The Enping formation of Y structure in block X in the east of the South China Sea develops a lake bottom fan deposit formed by the collapse of large sand rich braided river delta front sand body, which is vertically superimposed in multiple stages and has good superposition. The fluid properties in the block are complex and diverse, and there is a common phenomenon of gas production from oil reservoir and oil production from gas reservoir. The oil and gas layers have similar characteristics in logging data, which greatly increases the difficulty of fluid phase identification in the block, thereby providing certain difficulties to the comprehensive interpretation of logging. In view of the complexity of fluid properties in the study area and the difficulty of accurately identifying oil and gas reservoirs by using conventional gas logging anomaly multiple method, gas ratio method, three?dimensional and geochemical logging data, through the optimization of hydrocarbon component interpretation method based on gas logging, this paper came to the conclusion that Bar chart method and star chart method can quickly and effectively identify oil and gas reservoirs in this block. At the same time, the field application shows that the Bar chart and star chart fluid interpretation and evaluation method based on the difference of hydrocarbon component characteristics in gas measurement can quickly and accurately interpret and evaluate the complex fluid in block X reservoir. The results of interpretation and evaluation while drilling using this method are consistent with the results of testing, and the coincidence rate is more than 87%, which provides a reliable basis for the later reserve evaluation of the oilfield.