Permeability from Microscopy: Review of a Dream

Korvin, Gábor

doi:10.1007/s13369-016-2138-y

Cited by 18 publications

(6 citation statements)

References 61 publications

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“…The tortuosity of pores was calculated using the Avizo Centroid Path Tortuosity module (Thermo Fisher Scientific & FEI, ). The Otsu method (Boone et al, ; Keller et al, ; Korvin, ; Otsu, ; Zhang et al, ), an automated threshold segmentation method in the Avizo Auto Thresholding module, was used to obtain the relationship between threshold and calculated porosity. By comparing the inversely estimated porosity with the measured porosity through NMR experiments, the optimal thresholds were selected to segment the pore volume in the VOIs of the artificial cores.…”

Section: Materials and Methods Core‐scale Pore Structure Reconstructiomentioning

confidence: 99%

Pore‐Scale Reconstruction and Simulation of Non‐Darcy Flow in Synthetic Porous Rocks

et al. 2018

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We image synthetic porous rocks of varied porosity and pore size by micro–computed tomography with pore‐scale finite element modeling representing the pore space for single‐phase fluid flow. The simulations quantify the key features of microscale flow behavior in the synthetic cores. The smaller the permeability, the greater the critical pressure gradient required for the onset of non‐Darcy fluid flows, and the easier the emergence of nonlinear seepage within the tested cores. The relationship between permeability and porosity from different methods shows a power law correlation with pressure. Structural heterogeneity and anisotropy of the pore systems are shown to have a significant impact on transport through the three‐dimensional pore model—exhibiting irregular flow fields. The simulated permeabilities of the tested cores vary by a factor of 2–5 depending on the fluid flow directions. With the increase of flow seepage velocity, the flow regime deviates from Darcy linear relationship and non‐Darcy behavior (inertia) leads to a reduction in the effective permeability of the core. Both experiments and modeling demonstrate that the larger the porosity and permeability, the stronger the non‐linear phenomenon of the seepage within the pore space. A method is proposed to estimate the non‐Darcy coefficient β based on simulation results, which provides a good prediction for all the tested cores. A new equation is established to predict the transition of flow patterns as a function of the apparent permeability K* and Reynolds number Re. The K*‐Re model provides a theoretical approach to dynamically describe the transition from Darcy to Forchheimer flow.

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Section: Materials and Methods Core‐scale Pore Structure Reconstructiomentioning

confidence: 99%

Pore‐Scale Reconstruction and Simulation of Non‐Darcy Flow in Synthetic Porous Rocks

et al. 2018

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“…Therefore, the SSA of clay is very important. There are four versions of SSA defined according to different disciplines and application scenarios [33,34].…”

Section: Definition and Application Of Specific Surface Area (Ssa) Inmentioning

confidence: 99%

Using the Effective Void Ratio and Specific Surface Area in the Kozeny–Carman Equation to Predict the Hydraulic Conductivity of Loess

Hong

Wang

et al. 2019

Water

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Many modified Kozeny-Carman (KC) equations have been used to predict the saturated permeability coefficient (K s ) of porous media in various fields. It is widely accepted that the KC equation applies to sand but does not apply to clay. Little information is available to clarify this point. The effectiveness of the KC equation will be evaluated via laboratory penetration tests and previously published data, which include void ratio, specific surface area (SSA), liquid limit (LL), and permeability coefficient values. This paper demonstrates how to estimate the SSA of cohesive soil from its LL. Several estimation algorithms for determining the effective void ratio (e e ) of cohesive soil are reviewed. The obtained results show that, compared to the KC equation based on porosity and geometric mean particle size (D g ), the KC equation based on the SSA and the e e estimation algorithm can best predict the K s of remolded loess. Finally, issues associated with the predictive power of the KC equation are discussed. Differences between measured and the predicted K s values may be caused by the uniformity of the reconstructed specimen or insufficient control of the test process and errors in the SSA and e e .

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“…To select optimal thresholds for the segmentation of pores in the two types of sandstone, the effects of thresholds on the 3-D volumetric porosities and tortuosity of pores were calculated and listed in Table 3. The Otsu method [Otsu, 1979;Boone et al, 2014;Korvin, 2016;Sekkat et al, 2011;Zhang et al, 2015]-an auto threshold selection method exploited in Avizo Auto Thresholding module-was used to obtain the relationships between threshold and calculated porosity for two types of sandstone. By comparing the calculated porosity with the measured porosity by MIP, 54 and Journal of Geophysical Research: Solid Earth 10.1002/2016JB013786 27 were set as the thresholds to segment the pore volume in the VOIs of the silty sandstone and the coarsegrained sandstone, respectively.…”

Section: High-resolution X-ray Ct Imagingmentioning

confidence: 99%

Effects of microstructure on water imbibition in sandstones using X‐ray computed tomography and neutron radiography

et al. 2017

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Capillary imbibition in variably saturated porous media is important in defining displacement processes and transport in the vadose zone and in low‐permeability barriers and reservoirs. Nonintrusive imaging in real time offers the potential to examine critical impacts of heterogeneity and surface properties on imbibition dynamics. Neutron radiography is applied as a powerful imaging tool to observe temporal changes in the spatial distribution of water in porous materials. We analyze water imbibition in both homogeneous and heterogeneous low‐permeability sandstones. Dynamic observations of the advance of the imbibition front with time are compared with characterizations of microstructure (via high‐resolution X‐ray computed tomography (CT)), pore size distribution (Mercury Intrusion Porosimetry), and permeability of the contrasting samples. We use an automated method to detect the progress of wetting front with time and link this to square‐root‐of‐time progress. These data are used to estimate the effect of microstructure on water sorptivity from a modified Lucas‐Washburn equation. Moreover, a model is established to calculate the maximum capillary diameter by modifying the Hagen‐Poiseuille and Young‐Laplace equations based on fractal theory. Comparing the calculated maximum capillary diameter with the maximum pore diameter (from high‐resolution CT) shows congruence between the two independent methods for the homogeneous silty sandstone but less effectively for the heterogeneous sandstone. Finally, we use these data to link observed response with the physical characteristics of the contrasting media—homogeneous versus heterogeneous—and to demonstrate the sensitivity of sorptivity expressly to tortuosity rather than porosity in low‐permeability sandstones.

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Permeability from Microscopy: Review of a Dream

Cited by 18 publications

References 61 publications

Pore‐Scale Reconstruction and Simulation of Non‐Darcy Flow in Synthetic Porous Rocks

Pore‐Scale Reconstruction and Simulation of Non‐Darcy Flow in Synthetic Porous Rocks

Using the Effective Void Ratio and Specific Surface Area in the Kozeny–Carman Equation to Predict the Hydraulic Conductivity of Loess

Effects of microstructure on water imbibition in sandstones using X‐ray computed tomography and neutron radiography

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