Patent Application
20240102347
This document relates to drilling downhole regulating devices and related methods.
The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
The use of axial shock absorbers in a drill string is an industry practice, especially with roller cone bits. Improvements in axial shock absorbers with straight, axial splines to transmit torque and axial springs have led to the use of a separate counter springs with the purpose of balancing the “pump-open” force from differential pressure inside the tool and the hanging weight of drill string components below the device. A counter spring extends the effective operating envelope of the device to situations where the weight on bit is less than the pump-open force plus the hanging weight of components below the device.
Downhole regulating devices with a helical coupling that moderate the combination of downhole torque and axial force have been utilized with a single one-directional biasing device. Successful regulation of downhole vibrations are achieved by using a telescopic unit with a helical coupling that has a coupling with a steep lead angle. The unit is kept extended by a combination of the hanging weight of drilling string components below the device, pump-open pressure and a biasing device comprising a compression spring. When the bit sticks, the increased torque is converted by the threaded coupling into an axial contraction which relieves the weight on bit instantaneously and allows the bit to continue rotating smoothly. In many applications the weight on bit and torque are not sufficient to overcome the pump-open force and the hanging weight of the drilling string components below the device, and the result is that the device is rigid and ineffective.
In order to extend the effective operating envelope by placing the neutral point (position) of the tool between the fully contracted and fully extended positions, the use of a counter spring has been integrated with the helical coupling. The use of a counter spring extends the operating envelope to allow the regulating device to function at low weight improving the effectiveness. The first drawback of the counter spring design, is typically that a non-linear spring curve is provided. Once the second biasing device has fully extended the sensitivity to changes in axial and torsional loads is reduced. A second drawback is that a relatively long, heavy, and complex tool is required to provide the necessary stroke length between the fully extended and fully contracted positions. A third drawback with such a design is that the typical helical coupling lead angle of 40 to 80 degrees does not efficiently transfer torque spikes to axial movement because of friction in the helical coupling and bearings, and the net result is that the device is less responsive to small changes in torque or weight on bit.
A downhole regulating device is disclosed for use in a drill string, the downhole regulating device comprising: a helical coupling between a lower portion and an upper portion of the downhole regulating device and structured to allow relative axial and rotational movement between the lower portion and the upper portion; and a bi-directional biasing device that resists movement between the lower portion and the upper portion in both axial extension and contraction directions and is arranged such that a neutral position of the bi-directional biasing device is between fully extended and fully contracted positions of the helical coupling.
A method is disclosed comprising: operating a drill string in a well to drill, ream, or mill; and in which, during operation, a downhole regulating device in the drill string acts to relatively axially extend and retract an upper portion, and a lower portion, of the downhole regulating device corresponding to an angular position of the upper portion relative to the lower portion, while a bi-directional biasing device of the downhole regulating device resists movement between the lower portion and the upper portion in both axial extension and contraction directions, in which the bi-directional biasing device is arranged such that a neutral position of the bi-directional biasing device is between fully extended and fully contracted positions of the downhole regulating device.
A downhole regulating device is disclosed for use in a downhole drill string, the downhole regulating device comprising: a plurality of helical couplings between a lower portion and an upper portion of the downhole regulating device and structured to allow relative axial and rotational movement between the lower portion and the upper portion in both directions from a neutral position, between a fully extended position and a fully contracted position; and a plurality of bi-directional biasing devices that resist movement between the lower portion and the upper portion in both axial extension and contraction directions and are arranged such that a neutral position of the downhole regulating device is between fully extended and fully contracted positions of the plurality of helical couplings.
A torsional spring is disclosed that comprises a laminate of metal on an inside with layers of carbon fiber on an outside.
A torsional spring is disclosed comprising a laminate of: a metal on an inside portion of the torsional spring; and a composite material on an outside portion of the torsional spring, the composite material having one or more layers functioning to improve the fatigue performance, or increase the spring rate, of the torsional spring when loaded in a constricting direction.
In various embodiments, there may be included any one or more of the following features: The helical coupling comprises a plurality of helical couplings arranged to modify performance characteristics or to provide a variable lead angle. The bi-directional biasing device comprises a helical spring that functions in a) torsion, b) both compression and tension, or c) torsion, compression, and tension. The bi-directional biasing device comprises a plurality of helical springs that act in parallel or series, with the plurality of helical springs arranged concentrically, intertwined, or connected end-to-end. The bi-directional biasing device comprises a bellows spring. The bi-directional biasing device comprises a pipe spring. The bi-directional biasing device defines a central fluid passage. The bi-directional biasing device comprises a plurality of helical springs whose helical spring coils shoulder on adjacent helical spring coils in the fully contracted position. The bi-directional biasing device comprises one or multiple intertwined helical springs whose helical spring coils shoulder on adjacent helical spring coils in the fully contracted position. The helical coupling has a right-hand thread and the bi-directional biasing device comprises a plurality of helical springs that are rigidly connected to the lower portion and the upper portion and function in combined torsion, compression, and tension, with a left-hand coil direction to reduce the magnitude of diametrical changes within the helical spring while it moves between the fully extended and the fully contracted positions. The helical coupling has a right-hand thread and the bi-directional biasing device comprises a plurality of helical springs, with a left-hand coil direction, that are rigidly connected to the lower portion and rigidly connected to the upper portion and function in combined torsion, compression, and tension. The bi-directional biasing device is rigidly fixed, axially and rotationally, to both the lower portion and upper portion, resisting both axial movement and rotational movement. The bi-directional biasing device is axially fixed to both the lower portion and the upper portion using a plurality of bi-directional thrust bearings or bushings. The primary and secondary elements of the bi-directional biasing device work together in the same direction to extend the downhole regulating device between a contracted position and the neutral position. A bi-directional thrust bearing is located between the first element of the biasing device and the helical coupling. A second bi-directional thrust bearing is located between the first element and the second element of the biasing device. The secondary element of the bi-directional biasing device is axially confined to avoid overextension when the primary element of the bi-directional biasing device is extended from the neutral position. The bi-directional biasing device functions in tension and compression and is rotationally de-coupled from the relative rotation of the upper and lower portions. The bi-directional biasing device comprises a primary element and a secondary element; the secondary element comprises a compressive spring; the secondary element modifies a spring rate or increases a stroke length in the contraction direction of the bi-directional biasing device; and the primary and secondary elements of the bi-directional biasing device work together in the same direction. The secondary element comprises a stack of disc springs. The bi-directional biasing device comprises a bellows spring that functions in compression and tension. The bi-directional biasing device comprises a pipe spring that functions in compression and tension. The bi-directional biasing device functions in torsion; and the bi-directional biasing device is rotationally fixed to both the lower portion and upper portion of the downhole regulating device using a plurality of splines or ball splines to resist relative rotational movement in the helical coupling. The bi-directional biasing device comprises a laminate of metal on an inside portion of the bi-directional biasing device with layers of a composite material on an outside of the bi-directional biasing device. Shoulders are employed to limit a stroke of the bi-directional biasing device in both extension and contraction. The helical coupling defines a helix angle of between 5 and 70, for example between 20 and 40 degrees, in some cases between 10 and 50 degrees. A drill string has a drill bit, a downhole motor, and the downhole regulating device. A method comprises arranging the downhole regulating device in a lower string portion of the drill string near a drill bit. The downhole regulating device is arranged above a downhole motor. The downhole regulating device is arranged below a downhole motor. Operating the drill bit in a well to drill, ream, or mill. A first helical coupling of the plurality of helical couplings has a lead with a first biasing device, of the bi-directional biasing device, that resists movement in a contraction direction; a second helical coupling of the plurality of helical couplings has a lead with a second biasing device, of the bi-directional biasing device, that resists movement in both extension and contraction directions; and the second helical coupling is arranged such that a neutral position is between fully extended and fully contracted positions. A lead of the first helical coupling is larger than the second helical coupling; the first biasing device comprises a compressive spring or set of disc springs; and the second biasing device comprises a torsional spring. A lead of the first helical coupling is larger than the second helical coupling; the first biasing device comprises a compressive spring; and the second biasing device comprises a helical spring that functions in a) torsion, b) both compression and tension, or c) torsion, compression, and tension. A second biasing device is configured with a compression spring that it is not in a load path of the bi-directional biasing device and works in parallel, wherein the second biasing device is not compressed while the regulating device is at the neutral point. The downhole regulating device is arranged below a reamer. The downhole regulating device is arranged above a reamer. The composite material comprises layers of composite wherein at least 50% and up to 100% of filaments of carbon fibers or glass fibers are substantially oriented in a direction of spiral spring coil. Fibers of the composite material are oriented in various directions. The composite material has a higher tensile strength than the metal. The composite material retards crack propagation on the outer surface of the torsional spring when loaded in the constricting direction and used in cyclic service. The metallic layer is thicker than the composite material. End connectors of the torsional spring are formed into axial ends of the torsional spring. The composite material extends beyond an axial length of a helical path defined by the torsional spring by a ration of 1 to 100 coil thicknesses. A metallic tubing is located along an axial length of coils of the torsional spring to prevent slippage of the composite material off of the metal in the event of delamination through the use of ridges, grooves, or other profiles that are substantially aligned with a coil spiral direction. The metallic tubing is prepared at axial ends of the torsional spring with a surface with grooves, ridges, wrench flats, or a gripping surface in cross section that serve to prevent twisting between the composite material and the metal in the event of delamination at the axial ends. The composite material is manufactured by: preparing a metal bar or tube with a surface profile and finish, and primed; wrapping the metal bar or tube with carbon fibers that are pre-pregnated with epoxy resin using a filament winding technique; and after curing, cutting one or more helical slots in a direction substantially aligned with a majority of the carbon fibers. The composite material has a higher tensile modulus than the metal. Higher modulus carbon fibers are located closer to a center of the torsional spring in cross section, and lower modulus uniaxial carbon fibers are located closer towards an outer surface of the torsional spring in cross section. The lower modulus uniaxial fibers located closer towards an outer surface of the torsional spring in cross section have a higher tensile strength than the high modulus fibers.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the subject matter of the present disclosure. These and other aspects of the device and method are set out in the claims.
Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:
Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. The present disclosure relates to a regulating device and a method of using the regulating device in downhole drilling applications. The regulating device may be configured to mitigate axial and torsional drilling string dynamics that are known to damage drill string components, for example drill bits, motors, or directional tools.
Torsional vibrations are known in the industry as “stick-slip”. In severe cases the drill bit may stop rotating during the “stick” portion of the cycle and then accelerate during the “slip” portion to a rotational velocity that is multiples of the rotational velocity of the drill string at surface. When torsional vibration occurs at very high frequency it is known as High Frequency Torsional Oscillation (HFTO), a phenomenon that may be challenging to measure due to the limited data rate of downhole sensors. A typical drilling Bottom Hole Assembly (BHA) may comprise drill collars, non-magnetic drill collars, downhole motor, Measurement While Drilling (MWD), Logging While Drilling (LWD), Rotary Steerable System (RSS) and other miscellaneous equipment such as jars, reamers circulation subs, floats, stabilizers and filter subs. When drilling, BHA component failures commonly occur as a result of vibrations, stalling or micro-stalling events.
As drilling technology has advanced, the torque and power capacity of downhole motors increased substantially. This has increased the load applied to BHA components and the severity of stick-slip events. Innovations in RSS technology have also led to an increase in the amount of critical BHA components being run beneath the motor. Components beneath the motor rotate multiple times faster than those above the motor and must withstand increased vibration amplitude and frequency.
Effective drill bit design is of crucial importance to reduce damage to the drill bit and other drill string components. Most drill bit designs include features to make them less aggressive and thereby less sensitive to sticking in situations where a hard formation is encountered or a depth of cut is excessive. Most Polycrystalline Diamond Compact (PDC) bits employ a negative rake angle, so that relatively less torque is produced in response to increased weight-on-bit (WOB). Many PDC bit designs also employ depth of cut control features such as passive backup cutters or ovoids. Such features may reduce the risk of torsional vibrations in the drill string. The downside of bit-design solutions may be that they do not reliably protect the BHA, and they may reduce the efficiency of the bits. Especially in hard rock, PDC bits with negative rake angles, depth of cut control features and chamfers on the cutter surfaces, may require relatively very high weight on bit to cut as they are intended to. Additionally, the friction that results from such high weight on bit and poor cutting efficiency may result in cutters dulling rapidly due to excessive heat.
Alternately, to reduce downhole vibration, a drilling method known as ‘control drilling’ may be employed. While control drilling, drilling parameters for example weight on bit may be reduced to limit the drill bit's depth of cut and associated torque generated by interaction between the bit and formation. Control drilling is generally successful in reducing downhole vibration; however, it may significantly impair the efficiency and rate of penetration achievable while drilling.
In the prior art, utilizing axial shock absorbers in a drill string is known, especially with roller cone bits. U.S. Pat. No. 4,186,569 describes an axial shock absorber with straight, axial splines to transmit torque and axial springs. This is an example of a bi-directional tool that uses a separate counter spring, with the purpose of balancing the “pump-open” force from differential pressure inside the tool and the hanging weight of drill string components below the device while working in non-horizontal inclinations. For the purposes of this patent, a bi-directional tool is defined as one that can telescopingly contract and extend relative to the neutral position. The counter spring may extend the effective operating envelope of the device to situations where the weight on bit is less than the pump-open force plus the hanging weight of components below the device.
The application of axial shock absorbers was reduced when roller cone bits were replaced with PDCs in most drilling applications. While roller cone bits generated significant axial vibration, PDCs do not.
Regulating devices with a helical coupling that moderate the combination of downhole torque and axial force are known from the publication U.S. Pat. No. 2,754,086. Regulation of downhole vibrations are achieved by using a telescopic unit with a helical coupling that has a steep lead angle or lead. Lead is defined as the axial advance of a helix or screw during one complete turn (360°). Lead angle is the angle between the helix and a plane of rotation, and are related by the pitch diameter of a lead screw according to the following equation: Lead=tan(Lead Angle)*3.14*Pitch Diameter. The unit is kept extended by a combination of the hanging weight of drilling string components below the device, pump-open pressure and a biasing device, namely a compression spring. When the bit sticks, the increased torque is converted by the helical coupling into an axial contraction that relieves the weight on bit instantaneously and allows the bit to continue rotating smoothly. However, in many applications the weight on bit and torque are not sufficient to overcome the pump-open force and the hanging weight of the drilling string components below the device, with the result being that the device is rigid and ineffective. Even in situations where the “normal” drilling parameters allow the device to operate between fully extended and fully contracted positions, the device is less effective, especially when drilling is initiated against the work surface, or in extreme “slip” events.
In order to extend the effective operating envelope by placing the neutral point of the tool between the fully contracted and fully extended positions, U.S. Pat. No. 3,998,443 employs two biasing devices with one located above and another below the helical coupling. Extending the operating envelope to allow engagement at low weight on bit and torque provides advantages to drilling operations. However, a drawback of this design is that the biasing devices are comprised of compressible fluid chambers which experience extremely high pressures in a challenging service for which reliable seals have not yet been established. Compressible fluids also tend to heat up substantially when subjected to extreme services such as the proposed regulating device which further increases the pressure in the chambers and results in a variable spring rate. This patent also teaches to provide damping which is achieved by restricting the flow of a largely incompressible fluid between two chambers. Similar bi-directional functionality from the neutral point, but without a helical coupling, is achieved with two compressible fluid chambers in the bi-directional regulating device of U.S. Pat. No. 5,133,419.
In order to achieve bi-directional movement from the neutral point, the regulating device U.S. Pat. No. 4,276,947 utilizes a single compression spring, comprised of a stack of roller Belleville springs, which is configured to be compressed during both contraction and extension of the device. A helical coupling is not used. The roller Belleville springs are a variant of typical Belleville (disc) springs which promise to reduce friction and overloading which are inherent challenges of Belleville springs. A preload is used to compress the spring pack a small amount when it is in the neutral position. The primary drawback is that a bi-directionally loaded compression spring will have “dead zone” within the travel due to the preloaded. The “dead zone” exists when forces exerted on the spring do not exceed the preload in either the contraction or extension directions, and this results in reduced responsiveness of the device or in a worst case, damaging vibrations induced by the device while functioning around or through the “dead zone”. One might think therefore that a very small or zero preload is optimal; however, this is not practical. Most spring designs will tend to “set” when initially loaded, and “creep” during extended and severe service. In the case of a stack of Belleville washers, set and creep will result in a shortening of the free height of the spring pack and a loss of the preload. When the preload is lost, instead of exhibiting a “dead zone” there will instead be a “slop zone” wherein unconstrained extension or contraction of the device will occur between the position to engage the springs in the upwards and downwards directions. This “slop zone” is deleterious to the shock absorption function of the device and may result ineffective shock absorption or in a worst case, damaging vibrations induced by the device.
In order to achieve similar bi-directional functionality and an increasing spring rate an alternative to roller Belleville springs is proposed in U.S. Pat. No. 7,997,357 where special end spacers are used and the spring stack is comprised of two sections of Belleville springs each having a unique spring rate.
A bi-directionally loaded compression spring is incorporated into a helical coupling regulating device in U.S. Pat. Publication No. 2017/0342781 where it is used as a secondary biasing device “counterspring”. The first drawback of such a counter spring design, is that the spring curve is non-linear. Once the second biasing device has fully extended, sensitivity to changes in axial and torsional loads is reduced. A second drawback is that a relatively long, heavy, and complex tool may be required to provide the necessary stroke length between the fully extended and fully contracted positions. The increased length and weight of this tool may be a noteworthy concern when ran beneath a downhole motor as such increases the loads on the motor bearing pack and power section that can result in accelerated wear and premature failure. A third drawback is that higher levels of friction are generated by the many bearing faces and long inner sleeve which may contact various other components within device when subjected to bending through doglegs in a directionally drilled wellbore. Devices with opposing springs, particularly those which do not employ thrust bearings at every bearing surface will inherently experience much higher levels of friction. Friction is undesirable in almost all shock absorber applications, because friction results in sticking followed by sudden jerky movements. Additionally, friction makes the device less responsive to small changes in torque or WOB.
Moderately high levels of friction when responding to torsional inputs are inherent with known configurations that use an axially loaded spring to absorb the primarily torsional shocks and high frequency torsional oscillations that are created when drilling with PDC bits, because of the friction in the helical coupling, where the helical coupling converts a torsional input to an axial motion through a relatively steep helix lead angle, typically in the range of 40 to 80 degrees. Ball splines promise to reduce the friction of the helical coupling but have not yet proven reliable in downhole drilling service.
Further adaptations have been made to helical coupling regulating devices for various applications through the use of orifices, pressure balancing, use of elastomers at various interfaces, improved or customizable damping characteristics, and multiple splined sections. Various examples include: U.S. Pat. Nos. 4,901,806A, 6,308,940B1, 7,044,240B2, 7,578,360B2, US20120228029A1, U.S. Pat. No. 9,512,684B2, U.S. Ser. No. 10/190,373B2, U.S. Ser. No. 10/626,673B2, U.S. Pat. Nos. 7,377,339B2, 9,109,410B2, EP65601, U.S. Pat. No. 4,466,496, WO2016201443, NO325253, US20120228029, CN102678059, CN106837311, CN106894770, U.S. Pat. Nos. 3,156,106, 3,323,326, 3,998,443, 4,270,620, 3,339,380, 4,443,206, 2,754,086, 1,785,086.
Devices which attempt to mimic the function of a helical coupling through other means include: U.S. Pat. No. 7,654,344B2, GB201412778.
Other shock subs of particular interest include: U.S. Pat. Nos. 3,963,228, 9,347,279, 9,187,981, 3,947,008. Devices which utilize a helical coupling and biasing device for other non-drilling-regulating purposes for well construction and operations include: U.S. Ser. No. 10/221,657, U.S. Pat. No. 7,225,881.
Known regulating devices that use a helical coupling and disc springs may require a relatively steep helix lead angle in the range 40 to 80 degrees, or a lead of 10 to 100 inches per rotation. A lower lead angle of 5 to 40 degrees or a lead of 1 to 10 inches per rotation may be more optimal for mitigating PDC-bit induced torsional vibrations but may require use of a torsional spring to avoid excessive friction and binding in the regulating device and thrust bearing assembly.
The present disclosure proposes to improve upon the known regulating devices discussed above, or at least provide a useful alternative.
A regulating device according to the present disclosure may be an improvement upon features known from axial and helical-coupling (co-directional) shock absorbers for drill strings.
Referring to
Embodiments of the present disclosure may achieve an effective operating envelope, wherein the neutral point of the tool is located between the fully contracted and fully extended positions. For example, the neutral point may be located at a position where it can expand by a certain distance (x), and contract a different distance (y). The contraction distance (y) may be equal to 2×, 5×, 10×, or 50×. Such effect may be achieved using a single biasing device that smoothly functions in both directions about the neutral point, as opposed to known biasing devices which must be preloaded and compressed in both directions. While (the bit is) off bottom, tension from the hanging weight of the BHA and pump open force generated by fluid flow through the BHA may extend the biasing device from the neutral position. As bit is placed on bottom, weight is applied, torque is generated, and the biasing device contracts. In some cases, the device 32 may be structured or calibrated to be in the neutral position in normal operating drilling conditions. In some cases, the device 32 may be structured or calibrated to be in the fully extended position when (the bit is) off bottom. The biasing device 32 may have an operating envelope that allows for engagement and mitigation of torsional shock loads while the device is extended or contracted.
The regulating devices disclosed here may autonomously reduce vibration generated by the bit. An increase in weight or torque from the drill bit forces the regulating device to contract, reducing the weight and torque on the bit. A reduction in weight or torque from the bit forces the regulating device to extend, increasing the weight and torque on the bit. This ability to level the drilling loads on the bit may reduce the vibration generated at the bit and correspondingly, the vibration observed by all BHA components.
A single biasing device may resist axial forces, transmitting forces between the lower portion and upper portion through a bi-directional thrust-bearing. A single biasing device may resist torsional forces and transmit forces between the lower portion and upper portion through a suitable transfer mechanism such as a spline or ball spline. A single biasing device may be secured, for example anchored, for further example rigidly connected to both the lower portion and upper portion without need of a bearing and may transmit both axial and torsional forces. Because only a single biasing device may be required and may be ran at neutral load, with no pre-charge, the tool may be relatively short and light weight compared with other known tools, reducing fatigue on motor components when ran beneath a motor, and friction may be reduced.
Some embodiments may have the female portion of the helical coupling disposed on top with the biasing device contained within the female portion. This configuration may protect the biasing device from wear against the borehole while rotating, and if the device breaks, may contain any loose pieces within the tool. Additionally, such a configuration may minimize the “sprung weight” below the helical coupling which may be desirable to improve the responsiveness and effectiveness of the entire system.
Referring to
The biasing device may be located over the male portion or in the female portion or both.
The regulating device may incorporate load shoulders at either end of the operating envelope of the biasing device in both extension and contraction. The load shoulders may be the ends of the helical coupling. The load shoulders may be positioned to prevent the biasing device from exceeding its designed stress and travel limits. A secondary benefit may be that should the biasing device fail, drilling may continue, as after shouldering in contraction, drilling loads may be transmitted through helical coupling. Similarly, the shoulder in extension may allow the lower portion of the tool to retrieved to surface should the biasing device fail.
In some embodiments an inner sleeve may be used through the single biasing device to prevent buckling or erosion of the biasing device and reduce the turbulence and pressure drop of drilling fluid pumped through the device. Alternatively, the single biasing device may be exposed to the drilling fluid through the center biasing device to allow cooling and limit friction and binding.
In some embodiments, a secondary element of the biasing device may be run in combination with the primary element of the biasing device to extend the stroke achieved by the regulating device in contraction. The secondary element in this application may be oriented in the same direction as the primary element and may be ran with or without pre-charge. The secondary element of the biasing device may have low preload such that it activates after the weight on bit and torque generated through drilling exceed the hanging weight of the BHA and pump open force below the tool. In another embodiment the secondary element is preloaded such that it only begins to compress when the primary element is near the extent of its travel in the compressive direction. The secondary element may be axially contained between two shoulders, one shoulder being axially connected to the primary element of the biasing device. The telescoping movement of the primary element of the biasing device may apply axial loads on the secondary element, providing the regulating device additional stroke. The secondary element may comprise a compression spring such as a disc spring, however a compressible fluid piston or other type of spring may also be used.
In some embodiments, a secondary biasing device may be run in parallel with the primary biasing device to extend the operating envelope of the regulating device and reduce the stress on the primary biasing device. The secondary biasing device may comprise a helical spring, a compression spring such as a disc spring, compressible fluid piston or other type of spring and may not be in the same load path as the primary biasing device. For example, the primary biasing device may be a bi-directional helical spring located over the male portion while the secondary biasing device may be a disc spring located in the female portion. The secondary biasing device may function bi-directionally to assist in both extension and contraction of the regulating device, or only on contraction. The secondary biasing device may resist axial forces, transmitting forces between the lower portion and upper portion through a bi-directional thrust-bearing. The secondary biasing device may resist torsional forces and transmit forces between the lower portion and upper portion through a suitable transfer mechanism such as a spline or ball spline. The secondary biasing device may be secured, for example anchored, for further example rigidly connected to both the lower portion and upper portion without need of a bearing and may transmit both axial and torsional forces.
The regulating device may be utilized by a drilling rig comprising a drilling unit with top drive, a drilling unit with a rotary table, a servicing rig using only a downhole motor, a servicing unit with a power swivel, a servicing unit with a top drive, or a coil tubing unit.
In what follows, examples of embodiments are described and visualized in the accompanying drawings.
A tool joint 54 or other drill string connector may be provided on the end of the male portion 50 for safe and convenient handling on the drilling rig 4. While it would be possible to provide flow restrictors and lubricate the helical coupling with drilling fluid, drilling fluid lubrication may be more effective with roller or ball type bearings. However, ball bearings may be challenging to implement considering the severe service application and high loads that the helical coupling may transmit. It is therefore believed that the more cost effective and reliable solution may be to use a helical coupling as shown in
Seal, scraper, and wear bushing designs may be important for reliability of function, however also of importance may be surface finish and properties of the countersurface which the seal assemblies 33 are sliding against. The countersurface may be smoothly polished with a hard surface treatment for example induction hardening, hard chrome, various carbides or ceramics, other hard metals applied by high velocity oxygen fuel (HVOF) process, nitride or others as is known in the industry to reduce friction and wear rates on the countersurface. Similar coatings and surface treatments may be applied to the mating surfaces of the helical coupling. Such may be used for sliding metal-on-metal bearings like the helical coupling for dissimilar metals to be used on each surface.
The biasing device 32 may be connected with a top connector 34 and a top assembly screw 35 to the housing 30. This configuration may limit the number of housing connections and may allow the housing 30 to be constructed with robust connections that are important when considering the bending moments that the housing 30 may carry while rotating in high doglegs (bends) in the wellbore 7, which otherwise lead to fatigue. In this embodiment there are no bearings connecting the biasing device 32 to the male portion 50 or the top connector 34. The biasing device 32 may accommodate both axial and rotational movement as defined by the helical coupling while creating reactive axial and torsional forces. This embodiment may be advantageous because the combined loading of the biasing device 32 may further reduce friction losses through the helical coupling. The combined loading of the biasing device 32 may align the biasing device reaction force with the direction of travel in the helical coupling which may reduce side loading and friction within the helical coupling. Additionally, this embodiment may not require additional bearings or splines, which have the potential to bind or seize and add friction and complexity to the regulating device 20.
The helical coupling may be assembled in a manner where the neutral position (which may be defined as the position without external loads being applied), is between the fully extended position and the fully contracted position. The coupling may be free to move either direction (extension or contraction). During use it would be typical for the regulating device 20 to be in an extended position while tripping due to hanging weight from components below the regulating device 20, and further extended while circulating off-bottom due to pump open forces that occur because the fluid pressure is higher inside the tool than outside. The regulating device 20 may be designed to only extend to the fully extended position and shoulder during non-routine operations for example when components below the regulating device 20 become stuck.
In the figures shown the seal assemblies 33 may be disposed in grooves in the female component or housing 30. Such may provide reliability, lower friction, and lower cost. Alternatively, seals may be disposed in grooves in the male component or portion 50, for example if such better suits assembly requirements.
Seal assemblies 33 may not be required, and an alternative embodiment may use the drilling fluid to lubricate the helical coupling. In a “mud lube” configuration the seal assemblies 33 may be replaced by flow restrictors that limit the amount of drilling fluid that leaks out through the tool to a small fraction of the total flow. A flow restrictor may be a low clearance mating between female and male portions with a wear and erosion resistant surface that limits the flow rate of the drilling fluid that leaks past the flow restrictor. The drilling mud that leaks past the flow restrictor may provide essential cooling and cleaning of the helical coupling. A drawback of a mud lubricated helical coupling is higher wear rates on the helix surfaces, and higher friction coefficients caused by solid particles within the drilling fluid. The regulating device 20 is shown in the neutral position between fully extended and fully contracted positions. There may be more available distance to be travelled before fully contracting the tool onto the contracted shoulder 41 as compared to the available distance to be travelled before fully extending the tool onto the extension shoulder 43.
The outer torsional spring shown in
The inner sleeve 53′ may only carry a tensile load over the second element of the biasing device. While it is not shown in this drawing, an inner sleeve may extend through a portion or all of the primary element of the biasing device also. Bi-directional thrust bearings are not shown in this figure, but may be disposed at a number of locations at either end of the secondary element of the biasing device 32, within the secondary element 39, or between the primary and secondary elements of the biasing device.
Some features are mentioned in mutually different dependent claims and some combination of these features may be used with advantage.
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2021/050158 | 2/12/2021 | WO |
