A Sequential Inversion for the Velocity and the Intrinsic Attenuation Using Efficient Wavefield Inversion

Full-waveform inversion (FWI) has become a popular method to retrieve high-resolution subsurface model parameters. An accurate simulation of wave propagation plays an important role in achieving better data fitting. For intrinsically attenuative media, wave propagation experiences dispersion and loss of energy. Thus, it is sometimes crucial to consider the intrinsic attenuation of the Earth in the FWI implementation. Viscoacoustic FWI aims at achieving a joint inversion of the velocity and attenuative models. However, multiparameter FWI imposes additional challenges including expanding the null space problem and the parameter trade-off issue. We use an efficient wavefield inversion (EWI) method to invert for the velocity and the intrinsic attenuation, sequentially. This approach is implemented in the frequency domain, and the velocity, in this case, is complex-valued in the viscoacoustic EWI. The inversion for the velocity and the intrinsic attenuation is handled in separate optimizations. As viscoacoustic EWI is able to recover a good velocity model, the velocity update leakage to the Q model is largely reduced. We show the effectiveness of this approach using synthetic data generated for a viscoacoustic Marmousi model.