基于互相关相移的主动源地震面波频散成像方法

Activeseismic surface wave dispersion imaging method based on cross-correlation and phase-shifting

以多道面波分析技术(MASW)为代表的主动源面波方法已经在地表勘探领域获得越来越多的应用.准确的面波相速度频散成像是利用主动源面波法进行近地表横波速度反演的必要条件.本文提出了一种新的主动源面波频散成像方法—CCPS(Cross-Correlation and Phase-Shifting)法.首先,将单炮面波记录由时空域变换到频率空间域并消去振幅谱的影响,得到归一化频谱.然后,依次将每道信号与整个记录进行互相关的同时进行相速度扫描叠加.最后经过一次求和过程即得到最终的频散图像.通过理论数据、实际工程地震面波资料和石油勘探面波资料比较了普通相移法和CCPS法的频散成像效果.研究表明:新方法相对于普通相移法而言,明显提高了频散图像的质量,相速度聚焦性能和背景噪声压制能力有显著改善.

The active surface wave methods characterized by multichannel analysis of surface wave（MASW） have been widely used in near surface exploration field.Acquiring accurate phase velocity dispersion images is the essential condition to inverse near surface shear wave velocity by active surface wave phase velocities.This paper presents a new active surface wave phase velocity dispersion imaging method named CCPS（cross-correlation and phase-shifting）method.Firstly,by transforming the single shot surface wave gather from time-space domain to frequency-space domain and eliminating the influence of amplitude spectra,the normalized frequency spectrum can be obtained.Then cross-correlating each trace signal with the whole record,and conducting phase velocity scanning and superposing at the same time.After the above steps,we can get the dispersion image through a summation process finally.We compare the regular phase-shift method and CCPS method via theoretical data,real surface wave data from engineering seismic exploration and oil seismic exploration.The study indicates that the new method apparently improves the quality of dispersion images relative to the phase-shift method.The performance of phase velocity focusing and background noise suppression also has been improved significantly.The theory and realization procedures of this new method are simple.Better phase velocity dispersion images can be obtained with some small changes based on the phase-shift method.