DEVICE AND METHOD TO DETERMINE SHAPE OF STREAMER

• US 20130077436A1
• Filed: 09/07/2012
• Published: 03/28/2013
• Est. Priority Date: 09/22/2011
• Status: Active Grant

• Current Assignee: Cgg Services Sas (CGG)
• Original Assignee: Cggveritas Services SA (CGG)
• Inventors: SOUBARAS, Robert
• Granted Patent: US 10,459,099 B2
• Time in Patent Office: Days
• US Class Current: 367/24
• CPC Class Codes: G01V 1/3808 Seismic data acquisition, e.g. survey design
• CPC Class Codes: G01V 2210/56 De-ghosting; Reverberation compensation

Abstract

A method for determining a shape of a streamer to be towed under water for collecting seismic data. The method includes receiving a velocity model for the subsurface; selecting a first profile for a streamer to be used to survey the subsurface; calculating ghosts and/or residual ghosts and/or residual ghost spectra for a plurality of reflectors of the subsurface; and determining that the first profile is appropriate for surveying the subsurface when at least one criterion, related to the ghosts, residual ghosts and/or residual ghost spectra is met.

Claims

1. A method for determining a shape of a streamer to be towed underwater for collecting seismic data regarding a subsurface, the method comprising:

receiving a velocity model for the subsurface;

selecting a first profile for the streamer to be used to survey the subsurface;

selecting plural reflectors of the subsurface;

calculating ghosts and/or residual ghosts and/or residual ghost spectra for the plurality of the reflectors; and

determining that the first profile is appropriate for surveying the subsurface when at least one criterion, related to the ghosts, and/or the residual ghosts and/or the residual ghost spectra, is met.

2. The method of claim 1, wherein the at least one criterion is a minimum distance (MDTr) between the residual ghost and a first predetermined threshold (TR1).

3. The method of claim 2, wherein the at least one criterion is met when the minimum distance (MDTr) is smaller than a first predetermined value.

4. The method of claim 1, wherein the at least one criterion is a minimum distance (MDTs) between the residual ghost spectrum and a second predetermined threshold (TR2).

5. The method of claim 4, wherein the at least one criterion is met when the minimum distance (MDTs) is smaller than a second predetermined value.

6. The method of claim 1, wherein the at least one criterion is a slope of the ghost for a given length range.

7. The method of claim 6, wherein the at least one criterion is met when slopes of the ghosts corresponding to given length ranges are above a threshold slope.

8. The method of claim 1, further comprising:

calculating, in a processor, a shot point for the plural reflectors based on the velocity model and the first profile of the streamer; and

calculating, for the plural reflectors, corresponding residual ghosts and/or residual ghost spectra based on the shot point.

9. The method of claim 1, further comprising:

selecting a second profile for the streamer when the at least one criterion is not met;

recalculating the residual ghosts and/or the residual ghost spectra for the plurality of the reflectors based on the second profile of the streamer; and

determining whether the second profile is appropriate.

10. The method of claim 1, wherein the residual ghost is calculated in a post-stack phase.

11. The method of claim 1, wherein the residual ghost is calculated in a pre-stack phase.

12. The method of claim 1, wherein the first profile is a variable-depth profile.

13. The method of claim 1, wherein the first profile is a parameterized curve.

14. A computing device programmed for determining a shape of a streamer to be towed underwater for collecting seismic data regarding a subsurface, the computing device comprising:

an interface configured to receive a velocity model for the subsurface; and

a processor connected to the interface and configured to,

select a first profile for the streamer to be used to survey the subsurface,

select plural reflectors of the subsurface,

calculate ghosts and/or residual ghosts and/or residual ghost spectra for the plurality of the reflectors, and

determine that the first profile is appropriate for surveying the subsurface when at least one criterion, related to the ghosts, and/or the residual ghosts and/or the residual ghost spectra, is met.

15. The computing device of claim 14, wherein the at least one criterion is a minimum distance (MDTr) between the residual ghost and a first predetermined threshold (TR1), or a minimum distance (MDTs) between the residual ghost spectrum and a second predetermined threshold (TR2), or slopes of the ghosts corresponding to given length ranges.

16. The computing device of claim 14, wherein the processor is further configured to:

calculate a shot point for the plural reflectors based on the velocity model and the first profile of the streamer;

calculate, for the plural reflectors, corresponding residual ghosts and/or residual ghost spectra based on the shot point;

select a second profile for the streamer when the at least one criterion is not met;

recalculate the residual ghosts and/or the residual ghost spectra for the plurality of the reflectors based on the second profile of the streamer; and

determine whether the second profile is appropriate.

17. An article comprising at least one computer-readable storage medium containing instructions that when executed causes a computer to:

receive a velocity model for the subsurface;

select a first profile for the streamer to be used to survey the subsurface;

select plural reflectors of the subsurface;

calculate ghosts and/or residual ghosts and/or residual ghost spectra for the plurality of the reflectors; and

determine that the first profile is appropriate for surveying the subsurface when at least one criterion, related to the ghosts, and/or the residual ghosts and/or the residual ghost spectra, is met.

18. The article of claim 17, wherein the at least one criterion is a minimum distance (MDTr) between the residual ghost and a first predetermined threshold (TR1).

19. The article of claim 18, wherein the at least one criterion is met when the minimum distance (MDTr) is smaller than a first predetermined value.

20. The article of claim 17, wherein the at least one criterion is a minimum distance (MDTs) between the residual ghost spectrum and a second predetermined threshold (TR2).

21. The article of claim 20, wherein the at least one criterion is met when the minimum distance (MDTs) is smaller than a second predetermined value.

22. The article of claim 17, wherein the at least one criterion is a slope of the ghost for a given length range.

23. The article of claim 22, wherein the at least one criterion is met when slopes of the ghosts corresponding to given length ranges are above a threshold slope.