A kind of stable nanofluid was prepared based on surfactant modification,and its related chemical and fluid properties were analyzed through microscopic testing.The displacement effect of modified nanofluids in improving crude oil recovery was evaluated.The results indicated that the modification of PAN fluid with nano SiO2 was a chemical bonding reaction,and surfactant-modification of PAN was the physical adsorption behavior of surfactant,and the surface of nanoparticles changed from hydrophilicity to hydrophobicity after modification.The linking effect of surfactants enhanced the interaction between oil-water molecules,reduced the free energy at the interface,and rapidly reduced the interfacial tension of the PAN-B and PAN-C systems to below 10 mN·m-1.Oil-water mass ratio significantly affected the morphology and stability of Pickering lotion.The PAN-B system had the best emulsion performance,with a complete demulsification time of over 48 h.When the mass fraction of PAN-B nanofluid was 0.1%,the increase in crude oil recovery rate was the largest,and the recovery rate first increased and then decreased with the increase of injection rate or injection volume.
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