Development of Oil-in-Water Microemulsions and Evaluation of Its Presence in the Treatment of Produced Water.

Abstract

Enhanced oil recovery (EOR) by chemical methods, such as injection of surfactants and polymers, increases the efficiency of extracting petroleum. However, after permeating the reservoir, these products remain in the produced water and hamper its treatment, including the efficiency reduction of the flocculants normally used for this purpose. In this work, oil-in-water (O/W) microemulsions were prepared according to ternary phase diagrams, with two oil phases, solbrax and kerosene, extracted from oil fractions, and two ethoxylated nonylphenol surfactants with 8 and 9.5 ethylene oxide units (NP80 and NP95), respectively, along with brine. The objective was to evaluate the effects of these components presence in the microemulsions on the treatment of produced water. The microemulsified systems were characterized regarding viscosity, size of the dispersed droplets and stability. The results showed that the microemulsions containing the most polar surfactant (NP95) caused greater stabilization of the O/W emulsion (produced water). However, there also was a synergistic effect when using a commercial flocculant along with the microemulsion based on NP80, diminishing the residual oil content in the produced water.