Modeling of Bulk Kerogen Porosity: Methods for Control and Characterization

Vasileiadis, Manolis; Peristeras, Loukas D.; Papavasileiou, Konstantinos D.; Economou, Ioannis G.

doi:10.1021/acs.energyfuels.7b00626

Cited by 49 publications

(81 citation statements)

References 76 publications

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“…The difference between the PV1-TOC and PV2-TOC covariance (Figure 12a) was consistent with those described by Wang et al [66]. Some researchers have found that mesopores consisted of elliptical organic matter pores as well, as there were quite a few inorganic matter pores with various morphologies based on FE-SEM [71][72][73][74]. It is well documented that considerable micropores are formed within the macromolecular structure of organic matter [75].…”

Section: Pore Structure Parameters and Their Controlling Factorssupporting

confidence: 88%

“…Energies 2020, 13, x FOR PEER REVIEW 14 of 22 [83], so the microporous structure, related to the macromolecular structure of organic matter, may not become complicated as the organic matter content increases. The multifractal parameters for q > 0 corresponded to the dominance of a large concentration of the pore volume, and the parameters for q < 0 could be mainly affected by a small concentration of the pore volume [53,60,74]. As mentioned above, the PSDs of mesopores were unimodal.…”

Section: Multifractal Characteristics Of Micropores and Mesoporesmentioning

confidence: 74%

“…It is hypothesized that due to the multimodal distribution of the PSD in the micropores, the correlation between the singularity and the heterogeneity was weakened compared with the mesopores. Therefore, we can divide the multifractal parameters into the parameters of heterogeneity (D−10-D10, D0-D10 and D−10-D0) and the parameters of singularity (D1 and The multifractal parameters for q > 0 corresponded to the dominance of a large concentration of the pore volume, and the parameters for q < 0 could be mainly affected by a small concentration of the pore volume [53,60,74]. As mentioned above, the PSDs of mesopores were unimodal.…”

Section: Multifractal Characteristics Of Micropores and Mesoporesmentioning

confidence: 99%

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Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

2020

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To better understand the variability and heterogeneity of pore size distributions (PSDs) in the Longmaxi Shale, twelve shale samples were collected from the Xiaoxi and Fendong section, Sichuan Province, South China. Multifractal analysis was employed to study PSDs of mesopores (2–50 nm) and micropores (<2 nm) based on low-pressure N2/CO2 adsorption (LP-N2/CO2GA). The results show that the PSDs of mesopores and micropores exhibit a multifractal behavior. The multifractal parameters can be divided into the parameters of heterogeneity (D−10–D10, D0–D10 and D−10–D0) and the parameters of singularity (D1 and H). For both the mesopores and micropores, decreasing the singularity of the pore size distribution contributes to larger heterogeneous parameters. However, micropores and mesopores also vary widely in terms of the pore heterogeneity and its controlling factors. Shale with a higher total organic carbon (TOC) content may have a larger volume of micropores and more heterogeneous mesopores. Rough surface and less concentrated pore size distribution hinder the transport of adsorbent in mesopores. The transport properties of micropores are not affected by the pore fractal dimension.

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Section: Pore Structure Parameters and Their Controlling Factorssupporting

confidence: 88%

Section: Multifractal Characteristics Of Micropores and Mesoporesmentioning

confidence: 74%

Section: Multifractal Characteristics Of Micropores and Mesoporesmentioning

confidence: 99%

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Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

2020

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“…Various techniques were used to characterize pore systems of shale reservoirs, such as high pressure mercury injection, low pressure N 2 adsorption, CO 2 adsorption, and scanning electron microscopy (SEM). 10,[20][21][22] From these techniques, low pressure N 2 adsorption and SEM have been accepted as the most effective techniques for characterizing pore structures in shale. 13,21,23,24 It is widely accepted that pore volume and surface area are mainly affected by nanoscale pores, and most of these nanoscale pores lie in the range of low pressure N 2 adsorption scale.…”

Section: Introductionmentioning

confidence: 99%

Fractal Characteristics of Nanoscale Pores in Shale and Its Implications on Methane Adsorption Capacity

et al. 2019

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Pore structure in shale controls the gas storage mechanism and gas transport behaviors. Since nanoscale pores in shale matrix have fractal characteristics, fractal theory can be used to study its structure. In addition, fractal method has its own advantages to investigate nanopores in shale, especially for the heterogeneity and irregularity of nanopores in shale. In this work, fractal features of nanoscale pores and the implication on methane adsorption capacity of shale were investigated by employing low pressure nitrogen adsorption, scanning electron microscopy (SEM), and methane adsorption experiments. Frenkel–Halsey–Hill (FHH) model was also used to calculate the fractal parameters of nanoscale pores in shale. The results showed that nanoscale pores in 12 shale samples have obvious fractal features. All the fractal curves of these shale samples can be divided into two segments, which are cut off by [Formula: see text], and the fractal dimensions of these two segments vary from 2.48 to 2.92 [Formula: see text] and 2.42 to 2.80 [Formula: see text], respectively. Based on SEM images, it is found that self-similarity of organic pore systems in shales refers to two aspects. One is that relatively large-scale and small-scale pores have similar formation properties and types, which are of elliptical shape with rough surface. The other is that some small-scale pores are formed by rough surface of relatively large pores. The results also demonstrate that methane adsorption capacity of shale samples increase with increasing total organic carbon (TOC) contents. This is mainly because organic matter is rich in pores and has relatively large fractal dimension values. Larger fractal dimensions indicate rougher pore surfaces and could form more small-scale organic pores. These organic pores would provide more space for methane adsorption.

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“…The nanoscale organic pores, which contribute to the largest part of the total pore volume, are the main storage space for shale gas (Wang Min et al, 2016). Meanwhile, it is well documented that some nanoscale organic pores (<2 nm) are formed within the three-dimensional (3D) molecular structure, and their pore structure parameters are controlled by the molecular composition and spatial structure of the organic matter (Bousige et al, 2016;Huang et al, 2017;Vasileiadis et al, 2017;Liu et al, 2018a). Therefore, the evaluation of gas storage and transport is strengthened by a robust understanding of the molecular structure of the organic matter.…”

mentioning

confidence: 99%

Molecular Structure of Kerogen in the Longmaxi Shale: Insights from Solid State NMR, FT‐IR, XRD and HRTEM

Wang

Zhu

Liu

et al. 2019

Acta Geologica Sinica (Eng)

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Kerogen plays an important role in shale gas adsorption, desorption and diffusion. Therefore, it is necessary to characterize the molecular structure of kerogen. In this study, four kerogen samples were isolated from the organic-rich shale of the Longmaxi Formation. Raman spectroscopy was used to determine the maturity of these kerogen samples. Highresolution transmission electron microscopy (HRTEM), 13 C nuclear magnetic resonance ( 13 C NMR) , X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were conducted to characterize the molecular structure of the shale samples. The results demonstrate that VR eqv of these kerogen samples vary from 2.3% to 2.8%, suggesting that all the kerogen samples are in the dry gas window. The macromolecular carbon skeleton of the Longmaxi Formation kerogen is mainly aromatic (f a '=0.56). In addition, the aromatic structural units are mainly composed of naphthalene (23%), anthracene (23%) and phenanthrene (29%). However, the aliphatic structure of the kerogen macromolecules is relatively low (f al * +f al H =0.08), which is presumed to be distributed in the form of methyl and short aliphatic chains at the edge of the aromatic units. The oxygen-containing functional groups in the macromolecules are mainly present in the form of carbonyl groups (f a c =0.23) and hydroxyl groups or ether groups (f al O =0.13). The crystallite structural parameters of kerogen, including the stacking height (L c =22.84 Å), average lateral size (L a =29.29 Å) and interlayer spacing (d 002 =3.43 Å), are close to the aromatic structural parameters of anthracite or overmature kerogen. High-resolution transmission electron microscopy reveals that the aromatic structure is well oriented, and more than 65% of the diffractive aromatic layers are concentrated in the main direction. Due to the continuous deep burial, the longer aliphatic chains and oxygen-containing functional groups in the kerogen are substantially depleted. However, the ductility and stacking degree of the aromatic structure increases during thermal evolution. This study provides quantitative information on the molecular structure of kerogen samples based on multiple research methods, which may contribute to an improved understanding of the organic pores in black shale.

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Modeling of Bulk Kerogen Porosity: Methods for Control and Characterization

Cited by 49 publications

References 76 publications

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

Fractal Characteristics of Micro- and Mesopores in the Longmaxi Shale

Fractal Characteristics of Nanoscale Pores in Shale and Its Implications on Methane Adsorption Capacity

Molecular Structure of Kerogen in the Longmaxi Shale: Insights from Solid State NMR, FT‐IR, XRD and HRTEM

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