Title

On practical implementation of amplitude-preserving reverse time migration based on asymptotic approximation

单位

1.成都理工大学地球物理学院,四川成都610059;2.波现象与智能反演成像研究组(WPI),同济大学海洋与地球科学学院,上海200092

Organization

1.College of Geophysics,Chengdu University of Technology,Chengdu 610059,China;2.Wave Phenomena and Intelligent Inversion Imaging Group (WPI),School of Ocean and Earth Science,Tongji University,Shanghai 200092,China

摘要

从线性化反演成像的正问题出发,讨论了体散射和面散射模式下散射波场的表达、线性化及其高频近似表征。在Bayes框架下,进一步讨论了高频近似的线性化体散射模式(ray+Born近似)以及高频近似的线性化面散射模式(ray+Kirchhoff近似)下反演成像公式及其波动方程的实现。将逆散射成像公式中波场隐式分解思想融入到ray+Kirchhoff近似下波动方程反演成像公式中,得到了改进的基于反射模式的真振幅逆时偏移(RTM)成像条件。给出的改进成像条件能够在成像过程中自动保真地消除RTM成像过程中的低波数噪声,同时,该成像条件输出的成像结果与ray+Kirchhoff近似下反演结果具有一致性。此外,还简单讨论了基于给出的成像条件的角度反射系数输出、高效稳健角度域照明补偿方法以及阻抗扰动成像方法。

Abstract

Abstract: Based on the forward problem of the linearized inversion imaging,the expression,linearization,and high-frequency approximation of the scattering field in bulk and surface scattering modes are discussed.Under the Bayes framework,the inverse imaging formula and two modes of its wave equation implementation are discussed,namely,the linearized body scattering mode(ray-Born approximation),and the linearized surface scattering mode(ray-Kirchhoff approximation) of the high-frequency approximation.We integrate the concept of implicit wavefield decomposition of the inverse scattering imaging formula into the wave equation inversion with the ray-Kirchhoff approximation,and obtain an improved RTM imaging condition based on the reflection mode.The proposed imaging condition can automatically remove low-wavenumber RTM artifacts reliably.Meanwhile,the output imaging results are consistent with the ray-Kirchhoff approximation.In addition,the angle reflection coefficient output,the robust illumination compensation method,and the perturbation imaging method based on the proposed imaging conditions are discussed.

关键词：

散射场计算; 反演成像; 反射波; 高频近似; 逆时偏移; 角度反射系数; 角度域照明补偿; 波阻抗成像;

Keywords:

scattering wavefield calculation,inversion imaging,; reflection seismology,; high-frequency approximation,; reverse time migration,; angle-dependent reflection coefficient,; angle-dependent illumination compensation,; impedance perturbation imaging;

基金项目

国家自然科学基金(41774126,41604100)和国家科技重大专项(2016ZX05024-001,2016ZX05006-002)共同资助。

DOI

10.3969/j.issn.1000-1441.2019.03.008

基于高频近似波传播的实用化保真RTM成像方法