CO₂-WAG Injection and Hysteresis Effects: Insights for Improved Oil Recovery and Carbon Sequestration Applications

This study examines the impact of hysteresis effects on oil recovery during CO₂-Water Alternating Gas (WAG) injection, a widely applied enhanced oil recovery (EOR) technique with significant implications for carbon capture, utilization, and storage (CCUS). Hysteresis, which describes the cyclic variations in relative permeability during alternating imbibition and drainage cycles, plays a critical role in accurately modeling multiphase flow in porous media. However, its effects on CO₂-WAG efficiency remain underexplored in many reservoir simulations. To address this gap, a sector model was developed to simulate CO₂- WAG injection, incorporating hysteresis effects to assess their influence on oil recovery and CO₂ trapping. The results reveal that considering hysteresis leads to a 0.9% increase in the oil recovery factor, demonstrating its role in enhancing residual oil mobilization. Moreover, hysteresis significantly contributes to greater CO₂ retention within the reservoir, improving long-term sequestration potential and reducing gas production rates. The findings underscore the necessity of incorporating hysteresis in CO₂-WAG simulations to improve the accuracy of EOR performance predictions and optimize CCUS strategies. Neglecting hysteresis can lead to an underestimation of both oil recovery and CO₂ trapping potential, impacting reservoir management decisions. This study highlights the importance of precise relative permeability modeling in CO₂-WAG injection to ensure reliable performance forecasts and efficient field implementation.