Plain sailing offshore Angola as first ever wide-azimuth survey acquiredProjects and Operations // January 14, 2010
WesternGeco has completed the first ever wide-azimuth (WAZ) survey in Angolan waters. Despite challenging currents and unfavorable weather conditions, the survey was acquired ahead of schedule and within budget.
The Angola WAZ survey was acquired using three vessels that were organized in a unique acquisition pattern designed to improve azimuthal illumination over complex subsalt plays. Western Trident acted as a source and recording vessel, with Geco Diamond and Gilavar as additional source vessels.
Q-Pilot software was used to enable the vessels to automatically follow the planned vessel, source, and point-receiver positioning.
Particularly suitable for large-area 3D acquisition, WAZ utilizes different combinations of source boats and receiver boats. The geometry of the various sources and receivers enables the illumination of deep structures using near and far offsets, both inline and crossline.
Channel interval, streamer spacing, and streamer length can be varied to achieve the desired shot-receiver density, as well as the numbers of source boats and receiver boats used. Multiple source boat positioning provides the desired inline offsets and increased range of azimuths.
WAZ is most commonly used in the Gulf of Mexico; however, the technique is being adopted around the world for enhanced subsurface illumination and superior multiple attenuation over challenging lithology.