In this paper, a simulation technique has been developed and successfully applied to numerically simulate the experimentally determined displacement mechanisms governing alkaline flooding for enhancing oil recovery in heavy oil reservoirs. The measured pressure drop and oil recovery during the alkaline flooding processes have been found to increase as the alkaline concentration increases. The increase in pressure drop is mainly due to in situ formation of water-in-oil (W/O) emulsions, and oil recovery is thus improved because of the blockage of the high-permeability zones. The interfacial tension between heavy oil and alkaline solutions, viscosity of the in situ generated W/O emulsion, and relative permeabilities during waterflooding and alkaline flooding processes have been experimentally determined. An excellent agreement between the measured and simulated pressure drop and cumulative oil production are obtained by taking both the measured viscosity of W/O emulsions and the relative permeability into account. In particular, the in situ generation of W/O emulsion during alkaline flooding in heavy oil reservoirs has been numerically found to occur in the high-permeability zones. This finding is consistent with the experimentally determined displacement mechanisms (i.e., in situ generation of W/O emulsion) in the literature.