Dual transducer communications node including piezo pre-tensioning for acoustic wireless networks and method employing same

Patent metadata

Field	Value
Publication number	US-10697288-B2
Application number	US-201816139403-A
Country	US
Kind code	B2
Filing date	Sep 24, 2018
Priority date	Oct 13, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

An apparatus and method for securing a piezoelectric element in an electroacoustic communications node used in a downhole wireless telemetry system. An end mass is secured to the piezoelectric element. At least one fastener attaches a pre-tensioning support plate to a housing of the node. The pre-tensioning support plate and the at least one fastener impart a tensioning force to the end mass and/or the piezoelectric element when the pre-tensioning support plate and the end mass and/or the piezoelectric element are secured to the housing.

First claim

What is claimed is:

1. An apparatus for securing a piezoelectric element in an electroacoustic communications node used in a downhole wireless telemetry system, comprising:
an end mass configured to be secured to the piezoelectric element, the end mass configured to enhance transmission output or receiver sensitivity of the piezoelectric element;
a pre-tensioning support plate; and
at least one fastener that attaches the pre-tensioning support plate to a housing of the electroacoustic communications node, wherein the pre-tensioning support plate and the at least one fastener are together configured to impart a tensioning force to the end mass and/or the piezoelectric element when the pre-tensioning support plate and the end mass and/or the piezoelectric element are secured to the housing;
wherein the end mass and the pre-tensioning support plate are shaped according to one of the following:
(i) the end mass has a lip with a lip diameter, and the pre-tensioning support plate has an opening sized to accept the lip diameter of the lip such that part of the end mass fits into the opening of the pre-tensioning support plate; and
(ii) the pre-tensioning support plate has an opening having a first diameter and a second diameter, wherein the second diameter is greater than the first diameter, and the end mass has a diameter sized such that the diameter of the end mass is less than the second diameter of the pre-tensioning support plate and greater than the first diameter of the pre-tensioning support plate.

2. The apparatus of claim 1 , wherein the at least one fastener comprises one or more bolts.

3. The apparatus of claim 1 , wherein each of the at least one fastener comprises:
a threaded rod; and
a nut configured to be secured around an end of the threaded rod, to thereby impart the tensioning force to the end mass and/or the piezoelectric element.

4. The apparatus of claim 1 , wherein the at least one fastener is non-conductive to prevent an electrical connection between electrodes in the piezoelectric element through the at least one fastener.

5. The apparatus of claim 1 , further comprising a non-conductive sleeve surrounding the at least one fastener.

6. The apparatus of claim 1 , further comprising a non-conductive washer disposed between the end mass and the pre-tensioning support plate, the non-conductive washer contacting each of the end mass and the pre-tensioning support plate.

7. The apparatus of claim 1 , wherein the pre-tensioning support plate is made of a non-conductive material.

8. The apparatus of claim 1 , wherein the end mass is made of a non-conductive material.

9. The apparatus of claim 1 , wherein the piezoelectric element comprises multiple piezoelectric disks, each piezoelectric disk having at least a pair of electrodes connected in series with an adjacent piezoelectric disk.

10. The apparatus of claim 1 , wherein the piezoelectric element comprises multiple piezoelectric disks, each piezoelectric disk having at least a pair of electrodes connected in parallel with an adjacent piezoelectric disk.

11. The apparatus of claim 1 , wherein the piezoelectric element comprises a single piezoelectric disk.

12. The apparatus of claim 1 , wherein the pre-tensioning force is between 40-100 inch-ounces.

13. A method of securing a piezoelectric element in an electroacoustic communications node used in a downhole wireless telemetry system, comprising:
securing an end mass to the piezoelectric element, the end mass configured to enhance transmission output or receiver sensitivity of the piezoelectric element;
using at least one fastener, attaching the end mass and piezoelectric element to a housing of the electroacoustic communications node; and
using a pre-tensioning support plate and the at least one fastener, imparting a pre-tensioning force to the end mass and/or the piezoelectric element;
wherein the end mass and the pre-tensioning support plate are shaped according to one of the following:
(i) the end mass has a lip with a lip diameter, and the pre-tensioning support plate has an opening sized to accept the lip diameter of the lip such that part of the end mass fits into the opening of the pre-tensioning support plate; and
(ii) the pre-tensioning support plate has an opening having a first diameter and a second diameter, the second diameter being greater than the first diameter, and further comprising inserting the end mass into the opening, wherein the end mass has a diameter sized such that the diameter of the end mass is less than the second diameter of the pre-tensioning support plate and greater than the first diameter of the pre-tensioning support plate.

14. The method of claim 13 , wherein the at least one fastener comprises one or more bolts.

15. The method of claim 13 , wherein the each of the at least one fastener comprises:
a threaded rod; and
a nut configured to be secured around an end of the threaded rod, to thereby impart the tensioning force to the end mass and/or the piezoelectric element.

16. The method of claim 13 , wherein the at least one fastener is non-conductive to prevent an electrical connection between electrodes in the piezoelectric element through the at least one fastener.

17. The method of claim 13 , further comprising applying a non-conductive sleeve around the at least one fastener.

18. The method of claim 13 , further comprising:
installing a non-conductive washer disposed between the end mass and the pre-tensioning support plate.

19. The method of claim 13 , wherein the pre-tensioning support plate is non-conductive.

20. The method of claim 13 , wherein the end mass is non-conductive.

21. The method of claim 13 , wherein the pre-tensioning force is selected from a range of 40-100 inch-ounces.

22. The method of claim 13 , further comprising:
securing the end mass to the piezoelectric element using an adhesive.

23. The method of claim 13 , further comprising:
securing the end mass to the piezoelectric element using an adhesive, the adhesive being cured prior to the attaching step.

24. The method of claim 13 , further comprising:
securing the piezoelectric element to the housing using an adhesive.

25. A method of securing a piezoelectric element in an electroacoustic communications node used in a downhole wireless telemetry system, comprising:
securing an end mass to the piezoelectric element;
using at least one fastener, attaching the end mass and piezoelectric element to a housing of the electroacoustic communications node; and
using a pre-tensioning support plate and the at least one fastener, imparting a pre-tensioning force to the end mass and/or the piezoelectric element while curing an adhesive between the piezoelectric element and the housing.

Assignees

• Song Limin
• Wolf H Alan
• Smith Thomas M
• Walker Katie M
• Exxonmobil Upstream Res Co

Inventors

• Song Limin
• Wolf H Alan
• Smith Thomas M
• Walker Katie M

Classifications

• E21B47/16 Primary

  through the drill string or casing {, e.g. by torsional acoustic waves} · CPC title

• E21B41/00

  Equipment or details not covered by groups E21B15/00 - E21B40/00 · CPC title

• E21B47/01 Primary

  Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like · CPC title