Multi-scale characterization of porosity in Boom Clay (HADES-level, Mol, Belgium) using a combination of X-ray μ-CT, 2D BIB-SEM and FIB-SEM tomography

Hemes, Susanne; Desbois, Guillaume; Urai, János L.; Schröppel, Birgit; Schwarz, Jens-Oliver

doi:10.1016/j.micromeso.2015.01.022

Cited by 209 publications

(92 citation statements)

References 80 publications

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“…Extrapolations of RVE lengths suggest that the relative error will decrease to < 10 % if the cube length of the investigated volume is in the hundreds of microns or if the number of realizations is increased. Hemes et al (2015) agree with Keller et al's (2013) findings and further conclude that FIB analyses alone are not capable of covering spatial inhomogeneities and that a combination of methods (FIB, BIB, µCT) should be favored to characterize 3-D porosities as suggested by . However, the approach of Kanit et al (2003) is typically used to downscale a given volume rather than to upscale from a smaller one.…”

Section: Introductionsupporting

confidence: 89%

“…Further they conclude that the connectivity depends on the porosity of the investigated vol-ume and that a local porosity between at least 6 and 10 % is needed to realize percolation paths along the bedding plane. These findings are supported by Hemes et al (2015) who found that at a total porosity of about 18 % almost 87 % the pore space contribute to the axis connectivity. In our work we observed that at porosities of about 2 % connected pore clusters only exist at the scale of a few µm.…”

Section: Porositysupporting

confidence: 69%

“…Several studies made an attempt to determine the size of representative volume elements (RVEs). Based on the statistical approach of Kanit et al (2003) the cube lengths of RVEs were determined for Opalinus clay (Keller et al, 2013) and for Boom Clay (Hemes et al, 2015). Keller et al (2013) have shown that the relative error for porosity is about 40-50 % if only one FIB volume of 10 3 µm 3 is investigated.…”

Section: Introductionmentioning

confidence: 99%

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Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

et al. 2016

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Abstract. The goal of this study is to better understand the porosity and permeability in shales to improve modelling fluid and gas flow related to shale diagenesis. Two samples (WIC and HAD) were investigated, both mid-Jurassic organic-rich Posidonia shales from Hils area, central Germany of different maturity (WIC R 0 0.53 % and HAD R 0 1.45 %). The method for image collection was focused ion beam (FIB) microscopy coupled with scanning electron microscopy (SEM). For image and data analysis Avizo and GeoDict was used. Porosity was calculated from segmented 3-D FIB based images and permeability was simulated by a Navier Stokes-Brinkman solver in the segmented images.Results show that the quantity and distribution of pore clusters and pores (≥ 40 nm) are similar. The largest pores are located within carbonates and clay minerals, whereas the smallest pores are within the matured organic matter. Orientation of the pores calculated as pore paths showed minor directional differences between the samples. Both samples have no continuous connectivity of pore clusters along the axes in the x, y, and z direction on the scale of 10 to 20 of micrometer, but do show connectivity on the micrometer scale. The volume of organic matter in the studied volume is representative of the total organic carbon (TOC) in the samples. Organic matter does show axis connectivity in the x, y, and z directions. With increasing maturity the porosity in organic matter increases from close to 0 to more than 5 %. These pores are small and in the large organic particles have little connection to the mineral matrix. Continuous pore size distributions are compared with mercury intrusion porosimetry (MIP) data. Differences between both methods are caused by resolution limits of the FIB-SEM and by the development of small pores during the maturation of the organic matter. Calculations show no permeability when only considering visible pores due to the lack of axis connectivity. Adding the organic matter with a background permeability of 1×10 −21 m 2 to the calculations, the total permeability increased by up to 1 order of magnitude for the low mature and decreases slightly for the overmature sample from the gas window. Anisotropy of permeability was observed. Permeability coefficients increase by 1 order of magnitude if simulations are performed parallel to the bedding. Our results compare well with experimental data from the literature suggesting that upscaling may be possible in the future as soon as maturity dependent organic matter permeability coefficients can be determined.

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Section: Introductionsupporting

confidence: 89%

Section: Porositysupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

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Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

et al. 2016

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“…The measured total porosity based on water content (by drying at 100ºC) is in a range of 36-39%. Standard bulk porosity measurements using mercury injection porosimetry on dried Boom clay samples provide interconnected porosity between 23 and 40% [7] [12]. Mercuryintrusion porosimetry tests which are performed on freeze-dried samples show that the PSD in Boom clay possesses one dominant value about 90nm [7], see Figure 1.…”

Section: D Model Generationmentioning

confidence: 99%

Numerical Prediction of Gas Breakthrough in Boom Clay

Zhang¹,

Jun-tong²,

Colliat³

et al. 2018

dtetr

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In Belgium, Boom clay has been studied as a potential host rock for storage of high-level radioactive waste. This work aims at the numerical prediction of gas migration properties in the very low-porosity formation of Boom clay. Considering the meso/microscopic scale of pore network, the analyses based on macroscopic approaches or homogeneous transport properties are no longer appropriate. In this study, the 3D pore space morphological model of Boom clay which possesses a similar pore size distribution (PSD) with experimental results is generated through the union of excursions of Gaussian random fields. Essentially, the extraction of accessible pores for a given gas pressure is feasible via the purely geometric analysis of morpho-mathematical operations. Then this work numerically predicts the capillary induced gas entry and gas breakthrough pressures (GEP and GBP) in Boom clay.

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“…By using these imaging methods, it is possible to receive a solid idea of a shale's internal (micro) structure and pore geometry (e.g., [6][7][8][9][10][11]). BIB milling in combination with SEM imaging delivers direct information about pore sizes, their morphology and spatial distribution, rock microstructure, and potential anisotropy as well as core damage due to sample handling (e.g., [3,[12][13][14][15][16][17][18][19][20][21][22][23][24][25]). Additionally, in combination with energy dispersive X-ray spectroscopy (EDX), BIB-SEM enables the identification of individual grains [26,27].…”

Section: Introductionmentioning

confidence: 99%

Using BIB-SEM Imaging for Permeability Prediction in Heterogeneous Shales

et al. 2017

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Organic-rich shale samples from a lacustrine sedimentary sequence of the Newark Basin (New Jersey, USA) are investigated by combining Broad Ion Beam polishing with Scanning Electron Microscopy (BIB-SEM). We model permeability from this 2D data and compare our results with measured petrophysical properties. Three samples with total organic carbon (TOC) contents ranging from 0.7% to 2.9% and permeabilities ranging from 4 to 160 nD are selected. Pore space is imaged at high resolution (at 20,000x magnification) and segmented from representative BIB-SEM maps. Modeled permeabilities, derived using the capillary tube model (CTM) on segmented pores, range from 2.3 nD to 310 nD and are relatively close to measured intrinsic permeabilities. SEM-visible porosities range from 0.1% to 1.8% increasing with TOC, in agreement with our measurements. The CTM predicts permeability correctly within one order of magnitude. The results of this work demonstrate the potential of 2D BIB-SEM for calculating transport properties of heterogeneous shales.

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Multi-scale characterization of porosity in Boom Clay (HADES-level, Mol, Belgium) using a combination of X-ray μ-CT, 2D BIB-SEM and FIB-SEM tomography

Cited by 209 publications

References 80 publications

Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

Numerical Prediction of Gas Breakthrough in Boom Clay

Using BIB-SEM Imaging for Permeability Prediction in Heterogeneous Shales

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