不同成因天然气的氢同位素组成特征研究进展

THE HYDROGEN ISOTOPIC COMPOSITION OF NATURAL GASES GENERATED FROM DIFFERENT PATHWAY

天然气氢同位素研究是天然气成因理论以及天然气气源对比研究重要的手段和研究方向,氢同位素组成具有较宽的变化范围,可灵敏地反映天然气的成因和演化过程。综述了天然气氢同位素分析技术的进步和生物气氢同位素组成研究、有机热成因天然气氢同位素组成研究、无机成因天然气氢同位素组成研究进展,指出:新的分析技术GC/TC/IRM S实现了氢同位素的在线分析,提高了精度,给天然气氢同位素的研究带来新的机遇和挑战;生物成因甲烷的氢同位素组成和成因类型与共生地层水的δD值密切相关,而且不同的学者提出了不同的δDCH4与δDH2O值的线性关系式;我国生物气资源丰富,不同类型生物气氢同位素研究可为生物气资源勘探开发提供重要的科学信息;有机热成因烷烃气的氢同位素组成主要受源岩沉积环境和成熟度的影响,其δD值随碳数的增加而增加,称之为正常氢同位素序列,天然气氢、碳同位素研究的结合会提供了更多的关于成烃演化和成藏过程的信息;利用氢同位素研究水在成烃演化过程中的作用逐渐成为今后研究的热点;无机成因气的氢同位素研究较为薄弱,总的来说,无机成因甲烷的δD值较有机热成因天然气重。

The hydrogen isotopic composition of biogenic methane is closely related to the methanogenesis pathway and hydrogen isotopic composition of the coexisting water. Different scholars put forward different linear relational expression of δDCH4 and δDH2O. Whiticar etc. （1986） put forward linear relational expression δDCH4 =δDH2O-180‰ for carbonate reduction pathway and δDCH4 =0.25δDH2O-321‰ for acetate fermentation pathway. The application of these two relational expressions is the most extensive. Biogenic gases resources of our country are abundant. The hydrogen isotope research of different kinds of biogenic gases can offer important scientific information for exploration and development of gas resources. The hydrogen isotopic composition of thermal generation gases is influenced by the environment and maturity of the source rock mainly. The combination of carbon and hydrogen isotopic composition can offer a more message about generation and reservoir. More and more scholars focus on the study of the role of water in oil/gas generation. The research is comparatively weak in hydrogen isotope of inorganic gas. Generally speaking, δDCH4 of inorganic gases is relatively weight than organic gases. The progress of the analytical technology of hydrogen isotope is one of the driving force of promoting the hydrogen isotope research. New analytic technology （GC/TC/IRMS） realizes analyzing online, and have improved the precision of the hydrogen isotope analyses, bring new opportunity and challenge to research of the hydrogen isotope of natural gases.