This invention relates in general to subsea wellhead equipment, and in particular to a method of simultaneously running an internal tree cap and tubing hanger into a subsea horizontal tree.
A conventional subsea horizontal tree includes a wellhead housing which contains one or more casing hangers, one of which is secured to a string of production casing that extends into the well. A horizontal tree body, also known as a tree or tubing spool or spool tree, mounts to the top of the wellhead housing and seals to it. The horizontal tree body has a central bore axially through it and a horizontal or lateral production flow passage through the wall of the horizontal tree body. A tubing hanger lands and seals in the central bore of the horizontal tree body and is secured to a string of tubing that extends through the production casing hanger and production casing into the well. The tubing hanger has a production bore axially through it that is in fluid communication with the tubing. The tubing hanger also has a lateral flow passage in fluid communication with the tubing hanger production bore and with the lateral production flow passage in the horizontal tree body.
Annular seals are located between the tubing hanger and the central bore of the horizontal tree body above the production flow passage to provide primary, and occasionally, secondary barriers to leakage from the production flow pathways and well bore. Additionally, one or more wireline deployable plugs fit in one or more lockdown profiles in the tubing hanger production bore to provide primary, and occasionally, secondary barriers to leakage from the production and well bores. A tree cap may also fit above the tubing hanger in the central bore of the horizontal tree body. The tree cap may be of an internal or external lockdown configuration. In either case, the tree cap will seal to the central bore of the horizontal tree body and act as an additional barrier to leakage from the well. The tree cap of either configuration may have a vertical bore through it.
Another typical feature of subsea horizontal trees is an annulus and workover passageway that establishes a fluid communication pathway between the annular space around the tubing below the tubing hanger and a space inside the central bore of the horizontal tree body above the tubing hanger. This annulus and workover passageway can be ported through the tubing hanger, through the horizontal tree body or a combination of both. Alternatively, the annulus and workover passageway may be ported entirely out of the tree from a position below the tubing hanger.
In practice, there are generally two horizontal tree configurations: (1) a horizontal tree with a tubing hanger fitted with one or more plugs in its production bore and an internal tree cap, with a plug in its vertical bore; or (2) a horizontal tree with a tubing hanger fitted with at least two plugs in its production bore and eliminating the internal tree cap. This second style of horizontal tree typically utilizes a tree cap that locks externally to the tree body and may or may not include a seal to the tree body. In either tree cap case, the annulus and workover passageway will contain at least two closure members in the form of gate valves, for example.
The primary difference between these two general horizontal tree configurations is that the first has a primary and secondary barrier that employs independent lockdown structures for the two barriers, and the second has a primary and secondary barrier that ultimately rely on the tubing hanger to horizontal tree body lockdown structure. Some operators, and some regulatory authorities believe that the first and second horizontal tree configurations are equivalently safe in operation. Other operators and regulatory authorities believe only the first configuration meets the dual barrier industry philosophies and/or regulatory requirements.
One advantage of the second configuration is that the elimination of the internal tree cap eliminates the need for a second drill pipe run to install it. In running (or working over) the first style of horizontal tree, the tubing hanger is run into the horizontal tree body typically on a hydraulically-actuated running tool that is run on drill pipe. Afterwards, the internal tree cap is run into the horizontal tree body typically on the same hydraulically-actuated running tool, or one very similar, on drill pipe. This results in two drill pipe trips to the seafloor.
In running (or working over) the second style of horizontal tree, the tubing hanger is run into the horizontal tree body typically on the hydraulically-actuated running tool on drill pipe. Afterwards, a lower plug is run on wireline and landed, locked and sealed to the production bore of the tubing hanger and then an upper plug is run on wireline and landed, locked and sealed to the production bore above the first plug. In deeper water wells, this results in potentially significant rig time savings. However, it comes with the compromise that the two plugs rely on the single tubing hanger lockdown mechanism to ensure that the tubing string assembly does not part from the tree and cause potentially significant leakage of the well bore to the environment.
In this invention, a new method for completing a subsea well is provided, which involves the simultaneous running of the tubing hanger and internal tree cap. This method provides substantially similar equipment running, retrieving and workover times for the horizontal tree configured for both a tubing hanger and an internal tree cap as is provided with the horizontal tree configured for a tubing hanger with multiple plugs and no separately locked and sealed internal tree cap. Thus, it provides the advantage of a horizontal tree with two separate pressure barriers carried on two separate structures with independent lockdown mechanisms, without the cost of significant operational time during installation and retrieval.
More particularly, the method comprises connecting a running tool to the internal tree cap and to the tubing hanger, then lowering the internal tree cap, tubing hanger and string of tubing as an assembly. After landing the running tool locks the tubing hanger and the internal tree cap to the bore of the tree.
Preferably the internal tree cap and the tubing hanger each have a radially movable locking element and an axially movable actuator. In some of the embodiments, the running is lowered after the tubing hanger lands, which causes the tree cap to stroke the actuator of the tubing hanger to cause the locking element of the tubing hanger to move radially into a profile formed in the bore of the tree. Then, the running tool strokes the actuator of the internal tree cap to cause the locking element of the internal tree cap to move radially into a profile formed in the bore of the tree. In other embodiments, a piston is incorporated within the internal tree cap to push the tubing hanger actuator downward after the tubing hanger lands.
Preferably, the running tool has a lifting member that connects to the internal tree cap and a linking assembly that connects between the internal tree cap and the tubing hanger. While running the assembly down to the subsea tree, the internal tree cap supports the weight of the tubing hanger and string of tubing through the linking assembly. After the tubing hanger is set, the linking assembly is retrieved. Preferably, the linking assembly is retrieved by a wireline tool lowered through the running string and running tool.
Referring to
Tubing hanger 17 is installed by a running tool 29 that has a lifting member 27 that engages a profile on the upper end of the body of tubing hanger 17. Running tool 29 has an actuating sleeve 31 that when actuated will stroke actuator 25. After setting, as shown in
Tree 11 typically has a tubing annulus bypass passage 32 that extends from tree bore 13 below tubing hanger 17 to above tubing hanger 17. Tubing annulus bypass 32 allows circulation between the annulus surrounding the tubing and the interior of the tubing.
Referring to
Referring to
In the method of this invention, running tool 45 runs tree cap 33 and tubing hanger 17 in the same trip. Running tool 45 has a linking assembly 53 that links internal tree cap 33 to tubing hanger 17 so that tree cap 33 will support the weight of tubing hanger 17 and the string of tubing. A spacer plate 52 is secured to the bottom of tubing hanger 33. Spacer plate 52 is movable from the outer position shown in
In the operation of the embodiment of
The operator runs running tool 45 on a string of conduit, such as drill pipe. The entire assembly comprising the string of tubing, tubing hanger 17, tree cap 33, and running tool 45 are lowered simultaneously. In this example, when tubing hanger 17 lands on landing shoulder 18, the operator continues to lower the running string a short distance. The weight of the running string transfers through running tool 45, to the tree cap 33, and from there through spacer plate 52 to tubing hanger actuator 25. This weight causes actuator 25 to move to the lower position, forcing tubing hanger locking member 23 into locking profile 24 as shown in
When tubing hanger actuator 25 is in its lowest position, tree cap shoulder 38 will be spaced a short distance above its landing shoulder 40, as shown in
In the embodiment just described, tubing hanger actuator 25 is set by the weight of the running string acting through tree cap 33. In the embodiment of
After tubing hanger 17 has landed on shoulder 18, initially tree cap shoulder 38 will be spaced a short distance above its landing shoulder 40. The operator signals running tool 45 to supply hydraulic fluid pressure to piston chamber 57. Piston 55 then pushes tubing hanger actuator 25 downward via load transfer plate 58 to cause locking element 23 to engage locking profile 24. The operator retracts piston 55 and allows load transfer plate 58 to shift inward from tubing hanger actuator 58.
It will be necessary to lower tree cap 33 downward a short distance so that it will land on its landing shoulder 40 before stroking tree cap actuator 36. One way to accomplish this movement is to retrieve linkage assembly 53, then lower tree cap 33 on the running tool 45. Alternately, the linkage assembly 53 could disengage from either tubing hanger internal profile 43 or tree cap internal profile 44, or both. Once, tree cap shoulder 38 has landed on shoulder 40, the operator uses running tool 45 to stroke tree cap actuator 36 to the locked position. The operator then releases running tool lifting member 47 from tree cap 33 and retrieves running tool 45.
Note that in both the embodiments of
Running tool 65, as in the other embodiments, has a lifting member 67 that will engage a profile on an upper portion of tree cap 33. Running tool 65 has a hydraulically actuated actuator 69 (
Slip joint sleeve 76 is rigidly secured by threads to lower linking sleeve 74. Upper linking sleeve 73 has an internal flange that engages an external flange 78 on slip joint sleeve 76 to transmit tension. When tubing hanger 17 has landed, upper linking sleeve 73 is downwardly moveable relative to slip joint sleeve 76, as shown by comparing
A stem 81 is located within the inner diameters of linking sleeve 73, lower linking sleeve 74 and slip joint sleeve 76. Stem 81 is rigidly secured at its lower end to the lower end of lower linking sleeve 74 for movement therewith. Stem 81 defines an annular space between its exterior and the interior of linking sleeves 73 and 74. Stem 81 may be solid or hollow. Stem 81 has a downward facing shoulder 83 on its exterior.
A backup sleeve 85 is reciprocally carried within the annular space between linking sleeves 73, 74 and stem 81. Backup sleeve 85 has a retrieval profile 87 on its upper end and an upward facing shoulder 89 spaced below stem shoulder 83. Backup sleeve 85 has an upper recess 91 that is dimensioned to receive upper dog 75 when backup sleeve 85 is pulled upward to the position of
In the operation of the embodiments of
The operator then lowers the entire assembly on a running conduit until tubing hanger 17 lands on its landing shoulder in the tree 11. At this point landing shoulder 38 on internal tree cap 33 will be spaced above its landing shoulder 40 in tree bore 13. The operator in this embodiment continues to lower the running string, which causes the weight to transfer to tree cap 33, through spacer 59 and to tubing hanger actuator 25. Tubing actuator 25 moves downward to sets tubing hanger locking element 23 as shown in
When tubing hanger actuator 25 is fully set, tree cap shoulder 38 will be spaced a short distance above landing shoulder 40, as shown in
The operator then runs a wireline tool 96 through the running string and running tool 65 into latching engagement with retrieval profile 87 on backup sleeve 85. The operator pulls upward on the wireline to move backup sleeve 85 upward relative to linking sleeves 73, 74 and stem 81. When backup sleeve 85 reaches its upper position shown in
In the embodiment of
Linking assembly 103 has a linking sleeve 105 that extends completely through tree cap passage 34 and into tubing hanger passage 19. Linking sleeve 105 carries a set of upper dogs 107 that engage tree cap internal profile 44. Linking sleeve 105 carries a set of lower dogs 109 that engage tubing hanger internal profile 43. A stem 111 with a retrieval profile 113 on its upper end inserts within the inner diameter of linking sleeve 105. Stem 111 has a set of wickers or grooves 114 that engage in a ratcheting arrangement with internal wickers 115 at the upper end of linking sleeve 105. When wickers 114, 115 are engaged, step 11 is retained in the lower position of
An expansion ring 117 is carried on an outer diameter portion of stem 111 radially inward from transfer plate 101. Expansion ring 117 has an inner position in engagement with a mating profile 119 on stem 111. When stem 111 is moved downward relative to expansion ring 117, expansion ring 117 will expand, pushing transfer plate 101 to its outer position, shown in
Stem 111 has an annular upper dog recess 121 that receives upper dogs 107 to place upper dogs 107 in the inner position when stem 11 is in the upper position shown in
Referring still to
In the operation of the embodiment of
The entire assembly is lowered into the well with the running string. Tubing hanger 33 will land in a position with its locking member 23 aligned with lower profile 24, as shown in
The operator may optionally detach running tool 65 in the conventional manner and retrieves the running string. Alternately, the operator may choose to install tubing hanger crown plug 133 and internal tree cap crown plug 135 as shown in
In each of the embodiments, tubing hanger 17 and tree cap 33 can be retrieved simultaneously by reversing the steps described. Alternately, tree cap 33 can be retrieved by a conventional running tool, then tubing hanger 17 retrieved in a separate trip by the same running tool. In each of the embodiments, after tubing hanger 17 and tree cap 33 are locked to tree bore 13 and the running tool assembly removed, tubing hanger 17 and tree cap 33 are free of any engagement with each other.
The invention has significant advantages. By simultaneously running the tree cap and tubing hanger, a separate trip with a drill pipe running string is not required. Omitting a trip can save a considerable amount of time in deep water. This method allows the use of a separate sealing member through an internal tree cap, rather than using two crown plugs within a tubing hanger as in the prior art. The various embodiments allow the tubing hanger and internal tree cap to be retrieved during a workover with a single running string trip.
While the invention has been shown in only a few of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention.