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| Titel |
Seismic attenuation imaging from full-waveform inversion: an onshore case study |
| VerfasserIn |
Michał Malinowski, Stéphane Operto, Alessandra Ribodetti |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250047287
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| Zusammenfassung |
| Here we demonstrate the potential of the visco-acoustic frequency domain full-waveform
inversion (FWI) to reconstruct P-wave velocity and P-wave attenuation factor (QP) from the
onshore seismic data. First we perform a sensitivity analysis of the FWI based on simple
synthetic data. The relative sensitivity of the seismic data to the velocity and the attenuation
factor is strongly dependent on the values of the attenuation in the medium. We show that
both the velocity and the attenuation factor can be reliably reconstructed with a comparable
resolution and without trade-off for sufficiently attenuating media and sufficiently-accurate
velocity starting model by non-linear inversion. However, the imaging of the low
wavenumber of the attenuation from the low frequencies can be unstable. Subsequently, we
applied both the acoustic and visco-acoustic FWI to the real wide-aperture onshore
seismic data with a strong footprint of attenuation that were recorded in the Polish
Basin. We show how a heuristic normalisation of the data with offset allows us to
remove the effect of the attenuation from the data and reconstruct a reliable velocity
model in the acoustic approximation. Alternatively, visco-acoustic FWI allows
us to reconstruct jointly both a reliable velocity model and a Q model from the
true-amplitude data. We propose a pragmatical approach based upon seismic modelling
and source wavelet estimation to infer the best starting homogeneous Q model for
visco-acoustic FWI. We find the source wavelet estimation quite sensitive to the
quality of the velocity and attenuation models used for the estimation. Consistent
source-to-source wavelets obtained in the final visco-acoustic models and a very good
match of the real and time-domain synthetic seismograms confirm validity of our
results. We find the recovered velocity and attenuation models concordant with the
expected lithology and stratigraphy in the study area. We link high-attenuation
zones with the increased clay-content and a presence of the mineralized fluids. |
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