弹性波全波形反演目标函数性态与反演策略

Objective function behavior and inversion strategy in elastic full-waveform inversion

弹性波全波形反演面临的主要技术难题是源于弹性波传播的复杂性所引起的强烈非线性问题。基于弹性波有限差分正演模拟方法,数值分析了多波多分量地震数据的不同反演目标函数在纵、横波速度,阻抗以及Lamé常数3种参数化方式下随弹性参数摄动尺度的变化关系和非线性程度,具体分析了不同偏移距数据的L2范数目标函数随纵、横波速度摄动尺度的变化关系和非线性程度,为分步骤、分尺度弹性波全波形反演方法和反演策略的选择提供了理论指导。

Severe nonlinearity is one of the main obstacles for elastic full-waveform inversion （EFWI）, which is caused by the complexity of elastic wave propagation. Based on the finite-difference elastic wave simulation method, we analyzed the behav- ior and nonlinearity of different objective functions with respect to elastic parameter perturbation scales in velocity, impedance and Lam6 parameterizations, especially the evolution of L2 norm objective function calculated by seismic data in different off- sets with respect to P-wave and S-wave velocity perturbation scales. The analysis results will provide some theoretical guid- ance for EFWI to implement the multi-step and multi-scale inversion strategy.