Abstract:
A multi-zone formation has a plurality of sliding sleeve valves for selective access to the formation from the wellbore. Each of the sliding sleeves has a unique latch profile such that an initial dart with a matching profile will land on the predetermined sleeve. With all the sliding sleeves initially in the position where access ports are closed the sleeve that gets the first dart has pressure applied to shift that sleeve to the ports open position for well treatment. Thereafter, a second dart lands on the first effectively closing the ports just opened. Further pressure closes the sliding sleeve and blows both darts to hole bottom. Any other sleeve can then be selected with a unique profile that matches another sliding sleeve and the process repeats. For production selected sliding sleeves are opened preferably with a wireline shifting tool.

Description:
RELATED PRIORITY DATE APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. 119(e) of the U.S. provisional application No. 62/145,965 filed on Apr. 10, 2015. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of the invention is fracturing multiple zones and more particularly methods of fracturing the zones in a random order with sleeve valves having unique profiles that can be selectively opened and then closed without well intervention. 
       BACKGROUND OF THE INVENTION 
       [0003]    Fracturing operations can be in a bottom up orientation where progressively larger balls sequentially land on bigger seats to isolate zones already fractured so that the next zone uphole can be fractured. The procedure is repeated until all the zones are fractured. The balls can either be lifted to the surface with subsequent production from all zones or the balls can also be removed by blowing them through seats or drilling them out so that production can take place from the desired zones. Frequently wellbore intervention is needed to close sliding sleeve valves if production is needed only from select zones. Other techniques using sliding sleeve valves combines actuation to open with a ball landed on a seat and subsequent closure of the sliding sleeve with well intervention using a shifting tool. This method is illustrated in WO2014/094136. In US 2014/0345876 the same open and close technique using well intervention to close the fracturing port is illustrated. 
         [0004]    Unique profiles are used in tandem with a hydraulic tool to operate a variety of tools in a single trip using unique flow signaling as described in US 2010/0089587. In other designs darts with unique latch profiles are deployed on a rod with multiple sensors to be released to latch with matching profiles on sleeves for well stimulation as described in US2012/0048570. In U.S. Pat. No. 8,757,265 a plurality of subterranean tools can be operated with balls that emit an RFID signal to operate the tools in a desired order when a unique signal operates a unique tool so that the associated actuator for the tool is signaled to operate in response to the unique RFID signal associated with the dropped ball. 
         [0005]    What is needed and provided by the present invention is a way to fracture zones in any desired sequence without well intervention. The method is accomplished with sliding sleeve valves with unique profiles to accept darts with matching profiles. A selected valve gets a predetermined dart with a matching profile to allow subsequent pressure buildup to shift the sleeve to the ports open position. After the well treating job through the opened ports is completed a second dart lands on the first dart to effectively closed the open ports to allow a second pressure buildup on the sleeve to shift the sleeve so that the ports are then closed. Thereafter both darts are blown through the sleeve to hole bottom. At this point any other sleeve can be addressed by a conforming profile on another dart pumped into the borehole and the process repeats. After the treatment is over selected sleeves can be moved to a full open, screened open or choke position with wellbore intervention such as a shifting tool, pumping another dart, or in other ways. The method allows a random order of treatment of multiple zones without well intervention. 
         [0006]    These and other advantages of the present invention will become apparent from the following description and drawings. Those skilled in the art will further appreciate other aspects of the invention from a review of the detailed description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention can be determined by the appended claims. 
       SUMMARY OF THE INVENTION 
       [0007]    A multi-zone formation has a plurality of sliding sleeve valves for selective access to the formation from the wellbore. Each of the sliding sleeves has a unique latch profile such that an initial dart with a matching profile will land on the predetermined sleeve. With all the sliding sleeves initially in the position where access ports are closed the sleeve that gets the first dart has pressure applied to shift that sleeve to the ports open position for well treatment. Thereafter, a second dart lands on the first effectively closing the ports just opened. Further pressure closes the sliding sleeve and blows both darts to hole bottom. Any other sleeve can then be selected with a unique profile that matches another sliding sleeve and the process repeats. For production selected sliding sleeves are opened preferably with a wireline shifting tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a detailed description of the preferred embodiment of the invention, reference will now be made to the accompanying drawings wherein: 
           [0009]      FIG. 1  shows the basic system components; 
           [0010]      FIG. 2  is a detailed view of a treatment valve that is part of the system; 
           [0011]      FIG. 3  is a detailed view of the starter valve that is part of the system; 
           [0012]      FIG. 4  is a view of the starter valve where the first burst disc is broken with pressure; 
           [0013]      FIG. 5  is the view of  FIG. 4  where the second rupture disc is broken; 
           [0014]      FIG. 6  is the view of  FIG. 5  with the third rupture disc broken; 
           [0015]      FIG. 7  is the view of  FIG. 2  with the first dart landed in a matching profile; 
           [0016]      FIG. 8  is the view of  FIG. 7  with the valve ready to shift to the open treating position; 
           [0017]      FIG. 9  is the view of  FIG. 8  with the valve shifted to the treating position; 
           [0018]      FIG. 10  is the view of  FIG. 9  with a second dart landed and ready to further shift the valve in the same direction for closure so that another location can then be treated; 
           [0019]      FIG. 11  is the view of  FIG. 10  with the valve shifted closed and both darts released from the landing profile; 
           [0020]      FIG. 12  is the view of DIG.  11  showing both darts traveling through the starter valve and captured in a catcher below; 
           [0021]      FIG. 13  is a view of a first zone furthest uphole being treated first; 
           [0022]      FIG. 14  is the view of  FIG. 13  showing a lowermost zone being treated second; 
           [0023]      FIG. 15  is the view of  FIG. 14  showing a third zone between the first and second treated zone being treated next; 
           [0024]      FIG. 16  shows the plug in the starter valve to close it. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    The basic components of the subterranean treating system are shown in  FIG. 1 . The bottom hole assembly (BHA)  10  has a known cementing shoe  12  with a pair of flapper valves  14  and  16  to prevent pumped cement from u-tubing back out of the annulus and into the BHA  10 . Above the shoe  12  is a starter valve  18  designed to selectively open the toe of the well for treatment and to open a flow path into the formation for pumped dart delivery as will be explained below. Above the starter valve  18  are alternating tubulars  20  and treatment valves  22  strategically placed in the completion for treating respective adjacent zones  24 . Additional tubulars  26  extend the completion to another uphole string or to the surface depending on the well configuration. Treatment valves  22  are sequentially operated to open from an initially closed position by virtue of an opening pumpable dart  28 . Each dart  28  has a unique profile  30  (see  FIG. 7 ) that registers with a mating profile  32  unique to each sliding sleeve  34  that is part of each treatment valve  22 . To close a given treatment valve  22  a second pumpable dart  36  lands on dart  28  and with applied pressure shifts the sleeve a second time in the same direction as the initial movement of sleeve  34  to the closed position, whereupon further pressure buildup releases both darts  28  and  34  to and through the starter valve  18  into a catcher volume  38  (see  FIG. 12 ). Ultimately when all the treatment valves  22  have been opened, used for treatment and then reclosed in any desired order an isolation plug  40  is delivered so that its profile  42  registers with a starter valve profile  44  to seal the starter valve  18  closed (see  FIG. 16 ). Optionally, production of the formation near the toe of the well or at the starter valve location can take place exclusively or with other zones that have had their sliding sleeve  34  moved to an open position as will be explained in more detail below. Finally, dart  46  has the ability to travel through the treatment valves and sequentially register with all the sliding sleeves  34  to push them closed and pass through to the starter valve  18  should there be a need to shut in the well. 
         [0026]      FIG. 2  shows a treatment valve  22  in more detail. A housing  48  is rotationally locked to the sleeve  34  by virtue of a pin  50  on the housing  48  extending into a longitudinal slot  52 . Housing openings  54  are shown misaligned from openings  56  on the sliding sleeve  34 . When those openings align the fully open position of the treatment valve  22  is achieved for operations such as fracturing or acidizing, for example. Openings  58  have screen  60  across them and represent a screened open position for the valve  22  when in production. Openings  62  are used for a choke position when aligned with openings  54  for flow balancing among several zones that could be in production at the same time. Openings  58  and  62  can both be above the closed portion  64  for the valve  22  such that the sequence of movement from initially closed to open and back to closed followed by reopening for production can occur with movement of the sleeve  34  in a single direction. Making the latter pattern possible allows making the movements without well intervention such as the use of dart  28  to open a specific valve  22  followed by dart  36  landing on the dart  28  to reclose the valve, followed by another dart (not shown) to reopen the valve  22  to a screened or choked or even a wide open position for later production. Alternatively, the first two movements in the same direction can open and then close the valve  22  while borehole intervention with a shifting tool on wireline or coiled tubing, or a tractor device on slickline, for example, shown schematically as  66  can be used to register with at least one specific valve  22  to put that valve in a desired position. Item  68  is a schematic representation of a detent device that bumps the sleeve  34  progressively into different positions. This can be a biased collet that finds grooves in succession, a snap ring that progressively finds different grooves, a stepper motor that drives sleeve  34  in increments or a spring loaded j-slot responsive to pressure cycles on landed darts  28  and  36  to name a few examples. 
         [0027]    Referring now to  FIG. 3  the starter valve  18  is shown in more detail above the flappers  14  and  16  that are part of a cement shoe  15 . The starter valve  18  has a profile  44  to match profile  42  in isolation plug  40  as shown in  FIG. 16 . Chamber  70  is for catching darts  28  and  36  after they get blown through a treatment valve  22  as described above. Inner wall  72  has upper rupture discs  74  and lower rupture discs  76  that lead to a fluid bypass channel  78  which in turn leads to rupture discs  80  for access to the annulus. The rupture discs break sequentially with applied pressure when all the treatment valves are closed as the assembly is first run before treatment begins. With the rupture disc broken the darts  28  and  36  can be delivered to each treatment valve  22  and then blown though into catch volume  38 .  FIGS. 4-6  represent schematically the order of breakage of the rupture discs as  76 ,  74  and  80 . When the  FIG. 6  position is achieved, the toe of the well can be treated first. Pumping subsequent darts  28  and  36  is made possible by the flow passages shown in  FIG. 6  being open to allow fluid displacement to the formation ahead of such darts as the treatment progresses through the various treatment valves  22 . 
         [0028]      FIGS. 7-10  show the sequence of landing dart  28  with a unique profile  30  into a matching profile  32  in sliding sleeve  34 . In  FIG. 8  pressure is then applied from the surface or other location to slide sleeve  34  to open ports  54  for treatment when ports  56  are moved into alignment with ports  54 . When the treatment concludes as shown in  FIG. 8 , dart  36  lands on dart  28  and further pressure is applied as shown in  FIG. 10 . This is made possible because dart  36  when landed on dart  28  covers ports  56 ,  54  so that the sleeve  34  can be moved a second time in the same direction as the initial movement that opened ports  54 . Closed portion  64  lines up with ports  54  to close them as shown in  FIG. 11 . Continued pressure buildup blows both darts  36  and  28  into catch volume  38  in the starter valve  18 . This happens because the profile  30  on the dart  28  has a shear release that allows the profile  30  to retract into an adjacent slot (not shown) on the dart  28  body so that dart  28  with dart  36  that has landed on it can both be blown through the sleeve  34  to which dart  28  had been previously engaged. 
         [0029]      FIGS. 13-15  show three treatment valves  22 ,  22 ′ and  22 ″. Because of the unique profile at each of these treatment valves the order of operation can be  22 ,  22 ″ then  22 ′ as shown in  FIGS. 13-15 . The  FIGS. 13-15  are schematic to show one possible order depending on the profile of darts  28 ,  28 ′ and  28 ″. The second dart  36  that would land on each dart  28  at the various valves  22  is omitted from these FIGS. for greater clarity in illustrating that any order of sleeve  22  operation is possible when each of the sleeves have a unique latch profile including bottom up, top down or random. As mentioned before, after all the treatment is over the sleeves  22  corresponding to the zones to be operated can be opened with or without borehole intervention as explained above. At any time during production wiper  46  can be pumped down. It has a generic pattern that can latch on each sliding sleeve  34  and move such a sleeve to a closed position such as by positioning blank portion  82  opposite openings  54  to close them. As mentioned before an index mechanism allows movement from closed to open and again to closed during the treatment phase. Thereafter for production the sliding sleeves  34  in each treatment valve  22  can be further indexed to wide open, screened, or choked either with or without wellbore intervention using the detent feature shown schematically as  68 . 
         [0030]    Those skilled in the art will appreciate that the present invention enables treatment such as fracturing, acidizing, injection, for example in any needed order using objects with unique profiles that register in a specific location of a treatment valve that has the mating profile. The initial opening, treatment and closing sequence for a specific sliding sleeve valve can be done without intervention using pressurized darts. A starter valve at the toe of the well provides for displaced fluid ahead of the darts into the formation and acts as a repository for the darts blown through the sleeve with pressure as the sleeve closes. Thereafter, when the treatment is concluded sliding sleeve valves can be opened in a variety of modes for functions such as flow balancing with the choke open feature, for example. Valves can also be placed in screened open position or left closed or again put in a fully open position such as used during treatment. Such a reopening of one or more sliding sleeves can take place with or without well intervention depending on the configuration of the sliding sleeves. The sliding sleeves can be moved with a shifting tool additional wipers combined with pressure cycles and j-slots or dedicated motors that can be actuated locally or remotely. In case of a need to rapidly shut the well in, a dart that registers with all the sleeves can be delivered to engage each of the sleeves and close such sleeves before being blown through to land on the next sleeve in order. The sleeves that are still open at this time will move closed before such a dart moves through. The sleeves already closed will be configured to not move further but simply will release the dart to a new sleeve or the catcher without moving at all. 
         [0031]    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: