Adaptable seismic source for seismic surveys and method

Patent metadata

Field	Value
Publication number	US-9921328-B2
Application number	US-201414889194-A
Country	US
Kind code	B2
Filing date	Jun 13, 2014
Priority date	Jun 13, 2013
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

Method, source array and seismic vibro-acoustic source element for seismic data acquisition. The method includes storing in a controller a library of beam form factor sets associated with a source array and corresponding regions to be surveyed; towing the source array along survey lines over the regions to be surveyed; selecting a beam form factor set from the library to be applied to the source array for each region; and actuating the source array based on the selected set of beam form factors and a position of the source array relative to the regions. Each set of beam form factors maps to a corresponding region of an area to be surveyed.

First claim

What is claimed is:

1. A method for seismic data acquisition, the method comprising:
computing beam form factor sets for a source array that includes vibratory elements, the beam form factor sets being computed based on (1) a geometry of the source array, which includes a depth and a length of the source array, (2) a size of the source array, which includes a number of the vibratory elements, and (3) a frequency range of interest to be emitted by the source array;
storing in a controller a library of the beam form factor sets, wherein the library is associated with the source array and corresponding regions to be surveyed;
towing the source array along survey lines over the regions to be surveyed;
selecting a beam form factor set from the library to be applied to the source array for each region, based on a current geometry of the source array, a current water's reflectivity, and characteristics of the region; and
actuating the source array based on the selected set of beam form factors and a position of the source array relative to the regions,
wherein each set of beam form factors maps to a corresponding region of an area to be surveyed.

2. The method of claim 1 , further comprising:
automatically and dynamically selecting a single set from the beam form factor sets for a region being traversed by the source array.

3. The method of claim 1 , further comprising:
automatically and dynamically selecting plural sets from the beam form factor sets for a region being traversed by the source array.

4. The method of claim 1 , wherein when one of the beam form factor sets is applied to the source array, a beam having a given directivity is generated.

5. The method of claim 4 , wherein the directivity is described by a vertical angle between the beam and gravity.

6. The method of claim 5 , wherein the directivity is also described by an azimuth angle of the beam.

7. The method of claim 1 , further comprising:
adjusting an illumination of a feature being surveyed as the source array advances along a survey line.

8. The method of claim 1 , wherein each vibratory element is activated by a corresponding beam form factor.

9. The method of claim 1 , wherein prior seismic data is acquired during a test survey of the area to be surveyed or retrieved from a prior seismic survey is used for the computing of the beam form factor sets.

10. The method of claim 1 , further comprising:
adjusting orientations of reflector panels associated with the source array, relative to water surface, for controlling a reflection coefficient of waves generated by the source array and propagating toward the air-water interface.

11. The method of claim 10 , further comprising:
coordinating the adjusting of the orientations of the reflector panels with the instantaneous source array emission frequency so as to continuously tune the reflection coefficient to maximize a far-field output of the source array.

12. The method of claim 1 , wherein a beam form factor set becomes a beam form filter set if the geometry of the source array and the water's reflectivity above the source array are fixed.

13. A method for generating sets of beam form factors associated with a source array, the method comprising:
receiving prior seismic data related to an area to be surveyed, wherein the area to be surveyed includes plural regions having different geological characteristics;
calculating beam form factor sets for the source array for each region based on the prior seismic data and the geological characteristics of the region; and
storing in a library the beam form factors sets,
wherein the source array includes vibratory elements, and
wherein the beam form factor sets are calculated based on (1) a geometry of the source array, which includes a depth and a length of the source array, (2) a size of the source array, which includes a number of the vibratory elements, and (3) a frequency range of interest to be emitted by the source array.

14. The method of claim 13 , wherein the geological characteristics include chalk, salt and dipping features.

15. The method of claim 13 , wherein a set of beam form factors, when applied to the source array, generate a beam having a given directivity.

16. The method of claim 15 , wherein the directivity is described by a vertical angle between the beam and gravity.

17. The method of claim 16 , wherein the directivity is also described by an azimuth angle of the beam.

18. The method of claim 13 , wherein the prior seismic data is acquired during a test survey of the area to be surveyed or from a prior seismic survey.

19. The method of claim 13 , further comprising:
calculating orientations of reflector panels associated with the source array, relative to water surface, for controlling a reflection coefficient of waves generated by the source array and propagating toward the air-water interface; and
coordinating the adjusting of the orientations of the reflector panels with the instantaneous source array emission frequency so as to continuously tune the reflection coefficient to maximize a far-field output of the source array.

Assignees

• Cgg Services Sa
• Cgg Services Sas

Inventors

• Teyssandier Benoit
• Thomas Dominique
• Dowle Robert
• Sallas John

Classifications

• G01V1/3861 Primary

  control of source arrays, e.g. for far field control · CPC title

• G01V1/3808

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

• G01V1/006 Primary

  generating single signals by using more than one generator, e.g. beam steering or focusing arrays (G01V1/13, G01V1/3861 take precedence) · CPC title