Abstract:
A seal assembly including, a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface and method.

Description:
BACKGROUND 
       [0001]    Flow control seals are well known in downhole industries such as drilling and completion industries and especially so in the hydrocarbon recovery industry. Those of skill in the art will readily recognize that all manner of seals are used including compression seals, inflatable seals, etc. for different applications in the downhole environment. 
         [0002]    Compression set seals are traditionally fabricated from flexible rubber material. The seals are set by an axial force that may be applied mechanically by, for example, decreasing the weight of a tubing string supported by equipment uphole such as a derrick. Applying an axial force to the seal expands the seal such that the seal contacts the walls of a borehole. And while compression set seals are some of the oldest seals, and indeed some of the most reliable seals, the art is always receptive to improvements in performance. 
       SUMMARY 
       [0003]    A seal assembly including, a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface. 
         [0004]    A method for sealing a borehole includes applying a first axial force to a seal system operative to actuate a first seal assembly, applying a second axial force greater than the first axial force operative to actuate a second seal assembly. 
         [0005]    A seal assembly system includes a first seal assembly and a second seal assembly each having a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Referring now to the drawings wherein like elements are numbered alike in the several figures: 
           [0007]      FIG. 1  is a perspective partially cut away view of an exemplary embodiment of a seal assembly; 
           [0008]      FIG. 2  is a perspective view of an exemplary embodiment of the force transmission portion of the seal assembly of  FIG. 1 ; 
           [0009]      FIG. 3  is a side cut-away view of the assembly of  FIG. 1 ; 
           [0010]      FIGS. 4A-4C  illustrate an exemplary method for setting seals; 
           [0011]      FIG. 5  is a perspective view of an alternate embodiment of a seal assembly; and 
           [0012]      FIG. 6  is an alternate embodiment of a force transmission portion. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]      FIG. 1  illustrates a perspective partially cut away view of an exemplary embodiment of a seal assembly  10 . The assembly  10  includes a deformable force transmission portion  12 , which may be tubular in geometry. An outer seal portion  14  is positioned adjacent to, and in one embodiment sealed to, an outer diameter surface of the force transmission portion  12 . An inner seal portion  16  is positioned adjacent to, and in one embodiment sealed to, an inner diameter surface of the force transmission portion. The outer seal portion  14  and the inner seal portion  16  may be formed from a flexible material such as, for example, rubber. The force transmission portion  12  may be formed from metal, plastic, or a composite material. The force transmission portion  12  functions to resist a compressive load being applied to the seal  10  so that the same load may be transmitted thorough the seal  10  in order to be used downhole thereof. In one iteration, the use to be made of the force downhole of the seal  10  is as an actuation force. As noted above, compressive forces from uphole of a compressively set seal are traditionally not available downhole of the seal since those forces are reacted out by the radial expansion of the seal into contact with parametrical walls of the annulus in which they are positioned. Once the compression set seal is compressed into sealing contact, much if not all of the compressive load from uphole thereof can be borne by the compression set seal and hence does not transmit therethrough. Because of the configuration taught herein including the force transmission portion  12 , compressive setting force can indeed be used downhole of the seal  10 . This is effected by delaying the setting of the seal  10 . 
         [0014]    The seal assembly  10  is capable of transmitting a compressive axial force through the force transmission portion  12 , and due thereto, to components downhole of seal assembly  10 . This occurs while a threshold compressive force is not achieved whereat the seal  10  will itself set. Therefore depending upon the selected threshold force dictated by the ability of the force transmission portion to hold a load without itself deforming, other tools including seals, slips, or any other mechanically activated device downhole may be set (at lower threshold loads than the seal  10 ) prior to seal  10  setting and effectively preventing the application of compressive force downhole thereof thereafter. It is to be understood that multiple seals  10  may be used in a single system with increasing threshold compression set levels toward a surface location and setting of all of these is effectible through the compression set concept noted herein. 
         [0015]    After more downhole components are set, the seal assembly  10  may be set by applying a compressive axial force of greater than the threshold force to the seal assembly  10  that is sufficient to deform the force transmission portion  12 . At this point the seal  10  will set substantially normally. It is noted that a byproduct of the teaching hereof may be that the seal  10  is energized to a greater degree than traditional compression set seals because of the embedded force transmission portion that will tend to want to stay deformed once deformation thereof is effected. This is because it is contemplated that the deformation of the portion  12  is plastic deformation somewhere beyond the yield point of the material employed. 
         [0016]    While it is to be appreciated that a number of different shaped of force transmission portions  12  could be used, as illustrated, the profile of the force transmission portion  12  has a greater outer diameter in the center of the force transmission portion  12  relative to the ends. This encourages a more uniform deformation of the portion  12  thereby avoiding seal contact pressure irregularities. Other embodiments may include a force transmission portion  12  having a greater outer diameter that is offset from the center resulting in an asymmetrical profile. 
         [0017]    Referring to  FIG. 2 , a perspective view of an exemplary embodiment of the force transmission portion  12  alone, without the balance of the seal assembly  10  provides a greater understanding of the configuration and therefore working of the portion  12 . In the illustrated embodiment, circumferential lines  11  and  13  indicate areas of higher bending stress where the portion  12  will tend to yield under compressive load at the selected threshold level. 
         [0018]      FIG. 3  illustrates a side cut-away view of the seal assembly  10 . The force transmission portion  12  has an outer diameter at the center of the force transmission portion  12  that is greater than the outer diameter of the ends of the force transmission portion  12 . The main axis of the assembly  10  is represented by line  38 . 
         [0019]      FIGS. 4A-4C  illustrate an example of the operation of an array of seal assemblies  10  in an arrangement  400 . Referring to  FIG. 4A , a force  4  is transmitted through the tubing string  2  through the seal assemblies  10   a  and  10   b  such that the force  4  actuates a downhole tool  6  (which could be another compression set seal or some other tool responsive to compressive load). The axial force  4  may be applied mechanically by, for example, decreasing support of the weight of a tubing string  2  by, for example, a derrick at the surface (not shown). Referring to  FIG. 4B , once the tool  6  is set, the force  4  is increased such that the force is greater than the threshold setting force of the seal assembly  10   b  (but less than the threshold setting force for the seal assembly  10   a ); setting the seal assembly  10   b . Referring to  FIG. 4C , once the seal assembly  10   b  is set, the force  4  is increased above the threshold setting force for the seal assembly  10   a , resulting in the setting of the seal assembly  10   a.    
         [0020]      FIG. 5  illustrates a perspective view of an alternate embodiment of a seal assembly  50  having a force transmission portion  52 , an outer seal portion  54 , and an inner seal portion  56 . The seal assembly  50  is similar to the seal assemblies described above, however, a force transmission portion  52  includes threaded ends  60  that may be used to connect or link the assembly  50  to downhole and uphole equipment. This configuration would allow transmission of a tensile force through the seal. Where this force could be used to activate devices either before or after the elements were set. 
         [0021]      FIG. 6  illustrates another alternate embodiment of a force transmission portion  70 . The force transmission portion  70  comprises a plurality of ribs  72  arranged radially about the rotational axis of a seal assembly. The force transmission portion  70  operates similarly to the force transmission portions described above. 
         [0022]    While one or more 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.