System for controlling streamers

• US 20040060498A1
• Filed: 07/23/2003
• Published: 04/01/2004
• Est. Priority Date: 01/24/2001
• Status: Active Grant

• Current Assignee: Petroleum Geo-Services AG
• Original Assignee: Petroleum Geo-Services AG
• Inventors: Petersen, Egil, Naley, Svein J., Ronningen, Rolf
• Granted Patent: US 7,047,898 B2
• Time in Patent Office: Days
• US Class Current: 114/253
• CPC Class Codes: B63B 21/66 Equipment specially adapted for towing underwater objects or vessels, e.g. fairings for tow-cables paravanes for dragging fishing nets A01K73/02; salvaging underwater vessels or objects B63C7/00; towed underwater vessels B63G8/42
• CPC Class Codes: B63H 2025/045 making use of satellite radio beacon positioning systems, e.g. the Global Positioning System [GPS]
• CPC Class Codes: G01V 1/3826 dynamic steering, e.g. by paravanes or birds

Abstract

System for controlling cables and streamers in a seismic tow arrangement comprising at least one deflector (13) connected to one side of a tow vessel (10) via at least one wire (12), leading or the like, wherein the deflector is located in a position at a distance perpendicularly to the direction of movement (5) of the tow vessel, the vessel being equipped with a navigation system for measuring the position of the vessel. The system is characterised by comprising a command unit and a number of control units, where the control units are located on at least some of the streamers and are adapted to measure and report about their positions, that the command unit comprises means for receiving the position information from each individual control unit and calculation of possible deviations from predetermined positions, and that the system comprises means for changing the position of the streamers for re-establishing the positions of the control units.

Claims

1. System for controlling cables and streamers in a seismic tow arrangement comprising at least one deflector (13) connected to one side of a tow vessel (10) through at least one wire (12), lead-in or the like, wherein the deflector is located at a position with a distance perpendicularly of the direction of movement (5) of the tow vessel, the vessel being equipped with a navigation system (32) for measuring the position of the vessel, characterised by comprising a command unit (31) and a number of control units (33), the control units being located on at least some of the streamers (14) and being adapted to measure and report regarding their positions,

that the command unit (31) comprises means for receiving position information from each individual control unit (31) and calculation of possible deviations from predetermined positions,

and that the system comprises means for changing the position of the streamers in order to restore the positions of the control unit.

2. System according to claim 1, characterised in that the position information from at least one control unit (33) comprises horizontal and vertical position.

3. System according to claim 1 or 2, characterised in that the command unit (31) comprises means for measuring the relative position of the deflector (13) with respect to the vessel (10), and that the compensation comprises control of the global position of the deflector on the background of the position of the tow vessel and the relative position of the deflector with respect thereto.

4. System according to claim 1, 2 or 3, characterised in that at least one control device (33) comprises a depth measuring instrument and that the system comprises at least one depth controller connected to the depth measuring instrument, for adjusting the vertical position thereof.

5. System according to anyone of claims 1-4, characterised in that the tow wire (12) is connected to the tow vessel (10) via control devices, for example a winch, adapted to vary the wire length from the tow vessel to the deflector (13) and that the control devices are connected to the calculating means for adjusting of the wire length on the basis of said deviation in the position of the tow vessel, in order to counteract corresponding deviations in the movement of the deflector.

6. System according to anyone of claims 1-5, characterised in that the command unit (31) also comprises means as known per se for measuring deviations in the orientation of the vessel, for example roll, heave and pitch.

7. System according to anyone of the claims 1-6, characterised in comprising means for adjusting the lifting capacity of the deflector (13) for adjusting the position of the deflector.

8. System according to anyone of the claims 1-7, characterised in the streamer (14) comprises means (33) for measurement of position, and transfer thereof to the command unit.

9. System according to anyone of the claims 1-8, characterised in that the control units (33) are located in association with selected points at the streamers (14), the deflectors (13) and the depth controllers, for measuring selected variables such as effect or power, position and depth at each individual control unit.