Application of CO2-foam as a means of reducing carbon dioxide mobility

Reducing the mobility of carbon dioxide through co-injection; of CO2 and a suitable surfactant solution to form a CO2-foam system is a promising method for improving the oil recovery in carbon dioxide flooding projects. This paper presents the results of a set of experiments on screening and selecting a suitable surfactant for CO2-foam purposes in a carbonate porous medium, as well as the effect of various parameters on the mobility of the 1 CO2-foam system. Four surfactants were examined and the one that performed best throughout the screening experiments was used in the subsequent flow experiments. The surfactants tested were Surfonic N-95, Surfonic L24-9, Bio-Terge AS-40, and Chaser CD-1045. The screening criterion selected was the fall in foam height with time at 60 degrees C for 0.1 wt% solution of the above mentioned surfactants. Chaser CD-1045 performed best in all screening tests and was, used during the flow experiments. Flow experiments were conducted through a porous medium made of crushed carbonate at pressures of 8,270 kPa and 10,336, kPa, and temperatures of 22 degrees C and 50 degrees C. Mobility of CO2-brine (simulating the WAG process) and CO2-surfactant systems were compared through a series of experiments. The effect of operating pressure and temperature, brine concentration, and the ratio 1 of the amount of CO2 to total foam (i.e., foam quality) on the mobility of a CO2-foam system were investigated and results are presented. The results indicate that additional oil is recoverable for CO2-foam vs. the co-injection of CO2 and brine simulating the WAG process.