Acquisition geometry

The 3D dataset consists of 20 sail lines each with four active streamers and dual flip-flop shooting. The separation between streamers is 160 m and between receivers is 25 m. The shot interval is 37.5 m (between the flip and the flop). The minimum offset inline is 240 m and each streamer has 288 receivers for a maximum inline offset of 7175 m. Figure 1 shows the acquisition template. Figure 2 shows a map view of the subset of the shots used in this thesis. Although most sail lines were straight in the East-West direction, a few had significant curvature.

acq-sktch1
Figure 1. Sketch of the basic acquisition geometry

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Figure 2. Map view of the source locations.

The strong currents present in the area caused significant feathering. Figure 3 shows an example for the sail-line at cross-line distance 11440 m (see Figure 2. The feathering angle is about 25 deg with respect to the inline direction. For most shots, the feathering was in the same South-North direction. Figure 4 shows the fold of coverage that in some places depart significantly from its design value of 48. Some of the short source lines in Figure 2 were acquired as infill to avoid large coverage holes.

feathering
Figure 3. Map view of the receiver cables for one shot illustrating typical feathering. The feathering angle is about 25 deg with respect to the inline direction.

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Figure 4. Fold map illustrating relatively uniform coverage.