Multivessel Coil Surveys in the Gulf of Mexico - Current State of the Art and Future Directions

A unique multiple-vessel coil seismic survey design has been used to acquire over 12,000 sq km of data in the Gulf of Mexico since 2010. The surveys were designed to improve upon the existing wide- and multiazimuth data sets by recording full-azimuth, high-fold data with offsets in excess of 12 km. The Dual Coil Shooting configuration uses four vessels (two receiver vessels with sources and two source-only vessels) sailing in 12.5-km-diameter circles; with long offsets achieved by sources shooting across the coils. Vessels shoot continuously in a series of interlinked coils that reduces the line change time associated with conventional linear surveys. The coils are placed in a pseudorandom pattern that results in random shot and receiver positions to remove any pattern that may appear in the coverage fold. With the exception of the enhanced noise attenuation scheme (to remove turn noise), largely conventional algorithms and procedures are used in coil processing. Fast-track processing results that compare existing wide-azimuth data sets with the coil data show improved base-of-salt definition and better signal-to-noise ratio.