Abstract:
A shifting sleeve has differential piston areas so that applied pressure displaces the sleeve against spring bias, which preferably is a series of Belleville washer stacks associated with modular mandrel components, to obtain the desired opposing force to the movement initiated with pressure applied to differential piston areas. An indexing feature is located between the sleeve and the mandrel passage wall and on a predetermined number of cycles disables the Belleville washer stacks from biasing the sleeve in an opposed direction as when pressure is applied. At this time the pressure in the mandrel acting on the differential piston area simply shifts the sleeve to open a lateral port so that fracturing through the cement that was earlier placed with the port closed can take place.

Description:
PRIORITY INFORMATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/651,878 filed on Oct. 15, 2012. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of the invention is a pressure actuated sleeve used in a cementing assembly that is responsive to tubing pressure to open a port and more particularly a sleeve that has differential piston areas where application and removal of pressure cycles the sleeve on a j-slot to allow string pressure testing at a higher pressure than a pressure that releases a bias on the sleeve to allow the differential piston area to shift the sleeve to open a port at a lower pressure than the string integrity testing pressure. 
       BACKGROUND OF THE INVENTION 
       [0003]    Prior sleeves that have been deployed in cementing service have been based on the concept of providing opposed piston areas exposed to tubing pressure that are of different dimensions so that raising the tubing pressure will create a sufficient net force to in theory overcome seal friction and move the sleeve to the open position. One such design is the Halliburton Initiator Sliding Sleeve that has a larger upper seal diameter than a lower seal. Raising tubing pressure creates a net differential force and the piston is allowed to move because there is an atmospheric chamber between the upper and lower seals. The problem is that to get the lower seal to be smaller than the upper seal to create the desired net force in the needed direction, the wall of the sleeve adjacent the lower seal and the atmospheric chamber has to be reduced so that the sleeve can shift while the volume of the atmospheric chamber is reduced. 
         [0004]    The wall of the sleeve in the area of the atmospheric chamber sees substantial differential pressure and can flex or bend. When that happens the sleeve gets stuck and the desired port opening in the housing fails to occur. 
         [0005]    Apart from these designs there are sleeves that respond to tubing pressure with an associated piston that is open on one side to tubing pressure and on the other side to annulus pressure. Such a design is illustrated in US Publication 2011/0100643. This design cannot be used in cementing applications as the filling up of the annulus with cement can block access to annulus pressure. Furthermore, there is a leak path potential from the tubing to the annulus through a piston seal leak. 
         [0006]    Various pressure operated sleeves for downhole use are shown in USP and Publications: U.S. Pat. Nos. 7,703,510; 3,662,834; 4,330,039; 6,659,186; 6,550,541; 5,355,959; 4,718,494; 7,640,988; 6,386,289; US 2010/0236781 A1; U.S. Pat. No. 5,649,597; 5,044,444; 5,810,087; 5,950,733; 5,954,135; 6,286,594; 4,434,854; 3,189,044; 6,948,561; US Publication 20120006553; U.S. Pat. No. 8,171,994; US Publication 2011/0114324; US Publication 2012/0186803; U.S. Pat. Nos. 4,991,654; 5,325,917; US Publication 2012/0048559; US Publication 2011/0278017; U.S. Pat. Nos. 6,308,783 and 6,722,439. 
         [0007]    More noteworthy with respect to the present invention is Jasser U.S. Pat. No. 7,841,412 that couples a sleeve with a flapper at the top that closes with pressure delivered from above the closed flapper to then cycle the sleeve using a j-slot so that ultimately a lateral port is opened or closed. The application is to prevent fluid loss during treatment and the design is impractical in a cementing application. 
         [0008]    What is needed and provided by the present invention is an actuation technique for a sliding sleeve to open a port that responds to tubing pressure but addresses the flexing or bending problem associated with prior designs so that reliable movement of the sleeve is obtained. In the preferred embodiment the sleeve has differential piston areas so that applied pressure displaces the sleeve against spring bias which preferably is a series of Belleville washer stacks associated with modular mandrel components to obtain the desired opposing force to the movement initiated with pressure applied to differential piston areas. An indexing feature is located between the sleeve and the mandrel passage wall and on a predetermined number of cycles disables the Belleville washer stacks from biasing the sleeve in an opposed direction as when pressure is applied. At this time the pressure in the mandrel acting on the differential piston area simply shifts the sleeve to open a lateral port so that fracturing through the cement that was earlier placed with the port closed can take place. 
         [0009]    Those skilled in the art will better appreciate more aspects of the invention 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 by the appended claims. 
       SUMMARY OF THE INVENTION 
       [0010]    A shifting sleeve has differential piston areas so that applied pressure displaces the sleeve against spring bias, which preferably is a series of Belleville washer stacks associated with modular mandrel components, to obtain the desired opposing force to the movement initiated with pressure applied to differential piston areas. An indexing feature is located between the sleeve and the mandrel passage wall and on a predetermined number of cycles disables the Belleville washer stacks from biasing the sleeve in an opposed direction as when pressure is applied. At this time the pressure in the mandrel acting on the differential piston area simply shifts the sleeve to open a lateral port so that fracturing through the cement that was earlier placed with the port closed can take place. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of the ported sub shown in the run in position; 
           [0012]      FIG. 2  is a view of the indexing mechanism under applied pressure that pushes the sliding sleeve to a point where the pin engages in the j-slot to stop the movement; 
           [0013]      FIG. 3  shows the removal of applied pressure and the springs returning the sleeve to a point short of the slot hitting the pin; 
           [0014]      FIG. 4  is a view of sleeve movement down a long slot that allows the spring assembly to disengage from the sleeve so that the port can open; 
           [0015]      FIG. 5  is a view at the sleeve upper end during run in showing a shear pin intact and a ratchet mechanism deactivated; 
           [0016]      FIG. 6  shows the travel stop when applied pressure is removed and the port is still covered by the sleeve; 
           [0017]      FIG. 7  shows the position of the sleeve ready to open the port but before any sleeve movement that exposes the port; 
           [0018]      FIG. 8  shows the spring retainer moved into a recess to disengage the spring assembly from biasing the sleeve; 
           [0019]      FIG. 9  shows the sleeve moving off the port and a ratchet lock engaging to hold the open port position; and 
           [0020]      FIG. 10  shows the spring assembly retainer in a housing recess so that a bias force can no longer be applied to the released sleeve to allow the released sleeve to shift open under differential loading from applied pressure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    Referring to  FIG. 1  the ported sub  10  is part of a cementing assembly supported on a string that is not shown and leading to a bottom hole assembly (BHA) that has a cementing shoe and landing collars for wiper darts that aid in displacing cement to the surrounding annulus  12  of a borehole  14 . When the cementing is done the port or ports  16  can be opened with shifting of sleeve assembly  18  so that the formation can be fractured through the set up cement. 
         [0022]    The sub  10  allows pressure testing the string supporting the sub  10  at a higher pressure than will ultimately be needed to open the ports  16  for a subsequent frac of the formation through the cement  20 . 
         [0023]    The ported sub  10  has a top sub  22  and a bottom sub  24 . Each of these subs can be in one or more parts secured together generally by being threaded together. The top sub  22  has the ports  16  and the bottom sub  24  houses the indexing assembly  26  as will be explained in more detail below. In between the subs  22  and  24  are one or more modules  28  that have threaded ends  30  and  32  so that one or more modules can be stacked.  FIG. 1  happens to show five modules  28  but fewer or more can be used depending on the desired force to push the sleeve assembly  18  in an uphole direction, which is toward the left end of  FIG. 1 . The modules can be identical or different and are each preferably equipped with a stack of Belleville washers as also seen better in  FIG. 6 .  FIG. 8  shows a lowermost module  28  that is adjacent the bottom sub  24 . Each module  18  has a shoulder  36  on which the stack  34  bears for pushing the sleeve assembly  18  to the left in an uphole direction. The opposite end  38  of each stack  34  is retained to the sleeve assembly  18  with an end ring assembly  40  that comprises one or more dogs between two rings that extends into a groove  42  in the outer wall  44  of the sleeve assembly  18 . Release groove  46  is in the body  48  of the module  28 . Movement of the sleeve assembly  18  to the right or downhole takes with it end ring  40  and compresses the stack  34 . Movement in that direction is stopped short of end ring  40  reaching release groove  46  by the indexing assembly  26  as will be described below. Once end ring  40  gets into groove  46  it is liberated from being in registry with groove  42 . As long as end ring  40  is in groove  42  movement of the sleeve assembly  18  will compress the stack  34 . Note that a stack of Belleville washers is preferred because it can deliver a large force after being compressed a relatively short distance and can apply that force constantly when the movement direction of the sleeve assembly  18  is reversed as the applied pressure from the surface is cut off. Other types of biasing devices are contemplated such as other types of springs or a variable volume with a compressible gas trapped inside, for example. 
         [0024]    Referring again to  FIG. 1  it can be seen that diameter D 1  is larger than diameter D 2  so that when pressure is applied to the sleeve assembly  18  there is a net unbalanced force toward the downhole direction illustrated by arrow  50  in  FIG. 2 . This is because the piston area defined by seal pairs  52  is larger than the piston area defined by seal pairs  54 .  FIG. 2  shows how the travel limit with pressure from uphole is defined using the indexing assembly  26  with the bottom sub  24  removed for clarity. The indexing pin  56  extends from fixed sleeve  60  held in the bottom sub  24 . Sleeve  60  in turn surrounds sleeve  58 , as best seen in  FIG. 8 . Sleeve  58  reciprocates with sleeve assembly  18  and turns on its own axis as the j-slot pattern  64  is encountered by the pin  56 . Sleeve  60  is pinned at  62  to the bottom sub  24  to prevent rotation. Those skilled in the art will appreciate that there are a plurality of short slots  66  and  68  that are adjacent each other and represent movement of the sleeve assembly  18  against the stack  34  and upon removal of applied pressure a reverse movement of the sleeve assembly  18  under the force of the stack  34  in each module  28 .  FIG. 2  shows the downward travel limit of the sleeve assembly  18  under a net force from applied pressure from uphole operating on the differing piston areas represented by diameters D 1  that is larger than D 2 . That travel limit happens when movement of the sleeve assembly  18  takes sleeve  58  down to a point where the slot depth at  66  engages the fixed pin  56 . The downward travel limit shown in  FIG. 2  happens each cycle until the long slot  70  comes into alignment with pin  56 . 
         [0025]    On the other hand when the stacks  34  push the sleeve assembly  18  in the uphole direction as shown in  FIG. 3  the short slot  68  is not brought forcibly against the stationary pin  56  to avoid overstress of the pin  56 . Instead the uphole movement under the bias of the stacks  34  comes to a stop when end ring  40  hits shoulder  72  in each module  28  as shown in  FIG. 6 . 
         [0026]      FIG. 4  shows what happens when pressure applied from above the sleeve assembly after a predetermined number of cycles of applying pressure and removing pressure from above allows the long slot  70  align with pin  56 . As shown in  FIG. 4  the slot  70  allows an added movement of the sleeve assembly  18  in the direction of arrow  50 . What this does is shown in  FIG. 4 . During the short cycles of movement of the sleeve assembly  18  the surface  74  has kept the end ring  40  trapped in groove  42  of the sleeve assembly  18 . With the long stroke the end ring  40  can move into alignment with groove  46  of housing  48  of each module  28  to allow the end rings  40  the ability to retract away from sleeve assembly grooves  42  effectively disabling the stacks  34  from any further ability to push the sleeve assembly in the uphole direction when the applied pressure from uphole is subsequently removed. However, now any pressure in the sleeve assembly will still create a net force on it in the direction of arrow  50  which will now result in opening the port or ports  16 .  FIG. 7  shows the sleeve assembly just before it opens to uncover ports  16 . There is a fixed ratchet sleeve  76  that is still not in contact with a ratchet surface  78  on the sleeve assembly  18 . When the ports  16  open, as in  FIG. 9 , the ratchets line up to prevent reclosing of the ports  16 . The travel stop for the sleeve assembly  18  when the ports  16  open is shoulder  80  on the topmost module  28 .  FIG. 10  shows the lower end of the sleeve assembly  18  when ports  16  are open and how the end ring  40  has been allowed to retract from the sleeve assembly  18  to take the stacks  34  out of play as a biasing force on the sleeve assembly  18 . Note how groove  42  has moved downhole with respect to groove  48  that now holds the end rings  40  in each module  28 . 
         [0027]      FIG. 5  illustrates the shear pins  82  that hold the sleeve assembly from moving during cementing through the sleeve assembly  18  with the ports  16  closed. After the cementing is done a higher pressure than seen during cementing is applied to the sleeve assembly  18  to break the pins  82  as the pressure is further raised to the desired test pressure. After that the needed amount of pressure application and removal cycles are applied until such time as the ports  16  are open in the manner described above. 
         [0028]    Those skilled in the art will appreciate that the preferred embodiment employs a sleeve assembly responsive to cycles of applied and removed pressure to open ports for fracturing after cementing. The net force occurs due to different piston areas at the ends of the sleeve assembly and the resisting force when the applied pressure is removed is applied by spring modules to obtain the desired force. Ultimately the spring return force is disabled to allow the sleeve assembly to move down under a net force created by differential piston areas at opposed ends. The ports open position is then locked in the ports open position. 
         [0029]    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.