On the use and abuse of N2 physisorption for the characterization of the pore
            structure of shales

Bertier, Pieter; Pipich, Vitaliy; Clarkson, Christopher R.; Ghanizadeh, Amin; Busch, Andreas; Stanjek, Helge; Schweinar, Kevin; Amann-Hildenbrand, Alexandra; Kampman, Niko; Prinz, Dirk; Krooß, Bernhard M.

doi:10.1346/cms-wls-21.12

Cited by 82 publications

(48 citation statements)

References 20 publications

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“…Pore size distribution may be represented by the cumulative pore volume, incremental pore volume, differential pore volume, and surface area versus pore diameter, from which, information on pore size range, dominant pore size, and pore size distribution peak can be obtained . As demonstrated by previous studies, for example, Groen et al, the adsorption branch is highly preferred for the calculation of pore size distribution and can be hardly affected by the tensile strength effect . Therefore, in the present study, the BJH method and the adsorption branch of nitrogen adsorption/desorption isotherms were utilized to investigate pore size distributions within the Yanchang Formation Chang 7 Member shale samples of southwestern Ordos Basin.…”

Section: Resultsmentioning

confidence: 97%

Nanoscale pore structure and fractal characteristics of the continental Yanchang Formation Chang 7 shale in the southwestern Ordos Basin, central China

You

Chen

et al. 2019

Energy Science & Engineering

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Shales from the Yanchang Formation Chang 7 Member in the Ordos Basin are among the most important shale reservoirs in China and have been investigated due to their great potential. Knowledge of pore structure is important for understanding the storage capacity and flow mechanism in shale reservoirs. In this study, eight shale samples were collected from the Yanchang Formation Chang 7 Member in the southwestern Ordos Basin, and their geochemistry, mineral compositions, pore structure, and fractal characteristics were investigated based on X‐ray diffraction (XRD) analysis, total organic carbon (TOC) analysis, low‐pressure adsorption/desorption analysis, thermal maturity analysis, and fractal analysis. The results indicated that the TOC content ranged between 0.48% and 2.37%, and the Ro values varied from 0.826% to 1.217%. The major mineral compositions were quartz and clay minerals. Nitrogen adsorption/desorption analysis indicated that the isotherms were similar for all collected shale samples from the Chang 7 Member and resembled the type IV isotherm. Narrow slit‐like pore was the dominant pore type, and the pore size distribution appeared to be unimodal with its peak mainly around 40 nm. Investigation of factors for pore structures showed that the TOC content was the controlling factor for the Chang 7 shales. The Frenkel‐Halsey‐Hill (FHH) method was applied to determine fractal dimensions, which were calculated as the D1 (relative pressure >0.96), D2 (0.96 >relative pressure >0.45), and D3 (0.45 >relative pressure) values, ranging in the intervals of 2.788~2.854, 2.547~2.688, and 2.410~2.567, respectively. The relatively high fractal dimensions indicated that pore structures were complicated, and the higher D1 values suggested that pores with larger sizes showed a rougher pore surface and more complex pore structure. Fractal dimensions showed positive correlations with the contents of TOC and clay minerals, and a negative relationship with the quartz contents.

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Section: Resultsmentioning

confidence: 97%

Nanoscale pore structure and fractal characteristics of the continental Yanchang Formation Chang 7 shale in the southwestern Ordos Basin, central China

You

Chen

et al. 2019

Energy Science & Engineering

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“…One of the major uncertainties of the LPNP method is the influence of sample crushing. Primary structure and fabric will change at the microscopic level, which inevitably changes the surface properties of samples and may alter the original pore structure or generate new pore space 89 – 91 . During a crushing process, compression and shear forces acting on the samples also generate smaller fragments and induce fracture propagation as well 92 .…”

Section: Discussionmentioning

confidence: 99%

Integrating SANS and fluid-invasion methods to characterize pore structure of typical American shale oil reservoirs

Zhao

Jin

et al. 2017

Sci Rep

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An integration of small-angle neutron scattering (SANS), low-pressure N 2 physisorption (LPNP), and mercury injection capillary pressure (MICP) methods was employed to study the pore structure of four oil shale samples from leading Niobrara, Wolfcamp, Bakken, and Utica Formations in USA. Porosity values obtained from SANS are higher than those from two fluid-invasion methods, due to the ability of neutrons to probe pore spaces inaccessible to N 2 and mercury. However, SANS and LPNP methods exhibit a similar pore-size distribution, and both methods (in measuring total pore volume) show different results of porosity and pore-size distribution obtained from the MICP method (quantifying pore throats). Multi-scale (five pore-diameter intervals) inaccessible porosity to N 2 was determined using SANS and LPNP data. Overall, a large value of inaccessible porosity occurs at pore diameters <10 nm, which we attribute to low connectivity of organic matter-hosted and clay-associated pores in these shales. While each method probes a unique aspect of complex pore structure of shale, the discrepancy between pore structure results from different methods is explained with respect to their difference in measurable ranges of pore diameter, pore space, pore type, sample size and associated pore connectivity, as well as theoretical base and interpretation.

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“…Adsorption and desorption were analysed at relative pressure points in the range of 0.001-0.995 and 0.995-0.1, respectively. Among the parameters calculated from the N2 adsorption analysis, Brunauer-Emmett-Teller (BET) SSA and Barrett-Joyner-Halenda (BJH) cumulative pore area/volume and pore size distribution (2-100 nm in diameter) were calculated in this study (Bertier et al, 2016).…”

Section: Samples and Methodsmentioning

confidence: 99%

Microstructural Investigation of Mudrock Seals Using Nanometer-Scale Resolution Techniques

Rezaeyan¹,

Pipich²,

Bertier

et al. 2019

Sixth EAGE Shale Workshop

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Small angle neutron scattering (SANS) and nitrogen low-pressure adsorption (LPS) have been used to characterise the pore structure of two organic lean mudrocks, Opalinus Clay, Mont Terri, Switzerland and Carmel Claystone, Utah. This was done in order to obtain a better understanding of H2 and CO2 transport, reaction and sorption related to radioactive waste disposal and carbon storage, respectively. The pore structure information derived by SANS and LPS are comparable and the results have revealed a vast heterogeneity from 2 nm to 2 µm, which can be related to the high clay contents. Due to the high clay contents, pores smaller than 10 nm constitute a large fraction of total porosity (25-30 %) and most of specific surface area (up to 80 %) in the sample mudrocks. Accordingly, these interplays contribute to a pore network of few-to-several nano-Darcy permeability in which pore size dependent transport mechanisms can vary from high sorptive diffusional fluid flow in small pores to low sorptive slip flow regime at progressively larger pores.

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On the use and abuse of N2 physisorption for the characterization of the pore structure of shales

Cited by 82 publications

References 20 publications

Nanoscale pore structure and fractal characteristics of the continental Yanchang Formation Chang 7 shale in the southwestern Ordos Basin, central China

Nanoscale pore structure and fractal characteristics of the continental Yanchang Formation Chang 7 shale in the southwestern Ordos Basin, central China

Integrating SANS and fluid-invasion methods to characterize pore structure of typical American shale oil reservoirs

Microstructural Investigation of Mudrock Seals Using Nanometer-Scale Resolution Techniques

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