A Combined Elastic Waveform and Gravity Inversion for Improved Density Model Resolution Applied to the Marmousi-II Model
D. Wehner, D. Köhn, D. De Nil, S. Schmidt, S.A. al Hagrey and W. Rabbel
Event name: 77th EAGE Conference and Exhibition 2015
Session: Full Waveform Inversion VII
Publication date: 01 June 2015
Info: Extended abstract, PDF ( 990.91Kb )
Price: € 20
In recent years the elastic full waveform inversion (FWI) was successfully applied to synthetic and field data to compute high resolution velocity models. While seismic velocities are derived from recorded phase information, density models can be estimated from the amplitudes. However, due to the complexity of the inverse problem a long wavelength initial model is required for a good reconstruction of the density. The inclusion of gravity data into the FWI concept can solve this problem. In this study a two-step hierarchic joint inversion of seismic waveforms and gravity data is tested using the Marmousi-II model. In step 1 FWI is performed for all elastic parameters. Gaussian filtered velocity models of the true model and a constant halfspace density model (CDH) are used as initial models. While the velocities can be reconstructed well, the density shows large deviations from the true model. In step 2 joint inversion is applied to optimize only the density model, while the velocity inversion results of the first step and the CDH are used as initial models. The results of this combined approach show a significant improvement of the density model compared to the results of a pure FWI.