The applications of nanotechnology in oilfields have attracted the attention of researchers to nanofluid injection as a novel approach for enhanced oil recovery.To better understand the prevailing mechanisms in such new displacement scenarios,micromodel experiments provide powerful tools to visually observe the way that nanoparticles may mobilize the trapped oil.In this work,the effect of silicon oxide nanoparticles on the alteration of wettability of glass micromodels was investigated in both experimental and numerical simulation approaches.The displacement experiments were performed on the original water-wet and imposed oil-wet (after aging in stearic acid/n-heptane solution) glass micromodels.The results of injection of nanofluids into the oil-saturated micromodels were then compared with those of the water injection scenarios.The flooding scenarios in the micromodels were also simulated numerically with the computational fluid dynamics (CFD) method.A good agreement between the experimental and simulation results was observed.An increase of 9％ and 13％ in the oil recovery was obtained by nanofluid flooding in experimental tests and CFD calculations,respectively.