FIELD: crude oil treatment. SUBSTANCE: demulsifier is prepared by interaction of a branched polyether with p- tolylene diisocyanate in presence of cellulose, said branched polyether being polyether prepared by alcoholate polymerization of either propylene oxide with glycerol or ethylene oxide and propylene oxide with glycerol, or propylene oxide with glycerol followed by block copolymerization with ethylene oxide and molar ratio polyether/p- tolylene diisocyanate/cellulose being 1:(1-2):1. Interaction product is then mixed with linear polyether prepared by alcoholate polymerization of ethylene oxide and propylene oxide with ethylene glycol at interaction product-to-polyether weight ratio (1-4):(4-1). Final product is advantageously dissolved in organic solvent. Urethane-type demulsifier is effective is effective in destroying water-oil emulsion under conditions of decreased temperature and low formation-water mineralization. Demulsifier also protects equipment from corrosion. EFFECT: improved working characteristics.
