Claims
- 1. A tubing tightener adapted for insertion in a wellbore together with a tubing string, the tightener comprising:
- a mandrel adapted for connection to at least an upper section of tubing by attachment of the mandrel to a lower end of the tubing section, to secure the mandrel for axial and rotational movement with the tubing string and enable the tightener to be rotated between an unlocked and locked position by manipulation of the tubing string;
- a drag slip support assembly mounted upon the mandrel and means for restraining said support assembly from axial movement on said mandrel;
- a plurality of drag slips peripherally mounted upon the support assembly, the drag slips each having an outer surface comprising a slip surface region and a drag surface region which are selectively engageable with the wellbore and, located intermediate said regions, a region of contact between the drag slip surface and the wellbore in both the locked and unlocked conditions of the tightener;
- means biasing the slip surface regions inwardly towards the mandrel and the drag surface regions outwardly towards the wellbore with sufficient force that, in the unlocked position of the tightener, the drag surface regions frictionally engage the wellbore and restrain relative rotational movement between the drag slips and the wellbore whilst still permitting axial movement of the tubing string; and
- a booster assembly supported by and rotatable with the mandrel, and including a plurality of formations, each having an outwardly facing wall surface extending tangentially to an arc of rotation of the mandrel and engaging the respective drag slips upon rotation of the mandrel in a first direction to progressively force the slip surface regions outwardly into engagement with the wellbore with sufficient force to prevent relative movement between the drag slips and the wellbore;
- the booster assembly being rotatable with the mandrel in the opposite direction to allow the drag slips to rock about their regions of contact with the wellbore to retract the slip surface regions and advance the drag surface regions under the influence of the biasing means.
- 2. A tubing tightener as defined in claim 1, wherein each said outwardly facing wall surface has a convex curvature which curves from a tangential orientation at a point of contact with said arc of rotation of said mandrel to become progressively closer to an arcuate orientation centered on said mandrel axis.
- 3. A tubing tightener as defined in claim 2, wherein:
- said drag slip support assembly is freely rotatable about said mandrel and each said formation comprises a booster sub having side edges extending axially of the mandrel and a wedge profile in cross-section from one side edge to the opposite side edge to form said outwardly facing wall surface, each said booster sub adapted for selective engagement with a first rear surface region of the drag slip behind the slip surface region upon rotation of said mandrel;
- each booster sub being rotatable with the mandrel upon rotation thereof from the unlocked position of the tightener to its locked position whereupon said outwardly facing wall surface is moved into engagement with said first rear surface region of the drag slip and progressively forces said first rear surface region outwardly to cause the drag slip to rock about the region of contact between the drag slip surface and the wellbore to retract the drag surface region and advance the slip surface region until the slip surface region engages the wellbore with sufficient force to prevent relative movement between the drag slip and the wellbore; and
- each booster sub being rotatable with the mandrel upon rotation thereof from the locked position of the tightener to its unlocked position to disengage the outwardly facing wall surface from the drag slip to allow the drag slip to rock in the opposite direction under the influence of said biasing means to retract the slip surface region and advance the drag surface region.
- 4. A tubing tightener as defined in claim 3 comprising at least three said drag slips.
- 5. A tubing tightener as defined in claim 4, wherein each said slip surface region is provided with teeth extending in the axial direction of said wellbore for gripping said wellbore.
- 6. A tubing tightener as defined in claim 5, wherein each said drag slip has a second rear surface region located behind said drag surface region, said second rear surface region engaged by said biasing means.
- 7. A tubing tightener as defined in claim 6, wherein said booster assembly is in the form of a cylindrical cage assembly having a series of peripherally spaced openings through which said drag slips project radially outwardly.
- 8. A tubing tightener as defined in claim 7, wherein said cage assembly comprises upper and lower sleeve members rotatably mounted on said mandrel and a cage member secured to said sleeve members and extending therebetween.
- 9. A tubing tightener as defined in claim 8, wherein:
- said upper sleeve member comprises upper and lower sleeve sections, said lower section extending downwardly inside said cage member, and said lower sleeve member comprises upper and lower sleeve sections, said upper section extending upwardly inside said cage member, said upper section of said lower sleeve member and said lower section of said upper sleeve member each being provided with an outwardly extending peripheral flange; and
- said biasing means for each said drag slip comprises a flat spring having ends thereof captured between said flanges and a central region bowed outwardly into abutment with said drag slip second rear surface region.
- 10. A tubing tightener as defined in claim 9, wherein:
- each said drag slip has upper and lower ends respectively provided with arcuate flanges which extend upwardly and downwardly behind upper and lower edges of the cage openings, respectively, and prevent separation of said drag slip from said cage.
- 11. A tubing tightener as defined in claim 10, wherein:
- each said booster sub is keyed for rotation with said mandrel by means of key members projecting outwardly from axially extending slots in said mandrel and retaining therebetween said side edges of said booster sub.
- 12. A tubing tightener as defined in claim 11, wherein:
- said drag slips and said booster sub co-operate for locking said tightener in a first selected direction of rotation of said tubing string;
- said cage member is removably secured to said sleeve members; and
- said booster subs are removable from said mandrel and said drag slips are removable from said cage assembly, upon detachment of said cage member from said sleeve members, and are reversible to permit reattachment of said cage member to said sleeve members with said drag slips and said booster subs co-operating to lock said tightener upon rotation of said tubing string in the opposite direction.
- 13. A tubing tightener as defined in claim 2 comprising at least three of said drag slips.
- 14. A tubing tightener as defined in claim 1 comprising at least three of said drag slips.
- 15. A tubing tightener adapted for insertion in a wellbore together with a tubing string, the tightener comprising:
- a mandrel adapted for connection to at least an upper section of tubing by attachment of the mandrel to a lower end of the tubing section, to secure the mandrel for axial and rotational movement with the tubing string and enable the tightener to be rotated between an unlocked and a locked position by manipulation of the tubing string;
- a plurality of drag slips peripherally mounted upon said mandrel, the drag slips each having an outer surface comprising a slip surface region and a drag surface region which are selectively engageable with the wellbore and, located intermediate said regions, a region of contact between the drag slip surface and the wellbore in both the locked and unlocked conditions of the tightener;
- means biasing the slip surface regions inwardly towards the mandrel and the drag surface regions outwardly towards the wellbore with sufficient force that, in the unlocked position of the tightener, the drag surface regions frictionally engage the wellbore and restrain relative rotational movement between the drag slips and the wellbore whilst still permitting axial movement of the tubing string; and
- a booster assembly supporting said drag slips and comprising a pair of spaced elevators rotatably mounted on said mandrel with opposed surfaces between which said drag slips extend;
- each drag slip having extensions formed at its opposite ends, which extend into channels formed in the opposed surfaces of the elevators, the channel walls providing outwardly facing wall surfaces extending tangentially to an arc of rotation of said mandrel and engaging the drag slip extensions upon rotation of the mandrel, the extensions being located on the same side of the region of contact between the drag slip surface and the wellbore as the slip surface region, such that exertion of an outward force upon the extensions results in rocking of the drag slips to advance the slip surface regions and retract the drag surface regions;
- whereby rotation of the mandrel from the unlocked position of the tightener to its locked position moves said outwardly facing wall surfaces into engagement with said drag slip extensions and progressively forces said extensions outwardly to cause each drag slip to rock about the region of contact between the drag slip surface and the wellbore to retract the drag surface region and advance the slip surface region until the slip surface region engages the wellbore with sufficient force to prevent relative movement between the drag slip and the wellbore; and
- rotation of the mandrel from the locked position of the tightener to its unlocked position allows the drag slip to rock in the opposite direction under the influence of said biasing means to retract the slip surface region and advance the drag surface region.
- 16. A tubing tightener as defined in claim 15, wherein each said outwardly facing wall surface has a convex curvature which curves from a tangential orientation at a point of contact with said arc of rotation of said mandrel to become progressively closer to an arcuate orientation centered on said mandrel axis.
- 17. A tubing tightener as defined in claim 16, wherein:
- the outwardly facing wall surfaces of said channels are coextensive with end walls which move into engagement with said extensions as the elevators are turned into the unlocked position of the tubing tightener, said end walls being angled rearwardly and inwardly relative to the direction of turning of said elevators to force said extensions inwardly upon continued turning of the elevators and retract both said slip surface regions and said drag surface regions from engagement with said wellbore.
- 18. A tubing tightener as defined in claim 15, 16, or 17, comprising at least three said drag slips equispaced upon said booster assembly in circular array.
- 19. A tubing tightener as defined in claim 18, wherein each said slip surface region is provided with teeth extending in the axial direction of said wellbore for gripping said wellbore.
- 20. A tubing tightener as defined in claim 19, wherein each said drag slip has a second rear surface region located behind said drag surface region, said second rear surface region engaged by said biasing means.
- 21. A tubing tightener as defined in claim 20, wherein said booster assembly is in the form of a cylindrical cage assembly having a series of peripherally spaced openings through which said drag slips project radially outwardly, said cage assembly extending between and freely rotatable relative to said elevators.
- 22. A tubing tightener as defined in claim 21, further comprising a central sleeve member rotatably mounted on said mandrel between said elevators.
- 23. A tubing tightener as defined in claim 22, wherein:
- said biasing means for each said drag slip comprises a flat spring having ends thereof in abutment with said sleeve member and a central region bowed outwardly into abutment with said drag slip second rear surface region.
- 24. A tubing tightener as defined in claim 23, wherein:
- each said elevator is keyed for rotation with said mandrel by means of key members projecting outwardly from axially extending slots in said mandrel and engaging slots formed in each said elevator.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2162409 |
Nov 1995 |
CAX |
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Parent Case Info
This application is a continuation-in-part of application Ser. No. 08/568,199 filed Dec. 6, 1995, now U.S. Pat. No. 5,623,991.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1274470 |
Sep 1990 |
CAX |
Non-Patent Literature Citations (1)
Entry |
Drawing of clutch mandrel for slip assemblies for Homco Reversing Tool, Part No. 622-337 by Gulf Tool Co., Houston, Texas, Jan. 8, 1948, and photograph of same clutch mandrel believed to have been on sale more than one year prior to the filling of the present application. |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
568199 |
Dec 1995 |
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