# Patent

## Title
Launching tool with interlock system for downhole cement plug and method

## Abstract

A launching tool with interlock system for a downhole cement plug includes a mandrel having one or more windows therein; an interlock system disposed at the mandrel, the interlock system having a release member; one or more dogs extending from the release member through the one or more windows; a collet disposed at the mandrel and restrained by a restrainer, the restrainer releasable only after release of the interlock system and method.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 61/082,631 filed Jul. 22, 2008, the entire disclosure of which is incorporated herein by reference.


BACKGROUND
Cementing is common in the downhole industry in conjunction with the installation of a liner, etc. Often where cementing is undertaken, a wiper plug is deployed following the application of cement to wipe interior surfaces of conducting pathways, such as the inside surface of a liner to avoid the curing of any significant amount of cement on surfaces not intended to have such cement. Several configuration of launching tools are available to the art for deploying wiper plugs all of which are competent for their intended purposes. The art however is always receptive to improvements or alternative means, methods and configurations. Therefore the art will well receive the launching tool described herein.
SUMMARY
A launching tool with interlock system for a downhole cement plug includes a mandrel having one or more windows therein; an interlock system disposed at the mandrel, the interlock system having a release member; one or more dogs extending from the release member through the one or more windows; a collet disposed at the mandrel and restrained by a restrainer, the restrainer releasable only after release of the interlock system.
A wiper plug launching tool including a wiper plug; and a retainer in operable communication with the wiper plug, the retainer releasable only upon a sequence of mechanical and hydraulic events.
A method for wiping a tubular after cementing includes running a wiper plug launching tool to a selected location; pumping cement through the wiper plug; running an actuation plug; landing the actuation plug in the launching tool; causing a sequence of events resulting in release of the wiper plug; landing the actuation plug in the wiper plug; and pumping the wiper plug downhole.



BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
FIG. 1 is a cross section view of a launching tool as disclosed herein in a run in position;
FIG. 2 is a cross section view of the tool illustrated in FIG. 1 with an actuation plug disposed therein;
FIG. 3 is a cross section view of the tool as illustrated in FIG. 1 in a lockout released position;
FIG. 4 is a cross sectional view of the tool as illustrated in FIG. 1 in a fully actuated position.



DETAILED DESCRIPTION
Referring to FIG. 1, a launching tool 10 with an interlock system for a cement plug is illustrated in a run in position. The tool 10 employs a wiper mandrel 12 that includes a wiper plug engagement section 14 that provides lateral support of a wiper plug 15 for deployment. The mandrel 12 further includes a plurality of windows 16 therein that are positioned and dimensioned to accept through extension and axial displacement of one or more support dogs 18. Wiper mandrel 12 further includes an interconnection section 20 whereat the wiper mandrel 12 is fixedly connected to a gauge ring mandrel 22. Interconnection is effected by a thread 24, in one embodiment.
Radially outwardly disposed about the wiper mandrel 12 is a release member 26 in the form, in this embodiment, of a shear ring. The shear ring 26 is axially movable on the wiper mandrel 12 sufficiently to shift the one or more dogs 18 from one end 28 to an opposite end 30 of each of the windows 16. This movement can only be accomplished however after the release of a release component 32, such as a shear screw, etc. Further, the release member 26 supports a snap ring 34 in a radially more outward position than it would naturally take to axially lock a collet retention sleeve 36, preventing movement thereof until certain other preconditions within the tool 10 exist (described hereunder). The sleeve 36 restrains a retainer such as a collet 38 from opening until the same preconditions are met. The preconditions are those that cause an interlock system 35 (see FIG. 3 for unobstructed identification) made up of the dogs 18, the release member 26, the release component 32 (both threshold release devices, meaning that a threshold level of strain or pressure, for example must be attained before release occurs) and the snap ring 34, in this embodiment, to be removed as an impediment to the movement of the other components of the tool 10.
It is to be appreciated that radially outwardly of the windows 16 is an open volume 40 that serves two purposes for the disclosed tool 10. The first purpose is to provide room for the one or more dogs 18 to move radially outwardly thereby removing an occlusion of the bore of wiper mandrel 12 (explained further hereunder) and the second purpose is to act as a piston chamber. Promoting the second purpose are o-rings (or other sealing arrangement) 42 that contain fluid thereby allowing pressure buildup in the volumes 40 for hydraulic purpose.
Finally it is noted that an additional release configuration 44 (another threshold release device) releasably attaches the sleeve 36 to the mandrel 12. In one embodiment, the configuration 44 is one or more shear screws.
In operation the tool 10 as introduced above is attached to a string (not shown) and run into a borehole where its function is desired. The tool 10 is run to a selected depth and then an actuation plug 50 (see FIG. 2) is propagated to the tool 10. The actuation plug 50 lands within the interconnection section 20 with a leading profile 52 becoming supported by the one or more dogs 18. The plug 50 includes a number of seal cups 54 that contact and seal against an inside surface 56 of the gauge ring mandrel 22 to wipe cement. Further downhole on the plug 50 is one or more seals 51 that seal on an inside surface 53 (see FIG. 2) of the interconnection section 20. This allows an operator to increase pressure uphole of the plug 50 and force it to move the dogs 18, and thereby the release member 26 downhole. This will release the release component 32 and allow the dogs 18 to be moved into alignment with the open volume 40 simultaneously with the movement of the release member 26, the snap ring 34 will move radially inwardly under its own impetus once the support thereof in the radially outward position is removed (the axial motion of the release member). In another embodiment the snap ring does not have to move on its own impetus. In such embodiment, the snap ring 34 is forced down in to a radially smaller position by movement of the sleeve 36 based upon a chamfered edge 37. The dogs 18 will then move into the volume 40 with the urging of the plug 50 moving downhole. Once the dogs are fully moved into the volume 40, the plug can be hydraulically pushed past the dogs 18 and into sealing relationship with an inside dimension restriction 58 of the wiper mandrel 12. Pressure applied to the plug 50 will then increase the hydraulic load on release configuration 44 due to the fluid acting through the windows 16 into the open volume 40. A review of the drawings and the seals 42 will make clear to one of skill in the art the piston action created. Once the mechanical load on the release configuration 44 reaches a threshold value, the configuration 44 will release allowing the retention sleeve 36 to move into the position illustrated in FIG. 4. It will be appreciated that the sleeve 36 has moved in the uphole direction until making contact with a gauge ring 60 leaving a downhole end 62 of the sleeve 36 uphole of a number of finger ends 64 of the collet 38 free to deflect radially outwardly. The radially outward deflection of the finger ends 64 disengages a number of finger profiles 66 from a groove 68 in a wiper plug tail 70. A comparison of FIGS. 3 and 4 in this location will be edifying. Once the collet 38 releases from the tail 70, both the actuation plug 50 and the wiper plug 15 are free to move together under hydraulic pressure as desired.
The tool as described eliminates possible pressure spike based unintended wiper plug release as the wiper plug release cannot be completed until the interlock system has released. Since the interlock system provides a mechanical lockout, pressure even higher than that required to release prior art wiper plugs will have no effect until the interlock is first released by the actuation plug and discussed sequence.
While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.

## Claims

1. A launching tool with interlock system for a downhole cement plug comprising:
a mandrel having one or more windows therein;
an interlock system disposed at the mandrel, the interlock system having a release member;
one or more dogs extending from the release member through the one or more windows; and
a collet disposed at the mandrel and restrained by a restrainer, the restrainer releasable only after release of the interlock system.

2. A launching tool as claimed in claim 1 wherein the release member is a shear ring.

3. A launching tool as claimed in claim 1 wherein the interlock system further comprises a release component.

4. A launching tool as claimed in claim 3 wherein the release component is one or more shear screws.

5. A launching tool as claimed in claim 1 wherein the collet is engaged with a wiper plug prior to a release sequence of the interlock system, the collet preventing release of the wiper plug from the launching tool.

6. A launching tool as claimed in claim 1 wherein the mandrel and a collet retention sleeve define a piston chamber that participates through fluid pressure in the release of the interlock system.

7. A method for wiping a tubular after cementing comprising:
running a wiper plug launching tool according to claim 1 to a selected location;
pumping cement through the wiper plug;
running an actuation plug;
landing the actuation plug in the launching tool;
causing a sequence of events resulting in release of the wiper plug;
landing the actuation plug in the wiper plug; and
pumping the wiper plug downhole.

8. A method as claimed in claim 7 wherein the sequence of events includes mechanical events.

9. A method as claimed in claim 7 wherein the sequence of events includes hydraulic events.