Ultra-low interfacial tension biobased and catanionic surfactants for low permeability reservoirs

Alkyl polyglucoside, an eco-friendly, stable and low-cost available biobased surfactant, was chemically modified to develop ultra-low interfacial tension (IFT) surfactants for crude oil recovery from low permeability reservoirs. The modified anionic surfactant alkyl polyglucoside sodium hydroxypropyl sulfonate (APGSHS) was structurally characterized by FT-IR, H-1 NMR and TGA methods. Following that, the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) was combined with APGSHS to formulate the ultra-low oil/water IFT catanionic surfactants, which exhibits higher water-solubility than DTAB/APGSHS mixtures at various concentrations and combined ratios. Furthermore, the surface properties, thermodynamic parameters of the sole and combined surfactants show that the combined APGSHS/CTAB catanionic surfactants have lower surface tension (22.90 mN/m) at cmc, smaller area occupied per molecule and stronger micellization capacity, which indicates that the surfactant molecules are tightly absorbed onto the two-phase interface for catanionic surfactants. The mechanism underlying the strong electrostatic attraction between the ion head groups in APGSHS and CTAB could be proven by the high absolute value of interaction parameters (12.23) in binary systems. Besides, the salinity resistance effect tests indicate that the ultra-low IFT formula exhibits excellent performance in both monovalent and divalent ions conditions. Notably, the APGSHS/CTAB surfactants with total concentration of 3000 mg/L and molar ratio of 6:4 can effectively enhance oil recovery and decrease the injected pressure for low permeability reservoirs. Hence, the newly formulated green catanionic surfactants exhibit remarkable abilities for maintaining the ultra-low IFTs and can be used for EOR in low permeability and high salinity reservoirs. (C) 2020 Elsevier B.V. All rights reserved.