多分量联合逆时偏移最佳匹配层吸收边界

有限空间内的波动方程逆时偏移需要利用有效的边界处理技术用以消除人工截断对偏移结果产生的影响。本文以横向各向同性介质弹性波速度-应力方程为基础,依据传统分裂式最佳匹配层（Perfect Matched Layer,PML）吸收边界技术的思想,推导了应用于逆时偏移的完全匹配层波动方程,并给出了其高阶交错网格有限差分格式。针对由边界处向计算区域内传播的＂反射波＂,以及地震记录排列两端地震同相轴突变对计算区域的影响这两方面问题,本文给出了逆时偏移中吸收层的布设方式。模型和实际资料的弹性波叠前多分量联合逆时深度偏移结果表明本文的边界处理方法取得了较好的吸收效果,获得了好的联合偏移成像结果。

A study of perfectly matched layers for joint multicomponent reverse-time migration

Reverse-time migration in finite space requires effective boundary processing technology to eliminate the artificial truncation boundary effect in the migration result. On the basis of the elastic velocity-stress equations in vertical transversely isotropic media and the idea of the conventional split perfectly matched layer (PML), the PML wave equations in reverse-time migration are derived in this paper and then the high order staggered grid discrete schemes are subsequently given. Aiming at the “reflections” from the boundary to the computational domain, as well as the effect of seismic event’s abrupt changes at the two ends of the seismic array, the PML arrangement in reverse-time migration is given. The synthetic and real elastic, prestack, multi-component, reverse-time depth migration results demonstrate that this method has much better absorbing effects than other methods and the joint migration produces good imaging results.