Transient aqueous foam flow in porous media: experiments and modeling

Gas injection into reservoirs can be used to increase oil recovery. However, the viscosity and density differences between the injected and displaced fluids can lead to low sweep efficiency. To overcome mobility control problems: gas can be injected in the form of foam to increase its apparent viscosity and improve reservoir sweep efficiency. Our study is focused on transient aqueous foam flow in homogeneous porous media. The experimental apparatus designed for this study consisted on an unconsolidated porous medium, saturated by surfactant-laden water, where nitrogen is injected at a constant flow rate. Pressure drop along the core was monitored, while 2D saturation measurements were performed using a gamma-ray attenuation technique. The experiments were analyzed in terms of breakthrough time, liquid recovery, pressure drop evolution along the core, and gas saturation profiles. First, we studied the influence of surfactant concentration. Second, for two fixed values of the surfactant concentration, we studied the influence of gas flow rate. The experiments were interpreted using a foam simulator, including a classical Darcy's law model coupled with a foam bubble population-balance equation to model generation, destruction, and convection of gas bubbles along the porous medium. Physical parameters describing generation and coalescence of foam lamellae have been optimized by a sensitivity study. (C) 1998 Elsevier Science B.V.