Pore Structure Characterization and Single-Phase Flow Analysis of Glutenite and Pebbly Sandstone Reservoir Samples from the D84 Block Using CT Digital Cores

Pore-scale heterogeneity is an important consideration in the evaluation of heavy-oil reservoirs. The aim of this study was to reconstruct CT-based digital cores of four plug samples, characterize their pore structures, and analyze single-phase flow behavior, in order to clarify how pore geometry and segmentation control the computed porosity and permeability. Four plug samples (two glutenite and two pebbly sandstone) from the Guantao Formation of the D84 Block, Liaohe Depression, were investigated using X-ray micro-computed tomography (micro-CT) with an isotropic voxel size of 9.37 μm. Three-dimensional digital cores were reconstructed through image preprocessing and interactive threshold segmentation. CT-derived porosity, volume-weighted equivalent-diameter distributions of labeled pore objects, and axial porosity variability were analyzed. Single-phase flow simulations were performed in PerGeos to estimate permeability and visualize streamline and pressure distributions. The CT-derived porosities ranged from 27.37% to 32.92%, whereas the simulated permeabilities ranged from 1009 to 1477 mD. ZS-1 exhibited the lowest CT-derived porosity but the highest simulated permeability, indicating that bulk porosity alone did not fully account for variations in simulated flow behavior among the four samples. The simulated permeabilities were lower than the laboratory-measured values, with relative differences ranging from 10.6% to 52.4%. These differences highlight the influence of image resolution, segmentation, and differences between numerical and experimental conditions on image-based permeability estimation. The study provides a sample-scale characterization of pore structures and single-phase flow behavior in the investigated reservoir material.