The Synergistic Effect of Surfactant and Polymer in Stabilizing CO2-Foams

Injecting carbon dioxide (CO2) into oil reservoirs improves oil recovery and reduces carbon footprint by sequestering CO2 underground. While CO2 injection has been reported successfully around the world, sweep efficiency remains a key challenge with this EOR technique. Gravity override due to CO2’s low density and viscosity relative to reservoir fluids are the main factors for this challenge. Foam generation is one of the most promising techniques to overcome gas mobility issues and improve sweep efficiency inside the reservoir. This study evaluates the influence of various parameters, while surfactants tested demonstrated the formation of stable foams, mixtures of surfactant mixed with polymer were able to produce more stable foams. Increased concentration of both surfactant and polymer also led to the formation of more viscous and stable foams with prolonged foam half-life. The recorded values of half-life in surfactant-polymer mixtures were 3-5 times that of surfactant only. The presence of crude oil has a definite disruptive effect for most foams. The static foam tests provided evidence that presence of polymer in mixtures enhances foam stability in presence of crude oil. In addition, IFT measurements were performed on the samples, and the results were in agreement with the bulk tests findings.