Advanced multi-wall carbon nanotube-optimized surfactant-polymer flooding for enhanced oil recovery

[Display omitted] •The application of mMWCNT in nanofluids as a slug for enhanced oil recovery is investigated and reported for the first time.•The mMWCNT reduced the IFT up to 56 %.•mMWCNT efficiently modified the wetting behavior of the rock, aiding the oil recovery.•A recovery factor of 70 % was achieved. In this captivating study, we explored the fascinating potential of carbon nanotube-based nanofluids in improving oil recovery efficiency and transforming interfacial tension. To accomplish this, we acquired high-purity multi-walled carbon nanotubes from Plasma Chem Gmbh, ensuring a purity level exceeding 95 %, which underwent additional functionalization and experimentation to explore their impact. The functionalization of multi-wall carbon nanotubes with ammonium hydroxide and hydrogen peroxide generated diverse surface groups, reduced van der Waals interactions, and increased carbon nanotube dispersibility through enhanced interactions with polymers or solvents. The modified multi-wall carbon nanotubes were characterized using Raman analysis, HRTEM, and zeta potential. Varying concentrations of altered multi-wall carbon nanotube-based fluids were prepared to study their impact on surface tension using a Surface tensiometer. Adsorption studies were conducted to minimize surfactant loss. Contact angle experiments using a Goniometer helped alter the rock surface's wetting characteristics. Finally, the core flooding experiment using two pore volumes of the nanofluid with the optimal concentration of mMWCNT with SDS and 1000 ppm of polymer calculates the oil recovery factor. The study's findings revealed that the modified multi-wall carbon nanotubes significantly reduced surface and interfacial tension by approximately 59 % and 56 %, respectively, at the optimum concentration. Moreover, the nanotubes successfully minimized surfactant loss by about 49.3 %. The contact angle experiments demonstrated that the modified nanotubes transformed the rock surface from oil-wet to water-wet, as evidenced by a substantial reduction of approximately 54 % in the contact angle value. In conclusion, the core flooding experiment, employing a chemical slug composed of SDS at CMC, modified multi-wall carbon nanotubes, and industrial-grade polymer, yielded a remarkable oil recovery factor of approximately 70 % of the original oil in place.