Patent Publication Number: US-10329868-B2

Title: Releasably locked debris barrier for a subterranean tool

Description:
FIELD OF THE INVENTION 
     The field of the invention is debris barriers for subterranean tools and more particularly barriers that set and lock with the tool with the lock being releasable when the tool is unset and retrieved. 
     BACKGROUND OF THE INVENTION 
     Subterranean barriers such as packers normally have a sealing element and one or more assemblies of slips that are urged into contact with a surrounding borehole wall when pushed on ramps referred to as cones. Such barriers can be left in position for a very long time and as result the debris that is in well fluids that can come from the formation or from the borehole wall can over time precipitate down to the set sealing element and the slip assembly that is located above the sealing element. Many releasable packers release with a pickup force that shears a breakable member to allow the assembly of the seal and the slips and associated cones to stretch out. This movement allows the slips to ride down the cones and retract away from a gripping relationship with the surrounding tubular that defines the borehole wall. 
     To keep parts that need to move with respect to each other clear of debris, packers have been provided with debris barriers that span an annular gap between the packer outer assembly and the surrounding borehole wall. These debris barriers are usually folding structures when viewed in section whose ends are brought together to bring the folds together with the result that the barrier extends radially to span the surrounding gap to the tubular defining the wellbore wall. These devices are deployed after the packer sets and set down weight is applied. One problem with such designs is that due to loading changes or thermal effects that alter the length of the string, the amount of set down weight is variable and can actually disappear. Other designs compress the debris barrier as a result of the same piston movement that sets the slips and seal. However, even in these instances with loading to a predetermined level in a given direction, the compressive force that holds the debris barrier extended can be overcome which leads the barrier to retract and pass debris. This can lead to retraction of the barrier and admission of the debris onto closely fitting relatively moving parts which can then result in their jamming. When that happens the packer may not release and a milling operation could result to get the packer out of the hole. One attempt to address this problem is to unleash the potential energy of a spring against the barrier after the packer is set to help insure that the debris barrier stays folded even when the amount of set down weight on the debris barrier is sharply reduced or eliminated due to thermal effects or other operational reasons. Such a design is shown in U.S. Pat. No. 7,604,048. Fixed dimension debris barriers are shown in U.S. Pat. No. 8,881,802. A weight set debris barrier is shown in U.S. Pat. No. 8,474,522. Axially shifted foam sleeve that are brought into a zone of smaller dimension to span an annular gap are shown in U.S. Pat. No. 8,939,201. 
     What is needed and provided by the present invention is an articulated debris barrier that is selectively extended to span a surrounding annular gap when a tool such as a packer is set. The extended position of the debris barrier is then releasably locked in when the tool such as a packer is in service. When the tool is released for retrieval the lock on the debris barrier is released so that it can be retracted. This allows the barrier and the tool to be removed without hanging up or damaging the debris barrier. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims. 
     SUMMARY OF THE INVENTION 
     An articulated debris barrier folds on itself to extend radially to span a surrounding annular gap when the tool associated with it is set. The debris barrier can be used with a packer or bridge plug. The set position of the packer or plug is locked and another lock holds the extended position of the debris barrier. The debris barrier lock can be a snap ring that extends into a groove brought into alignment with it during the setting. Alternatively the lock for the debris barrier can be a body lock ring. In either case, release and retrieval of the packer or plug involves undermining of the locking feature for the debris barrier so that the debris barrier can extend while retracting from the borehole wall so that the barrier and the associated packer or plug can be removed together. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of the snap ring locking debris barrier in the run in position; 
         FIG. 2  is the view of  FIG. 1  with the debris barrier extended and locked before the slips and seal are extended; 
         FIG. 3  is the view of  FIG. 2  with the slip and seal in the set position; 
         FIG. 4  is the view of  FIG. 3  with the debris barrier extended and retracted before the slip is released; 
         FIG. 5  is a section view in the run in position showing the debris barrier and the body lock ring locking system for the debris barrier; 
         FIG. 6  is the view of  FIG. 5  showing the debris barrier extended and locked into position; 
         FIG. 7  is the view of  FIG. 6  with the debris barrier relaxed when the packer set is released; 
         FIG. 8  is an assembly drawing of the packer in  FIG. 6  shown in the debris barrier set position; 
         FIG. 9  is the view of  FIG. 8  with the debris barrier and the packer in the released position and ready for retrieval. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  a packer  10  of a known design has a sealing element  12  as well as a backup ring  14  and upper slips  16  that ride on a cone  18 . A debris barrier  20  is mounted between end rings  22  and  24 . As rings  22  and  24  are brought toward each other a groove  26 , a new feature of the packer  10 , is moved into alignment with a c-ring or snap ring  28  that is biased toward the groove  26 . This is shown in the  FIG. 2  where ring  24  has moved in the direction of arrow  30  and cannot come back in the direction of arrow  32 . The debris barrier is now against the surrounding tubular  34 . At this point with the barrier  20  against the tubular  24  additional axial compression of the outer assembly of the packer can take place which results in extension of the upper slip  16  followed by the seal  12  and then a lower slip that is not shown. This can be seen when comparing  FIG. 3  to  FIG. 2 . Release of the packer is accomplished with an upward pull to break a shear ring that is not shown which then allows the outer assembly of the seal and slips that surround it to extend in a downhole direction to then let the slips and seal radially retract for retrieval. As shown in  FIG. 4  the groove  26  has shifted with ring  24  to retract the debris barrier  20 . Next the slip  16  will resume the  FIG. 1  position as the cone  18  relaxes away due to movement in the direction of arrow  32 . Although not shown, the slips and low slip assembly will then relax so that the packer can be removed from the borehole. From what is seen in the FIGS. the movement from the ste position of  FIG. 3  to the retrieved position of  FIG. 4  is characterized by the upper slip cage moving up to contact the slip  16 , which provides the back-up needed to collapse the snap ring  28  into its groove. The top of the packer  12  and the internals then move up to close the gap between part  24  and the load ring  25  continuing up until the upper slip cage  27  makes contact with the slip  16  again. The upper slip cage  27  then, in  FIG. 4 , pulls the slip  16  away from the upper cone  18  allowing the element system to relax. 
     Note the shoulders  40  and  42  have separated in  FIG. 4  as the debris barrier has relaxed. The compression of the debris barrier when set is limited by the contact between shoulders  40  and  42 . When these two shoulders contact the snap ring or equivalent  28  lines up with groove  26 . Thus the set position of the debris barrier  20  can be locked against relaxation until a shear force is applied to release the locked in compressive force on the outer assembly. When that happens the lock for the debris barrier is defeated to allow the barrier  20  to extend axially with retracting radially as the snap ring  28  is forced back into its original groove and out of groove  26 . Through parts shouldering out the removal force for the released packer is not transmitted through the debris barrier  20 . One or more openings  44  can be provided in the debris barrier  20  to prevent liquid locking. The debris barrier  20  is preferably rubber or another resilient material that is compatible with well materials and temperatures. 
       FIGS. 5-7  show an alternative embodiment in the run in, set and released positions respectively.  FIGS. 8 and 9  show the debris barrier in the set and retrieved positions in the context of a complete packer assembly drawing. The debris barrier  60  is extended by bringing rings  62  and  64  together when setting the packer. As ring  64  moves up in the direction of arrow  66  it takes with it lock ring  68  that can ratchet up in the direction of arrow  66  but cannot move in the opposite direction of arrow  70 . Shoulders  71  and  72  are spaced apart in the set position of  FIG. 6  and are engaged for the retracted position of the barrier  60  to allow retrieval as shown in  FIG. 7 . When the packer seal and slips are released, as will be explained below, the lock ring  68  does not release. Instead a shear release of the packer allows rings  64  and  74  to move in tandem with the lock ring  68  so that the debris barrier can extend axially while retracting radially. This movement continues until shoulders  71  and  72  engage as shown in  FIG. 7  as the packer seal  12  extends in an uphole direction. The barrier  60  can have one or more openings  76  to prevent liquid locking as the set position of  FIG. 6  is accomplished. Openings  78  accomplish a similar purpose. A shear pin  80  can hold ring  62  and  74  together until the release of the packer where it breaks as shown in  FIG. 7 . 
       FIG. 8  shows the assembly of the entire packer which apart from the components described in  FIGS. 5-7  is of a known design. The release of the packer is accomplished by shearing l-shaped shear ring  90 . Setting is accomplished with pressure on piston  92  which pushes up lower slips  94  and cone  96 , seal  98 , cone  100 , upper slips  102  and ring  64  against barrier  60  against ring  62  which cannot move. As a result of axial force from piston  92  the above parts below ring  62  move up. Lock ring  104  ratchets to hold the ultimate set position. As the piston  92  moves the debris barrier  60  is extended and its extended position locked by lock ring  68 . Continued movement of piston  92  pushes cone  100  under upper slips  102  and that extends the slips  102  to the surrounding tubular. Thereafter, the seal  98  is set and then the slips  94  are pushed up ramp  96  thus holding the seal  98  in its set position against differential forces in opposed directions. The set of the slips  94  and  102  and the seal  98  are separately locked by the lock ring  104 . As shown in  FIG. 9  release is accomplished with a force applied to mandrel which defeats the lock ring assemblies  104  to release the packer and  68  to release the debris barrier  60 . Again, the basic packer as described in  FIGS. 8 and 9  is known apart from the application of the debris barrier and the locking of the debris barrier in a releasable manner. While the locking for the debris barrier  60  is accomplished with a lock ring assembly that engages when the packer is set and releases when the packer is released, other types of releasable locks are contemplated. To facilitate the packer design, the debris barrier  60  is extended and locked into position first as the rest of the packer components are then actuated and releasably locked. Other operating orders are contemplated. Of course, preferred placement of the barrier such as  60  is uphole from the packer components to keep falling debris from the borehole wall or in the drilling or well fluids out of the close fitting components that could jam. 
     While the context of the debris barrier has been described as with packers or bridge plug, other applications are envisioned such as valves, cutters, mills or any other tools with close fitting relatively moving components that could jam with debris found in a borehole. Debris barriers that set in a variety of ways are contemplated. These ways are with set down weight or with an uphole force using a setting piston or in either direction with a tool run into the borehole. The sequence can be the debris barrier is set with, before or after the tool is operated. The barrier can be set with motion in the same or the opposite direction than is used to set the tool. In essence the set position of the debris barrier is releasably locked, however, if the tool is not to be retrieved then the lock on the set position need not be releasable. The debris barrier is protected from tensile stress in the run in and retrieval of the packer or bridge plug with the debris barrier retracted. 
     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: