Apparatus and methods for manual override of hydraulic choke or valve actuators

A hydraulic actuator comprises a chamber, a first line, a second line, and an auxiliary line. The chamber allows fluid to move therethrough and comprises a movable element therein. The first line is in fluid communication with the chamber. The second line is in fluid communication with the chamber. The auxiliary line connects the first line and the second line and comprises a valve to selectively allow fluid communication between the first line and the second line as the movable element is moved in the chamber.

BACKGROUND

Controlling fluid pressure is needed and advantageous in many industries and environments. One such environment relates to controlling pressure in a wellbore during a drilling or another oilfield process.

Wells are drilled on land and in marine environments for a variety of exploratory and extractive purposes. Due to the variety of purposes, the conditions experienced while producing the wells also vary greatly. The particular conditions include changes in temperature, pressure, subterranean fluids, and formations, among other variables. Managed Pressure Drilling (“MPD”) is used to ensure the pressure within the wellbore is maintained within predetermined limits relative to the surrounding formation pressure. The formation pressure may change during drilling of the wellbore. The applied fluid pressure by the drilling system is increased or decreased as necessary to keep the wellbore pressure within the desired limits. Chokes, for example, may be used to maintain the wellbore pressure within the predetermined limits.

DETAILED DESCRIPTION

Examples will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Any element described in relation to any embodiment may be freely combinable with any element described in relation to any other embodiment. Combinations of elements described in relation to different embodiments should be understood to be within the scope of the present disclosure.

The present disclosure relates generally to the movement of fluid. More particularly, the present disclosure related to movement of a hydraulic fluid within or in relation to a hydraulic actuator. A hydraulic actuator may convert fluid movement to a mechanical force or torque to do work on a system. For example, fluid movement may be used to move one or more movable elements in the hydraulic actuator, and the one or more movable elements may, in turn, move a gate to control fluid flow through a fluid choke. In some instances, an operator may desire to manually adjust the hydraulic actuator. The manual adjustment of the hydraulic actuator may be limited or substantially prevented by the presence of the hydraulic fluid within the hydraulic actuator. A hydraulic bypass or reservoir in communication with an inlet and an outlet of the hydraulic actuator may lessen or substantially remove the fluid pressure on the hydraulic actuator, thereby allowing the manual adjustment of the hydraulic actuator.

A hydraulically powered actuator can be used to operate a valve of a drilling choke. The actuator can be of various types—a single-acting cylinder, a double-acting cylinder, a hydraulic motor, or the like. In situations where automated control of the hydraulic actuator encounters a problem, it may be useful to have a hydraulic actuator that includes a manual override feature that disables the automatic control and allows for manual control of the actuator.

Providing a manual override feature in a hydraulic actuator can be complicated because the fluid left in the cylinder or motor can hydraulically lock the mechanism if there is no means for the fluid to flow out of the actuator during manual override operation. Generally, the hydraulic lines of the hydraulic actuator use quick-disconnect fittings that include check valves preventing the lines from leaking fluid when the quick-disconnect fittings are disconnected. Manual override is not possible with the quick-disconnect fittings because the fluid is left in the hydraulic lines and resists the manual override operation. The fittings have to either be disassembled or the lines have to be cut to allow the fluid to move and neither of these options is easy. Typically, the fittings are hard to disassemble and the hydraulic lines are high-pressure armored lines that are designed to be cut resistant. Moreover, suddenly releasing the pressure stored in the hydraulic lines through disassembly or cutting can be dangerous.

Thus, the presence of the fluid in the hydraulic lines of the hydraulic actuator and the difficulty of removing the fluid may present an obstacle to an operator responding to an emergency condition through manual override. Moreover, once the manual override operation is completed, the hydraulic actuator needs to be repaired or reassembled before normal operations can resume such that the downtime of the system can be reduced.

FIG. 1shows a schematic representation of an embodiment of a hydraulic actuator100which is embodied as a hydraulic motor102. The hydraulic motor102may include a set of gears104that are rotated through movement of a fluid106through a chamber108of the hydraulic motor102. The chamber108may have a first port110and a second port112in fluid communication with the chamber108. The fluid106may be directed through the hydraulic motor102from an inlet line114coupled to the first port110through to an outlet line116coupled to the second port112. The inlet line114and the outlet line116may be in operative communication with one or more flow control devices that control the flow of the fluid106through the lines114,116when the hydraulic actuator100is operating in an automatic mode. For example, an electric pump, manual pump, or pump driven by an internal combustion engine may apply a pressure to the inlet line114to move the fluid106through the hydraulic motor102and turn the gears104. In another example, the pressure applied to the inlet line114may be at least partially a static pressure and/or columnar pressure of a fluid body in fluid communication with the inlet line. The gears104may be operatively connected to a fluid choke and configured to move a gate of the fluid choke relative to a seat of the fluid choke.

When the hydraulic actuator100is operated in a manual mode, a manual override system118may allow for an operator to move the fluid106through the hydraulic motor102. The manual override system118may allow fluid106to move through the hydraulic motor102irrespective of the state of the devices that control the flow of the fluid106through the lines114,116when the hydraulic actuator100is operating in an automatic mode. For example, if the aforementioned electric pump in communication with the inlet line114malfunctions, the fluid106in the inlet line114may become static and resist or prevent the movement of the hydraulic motor102. The manual override system118may decouple the fluid106in the hydraulic motor102from the exclusive influence of the electric pump or other source of fluid pressure on the inlet line114and to provide a fluid bypass between the inlet line114and the outlet line116, allowing manual operation of the gears104.

The manual override system118may include an auxiliary line120connecting the inlet line114and the outlet line116. The auxiliary line120may further include a valve122located on the auxiliary line120. In some embodiments, the valve122may be a check valve, for example. The valve122may have an open position and a closed position. During automatic operation of the hydraulic actuator100, the valve122may remain in the closed position limiting or preventing fluid communication between the inlet line114and the outlet line116. When the hydraulic actuator100is operated in the manual mode, the valve122may be in the open position allowing fluid106trapped in the hydraulic motor102to flow out of the hydraulic motor102to the outlet line116, into the auxiliary line120, and back into the inlet line114of the hydraulic actuator100. This movement allows the hydraulic motor102to spin during the manual mode operation. The electric pump or other source of fluid pressure on the inlet line114may continue to apply a fluid pressure to the fluid106within the hydraulic actuator100during manual mode operation. The fluid106may flow through the auxiliary line120between the inlet line114and outlet line116irrespective of the fluid pressure applied by the electric pump or other source of fluid pressure on the inlet line114. The inlet line114and outlet line116may include additional features or valves to channel fluid partly or entirely into the auxiliary line118. As soon as the manual mode operation is completed, the valve122may be moved to the closed position to resume automatic mode operations.

FIG. 2shows a second schematic embodiment of the hydraulic actuator200.

The hydraulic actuator200includes a hydraulic cylinder202which includes a stem or shaft224leading to a piston226. The piston226may divide a chamber208of the cylinder202into a first chamber portion228and a second chamber portion230. The hydraulic actuator200may further include a first line214that is in fluid communication with the first chamber portion228and a second line216that is in fluid communication with the second chamber portion230. The first line214and the second line216may be in operative communication with flow control devices, e.g., pumps, which control the flow of fluid through the lines214,216and, therefore, movement of the movable element, e.g., the piston226, during automatic operation.

During automatic operation, a fluid206can be supplied through the first line214into the first chamber portion228in order to move the piston226in a first direction within the chamber208while the fluid206can also be supplied to the second line216into the second chamber portion230in order to move the piston226in a second, opposite direction within the chamber208. The manual override system218may include an auxiliary line220connecting the first line214and the second line216and may further include a valve222on the auxiliary line220. The inlet and outlet lines214,216may include additional features or valves to channel the fluid206partly or entirely into the auxiliary line220. In some embodiments, the valve222may be a two-way valve.

During manual mode operation, the valve222may be moved to an open position to allow fluid communication between the first line214and the second line216. The presence of the stem224creates a varying rate of change in the volume of the second chamber portion230during movement of the stem224and piston226. For example, for a given displacement of the stem224and piston226, the change in volume of the first chamber portion228may be greater than the change in volume in the second chamber portion230. Therefore, the volume of the fluid206moving into and/or out of the first chamber portion228may be greater than the volume of the fluid206moving into and/or out of the second chamber portion230. If the manual override system218does balance this volumetric difference, a pressure difference between the first chamber portion228and the second chamber portion230may bias the piston226in one direction. If the fluid206is environmentally benign, the extra volume may simply be vented to the atmosphere.

In some embodiments, a stem or shaft of a manual crank may open/expose additional volume in the second chamber portion230, such as by including apertures, recesses, or pockets within a stem or shaft of the manual crank in communication with the second chamber portion230to manually adjust the volume of the second chamber portion230. Adjustment of the volume of the second chamber portion230may allow hydraulic pressure to release flow from one side of the actuator to the other as the manual crank is cranked or turned.

FIG. 3shows a schematic representation of an embodiment of a hydraulic actuator300including a reservoir in fluid communication with an auxiliary line to compensate for and/or balance a volume change of a hydraulic cylinder during manual mode operation of the hydraulic actuator300. The hydraulic actuator300may be similar to the hydraulic actuator200described in relation toFIG. 2. For example, the hydraulic actuator300may include a manual override system318, a hydraulic cylinder302, a first line314, a second line316, a stem324, a piston326, a first chamber portion328, and a second chamber portion330.

The manual override system318may include an auxiliary line320and a valve322. The valve322may be a three-way valve322that may provide fluid communication with a reservoir332via a reservoir line334coupled to the valve322. The valve322may, thereby, provide fluid communication between the auxiliary line320and the reservoir line334. The reservoir332may allow the extra volume of fluid306to move out of the chamber308of the hydraulic cylinder302and still be contained within the entire hydraulic actuator300. In some embodiments, the reservoir332may have a volume greater than the anticipated volume of fluid306displaced during manual mode operation of the hydraulic actuator300. In other embodiments, the reservoir332may initially contain fluid306to accommodate displacement of the stem324and piston326toward (i.e., a reduction of volume of) the second chamber portion330and away from (i.e., an increase of volume of) the first chamber portion328. For example, the reservoir332may initially include a volume of fluid306greater than the anticipated volume of fluid306displaced during manual mode operation of the hydraulic actuator300. The reservoir332may initially include a volume of vacuum or compressible gas336greater than the anticipated volume of fluid306displaced during manual mode operation of the hydraulic actuator300. The reservoir332may be twice the volume of the stem324and may be partially full to either absorb or provide the fluid306displaced during manual mode operation of the hydraulic actuator300. In other embodiments, the reservoir332may be at least partially expandable, collapsible, or otherwise configured to adjust volume to accommodate the displacement of fluid306from the hydraulic chamber302.

In other embodiments, an inlet line, an outlet line and a reservoir may be connected by two two-way valves, as shown inFIG. 4andFIG. 5, or one three-way valve, as shown inFIG. 6. A manual override system418including two two-way valves is shown inFIG. 4. The manual override system418may be connected to a first line414and a second line416of a hydraulic motor or cylinder and may include an auxiliary line420, two-way valves422, and a reservoir432. The first line414and the second line416may be in fluid communication with a chamber of the hydraulic motor or cylinder similar to those described in relation any ofFIG. 1throughFIG. 3. The reservoir432may be located serially along the auxiliary line420between the two two-way valves422. During automatic operation, the two-way valves422may remain in a closed position such that the reservoir432is not in fluid communication with the first line414and the second line416. During manual mode operation, the two-way valves422may be moved to an open position to allow fluid to be directed to the reservoir432. The reservoir432may include sufficient volume within the reservoir or an adjustable volume of the reservoir432to allow fluid to remain in the reservoir432and allow for the varying rate of volume change between the portions of the chamber that is separated by a stem and piston such as that described in relation to FIG.2. As discussed above, the inlet and outlet lines414,416may include additional features or valves to channel fluid partly or entirely into the auxiliary line420. One embodiment of the two-way valve422may be a ball or plug valve or a “quarter turn” valve that can be changed from the closed position to the open position quickly.

FIG. 5shows a different embodiment of the manual override system518in which a two-way valve522is used. The manual override system518includes a reservoir line538. The reservoir line538may provide fluid communication with the reservoir532and the auxiliary line520between the two-way valve522and the second line516. The reservoir line538may include a one-way valve540that allows entry into the reservoir532but prevents exit therefrom. The one-way valve540may be a check valve, for example. As shown inFIG. 5, in other embodiments, the auxiliary line540between the two-way valve522and the first line514may include a reservoir line538providing fluid communication with the reservoir532and the auxiliary line520. In yet other embodiments, the manual override system518may include a first reservoir in fluid communication with the auxiliary line520on a first side of the two-way valve522and a second reservoir in fluid communication with the auxiliary line520on a second side of the two-way valve522.

FIG. 6depicts a schematic representation of a manual override system618. The manual override system618may be connected to a first line614and a second line616of a hydraulic motor or cylinder and may include an auxiliary line620, a three-way valve642, and a reservoir632connected to the three-way valve642by a reservoir line638. The first line614, the second line616, and the reservoir632may be fluid communication with each other when the three-way valve642is in an open position. The first line614, the second line616, and the reservoir632may not be in fluid communication with each other when the three-way valve642is in a closed position. In some embodiments, the seat of the three-way valve642may include three passages in a “T’ orientation. For example, the three-way valve642is configured such that fluid communication between the first line614and the second line616is prevented and such that fluid communication from either the first line614or the second line616to the reservoir632is prevented when the valve20ais closed. The schematic representation of a three-way valve742inFIG. 7includes a threaded configuration so that it can be rotatably opened or closed. When the three-way valve742is in an open position as shown inFIG. 7, fluid communication between a first port744and a second port746and fluid communication from either of the first port744or the second port746to a third port748may be established. In other words, the three-way valve742seals all three ports (i.e., the first port744, the second port746, and the third port748) from each other when the valve is in a closed position and the seat750is in contact with the gate752. In some embodiments, the seat750may have a geometry that corresponds to the geometry of the gate752. When the three-way valve742is in an open position and the gate752is not in contact with the seat750of the three-way valve742, the three ports744,746,748may be connected for fluid communication.

Other embodiments of a three-way valve842,942,1042are shown inFIGS. 8 through 10. The three-way valve842, shown inFIG. 8, may be a needle valve. The three-way valve842may include a first port844, a second port846, and a third port848that each provide fluid communication with an interior volume of the three-way valve842. The first port844, second port846, and third port848may be connectable to fluid conduits to provide selective fluid communication therebetween. For example, the first port844may be connected to a first auxiliary line820a, the second port846may be connected to a second auxiliary line820b, and the third port848may be connected to a reservoir line838. In other examples, the first port844, second port846, and third port848may be connected to the first auxiliary line820a, second auxiliary line820b, and reservoir line838in other configurations. In yet other examples, the first port844, second port846, and third port848may be connected to other fluid conduits, such as additional reservoir lines to provide fluid communication to additional reservoirs of fluid. In yet another example, at least one of the first port844, second port846, and third port848may be sealed to allow the three-way valve842to operate as a two-way valve.

In some embodiments, the first port844and second port846of the three-way valve842may be positioned in the body or seat850of the three-way valve842longitudinally offset from one another. For example, the first port844and second port846may be covered or partially covered by a gate852of the three-way valve842at different positions within the range of motion of the gate852. The three-way valve842may, therefore, have an open position in which the first port844, second port846, and third port848may be in fluid communication with one another; a closed position in which the first port844, second port846, and third port848may not be in fluid communication with one another; and an intermediate position in which two of the three ports are in fluid communication with one another. For example, the three-way valve842may have an intermediate position in which the second port846and the third port848are in fluid communication with one another while the first port844may remain sealed relative to the other ports. In some embodiments, an intermediate position may allow bleeding of one of the hydraulic lines while not allowing for a hydraulic bypass of the hydraulic actuator or may allow for a direct bypass of a first line and a second line in a hydraulic actuator while selectively allowing the use of a reservoir also connected to the three-way valve842.

FIG. 8shows a fluid806entering the three-way valve842through the first auxiliary line820aconnected to the first port844. In some embodiments, the needle valve gate852may be positioned to substantially prevent flow through the three-way valve842. In other embodiments, such as that depicted inFIG. 8, the relative position and/or size of the gate852and the seat850may allow some flow around or past the gate852, while the relative position and/or size affects the flow rate of the fluid806through the three-way valve842to one or more of the ports therein.

Referring now toFIG. 9, a three-way valve942may have a square or knife gate952. The square or knife gate952may seal against the seat to provide a stronger valve than a needle valve such as three-way valve942. For example, the material of the seat0and/or gate952may wear over time with use of the system. As the sealing and/or unsealing of the three-way942may allow the automatic and/or manual modes of a hydraulic actuator, it may be desirable to mitigate or prevent operational wear of the three-way valve942. For embodiments in which mitigation or prevention of operational wear may not be possible, mitigation or prevention of the impact of the operation wear on the performance of the three-way valve942may be desirable.

As shown inFIG. 10, another embodiment of a three-way valve1042may be a spool-valve where a first auxiliary line1020a, a second auxiliary line1020b, and a reservoir line1038fluid passages enter parallel to each other and perpendicular to the chamber of the valve through a first port1044, a second port1046, and a third port1048, respectively. A cylindrical seat1050may include a rotatable gate1052that is rotated axially about a longitudinal axis1053of the rotatable gate1052within the cylindrical seat1050and may have one or more seals1055that separate the first port1044, second port1046, and third port1048from each other when the rotatable gate1052is in a closed position. When the rotatable gate1052is rotated axially to an open position shown inFIG. 10, the passages may be uncovered and fluid would be allowed to flow between the first port1044, second port1046, and third port1048through a channel1054in the cylindrical gate1052. The cylindrical gate1052may, in other embodiments, include additional channels1054that may provide fluid communication between different combinations of the first port1044, second port1046, and third port1048to provide selective fluid communication therebetween. In yet other embodiments, the three-way valve1042may include outlet ports allowing the connection of the three-way valve1042directly to the first line and second line of a hydraulic actuator. In a first position, fluid from the first line and second line may each flow through the three-way valve1042without interference to allow automatic mode operation of the hydraulic actuator. In a second position, the rotatable gate1052may be rotated to redirect fluid flow from the first line directly to the second line to provide fluid communication therebetween, scaling the first line and second line external to the hydraulic actuator and allowing manual mode operation of the hydraulic actuator.

FIG. 11is a flowchart depicting a method1156of manually overriding a hydraulic choke or valve actuator. The method1156may include filling1158an interior space of a chamber or other housing with a fluid. The fluid may enter the chamber through an inlet line and exit the chamber through an outlet line. The chamber or other housing may contain a movable element, such as a gear or a piston, in contact with the fluid. In some embodiments, the method1156may include connecting the inlet line and the outlet line through an auxiliary line. In other embodiments, the auxiliary line may have a valve therein to selectively allow fluid flow through the auxiliary line.

The method1156may include providing1160fluid communication between the inlet line and the outlet line through the auxiliary line, for example, by moving the valve in the auxiliary line to an open position. The method1156may include moving1162the movable element contained in the chamber or housing to generate fluid flow though the auxiliary line.

In some embodiments, the method1156may include disabling fluid communication between the inlet line and the outlet line through the auxiliary line, and moving fluid through the interior space of a chamber thereby generating movement of the movable element. In other embodiments, the chamber may have a first chamber portion and a second chamber portion. The first chamber portion and second chamber portion may have a different rate of volumetric change upon moving the movable element. For example, the first chamber portion may change volume more or less than the second chamber portion in response to a given movement of the movable element. In yet other embodiments, connecting the inlet line and the outlet line may include connecting a reservoir in fluid communication with the auxiliary line. In still further embodiments, generating fluid flow through the auxiliary line may include allowing fluid to flow into or out of the reservoir.

FIG. 12is a flowchart depicting another embodiment of a method1264of manually overriding a hydraulic actuator using a reservoir to balance volumetric changes in a chamber of the hydraulic actuator. Similar to the method1156described in relation toFIG. 11, the method1264may include filling1266an interior space of a chamber or other housing with a fluid. The fluid may enter the chamber through an inlet line and exit the chamber through an outlet line. The chamber or other housing may contain a movable element, such as a gear or a piston, in contact with the fluid.

In some embodiments, the method1264may include connecting the inlet line and the outlet line to one another and to a reservoir through an auxiliary line. In other embodiments, the reservoir may be at least partially full with fluid. In yet other embodiments, the reservoir may be empty. In yet further embodiments, the reservoir may be filled with fluid.

The method1264may include providing1268fluid communication between the inlet line, outlet line, and reservoir, for example, by moving a three-way valve in the auxiliary line to an open position. In some embodiments, providing1268fluid communication between the inlet line, outlet line, and reservoir may be simultaneous. In other embodiments, providing1268fluid communication between the inlet line, outlet line, and reservoir may be asynchronous. For example, providing1268fluid communication between the inlet line and outlet line may include opening a first valve in the auxiliary line at a first time and establishing fluid communication with the reservoir may include opening a second valve in a reservoir line at a second, different time.

The method1264may include moving1270the movable member to generate fluid flow though the auxiliary line. The method1264may include balancing1272a volumetric change in a first chamber portion relative to a second chamber portion. In some embodiments, the volumetric change may be balanced by allowing at least part of the fluid to flow into or out of the reservoir. For example, the movable element may have a greater volume (i.e., a stem of a piston) in the second chamber portion than the first chamber portion, thereby altering the volume of the second chamber portion at a different rate than the first chamber portion during movement of the movable element. Balancing1272the volumetric change in a first chamber portion relative to a second chamber portion may limit or prevent damage to the hydraulic actuator.

Other embodiments of the manual override system may be configured such that the valve and/or the reservoir are integrated directly into the body of the hydraulic motor or cylinder thereby making the overall apparatus more compact. The valve may be incorporated into the hydraulic power unit (i.e., the control console). However, the control console may potentially be located far away from the actuator thereby increasing the response time since the operator would need to move back and forth between the control console and the actuator. Thus, the valve may be integrated into both the console and the actuator so that it can be activated from either location. However, if valves are located at both locations, the potential exists for a valve at one location to be open unbeknownst to the operator thereby causing an erratic system response when normal operation is started. To prevent this, the operation of the valves may be linked together using a push/pull cable, an electric mechanism, a hydraulic mechanism or a mechanism similar to that described in U.S. patent application Ser. No. 13/942,420 which was filed on Jul. 15, 2013 and is hereby incorporated by reference in its entirety. In another embodiment, an indicator mechanism may be incorporated between the valves to allow the operator to see the valve configuration from either location. An indicator feature may be advantageous even when as single valve is used.

The manual override system may also be applied to pneumatic systems or other types of fluid power systems not mentioned herein or any other type of systems where relief of excess fluid or pressure for manual override operation may be helpful.

The term “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the term “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount. Further, it should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “up” and “down” are merely descriptive of the relative position or movement of the related elements. Any specific values described herein should be understood to not be limited to that value, but rather to encompass that value and associated values within a range within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount.

It should also be understood that while several embodiments are described, any element described in relation to any embodiment may be combined with any element described in relation to any other embodiment, as appropriate. Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather it extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.