Sultan K oilfield is a low salinity and middle permeability sandstone reservoir. According to the characteristics of the reservoir,when determining the original oil saturation of oil reservoir,using Indonesia formula to explain water saturation in reservoir by logging method. On the basis of this research,the author combined the K oil capillary pressure and RFT data,and studied the method to determine the original oil saturation of reservoirs by using the J function. this method can make up the defect of we...