西沟煤矿注CO2促抽煤层瓦斯模拟研究

为了提高瓦斯抽采效果，以西沟煤矿5315工作面注气瓦斯抽采方案为工程背景，开展注CO₂促抽煤层瓦斯模拟研究。通过对注CO₂驱替煤层瓦斯机理研究，结合注气瓦斯抽采过程中的气体运移场和煤体变形场的耦合关系，建立了注CO₂促抽瓦斯固气耦合模型；利用COMSOL Multiphysics软件模拟了工作面注气瓦斯抽采，对比分析了注气瓦斯抽采与本煤层顺层钻孔抽采的瓦斯抽采效果，论证了煤层注CO₂促抽煤层瓦斯工艺的可行性与有效性。研究结果表明:在工作面瓦斯抽采90 d后注入CO₂，对瓦斯抽采的促抽效果明显，煤层瓦斯压力降至0.46~0.49 MPa，瓦斯含量降低至4.22 m3/t；在90 d后注入CO₂促抽煤层瓦斯，在瓦斯抽采至第180 d时，抽采效果较钻孔瓦斯抽采明显提高，煤层瓦斯压力降低了7.84%~9.26%，残余瓦斯含量减少了18.63%。通过工程实测可知，5315工作面在注入CO₂促抽煤层瓦斯抽采后的瓦斯压力与瓦斯含量分别降低至0.48 MPa和4.76 m3/t，有效降低了煤与瓦斯突出的危险性。

Simulation study of coal seam gas extraction promoted by CO2 injection in Xigou coal mine

In order to improve the effect of gas extraction, the CO₂ injection and gas extraction scheme of No. 5315 working face in Xigou coal mine was used as the engineering background to carry out the simulation study of coal seam gas extraction promoted by CO₂ injection. Through studying the mechanism of CO₂ injection displacing the gas in coal seam, and combining the coupling relationship between gas migration field and coal body deformation field during the process of CO₂2 injection and gas extraction, a solid gas coupling model of CO₂2 injection for promoting gas extraction was established. The COMSOL Multiphysics software was used to simulate the CO₂ injection and gas extraction in the working face, then the gas extraction effect of gas extraction with CO₂ injection and borehole extraction along the coal seam were compared, and the feasibility and effectiveness of the technology of CO₂ injection in coal seam to promote the coal seam gas extraction were verified. The results showed that when implementing the CO₂ injection after 90 days of gas extraction in the working face, the effect of promoting the gas extraction was significant. The gas pressure in the coal seam decreased to 0.46-0.49 MPa, and the gas content decreased to 4.22 m3/t. In case of implementing the CO₂ injection after 90 days to promote the coal seam gas extraction, when the gas extraction was carried out on the 180th day, the gas extraction effect was significantly improved compared with that of borehole gas extraction. The gas pressure in coal seam reduced by 7.84%-9.26%, and the residual gas content reduced by 18.63%. The engineering measurement results showed that the gas pressure and gas content of 5315 working face after CO₂ injection to promote the coal seam gas extraction decreased to 0.48 MPa and 4.76 m3/t respectively, which effectively reduced the risk of coal and gas outburst.