裂隙对煤岩超声波速度影响的实验——以沁水盆地石炭系煤层为例

Experiment of influence of fractures on coal/rock acoustic velocity:with Carboniferous seams of Qinshui basin as example

对沁水盆地煤岩样品进行模拟煤层埋藏压力条件下的多方位超声波速度测试,研究煤岩中裂隙对超声波速度的影响,进而对地下裂隙进行预测,有利于煤层气的勘探开发。分析结果表明:煤岩中的裂隙会导致超声波速度降低,但当围压增大到10 MPa以后,大部分裂隙被压密闭合,煤岩的超声波速度趋于稳定;裂隙的方位对超声波在煤岩中的传播速度产生一定的影响,平行裂隙方向,超声波传播速度最大,垂直裂隙方向,超声波传播速度最小。研究成果为预测煤层中的裂隙提供了基础资料。

In order to study the impact of fractures on the ultrasonic velocity, multi-azimuth ultrasonic velocity of coal were tested under the pressure similar to buried stratum in Qinshui basin. The experimental results shows that： （1） Fractures will reduce ultrasonic velocity, but when the confining pressure increases to 10 MPa, most of frac- tures are closed together, the velocity comes table; （2）orientation of fractures makes certain impact on acoustic propagation velocity. Along the fracture direction, slowest perpendicular to the fracture directinn This acoustic wave goes the fastest, acoustic wave propagates the