Research On Inverting Quality Factor Of Near Surface Based On Surface Waves

In this paper,the problem of obtaining the velocity and quality factor of near surface in seismic record is studied.The idea of utilizing surface waves,which are often regarded as noise in seismic records,to invert the velocity and quality factor is raised in this paper.The research results will provide a new method of near surface parameters modeling for oil and gas exploration and engineering geophysical exploration,and it can avoid repeated collection and reduce production cost.Three aspects are mainly studied in this paper:(1)Firstly the phase velocity and attenuation coefficient curves are calculated from surface wave records.We raised fv-MUSIC method to obtain dispersion curve of surface waves,and use the extended MUSIC method to extract the attenuation coefficient curve.Based on the velocity difference of multi-modes of surface waves,we put forward a method of separating and extracting attenuation coefficient curves of multi-modes.(2)Secondly,the least square method is used to inverse the shear wave velocity and layer thickness by using the information of surface waves dispersion.(3)Lastly,based on the inverted velocity,the near surface Q value is obtained using the attenuation coefficient curves.And the jointly inversion of fundamental mode and higher modes of surface waves is realized.The feasibility and accuracy of the study route are verified by simulation experiments.The analysis of the practical data also proves the effects of extracting the surface wave dispersion curve and attenuation coefficient curves of multi-modes.