Digital-Core-Based Numerical Simulation of Conductivity in Low-Permeability Sandstone Reservoirs

Conventional petrophysical experiments struggle to systematically quantify the impact of microstructural factors such as pore heterogeneity, fluid-rock interactions, and clay distributions on the electrical properties in low-permeability reservoirs. Digital core modeling addresses this gap by providing a pore-scale framework to characterize multiscale petrophysical responses, enabling precise correlations between rock microstructure and macroscale reservoir behavior. In this work, we employed finite element simulations on three-dimensional (3D) digital models to study anisotropic electrical conductivity. This approach allowed us to quantify the contributions of pore topology, formation water salinity, fluid saturation, and wettability to effective resistivity. Results demonstrate that while formation factor (F) follows Archie’s law as a function of porosity in low-permeability sandstones, resistivity index (I)-water saturation (Sw) relationships exhibit a bimodal trend at Sw ≈ 45%, deviating from classical Archie behavior. Wettability and salinity thresholds significantly alter Archie parameters, necessitating microstructural considerations for accurate Sw estimation in unconventional reservoirs. These findings underscore the importance of integrating pore-scale complexity into petrophysical models to improve resistivity-based saturation evaluations in tight hydrocarbon systems.