关键词: 无机成因油气, 昌德气藏, 无机成因气鉴别

Abstract: The research on the abiogenic origin theory in China is in the forward position in the world.Extensive scientific research and practice have proven that a relatively large percentage of hydrocarbons,especially oil,are generated organically.However,this does not rule out the possibility that another large proportion of hydrocarbons,gas in particular,may be of abiogenic origin.The identifications of organic and abiogenic gases are as the follows:1) The abiogenic origin CH₄ has a δ¹³C₁ value greater than -30‰; 2) The abiogenic alkane gases have negative carbon isotope sequences; 3) CH₄/³He values aren×10^5~7; 4) Abiogenic δ13Cco₂ values are greater than -8‰.The Changde Gas Field is possible the first abiogenic hydrocarbon gas field in the world. Favorable locations for abiogenic gas fields can be selected by following criteria:1) Existance of Moho up-pouring or mantle plume; 2) High thermal or thermal structural area with a heat flow value greater than 1.3 HFU and a geothermal gradient higher than 3.5℃/100m; 3)Anomalous R/Ra>1, especially R/Ra>2 zones;4) Presence basalt rock zone along the faults near the gas resource.

Key words: abiogenic hydrocarbon, Changde Gas Field, the identification of abiogenic gas