Oil and gas distribution in Lunnan area is very complicate in Tarim basin.Component analysis of the natural gas from the commercial wells in Lunnan area indicates that the gas here contains mostly methane and is typical dry gas.The dry coefficient and the gas/oil ratios decrease from east to west

suggesting a westward gas invasion from the east slope.Combining the fact that abundant pyrobitumen exists in the reservoirs with the ana-lysis of gas characteristics from other areas in Tarim basin

we conclude that gas in Lunan area is cracked gas from crude oils generated by the mature to over-mature Middle-Lower Cambrian source rocks.