基于P-SV波分离的VTI介质射线追踪方法

A New Ray Tracing Method for VTI Medium Based on Separated P-SV Waves

近年来,VTI介质参数建模和成像技术发展迅速,其中VTI介质射线追踪是基础,其精度和稳定性直接影响建模和成像的效果。VTI介质射线追踪大多通过前人提出的频散关系推导出程函方程和射线方程,该方法主要基于纵横波相互独立的假设,采用令横波速度等于零的手段,在某些特殊情况下精度较低、稳定性较差。针对其缺点提出一种新的射线追踪方法,该方法基于P-SV波分离得到的q P波频散关系,从而推导出程函方程和射线方程,提高了精度和稳定性。最后通过模型试算验证该方法的正确性和稳定性。

In recent years,modeling and imaging techniques for VTI medium have developed rapidly. Ray tracing in VTI medium is the key issue,whose precision and stability directly affect the results of modeling and imaging. Ray tracing in VTI medium is usually based on the eikonal equation and ray equation derived from the dispersion relation of Alkhalifah（ 2000）. The assumption is that the P wave and S wave are independence,and the velocity of S wave is zero. Thus,in some particular cases,this method is lack of accuracy and stability. In this paper,a new ray tracing method was proposed to overcome this problem. We separated P-SV waves to get the phase velocity of the q P wave,and then to get the eikonal equation and ray equation of q P wave,through which the precision and stability were improved. At the end,numerical tests were made to prove the effectiveness of this method.