Machine Learning Models for CO₂ WAG and SAG in an Open-Source Environment Open-Source Predictive Models for Optimizing CO₂-EOR

Open-source predictive models for optimizing CO₂ injection into reservoirs

The pre-implementation evaluation of CO₂ injection in enhanced oil recovery (CO₂-EOR) and geological storage processes requires running hundreds or thousands of numerical simulations to compare injection strategies such as WAG (Water Alternating Gas) and SAG (Surfactant Alternating Gas). However, these simulations are computationally expensive and often rely on commercial software, which limits their scientific reproducibility; to address this, predictive models—known as proxy models—can be developed.

In this study, machine learning-based proxy models—also known as smart proxy models (SPMs)—were developed using exclusively open-source tools: OPM Flow for numerical simulation, Python for automation, and Scikit-learn for implementing machine learning algorithms, all within a fully reproducible workflow.

The SPMs developed in this study are capable of predicting cumulative oil and gas production and CO₂ retention in WAG and SAG models, using datasets of 100 and 300 simulations (SPE CSP-5) and algorithms such as K-nearest neighbors, decision trees, random forest, and gradient boosting regressor (GBR). With 300 simulations, the GBR achieved high accuracy (R² > 0.995 for CO₂ sequestration, ≈ 0.999 for oil produced, and > 0.990 for gas produced), with an RMSE of less than 1%, demonstrating its potential as an efficient tool for prediction and decision-making in reservoir engineering that is accessible to all.

Participating researchers

FICT – ESPOL

  • Jorge Rodrigo Lliguizaca-Davila

  • Freddy Carrión Maldonado

  • Jorge Segundo Mendoza Sanz

Collaboration

University of Bergen (UiB), Norway

  • David Landa Marbán

  • Jorge Rodrigo Lliguizaca-Davila

  • Hilde Halsøy

  • Jacquelin E. Cobos

  • Zachary Paul Alcorn

DOI: https://doi.org/10.1016/j.petlm.2026.02.003

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