New high-molecular nonionic surfactant "SMATWEEN" was synthesized by catalytic esterification of styrene-comaleic anhydride copolymer (styromal) with polyoxyethylene sorbitantrioleate (Tween-85) and used as a demulsifier and depressant for multiple high-paraffinic oils from Kazakhstan oilfields. The structure of the synthesized surfactant was studied and proven. The high demulsibility efficiency of new macromolecular surfactant was shown. It was found that it is necessary to enter the demulsifier SMATWEEN before the pour point. Rheological parameters of the reagent show improvement by introducing it in high-paraffinic oil before the crystallization of the most high-molecular paraffins. (C) 2014 Elsevier B.V. All rights reserved.