高瓦斯厚煤层顺层钻孔有效抽采区及参数优化研究

    Effective drainage area and parameter optimization of bedding drilling in high gas and thick coal seam

    • 摘要: 为研究顺层抽采时不同参数对高瓦斯煤层抽采效果的影响,以Fick扩散、Darcy定律、理想气体状态方程和Langmuir方程为基础,结合煤体的裂隙-孔隙双重孔隙介质结构、瓦斯和水的运移特性,建立了瓦斯-水的气水两相流的流-固耦合数学模型;利用COMSOL Multiphysics软件对漳村煤矿3# 煤层顺层抽采进行数值模拟研究。结果表明:在一定范围内钻孔直径越大,抽采效率越高;抽采负压变化对瓦斯有效抽采区域和瓦斯压力变化的影响非常微弱,对抽采效率的提升不大;减小钻孔间距可以有效提高抽采效率,但并不是钻孔间距越小越好;在抽采初期,各钻孔的有效抽采区域处于相互独立状态,随着抽采进程,各钻孔有效抽采区域逐渐增大并与相邻钻孔的有效抽采区域汇合叠加,形成整体有效抽采区域;当要求抽采100 d内达标时,漳村煤矿3# 煤层单排布孔最佳方案为钻孔直径94 mm、抽采负压20 kPa、钻孔间距3 m。

       

      Abstract: In order to study the effect of different parameters on drainage effect of bedding drilling in high gas coal seam, based on Fick diffusion, Darcy’s law, ideal state gas equation and Langmuir equation, the flow-solid coupled mathematical model of gas-water two-phase flow of gas-water were established by combining the fracture-pore dual pore medium structure of coal mass and the transport characteristics of gas and water. The COMSOL Multiphysics software was employed to conduct a numerical simulation study on gas extraction of the 3# coal seam in Zhangcun Coal Mine. The results present that the larger the drill hole diameter in a certain range, the higher the extraction efficiency will be. The effect of the change of negative extraction pressure on the effective area of gas extraction and the change of gas pressure is significantly weak and the improvement of gas extraction efficiency is not much. Reducing the spacing between boreholes can effectively improve the extraction efficiency, however it is not the case that the smaller the spacing between boreholes, the better effect will be. In the early stage of extraction, the effective extraction area of each drill hole is independent. As the extraction progresses, the effective extraction zone of each drill hole gradually increases and is superimposed on the effective extraction zone of adjacent drill holes to form an overall effective extraction zone. When it is required to reach the standard within 100 days of extraction, the optimal plan for single hole arrangement of 3# coal seam in Zhangcun Coal Mine is 94 mm in diameter, 20 kPa in negative extraction pressure and 3 m in spacing.

       

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