Design and Fabrication of Anionic/Cationic Surfactant Foams Stabilized by Lignin–Cellulose Nanofibrils for Enhanced Oil Recovery

It has been decades since foams were adapted in further developing water-flooded oilfields. Foam stability is regarded as the governing factor that directly determines the enhanced oil recovery (EOR) efficiency of a foam injection. In this paper, we focus on a series of anionic surfactant-based foaming agent [sodium dodecyl sulfate (SDS)] and non-ionic surfactant-based foaming agent [alkyl polyglycoside (APG)] stabilized by lignin–cellulose nanofibrils (LCNFs), in the absence or presence of a cationic surfactant [hexadecyltrimethylammonium bromide (CTAB)]. Particular attention was placed on the proportion of LCNFs/SDS/CTAB and LCNFs/APG/CTAB as well as their synergism assessment, including foamability, drainage half-time, foam decay, surface tension, and micromorphology. Our results demonstrate that the synergism between cationic/anionic surfactants and LCNFs retarded film drainage and, thus, produced robust foams. The synergism mechanism, contributed to the electrostatic reaction and hydrogen bond between LCNFs and the surfactants, has been discussed and proposed.