Patent Application
20210189824
The present disclosure is directed to a subsea hydrocarbon production system which includes a tubing hanger that is installed in a wellhead or the like. More particularly, the disclosure is directed to a coil spring arrangement which functions to automatically adjust the vertical position of the tubing hanger load shoulder so that the vertical distance between the load shoulder and the tubing hanger lockdown mechanism is the same as the vertical distance between the seat on which the load shoulder is landed and the wellhead locking profile which the lockdown mechanism is configured to engage.
Subsea hydrocarbon production systems typically include a wellhead which is positioned at the upper end of a well bore. The wellhead comprises a central bore within which a number of casing hangers are landed. Each casing hanger is connected to the top of a corresponding one of a number of concentric, successively smaller casing strings which extend into the well bore, with the uppermost casing hanger being connected to the innermost casing string. After the innermost casing string is installed, a tubing string is run into the well bore. The top of the tubing string is connected to a tubing hanger having a downward facing circumferential load shoulder which lands on a seat formed at the top of the uppermost casing hanger. In certain tubing hangers, the load shoulder is formed on a load nut which is threadedly connected to the tubing hanger body.
The tubing hanger is usually secured to the wellhead using a lockdown mechanism, such as a lock ring or a number of locking dogs, both of which comprise a number of axially spaced, circumferential locking ridges. The locking dogs are supported on the tubing hanger body and are expandable radially outwardly into a locking profile formed in the bore of the wellhead, such as a number of axially spaced, circumferential locking grooves, each of which is configured to receive a corresponding locking ridge. In order to ensure that the tubing hanger is properly locked to the wellhead, the vertical distance between the load shoulder and the locking dogs must be the same as the vertical distance between the seat and the locking profile, which is commonly referred to as the wellhead space-out. In this regard, the term “the same as” should be interpreted to mean that the vertical distance between the seat and the locking profile is such that the locking ridges can fully engage their corresponding locking grooves.
In tubing hangers in which the load shoulder is formed on a load nut that is threadedly connected to the tubing hanger body, the vertical distance between the load shoulder and the locking dogs can be adjusted by rotating the load nut relative to the tubing hanger body. Thus, once the wellhead space-out is determined, the load nut can be rotated until the vertical distance between the load shoulder and the locking dogs is the same as the wellhead space-out.
In the prior art, a lead impression tool (LIT) is sometimes used to measure the wellhead space-out. In subsea wellheads, the LIT is lowered on a drill string and landed on the seat. The LIT is then hydraulically actuated to press typically three circumferentially spaced lead impression pads into the locking profile. After the impressions are taken, the LIT is retrieved to the surface and mounted on a storage/test stand, which is then manually adjusted to match the lead impression tool. The tubing hanger is then mounted on the storage/test stand and the load nut is adjusted until the vertical distance between the load shoulder and the locking dogs is the same as the wellhead space-out.
Although the LIT provides a useful means for determining the wellhead space-out, the time required to run and retrieve the LIT can be relatively long, especially in deep water. Also, setting the tubing hanger on the storage/test stand and adjusting the load nut can be a time consuming process and is dependent on human interpretation.
In accordance with one embodiment of the present disclosure, a tubing hanger assembly is provided that comprises a body which has an annular outer surface; a lockdown feature which is located on the body; a load nut which is threadedly connected to the body, the load nut comprising a downward facing load shoulder; and a torsion spring member which includes a first end that is connected to the tubing hanger and a second end that is connected to the load nut. In operation the torsion spring member rotates the load nut to thereby move the load nut axially relative to the body. In this manner, an axial distance between the load shoulder and the lockdown feature is adjustable.
In accordance with one aspect of the disclosure, the tubing hanger assembly further comprises means for selectively preventing the load nut from rotating relative to the body. For example, the means for selectively preventing the load nut from rotating relative to the body may include a latching mechanism which is positioned on one of the tubing hanger body and the load nut. In this example, the latching mechanism may comprise a latch member which is biased into engagement with a corresponding groove formed on the other of the tubing hanger body and the load nut.
In accordance with another aspect of the disclosure, the means for selectively preventing the load nut from rotating relative to the body further comprises a de-latching mechanism which is positioned on the other of the tubing hanger body and the load nut. For example, the de-latching mechanism may comprise a rod which includes a first end that is located proximate a bottom of the groove and a second end that extends a distance past the load shoulder, such that application of an axial force to the second end will cause the first end to displace the latch member from the groove.
In accordance with a further aspect of the disclosure, the latching mechanism is positioned on the tubing hanger body and the de-latching mechanism is positioned on the load nut. In this embodiment, the de-latching mechanism may comprise a rod which includes a first end that is located proximate a bottom of the groove and a second end that extends a distance past the load shoulder, such that application of an axial force to the second end will cause the first end to displace the latch member from the groove.
In accordance with yet another aspect of the disclosure, the tubing hanger assembly is configured to be installed in a wellhead which comprises a central bore in which a casing hanger is positioned, the load shoulder being configured to land on a seat which is formed on the casing hanger to thereby support the tubing hanger in the wellhead. In this embodiment, the central bore may comprise a locking profile and the lockdown feature may comprise a number of locking dogs which are supported on the body and are expandable into the locking profile to thereby secure the tubing hanger assembly to the wellhead. Further, during installation of the tubing hanger assembly, the torsion spring member may rotate the load nut until a distance between the load shoulder and the locking dogs is the same as a distance between the seat and the locking profile. Alternatively, the torsion spring member may rotate the load nut until a distance between the load shoulder and the locking dogs is the same as a distance between the seat and the locking profile after the locking dogs have been preloaded against the locking profile.
The present disclosure is also directed to method for installing a tubing hanger in a wellhead. The wellhead comprises a first tubing hanger lockdown feature and a central bore in which a casing hanger is positioned, and the tubing hanger comprises a second tubing hanger lockdown feature which is configured to engage the first tubing hanger lockdown feature, an annular body, and a load nut which is threadedly connected to the body and which includes a downward facing load shoulder which is configured to land on a seat that is formed on the casing hanger. The method comprises the steps of lowering the tubing hanger into the wellhead and then adjusting the axial position of the load nut until an axial distance between the load shoulder and the second tubing hanger lockdown feature is the same as a second axial distance between the seat and the first tubing hanger lockdown feature. In this embodiment, the step of adjusting the axial position of the load nut is performed by releasing a torsion spring member which is operatively engaged between the body and the load nut. Thus, the torsion spring member rotates the load nut and causes the load nut to move axially downward relative to the body.
In accordance with one aspect of the disclosure, the method further comprises the step of engaging the first and second tubing hanger lockdown features to thereby secure the tubing hanger to the wellhead.
In accordance with another aspect of the disclosure, the step of engaging the first and second tubing hanger lockdown features is performed before the step of adjusting the axial position of the load nut.
In accordance with yet another aspect of the disclosure, the step of adjusting the axial position of the load nut is performed after the first and second tubing hanger lockdown features have been preloaded against each other.
Thus, in one illustrative embodiment of the disclosure, the tubing hanger and adjustable load nut assembly enables the vertical spacing between the load shoulder and the locking dogs to be adjusted in real time as the tubing hanger is landed and locked in the wellhead. As a result, the need to measure the wellhead space-out and adjust the position of the load nut before the tubing hanger is run into the wellhead is eliminated, which greatly reduces the time required to install the tubing hanger.
These and other objects and advantages of the present disclosure will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers may be used to denote similar components in the various embodiments.
An example of a prior art wellhead system is shown in
The tubing hanger 18 is secured to the wellhead 10 using a suitable lockdown mechanism. In the example shown in
As discussed above, in order to ensure that the tubing hanger 18 is properly locked to the wellhead 10, the vertical distance between the load shoulder 24 and the locking dogs 26 must be the same as the vertical distance between the seat 16 and the locking profile 32 (i.e., the wellhead space-out). The wellhead space-out may be determined using, e.g., a lead impression tool (LIT). In the wellhead system shown in
In accordance with the present disclosure, a tubing hanger and adjustable load nut assembly is provided which enables the vertical spacing between the load shoulder and the locking dogs to be adjusted automatically. As a result, the need to measure the wellhead space-out and adjust the position of the load nut before the tubing hanger is run into the wellhead is eliminated, which greatly reduces the time required to install the tubing hanger.
An illustrative embodiment of a tubing hanger and adjustable load nut assembly of the present disclosure is shown in
Referring also to
The tubing hanger 100 is secured to the wellhead 10 by engagement of interacting lockdown features on the tubing hanger and the wellhead. The lockdown features may comprise any suitable means for securing the tubing hanger to the wellhead. For example, the wellhead may comprise a locking profile in the central bore which is engaged by a lock ring carried on the tubing hanger or on a separate lockdown mandrel or similar device. As another example, the tubing hanger may comprise a locking profile on the outer surface which is engaged by a number of locking pins or similar devices mounted on the wellhead.
In the example shown in
As discussed above, in order to ensure that the tubing hanger 100 is properly locked to the wellhead 10, the vertical distance between the load shoulder 106 and the locking dogs 108 must be the same as the vertical distance between the seat 16 and the locking profile 32. In the prior art, the vertical distance between the load shoulder 106 and the locking dogs 108 was adjusted manually. In accordance with the present disclosure, after the tubing hanger 100 is landed and locked in the wellhead 10, and preferably also pre-tensioned from above, the vertical distance between the load shoulder 106 and the locking dogs 108 is adjusted automatically using a novel torsion spring arrangement.
Referring also to
During assembly of the tubing hanger 100, the load nut 104 is threaded onto the tubing hanger body 102 until it reaches an initial or upper position, which is shown in
In order to maintain the torsion spring 114 in its torqued state, the tubing hanger 100 also includes means for preventing the load nut 104 from rotating relative to the tubing hanger body 102 until after the tubing hanger is landed in the wellhead 10. Referring to
In this example, when the load nut 104 is in its initial position, a distal end 142 of the latch member 130 will be positioned in a corresponding groove 144 formed in the upper surface of the load nut. In this position, the spring 136 will bias the latch member 130 toward the load nut 104 with sufficient force to maintain the distal end 142 of the latch member fully engaged in the groove 144 and thus prevent the torsion spring 114 from rotating the load nut relative to the tubing hanger body 102.
In the illustrative embodiment shown in
During installation, the tubing hanger 100 is connected to a drill string and lowered from a surface vessel toward the wellhead 10. The tubing hanger 100 is lowered into the wellhead 10 until the load shoulder 106 on the adjustable load nut 104 lands on the seat 16 at the top of the casing hanger 14. As shown in
Once the tubing hanger 100 is locked to the wellhead 10, tension is applied to the drill string to lift the tubing hanger upward until the upper facing portions of the locking ridges 108a are fully loaded against the corresponding downward facing portions of the locking grooves 32a. During this process, the load nut 104 is lifted off of the landing seat 106. Since the latch member 130 is no longer engaged with the groove 144 in the top of the load nut 104, the torsion spring 114 will force the load nut to rotate downward relative to the tubing hanger body 102 until the landing shoulder 106 is once again fully engaged with the landing seat 106. This is the position of the load nut 104 shown in
In other embodiments, the latching and de-latching mechanisms may take different forms from those described above. For example, the latch member 130 may be mounted on the load nut 104 and be biased by a spring 136 or other suitable means into engagement with a corresponding groove formed in the tubing hanger body 102. In this example, the de-latching mechanism may comprise a rod or pin which is linked to the latch member 130 and which functions to retract the latch member from the groove when the rod or pin engages the seat 16 or a corresponding feature in the central bore 12 of the wellhead 10.
In another example, the latch member 130 shown in
In a variation of this embodiment, the spring 136 may be removed and the source of pressurized fluid may be used to both extend the latch member 130 into the groove 144 (by applying a positive pressure to the bore 132) and retract the latch member from the groove 144 (by applying a negative pressure to the bore 132).
In a further variation, the spring 136 may comprise an extension spring which functions to retract the latch member 130 from the groove 144. In this example, the source of pressurized fluid may be used to maintain the latch member in the groove until the tubing hanger 100 is landed on the seat 16, at which point the pressure can be released to allow the latch member 130 to retract from the groove.
In a further embodiment, the latching and de-latching mechanisms may comprise a number of shear pins or the like which are connected between the load nut 104 and the tubing hanger body 102.
Although the torsion spring arrangement has been described herein in the context of a tubing hanger which is landed on a casing hanger supported in a wellhead, it should be understood that it could be used in other applications, either within or outside of the field of subsea hydrocarbon production systems. In the field of subsea hydrocarbon production systems, for example, the torsion spring arrangement could be used to obtain proper spacing between any tubular hanger and any component within which the tubular hanger is landed, such as, e.g., a tubing spool or tubing head.
More generally, the present disclosure provides a torsion spring arrangement for use in securing an inner member to an outer member which surrounds at least a portion of the inner member. In one embodiment, the outer member comprises first and second axially spaced outer features and the inner member comprises first and second axially spaced inner features which are configured to engage the outer features to secure the inner member to the outer member. The first inner feature is formed on a component which is threadedly connected to the inner member, and the torsion spring arrangement is operable to rotate the component to thereby move the first inner feature axially relative to the inner member until the first and second inner features engage the first and second outer features, respectively, to secure the inner member to the outer member. Alternatively, the first outer feature may be formed on a component which is threadedly connected to the outer member, and the torsion spring arrangement may be operable to rotate the component to thereby move the first outer feature axially relative to the outer member until the first and second inner features engage the first and second outer features, respectively, to secure the inner member to the outer member.
It should be recognized that, while the present disclosure has been presented with reference to certain embodiments, those skilled in the art may develop a wide variation of structural and operational details without departing from the principles of the disclosure. For example, the various elements shown in the different embodiments may be combined in a manner not illustrated above. Therefore, the following claims are to be construed to cover all equivalents falling within the true scope and spirit of the disclosure.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/060461 | 11/7/2017 | WO | 00 |
