method and apparatus for seismic exploration using pneumatic cannons navy

摘要

AIRGUN MARINE SEISMIC SURVEY METHOD AND APPARATUS A method and apparatus for simultaneously towing and handling multiple airguns are disclosed for use in marine seismic surveying which provide for ease in handling large numbers of airguns and enabling them to stream out at a desired depth behind a submerged towing head in a long flexible streamer, or a plurality of simultaneously towed airgun streamers whose level below the surface can be changed, if desired, while the survey is progressing. A plurality of airguns are included in each streamer extending for a length behind the survey vessel for providing an effective geographic diversity in the location of the airguns which can be simultaneously fired, or can be fired with time delay, for generating very powerful large area seismic energy wave fronts travelling down through the body of water. The buoyancy of the airgun streamer is controllable to provide neutral buoyancy during towing, if desired, and slight positive buoyance to float the streamer in preparation for taking it on board the towing vessel. The streamer can be conveniently hauled on board by hauling along a roller conveyor extending over the stern and can be rolled back along this conveyor for convenient launching into use. In the preferred streamer construction described, each airgun has a generally cylindrical configuration and is of the same diameter, same length, and same weight, but its firing chamber volume can be changed and pre-set to various sizes as may be described by the user, and each airguns with interconnecting flexible semi-inflatable sleeves extending between them.