Abstract:
An isolation method is described for gravel packed zones separated by at least one packer and having an auxiliary conduit passing through the packer into adjacent zones. The conduit includes at least one each of a shunt tube, flow housing, annular space, and isolation valve housing. The flow housing, the annular space, and the isolation valve housing are all annular and formed between two concentric pipes. The method includes running in an assembly of screens isolated by at least one packer with at least one auxiliary conduit extending into adjacent zones defined by the packer when the packer is subsequently set. The method also includes closing flow in said conduit to prevent flow into shunt tubes during production based on creating a flow barrier in the annular space, the flow housing, or the isolation valve housing, the shunt tubes supplying slurry through the auxiliary conduit prior to the production.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of an earlier filing date from U.S. application Ser. No. 14/218,460 filed Mar. 18, 2014, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The field of the invention is zonal isolation across a set packer that has alternate path passages that go through its body or seal and more particularly where such closures are automatically actuated. 
     BACKGROUND OF THE INVENTION 
     In the context of multiple zone isolation when gravel packing while using alternative path conduits there is a need to be able to isolate the zones on opposed sides of a set packer in open or cased hole. In doing so there is a need to seal off the alternate paths that run through the packer bodies or seals. One approach that has been tried is to introduce fluid in the wellbore that initiates a swelling response in a material that seals off the alternate paths. This approach is described in U.S. Pat. No. 7,407,007. The problem in this design is that it requires delivery to the swelling material of a fluid that will induce it to swell. The problem is that there is uncertainty if the delivered fluid has actually reached the swelling material in the individual tubes to start the process. Further, there is also a time delay issue from the onset of the circulation to the obtaining the desired result of path isolation. A variation of this design using a shifting tool to operate a valve in an auxiliary conduit is U.S. Pat. No. 7,562,709. 
     Also of general interest to the field of auxiliary conduits and closures associated with isolation devices or such conduits are the following: U.S. Pat. Nos. 7,126,160; 7,373,979; 7,296,624; 7,128,152; 7,784,532; 7,147,054; 6,464,007; 8,403,062; 6,588,506; 8,453,734 and 7,841,398. 
     SUMMARY OF THE INVENTION 
     According to an embodiment, an isolation method for gravel packed zones separated by at least one packer and having at least one auxiliary conduit passing through said packer into adjacent zones, the conduit comprising at least one each of a shunt tube, flow housing, annular space, and isolation valve housing, and the flow housing, the annular space, and the isolation valve housing all being annular and being formed between two concentric pipes includes running in an assembly of screens isolated by at least one packer with at least one auxiliary conduit extending into adjacent zones defined by said packer when said packer is subsequently set; and closing flow in said conduit to prevent flow into shunt tubes during production based on creating a flow barrier in the annular space, the flow housing, or the isolation valve housing, the shunt tubes supplying slurry through the auxiliary conduit prior to the production. 
     Auxiliary conduits that run through a packer body or seal are equipped with thermally responsive valve members that with a time exposure close off the conduits to create zonal isolation across one or more packers after a gravel pack. The heat source can also be added to the well fluids to control the speed of the process either in the form of heaters or reactive chemicals that create an exothermic reaction or by other means. The valve material can be shape memory polymer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a gravel packing assembly showing the auxiliary conduit with the closure in the conduit in the open position for multizone gravel packing; 
         FIG. 2  is the view of  FIG. 1  with the valve in the conduit in the closed position after the gravel packing so that adjacent zones are isolated for production; 
         FIG. 3  further details portions of the conduit in which flow is interrupted according to embodiments of the invention; 
         FIGS. 4A and 4B  illustrate an embodiment for closing the annular space, isolation valve housing, or flow housing using an injection device; 
         FIGS. 5A and 5B  illustrate an embodiment for closing the conduit at the flow housing or isolation valve housing using a rubber sleeve; 
         FIGS. 6A and 6B  illustrate an embodiment for closing the conduit at the flow housing or isolation valve housing using a sliding sleeve; and 
         FIGS. 7A and 7B  illustrate an embodiment for closing the conduit at the annular space using an inflatable packer within the communication mandrel. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As noted above, there is a need to achieve zonal isolation within a gravel pack screen. In particular, an alternate path or shunt tube channels flow through a flow housing to an annular space (cross-coupling annulus). Efforts to prevent flow back up the borehole (up the shunt tubes that deliver the slurry for the gravel pack screen) during production have focused on the shunt tubes themselves. In contrast to above-noted current approaches that relate to tubes or flow paths within an annulus, embodiments described herein address closing off the cross-coupling annulus or the flow housing, as detailed below. The purpose of closing off the annulus or flow housing is to prevent water or other material from being pumped up the shunt tubes after the shunt tubes have delivered slurry (down the borehole) for the gravel pack during the completion phase. One particular embodiment is discussed with reference to  FIGS. 1 and 2 . 
       FIG. 1  shows an open hole  1  that has a screen base pipe  2  that supports one or more isolation packers  11  that separate producing zones, although only a single zone is fully illustrated. Portions of an adjacent zone can be seen in the form of communication housing  4  that appears above and below the packer  11  and thus is shown extending into multiple zones. The base pipes  2  are connected with couplings  7  and communications mandrels  5  to make a continuous string that supports the screens that are not shown. Auxiliary conduits  3  include the shunt tube  13  (also referred to as the alternate path), flow housing  4 , isolation valve housing  9 , and the annular space  12 . The flow housing  4 , isolation valve housing  9 , and annular space  12  are all annular spaces between two concentric elements. During slurry flow, the flow housing  4  (shown on the left side at the start of the illustrated flow) is essentially a common chamber into which a number (e.g., four) shunt tubes  13  flow slurry. This slurry is channeled into the annular space  12  and into the isolation valve housing  9  then back out to the flow housing  4  (shown on the right side at the end of the illustrated flow) into a number of shunt tubes  13  again. The tubes into and out of the flow housing  4  are held in the annulus between two perforated tubes. The two concentric elements that form the boundaries of the annular space  12 , as shown in  FIG. 1 , are the communications mandrel  5  (in the base pipe  2 ) and one of the bottom sub  6 , coupling  7 , or top sub  8 . The auxiliary conduits  3  extend through either the body or seal of the packers  11  with the flow through the packer  11  illustrated with a series of arrows. In each conduit  3  there is a valve member  10  (shown in the annular space  12 ) that during running in leaves each conduit  3  open to pass gravel between zones on opposed sides of each packer  11 . The member  10  is preferably a high temperature shape memory polymer that responds to temperatures of the surrounding well fluid to cross its transition temperature and change shape into the  FIG. 2  shape where the conduits  3  are obstructed. The heat can come from well fluid temperatures that occur naturally or the temperature can be artificially enhanced with heat from a heater or from an induced reaction that is exothermic or from other heat sources brought into the vicinity of the member  10 . The artificial addition of heat just brings the member  10  to its critical temperature faster for closing off the annular space  12  of the conduits  3  on one or opposed sides of a packer  11  for full zonal isolation when the packer  11  is set. In alternate embodiments, the member  10  may be in the flow housing  4  or in the isolation valve housing  9  rather than in the annular space  12 . The packers  11  can be unset during gravel packing so that multiple zones can be gravel packed together followed by setting the packers  11  followed by using the heat in well fluid to automatically shut the annular space  12  of the conduits  3  for full zonal isolation.  FIG. 1  shows various components such as communication housing  4 , top sub  8 , isolation valve housing  9  and bottom sub  6  all of which are part of the conduits  3  that overly the base pipe  2  and associated screens that are not shown that overly the base pipes  2 . Member  10  is shown as a valve member inside the conduit  3  that with a crossing of the transition temperature closes it. Alternatively the conduit  3  itself can be made from a similar material so that the crossing of the critical temperature from well fluid makes the shape change that ensues change the tubular wall configuration and creates a closure for zonal isolation to become effective at the packers  11  because the conduits that span the set packer are effectively closed. The members  10  in each zone can be responsive to the same or different well fluid temperatures so that closure of members  10  in adjacent zones can occur at the same or different times. This allows sequential closures of the conduits  3  in an uphole or downhole sequence or in another desired sequence. Adding heat locally can also control the order of closures. It should be noted that the flow housings  4  allow entry or exit of gravel into the surrounding annulus for the gravel packing. 
     The advantage of the present invention is the automatic operation of the closures in the annular space  12  of the conduits  3  (or the isolation valve housing  9  or flow housing  4 ) that then make possible the zonal isolation at the packers  11  to allow selective production or injection into selected zones or full isolation of such zones if desired. With proper screen valves individual zones can be separately produced or multiple zones can be produced together. The closures can be situated anywhere in the annular space  12  of the conduits  3  between isolation packers  11  with preferably each conduit  3  having one or more members in a given packer  11  interval with the use of multiple members providing further assurance that there is tight closure in the conduits between the zones. Apart from a shape change that plugs the conduits  3  the shape of the conduits  3  can changes when the shape memory polymer is used for the conduit wall itself and reverts to a shape above the critical temperature that effectively closes the conduit. The member material can be shape memory alloy in an alternative design. The automatic operation of the closures for the conduits  3  can save time in getting the isolation of zones accomplished so that the next phase can be started that much faster. In the event additional time is needed before the conduits  3  close, fluid can be circulated with the gravel that is refrigerated to temporarily suspend the closure to allow time for effective completion of the gravel packing. 
       FIG. 3  further details portions of the conduit  3  in which flow is interrupted according to embodiments of the invention. As noted above, the annular space  12  is the space between two concentric elements. The inner concentric element that defines the inner boundary of the annular space  12  is the base pipe  2  or, more specifically, the communication mandrel  5  portion (as shown in  FIG. 3 ), and the outer concentric element that defines the outer boundary of the annular space  12  is the bottom sub  6 , the coupling  7 , or the top sub  8  (at the different axial locations shown in the figures). Perforations  310  shown in the bottom sub  6  and top sub  8  facilitate the flow of fluid between the flow housing  4  (or the isolation valve housing  9 , not shown in  FIG. 3 ) and the annular space  12 . Each of the embodiments discussed herein relates to closing off the annular space  12 , the isolation valve housing  9 , or the flow housing  4  of the conduit  3  to create zonal isolation. As discussed above, a member  10  (e.g., shape memory polymer) located in the annular space  12  (or in the flow housing  4 ) closes based on temperature. 
       FIG. 4  illustrates an embodiment for closing the annular space  12 , isolation valve housing  9 , or flow housing  4  using an injection device  400 . According to the embodiment shown in  FIG. 4 , the injection device  400  includes a container of resin  410  and a container of curing agent  420 . The containers stay separated until a trigger signal is issued. The resin  410  may be an epoxy resin, for example. The trigger may be in the form of a hydrostatic pulse or other signal. Once the trigger is issued, the resin  410  and agent  420  mix in a chamber  430  of the injection device  400 . The mixture (as the mixing is taking place) then invades the annular space  12 . There may be a number (e.g., 3 to 5) of injection devices  400  arranged circumferentially around the annular space  12  such that the mixture exiting each injection device  400  forms a gas tight seal in the annular space  12 . The containers for the resin  410  and curing agent  420  need not be kept together as shown but, instead, may be separated and located on the same joint as the packer  11 . Further, the chamber  430  may not be present such that the mixing takes place in the annular space  12 . In an alternate embodiment, as also shown in  FIG. 4 , the injection device  400  may be disposed in the flow housing  4  or in the isolation valve housing  9  rather than in the annular space  12 . Specifically, multiple injection devices  400  may be disposed circumferentially around the flow housing  4  or the isolation valve housing  9  to close off the flow housing  4  or isolation valve housing  9  based on a trigger that causes the resin  410  and curing agent  420  to mix. 
       FIGS. 5A and 5B  illustrate an embodiment for closing the conduit  3  at the flow housing  4  or isolation valve housing  9  using a rubber sleeve  510 . The rubber sleeve  510  is positioned at the perforations  310  on the bottom sub  6  or top sub  8 , as shown. As shown in  FIG. 5A , the rubber sleeve  510  is pushed (balloons) open based on fluid pressure of fluid flowing from the annular space  12  through the perforations  310  into the flow housing  4  or isolation valve housing  9 . This would be the case when slurry is flowing downhole prior to production, for example. As shown in  FIG. 5B , when fluid flow in the annular space  12  is not forcing the rubber sleeve  510  into the open position, the rubber sleeve  510  stays against the perforations  310  and prevents flow from the flow housing  4  or isolation valve housing  9  into the annular space  12 . As such, during production, water is prevented from going back uphole through the annular space  12  and ultimately into the shunt tubes  13 . Specifically, flow is prevented from the flow housing  4  into the annular space  12  between the bottom sub  6  and communication mandrel  5  or from the isolation valve housing  9  into the annular space  12  between the top sub  8  and communication mandrel  5 . In alternate embodiments, a sleeve made of a material other than rubber that expands to uncover the perforations  310  based on fluid pressure from fluid in the annular space  12  may be used. While one set of perforations  310  (at one axial location of the flow housing  4  or isolation valve housing  9 ) is shown, the rubber sleeve  510  or other sleeve may cover multiple sets (rows) of perforations  310 . 
       FIGS. 6A and 6B  illustrate an embodiment for closing the conduit  3  at the flow housing  4  or isolation valve housing  9  using a sliding sleeve  610 . Two different embodiments of a sliding sleeve  610  are discussed. The sliding sleeve  610  includes a pair of seals  620  associated with each perforation  310  in the bottom sub  6  or top sub  8 .  FIG. 6A  illustrates an open position in which both seals  620  of the sliding sleeve  610  are below the corresponding perforation  310  such that downhole flow of slurry, for example, is not obstructed. That is, slurry may freely flow through the annular space  12  between the communication mandrel  5  and bottom sub  6  through to the flow housing  4  or through the annular space  12  between the communication mandrel  5  and top sub  8  through to the isolation valve housing  9 .  FIG. 6B  illustrates a closed position in which each pair of seals  620  are on either side of each corresponding perforation  310  such that flow from the flow housing  4  into the annular space  12  or flow from the isolation valve housing  9  into the annular space  12  is prevented. According to one embodiment, the sliding sleeve  610  slides along the outer surface of the communication mandrel  5  while, according to another embodiment, the sliding sleeve  610  is a portion of the communication mandrel  5  itself. That is, a portion of the outer surface of the communication mandrel includes seals  620 . The sliding sleeve  610  may lock into place based on a mating of the sleeve portion  630  with the annular portion  640  locking mechanism that is disposed (attached) within the annular space  12 . 
     The sliding sleeve  610  (whether stand-alone or part of the communication mandrel  5 ) may slide into the position to close off the perforations  310  based on a number of mechanisms. According to one embodiment, a dissolvable nano material may hold the sliding sleeve  610  in the open position shown in  FIG. 6A . As long as the nano material is selected so that it does not dissolve too quickly (within hours), at a time at or nearing the end of the completion process (prior to start of production), the sliding sleeve  620  will be released to the closed position shown in  FIG. 6B . According to another embodiment, a trigger may be used to move the sliding sleeve  610  from the open to the closed position. For example, a washpipe (used until the end of the completion phase) is typically pulled up prior to production. Thus, the washpipe may be outfitted with a magnet or electrical signal source such that, as the washpipe passes the sliding sleeve  610  on its way out of the borehole, the sliding sleeve  610  is triggered to move to the closed position ( FIG. 6B ) prior to production. In alternate embodiments, the sliding sleeve  610  may be mechanically or hydraulically actuated. 
       FIGS. 7A and 7B  illustrate an embodiment for closing the conduit  3  at the annular space  12  using an inflatable packer  710  within the communication mandrel  5 . A portion of the communication mandrel  5  is comprised of an inflatable material (inflatable packer  710 ). In the open position, shown in  FIG. 7A , the inflatable packer  710  is not inflated and slurry flows through the annular space  12  into the flow housing  4  or isolation valve housing  9 . When the inflatable packer  710  within the communication mandrel  5  is inflated, as shown in  FIG. 7B , flow through the portion of the annular space  12  that is taken up by the inflated inflatable packer  710  is closed off. The inflatable packer  710  may be inflated prior to the start of the production phase based on hydraulic pressure, for example, or another mechanism. 
     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: