Digital rock physics (DRP) workflow to assess reservoir flow characteristics

Understanding the petrophysical properties of reservoir rocks is crucial for hydrocarbon exploration and production. The evolution of digital rock physics (DRP) in recent years has led to vital improvements in core characterization and in high-quality special core analysis (SCAL) measurements. DRP can estimate petrophysical properties in sandstone reservoirs using digital models. For heterogeneous carbonates, it is difficult to capture the full range of the pore structure with a single imaging technique due to pore sizes ranging from nm to cm. This study aims to accurately characterize sandstone and carbonate core plugs permeability using DRP. In addition, effective and total porosity was evaluated for establishing trends with a variable range of permeability. Six representative sandstone outcrop samples were chosen for this study to cover different lithology types, and five carbonate samples from Middle Eastern reservoirs were selected. A multi-scale imaging approach using an X-ray computer tomography CT, a 3D X-ray microtomographic CT, an X-ray diffraction (XRD), and a quantitative evaluation of minerals using scanning electron microscopy (QEMSCAN) were performed on the samples. After laboratory measurements, the samples were scanned using an X-ray CT with a 1-mm resolution to evaluate the heterogeneity of the rock structure. A sub-plug was then extracted for high-resolution scanning at a resolution of 4 µm using an X-ray micro-CT. At this scale, pore connectivity can be revealed from top to bottom. The 3D images were analyzed using the PerGeos software. The connected porosity of the segmented pores was obtained using the PerGeos software, and flow characteristics were simulated with the Lattice-Boltzmann method (LBM) and compared with laboratory measurements. The porosity obtained using the PerGeos software was comparable to laboratory measurements. The permeability obtained using LBM was in good agreement with experimental results. For high-permeability samples, the difference between total and effective porosity was observed to be lower than in low-permeability samples. This study forms the basis for accurate porosity–permeability evaluation using LBM and conventional laboratory measurements. It also shows the importance and application of DRP for flow characterization of reservoir rock. The accurate estimation of flow characteristics contributes to a better understanding of reservoir evaluation and management and mastering the usage of DRP as a non-destructive tool to evaluate rock characteristics and compare them to standard laboratory practices.