The field of this invention is downhole circulation valves that can be opened and closed with dropped balls and more particularly to valves that can open and close without having to use a larger ball for a second position of the valve.
There are many operations downhole that require circulation or reverse circulation through a tool string. Almost as often the circulation valve needs to be operated between two positions so that, for example, it can be run in open to the desired location and then after the circulation is done, it can be closed again.
There are many types of circulation valves that are in use downhole. Some have an internal ported sleeve that is attached to a housing with a port through a j-slot mechanism. With this type of valve picking up and setting down weight gets the ports aligned or misaligned, as needed. These types of valves are less suitable for deviated wellbores where it is difficult to know if picking up and setting down has actually shifted the circulation valve or merely stretched the tubing string from a location near a wellbore deviation.
Other types of circulation valves involve the use of ever larger balls to move a circulation valve between its end positions. This design allows an initial smaller ball to land on a seat to pressure up to set another tool followed by a further pressure to move the valve to another position. In order to move the valve again to its initial position a bigger ball has to land on a bigger seat to, for example, shift a different sleeve. The initial ball is typically released as its seat shifts into a recess and opens up. Such seats can be made of collet segments that are held together in an initial position to allow pressure buildup on a seated ball and then the collet fingers in a groove can spread apart allowing the ball to go on through.
As an alternative, a different seat has been employed that simply enlarges as the ball is blown though it with pressure. It then stands ready to receive another ball that is larger for another operation.
A circulation valve with disappearing balls has been offered. The idea here is to use a seat that keeps its dimension so that it can accept a constant ball size. The idea is that the ball lands on the seat and permits whatever operation is needed and then just goes away from exposure to well conditions over time. The problem with this design is that the balls are rather soft and are prone to be eroded during delivery or even when on the ball seat itself and before the operation that depends on the ball sealing can be accomplished.
Other issues that have affected ball seats made of a series of collets is that the sealing happens on a series of abutting shoulders and in a downhole environment where debris can settle on the seating surface and reduce the chance for a good seal on the ball.
The present invention seeks to overcome some of these disadvantages. While the invention is presented in the context of a circulation valve it can be deployed in other applications downhole. These and other advantages of the present invention will become more apparent to those skilled in the art from a review of the preferred embodiment described below along with its associated drawings while recognizing that the claims define the full scope of the invention.
A downhole tool can perform a series of operations with balls of the same size where movement caused by pressuring up on the first ball positions the next seat to accept another ball just like it. In a preferred embodiment a circulation sub is run in with a port closed and a first seat comprising of collets pushed together and preferably lined with a sleeve are in position to accept a first ball to perform a downhole operation and thereafter pass the ball and open the port. The act of opening the port gives support, by reducing their dimension, to the next assembly of collets also preferably lined with a sleeve so that they are energized to accept the same size ball. Pressuring up on the second ball can shift another sleeve to close the circulation port. The tool is modular and more than one module can be deployed in a given bottom hole assembly.
Sleeve 24 is initially secured to the housing 40 by a shear pin 42 or by equivalent devices. The presence of pin 42 allows pressure to build on seated ball 10 in the
The motions that a single modular housing 40 can undergo have been illustrated in the context of a circulation valve. A bottom hole assembly can employ multiple modules that work identically as circulation valves but are deployed at different depths. Alternatively, a single module can also comprise sufficient components to open and close a circulation port more than once. In yet another variation the module can accomplish other downhole operations rather than opening or closing a valve. The pressure operation made possible by the device can also simply allow other tools to be operated with a series of objects that do not need to be successively larger as has been the case in the prior art. Indeed, the modular housing 40 does not need to have a port such as 26 if it is not being used as a circulation valve.
There are many unique features of the present invention that should be mentioned. One is that successive objects, preferably spheres, can be used in succession where subsequent objects are no larger than the previously inserted objects. The release of one inserted object sets up the receipt of another no larger object on a different seat. That seat can subsequently release the later inserted object. The multiple seats allow operations of various tools and no significant drift restriction after the inserted objects are passed by the device. Apart from letting other downhole tools be operated in a desired sequence, the shifting or loss of support for the seats can also be deployed to operate a circulation valve or yet other tools whose operation can be wholly independent of the pressurization function on the seated balls.
Yet another optional feature of the present invention is that collet fingers 18 down to heads 14 can be lined with a material that stretches and is compatible with downhole conditions. This material can be in the form of a sleeve 60 that is secured to the inside of the collet fingers to effectively block the spaces between fingers 18 thus acting as a debris barrier. It can be preferably made of rubber but other materials compatible with downhole conditions can be used. It can be a solid sleeve or a coating on the inside surfaces of the collet fingers or any condition in between. The material 60 can go down to the collet heads 14 so that when the ball 10 arrives, it seals against the material as opposed to a line contact on the sphere 10 with the associated collet heads 14. Similarly, the same treatment can be applied using the material 64 on collet fingers 62 and on down to the associated collet heads 36. The function and operation is the same as described above.
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.
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Number | Date | Country | |
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20080093080 A1 | Apr 2008 | US |