Sanzhao sag in Daqing oil region is found to contain many small-to middle-sized gas fields.Analysis shows that there are gas of both inorganic and organic origins and the natural gas is composed of both alkane and non-hydrocarbon gases.The later contains not only conventional non-hydrocarbon gases like carbon dioxide

hydrogen

nitrogen

and etc

but also rare gases

such as helium

argon

and even neon.Rare gases

rare-earth elements

and isotopes of some elements

can be used to determine the sources

migration mechanisms

and enrichment patterns of hydrocarbons and metal deposits.By applying this principle to the analysis of hydrocarbon gases

non-hydrocarbon gases and the isotopes of rare gases

both the hydrocarbon gases and non-hydrocarbon gases are determined to be mainly inorganic gases sourced from the deep of the earth.They occur both in the exploration area and in the developed oilfields.In recent years

Daqing Oilfield has witnessed an increase of non-hydrocarbon gases with higher production of associated gas.In addition

the geochemical behaviors of these gases also indicate an inorganic origin

quite different from that of crude.