Abstract The low efficiency of coalbed methane (CBM) extraction not only causes a great waste of energy resources and environmental pollution but also poses potential safety risks during coal mining. The main reasons for these issues are the weak borehole sealing effect and serious air leakage that occur during CBM extraction. Seeking an effective sealing material is the key to improve the efficiency of CBM extraction and to protect the environment. In this paper, to explore ways to break through this bottleneck, the feasibility of silica sol (S.G325) as a sealing material for the boreholes used in CBM extraction was theoretically demonstrated. Scanning electron microscopy (SEM) was used to compare the surface morphological characteristics of S.G325 and some commonly used sealing materials. The performance of these materials after sealing the pores/fractures in the methane reservoir was also evaluated using mercury intrusion, an helium porosimeter and methane seepage tests. The experimental results indicate that S.G325 has obvious advantages over other materials because of its greater compactness, stability and performance after sealing. Evaluation of the effects of enhancing CBM extraction showed that S.G325 increased the initial concentration of CBM from 60% to 73.5%–82.9%, the amount of time the CBM that can be utilized from 54 d to 99 d - 132 d, the volume of utilizable CBM from 3421 m3 to 4951 m3 - 5773 m3, and the utilization rate of CBM increased by 44.7%–62.8% compared with the original utilizable methane volume. In this paper, new insights into the improvement of energy resource utilization and protection of the environment are shown.

中文翻译：

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硅溶胶对煤层气储层封闭机制的影响：提高甲烷浓度和利用率的新见解

摘要 煤层气（CBM）抽采效率低，不仅造成能源资源的大量浪费和环境污染，而且在煤炭开采过程中存在安全隐患。造成这些问题的主要原因是煤层气开采过程中井眼封闭效果差、漏气严重。寻求有效的密封材料是提高煤层气开采效率和保护环境的关键。本文为探索突破这一瓶颈的途径，从理论上论证了硅溶胶（S.G325）作为煤层气开采钻孔密封材料的可行性。扫描电子显微镜（SEM）用于比较S.G325和一些常用密封材料的表面形态特征。这些材料在封闭甲烷储层中的孔隙/裂缝后的性能也使用压汞、氦气孔隙率计和甲烷渗漏测试进行了评估。实验结果表明，S.G325在密封后具有更好的致密性、稳定性和性能，与其他材料相比具有明显的优势。对提高煤层气提取效果的评价表明，S.G325 将煤层气初始浓度从 60% 提高到 73.5%–82.9%，煤层气可利用时间从 54 d 增加到 99 d - 132 d可利用煤层气量从3421 m3 增加到4951 m3 - 5773 m3，煤层气利用率比原可利用甲烷量增加44.7%～62.8%。在本文中，