李青阳^1,2,,
吴国忱^1,2,,,
吴建鲁^1,2
1. 中国石油大学(华东)地球科学与技术学院, 青岛 266580
2. 海洋国家实验室海洋矿产资源评价与探测技术功能实验室, 青岛 266071

基金项目: 国家科技重大专项（2016ZX05024-001-008）资助


详细信息

作者简介: 李青阳, 男, 1994年出生, 博士研究生, 主要从事地球物理理论、方法与应用方面研究工作.E-mail:986132055@qq.com

通讯作者: 吴国忱, 男, 1965年出生, 教授, 博士生导师, 现从事地球物理方面的教学和科研工作.E-mail:guochenwu@upc.edu.cn

中图分类号: P631

收稿日期:2018-02-01
修回日期:2018-09-06
上线日期:2019-09-05

A multi-parameter full waveform inversion method for a heterogeneous medium with a fluid-solid coupled boundary

LI QingYang^1,2,,
WU GuoChen^1,2,,,
WU JianLu^1,2
1. School of Geosciences, China University of Petroleum(East China), Qingdao 266580, China
2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China


More Information

Corresponding author: WU GuoChen,E-mail:guochenwu@upc.edu.cn

MSC: P631

--> Received Date: 01 February 2018
Revised Date: 06 September 2018
Available Online: 05 September 2019


摘要
摘要:海洋勘探环境可以抽象为下伏固体与上覆流体相互耦合的介质，本文针对流-固边界耦合介质提出了一种高效、稳定的多参数（速度和密度）全波形反演方法.本文采用弹性波一阶位移-应力方程作为过渡层耦合声波压力方程与弹性波位移方程来模拟耦合环境，相比于传统的交错网格建模方法或者构建连续性条件，本文提出的方法在正演精度和稳定性上凸显出很大优势，极大降低了计算内存.反演策略对多参数全波形反演至关重要，由于不同参数之间的相互耦合使得密度在多参数全波形反演中较难获得，因此本文将非均匀流-固边界耦合介质多参数全波形反演分为两个步骤完成：第一步利用变密度声波方程结合推导出的密度梯度算子进行纵波速度和密度的双参数反演；第二步根据链式法则求取横波速度的梯度，结合第一步的反演结果使用流-固边界耦合方程反演横波速度.最后通过与声波动方程数值模拟结果对比证明正演算法的准确性；上覆流体的Marmousi-2模型的数值试验测试说明反演方法的有效性和适应性.
关键词: 流-固边界耦合介质/
全波形反演/
多参数/
纵横波速度/
密度

Abstract:The ocean exploration environment can be abstracted as a medium with the underlying solid and the overlying fluid that couple each other. To such a situation,we propose a novel and stable multi-parameter full waveform inversion method for a medium with a fluid-solid coupled boundary. It uses the elastic wave first-order displacement equation as a transition layer which couples the acoustic pressure wave equation and the elastic wave displacement equation to simulate the coupling environment.Compared with the traditional staggered grid modeling method or construction of continuous conditions,the proposed method has the advantages in accuracy and stability of forward modeling,greatly reducing computational memory.In the multi-parameter inversion problem,the coupling effect between velocity and density is difficult to obtain,so we divide the inversion into two steps:(1) the P-wave velocity and density are inverted simultaneously by using the variable-density acoustic wave equation and new density gradient; (2) the gradient of S-wave velocity is resolved according to the chain rule,and combining the inversion result of the first step,the S-wave velocity is determined using the fluid-solid boundary coupled equation. At last,the accuracy of fluid-solid boundary coupled equation in forward modeling is proved by comparing with the numerical simulation results of acoustic wave equation. A numerical test on Marmousi-2 model with overlying fluid validates the applicability of the proposed inversion method in this work.
Key words:Fluid-solid boundary coupled media/
Full waveform inversion/
Multi-parameter/
P/S-wave velocity/
Density



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