Gas assisted gravity drainage (GAGD) is an oil recovery mechanism that can be implemented after waterflood to enhance the recovery of oil. The performance of postwaterflood GAGD is affected by a variety of parameters that determine the balance between capillary, gravitational, and viscous forces. In this research, the influence of the wettability, heterogeneities, and production rate on the recovery of oil have been studied at the pore level to recognize phenomena affecting mechanisms of oil recovery visualizing interfaces in a newly designed micromodel that contains a coarse pore network covered by fine capillaries. Experimental results show that regions with high oil saturation (oil-bank) were formed ahead of the gas front in both oil-wet and water-wet micromodels when the production rate was low. Under oil-wet conditions, the size of the oil-bank was greater, and the recovery of oil initiated prior to a gas breakthrough. Under water-wet conditions, the flow of the residual oil after a gas breakthrough was initially restricted by the presence of the residual water in small pores and fine capillaries. However, high oil recovery was finally obtained upon an effective reduction of the water saturation extending the time of the process. Under both wettability conditions, increasing the drainage rate contributed to the instability of gas fronts and early gas breakthroughs without a remarkable oil recovery. The experimental result implies that, although the oil production characteristics under oil-wet and water-wet conditions are different, both of the wettability states have potential for the implementation of postwaterflood GAGD.