Reflection full-waveform inversion using a modified phase misfit function

摘要

Reflection full-waveform inversion (RFWI) updates the low-and high-wavenumber components,and yields more accurate initial models compared with conventional full-waveform inversion (FWI).However,there is strong nonlinearity in conventional RFWI because of the lack of low-frequency data and the complexity of the amplitude.The separation of phase and amplitude information makes RFWI more linear.Traditional phase-calculation methods face severe phase wrapping.To solve this problem,we propose a modified phase-calculation method that uses the phase-envelope data to obtain the pseudo phase information.Then,we establish a pseudophase-information-based objective function for RFWI,with the corresponding source and gradient terms.Numerical tests verify that the proposed calculation method using the phase-envelope data guarantees the stability and accuracy of the phase information and the convergence of the objective function.The application on a portion of the Sigsbee2A model and comparison with inversion results of the improved RFWI and conventional FWI methods verify that the pseudophase-based RFWI produces a highly accurate and efficient velocity model.Moreover,the proposed method is robust to noise and high frequency.