断层对煤层槽波传播特性影响分析

断层是煤系地层中常见的异常构造之一,对断层形态的研究,有利于提高探测断层的精度。基于弹性波动理论,建立三维煤系地层模型,采用有限元数值模拟方法,分析了断层断距和倾角对槽波传播特性的影响。通过对比各模型槽波记录和时频谱得出:随着断距和倾斜角的增大,断层对槽波的阻断作用增大;对于2m厚的煤层来说,当存在1.5m的断层时,断层后槽波能量峰值频率向高频移动,出现时间提前,当存在2.5m的断层时,断层后槽波能量峰值向低频移动,出现时间延后;随着倾斜角的增大,断层后的波主频向低频移动,主频出现时间延后;对于0.5m的断层,不易判断断层位置。模拟结果可为断层形态槽波探测提供理论支持,对槽波精细探测和信号解释有重要意义。

Analysis of the influence of faults on the channel wave propagation characteristics of coal seam

Fault is one of the common abnormal structures in coal measure strata. The study of fault geometry is an effective method to improve the accuracy of fault detection. Based on the elastic wave theory, a 3D coal-bearing strata model is established, and the finite element numerical simulation method is used to analyze the influence of fault throw and dip on the channel wave. From the record of channel waves and the time-frequency spectrum, it can be seen that the blocking effect of fault on channel wave increases with the increase of fault distance and inclination. For channel waves after fault, when there is a fault less than coal thickness, with the increase of fault distance, the frequency of the peak energy is higher, and the occurrence time is advanced. When there is a fault larger than the coal thickness, the frequency of the peak energy is lower, and the occurrence time is delayed. With the increase of the fault inclination, the main frequency is lower, and the occurrence time is delayed. It is not easy to judge the fault location for faults less than 1/2 coal thickness. The results can provide theoretical support for the detection of fault geometry, and are of great significance for the precise detection and signal interpretation of channel wave.