A critical evaluation of novel demulsifying agents based on acrylic terpolymers for Mexican heavy crude oils dehydration

A novel kind of random acrylic terpolymers based on butyl acrylate (B), 2-(dimethylamino)ethyl acrylate (Ae), and 2-carboxyethyl acrylate (Ce) monomers was obtained by emulsion polymerization. Monomers' weight ratios were varied, keeping in all cases a higher content of butyl acrylate (60, 70, 80, and 90 wt%) and controlling the number average molecular mass ((M) over bar (n)) during polymerization. The random acrylic terpolymers were characterized by spectroscopic techniques; subsequently evaluated as demulsifier agents in three aged heavy crude oils of 7.55, 6.11, and 3.33 degrees API (apparent gravities), which form very stable water-in-oil (W/O) emulsions. The best performance for removing the emulsified water at 80 degrees C was obtained with terpolymers containing 90-80 wt% of the hydrophobic monomer B and small amounts of the hydrophilic monomers Ae and Ce (BAeCe-9551 and BAeCe-8111), being more efficient than two commercial demulsifiers (FDH-1 and F-46 TRETOLITE (TM)). Moreover, the BAeCe-9551 terpolymer was evaluated in a fresh heavy crude oil of 20.2 degrees API at 60 degrees C - temperature of separation tanks -, showing better performance as breaker, coalescer, and clarifier than FDH-1. Finally, a quantitative structure-activity relationship (QSAR) analysis was carried out employing terpolymers' molecular parameters and crude oils' physicochemical parameters. Only one equation fulfilled all thresholds for Q(F1)(2), Q(F2)(2), Q(F3)(2), and r(m)(2), parameters, proving to be the most accurate to predict the water removal efficiency (WRE) of BAeCe-1 and BAeCe-2 series terpolymers when added to heavy crude oils. This correlation will allow selecting the best terpolymer for demulsifying a petroleum stream as a function of its physicochemical characteristics.