Investigation of pore size distributions of coals with different structures by nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP)

Li, Xiangchen; Kang, Yili; Haghighi, Manouchehr

doi:10.1016/j.measurement.2017.10.059

Cited by 133 publications

(47 citation statements)

References 26 publications

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“…Most of these are scattered with poor connectivity. Mineral‐associated pores are defined as the pores associated with minerals (both crystalline minerals and amorphous inorganic components), including corrosion pores, mold pores, intercrystalline pores, etc . In high‐rank coals, mineral pores are quite irregular both in size and morphology, and generally show angular edges due to deformation force (Figure B).…”

Section: Resultsmentioning

confidence: 99%

“…Mineral-associated pores are defined as the pores associated with minerals (both crystalline minerals and amorphous inorganic components), including corrosion pores, mold pores, intercrystalline pores, etc. [40][41][42] In high-rank coals, mineral pores are quite irregular both in size and morphology, and generally show angular edges due to deformation force ( Figure 6B). The direction of the elongated pores is primarily consistent with the overall orientation of the mineral grains.…”

Section: Observation and Statistics With Fesemmentioning

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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Section: Resultsmentioning

confidence: 99%

Section: Observation and Statistics With Fesemmentioning

confidence: 99%

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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“…NMR has been applied successfully to the analysis of conventional oil and gas reservoirs, such as clastic rock, carbonate rock, and volcanic rock. In recent years, NMR has received growing attention in the field of CBM reservoir characterization and considerable achievements have been made involving pore types identification, permeability prediction, and reservoir evaluation (Cai et al, 2013;Zhang et al, 2018;Li et al, 2018;Liu and Wang, 2018). NMR measurements obtain two transverse relaxation time (T 2 ) spectra: one in the irreducible water state and another in the saturated water state.…”

Section: Introductionmentioning

confidence: 99%

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

Guo

Qin

et al. 2020

Acta Geologica Sinica (Eng)

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The methods of nuclear magnetic resonance (NMR) spectroscopy, mercury injection porosimetry (MIP), and gas -water relative permeability (GWRP) were used to reveal the pore structure and permeability characteristics of high-rank coal reservoirs in the Bide-Santang basin, western Guizhou, South China, to provide guidance for coalbed methane (CBM) exploration and exploitation and obtain direct insights for the development of CBM wells. The results indicate that the coal reservoirs in the study area are characterized by well-developed adsorption pores and poorly developed seepage pores. The bimodal NMR transverse relaxation time (T 2 ) spectra and the mutation in the fractal characteristic of the MIP pore volume indicate poor connectivity between the adsorption pores and the seepage pores. As a result, the effective porosity is relatively low, with an average of 1.70%. The irreducible water saturation of the coal reservoir is relatively high, with an average of 66%, leading to a low gas relative permeability under irreducible water saturation. This is the main reason for the low recovery of high-rank CBM reservoirs, and effective enhanced CBM recovery technology urgently is needed. As a nondestructive and less time-consuming technique, the NMR is a promising method to quantitatively characterize the pores and fractures of coals.

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“…22,23 The mercury intrusion porosimetry (MIP) is also extensively used to characterize the pore characteristics of porous media, such as PV, PSD, and PSSA. [24][25][26][27] It is worth noting that although these methods have excellent observation on meso and micro structure, there are still some differences in their application due to respective precision and scope. By X-ray CT, 3-D scanning can be realized, and the density or structure change within samples can be determined.…”

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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Investigation of pore size distributions of coals with different structures by nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP)

Cited by 133 publications

References 26 publications

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

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

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

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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Investigation of pore size distributions of coals with different structures by nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP)

Cited by 133 publications

References 26 publications

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

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

Pore Structure and Permeability Characterization of High‐rank Coal Reservoirs: A Case of the Bide‐Santang Basin, Western Guizhou, South China

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

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