Device and method to determine shape of streamer

1. A signal generation device comprising:

a spool;

a flexible printed circuit board which surrounds the spool;

a reference signal generation unit which is disposed on the flexible printed circuit board to generate a reference signal;

an ultrasonic wave generation unit which surrounds the spool and is in contact with a contact electrode formed on the flexible printed circuit board to be supplied with power to generate an ultrasonic signal, wherein the contact electrode is formed in an area having the same height as that of the reference signal generation unit;

wherein the flexible printed circuit board includes a main portion which surrounds the spool and a sub portion which is extended from the main portion in a vertical direction; and

wherein the contact electrode is formed in an area of the main portion where the main portion and the sub portion are connected.

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 (TR 1 ).

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 (TR 2 ).

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 (TR 1 ), or a minimum distance (MDTs) between the residual ghost spectrum and a second predetermined threshold (TR 2 ), 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 (TR 1 ).

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 (TR 2 ).

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.