CO ₂ Huff and Puff under Relative Permeability Hysteresis Impact for Enhanced Oil Recovery in Gas Condensate Reservoir: A Sensitive Parametric Study

CO2 huff-and-puff method is an effective enhanced oil recovery (EOR) method for gas-condensate reservoirs; however, optimizing this cyclic process is challenging due to oil re-evaporation and the underexplored influence of relative permeability hysteresis. This study addresses this gap by integrating an accurate hysteresis model into huff-and-puff optimization analysis for the first time. Compositional reservoir simulations were conducted using CMG-GEM with a three-phase hysteresis model (Larsen and Skauge) to capture fluid trapping and reimbibition effects. A gas-condensate reservoir model, representing field conditions, was simulated with six cycles of CO2 injection, soaking, and production. The study varied key parameters: initiation timing (25% above, at, and 25% below dew point pressure), soaking duration (20, 40, and 60 days), and CO2 mass injection (1, 2, and 3% of total pore volume). Both hysteresis and nonhysteresis scenarios were considered, with natural depletion as the base case. A sensitivity analysis using CMOST AI assessed the impact of these parameters and hysteresis on the recovery and CO2 trapping performance. The findings indicated that maximizing recovery requires balancing residual oil saturation and oil revaporization under optimal operational parameters. Furthermore, the increase in the level of CO2 trapping due to hysteresis enhances oil recovery, while sensitivity analyses identify key operational controls. Specifically, the flow rate dominates performance below the dew point, whereas injection volume and hysteresis parameters have a greater impact above the dew point. Overall, these findings demonstrated that incorporating hysteresis into the CO2 huff-and-puff optimization is essential for gas-condensate reservoir EOR, as it refines recovery predictions and helps guide the selection of injection strategies to maximize condensate production.