Researchers from Southwest Research Institute (SwRI) and the University of Texas at Austin are advancing a novel approach utilizing foam-entrapped supercritical carbon dioxide (sCO2) to simultaneously enhance oil recovery (EOR) and improve the long-term security of carbon sequestration. This innovative technology aims to address the dual industry concerns of maximizing hydrocarbon extraction while effectively preventing stored CO2 from migrating back to the surface, holding significant implications for the global energy market, particularly in basins like the Permian.

The research builds upon principles from traditional CO2-EOR methods, focusing on the stability and behavior of sCO2 foams under extreme reservoir conditions. Angel Wileman, a co-principal investigator on the project, detailed that tests were conducted at pressures around 1,200 pounds per square inch and temperatures approximating 300 degrees Fahrenheit. These conditions closely mimic the subterranean environments encountered in active oil fields, providing critical insights into the practical application of the technology. SwRI has been investigating foam applications for approximately eight years, initially exploring methane foams for hydraulic fracturing to reduce water usage, and later high-pressure foams as drilling fluids in collaboration with major oil companies.

Under high pressure and temperature, CO2 transitions into its supercritical state, exhibiting a unique combination of gas-like viscosity and liquid-like density. This characteristic is pivotal to its mobility and storage behavior. A significant finding from the project, as highlighted by Wileman, was the observed variation in foam viscosity: it increased to a certain pressure point before suddenly dropping. This shear-thinning behavior means the foam’s viscosity decreases under higher shear rates, allowing it to flow more easily through high-permeability zones while diverting flow into less permeable regions. This property is crucial for improving sweep efficiency in EOR operations and for limiting CO2 channeling through fractures, thereby enhancing sequestration security.

Testing involved fractured sandstone rock and larger heterogeneous sand-packs, designed to accurately represent the complex underground formations encountered in oil fields. Wileman confirmed the stability of the foams under these challenging conditions, stating, “Our work is to show foams could be stable in high pressure and temperatures. We’re showing foam does remain stable.”

Despite the promising technical advancements, barriers to widespread adoption persist. Wileman identified two primary challenges: the high cost associated with the specialized equipment required to generate the foam and the consistent availability of CO2. Operators would need a reliable supply of CO2 to implement this technology on a commercial scale. While SwRI currently has no plans for a pilot project, the research team expresses keen interest in collaborating with industry partners to develop tailored applications for specific wells and to validate the equipment and processes in real-world scenarios. The potential to generate foam downhole, by integrating it into the alternating water and surfactant with gas (WAG) EOR process, offers a pathway to overcome some logistical hurdles.