Removing a wellhead system from a well

Abstract

Method of removing at least part of a wellhead system of a well, the method comprising steps of:—using a support module, supporting at least part of the wellhead system at one or more support locations;—using a severing module, severing at least part of the wellhead system at a severing location, thereby forming a severed wellhead system section; and—lifting the severed wellhead system section away from the well, wherein the severing location is below at least one of the support locations, and during at least part of the step of cutting through the wellhead system, the support module fixes a vertical position of at least part of the wellhead system and / or exerts an upward vertical force on at least part of the wellhead system above the severing location.

Description

TECHNICAL FIELD

[0001] The aspects and embodiment thereof relate to the field of well abandonment, in particular to removing at least part of a wellhead system from a well. More in general, the aspects and embodiment thereof relate to the removal of part of a conduit or system of conduits.BACKGROUND

[0002] When a well for production of oil or gas from an oil or gas source is abandoned, a cement plug is placed in the well, for example near the cap rock. Subsequently the casings and tubing above the cement plug have to removed. When the casings and tubing have been removed, a top plug can be placed above the cement plug as a final seal for the oil or gas source. The casings and tubing are removed by severing the casings and tubing at a certain depth, and subsequently pulling the casings and tubing out of the well.

[0003] To be able to pull the casings and the tubing out of the well, a Christmas tree positioned on top of the wellhead has to be removed first. Typically, the Christmas tree is bolted to the wellhead. Thus, to remove the Christmas tree, the bolts have to be removed. It has been observed that these bolts may be hard to remove, in particular because the bolts may have been exposed to harsh environmental conditions for many years or even decades, for example causing corrosion of the bolts. After the bolts connecting the Christmas tree to the wellhead have been removed, a crane is used to lift the Christmas tree up and away from the wellhead.

[0004] After the Christmas tree has been removed, it may be further required to removing a tubing hanger and / or one or more conduit hangers. A large lifting force, in the order of hundreds of tons, may be required to pull the tubing hanger and / or one or more conduit hangers from the respective tubing or conduit due to for example corrosion.SUMMARY

[0005] A wellhead system is defined as the part of a well which is above the borehole. In general, a well disclosed herein may be a well for production of natural resources, such as but not limited to hydrocarbons such as oil and gas, salt, geothermal energy, or any other underground resource. A well may alternatively be used for transporting materials underground, such as in case of carbon sequestration or in geothermal applications.

[0006] A wellhead system typically comprises a wellhead and a Christmas tree on top of the wellhead, together with any tubing and casing extending above the borehole. A Christmas tree is an assembly of valves and conduits used to regulate the flow of natural resources produced from the well. Typically, a Christmas tree is a heavy object, with a weight which may exceed 5000 kg or even 10000 kg. Any tubing and casing extending out of the borehole of the well is in the present disclosure also regarded as being comprised by the wellhead system. Typically, a wellhead system may further comprise one or more blow-out-preventers, a casing head, any number of casing hangers, a tubing hanger, one or more casing spools, a tubing spool, any other wellhead component, or any combination thereof. Wellhead components typically have flanges which can be bolted together.

[0007] It is an object to make the abandonment of a well more easy, more safe, more convenient, faster, more predictable, less labour intensive, or any combination thereof. In particular, it is an object to make the process of removing at least part of a wellhead system of a well, such as but not limited to a Christmas tree and / or any conduit hanger such as a tubing hanger or casing hanger, more easy, more safe, more convenient, faster, more predictable, less labour intensive, or any combination thereof.

[0008] A first aspect provides a method of removing at least part of a wellhead system of a well. The method comprises steps of supporting at least part of the wellhead system at one or more support locations, and severing at least part of the wellhead system at a severing location, thereby forming a severed wellhead system section and lifting the severed wellhead system section away from the well.

[0009] The supporting may be performed by one or more support modules and / or the severing may be performed by one or more severing module. It is envisioned that the severing may also be at least partially manually performed by one or more operators.

[0010] According to the first aspect, the severing location is below at least one of the support locations, and during at least part of the step of severing the wellhead system, the support module fixes a vertical position of at least part of the wellhead system and / or exerts an upward vertical force on at least part of the wellhead system.

[0011] By fixing the vertical position and / or exerting an upward vertical force on the at least part of the wellhead system, it may be prevented that part of the wellhead system section above the severing location moves downwards. Such downward movement may negatively affect the step of severing the at least part of the wellhead system. For example, when the severing involves a cutting, milling, sawing, grinding, burring, burning, incinerating, oxidising, abrasive jetting, using a shaped charge explosive, using a laser, using a jet of fluid, or other action in which a saw cut is formed, the part of the wellhead system positioned above the saw cut may fall into the saw cut and / or the part of the wellhead system positioned above the saw cut may press onto the part of the severing module forming the saw cut.

[0012] When part of the wellhead system positioned above the saw cut presses onto the part of the severing module forming the saw cut, that part of the severing module may cause the part of the severing module forming the saw cut to become stuck. When the wellhead system in such cases is manually severed by an operator, a sudden increase or decrease of the force pressing onto the severing module, for example a saw, wire saw, or band saw, may cause a dangerous sudden increase or decrease of the force exerted by the severing module onto operator.

[0013] When the upward vertical force is exerted onto the part of the wellhead system above the severing location, the part of the wellhead system above the severing location may be actively moved away from the severing location, or at least the wellhead system can be pretensioned during the severing step to aid in the severing step.

[0014] The support module is arranged to support at least part of the wellhead system at one or more support locations. Supporting at least part of the wellhead system implies that at the one or more support locations, one, multiple or all degrees of freedom of the wellhead system are fixed relative to another point. Such other point may be the fixed world, for example via an arrangement frame, a support member of the support module, and / or a remaining part of the wellhead system such as a conductor casing.

[0015] When the support modules exerts an upward vertical force on at least part of the wellhead system above the severing location, at the severing location, a cutting plane or saw cut may be pretensioned. This pre-tensioning may even result in the saw cut or cutting plane to be opened up further as the saw cut or cutting plane progresses deeper into the wellhead system.

[0016] It will be understood that any support module disclosed herein for any arrangement and any method may be embodied as a single device, or a plurality of separate devices, such as a plurality of separate support members.

[0017] Another example of a support member which may be comprised by any support module disclosed herein is a wedge, which can be wedged into a saw cut. In particular, when a wedge is wedged into the saw cut while the saw cut is being formed, the wedge may prevent part of the wellhead system above the saw cut from pressing down onto the part of the severing module performing the cutting or sawing. The wedge may even be used to force the part of the wellhead system above the saw cut upwards, which may make the severing step easier.

[0018] Yet another example of a support member can be inserted into any opening of the wellhead system. Such an opening may for example be formed by any conduit, for example any radially extending conduit. Such an opening may alternatively be formed by opening a top of a Christmas tree. When the support member can be inserted into any opening of the wellhead system, the support member may be arranged to frictionally engage the wellhead system, for example an inner wall of the wellhead system. A frictional engagement may not be necessary when the support member is oriented under an angle relative to gravity, for example when the support member is inserted into a generally horizontal conduit of the wellhead system. The support member may thus be an inner gripper.

[0019] Any support member which may be comprised by any support module may be a threaded support member comprising an inner thread and / or an outer thread. The threaded support member may be threaded into or onto any part of the wellhead system comprising an inner thread or an outer thread. By virtue of the threaded connection then formed, forces can be transferred between the wellhead system and the support module.

[0020] In general, each support member may individually or together with a further support member constrain one, multiple, or all degrees of freedom, in any combination of one or more translations and / or rotations.

[0021] Any support member may be a moveable support member. When a support member is moveable, for example using any support member actuator, any support member may be used to control one or more or all degrees of freedom of the wellhead system and their respective support location. A support member actuator may for example be a hydraulic actuator, winch, electric actuator, or any other actuator for moving the support member for example relative to the arrangement frame and / or relative to the remaining wellhead system section.

[0022] Preferably, when a support module comprises at least two support members, at least one support member is moveable relative to at least one other support member. This allows the support module to be compatible with differently sized wellhead systems.

[0023] When at least some, and preferably all, of the degrees of freedom of the wellhead system are fixed, the wellhead system may remain stable during the step of cutting through the wellhead system. When the wellhead system would not be supported, in particular during or after the step of cutting through the wellhead system, the severed wellhead system section may accidentally fall off the remaining wellhead system section or generally the centreline of the severed wellhead system section may become misaligned with the centreline of the remaining wellhead system section.

[0024] At any support location, the wellhead system may for example be clamped by a clamp comprised by the support module. A clamp may generally comprise multiple clamp members which can be moved relative to each other towards one another. Clamp members moving relative to each other implies that any one or both clamp members move. When part of the wellhead system is positioned between the clamp members and the clamp member are moved relative to each other and towards one another, the wellhead system can be clamped between the clamp members. When the wellhead system is clamped at a support location, one or more or all degrees of freedom of the wellhead system at the support location become coupled to the clamp. As such, for example when the clamp in turn is fixed relative to the fixed world, the support location becomes coupled to the fixed world.

[0025] At any support location, the wellhead system may be vertically suspended from one or more suspension members as a support member. A suspension member may for example be a cable, rope, chain, lashing belt or other tension member suspended from a crane or hoist.

[0026] At any support location the wellhead system may be vertically supported by one or more support members. A support member may be a girder, beam, fork, or other stiff body onto which at least part of the weight of the wellhead system may be supported.

[0027] As an example, any support member which may be comprised by any support module disclosed herein may be wrapped at least partially around the wellhead system. For example, such a support member may comprise or be a cable, chain, belt, lashing belt or other type which can be at least partially wrapped around the wellhead system.

[0028] It will be appreciated that support modules are envisioned comprising any combination of the clamps, suspension members, and / or support members disclosed herein, such that at any support location, at least part of the wellhead system may be clamped, suspended, and / or supported in any manner as disclosed herein.

[0029] The severing module may for example be a cutting module. When the severing module is or comprises a cutting module, the severing location may be a cutting location. Alternatively or additionally, the severing module may be arranged for releasing a bolted connection between two elements of the wellhead system. Whenever in the present disclosure a severing module is mentioned, the severing module may be any cutting module. Whenever in the present disclosure a cutting module is mentioned, the cutting module may be substituted by any other severing module.

[0030] The cutting module is arranged for cutting through at least part of the wellhead system at a cutting location. This cutting action generally splits the wellhead system into two portions: a severed wellhead system section above the cutting location, and a remaining wellhead system section below the cutting location. A cutting action may additionally or alternatively sever one or more connection elements, such as bolts, nuts, and / or stud bolts comprised by the wellhead system and thus forming part of the wellhead system.

[0031] A cutting location may for example be expressed as a certain height, and the cutting module may generally cut through the wellhead system in a generally horizontal plane. In other embodiments, the cutting module may generally cut through the wellhead system in a plane under an angle relative to the horizon.

[0032] Severing the wellhead system using the severing module may involve breaking, tearing, demolishing, incineration, burning, cutting, sawing, or otherwise destructively forming two separate parts of the wellhead system. It may not be required to sever the entire wellhead system, for example when it is sufficient to severe one or more bolts and / or one or more conduits such as a tubing or casing.

[0033] For any embodiment of the method and arrangement disclosed herein, the cutting module may comprise one or more cutting devices. A cutting device may use a sawing action, milling action, cutting action, drilling action, burning action, melting action, incineration action, explosive action, abrasive action, or any combination thereof to cut through the wellhead system section. As such, for example a cutting device may be a circular saw, reciprocal saw, angle grinder, mill, chisel cutter, cutting wheel, torch, thermal lance, laser, water jet cutter, abrasive cutter, shaped charge, diamond wire, and / or any other device for cutting through the wellhead system section, which wellhead system section will typically comprise metal and / or concrete and / or cement.

[0034] The cutting location may be above a tubing hanger of the wellhead system, preferably near the tubing hanger. As such, after cutting through the wellhead system, the tubing hanger is exposed and any parts of the wellhead system which previously prevented or hindered access to the tubing hanger—such as the Christmas tree—can be removed.

[0035] For severing at least part of the wellhead system, the cutting module may be used to cut through one or more bolts and / or nuts of a bolted connection. By cutting through the bolts and / or nuts, which are part of the wellhead system.

[0036] It will be appreciated that preferably, but not necessarily, in any embodiment of the method for removing at least part of a wellhead system of a well, the Christmas tree or at least part thereof is removed. Such a Christmas tree is typically hard to handle because of its volume and / or weight and / or weight distribution and / or the shape with one or more conduits and valves protruding from the Christmas tree.

[0037] Generally, for any method disclosed herein, the wellhead system may be positioned at least partially in a well cellar. Alternatively, the wellhead system may be positioned above ground level, or above a sea bed.

[0038] Preferably, during at least part of the step of severing the wellhead system, the support module fixes an orientation of at least part of the wellhead system. Without the support module fixing the orientation of the wellhead system, due to the centre of gravity of the severed wellhead system section possibly being misaligned with the centreline of the severed wellhead system section, the severed wellhead system section might inadvertently tilt relative to its original orientation. Such tilting may be dangerous, especially considering the high weight of the severed wellhead system section, and the tilting is thus preferably avoided.

[0039] If the wellhead system would be manually severed, and the wellhead system is positioned in a deep well cellar, one or more persons would have to be present in the cellar. If the wellhead system would be suspended only from a crane, during or after the severing, the severed wellhead system section may move due to the centre of gravity of the severed wellhead system being misaligned with the hoisting point of the crane—causing a potentially dangerous situation. Furthermore, if only a crane is used for removing the severed wellhead system section, the crane is typically loaded with a high amount of elastic energy which is released at the moment the wellhead system is severed. This sudden release of elastic energy, which is for example stored in the long boom of a crane, may be dangerous and may even tip the crane over.

[0040] In any method disclosed herein, the severed wellhead system section may be lifted away from the remaining wellhead system section by pivoting the severed wellhead system section relative to a generally horizontal axis, which axis preferably but not necessarily is at a horizontal distance from the remaining wellhead system section.

[0041] Alternatively, the severed wellhead section may be lifted away from the remaining wellhead system section in a generally vertical movement, and subsequently pivoted about a generally vertical axis, which axis preferably but not necessarily is at a horizontal distance from the remaining wellhead system section. During this lifting and / or pivoting, the severed wellhead system section may remain in the same orientation.

[0042] Preferably, but not necessarily, as an option applicable to any method disclosed herein, the severing location may be below a tubing hanger of the wellhead system, and even more preferably, when the wellhead system comprises one or more casing hangers, preferably thus below any conduit hanger of the wellhead system. This may prevent a requirement that the tubing has to be removed from the tubing hanger, or that a casing has to be removed from its casing hanger, or that a hanger has to be removed from its housing such as a tubing spool or casing spool. Furthermore, having the severing location below the tubing hanger and / or casing hanger(s) allows the tubing and / or casing to be directly pulled out of the well—for example after having been severed downhole in the well—without having to accommodate the larger diameter of the hanger(s).

[0043] Additionally or alternatively, the severed wellhead system section comprises at least part of a Christmas tree of the wellhead system, preferably the entire Christmas tree. As such, the severing location may thus be below the Christmas tree.

[0044] For any method disclosed herein, the support module and the severing module may be connected to an arrangement frame of an arrangement for removing at least part of a wellhead system of a well. This may provide an advantage that the support module and the severing module can be transported and positioned together.

[0045] Whenever an arrangement frame is used, any method may comprise a step of positioning the arrangement frame next to the wellhead system. Alternatively, whenever an arrangement frame is used, any method may comprise a step of positioning the arrangement frame over opposing edges of a well cellar in which at least part of the wellhead system is positioned, in particular wherein at least part of the wellhead system protrudes through a notch or opening in the arrangement frame after the positioning of the arrangement frame.

[0046] Additionally, or alternatively, whenever an arrangement frame is used, the support module may be connected to the arrangement frame via a support module actuator, arranged to move at least part of the support module relative to the arrangement frame, and the method may further comprise a step of moving the support module supporting the severed wellhead system section relative to the arrangement frame away from the well. It will thus be understood that the support module and severed wellhead system section may be moved together after severing the severed wellhead system section from the remaining wellhead system section. The support module may continue to support the severed wellhead system section even during transport of the severed wellhead system section away for the well.

[0047] When the severing module is connected to the arrangement frame via a severing module actuator, arranged to move at least part of the severing module relative to the arrangement frame, the method may further comprise moving the severing module relative to the arrangement frame while severing the wellhead system at the severing location. This for example may allow a more automated severing step.

[0048] In any method and arrangement disclosed herein, a support surface may be comprised by or connected to the arrangement frame, and the method further comprises a step of placing the severed wellhead system section onto the support surface. Preferably, but not necessarily, the severed wellhead system section is positioned horizontally onto the support surface. Horizontally here means that a centreline of the severed wellhead system section is oriented generally horizontally.

[0049] In any method disclosed herein, the method comprise a step of placing at least part of the severed wellhead system section over or into a support body, preferably with the severed wellhead system section oriented in a vertical direction.

[0050] The support body may be generally positioned adjacent to the well, and may be used to prevent or reduce the chance of the severed wellhead system section from tilting and tipping over. As an option, but not necessarily, the support body may be connected to the arrangement frame.

[0051] For example to conveniently transport the severed wellhead system section away from the well, for example to be recycled or discarded, any method may comprise lifting the arrangement frame with the severed wellhead system section onto a vehicle or trailer. Preferably, but not necessarily, the severed wellhead system section is in a horizontal orientation when transported on the vehicle or trailer, for example to reduce the height of the severed wellhead system section, for example to allow the vehicle or trailer to pass under lowered bridge or other obstacles during transport.

[0052] As a particular option, when the severing module is a cutting module comprising a plurality of hollow conduits, severing the wellhead system at the severing location may comprise steps of feeding oxygen through the hollow conduits, igniting a distal end of the hollow conduits, thereby producing a stream of combustion products, and cutting through the wellhead system using the stream of combustion products.

[0053] As another option, for any arrangement and method disclosed herein, the severing module comprises a wire saw, such as a diamond wire saw, and the step of severing the wellhead system comprising sawing through the wellhead system with the wire saw. Alternatively, a band saw may be used and thus a band saw may be comprised by any severing module disclosed herein.

[0054] Any embodiment of the method may comprise supporting at least part of the wellhead system at at least two support locations, wherein the two support locations are positioned above the severing location and are spaced apart from each other.

[0055] When the support module comprises two support members which are moveable relative to each other, the method may further comprise supporting the wellhead system at a first support position below the severing location with a first support member, supporting the wellhead system at a second support location above the severing location with the second support member, and forcing the first support member away from the second support member. This forcing of the first support member away from the second support member may aid in severing the wellhead system.

[0056] A second aspect provides an arrangement for removing at least part of a wellhead system from a well. It will be appreciated that the arrangement according to the second aspect may be used in any method according to the first aspect.

[0057] The arrangement according to the second aspect comprises a support module for supporting at least part of the wellhead system at one or more support locations and a severing module for severing at least part of the wellhead system at a severing location. The support module is arranged for fixing a vertical position of at least part of the wellhead system and / or for exerting an upward vertical force on at least part of the wellhead system above the severing location.

[0058] Preferably, but not necessarily, the support module is arranged for fixing and / or controlling all degrees of freedom of the part of wellhead system above the severing location. As such, there is no risk of the severed wellhead system section from tipping over and / or falling into a saw cut and / or pressing its weight onto the severing module.

[0059] The severing module may comprise a wire saw, in particular a diamond wire saw. Additionally or alternatively, for any arrangement disclosed herein, the severing module may comprise any other severing module disclosed herein, such as a cutting module or severing module arranged for releasing a bolted connection.

[0060] It has been observed that for releasing a bolted connection between two flanges, it may be insufficient to remove the nuts of the bolted connection. In particular when the wellhead system has been in place for many years or even decades, corrosion may cause bolts or stud bolts to become stuck in the bores through the flange. In such cases, it may be desired to use the severing module to sever the bolts—preferably with the severing location in-between the flanges.

[0061] When any arrangement disclosed herein comprises an arrangement frame, the severing module and the support module may be connected to the arrangement frame. In particular, one or both of the severing module and the support module may be moveably connected to the arrangement frame.

[0062] For example, at least part of the support module may be moveably connected to the arrangement frame via a support module actuator, and / or at least part of the severing module may be moveably connected to the arrangement frame via a severing module actuator. This allows the support module and / or severing module to be positioned relative to the arrangement frame and / or relative to the wellhead system.

[0063] When an arrangement comprises a severing module actuator, the severing module actuator may be arranged for positioning at least part of the severing module below the arrangement frame, for example in to a well cellar. As such, the severing location may be in the well cellar, which allows a large part of the wellhead system to be severed.

[0064] The support module actuator may be arranged to pivot the support module relative to the arrangement frame. As such, for example during transport, the height of the arrangement may be reduced. Additionally or alternatively, when the support module can be pivoted relative to the arrangement frame, the severed wellhead system section when supported by the support module may be pivoted, for example from a vertical orientation to a horizontal orientation.BRIEF DESCRIPTION OF THE FIGURES

[0065] In the figures,

[0066] FIG. 1 schematically shows part of a well;

[0067] FIGS. 2A and 2B show a wellhead system of a well, respectively before a step of removing part of the wellhead system, and after the step of removing part of the wellhead system;

[0068] FIG. 3 schematically shows another example of a well;

[0069] FIGS. 4A and 4B show another example of an arrangement for removing part of a wellhead system;

[0070] FIGS. 5A-5C schematically depict in a section view other examples of a method of removing at least part of a wellhead system;

[0071] FIG. 6 shows a well 100 in a schematic top view; and

[0072] FIGS. 7A and 7B schematically show another arrangement in a side view and a front view.DETAILED DESCRIPTION OF THE FIGURES

[0073] FIG. 1 schematically shows part of a well 100, with a wellhead system 101 protruding out of a well cellar 102. The wellhead system 101 is generally defined as comprising any and all components of the well which protrude from the ground surface 104 of the well cellar 102. In case the wellhead system 102 is not positioned in a well cellar, the wellhead system 101 is generally defined as comprising any and all components of the well which protrude from the ground surface 109. Generally, the wellhead system 101 comprises a plurality of components which are connected via bolted connections, in particular via flanges which are bolted together.

[0074] For example, as depicted in FIG. 1, a Christmas tree 106 comprised by the wellhead system 101 has a flange 107 by which it is connected to a lower part of the wellhead system 101, by virtue of a schematically indicated bolted connection. The Christmas tree 106 may for example be connected to a tubing spool 108 of the wellhead system, in which a tubing hanger 110 may be positioned. It will be understood that in other examples of wellhead systems, the Christmas tree may be connected to another part of the wellhead system.

[0075] Generally, a well 100 comprises a tubing 112 connected to tubing hanger 110 positioned in the tubing spool 108. The well 100 depicted in FIG. 1 as an example comprises multiple casings surrounding the tubing 112, of which a single casing as an example is indicated with reference numeral 130. The casing 130 is connected to a casing spool 132 via a casing hanger 134.

[0076] It is an object of the present disclosure to provide for methods and arrangements with which at least part of a wellhead system 101—an example of which has been schematically depicted in FIG. 1—can be removed.

[0077] FIGS. 2A and 2B show a wellhead system 101 of a well 100, respectively before a step of removing part of the wellhead system 101, and after the step of removing part of the wellhead system 101. The removed part is in FIG. 2B indicated as severed wellhead system section 101′. When part of the wellhead system remains in place after the severing, the part is referred to as the remaining wellhead system section 101″. For removing the part of the wellhead system 101, an arrangement 200 for removing part of a wellhead system is used.

[0078] The arrangement 200 as shown in FIGS. 2A-2B comprises an arrangement frame 202, which however should be understood as being optional for any arrangement disclosed herein. Typically, but not necessarily, the arrangement frame 202 comprises a horizontal frame part 204 which can be supported on the ground surface 106. Optionally, although not depicted in FIGS. 2A-2B, the arrangement frame 202 may be supported on one or more legs, in particular the horizontal frame part 204 may be supported on one or more legs. One or more legs may be supported on the ground surface or even on a bottom surface or side surface of the well cellar or on the wellhead system. An example of such a leg is the support 250 depicted in FIG. 4A.

[0079] As an option for any arrangement 200, which is depicted in FIGS. 2A-2B, the arrangement frame 202 further comprises a moveable frame part 206 which is moveable relative to the horizontal frame part 204. In particular, between FIGS. 2A-2B, the moveable frame part 206 is moved upwards, as schematically depicted by arrow 1, and folded down towards the horizontal frame part 204, schematically depicted by arrow 2, in a pivoting movement. Embodiments of the arrangement 200 are also envisioned in which the upward movement depicted by arrow 1 is not required.

[0080] In the example of FIGS. 2A-2B, the arrangement 200 further comprises a support module 300, and a severing module 400. The support module 300 and the severing module 400 are both connected to the moveable frame part 206. Further embodiments are envisioned wherein one or both of the support module 300 and the severing module 400 are as an alternative connected to the horizontal frame part 204. In even further embodiments, separate arrangement frames may be provided for the support module 300 and for the severing module 400.

[0081] In the example of FIGS. 2A-2B, as an option applicable to any other arrangement disclosed herein, the support module 300 comprises an upper support member 302 and a lower support member 304. Respectively, the upper support member 302 and the lower support member 304 support the Christmas tree 106 as the part of the wellhead system which has to be removed at a first support location 301 and a second support location 303. The first support location 301 is spaced apart from the second support location 303.

[0082] In general, when the support module 300 is arranged to support the wellhead system 101 at multiple support locations, it may be desired to be able to move the support locations relative to each other—for example in order to be able to handle different types and sizes of wellhead systems.

[0083] Generally, the arrangement 200 may comprise a support module actuator (not shown) for moving the support member or support members relative to the arrangement frame 200 and / or relative to the fixed world and / or relative to one another. The support module actuator may be used to move the support member or support members over any one or more degrees of freedom relative to the arrangement frame 200 and / or relative to the fixed world and / or relative to one another.

[0084] When support members are moveable relative to one another, the direction of movement is preferably parallel to a centreline of the wellhead system 101.

[0085] As depicted in FIGS. 2A and 2B, the wellhead system 101 can be severed at a severing location 402 by the severing module 400, which severing location 402 may be in the well cellar 102. By virtue of the severing, in the example of FIGS. 2A and 2B, the tubing is also severed into a severed tubing section 112′ and a remaining tubing section 112″.

[0086] Preferably, as depicted in FIGS. 2A and 2B, but not necessarily for other methods disclosed herein, the severed wellhead system section 101′ comprises the Christmas tree 106 and the tubing hanger. Further preferably, the severed wellhead system section 101′ also comprises any casing hanger of the wellhead system section. As such, the tubing section 112″ of the remaining wellhead system section 101″ as well as any casing section of the remaining wellhead system section 101″ may be easily accessible for further well abandonment steps. In many of such well abandonment steps, equipment and / or fluid has to be lowered into the tubing and / or casings.

[0087] Examples are also envisioned wherein the tubing has already been removed. In such cases, wherever in the present disclosure the wording tubing is used in the present disclosure, the innermost casing or any other casing can also be envisioned.

[0088] In the example of FIGS. 2A and 2B, the severing module 400 is a cutting module 400, for example but not necessarily comprising a wire saw. When the severing module 400 is a cutting module 400, the severing location 402 is a cutting location 402. With may embodiments of the cutting module 400, the cutting module 400 is arranged to cut through the wellhead system 101 and the cutting location 402 may thus be at a variety of heights. To adjust the cutting location 402, a cutting module actuator as an example of a severing module actuator may be used to position the cutting module 400 relative to the wellhead system 101.

[0089] During the step of severing the wellhead system 101, the support module 300 fixes a vertical position of at least the part of the wellhead system above the severing location 402 and / or the support module 300 can exert an upward vertical force on at least the part of the wellhead system above the severing location 402 and / or prevents tilting of at least the part of the wellhead system above the severing location 402 and / or fixing all degrees of freedom of at least the part of the wellhead system above the severing location 402, and / or control any degree of freedom of the wellhead system, in any combination thereof. It will be understood that when a support module 300 comprises multiple support members, different functionalities may be performed by one or more support members, in any combination.

[0090] FIG. 3 schematically shows the well 100 of FIG. 1, with schematically indicated parts of an arrangement 200 for removing part of the wellhead system 101. In the example shown in FIG. 3, it is an object to sever a bolted connection between different elements of the wellhead system 101, and to remove the part of the wellhead system 101 above said bolted connection.

[0091] To sever a bolted connection, one or more nuts comprised by the bolted connection may be removed, for example by unthreading one or more nuts from a bolt. Alternatively, a bolted connection may be destructively severed, for example by cutting through one or more bolt and / or one or more nuts forming the bolted connection.

[0092] During and / or after a bolted connection has been severed, it may be preferred that the part of the wellhead system above the bolted connection is pulled or pushed away from the part of the wellhead system below the bolted connection. To this end, the support module of any arrangement may comprise at least two support members, one of which engaging part of the wellhead system above the bolted connection, and one of which engaging part of the wellhead system below the bolted connection. As such, it may be prevented that the entire wellhead system is accidentally pulled away from the bottom of the well cellar, for example by breaking a connection between a base plate or conductor casing of the wellhead system and the well cellar. In particular when wellhead system is not provided in a well cellar, it may be prevented that the wellhead system or part thereof, such as a casing, such as a conductor casing, is pulled out of the soil, in particular in case of a relatively shallow well—for example less than 1.000 metres or even less than 500 metres—for example a salt well. It will thus be understood that the methods and arrangements disclosed herein are also applicable to wells without a well cellar or with a shallow well cellar.

[0093] FIG. 3 shows an example of a well 100 with a wellhead system 101, and schematically indicated parts of an arrangement 200 for removing part of the wellhead system 101. For clarity of the figure, not all parts of the arrangement 200 are necessarily shown, such as one or more arrangement frames. The same reference numerals as used in conjunction with FIG. 1 apply here as well.

[0094] The arrangement 200 schematically depicted in FIG. 3 comprises a support module with a first support member 302 spaced apart from a second support member 304 of the support module. The arrangement 200 also comprises a severing module 400, here arranged for releasing one or more bolted connections 401 with which two elements of the wellhead system 101 are connected.

[0095] The first support member 302 is positioned below the bolted connection 401, and thus below at least part of the severing module 400. The second support member 304 is positioned above the bolted connection 401, and thus above at least part of the severing module 400.

[0096] As an example shown in FIG. 3, which as an option is applicable to any support member, the second support member 304 is positioned directly below a protruding part 163 of the wellhead system 101, which for example may be a flange, conduit, valve, or any other part of the wellhead system 101 with a locally increased diameter or width. The second support member 304 may as such be used to exert an upward vertical force on the wellhead system 101 via the protruding part 163. The second support member 304 may for example be or comprise a fork, girder, beam, or other stiff element. Additionally or alternatively, whenever in any method or arrangement a vertically upward force on the wellhead system is desired, a crane or hoist may be used as a support member.

[0097] As a further example shown in FIG. 3, which as an option is applicable to any support member, the first support member 302 may be positioned directly above a protruding part 164 of the wellhead system 101, which for example may be a flange, conduit, valve, or any other part of the wellhead system 101 with a locally increased diameter or width.

[0098] By virtue of being directly positioned above the protruding part 164, a vertically downward force may be applied onto the wellhead system 101 via the first support member 302.

[0099] Alternatively or additionally to exerting a vertical upward or downward force on the wellhead system by pushing against a protruding part of the wellhead system 101 with one or more support members, any support member may exert the force by virtue of a clamping action based on friction between the support member and the wellhead system 101.

[0100] The arrangement 200 as schematically indicated in FIG. 3 further comprises a support member actuator 330 for moving the first support member 302 relative to the second support member 304, in particular away from each other. The support member actuator 330 may comprise one or more hydraulic actuators, but may conceivably additionally or alternatively comprise any other electric, pneumatic, mechanical spindle, or other actuator.

[0101] During or after the severing module 400 has released the bolted connection 401, and in the example of FIG. 3 severs the Christmas tree 106 from the tubing spool 108, the support member actuator 330 can be used to force the Christmas tree 106 away from the tubing spool 108. Without the first support member 302, the Christmas tree 106 would have been pulling onto the base plate 133 of the wellhead system 101, which connects the wellhead system 101 to the well cellar 102, in particular to the bottom 104 of the well cellar. This may inadvertently break the base plate 133 away from the well cellar 102, which may be undesired.

[0102] FIGS. 4A and 4B show another example of an arrangement 200 for removing part of a wellhead system 101 of a well 100. The arrangement 200 of FIGS. 4A and 4B is used to explain different optional features, which may be readily applied to any other embodiment of the arrangement of the present disclosure.

[0103] A first option depicted in FIGS. 4A and 4B is that the severed wellhead system section 101′ can be first lifted vertically away from the remaining wellhead system section 101″ and / or the bottom 104 of the well cellar (depicted as arrow 1), and subsequently pivoted about a generally vertically axis (depicted as arrow 2). Furthermore, after the pivoting, optionally the severed wellhead system section 101′ may be lowered (depicted as arrow 3), for example onto the arrangement frame 202.

[0104] A second option depicted in FIGS. 4A and 4B is that a support protrusion 240 may be provided on which the severed wellhead system section 101′ can be placed, as shown in FIG. 4B. The support protrusion 240 may be comprised by the arrangement 200, or may be provided separate from the arrangement 200. When position on the support protrusion 240, the severed wellhead system section 101′ may be positioned more securely, for example less prone to tipping over.

[0105] A third option depicted in FIGS. 4A and 4B is that the arrangement 200 may comprise a support 250 to support the arrangement 200 on the bottom 104 of the well cellar 102. Preferably, the support 250 can be selectively lowered into the well cellar 102—as shown in FIG. 4A—and raised again out of the well cellar 102—as shown in FIG. 4B. The support 250 may for example be used to prevent the arrangement 200 from tipping over into the well cellar 102.

[0106] Any arrangement disclosed herein may comprise one or more supports. In general, a support may be positioned on the bottom of the well cellar 102, but also on any part of the wellhead system, in particular of the remaining wellhead system section. For example, the support may be positioned on a conductor casing or base plate of the wellhead system.

[0107] Any support 250 may be positioned between at least part of the arrangement frame 202 and the wellhead system 101. Alternatively, the wellhead system 101 may be positioned between a support 250 and at least part of the arrangement frame 202. Further alternatively, a support 250 may be positioned at the same offset to the arrangement frame 202 than the wellhead system 101.

[0108] A fourth option depicted in FIGS. 4A and 4B is that the severing module 400 and the support module 300 can be provided separately, for example on separate frames 202, 202′.

[0109] Any severing module 400 may be moveable relative to the frame 202′ to which the severing module 400 is connected. For example, one or more of a hydraulic, electric, pneumatic, mechanical spindle, or other actuator may be used to move the severing module 400.

[0110] It will be appreciated that the explicitly numbered first, second third and fourths options may be readily applied to any other arrangement of the present disclosure. Also optional features disclosed but not explicitly numbered may be readily applied to any other arrangement of the present disclosure.

[0111] FIGS. 5A and 5B schematically depict in a section view another example of a method of removing at least part of a wellhead system 101, in particular for removing at least a tubing hanger 110 as an example of a conduit hanger. FIG. 5A shows the wellhead system 101. A tubing 112 is connected to the tubing hanger 110, which tubing hanger 110 in turn is connected to a tubing spool 108. It will again be appreciated that whenever a tubing is shown and / or discussed, also any other conduit may be implied, such as any casing.

[0112] In the situation depicted in FIG. 5A, a severing member 405 as at least part of a severing module has been in inserted into the tubing 112. The severing member 405 may be a cutting member, sawing member, milling member, incineration member, demolition member such as a shaped charge, abrasive jetting member, or any other device suitable for severing a conduit such as a tubing or casing. The severing member 405 is used to sever the tubing 112 at a severing location 402. Whenever the tubing 112 is severed, the severing location 402 may be below the wellhead system 101, i.e. underground in the well.

[0113] The severing member 405 may be suspended from a suspension member 407 which for example can be a rope, cable, E-line, slickline, conduit, or any other suspension member. The suspension member 407 can be suspended from a crane of hoist, and as such lowered into the tubing 112.

[0114] Before, during, or after the tubing 112 is severed, a bolted connection 401 between the tubing spool 108 and an element of the wellhead system 101 to which the tubing spool 108 is connected, such as a casing spool 132, can be severed.

[0115] Whenever it is desired to sever a bolted connection, thus also in other examples than the example depicted in FIGS. 5A and 5B, it may be sufficient to cut or saw or sever only the bolts forming the bolted connection. When all bolts are severed, the elements which were previously connected via the bolted connection can be moved away from each other.

[0116] Any severing module may be generally moveable relative to the wellhead system 101, for example using one or more severing module actuators. The movement may for example be a movement in a generally horizontal plane, or at least a translational movement, for example generally radially relative to the wellhead system 101. Movements for the severing module are also envisioned wherein the severing module is moved circumferentially around the wellhead system 101 to sever the well head section.

[0117] FIG. 5B depicts the wellhead system 101 of FIG. 5A after severing the tubing 112, and thus after a severed tubing section 112′ and a remaining tubing section 112″ have been formed. Furthermore, the bolted connection 401 has been severed, allowing the tubing spool 108 to be lifted or generally moved away from the casing spool 132.

[0118] In the situation depicted in FIG. 5B, as an option applicable in any method and arrangement disclosed herein, an inner support member 350 has been inserted into the severed wellhead system section 101′. The inner support member 350 may for example frictionally engage an inner wall of the severed tubing section 112′ or may be threaded into the tubing hanger 110. When the inner support member 350, which can be comprised by the support module of any arrangement, is suspended from a suspension member 307, a movement, for example a vertical movement, of the inner support member 350 can be used to move the severed wellhead system section 101′.

[0119] As can be seen in FIGS. 5A and 5B, the method for removing at least of a wellhead system allows such removal without having to disconnect the tubing 112 from the tubing hanger 108, which would otherwise require a large pulling force, often in the order of hundreds of tons, for example 350 tons or more.

[0120] FIG. 5C schematically shows yet another method for removing at least part of a wellhead system. Compared to the situation depicted in FIG. 5A, the Christmas tree has been removed from the wellhead system 101, for example but not necessarily using any of the methods disclosed herein. Although not shown in the figures, it is envisioned that the Christmas tree may be replaced with a BOP-system.

[0121] FIG. 5C shows a further part of the wellhead system 101 being removed: the tubing hanger 110 with a severed section of the tubing 112′ still connected thereto. The tubing hanger 110 has been pulled out of the tubing spool 108, which tubing spool 108 may thus still be connected to the remaining wellhead system section 101″. Thus, it may be avoided that the tubing 112 has to be pulled out of the tubing hanger 110. It will be appreciated that the severed tubing section 112′ may have any length, for example in the orders of centimetres, but also metres, tens of metres, or even kilometres. As such, it will be understood that the severing location 402 may indeed be underground in the well, for example at 50 metres or below, 100 metres or below, or even 1.000 metres or below.

[0122] For lifting the tubing hanger 110 away from the remaining wellhead system section 101″, a support member 377 is connected to the tubing hanger 110. The support member 377 may be a threaded support member threaded into a thread of the tubing hanger 110, or conceivable any other support member disclose herein.

[0123] FIG. 6 shows a well 100 in a schematic top view, with a wellhead system 101 in a well cellar 102. An arrangement 200 is positioned over the well cellar 102, over opposing edges thereof and optionally even covering all edges of the entire well cellar 102. An opening 260 is provided through the arrangement frame 202, through which part of the wellhead system 101 protrudes. Alternatively to the opening, a notch may be provided into the arrangement frame 202, through which part of the wellhead system 101 protrudes.

[0124] As an option shown in FIG. 6 but applicable to any of the arrangements disclosed herein, the arrangement 200 comprises a moveable frame part 206. In the example of FIG. 6, the moveable frame part 206 is moveable in an x-direction, for example but not necessarily over a pair of rails 262. The moveable frame part 206 is preferably further moveable in an y-direction orthogonal to the y-direction. An actuator for moving the moveable frame part 206 in the y-direction may be moveable by the actuator for moving the moveable frame part 206 in the x-direction.

[0125] In general, by allowing the moveable frame part 206 to be positioned in a horizontal plane relative to the arrangement frame 202, the moveable frame part 206 may be positioned relative to the wellhead system 101 after the arrangement frame 202 has been put in place. When at least part one or both of the support module 300 and the severing module 400 are mounted to the moveable frame part 206, the at least part one or both of the support module 300 and the severing module 400 are mounted to the moveable frame part 206 may thus be positioned relative to the wellhead system 101 after the arrangement frame 202 has been put in place.

[0126] FIGS. 7A and 7B schematically show another arrangement 200 in a side view and a front view. In FIGS. 7A and 7B, different options for arrangement are depicted in a single embodiment of an arrangement 200 for removing at least part of a wellhead system from a well. It will be understood that this embodiment is also envisioned with less optional features, more optional features, or other optional features as disclosed herein.

[0127] The arrangement comprises an arrangement frame 202, to which the support module 300 and the severing module 400 are connected, preferably by one or more actuators such that at least part of the support module 400 and at least part of the severing module 400 are moveable relative to the arrangement frame 202.

[0128] For example, the severing module 400 may be moveable in a cutting direction c, which may be substantially radial relative to the centreline 103 of the wellhead system 101.

[0129] The support module as depicted in FIGS. 7A and 7B comprise a number of support members. Although this particular combination is a preferred combination of support members, it will be understood that the support module 300 may comprise any number of other support members as disclosed herein, in any combination.

[0130] A fork 371 is depicted in FIGS. 7A and 7B as an example of a support member, which fork 371 comprises two fork members 371′, 371″ between which the wellhead system 101 can be positioned. As a further option, an indentation 379 may be provided in the fork members 371′, 371″ to accommodate part of the wellhead system 101, for example a protruding conduit 170 of the wellhead system 101. Optionally, the fork members 371′, 371″ can be moved towards each other to clamp the wellhead system 101 in-between the fork members 371′, 371″.

[0131] A clamp 372 is depicted in FIGS. 7A and 7B as an example of a support member, which clamp 372 comprises two clamp members 372′, 372″. The clamp members 372′, 372″ can be moved towards each other and clamp the wellhead system 101 in-between each other. Preferably, as shown in FIG. 7B, the clamp members 372′, 372″ hook around the wellhead system 101.

[0132] Another fork 374 is depicted in FIGS. 7A and 7B as an example of a support member, which fork 374 defines a reception space 374 for receiving part of the wellhead system, such as a conduit 171 of a Christmas tree, therein. The fork 374 can be used to prevent tilting of the wellhead system 101 in one or more directions. Compared to the orientation depicted in FIG. 7A, the fork may also be rotated 90 degrees.

[0133] One, more, and preferably all of the support members 371, 372, 373, are adjustable in height—i.e. in the axial direction A. Furthermore preferably, also the severing module 400 is adjustable in height—i.e. in the axial direction A. This applies to any support member and severing module disclosed herein.

[0134] One, more, and preferably all of the support members 371, 372, 373, may be moved towards and / or away from the wellhead system 101—e.g. in the radial direction R—for example relative to the support frame 202. This applies to any support member of any support module disclosed herein.

[0135] In the description above, it will be understood that when an element is referred to as being connect to another element such as the arrangement frame, the element is either directly connected to the other element, or intervening elements may also be present. Also, it will be understood that the values given in the description above, are given by way of example and that other values may be possible and / or may be strived for.

[0136] It is to be noted that the figures are only schematic representations of embodiments that are given by way of non-limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the disclosure may include embodiments having combinations of all or some of the features described.

Claims

1. A method of removing at least part of a wellhead system of a well, the method comprising steps of:using a support module, supporting at least part of the wellhead system at one or more support locations;severing at least part of the wellhead system at a severing location, thereby forming a severed wellhead system section; andlifting the severed wellhead system section away from the well,wherein the severing location is below at least one of the support locations, and during at least part of the step of severing the wellhead system, the support module fixes a vertical position of at least part of the wellhead system and / or exerts an upward vertical force on at least part of the wellhead system above the severing location.

2. The method of claim 1, wherein during at least part of the step of severing the wellhead system, the support module fixes an orientation of at least part of the wellhead system.

3. The method of claim 1, wherein the severed wellhead system section is lifted away from the remaining wellhead system section by pivoting the severed wellhead system section relative to a generally horizontal axis.

4. The method of claim 1, wherein the severed wellhead system section is lifted away from the remaining wellhead system section in a generally vertical movement, and subsequently pivoted about a generally vertical axis, which axis is at a horizontal distance from the remaining wellhead system section.

5. The method of claim 1, wherein the severing location is below a tubing hanger of the wellhead system.

6. The method of claim 1, wherein the severed wellhead system section comprises at least part of a Christmas tree of the wellhead system.

7. The method of claim 1, wherein the support module and the severing module are connected to an arrangement frame of an arrangement for removing at least part of a wellhead system of a well.

8. The method of claim 7, further comprising a step of positioning the arrangement frame next to the wellhead system.

9. (canceled)10. The method of claim 7, wherein the support module is connected to the arrangement frame via a support module actuator, arranged to move at least part of the support module relative to the arrangement frame, and the method further comprises a step of moving the support module supporting the severed wellhead system section relative to the arrangement frame away from the well.11.-13. (canceled)14. The method of claim 7, further comprising lifting the arrangement frame with the severed wellhead system section onto a vehicle or trailer.15.-16. (canceled)17. The method of claim 1, comprising supporting at least part of the wellhead system at at least two support locations, wherein the two support locations are positioned above the severing location and are spaced apart from each other.

18. The method of claim 1, wherein the support module comprises two support members which are moveable relative to each other, and the method comprises supporting the wellhead system at a first support position below the severing location with a first support member, supporting the wellhead system at a second support location above the severing location with a second support member, and forcing the first support member away from the second support member.

19. The method of claim 1, wherein the severed wellhead section comprises a conduit hanger, and the conduit hanger is pulled out of a hanger spool in which the conduit hanger is connected.20.-21. (canceled)22. An arrangement for removing at least part of a wellhead system from a well, the arrangement comprising:a support module for supporting at least part of the wellhead system at one or more support locations; anda severing module for severing at least part of the wellhead system at a severing location;wherein the support module is arranged for fixing a vertical position of at least part of the wellhead system and / or for exerting an upward vertical force on at least part of the wellhead system above the severing location.

23. The arrangement of claim 22, wherein the support module is arranged for fixing and / or controlling all degrees of freedom of the part of wellhead system above the severing location.

24. The arrangement of claim 22, wherein the severing module comprises a wire saw.

25. The arrangement of claim 22, further comprising an arrangement frame, and wherein the severing module and the support module are connected to the arrangement frame.

26. (canceled)27. The arrangement of claim 25, further comprising a severing module actuator for positioning the severing module below the arrangement frame.

28. The arrangement of claim 25, wherein the support module actuator is arranged to pivot at least part of the support module relative to the arrangement frame.29.-31. (canceled)

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