Patent ID: 12228001

DETAILED DESCRIPTION

In the following description, various embodiments will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

Rigid locking of certain components in a sealing system can help to provide control of the components when used together. For casing hangers in a wellhead, rigid locking of components can be useful to prevent forces from thermal expansion and pressure acting on the casing hanger to cause movement of the components upwards inside the wellhead. For example, in one embodiment of the present technology, certain components may be rigidly locked together so there is no gap between the components. Such an arrangement may be beneficial because a gap may permit a shuttling effect when the seal is under pressure, which can lead to failure of other components in the sealing system. When an interface, between rigidly locked components is too tight, one or more of the components may disengage from the other. In an example, if the interface between two components consists of two flat, smooth surfaces abutting at a tapered angle, the forces acting on the components can cause a wedge action. In other words, longitudinal forces acting on the interface through the tapered plane can have a transverse component. The transverse component of the force may act to disengage the components, and to unlock the components. Further, the transverse and longitudinal forces can cause the sealing system to shuttle, wear, and potentially fail. The upshot is that when interfacing surfaces between components are flat, tolerances and setting position may not permit a consistent setting force to rigidly lock the components. Either a gap can remain between the components where the rigid locking is intended, which prevents preload and permits shuttling, or the gap must be closed using a press-fit, which can be undesirable for other reasons.

Systems and methods in accordance with various embodiments of the present disclosure may overcome one or more of the aforementioned and other deficiencies by reshaping interface surfaces between components. In particular, a mechanical connector for transitions between mechanical locking applications is disclosed. The mechanical connector includes a first surface with stepped tapers for a mechanically loaded connection to a mating surface on an adjacent component. The mechanical connector can further include second surface having an engagement portion for supporting the mechanically loaded connection. In an example, the stepped tapers can form a ratcheting surface with an actuating member that may be part of a system with the mechanical connector for providing a pedestal or locked surface over which sealing or other components may be fixed. For example, components, systems, and methods of the present disclosure allow for preloaded mechanical connections (e.g. between an actuator ring and a lockdown ring) that are able to tolerate movements from forces in transitions between mechanical locking systems using stepped tapers.

A further intent of the present disclosure is to create the aforementioned pedestal or supporting structure over which components, including sealing systems may be placed, so that the pedestal offered by the combination of the mechanical connector and its mating surface prevents relative movement of the sealing system. This enables the sealing system or any associated components to be accurately placed, and enables the sealing system or any associated components to stay in position. Furthermore, adjustability in setting depth of the mechanical connector can be achieved using the stepped tapers for the mechanical connector and of the mating surface, while limiting any upward back-driving forces on the mating surface.

Various other functions can be implemented within the various embodiments as well, as discussed and suggested elsewhere herein.

FIG.1illustrates an example of wellbore system100with a casing hanger applied in a mandrel (e.g., wellhead housing, Christmas tree, or blow-out preventer), in which aspects of the present disclosure may be applied. However, a person of ordinary skill reading the present disclosure will be able to recognize variations of the present disclosure for other mechanical locking applications than wellbore applications. In present example of the wellbore system100, region116may represent a subsea or offshore formation. A low pressure wellbore housing106may include a wellhead112, and tubing or casing hanger114, which may be moved into place with a running tool110. External wellhead support structure of the low pressure wellbore housing106(e.g., conductor casing) supports the wellhead112and additional casings within the wellhead. Pipe string is fed into the wellbore to approach the required depth for placement and drilling. For example running string or landing string108may be used to place the hanger114in its position in the wellhead112. In addition, a platform104may be provided, where equipment in module102is provided for power, communication, and monitoring between the wellhead112and external structures. A person of ordinary skill would recognize, from the present disclosure, the requirements to enable a stable and rigid locking of the movable portions in the tubing hanger, and a corresponding mating inner diameter of a corresponding mating surface.

A person of ordinary skill reading the present disclosure would recognize that the equipment shown inFIG.1may further include a power unit for providing power through the pipe string108into the wellbore, but also for controlling the drilling into the wellbore. The power unit may be located near the pipe string108, at about the center of the platform104. In addition, the wellbore system100may include a communications outpost for providing communications to other units, such as a subsea electronics module (SEM). Furthermore, in subsea implementations, the platform104can be located at the surface of the sea, while the wellhead112and the SEM can be located in some embodiments subsea. The power unit may be coupled with the communications to allow for redundancy and singular cable transmission through the wellhead while providing sufficient room for drilling via rotation of the appropriate pipe string108.

FIG.2Aillustrates an example system200of a mechanical connector204, in this case a lockdown ring, having stepped tapers204A. Area210between hanger206and wellhead housing208(or any intermediate components, such as a slick bore) require a supporting structure where components are rigidly locked together. In an example, such a supporting structure with rigid locking between the hanger206and the wellhead housing208may be accomplished by a mechanical connector204for mechanical locking applications. A first surface of the mechanical connector204includes stepped tapers204A for a mechanically loaded connection to a mating surface, illustrated as corresponding stepped tapers202A of mating surface of actuating member202. Further, a second surface having one or more engagement portions204B is provided, illustrated here as protrusions from the surface opposing the stepped tapers204A. The one or more engagement portions204B support the mechanically loaded connection by engaging in one or more indentations208A in the wellhead housing208.

FIG.2Billustrates a further example system250of the mechanical connector204ofFIG.2Ain engagement, using its surfaces having stepped tapers, with associated mating surfaces having corresponding stepped tapers, in accordance with an aspect of this disclosure. In an example,FIG.2Aillustrates a landing stage or phase where components204and202are landed within area210.FIG.2Billustrates a locked phase where a rigid connection is made so that the components204,202are able to support substantial load at a position that may be predetermined for the example system250.FIG.2Billustrates that the stepped tapers are fully engaged with the corresponding stepped tapers so that substantially all parts of the stepped tapers204A of the mechanical connector204engage the corresponding parts of the stepped tapers202A of the actuating member202. In such a configuration, the mechanical connector204is rigidly locked in position relative to the actuating member202and against the rigid members206,208. The system250then behaves like it has an optimally-sized straight-interface actuating member and mechanical connector. The actuating member is fully self-locked and cannot back out during operation due to applied forces on the system250. The combination of flats and steps in the stepped tapers causes the mechanical connector and the actuating member to ratchet as the actuating member urges the mechanical connector to engage.

FIG.2Cillustrates an in-depth view270of the mechanical connector204ofFIG.2Bin engagement (e.g., locked stage or phase), using its surfaces having stepped tapers204A, with associated mating surfaces having corresponding stepped tapers202A, in accordance with an aspect of this disclosure. Further,FIG.2Cillustrates that the mechanical connector204includes a bottom surface204D for resting the mechanical connector on a lower member or on a surface206A provided in the hanger206. In the example system200,250,270, the first surface is part of a lockdown ring and the mating surface is part of an actuator ring. The lockdown ring and the actuating ring are positioned between the wellhead housing and the hanger to support an annular seal (not shown). The mechanically loaded connection formed between the mechanical connector204, the actuating member202, and the rigid members206,208extends laterally, illustrated by reference axis212, from the first surface of the mechanical connector204(and also an interface formed by the first surface and a surface of the actuating member202). A person of ordinary skill reading the present disclosure would recognize that the lateral direction of reference axis212of the mechanically loaded connection is not necessarily perpendicular to the interface of the mechanical connector204and the actuating member202, but is perpendicular to an axis of the hanger and wellhead housing and/or parallel to mating surface204D. As such, lateral is a reference to sideways loading caused by wedging the mechanical connector204with the actuating member202between the hanger and the wellhead housing.

In application, the mechanical connector204can be placed in area210between the rigid members206,208. The mechanical connector204may be first loosely engaged with the actuating member202before being placed in the area210. Alternatively, the actuating member202may be separately placed in the area210, subsequent to the placement of the mechanical connector204. The actuating member202is illustrated inFIGS.2A-2Cas having corresponding stepped tapers202A. The actuating member202may be influenced to slide against the stepped tapers in a ratcheting action. The actuating member202includes an opposing mating surface for tagging or engaging the hanger206or any rigid member otherwise provided in the area210. In an example, a load may be applied to the actuating member202at its upper rigid portion so that each of the corresponding stepped tapers202A ratchets against each of the stepped tapers204A of the mechanical connector204. As this happens, one or more protrusions204B of a second surface of the mechanical connector204engage deeper into one or more indentations208A of the rigid member208. This process locks the mechanical connector204between the rigid members206,208by virtue of the stepped tapers204A being aligned substantially fully with the corresponding stepped tapers202A. As such, the actuating member202locks with the mechanical connector204against the rigid members206,208by a mechanically loaded connection extending laterally from an interface of the stepped tapers and the corresponding stepped tapers. The ratcheting action of ratcheting surfaces (i.e., the stepped tapers and the corresponding stepped tapers) prevents return movement of the mechanical connector or the mating surface of the actuating member202.

FIG.3Aillustrates an example system300of a mechanical connector308having stepped tapers that correspond to tapers on a wellhead connector302, in accordance with an aspect of this disclosure. In the example, the wellhead system300includes an adapter302to be connected with mandrel304, with intermediate components omitted to focus on the rigid locking or supporting structure features of the present disclosure. The mandrel304may be a wellhead housing, a Christmas tree arrangement, or a blow-out preventer. Further, this and other aspects may be combined or modified in any way as described in the present disclosure and that is readily understood by a person of ordinary skill in the art. The person of ordinary skill reading the present disclosure would also recognize the components omitted, and would recognize modifications required to apply the present rigid locking and supporting structure features.

When the wellhead connector302is lowered on a riser string over a previously installed mandrel304, an inner diameter of a lower insert318fits over an outer diameter of the mandrel304at a point of engagement, as illustrated. After wellhead connector302lands on the rim of the mandrel304, hydraulic fluid pressures piston cylinder312A to stroke piston312B. Cam ring308in turn pushes dogs306radially into engagement with mandrel grooves314. A large downward preload force is applied to the rim of the mandrel304as a result of teeth320of dogs306engaging grooves314. A stop plate322limits the downward travel of cam ring308to prevent applying too much preload to an upper rim portion of the mandrel304. Cam ring308has an inner diameter324that engages outer surfaces of the dogs306. The present disclosure enables rigid locking of the cam ring308with the dogs306, thereby forming a locking member.FIG.3Billustrates an in-depth view350of the rigid locking310of a mechanical connector, such as the cam ring308ofFIG.3A, in engagement with associated mating surfaces, such as of one or more dogs306, in accordance with an aspect of this disclosure. As such, a first surface308A of the mechanical connector of example system300,350is part of a cam ring308and the mating surface306A is part of a locking member306. The cam ring308and the locking member306are located in an area between the mandrel304and an outer wall316of the wellhead connector302. The stepped tapers308B of the mating surface308A may be a portion of the mating surface308A.

As previously noted, the mechanical connector and/or an associated actuating member may be applied in any mechanical application requiring rigid locking and or a supporting structure; and the above examples of a hanger lockdown and wellhead connector are only provided as non-limiting examples.FIG.4illustrates an example400of a mechanical connector406B having stepped tapers in another application of a wellhead connector having a cam interface, in accordance with an aspect of this disclosure. In example400, an actuating member406A with associated stepped tapers is provided in section406. The actuating member406A is rigidly locked with the lockdown ring406B, between a high pressure wellhead housing402and a low pressure wellhead housing404. The mechanical connector406B is provided with a first surface having stepped tapers and a second surface having one or more engagement portions, in a similar manner as inFIGS.2B,2C. The stage or phase illustrated inFIG.4is a locked phase for the mechanical connector406B and the actuating member406A between rigid members404,402. Furthermore, the mechanical connector406B includes a bottom surface for supporting the mechanical connector406B in a stable manner, on a shoulder of the rigid member404as illustrated, during the locking phase. When locked, example400represents a rigid locking achieved between high and low pressure cam interfaces for wellhead connectors. In a similar manner, mechanical connectors with stepped tapers and associated actuating members with corresponding stepped tapers may be used for tieback connectors, in riser joint connectors, pipeline connectors, and in flowline connectors (for trees, for pipeline end manifolds (PLEMs), and for pipeline end terminations (PLETs), etc.)

FIG.5illustrates a process flow500for a method of using a mechanical connector including stepped tapers, in accordance with aspects of this disclosure. In sub-process502of process500, a mechanical connector having stepped tapers is placed in an area between rigid members. As noted in the above embodiments, which may be combined or modified by a person of ordinary skill reading the present disclosure in any applicable manner, the mechanical connector may be engaged loosely with an actuating member and/or other intermediate or overlying components. As such, the placement of the mechanical connector in sub-process502does not preclude placement of the actuating member and/or other intermediate or overlying components concurrently or subsequently. In sub-process504, the actuating member having corresponding stepped tapers is inserted into the area. As noted with respect to the sub-process502, the placing of the mechanical connector may be concurrent with the actuating member, but as the actuating member is above or below, relatively, to the mechanical connector, the sub-process504may be applied as automatically following from sub-process502.

An influencing of the actuating member is performed via sub-process506so that the actuating member begins to engage the stepped tapers. As in the system examples, the corresponding stepped tapers of the actuating member begin to mate against the stepped tapers of the mechanical connector to cause a ratcheting action. Sub-process508can first ensure that the actuating member and the mechanical connector are engaged so that the actuating member can be further influenced to mate and lock with the mechanical connector by virtue of the corresponding stepped tapers of the actuator ring being locked flat-to-flat against the stepped tapers of the mechanical connector. The process500, in an aspect, enables control for a force of installation that influences the engagement and subsequent mating of the actuating member and the mechanical connector; and enables control of a preload of the mechanically loaded connection. In an example, the force may be predetermined as a theoretical value and then a force, in application, may be compared to the theoretical value to ensure that the mechanically loaded connection is achieved. In a configuration where the mechanically loaded connection is achieved, the supporting structure in the mechanically loaded connection is both locked and preloaded. As such, sub-process508may also include verification to more than an engagement, for e.g., that the actuating member is locked and preloaded with the mechanical connector.

A determination is made, in sub-process510, that the actuating member is engaged with the mechanical connector between the rigid members, and a further force may be applied to mate the surfaces and cause a mechanically loaded connection extending laterally with respect to an interface of the stepped tapers and the corresponding stepped tapers. The mechanically loaded connection extending laterally may be also taken as in a direction perpendicular to an axis of the area or radially about the axis. For example, the mechanically loaded connection may be also taken as in a direction that is radially outwards and downwards, as partly illustrated inFIG.2C, because of an embodiment where the mechanical connector may pivot to engage its protrusions with the indentations of the housing. The axis of the area is longitudinal, along a vertical bore axis in most applications, versus a latitudinal or side-to-side axis along which the mechanically loaded connection is achieved.

The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims. Further, any of the many embodiments disclosed here may be combined by a person of ordinary skill using the present disclosure to understand the effects of such combinations.