Emulsification and stabilization mechanism of crude oil emulsion by surfactant synergistic amphiphilic polymer system

The synergistic effects between surfactant and amphiphilic polymer on emulsion stability (a) the physical twine of wormlike micelles and the hydrophobic association (b) the mixed adsorption of surfactant and polymer at the surface. • A surfactant synergistic amphiphilic polymer system was selected. • The emulsifying ability of the combination system was evaluated and the mechanism was proposed. • The mechanisms of the emulsion stability of the combination system were determined by various methods. • The synergistic mechanisms of improving emulsion stability were proposed. Both amphiphilic polymer and surfactant can be used to enhance oil recovery (EOR) by emulsifying crude oil. In this work, the emulsifying ability and emulsion stability of combination system constituted by amphiphilic polymer (APC 16 ) and anionic surfactant (erucyl dimethyl amidopropyl betaine, EDAB) were studied. The bottle test was selected to evaluate the emulsifying ability. The TURBISCAN Lab and laser particle size analyzer were applied to evaluate emulsion stability. The rheometer, interfacial tensiometer and microscope were used to explore the stability mechanisms of emulsions. The results showed that the combination system exhibited better emulsifying ability than APC 16 and emulsion formed by the combination system also performed greater stability than those formed by either EDAB or APC 16 system. The better emulsifying ability of the combination system depended on low interfacial tension (IFT) due to the addition of surfactant. The greater emulsion stability of the combination system can attribute to three perspectives. Firstly, emulsion formed by the combination system exhibited higher external viscosity, which slowed down the migration velocity of the emulsion droplets. Secondly, the excellent interfacial film strength prevented the emulsion droplets from coalescence. Finally, the small emulsion droplet performed lower floating and coalescence velocity so as to increase emulsion stability.