The present disclosure relates in general to apparatus for controlling or regulating the torque transfer between components of a torsional drive system, such as but not limited to drill string components used to transmit rotary power and carry axial loads in top-drive-equipped drill rigs, such as in casing-running or drilling-with-casing operations for wells bored into subsurface formations.
It is well known to construct a well by rotating a drill bit mounted to the lower end of string of drill pipe to drill a borehole into subsurface soil formations, and then to install a tubular casing (or liner) string in the borehole to prevent adjacent soil materials from falling into the borehole. After the borehole has been cased, a string of production tubing is run into the well to carry well fluids to the surface.
In cases where a top-drive-equipped drilling rig is used for the drilling operation (as opposed to a “rotary table”), it is increasingly common to install (or “run”) the casing using so-called casing running tools (CRTs) operatively engaged by the top drive. In an alternative method of constructing a well commonly called “drilling with casing”, the drill bit is mounted to the end of a casing string such that the casing string acts as the drill string and remains in the borehole after completion of drilling operations, thus eliminating the need to remove the drill string to install casing. In either of these methods, the top drive must transmit torque and axial loads to the tubular string (i.e., drill string or casing string), and a sealed conduit for drilling and completion fluids must be provided between the top drive and the tubular string.
Among the routine procedures carried out during well drilling and completion operations are the assembly (or “make-up”) of the tubular string by means of threaded connections between adjacent lengths (or “joints”) of pipe, and the disassembly (or “break-out”) of these connections. The upper end of each joint of pipe in the tubular string typically carries a female thread (and is referred to as a “box end”), and the lower end of each joint carries a complementary male thread (and is referred to as a “pin end”). To add a new joint to the tubular string, the upper end of the string is suspended by gripping apparatus commonly known as “slips” mounted in the rig floor, and the pin end of the new joint is “stabbed” into the box end at the top of the string suspended in the slips. The new joint is then rotated to make up a threaded connection with the suspended string.
Such threaded connections usually need to be made up to a controlled torque to form a mechanical, metal-to-metal seal between the ends of the pipe joints, and to ensure that drilling loads (or casing running loads) can be properly transmitted through the connection. In more traditional drilling operations using a rotary table, tubing joints are typically made up using power tongs to both apply and control the rotation and torque. However, in drilling operations using top-drive-equipped rigs, the top drive may be used not only to assemble drill strings, but also for make-up (and break-out) of tubing string connections.
For threaded connections for casing strings and production strings, the applied make-up torque typically needs to be within a relatively more tightly-controlled range than for drill strings, to ensure proper function of the connection. These connections may incorporate torque shoulders and metal-to-metal seals requiring precise make-up control (commonly referred to as “torque-turns” control), and they tend to be more sensitive to over-torque damage than drill pipe connections. These connections are relied upon to provide a high level of leakage integrity. If the make-up torque of a connection is too low, the torque shoulders and metal-to-metal seals might not be properly engaged, resulting in poor connection performance. If the make-up torque is too high, the connection may be damaged, thereby compromising its seal performance and/or structural capacity.
Generally speaking, the torque-turns (i.e., rotational position) control systems of top drives only anticipate the control needs for make-up of tool joint connections used on drill pipe, and not the needs for relatively much more rapid response and more precise torque-turns control for casing and production tubing connection make-up. Furthermore, the large size of many top drive units makes such rapid and precise control difficult in any case. Accordingly, there is an increased need for means for better managing the torque loads applied during make-up operations using top drives, particularly in the context of casing and production tubing strings.
In general terms, one aspect, the present disclosure teaches a torque transfer control tool for installation between components of a torsional drive system, for preventing the transfer of excessive torque that could damage the torsional drive system. This functionality is provided by means of a rotary-stroking piston or plunger actuated by a mandrel having an upper end which may be co-rotatably coupled to a first torsional drive system component (such as but not limited to a top drive), and a lower end coaxially disposed within the bore of a generally cylindrical tool housing, with a lower end of the tool housing being co-rotatably coupled to a second torsional drive system component (such as but not limited to a tubular casing joint).
The mandrel is coaxially rotatable relative to the tool housing, and it coaxially engages the rotary-stroking piston such that rotation of the mandrel will result in axial movement of the piston within the housing without corresponding axial movement of the mandrel relative to the housing. The piston is axially movable within a sealed fluid chamber that comprises an upper fluid chamber above the piston and a lower fluid chamber below the piston.
Downward axial movement of the piston (induced by rotation of the mandrel in a first rotational direction due to torque transferred to the mandrel by the first torsional drive system component) will pressurize a fluid present in the lower fluid chamber until the pressure therein reaches a first pre-set pressure, whereupon fluid flow control means associated with the piston will allow fluid from the lower fluid chamber to flow into the upper fluid chamber, so as to prevent the pressure in the lower fluid chamber from exceeding the first pre-set pressure. This has the effect of limiting the torque that will be transferred to the second torsional drive system component in the first rotational direction via the tool housing.
Similarly, upward axial movement of the piston (induced by rotation of the mandrel in a second rotational direction due to torque transferred to the mandrel by the first torsional drive system component) will pressurize a fluid present in the upper fluid chamber until the pressure therein reaches a second pre-set pressure, whereupon fluid flow control means associated with the piston will allow fluid from the upper fluid chamber to flow into the lower fluid chamber, so as to prevent the pressure in the upper fluid chamber from exceeding the second pre-set pressure. This has the effect of limiting the torque that will be transferred to the second torsional drive system component in the second rotational direction via the tool housing.
One non-limiting example of a practical use for a torque transfer control tool in accordance with the present disclosure is to facilitate more precise control of make-up torque during the assembly of tubing strings during the drilling and construction of oil and gas wells. In this particular context, such a tool may alternatively be referred to as a “torque hold sub” or “THS” (the term “sub” being a common term in the petroleum industry for a secondary component in a tubular string), as the tool is effective to “hold” the torque transferred thereby at a predetermined maximum level, regardless of the magnitude of the torque applied to the tool (within tool-specific operational limits).
In one exemplary embodiment, the present disclosure teaches a tool for controlling torque transfer in a torsional drive system, comprising:
In another exemplary embodiment, the present disclosure teaches a tool for controlling torque transfer in a torsional drive system, comprising:
Embodiments in accordance with the present disclosure may use what are commonly known as rotary actuators, meaning mechanisms that convert linear piston motion into piston shaft rotation using pressurized hydraulic fluid to move an actuator, thus creating torque in the system. Non-limiting examples of rotary actuators include helical-splined actuators, piston-and-helix actuators (which may alternatively be referred to as rotary-stroking pistons), and sliding sleeve actuators. In systems taught herein, however, instead of hydraulic fluid being used to move an actuator to create torque (as in conventional usage of rotary actuators), rotational input causes a piston or plunger to move the hydraulic fluid. In other words, rotary actuators as used in accordance with the present disclosure operate in reverse as compared to how they operate in conventional use.
Embodiments will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which:
Tool housing 20 has an upper end 20U, a lower end 20L, and a tool housing bore 21 extending between upper and lower ends 20U and 20L. In the particular embodiment illustrated in
Endcap 30 has an upper end 30U, a lower end 30L, and an endcap bore 31 extending between upper and lower ends 30U and 30L. Endcap 30 is coaxially fixed within a lower region of tool housing bore 21 (by means of longitudinal keyways 110 or any other functionally suitable means), with external threads on endcap 30 engaging threaded tool housing bore interval 21A, and sealed relative to tool housing 20 by suitable seal means (such as but not limited to an O-ring disposed in an annular groove in tool housing bore 21 as generally denoted by reference number 23). Lower end 30L of endcap 30 is adapted for coaxial connection to a tubing string (not shown). In the illustrated embodiment, lower end 30L of endcap 30 is configured as a pin end for this purpose; but this is by way of non-limiting example only; in alternative embodiments, lower end 30L could be configured as a box end or in any other functionally adequate fashion.
Piston housing 60 has an upper end 60U and a lower end 60L, and is coaxially fixed to tool housing 20 within lower medial tool housing bore interval 21B. To prevent rotation of piston housing 60 relative to tool housing 20, lower end 60L of piston housing 60 is shown in
As illustrated in
In the illustrated embodiment, piston housing 60 is disposed within tool housing bore 21 such that upper end 60U of piston housing 60 abuts downward-facing annular shoulder 23 in tool housing bore 21.
In the particular embodiment illustrated in
In the particular embodiment illustrated in
As illustrated in
The subassembly of lower mandrel 40, rotary actuator 50, and piston housing 60 may be referred to as torque-hold mechanism 456.
Also as illustrated in
In a typical procedure for assembling THS 100, installation of mandrel assembly 70 will take place after piston housing 60 has been installed inside tool housing bore 11, with upper end 60U of piston housing 60 abutting downward-facing shoulder 23 in tool housing bore 11. Mandrel assembly 70 may then be inserted into tool housing bore 11 and piston housing bore 61, such that upward movement of lower mandrel 40 is prevented or restrained by downward-facing shoulder 65 in piston housing bore 61. As best seen in
In the illustrated embodiment, lower end 40L of lower mandrel 40 sealingly and coaxially engages endcap bore 31 such that mandrel assembly 70 is rotatable about the longitudinal axis of THS 100 relative to endcap 30 and tool housing 20, with endcap bore 31 in fluid communication with lower mandrel bore 41. As indicated in
In the embodiment shown in
As may be seen in
In an alternative embodiment, outer cylindrical surface 124 of piston shaft 120 and lower medial region 61B of piston housing bore 61 could be smooth rather than threaded as shown in
In the particular embodiment illustrated in
When fluid pressure acts on the sealing element from the side opposite the valve seat, herein referred to as the outlet side, the pressure acts to sealingly engage the sealing element to the valve seat and prevent fluid flow. When fluid pressure acts on the sealing element from the same side as the valve seat, herein referred to as the inlet side, the pressure acts to disengage the sealing element from the valve seat, thus allowing fluids to flow through the valve.
The sealing element is sealingly pre-engaged to the valve seat by use of a pre-loaded spring, such that higher fluid pressure is required on the inlet side to disengage the sealing element from the valve seat. The differential fluid pressure required to dis-engage the sealing element from the valve seat is herein referred to as the opening pressure. The opening pressure is a function of the preload force exerted by the sealing element on the valve seat and the area of the sealing element upon which the fluid pressure acts. Pre-engagement is achieved. Valve 80 further comprises an adjustment to alter the amount of pre-engagement between the sealing element and the valve seat, such that the opening pressure can be adjusted.
As best seen in
THS 100 also an upper fluid chamber 142 comprising an annular space 125 between tool housing 20 and piston housing 60, and annular space 115 between piston housing 60 and lower mandrel 40 above primary piston 150, with annular spaces 115 and 125 being in fluid communication via a port 68 in piston housing 60. Pressure integrity of upper fluid chamber 142 is maintained by seals 202, 206, 201, 207, and 204, and valve 160, which is oriented such that pressure in lower fluid chamber 141 acts on the inlet side of the valve 160, and by valve 80, which is oriented such that pressure in fluid chamber 141 acts on the outlet side of valve 80.
A port 39 is provided in endcap 30 for filling fluid chambers 141 and 142 with a suitable fluid (such as but not limited to a hydraulic fluid) or fluid mixture. After filling and during operation, a plug is placed in port 39 at its lower end to seal port 39 and prevent fluid leakage.
THS 100, in the embodiment shown in
Axial translation of primary piston 150 results in compressive loads being transmitted to a fluid provided in lower fluid chamber 141, thus increasing the pressure of that fluid, and thereby restraining incremental axial translation of primary piston 150. Selection of helix angles is thus further directed to control piston displacement and resultant fluid displacement, thus significantly facilitating control or regulation of the rotation allowed and the fluid pressure induced by torque applied to THS 100.
The composition of the fluid (or fluid mixture) in lower fluid chamber 141 is selected to provide the desired tool stiffness, defined by the amount of piston stroke for the fluid to be compressed, for the application. While axial translation of the piston is restrained by the fluid, relative rotations between lower mandrel 40, primary piston 150 and piston housing 60 are prevented; accordingly, the torsional loads are transmitted from lower mandrel 40 through piston housing 60 to endcap 30. As torsional loads increase, the pressure of the fluid will increase due to the increased axial compression placed on the fluid by primary piston 150.
When the pressure in lower fluid chamber 141 exceeds the opening pressure of valve 80, fluid will be displaced from chamber 141 through relief valve 80 and port 38 to upper fluid chamber 142 thus allowing axial translation of primary piston 150 toward endcap 30. Accordingly, torsional load transmitted through piston housing 60 tends to plateau while relative rotation occurs between mandrel assembly 70 and endcap 30.
At the end of its stroke, primary piston 150 butts against endcap 30, at which point there can be a risk of frictional locking (analogous to jamming of a torqued nut into the head of a bolt) at the helically-threaded engagements between piston shaft 120 and piston housing 60 and between piston shaft 120 and lower mandrel 40. In the described tool configuration, for a given thread form, the helix angles may be selected to be sufficiently steep to prevent such frictional locking, as will be apparent to one skilled in the art. For reference, the fluid path through the tool is indicated by arrows F in
Tools in accordance with the present disclosure provide means for generating a controlled torque/rotation profile (which may be referred to as a plateau, although the plateau does not necessarily have to be flat) that is transmitted through the tool when torque and rotation are applied to the tool. Referring now to
Accordingly, when primary piston 150 has helically translated a sufficient distance downward, dog stops 56 contact dog stops 310 on endcap 30, thus preventing further relative rotation so that incremental rotation applied to lower mandrel 40 (via upper mandrel 10) is passed directly to endcap 30. The dog stops thus provide positive means for stopping for primary piston 150 when it contacts endcap 30 and prevents primary piston 150 from sticking due to frictional locking at the helically-threaded engagements between piston shaft 120 and piston housing 60 and between piston shaft 120 and lower mandrel 40.
Similarly in break-out, dog stops 69 provide a positive stop for dog stops 55, preventing primary piston 150 from sticking due to frictional locking. When primary piston 150 has helically translated a sufficient distance downward, dog stops 55 on primary piston 150 contact dog stops 69 on piston housing 60, thus contact preventing further relative rotation. The dog stops thus provide a positive stop for primary piston 150 before it can contact downward-facing shoulder 45 on lower mandrel 40. This prevents primary piston 150 from sticking due to frictional locking (as previously described).
Movement of pressurized fluid through valve 80 will generate heat and induce a subsequent rise in the fluid temperature. To ensure that heat does not adversely affect tool performance (such, for example, by increasing the fluid temperature beyond a physical limit, like the fluids boiling or flash points, or degrading the quality of elastomeric seals or valve components), the heat must be dissipated from the fluid to the atmosphere. The fluids in fluid chambers 141 and 142 represent a small portion of the total thermal mass of the tool; therefore, the mechanical components of the tool can function as a heat sink. The contact area between the working fluid and mechanical components of the tool may be selected to enable heat to be dissipated at an adequate rate into the tool. External tool surface area may be selected to dissipate the heat to the atmosphere.
In the embodiment illustrated in
THS 100 may be reset (i.e., returned to its original position) by applying break-out rotation to upper mandrel 10 (and thereby to lower mandrel 40) such that primary piston 150 helically translates upward toward downwards-facing shoulder 44 on lower mandrel 40. This reverse helical motion causes fluids to be displaced from upper fluid chamber 142 into lower fluid chamber 141 through valve 160 via a port 54 formed in piston shaft 120 above valve 160. Valve 160 optionally may be configured to provide pre-engagement of the valve sealing element such that during break-out rotation, translation of primary piston 150 axially toward lower mandrel 40 is restrained by fluid in upper fluid chamber 142 such that torsional loads are through piston housing 60. When sufficient pressure is generated such that the opening pressure of valve 160 is reached, fluid is displaced from upper fluid chamber 142 through port 54 back into lower fluid chamber 141, thus allowing upward axial translation of primary piston 150 towards lower mandrel 40.
The opening pressure of relief valve 80, in combination with the fluid characteristics and flow path geometry from fluid chambers 141 to 142, defines the maximum torsional load that can be transferred through torque-hold mechanism 456 in make-up rotation before relative rotation begins and the torque transmitted plateaus (curve 902 in
In one embodiment, the flow resistance between fluid chambers 141 and 142 is minimized, such that the actual differences in torque between curves 902, 904, and 905 are small, by incorporating a grooved interval 66 between piston housing 60 and tool housing 20 from the lower end 40L of piston housing 60 to the upper end 40U. Any means that reduces the flow resistance in the annular space could be used, such as, by way of non-limiting example, helical grooves in an inner surface of tool housing 20 or a series of axial grooves or axial ports in piston housing 60 or tool housing 20. Alternatively, flow resistance could be increased, by changing the shape and path of any port or grooved interval through which fluids must pass when flowing from fluid chamber 141 to fluid chamber 142, such that curves 904 or 905 occur at some other torque level, the torque level and the corresponding rotation rate being selected based on the particular application.
The opening pressures of valves 80 and 160 are illustrated as being mechanically controlled. In such embodiments, opening pressures would have to be set manually at the tool. However, other means could be used to set valve opening pressures indirectly or automatically. For example, mechanical setting of valve opening pressures could be effected by an electronic servo mechanism controlled by a transmitter located away from the tool. Communication between the servo mechanism and the transmitter could be achieved either through wired or wireless (remote) equipment, although wireless would be preferred in a typical application to avoid damage to the electronic equipment as the tool is rotated.
Further, the transmitter could be linked to a computer system with intelligent programming, such that the “hold” torque is set automatically based on a predefined program or a path tailored for the specific connections that are being made up or broken out.
The opening pressure of the relief valve therefore controls the maximum torsional load that can be transferred from mandrel 70 to tool housing 20 in break-out rotation before relative rotation begins. The length of axial translation (i.e., stroke) of primary piston 150 in make-up rotation, combined with the geometry of the helical threads on piston shaft 120, defines the maximum number of rotations through which the torsional load is held constant.
It is not essential that valve 80 or valve 160 (or an alternative control valve) be in the specific locations illustrated in the Figures to achieve the desired function, persons skilled in the art will readily appreciate that other effective means of providing fluid flow communication and restriction between fluid chambers 141 and 142 may be devised without inventive effort. To provide non-limiting examples of this, a similar function could be achieved by removing port 54 and valve 160 and replacing relief valve 80 with a double-acting control valve or by removing port 54 and valve 160 and placing additional ports in endcap 30 and a control valve within those ports, such that the relief valve acts to prevent fluid movement from fluid chamber 141 into fluid chamber 142 and restrains fluid movement from chamber 142 into chamber 141.
Throughbores 12, 31 and 41 provide a flow path through THS 100 for circulating fluids into the wellbore during drilling and running operations. Seals 205 and 208 ensure no fluid communication between the internal working fluid and the wellbore fluids.
Optionally, a mandrel sleeve 170 may be provided over upper portions of upper mandrel 10 and tool housing 20. Sleeve 170 is non-rotatably and non-translatably fix to upper mandrel 10 by any suitable means (such as bolts, splines, and/or keyways), but is both rotatable and axially movable relative to tool housing 20. Sleeve 170 provides a sacrificial surface for gipping upper mandrel 10 for make-up and break-out of threaded connections in a tubular string, and for preventing contaminants from entering tool housing 20.
The embodiment shown in
As best seen in
In the illustrated embodiment, an annular bearing 90 is disposed upon upward-facing shoulder 64 on piston housing 60 and encircling an upper region of lower mandrel 40, with a lock ring 185 disposed above bearing 90 around and anchored to lower mandrel 40 for axial retention of bearing 90 relative to tool housing 20 and lower mandrel 40. When compressive axial load is applied to THS 100, downward facing shoulder 15 of upper mandrel 10 abuts onto upper end 40U of lower mandrel 40, thus transferring axial loads through lock ring 185 to bearing 90 to piston housing 60 to endcap 30. When such compressive load is present, bearing 90 ensures that frictional resistance to rotation is sufficiently low during rotation of upper mandrel 10 and lower mandrel 40 relative to piston housing 60.
Friction within the various interfaces of THS 100—particularly at the abutment between upward-facing shoulder 14 on upper mandrel 10 and downward-facing shoulder 25 on tool housing bore 21, and between lock ring 185 and upward-facing shoulder 64—in the presence of axial loading of THS 100, causes torque to bypass the torque hold mechanism, and to be transmitted to endcap 30 via frictional forces generated at the interfaces. The torque allowed to bypass the torque-hold mechanism is a function of the axial load in THS 100 and the coefficient of friction between the abutting components. One particular intended use of THS 100 is for make-up of casing strings, during which minimal axial load is present on THS 100, and as such THS 100 is been illustrated with a shoulder that has no supplementary means of friction reduction. However, in some applications, axial load along with controlled torque-hold functionality may be desired simultaneously, and for such applications a low-friction bushing or bearing could be provided at this interface to minimize torque transfer through friction.
It will be apparent to persons skilled in the art that tools in accordance with this disclosure can readily adapted to provide any practical desired length of axial compensation stroke. However, the practical utility of torque transfer control tools in accordance with the present disclosure is not reliant upon the incorporation of axial compensation functionality. For application in which the required amount of axial compensation is minimal, the number and complexity of tool components can be reduced to provide a more compact tool, without taking away from the primary function of the tool, which is to provide control of torque during rotation.
It will be apparent to persons skilled in the art that tools in accordance with this disclosure can readily adapted to provide any practical desired length of axial compensation stroke. However, the practical utility of torque transfer control tools in accordance with the present disclosure is not reliant upon the incorporation of axial compensation functionality. For application in which the required amount of axial compensation is minimal, the number and complexity of tool components can be reduced to provide a more compact tool, without taking away from the primary function of the tool, which is to provide control of torque during rotation.
Persons skilled in the art will recognize that variant embodiments of THS 100 be can readily adapted to provide any practical desired length of axial compensation stroke. However, the practical utility of torque transfer control tools in accordance with the present disclosure is not reliant upon the incorporation of axial compensation functionality. For applications in which the required amount of axial compensation is minimal, the number and complexity of tool components can be reduced to provide a more compact tool, without taking away from the primary function of the tool, which is to provide control of torque during rotation.
In some applications, it may be beneficial to incorporate multiple torque plateaus in the torque transmitted through the tool.
Various components of THS 400 generally correspond to analogous components in other illustrated embodiments, and share the same reference numbers. In addition to a modified unitary mandrel 410, a modified tool housing 420, THS 400 includes additional components as described below.
An endcap extension 190 is mounted on upper end 30U of endcap 30, and has an upper end 190U, a lower end 190L, and a coaxial longitudinal throughbore 191. A series of dog stops 192 are provided on upper end 190U near throughbore 191. The outer surface of endcap extension 190 is generally cylindrical, and has longitudinal keys 193 near its upper end for engagement with longitudinal keys 62 on piston housing 60. Endcap extension 190 further comprises port 194 and 195 providing for fluid communication in the assembled tool from its outer surface to its lower and upper ends, respectively.
THS 400 also includes a secondary piston 210 having configuration generally similar to that of actuator 50 and primary piston 150, but with necessarily larger inner and outer diameters, such that helical threads 211 and 212 located on its inner and outer surfaces, respectively, engage with helical threads 69 and 27 on the outer surface of piston housing 60 and the inner surface of tool housing 420, respectively.
Rotation applied to mandrel 410 causes primary piston 150 to rotate, thus resulting in concurrent axial movement downward away from mandrel 410 and toward endcap extension 190. The relative rotation and axial translation of primary piston 150 relative to mandrel 410 and tool housing 420 depends on the helix angles of helical engagements between piston shaft 120 and piston housing 60 and between piston shaft 120 and mandrel 410, respectively. Downward axial translation of primary piston 150 results in compressive loads being transmitted to a fluid placed in annular chamber 141, thus increasing the pressure of that fluid, and thereby restraining incremental axial translation of primary piston 150.
While axial translation of primary piston 150 is restrained by the fluid, relative rotation between mandrel 410, primary piston 150 and piston housing 60 is prevented, such that the torsional loads are transmitted through these torque-hold mechanism components to secondary piston 210, causing secondary piston 210 to rotate, resulting in concurrent downward axial movement away from piston housing 60 and toward endcap 30. Downward axial translation of secondary piston 210 results in compressive loads being transmitted to a fluid placed in an annular fluid chamber 444 below secondary piston 210, thus increasing the pressure of that fluid, and thereby restraining incremental axial translation of secondary piston 210. As torsional loads increase, the pressures of the fluids in fluid chambers 141 and 444 will increase due to the increased axial compression placed on the fluid by primary piston 150 and secondary piston 210 respectively.
When the pressure in chamber 141 exceeds the opening pressure of valve 80, fluid will be displaced from chamber 141 through relief valve 80, port 195 and port 213 to fluid chamber 142 thus allowing axial translation of primary piston 150 towards endcap extension 190, while valve 80 ensures the fluid pressure is maintained at the opening pressure, thus torsional load transmitted through the torque-hold mechanism plateaus while relative rotation occurs between mandrel 410 and endcap 30. When primary piston 150 has helically translated a sufficient distance, dog stops 56 make contact with dog stops 192 on cam stop 190, thus preventing further rotation so that incremental rotation applied to mandrel 410 is passed directly to piston housing 60.
When the pressure in chamber 145 exceeds the opening pressure of valve 220, fluid will be displaced upward from chamber 444 via valve 220, port 38, port 194, and port 213 to an annular chamber 442 above secondary piston 210, thus allowing axial translation of secondary piston 210 toward endcap 30, while valve 220 ensures the fluid pressure is maintained at the opening pressure, thus torsional load transmitted through the torque-hold mechanism plateaus while relative rotation occurs between mandrel 410 and endcap 30. When secondary piston 210 has helically translated a sufficient distance, dog stops 214 make contact with dog stops 192 on endcap 30, thus preventing further rotation so that incremental rotation applied to mandrel 410 is passed directly to endcap 30.
The opening pressure of valves 80 and 220 therefore control the maximum torsional load that can be transferred through the torque-hold mechanism before activation of each respective torque hold stage. Generally, the opening pressure of valve 80 is set to open at a lower pressure than valve 220, thus activating torque hold via primary piston 150 first. However, given the teachings above, it will be apparent to those skilled in the art that the sequence of torque hold stage activation does not impact to intended function of the tool. Further, in some applications it may be advantageous to set the opening pressures of valves 80 and 220 such that both torque hold stages activate at a similar torque, thus increasing the length number of relative rotations during the torque plateau.
The torque-hold mechanism is reset by applying break-out rotation in a manner that is similar to that of the preferred embodiment, but where breakout rotation drives concurrent rotation and upward axial translation of both primary piston 150 and secondary piston 210.
Tensile loading applied to THS 400 is transferred from upper mandrel 10 to piston housing 60 to tool housing 420 to pin connection 32 on the lower end of endcap 30. Compressive load applied to the tool is transferred from upper mandrel 10 to lock ring 185 to bearing 90 to piston housing 60 to endcap extension 190 to endcap 30.
Referring now to
As with the preferred embodiment, the torque response will vary somewhat under increasing rotational speeds based on fluid and flow path characteristics that can be selected to obtain a particular torque hold behaviour.
It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the scope of the present teachings, including modifications which may use equivalent structures or materials hereafter conceived or developed. It is to be especially understood that the scope of the present disclosure is not intended to be limited to described or illustrated embodiments, and that the substitution of a variant of a claimed or illustrated element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure.
In this patent document, any form of the word “comprise” is to be understood in its non-limiting sense to mean that any item following such word is included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure.
Relational and conformational terms such as (but not limited to) “coaxial” and “axisymmetric” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially coaxial” or “substantially axisymmetric”) unless the context clearly requires otherwise.
Unless specifically noted otherwise, any reference to an element being “generally cylindrical” is intended to denote that the element in question would appear substantially cylindrical in transverse cross-section, although the cross-sectional configuration of the element may vary along its length.
Wherever used in this document, the terms “typical” and “typically” are to be understood and interpreted in the sense of being representative of common usage or practice, and are not to be understood or interpreted as implying essentiality or invariability.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2017/000240 | 11/2/2017 | WO | 00 |
Number | Date | Country | |
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62421963 | Nov 2016 | US |