Comprehensive experimental study to compare the effects of flue gases and CO 2 injection on enhancing oil recovery and asphaltene deposition

Non-hydrocarbon injection gases, such as carbon dioxide (CO ₂ ) and flue gas, offer cost-effective and environmentally friendly alternatives to traditional hydrocarbon gases for enhanced oil recovery (EOR). However, issues such as asphaltene deposition and formation damage challenge their use in tight carbonate reservoirs. While CO ₂ injection has been extensively studied, experimental data on flue gas remain limited. This study presents a detailed experimental comparison of CO ₂ and synthetic flue gas through eight core flooding tests using recombined live oil and two low-permeability carbonate cores. Effects of gas type, pressure, temperature, and injected gas volume on oil recovery, asphaltene deposition, and permeability reduction were evaluated. CO ₂ injection yielded approximately 15% higher oil recovery than flue gas at the same pressure. However, for equal injected volumes, the flue gas achieved 16 to 46% higher recovery, indicating a more efficient use. Comparable oil recovery was achieved by injecting flue gas at 20 to 30% higher pressure with 10 to 15% less gas volume. Additionally, CO ₂ caused up to 18.6% more asphaltene deposition and 67% more formation damage than flue gas under identical conditions. This study also investigates the role of injection pressure and temperature in influencing formation damage behavior. The results confirm that flue gas injection can be used as an alternative to CO ₂ for EOR in carbonate reservoirs.