Using 3D finite‐difference modeling to design wide azimuth surveys for improved subsalt imaging

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  • CRCarl Regone
    Carl Regone
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Abstract
3D finite‐difference (FD) modeling studies conducted over subsalt structures in the deep‐water Gulf of Mexico confirm the deficiencies of narrow azimuth towed streamer (NATS) surveys and predict significant improvement in image quality with wide azimuth methods. FD modeling has provided important design parameters for two separate approaches for wide azimuth surveys: OBS nodes distributed on the ocean floor in a regular grid coupled with a dense grid of sources on the surface, and a Wide Azimuth Towed Streamer (WATS) method using multiple standard marine seismic vessels in a novel configuration. These two methods complement each other. OBS nodes may be used effectively where field development results in many obstacles that might interfere with towed streamer methods, where the required size of the 3D survey is not too extensive, or where very long offsets are required for all azimuths. The WATS method becomes more efficient as the survey size increases, and key parameters scale to provide a wide range of cost vs. data quality options that make the method suitable for field development or exploration.