FORMATION CONDITIONS AND MAIN CONTROLLING FACTORS OF LARGE GAS FIELDS IN CHINA

The large gas fields in China are mainly located in gas generating centers and their surrounding areas(with gas generating strength bigger than 20 bcm/km2),traps related to the paleohighs in coal-formed gas generating areas,or traps above or beneath coal measures,big areas of pore-type reservoir bed in gas generating areas,and low gas potential areas.What's more,the gas fields should be accumulated in late period.With these formation conditions and controlling factors,7 large gas fields with the reserves over 1000 bcm have been discovered since 1996,including the Kela 2,Dina 2,Sulige,Jinbian,Zizhou,Yulin,Wushenqi,Puguang and Qingshen large gas fields.Theoretically and practically the study on the formation conditions and controlling factors of large gas fields is of great significance to the natural gas industry in China.The gas production will be 500×108 m3 to the year of 2005.