CO₂ injection for enhanced oil recovery: A review of existing methods, challenges and promising solutions

Carbon dioxide injection for enhanced oil recovery is a key technology that combines increased hydrocarbon extraction with CO₂ storage. However, existing literature mostly describes isolated solutions and rarely offers a comparative systematization of methods considering their practical limitations and industrial results. The purpose of this review is to systematize CO₂ enhanced oil recovery methods and summarize the experience of the world largest projects to develop a comprehensive approach to selecting injection schemes under various geological and technological conditions. Based on an analysis of more than 100 studies, carbon dioxide enhanced oil recovery methods in this work are classified by injection type and additives used. For each method, the main recovery mechanisms are summarized, including fluid mobility control, wettability modification, and asphaltene deposition inhibition. An analysis of major industrial projects in North America, China, and Europe, conducted in the paper, showed up to 25% increase in oil recovery with optimized water-alternating-gas schemes. Pore-scale visualization studies show that CO₂ flow involves unsteady effects like snap-off and cyclic bubble dilation. These phenomena explain channel formation and early gas breakthrough, justifying the need for mobility control methods. Synthesis of the results identified three prioritized technological limitations: First, the reliability of CO₂ infrastructure and supply; second, control of the displacement profile in heterogeneous reservoirs; and third, long-term well integrity and CO₂ balance management. These findings support the selection of optimal carbon dioxide enhanced oil recovery schemes and future research priorities.