咸阳市区富氦水溶气组分特征及成因分析

The Constituents Characteristics and Genetic Analysis of Water-soluble Helium-rich Gas in Xianyang

咸阳市区位于渭河盆地中部,其地热资源丰富。在开发过程中发现地热水中普遍伴生有天然气,其组分多样、成因复杂。通过对咸阳市区34口地热井天然气样组分及碳同位素分析,结果认为,市区内地热井天然气主要以氮气(大部分在70%~90%)、甲烷(10%左右)为主,氦气(2%左右)含量普遍偏高;甲烷主要以煤成气混无机成因气为主。大部分地热井伴生气中氦气属于典型的壳源氦,个别属壳源气混有极少量幔源气。

Xianyang is located in the middle of Weihe basin with rich geothermal resources.In the course of development,natural gas is commonly associated with geothermal water,and the components are diverse and the causes are complex.Based on the analysis of gas sample composition and carbon isotope of 34 geothermal wells in Xianyang city,it is concluded that,the gas content of geothermal wells in the city is mainly nitrogen(most are around 70%~90%)and methane(about 10%),and the helium content is generally high(about 2%).Methane is mainly coal-genetic gas mixed with inorganic gas.The helium in most geothermal well associated gas belongs to the typical shell source helium,and some shell source gas is mixed with a very small amount of mantle source gas.