Coupled Multiphase Flow and Poromechanics: Insights into the Effect of Capillarity on Strain Localization from High-Resolution GPU Simulations

Coupled multiphase flow and poromechanics play a fundamental role in various Earth science applications, from subsurface energy extraction to induced seismicity. However, the inherent complexity of subsurface environments—characterized by fluid compressibility, capillary effects, and heterogeneous permeability—poses significant computational challenges, particularly in high-resolution three-dimensional simulations.

To overcome these challenges, we develop a high-performance computational framework optimized for Graphics Processing Units (GPUs) to simulate two-phase flow in deformable porous media. Our approach introduces a novel formulation of the poro-visco-elasto-plastic equations, explicitly designed for GPU architectures. This framework accounts for compressible fluids with capillary pressure effects and employs a customized iterative solver that enhances computational efficiency. By leveraging modern GPU hardware, we enable large-scale simulations with unprecedented spatial resolution, facilitating faster computations and significantly larger grid sizes than previously achievable.

Our results reveal that within shear bands, pressure drops occur similarly to single-phase fluid environments. However, in our two-phase flow model, pressure evolves differently due to the influence of strain localization on capillary pressure. This interaction between multiphase flow and mechanical deformation introduces new physical insights, suggesting that strain localization may play a critical role in modifying fluid distributions and capillary effects. These findings offer a deeper understanding of two-phase flow behavior in deforming porous media, with implications for geomechanics, fault stability, and fluid-driven deformation processes.