Abstract:
Two subs are held in a fixed position relative to each other when assembled to a string and run into a wellbore. A reservoir of fluid is defined in a wall between the subs. The reservoir has one or more outlets connected by a short jumper line to an adjacent tool to be operated. At the appropriate time, set down weight breaks a shear pin to reduce the reservoir volume and create pressure in the exit lines. The exit lines can be connected to operating pistons in adjacent tools to actuate them or to perform other desired functions using a stream of pressurized fluid. The device can be set for one time or multiple cycles where fluid in the reservoir can be replenished and re-pressurized for multiple cycles of operation.

Description:
FIELD OF THE INVENTION 
     The field of this invention is downhole tool that require hydraulic pressure to perform a function and a way of generating that pressure without resort to a control line extending from the surface where that pressure is generated or pressure transmitted through the well tubulars and instead using string manipulation to locally generate the pressure to perform a downhole function. 
     BACKGROUND OF THE INVENTION 
     A wide variety of tools for downhole applications are operated on supplied fluid pressure. One of the most common ways to supply hydraulic pressure to downhole components in a bottom hole assembly is to run a control line from the surface. A control line is secured outside a tubing string and connected at the surface to a source of fluid pressure and at the other end to a housing of a downhole tool. Generally, when pressure is applied from the surface through the control line it is communicated to the tool housing where it moves a piston that actuates the tool to perform a downhole operation. Subsurface safety valves commonly operate this way. They are designed to stay in the open position as long as control line pressure is applied. Applying pressure compresses a return spring acting on the flow tube. Applying pressure shifts the flow tube to rotate a flapper to hold the valve open. A loss of control line pressure allows the spring to return the flow tube up to allow the flapper to close generally under the further bias of a pivot pin mounted spring. 
     Other variations involve using internal tubing pressure applied form the surface. In these designs there is a ball seat that receives a ball. When the ball has landed pressure can be built up to actuate the tool. In some designs the ball on the seat can be blown out with a further increase in pressure beyond what it took to operate the tool so that the internal passage in the tool is at least partially cleared for running other tools even further into a well. These designs require special features and can shock a formation below when the ball and its seat are blown out or alternatively when the ball is blown through the seat. 
     Sometimes tools designed for one job are retrofitted to other jobs but require modification to function in the new application. For example downhole wet connects are devices that mate an upper portion of a string to a lower portion. These devices feature an orientation pin on one half of a connection and a longitudinal groove usually having a broad tapering entrance to initially grab the alignment pin and cause some relative rotation so that the two parts of the string can be mated downhole. Wet connects generally connect the main bores in the upper and lower tubular strings as well as connecting adjacent conduits for such purposes as a control line for a subsurface safety valve, for example. Once wet connect connections are fully mated, they generally need to be locked together and such locks or anchors have been in the past actuated with hydraulic pressure from an available adjacent control line that the wet connect mated to its downhole counterpart segment. However, some wet connects are not designed to couple hydraulic control lines so a ready source of hydraulic pressure was not available for such designs. One design that connected fiber optic cables had no available hydraulic sources but still needed to be locked in a connected mode. It was this need to adapt a known design for a new application that drove to the discovery of the present invention that not only solved the problem of locking that connection together but further has application in a wide variety of situations where hydraulic pressure is needed for a variety of purposes. In the fiber optic wet connect, for example, not only was hydraulic pressure needed to lock the connection together, but there was a need to clean the fiber cable ends of one or more cable end pairs before the connection was driven home to get drilling fluid or other solids that might impede signal transmission through the cable connection out of the way. The present invention addresses a problem in this context, in a preferred embodiment but its application is far more universal to a wide variety of tools. Variations are also possible to allow multiple pressure sources to deliver pressure to various locations with a single or multiple manipulations of the string. One time operation with a single string manipulation is envisioned as well as multiple actuations from a series of string manipulations with multiple reservoirs or reservoirs that can recharge for reuse. Details of these alternatives will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawing while recognizing that it is the claims that contain the full scope of the invention. 
     SUMMARY OF THE INVENTION 
     Two subs are held in a fixed position relative to each other when assembled to a string and run into a wellbore. A reservoir of fluid is defined in a wall between the subs. The reservoir has one or more outlets connected by a short jumper line to an adjacent tool to be operated. At the appropriate time, set down weight breaks a shear pin to reduce the reservoir volume and create pressure in the exit lines. The exit lines can be connected to operating pistons in adjacent tools to actuate them or to perform other desired functions using a stream of pressurized fluid. The device can be set for one time or multiple cycles where fluid in the reservoir can be replenished and re-pressurized for multiple cycles of operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of a first embodiment of the invention used in conjunction with the anchor portion of a wet connect; 
         FIG. 2  is a section view of the subs that define a chamber to be pressurized when weight is set down; 
         FIG. 3  is an alternative to  FIG. 2  showing a floating piston in the chamber; 
         FIG. 4  is an alternative to  FIG. 3  showing multiple floating pistons and multiple outlets that can be used for different purposes; and 
         FIG. 5  is a variation of  FIG. 4  showing an undercut adjacent one of the floating pistons. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates an anchor section  10  of the upper half of a wet connect having the upper connector portion  12  at its upper end. The lower half of the wet connect assembly containing the other connector mate is not shown. An upper string  14  extends into a sub  16  that defines an internal recess  18  with an outlet  20 . A hydraulic line  22  extends from outlet  20  and is connected to in the preferred embodiment to a connection  24  that actuates a lock between the upper portion of the wet connect  12  and the lower portion of the wet connect after they are pushed together and weight is set down on the upper string  14 . 
       FIG. 2  shows how hydraulic pressure is generated locally to lock the wet connect in  FIG. 1  in a way other than the prior design that depended on a control line run to connection  24  from the surface. Top sub  28  is secured at thread  30  to the upper string  14 , which is not shown in this FIG. In this embodiment, the bottom sub  16  and top sub  28  are configured to create a chamber  32  where preferably an incompressible fluid is stored to preferably fill the chamber  32 . Outlet  20  communicates with chamber  32  and line  22  which leads to an anchor on the wet connect at a connection  24 . From that point on the operation of the anchor is the same as if the pressure source was from a control line that started at the surface. In essence, the pressure moves a piston in the anchor to actuate it when the wet connect segments are fully pushed together engaging the locking collet threads in the anchor section  10  of the upper connector segment with a matching profile in the lower connector segment in a manner known in the art. Chamber  32  is sealed at seals  34  and  36  so that when the wet connect segments are together, setting down weight on top sub  28  will break the shear pin  38  to allow the top sub  28  to advance to reduce the volume of chamber  32  so that pressure builds up in it. That pressure passes through conduit  22  to set a downhole tool such as an anchor for a wet connect that needs to be locked together after being pushed together. It can also serve other purposes. For example, when a wet connect with two ends of a fiber optic cable is being made up, it is good to make sure the abutting exposed ends are free of debris so that the integrity of the optical connection is maintained. In another application of the embodiment shown in  FIG. 2 , fluid can be forced out to reach the fiber optic cable ends on the two parts of the wet connect as they come together to clean debris away from the end area of each fiber optic cable segment. This helps to insure the quality of signal transmission through the made up connection. As will be seen below, this can be accomplished with a single reservoir that not only builds pressure in line  22  that can actuate a tool but also ejects fluid through an orifice, for example, to keep the connection in a tool clean as it is being made up downhole. Those skilled in the art will realize that wholly unrelated applications are envisioned such as shifting sleeves, holding safety valves open, setting anchors or operating lock mechanisms, to name but a few possible applications. The present invention allows elimination of one or more control lines from the surface. 
     The mechanism of the present invention as shown in  FIG. 2  can be adapted for single application or multiple applications. Without the optional passage  40  and an associated check valve  42  shown schematically in  FIG. 2 , an initial setting down weight will break the shear pin  38  and initiate a one time pressure buildup to operate a tool or perform another downhole function. In that version, once weight is set down the pressure is applied. In systems where some of the pressurized fluid is allowed to escape such as for a purpose of displacing debris before a downhole connection is made, the loss of fluid from the system could mean that an insufficient volume of incompressible fluid could remain to re-establish the initial pressure generated from the original settling down weight and reduction of the volume of chamber  32 . However, it is possible to have a system of being able to recharge the chamber  32  with well or other fluids for example stored in other compartments in sub  28  and a way to do this is to provide a passage  40  which can optionally have a check valve  42  that only allows fluid into chamber  32  when top sub  28  is picked up. In  FIG. 2  passage  40  is shown terminating in passage  44  formed by subs  28  and  46 . Alternatively passage  40  can lead into the surrounding annulus  48  or to an enclosed compartment of clean fluid within sub  28  or in the string above it. Using passage  40  the chamber  32  fills when sub  28  is picked up because such movement reduces pressure in chamber  32  to allow fluids to come in. Even without a check valve  42 , pressure can still be built up after recharging chamber  32  through passage  40  by advancing passage  40  beyond seal  34 . This will create a vacuum upon re-charging until the port re-enters the chamber if the other end of the tube is plugged. The preferred alternative is the check valve  42 . 
     Alternatively, with the addition of the check valve  42  any subsequent setting down of the sub  28  will close the check valve  42  and allow chamber  32  to be pressurized. Those skilled in the art will also appreciate that while a shear pin  38  is shown as holding the relative positions of subs  28  and  46 , other ways of holding them together can be used that also accommodate subsequent relative movement. Clearly after the shear pin  38  is broken the sub  28  can be raised and lowered from the surface any number of times. Alternatively, a j-slot mechanism of a type known in the art can be supplied to allow relative movement between sub  28  and sub  46  in a defined range any number of times. Finally, it is worth mentioning that the embodiment of  FIG. 2  because it has seals  34  and  36  is isolated from wellbore hydrostatic pressure increase as the assembly is introduced into the wellbore. The embodiments in  FIGS. 3 and 4  use a floating piston to balance out wellbore hydrostatic that is an issue in those embodiments due to the different sealing arrangements from  FIG. 2 , as will be explained below. 
     In  FIG. 3 , a top sub  50  that is supported by a tubing string that is not shown, is inserted into a bottom sub  52  defining chambers  54  and  56  that are divided by floating piston  58 . Floating piston  58  has outer seal  60  and inner seal  62 . Chamber  54  is not sealed and is exposed to wellbore hydrostatic pressure. Chamber  56  has an outlet  64  that goes to a tool to be operated or for flushing purposes as described above or for any other downhole use of pressurized fluid. Seal  66  isolates chamber  56  from bore  68  in the subs  50  and  52 . Those skilled in the art will appreciate that movement of floating piston  58  allows the increasing hydrostatic pressure to be transferred to chamber  56  to avoid any pressure imbalances from forming inside the tool prior to operation. A shear pin  70  prevents relative movement between subs  50  and  52  until enough set down weight is applied to sub  50 . Movement of sub  50  with respect to sub  52  builds pressure in chambers  54  and  56  although some leakage occurs out of chamber  54  into the annulus  72  as sub  50  is moved down. Pressure builds up in chamber  56  and is delivered though outlet  64  to perform the downhole operation with the various options again available as earlier described with regard to  FIG. 2 . 
       FIG. 4  is similar to  FIG. 3  except that in  FIG. 4  there is a second floating piston  74  and chamber  54  is isolated from annulus  72  while a new chamber  76  is provided that is not sealed from annulus  72 . Setting down sub  50  pressurizes all three chambers  76 ,  54  and  56 . Discrete fluid paths are made available as between chambers  54  and  56  through separate outlets  64  and  77 . Outlet  64  can be used to lock a wet connect together while outlet  77  can be used for a fluid flush of the ends of the fiber optic cable before they are pushed together, for example. It may be desirable to sequence the action of pressure buildup on the end user tools or devices affected by them. For example, in making up a downhole wet connect it is desirable to flush the fiber optic cable ends before the connection is fully pushed together. 
     A way to address these conflicting needs is to put a rupture disc  78  in outlet  77 . That way if outlet  64  is used to flush the ends of the fiber optic cables it can be activated first before the wet connect is fully made up. Then when that process completes and more pressure is developed with further movement of sub  50 , at some point, calculated to be when the wet connect halves are abutting and are ready to be locked together, the rupture disc  78  will fail to allow the built up pressure to be communicated through passage  77  to set the anchor that locks the wet connect together. It is worth noting that if a rupture disk is placed in outlet  64  there will be a trapped fluid volume between the disk and piston in the anchor. A better way to do this is to have a low-pressure disk in outlet  77  which shears at a relatively low pressure when compared to the pressure required to shear the commit piston in the anchor. This way there is no trapped fluid volume which cannot be hydrostatically balanced. 
     Yet another way to do this is to allow the relative motion between subs  50  and  52  to open a port communicating with outlet  77  first to allow the connection to be washed before it is fully mated up with additional movement then closing access to port  77  so that available pressure can act through port  64  to which access only opens up after access to port  77  is closed or nearly closed to avoid fluid lock in chambers  54  and  56 . 
       FIG. 5  is a variation on  FIG. 4  adding an undercut  80  at piston  74  so that seal  82  can initially be bypassed. Chamber  54  can be filled with a viscous material such as optical index matching gel to keep it in place as the assembly is run into the hole. When the shear screw  70  is sheared the contents of chamber  54  will be pushed out passage  77  for, for example, cleaning the connection before it is fully made up so that the fiber optic cables can effectively transmit signals. Eventually, piston  74  will contact piston  58  after which the contents of chamber  56  will be pushed out through connection  64 . Since an actuating piston for the anchor or lock for the wet connect (not shown) is also shear pinned, the pressure has to build in chamber  56  with piston  80  against piston  58  and set down weight applied to sub  50  before the shear pin in the anchor or lock can break to actuate that tool. Again, the concept being illustrated is sequential operation of two downhole operations the details of which can vary broadly. The invention encompasses this staged actuation as well as simultaneous actuation of different or even an identical downhole device. 
     Those skilled in the art will appreciate that the present invention allows the elimination of a control line from the surface and replaces its operation with a pressure generation system that is localized and preferably initiated with string manipulation. Designs are presented that allow for single operation for a specific task or the ability to cycle as many times as needed to accomplish the same or different tasks. The reservoirs can be isolated from wellbore hydrostatic or compensated to neutralize its effects. A single or multiple reservoirs can be actuated either at once or in sequential order to meet the well conditions and the desired order of operations downhole. The chambers can be pre-filled for a single time fluid displacement or they can have the capability of being recharged using a passage that passes a seal or a passage with a check valve. Recharge fluid can come from the tubing, the annulus or a storage chamber for fluid provided in the string. Splines or other rotational locking features can be provided to allow for torque transmission through the subs independent of their ability to move longitudinally relative to each other to create the desired pressure to use downhole. 
     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.