基于最佳小波基的地震面波插值方法

在利用实际地震数据中的面波反演近地表横波速度的过程中,若道间距较大、空间采样率不足,则会产生空间假频现象,从而降低频率速度谱的信噪比,影响频散曲线提取的精度以及反演效果,因此需要针对面波进行插值处理。文中提出了一种基于最佳小波基的地震面波插值方法,通过理论分析和实验误差对比在地震数据处理常用的众多小波基中选出适用于插值处理的最佳小波基bior6.8,提高了插值精度。针对面波同向轴为线性且斜率较大的特点,文中首先采用线性动校正的方法对面波进行拉平处理,再进行小波变换插值,最后进行反线性动校正恢复面波。通过对理论模型与实际资料进行插值处理验证了本文方法的有效性,插值后的面波记录波形恢复较好,显著提高了频率速度谱的信噪比,有效解决了面波数据空间采样率不足引起的假频问题。

Seismic surface wave interpolation method based on optimistic wavelet basis

The surface wave in the real seismic data can be used to invert near surface shear velocity.If the trace interval is large and the spatial sampling rate is not enough,there will be spatial aliasing.This can not only decrease the signal-to-noise ratio of frequency-velocity spectra but also affect the accuracy of dispersion curves and the result of inversion.So it is necessary to do the interpolation of surface wave.This paper presents a seismic surface wave interpolation method based on optimistic wavelet basis.The optimistic wavelet basis bior6.8 which is suitable for interpolation processing can be selected among many wavelet bases commonly used in seismic data processing through the theoretical analysis and the comparison of experimental error.The use of optimistic wavelet basis bior6.8 will increase the accuracy of interpolation.Because the events of surface wave are linear and the slopes of them are larger,this paper uses the linear normal moveout to level the events of surface wave firstly,then carries out the wavelet transform interpolation,and finally uses the inverse linear normal moveout to recover the surface wave.The effectiveness of the proposed method is verified by the interpolation result of theoretical model and real seismic data.After the interpolation,the waveform of the interpolated surface wave records is well recovered. It can improve the signal-to-noise ratio of frequency-velocity spectra,and solve the aliasing problem effectively caused by the undersampling of the surface wave data.