低透高吸附煤层大孔径钻孔预抽瓦斯技术及应用

Application of large borehole pre-extracting gas technology in low permeability and high adsorption coal seams

矿井瓦斯是煤矿五大灾害之首,瓦斯抽采是瓦斯治理最行之有效的手段,而对于低透气、高吸附特性煤层的瓦斯治理难度相对较大。采用现场实测的方法得到了建新煤矿4304工作面透气性系数以及百米钻孔瓦斯流量衰减系数,基于煤层特性依据抽采半径参数分析制定了大孔径钻孔预抽煤层瓦斯的方案,实现了较好的瓦斯治理效果。建新煤矿百米钻孔瓦斯流量衰减系数为0.032,4-2煤层透气性系数为0.506,煤层属于低透气性煤层,通过实施低透气高吸附煤层大孔径长距离钻孔预抽瓦斯技术,综放工作面回采期间隅角瓦斯浓度介于0.14%~0.39%,回风流瓦斯浓度介于0.12%~0.17%,实现了该工作面安全高效生产。

Mine gas is the top five major disasters in coal mines,and gas extraction is the most effective means of gas control.The difficulty of gas control in low permeability and high adsorption coal seams is relatively increased.We use on-site measurement methods to obtain the permeability coefficient and gas flow attenuation coefficient of the 4304 working face of Jianxin Coal Mine.Based on the characteristics of the coal seam and the analysis of the extraction radius parameters,a plan for pre-extraction of coal seam gas through large aperture drilling has been developed with good gas control effects.The gas flow attenuation coefficient of the 100 meter borehole in the mine is 0.032,and the permeability coefficient of the 4-2 coal seam is 0.506.The coal seam belongs to a low permeability coal seam.By implementing the technology of pre-extraction of gas through large-diameter and long-distance drilling in low permeability and high adsorption coal seams,the gas concentration in the corners of the fully mechanized top coal caving face during mining is between 0.14%and 0.39%,and the gas concentration in the return air flow is between 0.12%and 0.17%,achieving safe and efficient production in the face.