煤渗透特性及其气体压力敏感性试验研究

Experimental research on the gas pressure sensitivity to the permeability of coal

为探索煤中孔隙流体压力的变化导致渗透率的改变,引发煤渗透率压力敏感性现象,利用自主研发的出口端压力可调的三轴渗流装置,对贵州3个矿区的煤开展不同吸附性气体与不同气体压力下煤的敏感性试验研究。研究结果表明:在较低气压范围内(0~0.6 MPa),随气体压力的增加,煤渗透率下降明显,当气体压力继续上升煤的吸附作用逐渐趋于平衡,煤体骨架的吸附膨胀变形也越来越小,渗透率的下降速率逐渐减少并趋于平缓。在气体压力小于1.0 MPa时,煤渗透率损害率Dp变化较大,且随气体压力增加快速增大,表现出较强的压力敏感性。不同吸附性气体条件下,气体压力指数关系敏感系数Cp均随气体压力的增加而逐渐减小,煤渗透率对气体压力的敏感性降低。对于同一煤,在相同的条件下,CH4的气体压力乘幂关系敏感系数Sp的值最小,煤对气压的敏感性越差。乘幂关系的气体压力敏感系数Sp与渗透率损害率Dp有很好的线性相关性。

In order to explore the gas pressure changes caused changes of permeability of coal, leading to the phenomenon of pressure sensitivity. Using the self-developed triaxial seepage equipment with an adjustable outlet pressure,the experimental study of permeability sensitivity of coal sample from 3 mines in Guizhou province under different gases and gas pressure was performed. The results are show that at the lower pressure range （0-0.6 MPa）,the permeability decreases significantly when gas pressure increases, the adsorption of coal tends to balance and the rate of descent reduced and leveled off with the rising of gas pressure. When the gas pressure is less than 1.0 MPa, the damage rate of permeability Dp has a great change,and it increases rapidly showed a significant sensitivity. Under the different gases condition, the sensitiveness coefficient of gas pressure Cp decreases when the gas pressure increases. The sensitiveness coefficient of gas pressure Sp is minimum when filling CH4 under the same condition. The sensitiveness coefficient of gas pressure has the power relationship Sp and damage rate of permeability Dp has a better linear correlation.