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.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    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 
       [0002]    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 
       [0003]    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. 
         [0004]    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. 
         [0005]    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 
         [0006]    Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
           [0007]      FIG. 1  is a cross section view of a launching tool as disclosed herein in a run in position; 
           [0008]      FIG. 2  is a cross section view of the tool illustrated in  FIG. 1  with an actuation plug disposed therein; 
           [0009]      FIG. 3  is a cross section view of the tool as illustrated in  FIG. 1  in a lockout released position; 
           [0010]      FIG. 4  is a cross sectional view of the tool as illustrated in  FIG. 1  in a fully actuated position. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    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. 
         [0012]    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 . 
         [0013]    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. 
         [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    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.