采空区瓦斯涌出来源量化判识方法——以寺河矿为例

摘要

This paper describes a new method for determining the individual sources of goaf gas emissions in Shihe coal mine.Desorbed gases from coal seam No.3 and its seven neighboring seams were respectively sampled and analyzed of their composition including CH4,C2H6,stable carbon isotopes in CO2 and hydrogen isotopes in CH4.Based on the analyzed results,a mathematical model was developed for calculating the sources of goaf gas emissions.The model was then applied in No.5302 panel in Shihe coal mine to determine the emission sources of the goaf gas from each of the coal seams.The results show that CH4 concentration,stable carbon isotopes in CO2 and hydrogen isotopes in CH4 increased with the depth of No.3 seam.In terms of the characteristics of goaf gas emissions in No.5302 panel,it can be divided into three stages with the panel advance.In the initial stage,the goaf gas emission was dominated with gas desorbed from the mining No.3 seam,this dominance weakened as the panel advances and stabilized at around 20％-25％ of the total goaf gas emissions.In the second stage,gas from neighboring seams started to play an important role in the goaf gas,taking up 20％-25％ of the total goaf gas emissions.In the third stage,the sources of the goaf gas emission became stable and gases desorbed from No.9 and No.15 seams made up 20％-25％ and 30％-35％ of the total goaf gas emissions respectively.This isotopes based method,in comparison with the tradition method for determining the sources of goaf gas emissions,can give quantitative description of dynamic change in the individual sources of goaf gas emissions with the advance of a mining panel,enabling a more targeted and effective control of goaf gas emissions.%为准确量化和动态反映工作面采空区瓦斯涌出来源,以沁水盆地寺河矿为研究区,采集煤体解吸瓦斯,测试分析了3号煤层及其7层邻近煤层解吸瓦斯组成成分,CH4,C2H6,CO2稳定碳同位素值,CH4氢同位素值及其分布特征,建立了基于稳定碳氢同位素和组分平均值的采空区瓦斯分源计算模型,实现采空区沿走向推进时各煤层瓦斯来源的量化分源计算,并完成了与传统分源预测计算结果的对比分析.研究表明,寺河矿主要煤层解吸气组分和稳定碳氢同位素值在横纵向均存在差异,总体表现为瓦斯中甲烷体积分数随煤层深度增大而增大,瓦斯碳氢同位素随深度增大出现偏重的特点,5302工作面采空区沿走向瓦斯涌出动态变化过程可以分本煤层涌入主体阶段、近邻近层涌入过渡阶段、动态平衡稳定阶段.随工作面推进,采空区内3号煤瓦斯涌出占比逐渐下降,最终稳定在20％～25％,近邻近层呈现先升后降并趋稳的特征,最终稳定在20％～25％,远邻近层9和15号瓦斯涌入主要在滞后工作面110 m后逐渐上升后趋稳,9号煤瓦斯最终占比20％～25％,15号煤瓦斯最终占比30％～35％.与传统分源预测结论相比,稳定碳氢同位素量化分源可以反映采空区内各煤层瓦斯涌出的动态演化过程,相比分源预测结论更有利于指导工作面生产实际.