A number of heavy oil reservoirs show anomalously good primary performance under cold heavy oil production. Foamy oil behavior is believed to be the main reason. Previous numerical simulation of primary depletion in foamy oil reservoirs is still based primarily on empirical adjustments to the conventional solution gas drive models. While these models do not involve the gas dynamic process? es in foamy oil flow. This paper presents a numerical model including the non-equilibrium rate processes of the foamy oil. The model was tested by the primary depletion experiment and investigates the effects of various process parameters on oil recovery. It was observed that higher oil recovery was predicted under higher pressure decline rate. The maximum volume of the oil decreases as the gas decay coefficient λs increases. And the greater the bubble growth index b is, the later the foamy oil forms.