Coil Shooting single-vessel full-azimuth (FAZ) acquisition is a technique that extends conventional multi- and wide-azimuth (MAZ and WAZ) survey capabilities by acquiring marine seismic data using a single vessel sailing in a series of overlapping, continuously linked circles. This delivers a greater range of azimuths and offsets compared with parallel WAZ geometries, resulting in better target illumination without nonproductive intervals for line changes.
The Coil Shooting acquisition technique can be extended to Dual Coil Shooting multivessel FAZ acquisition, which involves multiple source and receiver vessels sailing in interlinked circles and offers ultralong-offset FAZ data. The trace density of this design is approximately 2.5 times that of current WAZ survey designs, and the resulting very-high fold will improve signal-to-noise ratio for imaging weak subsalt reflections.
Coil Shooting and Dual Coil Shooting acquisition are both supported by the DSC dynamic spread control system, which automatically controls the vessel, streamer, and source positions; maintains the positioning of the sources based on the preplot; and keeps constant streamer separation.
The departure from traditional linear shooting patterns presents processing challenges, such as different noise modes, the offset and azimuth characteristics, and higher volumes of data. WesternGeco has developed processing methods to address these challenges. Many of these methods are based on the unique point-receiver recordings available from the Q-Marine point-receiver marine seismic system.