In order to understand the generation and distribution of natural gas in the northern margin of the Qaidam Basin

the geochemical characteristics of natural gas are analysed with both natural gas composition and carbon isotope.The results show that the natural gas is dominated by methane

but the content of heavy hydrocarbons is relatively high.There are obvious differences in natural gas composition in different structural belts.Research on carbon isotopes indicated that the δ

13

C

1

and δ

13

C

2

values are -36.4‰~-19.3‰ and -27.4‰~-19.82‰

respectively.The identification of na-tural gas shows that the main type of natural gas in this area is coal-generated gas and is derived from Jurassic source rocks.Carbon isotopic distribution of the northern margin of the Qaidam Basin is characterized by positive sequence

and there are carbon isotope reversal phenomena in some areas due to different maturity

different mixture types of sources and the gas generation from source rocks in the high-mature stage.The distribution of oil and gas reserves in the northern margin of the Qaidam Basin is characterized by spatial zonation from the outer edges to the centre of the basin and is controlled by the source rock maturity.The natural gas is located in mature and high maturity areas.Future promising areas for exploration have been put forward

which include Lenghu NO.6 and NO.7

Eboliang-Hulushan tectonic belt and the foreland of the Altun Mountains.