Stacking Learning for Smart Proxy Modeling in CO₂-WAG Optimization: A Techno-Economic Approach to Sustainable...

Climate change and greenhouse gas emissions are critical global challenges, driving the need for innovative solutions to reduce carbon footprints while meeting energy demands. This study addresses these challenges by optimizing the CO₂-WAG (water-alternating gas) injection process, a technique that enhances oil recovery while sequestering carbon dioxide in oil reservoirs. The optimization framework integrates machine learning methods with the non-dominated sorting genetic algorithm II (NSGA-II) to simultaneously maximize cumulative oil production and CO₂ sequestration, minimize water production, and ensure economic viability through the net present value (NPV) objective function. The study employs stacking learning to develop smart proxy models, which significantly reduce computational time while maintaining high accuracy in predicting objective functions. These models are trained on a comprehensive data set generated from reservoir simulations, enabling efficient optimization across diverse reservoir conditions. The NSGA-II algorithm is used to generate a three-dimensional Pareto front, representing optimal trade-offs between the conflicting objectives. To facilitate decision-making, a clustering-based approach is introduced, categorizing solutions into groups such as gold, silver, and bronze based on their performance metrics. The results demonstrate the effectiveness of the proposed framework, with the NSGA-II algorithm producing 500 optimal solutions on the Pareto front. Among these, 60 solutions are identified as gold, offering the best balance between technical and economic objectives. Compared to previous studies, the introduced framework significantly improves computational efficiency and prediction accuracy, reducing optimization time while maintaining high precision in the results. This approach not only enhances the accuracy of CO₂-WAG optimization but also provides a scalable and adaptable framework for sustainable oil recovery and carbon management in various reservoir settings.