Abstract: Methods and systems that compute an approximate vertical-velocity wavefield based on a measured pressure wavefield and knowledge of the free-surface shape when the pressure wavefield was measured are described. The measured pressure wavefield is used to compute an approximate frozen free-surface profile of the free surface. The approximate frozen free-surface profile and the measured pressure wavefield are then used to compute an approximate vertical-velocity wavefield that does not include low-frequency streamer vibrational noise. The approximate vertical-velocity wavefield and measured pressure wavefield may be used to separate the pressure wavefield into up-going and down-going pressure wavefields.

Abstract: Methods and systems that remove particle-sensor noise from measured vertical-velocity wavefield are presented. A approximate vertical-velocity data is computed from pressure data and vertical-velocity data at receiver coordinates of a seismic data acquisition system. The pressure data is composed of a pressure signal component and pressure-sensor noise and the vertical-velocity data is composed of a vertical-velocity signal component and particle-motion-sensor noise. A filter that gives a minimum difference between the vertical-velocity data and the approximate vertical-velocity data at each receiver coordinate is computed. Vertical-velocity data composed of the vertical-velocity signal component and approximate particle-motion-sensor noise based on the pressure-sensor noise is convolved with the filter at each receiver coordinate.

Abstract: Methods and systems that remove particle-sensor noise from measured vertical-velocity wavefield are presented. A approximate vertical-velocity data is computed from pressure data and vertical-velocity data at receiver coordinates of a seismic data acquisition system. The pressure data is composed of a pressure signal component and pressure-sensor noise and the vertical-velocity data is composed of a vertical-velocity signal component and particle-motion-sensor noise. A filter that gives a minimum difference between the vertical-velocity data and the approximate vertical-velocity data at each receiver coordinate is computed. Vertical-velocity data composed of the vertical-velocity signal component and approximate particle-motion-sensor noise based on the pressure-sensor noise is convolved with the filter at each receiver coordinate.

Abstract: Methods and systems that compute an approximate vertical-velocity wavefield based on a measured pressure wavefield and knowledge of the free-surface shape when the pressure wavefield was measured are described. The measured pressure wavefield is used to compute an approximate frozen free-surface profile of the free surface. The approximate frozen free-surface profile and the measured pressure wavefield are then used to compute an approximate vertical-velocity wavefield that does not include low-frequency streamer vibrational noise. The approximate vertical-velocity wavefield and measured pressure wavefield may be used to separate the pressure wavefield into up-going and down-going pressure wavefields.