OPTICAL METHODS AND SYSTEMS IN MARINE SEISMIC SURVEYING

• US 20080008031A1
• Filed: 07/06/2006
• Published: 01/10/2008
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: WesternGeco LLC
• Original Assignee: WesternGeco LLC
• Inventors: Yang, Luren, Vigen, Erik
• Granted Patent: US 7,835,221 B2
• Time in Patent Office: Days
• US Class Current: 367/015
• CPC Class Codes: G01V 1/3835 measuring position, e.g. by GPS or acoustically

Abstract

Methods and systems for determining position of marine seismic spread components are disclosed. One method comprises exposing an underwater marine seismic spread component to an optical device, and calculating geometry of the spread component using at least some of the data obtained by the optical device, for example travel time for an optical signal to travel to and return from one or more spread elements in the spread component. The optical device may comprise one or more laser scanners, cameras, or laser scanners and cameras. The spread component may be a marine seismic source, a marine seismic streamer cable, and the like. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Claims

1. A method comprising:

(a) exposing an underwater marine seismic spread component to an optical device; and

(b) calculating geometry of the spread component using at least some of the data obtained by the optical device.

2. The method of claim 1 wherein the exposing comprises scanning an underwater marine seismic spread component with an optical signal from an optical scanner, and the calculating geometry comprises using travel time for the optical signal to travel to and return from one or more spread elements in the spread component.

3. The method of claim 2 wherein the optical scanner comprises one or more lasers to point at reflectors on the spread elements and measure the travel time.

4. The method of claim 2 wherein the step of calculating geometry of the spread component comprises producing a network of optical ranges.

5. The method of claim 2 comprising reflecting a portion of the optical signal using means for reflecting selected from 1) an optical reflector attached directly on the spread element;

2) an optical reflector integrated into the spread element; and

     3) an optically reflective surface or portion of a surface of the spread element; and

combinations thereof, with the proviso that when the optical reflector is attached to the spread element or integrated into the spread element, the optical reflector is selected from reflective means, a prism, or combinations thereof, wherein the reflective means is selected from a mirror, a reflective tape, reflective signage, reflective symbols, and combinations thereof.

6. The method of claim 2 wherein the optical signal is selected from continuous and discontinuous signals.

7. The method of claim 2 wherein the scanning comprises sending laser light pulses, and calculating geometry comprises calculation of a distance by measuring time delay of a reflected laser light pulse.

8. The method of claim 2 wherein the scanning comprises pointing the optical signal directly on a reflector or reflective surface of a single spread element.

9. The method of claim 2 wherein the scanning comprises sending laser light pulses through an optical element that bends light rays while rotating the optical element through a fanning angle sufficient to scan at least to spread elements.

10. The method of claim 9 comprising using a second optical element that bends light rays to direct the laser light pulses in a spherical sector large enough to ensure that there is a laser light pulse impinging on each spread element.

11. The method of claim 2 wherein the scanning comprises scanning with two or more optical scanners.

12. The method of claim 2 comprising identifying a reflection point as being a target point of interest, extracting a range measurement for use in a computing an optical network, and filtering out less useful range data before computing the optical network.

13. The method of claim 2 comprising adjusting optical signal beam size and/or reflector size to compensate for dispersion of the optical signal.

14. The method of claim 2 wherein the optical scanner comprises a laser, the calculating geometry occurs virtually continuously and uses one or more algorithms stored on a computer.

15. The method of claim 2 wherein the spread component is a seismic source, and the scanning comprises using a laser ranging system comprising one or more laser scanners positioned in front of the seismic source, the seismic source comprising one or more source elements, each source element having a means for reflecting on a front thereof.

16. The method of claim 15 wherein the laser scanners are located slightly below a plane roughly defined by three or more source elements.

17. The method of claim 2 wherein the spread component geometry is three-dimensional, and the scanning forms a three-dimensional optical network using at least three optical scanners, or two optical scanners used in conjunction with a depth measurement instrument.

18. The method of claim 1 wherein the exposing comprises selecting from:

a) positioning a single camera compatible with marine conditions at a first position, taking a first photographic image of the spread component, the spread component comprising at least one spread element, moving the camera to second position, and taking a second photographic image of the same spread component, measuring image coordinates of one and the same point or mark on one of the spread elements in the first and second photographic images, and determining the three dimensional coordinates of the point or mark in a stereographic model; and

b) providing two or more cameras compatible with marine conditions, positioning the two or more cameras at at least two different initial camera locations, taking at least first and second photographic images of a spread component simultaneously from the at least two different initial camera locations, the spread component comprising at least one spread element, moving at least one of the two or more cameras and taking at least a third photographic image of the spread component, measuring image coordinates of one and the same point or mark on one of the spread elements in at least the first, second, third and photographic images, and determining the three dimensional coordinates of the point or mark in a stereographic model.

19. The method of claim 18 comprising repeating the method for a plurality of points on the spread component and determining the relative positions of the spread elements making up the spread component.

20. The method of claim 18 comprising improving contrast in at least one of the photographic images obtained by providing light sources on one or more of the spread elements.

21. The method of claim 18 comprising calibrating at least one of the cameras to reduce or eliminate distortions of the lenses, deviation of a projection surface from a plane, and other effects affecting image coordinates.

22. The method of claim 21 comprising determining shape of the spread component using at least one calibrated camera, and obtaining the size of the spread component using a known baseline distance selected from a distance between the first and second positions of a single camera, a distance between two different cameras, a known or measured distance between two marks on the spread component, and a known or measured distance comprising a distance from a camera to a mark on a spread element.

23. The method of claim 18 comprising automating the method by at least one camera being a digital camera or a digital video camera interacting with a computer.

24. The method of claim 18 comprising processing the photographic images using a computer with one or more algorithms to convert pixels to desired coordinates.

25. The method of claim 20 comprising improving quality of at least one of the photographic images by means selected from 1) adjusting the intensity of the light sources;

2) using light sources that are monochromatic light sources of different wavelength to help identify the marks in the images and distinguish them;

3) positioning a laser scanner close to at least one camera and using a means for reflecting optical signals on the spread element; and

combinations thereof.

26. The method of claim 18 comprising positioning a laser scanner close to at least one camera and using a means for reflecting optical signals on the spread elements.

27. The method of claim 26 comprising measuring position and three-dimensional attitude of any spread component using means selected from an acoustic positioning system, a satellite positioning system, an inertial platform, and combinations thereof.

28. The method of claim 20 comprising positioning a laser scanner close to each camera and using means for reflecting optical signals on the spread elements.

29. The method of claim 1 wherein the calculating geometry comprises using a computer selected from a vessel-located on-board computer, a remote computer, and both.

30. The method of claim 1 wherein the exposing comprises using one or more cameras compatible with marine conditions, taking one or more photographic images of a spread component comprising one or more spread elements, measuring image coordinates of one or more marks on the spread elements in the photographic images, and determining the geometry of the spread component using the image coordinates together with at least one additional geometric measure and/or assumption.

31. The method of claim 30 wherein lights are used as the marks on the spread elements.

32. The method of claim 31 wherein different light spectra are used to differentiate the marks on the spread elements.

33. A method comprising:

(a) scanning an underwater marine seismic spread component with an optical signal from an optical scanner; and

(b) calculating geometry of the spread component using travel time for the optical signal to travel to and return from one or more spread elements in the spread component.

34. A system comprising:

(a) at least one optical device exposed to an underwater marine seismic spread component; and

(b) a calculation unit receiving data from the at least one optical device and using at least some of the data to calculate geometry of the spread component.

35. A system comprising:

(a) one or more laser scanners scanning an underwater marine seismic spread component;

(b) one or more cameras photographing the spread component; and

(c) a calculation unit receiving data from the one or more laser scanner and the one or more cameras and using at least some of the data to calculate geometry of the spread component.

36. A method comprising:

a) exposing an underwater marine seismic spread component comprising at least one spread element to optical equipment selected from

i) a camera and a laser scanner co-located with the camera;

and ii) an imaging laser scanner,

the spread elements comprising means for reflecting optical signals;

b) taking a single photograph per update cycle using the camera or capturing an image using the imaging laser scanner; and

c) identifying angles between the spread elements of the spread component using the single photograph or image, and calculating distances between spread elements using the laser scanner or imaging laser scanner, and the means for reflecting.

37. The method of claim 36 wherein the spread component has dimensions selected from one dimension, two dimensions, and three dimensions, and wherein one or more additional geometric measures are used to calculate size of the spread component.