天然气中Ar同位素测量的新技术

A NEW TECHNIQUE FOR MEASURING ARGON ISOTOPE IN NATURAL GAS

孙明良

SUN Ming-liang

中国科学院兰州地质研究所, 气体地球化学国家重点实验室, 甘肃, 兰州, 730000

State Key Laboratory of Gas Geochemistry, Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China

由于天然气的Ar浓度一般在n×10-4～n×10-5范围内,而空气的Ar浓度为9.3×10-3,比天然气的高2～3个量级,所以从野外采样到实验室检测的全过程中,减少和防止空气Ar对样品Ar的污染始终是Ar同位素准确测量的核心技术.资料显示,国内外的一些有关实验室还没有很好地完善该项实验技术.作者在实验中边检测边查找问题边改进,建立了能基本上防止空气Ar对天然气Ar污染的新技术,并取得了令人惊喜和可信的天然气Ar同位素分析结果.该项新技术主要包括高压钢瓶采样、高真空低漏率的进样系统、降低仪器系统的本底与漏率、防止实验室环境波动等内容.

The Ar concentration in natural gases ranges from n×10-4～n×10-5,while that in the air is 9.3×10-3,which is in 2 to 3 orders of magnitude higher than that of the former.Reducing and preventing natural gas Ar being contaminated by atmospheric Ar during sampling in the field and detecting in laboratories is a key technique for the accurate measurement of Ar isotope.Presently there are no perfect above-mentioned techniques at home and abroad.We tried and improved the measurement method several tens of times,and finally we set up a new technique which can prevent natural gas Ar being contaminated by atmospheric Ar and obtained the surprising and convincing analytic results of natural gas Ar isotope.The technique includes sampling using high pressure steel vases,injecting samples under the conditions of high vacuum and low seepage rate,reducing background values of the instrument and preventing the fluctuation of the environment of laboratory.

“九五”国家重点科技攻关项目“中国大中型气田勘探开发研究”(99-110-01-03)

https://doi.org/10.11781/sysydz200104452