A review of recent developments in CO₂ mobility control in enhanced oil recovery

<div>Carbon dioxide-enhanced oil recovery (CO₂-EOR) has gained widespread attention in light of the declining conventional oil reserves. Moreover, CO₂-EOR contributes to the reduction of the global emissions of greenhouse gases through CO₂ sequestration in subsurface geologic formations. This method has been largely used in the petroleum industry for several decades especially for extracting oil from light-to-medium oil reservoirs approaching an advanced state of maturity. Traditionally, CO₂ is used in a continuous flooding scheme for EOR. However, continuous CO₂ flooding tends to be problematic due to unfavorable mobility, viscous fingering/channeling and early breakthrough of CO₂, especially in the presence of reservoir heterogeneities. In this paper, recent developments in the methods used to overcome these problems are reviewed. These developments include CO₂water-alternating-gas (WAG) injection, polymer-assisted CO₂ injection, surfactant-assisted CO₂mobility control (CO₂-foam injection), and nanoparticle-assisted CO₂ flooding. Each method addresses, to an extent, one or more of the problems associated with conventional CO₂ flooding. Furthermore, incorporating more than one method can provide better performance in terms of CO₂ mobility control and oil recovery. In comparison with CO₂-WAG and CO₂-foam injection methods, the use of polymers and nanoparticles with CO₂ flooding is relatively new. These two new methods were mostly investigated experimentally, at the laboratory level, and they still need further development prior to field implementation.</div> <h2>Other Information</h2> <p>Published in: Petroleum<br> License: <a href="http://creativecommons.org/licenses/by-nc-nd/4.0/" target="_blank">http://creativecommons.org/licenses/by-nc-nd/4.0/</a><br> See article on publisher's website: <a href="https://dx.doi.org/10.1016/j.petlm.2021.05.002" target="_blank">https://dx.doi.org/10.1016/j.petlm.2021.05.002</a></p>