Crude Oil Oxidation in an Air Injection Based Enhanced Oil RecoveryProcess: Chemical Reaction Mechanism and Catalysis

Air injection as a thermal method for heavy oilrecovery has a long history of about a century. However, it has notbeen widely applied in oilfields to date because of many challengescaused by its technical complexity. In the last two decades, moreand more attention has been paid to the air injection techniquebecause of the increasing demand for the effective development ofhard-to-recover resources, including heavy oil, bitumen, oil shale,water-flooded mature reservoirs, etc. in a more energy-saving, cost-effective, environmentally friendly way. Consequently, manyconsiderable improvements in both theory and technology havebeen made recently. This workfirst reviews the recent advances inthe reaction mechanism of crude oil oxidation with highlights onthe difference and connection between the oxidation of different oilcomponents as well as their interaction during cocombustion; then, it discusses the catalytic methods for intensifying crude oilcombustion with different types of catalysts, including nanometal-based particles, water-soluble metallic salts, and oil-dispersedmetal-based catalysts. On the basis of the detailed review and discussion, we shed light on the challenges facing the air injectionprocess and put forward possible methods to solve them. Simultaneously, we point out the neglected aspects of the air injectionprocess and open the way toward fresh thinking for its technical application. Andfinally, we propose promising perspectives forfuture work for improving the performance of air injection and its wide application