Reflectivity wavefield inversion of synthetic data from elastic and viscoelastic anisotropic flat-layered, shale-bounded fractured sandstone reservoir models

Pacheco, S. and McMechan, G.A., 2013. Reflectivity wavefield inversion of synthetic data from elastic and viscoelastic anisotropic flat-layered, shale-bounded fractured sandstone reservoir models. Journal of Seismic Exploration, 22: 223-250. Full-wavefield inversion based on frequency-domain reflectivity modeling is developed and applied, in the 7-p domain, to synthetic data for flat-layered viscoelastic, anisotropic models. P- and S-wave quality factors and HTI and VTI anisotropy are extracted, by inversion, from synthetic data for viscoelastic, fractured sand reservoir models. Ignoring viscoelasticity or anisotropy results in errors and increased uncertainty in the estimates of the other seismic parameters, as the parameterization is incomplete. Increasing the number of layers or parameters, or adding noise, makes the inversion more difficult to converge to the correct solution; parameter correlations confirm this observation, showing more inter-layer correlations. The noise is mainly left in the residual wavefield. Better results are obtained with layer stripping than without, as the solution space has fewer local minima when the model contains fewer parameters (fewer degrees of freedom). Multiple layer stripping runs, solving for parameters adjacent pairs of layers together, improves the inversion performance and the accuracy of the results.
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