Abstract: Improved performance in the phase separation of aqueous brines from hydrocarbons within an electrostatic desalter operation is obtained by the addition to the crude oil emulsions entering the desalter of an effective asphaltene dispersing amount of an alkyl phenol-formaldehyde liquid resin polymer, optionally in the presence of a lipophilic/hydrophilic vinylic polymer. The preferred resin is a nonyl phenol-formaldehyde resin having a molecular weight of from 1,000-20,000, and the preferred vinylic polymer is a copolymer of lauryl (meth)acrylate and hydroxyethyl (meth)acrylate. Best results from the electrostatic desalter are obtained when also using a demulsifier chemical treatment along with the asphaltene dispersing treatments. Desalter efficiency is increased and desalter brine effluent quality is greatly increased.