Foams are used for mobility control in enhanced oil recovery operations. However, a typical oil-field application of foam suffers from such problems as early CO2 breakthrough, poor sweep efficiency, and inefficient oil recovery due to viscous fingering resulting from a low gas-phase viscosity and an unfavorable mobility ratio. The objective of this experimental investigation was to study the use of additives to enhance foam properties and to improve the in situ generation of foams for enhancing the gas-flood sweep efficiency. Foam generation was achieved by flowing nitrogen, surfactant, and various foam-enhancing additives through a sandpack. Some of the parameters affecting the foam performance were the polymer concentration, type of surfactants and their concentrations, aqueous-phase salinity and pH, and effect of flow rate (or shear rate). The performance of polymer-enhanced foams (PEFs) was much better than that of conventional foams. Poly(acrylamide) polymers were used as an additive. Higher foam resistance and longer foam persistence were achieved by using relatively low concentrations of polymers. The studies also showed that the foam performance was significantly improved over a broad range of polymer concentrations. A number of other investigators have shown that foams are severely affected in the presence of oil. This is especially true of lighter or less viscous oils, and the destabilizing effect is magnified with a higher salinity aqueous phase. PEFs with a low-salinity aqueous phase showed improvement in foam stability. The effective viscosities of PEFs were higher than those of conventional foams with a high-salinity aqueous phase and the presence of lighter oils. Further, PEFs reduced the negative impact of oils on foam mobility. Of the surfactants studied, alpha-olefin sulfonates were found to be stable with high-salinity brines as well as compatible with polymer additives. Other surfactants, including amine oxide surfactants, were also studied and showed unusually high foam resistance and stable properties.