Characterizing mechanical heterogeneity of coal at nano-to-micro scale using combined nanoindentation and FESEM-EDS

Liu, Ang; Liu, Shimin; Liu, Yiwei; Liu, Bangzhi; Liu, Ting

doi:10.1016/j.coal.2022.104081

Cited by 17 publications

(7 citation statements)

References 47 publications

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“…Qualitative methods include optical microscope (OM), casting thin section (CTS) [19], field emission scanning electron microscopy (FESEM) [2,16,[20][21][22][23][24], transmission electron microscope (TEM) [25][26][27][28][29], focused ion beam scanning electron microscopy (FIBSEM) [30][31][32][33][34][35][36][37], focused ion beam helium ion microscope (FIBHIM) [38,39], atomic force microscope (AFM) [40][41][42][43][44][45][46], X-ray computed tomography (X-CT) [12,[47][48][49][50][51][52][53][54]; the quantitative methods can be divided into mercury injection capillary pressure (MICP) [5,[55][56][57], constant-rate mercury injection (CRMI) [58][59][60][61], nuclear magnetic resonanc...…”

Section: Methods For Reservoir Characterizationmentioning

confidence: 99%

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Guan,

Cai,

et al. 2024

JMSE

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The complex pore structure of unconventional oil and gas reservoirs is one of the reasons for the difficulties in resource evaluation and development. Therefore, it is crucial to comprehensively characterize the pore structure, understand reservoir heterogeneity from multiple perspectives, and gain an in-depth understanding of fluid migration and accumulation mechanisms. This review outlines the methods and basic principles for characterizing microporous systems in unconventional reservoirs, summarizes the fractal analysis corresponding to the different methods, sorts out the relationship between the fractals and reservoir macroscopic physical properties (porosity, permeability, etc.) with the reservoir microscopic pore structures (pore structure parameters, pore connectivity, etc.). The research focuses on cutting-edge applications of characterization techniques, such as improved characterization accuracy, calibration of PSD ranges, and identification of different hydrogen compositions in pore systems for dynamic assessment of unconventional reservoirs. Fractal dimension analysis can effectively identify the quality level of the reservoir; complex pore-throat structures reduce permeability and destroy free fluid storage space, and the saturation of removable fluids is negatively correlated with Df. As for the mineral composition, the fractal dimension is positively correlated with quartz, negatively correlated with feldspar, and weakly correlated with clay mineral content. In future qualitative characterization studies, the application and combination of contrast agents, molecular dynamics simulations, artificial intelligence techniques, and 4D imaging techniques can effectively improve the spatial resolution of the images and explore the adsorption/desorption of gases within the pores, and also help to reduce the computational cost of these processes; these could also attempt to link reservoir characterization to research on supercritical carbon dioxide-enhanced integrated shale gas recovery, carbon geological sequestration, and advanced underground hydrogen storage.

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Section: Methods For Reservoir Characterizationmentioning

confidence: 99%

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Guan,

Cai,

et al. 2024

JMSE

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“…In combination with Figure c, the loading and unloading process can be converted into energy changes. The total energy U t during the nanoindentation test satisfies the following relationship with U c , U p , and U e : U normalt = U normalc + U normalp + U normale U normalp + U normale = prefix∫ 0 h max P ⁡ d h U normalt = P max ( h max + h k ) 2 The sample fracture toughness K c can be computed using U c , A m , and E r K normalc = U normalc A normalm E normalr …”

Section: Nanoindentation Test Principle and Experimental Samplesmentioning

confidence: 99%

Section: Nanoindentation Test Principle and Experimental Samplesmentioning

confidence: 99%

“…These characteristics determine the range of coal fracturing and permeability enhancement as well as gas extraction efficiency. They also significantly impact the occurrence and evolution of gas dynamic disasters . Additionally, the migration and storage of gas also influence the micromechanical properties of coal seams. , Hence, investigating the coal micromechanical characteristics across various ranks holds paramount importance for ensuring the safe exploitation of coal resources and the prevention and control of gas dynamic disasters.…”

Section: Introductionmentioning

confidence: 99%

“…Meng et al , studied the micromechanical properties of coal at different coal ranks using nanoindentation experimental methods and molecular dynamics simulation and explored the changes in micromechanical properties during cyclic loading. Using nanoindentation technology along with X-ray diffraction (XRD) and field emission scanning electron microscopy energy-dispersive spectroscopy (FESEM-EDS), Liu et al delved into the coal micromechanical properties and established correlations with both the coal composition and microstructure. Liu et al revealed the impact of organic macerals in low-rank coal on the mechanical properties and rheological behavior of coal using nanoindentation methods.…”

Section: Introductionmentioning

confidence: 99%

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Micromechanical Properties of Different Rank Coal and Their Impact on Fracture Compressibility

Zhao,

Liu,

Lin

2024

Energy Fuels

Self Cite

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The micromechanical properties are crucial factors influencing coal fracturing and efficient gas extraction. This paper employs nanoindentation techniques to investigate coal micromechanical properties across various ranks, analyzing their impact on fracture compressibility. The results indicate significant variations in the distribution of micromechanical parameters of lignite, exhibiting the strongest heterogeneity. Average contact depth and creep displacement follow the order lignite > bituminous coal > anthracite. In terms of average hardness, reduced modulus, and fracture toughness, the ranking is anthracite > bituminous coal > lignite. Guhanshan Mine (GHS) anthracite demonstrates the highest values, exceeding Simengou Mine (SMG) lignite by factors of 2.73, 1.82, and 1.83, respectively. Both hardness and fracture toughness show a significant linear relationship with the elastic modulus. The average fracture compressibility coefficients for Daliuta Mine (DLT), Pingdingshan Mine (PDS), Jiaozishan Mine (JZS), and GHS are 0.144, 0.098, 0.09, and 0.08 MPa–1, respectively. Coal with greater micromechanical strength demonstrates enhanced resistance to compressive deformation fractures. This indicates that higher fracture toughness not only resists fracture propagation but also effectively withstands compressive deformation. Quantitative relationship models between the fracture compressibility coefficient and contact depth, hardness, reduced modulus, and fracture toughness are obtained through fitting analysis. These models facilitate the calculation of coal fracture compressibility coefficients under varying micromechanical strengths. The research findings offer theoretical guidance for optimizing coal seam fracturing and enhancing permeability schemes.

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Quantifying and Controller Determination of Shale Matrix Compressibility: Implications for Pore Structure and Gas Flow Behavior Analyses

et al. 2023

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Characterizing mechanical heterogeneity of coal at nano-to-micro scale using combined nanoindentation and FESEM-EDS

Cited by 17 publications

References 47 publications

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Micromechanical Properties of Different Rank Coal and Their Impact on Fracture Compressibility

Quantifying and Controller Determination of Shale Matrix Compressibility: Implications for Pore Structure and Gas Flow Behavior Analyses

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