煤层水力造穴钻孔含水特征及对抽采瓦斯浓度的影响研究

Research on Water-bearing Characteristics of Coal Seam Hydraulic Cavitation Borehole and Its Influence on Gas Drainage Concentration

煤层水力造穴增透技术是低渗松软煤层十分有效的“增透-增流”方法之一,但受外侵水浸润与积存等影响,水力造穴钻孔抽采瓦斯参数具有明显的分区分布特征。为此,通过图示法分析钻孔积水积煤状态,利用钻孔成像轨迹仪现场观测水力造穴钻孔内含水特征,在此基础上跟踪测定不同钻孔倾角条件下的水力造穴施工钻孔抽采瓦斯参数。分析及观测结果表明,钻孔造穴处具有明显的积水积煤现象,其体积可达造穴空间的1/3以上;同时,钻孔倾角对水力造穴钻孔瓦斯抽采参数影响较大,呈现典型的“高流量、低浓度”现象;此外,受外侵水作用影响,抽采瓦斯浓度呈现“先增后减”的分布规律。研究结果可为煤层水力造穴增透技术施工参数的合理选择,提供科学的借鉴。

Coal seam hydraulic cavitation permeability enhancing technology is one of the very effective"increasing permeability-increasing flow"methods for low-permeability soft coal seams.However,due to the influence of external water infiltration and accumulation,the gas drainage parameters of hydraulic cavitation boreholes have obvious characteristics of regional distribution.To this end,analyze the state of water and coal accumulation in boreholes by graphical method,and use borehole imaging tracker to observe the water content characteristics of hydraulic caverns on site,and on this basis,track and determine gas drainage parameters of hydraulic cavitation construction boreholes under different borehole inclination conditions.On this basis,hydraulic cavern construction drills under different borehole dip angles were tracked and measured.The analysis and observation results show that there is obvious water and coal accumulation in the hydraulic cavitation,and its volume can reach more than one-third of the hydraulic cavitation space.At the same time,the hole inclination has a great influence on the gas drainage parameters of the hydraulic cavitation boreholes,showing a typical phenomenon of high flow and low concentration.In addition,due to the effect of external water intrusion,the gas concentration of the extracted gas presents a distribution law that first increases and then decreases.The research results can provide a scientific reference for the reasonable selection of construction parameters of the coal seam hydraulic cavitation permeability enhancing technology.