Dioctyl fumarate-co-vinyl benzoate copolymers preparation and their performance as flow improvers in waxy crude oils

Abstract

This work presents the synthesis of new copolymers based on dioctyl fumarate (DOF) and vinyl benzoate (VB) and their application as flow improvers in a waxy crude oil. The copolymers were obtained by solution radical polymerization starting from a broad range of monomer compositions (fDOF) and characterized by Fourier-transform infrared spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (1H-NMR) Spectroscopy and Size exclusion chromatography. Results indicated that polymerization yield and molecular weight increases with decrease in fDOF. Based on the composition of the copolymers the reactivity coefficients of the monomers were obtained, whose product r1. r2 = 0.042 indicates a copolymerization behavior with a high tendency to alternating copolymerization. Selected copolymers varying composition or molecular weight, were used as additive at different concentration to evaluate the effect of these variables on their performance as flow improvers in a waxy crude oil composed of paraffin with high average carbon number and a narrow carbon number distribution. The analysis was done through differential scanning calorimetry and rheological measurements. The addition of the lowest molecular weight copolymer resulted in the best efficacy as flow improver, while the highest molecular weight rich in VB copolymer produced an unwanted effect that worsen the flow properties of waxy crude oil at low temperatures.