Abstract
To study the effect of uniaxial compression on coal nanostructure during uniaxial compression, in situ synchrotron radiation small angle X-ray scattering experiments were carried out on four coals with different ranks under uniaxial compression. According to the scattering data during the uniaxial compression process, the fractal characteristics and the variation feature of fractal dimension with stress were obtained. Four coals with different ranks all possess two fractal characteristics: pore fractal occur in the smaller pore range (7–17 nm) in the high q value range, and surface fractal occur in the larger pore range (17–52 nm) in the low q value range. For two low rank coals, with increasing stress, the pore fractal dimension DP decreased and the surface fractal dimension DS increased, respectively; the variation trends of DP and DS were obvious. This indicates that with increasing stress, the heterogeneity and complexity of the pores decrease, the surface roughness of the pores increases, and stress has a significant effect on the nanopore structure. The smaller pores are more susceptible to stress, and the influence range of stress on low rank coals is larger than that on high rank coals. The change rate of fractal dimension (RD) has a poor relationship with compressibility during uniaxial loading and is related to coal rank. The RD per unit stress for high rank coals is larger than that for low rank coals. Nanostructure response to uniaxial compressive stress is more significant in low rank coals than in high rank coals. Compared with low rank coals, high rank coals have strong aromatization and molecular structure, and the nanostructures are less susceptible to failure under uniaxial stress.
Issue Section:
Technical Papers
References
1.
Cai
Y.
, Liu
D.
, Pan
Z.
, Yao
Y.
, Li
J.
, and Qiu
Y.
, “Pore Structure of Selected Chinese Coals with Heating and Pressurization Treatments
,” Science China Earth Sciences
57
, no. 7
(July 2014
): 1564
–1582
, https://doi.org/10.1007/s11430-014-4855-y2.
Liang
W.-G.
, Zhang
B.-N.
, Han
J.-J.
, and Wu
D.
, “Experimental Study on Coal Bed Methane Displacement and Recovery by Super Critical Carbon Dioxide Injection
,” Journal of China Coal Society
39
, no. 8
(August 2014
): 1511
–1520
, https://doi.org/10.13225/j.cnki.jccs.2014.90123.
Clarkson
C. R.
and Bustin
R. M.
, “Binary Gas Adsorption/Desorption Isotherms: Effect of Moisture and Coal Composition upon Carbon Dioxide Selectivity over Methane
,” International Journal of Coal Geology
42
, no. 4
(March 2000
): 241
–271
, https://doi.org/10.1016/S0166-5162(99)00032-44.
Fu
X.
, Qin
Y.
, Zhang
W.
, Wei
C.
, and Zhou
R.
, “Fractal Classification and Natural Classification of Coal Porosity Based on CBM Migration
,” Chinese Science Bulletin
50
, no. 1
(January 2005
): 66
–71
, https://doi.org/10.1007/bf031840855.
Liu
G.
, Zhang
Z.
, Zhang
X.
, and Lu
R.
, “Pore Distribution Regularity and Absorption-Desorption Characteristics of Gas Coal and Coking Coal
,” Chinese Journal of Rock Mechanics and Engineering
28
, no. 8
(August 2009
): 1587
–1592
.6.
Yao
Y.-B.
and Liu
D.-M.
, “Developing Features of Fissure System in Henan Coal Reserves Seams and Research on Mining of Coalbed Methane
,” Coal Science and Technology
34
, no. 3
(2006
): 64
–68
, https://doi.org/10.13199/j.cst.2006.03.68.yaoyb.0217.
Zhou
S.
, Liu
D.
, Cai
Y.
, and Yao
Y.
, “Fractal Characterization of Pore-Fracture in Low-Rank Coals Using a Low-Field NMR Relaxation Method
,” Fuel
181
(October 2016
): 218
–226
, https://doi.org/10.1016/j.fuel.2016.04.1198.
Durucan
S.
, Ahsanb
M.
, and Shi
J.-Q.
, “Matrix Shrinkage and Swelling Characteristics of European Coals
,” Energy Procedia
1
, no. 1
(February 2009
): 3055
–3062
, https://doi.org/10.1016/j.egypro.2009.02.0849.
Crosdale
P. J.
, Moore
T. A.
, and Mares
T. E.
, “Influence of Moisture Content and Temperature on Methane Adsorption Isotherm Analysis for Coals from a Low-Rank, Biogenically-Sourced Gas Reservoir
,” International Journal of Coal Geology
76
, nos. 1–2
(October 2008
): 166
–174
, https://doi.org/10.1016/j.coal.2008.04.00410.
Liu
A.
, Liu
S.
, Liu
P.
, and Wang
K.
, “Water Sorption on Coal: Effects of Oxygen-Containing Function Groups and Pore Structure
,” International Journal of Coal Science & Technology
8
, no. 5
(October 2021
): 983
–1002
, https://doi.org/10.1007/s40789-021-00424-611.
Sun
Y.
, Zhao
Y.
, and Yuan
L.
, “CO2-ECBM in Coal Nanostructure: Modelling and Simulation
,” Journal of Natural Gas Science and Engineering
54
(June 2018
): 202
–215
, https://doi.org/10.1016/j.jngse.2018.04.00712.
Liu
Y.
, Kang
J.
, Zhou
F.
, Fan
Y.
, and Li
H.
, “Effects of Maceral Compositions of Coal on Methane Adsorption Heat
,” Geofluids
2018
(2018
): 7596138, https://doi.org/10.1155/2018/759613813.
Blach
T.
, Radlinski
A. P.
, Vu
P.
, Ji
Y.
, de Campo
L.
, Gilbert
E. P.
, Regenauer-Lieb
K.
, and Mastalerz
M.
, “Deformation of Pores in Response to Uniaxial and Hydrostatic Stress Cycling in Marcellus Shale: Implications for Gas Recovery
,” International Journal of Coal Geology
248
(December 2021
): 103867, https://doi.org/10.1016/j.coal.2021.10386714.
He
X.
, Cheng
Y.
, Hu
B.
, Wang
Z.
, Wang
C.
, Yi
M.
, and Wang
L.
, “Effects of Coal Pore Structure on Methane-Coal Sorption Hysteresis: An Experimental Investigation Based on Fractal Analysis and Hysteresis Evaluation
,” Fuel
269
(June 2020
): 117438, https://doi.org/10.1016/j.fuel.2020.11743815.
Yang
Y.
, Liu
S.
, Zhao
W.
, and Wang
L.
, “Intrinsic Relationship between Langmuir Sorption Volume and Pressure for Coal: Experimental and Thermodynamic Modeling Study
,” Fuel
241
(April 2019
): 105
–117
, https://doi.org/10.1016/j.fuel.2018.12.00816.
Li
Z.
, Lin
B.
, Gao
Y.
, Cao
Z.
, Cheng
Y.
, and Yu
J.
, “Fractal Analysis of Pore Characteristics and Their Impacts on Methane Adsorption of Coals from Northern China
,” International Journal of Oil, Gas and Coal Technology
10
, no. 3
(2015
): 306
–324
, https://doi.org/10.1504/IJOGCT.2015.07150717.
Wang
B.
, Qin
Y.
, Shen
J.
, Zhang
Q.
, and Wang
G.
, “Pore Structure Characteristics of Low- and Medium-Rank Coals and Their Differential Adsorption and Desorption Effects
,” Journal of Petroleum Science and Engineering
165
(June 2018
): 1
–12
, https://doi.org/10.1016/j.petrol.2018.02.01418.
Xie
H.
and Zhou
H. W.
, “Application of Fractal Theory to Top-Coal Caving
,” Chaos, Solitons & Fractals
36
, no. 4
(May 2008
): 797
–807
, https://doi.org/10.1016/j.chaos.2006.07.02419.
Zhao
C.
, Zhang
R.
, Zhao
C.
, Wang
W.
, and Wang
Y.
, “A Three-Dimensional Evaluation of Interface Shear Behavior between Granular Material and Rough Surface
,” Journal of Testing and Evaluation
49
, no. 2
(March 2021
): 713
–727
, https://doi.org/10.1520/JTE2018074920.
Pyun
S.-I.
and Rhee
C.-K.
, “An Investigation of Fractal Characteristics of Mesoporous Carbon Electrodes with Various Pore Structures
,” Electrochimica Acta
49
, no. 24
(September 2004
): 4171
–4180
, https://doi.org/10.1016/j.electacta.2004.04.01221.
Pan
J.
, Zhu
H.
, Hou
Q.
, Wang
H.
, and Wang
S.
, “Macromolecular and Pore Structures of Chinese Tectonically Deformed Coal Studied by Atomic Force Microscopy
,” Fuel
139
(January 2015
): 94
–101
, https://doi.org/10.1016/j.fuel.2014.08.03922.
Peng
R.-D.
, Xie
H.-P.
, and Ju
Y.
, “Computation Method of Fractal Dimension for 2-D Digital Image
,” Journal of China University of Mining and Technology
33
, no. 1
(January 2004
): 22
–27
.23.
Liu
Y.
, Zhu
Y.
, Wang
Y.
, and Chen
S.
, “Fractal Characteristics of Nanoscale Pores in Shale and Its Implications on Methane Adsorption Capacity
,” Fractals
27
, no. 1
(February 2019
): 1940014, https://doi.org/10.1142/S0218348X1940014024.
Li
Z.-W.
, Hao
Z.-Y.
, Pang
Y.
, and Gao
Y.-B.
, “Fractal Dimensions of Coal and Their Influence on Methane Adsorption
,” Journal of China Coal Society
40
, no. 4
(2015
): 863
–869
, https://doi.org/10.13225/j.cnki.jccs.2014.302225.
Zhai
C.
, Qin
L.
, Liu
S.
, Xu
J.
, Tang
Z.
, and Wu
S.
, “Pore Structure in Coal: Pore Evolution after Cryogenic Freezing with Cyclic Liquid Nitrogen Injection and Its Implication on Coalbed Methane Extraction
,” Energy Fuels
30
, no. 7
(July 2016
): 6009
–6020
, https://doi.org/10.1021/acs.energyfuels.6b0092026.
Zhao
Y.
and Peng
L.
, “Investigation on the Size and Fractal Dimension of Nano-Pore in Coals by Synchrotron Small Angle X-ray Scattering
,” Chinese Science Bulletin
62
, no. 21
(2017
): 2416
–2427
, https://doi.org/10.1360/N972016-0097027.
Sastry
P. U.
, Sen
D.
, Mazumder
S.
, and Chandrasekaran
K. S.
, “Structural Variations in Lignite Coal: A Small Angle X-ray Scattering Investigation
,” Solid State Communications
114
, no. 6
(April 2000
): 329
–333
, https://doi.org/10.1016/S0038-1098(00)00060-028.
Radlinski
A. P.
, Mastalerz
M.
, Hinde
A. L.
, Hainbuchner
M.
, Rauch
H.
, Baron
M.
, Lin
J. S.
, Fan
L.
, and Thiyagarajan
P.
, “Application of SAXS and SANS in Evaluation of Porosity, Pore Size Distribution and Surface Area of Coal
,” International Journal of Coal Geology
59
, nos. 3–4
(August 2004
): 245
–271
, https://doi.org/10.1016/j.coal.2004.03.00229.
Diduszko
R.
, Swiatkowski
A.
, and Trznadel
B. J.
, “On Surface of Micropores and Fractal Dimension of Activated Carbon Determined on the Basis of Adsorption and SAXS Investigations
,” Carbon
38
, no. 8
(2000
): 1153
–1162
, https://doi.org/10.1016/S0008-6223(99)00236-530.
Niu
Q.
, Pan
J.
, Jin
Y.
, Wang
H.
, Li
M.
, Ji
Z.
, Wang
K.
, and Wang
Z.
, “Fractal Study of Adsorption-Pores in Pulverized Coals with Various Metamorphism Degrees Using N2 Adsorption, X-ray Scattering and Image Analysis Methods
,” Journal of Petroleum Science and Engineering
176
(May 2019
): 584
–593
, https://doi.org/10.1016/j.petrol.2019.01.10731.
Wang
Y.
, Zhang
T.
, Jing
L.
, Deng
P.
, Zhao
S.
, and Guan
D.
, “Exploring Natural Palm Fiber’s Mechanical Performance Using Multi-scale Fractal Structure Simulation
,” BioResources
15
, no. 3
(August 2020
): 5787
–5800
, https://doi.org/10.15376/biores.15.3.5787-580032.
Liu
D.
, Pallon
L. K. H.
, Pourrahimi
A. M.
, Zhang
P.
, Diaz
A.
, Holler
M.
, Schneider
K.
, Olsson
R. T.
, Hedenqvist
M. S.
, Yu
S.
, and Gedde
U. W.
, “Cavitation in Strained Polyethylene/Aluminium Oxide Nanocomposites
,” European Polymer Journal
87
(February 2017
): 255
–265
, https://doi.org/10.1016/j.eurpolymj.2016.12.02133.
Wang
W.
, Murthy
N. S.
, Chae
H. G.
, and Kumar
S.
, “Small-Angle X-ray Scattering Investigation of Carbon Nanotube-Reinforced Polyacrylonitrile Fibers during Deformation
,” Journal of Polymer Science Part B: Polymer Physics
47
, no. 23
(December 2009
): 2394
–2409
, https://doi.org/10.1002/polb.2183634.
Balima
F.
, Pischedda
V.
, Le Floch
S.
, Brûlet
A.
, Lindner
P.
, Duclaux
L.
, and San-Miguel
A.
, “An In Situ Small Angle Neutron Scattering Study of Expanded Graphite under a Uniaxial Stress
,” Carbon
57
(June 2013
): 460
–469
, https://doi.org/10.1016/j.carbon.2013.02.01935.
Cherny
A. Y.
, Anitas
E. M.
, Kuklin
A. I.
, Balasoiu
M.
, and Osipov
V. A.
, “Small-Angle Scattering from the Deterministic Fractal Systems
,” Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques
4
, no. 6
(November 2010
): 903
–907
, https://doi.org/10.1134/S102745101006005436.
Li
W.-H.
, Bai
X.-F.
, Yang
J.-H.
, Chen
W.-M.
, and Ma
W.-W.
, “Correspondence between Mean Maximum Reflectance of Vitrinite and Classification of Bituminous Coals
,” Journal of Chin Coal Society
31
, no. 3
(June 2006
): 342
–345
.37.
Li
Z.
, Wu
Z.
, Mo
G.
, Xing
X.
, and Liu
P.
, “A Small-Angle X-ray Scattering Station at Beijing Synchrotron Radiation Facility
,” Instrumentation Science & Technology
42
, no. 2
(March 2014
): 128
–141
, https://doi.org/10.1080/10739149.2013.84584538.
Hammersley
A. P.
, “FIT2D: A Multi-purpose Data Reduction, Analysis and Visualization Program
,” Journal of Applied Crystallography
49
, no. 2
(April 2016
): 646
–652
, https://doi.org/10.1107/S160057671600045539.
Li
Z.-H.
, “A Program for SAXS Data Processing and Analysis
,” Chinese Physics C
37
, no. 10
(October 2013
): 108002, https://doi.org/10.1088/1674-1137/37/10/10800240.
Vollet
D. R.
, Donatti
D. A.
, and Ibañez Ruiz
A.
, “Comparative Study Using Small-Angle X-ray Scattering and Nitrogen Adsorption in the Characterization of Silica Xerogels and Aerogels
,” Physical Review B
69
, no. 6
(February 2004
): 064202, https://doi.org/10.1103/PhysRevB.69.06420241.
Zhou
S.
, Liu
D.
, Cai
Y.
, Yao
Y.
, Jiao
Y.
, and Ren
S.
, “Characterization and Fractal Nature of Adsorption Pores in Low Rank Coal
,” Oil & Gas Geology
39
, no. 2
(2018
): 373
–383
.42.
Zhao
P.
, Wang
Z.
, Sun
Z.
, Cai
J.
, and Wang
L.
, “Investigation on the Pore Structure and Multifractal Characteristics of Tight Oil Reservoirs Using NMR Measurements: Permian Lucaogou Formation in Jimusaer Sag, Junggar Basin
,” Marine and Petroleum Geology
86
(September 2017
): 1067
–1081
, https://doi.org/10.1016/j.marpetgeo.2017.07.01143.
Cai
J.-C.
, Yu
B.-M.
, Zou
M.-Q.
, and Mei
M.-F.
, “Fractal Analysis of Surface Roughness of Particles in Porous Media
,” Chinese Physics Letters
27
, no. 2
(February 2010
): 024705, https://doi.org/10.1088/0256-307X/27/2/02470544.
Radlinski
A. P.
, Blach
T.
, Vu
P.
, Ji
Y.
, de Campo
L.
, Gilbert
E. P.
, Regenauer-Lieb
K.
, and Mastalerz
M.
, “Pore Accessibility and Trapping of Methane in Marcellus Shale
,” International Journal of Coal Geology
248
(December 2021
): 103850, https://doi.org/10.1016/j.coal.2021.10385045.
Mathews
J. P.
and Chaffee
A. L.
, “The Molecular Representations of Coal – A Review
,” Fuel
96
, no. 1
(June 2012
): 1
–14
, https://doi.org/10.1016/j.fuel.2011.11.02546.
Wang
Y.
, Zhang
Y.-G.
, and Xu
X.-K.
, “Relationship between the Maximum Vitrinite Reflectance and the Elastic Parameters of Coal: A Lab Ultrasonic Measurement of 6 Metamorphic Kinds of Coals
,” Chinese Journal of Geophysics
56
, no. 6
(June 2013
): 2116
–2122
.47.
Zhao
Y.
, Lin
B.
, Liu
T.
, Zheng
Y.
, Kong
J.
, Li
Q.
, and Song
H.
, “Mechanism of Multifield Coupling-Induced Outburst in Mining-Disturbed Coal Seam
,” Fuel
272
(July 2020
): 117716, https://doi.org/10.1016/j.fuel.2020.117716
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