Methods for controlling towed marine sensor array geometry

• US 20090262601A1
• Filed: 03/24/2009
• Published: 10/22/2009
• Est. Priority Date: 04/21/2008
• Status: Active Grant

• Current Assignee: PGS Geophysical As (PGS ASA)
• Original Assignee: PGS Geophysical As (PGS ASA)
• Inventors: Lunde, Nils, Hillesund, Oyvind
• Granted Patent: US 8,976,622 B2
• Time in Patent Office: Days
• US Class Current: 367/16
• CPC Class Codes: G01V 1/3817 Positioning of seismic devices
• CPC Class Codes: G01V 1/3826 dynamic steering, e.g. by paravanes or birds
• CPC Class Codes: G01V 1/3835 measuring position, e.g. by GPS or acoustically

Abstract

A method for towing a streamer array includes moving a vessel along a body of water. Streamers are towed by vessel. A relative position is determined at selected points along each streamer with respect to the vessel. At least one of the streamers is deflected at at least one longitudinal position along the streamer in response to the determined positions to maintain the streamers in a selected geometry. The selected geometry is related to one of survey vessel heading, energy source trajectory, previously plotted sensor trajectory and a lateral separation related to distance from the towing vessel.

Claims

1. A method for towing a sensor streamer array in a body of water, comprising:

towing a plurality of sensor streamers behind a survey vessel in the water;

determining a relative position at selected points along each streamer with respect to the vessel; and

laterally deflecting at least one streamer at at least one longitudinal position therealong in response to the determined positions such that the streamers are maintained in a selected geometry in the water, in which the determined positions along each streamer substantially follow a trajectory of geodetic position of a geophysical energy source towed in the water.

2. The method of claim 1 wherein the energy source is towed by the survey vessel.

3. The method of claim 1 wherein the determining relative position comprises measuring acoustic travel time to a selected position along another streamer.

4. The method of claim 1 wherein the determining relative position comprises measuring geomagnetic direction.

5. The method of claim 1 wherein the sensor streamers comprise seismic sensors.

6. The method of claim 1 wherein the sensor streamers comprise electromagnetic sensors.

7. A method for towing a sensor streamer array in a body of water, comprising:

towing a plurality of sensor streamers behind a survey vessel in the water;

determining a relative position at selected points along each streamer with respect to the vessel; and

laterally deflecting at least one streamer at at least one longitudinal position therealong in response to the determined positions such that the streamers are maintained in a selected geometry in the water, in which the determined positions along each streamer substantially follow a geodetic path of sensors along a selected path.

8. The method of claim 7 wherein the determining relative position comprises measuring acoustic travel time to a selected position along another streamer.

9. The method of claim 7 wherein the determining relative position comprises measuring geomagnetic direction.

10. The method of claim 7 wherein the sensor streamers comprise seismic sensors.

11. The method of claim 7 wherein the sensor streamers comprise electromagnetic sensors.

12. A method for towing a sensor streamer array in a body of water, comprising:

towing a plurality of sensor streamers behind a survey vessel in the water;

determining a relative position at selected points along each streamer with respect to the vessel; and

laterally deflecting at least one streamer at at least one longitudinal position therealong in response to the determined positions such that the streamers are maintained in a selected geometry in the water, in which the determined positions along each streamer substantially follow a geodetic heading of the survey vessel.

13. The method of claim 12 wherein the determining relative position comprises measuring acoustic travel time to a selected position along another streamer.

14. The method of claim 12 wherein the determining relative position comprises measuring geomagnetic direction.

15. The method of claim 12 wherein the sensor streamers comprise seismic sensors.

16. The method of claim 12 wherein the sensor streamers comprise electromagnetic sensors.

17. The method of claim 12 wherein the geodetic heading is a geomagnetic heading.

18. A method for towing a sensor streamer array in a body of water, comprising:

towing a plurality of sensor streamers behind a survey vessel in the water;

applying a lateral deflecting force at selected positions along each streamer, the lateral deflecting force at each selected position related to a lateral distance of a forward end of each streamer from a center line of the survey vessel.