Synthesis and Physicochemical Investigation of Anionic-Nonionic Surfactants Based on Lignin for Application in Enhanced Oil Recovery

A series of eco-friendly anionic-nonionic surfactant lignin polyether sulfonates (LPES) based on alkali lignin from the paper-making industry was prepared through alkoxylation, allylation, and sulfonation reactions. The chemical structures of synthesized surfactants were determined by an infrared (IR) spectrogram and H-1 nuclear magnetic resonance (H-1 NMR). In order to verify the adaptability of LPES surfactants applied in chemical enhanced oil recovery (EOR), the physicochemical properties including surface tension, salt tolerance, hydrophile lipophile balance (HLB) values, and interfacial tension for LPES surfactants were investigated through experiments. The critical micelle concentration (cmc) of LPES surfactants increased with the growth of ethylene oxide (EO) groups in the molecules, and the corresponding surface tension values were about 32-38 mN/m. Salt tolerance measurements prove that the LPES surfactants have a high tolerance to Na+ and Ca2+, and the HLB measurements demonstrate that the LPES surfactants have excellent emulsifying properties in oil/water (O/W) systems. Compared with Xinjiang crude oil, the LPES surfactants exhibit the desired ability of decreasing the interfacial tension (IFT) of Daqing/Huabei crude oil, which contains more colloid and asphaltene, and the LPES surfactants can reduce the IFT between Daqing (or Huabei) crude oil and brine to the 10(-3) mN/m level in the presence of alkali.