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 crudeoil

Petroleum companies have enhanced the offshore exploration, where the field s are located under deep water. In such cases, the low temperature of the w ater leads to the cooling of the oil and provokes wax deposition. Several t echniques are used to reduce the problems caused by wax deposition. Polymer ic additives, as ethylene-co-vinyl acetate co-polymers (EVA), are intensive ly used. In this work, the influence of the EVA vinyl acetate content on th e 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 conce ntration 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 f rom viscosity measurements showed that only below the temperature in which the wax crystals start forming the copolymer exhibited a strong influence o n the oil viscosity reduction at an optimum concentration. The pour point r esults showed the best efficiency to EVA, 32. The results obtained from bot h experiments showed that the viscosity and the pour point behaviors do not present good correlations to each other.