Abstract:
The present invention provides for an annular barrier tool to block or restrict the flow of well fluids in the annular region of a well.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application 60/539,398 filed on Jan. 27, 2004. 
     
    
     BACKGROUND  
       [0002]     1. Field of Invention  
         [0003]     The present invention pertains to downhole completion devices, and particularly to a downhole completion device in which a barrier to annular flow is established.  
         [0004]     2. Related Art  
         [0005]     It is often desirable to run a completion device such as a packer, for example, to block or restrict fluid flow through an annular region in a well. The annular region at issue is the space between the wellbore wall and a downhole tool such as production tubing or a completion assembly. Providing an annular barrier to block annular flow allows, for example, zones to be isolated.  
       SUMMARY  
       [0006]     The present invention provides for an annular barrier tool to block or restrict the flow of well fluids in the annular region of a well.  
         [0007]     Advantages and other features of the invention will become apparent from the following description, drawings, and claims. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]      FIG. 1  shows a schematic view of a seal element used in an annular barrier tool constructed in accordance with the present invention.  
         [0009]      FIG. 2  shows a schematic view of the seal element of  FIG. 1  in a first compressed state.  
         [0010]      FIG. 3  shows a schematic view of the seal element of  FIG. 1  in a second compressed state.  
         [0011]      FIG. 4  shows a schematic view of the seal element of  FIG. 1  in a third compressed state.  
         [0012]      FIGS. 5A and 5B  show external and internal schematic views, respectively, of an annular barrier tool constructed in accordance with the present invention.  
         [0013]      FIGS. 6A and 6B  show external and internal schematic views, respectively, of multiple annular barrier tools constructed in accordance with the present invention.  
         [0014]      FIG. 7  shows a schematic view of a first seal arrangement for the annular barrier tool of  FIG. 5 .  
         [0015]      FIG. 8  shows a schematic view of a second seal arrangement for the annular barrier tool of  FIG. 5 .  
         [0016]      FIG. 9  shows a schematic view of a third seal arrangement for the annular barrier tool of  FIG. 5 .  
         [0017]      FIGS. 10A and 10B  show schematic views of an alternate embodiment of an annular barrier tool constructed in accordance with the present invention.  
         [0018]      FIGS. 11A and 11B  show schematic views of an alternate embodiment of the annular barrier tool of  FIG. 10A . 
     
    
     DETAILED DESCRIPTION  
       [0019]     Referring to  FIG. 1 , a seal element  10  used in an annular barrier tool  12  (hereinafter, ABT  12 ) (see  FIGS. 5A, 5B ,  6 A, and  6 B) comprises a support  14  disposed between an outer conformable layer  16  and an inner conformable layer  18 . Conformable layers  16 ,  18  may be, for example, made of rubber, metal, thermoplastic, or an elastomeric material. Seal element  10  uses support  14  to provide structural support to conformable layers  16 ,  18  of ABT  12 .  
         [0020]     Seal element  10  is carried on a mandrel  20  of ABT  12 . A ratchet  22  is mounted on mandrel  20  near an end of seal element  10 . Seal element  10  has mating teeth to engage ratchet  22 , preventing relative motion between that end of seal element  10  and mandrel  20  in one direction. A mandrel seal  24  is carried on mandrel  20  and forms a barrier to fluid flow between mandrel  20  and seal element  10  at the end where mandrel seal  24  is located. Fluid communication exists, however, between an annulus  26  and a chamber  28  behind inner conformable layer  18 .  FIG. 1  shows seal element  10  in a relaxed or unenergized state.  
         [0021]     Conformable layers  16 ,  18  and support  14  are held between end stops  30 ,  32  ( FIG. 2 ). Outer conformable layer  16  is protected against abrasive damage by end stops  30 ,  32 . One end stop (say,  30 ) is fixed to mandrel  20 , while the opposite end stop ( 32 ), on which the mating teeth to ratchet  22  are located, is moveably mounted to mandrel  20 . Moveable end stop  32  acts as a piston when a force is applied to it. The roles of end stops  30 ,  32  may be interchanged.  
         [0022]     When pressure is applied to end stop  32 , support  14  is compressed against fixed end stop  30 , causing support  14  to deflect outward toward and ultimately against a wellbore wall  34  ( FIG. 3 ). A setting force may also be applied to end stop  32  using mechanical or chemical means. While  FIG. 3  shows the wellbore to be an open hole, ABT  12  may be used in cased holes as well. Support  14  is compressed and elastically deformed. Ratchet  22  maintains compression energy in support  14  even if the pressure on end stop  32  is removed.  
         [0023]     When support  14  is deformed sufficiently outward, outer conformable layer  16  surrounding support  14  contacts wellbore wall  34  and creates a seal between wellbore and outer conformable layer  16 . To further increase the sealing capacity, ABT  12  uses, for example, hydrostatic pressure from a high pressure zone to further increase the pressure applied by ABT  12  against wellbore wall  34  ( FIG. 4 ). Injection pressure may also be used. The seal elements  10  may be configured to be used on the up-hole side, the down-hole side, or both, simply by proper arrangement of seal elements  10 . In principle, seal element  10  works similarly to C-cup type seals.  
         [0024]     The high pressure fluid penetrates beneath inner conformable layer  18  into chamber  28  and pressures up the interior of seal element  10 . This can be achieved, for example, by a leak path past ratchet  22  or through a port through end stop  32 . The pressure further pushes outer conformable layer  16  against wellbore wall  34 , thus increasing the sealing with wellbore wall  34 . The elastic deformation of support  14  helps maintain the seal with wall  34  even with the slight variations that may occur because of, for example, changes in pressure, bore shape, and tool movement.  
         [0025]     Seal element  10  may be stacked with other seal elements  10  to form a module  36  ( FIGS. 5A and 5B ). Multiple modules  36 , such as the three shown in  FIGS. 6A and 6B , may be stacked to create an embodiment of ABT  12 .  
         [0026]     The independent seal elements  10  may be arranged within modules  36  to control how the high pressure is allowed to get inside the “dome” of chamber  28 . There are at least three possible seal arrangements: (1) facing each other ( FIG. 7 ); (2) opposite each other ( FIG. 8 ); and (3) both facing the same side ( FIG. 9 ).  
         [0027]     In the embodiment of  FIG. 7 , high pressure fluid below the lower seal element  10  slips past that seal element and enters chamber  28  of the upper seal element  10 . Similarly, high pressure fluid above the upper seal element  10  slips past that seal element and enters chamber  28  of the lower seal element  10 .  
         [0028]     In the embodiment of  FIG. 8 , high pressure fluid below the lower seal element  10  enters chamber  28  of the lower seal element  10 . Similarly, high pressure fluid above the upper seal element  10  enters chamber  28  of the upper seal element  10 .  
         [0029]     In the embodiment of  FIG. 9 , high pressure fluid above the upper seal element  10  enters chamber  28  of the upper seal element  10 . If any high pressure fluid leaks past the upper seal element  10 , it enters chamber  28  of the lower seal element  10 . In all three embodiments, there is no fluid communication between the annular regions above and below ABT  12 .  
         [0030]     ABT  12  may be activated in numerous ways such as activation through tubing pressure, control line activation, shunt tube activation, and mechanical activation. For example, a profile may be placed in end stop  32  so that a latching tool run on an intervention device such as slickline, wireline, or coiled tubing can be releasably affixed to end stop  32 . Pulling on the intervention device will move end stop  32 , forcing seal element  10  to set. Alternatively, pressurized fluid can be transported via the tubing, a shunt tube, or a control line to the entry port of chamber  28 , pressurizing chamber  28  and setting seal element  10 . In some instances it may be possible to combine two or more of the activation mechanisms, with the aim of building in redundancy or remedial functionalities.  
         [0031]     An alternate embodiment of ABT  12  ( FIGS. 10A and 10B ) has slips  100  and a seal  102  incorporated into a single unit. In the embodiment shown, slips  100  are arranged over a barrel support  104  as an integral part of a support sleeve  106 . Slips may also be attached by being welded, for example, directly to support sleeve  106 . Support sleeve  106  is preferably made of metal and is attached and sealed on both ends to upper and lower cones  108 ,  110 . Seal  102  is mounted along a portion of the outer surface of support sleeve  106 , preferably in its central region, and slips  100  are located on opposite sides of seal  102 . Seal  102  is preferably made of rubber, thermoplastic, or an elastomer. When ABT  12  is actuated, seal  102  seals against wellbore wall  34  (or casing, if present) and slips  100  anchor ABT  12  in place in wellbore wall  34  (or casing, if present), as shown in  FIG. 10B .  
         [0032]     One cone, say upper cone  108 , may be fixed to mandrel  20  of ABT  12 , while lower cone  110  acts as a moveable piston to press against the lower end of barrel support  104 . Lower cone  110  may move, for example, in response to applied pressure or a mechanical force. Fluid pressure may be applied via a port  112 . As described above, a ratchet mounted to mandrel  20  mates with complementary teeth on lower cone  110  to prevent movement of lower cone  110  in a particular direction. When lower cone  110  is displaced to actuate ABT  12 , it pushes barrel support  104  outward toward wellbore wall  34 . In response to the outward push of barrel support  104 , support sleeve  106  deforms elastically, forcing seal  102  and slips  100  to engage wellbore wall  34 . The roles of upper and lower cones  108 ,  110  may be interchanged, or both cones  108 ,  110  may be moveably mounted to mandrel  20 . ABT  12  may also be configured to be releasable to allow ABT  12  to be retrieved.  
         [0033]      FIGS. 11A and 11B  show an embodiment of ABT  12  in which fluid pressure is allowed to pass through a passageway  116  to bear on barrel support  104 . In this embodiment, fluid pressure aids the actuation and maintenance of contact forces between wellbore wall  34  and seal  102  and slips  100 . Passageway  116  may be located on either end of barrel support  104 .  
         [0034]     If one or more check valves  118  are used, passageways  116  may be on both sides of barrel support  104  such that fluid pressure from the higher pressure side will bear on barrel support  104 .  
         [0035]     Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph  6  for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.