Seung Ihl Kam

Foam Generation in Homogeneous Porous Media

Abstract In steady gas–liquid flow in homogeneous porous media with surfactant present, there is often observed a critical injection velocity or pressure gradient ∇ p min at which “weak” or “coarse” foam is abruptly converted into “strong foam”, with a reduction of one to two orders of magnitude in total mobility: i.e., “foam generation”. Earlier research on foam generation is extended here with extensive data for a variety of porous media, permeabilities, gases (N 2 and CO 2 ), and surfactants. For bead and sandpacks, ∇ p min scales like (1/ k ), where k is permeability, over 2 1 2 orders of magnitude in k ; for consolidated media, the relation is more complex. For dense-CO 2 foam, ∇ p min exists but can be less than 23 KPa/m (1 psi/ft). If pressure drop, rather than flow rates, is fixed, one observes an unstable regime between stable “strong” and “coarse” foam regimes; in the unstable regime ∇ p is nonuniform in space or variable in time. Results are interpreted in terms of the theory of foam mobilization at a critical pressure gradient.

Three-Phase Fractional Flow Analysis for Foam-Assisted Non-aqueous Phase Liquid (NAPL) Remediation

Among numerous foam applications in a wide range of disciplines, foam flow in porous media has been spotlighted for improved/enhanced oil recovery processes and shallow subsurface in situ NAPL (non-aqueous phase liquid) remediation, where foams can reduce the mobility of gas phase by increasing effective gas viscosity and improve sweep efficiency by mitigating subsurface heterogeneity. This study investigates how foams interact with and displace oleic contaminants in remediation treatments by using MoC (Method of Characteristics)-based three-phase fractional flow theory. Six different scenarios are considered such as different levels of foam strength (i.e., gas mobility reduction factors), different initial conditions (i.e., initially oil/water or oil/water/gas present), foam stability affected by water saturation

Modeling foam delivery mechanisms in deep vadose-zone remediation using method of characteristics.

({S}_{\mathrm{w}})

The compressibility of foamy sands

(Sw) and oil saturation

Simulating use of foam in aquifer remediation

({S}_{\mathrm{o}})

Fractional-flow Theory of Foam Displacements with Oil

(So), and uniform versus non-uniform initial saturations. The process is analyzed by using ternary diagrams, fractional flow curves, effluent histories, saturation profiles, time–distance diagrams, and pressure and recovery histories. The results show that the three-phase fractional flow analysis presented in this study is robust enough to analyze foam–oil displacements in various conditions, as validated by an in-house numerical simulator built in this study. The use of numerical simulation seems crucial when the foam process becomes very complicated and faces multiple possible solutions.