Abstract:
A port control system including a group of port control assemblies at least one of which delaying passage of a plug and at least one of which preventing passage of a plug, each assembly of the group configured to shift a sleeve to open one or more ports responsive to contact with a same sized plug upon fluid pressure differential across the plug; and at least one second group of port control assemblies at least one of which delaying passage of a plug and at least one of which preventing passage of a plug, each assembly of the group configured to shift a sleeve to open one or more ports responsive to contact with a same sized plug upon fluid pressure differential across the plug. A method is included.

Description:
BACKGROUND 
     In the downhole drilling and completion industry control of the opening of ports in certain sequences or individually can be important to a particular operation. One such operation is fracturing. It is sometimes desirable to “frac” an earth formation for the purpose of increasing the availability of production fluids to the borehole or to increase access of fluids from the borehole to the formation. 
     Many systems exist for “fracing” most of which use pressure that is significantly higher than that of the downhole pressure where the fracing operation is to take place and direct that pressure through one or more ports. Unfortunately, the process is time consuming and requires a relatively large number of tools be used. Both of these conditions are undesirable because of direct cast and delays, which translate to cost via a lack of revenue. For these reasons, the art is always receptive alternatives that improve efficiency. 
     SUMMARY 
     A port control system including a group of port control assemblies at least one of which delaying passage of a plug and at least one of which preventing passage of a plug, each assembly of the group configured to shift a sleeve to open one or more ports responsive to contact with a same sized plug upon fluid pressure differential across the plug; and at least one second group of port control assemblies at least one of which delaying passage of a plug and at least one of which preventing passage of a plug, each assembly of the group configured to shift a sleeve to open one or more ports responsive to contact with a same sized plug upon fluid pressure differential across the plug. 
     A method for carrying out an operation in a downhole environment in deploying a first plug; seating the plug in a first port control assembly of a group of port control assemblies all being responsive to a plug of a single set of dimensions; pressuring against the plug to actuate a first assembly of the first group of port control assemblies to a port open position and passing the plug through the assembly; seating the plug at least one other port control assembly of the first group of port control assemblies and actuating that assembly to a port open position; deploying a second plug having a set of dimensions different than the first plug; seating the plug in a first port control assembly of a second group of port control assemblies all being responsive to a plug of a single set of dimensions; pressuring against the plug to actuate the first assembly of the second group of assemblies to a port open position and passing the plug through the assembly; and seating the plug at least one other port control assembly of the second group of port control assemblies and actuating that assembly to a port open position. 
     A port control system including a group of port control assemblies at least one of which delaying passage of a plug and at least one of which preventing passage of a plug, each assembly of the group configured to shift a sleeve to open one or more ports responsive to contact with a same sized plug upon fluid pressure differential across the plug. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
         FIG. 1  is a schematic cross sectional view of a port control assembly as disclosed herein in a plug catching position; 
         FIG. 2  is a schematic view of the port control assembly illustrated in  FIG. 1  in a plug passing position; 
         FIG. 3  is a schematic cross sectional view of an alternate embodiment of a port control assembly as disclosed herein; and 
         FIG. 4  is a schematic cross sectional view of another alternate embodiment of a port control assembly as disclosed herein. 
     
    
    
     DETAILED DESCRIPTION  
     A port control system is disclosed that uses groups of port control assemblies that each respond to a same sized plug within the group. Other groups respond to other same sized plugs. As a system, operability of a fracturing operation for example is improved in efficiency since multiple ports can be opened with one plug and fractured and then a next group can be fractured the same way using a different sized plug. The number of groups possible is limited only by the plug size differential practicality. Each assembly is described for an understanding of the system. 
     Referring to  FIG. 1 , a port control assembly  10  is illustrated. The assembly includes a housing  12  having one or more ports  14  therein. The housing further includes a recess  16 . A sleeve  18  is positioned radially of the housing  12  and longitudinally movably therein. The sleeve is restricted against rotational movement by a key  20  that extends from the housing to the sleeve  18 . The key may be fixed to the sleeve, fixed to the housing, or slidable in both so long as rotational movement is not possible. 
     The sleeve  18  includes a load hold and release configuration  22  that in one embodiment is a collet ( FIGS. 1 and 2 ) and may be one or more dogs (see  FIG. 3 ), C-ring (see  FIG. 4 ), etc. The hold and release configuration  22  includes a seat  24  that is configured to receive a plugging implement (hereinafter “plug”)  26  such as a tripping ball, a dart, or other similar implement. As illustrated the leading portion of the plug  26  is shown in contact with the seat  24  in  FIG. 1 . The seat is to be sufficiently formed that the plug  26  will substantially or completely block fluid flow therepast such that pressure is buildable on an uphole side of the plug  26  (left in the drawing). 
     The sleeve  18  is initially maintained in place by a release member  28 . The release member may be of any known kind and is illustrated broadly as a shear ring. Other members such as parting rings, detents, etc are known equivalents to one of ordinary skill in the art and do not require individual drawings. 
     Further the sleeve includes seals  30  that are positioned on the sleeve such that in a first position of the sleeve  18  relative to the housing  12 , the seals  30  will be on either longitudinal end of the one or more ports  14 . The one or more ports  14  are hence sealed by the sleeve  18  and the seals  30 . 
     In use, the port control assembly  10  is disposed in a borehole (open or cased). A plug  26  is dropped or pumped to the seat  24  and pressure is applied to fluid uphole of the plug  26 . The pressure loads the release member  28  until it releases. It is noted that it is not necessary for the release value to be particularly high so that the pressure differential need not be substantial in order to release the release member  28 . Once the pressure differential achieves the design point for the release member  28 , the release member will release the sleeve  18 , thereby allowing the sleeve  18  to move downhole. Movement of the sleeve downhole will be seen through  FIGS. 1 and 2  to uncover the one or more ports  14 . This occurs first in a sequence for each port control assembly  10 . The next occurrence is that the hold and release component is caused to release the plug  26 . This is accomplished in the illustrated embodiment by aligning a portion of the hold and release component  22  with the recess  16  and allowing the hold and release component  22  to deflect into the recess thereby enlarging the seat  24  of the hold and release component to a diameter larger than that of the plug  26 , whereby the plug is free to pass through the seat  24 . This is illustrated in  FIG. 2 . 
     An important aspect of the port control assembly as described is that it is usable with a number of other such assemblies in a system that is capable of opening a number of port areas (each area being a part of one assembly of the group of assemblies and having one or more ports) with a single plug  26 . More specifically, because a plug  26  will land in a seat  24 , open the sleeve  18  and pass through the seat  24  it can do precisely the same job on the next assembly  10  that is configured with the same size seat  24 . It is an aspect of the invention to build such a system that includes one or more of the assemblies  10  as described and a similar assembly at a downhole extent of a particular group of assemblies of the system that does not include recess  16  or that the seat created in the last assembly in the group of assemblies is a nonexpandable seat. Without recess  16 , the plug  26  will not pass the seat  24  and hence will hold pressure without release. It is this assembly of each group of assemblies that allows for fracturing pressure to be imposed on the open ports of a group of assemblies. It should be clear to the reader that not only can there be a number of assemblies  10  that use the same size plug  26  in a system but that the system may also be expanded to include more than one group of assemblies. More specifically, a full system may include for example, four assemblies  10  that use the same size plug at a downhole end of the full system and the downhole most of those assemblies being a nonpassing assembly; four more assemblies that use a different size plug than the first four assemblies do (larger), with the most downhole of those being a nonpassing assembly; four more assemblies uphole of the last group of four that each use the same size plug  26  but a larger one than the next downhole group of four (this group also having a nonpassing assembly at the downhole most position of the group); and so on. It is to be understood that the numeral four used in explanation is in no way intended to limit the number of assemblies used nor to convey that an equal number of assemblies must be in each groups. It is expressly noted that any number of assemblies desired may be designed into any groups of assemblies. Each of the assemblies in a group of assemblies uses the same size plug and each subsequently uphole group of assemblies uses a next larger plug size. One of ordinary skill in the art recognizes that the larger plugs are used more uphole since they do not physically fit into the more downhole components. 
     It should now be appreciated that a full system of the assemblies as described allows for an operator to actuate one or more assemblies with a single size plug  26  giving access to a selected number of ports associated with the groups of assemblies. In one embodiment there will be several assemblies used in each group. The collectively opened ports  14  provide a fracture access point for frac pressure while speeding the operation due to an increase in the length of the formation exposed at any given time. 
     While it is noted that because each plug actuates an uphole most assembly into which it has dimensions sufficient to land and thereby leaves an open port  14  uphole of the next downhole assembly, pressure can still be raised sufficiently to actuate the next downhole assembly due to restricted flow paths in the annulus and because the load required to release the release member  28  is not significant. Pressure delivered to the annulus through one or more open ports is attenuated before getting to the bottom of the hole and back to the downhole side of the plug  26 . Differential pressure is thus still experienced by the plug. 
     In another embodiment of the assembly  10  of  FIG. 1 , reference is made to  FIG. 3 . In  FIG. 3  is illustrated a port control assembly  110 . The assembly includes a housing  112  having one or more ports  114  therein. The housing further includes a recess  116 . A sleeve  118  is positioned radially of the housing  112  and longitudinally movably therein. 
     The sleeve  118  includes a load hold and release configuration  122  illustrated as one or more dogs. The hold and release configuration  122  includes a seat  124  that is configured to receive a plug  26  identical to the foregoing embodiment and not shown here. The seat  124  is to be sufficiently formed that a plug  26  will substantially or completely block fluid flow therepast such that pressure is buildable on an uphole side of such plug  26  just as in the embodiment of  FIG. 1 . In each respect, this embodiment is as it is in  FIG. 1  except that the hold and release component  122  is one or more dogs and the dogs are slidable into the recess  116  to allow passage of a plug  26 . This embodiment also includes an optional downhole shield  140  having seals  142  to prevent debris from entering the recess  116  prior to actuation of the assembly  110 . 
     In yet another embodiment of an assembly similar to that of  FIG. 1 , reference is made to  FIG. 4 . In  FIG. 4  is illustrated a port control assembly  210 . The assembly includes a housing  212  having one or more ports  214  therein. The housing further includes a recess  216 . A sleeve  218  is positioned radially of the housing  212  and longitudinally movably therein. 
     The sleeve  218  includes a load hold and release configuration  222  illustrated as a C-ring. The hold and release configuration  222  includes a seat  224  that is configured to receive a plug  26  identical to the foregoing embodiment and not shown here. The seat  224  is to be sufficiently formed that a plug  26  will substantially or completely block fluid flow therepast such that pressure is buildable on an uphole side of such plug  26  just as in the embodiment of  FIG. 1 . In each respect, this embodiment is as it is in  FIG. 1  except that the hold and release component  222  is a C-ring. The C-ring is expandable into the recess  216  to allow passage of a plug  26 . C-rings are known to the art generally and one of ordinary skill in the art appreciates that C-rings are resilient structures. They can be configured to naturally hold a circular configuration where deflection is outwardly or a position that is open where deflection occurs toward the circular configuration. In the case of the embodiment of  FIG. 4 , the C-ring is configured to hold a circular geometry when at rest and under impetus, expand to increase an inside diametric dimension thereof. The purpose of this should be evident from the foregoing in that a configuration capable of expanding in its inside dimension is also capable of receiving a plug  26  that is selected to have a size to substantially seat thereagainst and then passing that plug  26  when translated to a position relative to housing  212  where the C-ring is aligned with the recess  216 . The assembly  210  hence effectively works as do the other embodiments discussed herein. 
     Each of the foregoing embodiments of assemblies  10 ,  110 ,  210  is useable in a full system and can be mixed and matched if the particular application lends itself to such. 
     While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.