Key information

Title: TOOL FOR THE RECOVERY OF A CASING HANGER FROM A WELLHEAD
Application number: 20251493
Case type: PCT-based
Status: 30.11.2025 Formaliakontroll utført
Filed: 30.11.2025
Priority: 30.05.2023 GB 2308040.1
International application date: 30.05.2024
International application number: PCT/NO2024/050125
Effective date: 30.05.2024
Publicly available: 30.11.2025
Next annual fee due: 31.05.2027
Applicant: OneSubsea AS (NO)
Inventor: Dmitri Volkov (NO) et al.
Agent: BRYN AARFLOT AS (NO)

Abstract and drawing

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.

A tool for recovering a casing hanger from a wellhead, the tool comprising a tool body having a longitudinal axis, a pressure operated locking assembly, a pressure operated latch assembly which are configured to move in response to the supply of fluid to the tool, a retainer which is configured to prevent movement of either the locking assembly or the latch assembly until the pressure of the fluid supplied to the tool reaches a pre-determined level The tool may include a cutting apparatus which is configured to be inserted into a main passage of a tubular having a longitudinal axis and which is operable to cut through the tubular in a plane generally perpendicular to the longitudinal axis thereof.

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Date

Date	Doc. No.	Process	Case number	In/Out	Journal description	To/from
02.04.2026	05-01	Saksbehandling	20251493	UT	PT Varsel om betaling av første årsavgift (3317) (PT20251493)	BRYN AARFLOT AS
05.03.2026	04-02	Saksbehandling	20251493	INN	Power of Attorney	BRYN AARFLOT AS
05.03.2026	04-01	Saksbehandling	20251493	INN	Korrespondanse (Hovedbrev inn)	BRYN AARFLOT AS
29.01.2026	03-02	Saksbehandling	20251493	INN	Assignment	BRYN AARFLOT AS
29.01.2026	03-01	Saksbehandling	20251493	INN	Korrespondanse (Hovedbrev inn)	BRYN AARFLOT AS
02.01.2026	02-01	Saksbehandling	20251493	UT	Formal Examination 1	BRYN AARFLOT AS
02.01.2026	02-01	Saksbehandling	20251493	INN	Initial Publication with ISR (A1 09/2017)
30.11.2025	01-02	Saksbehandling	20251493	INN	Publication	BRYN AARFLOT AS
30.11.2025	01-01	Saksbehandling	20251493	INN	Søknadsskjema Patent	BRYN AARFLOT AS

Description, claims and drawings

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.

Description

Tool for the Recovery of a Casing Hanger from a Wellhead

The present invention relates to a tool for use in decommissioning a wellhead, in particular to a tool for the recovery of a casing hanger from a wellhead.

BACKGROUND

When decommissioning an offshore wellbore, for example because the wellbore has reached the end of its production life, it is necessary to remove all the wellhead components at the seabed and all the casings to a specified depth below the ocean floor before the wellbore can be plugged. As part of this process, it is known to run a pack-off recovery tool into the wellbore and to operate the tool to unlock the packoff, and then to pull the tool to recover the pack-off. Typically, a casing cutting tool is then run into the wellbore and operated to cut the casing at the required depth. The cutting tool is then retrieved and a casing hanger recovery tool is run into the wellbore, and engaged with the casing hanger from which the casing is suspended. The casing hanger recovery tool, together with the casing hanger and the top section of casing, may then be pulled from the wellbore.

It is an object of the present invention to provide a tool which may be improve the process of the recovery of a casing hanger and associated pack-off and casing from a wellbore.

SUMMARY

According to a first aspect of the disclosed technology we provide a tool for recovering a casing hanger from a wellhead, the tool comprising a tool body having a longitudinal axis, a pressure operated locking assembly and a pressure operated latch assembly which are configured to move in response to the supply of fluid to the tool, and a retainer which is configured to prevent movement of either the locking assembly or the latch assembly until the pressure of the fluid supplied to the tool reaches a pre-determined level.

The retainer is engageable with the locking assembly or the latch assembly accordingly, to prevent movement of either the locking assembly or the latch assembly by engagement until the pressure of the fluid supplied to the tool reaches a pre-determined level (causing release of the locking assembly or the latch assembly, respectively).

The tool may comprise a latch retainer which engages with the latch assembly to prevent movement of the latch assembly until the pressure of the fluid supplied to the tool exceeds a predetermined level.

The tool may comprise a lock retainer which engages with the locking assembly to prevent movement of the locking assembly until the pressure of the fluid supplied to the tool exceeds a first predetermined level and a latch retainer which engages with the latch assembly to prevent movement of the latch assembly until the pressure of the fluid supplied to the tool exceeds a second predetermined level which is higher than the first predetermined level.

In other words, one or both of the locking assembly and the latch assembly may be retained until the pressure of the fluid supplied to the tool exceeds a predetermined level that causes the retainer(s) to release of the or each assembly. It is envisioned that only one of the locking assembly or the latch assembly may need to be retained such that each of the locking assembly and latch assembly can be allowed to move at different predetermined pressure levels. However, both may be retained. In that case, each retainer may be caused to release its respective assembly at a different predetermined pressure level. In this way, movement of the locking assembly and the latch assembly may be staggered in time.

The latch assembly may comprise a latch and a pressure actuated latch actuator, the latch being movable relative to the tool body by movement of the latch actuator in response to the supply of fluid to the tool. In this case, the latch retainer may engage with the latch actuator to prevent movement of the latch actuator relative to the tool body until the pressure of the fluid supplied to the tool exceeds a predetermined level.

The latch may be configured to move radially outwardly relative to the tool body from a contracted configuration to an expanded configuration.

The latch may be arranged on a radially outwardly facing surface of the tool.

The latch may comprise a split ring.

The latch actuator may comprise a sleeve which is mounted around the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis of the tool body in response to the supply of fluid to the tool.

The latch may be mounted on a radially outwardly facing surface of the latch actuator.

The pressure actuated locking assembly may comprise at least one locking element and a pressure actuated locking actuator, the locking element engaging with the locking actuator and being movable relative to the tool body by movement of the locking actuator in response to the supply of pressurised fluid to the tool.

The lock retainer may engage with the locking actuator to prevent movement of the locking actuator relative to the tool body until the pressure of the fluid supplied to the tool exceeds a predetermined level.

The pressure actuated locking assembly may comprise a plurality of locking elements, each and a pressure actuated locking actuator, the locking elements engaging with the locking actuator and being movable relative to the tool body by movement of the locking actuator in response to the supply of fluid to the tool.

The or each locking element may be movable radially outwardly of the tool body by the locking actuator in response to the supply of fluid to the tool.

The locking elements may be arranged around a radially outward facing surface of the tool.

The or each locking element may comprise a locking dog, or a snap ring.

The locking actuator may comprise a sleeve which is mounted around the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis of the tool body in response to the supply of fluid to the tool.

The pressure operated locking assembly and pressure operated latch assembly may be configured to move in response to the supply of fluid to a common pressure supply port.

The tool may comprise a pressure supply port in a radially outward facing surface of the tool, the pressure operated locking assembly moving in response to the supply of pressurised fluid to the pressure supply port.

The tool may comprise a pressure supply port in a radially outward facing surface of the tool, the pressure operated latch assembly moving in response to the supply of pressurised fluid to the pressure supply port.

The lock actuator and latch actuator may each comprise a sleeve which is mounted on the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis thereof in response to the supply of fluid to an actuation chamber formed between the lock actuator, the latch actuator and the tool body, such movement of the lock actuator and latch actuator moving the lock element and latch respectively. In this case, the tool may be provided with a supply pressure port which extends from the radially outwardly facing surface of the tool into the actuation chamber.

The tool may further comprise a cutting apparatus which is configured to be inserted into a main passage of a tubular having a longitudinal axis and which operable to through the tubular in a plane generally perpendicular to the longitudinal axis thereof.

According to a second aspect of the disclosed technology we provide a tool for removing a casing hanger from a wellhead having a tool body having a longitudinal axis, a pressure operated locking assembly, and a pressure operated latch assembly which are configured to move in response to the supply of fluid to the tool, and a cutting apparatus which is configured to be inserted into a main passage of a tubular having a longitudinal axis and which is operable to cut through the tubular in a plane generally perpendicular to the longitudinal axis thereof.

The tool body may enclose a main passage, the cutting apparatus be configured to cut by the supply of fluid to either the main passage or the space surrounding the tool and the locking assembly and latch assembly move in response to the supply of pressurised fluid to the other of the main passage or the space surrounding the tool.

The pressure operated locking assembly and pressure operated latch assembly may move in response to the supply of pressurised fluid to a common pressure supply port.

The lock actuator and latch actuator each comprise a sleeve which is mounted on the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis thereof in response to the supply of fluid to an actuation chamber formed between the lock actuator, the latch actuator and the tool body, such movement of the lock actuator and latch actuator moving the lock element and latch respectively.

According to a third aspect of the disclosed technology we provide a casing hanger recovery assembly comprising a landing string and a tool according to the first or second aspect of the invention mounted on an end of the landing string.

According to a fourth aspect of the disclosed technology we provide a method of removing a casing hanger and casing suspended from the casing hanger from a wellhead using a casing hanger recovery assembly according to the third aspect of the invention comprising:

a) running the landing string into the wellhead so that the tool is landed in the casing hanger,

b) supplying fluid to the wellhead to move the pressure operated locking assembly to lock the tool to the casing hanger,

c) supplying fluid to the wellhead to move the pressure operated latch assembly to disengage a pack-off from the wellhead.

d) pulling the landing string to lift the pack-off, casing hanger and top portion of casing from the wellhead.

The tool may comprise a cutting apparatus, and the method include operating the cutting apparatus to cut the casing in a plane generally perpendicular to the longitudinal axis thereof.

The tool body may enclose a main passage, and the method comprise supplying fluid to either the main passage or the annular between the tool and the wellhead to operate the cutting apparatus and supplying fluid to the other of the main passage or the annulus between the tool and the wellhead to move the locking assembly and the latch assembly.

The tool may further comprise a cutting apparatus which is operable by the supply of pressurised fluid to a different portion of the tool than that which receives the pressurised fluid for operating the locking assembly and the latch assembly.

Steps b and c may be carried out without lifting the tool out of the wellhead.

Steps b and c may be carried out using the supply of pressurised fluid to same part of the tool. Where provided, the cutting apparatus may be pressure operated, and operation of the cutting tool may be carried out by the supply of pressurised fluid to a different part of the tool to the supply of pressurised fluid in steps b and c.

Steps c and d may involve supplying pressurised fluid to an annulus around the tool between the tool and the wellhead.

The tool may have a tool body enclosing a main passage, and the cutting tool may be operated by the supply of pressurised fluid to the main passage.

BRIEF DESCRIPTION OF THE DRAWINGS

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 longitudinal cross-section through an embodiment of casing hanger recovery assembly including a casing hanger recovery tool according to the invention,

FIGURE 2 is a longitudinal cross-section through the portion of the casing hanger recovery assembly labelled X in Figure 1, showing more detail of the casing hanger recovery tool,

FIGURE 3 is a longitudinal cross-section through a wellhead assembly with the casing hanger recovery assembly illustrated in Figure 1 landed in the wellhead assembly, the casing hanger recovery tool of the casing hanger recovery assembly being in a first configuration,

FIGURE 3a is an enlarged portion of the longitudinal cross-section illustrated in Figure 3,

FIGURE 4 is an enlarged portion of the longitudinal cross-section through a wellhead assembly with the casing hanger recovery assembly illustrated in Figure 1 landed in the wellhead assembly, the casing hanger recovery tool of the casing hanger recovery assembly being in a second configuration, and

FIGURE 5 is an enlarged portion of the longitudinal cross-section through a wellhead assembly with the casing hanger recovery assembly illustrated in Figure 1 landed in the wellhead assembly, the casing hanger recovery tool of the casing hanger recovery assembly being in a third configuration.

DETAILED DESCRIPTION

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 used for the reader’s convenience only and shall not be limiting.

Referring now to Figures 1 and 2 there is shown a tool 10 for recovering a casing hanger from a wellhead, the tool 10 comprising a tool body 12 having a longitudinal axis A, a pressure operated locking assembly 14 and a pressure operated latch assembly 16 which are configured to move in response to the supply of pressurised fluid to the tool 10. In particular, in this embodiment, the pressure operated locking assembly 14 is configured to move in response to the supply to the tool 10 of pressurised fluid at first pressure, and the pressure operated latch assembly 16 is configured to move in response to the supply to the tool 10 of pressurised fluid at a second pressure, the second pressure being higher than the first pressure.

In this embodiment, the tool body 12 is tubular, and encloses a main passage 13 which extends parallel to the longitudinal axis A from a first end 12a to a second end 12b of the tool body 12.

The locking assembly 12 comprises a plurality of locking elements 18 and a pressure actuated locking actuator 20, the locking elements 18 engaging with the locking actuator 20 and being movable relative to the tool body 12 by movement of the locking actuator 20 in response to the supply of pressurised fluid to the tool 10. The locking elements 18 are arranged around a radially outward facing surface of the tool 10, each the locking element 18 engaging with the locking actuator and being movable radially outwardly of the tool body 12 by the locking actuator 20 in response to the supply of pressurised fluid to the tool. The locking elements are movable from a retracted position radially outwardly of the tool body 12 into an extended position.

A radially outwardly facing face of each locking element is provided with a plurality of locking formations 22 (in this embodiment, a plurality of generally parallel ridges which extend generally perpendicular to the longitudinal axis of the tool 10).

Specifically, in this embodiment, each locking element 18 comprises a locking dog which is mounted in a dog cage 24 which is arranged around the tool body 12 supported by a dog cage support 26 which extends from the tool body 12. In this embodiment, the dog cage support 26 is secured to the tool body 12 adjacent the second end 12b thereof by a screw thread.

It should be appreciated that the locking elements 18 need not comprise locking dogs. The locking assembly 12 could, for example, comprise a single locking element in the form of a split ring, i.e. a thin ring with a radial split which can be expanded an increased diameter configuration by the application of a radially outward force, and which, when released, contracts to a decreased diameter configuration.

The locking actuator 20 is configured so that a surface of the locking actuator 20 (in this embodiment, a radially outwardly facing surface) engages with the locking elements 18 and acts a wedging surface, movement of the locking actuator 20 in a first direction (in this embodiment towards the second end 12b of the tool body 12) causing the locking elements 18 to move in a generally perpendicular direction.

In particular, in this embodiment, the locking actuator 20 comprises a piston in the form of a sleeve which is mounted around the tool body 12 and which is movable relative to the tool body 12 generally parallel to the longitudinal axis A of the tool body 12 in response to the supply of pressurised fluid to the tool 10. The locking actuator 20 has a first portion 20a with a first outer diameter, and a second portion 20b with a second outer diameter, the second outer diameter being greater than the first, and a transitional portion 20c which is between the first and second portions 20a, 20b, over which the outer diameter increases, in this embodiment generally linearly. The first portion 20a is closest to the first end 12a of the tool body 12, and the second portion 20b is closest to the second end 12b of the tool body 12.

In this embodiment, the locking actuator 20 has a substantially constant internal diameter along its entire length, and its thickness, and therefore the outer diameter, varies along its length. As such, the entire radially inward facing surface of the locking actuator 20 engages with the radially outwardly facing surface of the tool body 12. This need not be the case, however, and internal diameter of the locking actuator 20 may vary along its length. For example, the locking actuator 20 may have an intermediate portion with an increased internal diameter to reduce the area of the locking actuator 20 which is in contact with the tool body 12.

The locking dog cage 24 and locking dogs 18 are mounted around the locking actuator 20, so that when the locking actuator 20 is in a first position (in this embodiment an uppermost position in which it is closer to the first end 12a of the tool body 12) relative to the tool body 12, radially inwardly facing surfaces of the locking dogs 18 engage with the first portion 20a of the locking actuator 20. The locking dogs 18 are thus in their retracted position. If the locking actuator 20 is moved along the tool body 12 in towards the second end 12b of the tool body 12, the intermediate portion 20c of the lock actuator 20 bears on the radially inward facing surface of the locking dogs 18 and pushes the locking dogs 18 radially outwardly, until the second portion 20b of the lock actuator 20 comes into engagement with the locking dogs 18 and they reach a fully extended position.

It should be appreciated that if the tool 10 were to comprise a snap/retainer ring as the locking element, the snap ring would be engaged with the first portion 20a of the locking actuator when in its contracted configuration and expand with relative axial movement of the locking actuator 20 as it engages with the intermediate portion 20c, until it reaches its expanded configuration when engaged with the second portion 20b.

Similarly, the latch assembly 16 comprises a latch 28 and a pressure actuated latch actuator 30, the latch 28 being movable relative to the tool body 10 by movement of the latch actuator 30 in response to the supply of pressurised fluid to the tool 10.

In this example, the latch actuator 30 comprise a piston in the form of a sleeve which is mounted around the tool body 12 and which is movable relative to the tool body 12 generally parallel to the longitudinal axis A of the tool body 12 in response to the supply of pressurised fluid to the tool 10. The latch 28 is mounted in a radially outwardly facing surface of the latch actuator 30, and, and is movable radially outwardly relative to the tool body 12 from a contracted configuration to an expanded configuration. In this particular embodiment the latch 28 is a snap ring, i.e. a thin ring with a radial split which can be compressed to a reduced diameter configuration which, when released, expands to an increased diameter configuration.

An actuation chamber is formed between the lock actuator 20, the latch actuator 30 and the tool body 12, such that the supply of pressurised fluid to the actuation chamber 32 can move the lock actuator 20 and the latch actuator 30 relative to the tool body 12. The tool 10 is provided with a pressure supply port 34 which provides a means for the supply of pressurised fluid into the actuation chamber. It should be appreciated, therefore, that by virtue of this arrangement, movement of the latch actuator 30 and the lock actuator 20 relative to the tool body 12 is achieved by the supply of pressurised fluid to the same actuation chamber via a common pressure supply port 34.

In this case, the tool 10 is provided with a plurality of pressure supply ports 34 which extend from the radially outwardly facing surface of the tool 10 into the actuation chamber 32. One such pressure supply port could be provided, however. In either case, it should be appreciated that in this embodiment, that by virtue of this arrangement of pressure supply port 34 and actuation chamber, movement of the latch actuator 30 and the lock actuator 20 relative to the tool body 12 is achieved by the supply of pressurised fluid to the annular volume which surrounds the tool 10.

In this embodiment, the tool body 12 has a latch actuator support portion 12c which is adjacent the first end 12a of the tool body, and which has a larger outer diameter than the remainder of the tool body 12. The latch actuator 30a has a first end 30a which engages with the radially outwardly facing surface of the latch actuator support portion 12c of the tool body 12, and a second end 30b which extends around and engages with the second portion 20b of the lock actuator 20.

Seals 36 are provided between the first end 30a of the latch actuator 30 and the latch actuator support portion 12c of the tool body 12, and between the second end 30b of the latch actuator 30 and the second portion 20b of the lock actuator 20. These seals 36 are configured to provide a substantially fluid tight seal between the two parts, whilst allowing one part to slide relative to the other. In this embodiment, the seals 36 are mounted in grooves provided in the radially outwardly facing surface of the latch actuator support portion 12c of the tool body 12 and the second portion 20b of the lock actuator 20. The seals 36 may, for example comprise lip seals, T-seals or O-rings or any other type of seal design.

There is an annular space between the tool body 12 and the radially inwardly facing surface of the latch actuator 30 which is bounded at its ends by second end portion 20b of the lock actuator 20 and the latch actuator support portion 12c of the tool body 12. This annular space is divided into two separate chambers 38a, 38b by a divider portion 30c of the latch actuator 30, the divider portion 30c comprising a portion of the latch actuator 30 which lies between the first and the second ends 30a, 30b and which has a smaller internal diameter than the remainder of the latch actuator 30. The first chamber 38a is located between the second end portion 20b of the lock actuator 20 and the divider portion 30c, and the second chamber 38b is located between the latch actuator support portion 12c of the tool body 12 and the divider portion 30c. The first chamber 38a forms the actuation chamber. The pressure supply ports 34 extend through the latch actuator 30 to provide a fluid flow path into the actuation chamber 38a via from the radially outward facing surface of the tool 10.

Seals 40 are provided between the divider portion 30c of the latch actuator 30 and the tool body 12 to provide a substantially fluid tight seal between the latch actuator 30 and the tool body 12 whilst allowing the latch actuator 30 to slide along the tool body 12. In this embodiment, the seals 40 are mounted in grooves provided in the radially inwardly facing surface of the divider portion 30c. The seals 40 may, for example, comprise lip seals, T-seals or O-rings or any other seal design.

The relative volume of the two chambers 38a, 38b may therefore be changed by movement of the latch actuator 30 relative to the tool body 12, the volume of one chamber 38a increasing as the volume of the other increases 38b and vice versa. The volume of the first chamber 38a (hereinafter referred to as the actuation chamber 38a) may also be varied by movement of the lock actuator 20 relative to the tool body 12.

As mentioned above, the locking assembly 14 is configured to move in response to the supply to the tool 10 of pressurised fluid at first pressure, and the pressure operated latch assembly 16 is configured to move in response to the supply to the tool 10 of pressurised fluid at a second pressure, the second pressure being higher than the first pressure. In this embodiment, this is achieved by the provision of a latch retainer which engages with the latch actuator 30 to prevent movement of the latch actuator 30 relative to the tool body 12 until the pressure in the actuation chamber 38a exceeds a predetermined level.

The latch retainer is configured to engage the latch assembly 16 until the pressure of the fluid supplied to the tool 10 reaches a predetermined level. In this way, the latch retainer engaging the latch assembly 16 prevents movement of the latch assembly 30 until the predetermined pressure level is reached.

In this embodiment, the latch retainer comprises a plurality of pins 44 which are each mounted in an aperture in the latch actuator 30 (in this embodiment in the first end 30a of the latch actuator 30) and pushed radially inwardly relative to the latch actuator 30 into engagement with a corresponding retainer formation 48 (in this embodiment a groove or aperture) provided on the radially outward surface of the tool body 12 (in this embodiment, the latch actuator support portion 12c of the tool body 12) by a spring 46. Each pin 44 has an inclined cam surface which ensures that a force on the latch actuator 30 generally parallel to the longitudinal axis A pushing the latch actuator 30 towards the first end 12a of the tool body 12 results in a force on each retainer pin 44 which has a component acting to push the retainer pin 44 radially outwardly against the biasing force of the spring 46. The latch retainer thus ensures that the latch actuator 30 can only move when the pressure in the actuation chamber 38a is sufficiently high that the force on the latch actuator 30 is sufficient to overcome the biasing force of the springs 46 to push the pins 44 radially outwardly out of their corresponding retainer formation 48.

Although not essential, in this embodiment, the tool 10 further comprises a lock retainer which engages with the lock actuator 20 to prevent movement of the lock actuator 20 relative to the tool body 12 until the pressure of the pressurised fluid in the actuation chamber 38a exceeds a predetermined level which is lower than the predetermined pressure level at which the latch actuator 30 can move.

The retainer is configured to engage the locking assembly 14 until the pressure of the fluid supplied to the tool 10 reaches a predetermined level. In this way, the lock retainer engaging the locking assembly 14 prevents movement of the locking assembly 14 until the predetermined pressure level is reached.

Alternatively, the tool 10 may comprise a lock retainer without including a latch retainer. In the present tool 10, the pressurised fluid may be supplied to the actuation chamber 38a via a common supply port 34. Only one of the locking assembly 14 and the latch assembly 16 may be retained by a retainer, in an example, to facilitate one of the locking assembly 14 or the latch assembly 16 moving before the other under the action of the pressurised fluid. Each of the latch assembly 16 and the locking assembly 14 may be retained by a respective retainer until the predetermined pressure is reached to cause the respective retainer to disengage. Provision of a retainer for either of the locking assembly 14 or the latch assembly 16 allows for a common supply port for the pressurised fluid to be used in the tool 10 to actuate both the locking and latching assemblies.

In this embodiment, the lock retainer comprises a plurality of pins 50 which are each mounted in an aperture in the latch actuator 30 and pushed radially inwardly relative to the latch actuator 30 by a spring 54 into engagement with a corresponding retainer formation 52 (in this embodiment a groove, indentation or aperture) provided on the radially outward surface of the lock actuator 20. Each pin 50 has an inclined cam surface which ensures that a force on the lock actuator 20 generally parallel to the longitudinal axis A pushing the lock actuator 20 towards the second end 12b of the tool body 12 results in a force on each retainer pin 50 which has a component acting to push the retainer pin 50 radially outwardly against the biasing force of the spring 54. The lock retainer thus ensures that the lock actuator 20 can only move when the pressure in the actuation chamber 38a is sufficiently high that the force on the lock actuator 20 is sufficient to overcome the biasing force of the springs 54 to push the pins 50 radially outwardly out of their corresponding retainer formation 52.

Whilst in this embodiment, the latch retainer and lock retainer are both spring pin assemblies, this need not be the case. Any form or retainer which prevents sliding movement of one part relative to another until the shear forces on the parts exceeds a predetermined level can be used. For example, one or both may equally comprise a shear pin or a snap ring.

It will be appreciated that once the pressure in the actuation chamber 38a is sufficient to overcome the retainers and release the lock actuator 20 and latch actuator 30, the lock actuator 20 and latch actuator 30 move in opposite directions -in this embodiment, the latch actuator 30 moving towards the first end 12a and the tool body 12 and the lock actuator 20 moving towards the second end 12b of the tool body 12.

There is an annular chamber 56 between the first end 20a of the lock actuator 20 an and the dog case support 26, which contracts when the lock actuator 20 moves in response to the supply of pressurised fluid to the actuation chamber 38a. A plurality of vent passages 58 are provided in the tool body 12 which each extend from this chamber 56 to a vent port 59 provided at the first end 12a of the tool body 12. The chamber 38b is also connected to the vent passages 58, to allow for venting of chamber 38b when its volume decreases by upwards movement of the latch actuator 30.

In this embodiment, the tool 10 further comprises a cutting apparatus 60 which is operable by the supply of pressurised fluid to a different portion of the tool than that which receives the pressurised fluid for operating the locking assembly and the latch assembly. The cutting apparatus 60 is operable to cut through a casing into which the cutting apparatus 60 is inserted in a plane generally perpendicular to the longitudinal axis of the casing. When used on a casing suspended in a wellbore, the cutting apparatus can therefore be used to cut the casing into an upper portion (which is secured to the wellhead) and a lower portion (which extends down into the wellbore Such a fluid operated cutting apparatus is well known to persons of skill in the art.

It should be appreciated, however, that the cutting tool need not be pressure operated. It could be electrically operated, configured to cut the casing by rotation of the cutting tool, or by a combination of pressure and rotation.

In this embodiment, the cutting apparatus 60 is operated by the supply of pressurised fluid along the main passage 13 of the tool body 12, whilst the locking assembly and latch assembly is operated by the supply of pressurized fluid to the space around the outside of the tool body 12. The cutting apparatus 60 is mounted on the second end 12b of the tool body 12.

Finally, a retainer ring 62 is mounted around the first end 12a of the tool body 12. The retainer ring 62 has a radially outwardly extending lip 62a at one end and the other end is secured to the tool body 12 via a shear ring 64.

The casing hanger recovery tool 10 is, in use, incorporated into a casing hanger recovery tool assembly 70 as illustrated in Figure 1. The casing hanger recovery tool 10 is secured to a landing string 72 via a slick joint 74 and spacer sub 76. The spacer sub 76 is connected to the first end 12a of the tool body 12 via a threaded tool joint, the spacer sub 76 is connected to the slick joint 74 via a threaded tool joint, and the slick joint 74 is connected to an end of the landing string 72 also via a threaded tool joint.

Vent lines 78 extend from each of the vent ports 59 in the tool body 12 through the slick joint 74 to a port adjacent the tool joint via which the slick joint 74 is connected to the landing string

The tool 10 may be used to recover the casing hanger and the top portion of the associated casing by running the casing hanger recovery tool assembly 70 into a wellhead assembly 100 as illustrated in Figure 3. The wellhead assembly 100 includes a BOP stack 102 which is mounted on top of a wellhead 104. A casing hanger 106 is located in the wellhead 104, and a casing 108 is suspended from the lowermost end of the casing hanger 106.

A pack-off 110 is secured to wellhead 104 just above the casing hanger 106, to lock the casing hanger 106 in the wellhead, and to provide substantially fluid tight seal which substantially prevents fluid from passing along the space between the casing hanger 106 and the wellhead 104. The pack-off 110 comprises a pack-off body 114 which supports a seal 116 which extends between the wellhead 104 and the casing hanger 106, and a locking element 118 which is arranged around the pack-off body 114 and urged radially outwardly by the pack-off body 114 into engagement with corresponding locking formations in the radially inwardly facing surface of the wellhead 104.

The wellhead assembly 100 is of conventional construction, and examples of such assemblies are well known to those of skill in the art.

The wellhead assembly 100 has a main passage, part of which is enclosed by a radially inwardly facing surface of the casing hanger 106. The casing hanger recovery tool assembly 70 is lowered into the main passage of the wellhead assembly 100 so that the dog cage support 26 of the casing hanger recovery tool 10 lands on a landing shoulder 112 provided on the radially inwardly facing surface of the casing hanger 106. The dog cage support 26 and landing shoulder 112 are provided with interlocking anti-rotation formations which prevent rotation of the dog cage support 26 relative to the casing hanger 106.

During this process, the casing hanger recovery tool 10 is arranged as illustrated in Figure 2. The lock actuator 20 is in an uppermost position in which it is as close to the first end 12a of the tool body 12 as possible, the latch actuator 30 is in a lowermost position in which it engages with the dog cage 24. The volume of the actuation chamber 38a is therefore minimized. The lock retainer pins 44 and latch retainer pins 50 are engaged with their corresponding retainer formations 48, 52, and so the lock actuator 20 and latch actuator 30 are locked in place. The locking dogs 18 are in their retracted positions. This arrangement of the casing hanger recovery tool 10 is herein after referred to as the run-in configuration.

As the casing hanger recovery tool 10 is landed on the landing shoulder 112, the latch 28 engages with a corresponding latch formation 120 provided on the pack-off 110. In this embodiment, the latch 28 is a snap ring, and this engagement occurs as a result of contraction followed by expansion of the snap ring during the landing process.

The casing hanger recovery tool 10 is then operated so that the casing hanger 106 is secured to the casing hanger recovery tool 10. This is achieved by the supply of pressurised fluid to the annular space in the main passage of the wellhead around the casing hanger recovery tool 10. This may be achieved by closing one or more blowout preventer in the BOP stack 102 around the slick joint 74 and using a choke / kill line to direct pressurised fluid to the annulus below the slick joint 74.

This causes fluid to flow through the actuation port 34 and into the actuation chamber 38a. As the pressure in the actuation chamber 38a increases, eventually it is sufficient to overcome the biasing force of the spring 54 of the lock retainers, and the pins 50 move radially outwardly out of engagement with the retainer formations 52. This release of the lock retainers allows the lock actuator 20 to move towards the second end 12b of the tool body 12 to increase the volume of the actuation chamber 38a. The lock actuator 20 therefore pushes the locking dogs 18 radially outwardly into their extended position, in which the locking formations 22 provided on the radially outwardly facing surface of each locking dog 18 engage with corresponding locking formations provided on the radially inwardly facing surface of the casing hanger 106. This is illustrated in Figure 4.

As the lock actuator 20 moves downwards, the volume of the annular chamber 56 below the lock actuator 20 decreases, and fluid from this chamber 56 is vented through the vent passages 58, the vent ports 59 and the vent lines 78 to the annulus above the slick joint 74. The pressure in the actuation chamber 38a is not, at this stage, sufficiently large to release the latch retainer, so the latch actuator 30 does not move.

The casing hanger recovery tool 10 is then operated to release the pack-off 110 from the wellhead 104. This is achieved by the continued supply of pressurised fluid to the annular space in the main passage of the wellhead around the casing hanger recovery tool 10. This causes fluid to continue to flow through the actuation port 34 and into the actuation chamber 38a. As the pressure in the actuation chamber 38a increases further, eventually it is sufficient to overcome the biasing force of the springs 46 of the latch retainers, and the pins 44 move radially outwardly out of engagement with the retainer formations 48. This release of the latch retainers allows the latch actuator 30 to move towards the first end 12a of the tool body 12, thus further increasing the volume of the actuation chamber 38a. This upwards movement of the latch actuator 30 and the latch 28 pulls the pack-off body 114 upwards, thus releasing the locking element 118 from engagement with the wellhead 104.

At some point in the process, the cutting tool 60 is operated by the supply of pressurised fluid to the main passage 13 of the casing hanger recovery tool 10 via the interior of the landing string 72 to cut the casing 108 at the desired location so that only a top portion of the casing 108 remains suspended from the casing hanger 106. Typically this is carried out after the movement of the latch actuator 30 to release the pack-off, or before. It could, however, be carried out before the tool 10 is locked to the casing hanger 106, or after the tool 10 is locked to the casing hanger 106 but before the pack-off is released. The casing may be cut a significant distance from the casing hanger 106 so that as much of the casing can be retrieved as possible.

In any event, once the casing is cut, the tool 10 locked to the casing hanger 106, and the pack-off released, the landing string 72 may then be pulled to lift the packoff 110, casing hanger 106 and severed top portion of the casing 108 out of the wellhead 104 together. The casing hanger recovery tool assembly 70 can thus be used to recover the pack-off 100, casing hanger 106 and top section of casing 108 in a single trip.

Whilst in this embodiment, as described above the retainers are configured so that the locking actuator 20 is released before the latch actuator 30 (lock release first), this need not be the case. They may, instead be configured so that the latch actuator 30 is released when the pressure in the actuation chamber 38a reaches a lower pressure, and the lock actuator 20 released when the pressure in the actuation chamber 38a reaches a higher level (latch release first). In this embodiment, this would be achieved by using different springs. By virtue of the use of such retainers, the tool 10 may be changed between the lock release first and latch release first modes of operation simply by replacing or swapping the retainers.

The pressurised fluid may be supplied to the latch assembly 16 and locking assembly 14 arranged in the same portion of the tool 10, i.e. both within the annulus (or possibly both in the main passage 13, with the cutting tool 60 supplied pressurised fluid via the annulus). A benefit of this configuration - with the latch assembly 16 and locking assembly 14 supplied from a common supply port, wherein the latch assembly 16 and locking assembly 14 are operated via a common fluid supply path - is that with the aid of at least one retainer, both the latch assembly 16 and locking assembly 14 can be made to move using the same supply of pressurised fluid, leaving an alternative fluid supply route for the cutting tool 60. Independent of the cutting tool 60, this also means thatthe annular space in the main passage of the wellhead around the casing hanger recovery tool 10 can be used both to route pressurised fluid to and to operate both the locking assembly 14 and latch assembly 16, and as this annulus is already a feature of the wellhead assembly 100 no dedicated channel or line or the like is required, nor are separate lines for each of the latch and locking assemblies.. Supplying pressurised fluid via the annulus is a simple approach and elegant solution when working at the relevant depths.

It is possible that the top section of the casing 108 may remain stuck in the wellbore, and it is impossible to pull the landing string 72 as described above. In this embodiment, the tool 10 is provided with contingency features to facilitate the release of the assembly. In particular, the tool 10 is configured so that this can be achieved by rotating the landing string 72 to rotate the casing hanger recovery tool 10 about its longitudinal axis. As specified above, the dog cage support 26 is secured to the tool body 12 using a screw thread, and is engaged with anti-rotation formations on the landing shoulder 112 of the casing hanger 106 so that it cannot rotate relative to the casing hanger 106. The rotation of the tool body 12 therefore generates a force parallel to the longitudinal axis A of the tool 10 between the tool body 12 and dog cage support 26. This generates a shear force on the shear ring 64, causing the shear ring 64 to be sheared. Once the shear ring 64 is sheared, the rotation of the tool 10 causes linear movement of the tool body 12b so that the second end of the tool body 12b moves towards the dog cage support 26, while the remaining parts of tool 10 are lifted towards the first end of the tool body 12a.

Eventually, the dog cage support 26 becomes detached from the screw thread on the tool body 12, and the locking actuator 20 returns to its starting position. The landing string 72 can then be pulled, the dog cage 26 landing on the radially outwardly extending lip 62a of the retainer ring 62, leaving the casing hanger 106 and casing in the wellhead, and recovering pack-off 110.

The invention is not limited by the embodiments described above; reference should be had to the appended claims.

Claims

CLAIMS

1. A tool for recovering a casing hanger from a wellhead, the tool comprising a tool body having a longitudinal axis, a pressure operated locking assembly, a pressure operated latch assembly which are configured to move in response to the supply of fluid to the tool, a retainer which is configured to prevent movement of either the locking assembly or the latch assembly until the pressure of the fluid supplied to the tool reaches a pre-determined level. 2. A tool according to claim 1 comprising a latch retainer which engages with the latch assembly to prevent movement of the latch assembly until the pressure of the fluid supplied to the tool exceeds a predetermined level. 3. A tool according to claim 1 comprising a lock retainer which engages with the locking assembly to prevent movement of the locking assembly until the pressure of the fluid supplied to the tool exceeds a predetermined level. 4. A tool according to claim 1 comprising a lock retainer which engages with the locking assembly to prevent movement of the locking assembly until the pressure of the fluid supplied to the tool exceeds a first predetermined level and a latch retainer which engages with the latch assembly to prevent movement of the latch assembly until the pressure of the fluid supplied to the tool exceeds a second predetermined level which is higher than the first predetermined level.

5. A tool according to any preceding claim wherein the latch assembly comprises a latch and a pressure actuated latch actuator, the latch being movable relative to the tool body by movement of the latch actuator in response to the supply of fluid to the tool.

6. A tool according to claim 2 or claim 4 and claim 5 wherein the latch retainer engages with the latch actuator to prevent movement of the latch actuator relative to the tool body until the pressure of the fluid supplied to the tool exceeds a predetermined level.

7. A tool according to claim 5 or 6 wherein the latch is configured to move radially outwardly relative to the tool body from a contracted configuration to an expanded configuration.

8. A tool according to any one of claims 5 - 7 wherein the latch actuator comprises a sleeve which is mounted around the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis of the tool body in response to the supply of fluid to the tool.

9. A tool according to any preceding claim wherein the pressure actuated locking assembly comprises at least one locking element and a pressure actuated locking actuator, the locking element engaging with the locking actuator and being movable relative to the tool body by movement of the locking actuator in response to the supply of pressurised fluid to the tool. 10. A tool according to claim 2 or claim 3 and claim 9 wherein the lock retainer engages with the locking actuator to prevent movement of the locking actuator relative to the tool body until the pressure of the fluid supplied to the tool exceeds a predetermined level.

11. A tool according to claim 9 or 10 wherein the pressure actuated locking assembly comprises a plurality of locking elements, each and a pressure actuated locking actuator, the locking elements engaging with the locking actuator and being movable relative to the tool body by movement of the locking actuator in response to the supply of fluid to the tool.

12. A tool according to any one of claims 9 - 11 wherein the or each locking element is movable radially outwardly of the tool body by the locking actuator in response to the supply of fluid to the tool.

13. A tool according to any one of claims 9 - 12 wherein the locking actuator comprises a sleeve which is mounted around the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis of the tool body in response to the supply of fluid to the tool.

14. A tool according to any preceding claim wherein the pressure operated locking assembly and pressure operated latch assembly move in response to the supply of fluid to a common pressure supply port.

15. A tool according to any one of claims 5 - 8, and any one of claims 9 - 13 wherein the lock actuator and latch actuator each comprise a sleeve which is mounted on the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis thereof in response to the supply of fluid to an actuation chamber formed between the lock actuator, the latch actuator and the tool body, such movement of the lock actuator and latch actuator moving the lock element and latch respectively.

16. The tool according to any preceding claim further comprising a cutting apparatus which is configured to be inserted into a main passage of a tubular having a longitudinal axis and which operable to through the tubular in a plane generally perpendicular to the longitudinal axis thereof.

17. A tool for recovering a casing hanger from a wellhead, the tool comprising a tool body having a longitudinal axis, a pressure operated locking assembly and a pressure operated latch assembly which are configured to move in response to the supply of fluid to the tool, and a cutting apparatus which is configured to be inserted into a main passage of a tubular having a longitudinal axis and which is operable to cut through the tubular in a plane generally perpendicular to the longitudinal axis thereof.

18. A tool according to claim 17 wherein the tool body encloses a main passage, the cutting apparatus is configured to cut by the supply of fluid to either the main passage or the space surrounding the tool and the locking assembly and latch assembly move in response to the supply of pressurised fluid to the other of the main passage or the space surrounding the tool.

19. A tool according to claim 17 or 18 wherein the pressure operated locking assembly and pressure operated latch assembly move in response to the supply of pressurised fluid to a common pressure supply port.

20. A tool according to any preceding claim wherein the latch assembly comprises a latch and a pressure actuated latch actuator, the latch being movable relative to the tool body by movement of the latch actuator in response to the supply of fluid to the tool.

21. A tool according to any preceding claim wherein the pressure actuated locking assembly comprises at least one locking element and a pressure actuated locking actuator, the locking element engaging with the locking actuator and being movable relative to the tool body by movement of the locking actuator in response to the supply of fluid to the tool.

22. A tool according to any claim 20 and claim 21 wherein the lock actuator and latch actuator each comprise a sleeve which is mounted on the tool body and which is movable relative to the tool body generally parallel to the longitudinal axis thereof in response to the supply of fluid to an actuation chamber formed between the lock actuator, the latch actuator and the tool body, such movement of the lock actuator and latch actuator moving the lock element and latch respectively.

23. A casing hanger recovery assembly comprising a landing string and a tool according to any preceding claim mounted on an end of the landing string.

24. A method of removing a casing hanger and casing suspended from the casing hanger from a wellhead using a casing hanger recovery assembly according to claim 23 comprising:

a) running the landing string into the wellhead so that the tool is landed in the casing hanger,

b) supplying fluid to the wellhead to move the pressure operated locking assembly to lock the tool to the casing hanger,

c) supplying fluid to the wellhead to move the pressure operated latch assembly to disengage a pack-off from the wellhead.

d) pulling the landing string to lift the pack-off, casing hanger and top portion of casing from the wellhead.

25. A method according to claim 24 wherein the tool comprises a cutting apparatus, and the method includes operating the cutting apparatus to cut the casing in a plane generally perpendicular to the longitudinal axis thereof.

26. A method according to claim 25 wherein the tool body encloses a main passage, and the method comprises supplying fluid to either the main passage or the space surrounding the tool to operate the cutting apparatus and supplying fluid to the other of the main passage or the space surrounding the tool to move the locking assembly and the latch assembly.

Drawings

Priority

30.05.2023 GB 2308040.1

Patent classes

IPC classes

E21B 23/01

E21B 23/04

E21B 31/16

E21B 33/04

CPC classes

E21B 23/01

E21B 23/04

E21B 31/16

E21B 33/04

Citations

No publications found

Applicants, owners and inventors

Applicants

OneSubsea AS

Strandveien 4

1366 LYSAKER

NO (BÆRUM Municipality, Akershus county)

Org. number: 929765001

Inventors

Dmitri Volkov

Heggtoppen 12

3403 LIER

NO (LIER Municipality, Buskerud county)

Sachin Karegaonkar

Hurumveien 37

3474 ÅROS

NO (ASKER Municipality, Akershus county)

Agent

BRYN AARFLOT AS

Stortingsgata 8

0161 OSLO

NO (OSLO Municipality, Oslo county)

Org. number: 979993269

Reference: 148879NO

Status history

Payment history

Oppositions and appeals

No oppositions or appeals

Administrative limitation

No administrative limitation

Liens and licences

No liens or licenses registered

Gazette entries

No Gazette entries found

Only events from 2024.03.04 and onwards are shown.

TOOL FOR THE RECOVERY OF A CASING HANGER FROM A WELLHEAD