This paper describes a dynamic model for the simulation of foamy oil flow in porous media. The model includes expressions for the rate processes of nucleation, bubble growth and disengagement of dispersed gas bubbles from the oil. The model is used to simulate experimental results pertaining to primary depletion tests conducted in a sand pack. Using the model to interpret experimental results indicated that, although the lifetimes of supersaturation and dispersed gas bubbles may be short, supersaturated conditions are likely to exist, and dispersed gas bubbles are likely to be present during the entire production period, as long as the pressure continues to decline at a high rate. The model developed in this paper gave better agreement with experimental data than other proposed models. The effect of foamy oil flow increases as the rate of pressure decline increases.