Pore-Scale Simulation of Flow and Heat Transfer in Heterogeneous Rock Cores under Thermal-Hydraulic coupling

Rock formations act as a critical medium in subsurface resource development, where macroscopic reservoir recovery efficiency is governed by randomly distributed heterogeneous micropores and fractures. A thorough understanding of how rock microstructure influences flow and heat transfer is essential for accurate prediction of resource migration. In this study, three-dimensional rock core models, including homogeneous, heterogeneous, and fractured configurations, are reconstructed using the quartet structure generation set (QSGS) algorithm. A pore-scale thermal-hydraulic coupled model is developed with the lattice Boltzmann method (LBM) to simulate and analyze the physical field distributions. Comparative results indicate that the growth direction of the solid skeleton significantly affects flow and heat transfer paths. When skeleton growth is preferentially oriented along the mainstream direction, efficient seepage channels form, leading to enhanced convective heat transfer through increased flow velocity. By contrast, when oriented along the primary heat transfer direction, efficient conductive paths are provided, promoting convective heat transfer via an increased effective temperature difference. Fractures substantially alter local flow and heat transfer, creating high-velocity channels that greatly improve permeability and overall heat transfer capacity, with effects intensifying continuously as fracture aperture increases.