Near Surface S-wave Velocity Inversion Based On Rayleigh Surface Wave Dispersion Curve

With the increasing requirements of seismic exploration,elastic wave exploration has been paid more and more attention.However,elastic wave seismic data processing still faces many challenges,especially the near surface problem.Obtaining accurate near surface velocity is very important for seismic data processing and imaging accuracy in complex areas,and it is also an important basis for reasonably selecting source excitation parameters.For shallow layer wave exploration,the subsurface near surface shear wave velocity structure is mainly obtained by inverting the extracted dispersion curve.Therefore,the near surface shear wave velocity inversion based on Rayleigh surface wave dispersion curve is studied in detail in this paper.In the process of multi-channel surface wave analysis,the accuracy of picking up the dispersion relationship directly affects the reliability of velocity inversion results.In this paper,the surface wave information is used to obtain the very important near surface shear wave velocity of elastic wave.On the basis of multi-channel surface wave superposition and automatic picking up,a near surface shear wave velocity inversion method based on cluster analysis of surface wave dispersion curve is proposed.This method fully considers the uncertainty of wave dispersion curve under the condition of low signal-tonoise ratio,and improves the accuracy of dispersion curve picking by introducing Manhattan distance K-means clustering algorithm into dispersion curve picking.The multi-channel and multi window superposition technology is used to improve the adaptability of surface wave inversion to the variation of transverse velocity.The reliability of inversion is improved by clustering algorithm and multi window superposition.The clustering algorithm obtains more accurate dispersion curve,which is more conducive to the subsequent process of shear wave velocity inversion.The comparison of simulation data shows that the method proposed in this paper has better effect and higher accuracy than the conventional algorithm.The proposed method is applied to the inversion of surface wave data in engineering exploration and oil and gas exploration,and the results also verify the effectiveness of the method.