Terpolymers as flow improvers for Mexican crude oils

The rheological behavior of dilute solutions from different terpolymers was investigated over a wide range of temperatures (20-45°C) and shear rates (0.1-300 s^-1). The investigation focuses on the effect of three co-monomer contents, their molecular weight, the terpolymer, and the viscosity-temperature relationship of a Mexican crude oil (MCO). Terpolymers with different contents of styrene (S), n-butylacrylate (BA), and vinyl acetate (VA) were synthesized through semi-continuous emulsion polymerization. The composition of the terpolymers was evaluated by nuclear magnetic resonance (NMR) spectroscopy. The average molecular weight and polydispersity of the polymers were determined through size-exclusion chromatography (SEC). Both the untreated crude oil and the one treated with a solution of terpolymer exhibited non-Newtonian behavior. The results confirm that the viscosity of crude oil is reduced when the terpolymers have a high percentage of S and small amounts of BA or VA. The molecular weight of terpolymers plays a fundamental role in their performance as viscosity reducers.