The behavior of gas in foamy oil is one of the key factors for the heavy-oil solution-gas-drive process. Due to the high viscosity of the oil, and the interaction between capillary pressure and viscous forces, the depressurization of live heavy oil below the bubble point causes bubbles of gas to nucleate, grow, cluster, and eventually connect into a free phase.

In this paper, two models aimed at simulating foamy oil behavior are described and compared. One model partitions the gas into three groups (solution gas, dispersed gas, and free gas), while the other distinguishes four groups (including two types of dispersed gas). In the first model, two kinetic equations for mass transfer are defined to describe how one group of gas is transformed into another, while in the second model six kinetic equations for mass transfer are proposed. Each model defines in an original way the mobility of the gas groups, which leads to different relative permeability models.

Both models were applied to two sets of long core depletion experiments with significantly different depletion rates. A comparison of the matched results from the two models is presented in this paper.

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