Abstract: For complex oil and gas reservoirs with gas-liquid interlacing state, the common phenomenon of gas inoil layer and oil in gas layer makes it very difficult to identify fluid phase.The lack of knowledge of fluid type will bring confusionto the determination of reserves.In order to quickly identify the fluid phase in the reservoir with oil and gas, based on the differences of hydrocarbon component characteristics measured by gas logging, the Star diagram method; Bar diagram method and FLAIR oil, gasand water index method are proposed, which can effectively identify the fluid phase change characteristics in the reservoir.The proposed method is used to analyze the fluid phase of the buried low-porosity and low permeability glutenite and burial hill in the Bozhong 19-6 structure.The results showed that the fluid phase of the deep reservoir is gas phase with local oil ring, and the fluid property is mainly condensate gas containing condensate oil.The resultsare consistent with the oil testing conclusion.The proposed method can be used to quickly and accurately identifyand evaluate the fluid phase state in the reservoir of complex structure.