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BACKGROUND 
   In the field of hydrocarbon exploration and recovery, holes (wellbores, boreholes) are drilled deep into the crust of the earth to access deposits of fluid hydrocarbons. The degree of fluidity and the makeup of deposits varies, it is desirable to have the ability to control flow from different deposits into the wellbore. Flow control devices are varied in nature and in their particular construction but all must be actuatable from a remote location, such as a surface location, to be of use to a well operator. One common configuration for remote actuation of a downhole device such as a flow control device is a pair of hydraulic control lines. One of the lines is employed to force the flow control device to an open position while the other is employed to force the device to a closed position. While such systems work well for their intended purpose, it is axiomatic that a number of flow control devices each having a pair of hydraulic control lines is problematic with respect to the number of control lines that would ultimately need to reach the location intended for remote control (e.g. surface). All such control lines would need to extend through a borehole that in most instances is 9⅝ inches in diameter. Large numbers of control lines in such a small diameter borehole take up space where space is at a premium. This is not an advantageous situation. 
   While the art has proposed several remedies for this issue, each is complex, adds cost, adds potential for malfunction and is overall not a panacea. The art is therefore still in need of a configuration and operative modality for flow control valves that reduces the number of necessary hydraulic control lines while maximizing the number of devices controllable thereby and while maintaining simplicity and cost efficiency of design. 
   SUMMARY 
   Disclosed herein is a control system for a plurality of devices including a plurality of devices in at least one group. A first control line is in operable communication with the plurality of devices. A second control line in operable communication with the at least one group. A step-advance mechanism is in operable communication with each of the plurality of the devices, each mechanism being distinct from each other mechanism within the group of devices. 
   Further disclosed herein is a method for reducing the number of control lines needed to control a plurality of downhole devices including supplying a first control line in operable communication with a plurality of devices, the plurality of devices including at least one group of devices and supplying a second control line in operable communication with the at least one group. The method further includes moving the at least one group of devices to a selected position with a step-advance mechanism. 
   Further disclosed herein is a method for controlling a plurality of devices with two control lines including configuring each device with a distinct step-advance mechanism and alternating pressurization in the control lines to sequentially position the three devices so that following fourteen steps, all possible configurations of the devices have been achieved. 
   Yet further disclosed herein is a system controlling nine devices with four control lines. The system includes a first control line in operable communication with all nine devices, a second control line in operable communication with a group of three of the devices, a third control line in operable communication with a second group of three of the devices, a fourth control line in operable communication with a third group of three of the devices and each of the nine devices having a step-advance mechanism, and wherein the step-advance mechanisms are distinct within groups. 
   Yet further disclosed herein is a method for independently controlling a plurality of groups of devices including supplying a number of control lines equal to the number of groups of devices plus 1 control line. 
   Yet further disclosed herein is a system for controlling a plurality of devices with a reduced number of control lines. The system includes a plurality of devices represented by one or more groups of devices, a number of control lines equal to the number of groups of devices plus one control line. 

   
     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 illustration of a flow control valve actuation configuration utilizing four control lines and actuating nine flow control devices; 
       FIG. 2  is a representative schematic view of a J-slot and bearing sleeve laid flat; 
       FIG. 3  is a schematic view of a J-slot and bearing sleeve arrangement for a first control device in a group; 
       FIG. 4  is a schematic view of a J-slot and bearing sleeve arrangement for a second control device in a group; 
       FIG. 5  is a schematic view of a J-slot and bearing sleeve arrangement for a third control device in a group; and 
       FIG. 6  is a representation of the collective movements of the flow control devices in a nine valve on four line setup. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a system is illustrated that provides for remote control of nine individual flow control devices using only four hydraulic control lines. The configuration and operational functionality is facilitated by grouping of flow control devices and through the incorporation of a step-advance mechanism, which may comprise a J-slot and optionally a bearing sleeve in each flow control device. The illustrations and most of this specification are directed to a three device per group arrangement. It is to be understood however that groups of two devices or four devices are also possible and contemplated as within the scope of the invention. In the specifically illustrated embodiment(s) groupings of flow control devices include groups  12 ,  14  and  16 . Each group includes three flow control devices  18 ,  20 ,  22 ;  24 ,  26 ,  28 ; and  30 ,  32 ,  34 , each device having two positions, those being closed and open, open and choked or choked and closed. This provides a total number of distinct configurations of two to the third power or eight (2 3 =8). This is represented for clarity in the following table: 
   
     
       
             
             
             
           
             
             
             
             
             
             
             
             
             
           
         
             
                 
                 
             
             
                 
               Position 
                 
             
           
        
         
             
               Sleeves 
               1 
               2 
               3 
               4 
               5 
               6 
               7 
               8 
             
             
                 
             
             
               1 
               O 
               C 
               O 
               C 
               O 
               C 
               O 
               C 
             
             
               2 
               O 
               O 
               C 
               C 
               O 
               O 
               C 
               C 
             
             
               3 
               O 
               O 
               O 
               O 
               C 
               C 
               C 
               C 
             
             
                 
             
             
               Where O = Open and 
             
             
               C = Closed 
             
           
        
       
     
   
   Two hydraulic control lines are employed for each group of devices  12 ,  14  and  16  as one line is required to actuate the devices to the home position and one line is required to actuate the devices to the second position. For group  12 , these lines are line  36  and line  38 . The reader will note that line  38  is a home line (home position for purposes of this disclosure is the open position of the devices; it will be appreciated however that home could be any predetermined position to which the device will return when actuated in one direction). Home line  38  is shared by all devices in groups  12 ,  14  and  16  as illustrated. When line  38  is pressured-up then, all devices of group  12  are actuated and move to the home position. Line  38  and individual lines for groups  14  and  16 , i.e., lines  40  and  42  are not shared between groups but are shared among devices within each group. More specifically, line  38  is shared among devices  18 ,  20  and  22 ; line  40  is shared among devices  24 ,  26  and  28 ; and line  42  is shared among devices  30 ,  32  and  34 . Each of lines  38 ,  40  and  42  are “home” actuating lines. Line  36  is common to all devices and actuates to the second (open, choked or closed) position. Each of lines  38 ,  40  and  42  independently actuate only the single group with which they are associated. 
   At this point it is clear that all devices can be moved to the position by line  36  pressure. It is also clear that group  12  devices may all be actuated to the home position by line  38 ; group  14  devices may all be actuated to the home position by line  40 ; and group  16  devices may all be actuated to the home position by line  42 . 
   If it would be sufficient for a particular application to have each device of each group of devices in the same position (i.e., either open or closed; open or choked; closed or choked), then the system so far described is useful in that nine devices are operable by four control lines. 
   Since it is not often sufficient in the downhole environment to have a group of devices, for example devices  18 ,  20  and  22 , all open or all closed or all choked, but rather is often the case that they would be in different positions, further capability in the groups is desirable. To provide the greater variability of positioning among individual devices of each group of devices  12 ,  14  or  16 , each device  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30 ,  32  and  34  is constructed with a step-advance mechanism comprising such as a J-slot and optionally a bearing sleeve. 
   Referring to  FIG. 2 , a J-slot sleeve  46  has been illustrated cut and laid flat for clarity. One of ordinary skill in the art is familiar with J-slot sleeves, their purpose being to guide a pin during reciprocal movement into advancing slots. In the illustration, a number of slot sections  48  and slot sections  50  are shown. The “J-sections”  52  between each slot section pair  48 / 50  are configured to allow a pin  54  to advance in the J-slot sleeve  46  in only one direction. It will be noted that each slot section  48  is the same length in the figure and each slot section  50  is the same length in the figure. In such configuration, there is no specifically controlled movement of the attached device. It is possible in this invention to use J-slots having different slot section lengths to specifically control movement but this relies on the load holding capability of the pin  54 . In higher load situations, which are anticipated for the devices hereof, a bearing sleeve  60  is employed along with the J-slot sleeve  46 , together making up the step-advance mechanism. The purpose of the bearing sleeve  60  is to create a specific control of motion of the attached device and hold the load thereof. Thus bearing lug  62  is appreciably larger in dimension, and therefore strength, than pin  54 . The bearing sleeve  60  is of a stepped configuration allowing for specific position limiting of the bearing lug  62 . 
   In this disclosure, an object is to operate multiple flow control devices with few control lines. In the illustrations, which follow, the individual flow control devices utilize only two positions: open and closed, closed and choked or choked and open. The  FIG. 2  illustration allows for more variability than that illustrated in the balance of the drawings hereof. Upon exposure to more of this disclosure one skilled in the art will appreciate that more variables could be introduced to the concept hereof by lengthening the circumferential step-advance mechanism path. This is done for example by adding more J-steps (each comprised of slot section  48 / 50  and J-section  52 ) to the sleeve. In such a system, it is possible to add more variability regarding positioning and still allow for sufficient stepping to account for all combinations of possible positions. More or fewer J-slot steps is also relevant to groups of devices containing more of fewer devices. For example, other groups of devices are contemplated herein and include for example two or four devices. In a two device group, the step-advance mechanism would have four total positions yielding four steps of the device (three home positions and three second positions). In a four device group the step-advance mechanism would have thirty positions to account for all combinations of device positions. Alternatively, one or more of the devices could have no step-advance mechanism at all while others in the same group would have a step-advance mechanism. By so configuring the system, more devices are available without requiring an unwieldy number of step-advance mechanism positions. It is to be understood that the number of devices operable by the concept hereof is limited only by the number of control lines allowed. Twenty one devices or more can be controlled, for example. Essentially, the concept hereof is mathematically described as number of control lines equal (number of devices/number of devices per group plus 1). 
     FIG. 2  illustrates bearing lug  62  in a position away from home (or open) and stopped from further motion by stop  64  of bearing sleeve  60 . A stop such as this is illustrated more schematically in  FIGS. 3-5  and is referred to here for the clarity offered by the more detailed drawing. As noted above, the  FIG. 2  bearing sleeve provides for variable actuation of a single sleeve. This must be taken into account when considering the following figures and disclosure. Providing this variability in a control line reducing system as set forth herein increases complexity and would require significantly more J-steps to represent each possible interaction. While possible, the number of system pressure-up steps will at some point become unwieldy and outweigh the benefit-ratio of the concept. 
   Referring to  FIGS. 3-5 , schematic illustrations of the J-slot sleeve and bearing sleeve are shown.  FIG. 3  relates to device  18  for a one group system; devices  18  and  24  for a two group system; and devices  18 ,  24  and  30  for a three group system.  FIG. 4  relates similarly to device  20 ; to devices  20  and  26 ; or to devices  20 ,  26  and  32 .  FIG. 5  relates to device  22 ; to devices  22  and  28 ; or to devices  22 ,  28  and  34 . As is now apparent, each device of a group of devices is constructed with a unique bearing sleeve. Because of this, pressuring up on control line  36  may have differing actuation of the three devices in each group. Moving through the various positions of the J-slot sleeve, each group of three devices can be moved through every possible combination of positions. 
   Still referring to  FIGS. 3-5 , the J-slot sleeve representation is of a continuous J-slot with end  56  adjoining end  58  when in tubular configuration. As stated above, the J-slot sleeve portion of this arrangement operates to advance the pin  54  shown in  FIG. 2  thereby also advancing the bearing lug  62  shown in  FIG. 2 . In  FIG. 3  one should appreciate that bearing lug  62  (shown in  FIG. 2 ) cannot move leftwardly in the figure at position  12 ,  8  and  4  but can so move at position  10 ,  6 ,  2  and  14 , with position  13 ,  11 ,  9 ,  7 ,  5 ,  3  and  1  being rightwardly of the figure and unimpeded. These latter positions are the home positions, have in this example being open. The operation of the J-slot and bearing sleeves in  FIG. 3  is the same in  FIGS. 4 and 5  with stops at distinct positions. The stops in  FIG. 4  are at positions  10 ,  8  and  2  and for  FIG. 5  at positions  6 ,  4  and  2 . In each case the stops prevent closure of the associated device when pressure is exerted on line  36  while allowing such closure when stops are not positioned. 
   In each of the J-slot configurations, fourteen positions are shown. This comports with the two positions to the third power statement made earlier as each valve is stepped back and forth between a home position and a second position. This means that the valves are at the home condition at positions  1 ,  3 ,  5 ,  7 ,  9 ,  11  and  13  and at second positions, which are dictated by the stops of  FIGS. 3-5  for positions,  2 ,  4 ,  6 ,  8 ,  10 ,  12  and  14 . One will appreciate this and its cyclic implications for combinations of device position in the table below: 
   
     
       
             
             
           
             
             
             
             
             
             
             
             
             
             
             
             
             
             
             
           
         
             
                 
                 
             
             
                 
               Positions 
             
           
        
         
             
               Sleeves 
               1 
               2 
               3 
               4 
               5 
               6 
               7 
               8 
               9 
               10 
               11 
               12 
               13 
               14 
             
             
                 
             
             
               1, 4&amp;7 
               H 
               C 
               H 
               O 
               H 
               C 
               H 
               O 
               H 
               C 
               H 
               O 
               H 
               C 
             
             
               2, 5&amp;8 
               H 
               O 
               H 
               C 
               H 
               C 
               H 
               O 
               H 
               O 
               H 
               C 
               H 
               C 
             
             
               3, 6&amp;9 
               H 
               O 
               H 
               O 
               H 
               O 
               H 
               C 
               H 
               C 
               H 
               C 
               H 
               C 
             
             
                 
             
             
               Positions: 
             
             
               H = Home Position (= Open), 
             
             
               C = Closed, 
             
             
               O = Open 
             
           
        
       
     
   
   Referring to  FIG. 6 , the foregoing tabular operation is illustrated more graphically. A nine valve (device) system is illustrated however it should be understood that this same figure could represent a three or six device configuration identically. The graphical representations each include three broken lines  70 ,  72  and  74 . Line  70  represents the home position; line  72  the stopped position and line  74  the closed position. The three graphical representations are specifically aligned from top to bottom to provide an indication of the distinctions of actuation among the three devices in each group. These three graphical representations also relate directly to  FIGS. 3-5 . The top most graphical representation  76  relates to  FIG. 3 ; the representation  78  to  FIG. 4  and the representation  80  to  FIG. 5 . 
   By stepping through all fourteen positions of the illustrated embodiments, each possible combination of binary movement for the three valves in each group is achievable and this control for flow in the well is achieved for three valves with only two control lines; for six valves with only three control lines and for nine valves with only four control lines. As noted above: number of control lines equals (number of devices divided by number of devices per group) plus 1. The system as described significantly reduces the problem of overcrowding of the wellbore with control lines. Moreover, since this system uses only two positions for each valve, no graduated fluid pressure in the control line is necessary. This facilitates non-surface located hydraulic initiators and therefore additional benefit to the art in the form of reduced well head crowding since the lines need not exit the wellbore at all. 
   In one embodiment utilizing the above-disclosed concept, a surface control system having predictable and controllable volume and/or pressure capability is provided. This provides for automatic compensation of fluid volumes and/or pressures as the devices age. Furthermore, the control system may be operable remotely. The control system may in one embodiment include a programmable logic system. 
   While preferred 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 illustrations and not limitation.

Summary:
A control system for a plurality of devices including a plurality of devices in at least one group. A first control line is in operable communication with the plurality of devices. A second control line in operable communication with the at least one group. A step-advance mechanism is in operable communication with each of the plurality of the devices, each mechanism being distinct from each other mechanism within the group of devices. Further disclosed herein is a method for reducing the number of control lines needed to control a plurality of downhole devices including supplying a first control line in operable communication with a plurality of devices including at least one group of devices and supplying a second control line in operable communication with the at least one group.