Geochemical characteristics and formation process of natural gas in Kela 2 gas field

 On the basis of a large amount of natural gascomponents and the carbon isotope as well as some otheranalysis data in Kela 2 gas field, the geochemical character-istics, source, origin, and formation process of natural gashave been discussed. The components of gas in the field tendto be "dry", and the drying coefficient is close to 1.0. Thecarbon isotope tends to be heavier, for instance, the averageof δ¹³C₁ is -27.36‰ and that ofδ¹³C₂ is -18.5‰. Compre-hensive analysis shows that humic natural gas in the Kuqapetroleum system comes mainly from Triassic and Jurassicsource rocks, and the contribution of Jurassic source rocks tothe pool maybe is more than that of Triassic rocks. The maincause that the gas tends to be dry and bears heavier isotopecomposition lies in the fact that Kela 2 natural gas is the ac-cumulation of late production of humic source rocks, and itis affected by the abnormal high pressure as well. Consider-ing the hydrocarbon generating and structural history, wecan regard the gas pool formation processes as twice fillingand twice adjusting (destroying), that is, the filling anddestroying process in the early Himalayan movement and thefilling and adjusting in the late Himalayan movement.