US20090071641A1 - Expandable metal-to-metal seal - Google Patents

Abstract

A seal includes a seal body configured to form a teardrop shaped seal member upon axial compression of the seal body; a gauge ring in operable communication with the seal body and capable of applying an axial load on the seal body and method.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 11/854,950, filed Sep. 13, 2007, the entire contents of which is incorporated herein by reference.
BACKGROUND
• In the hydrocarbon recovery arts, seals are endlessly used to effect working conditions supportive of desired production fluid recovery. In recent years engineering and development dollars have been spent attempting to improve both pressure holding capacity and longevity. One type of seal receiving significant interest is a metal-to-metal seal due to the fact that of many types metal seals exhibit high temperature tolerance, high-pressure capability, robust chemical resistance, and high durability.
• Although there are many types of seals that utilize metal as a ceiling structure, those receiving the most attention contemporaneously with the filing of this document are heavier wall metal seals that are deformed in order to bring them into contact with another structure in a manner where seal is created against that other structure. While such seals do indeed provide all of the above noted benefits with respect to metal-to-metal seals, recovery sometimes can be difficult. Such seals experience a high degree work hardening when they are set and because of this work hardening experience loss of resilience. This is of course an issue with respect to stretching a seal out to retrieve it from the wellbore.
SUMMARY
• A seal includes a seal body having a bridge; a leg extending from the bridge; and a gauge ring in operable communication with the leg, the gauge ring including a support surface for the leg, the gauge ring interacting with the seal body to cause axial compression thereof, thereby forming a teardrop configuration of the bridge.
• A seal includes a seal body configured to form a teardrop shaped seal member upon axial compression of the seal body; a gauge ring in operable communication with the seal body and capable of applying an axial load on the seal body.
• A downhole sealed system, includes at least one tubular member of the tubular system disposed in one of radially inwardly of or radially outwardly of another component of the system; and a seal disposed annularly at the tubular member, the seal having a teardrop shaped cross section.
• A method for setting a seal in a target tubular includes axially compressing a seal; bending the bridge into a teardrop shape in sealing contact with the tubular; and substantially preventing introduction of bending stress into the leg.
BRIEF DESCRIPTION OF THE DRAWINGS
• Referring now to the drawings wherein like elements are numbered alike in the several Figures:
• FIG. 1 is a schematic view of one embodiment of a seal disclosed herein in a run in condition;
• FIG. 2 is a schematic view of the embodiment ofFIG. 1 illustrated in a set position;
• FIGS. 3A-3F represent sequential views of the seal ofFIG. 1 withdrawing from the set position during retrieval;
• FIG. 4 is a schematic view of an alternate embodiment in a run in condition; and
• FIG. 5 is the embodiment ofFIG. 4 in a set position.
DETAILED DESCRIPTION
• Initially it is to be understood that the seal created as disclosed herein performs better in one respect due to its teardrop cross sectional shape. The shape itself helps to absorb backlash in the setting force and therefore renders the seal more reliable. This is described in more detail in connection with one embodiment of a seal that forms the stated shape. It is also to be understood that although the drawings hereof illustrate a seal that bows radially outwardly, the components can easily be reversed such that the seal will bow radially inwardly such that the seal will be formed against a tubular radially inwardly disposed of the seal device rather than radially outwardly of the seal device as specifically illustrated.
• Referring toFIG. 1, an embodiment of aseal10 in accordance with this disclosure is illustrated. Theseal10 comprises aseal body12 having afirst end ring14 and asecond end ring16.Seal body12 comprises aseal bridge18 and first andsecond seal legs20 and22. The legs terminate atroots36 and38.Seal10 further includes configurations capable of causing the seal body to collapse axially into a set position such as, for example, twogauge rings24 and26, each disposed in operable communication with one end of theseal body12. While gauge rings are specifically disclosed, the terms as used herein are intended to convey any configuration capable of loading theseal body12 to set theseal10 and to be instrumental in retrieving theseal10. This “operable communication” as noted is, in one embodiment, a fixed connection to eachend ring14 and16, respectively, while in other embodiments it can float. The fixed connection as illustrated isadjacent roots36 and38. Thegauge rings24 and26 are also in supportive communication with thelegs20 and22, respectively. As can be readily seen inFIG. 1, each gauge ring includes an angled surface identified by thenumerals28 and30, respectively. Thesurfaces28 and30 are roughly parallel to thelegs20 and22 although not in contact therewith prior to the setting sequence for theseal10. Thesesurfaces28 and30 come in contact with thelegs20 and22 during the setting sequence to support the same as will be better appreciated after exposure to the operation section of this document.
• Also visible inFIG. 1 are tworadiuses32 and34 provided one on each ofgauge rings24 and26, respectively. The radiuses, in one embodiment, are in a range of about 0.13 to about 0.16 inch. While a wider range is also operable, it has been found that the range of about 0.13 to about 0.16 is effective in minimizing stress in theseal body12 during setting. This is also the purpose for which theangled surfaces28 and30 are provided. The angle of thesurfaces28 and30 is selected to coincide with the angle oflegs20 and22 as noted above in order to support these structures thereby preventing significant bending thereof during setting of theseal10. Angles forsurfaces28 and30 range in particular embodiments from about 45 degrees to about 90 degrees. As illustrated, the angles are both about 60 degrees. The range indicated has been found to work well though it is to be appreciated that angles outside the exemplary range are also contemplated but may not reduce stress inlegs20 and22 to the extent of the reduction found in the identified range.
• The prevention of bending reduces work hardening effects that would otherwise be experienced in these locations. Such reduction in work hardening effectively equates to more residual elasticity in the material of the seal in locations of the seal (legs and roots) that will be subject to bending stresses upon retrieval of the seal. During setting of the seal the bending stress is localized in thebridge18 and in retrieval, bending stress is localized in the legs and roots. Generally, materials that are somewhat ductile can be bent at least once without breaking, work hardening, of course, building within the material during this and any subsequent bending stress. Since in the disclosed seal, the configuration ensures that bending is experienced substantially only once in each localized area of theseal12, the likelihood of each localized area enduring sufficient stress to rupture is dramatically reduced. The protective action of thesurfaces28 and30 extends to both thelegs20 and22 andleg roots36 and38, respectively. By avoiding stress in these structures during setting of theseal10, the ability to retrieve theseal10, without suffering a rupture of the seal, is facilitated. It is further noted that in theseal10, nowhere is there a sharp bend of the material of theseal body12. Rather, all bends are gradual thereby spreading the stress over a broader area of the seal material. This avoids point stresses that generally create weaknesses in the seal both while being initially deformed and certainly while being retrieved. As such, embodiments of the invention alleviate the problem found in the prior art as noted above.
• One last point that should be made prior to a discussion of actuation of anexemplary seal10 is thatseal body12 is a machined part in one embodiment such that there are no, or extremely little, residual stresses in thebody12 in the position shown inFIG. 1. Little residual stress in theseal body12 prior to deformation in use is a benefit as this helps to minimize the magnitude of stresses experienced by thebody12 during setting. As the purpose of this configuration is the reduction in initial stress of thebody12, it is noted that an alternate arrangement is thatbody12 could be a preformed and stress relieved component for some applications or even a molded component for some applications. Again, the important thing is that the position illustrated at theroots36 and38 is a position of theseal body12 that should exist prior to setting of the seal, with very little residual stress. Further, stress is not introduced intoroots36 and38 during the setting of theseal10 due to the configuration of the gauge rings thereby retaining elasticity of the material of thebody12 in the legs and the roots. This is to the operator's advantage during retrieval of theseal10, as noted above.
• Referring now toFIGS. 1 and 2 simultaneously, setting ofseal10 is illustrated.Seal10 is set through the application of an axial load resulting in the space between the gauge rings diminishing. This can be effected in a number of ways including: 1) by causing at least one of the gauge rings to move toward the other of the gauge rings while the “other” gauge ring is stationary; 2) to cause one ring to move toward the “other” ring while the other ring moves away from the one ring more slowly than the one ring is moving toward the other ring; or 3) to cause one ring to move toward the other ring while the other ring is moving towards the one ring. For illustrative purposes, the drawings and description herein are directed to an embodiment wheregauge ring24 is moved whilegauge ring26 remains stationary through, for example, operable contact with an anchoring mechanism (not shown).
• Due to the shape ofbody12, one will appreciate that axial shortening thereof will necessarily cause thebody12 to bulge outwardly. What may not be immediately appreciated from the drawings, however, is the action of gauge rings24 and26 on the process. As gauge rings24 and26 are moved so that they are closer to one another, surfaces28 and30 come into contact withlegs20 and22, respectively. As contact is made in this location, thelegs20 and22 are substantially supported such that they and theroots36 and38 from which the legs extend experience very little bending stress while theseal10 is being set. Since the distance between gauge rings24 and26 is still being reduced, however, theseal body12 must necessarily still react. Due to the supported condition oflegs20 and22, a great majority of the bending stress in thebody12 is concentrated in thebridge18. The stress inbridge18 causes it to bow outwardly until it makes contact with aninside surface40 of a tubular in which theseal10 is being set. Once contact is made atsurface40, a load useful for creating the desired seal begins to build. As gauge rings24 and26 continue to be urged into closer proximity with one another it will become apparent that radiuses32 and34 are also important to reducing stress in theseal body12. In the position ofFIG. 2, it will be easily appreciated that were the radiuses to be significantly sharper, much higher stress would be experienced by theseal body12 at the contact point with such radiuses. It has been determined by the inventors hereof that a radius range of from about 0.13 inches to about 0.16 inches produces a desirably low stress in theseal body12.
• It is to be appreciated fromFIG. 2 that thebridge18 is deformed such that over an axial length thereof, more than 180 degrees of repositionment is represented. In other words, thebridge18 is deformed from relatively flat to beyond U-shaped. In the illustrated embodiment ofFIG. 2, it will be appreciated that the bridge is nearly aclosed teardrop shape44. In the condition illustrated inFIG. 2 substantial sealing force is applied to surface40 such the pressure may be held in either direction relative to seal10. Important to notice as well is that because of the teardrop shape ofbridge18, backlash in the setting system is better absorbed than in prior art sealing systems. This is because with a reduction in the sealing force at gauge rings24 and26 move slightly away from each other. When this occurs elastic resilience in thebridge18 will tend to straighten the twosides46 and48 of theteardrop shape44. This will tend to increase loading atinterface50 withsurface40 rather than to reduce loading atinterface50 which would have been common in the prior art.
• Referring now toFIGS. 3athrough3fretrieval ofseal10 is illustrated in sequence. It is important to note in this sequence of drawings the relative positions of thelegs20 and22 versus theteardrop shape44 as they are illustrated inFIGS. 3band3c.Upon review of these figures it will become apparent to one of ordinary skill in the art that theteardrop shape44 is maintained substantially intact while thelegs20 and22 and theroots36 and38 are subjected to tensile bending stress and experienced a greater degree of movement. This is beneficial since as noted above the legs and roots are protected from bending stress during initial setting of this seal. Therefore they have significantly greater elasticity than thebridge18, which has been work hardened, at this stage in use of theseal10. With reference toFIG. 3d,it can be ascertained that he bridge18 has begun to reopen but it is also important to note that theinterface50 has come out of contact withsurface40 by a significant margin at this point in the retrieval process. While more bending stress is being added to bridge18 at this point in the process a rupture is less likely to create a problem. Moving on toFIGS. 3eand3fthe seal has already been substantially withdrawn and again rupture at this point is less damaging. It will also be appreciated by the reader atlegs20 and22 androots36 and38 are now significantly deformed but because this deformation is the first bending stress experienced by those components, they are highly likely to survive that stress.
• The foregoing description might be reasonably understood to relate to only a symmetrically positioned seal. It is to be appreciated however that depending upon the type of movement utilized during the setting process it is sometimes advantageous to prepare theseal10 as a non-symmetrical device. More specifically, and utilizing one-gauge-ring movement as an example, ifgauge ring24 is moved towardgauge ring26 whilegauge ring26 is held in a stationary position it is reasonably likely that theteardrop shape44 will contact the inside surface40 (at interface50) before theseal10 is fully set. While it is subtle in the drawings utilized to exemplify the invention, careful consideration of the illustrated position ofinterface50 relative to a centerline of theseal10 will show that it is offset in the direction ofgauge ring24. This is because of the contact withsurface40 prior to fully setting of theseal10. Once contact is made atinterface50, the positioning ofside48 is relatively fixed and the positioning ofside46 will continue to change.Side46 will deflect under the impetus ofgauge ring24 to have a greater curvature than that ofside48. Because it is desirable to promote symmetry as much as practicable inteardrop44 it may be desirable in certain applications to vary a thickness of theseal body12 over its length. More specifically is possible to utilize thickness ofseal body12 to encourage early deformation in some portions of theseal body12 and delayed deformation in other portions of theseal body12. Generally speaking in order to enhance symmetry in the teardrop44 a lesser thickness at the more relatively fixed end ofseal body12 will allowside48 to more readily deform into a desirable position. Likewise, while the angles of theangled surfaces28 and30 and theradiuses32 and34 need not be symmetrical and in some applications may be better operable by being disparate. It is further to be understood that although the disclosure hereinabove describes an embodiment where each component is mirrored on both axial ends of theseal10, albeit not necessarily with the identical dimensions or shapes, the teardrop shape can still be created with asset of the identified components on but one axial side of theseal10 with the other side being simply attached to a carrier component.
• Referring now toFIGS. 4 and 5, an alternate embodiment is illustrated having aseparate material52 to enhance sealing properties of thebridge18 at a seal interface thereof and against theinside surface40. Although thematerial52 is illustrated as a separate piece from the material of the bridge, it is also contemplated that thematerial52 could be a coating on the bridge or the bridge could be that material. Whether configured as a separate piece or as a coating, thematerial52 is a relatively soft material such as soft metal like copper, gold, silver, palladium, platinum, tin, lead, bismuth, etc, or alloys of these metals that can be applied to the bridge by such methods as plating, brazing, thermal spray, sputtering, etc. or elastomers, or plastic materials such as Teflon, Polyetheretherketones (PEEK), etc. that can be applied and/or bonded by various industry recognized processes, which enhances the sealing operation by deforming easily to imperfections in theinside surface40 as well as geometric variations in the seal due to the eccentric bending that occurs therein. In all other respects, the configuration is the same as that of the foregoing disclosure.
• It should be noted that although the foregoing discussion has focused upon the creation of a seal, further contemplated is the addition of a roughened surface at the interface of the bridge and a separate structure to act as an anchoring device. The anchoring function can range from a partial anchor and a seal to an anchor alone depending upon the desired purpose of the device.
• 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 (22)

1. A seal comprising:

a seal body having:

a bridge;

a leg extending from the bridge; and

a gauge ring in operable communication with the leg, the gauge ring including a support surface for the leg, the gauge ring interacting with the seal body to cause axial compression thereof, thereby forming a teardrop configuration of the bridge.

2. A seal as claimed inclaim 1 wherein the seal body is formed such that residual stress therein is minimized.

3. A seal as claimed inclaim 1 wherein a second leg extends from the bridge at an axially opposite end of the bridge.

4. A seal as claimed inclaim 3 wherein the legs are of distinct dimensions from one another.

5. A seal as claimed inclaim 4 wherein distinct dimensions are at least one of length, thickness and angle.

6. A seal as claimed inclaim 1 wherein the support surface for the leg is at an angle relative to an orthogonal plane through the seal that is greater than about 45 degrees.

7. A seal as claimed inclaim 1 wherein the support surface for the leg is at an angle relative to an orthogonal plane through the seal that is less than about 90 degrees.

8. A seal as claimed inclaim 1 wherein the support surface for the leg is at an angle relative to an orthogonal plane through the seal that is about 60 degrees.

9. A seal as claimed inclaim 3 wherein the seal further comprises a second gauge ring having a support surface for the second leg.

10. A seal as claimed inclaim 9 wherein the support surface of the gauge ring and the second gauge ring are one of angled identically to each other or angled independently of each other.

11. A seal as claimed inclaim 1 wherein the gauge ring further comprises a radius extending from the support surface.

12. A seal as claimed inclaim 1 wherein the radius is greater than about 0.13 inches.

13. A seal as claimed inclaim 1 wherein the radius is less than about 0.16 inches.

14. A seal as claimed inclaim 11 wherein the further includes a second gauge ring having a second radius.

15. A seal as claimed inclaim 14 wherein the radiuses are different from one another.

16. A seal as claimed inclaim 1 wherein the support surface substantially prevents bending stress in the leg during setting of the seal.

17. A seal as claimed inclaim 1 wherein the bridge further comprises a soft material at a seal interface thereof.

18. A method for setting a seal in a target tubular comprising:

axially compressing the seal claimed inclaim 1;

bending the bridge into a teardrop shape in sealing contact with the tubular; and

substantially preventing introduction of bending stress into the leg.

19. The method as claimed inclaim 18 further comprising retrieving the seal by:

introducing a tensile force to the leg;

subjecting the leg to bending stress; and

substantially delaying the introduction of tensile bending stress in the bridge.

20. The method as claimed inclaim 18 further comprising substantially returning the seal to a retrievable condition prior to introducing substantial tensile bending stress into the teardrop shape.

21. A seal comprising:

a seal body configured to form a teardrop shaped seal member upon axial compression of the seal body; and

a gauge ring in operable communication with the seal body and capable of applying an axial load on the seal body.

22. A downhole sealed system, comprising:

at least one tubular member of the tubular system disposed in one of radially inwardly of or radially outwardly of another component of the system; and

a seal disposed annularly at the tubular member, the seal having a teardrop shaped cross section.

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