Evaluation of the influence of polyoxide‐based surfactants on the separation process of model emulsions of asphaltenes using the FTIR‐ATR technique

Abstract

During extraction of crude oil, water is generally present in the oil. This water-in-oil (w/o) mixture undergoes turbulent flow that promotes sheer forces, resulting in the appearance of emulsions. These emulsions can be highly stable due to the presence of compounds with polar characteristics such as asphaltenes, which act as natural emulsifiers and form resistant films at the oil-water interface. Nonionic surfactants based on polyoxides are widely used to prevent the formation or to break down w/o emulsions. To shed more light on the destabilization mechanism of w/o emulsions promoted by these surfactants, in this study the techniques of tensiometry and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) were applied to study the interface formed by poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers and asphaltenic petroleum fractions. Initially, the critical micelle concentration of the copolymers in aqueous solution was determined. The results agreed with those found by tensiometry. The bottle test was used to evaluate the break-down of the w/o emulsions in the presence of the PEO-PPO block copolymers, and the results presented good agreement with those obtained by tensiometry and FTIR-ATR.

The Influence of Polymer Flooding on Produced Oily Water: A Review

“…They suggested that the flocculation when using PoAC works by electrostatic charge neutralization and bridging, while PEI works by demulsification. They also cited the results of Aguiar and collaborators showing that copolymers containing ethylene oxide and propylene can be used as demulsifiers of water-in-oil emulsions and can displace asphaltenes, which are natural surfactants (Aguiar et al, 2013). Based on these findings and also on the results of variation of the interfacial tension and interfacial dilational modulus with temperature, the authors concluded that PEI works by demulsification (Zhang et al, 2015).…”