碳同位素在天然气运移路径示踪中的应用研究进展

A Review of the Application of Carbon Isotopes in Tracing the Pathway of Natural Gas Migration

碳同位素在天然气运移路径示踪中的应用十分广泛,以游离相运移的天然气,运移过程中碳同位素的分馏主要受“质量分馏效应”控制;以水溶相运移的天然气,运移过程中碳同位素的分馏主要受“溶解分馏效应”控制。天然气运移中碳同位素的分馏程度不仅与气体分子质量、气体分子水溶解度等物理化学性质有关,同时也受天然气运移距离、输导层物性等外部环境条件的影响。常用的天然气运移路径示踪参数有δ13C1、δ13C2-δ13C1、δ13CO2及储集层中自生方解石的碳同位素。对研究现状分析后提出运移相态识别、碳同位素失真分析是应用碳同位素示踪天然气运移路径的基础,非烃碳同位素、多参数对比是碳同位素示踪天然气运移路径研究的未来趋势。

Carbon isotope is widely used in tracing the pathway of natural gas migration.For free phase natural gas,carbon isotope fractionation in the transport process is mainly controlled by the "mass fractionation effect",whereas carbon isotope fractionation of water-soluble natural gas in the migration process is mainly controlled by the "solubility fractionation effect".The degree of fractionation of carbon isotope during the natural gas migration is mainly affected by the molecular mass,solubility and other physicochemical properties of the gas.External environmental conditions such as the migration distance of natural gas,physical properties of the transport layer also play important roles in the fractionation of carbon isotopes.Parameters of natural gas,including δ13C1、δ13C2-δ13C1、δ13CO2 and carbon isotopes of calcite in the reservoir,have been widely used in tracing the pathway of natural gas migration.On the basis of the review of recent researches,we suggested that the identification of transport phases,later effects on carbon isotopic composition are the basis of application of carbon isotopes in tracing natural gas migration pathways.In the future,carbon isotopes of non-hydrocarbon materials and multi-parameter comparison would show great advantages in the application for the tracing of natural gas migration pathways.