基于互相关成像条件的VTI介质保幅高斯束逆时偏移

Amplitude-preserving reverse time migration with Gaussian beams for VTI media based on cross-correlation imaging conditions

保幅高斯束逆时偏移是一种兼具高斯束偏移灵活、高效和逆时偏移高精度特性的深度域成像算法,不仅能够消除偏移过程中由于入射角变化和几何扩散引起的振幅误差,而且具有面向目标成像的能力。其以Kirchhoff积分为基础,采用高斯束的加权积分来构建格林函数,进而实现正反向波场的延拓,最后通过相应的成像条件进行成像。这里从基于相速度的各向异性射线追踪算法出发,采用互相关成像条件,将保幅高斯束逆时偏移推广到VTI介质。随后通过模型试算对方法的正确性和有效性进行了验证。

Amplitude-preserving reverse time migration with Gaussian beams is a depth-domain imaging algorithm that combines the flexibility,high efficiency of Gaussian beam migration,and the accuracy of reverse time migration.It can not only eliminate amplitude errors caused by incident angle changes and geometric diffusion during migration,but also has the ability to target imaging.This method,based on Kirchhoff integral,uses Gaussian beam weighted integral to construct Green function,and then realizes continuation of forward and backward wave field,and finally imaging by corresponding imaging conditions as well.In this paper,starting from an anisotropic ray tracing algorithm based on phase velocity,the cross-correlation imaging conditions are adopted to extend the amplitude-preserving reverse time migration with Gaussian beams to VTI media.Subsequently,the correctness and effectiveness of the method were verified by model trial calculation.