Marine Survey Design for Rich-Azimuth Seismic Using Surface Streamers

By combining multi-azimuth and wide-azimuth acquisition methods, we have designed a richazimuth seismic survey for a sub-salt illumination problem at the Shenzi field in the Gulf of Mexico. The survey uses a master vessel with ten 7000 m streamers and two additional source vessels to make two passes in each of three different sailing directions. This gives full-azimuth illumination beyond 6000 m of sourcereceiver offset with rich coverage beyond 8000 m. The expected duration is about 50% longer than a<br>narrow-azimuth survey requiring infill and undershooting. Our survey requires two source vessels during the entire survey, whereas a standard survey uses one while undershooting. Shooting during the turns expands the coverage area significantly at little cost.