A mature oil and gas field in south Louisiana produces from multiple pay zones having various fault-related traps, simple closures, and stratigraphically controlled sands. Seismic understanding of the field is complicated by an ancestral river channel, its tributaries, and surface variances such as lakes, marshes, and canal levees. Surface access restrictions include wells, flow lines, tank batteries, and oyster beds. A careful study indicated the field to be complex, thus opening the possibility of further development if the significant subsurface parameters could be better defined. A 3-D seismic survey was planned and conducted to explore this possibility.

The 3-D survey was implemented using dynamite as the source with a "3-D swath" layout of shot-and-receiver locations. Approximately 4 sq mi (10.4 sq km) of 6-fold subsurface control was obtained with depth-point spacing equal to 82 ft (25 m) in both directions. This closely spaced control provided adequate subsurface definition of the proposed objectives. A 3-D migration algorithm was used for proper subsurface imaging of the data and yielded good fault definition. The regularly spaced 3-D migrated data were displayed in a series of equally spaced horizontal sections and printed in a movie format. These data were used by interpretive personnel to generate a set of depth maps that compare favorably with those generated in a conventional manner. Subsequent drilling in the field has demo strated the validity of the technique.

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