Experimental Study on the Microstructure Evolution Laws in Coal Seam Affected by Temperature Impact
Experimental Study on the Microstructure Evolution Laws in Coal Seam Affected by Temperature Impact
复制标题
温度影响下煤层微观结构演化规律的试验研究
DOI：
10.1007/s00603-019-01978-3
复制
发表时间：
2020-03-01
影响因子：
6.2
通讯作者：
Li, Xuelong
中科院分区：
文献类型：
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作者：
Liu, Shumin;Wang, Dengke;Li, Xuelong
煤的微观结构对煤层的渗透性有显著影响。为研究温度冲击下煤层微观结构变化特征，采用高低温试验系统进行了温度冲击实验，采用扫描电镜、工业显微计算机断层扫描、压汞等方法研究了温度冲击前后煤层孔隙和裂隙结构。基于数字图像处理技术和热应力理论，定性和定量分析了裂隙宽度、比表面积和孔径的变化规律，深入分析了温度对煤层微观结构影响的破坏机理。结果表明：温度影响使煤样中的大孔隙相互贯通，形成宏观裂缝，导致大孔隙体积相对较小，中孔和小孔隙体积增大；温度冲击过程中产生的最大热应力位于煤样表面切向。温度冲击产生的热应力超过了煤样的抗拉强度，直接导致裂纹萌生、扩展和相互渗透。该研究为煤层气高效开发和提高煤层瓦斯抽放速率提供了必要的技术支持。
The microstructure of coal has a significant influence on the permeability of the coal seam. To study the characteristics of microstructure changes in coal seam under temperature impact, we conducted temperature-impact experiments using a high-low temperature test system, and we studied the coal pores and fissure structure before and after the temperature impact using scanning electron microscopy, industrial micro-computed tomography, and mercury intrusion. Based on the digital image processing technology and thermal stress theory, we qualitatively and quantitatively analyzed the variation of crack width, specific surface area, and pore diameter, and deeply analyzed the failure mechanism of temperature impact on coal seam microstructure. The results showed that the temperature impact caused the macropores to interpenetrate and form macroscopic cracks in the coal sample, which resulted in a relatively small volume of macropores and increased the volume of mesopores and small pores. The maximum thermal stress generated during the temperature impact process was located in the tangential direction of the coal sample surface. The thermal stress generated by the temperature impact exceeded the tensile strength of the coal sample, which directly causes crack initiation, expansion, and mutual penetration. This study provided the technical support necessary for the efficient development of coalbed methane and the improvement of gas drainage rate in the coal seam.