中国大陆含油气盆地的氦同位素组成及大地热流密度  

HELIUM ISOTOPES AND HEAT FLOW IN THE OIL AND GAS BEARING BASINS IN CHINA'S CONTINENT

作　　者：杜建国[1] 徐永昌[2] 孙明良[2] 

机构地区：[1]国家地震局分析预报中心,北京100036 [2]中国科学院兰州地质研究所,兰州730000

出　　处：《地球物理学报》1998年第4期494-501,共8页Chinese Journal of Geophysics

基　　金：国家科技攻关(85-102-15-02-01);国家基金(49273185)

摘　　要：根据天然气中氦同位素组成,讨论了中国大陆主要含油气盆地氦同位素地球化学特征与大地热流密度。不同地区425个~3He/~4He 值表明中国含油气盆地天然气的氦同位素组成变化范围较大,为4.0×10^(-9)—7.21×10^(-6),在统计直方图上呈现三个峰值:1.5×10^(-8),3.0×10^(-7)和1.5×10^(-6)。中国东部大陆裂谷系中、新生代盆地内天然气的~3He/~4He 值分布范围为1.02×10^(-7)—7.21×10^(-6),50%以上大于大气的值(1.4×10^(-6));其他地区含油气盆地天然气的~3He/~4He 值分布范围为4.0×10^(-9)—7.01×10^(-7),全部小于大气的~3He/~4He 值。根据天然气中~3He/~4He 值计算的大地热流密度值分布在30—82mW/m^2 之间。利用~3He/~4He 值计算的大地热流密度值与用其他方法测得的值相一致,在中国大陆水平方向上呈现"东高西低"的变化趋势。The paper discusses the distribution of helium isotopes in natural gas and heat flow of oil and gas beating basins in China's Continent.Statistical results of 425 helium isotope ratios show that the ~3He/~4He values of natural gases from different parts of China have a wide range of 4.0×10^(-9)—7.21×10^(-6),and there are three peak values on the histograms:1.5×10^(-8),3.0×10^(-7) and 1.5×10^(-6).~3He/~4He values of natural gases in the continental rift valley are between 1.02×10^(-7) and 7.21×10^(-6) of which more than 50 percent is higher than that of atmosphere (1.4×10^(-6)).The helium isotope ratios of natural gases from other parts of China scatter from 4.0×10^(-9) to 2.35×10^(-7).Natural gases from unstable tectonic ragions in Cenozoic era have higher ratios of helium isotopes than those from stable tecotonic ragions.There is a good correlation between ~3He/~4He values and heat flow in most of the continental sediment basins.The calculated values of heat flow in the oil and gas beating basins have a range of 30—82mW/m^2 which is concordance with the measured values within the accuracy of ±3.5—7mW/m^2 for determinating heat flow.The estimated values of heat flow reveal a decreasing trend from the Eastern to Weastem China.

关 键 词：天然气 氦同位素 大地热流密度 含油气盆地 

分 类 号：P618.130.4[天文地球—矿床学] P314.2[天文地球—地质学]