Separating Simultaneous Sources Using Phase Sequencing and Reconstruction in Marine Seismic Vibrators

Abstract

Compared with a conventional airgun source, a marine seismic vibrator can allow for much greater control of the emitted seismic wavefield. One possibility with a marine vibrator is to control the phase of the wavefield. We consider the use of phase control to emit wavefields that change in phase from shot to shot, following a prescribed sequence, referred to as phase sequencing. Some phase sequences allow moving energy from selected sources into a normally empty part of the frequency-wavenumber spectrum in the common-receiver domain. We demonstrate how this type of seismic acquisition, combined with wavefield reconstruction techniques, has the potential to provide a new method of simultaneous-source acquisition and separation. We further describe how this technique may be extended to high-multiplicity simultaneous source acquisition, with potential implications for data quality and survey efficiency. Other phase sequences can be used to attenuate residual shot noise from marine seismic data. Phase sequencing cannot be used with airguns because we have no control of the phase of the airgun signal other than simple changes of amplitude and overall time delay.