STUDY OF DEMULSIFICATION OF WATER-IN-CRUDE OIL EMULSION

Demulsification of water-in-crude oil emulsion was studied at two different salinities, 0.5% and 10% sodium chloride, using five different nonionic surfactants. Equilibrium crude oil-water interfacial tension was measured with drop volume method. Low molecular weight surfactants were found to be completely ineffective as demulsifiers. Three surfactants which were effective demulsifiers, exhibited good interfacial activity, surface adsorption and surface pressure. The performance of the demulsifiers changed with change in salinity of aqueous phase. Surfactants effective as demulsifiers reduced surface tension of water by more than 25 dynes-cm-1. For a given crude oil-water system, the surfactant which developed surface pressure in excess of 15 dynes-cm-1 was found to be good demulsifier for that system. Based upon these studies, a physical model of demulsification has been proposed.