Nonstationary phase-corrected full-waveform inversion with attenuation compensation in viscoacoustic medium

Abstract

Abstract Full-waveform inversion (FWI) acts as an effective technique to estimate subsurface parameter by iteratively reducing the difference between the predictions and the observations. The classic FWI suffers from the problem of converging to the local minimum when the starting model is poor, which is known as the notorious cycle skipping phenomenon. Moreover, due to the anelasticity of the earth, seismic waves always suffer from energy dissipation and phase distortion while their propagation, which leads to an attenuated gradient for FWI, decelerates the convergence rate of the inversion processing. We have proposed a new method referred to as Q-compensated nonstationary phase-corrected FWI (QNPCFWI) to compensate for the attenuation-induced gradient energy loss and the phase mismatch caused by the less-accurate initial velocity model and phase dispersion simultaneously in viscoacoustic medium. We incorporated attenuation compensation mechanism and nonstationary phase correction method for improved inversion efficiency in the case that a poor initial model is used. The main points of this paper can be concluded as follows: (i) we compensate the lost energy for gradient calculation during wave propagation for improved inversion efficiency. (ii) As we know, Q model estimation for real data is challenging and an accurate Q model is hard to get. The proposed QNPCFWI can also work using an approximate Q model. (iii) The proposed method has the ability to mitigate cycle skipping even if the low-frequency components of seismic data are absent. Numerical examples validate the effectiveness and efficiency of our proposed method.