天然气中轻烃单体氢同位素分布规律及其应用研究

Light hydrocarbon (LH) associated in natural gas contains a wealth of geochemical information for gas source correlation, maturity forecasts and secondary effects, which has a wide application prospect. Althrough a few analytical methods of LH in the oil and rock have been reported in recent years, but due to the particularity of natural gas samples and the characteristics of hydrogen isotope fractionation effect, accurate compound specific hydrogen isotope analysis (CSHIA) of LH in natural gas has not been realized by the existing technologies. This project intends to utilize the gas circuit switching principle of six-way valve and combinate activated carbon adsorption enrichment techology to build an offline preconcentration device and establish its CSHIA method of LH in natural gas. Based on this method, the distribution rules of compound specific hydrogen isotopes of LH in the typical chinese coal-type gas, oil-type gas and biogas will be studied, the relationship between organic matter type, depositional environment, maturity and compound specific hydrogen isotopes of LH, as well as various identification standards, will be established for technical support in natural gas exploration and development.

天然气伴生轻烃含有丰富的地球化学信息，在天然气藏的来源判识、成熟度预测以及次生作用的影响等方面有广泛应用前景。虽然近年来已经报道了多种原油和烃源岩中轻烃的分析方法，但是因为天然气样品的特殊性以及氢同位素分馏效应的特点，现有分析技术还不能准确测定天然气轻烃单体氢同位素。本项目拟利用六通阀气路切换和活性炭吸附等技术建立离线轻烃单体氢同位素分析方法；以该方法为基础开展中国典型煤型气、油型气和生物气藏中伴生轻烃的单体氢同位素特征研究，建立其与有机质类型、沉积环境和成熟度之间的关系图版及多种判识标准，为天然气勘探开发提供技术支撑。

天然气伴生轻烃含有丰富的地球化学信息，在天然气藏的来源判识、成熟度预测以及次生作用的影响等方面有广泛应用前景。项目组通过优选吸附材料和冷却剂、考察多种色谱和质谱参数、研制和改造分析设备，建立了测定天然气中轻烃单体氢同位素的分析方法。以该方法为基础，对我国鄂尔多斯盆地、四川盆地、辽河盆地和塔里木盆地的典型煤型气、油型气和生物气进行了气体组分分析和单体碳、氢同位素分析，对相关地层水等地质样品进行了地球化学分析。实验结果为现有的认识进行了补充，为轻烃与有机质类型、沉积环境和成熟度之间的关系图版及判识标准建立了初步基础，也为天然气勘探开发提供了一定的技术支撑。