Lead impression wear bushing

A wear bushing having a lead impression block is landed axially above a casing hanger and actuated to test an elevation of lock ring grooves formed in a wellhead. Then, drilling operations are performed through the wear bushing. The wear bushing includes a first tubular member having an axis and a second tubular member coaxial with the first tubular member. The second tubular member moves down to actuate a lead impression assembly to measure an elevation within the wellhead with the lead impression block. After the drilling operations are completed, the deformed lead impression block is retrieved along with the wear bushing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to wear bushings and, in particular, to a wear bushing that measures the elevation of lock ring grooves on an inner diameter of a wellhead housing prior to running a lockdown hanger or locking ring bridging hanger.

2. Brief Description of Related Art

Following setting of a casing hanger, a wear bushing is often landed axially above the casing hanger. This is done prior to further drilling operations that may be conducted axially downhole from the casing hanger. The wear bushing protects the casing hanger and wellhead housing from damage and wear that might be caused by the drill bit and drill string during these operations downhole from the casing hanger. Generally, the casing hanger is set, then a casing hanger running tool that was used to land and set the casing hanger is pulled from the wellbore. A wear bushing running and retrieval tool is coupled to the drill string in place of the casing hanger running 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.

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.

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 must be 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. Operation of the rig would generally require running of a lead impression tool prior to running and setting of the lockdown hanger. The lead impression tool determines the elevation of the lock-ring grooves for proper landing of the lockdown hanger. However, this step is often bypassed due to the costs associated with performing an additional tool trip with the drilling rig. Typically, the lockdown hanger is run, landed, and set without checking the locking ring groove elevation. If there is a problem with the lockdown hanger, the lockdown hanger may then be removed and the elevation of the locking ring grooves checked with the lead impression tool. This adds an additional downhole trip and can significantly increase the costs associated with completion of a well. Therefore, a lead impression tool that determined lock-ring groove elevation without requiring an additional rig trip would be useful in ensuring more efficient rig operation and fewer problems in completion of the well.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention that provide a lead impression wear bushing, and a method for using the same.

In accordance with an embodiment of the present invention, a subsea wellhead assembly is disclosed. The subsea wellhead assembly includes a subsea wellhead having a bore containing a grooved profile, and a casing hanger landed in the bore below the profile. A wear bushing is retrievably landed in the bore, and shields the profile and an inner part of the casing hanger from drilling tools that pass through the wear bushing. An impression block formed of a deformable material is carried by the wear bushing. An actuator is housed within the wear bushing and is moveable in response to landing of the wear bushing to force the block into the profile to cause the block to form an impression of the profile for subsequent inspection when the wear bushing is retrieved.

In accordance with another embodiment of the present invention, a wear bushing for disposition within a wellhead is disclosed. The wear bushing includes a first tubular member having an axis, and at least one impression assembly housed within the first tubular member and radially moveable between a retracted and an extended position relative to the first tubular member. The wear bushing also includes a second tubular member coaxial with the first tubular member. The second tubular member is axially moveable between run-in and set positions relative to the first tubular member. Axial movement of the second tubular member to the set position will cause the impression assembly to move from the retracted to the extended position into engagement with a wellhead member profile. The impression assembly includes a permanently deformable block for creating an imprint of the profile. The wear bushing includes a latch mounted to one of the tubular members to latch the first and second tubular members in the wellhead, and a seal mounted to one of the tubular members to seal the first and second tubular member to the wellhead. The first and second tubular members of the wear bushing have bores sized for the passage of drilling tools.

In accordance with yet another embodiment of the present invention, a method for performing operations through and in a subsea wellhead is disclosed. The method begins by mounting an impression block in a wear bushing, and then running the wear bushing subsea and landing the wear bushing within the wellhead such that the impression block is adjacent a selected profile within the wellhead. The method then moves the impression block outward and deforms the impression block against the profile in the wellhead. The method continues by lowering a drill string through the wear bushing and wellhead and rotating the drill string to perform drilling activities. The wear bushing is then retrieved along with the deformed impression block. The method continues by inspecting the impression block to ascertain a location of the profile.

An advantage of a preferred embodiment is that the disclosed lead impression wear bushing allows an elevation of lock ring grooves within a wellhead to be checked while other drilling operations are conducted. This saves a trip down the wellbore because a separate tool need not be used to check the elevation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Additionally, for the most part, details concerning drilling rig operation, casing hanger landing and setting, and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons skilled in the relevant art.

Referring toFIG. 1, a lead impression wear bushing11having an axis12includes a lead assembly wear bushing13and an actuation wear bushing15. Lead assembly wear bushing13may be a tubular member having a central bore17as shown inFIG. 2A. A counterbore19is located at an upper end of central bore17of lead assembly wear bushing13. Counterbore19extends from the upper end of lead assembly wear bushing13to an upward facing annular shoulder21formed on an interior diameter portion of lead assembly wear bushing13at the transition from counterbore19to central bore17. Counterbore19includes a first tapered surface23extending at a first angle from shoulder21to a second tapered surface25. Second tapered surface25extends from first tapered surface23at a second angle to an upper rim27of lead assembly wear bushing13. In the illustrated embodiment, first tapered surface23has a greater slope than second tapered surface25.

Lead assembly wear bushing13includes windows29extending radially outward from tapered surface23to an exterior diameter surface of lead assembly wear bushing13. In the illustrated embodiment, there are four windows29. A person skilled in the art will understand that more or fewer windows29may be included in alternative embodiments. Each window29includes a counterbore31extending radially inward from the exterior diameter surface of lead assembly wear bushing13to a radially outward facing shoulder33. As shown inFIG. 1, lead assembly wear bushing13also includes actuation wear bushing slots35formed in first tapered surface23. Wear bushing slots35extend axially downward to upward facing shoulder21from the transition between second tapered surface25and first tapered surface23. Actuation wear bushing slots35have an inner diameter surface that is substantially vertical and parallel to axis12. A guidance recess37is formed within each actuation wear bushing slot35and extends from the substantially vertical inner diameter surface of actuation wear bushing slot35radially outward terminating at a vertical surface parallel to axis12. Each guidance recess37has an upper and lower shoulder36,38as shown inFIG. 3.

Referring toFIG. 2A, an actuator, such as lead impression assembly39, is mounted within each window29. Each lead impression assembly39includes a coupling ring41, a biasing spring43, a lead impression piston45, and an impression block or cartridge such as lead impression block47. The impression block, such as lead impression block47, is permanently deformable so that an imprint of a profile may be created in the impression block when pressed into the profile. Coupling ring41is mounted to shoulder33within counterbore31by any suitable means such as with the illustrated bolts. An inner diameter of coupling ring41is smaller than the diameter of window29such that coupling ring41will form a radially inward facing shoulder49.

Referring toFIG. 2B, lead impression piston45may be a cylindrical object as shown having a radially inward piston head51and a radially outward end53. Piston head51may be a conical surface having an exterior diameter55substantially equivalent to the diameter of window29. The conical surface of end51forms an angle extending from apex57at a center of piston head51to exterior diameter55of piston head51. The angle is substantially equivalent to the angle of first tapered surface23ofFIG. 2A. As shown inFIG. 2B, piston head51includes a sealing ring56on an exterior diameter surface of piston head51. Sealing ring56is adapted to form a pressure seal when piston head51moves into window29as shown inFIG. 6. In this manner, lead impression wear bushing11may be pressure tested prior to running of a drill tool and drill string to ensure proper setting of lead impression wear bushing11. Referring toFIG. 2B, piston head51defines a radially outward facing shoulder59opposite shoulder49of coupling ring41. Lead impression piston45has an inner shank61extending from outward facing shoulder59to a lead block shoulder63. Inner shank61has an exterior diameter less than the diameter of window29, such that the exterior diameter surface of inner shank61defines an annular cavity between outward facing shoulder59, coupling ring shoulder49, and the inner diameter surface of window29. Biasing spring43mounts within this cavity and has a first end abutting shoulder49of coupling ring41, and a second end abutting shoulder59of piston head51such that movement of piston45radially outward will compress biasing spring43.

As shown inFIG. 2B, biasing spring43is un-displaced. When compressed, biasing spring43exerts a radially inward force on shoulder59of piston head51biasing piston45to the position shown inFIG. 2AandFIG. 2B. Biasing spring43may be disc springs or any other suitably sprung device such that biasing spring43will bias piston45to the radially inward or retracted position ofFIG. 2AandFIG. 2B. Biasing spring43has a central opening allowing for the passage of inner shank61of piston45.

Inner shank61transitions to a lead impression block shank65at lead block shoulder63. Lead impression block shank65has an exterior diameter that is less than the inner diameter of coupling ring41. Lead impression block47mounts to lead impression block shank65in any suitable manner, such as with a bushing and bolt assembly as shown. Lead impression block47has an inner diameter shoulder67configured to abut an exterior diameter surface of coupling ring41. In this manner, lead impression block47will limit the radially inward movement of piston45through abutment of shoulder67with coupling ring41when in the retracted position.

Referring toFIG. 2A, actuation wear bushing15has an upper end with an exterior diameter substantially equivalent to the exterior diameter of the upper end of lead assembly wear bushing13. A lower end of actuation wear bushing15is adapted to insert into counterbore19of lead assembly wear bushing13. The lower end of actuation wear bushing15is tapered at two angles so that the exterior diameter surface of the lower end of actuation wear bushing15will have a third tapered surface24abutting first tapered surface23and a fourth tapered surface26abutting second tapered surface25of lead impression wear bushing13. Actuation wear bushing15includes ribs69(FIG. 1) formed on the exterior diameter surface of the lower end of actuation wear bushing15along third tapered surface24. Each rib69will substantially fill a respective slot35(FIG. 1) of lead assembly wear bushing13when actuation wear bushing15is fully inserted into lead assembly wear bushing13as shown inFIG. 3.

Referring toFIG. 3, a guidance pin71is inserted into a bore in each rib69. In the illustrated embodiment the bores in each rib69are threaded and each guidance pin71is threaded through a corresponding bore so that a radially outward end of each guidance pin71inserts into a respective recess37. Guidance pins71will allow actuation wear bushing15to move axially relative to lead assembly wear bushing13by traveling axially through recess37. Axial movement of actuation wear bushing15relative to lead assembly wear bushing13will be limited by abutment of guidance pin71with upper shoulder36and abutment of a lower rim of actuation wear bushing15with upward facing shoulder21of lead assembly wear bushing13. In the illustrated embodiment, guidance pins71support the weight of lead assembly wear bushing13during running and retrieval operations.

As shown inFIG. 2A, shear elements73pass through bores in actuation wear bushing15adjacent to guidance pins71. Shear elements73insert into corresponding bores (not shown) in lead assembly wear bushing13and prevent axial movement of actuation wear bushing15relative to lead assembly wear bushing13prior to shearing of shear elements73. As shown inFIG. 4A, shear elements73hold actuation wear bushing15at an elevated position relative to lead assembly wear bushing13during running of lead impression wear bushing11. In the illustrated embodiment, shear elements73are threaded into actuation wear bushing15and lead assembly wearing bushing13from an interior diameter of actuation wear bushing15. A person skilled in the art will understand that shear elements73may be threaded into lead assembly wear bushing13from an exterior diameter of lead assembly wear bushing13and then into actuation wear bushing15. Shear elements73may include a seal allowing shear elements73to seal to either lead assembly wear bushing13or actuation wear bushing15to prevent passage of fluid from an interior of lead impression wear bushing11to an exterior of lead impression wear bushing11and vice versa.

After landing lead impression wear bushing11, described in more detail below, set down weight will be applied to actuation wear bushing15, shearing shear elements73as shown inFIG. 4B. Referring toFIG. 4C, guidance pins71will be in the position shown during running and retrieval of lead impression wear bushing11. Again, after landing of lead impression wear bushing11and shearing of shear elements73(not shown inFIG. 4C), actuation wear bushing15will move axially downward relative to lead assembly wear bushing13landing a lower rim of actuation wear bushing15on shoulder21of lead assembly wear bushing13as shown inFIG. 4D.

Referring toFIG. 5, lead impression wear bushing11is shown in the running or run-in position. Shear elements73and guidance pins71are in the positions shown inFIGS. 4A and 4C, respectively. Actuation wear bushing15will contact, but not yet cause radial movement of piston45. Referring toFIG. 5, after landing on a casing hanger as described below, set down weight will be applied to actuation wear bushing15, causing shear elements73to shear and actuation wear bushing15to move axially downward in response. As actuation wear bushing15moves axially downward into a set position as shown inFIG. 6, third tapered surface24will move piston45radially outward as third tapered surface24moves into contact with first tapered surface23, compressing biasing spring43. As piston45moves radially outward, the coupled lead impression block47will move out of counterbore window31such that impression assembly39is in an extended position, as shown inFIG. 6.

During retrieval of lead impression wear bushing11, an upward axial force is applied to actuation wear bushing15, causing actuation wear bushing15to move upward axially in response. Actuation wear bushing15will initially move upward relative to lead impression wear bushing13until pins71land on downward facing shoulder36of recess37. This will cause third tapered surface24to move out of contact with first tapered surface23. As third tapered surface24moves out of contact with first tapered surface23, biasing springs43, compressed by pistons45, such that springs43exert a radially inward force on pistons45, will cause pistons45to move radially inward. As a result, lead impression blocks47will move radially inward to the retracted position within counterbore window31shown inFIG. 5.

Referring now toFIG. 7, lead impression wear bushing11is shown disposed within a casing hanger75in place within a subsea wellhead77. Lead impression wear bushing11is coupled to a wear bushing running and retrieval tool81and run to the position shown in FIG.7. This is done while still on the rig deck by first stabbing a lower end of wear bushing running and retrieval tool81into the lead impression wear bushing11until a stop ring of wear bushing running and retrieval tool81bottoms out on an inner diameter shoulder of lead impression wear bushing11. Wear bushing running and retrieval tool81is then lifted up to engage slips of wear bushing running and retrieval tool81with the inner diameter surface of lead impression wear bushing11.

The combined assembly is then run into the wellbore to land at the position shown inFIG. 7. The tool set down weight is then applied by wear bushing running and retrieval tool81to move lead impression blocks47into engagement with lock-ring grooves79, as described above with respect toFIGS. 4-6. A person skilled in the art will understand that the impression blocks, such as lead impression blocks47shown herein, may be formed of any suitable material, provided the material is deformable by the associated profile in the wellhead. Referring toFIG. 7, as lead impression blocks47engage lock-ring grooves79, lead impression blocks47will deform to provide a minor image of the profile of lock-ring grooves79above casing hanger75. Running tool81may then pressure test lead impression wear bushing11prior to removal of running tool81and further drilling operations. A pressure test of lead impression wear bushing11may then be conducted through wear bushing running and retrieval tool81. Wear bushing running and retrieval tool81is retrieved by rotating the wear bushing running and retrieval tool81one quaruter turn clockwise and pulling straight up to disengage the slips from the inner diameter surface of lead impression wear bushing11. In this manner, a wear bushing may be set, and pressure tested while also determining the elevation of lock ring grooves79in wellhead77relative to casing hanger75in a single trip.

After subsequent drilling operations through lead impression wear bushing11, lead impression wear bushing11will be removed from wellhead77, and a lockdown hanger may be run into place and landed at the appropriate elevation to engage lock-ring grooves79. Retrieval occurs by first landing wear bushing running and retrieval tool81on lead impression wear bushing11. Then, while a weight is maintained on wear bushing running and retrieval tool81, a left hand torque is applied to engage slips of wear bushing running and retrieval tool81with an inner diameter surface of lead impression wear bushing11. While maintaining the left and torque on wear bushing running and retrieval tool81, an upward pull is applied to wear bushing running and retrieval tool to pull lead impression wear bushing11from its location within the wellhead. A person skilled in the art will understand that the running and retrieval process as described herein with respect to wear bushing running and retrieval tool81is exemplary. Any suitable tool configured to run, set, release, and retrieve lead impression wear bushing11may be used and is contemplated by the disclosed embodiments. Alternative wear bushing running and retrieval tools may be hydraulically actuated, pneumatically actuated, or engage a differently operating mechanical system when compared to that described herein.

As shown inFIG. 7, lead impression wear bushing11may include an anti-rotation pin83coupled to a lower rim of lead assembly wear bushing13. Anti-rotation pin83is adapted to insert into a corresponding slot of casing hanger75and is of sufficient strength to prevent rotation of lead impression wear bushing11relative to casing hanger75during subsequent drilling operations performed after setting and testing of lead impression wear bushing11. In addition, wear bushing11includes a seal85, and an optional latch87. In the illustrated embodiment, seal85comprises a ring in sealing engagement with an exterior surface of the lower end of lead assembly wear bushing13and a corresponding inner diameter surface of casing hanger75. A similar seal89may be included on lead actuation wear bushing15. Seal89may seal the upper end of lead actuation wear bushing15to wellhead77.

Where used, latch87may be a lockdown “D” ring as shown. Latch87will reside within an outer diameter channel formed on a lower end of lead impression wear bushing13and have an outer diameter slightly larger than an upper inner diameter rim of casing hanger75. A first weight may be applied to latch87through wear bushing11to force latch87past the upper inner diameter rim of casing hanger75to land in a inner diameter groove of casing hanger75. Upward pull on wear bushing11will cause latch87to expand radially outward and latch to a downward facing shoulder of casing hanger75. Wear bushing11may be retrieved by pulling latch87past the upward facing shoulder, usually requiring an upward pull greater than the weight applied to set latch87. Alternative embodiments may not include latch87. In these alternative embodiments, lead impression wear bushing11will be held in place by the force of impression blocks47on grooves79within wellhead77.

Accordingly, the disclosed embodiments provide numerous advantages. For example, the disclosed embodiments provide an apparatus that allows for setting a wear bushing while testing the elevation of lock ring grooves in a subsea wellhead. By determining or testing for this elevation while performing other drilling activities, the disclosed apparatus reduces the number of tooling trips needed to properly complete the well. This will save rig time while allowing rig operators to include this step as a standard operational procedure.

It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or scope of the invention. Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.