超声波作用下煤中甲烷的渗流特性

Seepage Characteristics of Methane in Coal under Ultrasonic Wave

摘要: 为了提高煤的渗透率，采用自主研发的超声波作用下煤层气渗流实验系统研究了超声波作用时间、功率对甲烷渗流特性的影响。实验得出：超声波作用前后煤的渗透率随平均有效应力、有效轴压的增加而迅速减小，呈负指数关系；当应力恒定时，随着时间的增加，超声波作用下煤的渗透率明显增加，后趋于稳定；当超声波频率为25 kHz时，随着功率的增加，煤体裂隙的扩展范围增大，煤的渗透率增加，且超声波作用后渗透率与功率呈线性关系；超声波提高煤的渗透率是空化效应、机械作用和热效应共同作用的结果。

Abstract: In order to improve the permeability of coal, the seepage characteristics of coalbed methane under different treatment time and power of ultrasonic wave were studied by the self-developed experi-mental system of coalbed methane seepage under ultrasonic wave. The results show that the per-meability of coal decreases rapidly with the increase of the average effective stress and the effective axial pressure before and after the ultrasonic treatment, which shows a negative exponential rela-tion. When the stress is constant, the permeability of coal increases significantly with time, and then tends to be stable. As the ultrasonic frequency is 25 kHz, the expansion area of cracks increase and the permeability of coal increases with the increase of ultrasonic power. And the ratio of permeabil-ity before and after ultrasonic treatment is linear with ultrasonic power. The permeability of coal increased by ultrasonic wave is the result of cavitation effect, mechanical effect and thermal effect.