本煤层二氧化碳深孔预裂爆破驱气增透机理及参数优化研究

The complex storage of coal and the coal seams features such as high content, large pressure, and low permeability, which seriously affects the gas extraction of the coal seam in our country. The CO2 dioxide deep-hole pre-splitting blasting is a new type of enhanced increasing permeability technology that uses the mechanism of gas phase transformation fracturing. And it has the advantages of no spark, controllable power, and easy operation during fracturing. The project adopted a comprehensive analysis method to study the mechanism of CO2 Deep-hole pre-split blasting and purging increasing permeability in the coal seam. Firstly, the self-developed CO2 presplit blasting experimental platform was used to analyze the law of crack propagation combine with ultrasonic testing and VIC-3D observation system, and built a model of blast wave effect on the crack propagation; Secondly, analyze the crack propagation law of coal, establish the stress wave of stress-environmental stress-gas pressure coupling crack propagation mechanics model by a self-developed multi-factor blasting experimental system; Based on these researches, analyze the mechanism of displacing the gas in the process of CO2 pre-splitting blasting under coupling and introduce the model into COMSOL performing numerical analysis. Finally, the field parameters are used for optimizing the blasting parameters, correcting the theoretical model and verifying numerical analysis. The research results can provide a theoretical basis for pre-elevating gas in the coal seam, and it is of great significance for gas drainage in low-permeability coal seams.

我国煤炭资源赋存复杂，煤层普遍具有瓦斯含量高、瓦斯压力大、渗透率低等特点，严重影响本煤层瓦斯抽采。其中二氧化碳深孔预裂爆破为一种利用气体相变原理对煤层进行致裂的新型强化增透技术，具有致裂过程中不产生火花，威力可控和操作便捷等优点。项目采用综合分析方法对本煤层二氧化碳深孔预裂爆破驱气增透机理进行研究。首先，利用自主研发的二氧化碳预裂爆破实验平台，采用超声检测及VIC-3D观测系统分析裂隙扩展规律，建立爆破应力波对煤体裂隙扩展力学模型；其次，利用自主研发多因素爆破实验系统，分析煤体裂隙扩展规律，建立爆炸应力波-围岩应力-瓦斯压力耦合裂隙扩展力学模型；在此基础上分析耦合作用下二氧化碳预裂爆破过程驱替增透瓦斯机理，并将上述模型导入COMSOL软件进行数值分析；最后，采用现场实验的方法对爆破参数进行优化，对理论模型及数值分析进行验证。该研究成果可为矿井本煤层预抽瓦斯提供理论基础。

我国煤炭资源赋存复杂，煤层普遍具有瓦斯含量高、瓦斯压力大、渗透率低等特点，严重影响本煤层瓦斯抽采。其中二氧化碳深孔预裂爆破为一种利用气体相变原理对煤层进行致裂的新型强化增透技术，具有致裂过程中不产生火花，威力可控和操作便捷等优点。项目采用综合分析方法对本煤层二氧化碳深孔预裂爆破驱气增透机理进行研究。首先，利用自主研发的二氧化碳预裂爆破实验平台，采用超声检测及VIC-3D观测系统分析裂隙扩展规律，建立爆破应力波对煤体裂隙扩展力学模型；其次，利用自主研发多因素爆破实验系统，分析煤体裂隙扩展规律，建立爆炸应力波-围岩应力-瓦斯压力耦合裂隙扩展力学模型；在此基础上分析耦合作用下二氧化碳预裂爆破过程驱替增透瓦斯机理，并将上述模型导入COMSOL软件进行数值分析；最后，采用现场实验的方法对爆破参数进行优化，对理论模型及数值分析进行验证。该研究成果可为矿井本煤层预抽瓦斯提供理论基础。