The Kela-2 gas field is located in the center of Kelasu structural belt in Kuqa Depression. This trap is one of a series of traps in the folded belts which are distributed in a string of pearls in the dual structure. The primary gas- bearing layers are sandstone of Lower Cretaceous K1bs while the secondary layers are dolomite member and glutenite member of Lower Tertiary E1-2km and sandstone of Lower Cretaceous K1b. The main component of natural gas is methane whose content is higher than 97%. It is characterized by dry gas whose source rock is Jurassic coal measure. The Kela-2 structural trap was formed during the Xiyu period and then became a reservoir in the late time. The reservoir formed late and the thick seal rock of Lower Tertiary gipsmantle are the avail reason why the giant Kela-2 gas field has been well kept. The abnormal high pressure of the Kela-2 gas field results from the strong structural compression in the northern part during the Xiyu period.