基于共偏移距GPR信号包络和三维速度谱分析的介质电磁波速度估计方法  

A method for estimating electromagnetic wave velocities in subsurface media based on common-offset GPR signal envelope and 3D velocity spectrum analysis

作　　者：周鑫 王洪华[1] 王欲成 吴祺铭 王浩林 刘洪瑞 ZHOU Xin;WANG Hong-Hua;WANG Yu-Cheng;WU Qi-Ming;WANG Hao-Lin;LIU Hong-Rui(School of Geosciences,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541004

出　　处：《物探与化探》2024年第6期1693-1701,共9页Geophysical and Geochemical Exploration

基　　金：广西自然科学基金项目(2022GXNSFAA035595,2020GXNSFAA159121)。

摘　　要：目前广泛应用于探地雷达(ground penetrating radar,GPR)信号的速度谱分析方法大都通过叠加相干信号的振幅能量来构建速度谱,并估计地下介质电磁波速度;当信号子波出现多个波峰和波谷时,基于振幅的方法所构建的速度谱会出现多个能量团,不利于后续能量峰值的判别、拾取和速度估计。为此,提出了一种基于共偏移距GPR信号包络和三维速度谱分析的地下介质电磁波速度估计方法。该方法通过扫描GPR剖面中的双曲线绕射波信号包络来构建叠加能量随零偏双程走时、试速度以及测点位置变化的三维速度谱,并根据三维速度谱中双曲线顶点出现位置,提取二维速度谱切片。在此基础上,拾取二维速度谱切片中能量峰值对应的试速度并作为地下介质的电磁波速度。数值试验结果表明:与基于信号振幅的三维速度谱分析方法相比,基于信号包络的三维速度谱分析方法计算的速度谱中连续能量团更少、能量更集中、速度估计误差更小,且可更有效地构建逆时偏移的速度模型。Currently,velocity spectrum analysis methods widely used for ground-penetrating radar(GPR)signals mostly construct velocity spectra by superposing the amplitude energy of coherent signals to estimate electromagnetic wave velocities in subsurface media.In the case of multiple peaks and troughs in signal wavelets,velocity spectra constructed using these amplitude-based methods display multiple energy clusters,adversely affecting the identification,picking,and velocity estimation of subsequent energy peaks.Hence,this study proposed a method for estimating electromagnetic wave velocities in subsurface media based on common-offset GPR signal envelope and 3D velocity spectrum analysis.By scanning the signal envelope of hyperbolic diffracted waves in the GPR profile,the proposed method constructed the 3D velocity spectra of superimposed energy varying with zero-offset two-way travel time,test velocity,and measuring point position.Moreover,it extracted the slices of 2D velocity spectra according to the positions of hyperbolic vertices in the 3D velocity spectra.On this basis,the test velocities corresponding to the energy peaks in the slices of 2D velocity spectra were picked as the electromagnetic wave velocities in subsurface media.The numerical test results show that compared to the amplitude-based methods,the signal envelope-based 3D velocity spectrum analysis method obtained velocity spectra characterized by fewer continuous energy clusters,more concentrated energy,and minor velocity estimation errors,thus more effectively constructing the velocity model with inverse-time migration.

关 键 词：三维速度谱分析 信号包络 共偏移距探地雷达信号 速度估计 

分 类 号：P631.4[天文地球—地质矿产勘探]