黏声方程Q值反射波反演

地震波在非弹性介质中的衰减效应常用品质因子Q度量.相对准确的Q模型对提高强衰减介质中地震波成像的质量至关重要.本文提出了黏声介质反射波形反演(QRWI)方法来重建地下宏观Q模型.在缺乏大偏移距和低频地震数据时,该方法以黏声波方程为波场传播引擎,利用反射波核函数对模型中深部的敏感性去提取背景Q值.当速度高、低波数成分均已知时,基于波形拟合的QRWI可以获得较高分辨率的反演结果.由于地下介质速度的高波数扰动很难准确估计,本文通过引入峰值频移目标函数,极大地降低了QRWI对速度高波数成分的依赖.理论合成数据实验结果表明,本文方法反演得到的宏观Q模型可以满足衰减补偿逆时偏移成像的要求.

Visco-acoustic wave equation reflection inversion for the Q model

Seismic wave attenuation in anelastic media is characterized by the quality factor (Q). An appropriate Q model is very important for improving the quality of seismic imaging in strong attenuation setting. In this paper, we develop a visco-acoustic wave equation reflection waveform inversion (QRWI) to update the background Q model. When the low frequencies and long-offset components of seismograms are unavailable, QRWI use the visco-acoustic wave equation as a wave propagator and exploit the reflection kernel to update the deep part of the Q model. If both the low-and high-wavenumber velocity components are known, QRWI can obtain relatively high resolution inverted model by matching the waveform directly. Because of the difficulty to accurately estimate the high-wavenumber velocity perturbations, we further introduce the misfit function of peak frequency shifts to reduce the dependency on the high-wavenumber components of the velocity model. The synthetic example demonstrates that the inverted Q model by QRWI can be confidently used for attenuation compensation in reverse time migration.