Effects of Pore Geometry on Flowing Foam Dynamics in 3D-Printed Porous Media

Foam flow in porous media is important in several environmental and industrial applications including soil remediation and enhanced oil recovery. The behaviour of foam is greatly influenced by transport properties of porous media, properties of foam and the fluid residing in porous media. We conducted a series of experiments to investigate the effects of pore geometry on foam flow in porous media and its implications for hydrocarbon displacement. We fabricated four porous media with well-defined pore throat size distributions, permeability and angularity by means of 3D printing technology. The models were initially saturated with oil. Gas and surfactant solution were subsequently injected into the model simultaneously for in situ generation of foam to displace the oil. Displacement dynamics were recorded using an automated imaging setup. Analysis of the pore-scale images revealed that the injected pore volumes required for the initiation of foam generation decreased as the pore size of porous media increased, presumably due to the lower entry capillary pressure. For the same pore throat size range, changes in the permeability due to increased number of pore throats did not appear to have a significant influence on the overall recovery of oil. Our results illustrate the impact of grain angularity on foam generation owing to its influence on the pore-to-throat aspect ratio and capillary pressure gradient.