Foam is widely used in oil and gas recovery operations as a mobility control and profile correction agent. A brief list of foam applications includes acid diversion during matrix stimulation, gas blocking, hydraulic fracturing and clean-up of contaminated subsoil. In order to meet the growing demand of more difficult foam applications a deep insight on the dynamic of foam flow in a porous media is crucial to design a successful treatment. This paper is concerned with the foam flow behavior for acid diversion application taking into account the oil presence in the treated zone.

We report an experimental study based on core-flood experiments performed with the aid of X-ray computed tomography (CT) imaging technique, using Bentheimer sandstone and N2 foam. During the experiment, the residual oil condition was first established by performing drainage process followed with gravity stable water flooding to mimic the initial fluid distribution of the treated zone. Then, N2 was injected at a constant flow rate into the porous media saturated with surfactant solution. A series of longitudinal CT images were taken at different time intervals and pressure drop over the core was also monitored. The experiments were analyzed in terms of qualitative description of CT images, in situ liquid saturation profiles and pressure drop evolution along the core.

The experimental results indicate although foam breakthrough in the presence of oil occurs earlier than in absence of oil; however, foam generation continues, so that the liquid phase is displaced by foam flow in the treated region.

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