WO2008147707A2

WO2008147707A2 - A self energizing seal element

Info

Publication number: WO2008147707A2
Application number: PCT/US2008/063699
Authority: WO
Inventors: Martin P. Coronado
Original assignee: Baker Hughes Incorporated
Priority date: 2007-05-21
Filing date: 2008-05-15
Publication date: 2008-12-04
Also published as: WO2008147707A3; RU2009147817A; EP2153016A2; CA2687824A1; US20080290602A1; WO2008147707A4; AU2008257033A1

Abstract

A self-energizing seal element includes at least one inside interference surface having a dimension smaller than an inside dimension of an annulus in which the seal is to be disposed in use, at least one outside interference surface hav ing a dimension larger than an outside dimension of the annulus in which the seal is to be disposed in use, the at least one inside interference surface being axially offset from the at least one outside interference surface and at least one angular flange extending between the at least one outside interference surface and the at least one inside interference surface and method for sealing.

Description

A SELF ENERGIZING SEAL ELEMENT

BACKGROUND OF THE INVENTION

[0001] In any downhole fluid recovery operation that includes a number of different components and potentially a number of zones, there will be required a substantial number of seals. The seals are needed to fluid restrictively assist in the joining of various components of a downhole system. Many types of seals, not surprisingly, have been developed over the years to satisfy this need. These include, among others, "Chevron" seals and elastomeric seals.

[0002] Different types of seals utilize different types of actuation mechanisms or inputs, with some being self-energizing seals and some not. Generally speaking, the seal requires some kind of external input to create the desired impediment to fluid passage such as mechanical compression of the seal (for example, axial compression), inflation, etc. There are of course seals that require nothing more than stabbing into place but, commonly, these seals are nonspecifically modified in the process of stabbing in and often thereafter are not suitable for reuse. Further, the types of seals that are designed to be self-energizing tend to comprise softer material that degrades relatively easily in the downhole environment due to the inherently chemically harsh environmental conditions by processes such as flow cutting or wear. These seals also have temperature compatibility limitations that are much more significant than the metallic components upon which they are mounted.

[0003] In view of the foregoing, and although the presently marketed seals perform acceptably, an alternative seal that is self-energizing (if necessary) while maintaining simplicity would be well received by the art.

BRIEF SUMMARY OF THE INVENTION

[0004] A self-energizing seal element includes at least one inside interference surface having a dimension smaller than an inside dimension of an annulus in which the seal is to be disposed in use, at least one outside interference surface having a dimension larger than an outside dimension of the annulus in which the seal is to be disposed in use, the at least one inside interference surface being axially offset from the at least one outside interference surface and at least one angular flange extending between the at least one outside interference surface and the at least one inside interference surface.

[0005] A method for creating a metal-to-metal seal between at least a seal element and a component at an outside dimension of a seal element includes urging the element axially into contact with the component, interferingly engaging at least a maximum annular dimension of the element with the component and inducing axial extension of the element to produce sealing stress in the element.

[0006] A method for creating a metal to metal seal includes urging a first tubular member into a second tubular member, one of the first or second tubular members carrying a metal seal element, elongating the seal element through interference with the other of the first or second tubular members and inducing a radial expansion stress in the element against the tubular interfering with the element.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Referring now to the drawings wherein like elements are numbered alike in the several Figures:

[0008] FIG. 1 is a half-section view of a self-energizing seal element; and

[0009] FIG. 2 is similar to FIG. 1 except that it contains elastomeric members for another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Referring to figure 1, a half section of a self-energizing seal element 10 is depicted. The seal element begins as a simple tubular structure and is then machined to the profile illustrated. Taken into consideration before machining is a size of annulus (not shown) that the element is intended to seal. More specifically, the dimension at an inside diameter (such as for example a mandrel) and at an outside dimension (such as for example a seal bore) is calculated such that the element to be constructed is machined to present an interference fit with the mandrel and seal bore. Dimensions facilitative of an interference fit, in combination with the profile of the element as illustrated create a sealing element that is radially deformable while maintaining the element within the elastic limit of the material thereof. Resultantly, a sealing element is presented that generates its own sealing force through radial stress created by the relative size of the seal and an annulus into which the seal is disposed. Such a seal therefore requires no external compression force to energize the seal element and provides substantial benefit to the art.

[001 1] The benefits created by the self-energizable seal element hereof are occasioned by consideration of the profile of the element itself of which figure I is an embodiment. It is to be appreciated that the machining done to a simple tubular structure creates both the interference tolerance and the radial resiliency of the seal element.

[0012] Still referring to figure 1, it is to be understood that the element 10 requires a maximum outside dimension at surfaces 12 and 14 and an inside dimension at surfaces 16 and 18 that is a minimum for the element. Consequently, a blank (not shown) for this seal element must have a minimum outside dimension equal to or greater than those of surfaces 12 and 14 and an inside dimension equal to or smaller than that defined by surfaces 16 and 18. In addition, although surfaces 12 and 14 are illustrated as having the same outside dimensions and surfaces 16 and 18 are illustrated as having the same inside dimension, this is not a requirement, but merely is one embodiment. Rather it should be noted that these surfaces 16 and 18 can have distinct dimensions to provide different contact pressure against a mandrel or seal bore, respectively, which can change the loading characteristics of the seal. Also, it is to be noted that although the element 10 is illustrated with two interference surfaces on the inside and two interference surfaces on the outside, this is but one embodiment hereof. One or more interference surfaces may be constructed on either the inside or outside dimensions of the element. Moreover, the number of interference surfaces need not be the same inside to outside. Any number of interference surfaces may be utilized, the important consideration being the relative location of the surface and grooves therebetween. This will be more specifically addressed hereunder. It is further to be understood that these dimensions are of a relative nature and are not bounded by any particular numeric range. Stated alternatively, the seal element 10 may be manufactured in any desired size; the importance is the relative location of the largest outside dimension and smallest inside dimension of the finished seal element 10. It is these surfaces that provide both the interference fit against a selected mandrel (not shown) and seal bore (not shown) and the energization of the seal due to radial compression w ithin the elastic range of the element. Other surfaces of the element 10 are of various clearance fit relative to the same mandrel and seal bore.

[0013] With respect to positioning of the interference fit surfaces relative to the clearance fit surfaces and features, the interference fit surfaces must, individually or in groups of outside and inside interference surfaces, be off set from one another in an axial direction of the element 10. It is this offset in individual or group interference fit surfaces that facilitates the self energizing of the seal element 10 by causing intermediary walls of the element 10 to move from a relative orientation that is more orthogonal to the axis of the element to a relative orientation closer to axial of the element 10. It will be appreciated that the element will lengthen axially in response to the deformation. Additionally, providing the elastic limit of the material of element 10 (metal rubber, plastic, other resilient material) is not exceeded during this deformation, the element 10 will "want" to axially shrink, radially expand and thus create its own energization with respect to sealing between the mandrel and the seal bore.

[0014] Referring still to figure 1, one embodiment is illustrated in detail. Element 10, in this embodiment, includes inside housing surfaces 20 and 22. These may be of the same inside dimension as each other or may be of different inside dimensions providing they are both clearance dimensions relative to be mandrel outside dimension upon which they are intended to fit.

[0015] Further, a pair of larger grooves (as shown; one or more are possible) 24 and 26 are disposed in the inside of element 10 along with a smaller groove 28 (again could be one or more) disposed between the two (this embodiment) interference surfaces 16 and 18. Complementarily, outside end housing surfaces 30 and 32 bound a very similar pattern of construction with a pair of (again one or more) larger grooves 34 and 36 and a smaller groove 38, each of which is offset to its mirror image on the inside of the element 10. The offset grooves create a series of angular flanges 40 extending between the end housings, the flanges together representing a zig-zag shape. The construction as such facilitates radial deflection of the element 10 and thereby, providing deflection stays within the elastic limits of the material, facilitates radial rebound and therefore sealing. [0016] Referring to FIG. 2, an alternate embodiment includes one or more seal component(s) 42, such as elastomeric, rubber, plastic or even soft metal, may be inserted into one or more of the grooves 28 and 38 to enhance the low-pressure sealing performance of the seal. Once the element 10 is in sealing engagement with the tubulars in which it is set, the elastomeric seal component(s) 42 are entirely confined by the interference fit of the metal surfaces of the element 10 thereby protecting the less robust material of the component(s) 42. Other than the addition of component(s) 42, the element 10 operates and is configured identically to that of the FIG. I embodiment.

[0017] As should be understood by those of skill in the art, the element 10 as described herein must be constructed for a relatively narrow range of mandrel and seal bore sizes to perform properly. Due to standardization of components and tight tolerances held in the downhole industry, however, these elements are constructible in bulk for a wide range of applications.

[0018] In one embodiment, because the material of element 10 in the embodiment is metal, what is achieved is a non-elastomeric unloading seal capable of high temperature and pressure with no or not significant degradation. Such a seal is of great value to the art.

[0019] While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.

Claims

1. A self-energizing seal element comprising:

at least one inside interference surface having a dimension smaller than an inside dimension of an annulus in which the seal is to be disposed in use;

at least one outside interference surface having a dimension larger than an outside dimension of the annulus in which the seal is to be disposed in use, the at least one inside interference surface being axially offset from the at least one outside interference surface; and

at least one angular flange extending between the at least one outside interference surface and the at least one inside interference surface.

2. The self-energizing seal element as claimed in claim 1 wherein the element further includes end housings bounding the element.

3. The self-energizing seal element as claimed in claim 1 wherein the at least one outside interference surface is two outside interference surfaces.

4. The self-energizing seal element as claimed in claim 3 wherein two outside interference surfaces have equal outside dimensions.

5. The self-energizing seal element as claimed in claim 3 wherein two outside interference surfaces have unequal outside dimensions.

6. The self-energizing seal element as claimed in claim 1 wherein at least one inside interference surface is two inside interference surfaces.

7. The self-energizing seal element as claimed in claim 6 wherein two inside interference surfaces have equal inside dimensions.

8. The self-energizing seal element as claimed in claim 6 wherein two inside interference surfaces have unequal inside dimensions.

9 The self-energizing seal element as claimed in claim 1 wherein the element further includes at least one groove at an inside aspect of the element or at an outside aspect of the element directly radially inwardly of the at least one outside interference surface or directly radially outwardly of the at least one inside interference surface, respectively

10. The self-energizing seal element as claimed in claim 9 wherein the at least one groove houses at least one seal component

1 1. The self-energizing seal element as claimed in claim 10 wherein the seal component is elastomeπc.

12. The self-energizing seal element as claimed in claim 10 wherein the seal component is soft metal.

13 The self-energizing seal element as claimed in claim 1 wherein the dimension larger than an outside dimension of the annulus in which the seal is to be disposed in use is larger by about 0 015"

14 The self-energizing seal element as claimed in claim 1 wherein the dimension smaller than an inside dimension of the annulus in which the seal is to be disposed in use is smaller by about 0.015".

15. A method for creating a metal to metal seal between at least a seal element and a component at an outside dimension of a seal element, the method comprising:

urging the element axially into contact with the component;

interfeπngly engaging at least a maximum annular dimension of the element with the component, and

inducing axial extension of the element to produce sealing stress in the element. 16 A method for creating a metal to metal heal comprising

urging a firbt tubular member into a second tubular member, one of the first or second tubular members carrying a metal seal element,

elongating the seal element through interterence with the other of the first or second tubular members, and

inducing a radial expansion stress in the element against the tubular intertenng with the element

17 The method as claimed in claim 16 wherein the interfering fit is at both the first and second tubulars