PASSIVE NOISE CANCELLING PIEZOELECTRIC SENSOR APPARATUS AND METHOD OF USE THEREOF

• US 20120163120A1
• Filed: 12/24/2011
• Published: 06/28/2012
• Est. Priority Date: 12/28/2010
• Status: Abandoned Application

• Current Assignee: Seamap USA LLC
• Original Assignee: Seamap USA LLC
• Inventors: Pearce, Richard E.
• Application Number:
  US13/337,091
• Publication Number:
  US 20120163120A1
• Time in Patent Office: Days
• US Class Current: 367/21
• CPC Class Codes: G01V 1/186 Hydrophones
• CPC Class Codes: G01V 1/201 Constructional details of seismic cables, e.g. streamers integrated optoseismic systems G01V1/226; line connectors in general H01R, transducer mountings in general G10K11/004
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence
• CPC Class Codes: G01V 1/3826 dynamic steering, e.g. by paravanes or birds
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00

Abstract

Sensors used in mapping strata beneath a marine body and/or structures on a marine body floor are described, such as in a flexible buoyancy adjustable towed array. A first sensor is a traditional acoustic sensor or a novel acoustic sensor using a piezoelectric sensor mounted with a thin film separation layer of flexible microspheres on a rigid substrate. Additional non-acoustic sensors are optionally mounted on the rigid substrate for generation of output used to reduce noise observed by the acoustic sensors. Combinations of acoustic, non-acoustic, and motion sensors co-located in rigid streamer housing sections are provided, which reduce noise associated with different sensor locations and/or localized turbulence.

Claims

1. An apparatus, comprising:

an acoustic piezoelectric sensor, comprising;

a rigid tube;

a flexible piezoelectric sensing element; and

a gap between an inner surface of said piezoelectric sensing element and said rigid tube; and

a first non-acoustic piezoelectric sensor within twenty centimeters of said acoustic piezoelectric sensor, said first non-acoustic piezoelectric sensor bonded directly to said rigid tube.

2. The apparatus of claim 1, wherein, except for said gap and any element therein, said non-acoustic piezoelectric sensor contains substantially similar elements as said acoustic piezoelectric sensor.

3. The apparatus of claim 1, further comprising:

a first zone of flexible microsphere loaded transfer adhesive proximately contacting said acoustic piezoelectric sensor, said first zone substantially filling said gap;

a second zone of non-microsphere loaded transfer adhesive proximately contacting said non-acoustic piezoelectric sensor, said second zone not directly contacting said first zone.

4. The apparatus of claim 1, said non-acoustic piezoelectric sensor directly electrically coupled to said acoustic piezoelectric sensor.

5. The apparatus of claim 1, further comprising at least one of:

electronics configured to remove at least a portion of a first output of said non-acoustic piezoelectric sensor from a second output of said acoustic piezoelectric sensor; and

a communication line configured to carry first output from said non-acoustic piezoelectric sensor and second output from said acoustic piezoelectric sensor to a processing system for post-processing, said communication line running through said rigid tube.

6. The apparatus of claim 1, said acoustic piezoelectric sensor further comprising:

an inner film surface contacting said flexible piezoelectric sensing element;

an outer film surface contacting said flexible piezoelectric sensing element;

a first conductive element contacting said outer film surface; and

a second conductive element contacting said inner film surface, said inner film surface proximate said gap.

7. The apparatus of claim 1, further comprising:

means for constraining motion of at least one of;

a y-y axis length of said flexible piezoelectric sensing element; and

a x-x axis width of said flexible piezoelectric sensing element.

8. The apparatus of claim 7, said means for constraining comprising any of:

an adhesive;

a bonding agent; and

a wrap.

9. The apparatus of claim 1, further comprising:

a second non-acoustic piezoelectric sensor circumferentially wrapped about said rigid tube within less than twenty centimeters of said acoustic piezoelectric sensor, said second non-acoustic piezoelectric sensor directly bonded to said rigid tube, said first non-acoustic piezoelectric sensor on a first side of said acoustic piezoelectric sensor, said second non-acoustic piezoelectric sensor on a second side of said acoustic piezoelectric sensor.

10. The apparatus of claim 1, said gap substantially filled with:

a plurality of flexible microspheres, said plurality of flexible microspheres proximate both;

said rigid tube; and

said flexible piezoelectric sensing element or a coating thereon.

11. The apparatus of claim 10, said plurality of microspheres configured as a compressible gas chamber responsive to pressure changes and substantially immune to overburden pressure in a marine deployed hydrophone sensing apparatus.

12. The apparatus of claim 10, said plurality of flexible microspheres comprising:

an average cross-sectional diameter of less than about one hundred micrometers.

13. The apparatus of claim 10, wherein a majority of said flexible microspheres each comprise:

a flexible plastic shell encompassing a sealed inner air chamber.

14. The apparatus of claim 10, said plurality of flexible microspheres configured to form a layer in said gap, said layer comprising an average thickness of less than about two millimeters.

15. The apparatus of claim 1, wherein said rigid tube further comprises:

a concave inner surface;

a convex outer surface; and

a channel in said convex outer surface at least partially circumferentially surrounding said rigid tube.

16. The apparatus of claim 15, further comprising:

a motion sensor, comprising;

a piezoelectric motion film circumferentially wrapped in the channel about said rigid hollow tube, said channel comprising a total volume between said rigid hollow tube and said piezoelectric motion film; and

a conductive liquid in the channel, said conductive liquid contacting both said rigid hollow tube and said piezoelectric motion film.

17. An apparatus, comprising:

an acoustic piezoelectric sensor; and

a non-acoustic piezoelectric sensor within twenty centimeters of said acoustic sensor;

said acoustic piezoelectric sensor and said non-acoustic piezoelectric sensor configured to form a single output by directly wiring output of said non-acoustic piezoelectric sensor one hundred eighty degrees out of phase to output of said acoustic piezoelectric sensor.

18. The apparatus of claim 17, said acoustic piezoelectric sensor comprising at least one of:

a man made piezoelectric crystal;

a substantially lead free piezoceramic; and

a flexible film piezoelectric polymer, comprising;

an inner film surface and an outer film surface;

a first conductive element contacting said outer film surface; and

a second conductive element contacting said inner film surface.

19. The apparatus of claim 18, said polymer comprising:

a polyvinyl idene fluoride.

20. The apparatus of claim 18, said polymer comprising a strip of material, said material comprising:

an x-x width axis, said x-x width axis configured about parallel to a direction of towing of said apparatus;

a y-y length axis, wherein a constraining element restricts movement of said flexible film piezoelectric polymer along said y-y length axis; and

a z-z thickness axis electrically responsive to motion of said apparatus.

21. A method, comprising the steps of:

using an acoustic piezoelectric sensor in a marine towed sensor;

using a non-acoustic piezoelectric sensor within twenty centimeters of said acoustic sensor; and

combining outputs of said acoustic piezoelectric sensor and said non-acoustic piezoelectric sensor.

22. The method of claim 21, said acoustic piezoelectric sensor and said non-acoustic piezoelectric sensor responding with at least a ten decibel difference to a localized turbulence.