^13C values of methane and its homologue δ^13 C1 , δ^13 C2, δ^13 C3） in gaseous products become heavier with increase of simulation temperature. In addition, 3D values in gaseous products generated from vitrinite and fusinite has a serial of δDH2〈δDC1 〈δDC2 〈δDC3 〈δDC4 at the same temperature, and the same change of 3D values in gaseous products is observed with increasing temperature, i.e. δDH2〈δDC1 〈δDC2 〈δDC3 〈δDC4.