Volume and Surface Distribution Heterogeneity of Nano-pore in Coal Samples by CO2 and N2 Adsorption Experiments |
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| Authors: | ZHANG Junjian WEI Chongtao LUO Jinhui LU Guanwen QUAN Fangkai ZHENG Kai PENG Yujie |
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| Institution: | 1 College of Earth Sciences & Engineering, Shandong University of Science and Technology, Qingdao, Shandong 266590, China
2 School of Resources and Earth Science, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China; 3 Construction Equipment College, Guizhou Polytechnic of Construction, Guiyang 551400, China |
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| Abstract: | In this paper, the heterogeneity of adsorption pores in middle and high rank coal samples were analyzed by using low temperature N2 and CO2 adsorption technology and fractal theory. The following results were achieved. 1) According to the results of volume and surface fractal dimension, meso-pores can be classified into Mep-1, Mep-2, and Mep-3, respectively. Micro-pore can be classified into Mip-1, Mip-2, and Mip-3, respectively. 2) Pore types play an important role in affecting the heterogeneity of meso-pores. The volume heterogeneity (VHY) of Mep-1 is simpler than that of Mep-2 and Mep-3 in type A samples. However, the VHY of Mep-1 becomes gradually larger than that of Mep-2 and Mep-3 from type A to type B and C. The VHY of open pore in the same diameter is higher than that of semi-open or closed pore. Meanwhile, the surface heterogeneity (SHY) of types A and B samples is significantly larger than that of type C, the SHY of semi-open or closed pores is more complicated than that of open pores. 3) Coal rank mainly affects the heterogeneity of micro-pores. The heterogeneity of type A is always smaller than that of type B and C. The VHY of Mip-1 is more complicated than that of Mip-2 and Mip-3 in the same samples, and the sensitivity of the VHY of Mip-1 and Mip-2 to the degree of coal rank is smaller than that of Mip-3. Meanwhile, the SHY of Mip-1 and Mip-2 is simpler than that of Mip-3 in the same sample, the SHY of micro-pores remains stable as the pore size decreases, and the affect of coalification level on SHY decreases with the decrease in pore diameter. Full-scale fractal characterization has enabled quantitative characterization of adsorption pore properties and provided useful information with regards to the similarity of pore features in different coal reservoirs. |
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| Keywords: | pore volume and surface fractal dimension adsorption pore middle and high rank coal western Guizhou and eastern Yunnan area |
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