Evaluation of different polymeric scale inhibitors for oilfield application

Abstract

The current challenges in oil production involve increase in productivity for high temperature, pressure and salinity conditions. Specifically, for flow assurance, scale inhibitors injection plays a key role to control scale formation. In this work, homopolymers were synthesized by free radical solution polymerization using sulfonate monomers as sodium styrene sulfonate (NaSS), 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) and sodium vinyl sulfonate (SVS); phosphonic monomer as sodium vinyl phosphonic acid (VPA) and carboxylic monomer as sodium acrylic acid (AA). The homopolymers were characterized by 1H-NMR and SEC. The influence of the chemical structure and molecular weight of the polymers on scale inhibition process at different scenarios with high electrolyte concentration was evaluated by static and dynamic efficiency. AA and VPA polymeric scale inhibitors showed mainly effectiveness at short time (involved on nucleation mechanism) for barium and calcium sulfate, presented efficiency higher than 80%. NaSS homopolymers demonstrated higher efficiency (near to 75%) over time, comparing with other homopolymers specially in a multiple scale condition which presents high ionic forces (more than 200.000 ppm of total solids dissolved). These data suggest that NaSS polymeric inhibitor can act in different stages involved on scale inhibition, like as retarding nucleation, crystal modification and charge neutralization. It was observed that the best results were obtained using homopolymers from NaSS with number average molecular weight near to 13,000 Da.