Ensemble Score Filter for Data Assimilation of Two-Phase Flow Models in Porous Media

Ruoyu Hu; Sanjeeb Poudel; Feng Bao; Sanghyun Lee

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arXiv · 2504.09245

Ensemble Score Filter for Data Assimilation of Two-Phase Flow Models in Porous Media

Ruoyu Hu·Sanjeeb Poudel·Feng Bao·Sanghyun Lee

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Abstract

Numerical modeling and simulation of two-phase flow in porous media is challenging due to the uncertainties in key parameters, such as permeability. To address these challenges, we propose a computational framework by utilizing the novel Ensemble Score Filter (EnSF) to enhance the accuracy of state estimation for two-phase flow systems in porous media. The forward simulation of the two-phase flow model is implemented using a mixed finite element method, which ensures accurate approximation of the pressure, the velocity, and the saturation. The EnSF leverages score-based diffusion models to approximate filtering distributions efficiently, avoiding the computational expense of neural network-based methods. By incorporating a closed-form score approximation and an analytical update mechanism, the EnSF overcomes degeneracy issues and handles high-dimensional nonlinear filtering with minimal computational overhead. Numerical experiments demonstrate the capabilities of EnSF in scenarios with uncertain permeability and incomplete observational data.

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Ruoyu Hu, Sanjeeb Poudel, Feng Bao, Sanghyun Lee. 2025-05-11. Ensemble Score Filter for Data Assimilation of Two-Phase Flow Models in Porous Media. https://arxiv.org/abs/2504.09245

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