Anionic/Nonionic Surfactant Mixture for Enhanced Oil Recovery through the Investigation of Adsorption, Interfacial, Rheological, and Rock Wetting Characteristics

Surfactant adsorption is a major problem encountered with the surfactant polymer flooding. A lot of additives have been used in this regard to tackle this problem. In the present study, a mixture of a nonionic and an anionic surfactant was used to investigate its effect on the various aspects of the surfactant polymer flooding. The effect of temperature and the nonionic surfactant concentration on the critical micelle concentration of the anionic surfactant was explored. The adsorption behavior of the surfactant mixture on the sand particles was explored by comparing the initial and final concentrations of the surfactant mixture. The adsorption data were fitted in the different adsorption isotherms (Langmuir, Freundlich, and Temkin). The interfacial property and the rock wetting characteristics of the surfactant mixture were investigated by measuring the surface tension and contact angle, respectively. Next, the viscosity of the chemical slug (surfactant and polymer) was analyzed at different temperatures. The viscosity results were fitted in the power law model to understand the fluid flow behavior. Finally, the sand pack flooding experiments were performed using the chemical slug composed of a surfactant mixture and an industrial-grade polymer. In all the experiments, the binary surfactant mixture outperforms the individual surfactants and efficiently reduced the surfactant adsorption by 63%. Also, the binary surfactant mixture achieved an ultralow interfacial tension value of 0.0097 mN/m. The chemical slug composed of the binary surfactant and polymer was able to recover up to 76% of the total oil.

Automated summary

The present study investigated the effects of a binary surfactant mixture on various aspects of surfactant polymer flooding, including the critical micelle concentration, adsorption behavior, interfacial properties, and wetting characteristics. By comparing initial and final concentrations of the surfactant mixture, it was found that the binary surfactant mixture outperforms individual surfactants and efficiently reduces surfactant adsorption by 63%. Additionally, the binary surfactant mixture achieved an ultralow interfacial tension value of 0.0097 mN/m and was able to recover up to 76% of the total oil in sand pack flooding experiments.