Abstract:
A series of screens with restrictors to equalize flow through base pipe perforations downstream or upstream of each restrictor features a valve member in the openings so that the screens are closed to flow for run in. Pressure can be developed within the base pipe for operation of downhole equipment below the screens such as a mud motor or in the screen liner such as a packer with no need for an internal string or wash pipe. The openings can be opened selectively when the associated equipment connected to the base pipes has been operated. The valve member can be actuated to open in a variety of ways such as applied pressure, temperature or a change in well fluid condition.

Description:
FIELD OF THE INENTION 
       [0001]    The field of this invention relates to isolation valves for screens that allow the screens to be selectively closed to operate other equipment. 
       BACKGROUND OF THE INVENTION 
       [0002]    In some long horizontal completions steps are taken to reduce the tendency of produced fluids to run along the outside of screens until reaching a necking down of the annular space outside the screened interval before making an attempt to go through the screen, usually on the uphole or heel end of the screen interval. To counteract this effect, the screen sections are provided with a non-perforated base pipe under the screen section that forces the fluid along an annular path between the base pipe and the screen until a restriction section is reached. The restriction section can be a spiral path that provides a flow restriction to the filtered fluid. After going through the spiral restriction section, the filtered fluid reaches the openings to go though the base pipe. This product is offered by Baker Oil Tools under the product name Equalizer Screen. A series of screens with the same or differing restrictions are arranged in an interval to distribute the incoming flow among all the screen sections by counteracting the tendency of the fluid to otherwise follow the path of least resistance and flow in the annular space outside all the screen sections until reaching the heel of a horizontal run and trying to go through the most uphole screen first. 
         [0003]    It is desirable for a variety of reasons to keep the inflow openings in such screens closed until the screens are to be put in service. For one thing, if the inflow openings are kept closed there is no flow through the screens until they are to be put into service. Additionally, with the base pipe closed it can be pressurized so that equipment mounted on the lower end such as a mud motor to drive a bit can be installed and operated to bring the screens into the desired generally horizontal open hole completion for production. Additionally, hydraulic-set packers in the screen liner can be set without resorting to a wash pipe or inner string to isolate the packer inlet from what would otherwise be an open area at the screens. 
         [0004]    While a possible solution is to plug the inflow openings with a rupture disc, the problem with that is that there is no assurance all the rupture discs will break at the same time. If even one rupture disc breaks early, the others will not break at all as all the developed pressure within the base pipes will dissipate through the opened rupture disc. Early attempts to deal with this issue can be seen in U.S. Pat. No. 5,425,424 and the cited patents therein to Zandmer. 
         [0005]    What is needed is a technique that keeps the inflow passage closed until the screens need to be put into service while ensuring that all the screens will go into service when needed because the openings will go to the open position when needed. 
         [0006]    The present invention relates to a valve design for the inflow openings in the screen sections that make up the screened interval that keep the screens closed for run in to prevent flow through them while at the same time allowing pressure to build up within the base pipes so that tools can be operated. When the applied pressure is relieved the valves can open so that the screens can become operative. These and other features of the present invention will be more readily appreciated by those skilled in the art from a review of the description of the preferred embodiment and the associated drawings with the understand that the full scope of the invention is indicated in the claims. 
       SUMMARY OF THE INVENTION 
       [0007]    A series of screens with restrictors to equalize flow through base pipe perforations downstream or upstream of each restrictor features a valve member in the openings so that the screens are closed to flow for run in. Pressure can be developed within the base pipe for operation of downhole equipment below the screens such as a mud motor or in the screen liner such as a packer with no need for an internal string or wash pipe. The openings can be opened selectively when the associated equipment connected to the base pipes has been operated. The valve member can be actuated to open in a variety of ways such as applied pressure, temperature or a change in well fluid condition. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a section view of a horizontal run in a wellbore showing the screens that carry the valve of the present invention; 
           [0009]      FIG. 2  shows a valve locked in the closed position for isolation of its respective the screen; 
           [0010]      FIG. 3  is the view of  FIG. 2  with pressure applied to release the lock while the valve remains closed until pressure is relieved; 
           [0011]      FIG. 4  is an alternative embodiment to the valve of  FIG. 2  shown in the locked closed position; 
           [0012]      FIG. 5  is the valve of  FIG. 4  unlocked but still held closed with applied pressure but in the position to spring open if pressure is removed; 
           [0013]      FIG. 6  shows the valve of  FIG. 5  with pressure removed and the valve fully open; 
           [0014]      FIG. 7  is an alternative embodiment using a shear pin to allow cycles of pressure below a threshold from moving the valve member; 
           [0015]      FIG. 8  is the embodiment of  FIG. 7  armed to open if pressure is removed; 
           [0016]      FIG. 9  is an alternative to the  FIGS. 6-7  embodiment, in the run in position; 
           [0017]      FIG. 10  is the view of  FIG. 9  in the armed position; 
           [0018]      FIG. 11  is the view of  FIG. 10  in the valve open position; 
           [0019]      FIG. 12  is a perspective view of a piston end of the  FIG. 9  embodiment; 
           [0020]      FIG. 13  is an alternative embodiment shown in section during run in; 
           [0021]      FIG. 14  is the view of  FIG. 13  in the armed position; 
           [0022]      FIG. 15  is the view of  FIG. 14  in the open position; 
           [0023]      FIG. 16  is an alternative embodiment shown in section during run in; 
           [0024]      FIG. 17  is the view of  FIG. 16  in the armed position; 
           [0025]      FIG. 18  is the view of  FIG. 17  in the open position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]      FIG. 1  illustrates a horizontal interval  10  that is uncased and has a series of Equalizer screens  12  and  14 , for example connected to a production string  16 . A packer  18  is connected to string  16 . Base pipes  20  and  22  are solid. Annular spaces  24  and  26  lead to restrictors  28  and  30  respectively. These restrictors are essentially a spiral path whose dimensions determine resistance to the filtered fluid that has gotten through the screens  12  and  14 . After passing through the restrictors  28  and  30 , the filtered fluid enters annular spaces  32  or  34  to reach respectively the valves  36  and  38  that are a part of the present invention. When valves  36  and  38  are closed, pressure in passage  40  can be built up so that, for example, the packer  18  can be set. In other applications, the lower end can have a mud motor and drill bit attached so that drilling that brings the screens  12  and  14  into position in horizontal interval  10  can be accomplished and afterward the valves  36  and  38  can be operated to open so that fluid communication through screens  12  and  14  can begin into passage  40 . 
         [0027]    A preferred feature of the valves  36  or  38  is that they are run in closed and preferably locked in that position against opening. The valves move while remaining closed under increasing applied pressure. This feature allows internal pressure to build up in passage  40  to operate downhole tools, a few of which have been described above. Pressurizing also repositions the valves for subsequent opening. This can be configured in several ways. One way is to bias them so that removal of pressure the first time simply allows them all to open. Another way is to mount the valve members on a j-slot mechanism so that the pressure can be cycled off and on a predetermined amount of times before the valves go open. Another valve style altogether can be used so that the openings are blocked until a well condition changes so that the blocking material goes away. The well condition can be a change in temperature or pH that interacts with the blocking material to remove it. Here again, this latter technique is less preferred because it is not as simple to control the variables in the well. Additional, there is also the issue of the variability of the response of the valve material which could result in some openings being opened wide while others remain obstructed. 
         [0028]    A few of the preferred embodiments of valves such as  36  and  38  will now be described below.  FIG. 2  illustrates an opening  42  that leads from passage  40  to annulus  32  or  34  on the other end. Passage  42  is closed initially by plunger  44  that supports a seal  46  positioned in bore  48  of passage  42 . Head  50  sees pressure built up in passage  40  and is limited in motion by surface  52  that surround passage  42 . Spring  54  is supported by shoulder  56  to push the plunger  44  in the direction of passage  40 . A c-ring  58  is held compressed in bore  60 . In the compressed condition, the c-ring  58  will not allow bottom hub  62  to pass and this prevents spring  54  from moving seal  46  out of sealing position in bore  48 . However, as shown in  FIG. 3 , with pressure from passage  40  applied to head  50 , shoulder  64  pushed c-ring  58  out of bore  60  so that it can spring out into bore  66  so that hub  62  can clear through it but only after pressure on head  50  is reduced or removed. That lets spring  54  move plunger or valve member  44  enough to get seal  46  into taper  68  or bore  70  so that flow can commence in passage  42 . At this time the plunger  44  can be pushed clear of passage  42  by spring  54  and the flowing fluid from annular space such as  32 . Allowing the valve passage to open after applied pressure has been removed also prevents an undesirable pressure surge against the formation when the valves open, which may lead to production impairment. Alternatively, hub  62  can have a series of bores  72  and can be captured on bore  48  to retain the plunger  44  in passage  42  while still letting unhindered flow pass from the annular space such as  32  through the bores  72  and the now open passage  42 . 
         [0029]    Those skilled in the art will appreciate that while two screen sections are illustrated, additional sections could be used. Multiple valves may also be used in each screen joint. Additionally, instead of the one time pressurize and release operation shown in  FIGS. 2 and 3 , the c-ring  58  can be replaced with a j-slot mechanism between the plunger  44  and the passage  42  so that any number of desired pressure cycles could be applied to head  50  before the seal  46  is allowed to be displaced from bore  48 . Use of head  50  creates a travel stop under pressure in passage  40  to prevent bottoming the spring  54  or pushing seal  46  out of the bore  38 . 
         [0030]      FIGS. 4 and 5  are basically the same design as  FIGS. 2 and 3  with the exception that head  50  is not there. This allows the plunger  44 ′ to enter bore  70 ′ when pressure from passage  40  is applied. Otherwise the operation is the same. This design allows the coils of spring  54 ′ being pushed together to act as a travel stop for the plunger  44 ′. 
         [0031]      FIG. 6  shows the embodiment of  FIG. 3  and what happens after the pressure has been removed after that position is reached. In essence, the spring  54  expands to open bore  48  and let flow through the valve. 
         [0032]      FIGS. 7 and 8  show another embodiment that adds a shear pin  100 , to act as a restraining member, so that pressure below the break point of the shear pin  100  can be applied to the heads  50  in as many cycles as needed without any movement occurring. Pin  100  is retained by ring  102  that is slidably inserted into the housing  104 . Preferably, each valve exposed to the tubing pressure can have a shear pin  100  but as seen in the other embodiments, such use is entirely optional. When it is desired to open the valves, the pressure is simply raised to a point where all the shear pins  100  or equivalent structures used will all be broken and at that point the operation continues in the same manner described above. It should be noted that the shear plane for pin  100  is at the interface of the outer surface  106  of piston  108  and the inner surface  110  of ring  102 . When the pressure is relieved after the position of  FIG. 8  is achieved, this configuration will prevent jagged surfaces in the shear plane from impeding the bias force of spring  112  on piston  108 . 
         [0033]      FIG. 9  shows a piston  114  having a seal  116  blocking a passage  118  for run in. A groove  120  traps an object  122  to resist the bias imposed by spring  124  on pin retainer ring  126 . Ring  126  is not secured to housing  128  but has a lip  131  that limits its travel into housing  128  in response to applied pressure on head  130 . Pin  132  initially holds ring  126  to the piston  114 . Object  122  prevents piston  114  from being propelled out of passage  118 . This is because opposite to groove  120  for run in is a step  134  that opens into a larger groove  136 . Magnets  138  and  140  attract the objects  122  as piston  114  shifts under pressure to align the objects  122  with groove  136 .  FIG. 10  shows this position that is achieved by applying and holding pressure on head  130 . What has happened is that the shear pin  132  is sheared and groove  120  has shifted left to align with groove  136  so that the magnetic force attracts the objects  122 , which can be ball bearings or other shapes and materials that also respond to magnetic force. At this  FIG. 10  position, the removal of pressure on head  130  will allow spring  124  to propel both piston  114  and ring  126  out of passage  118  to the point where seal  116  is out of passage  118 . This position is shown in  FIG. 11 .  FIG. 12  shows a perspective view of piston  114  showing a rectangular shape of head  130  as one way to limit its rotation about its own axis, which maintains alignment with the objects  122  and magnets  138 . The important thing to note on this embodiment is that the shear surface  142  (which is actually in the shape of a cylinder) where pin  132  is sheared is not the surface where subsequent relative movement occurs to eject piston  114  from passage  118 . Instead, ring  126  moves with piston  114  so as to eliminate any resistance to relative movement that can occur at the shear surface  142  had the ring  126  been secured to the housing  128 . The invention envisions a variety of ways to temporarily retain the piston  114  to get the result that the shear surface for a pin or equivalent restraining device  132  is not the sliding surface for ejection of the piston  114 . 
         [0034]    In  FIG. 13  base pipe  200  has openings  202  into annular space  204  defined by outer sleeve  206 . A piston  208  is biased by a spring  210  but initially a snap ring  212  keeps piston  208  from moving in the direction of the bias. Piston  208  has seals  214  and  216  so that upon pressure delivered through openings  202  the piston  208  is able to translate in the direction to compress spring  210 . In the  FIG. 14  position, the snap ring has snapped outwardly into a groove  218  so that it no longer interacts with the piston  208 . No flow can get by the piston  208  and hence through the screen (not shown in these figures) because even in the  FIG. 14  position with continued pressure applied through ports  202 , the piston seals  214  and  216  are still in the narrow portion  220  defined by outer sleeve  206 . However, when pressure through ports  202  is relieved, spring  210  can now bias the piston  208  into the larger diameter portion  222  of outer sleeve  206  so that flow can occur around seals  214  and  216 . This open position is shown in  FIG. 15 . It should be noted that in this embodiment one end of spring  210  bears on the outer housing  206  while the other bears on the piston  208 . 
         [0035]    In  FIG. 16  spring  224  bears on lug  226  attached to the base pipe  228 . Pressure through openings  230  pushes piston  232  in a direction that compresses spring  224 . At that time the snap ring  234  jumps out into groove  236  and as long as pressure is held in ports  230  there will be no flow past the piston  232 . This is the view of  FIG. 17 . When pressure is relieved, the spring  224  pushes the piston  232  so that flow can bypass piston seals  238  and  240  as shown in  FIG. 18 . The alternative in  FIGS. 13-15  operates the same way as the alternative in  FIGS. 16-18  except the spring support location. The  FIGS. 16-18  embodiment allows for a bigger spring using the same outer sleeve dimension. 
         [0036]    The present invention allows equipment needing pressure to be operated without a wash pipe or an inner string while ensuring the openings open up when needed to allow proper screening of the produced fluids in the interval. When pressure is let up, either the first time, after a pre-determined pressure level is applied to activate a shear device or after sufficient cycles, the valves will be biased to open. Each valve works independently of the others so that problems in the past with a series of rupture discs is avoided. Since applied pressure is uniform, its removal in the presence of a biasing member such as a spring results in the Valves going to the open position independently. 
         [0037]    Alternatives to these preferred designs for an application for equalizing screens are also contemplated. This can be a material such as a plug that is threaded or otherwise secured in the openings and that goes away in response to well conditions such as temperature or well fluid properties. These alternatives feature somewhat less control over the process of opening all the openings preferably at the same time but presents a next best alternative to the preferred embodiments that use pressure actuated valves that open in one or more cycles of pressure. 
         [0038]    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.