HIGH SENSITIVITY GEOPHONE

• US 20110023614A1
• Filed: 08/03/2009
• Published: 02/03/2011
• Est. Priority Date: 08/03/2009
• Status: Active Grant

• Current Assignee: Nxtant Incorporated
• Original Assignee: Lumedyne Technologies Incorporated (Alphabet Inc.)
• Inventors: Fralick, Mark, Chisum, Brad, Waters, Richard
• Granted Patent: US 8,443,673 B2
• Time in Patent Office: Days
• US Class Current: 73/649
• CPC Class Codes: G01V 1/184 Multi-component geophones

Abstract

A geophone including a plurality of ferromagnetic masses (e.g., magnets) disposed to oscillate on one or more compliant elements (e.g., springs) in a manner that produces a steep flux gradient at one or more conductive coils is disclosed. The magnetic masses are positioned with like poles facing each other so as to compress the magnetic field gradient. The coils may be positioned in the flux gap either between the magnets, in close proximity to the magnets, or surrounding the magnets. Vibration measurements may then be detected from the movement of at least one of the magnetic masses.

Claims

1. A system for measuring vibrations comprising:

a vibration measuring apparatus; and

an output device operably connected to the vibration measuring apparatus configured to generate an indication based at least in part on vibrations measured by said vibration measuring apparatus;

said vibration measuring apparatus comprising;

a substrate having one or more integral compliant regions;

a plurality of ferromagnetic masses, each ferromagnetic mass coupled to corresponding one or more of the integral compliant regions wherein at least one of the ferromagnetic masses moves with respect to the substrate responsive to substrate acceleration, wherein at least two of the plurality of ferromagnetic masses have an inner magnetic pole disposed such that the inner magnetic poles are separated from one another by a flux gap, wherein the magnetic polarity of each inner magnetic pole is similar to the magnetic polarity of the inner magnetic pole on an opposite side of the flux gap; and

one or more coils coupled to the substrate and disposed within the flux gap where the one or more coils are exposed to a changing magnetic flux arising from motion of at least one of the ferromagnetic masses with respect to the substrate.

2. The system of claim 1, wherein the one or more coils are disposed within the flux gap between the at least two ferromagnetic masses.

3. The system of claim 1, wherein the one or more coils are disposed within the flux gap outside of the at least two ferromagnetic masses.

4. The system of claim 1, wherein the one or more coils are disposed within the flux gap surrounding the at least two ferromagnetic masses.

5. The system of claim 1, wherein the one or more coils are connected to one or more of the integral compliant regions.

6. The system of claim 1, wherein the at least two ferromagnetic masses are rigidly coupled to one another and disposed to move synchronously.

7. The system of claim 1, wherein the one or more coils comprises at least two coils that are connected in series or parallel.

8. The system of claim 5, further comprising an inertial mass that is attached to outer edges of the one or more coils.

9. The system of claim 1, wherein the plurality of ferromagnetic masses comprises six ferromagnetic masses, wherein two ferromagnetic masses are configured to detect movement in a first direction, two ferromagnetic masses are configured to detect movement in a second direction substantially perpendicular to the first direction and two ferromagnetic masses are configured to detect movement in a third direction substantially perpendicular to the first direction and the second direction.

10. A method for measuring vibrations comprising:

disposing one or more coils within a flux gap created between a plurality of ferromagnetic masses, wherein at least two of the plurality of ferromagnetic masses have an inner magnetic pole separated from one another by the flux gap, and wherein the magnetic polarity of each inner magnetic pole is similar to the magnetic polarity of the inner magnetic pole on the opposite side of the flux gap;

measuring voltage generated on the one or more coils in response to changing magnetic flux arising from motion of at least one of the ferromagnetic masses; and

generating an indication of vibrations based at least in part on the measured voltage.

11. The method of claim 10, wherein disposing the one or more coils comprises disposing the one or more coils within the flux gap between the at least two ferromagnetic masses.

12. The method of claim 10, wherein disposing the one or more coils comprises disposing the one or more coils within the flux gap outside of the at least two ferromagnetic masses.

13. The method of claim 10, wherein disposing the one or more coils comprises disposing the one or more coils within the flux gap surrounding the at least two ferromagnetic masses.

14. The method of claim 10, wherein the one or more coils are connected to one or more integral compliant regions.

15. The method of claim 10, wherein the at least two ferromagnetic masses are rigidly coupled to one another and disposed to move synchronously.

16. The method of claim 10, wherein the one or more coils are connected in series or parallel.

17. The method of claim 10, wherein the plurality of ferromagnetic masses comprises six ferromagnetic masses, wherein two ferromagnetic masses are configured to detect movement in a first direction, two ferromagnetic masses are configured to detect movement in a second direction substantially perpendicular to the first direction and two ferromagnetic masses are configured to detect movement in a third direction substantially perpendicular to the first direction and the second direction.

18. The method of claim 10, wherein generating the indication of vibrations comprises outputting the indication.

19. The method of claim 10, further comprising recording the indication to a log.

20. The method of claim 19, wherein recording the indication comprises recording the indication on a user-defined schedule.