Q estimation by full-waveform inversion: analysis and misfit functions comparison
Résumé
Attenuation parameter estimation, through the quality factor Q, is very important in many targets at the exploration scales, as it can provide direct information about subsurface fluid content and is also a key parameter for migration focalisation in Q-compensated migration. For constant Q properties over frequencies, the seismic attenuation effect on the waveform almost linearly increases with frequency. It is therefore challenging to estimate Q by Full Waveform Inversion (FWI), which often uses in practice a limited-band low-frequency information of seismic data. In this work, we first analyze the effect of Q on low-frequency data. Then, we evaluate the behavior of three FWI misfit functions: the usual waveform difference, the instantaneous centroid frequency, and a frequency weighted amplitude of the observed and predicted data. Different from waveform difference, the other two formulations can extract the peculiar features of spectral modification of the waveform related to attenuation.
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