A comparison between Laplace domain and frequency domain methods for inverting seismic waveforms

Abstract

We compared the ability of full waveform inversion to recover background velocity models from data containing no low-frequency information using the frequency and Laplace domains. Low-frequency information is crucial for recovering background velocity when using frequency-domain waveform inversions. However, the dearth of low-frequency information in field data makes frequency-domain inversion impractical without accurate starting velocity models. Instead, by performing waveform inversion in the Laplace domain, one can recover a smooth velocity model that can be used for either migration or for subsequent frequency-domain inversion as an accurate initial velocity model. The Laplace-transformed wavefield can be thought of as the zero-frequency component of a damped wavefield over a range of damping constants. In this paper, we compare results obtained from both frequency- and Laplace-domain inversions and confirm that the Laplace-domain inversion can be used to recover background velocity from real data without low-frequency information. We also demonstrate that the Laplace-domain inversion can provide the frequency-domain inversion with smooth initial velocity models for better inversion results.