摘要
随着多分量采集技术的发展,弹性波逆时偏移技术在三维各向异性介质复杂地质构造成像中得到了广泛的应用.然而耦合的P波场和S波场,会在传播过程中产生串扰噪声,降低弹性波逆时偏移的成像精度.为了解决这一问题,本研究针对具有倾斜各向异性对称轴的三维横向各向同性(Transverse Isotropy,TI)介质,提出了一种矢量弹性波场快速解耦方法,可以有效提高偏移剖面的成像质量.该方法首先通过坐标转换,将观测系统坐标系的垂直轴旋转到TI介质的对称轴方向,在新坐标系下,根据具有垂直对称轴的三维横向各向同性(Vertical Transverse Isotropy,VTI)介质中的分解算子,推导出三维TI介质解耦算子表达式.接着引入一种在空间域快速计算分解波场的方法,来实现空间域矢量P波场和S波场分离,极大地提高了计算效率.最后,通过点积成像条件,将提出的P/S波分解方法引入到三维TI介质弹性波逆时偏移中,得到高精度的PP和PS成像.与以往的波场分解方法相比,本文方法具有数值稳定和计算效率高的特点.数值算例表明,应用上述三维TI分解算子得到的偏移剖面有效压制了噪声,提高了成像质量.
With the development of multi-component acquisition technology,elastic reverse-time migration(ERTM)is widely used for seismic imaging in 3D anisotropic media.However,crosstalk artifacts degrade the image quality due to intrinsically coupled P-and S-wavefields.To solve this problem,this study presents an effective vector P-and S-wavefield decomposition approach that can improve the ERTM image of 3D Transverse Isotropy(TI)media.Firstly,we rotate the observation coordinate system to align its vertical axis with the tilted symmetry axis.Secondly,based on the 3D VTI decoupled operator,we derive the formulations of the 3D TI decomposing operator in the new coordinate system.Thirdly,we implement the vector P-and S-wavefield decomposition on the space domain by introducing a novel and efficient formula,which accelerates the computational efficiency of the decomposition.Finally,we introduce P/S wave-mode decomposition method into ERTM via a dot-product imaging condition to generate high-quality PP and PS images.Compared with previous studies,our proposed method in 3D TI media is both numerically stable and computationally efficient.Several numerical examples illustrate the good performance of our approach on image improvement in 3D TI media.
作者
张辉
尹国庆
徐珂
王志民
王海应
梁景瑞
来姝君
左佳卉
鲜成钢
申颍浩
赵杨
ZHANG Hui;YIN GuoQing;XU Ke;WANG ZhiMin;WANG HaiYing;LIANG JingRui;LAI ShuJun;ZUO JiaHui;XIAN ChengGang;SHEN YingHao;ZHAO Yang(PetroChina Tarim Oilfield Company,Korla Xinjiang 841000,China;Institute of Unconventional Science and Technology,China University of Petroleum,Beijing 102249,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第2期670-683,共14页
Chinese Journal of Geophysics
基金
国家重大科技专项(2016ZX05051)
中国石油天然气股份有限公司重大科技专项(2018E-1803)资助。
关键词
三维各向异性介质
弹性波逆时偏移
矢量P/S波场分解
多分量地震数据
3D anisotropic TI media
Elastic reverse time migration(ERTM)
Vector P/S wavefield decomposition
Multi-component seismic data
