Abstract: Screening multiple surfactants is performed by a screening method including passing foam compositions comprising a surfactant through a porous media while measuring pressure drop across the porous media until a first steady state pressure drop is achieved. Magnitude and frequency in oscillations of the first steady state pressure are measured. A gas is injected through the porous media while measuring the pressure drop across the porous media until a second steady state pressure drop is achieved. Magnitude and frequency in oscillations of the second steady state pressure drop are measured. Foam stability is determined based on the first steady state pressure drop, second steady state pressure drop, and magnitude and frequency of oscillations during the first and second steady states. Secondary oil recovery may include injecting a foam composition into an oil-containing reservoir, wherein the foam composition is based on results of the screening and properties of the oil-containing reservoir.

Abstract: A method for treating a hydrocarbon-containing formation includes injecting an aqueous solution that contains an alkali nitrite, an ammonium halide, and a foaming agent into the formation, injecting supercritical carbon dioxide into the formation, allowing a portion of the carbon dioxide to dissolve in the aqueous solutions, causing the alkali nitrite and ammonium halide to react and generate nitrogen gas, and allowing a foam to form by the interaction of the nitrogen gas with the foaming agent.

Abstract: A method for treating a hydrocarbon-containing formation includes injecting an aqueous solution that contains an alkali nitrite, an ammonium halide, and a foaming agent into the formation, injecting supercritical carbon dioxide into the formation, allowing a portion of the carbon dioxide to dissolve in the aqueous solutions, causing the alkali nitrite and ammonium halide to react and generate nitrogen gas, and allowing a foam to form by the interaction of the nitrogen gas with the foaming agent.