A multi-step strategy for mitigating severe nonlinearity in elastic full-waveform inversion
【Abstract】Elastic full-waveform inversion (EFWI) is a powerful tool for estimating high-accuracy subsurface elastic parameters. However the nonlinearity in EFWI is much severer than that in acoustic FWI. We propose a multi-step EFWI strategy to mitigate the nonlinearity for the reconstruction of high-accuracy P- and S-wave velocities. We use envelope-based EFWI as first step to update the long wavelength components of P- and S-wave velocities. Using the envelope-based EFWI's results as initial models, a time-domain modeling based frequency-domain EFWI is used to further reduce nonlinearity and recover short wavelength components of the models with hierarchical multi-scale inversion strategy. The numerical test demonstrates that, when the low frequency and long offset components are not available in seismic data, our multi-step strategy is effective for reconstructing high-accuracy P- and S-wave velocities, especially for S-wave velocity.
【Keywords】 elastic wave; full-waveform inversion; envelope; time domain ; frequency domain ; multi-scale;
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