Key Laboratory of Ministry of Education for Coal Methane and Fire Control, China University of Mining and Technology

为揭示煤微观结构变化对瓦斯解吸的影响，以河南省平顶山八矿的煤样为研究对象，选取1-丁基-3甲基咪唑四氟硼酸盐、十二烷基硫酸钠对煤样进行浸泡处理，结合低温液氮吸附、红外光谱、X射线衍射、吸附常数a测量、接触角测量以及瓦斯驱替和卸压解吸实验进行研究。结果表明：表面活性剂可以显著改变煤的孔隙特征、分子基团以及微晶结构。煤样微孔的比表面积减少、平均孔径增大，孔裂隙网络更加畅通。煤样的化学官能团发生变化，平均链长和脂芳比减少、富氧程度比值增大。芳香环层片层间距和芳香度增加，芳香层片堆砌高度和芳香堆砌层数减小，芳香层结构排列更紊乱疏松，芳香环缩合程度降低，煤分子排列被打乱，有序结构范围减小。这些孔隙特征、分子基团以及微晶结构发生的变化，大幅改善了煤体的润湿性，使得溶液侵入煤样内部的难度减小，有助于强化瓦斯驱替，增强瓦斯抽采效率，同时滞留在煤体孔隙中的溶液增多，所以卸压后，煤样瓦斯解吸和排出受阻，瓦斯解吸速率降低，水锁效应增强。本研究结果为煤层瓦斯资源开采提供理论指导，通过添加表面活性剂等方式人为改变煤的微观结构，进而定向改变瓦斯解吸特性，提高瓦斯抽采效率，同时在煤层开采时，避免大量瓦斯的突然涌出，从而实现煤层气高效、安全抽采。

In order to reveal the effect of changes in coal microstructure on gas desorption, this study selected coal samples from the Eighth Mine in Pingdingshan, Henan Province as the research object, and used two surfactants, 1-Butyl-3-methylimidazolium tetrafluoroborate and Sodium dodecyl sulfate, to soak the coal samples. The coal samples were investigated by low temperature liquid nitrogen adsorption, infrared spectroscopy, X-ray diffraction, the measurement experiment of adsorption constant a, contact angle measurement, and gas displacement and desorption experiment. The findings indicate that surfactants can dramatically alter the pore properties, molecular groups, and microcrystalline structure of coal. The specific surface area of the coal sample micropores decreases and the average pore diameter increases, so that the pore and fracture network is more smooth. The chemical functional groups of the coal samples change, the average chain length and the fat ratio decrease, and the oxygen enrichment degree increases. The aromatic ring layer spacing and aromaticity of the coal sample increase, while the aromatic layer stacking height and the number of aromatic stacking layers decrease, indicating that the structure arrangement of aromatic layer is more disordered and loose, the degree of condensation of aromatic ring is reduced, the arrangement of coal molecules is disrupted, and the range of ordered structure is narrowed. These changes in pore characteristics, molecular groups and microcrystalline structure greatly improve the wettability of coal and reduce the difficulty of solution intruding into coal samples, which helps to strengthen gas displacement and enhance the efficiency of gas extraction. At the same time, the solution in the pores of coal body increases, so after pressure relief, the coal sample gas desorption and discharge are blocked, the gas desorption rate decreases, and the water lock effect is enhanced. The results of this study provide a theoretical guidance for the exploitation of coal seam gas resources. By adding surfactants and other methods, the microstructure of coal is artificially changed, and then the gas desorption characteristics are directionally changed to improve the gas extraction efficiency. During coal seam mining, the sudden outflow of a large amount of gas can be avoided, so as to achieve an efficient and safe extraction of coal seam methane.

国家自然科学基金面上资助项目(52274239)；中央高校基本科研业务费专项资金资助项目(2021ZDPYYQ008)

杨威，罗黎明，王一涵，等. 煤微观结构化学调控及注水驱替瓦斯规律[J]. 煤炭学报，2023，48(8)：3091−3101.

YANG Wei，LUO Liming，WANG Yihan，et al. Chemical regulation of coal microstructure and study of water injection displacement gas law[J]. Journal of China Coal Society，2023，48(8)：3091−3101.