任意空间取向TI介质中速度随方位变化特征

The characteristics of velocities with azimuth variation for arbitrary spatial orientation TI media

本文基于任意空间取向TI介质中坐标变换的方法,扩展研究了任意强弱、具有任意空间取向对称轴的TI介质中体波相速度和群速度的方位变化;通过模型数值计算,获得了相速度与群速度方位变化图案,并比较了二者偏差.研究发现,各向异性越强群速度与相速度的偏差越大;并且,TI对称轴的空间取向和测线方位影响速度方位变化.相对于TI对称轴,速度方位变化图案不变;但是,随着TI对称轴空间取向和测线方位的改变,其速度方位变化呈现一定的规律性.研究结果可以精确地预测任意空间取向TI介质中速度方位变化,有利于地震各向异性数据处理与解释.

Based on the method of coordinates transform for arbitrary spatial orientation TI media, we expanded to study the azimuth variations of body-wave phase-velocity and group-velocity for arbitrary spatial orientation TI media with arbitrary strength of anisotropy. Using simulating calculation, we obtained the patterns of phase-velocity and group-velocity, and analyzed the deviation between group-velocity and phase-velocity. This research illustrates that the stronger is anisotropy the larger is the deviation between group-velocity and phase-velocity. The spatial orientation of TI symmetry axis and surveying line azimuth has the effect on the azimuth variation of body-wave velocities. The patterns of body-wave group-velocity and phase-velocity are fixed relative to TI symmetry axis, and exhibit certain symmetry and repetition with azimuth variation. This result can be directly predicted the azimuth variation of bodywave velocities for arbitrary spatial orientation TI media. Hence, this research benefits the data processing and interpretation of seismic anisotropy.