A multiscale LBM-TPM-PFM approach for modeling of multiphase fluid flow in fractured porous media

In this paper, we present a reliable micro-to-macroscale framework to model multiphase fluid flow through fractured porous media. This is based on utilizing the capabilities of the lattice Boltzmann method (LBM) within the phase-field modeling (PFM) of fractures in multiphase porous media. In this, we propose new physically motivated phase-field-dependent relationships for the residual saturation, the intrinsic as well as relative permeabilities. In addition, an anisotropic, phase-field-dependent intrinsic permeability tensor for the fractured porous domains is formulated, which relies on the single- and multiphasic LBM flow simulations. Based on these results, new relationships for the variation of the macroscopic theory of porous media (TPM)-PFM model parameters in the transition zone are proposed. Whereby, a multiscale concept for the coupling between the multiphasic flow through the crack on one hand and the porous ambient, on the other hand, is achieved. The hybrid model is numerically applied on a real microgeometry of fractured porous media, extracted via X-ray microcomputed tomography data of fractured Berea Sandstone. Moreover, the model is utilized for the calculation of the fluid leak-off from the crack to the intact zones. Additionally, the effects of the depth of the transition zone and the orientation of the crack channels on the amount of leakage flow rates are studied. The outcomes of the numerical model proved the reliability of the multiscale model to simulate multiphasic fluid flow through fractured porous media.

Automated summary

In this paper, a reliable micro-to-macroscale framework is presented to model multiphase fluid flow through fractured porous media. The lattice Boltzmann method (LBM) is utilized within the phase-field modeling (PFM) of fractures to achieve this. New phase-field-dependent relationships for various parameters are proposed and a multiscale concept for coupling is achieved. Numerical simulations on real microgeometries of fractured porous media validate the reliability of the model.