Acoustic full waveform tomography in the presence of attenuation: a sensitivity analysis
Abstract
Full waveform tomography (FWT) is a powerful velocity building method to exploit the full richness of seismic waveforms in complex media. Most applications today neglect the frequency-dependent amplitude decrease and phase velocity dispersion caused by intrinsic attenuation. In this study, we present a numerical investigation of the influence of attenuation on the recovered velocity model. Based on the generalized standard linear solid as rheological model, we incorporate attenuation into a 2-D time-domain acoustic FWT scheme. Attenuation is considered here as a modelling and not an inversion parameter. We investigate two reflection seismic experiments: (1) a visco-acoustic 1-D model and (2) a visco-acoustic version of the Marmousi model to which realistic quality factors are assigned. In the presence of soft rocks with pronounced absorption we observe a poor recovery of the velocity model when attenuation effects are not taken into account in the modelling. By considering an appropriate attenuation model in the forward modelling of the FWT, the accuracy of the reconstructed velocity model improves significantly in both cases. Even a homogeneous background quality factor model might allow a satisfactory recovery of the velocity model, provided that it is a quite good representation of the shallow structures. Our results suggest to consider attenuation as a smooth background modelling parameter in reflection seismic configurations to improve velocity model building by a purely acoustic inversion scheme.
- Publication:
-
Geophysical Journal International
- Pub Date:
- November 2013
- DOI:
- 10.1093/gji/ggt305
- Bibcode:
- 2013GeoJI.195..985K
- Keywords:
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- Inverse theory;
- Numerical approximations and analysis;
- Seismic attenuation;
- Seismic tomography;
- Wave propagation