Li Wei (李伟)1*, Shi Baohong (时保宏)1, Chen Jianfa (陈践发)2
(1 School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an 710065,Shanxi, China
2 College of Geosciences, China University of Petroleum, National Key Laboratory of Petroleum Resources and Engineering, Beijing 102249, China)
Abstract: The geochemistry of the noble gases has long been used in the study of the deep Earth mate-rial and meteorites. Recently, it was used in the research of natural gases owing to the development of polish instruments. By the most advanced noble gas mass spectrometer, the abundance and isotope compositions of the noble gases were analyzed about natural gas samples those were collected from the deep of Songliao Basin, China, in order to know the orgin of natural gases those distribute in the deep of rift basins. The study shows that the abundance of noble gases tends to decrease from light to heavy rare gases, and the abundance of He, Ne, Ar, Kr, Xe is respectively 2.87×10-4, 2.39×10-4, 2.20×10-4, 2.67×10-7, 2.37×10-8. The ratio of 3He/4He, 20Ne/22Ne, 21Ne/22Ne, 40Ar/36Ar is respectively 2.64×10-6, 9.94, 0.02922, 743.7 and the hinger abundance of 80Kr, 84Kr, 86Kr, 131~136Xe than atmospheric prove that the natural gases were mantle-derived. The compositional characteristics of alkanes and noble gases gives a reasonable explanation of the inorganic origin of the natural gases endured through a crust-mantle mixing. Mantle-derived He in CO2 gas reservoirs of Changling fault trap accounts for 40% and contrastly 26% in the hydrocarbon gas reservoirs, and occupies 13% in Xujiaweizi trapped gases. Comparison of the ability of distinguishing gas types shows that the composition of heavy noble gases is not significantly different in all sorts of natural gases which can be well differentiated by the light noble gases. Noble gas isotopes also play an unique role in identifying the genesis of natural gas, distinguishing natural gas types, and symbolizing the tectonics in addition to be applied in tracing the source of nature gases.
Keywords: Noble gas；Isotope of Noble gas；Helium source；Crust-mantle mixed origin Songliao Basin
Author Profile (first and corresponding author):
Li Wei (李伟) , Male, Lecturer, Ph D student, mainly engaged in natural gas geochemistry research.
E-mail:494039501@qq.com.
