Impact of Electrolytes on Produced Water Destabilization

In order to increase oil recovery, new techniques were developed such as chemical Enhanced Oil Recovery (EOR). The water injected in the reservoir tends to form and stabilize emulsions of oil droplets in produced water. That makes the separation of oil from the aqueous phase more difficult. The main goal of this work is to achieve a better understanding of emulsion destabilization in the presence of brine. In this work, different methods were used with emulsions and macroscopic drops to better understand oil droplet behavior. The experimental results are based on the determination of the zeta potential, the evolution of the kinetics of light transmission, the critical force of coalescence in centrifugation, and the rupture time of the aqueous thin film between an oil drop and a water/oil interface. These studies allowed the characterization of the impact of salinity on emulsion destabilization. It was observed that the negative charges at the oil droplets surface, due to migration of indigenous amphiphilic species from crude oil to the interface, are reduced by the presence of salts because salts decrease the adsorption of charged natural surfactants at the oil–water interface. The electrostatic repulsion between oil droplets is thus reduced, promoting flocculation and coalescence.