Abstract:
A pressure equalizing tool can be run into a downhole tool on wireline or coiled tubing preferably and temporarily secured before being actuated to separate two components in a downhole tool that are in a sealing relation but are configured to be temporarily movable so as to allow pressure equalization before the downhole component is actuated. Once pressure is equalized the equalizing tool is released, usually with an applied pick up force and the downhole tool being equalized as to differential pressure can be operated with the preexisting actuation parts that are on the downhole tool. In a preferred embodiment the downhole tool is a ball valve and the equalizing tool is temporarily secured to the ball valve housing to temporarily part the ball from the uphole seat to equalize an annular space around the ball with tubing pressure. The ball is allowed to go back to contact with the seat when the equalizing tool is released and removed from the tubing.

Description:
FIELD OF THE INVENTION 
     The field of the invention is downhole tools that are constructed in a manner that make it possible to trap high differential pressures on movable components, which makes the components hard to move with actuation equipment unless such pressure differentials are equalized. In that context various tool embodiments are used to equalize pressure to enable subsequent operation using the normal actuation components. 
     BACKGROUND OF THE INVENTION 
     Downhole tools are controlled from the surface or locally by control systems to move a component between two or more positions. The movable components are exposed to highly variable tubing pressures and can be constructed in ways where pockets that trap pressure at some pressure level can form with a resulting high differential pressure across a tool component that is high enough to prevent the normal actuation system from operating the tool into another position. 
     One example of such a tool is a barrier valve that uses a 90 degree rotating ball. In some designs the ball turns between opposes seats that can have a resilient seal in contact with the ball. The actuation system can be in part in an annular space that is in communication with the passage in the ball around its pivot axis. When the valve is open tubing pressure and the annular space equalize through the small passage around the ball pivot axis. The ball can be closed during a time when the tubing pressure is low. Thereafter with the ball in the closed position and the annular space around the ball and the passage in the ball isolated from tubing pressure, pressure can build on the ball under conditions where the differential across the ball from tubing to the annular space results in increased contact frictional force so that the mechanism that would rotate the ball under normal operation is not strong enough to turn the ball back to the open position. Merely adding pressure above the ball during these circumstances just increases the differential across the ball with respect to the annular space and aggravates the contact loading problem. 
     The present invention in its various embodiments addresses this problem by equalizing pressure into the annular space by separation of a ball from its uphole seal in a rotating ball environment for a downhole valve. Other applications where trapped low pressures create loading to the point where the tool will not move normally are envisioned. 
     Equalizing devices in downhole tool and more particularly flapper type safety valves are well known as shown in Fineberg U.S. Pat. No. 4,478,286 and which included a spring loaded plug in the flapper that is actuated by a flow tube. Other equalizing devices are shown in U.S. Pat. Nos. 7,204,313; 6,848,509; 3,799,204; 6,644,408; 6,296,061; 6,283,217; 6,079,497 and 5,752,569. These valves generally have an equalizing valve built into a flapper to be actuated by the advancing flow tube before the flow tube tries to move the flapper. Alternatively the valve can be built into the housing to equalize across a closed flapper as a result of initial flow tube movement that occurs before the flow tube engages the flapper. 
     While the objective of the present invention is equalization to enable operation when large pressure differentials are present, its execution of that objective is different from the above described equalizing mechanism. Rather, in one embodiment a tool is delivered to the downhole tool needing pressure equalization. The tool is anchored and actuated to separate two members that are in sealing contact using built in flexibility of these parts to move relatively to each other. There after the tool is released and removed. It can be delivered quickly by wireline with a jar actuated to operate the tool or in another embodiment it can be delivered on coiled tubing and respond to pressure applied through the coiled tubing to operate. It can be released with a pickup force on the coiled tubing. Other embodiments are envisioned. Those skilled in the art will more fully appreciate the various aspects of the present invention by reviewing the descriptions of the embodiments described below in conjunction with the associated drawings while recognizing that the full scope of the invention is found in the appended claims. 
     SUMMARY OF THE INVENTION 
     A pressure equalizing tool can be run into a downhole tool on wireline or coiled tubing preferably and temporarily secured before being actuated to separate two components in a downhole tool that are in a sealing relation but are configured to be temporarily movable so as to allow pressure equalization before the downhole component is actuated. Once pressure is equalized the equalizing tool is released, usually with an applied pick up force and the downhole tool being equalized as to differential pressure can be operated with the preexisting actuation parts that are on the downhole tool. In a preferred embodiment the downhole tool is a ball valve and the equalizing tool is temporarily secured to the ball valve housing to temporarily part the ball from the uphole seat to equalize an annular space around the ball with tubing pressure. The ball is allowed to go back to contact with the seat when the equalizing tool is released and removed from the tubing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of the equalizing tool in the run in position; 
         FIG. 2  is the tool of  FIG. 1  in the anchored position and before pressure is equalized; 
         FIG. 3  shows the tool of  FIG. 2  anchored in a ball valve in the closed position and the tool actuated to equalize pressure and the upper seat assembly; 
         FIG. 4  shows the ball and lower seat assembly of the ball valve of  FIG. 3 ; 
         FIG. 5  is an alternative embodiment of the equalizing tool when run in on tubing; 
         FIG. 6  is the tool of  FIG. 5  shown anchored in a ball valve and pressure equalized. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows the equalization tool  10 . It has a lower body  12  and a dog housing  14  secured at thread  16 . Dog housing  14  has openings  18  through which dogs  20  can be extended. A top sub  22  retains ring  24  internally so that actuator  26  can be fully extended to the position in  FIG. 1  without coming out of the top sub  22 . Top sub  22  is secured to the dog housing  14  at threads  28 . Actuator  26  has a larger outer diameter  30  and a small outer diameter  32  separated by tapered surface  36 . In the run in position of  FIG. 1  the tool  10  has the actuator  26  fully extended so that the small outer diameter  32  is under the dogs  20  so that the dogs  20  are retracted into the openings  18 . Actuator  26  has an internal groove  38 . The tool  10  is run in on wireline  40  with a jar tool or other known tool that can create a jarring force on actuator  28  preferably at groove  38  with the jarring force shown schematically as arrows  42 . Those skilled in the art will appreciate that in the  FIG. 1  position a snap ring  44  is held in groove  46  by the dog housing  14 . Inside the dog housing  14  is a release sleeve  48  that is shear pinned to dog housing  14  with a shear pin. A gap  52  is formed between the dog housing  14  and the release sleeve  48  to allow the lower end  54  of the actuator  26  to enter when the jar tool force  42  is applied. Internal recess  56  at the top of the release sleeve  48  can be grabbed by a fishing tool, not shown, for an emergency release of the dogs  20  as will be explained below. The jarring movement  42  puts the larger outer diameter  30  under the dogs  20  to cam them all out so that they can engage the tool to be equalized as will be discussed later in regard to  FIG. 3 . The only resistance offered by actuator  26  to moving down is any force required to make snap ring  44  jump out of a groove  58  that it sits in for run in and into another groove  60  where it snaps out with the dogs  20  in the extended position as shown in  FIG. 2 . The rating of shear pin  50  is considerably higher than the force required to drag the snap ring  44  from groove  58  to groove  60  and the friction force from it dragging on the inside surface of dog housing  14 . 
     Lower body  12  has a piston  62  that is initially secured with a shear pin  64 . Seals  66  and  68  define atmospheric or low pressure chamber  70 . Seals  72  and  74  seal the chamber  70  and the piston  62  initially to the release sleeve  48 . A hard seat  76  is secured at thread  78  to the piston  62 . A soft seat  80  is held by a retainer  82  to the hard seat  76 . In a ball valve application as shown in  FIG. 3 , the soft seat  80  lands on the ball  84 . The tool  10  has an open through passage  86  that gets obstructed when the soft seat  80  lands on the ball  84 . Because of the passage  86  the tool  10  can be run in with wireline  40  at a high rate of speed. After the tool  10  is locked in position with dogs  20 , surface pressure buildup acts on piston  62  to break the shear pin  64  to move the piston  62  against the low pressure chamber  70 . This movement of the piston  62  moves the ball  84  to equalize pressure to annular space  96 , as shown in  FIG. 3 . Passage  73  is exposed during emergency release when shear pin  50  is broken by an upward jar at fishing neck  56  of release sleeve  48  by a second jar tool schematically shown as  43  if the support for the dogs  20  by surface  30  cannot be undermined for removal of tool  10 . Moving the release sleeve  48  opens chamber  70  to tubing pressure to equalize tubing pressure on piston  62 . 
       FIG. 2  shows the tool  10  landed on the ball  84  with the actuator  26  pushed down so that the dogs  20  are extended by surface  30  to lock the tool  10  in position as can be seen by looking at  FIG. 3 , which is the top of the ball valve  88  while  FIG. 4  is the bottom of valve  88 . The tool  10  is shown in  FIG. 3  after equalizing has taken place with shear pin  64  broken.  FIG. 2  shows the dogs  20  extended before shear pin  64  is broken and  FIG. 3  shows how the dogs  20  lock the tool  10  to the ball valve  88 . As seen in  FIG. 3 , when the tool  10  lands on the ball  84  the dogs  20  are presented opposite groove  90  in upper seat assembly  92 . Groove  90  is longer than dogs  20  so that after dogs  20  are extended and the pressure is built up, there is room for lower housing to move up to break shear pin  64  so that the applied pressure on piston  62  can ultimately move the ball  84  away from seal  94  for pressure equalization. When actuator  26  is pushed down the dogs  20  are extended and locked to the groove  90 . Upper seat assembly  92  has a seal  94  that is against the ball  84 . When there is pressure equalization the ball  84  is pushed by the tool  10  away from seal  94  to equalize an annular space  96  with tubing pressure at  98  above the ball  84 . As the equalizing is done the pressure at  98  can be brought close to the pressure below ball  84  at  100  so that the ball  84  is equalized from above and below before it is to be rotated. 
     The workings of the valve  88  will now be briefly explained. Starting at the lower end there is an assembly that is preloaded by a spring  102  adjusted by changing the position of nut  104 . Nut  104  pushes on lower seat assembly  106  which has a lower seal  108  pushed against the ball  84 . An open cage  110  loosely secures the lower end of upper seat assembly  92  and its seal  94  to the ball  84  as well as securing the upper end of lower seat assembly  106  and its seal  108  to the ball  84 . The upper ball seat assembly  92  is ultimately pushed toward the ball  84  by a spring  112  putting a force on ring  114  which is mounted to the upper ball seat assembly  92 . The cage  110  supports ball  84  through opposed pins  116  and  118  for 90 degree rotation between an open position (not shown) and a closed position seen in  FIGS. 3 and 4 . 
     A control system is used to rotate the ball  84  through control line connections  120  shown in  FIG. 3 and 122  shown in  FIG. 4 . Each connection has a piston  124  and  126  respectively. Pistons  124  and  126  are connected to opposite ends of a slide  128  that has a pin connection  130  shown in dashed lines in  FIG. 3  to the ball  84  that is offset from its center pivots  116  and  118 . Slide  128  slides through a recess (not shown) in the cage  110 . Relative movement between the moving slide  128  and the stationary cage  110  rotates the ball. The direction of rotation is determined by which port  120  or  122  is pressurized and which has the pressure removed. The exterior of the upper seat assembly  92  is sealed to the housing of the valve  88  at seal  132 . The lower seat assembly  106  is sealed to the housing of valve  88  at seal  134 . The passage  136  through the ball  84  communicates with annular space  96  through a weep hole  138  near pivot  118 . The annular space  96  extends from seal  132  to seal  134  and outside the ball  84  and the upper and lower seat assemblies  92  and  106 . 
     What can happen is that the ball  84  can be in an open position when tubing pressure at  98  and  100  is fairly low such as 300 PSIG for example. Through weep hole  138  with the ball  84  open, the annular space  96  will equalize to that same 300 PSIG pressure. When the ball  84  is then closed the annular space  96  and the ball passage  136  are now isolated from tubing pressure above and below the ball due to seals  94  and  108  literally on the ball and seals  132  and  134  outside the upper and lower seat assemblies  92  and  106 . The weep hole  138  just communicates the sealed off passage  136  inside the ball  84  to the annular space  96 . The pressure can then go up either above the ball  84  at  98  or below the ball  84  at  100 . The differential can rise to thousands of pounds to the point where the ball  84  can experience loading to the point where the pressure applied at the hydraulic connections  120  or  122  will not get the ball to turn or may result in shearing the drive pin  130  at the location that it extends from the ball  84 . Simply adding pressure above the closed ball  84  just causes additional loading as the pressure differential across it is enhanced. 
     This frictional loading problem caused by high differential pressure across the ball  84  is resolved by the tool  10 . As shown in  FIG. 3  the tool  10  is anchored using dogs  20  in groove  90  in the upper ball seat  92 . With soft seat  80  landed on the ball  84  and dogs  20  latched to groove  90  of upper ball seat assembly  92 , applying pressure in the tubing at  98  breaks shear pin  64 . Tubing pressure at  98  is present above piston  62  and low or atmospheric pressure is in chamber  70  allowing the piston  62  to move down forcefully and reduce the volume of chamber  70  while pushing down on ball  84  as the tool  10  is anchored at dogs  24 . The pushing of the ball  84  by the soft seat  80  separates the ball  84  from the seal  94  to allow the annular space  96  to equalize with whatever pressure was applied above the ball  84  at  98 . The gap is made possible by slack between the cage  110  and where it retains the upper and lower seat assemblies  92  and  106  respectively. In essence spring  102  is compressed and spring  112  is extended as a gap is created by the tool  10  between the seal  94  and the ball  84 . If the pressure at  98  is selected close to that below the ball  84  at  100 , the operation of the tool  10  essentially makes the pressure in the annular space  96  and inside the ball at  136  the same as in the tubing so that the hydraulic system can operate the ball  84  in the normal manner. 
     Referring now  FIGS. 5 and 6  a different embodiment of the equalizing tool  200  is illustrated. It is run preferably on coiled tubing  202  but it can be run on rigid tubing in the alternative although it would take far longer to get it into position into a downhole tool such as a ball valve  88  located on a tubing string. The tubing  202  is connected to mandrel  204  at thread  206 . A passage  208  runs through the mandrel  204  to a port  210  that leads into an annular passage  212 . Piston  214  has seals  216  and  218  to allow pressure delivered through the coiled tubing  202  to reach the piston  214  to drive it along of mandrel  204  after breaking shear pin  219 . Also mounted to mandrel  204  is a cone  220  with a seal  222 . A slip ring  224  is supported by the mandrel  204 . It has a series of slips  226  that are initially retained to the mandrel  204  by a shear pin or pins  228 . As in the other embodiment there is at the lower end of piston  214  a soft seat  230  to contact the ball  84  and a retainer  232  surrounding the soft seat  230  for support. 
     In operation, as shown in  FIG. 6 , the soft seat  230  is landed on the ball  84  and pressure is built up in passage  208  so that the cone  220  is driven under the slips  226  to drive them out, while breaking pin  228 , against the upper seat assembly  92  that is shown in  FIG. 3  with the other embodiment. At this time pin  219  is not yet broken but the tool  200  is now anchored. A further pressure buildup breaks the pin  219  and the piston  214  is extended to push the ball  84  from its seal  94  shown in  FIG. 3  for pressure equalization. It should be noted that pressure outside the tool  200  is applied as pressure is equalized so that the annular space  96  will then be at a pressure close to the pressure downhole of the closed ball  84  to allow simple operation of the ball  84  without concern of breaking the actuation mechanism due to the frictional contact force from high pressure differential as the actuation systems attempts to rotate the ball  84  to the open position. Cone  220  can be biased to the retracted position by reducing pressure in annular space  212  to make the cone  220  and the piston  214  retract toward each other so that the tool  200  can be pulled out with the coiled tubing  202  because the slips  226  have become unsupported by the retraction of the cone  220 . 
     Those skilled in the art will appreciate that the tools  10  or  200  allow for pressure equalization for components operated in a downhole tool from a remote location. There are no additional valves added to an assembly within the tool housing. Instead an equalizing tool is rapidly deployed to the downhole tool and simply physically separates a downhole component from an adjacent seal to equalize pressure between formerly isolated zones affecting the component so the actuation system operated from outside the downhole tool can move the component without damage to the actuation system or the component from component loading that otherwise occur when there are significant pressure differences across the component before it is urged to move. In some cases such a valve the component can be a ball. Other applications where an actuated component can be placed under a pressure imbalance that needs to be equalized before the component is moved are also envisioned. 
     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: