CO_(2)驱替煤体内部CH_(4)气体变化模拟研究

The Simulation of CH_(4) Gas Change in CO_(2) Flooding Coal Body

CO_(2)驱替煤层CH_(4)作为一种降低煤矿开采过程中CH_(4)爆炸事故风险的手段,若能进一步提升驱替效率,对于保障煤矿开采人员生命安全具有重要意义。因此,针对CO_(2)驱替煤层CH_(4)效率不高、操作困难的难题,本文采用COMSOL 6.0模拟不同注气压力和渗透率下CO_(2)驱替煤层CH_(4)的过程,通过对比分析不同注气压力和不同渗透率下CO_(2)驱替煤层CH_(4)时煤体内部的气体变化情况可知,当CO_(2)注气压力增加后,其气体在煤体内部的运移速度也会随之增加,同时使得驱替煤体内部的CH_(4)也随之增加,进而达到减缓过程中速度损失的目的;而当煤体渗透率下降时,则会导致气体运移速度的大幅度损耗。通过模拟煤体内部的气体变化规律,对减少煤层CH_(4)含量,防止开采过程中发生因CH_(4)过量而导致爆炸事故具有参考意义。

CO_(2) displacement of CH_(4) in coal seam is a means to reduce the risk of CH_(4) explosion accident in the process of coal mining.If displacement efficiency can be further improved,it is of great significance to ensure the life safety of coal miners.Therefore,aiming at the problems of low efficiency and difficult operation of CO_(2) displacement CH_(4) in coal seam,COMSOL6.0 was adopted in this paper to simulate the process of CO_(2) displacement CH_(4) in coal seam under different gas injection pressures and permeability,and the gas changes in coal body during CO_(2) displacement CH_(4) in coal seam under different gas injection pressures and different permeability were comparatively analyzed.It can be seen that the increase of CO_(2) gas injection pressure can significantly increase the migration rate of gas in coal body and the efficiency of coal seam CH_(4) displacement,and effectively reduce the velocity loss caused by gas in the migration process.As the permeability of coal decreases,the difficulty of gas migration and displacement will increase,and the loss of gas migration speed will increase.The simulation of gas change in coal body has reference significance for reducing CH_(4) content in coal seam and preventing explosion accidents caused by excessive CH_(4) in mining process.