| Citation: |
ZHANG Kun，MENG Zhaoping，JIN Yi，et al. Fractal characteristics of pore structures on different coal structures and its research significance[J]. Coal Science and Technology，2023，51（10）：198−206. DOI: 10.13199/j.cnki.cst.2022-1867
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The occurrence and production of coalbed methane is related to the development degree of pore system in coal reservoirs. The pore structure characteristics of original structural coal seam will change significantly after damage and deformation, thus affecting the adsorption/desorption and diffusion process of coalbed methane. Through the low-temperature liquid N2 and low-pressure CO2 adsorption analysis and isothermal adsorption experiments on coal with different structures from the No. 3 coal seam in Zhaozhuang coalfield in Qinshui Basin, the variation laws of pore structure and adsorption of coals with various destructive strengths were analyzed. Applying experimental data and numerical fractal modeling, the pore fractal characteristics of coal with different structures and their effects on methane adsorption and diffusion in coal were revealed. The results shown that with the increase of the destructive intensity of coal structures, the specific surface area and pore volume of coal increased, the proportion of 50-300 nm pores gradually decreased, the micropores and mesopores of 2-50 nm and ultra-micropores of less than 2 nm increased. As the main adsorption pores in coal, the ultra-micropores size was mainly distributed in 0.45-0.65 nm and 0.80-1.0 nm. The adsorption amount of N2, CO2 and CH4 increased with the increasing destructive degree of coal structure. The order of adsorption capacity from large to small was: intact coal>mylonitic coal > granulated coal > cataclastic coal. The fractal dimensions of the micro-, meso- and macro-porous structures indicated that the pore structure of tectonically deformed coals will be simplified. Coal with a higher damage intensity had a rougher pore surface (corresponding to a higherD1) and a more homogeneous pore size distribution (corresponding to a lowerD2). The fractal dimension of ultra-microporous (Dm) gradually increased with the increasing structural destruction intensity of coal, and was positively correlated with Langmuir constant (VL) and the corresponding specific surface area, indicating that the increase of coal surface roughness led to the increase of specific surface area, which provided more adsorption points with high adsorption potential for gas adsorption and enhanced the adsorption capacity of coal. The effective diffusion coefficient and pore volume were positively correlated with the fractal dimensionsD1 and negatively correlated withD2, which indicated better pore connectivity, increased pore volume, improved gas inlet and outlet efficiency, and enhanced gas diffusion efficiency of destroyed intact coal.
| [1] |
YAN J,MENG Z,ZHANG K,et al. Pore distribution characteristics of various rank coals matrix and their influences on gas adsorption[J]. Journal of Petroleum Science and Engineering,2020,189:107041.
|
| [2] |
杨 明,柳 磊,刘佳佳,等. 中阶煤孔隙结构的氮吸附-压汞-核磁共振联合表征研究[J]. 煤炭科学技术,2021,49(5):67−74. doi: 10.3969/j.issn.1673-1328.2020.02.035
YANG Ming,LIU Lei,LIU Jiajia,et al. Study on joint characterization of pore structure of middle-rank coal by nitrogen adsorption-mercury intrusion-NMR[J]. Coal Science and Technology,2021,49(5):67−74. doi: 10.3969/j.issn.1673-1328.2020.02.035
|
| [3] |
BRUNAUER S,EMMETT P H,TELLER E. Adsorption of gases in multimolecular layers[J]. Journal of the American Chemical Society,1938,60(2):309−319.
|
| [4] |
LI X,KANG Y,HAGHIGHI M. Investigation of Pore Size Distributions of Coals with Different Structures by Nuclear Magnetic Resonance (NMR) and Mercury Intrusion Porosimetry (MIP)[J]. Measurement,2018,116:122−128. doi: 10.1016/j.measurement.2017.10.059
|
| [5] |
NIE B,LIU X,YANG L,et al. Pore structure characterization of different rank coals using gas adsorption and scanning electron microscopy[J]. Fuel,2015,158:908−917. doi: 10.1016/j.fuel.2015.06.050
|
| [6] |
WEI M. ZHANG L. XIONG Y. et al. Nanopore structure characterization for organic-rich shale using the non-local-density functional theory by a combination of N2 and CO2 adsorption[J]. Microporous and Mesoporous Materials,2016,227:88−94. doi: 10.1016/j.micromeso.2016.02.050
|
| [7] |
王佑安,杨思敬. 煤和瓦斯突出危险煤层的某些特征[J]. 煤炭学报,1980,1(6):47−53. doi: 10.13225/j.cnki.jccs.1980.01.006
WANG Youan,YANG Sijing. Some characteristics of coal seams with hazard of outburst[J]. Journal of China Coal Society,1980,1(6):47−53. doi: 10.13225/j.cnki.jccs.1980.01.006
|
| [8] |
JU Y. W, LI X. S. New research progress on the ultrastructure of tectonically deformed coals[J]. Progress in Natural Science,2009,19:1455−1466. doi: 10.1016/j.pnsc.2009.03.013
|
| [9] |
YU S,BO J,MING L,et al. A review on pore-fractures in tectonically deformed coals[J]. Fuel,2020,278:118248. doi: 10.1016/j.fuel.2020.118248
|
| [10] |
王 涛,黄文涛. 江西省新华煤矿软分层煤层的孔隙结构特征[J]. 中国煤田地质,1994,6(4):57−59.
WANG Tao,HUANG Wentao. Pore structure characteristics of soft stratified coal seam in Xinhua coal mine, Jiangxi Province[J]. Coal Geology of China,1994,6(4):57−59.
|
| [11] |
孟召平,刘珊珊,王保玉,等. 不同煤体结构煤的吸附性能及其孔隙结构特征[J]. 煤炭学报,2015,40(8):1865−1870. doi: 10.13225/j.cnki.jccs.2015.0620
MENG Zhaoping,LIU Shanshan,WANG Baoyu,et al. Adsorption capacity and its pore structure of coals with different coal body structure[J]. Journal of China Coal Society,2015,40(8):1865−1870. doi: 10.13225/j.cnki.jccs.2015.0620
|
| [12] |
金 毅,权伟哲,秦建辉,等. 孔隙-孔喉分形多孔介质复杂类型组构模式表征[J]. 煤炭学报,2020,45(5):1845−1854.
JIN Yi,QUAN Weizhe,QIN Jianhui,et al. Quantitative characterization of complex assembly in fractal pore-throat porous media[J]. Journal of China Coal Society,2020,45(5):1845−1854.
|
| [13] |
傅雪海,秦 勇,张万红,等. 基于煤层气运移的煤孔隙分形分类及自然分类研究[J]. 科学通报,2005,50(S1):51−55.
FU Xuehai,QIN Yong,ZHANG Wanhong,et al. Fractal classification and natural classification of coal pores based on coalbed gas migration[J]. Science China Press,2005,50(S1):51−55.
|
| [14] |
宋 昱,姜 波,李凤丽,等. 低-中煤级构造煤纳米孔分形模型适用性及分形特征[J]. 地球科学,2018,43(5):1611−1622.
SONG Yu,JIANG Bo,LI Fengli,et al. Applicability of fractal models and nanopores’ fractal characteristics for low-middle rank tectonic deformed coals[J]. Earth Science,2018,43(5):1611−1622.
|
| [15] |
杨师宇,姚艳斌,魏 韧,等. 乌鲁木齐河东矿区煤储层渗流孔孔隙分形特征研究[J]. 煤炭科学技术,2020,48(8):175−183. doi: 10.13199/j.cnki.cst.2020.08.022
YANG Shiyu,YAO Yanbin,WEI Ren,et al. Study on fractal characteristics of seepage pores of coal reservoirs in Hedong Mining Area of Urumqi[J]. Coal Science and Technology,2020,48(8):175−183. doi: 10.13199/j.cnki.cst.2020.08.022
|
| [16] |
降文萍,宋孝忠,钟玲文. 基于低温液氮实验的不同煤体结构煤的孔隙特征及其对瓦斯突出影响[J]. 煤炭学报,2011,36(4):609−614. doi: 10.13225/j.cnki.jccs.2011.04.021
JIANG Wenping,SONG Xiaozhong,ZHONG Lingwen. Research on the pore properties of different coal body structure coals and the effects on gas outburst based on thelow-temperature nitrogen adsorption method[J]. Journal of China Coal Society,2011,36(4):609−614. doi: 10.13225/j.cnki.jccs.2011.04.021
|
| [17] |
金 毅,赵梦余,刘顺喜,等. 基于压汞法的煤基质压缩对孔隙分形特征的影响[J]. 中国煤炭,2018,44(8):103−109. doi: 10.19880/j.cnki.ccm.2018.08.020
JIN Yi,ZHAO Mengyu,LIU Shunxi,et al. Study on the effect of coal matrix compression on fractal characteristics of pore structures by mercury intrusion method[J]. China Coal,2018,44(8):103−109. doi: 10.19880/j.cnki.ccm.2018.08.020
|
| [18] |
EVERETT D H. Manual of symbols and terminology for physicochemical quantities and units, appendix II: definitions, terminology and symbols in colloid and surface chemistry[J]. Pure and Applied Chemistry,1972,31(4):577−638.
|
| [19] |
HODOT B B. Outburst of coal and coalbed gas (Chinese Translation)[M]. Beijing: China Industry Press, 1966: 10−50.
|
| [20] |
HOU S,WANG X,WANG X,et al. Pore structure characterization of low volatile bituminous coals with different particle size and tectonic deformation using low pressure gas adsorption[J]. International Journal of Coal Geology,2017,183:1−13. doi: 10.1016/j.coal.2017.09.013
|
| [21] |
VISHNYAKOV A,RAVIKOVITCH PI,NEIMARK A. Molecular level models for CO2 sorption in nanopores[J]. Langmuir,1999,15(25):8736−8742.
|
| [22] |
WANG F,LI S. Determination of the surface fractal dimension for porous media by capillary condensation[J]. Industrial & Engineering Chemistry Research,1997,36(5):1598−1602.
|
| [23] |
PFEIFER P,AVNIR D. Chemistry nonintegral dimensions between two and three[J]. Journal of Chemical Physics,1983,79(7):3369−3558.
|
| [24] |
SING K S. IUPAC Recommendations 1984: reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity[J]. Pure and Applied Chemistry,1985:603−619.
|
| [25] |
JIN Y,ZHAO M,ZHENG J,et al. Characterizing the complexity assembly of pore structure in a coal matrix: principle, methodology, and modeling application[J]. Journal of Geophysical Research: Solid Earth,2020,125(12):e2020JB020110.
|
| [26] |
孟召平,张 昆,沈 振. 构造煤与原生结构煤中甲烷扩散性能差异性分析[J]. 煤田地质与勘探,2022,50(3):102−109. doi: 10.12363/issn.1001-1986.21.12.0799
MENG Zhaoping,ZHANG Kun,SHEN Zhen. Difference analysis of methane diffusion properties between tectonic coal and primary coal[J]. Coal Geology & Exploration,2022,50(3):102−109. doi: 10.12363/issn.1001-1986.21.12.0799
|
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