MOBILE RIG TO WELL SECUREMENT SYSTEM AND METHOD

Abstract

A mobile well rig can include a mast, an anchor that connects to a flange of a wellhead assembly, and a tensile member that transfers tensile loads between the wellhead assembly and the mast. A method of securing a mobile well rig to a wellhead assembly can include connecting an anchor to the wellhead assembly, connecting a tensile member to the anchor, and connecting the tensile member to a mast of the mobile well rig. A securement system can include an anchor secured to a wellhead assembly, a tensile member that transfers a tensile load between the wellhead assembly and a mast of a mobile well rig, and a strut that transfers a compressive load between the wellhead assembly and the mast.

Claims

1. A mobile well rig for use with a subterranean well, the mobile well rig comprising: a mast; an anchor configured for connection to a flange of a wellhead assembly; and a tensile member configured to transfer tensile loads between the wellhead assembly and the mast.

2. The mobile well rig of claim 1, in which the tensile member is selected from the group consisting of a cable, a chain, a rod and a brace.

3. The mobile well rig of claim 1, in which the tensile member is connected to the anchor and to a platform that extends laterally outward from the mast.

4. The mobile well rig of claim 3, in which the platform is positioned adjacent a stripping blowout preventer stack connected above a lubricator.

5. The mobile well rig of claim 1, in which the tensile member is pivotably connected to the anchor.

6. The mobile well rig of claim 1, in which the anchor is configured to connect between a lubricator and a blowout preventer of the wellhead assembly.

7. The mobile well rig of claim 1, in which the flange is formed on a blowout preventer of the wellhead assembly.

8. The mobile well rig of claim 1, in which a strut is connected between the anchor and the mast.

9. The mobile well rig of claim 8, in which the strut is pivotably connected to a laterally extending beam.

10. The mobile well rig of claim 1, further comprising a strut configured to transfer a compressive load between the mast and the wellhead assembly.

11. A method of securing a mobile well rig to a wellhead assembly, the method comprising: connecting an anchor to the wellhead assembly; connecting a tensile member to the anchor; and connecting the tensile member to a mast of the mobile well rig.

12. The method of claim 11, in which the step of connecting the anchor comprises connecting the anchor between a lubricator and a blowout preventer stack.

13. The method of claim 11, in which the step of connecting the anchor comprises connecting the anchor between a flange of a lubricator and a flange of a blowout preventer.

14. The method of claim 11 in which the step of connecting the tensile member to the anchor comprises pivotably connecting the tensile member to the anchor.

15. The method of claim 11, in which the step of connecting the tensile member to the anchor comprises connecting the tensile member to a laterally outward extending post of the anchor.

16. The method of claim 11, in which the step of connecting the tensile member to the mast comprises connecting the tensile member to a platform on the mast.

17. The method of claim 16, in which the platform extends at least partially about a stripping blowout preventer stack.

18. The method of claim 11, in which the tensile member is selected from the group consisting of a cable, a chain, a rod and a brace.

19. The method of claim 11, further comprising connecting a strut between the mast and the anchor.

20. The method of claim 19, further comprising the strut transferring a compressive load between the mast and the anchor.

21. A system for use with a subterranean well, the system comprising: an anchor secured to a wellhead assembly; a tensile member that transfers a tensile load between the wellhead assembly and a mast of a mobile well rig; and a strut that transfers a compressive load between the wellhead assembly and the mast.

22. The system of claim 21, in which the tensile member is selected from the group consisting of a cable, a chain, a rod and a brace.

23. The system of claim 21, in which the tensile member is connected to a platform that extends laterally outward from the mast.

24. The system of claim 23, in which the platform is positioned adjacent a stripping blowout preventer stack connected above a lubricator.

25. The system of claim 21, in which the tensile member is pivotably connected to the anchor.

26. The system of claim 21, in which the anchor is connected between a lubricator and a blowout preventer of the wellhead assembly.

27. The system of claim 21, in which the anchor is connected to a flange of the wellhead assembly.

28. The system of claim 27, in which the flange is formed on a blowout preventer of the wellhead assembly.

29. The system of claim 21, in which the strut is pivotably connected to a laterally extending beam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a representative perspective view of an example of a mobile well rig and associated method which can embody principles of this disclosure.

[0006] FIG. 2 is a representative perspective view of the rig, with a mast of the rig partially raised.

[0007] FIG. 3 is a representative perspective view of the rig, with the mast further raised.

[0008] FIG. 4 is a representative perspective view of the rig, with the mast fully raised and secured to a wellhead assembly.

[0009] FIG. 5 is a representative perspective view of a portion of the rig comprising a securement system and method.

DETAILED DESCRIPTION

[0010] Representatively illustrated in FIG. 1 is a mobile well rig 10 and associated method which can embody principles of this disclosure. However, it should be clearly understood that the rig 10 and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the rig 10 and method described herein and/or depicted in the drawings.

[0011] In one aspect of the present disclosure, a system that can be fully integrated into a service rig is disclosed, which in one example comprises a structural apparatus to support and anchor the rig to a wellhead assembly. The system can be particularly useful in well operations in which tubulars are snubbed into or out of the well (although this disclosure is not limited to snubbing operations).

[0012] A rig assist snubbing unit offers a cost-effective solution for running or pulling tubing in and out of a pressurized wellbore under what is considered live well intervention operations, avoiding the risk of formation damage caused by kill fluid. This enables operators to maintain production during such operations, for example.

[0013] Although rig assist snubbing units are cost effective, there is a considerable amount of concern for personnel safety due to the conditions personnel are exposed to during operation of the unit. Typically, rig assist units require two or more personnel to work very near the center of the wellbore right under the rig elevators, exposing the personnel to fall hazards and other hands-on related injuries. However, a drawback to conventional workover and/or drilling rigs is an inability to properly anchor the rig to the wellhead. Rig weight by itself may not be sufficient to fully resist snubbing loads safely at high pressures.

[0014] Some features disclosed herein can include (but are not limited to) a wellhead mount and anchoring system to structurally secure the rig to the wellhead, for example, to resist snub loads. In one embodiment, a wellhead securement system is structurally integrated into the rig structure to enable a rigid anchor connection between the rig and wellhead to resist snubbing loads that exceed rig weight.

[0015] The wellhead mount and anchoring system can comprise structural tie-back points to allow additional anchor reinforcement via beams, struts, stiff arms, guy wire, chains, boom lines and/or ground anchors. A strut can be provided to extend between the rig (such as, at a rear of a transport) and the wellhead (such as, at a flange of a blowout preventer stack), in order to prevent the rig from displacing toward the wellhead when large snubbing loads are encountered.

[0016] The wellhead mount system is integrated with the wellhead assembly, such that wellbore pressure is contained. The anchor may include a flange that is connected between an upper flange of the blowout preventer stack and a lower flange of a lubricator.

[0017] In one example, tie back cables or other tensile members are connected between the anchor and the mast (such as, at an underside of a stripping stack walk-around platform). The cables may be connected at laterally extending ears or posts of the anchor, permitting the cables to rotate about the ears.

[0018] In one example of the mobile well rig, a two-section jointed mast can comprise an ultra heavy-duty motor and conveyor system integrated into an upper mast section to snub tubulars connected to a top drive. When stowed on a transport vehicle an upper mast section is positioned below a lower mast section. During rig-up, both sections are raised to an upright position such that the upper mast is behind (on a tractor side of the vehicle) the lower section with the rear of the vehicle facing the wellhead.

[0019] The upper mast section is then rotated about an axis positioned at the top of the lower mast such that the upper mast folds outward and towards the wellhead, and is locked in place once upright. If the well is a slant well (in which the wellbore is inclined from vertical at the surface), the upper and lower masts may be positioned in an appropriately inclined position when extended.

[0020] The snubbing function is provided with multiple high torque electrical servo motors-two at each end of the chain conveyor assembly. A carriage is attached to the chain assembly which slides up and down a track integrated with the upper mast section. The top drive is mounted to the carriage once the mast apparatus is in the vertical upright position (or an inclined position for a slant well).

[0021] In one embodiment, a lubricator system is mounted above a wellhead blowout preventer stack for lubricating tools into the wellbore safely under pressure. A stripping blowout preventer stack is connected above the lubricator.

[0022] The stripping blowout preventer stack is used to contain wellbore pressures while snubbing tubulars into the wellbore. The stripping blowout preventer stack can comprise an annular blowout preventer, two or more slip/safety ram blowout preventers, a center drill spool, valves and an equalization loop.

[0023] Referring specifically now to FIG. 1, a representative perspective view of an example of the mobile well rig 10 and associated method is depicted. In this example, the mobile well rig 10 comprises a mast 12 mounted on a transport vehicle 14.

[0024] As depicted in FIG. 1, the rig 10 is appropriately positioned proximate a wellhead (not shown in FIG. 1, see FIG. 4), and outriggers 16 of the transport vehicle 14 have been deployed to support a generally horizontal bed or platform 18 on which the mast is pivotably mounted. The mast 12 is stored for transport on the platform 18 rearward of a cab 20 of the transport vehicle 14.

[0025] The mast 12 is in a folded configuration as depicted in FIG. 1. An upper section 12a of the mast 12 is positioned between the platform 18 and a lower section 12b of the mast.

[0026] Referring additionally now to FIG. 2, a representative perspective view of the rig 10, with the mast 12 partially raised is depicted. In this view, the lower mast 12b has been pivoted upward from the platform 18, so that the lower mast is now vertical. In some examples, the lower mast 12b could be raised to an inclined position relative to the platform 18 (such as, when used with a slant well).

[0027] Note that the upper mast 12a is also in a vertical orientation at this point as depicted in FIG. 2, although it remains folded against the lower mast 12b. The upper mast 12a is positioned between the lower mast 12b and the cab 20 of the transport vehicle 14.

[0028] Referring additionally now to FIG. 3, a representative perspective view of the rig 10, with the mast 12 further raised is depicted. In this view, the upper mast 12a is being pivoted upward relative to the lower mast 12b. When fully raised, the upper mast 12a will be vertical and aligned with the lower mast 12b. Hydraulic cylinders 32 (not shown in FIG. 3, see FIG. 4) or other suitable equipment (such as, a crane, a winch system, etc.) may be used to raise the mast 12 in other examples.

[0029] Referring additionally now to FIG. 4, a representative perspective view of the rig 10, with the mast 12 fully raised and secured to a wellhead assembly 22 is depicted. In this view, it may be seen that the wellhead assembly 22 is connected above a wellhead 24 and includes a blowout preventer stack 26 (comprising multiple blowout preventers 26a-d), a lubricator 28 and a stripping blowout preventer stack 30. Other equipment (such as, a slip bowl assembly) may be connected above the stripping blowout preventer stack 30 in some examples.

[0030] The lubricator 28 and stripping blowout preventer stack 30 are useful for containing well pressure when snubbing tubulars into and out of the well. If snubbing operations are not anticipated, these components may not be used, or other components not designed for use with snubbing operations may be used.

[0031] An anchor 34 is connected to the wellhead assembly 22 in order to secure the mast 12 against inadvertent movement due, for example, to snubbing loads on the tubulars run into or out of the well using the rig 10. The rig 10 in this example uses a top drive (not shown) to run the tubulars, and so the top drive will transfer snubbing loads from the tubulars to the mast 12.

[0032] Tensile members 36 are connected between the anchor 34 and the mast 12 to transfer tensile loads from the mast to the anchor (and thence to the wellhead assembly 22). The tensile members 36 may be in the form of cables, chains, rods or braces.

[0033] In this example, an upper end of each tensile member 36 is pivotably connected to an underside of a platform 38 positioned adjacent the stripping blowout preventer stack 30. A lower end of each tensile member 36 is pivotably connected to the anchor 34.

[0034] Struts 40 are connected between the mast 12 and the anchor 34. The struts 40 transfer compressive loads between the mast 12 and the anchor 34, in order to prevent the rig 10 from being moved toward the wellhead assembly 22 when substantial snubbing loads are applied.

[0035] Referring additionally now to FIG. 5, a representative perspective view of a portion of the rig 10 is depicted. In this view it may be seen that the anchor 34, tensile members 36 and struts 40 comprise a securement system 52 which can be used to secure the rig 10 relative to the wellhead assembly 22.

[0036] The anchor 34 is configured to connect between flanges 42, 44. In this example, the flange 42 is a lower flange of the lubricator 28, and the flange 44 is an upper flange of the upper blowout preventer 26a.

[0037] Ears or horizontal posts 46 (only one of which is visible in FIG. 5) extend laterally outward from the anchor 34. The lower ends of the tensile members 36 are pivotably connected to the posts 46.

[0038] A beam 48 extends laterally outward on a side of the anchor 34 facing toward the mast 12. An outer end of each of the struts 40 is pivotably connected to the beam 48. The other end of each strut 40 is pivotably connected to the lower mast 12b. Hydraulic cylinders 50 can be used to adjust positions of the struts 40 relative to the beam 48.

[0039] It may now be fully appreciated that the above disclosure provides significant advancements to the art of mobile well rig 10 construction and operation. In an example described herein, the mobile well rig 10 can be secured to a wellhead assembly 22 so that a mast 12 of the rig will not be displaced due to snubbing loads on tubulars run into or out of a well.

[0040] The present disclosure provides to the art a mobile well rig 10 for use with a subterranean well. In one example, the mobile well rig 10 can comprise a mast 12, an anchor 34 configured for connection to a flange 42, 44 of a wellhead assembly 22, and a tensile member 36 configured to transfer tensile loads between the wellhead assembly 22 and the mast 12.

[0041] The tensile member 36 may be selected from the group consisting of a cable, a chain, a rod and a brace. The tensile member 36 may be connected to the anchor 34 and to a platform 38 that extends laterally outward from the mast 12. The platform 38 may be positioned adjacent a stripping blowout preventer stack 30 connected above a lubricator 28.

[0042] The tensile member 36 may be pivotably connected to the anchor 34. The anchor 34 may be configured to connect between a lubricator 28 and a blowout preventer 26a of the wellhead assembly 22. The which the flange 44 may be formed on a blowout preventer 26a of the wellhead assembly 22.

[0043] A strut 40 may be connected between the anchor 34 and the mast 12. The strut 40 may be pivotably connected to a laterally extending beam 48. The strut 40 may be configured to transfer a compressive load between the mast 12 and the wellhead assembly 22.

[0044] The present disclosure also provides to the art a method of securing a mobile well rig 10 to a wellhead assembly 22. In one example, the method can comprise: connecting an anchor 34 to the wellhead assembly 22; connecting a tensile member 36 to the anchor 34; and connecting the tensile member 36 to a mast 12 of the mobile well rig 10.

[0045] The step of connecting the anchor 34 may include connecting the anchor 34 between a lubricator 28 and a blowout preventer stack 26.

[0046] The step of connecting the anchor 34 may include connecting the anchor 34 between a flange 42 of a lubricator 28 and a flange 44 of a blowout preventer 26a.

[0047] The step of connecting the tensile member 36 to the anchor 34 may include pivotably connecting the tensile member 36 to the anchor 34. The step of connecting the tensile member 36 to the anchor 34 may include connecting the tensile member 36 to a laterally outward extending post 46 of the anchor 34.

[0048] The step of connecting the tensile member 36 to the mast 12 may include connecting the tensile member 36 to a platform 38 on the mast 12. The platform 38 may extend at least partially about a stripping blowout preventer stack 30.

[0049] The method may include connecting a strut 40 between the mast 12 and the anchor 34. The strut 40 may transfer a compressive load between the mast 12 and the anchor 34.

[0050] A system 52 for use with a subterranean well is also disclosed. In one example, the system 52 can include an anchor 34 secured to a wellhead assembly 22, a tensile member 36 that transfers a tensile load between the wellhead assembly 22 and a mast 12 of a mobile well rig 10, and a strut 40 that transfers a compressive load between the wellhead assembly 22 and the mast 12.

[0051] The tensile member 36 may be selected from the group consisting of a cable, a chain, a rod and a brace. The tensile member 36 may be connected to a platform 38 that extends laterally outward from the mast 12. The platform 38 may be positioned adjacent a stripping blowout preventer stack 30 connected above a lubricator 28.

[0052] The tensile member 36 may be pivotably connected to the anchor 34. The anchor 34 may be connected between a lubricator 28 and a blowout preventer 26a of the wellhead assembly 22.

[0053] The anchor 34 may be connected to a flange 42, 44 of the wellhead assembly 22. The flange 44 may be formed on a blowout preventer 26a of the wellhead assembly 22. The strut 40 may be pivotably connected to a laterally extending beam 48.

[0054] Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example's features are not mutually exclusive to another example's features. Instead, the scope of this disclosure encompasses any combination of any of the features.

[0055] Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used.

[0056] It should be understood that the various embodiments described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.

[0057] In the above description of the representative examples, directional terms (such as above, below, upper, lower, upward, downward, etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein.

[0058] The terms including, includes, comprising, comprises, and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as including a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term comprises is considered to mean comprises, but is not limited to.

[0059] Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the invention being limited solely by the appended claims and their equivalents.