Abstract: Owe to nonconductivity of oil and gas,there is usually little differences between their displays in resistivity logs. Therefore conventional log analysis method developed by resistivity log using water saturation can only distinguish hydrocarbon zones from non—hydrocarbon zones,but cant tell oil zones from gas zones. Through the analysis of resoponse characteristic to oil and gas zones in domestic logs of Triassic in Xiazijie oilfield, this paper suggests that by combination of neutron gamma log and sonic log we could further distinguish oil zones from gas zones after we found hydrocarbon zones in Triassic of Xiazijie oilfieJd by resistivity and sonic logs. Examples showed in the paper tells good results.