Abstract:
A completion tubular is placed in position adjacent the zone or zones to be fractured and produced. It features preferably sliding sleeve valves one series of which can be put in the wide open position after run in for gravel packing and fracturing zones one at a time or in any desired order. These valves are then closed and another series of valves can be opened wide but with a screen material juxtaposed in the flow passage to selectively produce from one or more fractured zones. An annular path behind the gravel is provided by an offset screen to promote flow to the screened production port. The path can be a closed annulus that comes short of the production port or goes over it. For short runs an exterior screen or shroud is eliminated for a sliding sleeve with multiple screened ports that can be opened in tandem.

Description:
PRIORITY INFORMATION 
     This application is a divisional of U.S. patent application Ser. No. 11/949,403, filed on Dec. 3, 2007. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention relates to completion techniques involving fracturing and more particularly the ability to gravel pack and fracture discrete segments of a formation in a desired order through dedicated valved ports followed by configuring another valve for screened sand control duty to let production begin. A crossover tool and a separate run for sand control screens after the fracturing operation is not required. 
     BACKGROUND OF THE INVENTION 
     Typical completion sequences in the past involve running in an assembly of screens with a crossover tool and an isolation packer above the crossover tool. The crossover tool has a squeeze position where it eliminates a return path to allow fluid pumped down a work string and through the packer to cross over to the annulus outside the screen sections and into the formation through, for example, a cemented and perforated casing or in open hole. Alternatively, the casing could have telescoping members that are extendable into the formation and the tubular from which they extend could be cemented or not cemented. The fracture fluid, in any event, would go into the annular space outside the screens and get squeezed into the formation that is isolated by the packer above the crossover tool and another downhole packer or the bottom of the hole. When a particular portion of a zone was fractured in this manner the crossover tool would be repositioned to allow a return path, usually through the annular space above the isolation packer and outside the work string so that a gravel packing operation could then begin. In the gravel packing operation, the gravel exits the crossover tool to the annular space outside the screens. Carrier fluid goes through the screens and back into the crossover tool to get through the packer above and into the annular space outside the work string and back to the surface. 
     This entire procedure is repeated if another zone in the well needs to be fractured and gravel packed before it can be produced. Once a given zone was gravel packed, the production string is tagged into the packer and the zone is produced. 
     There are many issues with this technique and foremost among them is the rig time for running in the hole and conducting the discrete operations. Other issues relate to the erosive qualities of the gravel slurry during deposition of gravel in the gravel packing procedure. Portions of the crossover tool could wear away during the fracking operation or the subsequent gravel packing operation, if the zone was particularly long. If more than a single zone needs to be fractured and gravel packed, it means additional trips in the hole with more screens coupled to a crossover tool and an isolation packer and a repeating of the process. The order of operations using this technique was generally limited to working the hole from the bottom up. Alternatively, one trip multi-zone systems have been developed that require a large volume of proppant slurry through the crossover tool and that increases the erosion risk. 
     What the present invention addresses are ways to optimize the operation to reduce rig time and enhance the choices available for the sequence of locations where fracturing can occur. Furthermore, through a unique valve system, fracturing can occur in a plurality of zones in any desired order followed by operating another valve to place filter media in position of ports so that production could commence with a production string without having to run screens or a crossover tool into the well. These and other advantages of the present invention will be more readily apparent to those skilled in the art from the description of the various embodiments that are discussed below along with their associated drawings, while recognizing that the claims define the full scope of the invention. 
     SUMMARY OF THE INVENTION 
     A completion tubular is placed in position adjacent the zone or zones to be fractured and produced. It features preferably sliding sleeve valves one series of which can be put in the wide open position after run in for gravel packing and fracturing zones one at a time or in any desired order. These valves are then closed and another series of valves can be opened wide but with a screen material juxtaposed in the flow passage to selectively produce from one or more fractured zones. An annular path behind the gravel is provided by an offset screen to promote flow to the screened production port. The path can be a closed annulus that comes short of the production port or goes over it. For short runs an exterior screen or shroud is eliminated for a sliding sleeve with multiple screened ports that can be opened in tandem. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of an embodiment with a proppant control shroud shown in the run in position; 
         FIG. 2  is the view of  FIG. 1  with a valve open for proppant deposition and fracturing; 
         FIG. 3  is the view of  FIG. 2  with the frac valve closed and the production valve open with a screen in the flow path of the production valve; 
         FIG. 4  is the view of  FIG. 1  but with an alternative embodiment where the proppant shroud straddles the production valve; 
         FIG. 5  is the view of  FIG. 4  with the fracture and proppant deposition valve open; 
         FIG. 6  is the view of  FIG. 5  with the fracture and proppant deposition valve closed and the production valve open with a screen in the flow path; 
         FIG. 7  is an alternative embodiment with no external proppant shroud and instead having a sleeve to open multiple production ports with screened openings and a frac valve all shown in a closed position for run in; 
         FIG. 8  is the view of  FIG. 7  with the frac valve in the wide open fracturing position; 
         FIG. 9  is the view of  FIG. 8  with the frac valve closed and the production sliding sleeve in the open position; 
         FIG. 10  is a view of a frac valve in the closed position; 
         FIG. 11  is the view of  FIG. 10  with the frac valve in the open position; 
         FIG. 12  is the view of  FIG. 11  with the frac valve in the open position and an insertable screen in position for production; 
         FIG. 13  is the view of the insertable screen shown in  FIG. 12 ; 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a schematic illustration of a wellbore  10  that can be cased or in open hole. There are perforations  12  into a formation  14 . A string  16  is shown in part if  FIG. 1  to the extent it spans a production interval defined between seals or packers  18  and  20 . These seal locations can be polished bores in a cased hole or any type of packer. The two barriers  18  and  20  define a production interval  22 . While only one interval is shown the string  16  can pass through multiple intervals that preferably have similar equipment so that access to them can occur in any desired order and access can be to one interval at a time or multiple intervals together. 
     The string  16  for the interval  22  that is illustrated has a frac valve  24  that is preferably a sliding sleeve shown in the closed position in  FIG. 1  for run in. Valve  24  regulates opening or openings  25  and is used in two positions. The closed position is shown in  FIG. 1  and the wide open position is shown in  FIG. 2 . In the  FIG. 2  position, gravel slurry can be squeezed into the formation  14  leaving the gravel  28  in the annular interval  22  just outside the proppant screen or shroud  29 . Shroud  29  is sealed on opposite ends  30  and  32  and in between defines an annular flow area  34 . While the shroud  29  is shown as one continuous unit, it can also be segmented with discrete or interconnected segments. The proppant  28  stays in the interval  22  and the carrier fluid is pumped into the formation  14  to complete the fracturing operation. At that point the valve  24  is closed and excess proppant  28  that is still in the string  16  can be circulated out to the surface using, for example, coiled tubing  36 . 
     At this point the production valve  26  which is preferably a sliding sleeve with a screen material  38  in or over its ports is brought into alignment with ports  40  and production from the formation  14  begins. Alternatively, the screen material  38  can be fixed to either side of the string  16 . In short, the open position of production valve  26  results in the production flow being screened regardless of screen position and screen type. Flow can take a path of less resistance through the flow area  34  to reach the port  40 . While such flow avoids most of the gravel pack  28  by design, the presence of passage  34  allows a greater flow to reach the ports  40  so as not to impede production. The presence of a screen material  38  at ports  40  serves to exclude solids that may have gotten into passage  34  through the coarse openings in shroud  29 . The screen material  38  can be of a variety of designs such as a weave, conjoined spheres, porous sintered metal or equivalent designs that perform the function of a screen to keep gravel  28  out of the flow passage through string  16 . 
     It should be noted that while only a single port  25  and  40  are shown that there can be multiple ports that are respectively exposed by operation of valves  24  and  26 . While valves  24  and  26  are preferably longitudinally shiftable sliding sleeves that can be operated with a shifting tool, hydraulic or pneumatic pressure or a variety of motor drivers, other styles of valves can be used. For example, the valves can be a sleeve that rotates rather than shifts axially. While a single valve assembly in an interval between barriers  18  and  20  is illustrated for valves  24  and  26  and their associated ports, multiple assemblies can be used with either discrete sleeves for a given row of associated openings or longer sleeves that can service multiple rows of associated openings that are axially displaced. 
       FIGS. 4-6  correspond to  FIGS. 1-3  with the only difference being the shroud  29  having an end  32  that is past the openings  40  so that the passage  34  goes directly to the ports  40 . Here, as opposed to  FIGS. 1-3 , once the flow from the formation  14  passes through the shroud  29  it doesn&#39;t have to pass through that shroud  29  a second time. In all other respects the method is the same. In  FIG. 4  the valves  24  and  26  are closed for run in. When the string  16  is in position and the barriers  18  and  20  are activated, the valve  24  is opened, as shown in  FIG. 5 , and proppant slurry  28  is delivered through ports  25 . There is no crossover needed. When the proper amount of proppant is deposited in the interval  22 , the valve  24  is closed and valve  26  is opened to place the screen material  38  over openings  40  to let production begin. As before, with the design of  FIGS. 1-3  and the variations described for those FIGS., the same options are available to the alternative design of  FIGS. 4-6 . One advantage of the design in  FIGS. 4-6  is that there is less resistance to flow in passage  34  because of the avoidance of going through the shroud  29  a second time to get to the ports  40 . On the other hand, one of the advantages of the design of  FIGS. 1-3  is that the inside dimension of the string  16  in the region close to valve  26  can be larger because the shroud  29  terminates at end  32  well below the ports  40 . 
     In both designs the length of shroud  29  can span many pipe joints and can exceed hundreds if not thousands of feet depending on the length of the interval  22 . Those skilled in the art will appreciate that short jumper sections can be used to cover the connections after assembly so that the passage  34  winds up being continuous. 
       FIGS. 7-9  work similarly to  FIGS. 1-3  with the only design difference being that the shroud  29  is not used because the application for this design is for rather short intervals where a bypass passage such as  34  around a shroud  29  is not necessary to get the desired production flow rates. Instead valve  26  has a plurality of screen sections  38  that can be aligned with axially spaced arrays of openings  40 . In this case as with the other designs, the valves  24  and  26  can be located within or outside the tubular string  16 . In all other ways, the operation of the embodiment of  FIGS. 7-9  is the same as  FIGS. 1-3 . In  FIG. 7  for run in the valves  24  and  26  are closed. The string  16  is placed in position and barriers  18  and  20  define the producing zone  22 . In  FIG. 8 , the valve  24  is opened and the gravel slurry  28  is squeezed into the formation  14  leaving the gravel in the interval  22  outside of openings  40 . In  FIG. 9  the gravel packing and frac is completed and the valve  24  is closed. Then valve  26  is opened placing screen material  38  in front of openings  40  and production can begin. In essence, valve  26  with its screen sections  38  and openings  40  act as a screen that is blocked for run in and gravel deposition and frac and then functions as a screen for production. Again multiple assemblies of valves  24  and  26  can be used so that if one fails to operate another can be used as a backup. In the same manner if one set of screen sections  38  clog up, another section can be placed in service to continue production. 
       FIG. 10  illustrates a valve  50  that uses as sliding sleeve  52  to selectively cover ports  54 . The ports  54  are closed in  FIG. 10  and open in  FIG. 11 . A latch profile  56  is provided adjacent each sleeve  52 . An array of valves  50  and associated ports  54  is envisioned. The configuration of the latch profile  56  is preferably unique so as to accept a specific screen assembly  58 , one of which is shown in  FIG. 13 . Each screen assembly has a latch  60  that is uniquely matched to a profile  56 .  FIG. 12  shows a screen assembly  58  that has a latch  60  engaged in its mating profile  56 . In that position a screen  62  has end seals  64  and  66  that straddle ports  54  with sleeve  52  disposed to uncover the ports  54 . One or more such assemblies are envisioned in an interval  22  between isolators  18  and  20  in the manner described before. In operation, the ports  54  are closed for run in as shown in  FIG. 10 . After getting the string  16  into position and setting the barriers (not shown in  FIG. 10 ) to define an interval  22 , as before, the ports  54  are exposed and gravel slurry is forced into the formation as the formation is fractured. At this time the screen assembly  58  is not in string  16 . When that step is done and the excess slurry is circulated out, the valves  50  to be used in production are opened. A screen assembly  58  with a latch  60  that matches the valve or valves  50  just opened is delivered into the string  16  and secured to its associated profile  56 . In this manner, the ports  54  that are now open each receive a screen assembly  58  and production can begin. Any order of producing multiple intervals can be established. The screen sections  58  can be dropped in or lowered in on wireline or other means. They are designed to release with an upward pull so if they clog during production they can be released from latch  56  and removed and replaced to allow production to resume. The screen assemblies can have a fishing neck  68  to be used with known fishing tools to retrieve the screen section  58  to the surface. One screen section can cover one array of ports  54  or multiple arrays, depending on its length and the spacing between seals  64  and  66 . 
     Optionally, the shroud  29  of from the other embodiments can be combined into the  FIGS. 10-13  embodiment and it can be positioned to come just short of ports  54  or to straddle them as previously described and for the same reasons. 
     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.