不同瓦斯抽采钻孔封孔工艺封孔效果的现场试验对比研究

Field test and comparative study on sealing effect of different gas drainage borehole sealing technology

为了考察不同封孔工艺在低渗透煤层中的瓦斯抽采效果,通过现场瓦斯抽采试验,对比分析了传统封孔、自胀式封孔、袋装封孔、封孔器封孔以及主动承压式封孔5种封孔工艺的钻孔瓦斯浓度变化特征,介绍了主动承压式封孔工艺的工艺原理。结果表明:主动承压式封孔工艺的钻孔瓦斯浓度在抽采初期呈上升趋势,随后缓慢降低并稳定在70%左右,钻孔瓦斯浓度出现显著衰减的时间为70~80d,高瓦斯浓度抽采的时间长达91d,远高于相同条件下采用其他封孔工艺的抽采钻孔;此外,采用该封孔工艺的钻孔瓦斯浓度自孔底向孔口仅衰减14%,为各类封孔工艺中瓦斯浓度衰减最低的封孔方式。综合对比各类封孔工艺下抽采钻孔瓦斯浓度变化特征、瓦斯浓度显著衰减时间和高浓度瓦斯持续抽采时间等指标,采用主动承压式封孔工艺可以取得良好的瓦斯抽采效果。

In order to investigate the gas drainage effect of low-permeability coal seams with different sealing processes,the traditional gas sealing and self-expanding sealing,bag sealing,sealing and sealing are carried out through on-site gas drainage test.The variation of gas concentration in boreholes under five kinds of sealing methods of pressure-sealing were mainly introduced to the process principle of active pressure-sealing sealing process.The results showed that the gas concentration of drilling gas in active pressure-sealing sealing process was in the extraction.Initially,and it showed an upward trend,then slowly decreased and stabilized at around 70%.The time for significant attenuation of borehole gas concentration was about 70~80 d,and the extraction time of high gas concentration was as long as 91 d,much higher than other conditions under the same conditions.The drilling hole of the sealing process,in addition,the gas concentration of the drilling hole using the sealing process was only attenuated by 14%from the bottom of the hole to the orifice,which was the sealing method with the lowest attenuation of gas concentration in various sealing processes.Comprehensive comparison of various types of sealing technology,gas concentration variation characteristics,significant gas concentration reduction time and high concentration gas continuous extraction time and other indicators,the use of active pressure sealing method can achieve good gas drainage effect.