Device and method for continuous data acquisition

Patent metadata

Field	Value
Publication number	US-9759827-B2
Application number	US-201314103161-A
Country	US
Kind code	B2
Filing date	Dec 11, 2013
Priority date	Nov 15, 2012
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

Method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time. The method includes a step of determining a first target spectrum for the first vibratory seismic source; a step of setting a first group of constraints for the first vibratory seismic source; and a step of generating a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum. The first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first excitation signal.

First claim

What is claimed is:

1. A method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time, the method comprising:
determining a first target spectrum for the first vibratory seismic source;
setting a first group of constraints for the first vibratory seismic source;
generating a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum,
wherein the first excitation signal is a first pseudorandom excitation signal obtained by convolving a first pseudorandom sequence and one or more constraint reciprocal filter corresponding to a constraint that is a member of the first group of constraint; and
driving the first vibratory seismic source with the first excitation signal,
wherein first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first pseudorandom excitation signal.

2. The method of claim 1 , wherein the first vibratory seismic source is a marine vibratory source.

3. The method of claim 1 , wherein the step of generating comprises:
generating the first pseudorandom sequence in the time-frequency domain;
applying a fast Fourier transform to the first pseudorandom sequence to obtain a first Fourier transform pseudorandom sequence;
convolving the first Fourier transform pseudorandom sequence with the one or more constraint reciprocal filters to obtain corresponding constraint signals (LD, LC, LV);
rescaling the first Fourier transform pseudorandom sequence based on the constraint signals; and
applying an inverse fast Fourier transform to the rescaled first Fourier transform pseudorandom sequence to create the first pseudorandom excitation signal.

4. The method of claim 3 , wherein the constraint is a displacement, velocity, acceleration, current or voltage associated with the first vibratory seismic source.

5. The method of claim 3 , further comprising:
applying a compand function (f) to the first pseudorandom sequence.

6. The method of claim 5 , wherein the compand function f is given by f(x)=sin {2 x/π}, for |x|<1, and =x/|x| elsewhere.

7. The method of claim 1 , further comprising:
determining a second target spectrum for a second vibratory seismic source, wherein the second target spectrum partially overlaps with the first target spectrum;
setting a second group of constraints for the second vibratory seismic source; and
generating a second pseudorandom excitation signal for the second vibratory seismic source based on the second group of constraints and the second target spectrum,
wherein first and second seismic traces recorded with the plural receivers can be separated when the first and second vibratory seismic sources are driven with no listening time, and simultaneously based on the first and second pseudorandom excitation signals, and
wherein the first seismic traces are generated by the first seismic source and the second seismic traces are generated by the second seismic source.

8. The method of claim 7 , wherein the first vibratory seismic source emits in a frequency range different from a frequency range of the second vibratory seismic source.

9. The method of claim 7 , wherein the first vibratory seismic source is provided at a first depth underwater and the second vibratory seismic source is provided at a second depth underwater.

10. A computing device for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time, the computing device comprising:
an interface configured to,
receive a first target spectrum for the first vibratory seismic source, and
receive a first group of constraints for the first vibratory seismic source; and

a processor connected to the interface and configured to,
generate a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum,
wherein the first excitation signal is a first pseudorandom excitation signal obtained by convolving a first pseudorandom sequence and one or more constraint reciprocal filter corresponding to a constraint that is a member of the first group of constraints, and
drive the first vibratory seismic source with the first excitation signal,

wherein first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first pseudorandom excitation signal.

11. The computing device of claim 10 , wherein the first vibratory seismic source is a marine vibratory source.

12. The computing device of claim 10 , wherein the processor is further configured to:
generate the first pseudorandom sequence in the time-frequency domain;
apply a fast Fourier transform to the first pseudorandom sequence to obtain a first Fourier transform pseudorandom sequence;
convolve the first Fourier transform pseudorandom sequence with the one or more constraint reciprocal filters to obtain corresponding constraint signals (LD, LC, LV);
rescale the first Fourier transform pseudorandom sequence based on the constraint signals; and
apply an inverse fast Fourier transform to the rescaled first Fourier transform pseudorandom sequence to create the first pseudorandom excitation signal.

13. The computing device of claim 12 , wherein the constraint is a displacement, velocity, acceleration, current or voltage associated with the first vibratory seismic source.

14. The computing device of claim 12 , wherein the processor is further configured to:
apply a compand function (f) to the first pseudorandom sequence.

15. The computing device of claim 14 , wherein the compand function f is given by f(x)=sin {2 x/π}, for |x|<1, and =x/|x| elsewhere.

16. The computing device of claim 10 , wherein the processor is further configured to:
determine a second target spectrum for a second vibratory seismic source, wherein the second target spectrum partially overlaps with the first target spectrum;
set a second group of constraints for the second vibratory seismic source; and
generate a second pseudorandom excitation signal for the second vibratory seismic source based on the second group of constraints and the second target spectrum,
wherein first and second seismic traces recorded with the plural receivers can be separated when the first and second vibratory seismic sources are driven with no listening time, and simultaneously based on the first and second pseudorandom excitation signals, and
wherein the first seismic traces are generated by the first seismic source and the second seismic traces are generated by the second seismic source.

17. The computing device of claim 16 , wherein the first vibratory seismic source emits in a frequency range different from a frequency range of the second vibratory seismic source.

18. The computing device of claim 16 , wherein the first vibratory seismic source is provided at a first depth underwater and the second vibratory seismic source is provided at a second depth underwater.

19. A non-transitory computer-readable medium including computer executable instructions, wherein the instructions, when executed by a processor, implement a method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time, the method comprising:
determining a first targ

Assignees

• Cgg Services Sa
• Cgg Services Sas

Inventors

• Sallas John
• Dowle Robert
• Ruet Laurent
• Teyssandier Benoit

Classifications

• G01V1/005 Primary

  with exploration systems emitting special signals, e.g. frequency swept signals, pulse sequences or slip sweep arrangements · CPC title

• G01V1/3808 Primary

  Seismic data acquisition, e.g. survey design · CPC title

• G01V1/38 Primary

  specially adapted for water-covered areas (G01V1/28 takes precedence) · CPC title