Abstract: The natural gas in Wu-Xia area is dominated by methane wet gas of high maturity with dry coefficient of 0.8801, V(iC₄)/V(nC₄) of 0.88, V(iC₅)/V(nC₅) of 0.99 in average. Its non-hydrocarbon gas contains high content of N2, less CO2, micro-O2 and free H2S. With increase of the depth, the relative density, dry coefficient, methane content, heavy hydrocarbon gas content and non-hydrocarbon gas content have 7 changing trends by regularity. The natural gas is characterized by δ¹³C₁<δ¹³C₂<δ¹³C₃<δ¹³C₄ and the alkane gas is original organic genetic gas. The source rocks produce gases in low-matured and matured stages with Ro from 0.21% to 1.66%. According to the relationship between δ¹³C₁ and δ¹³C₂-δ¹³C₁ as well as δ¹³C₁ vs. V(C₁)/V(C₂₊₃), it is judged that the origin of natural gas belongs to associated gas of crude oil, and a small amount of associated gas of condensate oil may occur in Wu-32 Wellblock.

Key words: Junggar basin, Wuerhe-Xiazijie area, natural gas, geochemistry, genetic type