A Review of the Application of Non-Condensable Gases in Heavy Oil: Recovery Methods, Techniques, and Parametrization Employing Experiments, Simulations, and Field Implementations

Abstract

The use of steam-based thermal recovery techniques in heavy oil exploitation faces critical limitations in deep formations, aquifer-bearing reservoirs, and formations with high clay content. This has motivated increasing research interest in the use of non-condensable gases (NCGs; mainly CO2, N2, and flue gas) in this context. This review systematically synthesizes the results of experiments, numerical simulations, and field implementations related to NCG-enhanced heavy oil recovery, with special emphasis on clarifying ambiguous recovery mechanisms, comparing the performance under different injection modes, and describing key controlling parameters and existing technical bottlenecks. CO2 mainly contributes to oil mobilization by reducing oil viscosity and causing oil swelling after dissolution, while N2 primarily maintains reservoir pressure. Flue gas combines the advantages of both of these gases. Of the different injection patterns, cyclic huff and puff has received the most research attention, whereas studies on steam-assisted gravity drainage (SAGD) with NCGs remain insufficient. When co-injected with steam, NCGs can elevate reservoir pressure and mitigate steam heat loss; nevertheless, multiple potential mechanisms, including interfacial tension reduction, water wettability alteration, and solution gas drive, have not been quantitatively characterized. Our review shows that most existing laboratory and simulation investigations have adopted single-factor analysis, and multi-factor coupling evaluation considering reservoir fluid properties is urgently required. N2 foam flooding effectively suppresses detrimental gas channeling and steam override. Field cases demonstrate that combined steam flue gas injection can achieve up to 79% original oil in place (OOIP) recovery, yet gas channeling and asphaltene precipitation still restrain field performance. This work further summarizes field-scale failure triggers, identifies critical research gaps, and provides targeted suggestions for future laboratory optimization and pilot scheme design for NCG applications in heavy oil reservoirs.