Foam propagation and oil recovery potential at large distances from an injection well

While foam propagation, foam–oil interaction and foam oil recovery performance have been investigated by numerous research studies, most of previous works were performed on short porous media with the maximum length of 30 cm. Therefore, their results mostly represent foam behavior in the vicinity of the injection well and may not represent the foam propagation, quality and oil recovery potential at large distances from the injection well. In this study, by using a high-pressure and high-temperature rig equipped with a 12-m long porous medium and microscopic visualization facilities, foam stability in the presence and absence of a reservoir crude oil, foam propagation, foam–oil interaction, and finally foam oil recovery potential at large distances from the injection well were investigated. The oil recovery behavior of four tertiary scenarios, including Sodium Dodecyl Sulfate (SDS) foam, Alpha-Olefin Sulfonate (AOS) foam, gas, and simultaneous water alternating gas (SWAG) injection, were investigated. According to results, pressure presented a positive impact on the foam stability. The extent of this impact was a function of the surfactant type. Compared to gas and SWAG injection, in the 12-m long porous medium, foam flooding scenarios presented much stronger oil recovery potentials. This reveals the strong potential of foam flooding in producing the oil trapped in areas deep into the reservoir and far from the injection well. Based on this study, by using a suitable surfactant solution and optimum gas fractional flow, even in the presence of oil, foam can propagate to large distances from the injection well and leads to extra oil recovery.