THE INFLUENCE OF VINYL ACETATE CONTENT OF THE POLY(ETHYLENE-CO-VINYL ACETATE) (EVA) ADDITIVE ON THE VISCOSITY AND THE POUR POINT OF A BRAZILIAN CRUDE OIL

Abstract Petroleum companies have enhanced the offshore exploration, where the fields are located under deep water. In such cases, the low temperature of the water leads to the cooling of the oil and provokes wax deposition. Several techniques are used to reduce the problems caused by wax deposition. Polymeric additives, as ethylene-co-vinyl acetate co-polymers (EVA), are intensively used. In this work, the influence of the EVA vinyl acetate content on the viscosity and the pour point of a Brazilian crude oil was evaluated, and correlations for these properties as a function of the EVA co-polymer concentration were established. EVA copolymers were used containing 22,32,40 and 82 wt% of vinyl acetate and the tests with the crude oil were carried out using 50, 500, 1000 and 5000 ppm of EVA as additive. The results obtained from viscosity measurements showed that only below the temperature in which the wax crystals start forming the copolymer exhibited a strong influence on the oil viscosity reduction at an optimum concentration. The pour point results showed the best efficiency to EVA 32. The results obtained from both experiments showed that the viscosity and the pour point behaviors do not present good correlations to each other. Acknowledgments