Abstract: Halahatang oilfield in Tarim basin is a fractured?vuggy carbonate reservoir with complex communication between fracture and vug systems, in which the different systems have obvious differences in oil saturation pressure and fluid property. This paper presents the empirical formulas for oil saturation pressure calculation in the different blocks using the initial solution gas?oil ratio and saturation pressure data available in this oilfield. The calculated result shows that the accuracy given from these formulas is higher than that from those at home and abroad. Based on the calculated saturation pressure and the measured reservoir pressure data, whether or not a reservoir enters into a stage of dissolved gas drive can be determined, providing basis for maintaining the reservoir pressure by in?advance water injection process, rational development decision?making and EOR