Demulsifier performance at low temperature in a low permeability reservoir

The crude oil in Longdong area is produced in the form of emulsion containing associated oil and water, which needs to be separated before dispatch to end user. Chemical demulsification under high temperature is the most widely used technology to break the emulsions. In this study a rheological method was used to determine the curve of viscosity-temperature and lower limit of temperature was determined. A series of experiments on low-temperature commercial demulsifies were implemented for studying demulsification performance by bottle test method. Mechanism of low-temperature demulsifier was studied by using spinning drop interfacial tensiometer to determine interfacial tension between the crude oil and demulsifier solution by considering the concentration. Turbiscan stability analyzer was used to study the effect of water content, temperature, and demulsifier concentration on emulsion stability. The corresponding relationship between interfacial tension and demulsification was verified through the study of low-temperature demulsifier effect on interfacial tension. Efficient low-temperature demulsifiers AR102, AR901, PR929, and PRC06 were selected. PRC06 was chosen to be the best at 40°C, and when the optimal concentration was 200 mg/L, dehydration rate was 99.51%.