Well tool protection system and method

The system including a well tool having a housing forming a protection fluid chamber in fluid communication with a discharge port, a protection fluid disposed within the protection fluid chamber, and a moveable mechanism in functional connection with the protection fluid chamber in a manner to expel a portion of the protection fluid when the moveable mechanism moves.

BACKGROUND OF INVENTION

The present invention relates in general to well tools and more specifically to a device and method for removing debris from the vicinity of a portion of a well tool and for improved operation of the well tool.

Well tools are operated in harsh downhole conditions often resulting in failure of the well tool to operate as intended. One cause of the failure is due to debris that exists in the well fluid. For example, many well tools include moveable mechanisms such as flapper type valves. These valves are positioned to be readily operated when needed.

However, it is all to common for debris contained in the well fluid to settle around the flapper preventing the flapper from opening or opening completely as desired.

Another problem encountered in existing well tools is failure of a moveable mechanism to operate due to pressure fluctuations in the well bore. These failures tend to occur more often in high downhole pressure environments with large diameter well tools. For example, often one shear pin bears an excessively load resulting in premature shearing of that pin and failure of the well tool to operate properly.

Therefore, it is a desire to provide a system and method for increasing the operational reliability of a well tool. It is a further desire to provide a debris removal system for removing debris from the vicinity of a portion of the well tool to alleviate jamming and tool failure. It is a still further desire to provide a dischargeable protection fluid for removal of debris from proximate a moveable mechanism of a well tool. It is a still further desire to provide an improved release mechanism for operating a well tool.

SUMMARY OF INVENTION

In view of the foregoing and other considerations, the present invention relates to well tools and more specifically to a system and method for removing debris from proximate a well tool.

Accordingly, a well tool protection system and method is provided. The system including a well tool having a housing forming a protection fluid chamber in fluid communication with a discharge port, a protection fluid disposed within the protection fluid chamber, and a moveable mechanism in functional connection with the protection fluid chamber in a manner to expel a portion of the protection fluid when the moveable mechanism moves.

The housing may be a part of the well tool or a member attached to an existing well tool. The housing may include a portion of the tubing or casing.

The discharge port may be positioned in any position wherein it is desired to remove debris from the vicinity of the well tool. For example, in a well tool, such as a flapper type formation or tubing isolation valve, it may be desired to position the discharge port proximate the back of the flapper. It may further be desired to include more than one discharge port. Additionally, it may be desired to design the discharge port to achieve a type of discharge fluid flow.

It may be desired for the moveable mechanism to include an operational feature of the well tool. In an embodiment of the present invention the moveable mechanism includes a slide sleeve that carries the flapper. When the slide sleeve is actuated to move downward the flapper may be moved from the closed to the open position. Utilizing the slide sleeve in functional connection with the protection fluid chamber, the protection fluid is expelled as the flapper is being opened alleviating jamming of the flapper by debris.

It has been further realized that well tools may fail when there is a pressure fluctuation in the well. The moveable mechanism spreads an uneven load across the shearing members resulting in premature shearing of a shearing member preventing movement of the moveable mechanism. Therefore it may be desired to include a first and a second sleeve in a moveable mechanism and additional breakaway or breakable members. Breakable or breakaway members include, but are not limited to, release mechanism such as collets as detents, shearable ratchets, shear pins, springs, c-rings, dogs, tension rods and other mechanisms known in the art. The sleeves may have ports that facilitate equalization of the pressures encountered in the well. In this manner uniform loads are spread across the breakaway members and a consistent and uniform release of the moveable mechanism is achieved.

A well protection system of the present invention may include a flapper, a housing having a protection fluid chamber in fluid communication with a discharge port positioned proximate the flapper, a protection fluid contained within the protection fluid chamber; a first slide sleeve positioned in moveable connection with the flapper wherein the first slide sleeve is held in a static position by a first breakable member; a second slide sleeve positioned in moveable relation to the first slide sleeve; a load support positioned below the second slide sleeve in a manner supporting the second slide sleeve in a set position; a retainer maintaining the load support in a set position, and a second breakable member maintaining the retainer in a set position.

A method of protecting a well tool allowing full and proper operation may include the steps of supporting a force from a pressure differential across a flapper when the flapper is in a closed position, actuating a first slide sleeve to move the flapper to an open position, parting a first breakable member allowing the first slide sleeve to move, equalizing the pressure differential across the flapper; parting a second breakable member releasing a second slide sleeve for movement, urging a second slide sleeve into movement by movement of the first slide sleeve, moving a load support, expelling the protections fluid, and moving the flapper to the open position.

DETAILED DESCRIPTION

As used herein, the terms “up” and “down”; “upper” and “lower”; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements of the embodiments of the invention. Commonly, these terms relate to a reference point as the surface from which drilling operations are initiated as being the top point and the total depth of the well being the lowest point.

FIG. 1is a cross-sectional view of a debris removal system of the present invention designated generally by the numeral10.FIG. 2is a cross-sectional view of debris removal system10ofFIG. 1from a different angle. With reference toFIGS. 1 and 2, debris removal system10includes a well tool12having a housing14carrying a protection fluid16and a moveable mechanism18.

Well tool12is illustrated as a tubing isolation valve having a flapper20. InFIGS. 1 and 2well tool12and flapper20are in the closed position. For purposes of illustration, flapper20ais superimposed to illustrate flapper20in the open position. Moveable mechanism18includes a slide sleeve22that carries flapper20. Flapper20is pivotedly connected to slide sleeve22by a pivot pin24. Housing14forms a protection fluid chamber26for carrying protection fluid16. Protection fluid16may be any suitable fluid for removing debris25from about moveable mechanism18. Examples of protection fluid16include, but are not limited to, high-viscosity fluids, high-density fluids and jelly type lubricants. It may be desired to include a lubricant in the protection fluid for additional benefits.

Slide sleeve22is positioned within protection fluid chamber26. A protection fluid channel28, or channels, is formed by a groove in slide sleeve22. Protection fluid channel28has a discharge port30in fluid communication with chamber26. Discharge port30may be positioned proximate pivot pin24such that protection fluid16will be discharged at the back21of flapper20, as flapper20is being opened, to remove debris25and permit full movement of flapper20to the position shown by flapper20a. It should be recognized that discharge port30may be positioned in various positions for debris removal. System10may include more than one discharge port. Discharge port30may be designed for the type of discharge flow desired.

Operation of debris removal system10of the present invention is now described with reference toFIGS. 1 and 2. With well tool12and flapper20in the closed position an operating sleeve32is activated moving downward and urging slide sleeve22downward. As slide sleeve22is urged downward shear pins34are sheared releasing slide sleeve22carrying flapper20for downward movement. The flow ports36in flow tube38pass seals40allowing fluid communication with the large flow ports42in slide sleeve22. It is often desired to include more than one flow port36and flow port42. At this moment, flapper20is still separated a distance above flow tube38. Slide sleeve22and flapper20continue to move downward as pressure equalizes across flapper20. As slide sleeve22moves downward it displaces protection fluid16under pressure through protection fluid channels28and discharged through discharge port30removing debris25from about flapper20, releasing flapper20to move to the open position. As slide sleeve22moves downward it carries flapper seat56downward. When the tip44of flow tube38reaches flapper20, and the pressure across flapper20equalizes, flow tube38pushes flapper20open.

Since protection fluid channel28is formed on the same side of slide sleeve22as pivot pin24, protection fluid16will only be discharged to the back of flapper20. Protection fluid16will not have significant interaction with the well fluid getting into flow tube38through well fluid channels46.

Debris removal system10shown inFIGS. 1 and 2is adapted for small diameter well tools12in low-pressure conditions. When downhole pressure is high, especially in large well tools12, more and stronger shear pins may be needed to tolerate the load acting of the flapper before opening. Since there may be pressure fluctuations acting on the flapper during well operation, and the multiple shear pins may not take the load uniformly, one of the shear pins might be sheared prematurely causing the tool to malfunction. Therefore a two-step release mechanism may be desired.

FIG. 3is a cross-sectional view of a debris removal system10of the present invention having a two-step release mechanism. Debris removal system10further includes a second slide sleeve23, a second shear pin34b, load support members48, and retainer50.

Before flapper20is opened, there is a pressure differential across flapper20, and the downward load caused by this pressure differential is taken by the load support members48, which may include but are not limited to split rings. Seal40and seal41positioned in the outside diameter of flow tube38form a differential area. This differential area, with differential pressure, resists downward movement of second slide sleeve23until the pressure across flapper20is equalized. This minimizes the stress on flapper pin24and load support members48.

Load support members, split rings48, have a wedge face70and is installed in the groove71in flow tube38.

Groove71in flow tube38also has a wedge face72to match the wedge face on split rings48to balance the load acting on split rings48. Meanwhile, the radial load acting on split rings48from the ring wedge face70is balanced by the inner face74of retainer50. Split rings48can be made by cutting a whole ring with a wedge face into multiple pieces along its axial direction. Once retainer50is moved away from split rings48, split rings48will be free to be moved out of the groove of flow tube38.

When operating well tool12from the closed to the open position, operating sleeve32is actuated to move downward urging moving member18including first slide sleeve22downward. As first slide sleeve22is urged downward the first shear pin34ais sheared releasing first slide sleeve22for downward movement. Movement of first slide sleeve22downward opens the flow ports42in the second slide sleeve23. The pressure across flapper20then equalizes and first slide sleeve22continues to move downward.

Because of the equalized pressure the split rings48and retainers50do not bear a high load. As the lower end52of first slide sleeve22contacts retainer50it breaks second shear pin34b. As the first slide sleeve22continues to move downward its shoulder54urges the second slide sleeve23downward moving split rings48out of the groove71in flow tube38. As slide sleeves22and23move downward protection fluid16is discharged through discharge port30urging debris25from the vicinity of flapper20. As second slide sleeve23moves downward flapper seat56moves downward and tip44of flow tube38moves flapper20to an open position.

FIG. 4is a cross-sectional view of another embodiment of a debris removal system10of the present invention. Debris removal system10includes a well tool installed in a well62. Well tool12includes a housing14that defines a protection fluid chamber26carrying a protection fluid16. A moveable mechanism18of well tool12is functionally connected to fluid chamber26in a manner to force protection fluid16from chamber26through an annular discharge port30when moveable mechanism18is moved. When moveable mechanism18is moved protection fluid is discharged through annular discharge port30removing debris25from the vicinity of well tool12proximate annular discharge port30.

With reference toFIGS. 1–4a method of operating a well tool protection system is provided. A well tool12is positioned in a well bore62. Well tool12may be connected to a conduit60such as tubing or casing. Well tool12includes a housing14defining a protection fluid chamber26and a discharge port30in fluid communication with chamber26. Housing14may include a portion of conduit60. A protection fluid16is maintained in chamber26. Well tool12includes a moveable mechanism18for operation. At least a portion of the moveable mechanism is in functional connection with chamber26in a manner so as when moveable mechanism18moves it expels protection fluid16through discharge port30. Discharge port30is positioned in a location where it is desired to remove debris and/or provide a lubricant. As disclosed it may desired to provide a improved release mechanism for moveable mechanism18such as increased number of shear pins34, an additional side sleeve22to the moveable mechanism18and split-rings48and retainers50.

From the foregoing detailed description of specific embodiments of the invention, it should be apparent that a debris removal system for clearing a moveable mechanism of a well tool and a release mechanism that is novel has been disclosed. Although specific embodiments of the invention have been disclosed herein in some detail, this has been done solely for the purposes of describing various features and aspects of the invention, and is not intended to be limiting with respect to the scope of the invention. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the disclosed embodiments without departing from the spirit and scope of the invention as defined by the appended claims which follow. For example, the invention is described in relation to a flapper type valve such as in a formation isolation valve, tubing isolation valve or safety valve; however, the present invention may be incorporated into any well tools in particular well tools having moveable components.