Retaining apparatus for use in a wellhead assembly and method for using the same

Abstract

A retaining apparatus, in particular an internal tree cap, for use in a wellhead having a central bore and first and second retaining means, such as a shoulder and a groove, within the bore of the wellhead. The retaining apparatus has a housing for location within the bore of the wellhead. A first engagement assembly is provided for engaging with the first retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead. A second engagement assembly for engaging with the second retaining means in the bore of the wellhead is also provided. The apparatus further comprises a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to the housing between the first and second retaining means. A method for retaining an assembly within a wellhead bore, in which a preload is applied between the first and second retaining means, is also disclosed.

1. A retaining apparatus for use in a wellhead, the wellhead having a central bore and first and second retaining means within the bore of the wellhead, the apparatus comprising:
 a housing for location within the bore of the wellhead; 
 a first engagement assembly for engaging with the first retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead; 
 a second engagement assembly for engaging with the second retaining means in the bore of the wellhead; 
 a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to the housing between the first and second retaining means, the preload assembly comprises a loading member movable so as to be brought to bear against the second engagement assembly once the second engagement assembly is engaged with the second retaining means to urge the apparatus housing toward the first retaining means within the wellhead, to thereby provide the preload; 
 the loading member is a loading ring movable longitudinally with respect to the housing; and, 
 a threaded connection secures the loading ring to the housing, rotation of the loading ring with respect to the housing causing the loading ring to move longitudinally with respect to the housing. 
 
     
     
       2. The apparatus as claimed in  claim 1 , wherein, as the first retaining means the wellhead comprises an internal shoulder within the bore, the first engagement assembly comprising a shoulder provided on the housing for seating directly or indirectly on the wellhead internal shoulder. 
     
     
       3. The apparatus as claimed in  claim 2 , wherein the shoulder of the first engagement assembly is adapted to seat directly on a tubing hanger assembly present in the wellhead, the tubing hanger being seated directly on the internal shoulder. 
     
     
       4. The apparatus as claimed in  claim 1 , wherein, as the second retaining means the wellhead comprises a circumferential groove within the bore of the wellhead, the second engagement assembly engageable with the circumferential groove. 
     
     
       5. The apparatus as claimed in  claim 4 , further comprising an actuator movable between a first position in which the actuator is disengaged from the second engagement assembly to a second position in which the actuator is engaged with the second engagement assembly, movement of the actuator from the first position to the second position when the apparatus housing is positioned within the wellhead engaging the second engagement assembly with the circumferential groove. 
     
     
       6. The apparatus as claimed in  claim 5 , wherein the actuator comprises a collar moveable longitudinally with respect to the housing. 
     
     
       7. The apparatus as claimed in  claim 6 , wherein the collar comprises a tapered surface, movement of the collar from the second position to the first position bringing the tapered surface into contact with the second engagement assembly and thereafter urge the second engagement assembly into engagement with the circumferential groove. 
     
     
       8. The apparatus as claimed in  claim 1 , wherein the apparatus housing is an internal tree cap. 
     
     
       9. The apparatus as claimed in  claim 8 , wherein the internal tree cap is arranged to be landed within a spool tree. 
     
     
       10. The apparatus as claimed in  claim 9 , wherein the internal tree cap is arranged to be landed on a tubing hanger installed within the central bore of the spool tree. 
     
     
       11. A method for retaining an apparatus within the central bore of a wellhead assembly, the method comprising:
 providing a first retaining means within the bore of the wellhead assembly; 
 providing a second retaining means within the bore of the wellhead assembly; 
 providing the apparatus with an engagement assembly for engaging with the second retaining means within the bore of the wellhead assembly; 
 positioning the apparatus within the bore of the wellhead assembly so as to be retained by the first retaining means; 
 engaging the engagement assembly with the second retaining means; 
 applying a preload to the apparatus against the second retaining means to urge the apparatus toward the first retaining means; 
 providing an actuator movable longitudinally within the central bore of the wellhead assembly, movement of the actuator in a first direction causing the engagement ring to move into engagement with the groove and movement of the actuator in a second direction causing the engagement ring to move out of engagement with the groove, the method comprising moving the actuator in the first direction to engage the engagement ring with the groove; 
 providing a loading assembly, the loading assembly being movable longitudinally within the bore of the wellhead assembly, with the apparatus positioned within the bore of the wellhead assembly and the engagement assembly engaged with the second retaining means, movement of the loading assembly in a first direction causing the loading assembly to bear against the second retaining means and urge the apparatus against the first retaining means, thereby applying the preload to the apparatus, the method comprising moving the loading assembly in the first direction to bear against the second retaining means; and, 
 the apparatus comprises a housing, movement of the loading assembly in the first direction is obtained by rotation of the loading assembly with respect to the housing. 
 
     
     
       12. The method as claimed in  claim 11 , wherein the first retaining means is an internal shoulder formed within the central bore of the wellhead assembly. 
     
     
       13. The method as claimed in  claim 12 , wherein the apparatus is landed directly on the internal shoulder within the central bore of the wellhead. 
     
     
       14. The method as claimed in  claim 11 , the method further comprising:
 landing a wellhead component within the central bore of the wellhead assembly so as to be retained by the first retaining means; 
 the apparatus thereafter being landed on the wellhead component. 
 
     
     
       15. The method as claimed in  claim 14 , wherein the wellhead component is a tubing hanger. 
     
     
       16. The method as claimed in  claim 11 , wherein the second retaining means within the bore of the wellhead assembly comprises a circumferential groove, the apparatus being provided with an engagement ring movable radially into and out of engagement with the circumferential groove once the apparatus is positioned within the central bore of the wellhead assembly. 
     
     
       17. The method as claimed in  claim 11 , wherein the apparatus is an internal tree cap. 
     
     
       18. An internal tree cap for installation in the central bore of a wellhead assembly, the wellhead assembly comprising first and second retaining means within the bore of the wellhead, the internal tree cap comprising:
 a cap housing for location within the bore of the wellhead; 
 a first engagement assembly for engaging with the first retaining means in the bore of the wellhead to thereby retain the cap housing within the bore of the wellhead; 
 a second engagement assembly for engaging with the second retaining means in the bore of the wellhead; 
 a preload assembly operable when the cap housing is located within the bore of the wellhead, the preload assembly when operated bearing against the second retaining means to urge the cap housing towards the first retaining means, the preload assembly thereby applying a preload to the cap housing between the first and second retaining means. 
 
     
     
       19. The internal tree cap as claimed in  claim 18 , wherein, as the first retaining means the wellhead comprises an internal shoulder within the bore, the first engagement assembly comprising a shoulder provided on the housing for seating directly or indirectly on the wellhead internal shoulder. 
     
     
       20. The internal tree cap as claimed in  claim 19 , wherein the shoulder of the first engagement assembly is adapted to seat directly on a tubing hanger assembly present in the wellhead, the tubing hanger being seated directly on the internal shoulder. 
     
     
       21. The internal tree cap as claimed in  claim 18 , wherein, as the second retaining means the wellhead comprises a circumferential groove within the bore of the wellhead, the second engagement assembly comprising a locking ring engageable with the circumferential groove. 
     
     
       22. The internal tree cap as claimed in  claim 21 , further comprising an actuator movable between a first position in which the actuator is disengaged from the locking ring to a second position in which the actuator is engaged with the locking ring, movement of the actuator from the first position to the second position when the apparatus cap housing is positioned within the wellhead engaging the locking ring with the circumferential groove. 
     
     
       23. The internal tree cap as claimed in  claim 22 , wherein the actuator comprises a collar moveable longitudinally with respect to the housing. 
     
     
       24. The internal tree cap as claimed in  claim 23 , wherein the collar comprises a tapered surface, movement of the collar from the second position to the first position bringing the tapered surface into contact with the locking ring and thereafter urge the locking ring into engagement with the circumferential groove. 
     
     
       25. The internal tree cap as claimed in  claim 18 , wherein the preload assembly comprises a loading member movable so as to be brought to bear against the second engagement assembly once the second engagement assembly is engaged with the second retaining means to urge the apparatus cap housing toward the first retaining means within the wellhead, to thereby provide the preload. 
     
     
       26. The internal tree cap as claimed in  claim 25 , wherein the loading member is a loading ring movable longitudinally with respect to the housing. 
     
     
       27. The internal tree cap as claimed in  claim 26 , wherein a threaded connection secures the loading ring to the housing, rotation of the loading ring with respect to the housing causing the loading ring to move longitudinally with respect to the housing. 
     
     
       28. A wellhead assembly comprising:
 first and second retaining means within the bore of the wellhead; 
 an internal tree cap retained in the bore of the wellhead, the internal tree cap comprising: 
 a cap housing for location within the bore of the wellhead; 
 a first engagement assembly for engaging with the first retaining means in the bore of the wellhead to thereby retain the cap housing within the bore of the wellhead; 
 a second engagement assembly for engaging with the second retaining means in the bore of the wellhead; 
 a preload assembly operable when the cap housing is located within the bore of the wellhead, the preload assembly when operated bearing against the second retaining means to urge the cap housing towards the first retaining means, the preload assembly thereby applying a preload to the cap housing between the first and second retaining means. 
 
     
     
       29. The wellhead assembly as claimed in  claim 28 , further comprising a spool tree, the internal tree cap being retained in the central bore of the spool tree. 
     
     
       30. The wellhead assembly as claimed in  claim 28 , further comprising a tubing hanger, the tubing hanger being retained in the bore of the wellhead assembly by the first retaining means, the first engagement assembly of the internal tree cap engaging with the tubing hanger to retain the internal tree cap within the bore of the wellhead assembly. 
     
     
       31. An apparatus for use in a wellhead, the wellhead having a central bore and first and second retaining means within the bore of the wellhead, the apparatus comprising:
 a housing for location within the bore of the wellhead;   at least one seal mounted externally on a portion of the housing and adapted for sealing engagement with the wellhead;   a first engagement assembly associated with the first retaining means in the bore of the wellhead to thereby support the housing within the bore of the wellhead;   a second engagement assembly for engaging with the second retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead;   a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to that portion of the housing on which the at least one seal is mounted below the second retaining means, the preload assembly comprises a loading member movable so as to be brought to bear against the second engagement assembly once the second engagement assembly is engaged with the second retaining means to urge the housing toward the first retaining means within the wellhead, to thereby provide the preload;   the loading member is a loading ring movable longitudinally with respect to the housing; and,   a threaded connection secures the loading ring to the housing, rotation of the loading ring with respect to the housing causing the loading ring to move longitudinally with respect to the housing.   
     
     
       32. The apparatus as claimed in claim 31 wherein the loading member is movable in the first direction so as to be brought to bear against the second engagement assembly after the second engagement assembly is engaged with the second retaining means to urge the housing in the second direction opposite the first direction and toward the first retaining means within the wellhead and to secure the loading member to the housing to thereby provide and maintain the preload on the housing portion. 
     
     
       33. The apparatus as claimed in claim 31 wherein the preload on the housing prevents relative longitudinal movement of the housing portion between the housing portion and wellhead. 
     
     
       34. The apparatus as claimed in claim 31 wherein the housing is an internal tree cap. 
     
     
       35. The apparatus as claimed in claim 31 further including a bore through the housing having a profile adapted for a plug. 
     
     
       36. The apparatus as claimed in claim 35 wherein the bore includes a upwardly facing shoulder. 
     
     
       37. The apparatus as claimed in claim 31, wherein the housing has a downwardly facing shoulder adapted for engagement with a tubing hanger having seals engaging the wellhead. 
     
     
       38. The apparatus as claimed in claim 31, wherein the housing includes a downwardly extending portion adapted for insertion into a tubing hanger. 
     
     
       39. The apparatus as claimed in claim 31 wherein the housing is a tubing hanger. 
     
     
       40. The apparatus as claimed in claim 31, further comprising:
 a well component within the central bore adapted to be supported within the wellhead;   seals disposed around a part of the well component and engaging the wellhead;   the well component supporting the housing within the wellhead;   the second engagement assembly including a locking ring disposed on the housing and to project into a groove of the second retaining means in the wellhead to thereby retain the housing within the central bore of the wellhead;   the loading member movable longitudinally with respect to the housing so as to be brought to bear against the locking ring to urge the housing against the well component to thereby provide a force to the housing.   
     
     
       41. The apparatus as claimed in claim 40 wherein loading member applies a force through the housing to that part of the well component on which the seals are disposed. 
     
     
       42. The apparatus as claimed in claim 40 wherein the well component is a tubing hanger having a bore therethrough with a profile adapted for a plug. 
     
     
       43. The apparatus as claimed in claim 40 wherein the first retaining means includes the wellhead component. 
     
     
       44. The apparatus as claimed in claim 31 wherein the second engagement assembly includes an expandable locking member. 
     
     
       45. The apparatus as claimed in claim 31 wherein the second engagement assembly and force assembly include engaging tapers camming the second engagement assembly against a downwardly facing taper on a profile of the second retaining means in the wellhead and causing a downward force. 
     
     
       46. The apparatus as claimed in claim 31 wherein the wellhead assembly includes a horizontal tree and a tubing hanger, the horizontal tree and tubing hanger having aligned lateral production ports, the seals engaging the horizontal tree and tubing hanger. 
     
     
       47. The apparatus as claimed in claim 31 wherein:
 the housing has a neck;   the second engaging means includes a locking ring disposed around the neck;   the preload assembly including an actuator ring disposed between the neck and the locking ring;   the locking ring and the actuator ring having engaging tapered surfaces;   the actuator ring being movable longitudinally to cam the engaging tapered surfaces and apply a force to the housing; and   interengaging surfaces on the neck and the actuator ring engaging to maintain the housing in position as the actuator ring moves longitudinally.   
     
     
       48. A retaining apparatus for use in a wellhead, the wellhead having a central bore and a first retaining means with a support shoulder in the central bore and a second retaining means with a groove, the apparatus comprising:
 a well component within the central bore adapted to be supported by the support shoulder;   seals disposed around a part of the well component and engaging the wellhead;   a housing adapted for location within the bore of the wellhead;   at least one seal mounted externally on a portion of the housing and adapted for sealing engagement with the wellhead;   the housing engaging the well component;   a first engagement assembly associated with the support shoulder of the first retaining means in the bore of the wellhead to thereby support the housing within the bore of the wellhead;   a second engagement assembly for engaging with the groove of the second retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead;   the second engagement assembly including a locking ring disposed on the housing and adapted to project into the groove to thereby retain the housing within the bore of the wellhead;   a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to that portion of the housing on which the at least one seal is mounted below the second retaining means, the preload assembly comprises a loading member movable so as to be brought to bear against the second engagement assembly once the second engagement assembly is engaged with the second retaining means to urge the housing toward the first retaining means within the wellhead, to thereby provide the preload;   the loading member is a loading ring movable longitudinally with respect to the housing;   a threaded connection secures the loading ring to the housing, rotation of the loading ring with respect to the housing causing the loading ring to move longitudinally with respect to the housing; and   a retainer securing the loading member to the housing as the loading member moves longitudinally.   
     
     
       49. The retaining apparatus of claim 48 wherein the loading member applies a force through the housing portion to the well component part. 
     
     
       50. An internal tree cap for installation in the central bore of a horizontal tree with a tubing hanger, the horizontal tree comprising a retaining profile within the bore of the horizontal tree, and the tubing hanger having seals around a part of the tubing hanger, the internal tree cap comprising:
 a cap housing for location within the bore of the horizontal tree;   at least one seal mounted externally on a portion of the cap housing and adapted for sealing engagement with the horizontal tree;   the cap housing engaging the tubing hanger in the bore of the horizontal tree to thereby support the cap housing within the bore of the horizontal tree;   an engagement assembly on the internal tree cap engaging the retaining profile in the bore of the horizontal tree; and   a force assembly operable when the cap housing is located within the bore of the horizontal tree, the force assembly when operated bearing against the engagement assembly to urge the cap housing towards the tubing hanger, the force assembly thereby applying a force on the cap housing portion between the retaining profile and the tubing hanger.   
     
     
       51. The internal tree cap of claim 50 wherein the force assembly applies a force on the housing and tubing hanger which prevents relative longitudinal movement between the wellhead, housing portion and tubing hanger part. 
     
     
       52. The internal tree cap of claim 50 wherein the engagement assembly includes an expandable locking member. 
     
     
       53. The internal tree cap of claim 50 wherein the engagement assembly and force assembly include engaging tapers camming the engagement assembly against a downwardly facing taper on the retaining profile and causing a downward force on the cap housing. 
     
     
       54. A wellhead assembly comprising:
 first and second retainers within the bore of the wellhead assembly;   an internal tree cap retained in the bore of the wellhead assembly, the internal tree cap comprising:   a cap housing for location within the bore of the wellhead assembly;   at least one seal mounted externally on a portion of the cap housing;   a first engagement assembly supported by the first retainer in the bore of the wellhead assembly;   a second engagement assembly for engaging the second retainer in the bore of the wellhead assembly to thereby retain the cap housing within the bore of the wellhead assembly;   a preload assembly operable when the cap housing is located within the bore of the wellhead assembly, the preload assembly when operated moving axially bearing against the second engagement assembly and engaging the cap housing to urge the cap housing portion in an axial direction away from the second engagement assembly and against the first retainer, the preload assembly thereby applying a preload to the cap housing portion between the first and second retainers.   
     
     
       55. The wellhead of claim 54 wherein the wellhead assembly includes a tubing hanger, which serves as the second retainer. 
     
     
       56. The wellhead assembly of claim 55 wherein the wellhead assembly includes a horizontal tree and a tubing hanger, the horizontal tree and tubing hanger having aligned lateral production ports with seals around an external part of the tubing hanger. 
     
     
       57. A wellhead assembly having a wellhead, the wellhead assembly comprising:
 a horizontal tree having a central bore therethrough, a landing shoulder, and first and second profiles in the central bore;   a tubing hanger landed on the landing shoulder and having seals disposed around a part of the tubing hanger;   a first locking ring on the tubing hanger projecting into the first profile retaining the tubing hanger within the central bore;   an internal tree cap disposed within central bore and engaging the tubing hanger;   at least one seal mounted around an external portion of the internal tree cap;   a second locking ring on the internal tree cap projecting into the second profile retaining the internal tree cap within the central bore; and   a loading member engaging the internal tree cap and movable longitudinally with respect to the internal tree cap causing a downward force on the tubing hanger to prevent longitudinal movement of the tubing hanger part.   
     
     
       58. A wellhead assembly comprising:
 a spool tree having a bore with first and second retaining means;   an internal tree cap retained in the bore of the spool tree, the internal tree cap comprising:   a cap housing for location within the bore of the spool tree;   at least one seal mounted externally around a portion of the cap housing;   a first engagement assembly associated with the first retaining means in the bore of the spool tree to thereby support the cap housing within the bore of the spool tree;   a second engagement assembly for engaging with the second retaining means in the bore of the spool tree to retain the cap housing within the bore of the spool tree;   a force assembly operable when the cap housing is located within the bore of the spool tree and including a securing means, the force assembly when operated bearing against the second retaining means to urge the cap housing portion towards the first retaining means, the force assembly thereby applying a force to the cap housing portion between the first and second retaining means;   wherein:
 the spool tree is a horizontal tree having the bore therethrough and including a landing shoulder disposed in the bore of the horizontal tree and first and second profiles in a wall forming the bore of the spool tree; 
 a tubing hanger landed on the landing shoulder, the landing shoulder and tubing hanger forming the first retaining means; 
 seals disposed around an external part of the tubing hanger; 
 a first locking ring on the tubing hanger projecting into the first profile retaining the tubing hanger within the bore; 
 the internal tree cap having a downwardly facing shoulder forming the first engagement means and engaging the tubing hanger supported on the landing shoulder; 
 the second engagement means including a second locking ring on the internal tree cap projecting into the second profile forming the second retaining means to retain the internal tree cap within the bore; and 
 a loading member engaging the internal tree cap and movable longitudinally with respect to the internal tree cap causing a downward force on the internal tree cap portion and tubing hanger part to thereby prevent the cap housing portion and tubing hanger part from moving longitudinally with respect to the spool tree.