The effects of elastic data on acoustic and elastic full waveform inversion

Abstract

Full waveform inversion (FWI) is regarded as an effective method to obtain high accuracy subsurface parameters like velocity and density. When it is applied to real seismic data, some challenges may appear. Real seismic data contain complex wavefields including compressional waves, shear waves and their interconversions, however, acoustic FWI only matches compressional waves but not including the converted compressional waves and treats others as noise. Though elastic FWI can take all types of wave modes into consideration, the inversion results will be compromised by the lack of multi-component input since only the vertical component is generally acquired in practice. It is interesting to investigate the effects of a single-component input generated by an elastic model on acoustic and elastic FWI. The investigation is carried out using a modified Marmousi2 model. Numerical examples illustrate that elastic FWI using a single vertical component observation data has an advantage in obtaining higher resolution inversion results than acoustic FWI. However, the ability of elastic FWI to recover more accurate velocities, especially for S-wave velocity, is limited to a degree if the horizontal component is missing. This situation will worsen in the presence of noise. It is also found that the inversion results of acoustic FWI from the elastic data generated by an explosive source are acceptable, whereas those of acoustic FWI from the elastic data created by a vertical-directional normal stress source are of very low accuracy.