温度和围压耦合作用下煤样渗透率变化的试验研究

Experiment study on permeability variation of coal samples under coupling effect of temperature and confined pressure

为了探究不同温度和围压耦合影响下的煤样渗透率变化特征,选用甘肃新北矿区低变质程度的烟煤,采用实验室试验的方法,借助Quanta TM 250扫描电子显微镜、Auto Pore IV 9500全自动压汞仪、Autosorb-1型全自动比表面和孔径分布分析仪,对煤样的内外部孔隙特征进行了测试分析;采用自主搭建的瓦斯渗流测定装置,对不同温度和围压耦合条件下的原煤瓦斯渗流进行了测定。结果表明:在试验采用的温度、围压变化范围(25~80℃,3~9 MPa)内,所测得的16组煤样渗透率均表现出了较强的温度、压力敏感性,围压对渗透率的影响明显高于温度对渗透率的影响;随着温度和围压的增大,渗透率呈减小趋势,而且减小趋势逐渐放缓,变化符合幂函数关系;温度与围压耦合时对煤样渗透率的影响显著,渗透率的变化服从指数分布。

In order to explore the permeability variation features of the coal samples under the coupling influences of the different tempera- ture and the confined pressure, a low metamorphic degree anthracite coal from Gansu Xinbei Mining Area were selected. With the assis- tances of the QuantaTM 250 scanning electron microscope （SEM） , AutoPore IV 9500 full automatic mercury intrusion porosimet,7 and Autosorb-1 type full automatic specific surface and pore size distribution analyzer,a lab test method was applied to the test and analysis on the internal and external pore features of the coal samples. A self established gas seepage measuring device was applied to measure the gas seepage of the raw coal under the coupling condition of the different temperature and confined pressure. The results showed that within the variation range of the temperature and confined pressure （25- 80 ℃ ,3- 9 MPa） applied to the test,the permeability measured of 16 groups samples in average showed the high sensitivity of the temperature and pressure and the confined pressure affected to the permeability was higher than the temperature affected to the permeability. With the temperature and confined pressure increased, the permeability would be reduced in a tendency and the variation could meet the power function relationship. The coupling of the temperature and confined pressure would be obviously affected to the permeability and the variation of the permeability would obey the index distribution.