The invention relates to a locking device for locking two components to each other and a method of locking a first component to a second component. The two components may be components of a well assembly, e.g. a subsea well assembly.

Typically a well assembly comprises a number of stacked tubulars stacked inside each other and that extend into a formation.

Typically the outermost tubular section is a conductor which is made up of a conductor housing at its uppermost end and a conductor pipe connected at the lower end of the conductor housing. Inside the conductor housing is located a number of tubulars. These tubulars (that may or may not contain pressure) include a high pressure wellhead housing that is connected to a well casing and one or more casing hangers that each support a casing.

The conductor is known to be supported by a support structure that interfaces with the surface (e.g. a sea bed) through which the well penetrates.

Such a support structure may be a template or a suction anchor, for example.

It is desired to provide a locking device for locking two components of a well assembly to each other which facilitates locking of the components together.

In a first aspect, the present invention provides a locking device for locking a first well assembly component to a second well assembly component, the locking device comprising: a first engagement surface associated with the first well assembly component; and a second engagement surface associated with the second well assembly component, wherein the engagement surfaces can be moved relative to each other between an engaged position and a disengaged position, and wherein the engagement surfaces can be engaged and disengaged by rotation of the first and second engagement surfaces relative to each other.

The well assembly components may be subsea well assembly components, i.e. components of a well assembly that is installed and used subsea.

The locking device may be for providing a radial preloaded connection between the engagement surfaces so as to provide a preloaded connection between the first well assembly component and the second well assembly component.

Thus the present invention may provide a locking device for locking a first subsea well assembly component to a second subsea well assembly component, the locking device comprising: a first engagement surface associated with the first subsea well assembly component; and a second engagement surface associated with the second subsea well assembly component, wherein the engagement surfaces can be moved relative to each other between an engaged position and a disengaged position, wherein the engagement surfaces can be engaged and disengaged by rotation of the first and second engagement surfaces relative to each other, and wherein the locking device is for providing a radial preloaded connection between the engagement surfaces so as to provide a preloaded connection between the first subsea well assembly component and the second subsea well assembly component.

In a second aspect, the present invention provides a method of locking a first well assembly component to a second well assembly component, the method comprising: providing a first engagement surface associated with the first well assembly component; providing a second engagement surface associated with the second well assembly component; and rotating the first and/or second engagement surfaces relative to each other from a disengaged position to an engaged position.

As mentioned above, the well assembly components may be subsea well assembly components, i.e. components of a well assembly that is installed and used subsea.

Similarly, when in the engaged position, the locking device may provide a radial preloaded connection between the engagement surfaces so as to provide a preloaded connection between the first well assembly component and the second well assembly component.

Thus the present invention may provide a method of locking a first subsea well assembly component to a second subsea well assembly component, the method comprising: providing a first engagement surface associated with the first subsea well assembly component; providing a second engagement surface associated with the second subsea well assembly component; and rotating the first and/or second engagement surfaces relative to each other from a disengaged position to an engaged position, wherein, when in the engaged position, the locking device provides a radial preloaded connection between the engagement surfaces so as to provide a preloaded connection between the first subsea well assembly component and the second subsea well assembly component.

The method of the second aspect may be performed by providing and/or using the locking device of the first aspect. The below optional features are applicable, as appropriate, to both the locking device of the first aspect and the method of locking of the second aspect (including when the components are subsea well assembly components and/or when the locking device is for providing a radial preloaded connection between the engagement surfaces).

The well assembly components may be coaxial. One component may be located, at least in part, around the outside of, at least part of, the other component.

The first well assembly component may be located at least partially within the second well assembly component, i.e. the first well assembly component may be radially inward of the second well assembly component.

The first engagement surface may face radially outward and the second engagement surface may face radially inward.

The well assembly may be a subsea well assembly. The first and second well assembly components may be subsea well assembly components. The invention may be useful subsea when access to the well assembly components may be more difficult.

Alternatively, the well assembly may be a non-subsea well assembly, e.g. a land-based well assembly. Hence the well assembly components may be land- based well assembly components.

The well assembly may be or comprise a well, e.g. a subsea well, and/or any associated components such as a support structure/foundation and associated equipment such as safety devices (e.g. Christmas trees and/or BOP), riser and/or surface equipment etc.The locking device may ensure that there is no, or limited, e.g. substantially no, radial clearance between the well assembly components. The locking device and method may be for providing a preloaded connection between the two well assembly components.

By having a preloaded connection between well assembly components it may be ensured that loads can be effectively transferred from the well assembly components, such as the well tubulars, to the surface (e.g. sea bed) through which the well penetrates.

By preloaded it may be meant that the connection (i.e. between the engagement surfaces) is subjected to an initial load which statically determines the relative position of the well assembly components (and/or the engagement surfaces) as well as the resulting reaction load between these. The connection may be configured such that the internal reaction loads are retained when the initial load is removed. When the connection between two connected components is preloaded the relative position between the connected components may not be changed unless any applied external load (additional to the preload) results in a force on the connection which is greater and opposite to the preload force. The locking effect and/or the preloaded connection may be in a radial and/or axial direction. The locking device may result in a preloaded connection with a desired radial and/or axial preload. The resulting stress (which may be referred to as the contact stress) between the preloaded connected parts (i.e. engagement surfaces and/or well assembly components) may ensure that there is no relative displacement or change in the position of the connected parts unless any applied external load (additional to the preload) results in a force on the connection which overcomes, e.g. is greater than and in an opposing direction to, the preload force.

Thus, for example, if the assembly is subjected to a varying load that, even at its maximum, results in a load on the connection which is less than the preload, this varying load may not result in any change in the relative position of the engagement surfaces and/or well assembly components.

The parts of the well assembly components that are locked and/or preloaded relative to each other may have a circular or substantially circular cross- sectional shape. Conversely, the well assembly components may have a non circular cross-sectional shape. The references herein to radial and circumferential should not necessarily be interpreted as meaning that the parts necessarily have a circular cross-section.

The well assembly components may be well components, e.g. subsea well components.

The well assembly components that are directly or indirectly locked and/or preloaded relative to each other may comprise one or more of a well tubular (such as a conductor housing and/or a high pressure wellhead housing), a receptacle, a support structure (such as a template or suction anchor), and/or a well element for mounting on a well tubular (such as a blowout preventer (BOP) or Christmas tree).

For example, the locking device may be for directly or indirectly locking and/or preloading: a conductor housing to a receptacle and/or a support structure such as a template or a suction anchor; a high pressure wellhead housing to a conductor housing, adapter/receptacle and/or some other support structure such as a template or a suction anchor; and/or a well element for being mounted on one or more of the well tubulars (such as a Christmas tree or a blow-out preventer) to a well tubular, e.g. the high pressure wellhead housing, and/or a support structure.

When the well assembly component is a conductor housing and/or a wellhead housing it may be connected to a pipe (i.e. extension) at its lower end (as is conventional) or not connected to a pipe, i.e. the part may consist of only the housing itself.

The locking device may be for locking a well tubular (such as a high pressure wellhead housing or a conductor housing) within a receptacle. The receptacle may be another well tubular, a well bay or other receptacle of a support structure or any other receptacle that may be part of and/or fixed to the well support structure.

The support structure may have a well-bay area to which a tubular such as a conductor housing, can be locked using the locking device.

The locking device may align, e.g. centralise and/or coaxially align, the two well assembly components relative to each other. For example the locking device may securely and accurately align a conductor housing with a subsea structure.

The locking, centralisation and/or preload may be provided and released (i.e. the locking device may be engaged and disengaged) as required during the lifetime of the well. This may for example be to accommodate periods of well- growth and/or to ensure that the conductor housing is not distorted during installation of the high pressure wellhead housing.

The locking device may lock the well assembly components relative to each other in a radial/lateral direction and/or an axial/vertical direction.

The radial direction may be horizontal. The axial direction may be vertical.

The locking device may be engageable and disengageable repeatedly, as required.

The method may comprise rotating the first and/or second engagement surfaces relative to each other from an engaged position to a disengaged position.

The first and/or second engagement surfaces may be rotated relative to each other in a first direction from a disengaged position to an engaged position. The first and/or second engagement surfaces may be rotated relative to each other in a second opposite direction from an engaged position to a disengaged position.

For example, the locking device may be moved from a disengaged position to an engaged position by the first engagement surface moving in an anti-clockwise direction relative to the second engagement surface and the second engagement surface moving in a clockwise direction relative to the first engagement surface (although one or other of the engagement surfaces may be stationary during engagement of the surfaces).

The locking device may be moved from an engaged position to a disengaged position by the first engagement surface moving in a clockwise direction relative to the second engagement surface and the second engagement surface moving in an anti-clockwise direction relative to the first engagement surface (although one or other of the engagement surfaces may be stationary during disengagement of the surfaces).

When the locking device is in a disengaged position the distance between the first engagement surface and the second engagement surface may be non zero. In other words, there may be a gap or a clearance between the engagement surfaces. This non-zero distance may be in the radial direction (i.e. there is a radial distance/a radial gap/a radial clearance).

When the locking device is in an engaged position the distance between the first engagement surface and the second engagement surface may be zero or substantially zero, i.e. there may be no or substantially no gap between the engagement surfaces. This may be referred to as zero (or substantially zero) clearance. This zero distance may be in the radial direction (i.e. there is no radial distance/radial gap/radial clearance).

The locking device may be configured so that as the locking device is moved from a disengaged position to an engaged position the distance/clearance, e.g. radial distance/clearance, between the first and second engagement surfaces decreases, e.g. the radial gap narrows.

The locking device may be configured so that as the locking device is moved from the engaged position to the disengaged position the

distance/clearance, e.g. the radial distance/clearance, between the first and second engagement surfaces increases, e.g. the radial gap widens.

Moving the locking distance from the disengaged position to the engaged position may be understood as‘closing the radial gap’, i.e. decreasing the radial distance/clearance between the engagement surfaces until there is no radial clearance, i.e. until the engagement surfaces are in contact with each other in the radial direction. Once a zero distance between the engagement surfaces has been achieved, more force may be applied so as to provide a preloaded connection between the engagement surfaces.

The locking device may be engaged and disengaged during installation and/or operation of the well. This may allow times in which the locking device is disengaged such that the two well assembly components can move relative to each other and other times in which the locking device is engaged to prevent relative movement between the two well assembly components.

The locking device may be engaged and disengaged by application of a lateral force, i.e. a force that is applied from a lateral direction. The force may be lateral relative to the first well assembly component and/or the second well assembly component. The locking device may be engaged and disengaged without requiring the application of a vertical/axial force, e.g. a force which is vertical/axial relative to the first well assembly component and/or the second well assembly component.

The locking device may be engaged and disengaged without requiring vertical access above the locking device, e.g. without requiring vertical access above the well. This may facilitate the locking device being engaged and disengaged as required e.g. during installation or operation of a well. This may be achieved by the locking device being operable (i.e. engageable and disengageable) by means of lateral access to the locking device, e.g. by means of lateral access to the well and/or well assembly. The locking device may be operable from a lateral position of the first well assembly component and the second well assembly component. This may be achievable by the first and/or second engagement surface being rotatable by means of an actuator located laterally of the engagement surfaces. The engagement surface and/or actuator may extend through the wall of the outermost well assembly component, i.e. the second well assembly component.

The locking device may allow engagement and disengagement without having to remove equipment, e.g. well equipment such as valves such as a BOP or Christmas tree, that is mounted on or above the well assembly (e.g. mounted on the first or second well assembly component). For example, well equipment may be mounted (e.g. on the first or second well assembly component) after the first and second well assembly components are locked by the locking device. The first and second well assembly component may be unlocked from each other whilst the well equipment is mounted on the assembly (e.g. mounted on the first or second well assembly component).

The locking device may be used to engage and strengthen the interface between the components (e.g. between a well tubular, such as a conductor housing, and a support structure) during installation, re-entry and workover operations and be released during periods of production to allow relative

movement, such as well growth.

The locking device may be used to lock well assembly components relative to each other prior to installation, i.e. away from the installation site, and/or used to lock well assembly components relative to each other at the installation site. For example, the locking device may be adapted for use with both a pre-installed well assembly component, e.g. conductor housing, (for which locking would be performed away from the installation site) or a more conventional system where the well assembly component, e.g. conductor housing, is run and installed after the other well assembly component, e.g. support structure, has been installed (for which locking would be performed at the installation site).

The locking device may comprise one or more first engagement surfaces on or associated with (e.g. fixed relative to) the first well assembly component and one or more second engagement surfaces on or associated with (e.g. fixed relative to) the second well assembly component.

The engagement surfaces may be provided by one or more protrusions, e.g. wedge blocks. The first engagement surface may be provided by a plurality of first protrusions, for example inner wedge blocks, and the second engagement surface may be provided by a plurality of second protrusions, for example outer wedge blocks. The number of inner protrusions (i.e. that make up the first engagement surface) may equal the number of outer protrusions (i.e. that make up the second engagement surface).

When the engagement surfaces are provided by a plurality of protrusions, e.g. a plurality of wedge blocks, the protrusions may be circumferentially spaced about the first and/or second well assembly component.

The second engagement surface may be provided by one or more rotatable, eccentric cams. The cams may be circumferentially spaced about the first and second well assembly components.

The eccentric cams may be in a fixed location (e.g. fixed axially and radially) relative to the second well assembly component. The cams may each be rotatable between an engaged position (in which the cams are in contact with the first engagement surface and act to lock and/or preload the first well assembly component to the second well assembly component) and a disengaged position (in which the cams are not in contact with the first engagement surface and the first well assembly component to the second well assembly component are not locked together).

The locking device may be engaged and disengaged by engaging and disengaging first and second engagement surfaces. The engagement surfaces may be movable relative to each other between an engaged position and a disengaged position. The engaged position may be a position in which the engagement surfaces are in contact with each other and/or there is a preloaded connection between the engagement surfaces. The engaged position of the first and second engagement surfaces may be a position in which the first and second well assembly components are locked relative to each other. The disengaged position may be a position in which the engagement surfaces are not in contact with each other. The disengaged position of the first and second engagement surfaces may be a position in which the first and second well assembly components are not locked relative to each other.

The engagement surfaces may be engaged by rotating one or both of the engagement surfaces. For example, when the engagement surfaces are engaged and disengaged by rotation of the first and/or second engagement surfaces relative to each other the first engagement surface may be stationary and the second engagement surface rotated, the second engagement surface may be stationary and the first engagement surface rotated, and/or both engagement surfaces may be rotated relative to each other.

The rotation may be about a central axis, for example a vertical axis and/or a longitudinal axis of the well assembly components.

When the first and second engagement surfaces are rotated relative to each other (e.g. one or other or both engagement surfaces are rotated), the associated well assembly components may be stationary. In other words, when the engagement surfaces rotate relative to each other, the well assembly components may not rotate relative to each other. This may be because one or other or both of the engagement surfaces may be able to rotate relative to the well assembly component to which the engagement surface is associated. The first engagement surface being associated with the first well assembly component may mean that the first engagement surface is fixed to the first well assembly component in at least one direction. For example, the first engagement surface may be fixed relative to the first well assembly component in a radial and/or axial direction. However, the first engagement surface may be movable relative to the first well assembly component in a circumferential direction, i.e. the first engagement surface may be rotatable relative to the first well assembly component. This may for example be achieved by the first engagement surface being provided on one or more protrusions that are rotatable relative to the first well assembly component. For example, the one or more protrusions may extend through one or more circumferential slots in the first well assembly component. These slots may allow the first engagement surface to be rotatable relative to the first well assembly component whilst being fixed in the radial and/or axial directions.

The first engagement surface may be fixed to the first well assembly component in all directions, i.e. the first engagement surface may be immovable relative to the first well assembly component. In this case, if the first engagement surface is rotated, this may be achieved by rotating the first well assembly component. The first engagement surface may be attached to and/or integrally formed with the first well assembly component. For example, the first engagement surface may be the outer surface of the first well assembly component.

The second engagement surface being associated with the second well assembly component may mean that the second engagement surface is fixed to the second well assembly component in at least one direction. For example, the second engagement surface may be fixed relative to the second well assembly component in a radial and/or axial direction. However, the second engagement surface may be movable relative to the second well assembly component in a circumferential direction, i.e. the second engagement surface may be rotatable relative to the second well assembly component.

This may for example be achieved by the second engagement surface being provided on one or more protrusions that are rotatable relative to the second well assembly component. For example, the one or more protrusions may extend through one or more circumferential slots in the second well assembly component. These slots may allow the second engagement surface to be rotatable relative to the second well assembly component whilst being fixed in the radial and/or axial directions. The second engagement surface may be fixed to the second well assembly component in all directions, i.e. the second engagement surface may be immovable relative to the second well assembly component. In this case, if the second engagement surface is rotated, this may be achieved by rotating the second well assembly component. The second engagement surface may be attached to and/or integrally formed with the second well assembly component. For example, the second engagement surface may be the inner surface of the second well assembly component.

The first and/or second engagement surfaces may be rotated by an actuator. The actuator may be any known actuator such as a hydraulic actuator, an electric actuator and/or a mechanical drive screw etc. The actuator may be operated by a ROV and/or manually.

The actuator may be used to apply a force to create a preload between the engagement surfaces/well assembly components. Once the preload has been applied the actuator may be used to maintain the preload, e.g. the actuator may be locked in position to maintain the preload. Alternatively, once the preload has been applied by the actuator, the engagement surfaces may be locked relative to each other such that the actuator can be removed (and e.g. used on a different well assembly) whilst the preload between the engagement surfaces/components is maintained.

The first and/or second engagement surfaces, e.g. one or more first and/or second protrusions, may be fixed to, or part of, a connector, e.g. a ring. The ring may be a drive ring that is configured to move, e.g. rotate, the second engagement surface. For example when the second engagement surface is provided by outer protrusions, e.g. wedge blocks, the drive ring may rotate the plurality of outer protrusions together. The drive ring may be rotated by an actuator, for example a hydraulic actuator. Although referred to as a ring, this connector may not be limited to a ring shape (i.e. a shape with a circular cross section); other shapes may be used.

When connected to the second protrusions that form the second

engagement surface the ring may be provided circumferentially around the outside of the second well assembly component. The ring may be located above or below the second well assembly component and held in place axially and/or radially relative to the second well assembly component by a locking ring. The locking ring may allow the ring (e.g. drive ring) to rotate relative to the second well assembly component.

Rotating the engagement surfaces relative to each other (i.e. rotating one, or other or both of the engagement surfaces) may bring the engagement surfaces into contact with each other, i.e. close the gap between the engagement surfaces until there is zero clearance. This may lock the well assembly components relative to each other, i.e. provide a locking effect. Further rotation may build up a preload between the engagement surfaces. The lock and preload may be in a radial and/or axial direction. The geometry of the engagement surfaces may determine the direction of the locking effect and/or the magnitude and direction of the preload.

For example in the case that the engagement surfaces are provided by wedge blocks, the wedge blocks may have a radial thickness that varies in both the circumferential and axial directions to create a radial and axial locking effect and preload. The preload may be caused by elastic geometric changes in the engagement surfaces, e.g. elastic deformation of the engagement surfaces caused by further relative rotation of the engagement surfaces beyond the point at which the engagement surfaces are initially brought into contact with each other.

The locking device may create a preloaded connection, e.g. radial preloaded connection, between the engagement surfaces so as to create a preloaded connection (e.g. radial preloaded connection) between the first well assembly component and the second well assembly component.

It should be understood that a preloaded connection between engagement surfaces is not the same as zero clearance between the engagement surfaces. Engagement surfaces may have zero clearance, i.e. be in direct contact, without a preload being present between the surfaces. The engagement surfaces of the present locking device may have a preloaded connection in addition to having zero clearance (e.g. zero radial clearance).

An initial load, i.e. force, may be applied to create the preload. The locking device may be configured such that the preload is maintained after the initial load has been removed. When the engagement of the locking device is performed by an actuator, the actuator may remain in place once the initial load is removed in order to maintain the preload.

The engagement surfaces may be shaped so that there is a certain amount of radial and/or axial force exerted per degree of relative rotation between the engagement surfaces. The protrusions may each have a thickness (i.e. dimension in the radial direction) that increases or decreases in the circumferential direction.

The distance from the central axis of the well assembly components (e.g. at least the central axis of the first well assembly component) to the outer surface at the thickest part of the inner protrusions (that provide the first engagement surface) may be greater than the distance from the central axis of the well assembly components to the inner surface at the thickest part of the outer protrusions (that provide the second engagement surface). Additionally, the distance from the central axis of the well assembly components to the outer surface at the thinnest part of the inner protrusions may be smaller than the distance from the central axis of the well assembly components to the inner surface at the thinnest part of the outer protrusions. This means that as the protrusions of the first and second engagement surfaces are rotated relative to each other, they may overlap, at least at their thinnest parts, in a radial direction but as the rotation continues, they may engage and wedge, i.e. lock together and create a preload (e.g. radial preload).

The shape of the protrusions (e.g. wedges) may mean that when rotating the drive ring through a nominal distance the effective radial clearance between the two sets of protrusions may close and then a preload in a radial direction may build up between the protrusions. Owing to the fact that the protrusions may each be fixed radially to their respective well assembly component the preload between the protrusions may create a preloaded connection in the radial direction between the well assembly components.

Additionally the locking device may centralise the first well assembly component within the second well assembly component. This may be achieved because the action of the protrusions, which may be spaced circumferentially around their respective components, may centralise the first well assembly component relative to the protrusions of the second engagement surface, which in turn may be centralised to the second well assembly component.

Additionally or alternatively to the protrusions having a radial thickness that varies in the circumferential direction, the protrusions may have a radial thickness (i.e. dimension in the radial direction) that varies in the axial direction.

In the case that the thickness of the protrusions does not vary in the axial direction, the engagement surfaces may be parallel to the central axis. Such an arrangement may provide a radial centralisation, locking and/or radial pre-load force only as the engagement surfaces are moved relative to each other into the engagement position.

In the case that the thickness of the protrusions varies in the axial direction, the protrusions may engage to cause an axial (e.g. vertical) pre-load force.

The protrusions may be shaped so that as they are rotated in the

circumferential direction relative to each other about the axis of the well assembly components, the protrusions also move axially relative to each other thereby causing an axial preload relative to each other. Owing to the fact that the protrusions may be fixed relative to their respective components in the axial direction, this axial preload between the protrusions may also result in an axial preload between the first well assembly component and the second well assembly component.

As the drive ring and hence outer protrusions are rotated, the first and/or second well assembly component may need to be prevented from rotating. This is because the first and/or second well assembly component may have the tendency to rotate on engagement of the protrusions. The first and/or second well assembly component may be prevented from rotating by opposing the reaction torque, for example by using a component running tool or an anti-rotation key.

The engagement surfaces may be parallel to the central axis. In this arrangement when the engagement surfaces are rotated relative to each other only a radial force (i.e. locking and preload) is created between the engagement surfaces.

Alternatively, the engagement surfaces may not be parallel to the central axis. This may be achieved by the device having protrusions that may have a radial thickness that varies in both the circumferential and axial directions, e.g. they may have opposing helical engagement surfaces. This may result in both radial and axial reaction loads when the engagement surfaces (e.g. protrusions) are rotated relative to each other.

The geometry of the engagement surfaces (e.g. protrusions) may determine the load direction and magnitude induced between the engagement surfaces as they are rotated relative to each other, in the circumferential direction. For example, in the case that the protrusions are shaped to cause both a radial and axial load when rotated relative to each other the shape (e.g. helical angle) of the engagement surfaces may be varied (e.g. between 0 and 90 degrees) to generate the desired load direction and magnitude. The engagement surfaces may be shaped so that there is a certain amount of radial and/or axial force exerted per degree of relative rotation and/or force applied between the engagement surfaces.

The method may comprise determining the desired axial and/or radial preload between the first well assembly component and second well assembly component, and providing first and/or second engagement surfaces (e.g.

protrusions) that, when rotated relative to each other a given amount, provide the desired axial and/or radial preload between the first and second well assembly components.

The first well assembly component may be landed on a landing shoulder that is located within (or may be part of) the second well assembly component. The landing shoulder may set the axial height (i.e. the vertical alignment) of the first well assembly component relative to the second well assembly component. This may also set the axial alignment between the engagement surfaces, e.g. protrusions.

When the first well assembly component is landed on the landing shoulder the protrusions may be axially aligned (i.e. at the same height) but circumferentially offset. However, when the protrusions are rotated relative to each other they may at least circumferentially overlap such that they engage to cause the radial and/or axial load to be exerted between the components.

When the engagement surfaces are arranged to result in an axial force when rotated relative to each other, this axial force may be reacted by the landing shoulder so as to result in an axial preload between the first well assembly component and the second well assembly component.

The first and second engagement surfaces may be fixed radially and/or axially relative to the first and second well assembly components respectively. This may allow a radial and/or axial connection (i.e. lock and/or preload) between the well assembly components when the first and second engagement surfaces are radially and/or axially locked and/or preloaded relative to each other.

The first well assembly component may be landed on a landing surface (e.g. landing shoulder) within the second well assembly component. The locking device, if designed to provide an axial lock and/or preload between the two well assembly components, this may be reacted by the landing surface within the second well assembly component.

The locking device may comprise two, or more, sets of engagement surfaces that are spaced apart axially. This arrangement can provide an assembly with two, or more, actively engaged centralisation/locking mechanisms. In such an arrangement, it may not be necessary for there to be an internal landing surface for the first well assembly component within the second well assembly component.

This is because the second (e.g. lower) engagement surfaces may act as a reaction surface between which the components can be axially preloaded.

The locking mechanism may comprise separate engagement surfaces, for example separate sets of wedge blocks, for causing the radial preload and the axial preload.

The engagement surfaces may be arranged so that they do not contact each other during locating, e.g. landing, of one component within the other. To ensure the engagement surfaces do not interfere with each other during installation, the well assembly components may be oriented relative to each other such that the engagement surfaces are at different circumferential positions during locating. This may for example be achieved by alignment marks that are observed by an ROV or through alignment keys or any other known alignment device or method.

Thus the first and second engagement surfaces may be located relative to the first and second engagement surfaces respectively such that the well assembly components may be located within each other without the engagement surfaces interfering with each other during landing. For example, both the first and second engagement surfaces may extend over less than 50% of the circumference in the area between the outermost surface of the first engagement surface and the inner most surface of the second engagement surface. This means that the first and second engagement surfaces may be circumferentially offset during locating of the first component within the second component.

The force applied to the locking device to engage or disengage the locking device may be a lateral force rather than a vertical (i.e. axial) force. The locking device may be operable, i.e. the engagement surfaces may be movable, by operation from a lateral position rather than an overhead vertical position. The lateral and/or vertical positon may be a lateral and/or vertical position of or relative to the first and/or second well assembly component, i.e. to the side and/or above the first and/or second well assembly component. This may allow engagement and disengagement of the locking device even when there are components (e.g. the BOP and/or riser) above the location of the locking device. The locking device may be operable without overhead (i.e. axial) access to the locking device. The engagement surfaces may be modified to decrease or increase the friction therebetween. For example, the locking device may comprise one or more friction reducing solutions such as roller or a ball bearing type interface between at the engagement surfaces or friction reducing coatings on the engagement surfaces. If increased friction is desirable, one or more of the engagement surfaces may be roughened, e.g. serrated and/or coated with a friction increasing coating.

The present invention may ensure that the locking device is easily engageable and disengageable during installation and/or operation of the well.

Such an arrangement may also ensure that the locking device is operable from a lateral position rather than an overhead vertical position, which may allow engagement and disengagement of the locking device even when there are components (e.g. a BOP and/or a riser) above the location of the locking device.

Whilst the invention is described herein with reference to components of a well assembly, it could equally be used for locking two components that are not in a well assembly relative to each other, i.e. for locking components relative to each other that are not necessarily well assembly components.

Thus in a broader aspect, the present invention may provide a locking device for locking a first component to a second component, the locking device comprising: a first engagement surface associated with the first component; and a second engagement surface associated with the second well assembly component, wherein the engagement surfaces can be moved relative to each other between an engaged position and a disengaged position, and wherein the engagement surfaces can be engaged and disengaged by rotation of the first and/or second engagement surfaces relative to each other.

In another broader aspect, the present invention may provide a method of locking a first component to a second component, the method comprising the steps of: providing a locking device with a first engagement surface associated with the first component and a second engagement surface associated with the second component; and rotating the first and/or second engagement surfaces relative to each other from a disengaged position to an engaged position.

The invention according to these broader aspects may have one or more or all of the above described features, including optional features, that are described above in relation to the first and/or second aspects. Certain preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a plan view of a partial cross section through a locking device;

Figure 2 is a side view of the locking device of figure 1 ;

Figure 3 is a perspective partial cross section of the locking device of figure

1 ;

Figure 4 is an enlargement of part of the locking device of figure 3;

Figure 5 is an enlargement of part of an alternative locking device;

Figure 6 is a perspective view of an alternative locking device;

Figure 7 is an enlargement of part of the locking device of figure 6; and

Figure 8 is a perspective cross-section of an alternative locking device.

Figures 1 , 2 and 3 show a locking device 1 for locking a conductor housing 2 within a conductor housing receptacle 4. These maybe components of a subsea well assembly. The conductor housing receptacle 4 may be attached to, or part of, a support structure (not shown), such as a suction anchor, that is fixed to the seabed. A high pressure wellhead housing 5 may be landed in the conductor housing 2.

Whilst the locking device 1 is specifically illustrated as being used to lock a conductor housing 2 within a conductor housing receptacle 4, the locking device 1 may be used to lock other components, e.g. other well assembly components together. This may for example be for locking other well tubulars together and/or for locking mounted equipment such as a BOP and/or Christmas tree onto a wellhead.

The locking device 1 comprises a first engagement surface and a second engagement surface. In this embodiment the first engagement surface is provided by a plurality of protrusions in the form of inner wedge blocks 6 and the second engagement surface is provided by a plurality of protrusions in the form of outer wedge blocks 8. Each inner wedge block 6 may correspond to an outer wedge block 8 such that the number of inner wedge blocks 6 is equal to the number of outer wedge blocks 8.

The inner wedge blocks 6 are associated with the conductor housing 2 and the outer wedge blocks 8 are associated with the conductor housing receptacle 4. The inner wedge blocks 6 are located at spaced locations around the circumference of the conductor housing 2. The outer wedge blocks 8 are located similarly at spaced locations around the circumference of the conductor housing receptacle 4.

In this embodiment there are four inner wedge blocks 6 spaced 90 degrees apart, and four outer wedge blocks 8 spaced 90 degrees apart. The number of wedge blocks 6, 8 in each set of wedge blocks will depend on factors such as the precise design of the locking device and the load requirements.

The inner wedge blocks 6 may be fixed on to the outer surface of the conductor housing 2. This may be achieved by the inner wedge blocks 6 being bolted, glued, welded, or fixed by any other known means to the conductor housing 2 or by the inner wedge blocks 6 being an integral part of the conductor housing 2 (e.g. machined into the outer surface of the conductor housing 2).

When the inner wedge blocks 6 are separate parts fixed to the conductor housing 2, they may be designed to be fixed onto existing designs of conductor housings.

The inner wedge blocks 6 may be in a fixed location relative to the conductor housing 2, i.e. the inner wedge blocks 6 may not be able to move relative to the conductor housing 2.

The outer wedge blocks 8 may be in a fixed location radially and/or axially relative to the conductor housing receptacle 4. However, the outer wedge blocks 8 may be movable circumferentially relative to the conductor housing receptacle 4. This may allow the outer wedge blocks 8 to be moved circumferentially relative to the inner wedge blocks 6 between an engaged and disengaged position even if the conductor housing 2 and the conductor housing receptacle 4 are not rotated relative to each other.

The arrangement, e.g. circumferential extent, of the of the inner wedge blocks 6 and the arrangement, e.g. circumferential extent, of the outer wedge blocks 8 may allow the conductor housing 2 to be installed within the receptacle 4 without being prevented by the wedge blocks 6, 8.

For example each set of wedge blocks may be located around the circumference with sufficient intervals between adjacent wedge blocks to allow the conductor housing 2 to be lowered into the conductor housing receptacle 4 without the wedge blocks 6, 8 preventing the installation. This may be achieved by the inner wedge blocks 6 on the conductor housing 2 landing in between the outer wedge blocks 8 associated with the conductor housing receptacle 4.

The outer wedge blocks 8 are fixed to, or part of, a drive ring 10 that is connected to an actuator 12. The wedge blocks 6, 8 may be moved between engaged and disengaged positions by rotation of the drive ring 10 about the central axis of the components. The drive ring 10 may be rotated by means of an actuator 12. In this embodiment the actuator 12 is a hydraulic actuator, although the actuator 12 could be any other known actuator such as a mechanical drive screw. The actuator may be operated by an ROV and/or an electric motor etc.

The locking device 1 may comprise a plurality of actuators. For example, the outer wedge blocks 8 may each be rotated about the central axis by a separate actuator. In this case the drive ring 10 may not be required or present.

Rotation of the drive ring 10 in a first direction (e.g. clockwise) may move the locking device 1 from a disengaged position to an engaged position and rotation of the drive ring 10 in a second opposite direction (e.g. antic-clockwise) may move the locking device 1 from an engaged position to a disengaged position.

The drive ring 10 is provided circumferentially around the outside of the conductor housing receptacle 4 and the outer wedge blocks 8 each extend through circumferential slots, i.e. access windows, in the wall of the conductor housing receptacle 4.

The wedge blocks 6, 8 each have a thickness (i.e. dimension in the radial direction) that increases or decreases in the circumferential direction.

The distance from the central axis of the assembly to the outer surface at the thickest part of the inner wedge blocks 6 is greater than the distance from the central axis of the assembly to the inner surface at the thickest part of the outer wedge blocks 8. Additionally, the distance from the central axis of the assembly to the outer surface at the thinnest part of the inner wedge blocks 6 is smaller than the distance from the central axis of the assembly to the inner surface at the thinnest part of the outer wedge blocks 8. This means that as the wedge blocks 6, 8 are rotated relative to each other, they can overlap, at least at their thinnest parts, in a radial direction but as the rotation continues, they engage and wedge, i.e. lock together and create a preload.

The wedge shape of the wedge blocks 6, 8 means that when rotating the drive ring 10 through a nominal distance the effective radial clearance between the two sets of wedges will close and then a preload in a radial direction will build up between the wedge blocks 6, 8. Owing to the fact that the wedge blocks 6, 8 are each fixed radially to their respective well assembly component 2, 4, the preload between the wedge blocks 6, 8 will create a preloaded connection in the radial direction between the conductor housing 2 and the conductor housing receptacle 4. Additionally the locking device 1 will centralise the conductor housing 2 within the conductor housing receptacle 4. This is achieved because the action of the wedge blocks 6, 8, which are spaced circumferentially around their respective components 2, 4, will centralise the conductor housing 2 relative to the drive ring 10, which in turn is centralised to the conductor housing receptacle 4.

Additionally or alternatively to the wedge blocks 6, 8 having a radial thickness that varies in the circumferential direction, the wedge blocks 6, 8 may have a radial thickness (i.e. dimension in the radial direction) that varies in the axial direction.

In the case that the thickness of the wedge blocks 6, 8 does not vary in the axial direction, the engagement surfaces may be parallel to the central axis. Such an arrangement will provide a radial centralisation, locking and radial pre-load force only as the engagement surfaces are moved relative to each other into the engagement position.

In the case that the thickness of the wedge blocks 6, 8 varies in the axial direction, the wedge blocks 6, 8 may engage to cause an axial (e.g. vertical) pre load force.

The wedge blocks 6, 8 may be shaped so that as they are rotated in the circumferential direction relative to each other about the axis of the well assembly, the wedge blocks 6, 8 also move axially relative to each other thereby causing an axial preload relative to each other. Owing to the fact that the wedge blocks 6, 8 are fixed relative to their respective components 2, 4 in the axial direction, this axial preload between the wedge blocks 6, 8 also results in an axial preload between the conductor housing 2 and the conductor housing receptacle 4.

As the drive ring 10 and hence outer wedge blocks 8 are rotated, the conductor housing 2 may need to be prevented from rotating. This is because the conductor housing 2 may have the tendency to rotate on engagement of the wedge blocks 6, 8. The conductor housing 2 may be prevented from rotating by opposing the reaction torque, for example by using the conductor housing running tool or an anti-rotation key.

Figure 4 shows an arrangement with wedge blocks 6, 8 having engagement surfaces parallel to the central axis. In this arrangement when the wedge blocks 6, 8 are rotated relative to each other only a radial force (i.e. locking and preload) is created between the wedge blocks 6, 8. Figure 5 shows an arrangement with wedge blocks 6, 8 having engagement surfaces that are not parallel to the central axis. These wedge blocks 6, 8 have a radial thickness that varies in both the circumferential and axial directions, i.e. they have opposing helical engagement surfaces. This results in both radial and axial reaction loads when the wedge blocks 6, 8 are rotated relative to each other.

The geometry of the engagement surfaces may determine the load direction and magnitude induced between the engagement surfaces as they are rotated relative to each other, in the circumferential direction. For example, in the case that the wedge blocks 6, 8 are shaped to cause both a radial and axial load when rotated relative to each other the shape (e.g. helical angle) of the engagement surfaces may be varied (e.g. between 0 and 90 degrees) to generate the desired load direction and magnitude.

The engagement surfaces may be shaped so that there is a certain amount of radial and/or axial force exerted per degree of relative rotation between the engagement surfaces.

The conductor housing 2 is landed on a landing shoulder 14 that is located within (or may be part of) the conductor housing receptacle 4. The landing shoulder 14 sets the axial height (i.e. the vertical alignment) of the conductor housing 2 relative to the conductor housing receptacle 4. This may also set the axial alignment between the wedge blocks 6, 8.

When the conductor housing 2 is landed on the landing shoulder 14 the wedge blocks 6, 8 may be axially aligned (i.e. at the same height) but

circumferentially offset. However, when the wedge blocks 6, 8 are rotated relative to each other they may at least circumferentially overlap such that they engage to cause the radial and/or axial load to be exerted between the components 2, 4 as described above.

When the wedge blocks 6, 8 are arranged to result in an axial force when rotated relative to each other, this axial force may be reacted by the landing shoulder 14 so as to result in an axial preload between the conductor housing 2 and the conductor housing receptacle 4.

Figures 6 and 7 show a locking device T that is similar to the locking device 1 shown in Figures 1 to 3. However, rather than the outer wedge blocks 8 extending through circumferential slots in the conductor housing receptacle 4, the drive ring 10 is located on top of the conductor housing receptacle 4. The drive ring 10 is fixed in the axial and radial directions relative to the conductor housing receptacle 4 by a lock ring 16 that is fixed, for example bolted, to the top of the conductor housing receptacle. In the locking device 1’ the inner wedge blocks 6 are located higher on the conductor housing 2 compared to their position in locking device 1 , so that the engagement between the wedge blocks 6, 8 can still occur.

Although not shown in any of the figures, the locking device 1 could be located below the conductor housing receptacle 4. The only requirement is that the engagement surfaces be fixed relative to the components at least in one direction, e.g. the radial and/or axial direction.

Although the locking devices shown in Figures 1 to 7 only have engagement surfaces (i.e. wedge blocks 6, 8) at a single axial height, the locking device 1 could have engagement surfaces, i.e. wedge blocks, at a second axial height.

In the case that two (or more) sets of wedge blocks are present at different axial heights, the assembly may not comprise the landing shoulder 14.

Whilst the drive ring 10 in the illustrated embodiments is external of the conductor housing receptacle 4, it could alternatively be located internally of the conductor housing receptacle. In this case there may be an access window/slot through the wall of the conductor housing receptacle 4 that permits the drive ring 10 to be rotated. Alternatively or additionally, there may be some form of linkage from the drive ring 10 up to the top of the structure that permits the drive ring 10 to be rotated.

The relative movement between the engagement surfaces may be achieved by rotating the conductor housing 2 about its central axis. This may be achieved for example using the running tool for the conductor housing 2 during installation.

In the case that the conductor housing 2 is rotated, the outer wedge blocks 8 may be fixed relative to, or an integral part of, the conductor housing receptacle 4. In this case the drive ring 10 and actuator 12 may not be required or present.

The engagement surfaces may be provided by means other than wedge blocks. For example the engagement surfaces may be part of a radially outward facing surface of the first component and part of a radially inward facing surface of the second component.

One or both of the components may have a surface that is elliptical such that when the two components are rotated relative to each other engagement occurs. For example the conductor housing may have an external elliptical surface and/or the conductor housing receptacle and/or the drive ring if present may have an internal elliptical surface. Another alternative locking device is illustrated schematically by Figure 8. This locking device comprises a plurality of cam-shaped disks 18. The cam-shaped disks 18 are fixed relative to the conductor housing receptacle 4 in the axial and radial directions. Each of the cam-shaped disks 18 can be rotated about its own eccentric axis 20 between an engaged position and a disengaged position. In the engaged position the surface of the cam-shaped disk 18 engages with the external surface of the conductor housing 2. The plurality of cam-shaped disks 18 are spaced circumferentially around the conductor housing 2 and can operate together to lock and/or radially preload the conductor housing 2 within the conductor housing receptacle 4.

The above described locking devices may be used with components other than well tubulars, e.g. the conductor housing and conductor housing receptacle as specifically described above. For example, they could be used to lock well assembly components such as a well element such as a BOP to a support structure, e.g. a template or suction anchor.

In the case that the locking device is used to lock a well element, such as a BOP, to a support structure, the drive ring could be provided on the well element. The drive ring may thus have the wedge blocks with an outward facing engagement surface that engage with inwardly facing engagement surfaces on the support structure.