Zhang Beixi, Wang Haichao, Sun Bin, Ouyang Zheyuan, Dou Wei, Wang Bo, Lai Peng, Hu Zhenpeng, Luo Bing, Yang Mengmeng, Zeng Zhiwei
Xinjiang Key Laboratory for Geodynamic Processes and Metallogenic Prognosis of the Central Asian Orogenic Belt, Xinjiang University, Urumqi, Xinjiang 830047, China.
School of Geological and Mining Engineering, Xinjiang University, Urumqi, Xinjiang 830047, China.
ACS Omega. 2024 Jul 20;9(30):32837-32852. doi: 10.1021/acsomega.4c03510. eCollection 2024 Jul 30.
Important breakthroughs have recently been achieved in deep coalbed methane (CBM) exploration and development in regions such as the eastern margin of the Ordos Basin, China. Investigating the development characteristics of various-scale pores in deep coalbeds is of great significance for resource assessment and selection of favorable zones for CBM exploration. Herein, six deep coal samples were selected from the Shanxi and Taiyuan Formations in the Daning-Jixian block on the eastern margin of the Ordos Basin. Low-pressure CO/N adsorption (LP-CO/NGA) and high-pressure mercury intrusion (HPMI) methods were employed to analyze pore volume, specific surface area, and pore size distribution, thereby evaluating the full-scale pore characteristics. Furthermore, the fractal dimension characteristics of deep coal rock pores were elucidated, revealing the influence of pore structure, burial depth, and coal composition. The results indicate that micropores in deep coal rocks have the highest volume and specific surface area proportions, while mesopores have the smallest volume proportion, and macropores make the least contribution to the total specific surface area. The -, Frenkel-Halsey-Hill, and Sierpinski models were suitable for calculating the fractal dimensions of micropores, mesopores, and macropores with LP-COGA, LP-NGA, and HPMI experimental data, respectively. Other than the relatively smaller mesopore fractal dimension of samples 20-8 and 20-10, the micropore, mesopore, and macropore fractal dimensions successively increased in the other four samples. The comprehensive fractal dimension, which exhibited a decreasing trend with increasing pore volume and specific surface area, was negatively correlated with burial depth, mineral and moisture contents, and ash and volatile component yields, while it was positively correlated with vitrinite and fixed carbon contents.
近年来，中国鄂尔多斯盆地东缘等地区的深部煤层气（CBM）勘探开发取得了重要突破。研究深部煤层中不同尺度孔隙的发育特征，对于煤层气资源评价和有利区带选择具有重要意义。在此，从鄂尔多斯盆地东缘大宁 - 吉县区块的山西组和太原组选取了6个深部煤样。采用低压CO₂/N₂吸附（LP - CO₂/N₂GA）和高压压汞（HPMI）方法分析孔隙体积、比表面积和孔径分布，从而评估全尺度孔隙特征。此外，阐明了深部煤岩孔隙的分形维数特征，揭示了孔隙结构、埋藏深度和煤质组成的影响。结果表明，深部煤岩中微孔的体积和比表面积占比最高，而中孔的体积占比最小，大孔对总比表面积的贡献最小。-、Frenkel - Halsey - Hill和Sierpinski模型分别适用于用LP - CO₂GA、LP - N₂GA和HPMI实验数据计算微孔、中孔和大孔的分形维数。除了20 - 8和20 - 10号样品的中孔分形维数相对较小外，其他4个样品的微孔、中孔和大孔分形维数依次增加。综合分形维数随孔隙体积和比表面积的增加呈下降趋势，与埋藏深度、矿物和水分含量以及灰分和挥发分产率呈负相关，而与镜质体和固定碳含量呈正相关。
