In this study, researchers conducted experiments to understand how foam behaves in porous media and to validate models for predicting its behavior. The experiments involved injecting a gas and a surfactant solution together to create foam, and measuring various characteristics such as saturation and surfactant concentration profiles, the amount of water in the effluent, and the pressure drop. The researchers used a bubble population model that combines the density of bubbles in multiphase flow equations, including the water equation, an equation for foam as a gas with increased viscosity, a bubble density equation, and sometimes a surfactant transport equation. They used the IMPES method to solve these equations and calculated the apparent viscosity of the foam based on the bubble density and local interstitial velocity. The bubble density equation includes a term known as the bubble generation-coalescence function, which represents the difference between the rates at which bubbles are created and merged together. The researchers found that the bubble generation-coalescence function can be obtained by considering water saturation and the flowing fraction of foam, and equating the rate of change of bubble density during the transient state to this function plus terms for bubble transport by convection and diffusion divided by porosity and saturation. This approach could help to improve our understanding of foam flow in porous media and the effectiveness of foam in displacing fluids in reservoirs.
R. Thorat and H. Bruining. “Foam Flow Experiments. I. Estimation of the Bubble generation-Coalescence Function”. In: Transport in Porous Media 112.1 (2016), pp. 53–76. doi: 10.1007/s11242-016-0632-z.