Slip release assembly with cone undermining feature

Abstract

A slip release mechanism provides for undermining the slip cone in the set position of the slips so that the grip of the slips can be released subsequent to allowing the cone ramp to flex. The slips can be pulled back down the cone ramp as the completion of the same motion that undermines the support for the cone.

Claims

1. A fixation assembly for a subterranean tool, comprising: a mandrel; at least one slip assembly mounted to said mandrel; a cone mounted to said mandrel for selectively guiding said slip assembly radially away from said mandrel, said cone selectively collapsible toward said mandrel when said slip assembly is engaged to a surrounding tubular to facilitate release of grip by said slip assembly from the surrounding tubular, said release of grip accomplished by breaking a breakable member, on a support sleeve connecting said support sleeve to said at least one slip assembly, as said at least one slip assembly moves radially away from said mandrel thereby allowing initial registry of said support sleeve with said mandrel for subsequent movement of said support sleeve away from between said cone and said mandrel as said at least one slip assembly releases grip.

2. The assembly of claim 1, wherein: said cone further comprising at least a first and a second radially stacked components.

3. The assembly of claim 2, wherein: said first and said second components are relatively movable.

4. The assembly of claim 3, wherein: said mandrel engaging said second component to translate said second component axially away from said first component that comprises a tapered surface for engaging said slip assembly.

5. The assembly of claim 4, wherein: said mandrel movable axially for a predetermined distance before engaging said second component for tandem movement.

6. The assembly of claim 2, wherein: said second component initially secured to said slip assembly with a breakable member.

7. The assembly of claim 6, wherein: a broken portion of said breakable member enters a recess on said mandrel to facilitate tandem axial movement of said mandrel and said second component.

8. The assembly of claim 1, wherein: said cone comprising an undercut facing said mandrel that is selectively occupied by said a support sleeve.

9. The assembly of claim 8, wherein: said support sleeve disposed in said undercut as said slip assembly moves away from said mandrel on a tapered surface of said cone.

10. The assembly of claim 9, wherein: said mandrel selectively removing said support sleeve from said undercut for grip release by said slip assembly in response to flexing of said cone, enabled by movement of said sleeve.

11. The assembly of claim 1, wherein: a portion of said sheared breakable member engages a recess in said mandrel.

12. The assembly of claim 11, wherein: tandem movement of said mandrel and support sleeve using said sheared breakable member positioned in said recess removes said support sleeve from said undercut.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a section view in the run in position;

(2) FIG. 2 is the view of FIG. 1 in the set position; and

(3) FIG. 3 is the view of FIG. 2 in the released position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(4) Referring to FIG. 1 the slip assembly 10 is shown in the run in position. Cone 12 is supported from mandrel 14 by sleeve 16. Sleeve 16 is initially held to the outer assembly 19. Outer assembly 19 holds the slips 20 against axial movement when the cone 12, sleeve 16 and retainer 26 move up axially with respect to the mandrel 14 for the set position shown in FIG. 2. Ramp 22 on the cone 12 engages ramp 24 on the slips 20 as the slips 20 move out radially to engage the surrounding tubular for the set position.

(5) As seen in FIG. 2 the upward movement of the cone 12 takes with it sleeve 16 as the shear device 18 breaks. A retainer 26 sits in an opening 28 of the sleeve 16. When the shear device 18 breaks and the set position of FIG. 2 is reached, the retainer 26 is no longer retained by the now broken shear device 18. Retainer 26 is now able to fall radially inwardly into groove 30. Groove 30 has a retrieval surface 32 at its lower end designed to engage retainer 26 for undermining the cone 12 by pulling out the sleeve 16 out from under it as shown in FIG. 3. The parts are proportioned so that the sleeve 16 is first removed from under cone 12 before further picking up of mandrel 14 engages outer assembly 19 to pull the slips 12 down ramp 22 of the cone 12 for the fully released position.

(6) Those skilled in the art will appreciate that by initially undermining the cone with the slips extended, the slips are no longer wedged against the surrounding tubular and as a follow on movement can be retracted down the ramp that defines the cone. The sleeve 16 may engage the cone on a single or multiple surfaces 38, 40 and 42 with substantially parallel surfaces 44, 46 and 48 respectively. These surfaces can be parallel to the axis of the mandrel as illustrated in the drawing or at a skew to the mandrel 14 axis. The end of sleeve 16 can be a complete cylindrical shape or can have cutouts or slots to make retraction shown in FIG. 3 simpler. The cone 12 can also be a 360 degree ramp or can have cutouts or slots to the end or on the ramp for the same reason. The sleeve and associated cone can have similar or dissimilar features designed to facilitate release of sleeve 16 from under the cone 12. Other alternatives are contemplated such as a change in shape for the sleeve 16 in response to well conditions. One example is to use a shape memory alloy for the sleeve 16 that responds to added heat to reduce in thickness to facilitate removal.

(7) The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: