Wellhead system and method of operating a wellhead system
Patent Information
- Authority / Receiving Office
- GB · GB
- Patent Type
- Patents
- Current Assignee / Owner
- AKER SOLUTIONS SUBSEA AS
- Filing Date
- 2023-06-15
- Publication Date
- 2026-06-15
Smart Images
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Abstract
Description
BACKGROUND The present invention relates to a wellhead system, particularly, but not exclusively to a wellhead system including an orientation system for verifying the orientation of a 5 tubing hanger relative to a wellhead, and a method of operating a wellhead system. BACKGROUND A wellhead system typically comprises a wellhead housing mounted at the upper end of a wellbore, and a tubing hanger which is secured to the wellhead housing. The tubing hanger supports a long tubing string - known as production tubing, which io extends down into the wellbore, and which provides a conduit for the flow of formation fluid out of the wellbore. The tubing hanger may be supported by a tubing spool which is mounted on top of the wellhead, or directly in the wellhead housing. For a subsea wellhead, during the completion of the wellhead system, a blowout preventer (BOP) stack is mounted on the wellhead housing or, where a tubing spool is is used, on the tubing spool, and a riser extends upwards from the BOP stack to a surface rig or vessel. The tubing hanger and associated production tubing is installed by securing a tubing hanger running tool to the tubing hanger, and using a landing string to lower the tubing hanger running tool etc. down the riser towards the wellhead, and land the tubing hanger in the desired position in the tubing spool I 20 wellhead housing. The tubing hanger running tool can then be disconnected from the tubing hanger, and the landing string and tubing hanger running tool lifted out of the riser. The well is then prepared for completion by temporarily plugging the tubing hanger / production tubing, and removing the riser and BOP. A Christmas tree is then mounted on top of the tubing spool I wellhead housing, and the 25 Christmas tree connected, via a tie-in arrangement, to production flow lines which carry the formation fluids flowing out of the wellbore. In order to ensure that the tie-in connections between the Christmas tree and the production flowlines are properly made up, it is important to land the Christmas tree so that it is oriented in a predetermined orientation relative to the wellhead housing 30 and associated external structures such as a permanent guide base or template. If the Christmas tree is rotated about the longitudinal axis of the wellhead housing by 15 08 25 even a few degrees from the desired orientation, proper make-up of the tie-in connectors may be impossible. Tubing hangers often provide conduits for communication between topside and the space in the wellhead below the tubing hanger, for example, for communication with 5 or operation of sensors or equipment in the wellbore. These could be conduits for fluid flow, or comprise connections for the transmission of electrical or optical signals. Typically stab connectors or the like are provided at the upper end of the tubing hanger to provide the means for connection to these conduits I connections, and these mate with corresponding connectors provided on the Christmas tree when io the Christmas tree is landed on the wellhead. As such, because of these connections between the Christmas tree and the tubing hanger, the orientation of the Christmas tree is set by the orientation of the tubing hanger relative to the wellhead housing. It is therefore critical that when the tubing hanger is landed in the wellhead it is correctly oriented relative to the wellhead, in order to ensure that the is orientation of the Christmas tree is correct when it is eventually landed. Any misalignment of the tubing hanger may not become apparent until after the well is completed, and the riser and BOP removed, and a dedicated measurement tool is landed on the tubing hanger, and tested. At this point, to remedy the situation, it is necessary to reinstall the BOP and riser, and pull and reinstall the tubing hanger - a 20 process which is enormously time consuming and expensive. It will be appreciated that where the wellhead is located in deep water, the landing string can be very long, and there can be significant twisting of the landing string as the tubing hanger running tool and tubing hanger are lowered down the riser. As such, knowledge of the orientation of the tubing hanger running tool / tubing hanger 25 when it was first lowered into the riser, does not assist in providing a sufficiently accurate knowledge of the orientation of the tubing hanger running tool once it has been lowered down the riser and is approaching the wellhead landing shoulder. As such, it is known to provide a mechanical orientation system in which a formation such as a pin or key, which is mounted on a part secured relative to the wellhead 30 housing (typically in the BOP stack), interacts with an helical groove or ridge arranged around a part secured relative to the tubing hanger, in order to rotate the tubing hanger into the required orientation relative to the wellhead. 15 08 25 An example of such mechanical orientation systems is described in WO 2020 / 146187. In the system disclosed in this document, a hanger orientation device, having a helical profile is mounted between the landing string and the tubing hanger running tool. A helical ridge is provided on the radially outward facing 5 surface of the hanger orientation device, and this engages with a pin which is mounted on the wellhead to rotate the tubing hanger to the desired orientation. WO2022 / 103272 describes a wellhead system comprising a landing assembly and wellhead assembly, the landing assembly being provided with an orientation sensor assembly which is configured to measure the angular rotation of the landing string io about its longitudinal axis. The orientation sensor assembly may be used to ensure that the landing assembly is correctly orientated when it is landed in the wellhead assembly. The present application relates to a new wellhead system which is configured such that the ease of landing a landing assembly in a wellhead assembly at a precise is orientation may be further improved. SUMMARY According to a first aspect of the disclosed technology we provide a wellhead system comprising a generally tubular wellhead assembly with a main passage having a longitudinal axis, the wellhead assembly being configured to be secured to 20 the top of a borehole, the wellhead assembly having an interior surface which encloses the main passage, the wellhead system further comprising a landing assembly comprising a tubing hanger, the landing assembly being configured to be lowered into the main passage of the wellhead assembly to land the tubing hanger in the wellhead assembly, the landing assembly having a longitudinal axis and 25 further comprising an orientation control assembly which comprises an orientation engagement assembly having a segmented sleeve and an actuator system which is configured to move the orientation engagement assembly between a retracted configuration and an engaged configuration in which the segmented sleeve engages with the interior surface of the wellhead assembly, the orientation control assembly 30 further comprising a motor and a drive part which is configured to engage with the orientation engagement assembly and, when driven by the motor, to rotate the landing assembly about its longitudinal axis. 15 08 25 The orientation engagement assembly and drive part may be configured, when the orientation engagement assembly is in its engaged configuration and also engaged with the drive part, to prevent rotation of the landing assembly relative to the wellhead assembly in the absence of operation of the motor. 5 The motor may comprise a hydraulic or electric motor. The drive part may be connected to the motor such that operation of the motor rotates the drive part. In this case, operation of the motor may rotate the drive part about an axis of rotation which is parallel to the longitudinal axis of the landing assembly. io The drive part may comprise a plurality of radially outwardly extending teeth, and the orientation engagement assembly may comprise an orientation engagement part having a plurality radially inwardly extending teeth which are configured to mesh with the teeth of the drive part. The drive part may comprise a pinion gear. is The orientation control assembly may comprise a body and the orientation engagement assembly may be annular and extend around the entire circumference of the body. The orientation control assembly may comprise a body and the segmented sleeve may comprise a locking part which is movable radially outwardly of the body to 20 engage with the interior surface of the wellhead assembly. The orientation engagement assembly may comprise a plurality of locking parts which are movable radially outwardly of the body to engage with the interior surface of the wellhead assembly. The actuator system may be driven by the motor and drive part to move the or each 25 locking part from its retracted configuration to its engaged configuration, the drive part rotating the landing assembly about its longitudinal axis once the or each locking part is in its engaged configuration. The actuator system may be moved by the supply of pressurised fluid to the actuator system to move the or each locking part from the retracted configuration to 30 the engaged configuration. 15 08 25 Advantageously, the orientation control assembly further comprises an orientation sensor assembly which is configured to measure the orientation of the tubing hanger. The system may further comprise a controller which is connected to the motor and 5 configured to control the operation of the motor, and which is connected to the orientation sensor assembly and configured to receive a signal from the orientation sensor assembly indicative of the orientation of the tubing hanger. The controller may be further configured to use the signal from the orientation sensor assembly to determine whether the orientation of the tubing hanger deviates io from a desired orientation, and to operate the motor to rotate the tubing hanger about its longitudinal axis to bring the tubing hanger to the desired orientation. The wellhead system may further comprise a soft landing device which is operable to allow downward movement of the tubing hanger in the wellhead through a travel distance after initial engagement of the tubing hanger with a landing surface is provided in the wellhead from an initial landing position to a final landing position. In this case, the orientation engagement assembly and drive part may be configured to remain engaged as the tubing hanger moves with the landing surface as the landing surface moves from its initial landing position to its final landing position. The drive part may comprise a plurality of radially outwardly pointing teeth, and the 20 orientation engagement assembly may comprise an orientation engagement part having a plurality of radially inwardly pointing teeth which are configured to mesh with the teeth of the drive part, the teeth of the drive part each comprising a radially outwardly pointing ridge which extends generally parallel to the longitudinal axis of the landing assembly. 25 The teeth of the drive part may each comprise a radially outwardly pointing ridge which extends generally parallel to the longitudinal axis of the landing assembly along a distance which is at least as long as the travel distance of the tubing hanger. Alternatively, or additionally the drive part may comprise a plurality of radially outwardly pointing teeth, and the orientation engagement assembly may comprise 30 an orientation engagement part having a plurality of radially inwardly pointing teeth which are configured to mesh with the teeth of the drive part, the teeth of the orientation engagement part each comprising a radially inwardly pointing ridge 15 08 25 which extends generally parallel to the longitudinal axis of the main passage of the wellhead assembly. The teeth of the orientation engagement part may each comprise a radially inwardly pointing ridge which extends generally parallel to the longitudinal axis of the main 5 passage of the wellhead assembly along a distance which is at least as long as the travel distance of the tubing hanger. The system may further comprise a landing string, the landing assembly being mounted on an end of the landing string. According to a second aspect of the disclosed technology we provide a method of io operating a wellhead system according to the first aspect, the method comprising the steps of: a) mounting the landing assembly on an end of a landing string, b) lowering the landing assembly into the wellhead assembly, c) operating the actuating system to move the orientation engagement is assembly into its engaged configuration with the interior surface of the wellhead assembly, and d) operating the motor to rotate the tubing hanger to a desired orientation relative to the wellhead assembly. 20 Step b may comprise lowering the landing assembly into the wellhead assembly to land the tubing hanger on a landing surface provided on the interior surface of the wellhead assembly. The wellhead system may further comprise a soft landing device which is operable to allow downward movement of the tubing hanger in the wellhead through a travel 25 distance after initial engagement of the tubing hanger with a landing surface provided on the wellhead from an initial landing position to a final position, step b may comprise lowering the landing assembly into the wellhead assembly to land the tubing hanger in the initial landing position on a landing surface provided on the interior surface of the wellhead assembly, and the method may further include, after 30 carrying out step d, lowering the landing assembly further into the wellhead so that the tubing hanger moves from its initial landing position to its final landing position. 15 08 25 The orientation engagement assembly may be retained in its engaged configuration whilst the tubing hanger is lowered from its initial landing position to its final landing position. BRIEF DESCRIPTION OF THE DRAWINGS 5 These and other characteristics will become clear from the following description of illustrative embodiments, given as non-restrictive examples, with reference to the attached drawings, in which FIGURE 1 is a schematic illustration of a wellhead system according to the invention secured to the top of a subsea wellbore. io FIGURE 2 is an illustration of a longitudinal cross-section through a first embodiment of wellhead system according to the invention; FIGURE 3 is an enlarged illustration of the portion enclosed in dashed lines and labelled X in Figure 2, FIGURE 4 is an illustration of a transverse cross-section through the drive part and is orientation engagement assembly of the wellhead system along the line Y shown in Figure 3, FIGURE 5a and 5b are enlarged illustrations of portion of the wellhead and tubing hanger illustrated in figure 3 where the system is provided with a soft landing device, Figure 5a showing the tubing hanger in its initial landing position, and Figure 5b 20 showing the tubing hanger in its final landing position, FIGURE 6 is an illustration of a longitudinal cross-section through a second embodiment of wellhead system, FIGURE 7 is an enlarged illustration of the portion enclosed in dashed lines and labelled X in Figure 6, 25 FIGURE 8 is an illustration of a transverse cross-section through the wellhead system along the line Y shown in Figure 7, and FIGURE 9 is a perspective illustration of a portion of the orientation control assembly of the wellhead system illustrated in Figure 6. DETAILED DESCRIPTION 15 08 25 The following description may use terms such as “horizontal”, “vertical”, “lateral”, “back and forth”, “up and down”, ’’upper”, “lower”, “inner”, “outer”, “forward”, “rear”, etc. These terms generally refer to the views and orientations as shown in the drawings and that are associated with a normal use of the invention. The terms are 5 used for the reader’s convenience only and shall not be limiting. Figure 1 shows a wellhead system 10 comprising a generally tubular wellhead assembly 12 with a main passage 14 and having a longitudinal axis A. The wellhead assembly 12 is configured to be secured to the top of a subsea wellbore 16. The wellhead assembly 12 comprises a wellhead 18 which is mounted on top of the io wellbore at the seabed 20, and a blowout preventer (BOP) stack 22 which is mounted on top of the wellhead 18 via a connector 24. The wellhead system 12 further comprises a landing assembly 26 which is mounted on the end of a landing string 28. The landing assembly 26 comprises a tubing hanger 30, which is secured to a tubing hanger running tool 32. The landing is assembly 26 further comprises an orientation control assembly 34 which, in this embodiment is connected to the tubing hanger running tool 32 via a spacer sub 36. In this embodiment, the spacer sub 36 is connected to the tubing hanger running tool 32, and to the orientation control assembly 34 by means of threaded tool joints provided at each end of the spacer sub 36. 20 A riser 38 extends vertically upwards from the top of the BOP stack 22 to the ocean surface. The landing assembly 26 is configured to be lowered down the riser 38 on the landing string 28 into the main passage 14 of the wellhead assembly 12 to land the tubing hanger 30 in the wellhead 18. Tubing 40 is suspended from the tubing 25 hanger 30 and extends down into the wellbore 16. The wellhead system 10 is shown in more detail in Figure 2. The wellhead assembly 12 has an interior surface 42 which encloses the main passage 14. The BOP stack 22, the connector I spool 24 and the wellhead 18 each provide a portion of the interior surface 42. There is a shoulder 44 in the interior surface 42a of the 30 wellhead 18, the uppermost surface 46 of which is configured to engage with a corresponding landing surface 30a provided on the lowermost end of the tubing hanger 30 to support the tubing hanger 30 in the wellhead 18. 15 08 25 The landing assembly 28 also has a longitudinal axis, and in this embodiment, the longitudinal axis of the landing assembly 28 is coaxial with the longitudinal axis A of the wellhead assembly 12 when the tubing hanger 30 is landed on the shoulder 44. The orientation control assembly 34 of the landing assembly 26 comprises an 5 orientation engagement assembly 48, and an actuator system 49 (which will be described in more detail below) which is configured to move the orientation engagement between a retracted configuration and an engaged configuration in which it engages with the interior surface 42 of the wellhead assembly 12. It further comprises a motor 50 and a drive part 52 which is configured to engage with the io orientation engagement assembly 48 and, when driven by the motor 50, to rotate the landing assembly 26 about its longitudinal axis A. The motor 50 may comprise a hydraulic or electric motor. The drive part 52 is connected to the motor 50 such that operation of the motor 50 rotates the drive part 52. Specifically, in this embodiment, operation of the motor 50 is rotates the drive part 52 about an axis of rotation which is parallel to the longitudinal axis A of the landing assembly 26. The orientation control assembly 34 is shown in more detail in Figures 3 and 4. The orientation control assembly 34 has a tubular body 54 on which the motor 50 is mounted. The body 54 encloses a central passage 55, which, when the tubing 20 hanger 30 is landed in the wellhead 18 is coaxial with the longitudinal axis A of the wellhead assembly. The motor 50 is mounted on a first end 54a of the body 54, and a second, opposite end 54b of the body 54 is provided with a threaded tool joint to which the spacer sub 36 is secured. The motor 50 is connected to the drive part 52 by means of a drive 25 shaft 56 which has a longitudinal axis B and which extends along a drive shaft passage 58 provided in the body 54. The drive shaft passage 58 is general parallel to the central passage 55, and so the longitudinal axis B of the drive shaft 56 extends parallel to the longitudinal axis A of the wellhead assembly 12. The drive part 52 is mounted in a recess in the body 54 and is accessible to the orientation 30 engagement assembly 48 via an opening I window the radially outwardly facing surface of the body 54. The motor 50 is operable to rotate the drive shaft 56 and the drive part 52 about the axis B. The motor 501 drive shaft 56 and drive part 52 are advantageously configured so that there can be no rotation of the drive part 52 15 08 25 unless the motor is operational. In other words, the drive part 52 can only rotate when driven by the motor 50. The drive part 52 comprises a plurality of radially outwardly pointing teeth, and the orientation engagement assembly 48 comprises an orientation engagement part 48a 5 which has a plurality radially inwardly pointing teeth which mesh with the teeth of the drive part 52. Specifically, in this embodiment, the drive part 52 comprises a pinion gear, and the orientation engagement part 48a comprises an annular gear which extends around the entire circumference of the body 54. These are best seen in Figure 4. io In order to provide support for the orientation engagement assembly 48 around the entire circumference of the body 54, advantageously, a plurality of idler pinion gears are arranged around the body 54. The idler pinion gears, like the drive part 52, are provided with a plurality of teeth which mesh with the teeth of the orientation engagement assembly 48. Unlike the drive part 52, these idler gears are not driven is and are merely pivotally mounted in passages provided in the body 54 for rotation about an axis which is parallel to the longitudinal axis B of the drive shaft 56. The landing assembly 26 further comprises an orientation sensor assembly 60 which is configured to measure the orientation of the landing assembly. Any form of sensor which can measure the orientation of an object relative to true north, or 20 relative to a feature within the wellhead assembly 12 could be used. In this embodiment, one end of the orientation sensor assembly 60 is mounted on the first end 54a of the body 54, the other end of the orientation sensor assembly 60 being secured to the landing string 28 via a support clamp 62 which is clamped to the landing string 28 so that movement of that end of the orientation sensor 25 assembly 60 relative to the landing string 28 is prevented. In this embodiment, the landing string 28 is secured to the first end 54a of the body 54 via a second spacer sub 64 which is connected to the first end 54a of the body 54 and to the landing string 28 by means of threaded tool joints provided at either end of the second spacer sub 64. The orientation sensor assembly 60 therefore extends alongside the 30 second spacer sub 64. The orientation sensor assembly 60 engages with a locating feature such as a pocket or recess provided in the body 54 so that the precise position of the orientation sensor assembly 60 relative to the body 54 is fixed and known. 15 08 25 The wellhead system 10 further comprises a controller 63 which is connected to the motor 50 and configured to control the operation of the motor 50, and which is connected to the orientation sensor assembly 60 and configured to receive a signal from the orientation sensor assembly 60 indicative of the orientation of the landing 5 assembly 26. The controller 63 may be conveniently located at a topside location, and connected to the motor 501 orientation sensor assembly 60 via a conventional wired or wireless connection. In this embodiment, the orientation control assembly 34 comprises a seal carrier 66 which is mounted around the body 54 of the orientation control assembly 34 io between the drive part 52 and the second end 54b thereof. The seal carrier 66 is secured to the body 54 via a threaded retainer ring 68. The seal carrier 66 has a stepped radially outward facing surface with a first portion 66a and a second portion 66b, the first portion 66a having a larger diameter than the second portion 66b. A ring seal 70a, 70b is mounted in a groove provided in each of the first portion 66a is and second portion 66b of the radially outwardly facing surface of the seal carrier 68. In this embodiment, the orientation engagement assembly 48 comprises a support sleeve 72, which acts to retain the orientation engagement assembly 48 on the body 54. The support sleeve 72 has a correspondingly stepped radially inwardly facing 20 surface having a first portion 72a and a second portion 72b, the first portion 72a having a greater internal diameter than the second portion 72b. The orientation engagement part 48a is mounted at the uppermost end of the support sleeve 72, and the support sleeve 72 extends from the orientation engagement part 48a around the seal carrier 66 towards the second end 54b of the body 54. The first seal 70a 25 engages with first portion 72a of the support sleeve 72, and the second seal 70b engages with the second portion 72b of the support sleeve 72. A seal chamber 82 is formed between the steps in the radially outwardly facing surface of the seal carrier 66 and the radially inwardly facing surface of the support sleeve 72 and is enclosed by the seals 70a, 70b. The volume of the seal chamber 82 can be 30 changed by sliding the support sleeve 72 along the seal carrier 66 parallel to the longitudinal axis B of the drive shaft 56. Engagement of the step between the first portion 72a and the second portion 27b of the support sleeve 72 and the step between the first portion 66a and the second portion 66b of the seal carrier 66 limits 15 08 25 this movement of the support sleeve 72, and the volume of the seal chamber 82 is minimised when the two steps are engaged. The radially outward facing surface of the body 54 between the drive part and the first end 54a thereof is stepped and has a first portion 54c which is adjacent to the 5 first end 54a and a second portion 54d which is adjacent the opening I window which provides access to the drive part 52, the first portion 54c having a larger diameter than the second portion 54d. A ring seal 74a, 74b is mounted in a groove provided in each of the first portion 54c and second portion 54c of the radially outwardly facing surface of the body 54. io In this embodiment, the actuator system 49 is fluid pressure operated, i.e. acts to move the orientation engagement assembly 48 from its retracted position to its engaged configuration in response to the supply of pressurised fluid to the actuator system 49. In this example, the actuator system 49 comprises an energiser sleeve 76, which is mounted around the body 54. The energiser sleeve 76 has a stepped is radially inward facing surface with a first portion 76a and a second portion 76b, the first portion 76a having a larger diameter than the second portion 76b. The first portion 76a of the energiser sleeve contacts the first portion 54c of the body 54 and is in sealing engagement with the ring seal 74a mounted therein, and the second portion 76b of the energiser sleeve 76 contact the second portion 54d of the body 54 20 and is in sealing engagement with the ring seal 74b mounted therein. An energiser actuation chamber 78 is formed between the steps in the radially inwardly facing surface of the energiser sleeve 76 and the radially outwardly facing surface of the body 54, enclosed by the seals 74a, 74b. The volume of the seal chamber 82 can be changed by sliding the energiser sleeve 76 along the body 54 parallel to the 25 longitudinal axis B of the drive shaft 56. Engagement of the step between the first portion 76a and the second portion 76b of the energiser sleeve 76 and the step between the first portion 54c and the second portion 54d of the body 54 limits this movement of the energiser sleeve 76, and the volume of the energiser actuation chamber 78 is minimised when the two steps are engaged. 30 The energiser sleeve 76 is tapered at its lowermost end 76c, with the radially outwardly facing surface of the energiser sleeve 76 at the tapered end portion 76c being inclined relative to the longitudinal axis A of the drive shaft 56, in this example, at an angle of around 20°. 15 08 25 The orientation engagement assembly 48 is also provided with a locking part which is movable to engage with the interior surface 42b of the BOP stack 42. In this embodiment, the locking part comprises a tapered expandable collet 80 which is connected to the annular gear, at the opposite side of the annular gear to the 5 support sleeve 72. In other words, whilst the support sleeve 72 extends from the annular gear towards the second end 54b of the body 54, the collet 80 extends from the annular gear towards the first end 54a of the body 54. It should be appreciated that, by virtue of the arrangement of stepped surfaces described above, the separation of the energiser sleeve 76 and the support sleeve io 72 is greatest when the volumes of the seal chamber 82 and the energiser actuation chamber 78 are both minimum. Sliding movement of the energiser sleeve 76 to increase the volume of the energiser actuation chamber 78 moves the lowermost end 76c of the energiser sleeve 76 towards the expandable collet 80, and sliding movement of the support sleeve 72 to increase the volume of the seal chamber 82 is moves the collet 80 towards the lowermost end 76c of the energiser sleeve 76. The energiser actuation chamber 78 and the seal chamber 82 are both connected to a source of pressurised fluid (in this embodiment, they are both connected to the same source of pressurised fluid). This could be achieved via a fluid flow passage which extends through the body 54 from the top end 54a thereof, a first branch 20 extending through the body 54 into the second portion 54d adjacent the step, and a second branch extending through the body 54 to the seal carrier 66, and through the second portion 66b of the seal carrier 66 adjacent the step. The fluid flow passage could be connected to a top side source of pressurised fluid via a line which extends down the landing string 28. 25 The wellhead system 10 may be operated to install the tubing hanger 30 in the wellhead 18 by mounting the landing assembly 26 on an end of the landing string 28 and using the landing string 28 to run the landing assembly 26 down the riser 38 and into the wellhead assembly 12. When the tubing hanger 30 lands on the uppermost surface 46 of the landing shoulder 44, the orientation sensor assembly 30 60 is used to determine the angular orientation of the landing assembly 26 (either its absolute orientation or its orientation relative to the wellhead). This is compared with the desired orientation of the landing assembly 26, and if the landing assembly 26 is not in the desired orientation, the orientation control assembly 34 is operated as follows to rotate the tubing hanger 30 to the desired orientation as follows. 15 08 25 Pressurised fluid is supplied to the energiser actuation chamber 78 and the seal chamber 82, and this moves the energiser sleeve 76 and support sleeve 72 so that the collet 80 is forced into the tapered space between the tapered portion 76c of the energiser sleeve 76 and the interior surface 42b of the BOP stack 22. The collet 80 5 thus engages with the tapered radially outwardly facing surface of the lowermost end 76c of the energiser sleeve 76. As the supply of pressurised fluid continues, and the volumes of the energiser actuation chamber 78 and seal chamber 82 increase further, the radially outwardly facing tapered surface at the lowermost end 76c of the energiser sleeve 72 exerts a radially outward force on the collet 80 which io acts to expand the collet 80. Initially, the collet 80 resists such expansion. The step in the radially inwardly facing surface of the energiser sleeve 76 is bigger than the stop in the radially outwardly facing surface of the seal carrier 66, so the downwards force acting on the energiser sleeve 76 is greater than the force pushing the support sleeve 72, orientation engagement assembly 48 and collet 80 upwards. As such, is instead of expanding the collet 80, further supply of pressurised fluid causes the volume of the energiser actuation chamber 78 to continue to increase, whilst the volume of the seal chamber 82 decreases. In other words, the energiser sleeve 76, collet 80, orientation engagement part 48a and support sleeve 72 move together towards the second end 54b of the body 54. Eventually, the support sleeve 72, 20 orientation engagement part 48a and collet 80 moves to a lowermost position in which the volume of the seal chamber 82 is minimum and the step between the first portion 72a and the second portion 27b of the support sleeve 72 engages with the step between the first portion 66a and the second portion 66b of the seal carrier 66. As the fluid pressure in the energiser actuation chamber 78 continues to rise, 25 eventually it is sufficient for the lowermost end 76c of the energiser sleeve 76 to force the collet 80 to expand into engagement with the interior surface 42b of the BOP stack 22. The collet 80 grips the interior surface 42b of the BOP stack 22, and prevents movement of the orientation engagement assembly 48 relative to the wellhead assembly 12. To enhance this gripping force, the radially outwardly facing 30 surface of the collet 80 may be provided with features such as teeth, ridges, or striations, or may simply have a roughened surface which increase the coefficient of friction between the collet 82 and the interior surface 42b of the BOP stack 22. The motor 50 is then operated to rotate the drive part 52. By virtue of the meshing of the teeth of the drive part 52 with the teeth of the orientation engagement part 15 08 25 48a, and the gripping action of the collet 82 on the interior surface 42b of the BOP stack 22, rotation of the drive part 52 drives rotation of the landing assembly 26 within the wellhead assembly about the longitudinal axis A of the wellhead assembly. Using the signal from the orientation sensor assembly 60, the motor 50 5 is operated to rotate the landing assembly 26 until it reaches the desired orientation. It will be appreciated that this process could be carried out manually, with an operator reviewing the signal from the orientation sensor assembly 60 and controlling the operation of the motor 50 based on that signal. Advantageously, however, the controller 63 is configured to use the signal from the orientation sensor io assembly to determine of the orientation of the landing assembly deviates from a desired orientation, and automatically to operate the motor 50 to rotate the landing assembly 26 about its longitudinal axis to bring the landing assembly 26 to the desired orientation. Advantageously, the motor 50 is configured to be controllable to rotate the drive is shaft 56 in either a clockwise or anticlockwise direction depending on the direction of the rotation required to bring the landing assembly to the desired orientation in the minimum number of rotation of the drive shaft 56. The orientation engagement assembly 48 and drive part 52 are configured such that, when the orientation engagement assembly 48 is in its engaged configuration 20 and engaged with the drive part 52, rotation of the landing assembly 26 relative to the wellhead assembly 12 is prevented in the absence of operation of the motor 50. As such, once the landing assembly 26 is in its desired orientation, the motor 50 is switched off to fix the orientation of the landing assembly 26. The tubing hanger 30 may be moveable generally parallel to the longitudinal axis A 25 of the main passage through a travel distance between an initial landing position at which it first engages with the uppermost surface 46 of the landing shoulder 44 of the wellhead 18 and a final landing position. This may be achieved using a soft landing adapter of the sort disclosed in US 6,581,691, for example. The soft landing adapter is mounted on the lowermost end of the tubing hanger body and provides 30 the landing surface 30a. This arrangement is configured such that the landing surface 30a is held in the initial landing position, in which it is in an extended position, as the landing assembly 26 is run into the wellhead, and the tubing hanger 30 is landed on the shoulder 44 of the wellhead 18 whilst the landing surface 30a is 15 08 25 in the initial landing position. After engagement of the landing surface 30a with the uppermost surface 46 of the shoulder 44, the landing surface 30a retracts to the final landing position by the release of hydraulic fluid from a piston and cylinder arrangement, thus lowering the tubing hanger 30 to its final landing position in a 5 controlled manner. Such a soft landing adapter is designed to act as a buffer between the landing shoulder 44 in the wellhead 18 and the tubing hanger 30, and to absorb the impact of the tubing hanger 30 landing in the wellhead, thus avoiding or minimising damage to the tubing hanger 30 on landing. Whilst in this embodiment, the soft landing adaptor is provided on the tubing hanger io 30, it should be appreciated that this need not be the case. It could, instead, be provided on the wellhead 18, so that the uppermost surface 46 of the landing shoulder 44 is movable between an initial landing position and a final landing position, the initial landing position being higher than the final landing position. The soft landing adaptor 84 is illustrated schematically in Figures 5a and 5b. Figure is 5a shows the tubing hanger 30 in the initial landing position, and Figure 5b shows the tubing hanger in the final landing position. Where provision for soft landing of the tubing hanger 30 in the wellhead 18 is provided, advantageously, the above process for rotation of the tubing hanger 30 into its desired orientation is carried out when the tubing hanger 30 is in its initial 20 landing position. Once the desired orientation has been achieved, the motor 50 is shut off, and the fluid pressure in the energiser actuation chamber 78 and the seal chamber 82 is maintained so that the orientation engagement part 48 remains gripped to the interior surface 42b of the BOP stack 22. A downward force is applied to the landing string 28 to move the tubing hanger 30 (and with it, body 54 25 and carrier sleeve 66) downwards into the final landing position. The energiser sleeve 76, collet 80, orientation engagement part 48a and support sleeve 72 remain fixed to the interior surface 42b of the BOP stack 22, and the downwards movement of the body 54 is accommodated by an increase in the volume of the seal chamber 82 and a decrease in the volume of the energiser actuation chamber 78. The 30 downwards force applied to the landing string 28 must therefore be large enough to overcome the net force of the pressurised fluid resulting from the upwards force exerted on the body 54 by the pressurised fluid in the energiser actuation chamber 78 and the downwards force exerted on the body 54 by the pressurised fluid in the seal chamber 82. 15 08 25 In this embodiment, the drive part 52 has a length L generally parallel to the longitudinal axis B of the drive shaft 56 which is equal to or greater than the travel distance of the tubing hanger 30. The teeth of the drive part 52 comprise a radially outwardly pointing ridge which extends generally parallel to the longitudinal axis B of 5 the drive shaft 56 along the length L of the drive part 52, each pair of adjacent ridges being separated by a corresponding groove. When the tubing hanger 30 is in its initial landing position, the orientation engagement part 48a engages with the radially outward facing teeth of the drive part 52 at the lowermost end of the drive part 52. As the teeth (and also the grooves between the teeth) extend parallel to the io longitudinal axis A of the wellhead assembly 12, the body 54 can be lowered to lower the tubing hanger 30 to its final landing position with the teeth of the orientation engagement part 48a moving along the grooves between the teeth of the drive part 52, until, when the tubing hanger 30 reaches its final landing position, the teeth of the orientation engagement part 48a are located between the teeth of the is drive part 52 at the uppermost end of the drive part 52. It will be appreciated that this could equally be achieved by the orientation engagement part 48a having a length generally parallel to the longitudinal axis A of the wellhead assembly 12 which is equal to or greater than the travel distance of the tubing hanger 30. In this case, the teeth of the orientation engagement part 48a 20 would each comprise a radially inwardly pointing ridge (each pair of adjacent ridges being separated by a groove) which extends generally parallel to the longitudinal axis A of the wellhead assembly 12 along the length of the orientation engagement part 48a. The orientation engagement assembly 48 is positioned in the wellhead assembly 12 such that when the tubing hanger 30 is in its initial landing position, the 25 teeth at the uppermost end of the orientation engagement assembly 48 engage with the radially outward facing teeth of the drive part 52. As the teeth (and also the grooves between the teeth) extend parallel to the longitudinal axis A of the wellhead assembly 12, the body 54 can be lowered as the tubing hanger 30 is lowered to its final landing position with the teeth of the drive part 52 moving along the grooves 30 between the teeth of the orientation engagement assembly 48, until, when the tubing hanger 30 reaches its final landing position, the teeth of the drive part 52 are located between the teeth of the orientation engagement assembly 48 at the lowermost end of the orientation engagement assembly 48. 15 08 25 Where the wellhead system 10 is configured to provide a soft landing for the tubing hanger 30. The system 10 is advantageously operated to use the motor 50 to rotate the landing assembly 26 to its desired orientation when the tubing hanger 30 is in its initial landing position. Once the landing assembly 26 is in its desired orientation, 5 the operation of the motor 50 is stopped, and the lowering of the tubing hanger 30 is continued until it reaches its final landing position. As explained above, the drive part 52 can only rotate when driven by the motor 50, so after the motor 50 is stopped, there can be no rotation of the drive part 52. Also as explained above the teeth of the drive part 52 remain meshed with the teeth of the orientation io engagement part 48a whilst the tubing hanger 30 is lowered from its initial landing position to its final landing position. This ensures that that the landing assembly 26 cannot rotate from its desired orientation during the movement of the tubing hanger 30 to its final landing position. An alternative embodiment of orientation control assembly 34’ is illustrated in is Figures 6-9. Figure 6 shows a wellhead system 10 with a landing assembly 26 incorporating the alternative embodiment of orientation control assembly 34’. The same reference numerals are used as in Figures 1 - 5b to designate the common parts. The description below will focus on the differences between the embodiments, and parts not described below should be assumed to be the same as 20 in the embodiments illustrated in Figures 1 - 5b. The alternative embodiment of orientation control assembly 34’ is illustrated in more detail in Figures 7-9. The main differences lie in the configuration of the orientation engagement assembly 48’, the body 54’ and the actuator system 49’. In particular, rather than being operated by the supply of pressurised fluid, the actuator 25 system 49’ is operated by the motor 50. Moreover, rather than using a collet 80, movement of the orientation engagement formation 48 relative to the BOP stack 22 is prevented by means of a plurality of locking dogs which are movable radially outwardly to engage with the interior surface 42b of the BOP stack 22. As before the body 54’ of the orientation control assembly 34’ has a first end 54a’ 30 which is secured to the landing string 28 via the second spacer sub 64, and a second end 54b which is secured to the tubing hanger running tool 32 via a first spacer sub 36. In this embodiment, however, the body 54’ has a radially outwardly extending flange part 100 provided at the first end 54a’ thereof. The orientation engagement assembly 48’ comprises an annular dog cage 102, which is mounted 15 08 25 around the body 54 between the flange part 100 and the second end 54b’ of the body 54’, and is supported on the body 54’ by an end stop 103 which is secured to the body 54’ by a retainer ring 104. The motor is mounted on an uppermost surface of the flange part 100 and a first 5 end 56’ of the drive shaft 56 extends from the motor 50 through an aperture provided in the flange part 100 towards the second end 54b’ of the body 54. A second end portion 56b of the drive shaft is lodged in a bearing assembly I bushing 106 which is supported between the end stop 103 and a radially outwardly extending ledge 108 provided on the body 54’. A further bearing assembly I bushing io 108 is provided in the aperture in the flange part 100, both bearing assemblies supporting the drive shaft 56 for rotation about its longitudinal axis B when driven by the motor 50. In this embodiment, the drive part 52’ comprises an intermediate portion of the drive shaft 56’, which is provided with a plurality of radially outwardly extending teeth, best is illustrated in Figure 8. Again, the orientation engagement assembly 48’ comprises an orientation engagement part 48a’ which in this embodiment is an annular gear which has a plurality of radially inwardly extending teeth which mesh with the teeth of the drive part 52’ as illustrated in Figure 8. The orientation engagement part 48a’ is arranged radially inwardly of the dog cage 102, and is captured between the end 20 stop 103 and an annular spring carrier 109. A second retainer ring 109a is mounted around the orientation engagement part 48a’ and engages with the dog cage 102 to secure the dog cage 102 around the orientation engagement part 48a’, the dog cage 102 being captured between the second retainer ring 109a and the end stop 103. In this embodiment, idler gears 110 are mounted on the body 54’ and these also 25 mesh with the teeth of the orientation engagement part 48a’. The drive part 52’ and idler gears 110 are equally spaced around the circumference of the body 54 to ensure that the orientation engagement assembly 48’ is fully supported around the body 54’. The orientation engagement assembly 48’ includes a plurality of locking parts, which 30 in this embodiment are locking dogs 114. The dog cage 102 includes a plurality of windows 112 which are equally spaced around its circumference, and a locking dog 114 is located in each window. Each locking dog has a radially outwardly facing surface 114a which may be provided with features such as teeth, ridges, or 15 08 25 striations, or may simply have a roughened surface which increase the coefficient of friction between the locking dog 114 and the interior surface 42b of the BOP stack 22. Each locking dog 114 also has a radially inward facing surface 114b which engages with a radially outwardly facing surface of the orientation engagement 5 assembly 48’. For each locking dog 114, the radially outwardly facing surface of the orientation engagement part 48a’ has a camming formation 116 which comprises a recess 116a which is sufficiently large to contain the portion of the locking dog 114, and which has inclined edge portions 116b. These are best illustrated in Figures 8 and 9. io The locking dogs 114 can be placed in a retracted configuration in which each is located in a recess 116a of the orientation engagement part 48a’, as illustrated in Figure 9. 54’. The locking dogs 114 are captured in the windows of the dog cage 102, and therefore, if the orientation engagement part 48a’ is rotated around the body, the locking dogs 114 cannot rotate with the orientation engagement part 48a’. is The inclined edge portions 116b engage with the radially inward facing surfaces 114b of the locking dogs 114, to push the locking dogs 114 radially outwardly of the body 54’ into their engaged configuration as illustrated in Figure 8. It will therefore be appreciated that in this embodiment of orientation control assembly 34’, the actuator system 49’ comprises the motor 50, the drive shaft 56 and the camming 20 formations 116 of the orientation engagement assembly 48’. This embodiment of orientation control assembly 34’ can be operated as follows. As with the embodiment described above, the landing assembly 26 comprising the orientation control assembly 34’ is mounted on an end of the landing string 28 and the landing string 28 is used to run the landing assembly 26 down the riser 38 and 25 into the wellhead assembly 12. During this process, the orientation control assembly 34’ is configured such that the locking dogs 114 are in their retracted configuration. When the tubing hanger 30 lands on the uppermost surface 46 of the landing shoulder 44, the orientation sensor assembly 60 is used to determine the angular 30 orientation of the landing assembly 26 (either its absolute orientation or its orientation relative to the wellhead). This is compared with the desired orientation of the landing assembly 26, and if the landing assembly 26 is not in the desired 15 08 25 orientation, the orientation control assembly 34’ is operated as follows to rotate the tubing hanger 30 to the desired orientation as follows. The motor 50 is operated to rotate the drive part 52’. By virtue of the meshing of the teeth of the drive part 52’ with the teeth of the orientation engagement part 48a’, 5 orientation engagement part 48a’ rotates and the camming formations 116 drive the locking dogs 114 radially outwardly into engagement with the interior surface 42b of the BOP stack 22. Once this occurs, the locking dogs 114 block further rotation of the orientation engagement assembly 48’ relative to the BOP stack 22, and further rotation of the drive part 52 drives rotation of the landing assembly 26 within the io wellhead assembly 12 about the longitudinal axis A of the wellhead assembly 12. Using the signal from the orientation sensor assembly 60, the motor 50 is operated to rotate the landing assembly 26 until it reaches the desired orientation. The orientation engagement assembly 48’ and drive part 52’ are configured such that, when the orientation engagement assembly 48’ is in its engaged configuration is and engaged with the drive part 52’, rotation of the landing assembly 26 relative to the wellhead assembly 12 is prevented in the absence of operation of the motor 50. As such, once the landing assembly 26 is in its desired orientation, the motor 50 is switched off to fix the orientation of the landing assembly 26. This embodiment of orientation control assembly 34’ can also accommodate the 20 provision for a soft landing of the tubing hanger 30 in the wellhead 18. To facilitate this, the spring carrier 109 is spaced from the flange part 100 by a separation L which is either the same as or greater than the travel distance of the landing surface during the soft landing process, and the teeth of the drive part 52’ extend along the entire length of the intermediate portion of the drive shaft 56’ from the uppermost 25 surface of the end stop to the lowermost surface of the flange part 100. A plurality of springs 118 extend between the flange part 100 and the spring carrier 109. In this embodiment, the springs 118 are helical compression springs which are each coiled around a guide pin 120. Each guide pin 120 has a first end 120a which is secured to the spring carrier 103, and a second end 120b which is located adjacent 30 a passage in the flange 100. The springs 118 can therefore be compressed to reduce the space between the spring carrier 103 and the flange part 100, with the second end 120b of each guide pin 120 moving into its associated passage. During this process, the body 54’, drive shaft 56’, and end stop 103 move relative to the orientation engagement assembly 48’, dog cage 102 and locking dogs 114, the 15 08 25 teeth of the orientation engagement part 48a’ sliding along the grooves of the drive part 52’ towards the first end 56a of the drive shaft 56’. As previously described, the system 10 is advantageously operated to use the motor 50 to rotate the landing assembly 26 to its desired orientation when the tubing 5 hanger 30 is in its initial landing position. Once the landing assembly 26 is in its desired orientation, the operation of the motor 50 is stopped, and the lowering of the tubing hanger 30 is continued until it reaches its final landing position. During this process, the engagement of the locking dogs 114 with the interior surface 42b of the BOP stack 42 ensures that the locking dogs 114, the dog cage 102, the orientation io engagement part 48a’ and the spring carrier 109 are fixed relative to the interior surface 42b of the BOP stack 22, with the body 54’, drive shaft 56’ and end stop 103 moving downwards, compressing the springs 118 and reducing the gap between the flange part 100 and the spring carrier 109, the teeth of the orientation engagement part 48a’ sliding along the grooves of the drive part 52’ towards the first end 56a of is the drive shaft 56’ to keep the tubing hanger 30 in the desired orientation. It will be appreciated that, as discussed above, the surface of the orientation engagement assembly 48, 48’ which engages with the interior surface 42 of the wellhead assembly 12 (the radially outwardly facing surface of collet 80 or locking dogs 114) may be provided with features such as teeth, ridges, or striations, or may 20 simply have a roughened surface which increase the coefficient of friction between the orientation engagement assembly 48, 48’ and the interior surface 42 of the wellhead assembly 12. Alternatively, or additionally the relevant portion of the interior surface 42 of the wellhead assembly 12 may be provided with features (which could be integral with or secured to the wellhead assembly 12) which 25 facilitate effective engagement of the orientation engagement assembly 48, 48’ with the interior surface 42 of the wellhead assembly 12, and assist in ensuring that there is rotation of the orientation engagement assembly 48, 48’ relative to the interior surface 42 of the wellhead assembly 12 during operation of the motor 50 to rotate the tubing hanger 30. 30 The invention is not limited by the embodiments described above; reference should be had to the appended claims. 15 08 25
Claims
1. A wellhead system comprising a generally tubular wellhead assembly with a main passage having a longitudinal axis, the wellhead assembly being configured to be secured to the top of a borehole, the wellhead assembly5 having an interior surface which encloses the main passage, the wellheadsystem further comprising a landing assembly comprising a tubing hanger, the landing assembly being configured to be lowered into the main passage of the wellhead assembly to land the tubing hanger in the wellhead assembly, the landing assembly having a longitudinal axis and furtherio comprising an orientation control assembly which comprises an orientationengagement assembly having a segmented sleeve, and an actuator system which is configured to move the orientation engagement assembly between a retracted configuration and an engaged configuration in which the segmented sleeve engages with the interior surface of the wellheadis assembly, the orientation control assembly further comprising a motor and adrive part which is configured to engage with the orientation engagement assembly and, when the orientation engagement assembly is in its engaged configuration, to be driven by the motor and to rotate the tubing hanger relative to the wellhead assembly about the longitudinal axis of the landing20 assembly.
2. A wellhead system according to claim 1 wherein the orientation engagement assembly and drive part are configured, when the orientation engagement assembly is in its engaged configuration and also engaged with the drive part, to prevent rotation of the landing assembly relative to the wellhead25 assembly in the absence of operation of the motor.
3. A wellhead system according to claim 1 or 2 wherein the motor comprises a hydraulic or electric motor.
4. A wellhead system according to any preceding claim wherein the drive part is connected to the motor such that operation of the motor rotates the drive30 part.
5. A wellhead system according to claim 4 wherein operation of the motor rotates the drive part about an axis of rotation which is parallel to the longitudinal axis of the landing assembly.
6. A wellhead system according to claim 4 or 5 wherein the drive part35 comprises a plurality of radially outwardly pointing teeth, and the orientation15 08 25engagement assembly comprises an orientation engagement part with a plurality radially inwardly pointing teeth which are configured to mesh with the teeth of the drive part.
7. A wellhead system according to claim 6 wherein the drive part comprises a5 pinion gear.
8. A wellhead system according to claim 6 or 7 wherein the orientation control assembly comprises a body and the orientation engagement assembly is annular and extends around the circumference of the body.
9. A wellhead system according to any preceding claim wherein the orientation io control assembly comprises a body and the segmented sleeve is movableradially outwardly of the body to engage with the interior surface of the wellhead assembly.
10. A wellhead system according to claim 9 wherein the actuator system is driven by the motor and drive part to move the locking part from its retracted is configuration to its engaged configuration, the drive part rotating the landingassembly about its longitudinal axis once the or each locking part is in its engaged configuration.
11. A wellhead system according to claim 9 wherein the actuator system is moved by the supply of pressurised fluid to the actuator system to move the 20 locking part from the retracted configuration to the engaged configuration.
12. A wellhead system according to any preceding claim wherein the orientation control assembly further comprises an orientation sensor assembly which is configured to measure the orientation of the tubing hanger.
13. A wellhead system according to claim 12 wherein the system further25 comprises a controller which is connected to the motor and configured tocontrol the operation of the motor, and which is connected to the orientation sensor assembly and configured to receive a signal from the orientation sensor assembly indicative of the orientation of the tubing hanger.
14. A wellhead system according to claim 13 wherein the controller is further 30 configured to use the signal from the orientation sensor assembly todetermine whether the orientation of the tubing hanger deviates from a desired orientation, and, if it does, to operate the motor to rotate the tubing hanger about its longitudinal axis to bring the tubing hanger to the desired orientation.15 08 2515. A wellhead system according to any preceding claim wherein the wellhead system further comprises a soft landing device which is operable to allow downward movement of the tubing hanger in the wellhead through a travel distance after initial engagement of the tubing hanger with a landing surface5 provided on the wellhead from an initial landing position to a final position.
16. A wellhead system according to claim 15 wherein the orientation engagement assembly and drive part are configured to remain engaged as the tubing hanger moves from its initial landing position to its final landing position.io 17. A wellhead system according to any preceding claim wherein the drive part comprises a plurality of radially outwardly pointing teeth, and the orientation engagement assembly comprises an orientation engagement part having a plurality of radially inwardly pointing teeth which are configured to mesh with the teeth of the drive part, the teeth of the drive part each comprising ais radially outwardly pointing ridge which extends generally parallel to thelongitudinal axis of the landing assembly.
18. A wellhead system according to claims 15, 16, and 17 wherein the teeth of the drive part each comprise a radially outwardly pointing ridge which extends generally parallel to the longitudinal axis of the landing assembly20 along a distance which is at least as long as the travel distance of the tubinghanger.
19. A wellhead system according to any preceding claim wherein the drive part comprise a plurality of radially outwardly pointing teeth, and the orientation engagement assembly comprises an orientation engagement part having a25 plurality of radially inwardly pointing teeth which are configured to mesh withthe teeth of the drive part, the teeth of the orientation engagement assembly each comprising a radially inwardly pointing ridge which extends generally parallel to the longitudinal axis of the main passage of the wellhead assembly.30 20. A wellhead system according to claims 15, 16 and 19 wherein the teeth ofthe orientation engagement part each comprise a radially inwardly pointing ridge which extends generally parallel to the longitudinal axis of the main passage of the wellhead assembly along a distance which is at least as long as the travel distance of the tubing hanger.15 08 2521. A wellhead system according to any preceding claim the system further comprising a landing string, the landing assembly being mounted on an end of the landing string.
22. A method of operating a wellhead system according to any preceding claim,5 the method comprising the steps of:a) mounting the landing assembly on an end of a landing string,b) lowering the landing assembly into the wellhead assembly,c) operating the actuating system to move the orientation engagement assembly into its engaged configuration with the interior surface of theio wellhead assembly, andd) operating the motor to rotate the tubing hanger to a desired orientation relative to the wellhead assembly.
23. A method according to claim 22 wherein step b comprises lowering the landing assembly into the wellhead assembly to land the tubing hanger on a is landing surface provided on the interior surface of the wellhead assembly.
24. A method according to claim 22 wherein the wellhead system further comprises a soft landing device which is operable to allow downward movement of the tubing hanger in the wellhead through a travel distance after initial engagement of the tubing hanger with a landing surface provided20 on the wellhead from an initial landing position to a final position, and thestep b comprises lowering the landing assembly into the wellhead assembly to land the tubing hanger in the initial landing position on a landing surface provided on the interior surface of the wellhead assembly, and the method further includes, after carrying out step d, lowering the landing assembly25 further into the wellhead so that the tubing hanger moves from its initiallanding position to its final landing position.
25. A method according to claim 24 wherein the orientation engagement assembly is retained in its engaged configuration whilst the tubing hanger is lowered from its initial landing position to its final landing position.