“…Due to the amphiphilic structure, the surfactant can effectively reduce the water/oil interfacial tension (IFT) and change the formation wettability, which are the basic mechanisms of surfactant flooding in chemical enhanced oil recovery (EOR) (Zhang et al, ). Focused on the properties of reservoir water (salinity, temperature, viscosity, and so on), many groups modified the surfactant structures to develop their performances in EOR (Ahmadi and Shadizadeh, ; Babu et al, ; Chaturvedi et al, ; Cui et al, ; Hezave et al, ; Jia et al, ; Kamal, ; Kumar and Mandal, , ; Nguele et al, ; Pal et al, ; Pillai et al, , ; RodrĂguezâEscontrela et al, , b; Saxena et al, ; Zendehboudi et al, ; Zheng et al, ; Zhou et al, , ). Cui et al synthesized zwitterionic surfactants with double long alkyl chains to achieve the optimal hydrophileâlipophile balance for the remarkable IFT reduction (Cui et al, ).…”