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- ItemEnhanced pore space analysis by use of Ī¼-CT, MIP, NMR, and SIP(Gƶttingen : Copernicus Publ., 2018) Zhang, Zeyu; Kruschwitz, Sabine; Weller, Andreas; Halisch, MatthiasWe investigate the pore space of rock samples with respect to different petrophysical parameters using various methods, which provide data on pore size distributions, including micro computed tomography (Ī¼-CT), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and spectral-induced polarization (SIP). The resulting cumulative distributions of pore volume as a function of pore size are compared. Considering that the methods differ with regard to their limits of resolution, a multiple-length-scale characterization of the pore space is proposed, that is based on a combination of the results from all of these methods. The approach is demonstrated using samples of Bentheimer and Rƶttbacher sandstone. Additionally, we compare the potential of SIP to provide a pore size distribution with other commonly used methods (MIP, NMR). The limits of resolution of SIP depend on the usable frequency range (between 0.002 and 100āHz). The methods with similar resolution show a similar behavior of the cumulative pore volume distribution in the overlapping pore size range. We assume that Ī¼-CT and NMR provide the pore body size while MIP and SIP characterize the pore throat size. Our study shows that a good agreement between the pore radius distributions can only be achieved if the curves are adjusted considering the resolution and pore volume in the relevant range of pore radii. The MIP curve with the widest range in resolution should be used as reference.
- ItemDevelopment of a numerical workflow based on Ī¼-CT imaging for the determination of capillary pressureāsaturation-specific interfacial area relationship in 2-phase flow pore-scale porous-media systems: a case study on Heletz sandstone(Gƶttingen : Copernicus Publ., 2016) Peche, Aaron; Halisch, Matthias; Bogdan Tatomir, Alexandru; Sauter, MartinIn this case study, we present the implementation of a finite element method (FEM)-based numerical pore-scale model that is able to track and quantify the propagating fluidāfluid interfacial area on highly complex micro-computed tomography (Ī¼-CT)-obtained geometries. Special focus is drawn to the relationship between reservoir-specific capillary pressure (pc), wetting phase saturation (Sw) and interfacial area (awn). The basis of this approach is high-resolution Ī¼-CT images representing the geometrical characteristics of a georeservoir sample. The successfully validated 2-phase flow model is based on the NavierāStokes equations, including the surface tension force, in order to consider capillary effects for the computation of flow and the phase-field method for the emulation of a sharp fluidāfluid interface. In combination with specialized software packages, a complex high-resolution modelling domain can be obtained. A numerical workflow based on representative elementary volume (REV)-scale pore-size distributions is introduced. This workflow aims at the successive modification of model and model set-up for simulating, such as a type of 2-phase problem on asymmetric Ī¼-CT-based model domains. The geometrical complexity is gradually increased, starting from idealized pore geometries until complex Ī¼-CT-based pore network domains, whereas all domains represent geostatistics of the REV-scale core sample pore-size distribution. Finally, the model can be applied to a complex Ī¼-CT-based model domain and the pcāSwāawn relationship can be computed.