Abstract:
A hydraulic control system can be used on a downhole choke and has the feature of moving a travel stop for a sliding sleeve using discrete j-slot mechanisms for selectively moving the stop in either one of two opposed directions. The valve can be incrementally opened further with pressure cycling on an opening chamber. The valve can be immediately put to the closed position with pressure on a closing chamber. After closing, the valve can assume its former open position or other selected less open positions by reconfiguring the travel stop while the valve stays in the closed position In order to achieve a higher open percent after closing, one or more pressure cycles must be applied to the open chamber after the valve is reopened to the position it was in before it was closed.

Description:
FIELD OF THE INVENTION 
       [0001]    The field of the invention is control systems for hydraulically operated downhole tools and more particularly sliding sleeve valves that operate in multiple positions including fully open and closed. 
       BACKGROUND OF THE INVENTION 
       [0002]    Flow during production is regulated by a valve called a choke. The typical design for a choke comprises a body having a series of lateral ports and a sliding sleeve that has a matching port layout. A hydraulic system is used to move the insert sleeve in opposed directions. The hydraulic system also controlled the movement of the insert sleeve broadly in two different ways, both of which will be described in detail below. 
         [0003]    In the J-slot design cycles of pressure application and removal made a pin follow a j-slot. A lug also on the movable member with the pin followed the pattern defined by the j-slot and with each cycle of application and removal of pressure the lug would encounter a different fixed travel stop that would define a different amount of percentage open for the valve. In one known design of the HCM-A choke offered by Baker Hughes Incorporated the j-slot allows the insert sleeve to go from a diffused position where it is not totally closed to various open positions with the j-slot pattern having two open passages to allow the lug an extra travel distance so that the valve could go to the fully open or fully closed positions. 
         [0004]    In a modification to this valve the hydraulic control system was designed to move the insert sleeve a fixed amount for each pressure up cycle. Removal of the pressure in the second part of each cycle would simply leave the insert sleeve where it was and the next application of pressure would incrementally move the insert sleeve by an amount related to the displaced volume of a piston. Any time the pressure was applied to another control line the insert sleeve would go to the fully closed position. 
         [0005]    The details of both these designs and their shortcomings that lead to the development of the present invention will now be described. 
         [0006]    Referring to  FIGS. 1 and 2 , a valve housing  10  has control lines  12  and  14  that extend to opposite sides of piston  16 . Piston  16  is connected to insert sleeve  18  for tandem movement. Insert sleeve  18  has a hole pattern  20  that moves up and down into and out of alignment with openings  22  in the housing  10 . Seals  24  and  26  straddle ports  22  so that when openings  20  are not between seals  24  and  26  the valve is fully closed. On the other hand when the ports  20  are between seals  24  and  26 , as shown in  FIG. 1 , then the valve is in the diffused position where some flow is possible between ports  20  and  22  through diffuser  28 . Alternating pressure application between lines  12  and  14  forces relative movement of pin  30  in the j-slot pattern  32 . A series of stair step travel stops  34  define how much more open the valve gets in each pressure cycle. The other half of each cycle has the lug  36  landing on the same spot  38  to define the diffused position shown in  FIG. 1 . In each pressure cycle, the lug  36  lands on a different step  34  to represent another opening increment. After a predetermined number of cycles the lug  36  can go to landing  40  for a fully closed position where the openings  20  are no longer between seals  24  and  26 . In the very next cycle it can go to fully open when lug  36  is allowed to keep traveling by slot  41  until it hits stop  42 . 
         [0007]    This design does not allow the valve to always be closed with a single command. The design also usually requires multiple commands to reopen the valve after closure to a desired position. This mode of operation can result in additional wear on the ports  20  and  22 . In some instances, operators wanted the ability to step the valve to different opening percentages but to also have the ability to snap it closed without having it go through any steps. The design in  FIGS. 1 and 2  couldn&#39;t do this. What it could do is shown in  FIG. 3 . In each cycle it could open incrementally more and go to a diffused position where flow through it was fairly close to nothing. As a result a spike pattern of percent open was created and no provisions existed for a rapid close by skipping any part of the sequence illustrated in the j-slot of  FIG. 2 . 
         [0008]      FIG. 4  represents a modification of the original design in  FIGS. 1 and 2  that works on the principle of using a predetermined displaced volume to get a predetermined movement of an insert sleeve. Rather than going to almost closed in each cycle the insert sleeve just stays in position until the next cycle bumps it a finite amount proportional to the displaced hydraulic fluid volume. Another feature of this system is that it can be taken to closed immediately by applying pressure on one of the control lines. 
         [0009]    The design in- FIG. 4  includes the following components: Line  44  supplies opening pressure to the mechanism and is connected to lines  48  and  46 . Line  48  supplies pressure to piston  50 . Line  46  supplies pressure to plunger  76  which is connected to piston  74 , lines  68 ,  66  and  90  furnish pressure from the control mechanism to the valve  62  to cause the valve to open. Line  92  furnishes pressure to the valve to cause it to close. Piston  50  is used to move the valve from the fully closed position to the diffused position (such as is shown in  FIG. 1 ). Piston  74  is used to move the valve sequentially to different opening positions. Spring  84  causes piston  74  to move to the left when pressure is bled off of line  44 . The surface  86  of plunger  76  allows fluid to bypass plunger  76  during its movement to the left. 
         [0010]    The operation of this control system will now be described. Initial application of pressure to line  44  will transmit through line  48  causing Piston  50  to move to the right until it stops and seals at face  94 . This causes fluid in chamber  64  to move through lines  66  and  90  causing valve  62  to move from the closed position to the diffused position. Continued application of pressure to line  44 , which is also communicating through Line  46  with plunger  76 , will now cause plunger  86  and piston  74  to move to the right compressing spring  84  and causing fluid in chamber  70  to move through lines  68  and  90  moving valve  62  from the diffused position to the first open position. At this point, elimination of pressure in line  44  will allow spring  84  to move piston  74  and plunger  76  to the left. The design of plunger  76  includes the surface  86  which allows fluid from lines  44  and  46  to bypass plunger  76  during this leftward movement. Piston  50  does not move and stays in contact with face  94 . A second application of pressure to line  44  will communicate trough line  46  to plunger  76  causing it to again move to the right which induces fluid to flow from chamber  70 , through lines  68  and  90  to valve  62 , moving valve  62  from opening position number  1  to opening position number  2 . This elimination and application of pressure to line  44  will cause the valve  62  to consecutively move to opening positions  3 ,  4 ,  5 , etc. 
         [0011]    Any time the above opening sequence is interrupted by elimination of pressure from line  44  combined with application of pressure to line  92 , full closure of the valve  62  is achieved. During this closure, fluid is exhausted from valve  62  through line  90  to lines  68  and  66 . The exhaust flow in line  68 , along with aid of spring  84 , cause piston  74  and plunger  76  to move fully to the left. The exhaust flow in line  66  will cause the piston  50  to mover fully to the left. Continued exhaust flow from valve  62  is through lines  90  and  66  to chamber  64  and then through check valves  54  and  52  to lines  48  and  44  which enables the exhaust flow to be vented to surface. Now the valve  62  is fully closed. Valve  62  can now be re-opened as described above by application of pressure to line  44 . However, note that in order to return valve  62  to the previous open position (that is occupied before closure) may require multiple pressure applications to line  44 . Note also that any gas present in chambers  70  and  64  may affect the ability of piston  74  and plunger  76  to move valve  62  accurately to the next open position. 
         [0012]    The present invention presents a control system for a hydraulic control valve, for example, that allows incremental opening in steps by cycling pressure to an opening chamber. Removing pressure to the opening chamber sends the system into a neutral position. Applying pressure to a closing chamber closes the valve by moving the insert sleeve to the closed position. Reapplying pressure after closure on the opening side returns the valve to the position it was in before it was closed. On the other hand, cycling pressure on the closing chamber can allow the valve to be subsequently reopened at any smaller percentage opening than it was in before it was closed. To open the valve to an open percentage that is higher than open position it was in when it was closed, pressure cycles are applied to the opening line. A split j-slot is employed to cycle the valve incrementally toward greater percentage openings on one half of the j-slot while on the separate j-slot the cycling allows the valve to be positioned to subsequently open at a desired percentage opening while staying closed as the cycling takes place. The cycling at either of the separate j-slots allows a travel stop for the insert sleeve to be repositioned. In essence the j-slot cycling creates relative rotation in either direction to extend or retract a travel stop for the insert sleeve. Pressure applied to the opening chamber always urges the insert sleeve to move toward the movable travel stop. Pressure applied to the closing chamber always urges the insert sleeve toward its fully closed position away from the movable travel stop. These and other features of the present invention will be more readily apparent from a review of the description of the preferred embodiment and the associated drawings that appear below with the understanding that the claims set out the full literal and equivalent scope of the invention. 
       SUMMARY OF THE INVENTION 
       [0013]    A hydraulic control system can be used on a downhole choke and has the feature of moving a travel stop for a sliding sleeve using discrete j-slot mechanisms for selectively moving the stop in either one of two opposed directions. The valve can be incrementally opened further with pressure cycling on an opening chamber. The valve can be immediately put to the closed position with pressure on a closing chamber. After closing, the valve can assume its former open position or other selected less open positions by reconfiguring the travel stop while the valve stays in the closed position In order to achieve a higher open percent after closing, one or more pressure cycles must be applied to the open chamber after the valve is reopened to the position it was in before it was closed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a section view of a known choke valve in the diffused position; 
           [0015]      FIG. 2  is the valve of  FIG. 1  showing the j-slot portion of it rolled open; 
           [0016]      FIG. 3  shows the progression of percentage open per pressure cycle on the valve of  FIG. 1 ; 
           [0017]      FIG. 4  is a schematic representation of a different known control system for the valve of  FIG. 1  which works on the principle of displacement of a predetermined fluid volume; 
           [0018]      FIG. 5  is the progression of percentage opening with each cycle for the valve of  FIG. 1  using the control system of  FIG. 4 ; 
           [0019]      FIG. 6  is a section view of the control system of the present invention in a neutral position; 
           [0020]      FIG. 7  is a view along section lines  7 - 7  of  FIG. 6 ; 
           [0021]      FIG. 8  is a view along section lines  8 - 8  of  FIG. 6 ; 
           [0022]      FIG. 9  is a section view of the control system in a neutral position with the valve closed; 
           [0023]      FIG. 10  is the view of  FIG. 9  during an opening cycle; 
           [0024]      FIG. 11  is the view of  FIG. 10  showing the completion of an opening cycle; 
           [0025]      FIG. 12  is the view of  FIG. 11  showing the closed position; 
           [0026]      FIG. 13  is a layout of the opening j-slot showing pin movement on the piston and how it moves the j-slot; and 
           [0027]      FIG. 14  shows how the pin of  FIG. 13  is spring loaded to laterally deflect to allow it to exit from the j-slot without moving the j-slot. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    For continuity,  FIG. 6  shows the insert sleeve  18 , for the valve in  FIG. 1 . The present invention is focused on the control system and one application is on a valve with a basic structure as shown in  FIG. 1  although uses on other downhole tools are envisioned. There are two control lines  100  and  102  that extend from the surface. Line  100  branches into lines  104  and  106  and line  102  branches into lines  108  and  110 . Line  104  goes into opening port  112  in body  114 . Line  108  goes to closing port  116  in body  114 . A piston  118  defines opening chamber  120  and closing chamber  122  between itself and body  114  with the aid of seals  124 ,  126  and  128 . Piston  118  has a key  130  that rides in track  132  in the body  114  to limit the movement of piston  118  to longitudinal only without relative rotation. Piston  118  supports upper j-slot pin  134  and lower j-slot pin  136 . Pin  134  can selectively enter and exit j-slot assembly  138  on travel stop  142  for rotation of travel stop  142  in a manner so as to do up thread  144  to bring top end  146  closer to surface  148  which forms part of the body  114 . This is done by cycling pin  134  in and out of the j-slot  138  as will be described below. Similarly, pin  138  can engage j-slot assembly  140  that is on the travel stop  142  as is j-slot assembly  138 . Cycling pin  136  in and out of j-slot assembly  140  undoes thread  144  and brings end  146  away from surface  148 . Spring  150  urges piston  118  to the right extracting pin  134  out of j-slot  138  and spring  152  urges piston  118  to the left extracting pin  136  out of j-slot  140 . 
         [0029]    Referring to  FIGS. 13 and 14  and using pin  134  as an example,  FIG. 13  indicates that pin  134  can translate in tandem with piston  118  in opposed directions  154 . As the piston  118  moves up to compress spring  150 , pin  134  moves into position  156 . From that point on any further translation along travel stop  142  by pin  134  will turn stop  142  in direction  158  as pin  134  rides on ramp  160  of the now rotating travel stop  142 . When pin  134  gets to position  162  the piston  118  cannot move to further compress spring  150 . At that point applied pressure that drives the piston  118  in that direction is removed and spring  150  reverses the motion of piston  118  but still along a longitudinal path  154 . Again, piston  118  is keyed at  130  to body  114  and cannot rotate. As a result, pin  134  under the force of spring  150  rides down surface  164  to position  166 . As spring  150  continues to push on piston  118 , the pin  134  is forced to move transversely to the movement of piston  118  in direction  168  and against the bias of spring  170 . This movement allows the pin  134  to ride down ramp  174  to location  172  without rotating the travel stop in a direction opposite to  158 . Resisting this tendency of the travel stop to move opposite direction  158  as pin  134  moves from position  166  to  172  is the pitch and friction forces in thread  144 . Once clear of the j-slot assembly  138  by moving from position  172  to  176  under bias on piston  118  from spring  150 , spring  170  now can relocate pin  134  to the  FIG. 14  position and that puts pin  134  in position  178  ready to repeat the cycle just described and incrementally rotate travel stop  142  toward shoulder  146  and in turn allow the insert sleeve  18  to move higher for the next open increment of valve. This process can be repeated from a valve closed position through as many increments as the j-slot assembly  138  has for opening the valve to the full open position. Once full open is obtained the piston  118  has to be cycled in the opposite direction so that pin  136  will move selectively in and out of j-slot  140  to rotate it in direction  180  so as to bring end  146  away from surface  148 . The pin  136  is spring loaded so that it can interact with j-slot assembly  140  in the manner described above for pin  134 interacting with j-slot  138  but the movement of the travel stop  142  is in direction  180  rather than  158 . It should be noted that although pins  134  and  136  are described as being spring loaded, the same result can be obtained by putting j-slots  138  and  140  on spring loaded sleeves that go over the travel stop  142  while fixedly connecting pins  134  and  136  to piston  118 . 
         [0030]    It should further be noted that applying pressure in line  100  puts pressure in line  106  that urges the insert sleeve  18  toward travel stop  142 . At the same time, pressure also goes to line  104  and into chamber  120  to move piston  118  and pin  134  into selective engagement with j-slot assembly  138 . With each application of pressure in line  100  insert sleeve hits the travel stop  142  and pin  134  rotates travel stop  142  along thread  144  to bring end  146  higher or closer to surface  148 . With each removal of pressure from line  100  pin  134  is pushed out of j-slot  138  by the action of spring  150 . Removal of pressure from line  100  does not shift insert sleeve  18 . As pressure cycles in line  100  are repeated the valve opens incrementally but holds it previous position in each pressure release portion of every cycle. The opening increments are preferably identical but they don&#39;t have to be. Differing opening increments can be achieved by changing the slope lengths or/and angle of inclination in the j-slot assembly  138 . 
         [0031]    When pressure cycles are applied to line  102 , the pressure in line  110  causes the insert sleeve  18  to go closed. Repeated application and removal of pressure to line  102  will not move insert sleeve away from its closed position. What such cycles through line  108  will do is to cycle pin  136  in and out of j-slot assembly  140  to turn it in direction  180  and to undo thread  144  to bring travel stop  142  away from surface  148 . In this manner, the valve can be positioned to where it was before it was closed initially with pressure in line  102  so that the next time after an initial pressure cycle in line  102  a subsequent pressure cycle in line  100  will open the valve to exactly the same percentage opening it was in when it was previously closed. As another option, with the valve having been closed in any given position by applying pressure to line  102 , the valve can be manipulated without opening it by pressure cycles in line  102  so that when a pressure cycle is then applied to line  100  the valve can first open to a position different than it was in when it was initially made to close with the first pressure cycle in line  102 . In another mode of operation, after the valve is closed with a pressure cycle in line  102  it can then be made to open the next lower increment by adding one cycle to line  102  followed by a cycle in line  100 . Going to the next more open increment from closing with a cycle in line  102  is accomplished by first cycling once in line  100  to get the valve to open to the same position that it was in before it closed and then adding as many cycles in line  100  as needed to further open the valve. It should be noted that once the valve is cycled to fully open with pressure cycles in line  100  that it can&#39;t continue to be cycled in line  100  to smaller opening positions of the valve. This is because the travel stop  142  is translated by rotating it on thread  144 . When travel stop  142  is in its closest position to surface  148  representing the full open position of insert sleeve  18  pushed up against stop  142  by pressure in line  106 , that sleeve  142  has to now be rotated in direction  180  by pressure cycles in line  108  to move the travel stop  142  in as many desired increments to the new position needed for the valve to be in when it is made to open with a pressure cycle in line  100 . 
         [0032]      FIG. 9  shows the parts in position with no pressure applied to lines  100  and  102  and springs  150  and  152  keeping pins  134  and  136  on piston  118  respectively out of j-slots  138  and  140 . In  FIG. 10  pressure has been applied to line  100  to engage pin  134  with j-slot  138  while compressing return spring  150 . In  FIG. 11 , the pressure is removed from line  100  and a neutral position for both pins  134  and  136  out of their respective j-slots is assumed with spring  150  now relaxed. Finally in  FIG. 12  pressure is applied to line  102  causing pin  136  to engage j-slot  140  to turn travel stop  142  in direction  180 . 
         [0033]    The present invention provides for a movable travel stop that allows incremental opening of the valve by sequentially shifting a travel stop while using hydraulic pressure to cycle the insert sleeve  18  against it. Cycling in sequence from fully closed to fully open can be accomplished in a series of pressure cycles delivered through line  100 . At any time applying pressure to line  102  will force the valve to close. If the very next pressure cycle is in line  100  then the valve will resume the open position it had before it was closed. If the next pressure cycle or cycles after the initial cycle in line  102  is one or more additional cycles in line  102 , then the valve will not open but each cycle will bring the travel stop  142  further from surface  148  so that the next time pressure is cycled to line  100  will result in the valve opening but to a position that is not as open as it was when it was closed initially. The pins  134  and  136  that drive their respective j-slots  138  and  140  are preferably spring loaded so that they can exit their respective j-slots without driving their respective j-slots in a direction opposite to the respective intended drive direction. 
         [0034]    While the travel stop  142  is shown to be adjusted using a thread  144  a j-slot can also be used to shift its position as piston  118  moves back and forth. While the control system is shown for use in the preferred embodiment for use with a choke it can be used with other downhole tools that operate by a series of discrete movements to accomplish a task downhole. 
         [0035]    It is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims.