重复脉冲强冲击波对肥煤孔隙结构影响的实验研究

利用自行搭建的重复脉冲强冲击波煤体致裂实验平台，以肥煤为研究对象，在2种实验条件下分别对2块煤样进行了重复冲击实验，采集每块煤样在不同冲击次数下的样品，通过扫描电镜、压汞、核磁共振、氦孔隙度和空气渗透率等实验，对煤的孔隙结构和渗透性变化特征进行了研究。结果表明：随冲击次数的增加，整体上煤的孔容、比表面积、孔隙度、孔径分布范围均有增大趋势；大孔和中孔孔容增加显著，孔隙度增幅高达74%，孔径分布范围由最初的分散孤立逐渐变得连续；开放孔增多，孔隙连通性增强，渗透性增加，孔隙结构得以改善。分析认为重复脉冲强冲击波可以有效地改善煤的孔隙结构，提高煤储层的渗透性，有利于煤层气的产出。

Experimental study on the effect of strong repetitive pulse shockwave on the pore structure of fat coal

A self-designed experimental platform was established to study the variation characteristics of pore structure and the permeability of coal body affected by strong repetitive pulse shockwave.Two large fat coal blocks were tested with repeated impulses under two different experimental conditions respectively.In addition,the coal samples under different times of impulsion were collected,and subsequently the scanning electron microscopy,mercury injection,nuclear magnetic resonance,helium porosity and air permeability experiment were carried out.The results show that the pore volume,surface area,porosity and distribution range of pore size present an increasing trend with the number of discharge pulses;the volumes of mesopore and macropore increase obviously,and the increasing amplitude of porosity reaches up to 74%,and the distribution range of pore size gradually becomes continuous compared with initial dispersion and isolation.Moreover,the open pore increases,and pore connectivity and permeability are enhanced,which demonstrates that the pore structure is improved.The experimental results indicate that the pore structure and permeability can be improved by strong repetitive pulse shockwave technology,which benefits the output of coalbed methane.