Described is a method for treating hydrocarbons in a reservoir. A foaming surfactant solution and a foaming gas are introduced into the upper portion of a reservoir such that barrier foam bubbles form. Then, super/critical carbon dioxide is introduced such that a CO2 cap forms. The CO2 cap is formed above a foam barrier of aggregated barrier foam bubbles positioned at an interface between hydrocarbons to be treated in the reservoir and the CO2 cap. The super/critical carbon dioxide is introduced into the reservoir at an injection rate that is greater than a pre-treatment critical gas injection rate. Hydrocarbons are recovered from a lower portion of the reservoir.