Visual micromodels are a powerful tool for examining the mechanisms of oil recovery from porous media at the pore level. To this end, an algorithm has been developed to create two-dimensional flow network patterns simulating porous media with controlled properties. This has been used to manufacture flow micromodels that have different grain size distributions, permeabilities and heterogeneities. CO2 floods were carried out to determine the effect of several factors, such as injection rate, oil viscosity and the co-injection of water with CO2, on the displacement process and the oil recovery mechanism. Viscous fingering was found to be the dominant displacement mechanism up to solvent breakthrough at all the flooding conditions. Subsequent growth of the fingers was by a much slower dispersion-type process. A mechanism for recovering water-shielded oil by a cyclic build-up, thinning-out and then snap-off of the shield has been observed.