Eliminating the Ghost

The surface of the ocean acts like a perfect acoustic mirror. Every signal that is reflected back from the subsurface bounces off the sea-surface, creating echoes, or ghosts, that are visible on the seismic data

GeoStreamer® was designed to mitigate the effect of the ghost reflections coming from the perfectly reflecting sea surface. The ability to remove the ghost accurately allows us to tow the recording sensors deeper, further away from the noise generated by the ocean's surface. 

Noise is reduced and signal increases with deeper tow, especially for low frequencies. Improved low-frequency content enhances the quality and accuracy of seismic inversion and reservoir characterization.

Clear Benefits

GeoStreamer multisensor wavefield separation allows

  • Recording of high-quality data independent of the sea-state
  • Longer operating windows in moderate to marginal weather
  • Prestack AVO compliant (amplitude and phase preserved over full bandwidth)
  • Data richer in low-frequency information due to deeper tow
  • Improved subsurface velocity estimation (FWI)
  • Improved imaging using separated wavefields (SWIM)
  • Fully 4D compliant (full backward and forward compatibility)

Multisensor Signals

Using the complementary properties of two sensors, GeoStreamer enables the removal of the receiver ghost by combining pressure measurements and velocity measurements. 

The measurements from the two sensors can be used to perform wavefield separation into up- and downgoing wavefields. The receiver ghost or downgoing wavefield carries the imprint of the shape of the reflecting sea surface, which is different for every shot. Accurately removing the time- and space-varying receiver ghost improves repeatability for 4D monitoring.

Multisensor and multicomponent streamers benefit from improved overall signal-to-noise ratio (S/N) of the separated wavefields. The particle motion sensor is not used for the very low frequencies, typically below 15-20 Hz. Here the deep-towed high-quality pressure sensor is used to estimate the velocity sensor signal, which can be done with confidence. Towing deeper enables us to record more low-frequency information.