Shear Wave Velocity Inversion from the Seismic Surface Waves Using Data Adaptive Wavelets

摘要

We study the dynamic and physical properties (shear velocity, seismic attenuation, stiffness and density) of marine sediments from seismic-acoustic records of surface/interface waves along the water-seabed boundary. Accurate models of the marine sediments properties in the shallow subsurface are critical in many disciplines. For example, in oil and gas exploration knowledge of the sedimentary acoustic properties helps to improve the shear wave static corrections, it provides shear strength modulus in the geotechnical engineering, helps to estimate acoustic loss for sonar operation in the shallow water. Our method relies on using dispersive characteristics of the seismic surface waves which can be further inverted for the shear velocities as function of depth and distance. We use wavelet analysis to separate surface wave modes and extract their group and phase velocities. To improve the accuracy in imaging of the surface wave modes we have developed and applied a new tool - adaptive wavelet which parameters are defined directly from the data. We demonstrate how these wavelets can be employed to provide more accurate shear waves velocities estimates.