An extensive investigation into the applicability of poly(vinyl alcohol) (PVA) and its synergy with rhamonolipid (a surfactant-active agent) and/or an alkali (NaOH) was carried out to evaluate and define the best fluid formulation for enhanced oil recovery (EOR) processes. First, the effects of molecular weight, concentration, and temperature of the PVA solution on surface tension (ST), interfacial tension (IFT), apparent viscosity, and thermodynamic stability were determined. Then, a systematic formulation of PVA combined with rhamonolipid and NaOH in reconstructed brine from an Angolan offshore field was developed. The IFT experiment was carried out on crude oil samples obtained from Block T of the Angolan offshore field. The combined PVA–rhamonolipid and NaOH–rhamonolipid–PVA in saline medium reduced the ST and IFT to 25.90 and 0.73 mN/m, respectively. The values of ST are better than the ones reported in the literature, which are within the range of 27–35 mN/m, while the IFT values are within the range reported in the literature, which is below 1 mN/m. This provides an opportunity to use this new synergistic formulation in EOR processes, particularly in offshore Angolan oilfields.
This study is sponsored by the Angolan National Oil Company (Sonangol EP), and the authors are grateful to Sonangol EP and BP Angola for the support and the permission to use data and publish this manuscript.