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.

Surfactant polymer flooding is one of the most common chemical enhanced oil recovery techniques, which improves not only the microscopic displacement of the fluid through the formation of the emulsion but also the volumetric sweep efficiency of the fluid by altering the viscosity of the displacing fluid. However, one constraint of surfactant flooding is the loss of the surfactant by adsorption onto the reservoir rock surface. Hence, in this study, an attempt has been made to reduce the adsorption of the surfactant on the rock surface using novel colloidal silica nanoparticles (CSNs). CSNs were used as an additive to improve the performance of the conventional surfactant polymer flooding. The reduction in adsorption was observed in both the presence and absence of a polymer. The presence of a polymer also reduced the adsorption of the surfactant. Addition of 25 vol % CSNs effectively reduced the adsorption of up to 61% in the absence of a polymer, which increased to 64% upon the introduction of 1000 ppm polymer in the solution at 2500 ppm of the surfactant concentration at 25 °C. The adsorption of surfactant was also monitored with time, and it was found to be increasing with respect to time. The adsorption of surfactant increased from 1.292 mg/g after 0.5 days to 4.179 mg/g after 4 days at 2500 ppm of surfactant concentration at 25 °C. The viscosity, surface tension, and wettability studies were also conducted on the chemical slug used for flooding. The addition of CSNs effectively reduced the surface tension as well as shifted the wettability toward water-wet at 25 °C. Sand pack flooding experiments were performed at 60 °C to access the potential of CSNs in oil recovery, and it was found that the addition of 25 vol % CSNs in the conventional surfactant polymer chemical slug aided in the additional oil recovery up to 5% as compared to that of the conventional surfactant polymer slug.

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In this study, for the first time an effort is made to examine the effect of surfactant hydrophobicity on the synthesis of lanthanideseries nanoparticles inside the core of reverse micelles.Tween...

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