岩石非均匀性对超声衰减的影响及其修正

The Effect of Heterogeneity on Rock's Ultrasonic Attenuation and Its Correction

在充分考虑了岩石的非均匀性引起的Rayleigh散射对衰减测量值的影响后 ,通过有关理论和计算 ,将岩石的本征衰减和散射加以区分 ,对原先以均匀介质为基本假定的频谱比法进行了修正。改进后的频谱比法可在较宽的频率范围内进行Q值计算 ,避免了传统频谱比法在不同频段上得出不同的Q值的不确定性问题。同时 ,我们还引进并改进了频率移动法。我们将传统和改进的频谱比法、以及频率移动法应用于同一套实验数据 ,计算结果符合较好。

The effect of Rayleigh scattering caused by the heterogeneity of rocks, on attenuation measurement has been considered adequately. According to the related theory and calculation, we can distinguish the intrinsic attenuation from the scattering attenuation. And we amended the classic spectral ratio method, which based on the homogeneous medium hypothesis. Using the improved spectral ratio method, we can obtain Q value within a wide frequency range, so we can eliminate the uncertainty condition in classic spectral ratio, that Q value depends on the frequency range. The frequency shift method has been introduced and improved. Those three methods on one set of data had been applied. The results of classic and improved spectral ratio and frequency shift fit well.