Patent Application
20080302527
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.
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.
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.
The mechanism of the present invention as shown in
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
In
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.
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.
