Abstract:
A valve assembly for a plug to close off a zone in the well for further treatment above the plug features a valve member initially pinned in an open position where flow up to a predetermined level can move through without dislodging the valve plug to move to its associated seat. If the perforating gun misfires a replacement gun can be run in with flow as the plug is still retained in the position for flow through the plug. On the other hand flow around the plug above a predetermined level will shear retainers for the plug and let the plug land on its seat closing flow in a downhole direction for treatment.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is claims priority from U.S. Provisional Patent Application Ser. No. 62/232,179, for “Flow Activated Valve”, filed on Sep. 24, 2015, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of the invention is flow sensitive valves inserted as a component of frac plugs or seat assemblies and more particularly valves used in plug and perforate equivalent systems where the valve stays open at low flow rates and is selectively closed to flow in a downhole direction from surface provided flow. 
       BACKGROUND OF THE INVENTION 
       [0003]    There are many forms of fracturing being used and one of those methods is known as plug and perforate. In this method a zone that has already been treated is isolated with a plug and a perforating gun is released from the plug and repositioned for perforating. With the zone previously treated now isolated with the plug the newly perforated zone can be fractured through the newly made perforations above the plug. 
         [0004]    The plug designs in the past have involved dropping or pumping a ball onto a seat from surface after the guns are out of the hole, in one form of plug valve. The problem with this design is that it takes time and water to get the ball pumped to the seat. 
         [0005]    Other valve designs for frac plugs have been proposed to avoid sending down a ball to land in a seat. These designs involve a caged ball that lifts off a seat when the gun is advanced with the cage retaining the ball. Flow in the downhole direction seats the ball on the seat to prevent flow. This means if the gun fails to fire there is no way to use flow to deliver a replacement gun as any such flow in the downhole direction seats the ball on the seat. 
         [0006]    Yet other types of spring biased check valves have been suggested but they too will shut with flow in the downhole direction leaving the same problem of how to run in a replacement gun if the original gun fails to fire. 
         [0007]    U.S. Pat. No. 5,564,471 illustrates a fuel delivery breakaway valve that closes off flow in the hose that separates with a car that drives off and blocks flow out of the hose remnant going back out as well as blocking flow out of the portion still attached to the pump. The opposed check valves are actuated with physical separation of the housing. Automobile fuel nozzles also have a valve member that is resettable that is actuated by backpressure from the tank being filled to avoid overfilling the gas tanks while then resetting to allow pumping additional fuel. 
         [0008]    U.S. Pat. No. 6,394,180 shows a ball sitting on a spring with a covering cage to retain the ball to a frack plug. On increase in flow the ball compresses the spring to land on the seat until the flow is reduced and the spring can then raise the ball off the seat to reopen the passage. The ball is not retained in the uphole direction until it hits the surrounding cage. This design has the potential problem of the ball jamming around the spring rather than seating off on the seat for a clean seal. Other problems include; 1. Springs are made of hardened steel and aren&#39;t easily millable. Quick mill-out time is essential. 2. The force on the ball due to flow will change as it moves in the passage due to compressing the spring. This adds variability to the predetermined flow rate to close the valve. 
         [0009]    What is needed and addressed by the present invention is a valve for a plug in a plug and perforate context that is disposed in the plug and has a selectively secured valve member that allows bypass flow and remains in the open position if the gun fails to fire so that a replacement gun can be run in with flow through the open valve. The plug member is selectively released with raising the flow rate through the plug to release the valve member to land on its seat to allow subsequent fracturing or other treatments such as stimulation or acidizing, for example. A backup seat is provided for dropping an object if for any reason the plug member fails to release and move to its seat. These and other aspects of the present invention will be more readily apparent from a review of the description of the preferred embodiment and the associated Figure while recognizing that the full scope of the invention is to be determined by the appended claims. 
       SUMMARY OF THE INVENTION 
       [0010]    A valve assembly for a plug to close off a zone in the well for further treatment above the plug features a valve member initially pinned in an open position where flow up to a predetermined level can move through without dislodging the valve plug to move to its associated seat. If the perforating gun misfires a replacement gun can be run in with flow as the plug is still retained in the position for flow through the plug. On the other hand flow around the plug above a predetermined level will shear retainers for the plug and let the plug land on its seat closing flow in a downhole direction for treatment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0011]      FIG. 1  shows the valve member in the open position when running in while retained by one or more shear pins; 
           [0012]      FIG. 2  shows a valve member retained by extending fingers; 
           [0013]      FIGS. 3-5  show views of a spherical valve member retained by a wire; 
           [0014]      FIG. 6  shows a valve member retained by collet fingers; 
           [0015]      FIG. 7  shows a ball retained by a ring with extending fingers; 
           [0016]      FIG. 8  shows a ball retained by a plurality of fixed supports and a movable support; 
           [0017]      FIG. 9  shows a ball retained by a plurality of movable supports; 
           [0018]      FIG. 10  is a rotated view of  FIG. 8  showing the passages for flow between the fixed supports; 
           [0019]      FIG. 11  shows a j-slot variation of the control for the valve member in the open position; 
           [0020]      FIG. 12  is the view of  FIG. 11  in the closed position for the valve member. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    Referring to  FIG. 1  the valve body  5  retains a primary seat  4  for the plug member  3  that has a conforming shape at its leading end to the seat  4 . One or more shear pins  2  are supported from the backup seat  1  to hold the plug member  3  in the position shown. A bypass passage  6  allows flow in the direction of arrow  7  when the pins  2  have not sheared. Nothing moves below a predetermined flow rate that puts less force on the plug  3  than the capacity of the shear pins  2 . Those skilled in the art will realize that what is not illustrated is the plug that is initially set that has a sealing element ands slips. Typically this plug with the illustrated valve assembly is delivered with a perforating gun that supports the plug. The perforating gun is also not shown. The setting of the plug releases the gun from the plug so that the gun can be placed where needed and fired. Also those skilled in the art will realize that the valve can be incorporated in ball seat assemblies that are installed in pre-drilled baffles or seats in the casing and act and perform equivalently to a plug and perforate operation. 
         [0022]    If the gun fails to fire the position of the components in  FIG. 1  is unchanged. This means that passage  6  remains open to allow a subsequent run with a replacement gun to be accomplished with flow through the open passage  6 . 
         [0023]    If the gun does fire then one possibility is that the concussion from the firing of the gun will create a sufficient force to shear the pins  2  to allow the plug member  3  to advance and seal against the primary seat  4 . Another way to shear the pins  2  is to simply increase the flow rate in the direction of the arrow  7  until enough force is applied to pins  2  to shear them and get the same result. The flow increase can be at the same time the gun is fired but is preferably later because it is necessary to know that the gun has fired before shearing the pins  2 . As previously stated the firing of the gun may not shear the pins  2 . There may be a long distance between the gun and the plug member  3  in some applications so that the mere firing of the gun will not shear the pins  2 . 
         [0024]    If for any reason the pins  2  do not release the plug  3  then a ball not shown can be landed on the secondary seat  1  to close off the plug to allow treatment above in the known manner. 
         [0025]    While the retaining of the plug  3  can be done with one or more shear pins other temporary retaining devices that can selectively release are also contemplated such as shear rings, Belleville washer stacks or snap rings to name a few options. The bypass flow through passage  6  can be around the outside of the plug  3  or through the plug  3 . Typically after the pins  2  are sheared the pressure that sheared them is continually applied to keep the plug  3  against the seat  4 . Seat  1  is used to fixate seat  4  in body or mandrel  5  by supporting the lower end of the seat  4  on an internal shoulder in the valve body  5 . The treatment under pressure against the plug  3  seated on seat  4  can vary to include such events as fracturing, acidizing, conditioning or other pressure dependent procedures needed for completion. In this sense reference to treatment in this application is intended to incorporate all such pressure dependent procedures in a completion process. 
         [0026]    As an alternative to the valve member  3  landing on seat  4  to close flow in one direction the closing off of flow can be done indirectly using movement of the valve member  3  that in turn allows a flapper to fall closed blocking flow in a downhole direction. In the run in position the fixated valve member abuts the open flapper and movement of the valve member  3  downhole frees the flapper to rotate  90  degrees to the closed position. The flapper location can be downhole of seat  1  so that seat  1  can still be available as a backup, if the flapper fails to close. Body  5  and seat  4  can be one piece or more than one piece. 
         [0027]    Remote actuation is alternatively envisioned with the use of electromagnetic pulses, pressure pulses, pressure or electromagnetic pulses generated from the firing of the gun, or using a passage  6  large enough to provide no significant resistance at 15 BPM or less for example and more significant resistance at higher flows to be used to trigger a timer for the release of the valve member  3 . 
         [0028]    The valve member  3  can comprise a seat assembly or it can be disintegrating or dissolvable. 
         [0029]      FIG. 2  is an alternative embodiment using collet fingers  10  that have gaps  12  to retain an object such as a ball  14  away from a seat to allow flow under certain conditions before the fingers  10  no longer grip and the ball  14  lands on the seat  14 . At that point flow in the direction of arrow  18  stops. The release of ball  14  can occur with increasing flow rate, thermal exposure, chemical attack or disintegration of the fingers  10  to name a few examples. Another option is to install a band  20  around fingers  10  that can hold support  22  in place until enough force is applied with flow, for example, to break the band  20  and release the ball  14  to land on seat  16 . 
         [0030]      FIGS. 3-5  show different views of another embodiment where a ball or other object  30  is held away from a seat  32  by a wire  34  that can be copper or brass so that flow can pass through openings  36  bypassing ball  30  until the wire  34  fails from a variety of causes and advances onto seat  32  to shut off flow in the direction of arrow  38 . Wire  34  can be failed by increasing flow as well as the other options listed for fingers  10  above. 
         [0031]      FIG. 6  employs flexible collet fingers  40  retained in one or several grooves  42  that support a hemispherical leading end  44  that lands on the seat  46  after increased flow through gaps  48  between fingers  40  allows them to spring out of grooves  42 . As mentioned before with regard to fingers  10  other mechanisms are envisioned for release that allows end  44  to land on the seat  46 . Inclined surfaces  50  and  52  promote release on increasing flow while transversely oriented surfaces  54  and  56  resist movement in the uphole direction indicated by arrow  58 . 
         [0032]      FIG. 7  illustrates a ring  60  with spaced extending fingers  62  that define gaps  64  in between. Ball  66  is retained on fingers  62  so that flow can go around the ball  66  through the gaps  64  until a predetermined flow rate is reached at which point the ball  66  pushes through the fingers  62  to land on the seat  68 . While fingers  62  are shown oriented in a downhole direction they can also be oriented uphole or perpendicular to passage  70 . The ring  60  can be complete or split as shown in the associated groove  72 . If the ring is split the fingers  62  will move radially instead of or in addition to moving axially in a flexing motion. In another alternative the fingers can be eliminated when used with a gapped snap ring. The gap allows flow up to a predetermined value while excess flow simply expands the ring radially to let the ball pass. As another option the ball can be soft enough so that on flow buildup beyond a predetermined value, the ball  66  simply is forced through its support structure to land on the seat  68 . The ball  66  can be trapped between fingers  62  and seat  68  after being forced past fingers  62 . 
         [0033]      FIG. 8  shows a ball retained in part on one or more spaced ledges  82  that are fixed and a movable support such as a ball  84  biased by a spring  86  in a bore  88  transverse to passage  90 . When a predetermined flow is reached the force on the ball  80  increases to the point of compressing spring  86  to retract ball  84  to allow ball  80  to pass to seat  92 . Ball  84  can be retained against falling into passage  90  when in the extended position to support ball  80 . In  FIG. 9  the fixed support(s) is eliminated in favor of a second sprung ball assembly to the one shown in  FIG. 8 .  FIG. 10  is a rotated view of  FIG. 8  showing the spaced supports  82  that are fixed and flow passages  92  that exist in between the supports  82 . 
         [0034]    Those skilled in the art will appreciate that the various illustrated embodiments allow flow in a given direction through a plug passage and once closed by events in a passage therethrough stay closed to flow in the plug passage in the same direction. The housing for the valves remains intact and requires no physical separation to trigger valve member movement. Instead, valve movement occurs with increased flow or other means operative in the passage to release or remove the valve member. 
         [0035]      FIG. 11  shows a valve member  100  having spaced extending members  102  with a pin  104  in at least one end  106  of the extending members oriented to ride in j-slot  108 . Longitudinal slot  110  is shorter than adjacent slot  112  so that in  FIG. 11  the valve member is held off the seat to allow flow to pass between the extending members  102 . In the  FIG. 12  position the valve member  100  contacts the seat  114  due to the longer length of slot  112 . A force in the direction of arrow  116  can come from formation flow or a spring or equivalent biasing device. The j-slot can have just two slots  110  and  112  to allow it to be run in open and then closed when needed so that valve member  100  stays on seat  114  once landing on it. The initial open position can be selectively locked to avoid early actuation to the closed position. The lock can be a breakable or disintegrating member that will resist forces that would otherwise advance the valve member  100  before it is put in the desired location. In a frack plug application there is no need to go from the  FIG. 12  closed position back to the  FIG. 11  open position. However, in other applications the j-slot assembly can be configured to allow multiple cycles of closing and then reopening if needed. The connection of the valve member  100  to the j-slot  108  can also help resist relative rotation especially when the j-slot is not continuous to facilitate milling out the valve assembly when used with an associated frack plug. 
         [0036]    The above description is considered illustrative of the invention and those skilled in the art will appreciate that the claims below comprise the full scope of the invention.