Effects of Pressure Oscillations on Foam Transport in Porous Media

The effects of pressure and temperature on foam flow through porous media, critical for applications such as subsurface gas storage and enhanced oil recovery, have yet to be completely understood. This study provides valuable new insights into foam behavior by directly measuring both pressure drop and capillary pressure during a series of foam quality scan experiments conducted at 20 °C and 50 °C and under ambient and 500 psi pressures. A key innovation of this work is the development of an in-house-designed capillary pressure probe, which captures capillary pressure dynamics at the mid-length of the sandpack This allows for precise measurements of foam stability mechanisms as a function of foam quality. Experiments were conducted in two sandpacks with identical silica sand, one with a translucent polycarbonate tube for ambient conditions and another with a stainless-steel tube for high-pressure and temperature experiments. Results reveal that foam strength increases with pressure at moderate flow rates due to increased pressure oscillations that promote foam generation, while higher temperatures reduce foam strength, driven by reduced liquid viscosity and accelerated gas diffusivity. These findings challenge the conventional understanding of “limiting capillary pressure” by showing that foam in homogeneous sandpacks becomes generation-limited at high qualities, providing a foundation for improved modeling and application of foam in porous media.