Next Generation Shallow Water Resolution: Primary Wave Imaging and High Frequency Visco-acoustic Full-waveform Inversion

With many production reservoirs located at a depth greater than 1km, the near surface is often overlooked during seismic processing. Therefore, valuable information relating to shallow geohazards, shallow gas, faults and changes to lithology are lost or unused. We present a new processing methodology to improve the spatial resolution of the near surface seismic image. Careful treatment of source and receiver deghosting was required to handle azimuthal variations and spatial aliasing. A dense 5D interpolation was used to increase crossline sampling and nominal fold in the near surface, allowing for a better signal to noise ratio. At the migration stage, a one-way wave equation migration was considered to capture high frequencies (∼200 Hz) and steep dips while limiting migration noise. A velocity model update was performed using guided-wave inversion, visco-acoustic full-waveform inversion and a 32 Hz joint reflection and refraction full-waveform inversion to produce high spatial resolution. The resulting seismic image has high spatial resolution and broad bandwidth making shallow features highly resolved. The derived velocity model is sufficiently highly resolved to be considered as a tool to aid in seismic interpretation and sediment classification. This comprehensive workflow was essential to overcome the challenges imposed in shallow water acquisition.