Wang Zehua, Cui Hongqing, Wei Guoying, Jia Tianrang, Guo Jingyuan, He Xin
School of Safety Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China.
State Key Laboratory Cultivation Base for Gas Geology and Gas Control, Henan Polytechnic University, Jiaozuo 454000, Henan, China.
ACS Omega. 2021 Oct 18;6(43):28983-28991. doi: 10.1021/acsomega.1c04004. eCollection 2021 Nov 2.
Quantitative characterization of the pore structure and gas seepage characteristics of loaded coal is of great significance to the study of high-efficiency gas drainage in coal seams. Aiming at the problem of imperfect characterizations of coal seepage characteristics based on nuclear magnetic resonance (NMR), a calculation method for the pore permeability of coal with different pore diameters is proposed. The pore structure and seepage characteristics of coal have been quantitatively studied using a nuclear magnetic resonance (NMR) system. The results show that with increasing external load, the proportion of the pore volume of the coal sample in the range of 0.01-0.52 μm gradually decreases, while that in the range of 5.11-352.97 μm increases. In this process, the porosity increases from 0.9967 to 1.0103%, the connectivity increases from 0.1718 to 0.2391, and the permeability increases from 2.64 × 10 to 8.20 × 10 μm. The calculation of the coal sample connectivity and permeability using the improved NMR permeability component proves that 94.37-352.97 μm pores are the main channel of fluid flow. When the axial pressure increases, the coal body permeability in the aperture range of 94.37-352.97 μm rapidly increases. The improved permeability component calculation model can better reflect the variation law of pore permeability of the loaded coal body.
加载煤体孔隙结构与瓦斯渗流特性的定量表征对煤层高效瓦斯抽采研究具有重要意义。针对基于核磁共振（NMR）对煤体渗流特性表征不完善的问题，提出了不同孔径煤体孔隙渗透率的计算方法。利用核磁共振（NMR）系统对煤体孔隙结构与渗流特性进行了定量研究。结果表明，随着外部载荷增加，煤样孔径在0.01 - 0.52μm范围内的孔隙体积占比逐渐减小，而在5.11 - 352.97μm范围内的孔隙体积占比增加。在此过程中，孔隙率从0.9967%增加到1.0103%，连通性从0.1718增加到0.2391，渗透率从2.64×10μm增加到8.20×10μm。采用改进的NMR渗透率分量对煤样连通性和渗透率进行计算，证明94.37 - 352.97μm孔径的孔隙是流体流动的主要通道。当轴向压力增加时，孔径在94.37 - 352.97μm范围内的煤体渗透率迅速增加。改进后的渗透率分量计算模型能更好地反映加载煤体孔隙渗透率的变化规律。
