Low frequency marine acoustic vibrator

Patent metadata

Field	Value
Publication number	US-9618637-B2
Application number	US-201414284847-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	Sep 20, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Embodiments relate to marine acoustic vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine acoustic vibratory may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a spring element coupled to the piston plate and the fixture; and a driver coupled to the piston plate and the fixture and configured to move the piston plate back and forth.

First claim

What is claimed is:

1. A marine acoustic vibrator comprising:
a containment housing;
a first piston plate;
a second piston plate;
a fixture extending along a major axis of the containment housing, wherein the fixture is coupled to either end of the containment housing;
a first spring element coupled to the first piston plate and a first side of the fixture, a second spring element coupled to the second piston plate and a second side of the fixture, wherein the first spring element extends between the first side of the fixture and the first piston plate, and the second spring element extends between the second side of the fixture and the second piston plate; wherein the first and second spring elements each have selected spring constants to produce a first resonance frequency; and
a driver coupled to the first and second piston plates and the fixture, wherein the driver is configured to move the first and second piston plates back and forth, wherein the fixture supports the driver in the containment housing.

2. The marine acoustic vibrator of claim 1 , wherein the driver is a moving coil driver or a linear servo motor.

3. The marine acoustic vibrator of claim 1 , wherein the first and second piston plates are coupled to the housing by way of a rubber seal, the first piston plate covering a first opening in a first side of the containment housing and the second piston plate covering a second opening in a second side of the containment housing.

4. The marine acoustic vibrator of claim 1 , wherein the first and second piston plates are configured to not bend or flex during operation of the marine acoustic vibrator.

5. The marine acoustic vibrator of claim 1 , wherein the first and second spring elements comprise at least one type of spring selected from the group consisting of: a bow spring, a coil spring, a flat spring, and a leaf spring.

6. The marine acoustic vibrator of claim 1 , wherein the second spring element is disposed on an opposite side of the driver from the first spring element.

7. The marine acoustic vibrator of claim 1 , wherein the first spring element is coupled to a supplemental fixture by way of bearings, the supplemental fixture being coupled to the fixture.

8. The marine acoustic vibrator of claim 1 , wherein the marine acoustic vibrator is configured to have the first resonance frequency within a frequency range of about 1 Hz and about 200 Hz when disposed in water at a depth of about 0 meters to about 300 meters.

9. The marine acoustic vibrator of claim 8 , wherein the marine acoustic vibrator further comprises a mass spring having weights affixed thereto, the mass spring being coupled between the first side of the fixture and the first piston plate.

10. The marine acoustic vibrator of claim 9 , wherein the mass spring is configured to cause the marine acoustic vibrator to generate a second resonance frequency within the frequency range when disposed in water at a depth of about 0 meters to about 300 meters.

11. The marine acoustic vibrator of claim 8 , wherein the frequency range is from about 1 Hz to about 10 Hz.

12. A marine acoustic vibrator comprising:
a containment housing;
a fixture extending along a major axis of the containment housing, wherein the fixture is coupled to either end of the containment housing;
a first piston plate coupled to the containment housing;
a first driver disposed at least partially within the marine acoustic vibrator, the first driver being coupled to the fixture and the first piston plate, wherein the first driver is configured to move the first piston plate back and forth, wherein the fixture supports the first driver in the containment housing;
a first pair of spring elements coupled to the first piston plate and a first side of the fixture, wherein the first pair of spring elements has a selected spring constant to produce a first resonance frequency;
a second piston plate coupled to the containment housing opposite the first piston plate;
a second driver disposed at least partially within the marine acoustic vibrator, the second driver being coupled to the fixture and the second piston plate, wherein the second driver is configured to move the second piston plate back and forth, wherein the fixture supports the second driver in the containment housing; and
a second pair of spring elements coupled to the second piston plate and a second side of the fixture, wherein the second pair of spring elements has a selected spring constant.

13. The marine acoustic vibrator of claim 12 , wherein the first piston plate and the second piston plate are configured to not bend or flex during operation of the marine acoustic vibrator.

14. The marine acoustic vibrator of claim 12 , wherein at least one of the first pair of spring elements or the second pair of spring elements comprises at least one type of spring selected from the group consisting of: a bow spring, a coil spring, a flat spring, and a leaf spring.

15. The marine acoustic vibrator of claim 12 , wherein the first and second drivers, the first piston plate, the second piston plate, the first pair of spring elements, and the second pair of spring elements cause the marine acoustic vibrator to generate the first resonance frequency within a frequency range of about 1 Hz and about 10 Hz when disposed in water at a depth of about 0 meters to about 300 meters.

16. The marine acoustic vibrator of claim 12 , wherein the marine acoustic vibrator further comprises a mass spring having weights affixed thereto, the mass spring being coupled between the fixture and the first piston plate.

17. A method comprising:
providing a marine acoustic vibrator, wherein the marine acoustic vibrator comprises:
a containment housing;
a first piston plate;
a second piston plate;
a fixture extending along a major axis of the containment housing, wherein the fixture is coupled to either end of the containment housing;
a first spring element coupled to the first piston plate and a first side of the fixture, a second spring element coupled to the second piston plate and a second side of the fixture, wherein the first spring element extends between the first side of the fixture and the first piston plate, and the second spring element extends between the second side of the fixture and the second piston plate; wherein the first and second spring elements have selected spring constants; and

a driver coupled to the first and second piston plates and the fixture, wherein the driver is configured to move the first and second piston plates back and forth, wherein the fixture supports the driver in the containment housing; and
triggering the marine acoustic vibrator in a body of water in conjunction with a marine seismic survey to cause the first and second piston plates in the marine acoustic vibrator to move back and forth, such that the marine acoustic vibrator has a first resonance frequency based at least in part, on the selected spring constants, wherein the first and second spring elements exert biasing forces against the first and second piston plates.

18. The method of claim 17 , further comprising towing one or more additional marine acoustic vibrators in an array with the marine acoustic vibrator.

19. The method of claim 17 , further comprising towing the marine acoustic vibrator in the body of water.

20. The method of claim 17 , further comprising towing one or more air guns in conjunction with the marine seismic survey, and triggering the one or more air guns to generate acoustic energy.

21. The method

Assignees

• Pgs Geophysical As

Inventors

• Tenghamn Stig Rune Lennart

Classifications

• G01V1/145 Primary

  by deforming or displacing surfaces {, e.g. by mechanically driven vibroseis™} · CPC title

• G01V1/137 Primary

  which fluid escapes from the generator in a pulsating manner, e.g. for generating bursts {, airguns} · CPC title

• G01V2210/1293

  Sea · CPC title

• G01V1/159

  using piezoelectric or magnetostrictive driving means (generating mechanical vibrations by using piezoelectric or magnetostrictive effect in general, B06B1/06, B06B1/08) · CPC title

• G01V1/38

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