초록 ▼

A technique for seismic surveying is presented in which a towed array, marine seismic spread, includes a plurality of streamers and a deflector system. The deflector system laterally spreads the seismic streamers, wherein at least one streamer in the spread is deflected using more than one deflector

A technique for seismic surveying is presented in which a towed array, marine seismic spread, includes a plurality of streamers and a deflector system. The deflector system laterally spreads the seismic streamers, wherein at least one streamer in the spread is deflected using more than one deflector attached to the tow cable or streamer, and where the deflectors are not connected to a float on the sea surface. Other aspects of the technique include methods for towing such a spread and for controlling such a spread. Still other aspects include computing resources which may be used to perform the methods.

대표청구항 ▼

1. A towed-array seismic survey spread, comprising: a plurality of lead-ins operable to be towed by a vessel, wherein, each one of the plurality of lead-ins tows at least one streamer;at least one submerged positioning device attached to the each one of the plurality of lead-ins;at least another sub

1. A towed-array seismic survey spread, comprising: a plurality of lead-ins operable to be towed by a vessel, wherein, each one of the plurality of lead-ins tows at least one streamer;at least one submerged positioning device attached to the each one of the plurality of lead-ins;at least another submerged positioning device attached to either the each one of the plurality of lead-ins or a head of the at least one streamer; andwherein the positioning devices provide force in an outboard crossline direction offsetting hydrodynamical forces on the plurality of lead-ins and the at least one streamer to maintain the at least one streamer's position relative to the vessel's sail line, and wherein a number of the submerged positioning devices is equal to or greater than a number of the streamers, and the number of submerged positioning devices on each respective lead-in increases from one lead-in to the next from the lead-in closest to the vessel's sail line to the lead-in farthest from the vessel's sail line. 2. The towed-array seismic survey spread of claim 1, wherein the at least one streamer has a submerged positioning device attached to a head of the streamer, and each of the lead-ins is populated by the at least one submerged positioning device. 3. The towed-array seismic survey spread of claim 1, wherein the at least one submerged positioning device is an active device. 4. The towed-array seismic survey spread of claim 3, wherein the towed-array seismic survey spread includes a control system configured to control the active submerged positioning device. 5. The towed-array seismic survey spread of claim 1, wherein the at least one submerged positioning device is a self-stabilizing device. 6. The towed-array seismic survey spread of claim 5, wherein the self-stabilizing device is self stabilizing in its angular orientation around a given set point for the angle of attack relative to the flow. 7. The towed-array seismic survey spread of claim 5, wherein the self-stabilizing device is self-stabilizing in vertical motion around a given set point for its vertical position in the water column. 8. The towed-array seismic survey spread of claim 1, wherein the at least one submerged positioning device comprises means for generating hydrodynamical forces to maintain the streamer's position relative to the vessel's sail line. 9. The towed-array seismic survey spread of claim 8, wherein the means for generating hydrodynamical forces is an active device. 10. The towed-array seismic survey spread of claim 8, wherein the means for generating hydrodynamical forces is a self-stabilizing device. 11. The towed-array seismic survey spread of claim 1, further comprising a positioning system. 12. A method for use during a towed-array seismic survey comprising: generating hydrodynamical forces to maintain at least one streamer's position relative to a vessel's sail line, wherein the hydrodynamical forces are generated from at least one submerged positioning device having no direct physical connect to a body on the water surface and is attached to a lead-in of a streamer;providing an additional submerged positioning device attached to either the lead-in or a head of the streamer andwherein a number of submerged positioning devices is equal to or greater than a number of the streamers, and the number of submerged positioning devices on each respective lead-in increases from one lead-in to the next from the lead in closest to the vessel's sail line to the lead-in farthest from the vessel's sail line. 13. The method of claim 12, wherein generating hydrodynamical forces includes actively controlling the at least one submerged positioning device. 14. The method of claim 12, wherein each of the submerged positioning devices is self-stabilizing. 15. The method of claim 12, further comprising determining a position of selected points on a survey spread of the towed-array seismic survey. 16. The method of claim 12, further comprising independently deploying each of a plurality of streamers in the towed-array seismic survey. 17. The method of claim 12, further comprising independently retrieving each of a plurality of streamers in the towed-array seismic survey. 18. The towed-array seismic survey spread of claim 2, wherein the submerged positioning devices attached to the heads of the streamers have substantially neutral lift and actively steer the streamers. 19. The method of claim 12, wherein the additional submerged positioning device is attached to a head of the streamer, has substantially neutral lift and actively steers the streamer. 20. A towed-array seismic survey spread, comprising: a vessel;a plurality of streamers towed by the vessel;a plurality of lead-ins, each lead-in being coupled between the vessel and a corresponding streamer; anda plurality of submerged positioning devices with no direct physical connection to a body on the water surface, at least one submerged positioning device being attached to a head of each of the streamers, and at least one additional submerged positioning device being attached to one or more of the lead-ins, wherein the number of submerged positioning devices on each respective lead-in increases from one lead-in to the next from the lead-in closest to the vessel's sail line to the lead-in farthest from the vessel's sail line. 21. The towed-array seismic survey spread of claim 20, wherein at least one streamer closest to the vessel's sail line has no submerged positioning device attached to its corresponding lead-in. 22. The towed-array seismic survey spread of claim 21, wherein the spread includes an odd number of streamers, and the at least one streamer closest to the vessel's sail line is one streamer. 23. The towed-array seismic survey spread of claim 21, wherein the spread includes an even number of streamers, and the at least one streamer closest to the vessel's sail line is two streamers. 24. The towed-array seismic survey spread of claim 21, wherein the streamers disposed laterally outward of the at least one streamer closest to the vessel's sail line include one or more submerged positioning devices attached to their corresponding lead-ins. 25. The towed-array seismic survey spread of claim 20, wherein the submerged positioning devices attached to the heads of the streamers have substantially neutral lift and actively steer the streamers. 26. The towed-array seismic survey spread of claim 1, wherein the number of the plurality of submerged positioning devices is greater than the number of streamers. 27. The method of claim 12, wherein the number of the plurality of submerged positioning devices is greater than the number of streamers.