Seismic survey vessel

A seismic survey vessel maps subsurface geology under the seabed by towing arrays of airguns that fire a pressure pulse and long streamer cables fitted with hydrophones that record the reflected sound. Modern 3D and 4D vessels tow many streamers in parallel, several kilometers long, spread wide behind the ship; PGS Ramform designs, with their broad triangular sterns, tow up to 24 streamers and run air-gun arrays of about 2,820 to 3,280 cubic inches. The vessel sails long straight survey lines at a few knots while the spread is steered by paravanes and acoustic positioning. 4D, or time-lapse, surveys repeat the same geometry over years to track how a producing reservoir drains.