Effect of reservoir heterogeneity on well placement prediction in CO2-EOR projects using machine learning surrogate models: Benchmarking of boosting-based algorithms

Rising Carbon Dioxide (CO2) levels from human activities are driving climate change. Carbon capture and storage (CCS) during enhanced oil recovery (EOR) in underground reservoirs offer both environmental and economic benefits. This method boosts oil production, cuts greenhouse gas emissions, and supports sustainable energy. Precise well placement in CO2-EOR is a crucial task for effective oil displacement, but traditional reservoir simulators are costly. This study explores and compares boosting algorithms, as fast surrogate models, to achieve accurate well placement during CO2-EOR in light oil carbonate reservoirs. The research considers various reservoir scenarios with different geological heterogeneity levels (i.e., homogeneous, moderately heterogeneous, and highly heterogeneous reservoirs). Various parameters, such as injection and production well locations, the distance between production and injection wells in an inverted five-spot pattern, pattern angle, and injection and production rates are explored using a compositional reservoir simulator to assess their impact on the well placement problem. A comprehensive analysis of various boosting algorithms, including AdaBoost, CatBoost, Gradient Boosting, LightGBM, and XGBoost is performed using the simulated dataset to assess their efficacy. The results demonstrate that LightGBM outperformed the other algorithms with the lowest Mean Absolute Error and Root Mean Square Error of 115.3 × 106 $ and 188.2 × 106 $, respectively. Additionally, it demonstrates exceptional speed, averaging 3 to 8 times faster than other boosting algorithms in the three reservoir scenarios. This superior performance coupled with its efficient runtime makes LightGBM the ideal choice for the study objectives. Moreover, the mass balance approach highlights the significant CO2 storage efficiency, emphasizing the effectiveness of CO2-EOR in storing CO2 in underground heterogeneous reservoirs.