scholarly journals FRACTAL PARAMETERS OF PORE SPACE FROM CT IMAGES OF SOILS UNDER CONTRASTING MANAGEMENT PRACTICES

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440011 ◽  
Author(s):  
F. J. MUÑOZ ◽  
F. SAN JOSÉ MARTÍNEZ ◽  
F. J. CANIEGO
Keyword(s):  
Pore Size ◽  
Soil Structure ◽  
Management Practices ◽  
Pore Space ◽  
Fractal Dimensions ◽  
Soil Management ◽  
Ct Images ◽  
Pore Size Distributions ◽  
Fractal Parameters

Soil structure plays an important role in flow and transport phenomena, and a quantitative characterization of the spatial heterogeneity of the pore space geometry is beneficial for prediction of soil physical properties. Morphological features such as pore-size distribution, pore space volume or pore–solid surface can be altered by different soil management practices. Irregularity of these features and their changes can be described using fractal geometry. In this study, we focus primarily on the characterization of soil pore space as a 3D geometrical shape by fractal analysis and on the ability of fractal dimensions to differentiate between two a priori different soil structures. We analyze X-ray computed tomography (CT) images of soils samples from two nearby areas with contrasting management practices. Within these two different soil systems, samples were collected from three depths. Fractal dimensions of the pore-size distributions were different depending on soil use and averaged values also differed at each depth. Fractal dimensions of the volume and surface of the pore space were lower in the tilled soil than in the natural soil but their standard deviations were higher in the former as compared to the latter. Also, it was observed that soil use was a factor that had a statistically significant effect on fractal parameters. Fractal parameters provide useful complementary information about changes in soil structure due to changes in soil management.

scholarly journals Influence of cropping and fertilization on soil pore characteristics in a long-term field study

2020 ◽  
Author(s):  
David Nimblad Svensson ◽  
Jumpei Fukumasu ◽  
Gunnar Börjesson ◽  
John Koestel
Keyword(s):  
Organic Carbon ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Soil Structure ◽  
Management Practices ◽  
Pore Space ◽  
Pore Characteristics ◽  
Bare Fallow ◽  
Term Field

<p>Soil porosity, pore size distribution and pore characteristics such as connectivity are important for a range of soil processes including ease of root growth and air and water transport. The pore structure is therefore an important part of soil fertility. The pore space is sensitive to management practices such as tillage, fertilization and cropping. Understanding how these practices influence the pore space is important for maintaining a good soil structure that is well aerated and has sufficient drainage. X-ray computed tomography has become a widely used method for studying the pore space as it offers the advantage of enabling soil to be studied in its undisturbed form. In this study it was used to compare the effects of crop growth, tillage and N-fertilizing with Ca(NO3)<sub>2</sub> or farm yard manure (FYM). Soil samples were taken just below the surface from the long-term experiment in Ultuna, Sweden which was started in 1956. The bare fallow, FYM and Ca(NO3)<sub>2</sub>-treatment were sampled with minimum disturbance in two column sizes with inner diameters of 22.2 and 65.5 mm. Differences in pore space morphology were quantified and compared through pore size distribution and a range of connectivity measures, including the Euler number, the critical pore diameter and Gamma connectivity. Biopores were separated from non-biopores and their volume was quantified. Soil organic carbon was determined by dry combustion. Visible porosity and pores in the 150-500 µm class were significantly larger in the FYM and Ca(NO3)<sub>2</sub>-treatment compared to the bare fallow. The porosity occupied by biopores was not found to significantly differ between treatments but the biopores were found to have the largest diameters in the FYM-treatment. Despite that the organic carbon content was 1.7 times higher in the FYM compared to the Ca(NO3)<sub>2</sub>-treatment the visible porosity was similar. This may be due to the positive effects calcium has on the soil structure. The connectivity measures indicated that the FYM-treatment had the best connected pore networks. This may be partly due to the larger biopores. Ca(NO3)<sub>2</sub> showed to be a promising alternative to increase porosity. However, as all the management practices in the long-term field study are done by hand, future studies will have to investigate if the effect is equally similar to FYM under field conditions which are subject to heavy machineries.  </p>

scholarly journals Enhanced pore space analysis by use of μ-CT, MIP, NMR, and SIP

2018 ◽  
Author(s):  
Zeyu Zhang ◽  
Sabine Kruschwitz ◽  
Andreas Weller ◽  
Matthias Halisch
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Pore Space ◽  
Volume Distribution ◽  
Micro Computed Tomography ◽  
Pore Size Distributions ◽  
Scale Characterization ◽  
Relevant Range ◽  
Good Agreement

Abstract. We investigate the pore space of rock samples with respect to different petrophysical parameters using various methods, which provide data upon pore size distributions, including micro computed tomography (μ-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 geometry 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 Röttbacher 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 Hz and 100 Hz). The methods with similar resolution show a similar behavior of the cumulative pore volume distribution in the overlapping pore size range. We assume that μ-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 radii 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.

scholarly journals Enhanced pore space analysis by use of <i>μ</i>-CT, MIP, NMR, and SIP

Solid Earth ◽  
2018 ◽  
Vol 9 (6) ◽  
pp. 1225-1238 ◽  
Author(s):  
Zeyu Zhang ◽  
Sabine Kruschwitz ◽  
Andreas Weller ◽  
Matthias Halisch
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Pore Space ◽  
Volume Distribution ◽  
Micro Computed Tomography ◽  
Pore Size Distributions ◽  
Scale Characterization ◽  
Relevant Range ◽  
Good Agreement

Abstract. We 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 (μ-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 Röttbacher 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 100 Hz). The methods with similar resolution show a similar behavior of the cumulative pore volume distribution in the overlapping pore size range. We assume that μ-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.

CHARACTERIZATION OF PORE SIZE DISTRIBUTIONS USING NON-NEWTONIAN FLUIDS

2020 ◽  
Author(s):  
Scott C. Hauswirth ◽  
◽  
Majdi Abou Najm ◽  
Christelle Basset
Keyword(s):  
Pore Size ◽  
Newtonian Fluids ◽  
Size Distributions ◽  
Pore Size Distributions

Cementitious Sealing Material: 3D Digital Image Based Characterization of Pore Size Distribution and Modeling of Transport Properties

2013 ◽  
Author(s):  
Neven Ukrainczyk ◽  
Eduardus A. B. Koenders ◽  
Klaas van Breugel
Keyword(s):  
Pore Size ◽  
Transport Properties ◽  
Digital Image ◽  
Oil And Gas ◽  
Transport Model ◽  
Medial Axis ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Pore Size Distributions

Exhausted oil and gas reservoirs are one of the most potential storage facilities to sequestrate the worlds CO2. These reservoirs are sealed with cementitious materials, that should have a long time performance. Therefore, this paper emphasizes the characterization of the evolving capillary pore network and transport properties of the cementitious microstructure used to seal the wellbore. The Hymostruc numerical model is employed to simulate the development of an evolving virtual microstructure of cementitious materials. The simulated 3D microstructures were then digitized to form a matrix of cubic voxels. The pore-size distributions of the obtained virtual microstructures were calculated using a combination of three-dimensional digital image processing algorithms: 1) distance transform and 2) medial axis thinning algorithm to obtain a 3D skeleton of the pore structure. Transport properties of the simulated microstructures are analyzed employing a finite difference 3D transport model. The modeling results are compared with available literature results.

Fabrication and Characterization of Diatomite Functionalized Cellulose Acetate Nanofibers

2019 ◽  
Vol 6 (3) ◽  
pp. 28-36
Author(s):  
Çiğdem Akduman
Keyword(s):  
Pore Size ◽  
Cellulose Acetate ◽  
High Specific Surface Area ◽  
High Porosity ◽  
Size Distributions ◽  
Mean Flow ◽  
Water Contact ◽  
Pore Size Distributions ◽  
Nanofiber Membranes

Cellulose acetate (CA) nanofiber membranes incorporated with diatomite (DE) were prepared by electrospinning to produce electrospun nanofiber membranes with high specific surface area and high porosity with fine pores. When the DE percentage increased from 0 to 30%, the water contact angle (WCA) of the membranes increased from 86.21° to 118.44°, indicating that neat CA nanofibers were more hydrophilic than CA/DE nanofibers and had a better wetting tendency. CA, CA-10DE, and CA-20DE nanofiber membranes showed a mean flow pore size (MFP) of 2.941, 2.681, and 2.408 μm, respectively, with narrow pore size distributions. However, the CA-30DE nanofiber membrane showed a smaller MFP size of 0.5014 μm. CA nanofibers were produced in the range of 206.31 to 281.13 nm. The dye removal ability of these membranes was tested using an aqueous solution of C.I. Reactive Red 141.

scholarly journals Percolation properties of 3-D multiscale pore networks: how connectivity controls soil filtration processes

2010 ◽  
Vol 7 (2) ◽  
pp. 2997-3018 ◽  
Author(s):  
E. M. A. Perrier ◽  
N. R. A. Bird ◽  
T. B. Rieutord
Keyword(s):  
Pore Size ◽  
Scaling Laws ◽  
Fractal Dimensions ◽  
Natural Soil ◽  
Pore Networks ◽  
Multi Scale ◽  
Soil Ecosystems ◽  
Pore Size Distributions ◽  
Soil Structures ◽  
Soil Filtration

Abstract. Quantifying the connectivity of pore networks is a key issue not only for modelling fluid flow and solute transport in porous media but also for assessing the ability of soil ecosystems to filter bacteria, viruses and any type of living microorganisms as well inert particles which pose a contamination risk. Straining is the main mechanical component of filtration processes: it is due to size effects, when a given soil retains a conveyed entity larger than the pores through which it is attempting to pass. We postulate that the range of sizes of entities which can be trapped inside soils has to be associated with the large range of scales involved in natural soil structures and that information on the pore size distribution has to be complemented by information on a Critical Filtration Size (CFS) delimiting the transition between percolating and non percolating regimes in multiscale pore networks. We show that the mass fractal dimensions which are classically used in soil science to quantify scaling laws in observed pore size distributions can also be used to build 3-D multiscale models of pore networks exhibiting such a critical transition. We extend to the 3-D case a new theoretical approach recently developed to address the connectivity of 2-D fractal networks (Bird and Perrier, 2009). Theoretical arguments based on renormalisation functions provide insight into multi-scale connectivity and a first estimation of CFS. Numerical experiments on 3-D prefractal media confirm the qualitative theory. These results open the way towards a new methodology to estimate soil filtration efficiency from the construction of soil structural models to be calibrated on available multiscale data.

scholarly journals Multifractal Characterization of Pore Size Distributions of Peat Soil

2016 ◽  
Vol 48 (2) ◽  
pp. 106-114 ◽  
Author(s):  
Joko Sampurno ◽  
◽  
Azrul Azwar ◽  
Fourier Dzar Eljabbar Latief ◽  
Wahyu Srigutomo ◽  
...  
Keyword(s):  
Pore Size ◽  
Peat Soil ◽  
Size Distributions ◽  
Pore Size Distributions
Sign in / Sign up

Export Citation Format

Share Document