Pore structure characterization of coal by NMR cryoporometry

Zhao, Yixin; Sun, Yingfeng; Liu, Shimin; Wang, Kai; Jiang, Yaodong

doi:10.1016/j.fuel.2016.10.121

Cited by 222 publications

(108 citation statements)

References 49 publications

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“…Furthermore, Stratigraphic Modified Lorenz Plot (SMLP) uses HFUs zonations in single well vertically (Ge et al, 2015;Zhao et al, 2017), in which the cumulative flow capacity (Kh) and the cumulative storage capacity (Kφ) are plotted. Inflection points in SMLP plot indicates changes in flow characteristics, hence the segment points of HFUs.…”

Section: Pore Type and Hfusmentioning

confidence: 99%

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Chen

Zhou

2017

Adv. Geo-Energ. Res.

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Conventional petrophysical characterizations are often based on direct laboratory measurements. Although they provide accurate results, such measurements are time-consuming and limited by instrument and environment. What's more, in the georesource energy industry, availability and cuttings of core plugs are difficult. Because of these reasons, virtual digital core technology is of increasing interest due to its capability of characterizing rock samples without physical cores and experiments. Virtual digital core technology, also known as digital rock physics, is used to discover, understand and model relationships between material, fluid composition, rock microstructure and macro equivalent physical properties. Based on actual geological conditions, modern mathematical methods and imaging technology, the digital model of the core or porous media is created to carry out physical field numerical simulation. In this review, the methods for constructing digital porous media are introduced first, then the characterization of thin rock cross section and the capillary pressure curve using scanning electron microscope image under mixed wetting are presented. Finally, we summarize the hydraulic flow unit methods in petrophysical classification.Keywords: Digital core, porous media, petrophysical characterization, thin section, mercury injection capillary pressure.Citation: Chen, X., Zhou, Y. Applications of digital core analysis and hydraulic flow units in petrophysical characterization. Adv.

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Section: Pore Type and Hfusmentioning

confidence: 99%

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Chen

Zhou

2017

Adv. Geo-Energ. Res.

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“…(2) Fluid intrusion: three additional categories are used for the detection of pore size scope: (1) The first kind of methods mainly focuses on the adsorption pores with a small diameter. As the decisive role of nanoscale pores in the adsorption capacity, many new methods have been applied to coals, such as low‐temperature nitrogen and carbon dioxide (CO 2 ) adsorption, small angle X‐ray scattering (SAXS), small angle neutron scattering (SANS), and nuclear magnetic resonance cryoporometry (NMRC) . A CO 2 adsorption test can detect the pore structures with diameter <1 nm due to the small diameter (0.33 nm), strong adsorption potential and activated diffusion of the CO 2 molecule, which is not possible with other methods.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the specific surface area and pore volume from CO 2 adsorption is higher than those from low‐temperature nitrogen adsorption . The PSD measured by NMRC ranges from 1 to 500 nm, and the accuracy of the results is higher than that of low‐temperature nitrogen adsorption, especially for micropores . (2) The major research section is seepage pore and fracture, such as mercury intrusion porosimetry (MIP).…”

Section: Introductionmentioning

confidence: 99%

“…18 The PSD measured by NMRC ranges from 1 to 500 nm, and the accuracy of the results is higher than that of low-temperature nitrogen adsorption, especially for micropores. 21,22 (2) The major research section is seepage pore and fracture, such as mercury intrusion porosimetry (MIP). Since the pores in CBM reservoirs have strong compressibility, 23 the results of adsorption pores obtained by this means are usually inaccurate.…”

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confidence: 99%

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Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques

Liu

Cai

Zhou

2019

Energy Science & Engineering

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To evaluate the impacts of nanopores of high‐rank coals on coalbed methane adsorption and storage, 12 anthracite and semianthracite coal samples from Yangquan and Shouyang blocks in the Qinshui Basin were investigated. Field emission scanning electron microscopy (FESEM) and CO2 adsorption combined with nuclear magnetic resonance cryoporometry (NMRC) experiments were used to evaluate the pore structure with diameters ranging from 0 to 500 nm and their impact on adsorption capacity based on qualitative and quantitative analysis. The results show that a coalification jump from semianthracite to anthracite occurred in the study area due to the magmatic intrusion. In the process, the volume of supermicropores and micropores largely increased while the volume of transition pores and mesopores decreased slightly. Additionally, vitrinite gets purified and enriched during the rapid maturation of coal reservoir, which is beneficial to the microporous structure development. The pore size distribution (PSD) of anthracite is mainly divided into two types, which are in serrated and decreasing forms, respectively. Higher vitrinite content can promote the formation of decreasing type (type II), which corresponds to a lower degree of complexity. The fractal dimensions indicate that the heterogeneity of coal samples is increasing with the decrease in pore size. Accordingly, the increase in pore heterogeneity corresponds to the lower adsorption capacity. The main pore sizes that contribute to CBM adsorption include two parts: 25‐30 nm and 50‐60 nm. For the supermicropores with large specific surface areas, the pore system detected by CO2 molecules is not conducive to CBM adsorption, while the increase in pore volume can improve the adsorption rate and capacity of CO2. These findings are vital for a precisely understanding of nanoscale pores as well as future CBM exploitation.

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“…1 The heterogeneity of pores and fractures ranging from nm to mm scale has significant impact on the CBM storage and mass transport. 2 Previous studies on coal structure mainly concentrate on characteristics of pore structure, such as pore volume (PV), pore specific surface area (PSSA), pore size distribution (PSD), fractal dimension and so on, [3][4][5][6][7] few of the studies have attempted to characterize the entire coal structure with coal matrix, clay minerals and pore distribution all taken into consideration. As pores have larger gas storage capacity than coal matrix and clay minerals, 8,9 so the maceral compositions and the non-homogeneously distributed pores both affect the inhomogeneous methane adsorption and result in regional CBM enrichment.…”

Section: Introductionmentioning

confidence: 99%

Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP)

2018

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It is of great benefit to study the material and structural heterogeneity of coal for better understanding the coalbed methane (CBM) storage and enrichment. In this paper, multi-scale X-ray computed tomography (CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP) at multi scales were conducted to thoroughly study the material distribution, heterogeneity, pore development, porosity and permeability of coal. It is suitable and reasonable to divide the testing samples into three structural categories by average density and heterogeneity degree, and the meso structure in the three categories accords with the morphology on SEM images. The pore size distribution and pore development of each subsample cannot be correspondingly related to their respective structure category or morphology due to different observation scales, while the macro pore size development, accumulated macro pore volume and macro pores porosity accord with the meso structure category and morphology information by CT and SEM at the same scale very well. Given the effect of macro pores on permeability and the contribution of micro pores to CBM storage capacity, reservoirs with developed micro pores and macro pores may be the most suitable coal reservoir for CBM exploitation.

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Pore structure characterization of coal by NMR cryoporometry

Cited by 222 publications

References 49 publications

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques

Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP)

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Pore structure characterization of coal by NMR cryoporometry

Cited by 222 publications

References 49 publications

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Applications of digital core analysis and hydraulic flow units in petrophysical characterization

Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO2 adsorption, and NMRC techniques

Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP)

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Methane adsorption constrained by pore structure in high‐rank coals using FESEM, CO₂ adsorption, and NMRC techniques