Simultaneous Estimation of P- and S-Wave Velocities by Integrated Inversion of Guided-P and Surface Wave Dispersion Curves

Abstract

Compared with surface wave corresponding to the normal mode, which is widely studied, there is less research on guided-P wave corresponding to the leaking mode. Guided-P wave carries the dispersion information that can be used to construct the subsurface velocity structures. In this paper, to simultaneously estimate P-wave velocity (\({{v}}_{{P}}\)) and S-wave velocity (\({{v}}_{{S}}\)) structures, an integrated inversion method of guided-P and surface wave dispersion curves is proposed. Through the calculation of Jacobian matrix, the sensitivity of dispersion curves is quantitatively analyzed. It shows that the dispersion curves of guided-P and surface waves are, respectively, sensitive to the \({{v}}_{{P}}\) and \({{v}}_{{S}}\). Synthetic model tests demonstrate the proposed integrated inversion method can estimate the \({{v}}_{{P}}\) and \({{v}}_{{S}}\) models accurately and effectively identify low-velocity interlayers. The integrated inversion method is also applied to the field seismic data acquired for oil and gas prospecting. The pseudo-2D \({{v}}_{{P}}\), \({{v}}_{{S}}\) and Poisson’s ratio inversion results are of significance for near-surface geological interpretation. The comparison with the result of first-arrival traveltime tomography further demonstrates the accuracy and practicality of the proposed integrated inversion method. Not only in the field of exploration seismic, the guided-P wave dispersion information can also be extracted from the earthquake seismic, engineering seismic and ambient noise. The proposed inversion method can exploit previously neglected guided-P wave to characterize the subsurface \({{v}}_{{P}}\) structures, showing broad and promising application prospects. This compensates for the inherent defect that the surface wave dispersion curve is mainly sensitive to the \({{v}}_{{S}}\) structure.