煤孔隙结构对钻屑瓦斯解吸指标敏感度的影响

Influence of pore structure of coal on sensitivity of drillings gas desorption index

为研究新疆榆树岭煤矿下5煤层低瓦斯含量、高瓦斯压力的赋存对煤层钻屑瓦斯解吸指标敏感度的影响,采用恒温瓦斯放散试验、低温液氮吸附法测定榆树岭下5煤层煤样及端氏3号煤层煤样瓦斯吸附规律及孔隙构成,总结分析不同变质程度煤样的孔隙结构特征、瓦斯解吸速率对钻屑解吸指标准确性的影响。结果表明:瓦斯解吸扩散速率受煤的变质程度及孔隙结构的影响较大,低阶气煤前10 min内的瓦斯解吸速率整体趋势平稳,端氏高阶无烟煤在前4 min瓦斯解吸速率较快,后6 min瓦斯解吸速率趋势平稳;榆树岭煤钻屑瓦斯解吸指标K1与瓦斯压力相关性较钻屑瓦斯解吸指标Δh2差,而端氏煤钻屑瓦斯解吸指标K1与瓦斯压力相关性优于钻屑瓦斯解吸指标Δh2;Δh2更适合作为低阶煤突出预测指标,K1作为高阶煤突出预测指标较适用。

In order to study the influence of low gas content and high gas pressure of the occurrence of the lower 5#coal seam of Yushuling Coal Mine in Xinjiang on the sensitivity of coal seam drillings gas desorption index,this paper adopted a constant temperature gas release test and low-temperature liquid nitrogen adsorption method to determine the gas adsorption law and pore composition of the coal samples of the lower 5#coal seam of Yushuling and the coal sample of Duanshi No.3 coal seam,to summarize and analyze the influence of pore structure characteristics and gas desorption rate of coal samples with different degrees of metamorphism on the accuracy of drillings desorption index.The results show that:the degree of coal metamorphism and pore structure have a great influence on gas desorption and diffusion rate,and the overall trend of gas desorption rate of Yushuling low-rank gas coal is stable in the first 10 min,while the trend of gas desorption rate of Duanshi high-rank anthracite is faster in the first 4 min and stable in the last 6 min;the correlation between drillings gas desorption index K1and gas pressure p of Yushuling coal is poorer than that ofΔh2,while the correlation between K1 and gas pressure p is better than that ofΔh2 for Duanshi coal drillings gas desorption index.The analysis concludes thatΔh2 is more suitable as a predictor of the outburst of low-rank coal,and K1 is more suitable as a predictor of the outburst of high-rank coal.