DEVICE AND METHOD FOR STEERING SEISMIC VESSEL

• US 20160061980A1
• Filed: 11/18/2014
• Published: 03/03/2016
• Est. Priority Date: 11/18/2013
• Status: Active Grant

• Current Assignee: Sercel SAS (CGG)
• Original Assignee: Cgg Services Sa (CGG)
• Inventors: TONCHIA, Hlne, MOULINIER, Timothe
• Granted Patent: US 9,568,630 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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: B63H 25/04 automatic, e.g. reacting to compass
• CPC Class Codes: G01V 1/3808 Seismic data acquisition, e.g. survey design
• CPC Class Codes: G01V 2210/16 Survey configurations

Abstract

System and method for steering a vessel during a marine acquisition campaign. The method includes obtaining a pre-plot track of a steered point, wherein the steered point is associated with an equipment spread towed by the vessel; calculating an offset between a past position of the vessel and a current position of the steered point; and steering the vessel along a vessel track, wherein the vessel track is calculated by shifting the pre-plot track of the steered point with at least a cross-line component of the offset.

Claims

1. A method for steering a vessel during a marine acquisition campaign, the method comprising:

obtaining a pre-plot track of a steered point, wherein the steered point is associated with an equipment spread towed by the vessel;

calculating an offset between a past position of the vessel and a current position of the steered point; and

steering the vessel along a vessel track, wherein the vessel track is calculated by shifting the pre-plot track of the steered point with at least a cross-line component of the offset.

2. The method of claim 1, wherein the equipment spread is a seismic spread.

3. The method of claim 1, wherein the steered point is located mid-point between two seismic source arrays.

4. The method of claim 3, wherein the pre-plot track of the steered point is a mean course of two pre-plot tracks of the two seismic source arrays towed by the vessel.

5. The method of claim 3, wherein the pre-plot track of the steered point is a filtered mean course of the two pre-plot tracks of the two source arrays.

6. The method of claim 1, wherein the steered point is an abstract point logically linked to the equipment spread.

7. The method of claim 1, wherein the vessel track is further shifted with an inline component of the offset relative to the pre-plot track of the steered point.

8. The method of claim 1, wherein a new vessel track is recomputed when a variation of the offset is greater than a given threshold

9. The method of claim 1, further comprising:

determining a time interval Δ

t based at least on a speed of the vessel and an inline distance traveled by the steered point; and

determining the offset as a difference between the current position of the steered point at current time t and a past position of the vessel at a past time t−

Δ

t.

10. The method of claim 2, wherein the steered point is a virtual point corresponding to a given point in the seismic spread, the virtual point being the point where the given point would be if there had been no steering of a part of the seismic spread that includes the given point.

11. A method for steering a vessel during a marine seismic acquisition campaign, the method comprising:

determining a variation (δ

) of a cross-line component (CO) of an offset between a past position of a vessel and a current position of a steered point (P) associated with a marine seismic spread towed by the vessel during the campaign; and

offsetting a current track of the vessel with the variation (δ

) when the variation (δ

) is larger than a given threshold.

12. The method of claim 11, wherein the steered point (P) is one of a center of the source array, a midpoint between source arrays, a center of a front end of streamers and a midpoint between the source arrays and a center of the front end of the streamers.

13. The method of claim 11, further comprising:

calculating an inline offset (IO) between a path over ground of the steered point (P) and a path over ground of the vessel.

14. The method of claim 13, further comprising:

determining the offset to be a vector having a first component the cross-line offset and the second component the inline offset.

15. The method of claim 11, wherein the vessel advances along an inline direction and the cross-line offset is calculated along a cross-line direction, which is substantially perpendicular on the inline direction and within a plane substantially parallel to the water surface.

16. The method of claim 11, further comprising:

generating in a control device commands for steering the vessel along the vessel track that is offset by the variation (δ

) relative to the current track.

17. The method of claim 11, further comprising:

determining an inline offset (IO) along the inline direction, between the past position of the vessel and the current position of the steered point (P); and

offsetting the current path of the vessel with the inline offset (IO) prior to determining the cross-line offset (CO) between the vessel and the steered point (P) during the campaign.

18. The method of claim 11, further comprising:

receiving a pre-plot track of the steered point (P), where the pre-plot track includes a change in direction; and

further offsetting the current track of the vessel based on the change in direction.

19. The method of claim 11, further comprising:

receiving a pre-plot track associated with the steered point (P);

storing in a control device a cable model that describes an interaction between the vessel and the marine spread associated with the steered point;

receiving environmental conditions; and

computing a new track of the vessel based on the offset, the pre-plot track of the steered point, the cable model and the environmental conditions.

20. A navigation system configured to steer a vessel and associated seismic equipment, the system comprising:

a global positioning system configured to generate a first position for the vessel and a second position for the associated seismic equipment; and

a navigation module that obtains a pre-plot track of a steered point, wherein the steered point is associated with the associated seismic equipment towed by the vessel, calculates an offset between a past position of the vessel and a current position of the steered point, and steers the vessel along a vessel track, wherein the vessel track is calculated by shifting the pre-plot track of the steered point with at least a cross-line component of the offset.