从He同位素组成探讨塔里木盆地与东部诸含油气盆地天然气的成气机制

通过天然气中He同位素组成来研究天然气的成气机制。用VG-5400静态真空质谱计测定了采自塔里木盆地古生代和中生代地层中天然气的He同位素,其He/4He=2.58×10-8～8.33×10-8,R/Ra=0.019～0.059Ra,平3均值为0.031Ra,而我国东部几个主要含油气盆地天然气的R/Ra平均比值则变化于1.21～2.30Ra。He同位素组成对比研究表明,东部含油气盆地成烃作用是在幔源热流驱动下热水流体与烃源岩水岩反应形成的,而塔里木盆地成烃热源则主要是盆地地热增温热水流体与烃源岩水岩反应形成的。

Differences of Foring Mechansim of Natural Gas Between Tarim Basin and Several Oil-gas Bearing Basin in Easten China by Helium Isotopic Composition

Foring mechansim of natural gas was studied by helium isotopic composition. Helium isotopic composition of natural gas sampled from Mesozoic and Paleozoic stratum in Tarim Basin was analyzed with a VG-5400 static mass spectrometer. The 3He/4He ratio of natural gas in Tarim Basin rang from 2.58×10-8 to 8.33×10-8, the R/Ra ratio from 0.019 Ra to 0.059 Ra,average 0.031 Ra,The average for R/Ra ratio of natural gas from several oil-gas bearing basin in easten China is from 1.21Ra to 2.30 Ra. The characteristics of helium isotopic composition suggest that the formation of hydrocarbon processed by mantle-drived hydrothermal flow interacted with source rocks, but for Tarim Basin terrestrial heat drived hydrothermal flow interacted with source rocks.