US20120175846A1

US20120175846A1 - Threaded device with metal to metal seal and method

Info

Publication number: US20120175846A1
Application number: US13/004,579
Authority: US
Inventors: Marcelle H. Hedrick
Original assignee: Baker Hughes Inc
Current assignee: Baker Hughes Holdings LLC
Priority date: 2011-01-11
Filing date: 2011-01-11
Publication date: 2012-07-12

Abstract

A device including a metal to metal seal. The device includes a first section having a first threaded portion. A second section having a second threaded portion threadably engageable with the first threaded portion. A metal bump seal protruding radially from the first section and spaced from the first threaded portion, wherein a radially directed seal is formed with the second section. Also included is a method for sealing a device.

Description

BACKGROUND

Metal to metal seals may be utilized in lieu of elastomeric seal rings to seal in bores in downhole well tools in hostile environments, such as high-pressure and/or high-temperature environments, when the use of elastomeric sealing materials face limits with respect to reliability and durability. Seal failures can have undesirable consequences, require costly repairs, and cause lost production. Metal to metal seals have been shown to have significant reliability, durability and resistance in the most extreme conditions. Conventional metal to metal seals incorporate load shoulders which must make contact in order to achieve the appropriate seal. That is, such static metal to metal seals consist of a face seal that must be compressed into a seat for the seal to work. Should the seal be moved even slightly, then the integrity of the seal would be compromised. As oil and gas wells have been drilled into formations experiencing increased pressure and in deeper and deeper ocean waters, a need exists for reliable metal to metal sealing between sections of wellbore tools.

BRIEF DESCRIPTION

A device including a metal to metal seal, the device includes a first section having a first threaded portion; a second section having a second threaded portion threadably engageable with the first threaded portion; and a metal bump seal protruding radially from the first section and spaced from the first threaded portion, wherein a radially directed seal is formed with the second section.
A method of sealing a device including a first tubular section and a second tubular section, the method includes threadably connecting the first tubular section to the second tubular section with a threaded connection; engaging a first metal bump seal adjacent a first end of the threaded connection between the first and second tubular sections to form a radially directed metal to metal seal at a first contact stress; and applying pressure to create a second contact stress higher than the first contact stress with the metal bump seal.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a cross-sectional view of an exemplary embodiment of a threaded device incorporating a metal to metal seal usable in a wellbore tool;

FIG. 2 is a cross-sectional view of another exemplary embodiment of a threaded device incorporating a metal to metal seal; and,

FIG. 3 is a cross-sectional view of yet another exemplary embodiment of a threaded device incorporating a metal to metal seal.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
With reference to FIG. 1, in one exemplary embodiment, a device 30 including a metal to metal seal incorporates metal bump seals 32, 34 at both ends of a threaded connection 36, that is, the lead in area 38 before thread 36 and the lead out area 40 after the thread 36. In another exemplary embodiment shown in FIG. 2, a device 50 including a metal to metal seal incorporates the metal bump seal 34 at a first end of a threaded connection 36, such as the lead out area 40 of the threaded connection 36, and in yet another exemplary embodiment shown in FIG. 3, a device 60 includes a metal to metal seal that incorporates the metal bump seal 32 at a second end of a threaded connection 36, such as the lead in area 38 of the threaded connection 36.
As is understood in the art of threaded connections, the screw thread is a helical structure used to convert between rotational and linear movement. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix. A threaded connection includes both a section having an external thread, also known as a male portion or vernacularly a pin thread, and a section having an internal thread, also known as a female portion or vernacularly a box thread. In one exemplary embodiment, the section having the external thread may be one of a liner, liner hanger, casing, production string, work string, drill string, or other tubular connections that may benefit from a metal to metal seal, and the section having an internal thread may be another of a liner, liner hanger, casing, production string, work string, drill string, or other tubular connection, such that the sections are threadably secured together by the threads and sealed together by the metal to metal seal. When the device is used in a downhole environment, the device may be sealed such that an inner annulus is sealed from an outer annulus._[mmh1]As will be further described below, the use of the device in a downhole environment takes advantage of the pressure within the downhole environment to assist in the sealing process of the metal to metal seal. However, the device may also be employable in areas outside of a downhole environment. Thus, a first tubular section that employs internal or external threads is threaded and sealed to a second tubular section that employs the other of internal or external threads using the metal to metal seal of the present invention. For the purposes of this description, the first tubular section will be described as a box 42 and incorporates the internal threads 44 on its inner diameter and the second tubular section will be described as a pin 46 and incorporates the external threads 48 on its outer diameter. Also as shown in FIGS. 1-3, in an exemplary embodiment, the box 42 and the pin 46 employ tapered conical faces that carry the threads 44, 48 on their respective inner and outer faces. However, in an alternative exemplary embodiment, the box 42 and pin 46 may include cylindrical inner and outer thread carrying faces.
The metal bump seals 32, 34 are shown as integrally formed bumps that extend from the pin 46. As shown in FIGS. 1 and 3, a first bump 32 is provided on the lead in area 38 before the thread 36, and as shown in FIGS. 1 and 2, a second bump 34 is provided on the lead out area 40 after the thread 36. The first bump 32 is spaced a first distance D1 from the first end of the threaded connection 36 and the second bump 34 is spaced a second distance D2 from the second end of the threaded connection 36.
While the threads 36 are helically arranged about the outer diameter of the pin 46 and box 42, the first and second bumps 32, 34 may radially surround the pin 46 or radially protrude from an interior of the box 42. A cross-section of the bumps 32, 34 may by rounded, such as semi-circular shaped, however other cross-sections are also within the scope of these embodiments, including, but not limited to, flattened curved shapes, rectangular shapes, trapezoidal shapes, etc. The shape is selected to provide an interference fit with a mating portion of the pin 46 or box 42. Also, while the metal bump seals 32, 34 are shown as extending from the outer diameter of the pin 46, they may also extend from the inner diameter of the box 42. In yet another exemplary embodiment, the first bump 32 may extend from one of the pin 46 and the box 42 and the second bump 34 may extend from the other of the pin 46 and the box 42. While the first and the second bumps 32, 34 are described and shown as manufactured integrally with the pin 46 and/or the box 42, it is also within the scope of these embodiments to add the first and second bumps 32, 34 subsequent to the manufacture of the pin 46 and/or the box 42, such as by welding the metal bumps _[mhh2] 32, 34 thereon or therein. In such an exemplary embodiment, the welded material may or may not be identical to the base material.
As shown in FIG. 1, the inclusion of bumps 32, 34 on both the box 42 and the pin 46 creates an atmospheric pressure trap between the bumps 32, 34, which, when the device 30 is run into a well bore, facilitates the initial sealing mechanism. That is, the interference fit between the first and second bumps 32, 34 and their respective mating portions on the box 42 or pin 46 generates a first contact stress. Then, when the device 30 is run into a well bore, pressure is applied from the downhole environment and the differential pressure creates a second contact stress greater than the first contact stress. Thus, with the first and second bumps 32, 34 at opposing ends of the threaded connection 36, the atmospheric pressure trap is created between the first and second bumps 32, 34.
The bumps 32, 34 can be manufactured on either the box 42 or the pin 46, depending on which direction the pressure is desired to be held, that is, external pressure as shown in FIG. 2, internal pressure as shown in FIG. 3, or both as shown in FIG. 1. The bumps 32, 34 can be used singly on just the pin 46, or singly on just the box 42, or dually on both the box 42 and the pin 46. However, should the device, such as device 50 or device 60, be manufactured with only one bump seal 32, 34, either on the box 42 or the pin 46, the device 50 or 60 will still function, but will not have the advantage provided by the atmospheric pressure trap as with device 30.
The bumps 32, 34 are manufactured with an interference fit relative to the mating part or surface. The mating surface, that is the part upon which the bumps 32, 34 engage in operation, may include surface preparation, such as a coating, to prevent galling during assembly for long term corrosion prevention, which inevitably assists in the sealing between the bumps _[mhh3] 32, 34 and their respective mating surfaces by prolonging the life of the surfaces. In some exemplary embodiments, surface preparations may include surface treatments for the bumps 32, 34 such as surface hardening, for example, ion nitriding or carburization. Surface preparations may also include polished finishes on the mating surfaces opposite the bumps 32, 34. _{[mhh4] [mhh5]} Upon application of pressure, such as from a downhole environment, the differential pressure creates a higher contact stress, that is, provides boost, and the bump 32 or 34 seals even tighter thereby allowing application of high pressures.
Another advantage of using these embodiments of the metal to metal seal 32, 34 is that it is able to accommodate differences in makeup loss of the connection itself. That is, while other styles of metal to metal sealing threads incorporate load shoulders which must make contact in order to achieve the appropriate seal, the exemplary embodiments of the seal of the present invention can land anywhere on its mating surface and still be able to create a seal.
Thus, a metal to metal seal capable of sealing a threaded connection 36 between a box 42 and pin 46 has been described. The metal to metal seal incorporates a first and/or second bump 32, 34 to form a radially directed seal between the box 42 and pin 46. The metal to metal seal is able to fit in small cross sectional areas, utilizes initial contact stress to initiate the seal at low pressures and utilizes applied pressure to generate boost pressure for high pressure sealing. Also, the metal to metal seal advantageously accommodates variations in thread makeup lengths and does not depend on landing on a torque shoulder to create the seal. Thus, a method of sealing a threaded connection 36 using the metal to metal seal is made possible. Additionally, by running a device incorporating the threaded connection 36 in a downhole environment, the pressure within the environment facilitates the initial sealing mechanism to create a higher contact stress.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

Claims

1. A device including a metal to metal seal, the device comprising:

a first section having a first threaded portion;

a second section having a second threaded portion threadably engageable with the first threaded portion; and

a metal bump seal protruding radially from the first section and spaced from the first threaded portion, wherein a radially directed seal is formed with the second section.

2. The device of claim 1, wherein the first and second threaded portions include one of straight or tapered threads.

3. The device of claim 1, wherein the first and second sections are tubular.

4. The device of claim 3, wherein the first section is one of a liner hanger, liner, casing, production string, work string, and drill string and the second section is another of a liner hanger, liner, casing, production string, work string, and drill string.

5. The device of claim 1, wherein the metal bump seal is integrally formed with the first section.

6. The device of claim 1, wherein the first section and the second section are made from metal.

7. The device of claim 1, wherein the metal bump seal is a first metal bump seal adjacent a lead in area of the first threaded portion, and further comprising a second metal bump seal provided on one of the first section and the second section and adjacent a lead out area of the first threaded portion or second threaded portion.

8. The device of claim 7, wherein an atmospheric pressure trap is created between the first and second metal bump seals.

9. The device of claim 1, wherein the metal bump seal includes a cross-section forming an interference fit with a mating surface of the second section.

10. The device of claim 1, wherein the second section includes a mating surface engaged with the metal bump seal and provided with a surface preparation including a coating.

11. The device of claim 1, wherein the metal bump seal is adjacent a lead in area of the first threaded portion.

12. The device of claim 1, wherein the metal bump seal is adjacent a lead out area of the first threaded portion.

13. The device of claim 1, wherein the metal bump seal generates a first contact stress between the first and second sections.

14. The device of claim 13, wherein, upon application of external pressure, a second contact stress higher than the first contact stress is generated between the first and second sections.

15. The device of claim 14, wherein the device is run in a downhole environment to apply the external pressure.

16. The device of claim 15, wherein the metal bump seal is a first metal bump seal adjacent a lead in area of the first threaded portion, and further comprising a second metal bump seal provided on one of the first section and the second section and adjacent a lead out area of the first threaded portion or second threaded portion.

17. The device of claim 16, wherein, upon application of the external pressure, an atmospheric pressure trap is created between the first and second metal bump seals.

18. A method of sealing a device including a first tubular section and a second tubular section, the method comprising:

threadably connecting the first tubular section to the second tubular section with a threaded connection;

engaging a first metal bump seal adjacent a first end of the threaded connection between the first and second tubular sections to form a radially directed metal to metal seal at a first contact stress; and

applying pressure to create a second contact stress higher than the first contact stress with the metal bump seal.

19. The method of claim 18, wherein applying pressure includes running the device into a wellbore.

20. The method of claim 19, further comprising engaging a second metal bump seal adjacent a second end of the threaded connection and creating an atmospheric pressure trap between the first and second metal bump seals.