FIG. T-4. 3-D surveying (a)
Use of a cross-current to pull streamer off to the side; streamer positions are shown at 15 minute intervals. (b)
Use of paravanes to pull marine source arrays to the side. Paravanes are also used to pull streamers to each side; sometimes as many as 12 streamers are used with two source arrays firing alternately, giving as many as 24 parallel seismic lines on one pass with the seismic ship.