Designing and Selecting Demulsifiers for Optimum Field Performance on the Basis of Production Fluid Characteristics

Summary A method for characterizing and predicting the performance of emulsion breakers has been developed that involves the relationship between the preferred alkane carbon number (PACN) of the demulsifier and the equivalent alkane carbon number (EACN) of the crude oil and the salinity of the emulsified aqueous phase. This procedure can be used both to choose the proper demulsifier for field use and to develop effective new compounds by determining the effect of changes in molecular architecture and interfacial properties on performance. Parameters studied include chemical type, molecular weight, degree of branching, partition coefficient between the water and oil phases, interfacial-tension (IFT) reduction, and interfacial-viscosity changes. The importance of each of these properties to performance is discussed.