Molecular Mechanisms of Nanoparticle‐Assisted Surfactant Flooding: Interactions Among Nanoparticles, Surfactants, and Rock Surfaces

Synergistic flooding using nanoparticles and surfactants is a viable strategy for chemical enhanced oil recovery (EOR), yet its underlying molecular‐scale mechanisms require clearer elucidation. This study utilizes molecular dynamics simulations to investigate the microscopic mechanisms governing nanoparticle–surfactant displacement behavior. Adsorption simulations of four distinct surfactants on quartz surfaces reveal that cetyltrimethylammonium bromide (CTAB) yields the highest adsorption energy (149.33 kcal mol −1 ). The incorporation of nanoparticles enhances the adsorption energy of sodium dodecylbenzene sulfonate (SDBS) from 118.26 to 135.57 kcal mol −1 , promoting the formation of a highly ordered interfacial layer. Subsequent pore‐scale displacement simulations demonstrate that in smooth channels, alkyl‐modified nanoparticles accelerate initial oil mobilization through hydrophobic interactions, driving a displacement distance beyond 320 Å, whereas carboxyl‐modified nanoparticles ensure stable displacement due to enhanced hydrophilicity. Under rough‐wall conditions, the alkyl‐modified variants display superior transportability by penetrating structural grooves, while the carboxyl‐modified nanoparticles induce a uniform interfacial perturbation that facilitates oil stripping. These results provide molecular‐level insights into how nanoparticle surface functionality regulates oil mobilization and highlight the potential of nanoparticle‐assisted surfactant flooding for enhanced oil recovery.