Upscaling Nanoscale Clay Features for Improved Tight Sandstone Reservoir Characterization: Case Study from Gulf of Thailand

This study presents a novel Digital Rock Physics (DRP) workflow to characterize tight sandstones with high clay content. Traditional micro-CT (µCT) imaging often fails to resolve nanoscale pores within clays, leading to underprediction of key properties like absolute permeability and mercury injection capillary pressure (MICP). To overcome this, the authors integrate high-resolution 2D SEM images and stochastic modeling to generate nanoscale clay structures. These models capture the pore morphology of illite and kaolinite, and their permeability and MICP curves are simulated using fluid flow solvers. The nanoscale results are then upscaled and embedded into the larger µCT-based plug-scale models, improving predictions of reservoir properties. The final digital rock models show strong agreement with experimental data, demonstrating the method’s ability to address imaging limitations and enhance the accuracy of DRP for heterogeneous, dual-porosity rocks.