Acoustic Wave Based Time-Domain Full Waveform Inversion and Its Application

In this paper, the acoustic wave-based time-domain full waveform inversion (FWI) is investigated. The FWI is a typical nonlinear ill-posed problem. In order to overcome its ill-posedness, the strategy of stepwise inversion is adopted. The inversion is carried out from low frequency to high frequency, and the inverse result at low frequency is chosen as the initial model for the high frequency inversion. This strategy effectively strengthens the robustness of inversion. The forward simulation is implemented efficiently with the explicit finite difference scheme while the inverse iteration is based on the LBFGS algorithm. The gradient of the objection function is computed by the wavefield backward technique. Numerical computations are not only completed for the benchmark Overthrust model but also for a real data set and good inversion results are yielded.