垂直对称轴的横向各向同性介质中Thomsen参数对相速度和群速度的影响

The Influence of Thomsen Parameter on Phase Velocity and Group Velocity in VTI Media

相速度和群速度对于研究弹性波在各向异性介质中的传播具有重要意义;同时对合理评价地震资料解释成果也具有一定的指导意义。深入研究Thomsen参数与群、相速度的关系有助于研究复杂地层中波的传播规律以及速度的变化趋势,从而使地震资料解释更加准确。首先简要推导了各向同性(VTI)介质中弹性波的群、相速度解析表达式,然后通过编程实现,直观显示了三维速度曲面的变化特征与Thomsen参数的联系;并通过二维及一维速度曲线变化加以验证。实验结果表明:VTI介质中群速度较相速度对Thomsen参数的变化更加敏感;其中随着ε(q P波各向异性强度表征参数)与δ(描述纵横波相速度的过渡性参数)差值的不断增大,各向异性程度明显增强,群速度剧烈变化;尤其是q SV波;随着γ(横波分裂强度表征参数)值的不断增大,SH波群、相速度面的扁率也不断增大。

Phase velocity and group velocity are important for studying the propagation of elastic waves in anisotropic media,and also for guiding the reasonable evaluation of seismic data interpretation results. Further study of the relationship between Thomsen parameters and group velocity and phase velocity is helpful to study the wave propagation and the trend of velocity change in complex strata,so as to make seismic data interpretation more accurate. The analytical expression of group velocity and phase velocity of elastic wave in VTI media were firstly deduced,and then it is realized by programming. The relationship between the change features of the 3 D velocity and surface and the Thomsen parameters are displayed directly,and the change of the two-dimensional and one-dimensional velocity curves is verified. The experimental results show that the group velocity of elastic wave in VTI media is more sensitive to the phase velocity of the Thomsen parameters. With ε（ q P anisotropic strength parameters） andδ（ description of transitional horizontal parameter wave phase velocity） increasing difference,the degree of anisotropy increased,group velocity changes,especially the q SV wave. With γ（ shear wave splitting parameter strength）increases,surface flattening of SH wave phase velocity and group velocity increasing.