Electro-assisted enhanced oil recovery (EEOR) is an emerging technology that could significantly improve sweep efficiency. The aim of the present study was to scrutinize the simultaneous use of monovalent and divalent salts under low-voltage electric fields of direct and pulsed (sinusoidal and square waves) as a novel approach for reducing the IFT of crude oil–brine systems. IFTs were measured using a pendant drop device featuring parallel electrodes for electric field application at strengths of 1–3 V/cm and frequencies of 100–1000 Hz, with brine concentrations of 0.001–0.005 mol/dm3. Applying a square-wave pulsed electric field (3 V/cm, 600 Hz) brought about IFT changes from 27.5, 27.1, and 26.1 mN/m to 4.8, 4.7, and 4.0 mN/m at 0.005 mol/dm3 of NaCl, MgCl2, and Na2SO4, i.e., 82.5, 82.7, and 84.7% reductions, respectively. The IFT reduction corresponded to the boosted ion–dipole interactions under electro-hydrodynamic (EHD) effects, promoting adsorption of indigenous natural surfactants and interfacial instabilities induced by switching poles. Direct and sinusoidal waves were also effective but inferior to the square wave. Asphaltenes were precipitated and characterized to assess the role of present indigenous surfactants. Further, the IFT data were precisely adapted with the Young–Laplace equation combined with a developed correction factor as a function of involved parameters.
Hayati et al. (2026) studied this question.