Simulation-driven sensitivity analysis and optimization of critical parameters for maximizing CO2-EOR efficiency

Abstract

The application of Carbon Dioxide (CO₂) injection in enhanced oil recovery (EOR) has evolved, making a major benefit for increasing the production level from mature reservoirs. This paper investigates the optimization of the CO₂-EOR process based on using a new mode of simulation-based sensitivity analysis to understand two main proposed strategies, namely continuous gas injection and water-alternating-gas (WAG) injection. Prominent dynamical features including multiphase flow and displacement mechanisms were effectively captured in the form of a detailed reservoir model developed with considerable care for both techniques. The performance of each injection method was determined from a comprehensive analysis on the major production performance metrics: i) Oil recovery factor, ii) Gas-oil ratio iii) Cumulative oil production. Applying a wide range of sensitivity methods that included proxy model, Morris analysis and Sobol method were used to analyze the main parameters affecting the effectiveness of CO₂ injection. The analysis then produced an optimization framework highlighting conditions conducive to achieving maximum oil recovery. The results of the study point to the effectiveness of WAG injection strategy in promoting oil recovery through better mobility control and lower gas breakthrough risk compared with continuous gas injection. This approach enhances sweep efficiency and highlights the significance of selecting appropriate injection strategies to maximize recovery in immiscible CO₂ flooding processes. The alternating phases of water and CO₂ in the Water-Alternating-Gas (WAG) process are crucial for optimizing oil recovery outcomes.