氮气闷压对高阶煤渗透率影响的试验研究

Experimental study on the influence of nitrogen soaking on the permeability of high rank coal

为了探讨煤层气注氮过程中的闷压压力和时间对七元高阶煤层渗透率的影响规律,采用试验模拟注氮改造煤层过程的闷压阶段的研究方法,设计并组装了相关室内试验装置和设备,再现了氮气闷压过程中闷压压力和闷压时间的变化对七元高阶煤样的影响,获得了不同闷压压力和闷压时间条件下七元高阶煤样渗透率的变化。试验结果表明:在注氮改造煤层过程的闷压阶段,闷压压力越大,煤样渗透率增幅越大;闷压时间存在一个最佳值:闷压初期煤样渗透率增幅随着闷压时间增长而增大,在闷压48～72 h后,煤样渗透率增幅会存在一个急剧下降的过程。因此,提高注氮闷压压力对提高高阶煤层渗透率有着积极的影响,闷压时间对提高高阶煤层渗透率的影响则存在一个最佳值。

In order to study the influence of soaking pressure and soaking time on the permeability of Qiyuan high-rank coal seam during nitrogen injection,the experimental method that simulating the soaking stage of nitrogen injection was adopted,and the related laboratory experimental equipment were designed and assembled,which reproduced the soaking pressure and soaking time on the permeability of Qiyuan high-rank coal seam during nitrogen injection. The variation on the permeability of Qiyuan high-rank coal samples was obtained under different soaking pressure and soaking time. The experimental results show that the permeability of coal sample increases with the increasing of the soaking pressure in the soaking stage of the nitrogen injection process,and there is an optimum value of soaking time: the increase of permeability of coal sample increased with the increase of soaking time in the initial soaking stage,and there would be a sharp decline in the increase of permeability of coal sample after a certain time( 48 ~ 72 hours). Therefore,increasing the pressure of nitrogen injection has a positive impact on improving the permeability of high-rank coal seams,and there is an optimum soaking time.