The objective is to identify commercially available additives which are effective in reducing the mobility of carbon dioxide, CO/sub 2/, thereby improving its efficiency in the recovery of tertiary oil, and which are low enough in cost to be economically attractive. During the course of the project significant progress has been made in developing a commercial method of reducing the mobility of carbon dioxide in enhanced oil recovery processes. Experiments on gas mobility control, conducted in linear sand-pack models, show only a general correlation with the static foam test. The static test, which utilizes a blender to generate foam from an aqueous surfactant solution, is useful mainly for studying the effects of pH, temperature, salinity and crude oil on the relative foamability of any given surfactant. Surfactants that produce reasonable quantities of foam in the blender test also impart some degree of mobility control to gas during two-phase flow. The best mobility control additives however, are only modest foam volume producers. In addition, the best additives spontaneously produce a viscous foam under flow conditions and rates typical of petroleum reservoirs. Three basic chemical structures listed below appear to show most promise for gas mobility control: (1) ethoxylated adducts of C/sub 8/ to C/sub 14/ linear alcohols; (2) sulfate esters of ethoxylated C/sub 9/ to C/sub 16/ linear alcohols; (3) low molecular weight co-polymers of ethylene oxide and propylene oxide. For an immiscible CO/sub 2/ flood, reducing CO/sub 2/ mobility by a factor of 10 increased overall recovery by 20 percent. More importantly, incremental oil production was more than doubled during the early phase when only CO/sub 2/ was injected. Attempts to simulate the mobility controlled miscible CO/sub 2/ process were not successful. More work is planned. 98 refs., 73 figs., 23 tabs.