Patent 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

Full Description:
BACKGROUND 
       [0001]    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. 
         [0002]    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 
       [0003]    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. 
         [0004]    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. 
         [0005]    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. 
         [0006]    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 
         [0007]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0008]      FIG. 1  is a schematic view of one embodiment of a seal disclosed herein in a run in condition; 
           [0009]      FIG. 2  is a schematic view of the embodiment of  FIG. 1  illustrated in a set position; and 
           [0010]      FIGS. 3A-3F  represent sequential views of the seal of  FIG. 1  withdrawing from the set position during retrieval. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    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. 
         [0012]    Referring to  FIG. 1 , an embodiment of a seal  10  in accordance with this disclosure is illustrated. The seal  10  comprises a seal body  12  having a first end ring  14  and a second end ring  16 . Seal body  12  comprises a seal bridge  18  and first and second seal legs  20  and  22 . The legs terminate at roots  36  and  38 . Seal  10  further includes configurations capable of causing the seal body to collapse axially into a set position such as, for example, two gauge rings  24  and  26 , each disposed in operable communication with one end of the seal body  12 . While gauge rings are specifically disclosed, the terms as used herein are intended to convey any configuration capable of loading the seal body  12  to set the seal  10  and to be instrumental in retrieving the seal  10 . This “operable communication” as noted is, in one embodiment, a fixed connection to each end ring  14  and  16 , respectively, while in other embodiments it can float. The fixed connection as illustrated is adjacent roots  36  and  38 . The gauge rings  24  and  26  are also in supportive communication with the legs  20  and  22 , respectively. As can be readily seen in  FIG. 1 , each gauge ring includes an angled surface identified by the numerals  28  and  30 , respectively. The surfaces  28  and  30  are roughly parallel to the legs  20  and  22  although not in contact therewith prior to the setting sequence for the seal  10 . These surfaces  28  and  30  come in contact with the legs  20  and  22  during the setting sequence to support the same as will be better appreciated after exposure to the operation section of this document. 
         [0013]    Also visible in  FIG. 1  are two radiuses  32  and  34  provided one on each of gauge rings  24  and  26 , 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 the seal body  12  during setting. This is also the purpose for which the angled surfaces  28  and  30  are provided. The angle of the surfaces  28  and  30  is selected to coincide with the angle of legs  20  and  22  as noted above in order to support these structures thereby preventing significant bending thereof during setting of the seal  10 . Angles for surfaces  28  and  30  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 in legs  20  and  22  to the extent of the reduction found in the identified range. 
         [0014]    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 the bridge  18  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 the seal  12 , the likelihood of each localized area enduring sufficient stress to rupture is dramatically reduced. The protective action of the surfaces  28  and  30  extends to both the legs  20  and  22  and leg roots  36  and  38 , respectively. By avoiding stress in these structures during setting of the seal  10 , the ability to retrieve the seal  10 , without suffering a rupture of the seal, is facilitated. It is further noted that in the seal  10 , nowhere is there a sharp bend of the material of the seal body  12 . 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. 
         [0015]    One last point that should be made prior to a discussion of actuation of an exemplary seal  10  is that seal body  12  is a machined part in one embodiment such that there are no, or extremely little, residual stresses in the body  12  in the position shown in  FIG. 1 . Little residual stress in the seal body  12  prior to deformation in use is a benefit as this helps to minimize the magnitude of stresses experienced by the body  12  during setting. As the purpose of this configuration is the reduction in initial stress of the body  12 , it is noted that an alternate arrangement is that body  12  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 the roots  36  and  38  is a position of the seal body  12  that should exist prior to setting of the seal, with very little residual stress. Further, stress is not introduced into roots  36  and  38  during the setting of the seal  10  due to the configuration of the gauge rings thereby retaining elasticity of the material of the body  12  in the legs and the roots. This is to the operator&#39;s advantage during retrieval of the seal  10 , as noted above. 
         [0016]    Referring now to  FIGS. 1 and 2  simultaneously, setting of seal  10  is illustrated. Seal  10  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 where gauge ring  24  is moved while gauge ring  26  remains stationary through, for example, operable contact with an anchoring mechanism (not shown). 
         [0017]    Due to the shape of body  12 , one will appreciate that axial shortening thereof will necessarily cause the body  12  to bulge outwardly. What may not be immediately appreciated from the drawings, however, is the action of gauge rings  24  and  26  on the process. As gauge rings  24  and  26  are moved so that they are closer to one another, surfaces  28  and  30  come into contact with legs  20  and  22 , respectively. As contact is made in this location, the legs  20  and  22  are substantially supported such that they and the roots  36  and  38  from which the legs extend experience very little bending stress while the seal  10  is being set. Since the distance between gauge rings  24  and  26  is still being reduced, however, the seal body  12  must necessarily still react. Due to the supported condition of legs  20  and  22 , a great majority of the bending stress in the body  12  is concentrated in the bridge  18 . The stress in bridge  18  causes it to bow outwardly until it makes contact with an inside surface  40  of a tubular in which the seal  10  is being set. Once contact is made at surface  40 , a load useful for creating the desired seal begins to build. As gauge rings  24  and  26  continue to be urged into closer proximity with one another it will become apparent that radiuses  32  and  34  are also important to reducing stress in the seal body  12 . In the position of  FIG. 2 , it will be easily appreciated that were the radiuses to be significantly sharper, much higher stress would be experienced by the seal body  12  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 the seal body  12 . 
         [0018]    It is to be appreciated from  FIG. 2  that the bridge  18  is deformed such that over an axial length thereof, more than 180 degrees of repositionment is represented. In other words, the bridge  18  is deformed from relatively flat to beyond U-shaped. In the illustrated embodiment of  FIG. 2 , it will be appreciated that the bridge is nearly a closed teardrop shape  44 . In the condition illustrated in  FIG. 2  substantial sealing force is applied to surface  40  such the pressure may be held in either direction relative to seal  10 . Important to notice as well is that because of the teardrop shape of bridge  18 , 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 rings  24  and  26  move slightly away from each other. When this occurs elastic resilience in the bridge  18  will tend to straighten the two sides  46  and  48  of the teardrop shape  44 . This will tend to increase loading at interface  50  with surface  40  rather than to reduce loading at interface  50  which would have been common in the prior art. 
         [0019]    Referring now to  FIGS. 3   a  through  3   f  retrieval of seal  10  is illustrated in sequence. It is important to note in this sequence of drawings the relative positions of the legs  20  and  22  versus the teardrop shape  44  as they are illustrated in  FIGS. 3   b  and  3   c . Upon review of these figures it will become apparent to one of ordinary skill in the art that the teardrop shape  44  is maintained substantially intact while the legs  20  and  22  and the roots  36  and  38  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 the bridge  18 , which has been work hardened, at this stage in use of the seal  10 . With reference to  FIG. 3   d , it can be ascertained that the bridge  18  has begun to reopen but it is also important to note that the interface  50  has come out of contact with surface  40  by a significant margin at this point in the retrieval process. While more bending stress is being added to bridge  18  at this point in the process a rupture is less likely to create a problem. Moving on to  FIGS. 3   e  and  3   f  the seal has already been substantially withdrawn and again rupture at this point is less damaging. It will also be appreciated by the reader at legs  20  and  22  and roots  36  and  38  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. 
         [0020]    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 the seal  10  as a non-symmetrical device. More specifically, and utilizing one-gauge-ring movement as an example, if gauge ring  24  is moved toward gauge ring  26  while gauge ring  26  is held in a stationary position it is reasonably likely that the teardrop shape  44  will contact the inside surface  40  (at interface  50 ) before the seal  10  is fully set. While it is subtle in the drawings utilized to exemplify the invention, careful consideration of the illustrated position of interface  50  relative to a centerline of the seal  10  will show that it is offset in the direction of gauge ring  24 . This is because of the contact with surface  40  prior to fully setting of the seal  10 . Once contact is made at interface  50 , the positioning of side  48  is relatively fixed and the positioning of side  46  will continue to change. Side  46  will deflect under the impetus of gauge ring  24  to have a greater curvature than that of side  48 . Because it is desirable to promote symmetry as much as practicable in teardrop  44  it may be desirable in certain applications to vary a thickness of the seal body  12  over its length. More specifically is possible to utilize thickness of seal body  12  to encourage early deformation in some portions of the seal body  12  and delayed deformation in other portions of the seal body  12 . Generally speaking in order to enhance symmetry in the teardrop  44  a lesser thickness at the more relatively fixed end of seal body  12  will allow side  48  to more readily deform into a desirable position. Likewise, while the angles of the angled surfaces  28  and  30  and the radiuses  32  and  34  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 the seal  10 , 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 the seal  10  with the other side being simply attached to a carrier component. 
         [0021]    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.

Technology Classification (CPC): 4