基于酸热耦合作用的煤体微观孔隙结构演化规律研究

Research on evolution law of coal micropore structure based on acid-heat coupling

为了揭示酸热耦合作用在提高煤层透气性的作用机理,结合低温氮吸附法和压汞法在不同孔径测试下的优势,以X射线衍射(XRD)物相分析为辅助手段,从细微观多角度分析煤体孔隙结构。研究结果表明:酸热耦合条件对煤体孔隙结构有显著影响,且呈现随温度增加先增强后减弱的趋势;在50℃条件下,5%HF+5%HCl混合酸液对孔隙的改造作用最为显著,具体在微小孔阶段(低温氮吸附法测得)孔体积提高了22.3%,比表面积提高了23.9%,平均孔径提高57.1%,在可见裂纹阶段(压汞法测得)孔体积提高了110.2%。

In order to reveal the mechanism of acid-heat coupling in improving the permeability of coal seams,combined with the advantages of the low-temperature nitrogen adsorption method and mercury intrusion method under different pore size tests,X-ray diffraction(XRD)phase analysis was used as an auxiliary method to analyze the microscopic and multi-dimensional angle analysis of coal pore structure.The research results show that the coupling conditions of acid and heat have a significant effect on the pore structure of the coal body,and it shows a trend of first strengthening and then weakening with the increase of temperature.At 50℃,the 5%HF+5%HCl mixed acid solution has the most significant effect on pore reformation.Specifically,in the micro-pore stage(measured by the low-temperature nitrogen adsorption method),the pore volume increased by 22.3%,the specific surface area increased by 23.9%,and the average pore size increased by 57.1%.The pore volume increased by 110.2%in the visible crack stage(measured by the mercury intrusion method).