Pressure responsive downhole tool having a selectively activatable pressure relief valve and related methods

A pressure responsive downhole tool comprises a power piston pressure relief valve that is selectively activated and deactivated to allow pressure-related operations to be conducted. The pressure relief valve will not open until the power piston is activated, which also requires the operating element (ball valve, for example) to be opened, thereby avoided situations in which the ball valve is inadvertently placed in the Lock Open position.

The present application is a U.S. National Stage patent application of International Patent Application No. PCT/US2012/071816, filed on Dec. 27, 2012, the benefit of which is claimed and the disclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to pressure responsive tools and, more specifically, to a pressure responsive downhole tool (e.g., drill stem tester valve) having an operating element (ball valve, for example) that is only open when a power piston pressure relief valve is activated.

BACKGROUND

Conventional tester valves, such as the Select Tester® Valve commercially offered by Halliburton Energy Services, Co., utilize a pressure relief valve in the power piston to control whether the annulus pressure application is considered to be a normal opening pressure or a Lock Open operating pressure. For example, in conditions of 12,000 psi hydrostatic pressure and 300° F., the normal operating pressure is approximately 1400 psi and the Lock Open pressure is roughly 1300 psi higher at 2700 psi.

Such designs can be problematic. For example, the pressure relief valve in the power piston is normally in the range of about 1250 psi. Thus, if the ball valve has high friction due to wear or high pressure differential, the pressure required to open the ball valve and unlatch the collets at the same time, could exceed the 1250 pressure relief in the piston. Therefore, instead of the ball valve opening, the tester valve will index forward into the Lock Open position. Ultimately, when the annulus pressure is bled off, the ball valve will still be closed; but, the selector will be in the Lock Open position. If this is the case, the operator will think the valve is normally closed when, actually, it never opened but, instead, has indexed to the Lock Open position.

Moreover, if the friction on the ball mechanism is between the 1250 psi pressure relief pressure and the applied operating pressure, the ball can be opened after the tool has indexed forward. When the annulus pressure is released, the tool will again be unexpectedly in the Locked Open position. Therefore, without ever going above the normal operating pressure, it is possible to put the tool in the Locked Open position. If the tester valve is being utilized to perform a downhole closure, it will not close. If an emergency happens and the tester valve is expected to close in the well downhole, again, it will not. It will require a pressure cycle to the high Lock Open value to return the tool to normal functioning. Such an operation may take 30 minutes minimum to perform.

Accordingly, in view of the foregoing, there is a need in the art for a tester valve having a pressure relief valve that is only active when the ball valve is in the open position. Therefore, if high pressure is required to get the ball open, the ball must open before the pressure relief valve can open and place the tool in the Lock open position. Such a tool would avoid inadvertent Lock Open positions whereby the operator believes that bleeding off the annulus pressure will close the ball, when in fact the tool is in the Locked Open position.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments and related methodologies of the present invention are described below as they might be employed in a pressure responsive downhole tool having a selectively activatable power piston pressure relief valve. In the interest of clarity, not all features of an actual implementation or methodology are described in this specification. Also, the “exemplary” embodiments described herein refer to examples of the present invention. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments and related methodologies of the invention will become apparent from consideration of the following description and drawings.

As described herein, exemplary embodiments of the present invention are directed to a pressure responsive downhole tool having a power piston pressure relief valve that may be selectively deactivated and activated to allow operations to be conducted using the tool. The pressure responsive downhole tool may be a variety of tools, such as, for example, a tester valve as described in U.S. Pat. No. 5,558,162, entitled “MECHANICAL LOCKOUT FOR PRESSURE RESPONSIVE DOWNHOLE TOOL,” also owned by the Assignee of the present invention, Halliburton Energy Services, Co. of Houston, Tex., the disclosure of which is hereby incorporated by reference in its entirety. As such, the inventive features described herein will be discussed in relation to a drill stem tester valve. However, those ordinarily skilled in the art having the benefit of this disclosure realize the present invention may be applied to any variety of pressure responsive tools.

As further described herein, exemplary embodiments of the pressure responsive tool include a power piston pressure relief valve having a vent port that vents between two annular seals positioned around the outer diameter of the power piston. In embodiments utilized within a drill stem tester valve, during downhole deployment of the tool, the ball valve assembly is in the closed position and the two seals of the power piston seal against the tool housing, thus maintaining the pressure relief valve in a deactivated position. As the ball valve is opened, annular pressure is applied to the power piston which moves the lower annular seal into a slot along the inner diameter of the tool housing, thus allowing pressure to vent around the seal to activate the pressure relief valve. Activation of the pressure relief valve can only happen if the ball valve is open. Thereafter, drill stem testing may be conducted as understood in the art. When it is desired to deactivate the pressure relief valve, the annular pressure is bled off and the power piston moves back to the deactivated position, which also actuates the ball valve back to the closed position. Accordingly, the pressure relief valve is only open when the ball valve is in the open position, thus avoiding any inadvertent Locked Open positions.

Referring now toFIGS. 1A-1I, an annular pressure responsive tool10will now be described in accordance to one or more exemplary embodiments of the present invention. As previously described, annular pressure responsive tool10may be, for example, a drill stem tester valve. For example, annular pressure responsive tool10may be used with a formation testing string during the testing of an oil well to determine production capabilities of a subsurface formation. The testing string will be lowered into a well such that a well annulus is defined between the test string and the well bore hole. A packer associated with the annular pressure responsive tool10will be set in the well bore to seal the well annulus below the power port214of valve10, as hereinafter described in detail, which is then subsequently operated by varying the pressure in the well annulus.

Referring now toFIGS. 1A-1Iof the present invention, the annular pressure responsive tool10includes a housing12having a central flow passage14disposed longitudinally therethrough. Housing12includes an upper adapter16, a valve housing section18, a ported nipple20, power housing section22, connector section24, an upper gas chamber housing section26, a gas filler nipple28, a lower gas chamber housing section30, a metering cartridge housing32, a lower oil chamber housing section34and a lower adapter36. The components just listed are connected together in the order listed from top to bottom with various conventional threaded and sealed connections. The housing12also includes an upper inner tubular member38, an inner connector40, and a lower inner tubular member42. Upper inner tubular member38is threadedly connected to gas filler nipple28at thread44and sealingly received within bore46to be affixed to inner connector40below. Lower gas chamber housing30is attached to inner connector40at thread47. O-ring seals49seal the connections, as understood in the art. Lower inner tubular member42is threadedly connected to inner connector40at thread48. Lower inner tubular member42is sealingly received within a bore50of lower adapter36with an O-ring seal52being provided therebetween.

An upper seat holder54is threadedly connected to upper adapter16at thread56. Upper seat holder54has a plurality of radially outward extending splines58which mesh with a plurality of radially inward extending splines60of valve housing section18. Upper seat holder54includes an annular upward facing shoulder62which engages lower ends64of splines60of valve housing section18to thereby hold valve housing section18in place with the lower end of upper adapter16received in the upper end of valve housing section18with a seal66being provided therebetween. An annular upper valve seat68is received in upper seat holder54, and a spherical ball valve (i.e., operating element)70engages upper seat68. Ball valve70has a bore72disposed therethrough. InFIG. 1, ball valve70is shown in its open position so that the bore72of ball valve70is aligned with the longitudinal flow passage14, or bore, of annular pressure responsive tool10. As will be further described below, when ball valve70is rotated to its closed position, the bore72is isolated from the central flow passage14of annular pressure responsive tool10.

In this exemplary embodiment, ball valve70is held between upper seat68and a lower annular seat74. Lower annular seat74is received in a lower seat holder mandrel76. The lower seat holder mandrel76is a cylindrical cage-like structure having an upper end portion78threadedly connected to upper seat holder54at thread80to hold the two together with the ball valve70and seats68,74clamped therebetween. A spring82(Belleville spring, for example) is located below lower seat74to provide the necessary resilient clamping of the ball valve70between seats68and74.

Cylindrical cage-like lower seat holder76has two longitudinal slots, one of which is visible inFIG. 1Band designated by the numeral84. Within each of the slots, such as84, there is received an actuating arm such as the one visible inFIG. 1Band designated as86. Actuating arm86has an actuating lug88disposed thereon which engages an eccentric bore90disposed through the side of ball valve70so that the ball valve70may be rotated to a closed position upon upward movement of actuating arm86relative to the housing12, as seen inFIG. 1B. Although not shown, there are two such actuating arms86with lugs88engaging two such eccentric bores such as90. Further details regarding the operation of ball valve70will be understood by those ordinarily skilled in the art having the benefit of this disclosure.

An operating mandrel assembly92includes an upper operating mandrel portion94, and intermediate operating mandrel portion96, and a lower operating mandrel portion98. As shown inFIG. 1B, upper operating mandrel portion94includes a radially outer annular groove100disposed therein which engages a radially inwardly extending shoulder102of actuating arm86so that actuating arm86reciprocates with the upper operating mandrel portion94within the housing12to move ball valve70between the open and closed positions. Lower seat holder mandrel76has an outer surface104closely received within an inner cylindrical bore106of the upper operating mandrel portion94with a seal being provided therebetween by annular seal108. An upper portion of intermediate operating mandrel portion96is received within a smaller bore110of upper operating mandrel portion94. Upper operating mandrel portion94carries a plurality of locking dogs112each disposed through a radial window114in upper operating mandrel portion94with a plurality of annular biasing springs116received about the radially outer sides of locking dogs112to urge them radially inward through the windows114against the intermediate operating mandrel portion96.

Operating mandrel assembly92is seen inFIGS. 1A-1F, where annular pressure responsive tool10is in an initial run-in open position wherein the ball valve70is open as shown. However, as will also be described herein, annular pressure responsive tool10may also be initially run into the well with the ball valve70in a closed position. When in the initial run in closed position, intermediate operating mandrel portion96carries an annular radial outer groove118, which inFIG. 1Bis shown displaced above locking dogs112. Intermediate operating mandrel portion96slides freely relative to upper operating mandrel portion94until locking dogs112are received within annular groove118. Thus, referring toFIG. 1B, annular pressure responsive tool10could be initially assembled with upper operating mandrel portion94displaced upwardly relative to housing12and intermediate operating mandrel portion96from the position shown inFIG. 1Bsuch that locking dogs112are received and locked in place in groove118with ball valve70rotated to a closed position.

Intermediate operating mandrel portion96is closely slidably received within a bore119of ported nipple20with an O-ring seal120being provided therebetween. Intermediate operating mandrel portion96includes a radially outwardly extending flange122. An annular mud chamber130is defined between ported nipple20and intermediate operating mandrel portion96. One or more power ports132are radially disposed through ported nipple20to communicate a well annulus surrounding annular pressure responsive tool10with mud chamber130. An annular oil power chamber134is defined between power housing section22and intermediate operating mandrel portion96. An actuating piston136is slidably received within annular oil power chamber134with an outer seal138sealing against power housing section22and an inner seal140sealing against intermediate operating mandrel portion96. Actuating piston136includes an upper side133and lower side135.

Actuating piston136serves to isolate well fluid (e.g., mud) entering power port132from hydraulic fluid (e.g., oil) contained in oil power chamber134. Actuating piston136is connected at lower threads124to load transfer sleeve126which presents four inwardly protruding load transfer shoulders proximate its lower end. One of these shoulders is shown at128inFIG. 1C, which also includes upwardly facing contact surfaces128a. A bearing race (not shown) of slightly enlarged diameter is disposed about the inner circumference of the load transfer sleeve126. A bearing insertion aperture (also not shown) is disposed through the load transfer sleeve126proximate the bearing race. Split ring139and shoulder147fixedly surround the intermediate operating mandrel portion96and limit upward axial movement of the ratchet sleeve127with respect to the intermediate operating mandrel portion96. A snap ring149fixedly surrounds the intermediate operating mandrel portion96proximate the lower end of the ratchet sleeve127to limit downward axial movement of the ratchet sleeve127.

Referring now toFIGS. 1C and 3, ratchet sleeve127surrounds the intermediate operating mandrel portion96and is loosely received within load transfer sleeve126. Ratchet sleeve127is axially rotatable upon the intermediate mandrel portion96. The outer surface of an exemplary ratchet sleeve127is shown inFIG. 3. A milled out area129is located proximate the lower end and upon the outer circumference of ratchet sleeve127. Milled out area129is a section of sufficiently reduced thickness on ratchet sleeve127to permit load transfer shoulders128of the load transfer sleeve126to be moved freely adjacent thereto. Load bearing shoulders131which present downwardly facing contact surfaces131are provided proximate the lower end of ratchet sleeve127. In certain exemplary embodiments, there are four outward load bearing shoulders131adisposed about the outer circumference of ratchet sleeve127positioned so as to be in complimentary engagement with load transfer shoulders128of load transfer sleeve126. Bearing slot grooving133is provided on the outer circumference of the ratchet sleeve127which is shaped and sized to receive a bearing. Bearing slot grooving133includes a first bearing stop position133a, a second bearing stop position133b, third bearing stop position133cand fourth bearing stop position133d, as shown in the dotted lines inFIG. 3.

Bearing installation grooving135is provided which is deeper than the bearing slot grooving133. In certain exemplary embodiments, there may be two arrangements of bearing slot grooving133located on opposing sides of the ratchet sleeve127. Similarly, there would be two such milled out areas129with protruding load bearing shoulders131. While load transfer shoulders128are engaged with load bearing shoulders131of ratchet sleeve127, upward axial load may be transmitted to the ratchet sleeve127, shoulder147and intermediate operating mandrel portion96such that the ball valve70may be closed by an upward pressure differential upon the lower side135of actuating piston136. Upward loading on the actuating piston136causes the load transfer sleeve126to transfer its upward load through the engagement of load transfer shoulders128and load bearing shoulders131to ratchet sleeve127, shoulder147and, thereby, to operating mandrel assembly92.

Still referring toFIGS. 1C and 3, ratchet sleeve127and load transfer sleeve126are operatively associated as a ratchet assembly by insertion of a bearing137into the insertion aperture when the insertion aperture is aligned with the installation grooving135of the ratchet sleeve127. By manipulating ratchet sleeve127, bearing137is then captured and moved within the bearing race and the bearing slot grooving133. In operation, the arrangement functions as a selectively actuatable load transfer assembly which provides for translation of axial motion by the load transfer sleeve126as movement of bearing137along bearing slot grooving133rotates ratchet sleeve127with respect to the load transfer sleeve126, and selectively brings load transfer shoulders128of load transfer sleeve126into engagement with load bearing shoulders131of ratchet sleeve127. Operation of such a ratchet assembly to selectively actuate actuating arm86and ball valve70between various open positions will be readily understood by those ordinarily skilled in the art having the benefit of this disclosure.

Referring now toFIG. 1D, an exemplary embodiment of an annular power piston142will now be described. Note that annular power piston142is illustrated in the activated position, whereby ball valve70is also in the open position. However, as will be described below, in one exemplary methodology, annular pressure responsive tool10is run downhole having ball valve70in the closed position and annular power piston142is the deactivated position. Nevertheless, as shown inFIG. 1D, annular power piston142is fixedly attached to the operating mandrel assembly92and is held in place between by a sleeve144mounted between upper side141of power piston142and the lower end of shoulder128. Intermediate operating mandrel portion96and lower operating mandrel portion98are threadedly connected at thread148after the power piston142has been placed about the intermediate operating mandrel portion96below the sleeve144.

In addition, power piston142has a shoulder145which engages sleeve144positioned around intermediate operating mandrel portion96. Power piston142has an upper side141and a lower side143. Power piston142also carries an outer annular seal150which provides a sliding seal against the wall of an inner cylindrical bore152(i.e., power housing section22) and an inner annular seal154which seals against the intermediate operating mandrel portion96.

Power piston142includes a pressure relief valve250and check valve252, both of which combine to form a fluid transfer assembly that permits fluid transfer across power piston142. Pressure relief valve250provides sufficient resistance so that it will not open to relieve pressure until the annulus has been overpressured to a second level which is above the first pressure level needed to move power piston142and ball valve70between the closed and open positions. Pressure relief valve250is thereby set such that it will not open during normal operation of annular pressure responsive tool10. Thus, if annular pressure responsive tool10is normally operated by increasing well annular pressure to, for example, 1,000 psi above hydrostatic well annulus pressure, pressure relief valve250is designed to require greater than 1,000 psi to open.

However, in exemplary embodiments of the present invention, pressure relief valve250must first be activated in order to relieve the pressure once the rated pressure level has been exceeded. As described herein, pressure relief valve is “deactivated” when, despite the rated pressure being exceeded, pressure relief valve does not function to allow relief of pressure therethrough. As a corollary, “activated” describes the state of pressure relief valve250whereby it is allowed to relieve the pressure once the rated level has been exceeded.

To further illustrate this feature of the present invention,FIG. 1Dshows power piston142and pressure relief valve250in the activated position, whileFIG. 2illustrates the deactivated position. As previously mentioned, in certain exemplary methodologies, annular pressure responsive tool10is run downhole with power piston142in the deactivated position and ball valve70in the closed position, as shown inFIG. 2. To achieve this objective, pressure relief valve250includes a vent port260that vents along the outer diameter of power piston142. In this example, vent port260is a one-way vent port that only allows fluid flow down out of pressure relief valve250. An annular fluid flow groove262extends around power piston142and communicates with vent port260to allow pressure communication accordingly. Vent port260is positioned between outer annular seal150(O-ring seal, for example) and another outer annular seal264.

A plurality of slots266are positioned along the inner diameter of power housing section22, which are adapted to receive seal264. However, in the alternative, slots266may instead be one continuous slot extending around power housing section22. As will be described herein, when power piston142is in the deactivated position (FIG. 2), outer annular seal264is energized to effectively seal between power piston142and power housing section22. However, when power piston142is in the activated position (i.e., pressure relief valve250is activated) (FIG. 1), outer annular seal264no longer seals because it has been received along slots266wherein vent port260is then allowed to communicate pressure around outer annular seal264.

In addition to activating power piston142, downward movement of power piston142relative to housing12due to annular pressure also results in movement of operating mandrel assembly92, thus moving ball valve70to its open position. A rapid increase in well annulus pressure will be immediately transmitted to the upper side141of power piston142, but will be delayed in being communicated with the lower side143of power piston142, so that a rapid increase in well annulus pressure will create a downward pressure differential across power piston142thus urging it downward within the housing12. Accordingly, in this exemplary embodiment, pressure relief valve250will not open until power piston142is in the activated position which also requires ball valve70to be in the open position, thus avoid inadvertent Locked Open tool positions.

To further describe this exemplary embodiment of annular pressure responsive tool10, lower operating mandrel portion98carries a radially outward extending flange156having a lower tapered shoulder158and an upper tapered shoulder160defined thereon. A spring collet retaining mechanism162has a lower end fixedly attached to connector section24at thread164. A plurality of upward extending collet fingers166are radially inwardly biased. Each finger166carries an upper collet head168which has the upper and lower tapered retaining shoulders170and172, respectively, defined thereon.

In the initial position of lower operating mandrel portion98as seen inFIG. 1D, collet head168is located immediately below flange156with the upper tapered retaining shoulder170of collet head168engaging the lower tapered shoulder158of the flange156of lower operating mandrel portion98. This engagement prevents operating mandrel assembly92from moving downward relative to housing12until a sufficient downward force is applied thereto to cause the collet fingers166to be cammed radially outward and pass up over flange156thus allowing operating mandrel assembly92to move downward relative to housing12. Similarly, subsequent engagement of upper tapered shoulder160of flange156with lower tapered retaining shoulder172of collet head168will prevent the operating mandrel assembly92from moving back to its upward most position relative to housing12until a sufficient pressure differential is applied thereacross. In certain embodiments of the present invention, spring collet162is designed so that a differential pressure in the range of from 500 to 700 psi, for example, is required to move the operating mandrel assembly92past the spring collet162. Thus, spring collet162prevents premature movement of operating mandrel assembly92in response to unexpected annulus pressure changes.

Referring toFIG. 1D, an irregularly shaped annular oil balancing chamber174is defined between power housing section22and lower operating mandrel portion98below power piston142. Oil balancing chamber174is filled with a hydraulic fluid such as oil. As shown inFIG. 1E, an upper annular nitrogen chamber176is defined between upper gas chamber housing section26and lower operating mandrel portion98. An annular upper floating piston or isolation piston178is slidably received within nitrogen chamber176, as understood in the art. A plurality of longitudinal passages180are disposed through an upper portion of upper gas chamber housing section26to communicate oil balancing chamber174with the upper end of nitrogen chamber176. Floating piston178isolates hydraulic fluid thereabove from a compressed gas such as nitrogen located therebelow in the upper nitrogen chamber176.

An annular lower nitrogen chamber182is defined between lower gas chamber housing section30and upper inner tubular member38. A plurality of longitudinally extending passages184are disposed through gas filler nipple28and communicate upper nitrogen chamber176with lower nitrogen chamber182. A transversely oriented gas fill port186intersects passage184so that the upper and lower nitrogen chambers176and182can be filled with pressurized nitrogen gas in a known manner. A gas filler valve (not shown) is disposed in gas fill port186to control the flow of gas into the nitrogen chambers and to seal the same in place therein. The nitrogen chambers176and182serve as accumulators which store increases in annulus pressure that enter annular pressure responsive tool10through power ports132above and through equalizing port214. The nitrogen accumulators also function to balance the pressure increases against each other and, upon subsequent reduction of annulus pressure, to release the stored pressure to cause a reverse pressure differential within annulus pressure responsive tool10.

A lower floating piston or isolation piston188is slidingly disposed in the lower end of lower nitrogen chamber182. It carries an outer annular seal190which seals against an inner bore192of lower gas chamber housing section30. Piston188carries an annular inner seal193which seals against an outer cylindrical surface195of upper inner tubular member38. Lower isolation piston188isolates nitrogen gas in the lower nitrogen chamber182thereabove from a hydraulic fluid such as oil contained in the lower most portion of chamber182below the piston188.

Referring now toFIG. 1H, an annular multi-range metering cartridge194is located longitudinally between inner tubular member connector40and the metering cartridge housing32, and is located radially between the metering cartridge housing32and the lower inner tubular member42. Multi-range metering cartridge194is fixed in place by the surrounding components just identified and is adjustable to meter fluid over a wide range of differential pressures. Metering cartridge194carries outer annular seal196which seals against the inner bore of metering cartridge housing32. Multi-range metering cartridge194carries an annular inner seals198which seal against a cylindrical outer surface200of lower inner tubular member42. An upper end of multi-range metering cartridge194is communicated with the lower nitrogen chamber182by a plurality of longitudinal passageways (not shown) cut in the radially outer portion of inner tubular member connector40. Operation of multi-metering cartridge194will not be described herein, as those ordinarily skilled in the art having the benefit of this disclosure will readily understand its function and operation.

Referring now toFIG. 1I, multi-range metering cartridge194communicates with a lower oil filled equalizing chamber210via annular passage208. A lowermost floating piston or isolation piston212is slidably disposed in equalizing chamber210and isolates oil thereabove from well fluids such as mud which enters therebelow through an equalizing port214defined through the wall of lower oil chamber housing section34.

Referring toFIGS. 1A-1I, housing12can be generally described as having a first pressure conducting passage236defined therein for communicating the well annulus with the upper side141of power piston142. In certain exemplary embodiments, the first pressure conducting passage236includes, for example, power port132, annular mud chamber130, and oil power chamber134. Housing12can also be generally described as having a second pressure conducting passage238defined therein for communicating the well annulus with the lower side135of actuating piston136. The second pressure conducting passage238includes oil power chamber134, oil balancing chamber174, longitudinal passage180, upper nitrogen chamber176, longitudinal passage184, lower nitrogen chamber182, longitudinal passages202, the flow path204of multi-range metering cartridge194, annular passage208, equalizing chamber210and equalizing port214. Also, as previously described, once in the activated position, pressure relief valve250is designed to relieve pressure from the first flow passage236to the second flow passage238when the pressure differential therebetween exceeds the pressure rating of pressure relief valve250.

As understood in the art, multi-range metering cartridge194and the various passages and components contained therein can generally be described as a retarding mechanism disposed in the second pressure conducting passage238for delaying communication of a sufficient portion of a change in well annulus pressure to the lower side135of actuating piston136for a sufficient amount of time to allow a pressure differential on the lower side135of actuating piston136to move the actuating piston136upwardly relative to housing12. Retarding mechanism also functions to maintain a sufficient portion of a change in well annulus pressure within the second pressure conducting passage and permit the differential in pressures between the first and second pressure conducting passages to balance.

Moreover, ball valve70can generally be referred to as an operating element operably associated with power piston142and actuating piston136for movement with power piston142between a first closed position and a second open position. However, in other exemplary embodiments, the first position may be open, while the second position may be closed. Those ordinarily skilled in the art having the benefit of this disclosure will realize that this and a variety of other alterations may be embodied within annular pressure responsive tool10without departing from the spirit and scope of the present invention.

Now that the various exemplary components of annular pressure responsive tool10have been described, an exemplary operation conducted using annular pressure responsive tool10will now be described with reference toFIGS. 1A-1I and 2. As will be understood by those ordinarily skilled in the art having the benefit of this disclosure, ball valve70may be opened and closed by increasing and decreasing the annulus pressure between hydrostatic pressure and the first level above hydrostatic. Assuming that we begin with well annulus pressure at hydrostatic levels and a closed position of ball valve70, annular pressure responsive tool10is assembled for deployment into the wellbore such that load transfer shoulders128are aligned with load bearing shoulders131. For exemplary purposes only, the first level of pressure above hydrostatic pressure may be 1000 psi above hydrostatic, a sufficient change in annulus pressure from hydrostatic to move ball valve70between its open and closed positions. Also by way of example, the second level of pressure above hydrostatic pressure is stated to be 2000 psi above hydrostatic. Pressure relief valve250, for example, may be designed to be operable at a differential pressure somewhere between those first and second levels, for example, at a pressure differential in the range of 1200 to 1400 psi. When this differential pressure is applied across relief valve250(after it is activated), it will open allowing hydraulic fluid to be metered slowly through the fluid restrictor from the oil power chamber134to the oil balancing chamber174, as understood in the art.

Nevertheless, to describe an exemplary operation in more detail, annular pressure responsive tool10is made up, deployed downhole and set at a desired location. During its deployment, ball valve70and power piston142are in a first closed position whereby ball valve70is closed and power piston142is in a deactivated position as shown inFIG. 2. After annular pressure responsive tool10has been set at the desired location, a pressure increase will be imposed upon the well annulus so that the pressure exterior of the housing12is brought to the first level above hydrostatic. Fluid pressure will be transmitted into mud chamber130through power port132and along the first pressure conducting passage236to exert pressure upon actuating piston136to move actuating piston136downwardly. The fluid pressure is transmitted through the fluid within the oil power chamber134to the power piston142below. At this time, pressure relief valve250is in the deactivated positioned because vent port260is sealed by seal150above and seal264below.

As the first level of pressure is applied to the power piston142, it and operating mandrel assembly92are moved downwardly to a second position, whereby seal264is de-energized, or unseals, as it moves into slot266thus activating pressure relief valve250. As a result, ball valve70is also actuated into an open position. Here, fluid pressure may be communicated through pressure relief valve250and vent port260. Once the fluid exits vent port260it may flow around flow groove262until it encounters slots266whereby the fluid may then communicate on to oil balancing chamber174.

Once pressure relief valve250is in the activated position as shown inFIG. 1D, power piston142and pressure relief valve250operate as understood in the art, whereby ball valve70may be selectively actuated to one or more open positions (Open, Locked Open, etc., for example) in response to changes in the well annulus pressure. For example, the pressure increase within the first pressure conducting passage236, following downward movement of the power piston142, is then stored with the nitrogen chambers176and182via compression of nitrogen gas contained within. An offsetting amount of fluid pressure is then transmitted upward along the second pressure conducting passage238through equalization port214at the same time that it is transmitted downward along the first pressure conducting passage236through power port132. Ball valve70will still open, however, since the retarding mechanism of the multi-range metering cartridge194will delay the increase in well annulus pressure from being communicated from longitudinal passages208below to longitudinal passages202above. As a result of the delay, the pressure within the first pressure conducting passage236will be greater than that within the second pressure conducting passage238during the delay and permits the ball valve70to open. Eventually, the pressure differential between the first and second pressure conducting passages236,238will become relatively balanced after a period of time.

When it is desired to close ball valve70, annulus pressure may be reduced to hydrostatic causing a reverse pressure differential within both the first and second pressure conducting passages236and238from the stored pressure within the nitrogen chambers176and182. Metering cartridge194delays transmittal of the pressure differential downward within the second pressure conducting passage238from passages202to passages208, thereby maintaining an increased level of pressure within the upper portions of the second pressure conducting passage238. The pressure differential upward within first pressure conducting passage236urges power piston142and actuating piston136upwardly at lower side135. As power piston142moves upwardly, the lower end of power piston142and seal264are moved up out of slot266, thus reactivating seal264to seal against housing12and deactivating pressure relief valve250. Through the resulting load transfer, sleeve126, ratchet sleeve127and shoulder147, the upward motion is transmitted to the operating mandrel96, and ball valve70is moved back to its closed position.

Moreover, as previously mentioned, while pressure relief valve250and power piston142are in the activated position, annular pressure responsive assembly10may also be placed into a “Locked Open” position, as understood in the art. As such, ball valve70is retained in an open position during subsequent changes of well annulus pressure between hydrostatic and the first level above hydrostatic pressure by imposing upon the well annulus a second level of pressure which is above the first level and then reducing the pressure. Here, the well annulus pressure may be changed between hydrostatic and the first level any number of times through use of the ratchet assembly described herein.

Accordingly, through use of the present invention, the pressure relief valve will not open until the power piston142is in the activated position, which also requires ball valve70to be in the open position. Therefore, inadvertent Locked Open positions which persist in conventional tester valves are avoided. In addition, if the ball valve has a high differential, the operating pressure may be increased without the associated risks. Lastly, tools utilizing the inventive aspects described herein may be utilized by current field personnel, as retraining will not be necessary because the tool will operate as expected in all conditions.

An exemplary embodiment of the present invention provides a pressure responsive downhole tool, comprising a tool housing; a power piston slidably disposed within the tool housing for movement between a first position and a second position, the power piston comprising a first and second seal disposed around an outer diameter of the power piston to provide a seal between the power piston and the tool housing; and a pressure relief valve disposed along the power piston, the pressure relief valve comprising a vent port disposed between the first and second seals; a first pressure conducting passage for communicating a well annulus pressure with the power piston to move the power piston from the first position whereby the vent port is not allowed to vent, to the second position whereby the vent port is allowed to vent; and an operating element operably associated with the tool for movement with the power piston between the first and second positions. In another, the tool housing comprises a slot positioned along an inner diameter of the tool housing to receive the second seal when the power piston is in the second position.

In yet another, the operating element is a ball valve assembly that prevents fluid communication through a bore of the tool in the first position, and allows fluid communication through the bore in the second position. Another further comprises a mechanism to selectively actuate the ball valve assembly to the second position in response to changes in the well annulus pressure. Yet another further comprises a flow groove in fluid communication with the vent port, the flow groove extending around the outer diameter of the power piston. In another, the flow groove is positioned between the vent port and the second seal. Yet another further comprises a second pressure conducting passage for communicating pressure to move the power piston back to the first position.

An exemplary methodology of the present invention provides a method of using a pressure responsive downhole tool, the method comprising setting the tool along a desired location of a well, the tool comprising a power piston slidably disposed within a housing of the tool for movement between a first position and a second position, the power piston comprising a pressure relief valve; and an operating element operably associated with the tool for movement with the power piston between the first and second positions; applying well annulus pressure to the tool to move the power piston from the first position to the second position, thereby activating the pressure relief valve, while also moving the operating element from a closed position to an open position; and selectively actuating the operating element to one or more open positions in response to changes in the well annulus pressure.

In another, selective actuation of the operating element to the one or more open positions is only allowed while the power piston is in the second position. Yet another method further comprises bleeding off the well annulus pressure to allow the power piston to move back to the first position, thereby also moving the operating element back to the closed position. In another, the pressure relief valve is deactivated in the first position.

Another exemplary methodology of the present invention provides a method of using a pressure responsive downhole tool, the method comprising deploying the tool to a desired location within a well; applying well annulus pressure to the tool to move a power piston from a first position to a second position; activating a pressure relief valve of the power piston when the power piston is in the second position; and selectively actuating an operating element of the tool in response to changes in the well annulus pressure. In another, the pressure relief valve is deactivated while the power piston is in the first position. Yet another method further comprises moving the power piston back to the first position. In another, moving the power piston back to the first position further comprises bleeding off the well annulus pressure.

In yet another, activating the pressure relief valve further comprises deactivating an annular seal positioned around the power piston. In another, deactivating the annular seal comprises causing the annular seal to enter a slot along an inner diameter of a tool housing. In yet another, the operating element is in a closed position while the power piston is in the first position, the closed position preventing fluid from passing through a bore of the tool. In another, the operating element is in an open position while the power piston is in the second position, the open position allowing fluid to pass through the bore of the tool. In another, the operating element is a ball valve assembly.

The foregoing disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the apparatus in use or operation in addition to the orientation depicted in the figures. For example, if the apparatus in the figures is turned over, elements described as being “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Although various embodiments and methodologies have been shown and described, the invention is not limited to such embodiments and methodologies and will be understood to include all modifications and variations as would be apparent to one skilled in the art. Therefore, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.