P & S wave attenuation effects on full-waveform inversion for marine seismic data

Abstract

Summary Marine seismic data inversion in 3D is a very computationally intense process. Often, approximating assumptions are made which limit the number of physical parameters inverted for or speed up the forward modeling. The standard approach to seismic waveform inversion consists of iteratively minimizing the misfit between the amplitudes of the measured and the modeled data. The approximation that the propagation is purely elastic may be acceptable for inversions at low frequencies, but for higher frequencies will result in significant errors in the modeled amplitudes, and will therefore have a direct impact on the inversion results. In this paper we evaluate the potential impact of such approximations by performing a series of inversions of different models with different approximations and for different viscoelastic Earth models. In these inversions the synthetic data set is computed for a 1D viscoelastic medium, and the inversion is likewise performed for vertical variation only. The different physical approximations go from a quasi-elastic medium to a fully viscoelastic medium. Blocky versus smooth viscoelastic Earth models are also considered. As expected, the viscoelastic approximation is not minor and it impacts the inversion results. Even if, in the inversion process, the viscoelastic parameters are not perfectly estimated, their inclusion substantially improves the estimation of the elastic parameters.