A B S T R A C TLand seismic data quality can be severely affected by near-surface anomalies. The imprint of a complex near-surface can be removed by redatuming the data to a level below the surface, from where the subsurface structures are assumed to be relatively smooth. However, to derive a velocity-depth model that explains the propagation effects of the near-surface is a non-trivial task. Therefore, an alternative approach has been proposed, where the redatuming operators are obtained in a data-driven manner from the reflection event related to the datum. In the current implementation, the estimation of these redatuming operators is done in terms of traveltimes only, based on a high-frequency approximation. The accompanying amplitudes are usually derived from a local homogeneous medium, which is obviously a simplification of reality. Such parametrization has produced encouraging results in the past but cannot completely remove the near-surface complexities, leaving artefacts in the redatumed results. In this paper we propose a method that estimates the redatuming operators directly from the data, i.e., without using a velocity model, in a full waveform manner, such that detailed amplitude and phase variations are included. The method directly outputs the inverse propagation operators that are needed for true-amplitude redatuming. Based on 2D synthetic data it is demonstrated that the resulting redatuming quality is improved and artefacts are reduced.

Full waveform inversion (FWI) has the potential to recover detailed quantitative property models of the subsurface, but the process is computationally expensive. Currently available computer systems do not allow to use the full bandwidth of the acquired seismic data, which effectively reduces the resolution that can be obtained. In this paper, we propose a novel approach to obtain high resolution subsurface models from broad-band FWI. The method is based on localization of the inversion, while subsequently the interaction between local domains is estimated. A global field update is calculated which honours the non-linear relationship between the subsurface properties and the measured seismic data. By using this non-linearity, the spectral gap between the a priori background model and the seismic bandwidth will be closed and spatially broad-band properties can be estimated from a band-limited seismic signal.

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