GB2535587A

GB2535587A - Landing string for landing a tubing hanger in a production bore of a wellhead

Info

Publication number: GB2535587A
Application number: GB1521076.8A
Authority: GB
Inventors: Abraham Siby; Olsen Robert
Original assignee: Vetco Gray Scandinavia AS
Current assignee: Vetco Gray Scandinavia AS
Priority date: 2014-12-05
Filing date: 2015-11-30
Publication date: 2016-08-24
Anticipated expiration: 2035-11-30
Also published as: GB2535587B; GB201521076D0; NO20141475A1; NO341605B1

Abstract

A tubing hanger landing string comprising a tubing hanger running tool 90 and a slick joint 40 provided with a production bore 43 connected to a production bore 93 of the running tool. An annulus access port 55 is provided in an outer periphery of the slick joint or in an outer periphery of a part of the landing string located below the slick joint. A remotely controlled valve device 56 is provided in the landing string, the valve device being remotely adjustable between an open position, in which the annulus access port is connected to the annulus bore 95 of the running tool, and a closed position, in which the annulus access port is disconnected from the annulus bore of the running tool.

Description

LANDING STRING FOR LANDING A TUBING HANGER IN A PRODUCTION

BORE OF A WELLHEAD

FIELD OF THE INVENTION AND PRIOR ART

The present invention relates to a landing string according to the preamble of claim 1 for landing a tubing hanger in a production bore of a wellhead.

Offshore oil and gas platforms or vessels typically use a riser to connect a subsea wellhead with the platform or vessel. A blowout preventer is located on the wellhead at the lower end of the riser. A blowout preventer comprises components for many different types of operations, such as for instance a pipe ram which is configured to sealingly engage with the outer surface of a pipe section of a working string or any other tubular object received inside the blowout preventer, and a shear ram which is configured, in case of emergency, to shear a pipe section of a working string or any other tubular object received inside the blowout preventer.

Tubing hangers are installed in wellheads of, for instance, subsea oil and gas wells. A tubing hanger supports the tubing that extends down into the production zone of the well. When a tubing hanger is to be installed in a wellhead, the tubing hanger is positioned on a landing seat in the wellhead by means of a landing string comprising a tubing hanger running tool releasably secured to the tubing hanger. A tubing hanger installed in a subsea wellhead is provided with a production bore and is normally also provided with an annulus bore which may be used for monitoring pressure or communicating fluid to and from the annulus below the tubing hanger during and after the installation of the tubing hanger in the wellhead. A landing string used for handling such a dual bore tubing hanger has a production line which is connected to the production bore of the tubing hanger and an annulus line which is connected to the annulus bore of the tubing hanger. When the tubing hanger has been landed onto the landing seat in the wellhead, the landing string extends through the blowout preventer. In case of emergency, it might be necessary to cut the landing string. However, it might be difficult for the shear ram of a conventional blowout preventer to cut a landing string which has a production line and an annulus line extending in parallel with each other all along the landing string.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a new and advantageous landing string, which in at least some aspect offers an advantage as compared to previously known landing strings.

According to the invention, this object is achieved by a landing string having the features defined in claim 1.

The landing string of the present invention comprises a tubing hanger running tool and a slick joint which is located above the tubing hanger running tool. The tubing hanger running tool comprises: - a production bore configured for connection to a production bore of the tubing hanger; an annulus bore configured for connection to an annulus bore of the tubing hanger; and a gripping device configured for gripping and holding the tubing hanger during the landing of the tubing hanger in the production bore of the wellhead.

The slick joint comprises: a production bore which is connected to the production bore of the tubing hanger running tool; and an outer engagement surface configured for a sealing engagement with a pipe ram of a blowout preventer.

An annulus access port is provided in an outer periphery of the slick joint below said engagement surface or in an outer periphery of a part of the landing string located below the slick joint.

The landing string comprises a remotely controlled valve device which is remotely adjustable between an open position, in which the annulus access port is connected to the annulus bore of the tubing hanger running tool so as to allow fluid communication between the annulus access port and this annulus bore, and a closed position, in which the valve device keeps the annulus access port disconnected from the annulus bore of the tubing hanger running tool and thereby prevents fluid communication between the annulus access port and this annulus bore.

Thus, in the landing string of the present invention, the annulus line is terminated in or below the slick joint and it is thereby possible to introduce a monobore shear section in the landing string above the slick joint at such a position that this shear section will be located at the level of the shear ram of the blowout preventer when a tubing hanger secured to the tubing hanger running tool has been brought into engagement with the dedicated landing seat in the wellhead. Hereby, the shear ram of the blowout preventer only needs to cut a production pipe of the landing string in case of emergency and not also an annulus pipe of the landing string, which will facilitate the cutting operation. Furthermore, the remotely controlled valve device makes it possible to control the access to the annulus line in the tubing hanger running tool and thereby the access to the annulus of the wellhead below the tubing hanger, which is of advantage when it comes to the performance of different operations in connection with the installation of a tubing hanger by means of the landing string, as will be described in closer detail in the detailed description of the invention following below.

By means of the remotely controlled valve device, it will be possible to provide annulus communication to the surface through the blowout preventer while still being able to isolate the blowout preventer from the annulus below the tubing hanger when so needed.

An embodiment of the invention is characterized in: - that the valve device comprises a valve actuator bore extending in the axial direction of the landing string and an elongated valve piston body which is displaceably received in the valve actuator bore and hydraulically actuatable; that the valve actuator bore has an inlet opening at its lower end, this inlet opening being connected to the annulus bore of the tubing hanger running tool; and that the valve piston body is axially displaceable in the valve actuator bore between a first position, in which the annulus access port is connected to the annulus bore of the tubing hanger running tool so as to allow fluid communication between the annulus access port and this annulus bore, and a second position, in which the valve piston body keeps the annulus access port disconnected from the annulus bore of the tubing hanger running tool and thereby prevents fluid communication between the annulus access port and this annulus bore.

Thus, the valve device is open when the valve piston body is in said first position and closed when the valve piston body is in said second position.

According to another embodiment of the invention, a pressure balance channel extends axially through the valve piston body in order to allow fluid communication between the annulus bore of the tubing hanger running tool and a pressure balance chamber provided in the valve actuator bore between an upper end face of the valve actuator bore and an upper end face of the valve piston body. Fluid may flow through the pressure balance channel from the area at the bottom of the valve piston body to the pressure balance chamber at the top of the valve piston body to thereby balance the pressure load on the valve piston body. Thus, there will be no pressure difference between the bottom end and the top end of the valve piston body and the hydraulic pressure required for actuating the valve piston body can thereby be reduced.

According to another embodiment of the invention, a filter is arranged in the valve piston body at the lower end of the pressure balance channel in order to avoid clogging of the pressure balance channel.

Further advantages as well as advantageous features of the landing string of the present invention will appear from the following description and the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, a specific description of preferred embodiments of the invention cited as examples follows below. In the drawings: Fig 1 is a vertical section through a landing string according to an embodiment of the present invention as seen with a tubing hanger secured to the tubing hanger naming tool, Fig 2 is a vertical section through a part of the landing string of Fig 1, Fig 3 is a vertical section through a valve device included in the landing string of Fig 1, as seen with the valve device in an open state, Fig 4 the valve device of Fig 3, as seen in a closed state, Fig 5 a detail enlargement of a part of the valve device of Figs 3 and 4, Fig 6 a lateral view of a blowout preventer with the landing string of Fig 1 positioned inside the blowout preventer and shown in broken lines, and Fig 7 is a vertical section through a part of a landing string according to another embodiment of the invention

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

A landing string 1 according to an embodiment of the present invention for landing a tubing hanger 2 in a wellhead 4 is illustrated in Fig 1 As seen from top to bottom the landing string 1 comprises a monobore centralizer joint 20, a monobore shear joint 30, a monobore slick joint 40, a tubing hanger orientation joint 50 and a tubing hanger running tool 90. The tubing supported by the tubing hanger 2 is not shown in Fig 1.

When in use, the upper end of the centralizer joint 20 is releasably connected to the lowermost pipe section 5 of a working string to thereby allow the landing string 1 to be run down through a riser (not shown), while hanging in the working string, until the landing string 1 has been received in a central bore of a blowout preventer 100 (see Fig 6) arranged on the wellhead 4 at the lower end of the riser and a tubing hanger 2 secured to the tubing hanger running tool 90 has been landed onto a landing seat 7 in the form of an internal shoulder provided in the wellhead 4. At a later moment, when the tubing hanger 2 has been properly installed in the wellhead 4 and released from the tubing hanger running tool 90, the landing string 1 may be lifted upwards by means of the working string.

The centralizer joint 20 is configured to keep the landing string 1 properly centered inside the blowout preventer 100. In the illustrated embodiment, the centralizer joint 20 also acts as the termination point of control lines of the landing string 1 which are connected to corresponding control lines of an umbilical 8 by means of suitable connectors. The lower part of the umbilical 8 is illustrated in Fig 1. The lower end 9 of the umbilical 8 may be secured to the centralizer joint 20, for instance by being hinged to an eye bolt on the centralizer joint. At its upper end, the centralizer joint 20 is provided with a threaded coupling part 21 configured for engagement with a corresponding threaded coupling part 11 provided at the lower end of the above-mentioned pipe section 5. At its lower end, the centralizer joint 20 is provided with a threaded coupling part 22 configured for engagement with a corresponding threaded coupling part 32 provided at the upper end of the shear joint 30. The shear joint 30 is releasably connected to the centralizer joint 20 through the threaded coupling formed by the last-mentioned coupling parts 22, 32. A production bore 23 extends axially through the centralizer joint 20 from the lower end to the upper end thereof, wherein this production bore 23 is aligned with and in fluid communication with an axial bore 12 of the pipe section 5 when the pipe section is connected to the centralizer joint 20.

The shear joint 30 is arranged at such a position in the longitudinal direction of the landing string 1 that the shear joint 30 will be located at the level of the shear ram 101 (see Fig 6) of the blowout preventer 100 when a tubing hanger 2 secured to the tubing hanger running tool 90 has been landed onto the landing seat 7 in the wellhead 4. The shear joint 30 is tubular and has a wall thickness which is selected in dependence on the shearing capacity of the shear ram 101 so as to allow the cutting members of the shear ram 101 to cut through the shear joint 30 in a reliable manner in case of an emergency situation. At its lower end, the shear joint 30 is provided with a threaded coupling part 31 configured for engagement with a corresponding threaded coupling part 41 provided at the upper end of the slick joint 40. The slick joint 40 is releasably connected to the shear joint 30 through the threaded coupling formed by these coupling parts 31, 41. A production bore 33 extends axially through the shear joint 30 from the lower end to the upper end thereof, wherein this production bore 33 is aligned with and in fluid communication with the production bore 23 of the centralizer joint 20.

The slick joint 40 is arranged at such a position in the longitudinal direction of the landing string 1 that the slick joint 40 will be located at the level of a pipe ram 102 (see Fig 6) of the blowout preventer 100 when a tubing hanger 2 secured to the tubing hanger running tool 90 has been landed onto the landing seat 7 in the wellhead 4. The outer diameter of the slick joint 40 is adapted in dependence on the pipe ram requirement in order to allow the pipe ram 102 to sealingly engage with an outer engagement surface 44 of the slick joint 40 in a reliable manner. At its lower end, the slick joint 40 is provided with a threaded coupling part 42 configured for engagement with a corresponding threaded coupling part 52 provided at the upper end of the tubing hanger orientation joint 50. The tubing hanger orientation joint 50 is releasably connected to the slick joint 40 through the threaded coupling formed by these coupling parts 42, 52. A production bore 43 extends through the slick joint 40 from the lower end to the upper end thereof, wherein this production bore 43 is in fluid communication with the production bore 33 of the shear joint 30.

The tubing hanger orientation joint 50 is configured to position the landing string 1 in a correct rotational position inside the blowout preventer 100 when the landing string 1 is lowered downwards within the central bore the blowout preventer to thereby ensure that the tubing hanger 2 has assumed a correct rotational position in relation to the wellhead 4 before it is landed onto the landing seat 7 in the wellhead 4. The tubing hanger orientation joint 50 is in a conventional manner provided with suitable guiding means (not shown) which are configured to co-operate with corresponding guiding means arranged inside the blowout preventer 100. The guiding means of the tubing hanger orientation joint 50 may for instance consist of a double helix cam assembly and a slot or the like, which interact with a guiding member in the form of a pin or the like projecting into the central bore of the blowout preventer 100. When the guiding means of the tubing hanger orientation joint 50 makes contact with the guiding means of the blowout preventer 100 they gradually impose the correct rotational orientation of the landing string 1 as the landing string is lowered downwards through the central bore of the blowout preventer. At its lower end, the tubing hanger orientation joint 50 is provided with a threaded coupling part 51 configured for engagement with a corresponding threaded coupling part 91 provided at the upper end of the tubing hanger running tool 90. The tubing hanger running tool 90 is real easably connected to the tubing hanger orientation joint 50 through the threaded coupling formed by these coupling parts 51, 91. A production bore 53 extends axially through the tubing hanger orientation joint 50 from the lower end to the upper end thereof, wherein this production bore 53 is in fluid communication with the production bore 43 of the slick joint 40.

The tubing hanger running tool 90 is in a conventional manner provided with a gripping device 94 at its lower end configured for gripping and holding the tubing hanger 2 during the running of the tubing hanger 2 down through the riser and the blowout preventer 100 and during the landing of the tubing hanger 2 in the production bore 3 of the wellhead 4. A production bore 93 extends axially through the tubing hanger running tool 90 from the lower end to the upper end thereof, wherein this production bore 93 is aligned with and in fluid communication with the production bore 53 of the tubing hanger orientation joint 50. In the embodiment illustrated in Figs 1-6, the production bore 43 of the slick joint 40 is connected to the production bore 93 of the tubing hanger running tool 90 via the production bore 53 of the tubing hanger orientation joint 50. When the tubing hanger 2 is secured to the tubing hanger running tool 90, the production bore 93 of the tubing hanger running tool 90 is also aligned with and in fluid communication with a production bore 13 of the tubing hanger 2. An annulus bore 95 extends axially through the tubing hanger running tool 90 from the lower end to the upper end thereof in parallel with the production bore 93, wherein this annulus bore 95 is aligned with and in fluid communication with an annulus bore of the tubing hanger 2 when the tubing hanger is secured to the tubing hanger running tool 90.

In the embodiment illustrated in Figs 1-6, an annulus access port 55 is provided in an outer periphery of the tubing hanger orientation joint 50. In the illustrated embodiment, the annulus access port 55 is radially directed. Furthermore, a remotely controlled valve device 56 is provided in the tubing hanger orientation joint 50. In the illustrated embodiment, this valve device 56 is hydraulically operated and comprises a valve housing 57 (see Fig 3), a valve actuator bore 58 arranged in the valve housing 57 and an elongated valve piston body 59, which is displaceably received in the valve actuator bore 58 and hydraulically actuatable. The valve actuator bore 58 extends in the axial direction of the tubing hanger orientation joint 50 in parallel with the production bore 53. The valve actuator bore 58 has an inlet opening 60 at its lower end, wherein this inlet opening 60 is connected to the annulus bore 95 of the tubing hanger running tool 90 through an axial connecting channel 61 provided in the valve housing 57 below the valve actuator bore 58. The valve piston body 59 is axially displaceable in the valve actuator bore 58 between an upper first position (see Fig 3), in which the annulus access port 55 is connected to the annulus bore 95 of the tubing hanger running tool 90 so as to allow fluid communication between the annulus access port 55 and this annulus bore 95, and a lower second position (see Fig 4), in which the valve piston body 59 keeps the annulus access port 55 disconnected from the annulus bore 95 of the tubing hanger running tool 90 and thereby prevents fluid communication between the annulus access port 55 and this annulus bore 95. Thus, the valve device 56 is open when the valve piston body 59 is in said first position and closed when the valve piston body 59 is in said second position. In the illustrated embodiment, the valve piston body 59 comprises a lower piston rod member 62a, an intermediate cylindrical piston member 63 and an upper piston rod member 62b, wherein the piston member 63 has a larger diameter than the lower and upper piston rod members 62a, 62b. The valve actuator bore 58 is divided by said piston member 63 into a lower hydraulic chamber 64a and an upper hydraulic chamber 64b. Each hydraulic chamber 64a, 64b is connected to a hydraulic system (not shown) for feeding pressure medium, preferably in the form of hydraulic oil, to the hydraulic chamber in order to control the displacement of the valve piston body 59 in the valve actuator bore 58. One or more sealing members 65 are provided on the outer periphery of the piston member 63 in order to form a fluid tight seal between the lower hydraulic chamber 64a and the upper hydraulic chamber 64b.

In the illustrated embodiment, the inlet opening 60 of the valve actuator bore 58 is connected to the annulus access port 55 through a connecting chamber 66 provided in the lower part of the valve actuator bore 58 and a radial connecting channel 67 extending between the connecting chamber 66 and the annulus access port 55. When the valve piston body 59 is in the above-mentioned second position, the lower end of the lower piston rod member 62a extends into the connecting chamber 66 and prevents fluid communication between the connecting chamber 66 and the radial connecting channel 67, as illustrated in Fig 4. When the valve piston body 59 is moved from the second position to the first position, the lower end of the lower piston rod member 62a is moved out of the connecting chamber 66 to thereby put the connecting chamber in fluid communication with the radial connecting channel 67, as illustrated in Fig 3.

In the illustrated embodiment, the valve piston body 59 is biased towards the second position by a spring member 68, wherein the valve piston body 59, against the action of the spring force from the spring member 68, is hydraulically displaceable from the second position to the first position by a hydraulic actuation force applied against a lower shoulder 69a on the piston member 63. Thus, the spring force exerted by the spring member 68 urges the valve piston body 59 back towards the second position when this hydraulic actuation force is no longer applied. In the illustrated example, the spring member 68 is a helical spring which is arranged in the upper hydraulic chamber 64b around the upper piston rod member 62b and clamped between an upper shoulder 69b on the piston member 63 and an opposite shoulder 70 at an upper part of the upper hydraulic chamber 64b.

A pressure balance channel 71 extends axially through the valve piston body 59 from the lower end to the upper end thereof in order to allow fluid communication between the annulus bore 95 of the tubing hanger running tool 90 and a pressure balance chamber 72 (see Fig 4) provided in the valve actuator bore 58 between an upper end face 73 of the valve actuator bore 58 and an upper end face 74 of the valve piston body 59. Hereby, the pressure acting on the lower end face of the valve piston body 59 will be the same as the pressure acting on the upper end face 74 of the valve piston body 59.

A filter 75 is arranged in the valve piston body 59 at the lower end of the pressure balance channel 71 in order to avoid clogging of the pressure balance channel. In the illustrated embodiment, the filter 75 is mounted in a through hole 76 (see Fig 5) of a holder 77 which has a shaft part 78 provided with an external thread 79 configured for engagement with an internal thread 80 provided in a widened end section 81 at the lower end of the pressure balance channel 71. The holder 77 also has a head part 82 which is fixed to the shaft part 78, a shoulder 83a being provided on the head part 82 on the side thereof facing the shaft part 78. The holder 77 also functions as a retaining member for a seal housing 84 mounted to the lower piston rod member 62a at the lower end thereof. The holder 77 extends through an axial through hole 85 in the seal housing 84 and the shoulder 83a on the head part 82 abuts against a corresponding shoulder 83b in the through hole 85 to thereby clamp the seal housing 84 to the lower piston rod member 62a. In the illustrated example, a sealing member 86 is arranged in a recess 87 between the seal housing 84 and the lower piston rod member 62a in order to form a fluid tight seal between the connecting chamber 66 and the radial connecting channel 67 when the valve piston body 59 is in the above-mentioned second position.

One or more sealing members 88b (see Fig 4) are provided on the outer periphery of the upper piston rod member 62b at the upper end thereof in order to form a fluid tight seal between the pressure balance chamber 72 and the upper hydraulic chamber 64b.

One or more sealing members 88a are also provided on the outer periphery of the lower piston rod member 62a in order to form a fluid tight seal between the lower hydraulic chamber 64a and the radial connecting channel 67 when the valve piston body 59 is in the above-mentioned second position.

A flushing line 89 is provided at the upper part of the valve housing 57. If the pressure balance channel 71 is clogged, flushing fluid may be fed through the flushing line 89, into the pressure balance chamber 72 and further down through the pressure balance channel 71 in order to remove debris from the pressure balance channel. Such a flushing operation may be performed when the tubing hanger orientation joint 50 is in a workshop or on the oil and gas platform. The valve housing 57 may also be provided with flushing lines (not shown), through which flushing fluid may be fed into the upper hydraulic chamber 64b and/or lower hydraulic chamber 64a in order to remove debris therefrom.

In the embodiment illustrated in Fig 7, the slick joint 40 is located between the tubing hanger running tool 90 and the tubing hanger orientation joint 50. In this embodiment, the production bore 43 of the slick joint 40 is connected directly to the production bore 93 of the tubing hanger running tool 90 and the annulus access port 55 is provided in an outer periphery of the slick joint 40 below the above-mentioned engagement surface 44. The landing string I illustrated in Fig 7 comprises a valve device 56 of the type described above. In this case, the valve actuator bore 58 has an lower part 58a located in the slick joint 40 and an upper part 58b located in the tubing hanger orientation joint 50. Furthermore, the lower piston rod member 62a of the valve piston body 59 included in the valve device 56 of the landing string illustrated in Fig 7 is longer than the lower piston rod member 62a of the valve piston body 59 included in the valve device 56 of the landing string illustrated in Fig 1-6. As to the rest, the valve device 56 of the landing string illustrated in Fig 7 corresponds to the valve device described above with reference to Figs 1-6.

As an alternative to the type of valve device 56 illustrated in Figs 1-4 and 7, the landing string 1 could be provided with a valve device in the form of a hydraulically actuated ball valve, gate valve or needle valve for controlling the fluid communication between the annulus access port 55 and the annulus bore 95 of the tubing hanger running tool 90.

The gripping device 94 of the tubing hanger running tool 90 normally comprises hydraulically actuated gripping members which are maintained in a locked position in engagement with the tubing hanger 2 during the landing of the tubing hanger onto the landing seat 7 in the wellhead 4. After the landing of the tubing hanger 2 onto the landing seat 7, the gripping members are to be unlocked in order to allow the tubing hanger running tool 90 to be released from the tubing hanger. If the primary unlocking operation fails due to hydraulic line failure, a secondary unlocking operation may be executed in order to unlock the gripping members of the gripping device 94. In the latter case, the pipe ram 102 is made to seal against the slick joint 40, whereupon pressure is applied in the central bore of the blowout preventer 100, below the pipe ram 102, through the choke and kill lines (not shown) of the blowout preventer in order to generate a pressure capable of unlocking the gripping members of the gripping device 94. In order to prevent production tubing, casing and other equipment installed in the wellhead below the tubing hanger from being damaged by the high pressure applied on the outside of the tubing hanger running tool 90 during the secondary unlocking operation, the access to the annulus below the tubing hanger 2 is blocked by making the valve device 56 assume its closed position.

Furthermore, a tubing hanger seal test may be carried out when the pipe ram 102 seals against the engagement surface 44 of the slick joint 40. In a first step, the valve device 56 is made to assume its open position and pressure is applied in the central bore of the blowout preventer 100, below the pipe ram 102, through the choke and kill lines of the blowout preventer in order to pressurize both sides of the tubing hanger seal with the same seal testing pressure. In a subsequent second step, the valve device 56 is made to assume its closed position in order to isolate the area above the tubing hanger seal from the area below the tubing hanger seal and thereby make it possible to test the seal leakage from above and below the tubing hanger seal separately.

In the illustrated embodiments, the different parts 20, 30, 40, 50, 90 of the landing string 1 are connected to each other by means of threaded couplings. However, these parts 20, 30, 40, 50, 90 may be connected to each other in any other suitable manner, such as by flange joints.

The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.

Claims

CLAIMS: 1. A landing string for landing a tubing hanger (2) in a production bore (3) of a wellhead (4), the landing string (1) comprising a tubing hanger running tool (90) and a slick joint (40) which is located above the tubing hanger running tool (90) and which is provided with an outer engagement surface (44) configured for a sealing engagement with a pipe ram (102) of a blowout preventer (100), wherein the tubing hanger running tool (90) is provided with: a production bore (93) configured for connection to a production bore (13) of the tubing hanger (2); an annulus bore (95) configured for connection to an annulus bore (15) of the tubing hanger (2); and a gripping device (94) configured for gripping and holding the tubing hanger (2) during the landing of the tubing hanger in the production bore (3) of the wellhead (4), and wherein the slick joint (40) is provided with a production bore (43) which is connected to the production bore (93) of the tubing hanger running tool (90), characterized in: that an annulus access port (55) is provided in an outer periphery of the slick joint (40) below said engagement surface (44) or in an outer periphery of a part of the landing string (1) located below the slick joint (40); and that the landing string (1) comprises a remotely controlled valve device (56) which is remotely adjustable between an open position, in which the annulus access port (55) is connected to the annulus bore (95) of the tubing hanger running tool (90) so as to allow fluid communication between the annulus access port (55) and this annulus bore (95), and a closed position, in which the valve device (56) keeps the annulus access port (55) disconnected from the annulus bore (95) of the tubing hanger running tool (90) and thereby prevents fluid communication between the annulus access port (55) and this annulus bore (95).
A landing string according to claim 1, characterized in: that the valve device (56) comprises a valve actuator bore (58) extending in the axial direction of the landing string (1) and an elongated valve piston body (59) which is di splaceably received in the valve actuator bore (58) and hydraulically actuatable; that the valve actuator bore (58) has an inlet opening (60) at its lower end, this inlet opening (60) being connected to the annulus bore (95) of the tubing hanger running tool (90); and that the valve piston body (59) is axially displaceable in the valve actuator bore (58) between a first position, in which the annulus access port (55) is connected to the annulus bore (95) of the tubing hanger running tool (90) so as to allow fluid communication between the annulus access port (55) and this annulus bore (95), and a second position, in which the valve piston body (59) keeps the annulus access port (55) disconnected from the annulus bore (95) of the tubing hanger running tool (90) and thereby prevents fluid communication between the annulus access port (55) and this annulus bore (95).
3. A landing string according to claim 2, characterized in that a pressure balance channel (71) extends axially through the valve piston body (59) in order to allow fluid communication between the annulus bore (95) of the tubing hanger running tool (90) and a pressure balance chamber (72) provided in the valve actuator bore (58) between an upper end face (73) of the valve actuator bore (58) and an upper end face (74) of the valve piston body (59).
4. A landing string according to claim 3, characterized in that a filter (75) is arranged in the valve piston body (59) at the lower end of the pressure balance channel (71) in order to avoid clogging of the pressure balance channel.
A landing string according to any of claims 2-4, characterized in: that the valve piston body (59) is biased towards the second position by a spring member (68); and that the valve piston body (59), against the action of the spring force from said spring member (68), is hydraulically displaceable from the second position to the first position.
6. A landing string according to any of claims 1-5, characterized in that the landing string (1) comprises a monobore shear joint (30) which is located in the landing string (1) in a position above the slick joint (40).
A landing string according to any of claims 1-6, characterized in: that the landing string (1) comprises a tubing hanger orientation joint (50) which is located between the tubing hanger running tool (90) and the slick joint (40), wherein the tubing hanger orientation joint (50) is provided with a production bore (53) which is connected to the production bore (93) of the tubing hanger running tool (90) and to the production bore (43) of the slick joint (40); and that the annulus access port (55) and the valve device (56) are provided in the tubing hanger orientation joint (50).
8. A landing string according to claim 7, characterized in that the slick joint (40) is a monobore slick joint.
A landing string according to claim 7 or 8, characterized in: that the production bore (53) of the tubing hanger orientation joint (50) extends axially through the tubing hanger orientation joint (50); and that the valve actuator bore (58) extends in parallel with the production bore (53) of the tubing hanger orientation joint (50).
10. A landing string according to any of claims 7-9, characterized in that the tubing hanger running tool (90) is releasably connected to the tubing hanger orientation joint (50) through a coupling (51, 91) comprising: a first coupling part (91) which is provided at the upper end of the tubing hanger running tool (90); and a second coupling part (51) which is provided at the lower end of the tubing hanger orientation joint (50) and configured for engagement with the first coupling part (91).
11. A landing string according to any of claims 1-10, characterized in that the production bore (93) of the tubing hanger running tool (90) extends axially through the tubing hanger running tool (90); and that the annulus bore (95) of the tubing hanger running tool (90) extends axially through the tubing hanger running tool (90) in parallel with the production bore (93) of the tubing hanger running tool.
12. A landing string according to any of claims 1-11, characterized in that the annulus access port (55) is radially directed.