Imaging normal faults using dual sensor streamers

Increasing the tow depth of hydrophone-only acquisition systems from 6 to 15 m moves the notches created by the sea-surface ghost reflections to midrange frequencies. To preserve the mid-frequency range, the compromise was to tow the streamers shallow, resulting in higher noise levels and poor imaging of the deeper reflectors. The marine seismic industry has designed several solutions to this problem, giving rise to broad-bandwidth de-ghosted seismic data. The first effective acquisition-based solution to the ghost notch problem was developed by Petroleum Geo-Services (PGS) and involves dual-sensor streamers (GeoStreamer®). In contrast to conventional, hydrophone-only acquisition systems, GeoStreamer® is equipped with a hydrophone and a vertical velocity sensor, which detects the time-delayed receiver ghost reflection with the opposite polarity to the hydrophone. The signal-to-noise ratio is improved by a deeper tow, especially at the low frequency end of the seismic spectrum. Improved low frequency content enhances the quality and accuracy of seismic inversion and reservoir characterization.