Abstract:
A wear bushing assembly protects and locks down a hanger in a wellhead housing; and which includes a wear bushing body that inserts into a wear bushing sleeve. A lock ring extends into registered recesses on the body and sleeve to couple together the body and sleeve. The wellhead housing has a profiled recess circumscribing its inner surface. A lockdown ring selectively mates with the profiled recess; and when mated is in interfering contact with an upper surface of the wear bushing sleeve, thereby coupling the sleeve to the wellhead housing. The sleeve outer surface is profiled to interfere with upward movement of the hanger, so that force is transferred from the hanger to the housing through the sleeve which locks down the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present disclosure relates in general to a wear bushing for use with a wellhead assembly; and in particular to a wear bushing for use with a wellhead assembly that locks a hanger in the wellhead assembly. 
         [0003]    2. Description of Prior Art 
         [0004]    Following setting of a casing hanger in a wellhead assembly, a wear bushing is often landed axially above the casing hanger. This is done prior to operations that involve inserting tools and devices (such as a drill bit and drill string) axially through the wellhead assembly to shield the casing hanger(s) and other components in the wellhead housing from damage and wear during these operations. Generally, a casing hanger running tool is mounted onto the drill string and used to land and set the casing hanger. After landing the casing hanger, the casing hanger running tool is removed from the drill string and replaced with a wear bushing running and retrieval tool. The wear bushing running and retrieval tool runs, lands, and sets the wear bushing. After landing the wear bushing, the wear bushing running and retrieval tool may pressure test the wear bushing to ensure that the wear bushing has properly landed on the casing hanger. 
         [0005]    Following a successful pressure test, the wear bushing running and retrieval tool is decoupled from the wear bushing and pulled from the wellbore. Various drilling tools may then be attached to the drill string in place of the wear bushing running and retrieval tool. The drilling tools are then run downhole past the wear bushing and the casing hanger to conduct drilling operations. Preferably, the drill tool and drill string will pass through a bore of the casing hanger without contacting or damaging the inner diameter or the rim of the casing hanger. However, if the drill tool is misaligned relative to the casing hanger, the drill tool may contact and damage the casing hanger as it passes through the casing hanger. If a wear bushing is landed axially above the casing hanger, the drill tool will first contact the wear bushing, and, as the drill tool passes through the wear bushing, it will come into alignment with the casing hanger. Thus, the wear bushing protects the casing hanger. In addition, if the drill string rotates eccentrically during the drilling operation, the drill string will contact and wear the wear bushing rather than the casing hanger, thus protecting the casing hanger. After performance of the desired drilling operations, the drill string and the drill tool will be pulled from the wellbore. The wear bushing running and retrieval tool may then be coupled to the drill string in place of the drill tool, and then be run to the wear bushing to pull the wear bushing from the wellbore. 
         [0006]    Typically, a lockdown hanger may then be run downhole to land and set above the casing hanger to provide additional casing lockdown capability. The lockdown hanger may be needed due to thermal expansion of the casing string. Lockdown hangers improve long-term seat reliability below the lockdown hanger by sharing the cyclic axial loads applied to the casing hanger. To properly land and set a lockdown hanger, the lockdown hanger is run proximate to lock-ring grooves formed in the subsea wellhead axially above the casing hanger. After landing, a grooved ring of the lockdown hanger will actuate to engage the lock-ring grooves, thereby properly securing the lockdown hanger to the wellhead and casing hanger. 
       SUMMARY OF THE INVENTION 
       [0007]    Disclosed herein are embodiments of a wear bushing assembly for use with a wellhead assembly. In an example, wear bushing is insertable into a wellhead housing and includes an annular wear bushing sleeve having a lower end selectively in interfering contact with an upper end of a hanger that is landed in the wellhead housing. Also included is an annular wear bushing body that inserts within and selectively couples to the wear bushing sleeve, and a lockdown ring that selectively couples to an inner surface of the wellhead housing and into interfering contact with an upper end of the wear bushing sleeve when the wear bushing body is landed in the wear bushing sleeve, so that when the wear bushing body is landed in the wear bushing sleeve and the wear bushing sleeve lands in the hanger, an axial lockdown force is transmitted between the hanger and the wellhead housing and through the wear bushing sleeve that opposes axial movement of the hanger in a direction towards the lockdown ring. Optionally included is a lock ring for coupling together the wear bushing body and wear bushing sleeve and that moves into interfering contact when an inner recess on the outer surface of the wear bushing body registers with an outer recess on the inner surface of the wear bushing sleeve. In this example, the wear bushing assembly is in a landed configuration when the inner and outer recesses are registered. Further in this example, the outer recess comprises a lower outer recess, and wherein the lock ring is in interfering contact with the inner recess and an upper outer recess on the outer surface of the wear bushing sleeve that is axially above the lower outer recess and when the wear bushing assembly is in a running configuration. Pins are included with this example that are radially extending through the wear bushing sleeve with inner ends that intersect the upper outer recess and outer ends that project radially outward past an outer surface of the wear bushing sleeve. The outer ends of the pins can contact the upper end of the hanger as the wear bushing sleeve is inserted into the hanger. The lockdown ring may be frangibly connected to the wear hushing body. In an alternative, the wear bushing body has an outer diameter that transitions radially outward for urging the lockdown ring into engagement with a groove formed on an inner surface of the wellhead housing. A profile of the inner surface of the wear bushing sleeve can define an upward facing shoulder on which a downward facing shoulder on an outer surface of the wear bushing body is supported when the wear bushing body is landed in the wear bushing sleeve. 
         [0008]    In another example, a wear bushing assembly is disclosed that is for use with a wellhead assembly that has a wellhead housing. In this example the wear bushing is made up of an annular wear bushing sleeve having an inner bore that transitions radially inward a distance to define an upward facing shoulder, and having a lower portion that is selectively in interfering contact with a casing hanger that is landed in the wellhead housing. An annular wear bushing body is included that has an outer surface profiled to define a downward facing shoulder, and that is insertable in the wear bushing sleeve to a running position with the upward and downward facing shoulders spaced apart, and that is inserted in the wear bushing sleeve is to a landed position with the downward facing shoulder in interfering contact with the upward facing shoulder. This example further includes a lockdown ring circumscribing the wear bushing body and that selectively engages an inner surface of the wellhead housing and that is in interfering contact with an upper end of the wear bushing sleeve when the wear bushing body is in the landed position. A lock ring is optionally included that is for coupling together the wear bushing sleeve and the wear bushing body, and that is in interfering contact in an inner recess on an outer surface of the wear bushing body and an upper outer recess on an inner surface of the wear bushing sleeve when the wear bushing body is in the running position. The lock ring of this example is in interfering contact in the inner recess and a lower outer recess on an inner surface of the wear bushing sleeve when the wear bushing body is in the landed position, and wherein the lower outer recess is on a side of the upper outer recess opposite from the lockdown ring. This example embodiment further includes pins that project through a sidewall of the wear bushing sleeve and that are for urging the lock ring out of the upper recess so that the wear bushing body and lock ring slide axially with respect to the wear bushing sleeve until the inner recess and lower outer recess register with one another. 
         [0009]    Another example of a wear bushing assembly is disclosed that is for use with a wellhead assembly having a wellhead housing. In this example the wear bushing assembly includes an annular wear bushing sleeve selectively inserted into the wellhead housing and landed on an upper end of a casing hanger, an annular wear bushing body selectively inserted into the wear bushing sleeve and moveable between a running position and a landed position that is axially spaced away from the running position, and a lockdown ring that circumscribes the wear bushing body and has undulations on an outer surface, and when the wear bushing body is in the landed position, the undulations engage a profiled portion on an inner surface of the wellhead housing so that the lock ring is in interfering contact with an upper end of the wear bushing sleeve. Also included is a protrusion on an outer surface of the wear bushing body for urging the lock ring radially outward into engagement with the profiled portion A lock ring for coupling the wear bushing body to the wear bushing sleeve can be included. An inner recess can be included that is on an outer surface of the wear bushing body, along with an upper outer recess on an inner surface of the wear bushing sleeve and that registers with the inner recess when the wear bushing body is in the running position, and a lower outer recess spaced axially away from the upper outer recess and on the inner surface of the wear bushing sleeve, and wherein the lower outer recess registers with the inner recess when the wear bushing body is in the landed position. In one example, when the wear bushing body is in the running position, the lock ring extends radially into the inner recess and upper outer recess and is in interfering contact with the wear bushing sleeve and wear bushing body thereby coupling together the wear bushing sleeve and wear bushing body, and wherein when the wear bushing body is in the landed position, the lock ring extends radially into the inner recess and lower outer recess and is in interfering contact with the wear bushing sleeve and wear bushing body thereby coupling together the wear bushing sleeve and wear bushing body. Optionally included are pins for frangibly coupling together the lockdown ring and the wear bushing body, and wherein when the wear bushing body is in the running position, an upper end of the wear bushing sleeve is in interfering contact with the lockdown ring, so that when the wear bushing body moves from the running position to the landed position, the wear bushing sleeve opposes axial movement of the lockdown ring thereby shearing the pins. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0011]      FIGS. 1-3  are side sectional views of an example of a wear bushing assembly being inserted into and locked down in a wellhead housing and in accordance with the present invention. 
           [0012]      FIG. 4  is a side sectional detailed view of an example of a portion of the wear bushing assembly and wellhead housing of  FIG. 3  and in accordance with the present invention. 
       
    
    
       [0013]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF INVENTION 
       [0014]    The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term about includes +/−5% of the cited magnitude. 
         [0015]    It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
         [0016]      FIG. 1  is a side sectional view of an example of a wear bushing assembly  20  that includes an annular wear bushing body  22  with a bore  23  shown formed axially through the body  22 . The outer diameter of body  22  transitions radially inward to define a pair of downwardly facing shoulders  24 ,  26  that are spaced axially apart. A lockdown ring  28  is shown circumscribing an outer surface of the wear bushing body  22  and adjacent lower facing shoulder  24 . In the example of  FIG. 1  the outer curved surface of the lockdown ring  28  includes a pair of undulations that define a profile  30 . The lockdown ring  28  couples with the wear bushing body  22  via pins  32  that project radially through the lockdown ring  28  and into an outer surface of the wear bushing body  28  just above downward facing shoulder  24 . In the example of  FIG. 1 , the lower end of lockdown ring  28  depends between downward facing shoulder  24  and downward facing shoulder  26 . 
         [0017]    The wear bushing body  22  of  FIG. 1  is shown inserted into a bore  33  that extends axially through an annular wear bushing sleeve  34 . In the example of  FIG. 1 , the wear bushing body  22  is in what is referred to as a running position and wherein the lockdown ring  28  is in an interfering contact within an upper end  35  of the wear bushing sleeve  34 . Illustrated axially spaced away from downward facing shoulder  26  is an upward facing shoulder  36  formed on an inner surface of wear bushing sleeve  34  where a radius of bore  33  transitions radially inward. 
         [0018]    Push rods  38  are shown projecting radially through a side wall of wear bushing sleeve  34  and on a side of upward facing shoulder  36  opposite downward facing shoulder  26 . The push rods  38  have elongate cylindrical bodies that project radially through the passages in the side wall of wear bushing sleeve  34 . A piston like head is formed on an inner radial end of the push rods  38 , and is shown in contact with an outer surface of a lock ring  40 . Lock ring  40  circumscribes a lower portion of the wear bushing body  22 , and has a cross section with an the axial height that is greater than its radial width. Lock ring  40  circumscribes an outer surface of wear bushing body  22 , and its cross sectional radial width extends from within a portion of an inner recess  42  and radially outward into an upper outer recess  43  that is formed on an inner surface of wear bushing sleeve  34 . Thus, when the wear bushing body  22  is in the running position and inserted within wear bushing sleeve  34 , inner recess  42  is in registration with upper outer recess  43 , and portions of the lock ring  40  are in recesses  42 ,  43  thereby coupling together the wear bushing body  22  and wear bushing sleeve  34 . Spaced axially away from upper outer recess is a lower outer recess  44  formed along the inner surface of wear bushing sleeve  34 . 
         [0019]    In the example of  FIG. 1 , the wear bushing assembly  20  is being landed within a wellhead housing  45  that is part of a wellhead assembly. Also included with the wellhead assembly is a casing hanger  46 , which is an annular member shown landed within wellhead housing  45  and below wear bushing assembly  20 . A ledge  47  is shown that is axially spaced below where the upward facing shoulder  36  is formed on the inner surface of the wear bushing sleeve  34 ; ledge  47  faces downward and towards an upper end of casing hanger  46 . Further in the example of  FIG. 1  is shown an example of a seal assembly  48  between the outer surface of casing hanger  46  and inner surface of wellhead housing  45 . 
         [0020]    Referring now to  FIG. 2 , shown in side sectional view is an example of wear bushing assembly  20  moved axially downward from its position of  FIG. 1 , and landed on an upper end of casing hanger  46 . In the position of  FIG. 2 , ledge  47  is in interfering contact with an upper end of casing hanger  46 . As the outer radial tips of the push rods  38  extend past the outer circumference of the side wall of wear bushing sleeve  34 , the tips of the push rods  38  come into interfering contact with an inner surface of casing hanger  46 . The contact between casing hanger and push rods  38  urges push rods  38  radially inward so that the piston portion of the push rods  38  in turn urges the lock ring  40  radially inward and out of the upper outer recess  43 . With lock ring  40  out of upper outer recess  43 , the coupling between the wear bushing body  22  and wear bushing sleeve  34  is removed. Potential energy is stored in the lock ring  40  when it is radially compressed within the recess  42 , wherein the potential energy exerts a force to expand lock ring  40  radially outward from recess  42 . As will be described in further detail below, moving lock ring  40  into inner recess  42  allows where bushing body  22  to be moved from the running position to a landed position and axially downward within wear bushing sleeve  34 . 
         [0021]    Referring now to  FIG. 3 , the wear bushing body  22  is moved axially downward into the landed position so that its downward facing shoulder  26  is in an interfering contact with the upward facing shoulder  36  of the wear bushing sleeve  34 . In this configuration, inner recess  42  is moved into registration with lower outer recess  44 , so that the potential energy stored within lock ring  40  causes it to radially expand and reside partially within each recess  42 ,  44 . When portions of lock ring  40  are in recesses  42 ,  44 , lock ring  40  couples together wear bushing body  22  wear bushing sleeve  34 . Also, push pins  38  having been moved radially inward are positioned such that the outer radial portion is within the outer circumference of wear bushing sleeve  34  and the piston portion of the push rods is set within the upper outer recess  43 . Because the lockdown ring  28  is in interfering contact with the upper end  35  of wear bushing sleeve  34  when in the running position, moving the wear bushing body  22  axially downward and into the landed position axially moves the lockdown ring  28  with respect to wear bushing body  22 . This movement shears shear pins  32  thereby releasing the lockdown ring  28  from the wear bushing body  22 . 
         [0022]    The relative axial movement of wear bushing body  22  with respect to lockdown ring  28  positions lockdown ring  28  adjacent a protrusion  49  defined where the outer radius of wear bushing body  22  is increased. Protrusion  49  urges the lockdown ring  28  radially outward and into engaging contact with a groove  50  formed on an inner diameter surface of bore  52  created axially through wellhead housing  45 . As such, not only is the wear bushing assembly  20  secured within wellhead housing  45 , but because the ledge  47  on the lower end of wear bushing sleeve  34  is in interfering contact with the upper surface of casing hanger  46 , the interfering contact between the upper end of wear bushing sleeve  34  and lockdown ring  28  puts the casing hanger  46  in a lockdown position within wellhead assembly. In an example, interfering contact between two bodies occurs by affixing one of the bodies in a space that interferes with movement of the other body through that space. The lockdown configuration of casing hanger  46  is achieved by its interfering contact with the ledge  40  of the wear bushing sleeve  34 . Accordingly, axial forces created by thermal expansion of a casing string (not shown) coupled with the lower end of casing hanger  46  is countered by opposing forces generated by the interfering contact between the casing hanger  46  and wear bushing sleeve  34 , and between wear bushing sleeve  34  and lockdown ring  28 . Thus axial movement of the casing hanger  46  within wellhead housing  45  is opposed by the anchoring of the wear bushing assembly  20  by virtue of the lockdown ring  28  within profile  50 . 
         [0023]      FIG. 4  is a side sectional view of a portion of the wear bushing assembly  20  of  FIG. 3  and inserted within casing hanger  46 . As illustrated, the lock ring  40  occupies a portion of both the inner recess  42  and lower outer recess  44 . To facilitate removal of the wear bushing assembly  20  when all operations are complete, an optional bevel is provided on an upper surface  54  of lower outer recess  44 . In an example, the bevel reduces resistive forces of urging the lock ring  40  radially inward from the lower outer recess  44  and fully into inner recess  42  when upward forces applied to the wear bushing assembly  20  for its removal from within the wellhead housing  45 . Further illustrated in  FIG. 4  is a tie back profile  56  on an inner surface of casing hanger  46  and axially adjacent lower outer recess  44 . As is known, tie back profile  56  provides a location for a running tool (not shown) to engage casing hanger  46  so casing hanger  46  may be landed within wellhead housing  45  ( FIG. 3 ). A profile  58  on an outer surface of wear bushing sleeve  34  may be included that projects into a portion of the space defined by tie back profile  56 . 
         [0024]    In one example of operation, casing hanger  46  is landed within wellhead housing  45  by the running tool, and then the running tool is removed and then attached to the wear bushing assembly  20 . Wear bushing assembly  20  is lowered into the wellhead housing  45  so it can be landed onto casing hanger  46  as illustrated in  FIG. 2 . Downward force provided via running tool onto wear bushing assembly  20  can generate the applied force for shearing shear pins  32  so that the wear bushing body  22  can be moved into the landed position of  FIG. 3  from the running position of  FIG. 1 , and also urge the lockdown ring  28  into engaging contact with the profile  50  of wellhead housing  45 . While wellbore operations, such as drilling or other actions that require insertion of tools within the wellhead housing  45  take place, the wear bushing assembly  20  remains in place to protect wellhead housing  45 , and also exerts a lockdown force onto a casing hanger  46 . As such, the need for a separate lock down system (not shown) is eliminated with the embodiments disclosed herein. At a designated time, such as when the aforementioned downhole operations have been completed, the running tool can engage the wear bushing assembly  20  and remove it from within wellhead housing  45  with an applied upward force to decouple lockdown ring  28  from within profile  50 . 
         [0025]    The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.