Effect of partially hydrolyzed polyacrylamide on emulsification stability of wastewater produced from polymer flooding

Abstract

Abstract In this work, the effect of partially hydrolyzed polyacrylamide (HPAM) on the oil–water interfacial properties of produced water from polymer flooding (PWPF) was investigated. In addition, this study investigated the effects of three fiocculants (polyaluminium chloride PAC, cationic polymer FO4800SH, and nonionic polymer 402) on the stability of PWPF. The experimental results demonstrate that the addition of HPAM enhances the emulsion stability by increasing viscosity, zeta potential, interfacial tension and interfacial dilational viscoelasticity. The molecular weight and hydrolysis degree of HPAM have no significant influences on these properties. The stability of PWPF can be enhanced by increasing HPAM concentration. Dependency of frequency and concentration was observed for the interfacial dilational viscoelasticity. With the addition of HPAM, the dilational viscoelasticity not only increases with HPAM concentration but runs through a maximum at a concentration of 300 mg/L. As the oscillating frequency increases, the dilational modulus and dilational elasticity increase but the dilational viscosity decreases. The three flocculants can reduce the stability of the emulsion by considerably decreasing the absolute value of zeta potential of oil droplets. FO4800SH has a greater ability than PAC and 402 to separate oil from the emulsion. But the demulsification efficiencies of the three flocculants are not satisfactory because of the presence of HPAM residue. Further research is needed to find more efficient methods to achieve excellent performance of oil–water separation towards PWPF.