瓦斯强化抽采技术是局部瓦斯治理的有效措施，为提高抽采衰竭期工作面的瓦斯抽采效果，基于流体力学理论分析了抽采衰竭期瓦斯抽采量下降原因，提出了抽采衰竭期注气增压强采欠压瓦斯技术，分析了技术作用机理、理论模型并开展了相关现场试验。研究结果表明：随着抽采过程中瓦斯压力的逐步降低，煤层瓦斯进入欠压状态，流动的驱动力不足，抽采进入衰竭期；注气增压强采技术具有“促流”、“增透”和“置换”的三重效果；推导了注气强采二元气体对流数学模型，以模型为基础进行了定量化注气强采效果数值计算；澳大利亚Sydney Basin的现场试验表明注气强采能够迅速提升抽采瓦斯混合量与纯量，注气期间瓦斯含量减少量为5.28 m3/t，降幅73.90%，常规抽采期间瓦斯含量减少量为2.93 m3/t，降幅39.1%。结果表明，与常规抽采相比较，注气强采能更有效提高煤层瓦斯抽采效果，实现欠压煤层的快速强采，减少了煤炭开采过程中的煤与瓦斯突出危险性及瓦斯异常涌出可能性。

Enhanced gas drainage technology is an effective measure for local gas control, in order to improve the gas drainage effect at the working face during the exhaustion period, the reason of the decrease of gas drainage flow during drainage exhaustion period was analyzed based on fluid mechanics. Periodic gas injection, pressurization and strong production of underpressure gas technology was proposed in this paper. Its mechanism, theoretical models and field trials are studied. The research results show that with the gradual reduction of gas pressure in the coal seam, the driving force for gas flow is insufficient and the drainage enters the exhaustion period. The gas injection pressurization and strong mining technology has the advantages including “promoting flow”, “increasing permeability” and “gas replacement”. A binary gas convection mathematical model for gas injection and forced production is derived. Based on the model, the effect during gas injection and methane recovery is analyzed quantitatively through numerical simulation. Through on-site trials in the Sydney Basin in Australia, it is found that gas flushing can rapidly increase the mixed volume and scalar of the extracted gas.During the gas injection, the gas content is reduced by 5.28 m3/t, a decrease of 73.90%, and the reduction of gas content during conventional drainage was 2.93 m3/t, a decrease of 39.1%. The results show that, compared with conventional drainage, gas injection can improve the coal seam gas drainage effect more effectively, and realize the rapid and strong extraction of the underpressured coal seam, and reduce the risk of coal and gas outburst possibility and methane emission rate.  

0 引言

1 常规抽采的煤层瓦斯流动原理

2 注气增压强采欠压瓦斯原理

3 注气强采二元气体对流数学模型

4 现场应用

5 结论