DEPTH ACTIVATED DOWNHOLE ADJUSTABLE BEND ASSEMBLIES

A downhole mud motor includes a driveshaft rotatably disposed in a driveshaft housing, a bearing mandrel coupled to the driveshaft, wherein the bend adjustment assembly includes a first configuration that provides a first deflection angle between the driveshaft housing and the bearing mandrel, wherein the bend adjustment assembly includes a second configuration that provides a second deflection angle between the driveshaft housing and the bearing mandrel, and a locking assembly including a locked configuration configured to lock the bend adjustment assembly into one of the first configuration and the second configuration until the downhole mud motor has at least one of reached a predefined depth in the wellbore, and a mud weight has reached a predefined mud weight threshold at a given depth, in response to which the locking assembly is configured to actuate from the locked configuration to an unlocked configuration.

Not applicable.

BACKGROUND

In drilling a wellbore into an earthen formation, such as for the recovery of hydrocarbons or minerals from a subsurface formation, it is typical practice to connect a drill bit onto the lower end of a drillstring formed from a plurality of pipe joints connected together end-to-end, and then rotate the drillstring so that the drill bit progresses downward into the earth to create a wellbore along a predetermined trajectory. In addition to pipe joints, the drillstring typically includes heavier tubular members known as drill collars positioned between the pipe joints and the drill bit. The drill collars increase the weight applied to the drill bit to enhance its operational effectiveness. Other accessories commonly incorporated into drillstrings include stabilizers to assist in maintaining the desired direction of the drilled wellbore, and reamers to ensure that the drilled wellbore is maintained at a desired gauge (i.e., diameter).

In some applications, horizontal and other non-vertical or deviated wellbores are drilled (i.e., “directional drilling”) to facilitate greater exposure to and production from larger regions of subsurface hydrocarbon-bearing formations than would be possible using only vertical wellbores. In directional drilling, specialized drillstring components and “bottomhole assemblies” (BHAs) may be used to induce, monitor, and control deviations in the path of the drill bit, so as to produce a wellbore of the desired deviated configuration. Directional drilling may be carried out using a downhole or mud motor provided in the BHA at the lower end of the drillstring immediately above the drill bit. Downhole mud motors may include several components, such as, for example (in order, starting from the top of the motor): (1) a power section including a stator and a rotor rotatably disposed in the stator; (2) a driveshaft assembly including a driveshaft disposed within a housing, with the upper end of the driveshaft being coupled to the lower end of the rotor; and (3) a bearing assembly positioned between the driveshaft assembly and the drill bit for supporting radial and thrust loads. For directional drilling, the motor may include a bent housing to provide an angle of deflection between the drill bit and the BHA.

SUMMARY

An embodiment of a downhole mud motor positionable in a wellbore comprises a driveshaft housing, a driveshaft rotatably disposed in the driveshaft housing, a bearing mandrel coupled to the driveshaft, wherein the bend adjustment assembly includes a first configuration that provides a first deflection angle between a longitudinal axis of the driveshaft housing and a longitudinal axis of the bearing mandrel, wherein the bend adjustment assembly includes a second configuration that provides a second deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel that is different from the first deflection angle, and wherein the bend adjustment assembly is configured to shift between the first configuration and the second configuration when positioned in the wellbore, and a locking assembly comprising a locked configuration configured to lock the bend adjustment assembly into one of the first configuration and the second configuration until the downhole mud motor has at least one of reached a predefined depth in the wellbore, and a mud weight has reached a predefined mud weight threshold at a given depth, in response to which the locking assembly is configured to actuate from the locked configuration to an unlocked configuration. In some embodiments, the locking assembly comprises a rupture disk configured to burst at a predefined pressure. In some embodiments, the locking assembly comprises a locking sleeve including a locked position and an unlocked position longitudinally spaced from the locked position, and wherein the locking sleeve is configured to shift from the locked position to the unlocked position in response to bursting of the rupture disk. In certain embodiments, the bend adjustment assembly comprises an offset housing and an adjustment mandrel having a first relative angular orientation associated with the first configuration and a second relative angular orientation associated with the second configuration. In certain embodiment, the locking assembly comprises a locking piston configured to lock the offset housing and the adjustment mandrel in the first relative angular orientation when in a first position. In some embodiments, the locking assembly comprises a first locking pin configured to lock the locking piston in the first position. In some embodiments, the locking assembly comprises a second locking pin configured to lock the locking piston in a second position configured to lock the offset housing and the adjustment mandrel in the second relative angular orientation. In certain embodiments, the adjustment mandrel and offset housing comprise interlocking castellations configured to lock the offset housing and adjustment mandrel in the first relative angular orientation. In certain embodiments, the adjustment mandrel has a first axial position wherein the interlocking castellations between the adjustment mandrel and offset housing are matingly engaged, and a second axial position wherein the interlocking castellations between the adjustment mandrel and offset housing are disengaged, and the adjustment mandrel shifts from the first axial position to the second axial position in response to the locking sleeve shifting from the locked to the unlocked position. In some embodiments, the adjustment mandrel is held in the first axial position by a shear pin, the locking assembly comprises a first locking pin configured to hold the locking piston axially separated from the adjustment mandrel when the locking sleeve is in the locked position, the locking pin is configured to release the locking piston into contact with the adjustment mandrel when the locking sleeve is in the unlocked position, and the locking piston is configured to apply force to the adjustment mandrel to fracture the shear pin and permit the adjustment mandrel to shift from the first axial position to the second axial position. In certain embodiments, the bend adjustment assembly can shift between the first relative angular orientation and second relative angular orientation when the adjustment mandrel has shifted into the second axial position. In certain embodiments, the locking assembly comprises a second locking pin configured to lock the locking piston in a second position configured to lock the offset housing and the adjustment mandrel in the second relative angular orientation.

In some embodiments, the offset housing and the adjustment mandrel can shift between the first relative angular orientation and the second relative angular orientation up to an unlimited number of times. In some embodiments, the offset housing and the adjustment mandrel can shift between the second relative angular orientation and a third relative angular orientation up to an unlimited number of times.

In some embodiments, the offset housing and adjustment mandrel have a third relative angular orientation associated with a third configuration. In certain embodiments, the second deflection angle is larger than the first deflection angle. In certain embodiments, the second deflection angle is less than the first deflection angle. In some embodiments, the actuator assembly is configured to shift the bend adjustment assembly between the first configuration and the second configuration in response to a change in at least one of flowrate of a drilling fluid supplied to the downhole mud motor, pressure of the drilling fluid supplied to the downhole mud motor, and relative rotation between the driveshaft housing and the bearing mandrel. In some embodiments, the bend adjustment assembly includes a third configuration providing a third deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel that is different from at least one of the first deflection angle and the second deflection angle.

An embodiment of a downhole mud motor positionable in a wellbore comprises a driveshaft housing, a driveshaft rotatably disposed in the driveshaft housing, a bearing mandrel coupled to the driveshaft, wherein the bend adjustment assembly includes a first configuration that provides a first deflection angle between a longitudinal axis of the driveshaft housing and a longitudinal axis of the bearing mandrel, wherein the bend adjustment assembly includes a second configuration that provides a second deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel that is different from the first deflection angle, an actuator assembly configured to shift the bend adjustment assembly between the first configuration and the second configuration when the mud motor is disposed in the wellbore, and a locking assembly configured to prevent the actuator assembly from shifting the bend adjustment assembly between the first configuration and the second configuration until the mud motor has at least one of reached a predefined depth in the wellbore, and a mud weight has reached a predefined mud weight threshold at a given depth. In some embodiments, the locking assembly comprises a rupture disk configured to burst at a predefined pressure. In some embodiments, the locking assembly comprises a locking sleeve including a locked position and an unlocked position longitudinally spaced from the locked position, and wherein the locking sleeve is configured to shift from the locked position to the unlocked position in response to bursting of the rupture disk. In certain embodiments, the bend adjustment assembly comprises an offset housing and an adjustment mandrel having a first relative angular orientation associated with the first configuration and a second relative angular orientation associated with the second configuration, and the locking assembly comprises a locking piston configured to lock the offset housing and the adjustment mandrel in the first relative angular orientation when in a first position. In certain embodiments, the locking assembly comprises a first locking pin configured to lock the locking piston in the first position. In some embodiments, the locking assembly comprises a second locking pin configured to lock the locking piston in a second position configured to lock the offset housing and the adjustment mandrel in the second relative angular orientation. In some embodiments, the actuator assembly is configured to shift the bend adjustment assembly between the first configuration and the second configuration in response to a change in at least one of flowrate of a drilling fluid supplied to the downhole mud motor, pressure of the drilling fluid supplied to the downhole mud motor, and relative rotation between the driveshaft housing and the bearing mandrel. In certain embodiments, the bend adjustment assembly includes a third configuration providing a third deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel that is different from at least one of the first deflection angle and the second deflection angle.

An embodiment of a method for forming a deviated wellbore using a downhole mud motor comprises (a) positioning a bend adjustment assembly of the downhole mud motor in the wellbore in a first configuration that provides a first deflection angle between a longitudinal axis of a driveshaft housing of the downhole mud motor and a longitudinal axis of a bearing mandrel of the downhole mud motor, (b) locking the bend adjustment assembly into the first configuration with a locking assembly of the bend adjustment assembly that is disposed in a locked configuration, (c) automatically shifting the locking assembly from the locked configuration to an unlocked configuration upon at least one of the mud motor reaching a predefined depth in the wellbore, and a mud weight has reached a predefined mud weight threshold at a given depth, and (d) with the downhole mud motor positioned in the wellbore and the locking assembly in the unlocked configuration, shifting the bend adjustment assembly from the first configuration to a second configuration that provides a second deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel, the second deflection angle being different from the first deflection angle. In some embodiments, (c) comprises (c1) bursting a rupture disk of the locking assembly, and (c2) longitudinally shifting a locking sleeve of the locking assembly from a locked position to an unlocked position. In some embodiments, (c) comprises (c3) laterally shifting a locking pin from a first lateral position to a second lateral position in response to longitudinally shifting the locking sleeve to the unlocked position. In certain embodiments, (c) comprises (c4) shifting a locking piston of the locking assembly from a locked position to an unlocked position in response to laterally shifting the locking pin to the unlocked position. In certain embodiments, (d) comprises (d1) pumping drilling fluid into the wellbore from the surface pump at a reduced flowrate that is less than the drilling flowrate for a first time period, and (d2) following the first time period, pumping drilling fluid in the wellbore from the surface pump at an increased flowrate that is different than the reduced flowrate for a second time period. In some embodiments, the method comprises (e) with the downhole mud motor positioned in the wellbore and the locking assembly in the unlocked configuration, shifting the bend adjustment assembly from the second configuration to the first configuration. In some embodiments, the method comprises (e) with the downhole mud motor positioned in the wellbore and the locking assembly in the unlocked configuration, shifting the bend adjustment assembly from the second configuration to a third configuration that provides a third deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel, the third deflection angle being different from at least one of the first deflection angle and the second deflection angle.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims is made for purposes of clarity, with “up”, “upper”, “upwardly”, “uphole”, or “upstream” meaning toward the surface of the wellbore and with “down”, “lower”, “downwardly”, “downhole”, or “downstream” meaning toward the terminal end of the wellbore, regardless of the wellbore orientation.

As described above, downhole mud motors may include a bent housing for providing a deflection angle between the drill bit and the BHA. Conventionally, bent housings either provide a fixed deflection angle or an adjustable deflection angle that may only be adjustable at the surface. However, it may be desirable to adjust a deflection angle of the bent housing without needing to go through the lengthy process of pulling the BHA out of the wellbore so that the deflection angle may be adjusted.

Accordingly, embodiments of downhole-adjustable bend adjustment assemblies of downhole mud motors are described herein which may be adjusted in situ within the wellbore without needing to retrieve the downhole mud motor to the surface. Additionally, bend adjustment assemblies described herein include a locking assembly which only permits the bend adjustment assembly to adjust the deflection angle provided by the bend adjustment assembly once the downhole mud motor had reached a predefined depth in the wellbore. In this manner, the mud motor may be operated as desired (e.g., at different fluid flowrates, while providing rotation to the mud motor from the surface, etc.) without inadvertently actuating the bend adjustment assembly when it is not desired to do so. Additionally, locking assemblies of the bend adjustment assemblies described herein are configured to actuate automatically in response to reaching the predefined depth in the wellbore from a locked configuration locking the bend adjustment assembly into a given configuration and an unlocked configuration in which the bend adjustment assembly is permitted to actuate between a plurality of configurations providing a plurality of different deflection angles.

Referring toFIG.1, an embodiment of a well system10is shown. Well system10is generally configured for drilling a wellbore16in an earthen formation5. In this exemplary embodiment, well system10includes a drilling rig20disposed at the surface, a drillstring21extending downhole from rig20, a bottomhole assembly (BHA)30coupled to the lower end of drillstring21, and a drill bit90attached to the lower end of BHA30. A surface or mud pump23is positioned at the surface and pumps drilling fluid or mud through drillstring21. Additionally, rig20includes a rotary system24for imparting torque to an upper end of drillstring21to thereby rotate drillstring21in wellbore16. In this exemplary embodiment, rotary system24comprises a rotary table located at a rig floor of rig20; however, in other embodiments, rotary system24may comprise other systems for imparting rotary motion to drillstring21, such as a top drive. A downhole mud motor35is provided in BHA30for facilitating the drilling of deviated portions of wellbore16. Moving downward along BHA30, motor35includes a hydraulic drive or power section40, a driveshaft assembly100, and a bearing assembly200. In some embodiments, the portion of BHA30disposed between drillstring21and motor35can include other components, such as drill collars, measurement-while-drilling (MWD) tools, reamers, stabilizers and the like.

Power section40of BHA30converts the fluid pressure of the drilling fluid pumped downward through drillstring21into rotational torque for driving the rotation of drill bit90. Driveshaft assembly100and bearing assembly200transfer the torque generated in power section40to bit90. With force or weight applied to the drill bit90, also referred to as weight-on-bit (“WOB”), the rotating drill bit90engages the earthen formation and proceeds to form wellbore16along a predetermined path toward a target zone. The drilling fluid or mud pumped down the drillstring21and through BHA30passes out of the face of drill bit90and back up the annulus18formed between drillstring21and the wall19of wellbore16. The drilling fluid cools the bit90, and flushes the cuttings away from the face of bit90and carries the cuttings to the surface.

Referring toFIGS.1-3, an embodiment of the power section40of BHA30is shown schematically inFIGS.2and3. In this exemplary embodiment, power section40comprises a helical-shaped rotor50disposed within a stator60comprising a cylindrical stator housing65lined with a helical-shaped elastomeric insert61. Helical-shaped rotor50defines a set of rotor lobes57that intermesh with a set of stator lobes67defined by the helical-shaped insert61. As best shown inFIG.3, the rotor50has one fewer lobe57than the stator60. When the rotor50and the stator60are assembled, a series of cavities70are formed between the outer surface53of the rotor50and the inner surface63of the stator60. Each cavity70is sealed from adjacent cavities70by seals formed along the contact lines between the rotor50and the stator60. The central axis58of the rotor50is radially offset from the central axis68of the stator60by a fixed value known as the “eccentricity” of the rotor-stator assembly. Consequently, rotor50may be described as rotating eccentrically within stator60.

During operation of the power section40, fluid is pumped under pressure into one end of the power section40where it fills a first set of open cavities70. A pressure differential across the adjacent cavities70forces the rotor50to rotate relative to the stator60. As the rotor50rotates inside the stator60, adjacent cavities70are opened and filled with fluid. As this rotation and filling process repeats in a continuous manner, the fluid flows progressively down the length of power section40and continues to drive the rotation of the rotor50. Driveshaft assembly100shown inFIG.1includes a driveshaft discussed in more detail below that has an upper end coupled to the lower end of rotor50. In this arrangement, the rotational motion and torque of rotor50is transferred to drill bit90via driveshaft assembly100and bearing assembly200.

In this exemplary embodiment, driveshaft assembly100is coupled to bearing assembly200via a bend adjustment assembly300of BHA30that provides an adjustable bend301along motor35. Due to bend301, a deflection angle θ is formed between a central or longitudinal axis95(shown inFIG.1) of drill bit90and the longitudinal axis25of drillstring21. To drill a straight section of wellbore16, drillstring21is rotated from rig20with a rotary table or top drive to rotate BHA30and drill bit90coupled thereto. Drillstring21and BHA30rotate about the longitudinal axis of drillstring21, and thus, drill bit90is also forced to rotate about the longitudinal axis of drillstring21. With bit90disposed at deflection angle θ, the lower end of drill bit90distal BHA30seeks to move in an arc about longitudinal axis25of drillstring21as it rotates, but is restricted by the sidewall19of wellbore16, thereby imposing bending moments and associated stress on BHA30and mud motor35.

In general, driveshaft assembly100functions to transfer torque from the eccentrically-rotating rotor50of power section40to a concentrically-rotating bearing mandrel220of bearing assembly200and drill bit90. As best shown inFIG.3, rotor50rotates about rotor axis58in the direction of arrow54, and rotor axis58rotates about stator axis68in the direction of arrow55. However, drill bit90and bearing mandrel220are coaxially aligned and rotate about a common axis that is offset and/or oriented at an acute angle relative to rotor axis58. Thus, driveshaft assembly100converts the eccentric rotation of rotor50to the concentric rotation of bearing mandrel220and drill bit90, which are radially offset and/or angularly skewed relative to rotor axis58.

Referring toFIGS.4-7, embodiments of driveshaft assembly100, bearing assembly200, and bend adjustment assembly300are shown. In this exemplary embodiment, driveshaft assembly100includes an outer or driveshaft housing110and a one-piece (i.e., unitary) driveshaft120rotatably disposed within housing110. Housing110has a linear central or longitudinal axis115, a first or upper end111, a second or lower end113coupled to an outer or bearing housing210of bearing assembly200via bend adjustment assembly300, and a central bore or passage112extending between ends111and113. Particularly, an externally threaded connector or pin end of driveshaft housing110located at upper end111threadably engages a mating internally threaded connector or box end disposed at the lower end of stator housing65, and an internally threaded connector or box end of driveshaft housing110located at lower end113threadably engages a mating externally threaded connector of bend adjustment assembly300. Additionally, in this exemplary embodiment, driveshaft housing includes ports114that extend radially between the inner and outer surfaces of driveshaft housing110.

In this exemplary embodiment, driveshaft housing110is coaxially aligned with stator housing65. As will be discussed further herein, bend adjustment assembly300is configured to actuate between a first configuration303(shown inFIGS.4,5), and a second configuration305(shown inFIG.21). In this exemplary embodiment, when bend adjustment assembly300is in the first configuration303, driveshaft housing110is not disposed at an angle relative to bearing assembly200and drill bit90. However, when bend adjustment assembly is disposed in the second configuration305, bend301is formed between driveshaft assembly100and bearing assembly200, orienting driveshaft housing110at deflection angle θ relative to bearing assembly200and drill bit90. Additionally, as will be discussed further herein, bend adjustment assembly300is configured to actuate between the first and second configurations303and305in-situ with BHA30disposed in wellbore16.

Driveshaft120of driveshaft assembly100has a linear central or longitudinal axis, a first or upper end121, and a second or lower end123opposite end121. Upper end121is pivotally coupled to the lower end of rotor50with a driveshaft adapter130and a first or upper universal joint141, and lower end123is pivotally coupled to an upper end221of bearing mandrel220with a second or lower universal joint143. In this exemplary embodiment, upper end121of driveshaft120and upper universal joint141are disposed within driveshaft adapter130, whereas lower end123of driveshaft120comprises an axially extending counterbore or receptacle that receives upper end221of bearing mandrel220and lower universal joint143. In this exemplary embodiment, driveshaft120includes a radially outwards extending shoulder122located proximal lower end123.

In this exemplary embodiment, driveshaft adapter130extends along a central or longitudinal axis135between a first or upper end coupled to rotor50, and a second or lower end coupled to the upper end121of driveshaft120. In this exemplary embodiment, the upper end of driveshaft adapter130comprises an externally threaded male pin or pin end that threadably engages a mating female box or box end at the lower end of rotor50. A receptacle or counterbore extends axially (relative to axis135) from the lower end of adapter130. The upper end121of driveshaft120is disposed within the counterbore of driveshaft adapter130and pivotally couples to adapter130via the upper universal joint141disposed within the counterbore of driveshaft adapter130.

Universal joints141and143allow ends121and123of driveshaft120to pivot relative to adapter130and bearing mandrel220, respectively, while transmitting rotational torque between rotor50and bearing mandrel220. Driveshaft adapter130is coaxially aligned with rotor50. Since rotor axis58is radially offset and/or oriented at an acute angle relative to the central axis of bearing mandrel220, the central axis of driveshaft120is skewed or oriented at an acute angle relative to axis115of housing110, axis58of rotor50, and a central or longitudinal axis225of bearing mandrel220. However, universal joints141and143accommodate for the angularly skewed driveshaft120, while simultaneously permitting rotation of the driveshaft120within driveshaft housing110.

In general, each universal joint (e.g., each universal joint141and143) may comprise any joint or coupling that allows two parts that are coupled together and not coaxially aligned with each other (e.g., driveshaft120and adapter130oriented at an acute angle relative to each other) limited freedom of movement in any direction while transmitting rotary motion and torque including, without limitation, universal joints (Cardan joints, Hardy-Spicer joints, Hooke joints, etc.), constant velocity joints, or any other custom designed joint. In other embodiments, driveshaft assembly100may include a flexible shaft comprising a flexible material (e.g., Titanium, etc.) that is directly coupled (e.g., threadably coupled) to rotor50of power section40in lieu of driveshaft120, where physical deflection of the flexible shaft (the flexible shaft may have a greater length relative driveshaft120) accommodates axial misalignment between driveshaft assembly100and bearing assembly200while allowing for the transfer of torque therebetween.

As previously described, adapter130couples driveshaft120to the lower end of rotor50. During drilling operations, high pressure drilling fluid or mud is pumped under pressure down drillstring21and through cavities70between rotor50and stator60, causing rotor50to rotate relative to stator60. Rotation of rotor50drives the rotation of driveshaft adapter130, driveshaft120, bearing assembly mandrel220, and drill bit90. The drilling fluid flowing down drillstring21through power section40also flows through driveshaft assembly100and bearing assembly200to drill bit90, where the drilling fluid flows through nozzles in the face of bit90into annulus18. Within driveshaft assembly100and the upper portion of bearing assembly200, the drilling fluid flows through an annulus116formed between driveshaft housing110and driveshaft120.

Still referring toFIGS.4-7, bearing assembly200includes bearing housing210and one-piece (i.e., unitary) bearing mandrel220rotatably disposed within housing210. Bearing housing210has a linear central or longitudinal axis disposed coaxial with central axis225of mandrel220, a first or upper end211coupled to lower end113of driveshaft housing110via bend adjustment assembly300, a second or lower end213, and a central through bore or passage extending axially between ends211and213. Particularly, the upper end211comprises an externally threaded connector or pin end coupled with bend adjustment assembly300. Bearing housing210is coaxially aligned with bit90, however, due to bend301between driveshaft assembly100and bearing assembly200, bearing housing210is oriented at deflection angle θ relative to driveshaft housing110. In this exemplary embodiment, bearing housing210comprises a plurality of separate tubular housings connected end-to-end; however, it may be understood that in other embodiments, bearing housing210may comprise a single, integrally or monolithically formed housing.

In this exemplary embodiment, bearing mandrel220of bearing assembly200has a first or upper end221, a second or lower end223, and a central through passage222extending axially from lower end223and terminating axially below upper end221. The upper end221of bearing mandrel220is directly coupled to the lower end123of driveshaft120via lower universal joint143. In particular, upper end221is disposed within a receptacle formed in the lower end123of driveshaft120and pivotally coupled thereto with lower universal joint143. Additionally, the lower end223of mandrel220is coupled to drill bit90.

In this exemplary embodiment, bearing mandrel220includes a plurality of drilling fluid ports227extending radially from passage222to the outer surface of mandrel220, and a plurality of lubrication ports229also extending radially to the outer surface of mandrel220, where drilling fluid ports227are disposed proximal an upper end of passage222and lubrication ports229are axially spaced from drilling fluid ports227. In this arrangement, lubrication ports229are separated or sealed from passage222of bearing mandrel220and the drilling fluid flowing through passage222. Drilling fluid ports227provide fluid communication between annulus116and passage222. During drilling operations, mandrel220is rotated about axis225relative to housing210. In particular, high pressure drilling fluid is pumped through power section40to drive the rotation of rotor50, which in turn drives the rotation of driveshaft120, mandrel220, and drill bit90. The drilling mud flowing through power section40flows through annulus116, drilling fluid ports227and passage222of mandrel220in route to drill bit90.

In this exemplary embodiment, the upper end121of driveshaft120is coupled to rotor50with a driveshaft adapter130and upper universal joint141, and the lower end123of driveshaft120is coupled to the upper end221of bearing mandrel220with lower universal joint143. As shown particularly inFIG.7, bearing housing210has a central bore or passage defined by a radially inner surface212that extends between ends211and213. One or more upper annular seals214are disposed in the inner surface212of housing210proximal upper end211while a second or lower annular seal216is disposed in the inner surface212proximal lower end213. In this arrangement, an annular chamber217is formed radially between inner surface212and an outer surface of bearing mandrel220, where annular chamber217extends axially between upper seals214and lower seal216. In this exemplary embodiment, the inner surface212of bearing housing210additionally includes an annular seal215located proximal an annular shoulder218of the inner surface212. Bearing housing210further includes one or more radial ports219in this exemplary embodiment.

Additionally, in this exemplary embodiment, bearing mandrel220includes a central sleeve224disposed in passage222and coupled to an inner surface of mandrel220defining passage222. An annular piston226is slidably disposed in passage222radially between the inner surface of mandrel220and an outer surface of sleeve224, where piston226includes a first or outer annular seal that seals against the inner surface of mandrel220and a second or inner annular seal that seals against the outer surface of sleeve224. In this arrangement, chamber217extends into the annular space (via lubrication ports229) formed between the inner surface of mandrel220and the outer surface of sleeve224that is sealed from the flow of drilling fluid through passage222via the annular seals of piston226.

In this exemplary embodiment, a first or upper radial bearing230, a thrust bearing assembly232, and a second or lower radial bearing234are each disposed in chamber217. Upper radial bearing230is disposed about mandrel220and axially positioned above thrust bearing assembly232, and lower radial bearing234is disposed about mandrel220and axially positioned below thrust bearing assembly232. In general, radial bearings230,234permit rotation of mandrel220relative to housing210while simultaneously supporting radial forces therebetween. In this exemplary embodiment, upper radial bearing230and lower radial bearing234are both sleeve type bearings that slidingly engage the outer surface of mandrel220. However, in general, any suitable type of radial bearing(s) may be employed including, without limitation, needle-type roller bearings, radial ball bearings, PDC Diamond tiled bearings, and/or combinations thereof.

Annular thrust bearing assembly232is disposed about mandrel220and permits rotation of mandrel220relative to housing210while simultaneously supporting axial loads in both directions (e.g., off-bottom and on-bottom axial loads). In this exemplary embodiment, thrust bearing assembly232generally comprises a pair of caged roller bearings and corresponding races, with the central race coupled to bearing mandrel220. In other embodiments, one or more other types of thrust bearings may be included in bearing assembly200, including ball bearings, planar bearings, PDC Diamond insert bearings etc. In still other embodiments, the thrust bearing assemblies of bearing assembly200may be disposed in the same or different thrust bearing chambers (e.g., two-shoulder or four-shoulder thrust bearing chambers). In this exemplary embodiment, radial bearings230,234and thrust bearing assembly232are oil-sealed bearings. Particularly, chamber217comprises an oil or lubricant filled chamber that is pressure compensated via piston226. In other words, piston226equalizes the fluid pressure within chamber217with the pressure of drilling fluid flowing through passage222of mandrel220towards drill bit90. As previously described, in this exemplary embodiment, bearings230,232,234are oil-sealed. However, in other embodiments, the bearings of the bearing assembly (e.g., bearing assembly200) are mud lubricated.

Referring still toFIGS.4-7, as previously described, bend adjustment assembly300couples driveshaft housing110to bearing housing210, and introduces bend301and deflection angle θ along motor35. Central axis115of driveshaft housing110is coaxially aligned with axis25, and central axis225of bearing mandrel220is coaxially aligned with axis95, thus, deflection angle θ also represents the angle between axes115,225when mud motor35is in an undeflected state (e.g., outside wellbore16). Bend adjustment assembly300is configured to adjust the deflection angle θ between a first predetermined deflection angle θ1and a second predetermined deflection angle θ2, different from the first deflection angle θ1, with drillstring21and BHA30in-situ disposed in wellbore16. In other words, bend adjustment assembly300is configured to adjust the amount of bend301without needing to pull drillstring21from wellbore16to adjust bend adjustment assembly300at the surface, thereby reducing the amount of time required to drill wellbore16. In this exemplary embodiment, first predetermined deflection angle θ1is substantially equal to 0° while second deflection angle θ2is an angle greater than 0°, such as an angle between 0°-5°; however, in other embodiments, first deflection angle θ1may be greater than 0°, as will be discussed further herein.

In this exemplary embodiment, bend adjustment assembly300generally includes a first or upper housing310, a second or lower housing320, a piston mandrel350, a first or upper adjustment mandrel360, a second or lower adjustment mandrel370, and a locking assembly400. Additionally, in this exemplary embodiment, bend adjustment assembly300includes an actuator assembly450housed in bearing housing210, where actuator assembly450is generally configured to control the actuation of bend adjustment assembly between the first deflection angle θ1and the second deflection angle θ2with BHA30disposed in wellbore16. Upper housing310and lower housing320may be referred to at times as offset housings310,320. Additionally, in this exemplary embodiment, upper housing310comprises a plurality of tubular housings connected end-to-end; however, it may be understood that in other embodiments, upper housing310may comprise a singular integrally or monolithically formed housing.

Referring now toFIGS.5,6, and8-11, components of the bend adjustment assembly300are shown. As shown particularly inFIG.6, upper housing310is generally tubular and has a first or upper end311, a second or lower end313, and a central bore or passage defined by a generally cylindrical inner surface312extending between ends311and313. The inner surface312of upper housing310includes an engagement surface314extending from upper end311and a threaded connector316extending from lower end313. An annular seal318is disposed radially between engagement surface314of upper housing310and an outer surface of upper adjustment mandrel to seal the annular interface formed therebetween.

Lower housing320of bend adjustment assembly300is generally tubular and has a first or upper end319, a second or lower end321, and a generally cylindrical inner surface322extending between ends319and321. A generally cylindrical outer surface of lower housing320includes a threaded connector coupled to the threaded connector316of upper housing310. The inner surface322of lower housing320includes an offset engagement surface323extending from upper end319to an internal shoulder327S, and a threaded connector324extending from lower end321. In this exemplary embodiment, offset engagement surface323defines an offset bore or passage327that extends between upper end319and internal shoulder327S of lower housing320.

Additionally, lower housing320includes a central bore or passage329extending between lower end321and internal shoulder327S, where central bore329has a central axis disposed at an angle relative to a central axis of offset bore327. In other words, offset engagement surface323has a central or longitudinal axis that is offset or disposed at an angle relative to a central or longitudinal axis of lower housing320. Thus, in this exemplary embodiment, the offset or angle formed between central bore329and offset bore327of lower housing320facilitates the formation of bend301described above. In this exemplary embodiment, the inner surface322of lower housing320additionally includes a first or upper annular shoulder325, and a second or lower annular shoulder326. Additionally, inner surface322of lower housing320includes a pair of circumferentially spaced slots331, where slots331extend axially into lower housing320from upper shoulder325.

In this exemplary embodiment, lower housing320of bend adjustment assembly300includes an arcuate lip or extension328at upper end319. Particularly, extension328extends arcuately between a pair of axially extending shoulders328S. In this exemplary embodiment, extension328extends less than 180° about the central axis of lower housing320; however, in other embodiments, the arcuate length or extension of extension328may vary. Additionally, in this exemplary embodiment, a plurality of circumferentially spaced teeth or castellations333are formed on the extension328. Further, in this exemplary embodiment, lower housing320includes a plurality of circumferentially spaced and axially extending ports330. Particularly, ports330extend axially between lower shoulder326and an arcuate shoulder332from which extension328extends. As will be discussed further herein, ports330of lower housing320provide fluid communication through a generally annular compensation or locking chamber395of bend adjustment assembly300.

As shown particularly inFIG.5, piston mandrel350of bend adjustment assembly300is generally tubular and has a first or upper end351, a second or lower end353, and a central bore or passage extending between ends351and353. Additionally, in this exemplary embodiment, piston mandrel350includes a generally an annular seal352positioned on an outer surface thereof proximal upper end351and which sealingly engages the inner surface of driveshaft housing110. Further, piston mandrel350includes an annular shoulder located proximal upper end351that physically engages or contacts an annular biasing member354extending about the outer surface of piston mandrel350. In this exemplary embodiment, an annular compensating piston356is slidably disposed about the outer surface of piston mandrel350. In some embodiments, compensating piston356may include a pair of annular seals which sealingly engage the inner surface of driveshaft housing110and the outer surface of piston mandrel350.

The upper adjustment mandrel360of bend adjustment assembly300is generally tubular and has a first or upper end361, a second or lower end363, and a central bore or passage defined by a generally cylindrical inner surface extending between ends361and363. In this exemplary embodiment, the inner surface of upper adjustment mandrel360includes an annular recess extending axially into mandrel360from upper end361, and an annular seal362axially spaced from recess361and which sealingly engages the outer surface of piston mandrel350. Adjustment mandrel360is connected with piston mandrel350to restrict relative movement therebetween. In this exemplary embodiment, an outer seal of compensating piston356sealingly engages the inner surface of upper adjustment mandrel360, restricting fluid communication between locking chamber395and a generally annular compensating chamber359formed about piston mandrel350and extending axially between seal352of piston mandrel350and outer seal of compensating piston356. In this configuration, compensating chamber359is in fluid communication with the surrounding environment (e.g., wellbore16) via ports114in driveshaft housing110.

In this exemplary embodiment, upper adjustment mandrel360includes a generally cylindrical outer surface comprising a first or upper threaded connector, an offset engagement surface365, and a second or lower threaded connector. The upper threaded connector of upper adjustment mandrel360extends from upper end361and couples to a threaded connector disposed on the inner surface of driveshaft housing110at lower end113. Offset engagement surface365has a central or longitudinal axis that is offset from or disposed at an angle relative to a central or longitudinal axis of upper adjustment mandrel360. Offset engagement surface365matingly engages the engagement surface314of upper housing310, as will be described further herein. In this exemplary embodiment, relative rotation is permitted between upper housing310and upper adjustment mandrel360while relative axial movement is restricted between housing310and mandrel360. Adjustment mandrel360is connected with lower adjustment mandrel370to restrict relative movement therebetween. Further, the outer surface of upper offset mandrel360proximal the lower end363thereof includes an annular seal366located proximal lower end363that sealingly engages lower adjustment mandrel370.

Referring still toFIGS.5,6, and8-10, lower adjustment mandrel370of bend adjustment assembly300is generally tubular and has a first or upper end371, a second or lower end373, and a central bore or passage extending therebetween that is defined by a generally cylindrical inner surface. In this exemplary embodiment, the inner surface of lower adjustment mandrel370includes axial slots which engage axial splines of upper adjustment mandrel360. Additionally, in this exemplary embodiment, lower adjustment mandrel370includes a generally cylindrical outer surface comprising an offset engagement surface372. Offset engagement surface372has a central or longitudinal axis that is offset or disposed at an angle relative to a central or longitudinal axis of the upper end361of upper adjustment mandrel360and the lower end321of lower housing320, where offset engagement surface372is disposed directly adjacent or overlaps the offset engagement surface323of lower housing320. When bend adjustment assembly300is disposed in the first configuration303, a first deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360, and when bend adjustment assembly300is disposed in the second configuration305, a second deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360that is different from the first deflection angle.

In this exemplary embodiment, an annular seal374is disposed in the outer surface of lower adjustment mandrel370to sealingly engage the inner surface of lower housing320. In this exemplary embodiment, a recess379is formed on the outer surface of lower adjustment mandrel370which extends arcuately between a pair of circumferentially spaced shoulders375. Additionally, a plurality of circumferentially spaced teeth or castellations376are formed in the arcuate recess379between shoulders375. In this exemplary embodiment, lower adjustment mandrel370further includes a pair of circumferentially spaced first or short slots377and a pair of circumferentially spaced second or long slots378. Both the short slots377and long slots378of lower adjustment mandrel370extend axially into lower adjustment mandrel370from the lower end373thereof. In this exemplary embodiment, each short slot377is circumferentially spaced approximately 180° apart. Similarly, in this exemplary embodiment, each long slot378is circumferentially spaced approximately 180° apart.

FIG.10illustrates the short slots377and long slots378directly adjacent each with no rib of material or other obstruction interposed therebetween thereby permitting a single shift from the first configuration303to the second configuration305of bend adjustment assembly300. However, it may be understood that other applications may require multiple shifts during the run, as will be described further herein with respect toFIG.11, which permits the use of a lower adjustment mandrel390with slots377and378circumferentially spaced such that a rib of material is present between the adjacent slots of the lower adjustment mandrel.

In this exemplary embodiment, lower adjustment mandrel370is initially coupled to upper adjustment mandrel360by a shear member or pin380positioned radially therebetween which restricts relative axial movement between adjustment mandrels360,370. As will be described further herein, shear pin380may be sheared during the operation of bend adjustment assembly300to permit relative axial movement between adjustment mandrels360,370. Additionally, one or more splines or keys are positioned radially between adjustment mandrels360,370to restrict relative rotation therebetween.

Referring now toFIG.11, another embodiment of a lower adjustment mandrel390is shown. It may be understood that in some embodiments lower adjustment mandrel390may be used in the bend adjustment assembly300(and other bend adjustment assemblies which vary in configuration from bend adjustment assembly300) in lieu of the lower adjustment mandrel370shown inFIG.10.

In this exemplary embodiment, lower adjustment mandrel390has a first or upper end391, a second or lower end393, and a central bore or passage extending therebetween that is defined by a generally cylindrical inner surface. Additionally, in this exemplary embodiment, lower adjustment mandrel390includes a generally cylindrical outer surface comprising an offset engagement surface392which has a central or longitudinal axis that is offset or disposed at an angle relative to a central or longitudinal axis of the upper end361of upper adjustment mandrel360and the lower end321of lower housing320.

In this exemplary embodiment, an annular seal394is disposed in the outer surface of lower adjustment mandrel390to sealingly engage the inner surface of lower housing320. Additionally, a recess399is formed on the outer surface of lower adjustment mandrel390which extends arcuately between a pair of circumferentially spaced shoulders395. A plurality of circumferentially spaced teeth or castellations396are formed in the arcuate recess399between shoulders395. Lower adjustment mandrel390further includes a pair of circumferentially spaced first or short slots397and a pair of circumferentially spaced second or long slots398. Both the short slots397and long slots398of lower adjustment mandrel390extend axially into lower adjustment mandrel390from the lower end393thereof. In this exemplary embodiment, each short slot397is circumferentially spaced approximately 180° apart. Similarly, each long slot398is circumferentially spaced approximately 180° apart.

Referring now toFIGS.5,6, and12-19, as will be described further herein, locking assembly400prevents bend adjustment assembly from shifting from the first configuration303to the second configuration305until mud motor35has reached a predefined depth within wellbore16. In other words, prior to reaching the predefined depth, mud motor35may be operated in any manner desired by an operator of well system10without inadvertently triggering the actuation of bend adjustment assembly300from the first configuration303to the second configuration305. For example, the pumping of drilling fluid through drillstring21may be ceased without inadvertently unlocking bend adjustment assembly300from the first configuration303until the predefined depth has been achieved. Similarly, drilling fluid may be pumped through drillstring21at a maximum drilling pressure without inadvertently unlocking bend adjustment assembly300from the first configuration303until the predefined depth has been achieved. The maximum drilling pressure may correspond to a maximum discharge pressure of mud pump23that may be safely and practically delivered by mud pump23. To state in other words, locking assembly400allows mud motor35to be operated as if bend adjustment assembly300were not present therein until the predefined depth has been achieved.

In this exemplary embodiment, locking assembly400generally includes a locking piston402, a locking sleeve420, a rupture disk426, a first locking pin430, and a second locking pin440circumferentially spaced from the first locking pin430. Locking piston402is generally tubular and has a first or upper end401, a second or lower end403, and a central bore or passage extending therebetween. Locking piston402includes a generally cylindrical outer surface comprising an annular shoulder404positioned axially between a pair of annular seals406,408positioned on the outer surface of locking piston402.

Locking piston402additionally includes a pair of circumferentially spaced keys410that extend axially from upper end401, where each key410extends through one of the circumferentially spaced slots331of lower housing320. In this arrangement, relative rotation between locking piston402and lower housing320is restricted while relative axial movement is permitted therebetween. As will be discussed further herein, each key410is receivable in either one of the short slots377or long slots378of lower adjustment mandrel370depending on the relative angular position between locking piston402and lower adjustment mandrel370.

In this exemplary embodiment, the outer surface of locking piston402additionally includes a pair of circumferentially opposed recesses411,413formed therein. First recess411is circumferentially aligned with the first locking pin430and a first ledge412of locking piston402formed on the first recess411engages the first locking pin430as will be described further herein. Similarly, second recess413is circumferentially aligned with the second locking pin440and a second ledge414of locking piston402formed on the second recess413engages the second locking pin440as will be described further herein.

The combination of sealing engagement between seals406,408of locking piston402and the inner surface322of lower housing320defines a lower axial end of locking chamber395. Locking chamber395extends longitudinally from the lower axial end thereof to an upper axial end defined by the combination of sealing engagement between the outer seal of compensating piston356and the inner seal of piston356. Particularly, lower adjustment mandrel370and upper adjustment mandrel360each include axially extending ports similar in configuration to the ports330of lower housing320such that fluid communication is provided between the annular space directly adjacent shoulder404of locking piston402and the annular space directly adjacent a lower end of compensating piston356. Locking chamber395is sealed from annulus116such that drilling fluid flowing into annulus116is not permitted to communicate with fluid disposed in locking chamber395, where locking chamber395is filled with lubricant.

The locking sleeve420of locking assembly400is positioned about locking piston402radially between the outer surface of locking piston402and the inner surface322of lower housing320. In this exemplary embodiment, locking sleeve420includes a first or upper end421, a second or lower end423opposite upper end421, and a pair of circumferentially opposed fingers422extending from the upper end421. Fingers422are circumferentially aligned with the locking pins430,440of locking assembly400as will be described further herein. Additionally, a generally cylindrical outer surface of locking sleeve420includes an annular shoulder424formed thereon.

In this exemplary embodiment, the rupture disk426of locking assembly400is positioned in an internal fluid passage334of lower housing320which extends from a first opening formed in the internal shoulder327S to a second opening formed in the inner surface322of lower housing320. Additionally, lower housing320includes a pair of annular seals336positioned on the inner surface322of lower housing320and flanking the second opening of fluid passage334. Each of the seals336sealingly engages the outer surface of locking sleeve420such that while fluid communication between fluid passage334and the shoulder424of locking sleeve420is permitted, fluid communication between the ends421,423of locking sleeve420is restricted.

Fluid passage334may initially comprise or form an ambient chamber filled with air at ambient pressure. Rupture disk426is configured to burst or rupture in response to the mud motor35reaching the predefined depth within wellbore16, causing fluid pressure within fluid passage334to increase and equalize with the fluid pressure in the central passage of lower housing320. The increase in pressure within fluid passage334is applied to the shoulder424of locking sleeve420as will be described further herein.

In some embodiments, the rupture disk426is configured to burst in response to fluid pressure within bend adjustment assembly300reaching a pressure corresponding to the predefined depth. A static or head pressure of the drilling fluid flowing through bend adjustment assembly300increases as the depth of mud motor35within wellbore16increases. In addition to the head pressure dependent on the depth of mud motor35within wellbore16, a dynamic pressure is added to the drilling fluid by mud pump23, where the pressure of the drilling fluid flowing through bend adjustment assembly300at a given time is equal to the combined head pressure (dependent on the depth of the mud motor35) and dynamic pressure (dependent on the operation of mud pump23) of the drilling fluid. In some embodiments, the rupture disk426is configured to burst when the head pressure of the drilling fluid within bend adjustment assembly300corresponds to the predefined depth and the dynamic pressure of the drilling fluid is equal to the maximum drilling pressure delivered by mud pump23.

First locking pin430initially holds or restrains locking piston402in a first or initial axial position before mud motor35achieves the predefined depth within wellbore16. First locking pin430has a longitudinal first end431, a longitudinal second end433opposite first end431, an outer receptacle432extending longitudinally into second end433, and a slotted opening434located between ends431,433. A first biasing member436of locking assembly400biases first locking pin430in a first lateral direction435(shown inFIG.19) that extends orthogonal the central axis of lower housing320. The first locking pin430and first biasing member436are each positioned in a first lateral slot338A formed in the lower housing320of bend adjustment assembly300where both the outer receptacle432and slotted opening434of first locking pin430are positioned within the central passage of lower housing320.

Second locking pin440locks the locking piston402in a second or set axial position that is spaced from the initial axial position of locking piston402. As will be described further herein, locking piston402travels from the initial axial position to the set axial position during the actuation of bend adjustment assembly300from the first configuration303to the second configuration305once mud motor35achieves the predefined depth within wellbore16.

Similar to first locking pin430described above, second locking pin440has a longitudinal first end441, a longitudinal second end443opposite first end441, an outer receptacle442extending longitudinally into second end443, and a slotted opening444located between ends441,443. A second biasing member446of locking assembly400biases second locking pin440in a second lateral direction445(shown inFIG.19) that extends orthogonal the central axis of lower housing320and is opposite the first lateral direction435. Additionally, the second locking pin440and second biasing member446are each positioned in a second lateral slot338B formed in lower housing320where both the outer receptacle442and slotted opening444of second locking pin440are positioned within the central passage of lower housing320. In this exemplary embodiment, the location of slotted opening444is shifted closer to the second end443of second locking pin440compared to the location of slotted opening434of first locking pin430. However, in other embodiments, the configuration of locking pins430,440may vary.

In this exemplary embodiment, the first locking pin430is received in the first recess411of locking piston402while the second locking pin440is received in the second recess413of locking piston402. Particularly, when bend adjustment assembly300is in the first configuration303, the first ledge412of locking piston402is laterally offset from the slotted opening434of first locking pin430and contacts a side of the first locking pin430. Contact between the first ledge412and first locking pin402prevents locking piston402from travelling upwards from the initial axial position to the set axial position. Additionally, when bend adjustment assembly300is in the first configuration303, one of the fingers422of locking sleeve420is received in the outer receptacle432of first locking pin430, preventing first locking pin430from travelling in the first lateral direction435from a first or initial lateral position (corresponding to the first configuration303of bend adjustment assembly300) to a second or set lateral position that is spaced in the first lateral direction435from the initial lateral position.

Further, when bend adjustment assembly300is in the first configuration303, the second ledge414of locking piston402is laterally aligned with and received in the slotted opening444of second locking pin440. Additionally, when bend adjustment assembly300is in the first configuration303, the other of the fingers422of locking sleeve420is received in the outer receptacle442of second locking pin440, preventing second locking pin440from travelling in the second lateral direction445from a first or initial lateral position (corresponding to the first configuration303of bend adjustment assembly300) to a second or set lateral position that is spaced in the second lateral direction445from the initial lateral position.

Referring now toFIG.7, actuator assembly450of bend adjustment assembly300forces or causes bend adjustment assembly300to actuate from the first configuration303to the second configuration305after mud motor35has achieved the predefined depth within wellbore16. In this exemplary embodiment, actuator assembly450generally includes an actuator piston452and a torque transmitter or teeth ring470. Actuator piston452of actuator assembly450is slidably disposed about bearing mandrel220and has a first or upper end453, a second or lower end455, and a central bore or passage extending therebetween. In this exemplary embodiment, actuator piston452has a generally cylindrical outer surface including an annular shoulder454and an annular seal456located axially between shoulder454and lower end455. The outer surface of actuator piston452includes a plurality of radially outwards extending and circumferentially spaced keys received in slots of the bearing housing210to restrict relative rotation between actuator piston452and bearing housing210while permitting actuator piston452to slide axially relative bearing housing210. Additionally, in this exemplary embodiment, actuator piston452includes a plurality of circumferentially spaced locking teeth460extending axially from lower end455.

In this exemplary embodiment, seal456of actuator piston452sealingly engages the inner surface212of bearing housing210and the seal215of bearing housing210sealingly engages the outer surface of actuator piston452to form an annular, sealed compensating chamber412extending therebetween. Fluid pressure within compensating chamber412is compensated or equalized with the surrounding environment (e.g., wellbore16) via ports219of bearing housing210. Additionally, an annular biasing member462is disposed within compensating chamber412and applies a biasing force against shoulder454of actuator piston452in the axial direction of teeth ring470.

Teeth ring470of actuator assembly450is generally tubular and comprises a first or upper end471, a second or lower end473, and a central bore or passage extending between ends471and473. Teeth ring470is coupled to bearing mandrel220via a plurality of circumferentially spaced splines or pins472disposed radially therebetween. In this arrangement, relative axial and rotational movement between bearing mandrel220and teeth ring470is restricted. In this exemplary embodiment, teeth ring470comprises a plurality of circumferentially spaced teeth474extending from upper end471. Teeth474of teeth ring470are configured to matingly engage or mesh with the teeth460of actuator piston452when biasing member462biases actuator piston452into contact with teeth ring470, as will be discussed further herein.

In this exemplary embodiment, actuator assembly450is both mechanically and hydraulically biased during operation of mud motor35. Additionally, the driveline of mud motor35is independent of the operation of actuator assembly450while drilling, thereby permitting 100% of the available torque provided by power section40to power drill bit90when actuator assembly450is disengaged. The disengagement of actuator assembly450may occur at high flowrates through mud motor35, and thus, when higher hydraulic pressures are acting against actuator piston452. Additionally, in some embodiments, actuator assembly450may be used to rotate something parallel to bearing mandrel220instead of being used like a clutch to interrupt the main torque carrying driveline of mud motor35. In this configuration, actuator assembly450comprises a selective auxiliary drive that is simultaneously both mechanically and hydraulically biased. Further, this configuration of actuator assembly450allows for various levels of torque to be applied as the hydraulic effect can be used to effectively reduce the preload force of biasing member462acting on mating teeth ring470. This type of angled tooth clutch may be governed by the angle of the teeth (e.g., teeth474of teeth ring470), the axial force applied to keep the teeth in contact, the friction of the teeth ramps, and the torque engaging the teeth to determine the slip torque that is required to have the teeth slide up and turn relative to each other.

In some embodiments, actuator assembly450permits rotation in mud motor35to rotate rotor50and bearing mandrel220until bend adjustment assembly300has fully actuated from the first configuration303to the second configuration305, and then, subsequently, ratchet or slip while transferring relatively large amounts of torque to bearing housing210. This reaction torque may be adjusted by increasing the hydraulic force or hydraulic pressure acting on actuator piston452, which may be accomplished by increasing flowrate through mud motor35. When additional torque is needed a lower flowrate or fluid pressure can be applied to actuator assembly450to modulate the torque and thereby rotate bend adjustment assembly300. The fluid pressure is transferred to actuator piston452by compensating piston226. In some embodiments, the pressure drop across drill bit90may be used to increase the pressure acting on actuator piston452as flowrate through mud motor35is increased.

Referring now toFIGS.4-7,19-21, having described the structure of the embodiment of driveshaft assembly100, bearing assembly200, and bend adjustment assembly300, an embodiment for operating assemblies100,200, and300will now be described. As described above, bend adjustment assembly300includes first configuration303shown inFIGS.4,5and second configuration305shown inFIGS.20,21. In this exemplary embodiment, first configuration303of assembly300corresponds to a low bend setting providing a first non-zero deflection angle θ1while second configuration305corresponds to a high bend setting providing a second deflection angle θ2that is greater than the first non-zero deflection angle θ1. In other embodiments, the fist configuration303or second configuration305may correspond to a straight setting providing a 0° deflection angle θ.

In this exemplary embodiment, mud motor35may be operated to drill wellbore16with bend adjustment assembly300locked into the first configuration303until mud motor35reaches the predefined depth at which point locking assembly400is configured to automatically unlock bend adjustment assembly300such that bend adjustment assembly300may be actuated from the first configuration303to the second configuration305. Locking assembly400includes a first or locked configuration which prevents actuator assembly350from shifting bend adjustment assembly300from the first configuration303to the second configuration305irrespective of the manner in which mud motor35is operated (e.g., irrespective of the flowrate of drilling fluid through mud motor35and/or the amount of rotational torque applied to mud motor35from the rotary system24). Locking assembly400is configured to automatically actuate from the locked configuration to an unlocked configuration upon the mud motor35reaching the predefined depth in wellbore16. In the unlocked configuration, locking assembly400permits actuator assembly450to actuate the bend adjustment assembly300from the first configuration303to the second configuration305, as will be described further herein.

Particularly, in the locked configuration of locking assembly400, first locking pin430restrains or locks locking piston402into the initial axial position within lower housing320. Additionally, the fingers422of locking sleeve420are received in the outer receptacles432,442of locking pins430,440, respectively, preventing locking pins430,440from travelling from their respective first lateral positions to their respective second lateral positions. Additionally, with locking assembly400in the locked configuration, lower adjustment mandrel370is axially locked in a first or initial axial position relative to upper adjustment mandrel360by shear pin380. In the initial axial position of lower adjustment mandrel370, castellations333of lower housing320interlock with the castellations376of lower adjustment mandrel370, preventing relative rotation between lower adjustment mandrel370and lower housing320. The prevention of relative rotation between housing320and mandrel370in-turn prevents bend adjustment assembly300from shifting from first configuration303to second configuration305.

Upon reaching the predefined depth in wellbore16, pressure within the central passage of lower housing320reaches a predefined burst pressure causing the rupture disk426to burst, exposing fluid passage334of lower housing320to the pressure of the drilling fluid flowing through bend adjustment assembly300. This increase in fluid pressure is applied to the shoulder424of locking sleeve420, forcing the locking sleeve420to travel axially through lower housing320until the lower end423of locking sleeve420contacts an annular ring or stop342positioned in lower housing320.

As locking sleeve420travels towards annular stop342, the fingers422of locking sleeve420release from the outer receptacles432,442of locking pins430,440, respectively, allowing biasing members436,446to shift locking pins430,440, respectively, from their respective first lateral positions to their respective second lateral positions, as shown particularly inFIG.20.

With first locking pin430in the second lateral position, the slotted opening434of first locking430aligns with the first ledge412of locking piston402. In this arrangement, the net pressure force applied to locking piston402by the pressure of the drilling fluid flowing through bend adjustment assembly forces locking piston402from the initial axial position to the set axial position. Additionally, keys410of locking piston402press against the lower adjustment mandrel370as the locking piston402is shifted to the set axial position, thereby shearing the shear pin380connecting lower adjustment mandrel370with upper adjustment mandrel360, and forcing lower adjustment mandrel370upwards from the initial axial position of mandrel370into a second or set axial position of lower adjustment mandrel370. In the set axial position of lower adjustment mandrel370, the castellations333of lower housing320are no longer interlocked with the castellations376of lower adjustment mandrel370, thereby permitting relative rotation between lower housing320and lower adjustment mandrel370.

With locking assembly400in the unlocked configuration and with lower adjustment mandrel370in the set axial position, bend adjustment assembly300may be actuated from the first configuration303to the second configuration305by rotating offset housings310and320relative adjustment mandrels360and370in response to varying a flowrate of drilling fluid through annulus116and/or varying the degree of rotation of drillstring21at the surface. As described above, offset bore327and offset engagement surface323of lower housing320are offset from central bore329and the central axis of housing320to form a lower offset angle, and offset engagement surface365of upper adjustment mandrel360is offset from the central axis of mandrel360to form an upper offset angle. Additionally, offset engagement surface323of lower housing320matingly engages the engagement surface372of lower adjustment mandrel370while the engagement surface314of upper housing310matingly engages the offset engagement surface365of upper adjustment mandrel360.

In this configuration, the relative angular position between lower housing320and lower adjustment mandrel370determines the total offset angle (ranging from 0° to a maximum angle greater than 0°) between the central axes of lower housing320and driveshaft housing110. The minimum angle occurs when the upper and lower offsets are in-plane and cancel out, while the maximum angle occurs when the upper and lower offsets are in-plane and additive. Therefore, by adjusting the relative angular positions between offset housings310,320, and adjustment mandrels360,370, the deflection angle θ and bend301of bend adjustment assembly300may be adjusted or manipulated.

The magnitudes of bend301in configurations303and305(e.g., the magnitudes of deflection angles θ1and θ2) are controlled by the relative positioning of shoulders328S and shoulders375, which establish the extents of angular rotation in each direction. In this exemplary embodiment, lower housing320is provided with a fixed amount of spacing between shoulders328S, while adjustment mandrel370can be configured with an optional amount of spacing between shoulders375, allowing the motor to be set up with the desired bend setting options (θ1and θ2) as dictated by a particular application simply by providing the appropriate configuration of lower adjustment mandrel370.

Actuator assembly450controls the actuation of bend adjustment assembly300between first configuration303and second configuration305. In this exemplary embodiment, actuator assembly450selectively or controllably transfers torque from bearing mandrel220(supplied by rotor50) to bearing housing210in response to changes in the flowrate of drilling fluid supplied to power section40. In this exemplary embodiment, to actuate bend adjustment assembly300from the first configuration303to the second configuration305, the pumping of drilling mud from surface pump23and the rotation of drillstring21by rotary system24is ceased and/or reduced by a predetermined percentage from the maximum drilling flowrate of well system10, where the maximum drilling flowrate of well system10is dependent on the application, including the size of drillstring21and BHA30.

For instance, the maximum drilling flowrate of well system10may comprise the maximum drilling flowrate that may be pumped through drillstring21and BHA30before components of drillstring21and/or BHA30are eroded or otherwise damaged by the mud flowing therethrough. In some embodiments, the reduced flowrate of drilling mud from surface pump23comprises approximately 1%-30% of the maximum drilling flowrate of well system10; however, in other embodiments, the reduced flowrate may vary. For instance, in some embodiments, the reduced flowrate may comprise zero or substantially zero fluid flow.

In this exemplary embodiment, as drilling fluid flows through BHA30from drillstring21at the reduced flowrate, rotational torque is transmitted to bearing mandrel220via rotor50of power section40and driveshaft120. Additionally, biasing member462applies a biasing force against shoulder454of actuator piston452to urge actuator piston452into contact with teeth ring470, with teeth460of piston452in meshing engagement with the teeth474of teeth ring470. In this arrangement, torque applied to bearing mandrel220is transmitted to bearing housing210via the meshing engagement between teeth474of teeth ring470(rotationally fixed to bearing mandrel220) and teeth460of actuator piston452(rotationally fixed to bearing housing210).

Rotational torque applied to bearing housing210via actuator assembly450is transmitted to offset housings310,320, which rotate (along with bearing housing210) in a first rotational direction relative adjustment mandrels360,370. Particularly, extension328of lower housing320rotates through arcuate recess379of lower adjustment mandrel370until a shoulder328S engages a corresponding shoulder375of recess379, restricting further relative rotation between offset housings310,320, and adjustment mandrels360,370. Following the rotation of lower housing320, bend adjustment assembly300forms second deflection angle θ2with bend adjustment assembly300now in the second configuration305.

With bend adjustment assembly300now in the second configuration305, the flowrate of drilling mud from surface pump23is increased from the reduced flowrate to an increased flowrate. In some embodiments, the increased flowrate of drilling mud from surface pump23comprises approximately 50%-100% of the maximum drilling flowrate of well system10; however, in other embodiments, the increased flowrate may vary. The increased flowrate applies a net pressure force sufficient to overcome the biasing force applied against the upper end401of locking piston402via biasing member354to force the locking piston upwards into a locked position whereby the keys410of locking piston402are received in long slots378as shown particularly inFIG.21.

Additionally, with drilling mud flowing through BHA30from drillstring21at the increased flowrate, fluid pressure applied against the lower end455of actuator piston452from the lubricant in chamber217is increased (due to the increased pressure of the drilling fluid which is transferred through piston226), overcoming the biasing force applied against shoulder454by biasing member462and thereby disengaging actuator piston452from teeth ring470. With actuator piston452disengaged from teeth ring470, torque is no longer transmitted from bearing mandrel220to bearing housing210. Further, in this exemplary embodiment, a flow restriction is formed between the inner surface of locking piston402and shoulder122of driveshaft120when locking piston402is in the locked position with keys410received in short slots377of lower adjustment mandrel370, corresponding to first bend configuration303. The flow restriction is deactivated when locking piston402is in the locked position with keys410received in long slots377of lower adjustment mandrel370, corresponding to second bend configuration305. The flow restriction may be registered or indicated by a pressure increase in the drilling fluid pumped into drillstring21by surface pump23, where the pressure increase results from the backpressure provided by the flow restriction. Thus, bend adjustment assembly300provides a surface indication of the assembly300shifting into the second configuration305.

Further, the second locking pin440retains locking piston402in the locked position with keys410received in long slots378such that relative rotation between lower adjustment mandrel370and lower housing320is restricted (keeping in mind relative rotation between locking piston402and lower housing320is restricted) and bend adjustment assembly300remains locked in the second configuration305. Particularly, with locking piston402in the locked position and second locking pin440in the second lateral position, the slotted opening444is laterally offset from the second ledge414of locking piston402. Instead, the second ledge414contacts or abuts a side of the second locking pin440, preventing locking piston402from travelling downwards through lower housing320away from the locked position. Thus, in this exemplary embodiment, second locking pin440automatically relocks the locking assembly400into the locked configuration following the actuation of bend adjustment assembly300into the second configuration305such that assembly300cannot depart the second configuration305irrespective of changes in drilling fluid flowrate and/or rotation of mud motor35by rotary system24.

In an alternative embodiment, the procedures for shifting bend adjustment assembly300between the first configuration303and the second configuration305may be reversed by reconfiguring lower adjustment mandrel370of bend adjustment assembly300. Particularly, in this alternative embodiment, the position of arcuate recess379is shifted 180° about the circumference of lower adjustment mandrel370. By shifting the angular position of arcuate recess379180° about the circumference of lower adjustment mandrel370, the alternative embodiment of bend adjustment assembly300may be shifted from the first configuration303to the second configuration305by applying WOB to the mud motor35and activating rotary system24to rotate drillstring21to apply reactive torque to bearing housing210and rotate lower housing320relative to adjustment mandrel370in the second rotational direction, thereby shifting the alternative embodiment of bend adjustment assembly300into the second configuration305.

In an alternative embodiment, rather than having second locking pin440automatically relock the locking assembly400into the locked configuration following the actuation of bend adjustment assembly300into the second configuration305, a different configuration of locking pin may be used, as shown for example inFIG.26, that is not acted on by a biasing member and does not engage second ledge414at any point during operation. This allows for unlimited shifting between first configuration303and second configuration305upon reaching the predefined depth in wellbore16and causing rupture disk426to burst.

The bend adjustment assembly300described above comprises a single-shift bend adjustment assembly300which shifts automatically upon reaching the predefined depth in wellbore16from the first configuration303to the second configuration305. Prior to reaching the predefined depth the bend adjustment assembly300cannot be shifted from the first configuration303into a different configuration providing a different deflection angle θ by, for example, using a shear pin to hold the lower adjustment mandrel370in an axial position that keeps castellations376engaged with the castellations333of lower housing320. Additionally, after shifting into the second configuration305once the predefined depth has been reached, the bend adjustment assembly300cannot be shifted from the second configuration305into another configuration providing a different deflection angle θ.

In some applications, it may be desirable to shift a downhole-adjustable bend assembly an indefinite number of times between separate configurations providing separate deflection angles without needing to retrieve the bend adjustment assembly from the wellbore. Referring now toFIGS.22-28, another embodiment of a multi-shift bend adjustment assembly500is shown which may be locked in a first configuration503(shown inFIGS.22-26) providing a first deflection angle θ, then activated at a predefined depth to unlock and allow shifting between a first configuration503(shown inFIG.28) and a second configuration505(shown inFIG.27) an unlimited number of times without needing to retrieve the bend adjustment assembly500to the surface. In some embodiments, mud motor35may comprise bend adjustment assembly500in lieu of bend adjustment assembly300; however, in other embodiments, bend adjustment assembly500may comprise a component of mud motors which vary in configuration from mud motor35.

Bend adjustment assembly500includes features in common with mud motor300, and shared features are labeled similarly. Particularly, bend adjustment assembly500is similar to assembly300except that assembly500includes a lower adjustment mandrel510instead of lower adjustment mandrel370and a locking assembly550which includes an alternative second locking pin560instead of the second locking pin440of the locking assembly400described above. Second locking pin560has a longitudinal first end561, a longitudinal second end563opposite first end561, an outer receptacle562extending longitudinally into second end563, and a slotted opening564located between ends561,563.

As shown particularly inFIGS.24,25, lower adjustment mandrel510of bend adjustment assembly300is generally tubular and has a first or upper end511, a second or lower end513, and a central bore or passage extending therebetween that is defined by a generally cylindrical inner surface. In this exemplary embodiment, lower adjustment mandrel510is splined to the upper adjustment mandrel360such that relative movement therebetween is restricted. Similar to the operation of lower adjustment mandrel370described above, when bend adjustment assembly500is disposed in the first configuration503, a first deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360, and when bend adjustment assembly500is disposed in the second configuration505, a second deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360that is different from the first deflection angle.

In this exemplary embodiment, lower adjustment mandrel510additionally includes a pair of circumferentially spaced first or short slots512and a pair of circumferentially spaced second or long slots514. Both the short slots512and long slots514of lower adjustment mandrel510extend axially into lower adjustment mandrel370from the lower end513thereof. In this exemplary embodiment, each short slot512is circumferentially spaced approximately 180° apart. Similarly, in this exemplary embodiment, each long slot514is circumferentially spaced approximately 180° apart. Additionally, each of the slots512,514of lower adjustment mandrel510are configured to rotationally lock the lower housing320through the locking piston402to the lower adjustment mandrel510when the keys410of locking piston402are received in slots512,514. The locking between locking piston402and lower adjustment mandrel510via slots512,514eliminates the need for castellations376. Thus, although lower adjustment mandrel510is shown inFIGS.24,25as including castellations, it may be understood that in this exemplary embodiment, neither lower housing320nor lower adjustment mandrel510need include castellations.

Additionally, unlike lower adjustment mandrel370described above, lower adjustment mandrel510of bend adjustment assembly500is axially locked to upper adjustment mandrel360such that axial movement is prevented therebetween at all times. In other words, mandrels360,510are not connected by a shear pin in this embodiment intended to break during the operation of bend adjustment assembly500. Instead, lower adjustment mandrel510remains in the same axial position relative upper adjustment mandrel360in both the first configuration503and second configuration505of bend adjustment assembly500.

In the first configuration503of bend adjustment assembly500, locking piston402is disposed in a locked position with keys410received in the long slots514of lower adjustment mandrel510, preventing relative rotation between lower housing320and lower adjustment mandrel370(rotation being restricted between locking piston402and lower housing320). Additionally, locking piston402is prevented by first locking pin430(due to engagement between pin430and second ledge414) from shifting from the locked position to an unlocked position (axially spaced from the locked position) in which keys410are released from long slots514. Thus, similar to bend adjustment assembly300described above, locking assembly550prevents bend adjustment assembly500from shifting from the first configuration503to the second configuration505until bend adjustment assembly500has reached the predefined depth at which rupture disk426is configured to burst.

Similar to the operation of locking assembly400described above, upon reaching the predefined depth and bursting rupture disk426(which can be accomplished automatically by reaching a given depth at a given mud weight or by increasing mud weight at the given depth such that the mud weight reaches a predefined mud weight threshold to thereby increase the hydrostatic pressure beyond the burst disk threshold), the locking sleeve420of locking assembly550shifts from the locked position to the unlocked position, releasing finger422of locking sleeve420from the outer receptacle432of first locking pin430. First locking pin430is thus permitted to shift into the second lateral position via the biasing force applied by first biasing member436, thereby aligning slotted opening434of first locking pin430with the second ledge414of locking piston402.

In this configuration, the flowrate of drilling fluid through bend adjustment assembly500may be reduced and/or ceased to allow locking piston402to travel downwards into the unlocked position releasing keys410from long slots514of lower adjustment mandrel510. With locking piston402in the unlocked position, drilling fluid may be flowed through the bend adjustment assembly500at the reduced flowrate to activate actuator assembly450and thereby rotate lower housing320in the first rotational direction relative to lower adjustment mandrel510until bend adjustment assembly500is shifted into the second configuration505, as shown particularly inFIG.24. Drilling fluid may then be flowed through bend adjustment assembly500at a rate above the reduced flowrate (e.g., at the maximum drilling flowrate) to shift locking piston402upwards into a locked position with keys410received in the short slots512of lower adjustment mandrel510.

Unlike bend adjustment assembly300described above, second locking pin560does not lock bend adjustment assembly500into the second configuration505. Instead, bend adjustment assembly500is permitted to actuate back-and-forth between the second configuration505and first configuration503by reducing and/or ceasing the flow of drilling fluid through bend adjustment assembly500to shift locking piston402into the unlocked position, and rotating lower housing320relative lower adjustment mandrel510via the actuator assembly450. As an example, once in the second configuration505, bend adjustment assembly500may be returned to the first configuration503with or without applying WOB to the mud motor35and activating rotary system24to rotate drillstring21to apply reactive torque to bearing housing210and rotate lower housing320relative to adjustment mandrel510in a second rotational direction, thereby shifting bend adjustment assembly500from the second configuration505to the first configuration503.

Referring now toFIGS.29-32, another embodiment of a bend adjustment assembly600is shown. Bend adjustment assembly600includes features in common with the bend adjustment assemblies300,500described above, and shared features are labeled similarly. Particularly, bend adjustment assembly600comprises a single-shift bend adjustment assembly similar to bend adjustment assembly300except that, unlike bend adjustment assembly300, bend adjustment assembly600comprises the lower adjustment mandrel510of bend adjustment assembly500, which is axially locked to upper adjustment mandrel360such that axial movement is prevented therebetween at all times. As with bend adjustment assembly500, the locking between locking piston402and lower adjustment mandrel510via slots512,514eliminates the need for castellations376.

In this exemplary embodiment, bend adjustment assembly600is in the second configuration505when locking assembly500is in the locked configuration and may only shift from the second configuration505to the first configuration once locking assembly500has automatically shifted into the unlocked configuration upon mud motor35/bend adjustment assembly600reaching the predefined depth in the wellbore16. Thus, while both bend adjustment assembly300and bend adjustment assembly600each comprise single-shift bend adjustment assemblies shiftable between configurations303,305, bend adjustment assembly300shifts from the first configuration303to the second configuration305after reaching the predefined depth in wellbore16while bend adjustment assembly600shifts from the second configuration505to the first configuration503after reaching the predefined depth. In this exemplary embodiment, bend adjustment assembly600may shift from a high bend setting to a low bend setting after reaching the predefined depth.

Referring now toFIG.33, an embodiment of a method650for forming a deviated wellbore using a downhole mud motor is shown. Initially, at block652method650includes positioning a bend adjustment assembly of the downhole mud motor in the wellbore in a first configuration that provides a first deflection angle between a longitudinal axis of a driveshaft housing of the downhole mud motor and a longitudinal axis of a bearing mandrel of the downhole mud motor. In some embodiments, block652comprises positioning one of the bend adjustment assemblies300,500, and600of a downhole mud motor (e.g., mud motor35) in wellbore16in a first configuration (e.g., one of configurations303,503, and505) that provides a first deflection angle between the longitudinal axis115of driveshaft housing110and longitudinal axis225of bearing mandrel220.

At block654, method650comprises locking the bend adjustment assembly into the first configuration with a locking assembly of the bend adjustment assembly that is disposed in a locked configuration. In some embodiments, block654comprises locking one of the bend adjustment assemblies300,500, and600into the first configuration with one of the locking assemblies400,550. At block656, method650comprises automatically shifting the locking assembly from the locked configuration to an unlocked configuration upon the mud motor reaching a predefined depth (which can be accomplished automatically by reaching a given depth at a given mud weight or by increasing mud weight at the given depth such that the mud weight reaches a predefined mud weight threshold to thereby increase the hydrostatic pressure beyond the burst disk threshold), in the wellbore. In some embodiments, block656comprises automatically shifting the locking assembly400,550from the locked configuration to an unlocked configuration upon reaching the predefined depth in the wellbore16.

At block658, method650comprises shifting the bend adjustment assembly, with the downhole mud motor positioned in the wellbore and the locking assembly in the unlocked configuration, from the first configuration to a second configuration that provides a second deflection angle between the longitudinal axis of the driveshaft housing and the longitudinal axis of the bearing mandrel, the second deflection angle being different from the first deflection angle. In some embodiments, block658comprises shifting the bend adjustment assembly300,500,600, with the downhole mud motor positioned in the wellbore16and the locking assembly400,550in the unlocked configuration, from the first configuration to the second configuration305,505, and503, respectively.

Referring now toFIG.34, another embodiment of a downhole mud motor700is shown. Downhole mud motor700may replace the mud motor40described above in the BHA30shown inFIG.1. Additionally, mud motor700includes features in common with mud motor40, where shared features are labeled similarly. Mud motor700includes driveshaft assembly100, bearing assembly200, and a bend adjustment assembly705. Similar to bend adjustment assembly300described above, bend adjustment assembly705is configured to shift from a first configuration707(shown inFIGS.36and37as further described below) providing a first deflection angle θ1to a second configuration709(shown inFIG.38as further described below) providing a second deflection angle θ2upon achieving a predefined depth in a wellbore (e.g. wellbore16shown inFIG.1). In addition, after shifting from the first configuration707to the second configuration709upon achieving the predefined depth, bend adjustment assembly705is configured to shift from the second configuration709to a third configuration711(shown inFIG.39as further described below) providing a third deflection angle θ1that is different from the first deflection angle θ1and/or the second deflection angle θ2.

Structurally, bend adjustment assembly705is similar in configuration to the bend adjustment assembly300described above except that bend adjustment assembly705includes a lower adjustment mandrel710in lieu of the lower adjustment mandrel370shown inFIG.10. Referring toFIG.35, lower adjustment mandrel710of bend adjustment assembly705is generally tubular and has a first or upper end710A, a second or lower end710B opposite upper end710A, and a central bore or passage extending therebetween that is defined by a generally cylindrical inner surface. In this exemplary embodiment, lower adjustment mandrel710includes a generally cylindrical outer surface comprising an offset engagement surface712, an annular seal713, and an arcuately extending recess714. Offset engagement surface712has a central or longitudinal axis that is offset or disposed at a non-zero angle relative to a central or longitudinal axis of the upper end360A of upper adjustment mandrel360and the lower end320B of lower housing320, where offset engagement surface712is disposed directly adjacent or overlaps the offset engagement surface323of lower housing320. Additionally, lower adjustment mandrel710includes a pair of circumferentially spaced stop shoulders715A and715B.

In this exemplary embodiment, when bend adjustment assembly705is disposed in the first configuration707, a first deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360. When bend adjustment assembly705is in the first configuration707the bend adjustment assembly705cannot change its angular position and, unlike bend adjustment assembly300described above, all of the reactive torque loads (e.g., reactive torque applied to the drill bit90by the sidewall19of wellbore16) are passed through castellations717and333. Additionally, in this exemplary embodiment, the initial angular position of bend adjustment assembly705comprises a value in-between a maximum bend setting and a minimum bend setting of the bend adjustment assembly705without either of the large stop shoulders715A and715B being in contact with the328S shoulders of lower housing320.

When bend adjustment assembly300is disposed in the second configuration709, a second deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360that is different from the first deflection angle (shoulder328S of lower housing320being in contact with shoulder715A of lower adjustment mandrel710when in the second configuration709), and when bend adjustment assembly300is disposed in the third configuration711, a third deflection angle is provided between the central axis of lower housing320and the central axis of upper adjustment mandrel360that is different from both the first deflection angle and the second deflection angle (shoulder328S of lower housing320being in contact with shoulder715B of lower adjustment mandrel710when in the third configuration709).

Annular seal713of lower adjustment mandrel710is disposed in the outer surface of lower adjustment mandrel710to sealingly engage the inner surface of lower housing320. Arcuate recess714of lower adjustment mandrel710is defined by an inner terminal end or arcuate shoulder714E and the pair of circumferentially spaced axially extending shoulders715A and715B. Lower adjustment mandrel710also includes a pair of circumferentially spaced first or short slots716and a pair of circumferentially spaced second or long slots718, where both short slots716and long slots718extend axially into lower adjustment mandrel710from lower end710B. In this embodiment, each short slot716is circumferentially spaced approximately 180° apart. Similarly, in this embodiment, each long slot718is circumferentially spaced approximately 180° apart; however, in other embodiments, the circumferential spacing of short slots716and long slots718may vary.

In this embodiment, the lower end710B of lower adjustment mandrel710further includes a plurality of circumferentially spaced protrusions or castellations717configured to matingly or interlockingly engage the castellations333formed at the upper end320A of lower housing320. Castellations717are spaced substantially about the circumference of lower adjustment mandrel710, and may be formed on the portion of the circumference of lower adjustment mandrel710comprising recess714as well as the portion of the circumference of lower adjustment mandrel710which is arcuately spaced from recess714. Castellations717may be circumferentially spaced uniformly about a circumference of lower adjustment mandrel710; alternatively, castellations717may only be positioned along a portion of the circumference of lower adjustment mandrel710.

In some embodiments, lower adjustment mandrel710comprises a first or lower axial position (shown inFIGS.36and37) relative lower housing320and upper adjustment mandrel360, and a second or upper axial position relative lower housing320and upper adjustment mandrel360which is axially spaced from the lower axial position. When lower adjustment mandrel710is in the lower axial position, castellations717of lower adjustment mandrel710may interlock with castellations333of lower housing320, restricting relative rotation therebetween. In this configuration, bend adjustment assembly705may be operated by an operator of well system10as a bend assembly that provides a fixed bend and thus may operate drillstring21and BHA30as desired without inadvertently actuating bend assembly300between configurations705,707, and709. For example, with lower adjustment mandrel710disposed in the lower axial position, rotation of drillstring21and/or the flow of drilling fluid at a drilling flowrate through bend adjustment assembly705will not unlock or otherwise actuate bend adjustment assembly705from the first configuration707to either the second configuration709or third configuration711given the interlocking engagement between castellations333of lower housing320with castellations717of lower adjustment mandrel710. However, when lower adjustment mandrel710is in the upper axial position (this movement of lower adjustment mandrel710occurs after achieving the predefined depth), castellations717of lower adjustment mandrel710are axially spaced and disengaged from castellations333of lower housing320, permitting relative rotation therebetween. As will be described further herein, in some embodiments, lower adjustment mandrel710is initially retained in the lower axial position via a shear pin or member719and lower adjustment mandrel710is actuatable while downhole or in-situ from the lower axial position to the upper axial position.

Referring now toFIGS.34-39, initially, it may be understood that upper housing310is shown as transparent inFIGS.35-39for the purpose of clarity. Similar to bend adjustment assembly300described above, the bend adjustment assembly705of mud motor700is configured to shift from the first configuration707(shown inFIGS.36and37) to the second configuration709(shown inFIG.38) automatically upon reaching the predefined depth in wellbore16. Particularly, mud motor700may be operated to drill wellbore16with bend adjustment assembly705locked into the first configuration707until mud motor700reaches the predefined depth at which point locking assembly400is configured to automatically unlock bend adjustment assembly705such that bend adjustment assembly705may be actuated automatically from the first configuration707to the second configuration709.

It may be understood that in the first configuration707the extension328of lower housing320is oriented angularly relative to lower adjustment mandrel710whereby both shoulders328S of extension328are circumferentially spaced from the corresponding shoulders715A and715B of mandrel710. Additionally, in the first configuration707relative rotation between lower housing320and lower adjustment mandrel710is restricted via interlocking engagement between castellations333of lower housing320and castellations717of lower adjustment mandrel710prior to mud motor700achieving the predefined depth. Once bend adjustment assembly705is unlocked from the first configuration707via the bursting of rupture disk426of locking assembly400as described in further detail above in relation to bend adjustment assembly700may be cycled or toggled indefinitely between the second configuration709and third configuration711(shown inFIGS.38and39) an unlimited number of times without needing to retrieve the mud motor700from the wellbore16.

In this exemplary embodiment, bend adjustment assembly705may be shifted from the second configuration709to the third configuration711by ceasing the pumping of drilling fluid from surface pump23for a first time period to shift the locking piston380of bend adjustment assembly705into the unlocked position. Either concurrent with the first time period or following the initiation of the first time period, rotary system24may be activated to rotate drillstring21at an actuation rotational speed (surface pump23is also activated to flow at a first actuation flowrate) for a second time period to apply reactive torque from the sidewall19of wellbore16to the bearing housing210of bearing assembly and thereby rotate lower offset housing320relative to the lower adjustment mandrel710in a first rotational direction, which thereby shifts bend adjustment assembly705into the third configuration711. With bend adjustment assembly705in the third configuration711, surface pump23may be operated either at a second actuation flowrate for a third time period or operated immediately at a maximum drilling flowrate of the well system comprising mud motor700to thereby shift locking piston380into the locked position, locking bend adjustment assembly705into the third configuration711. This exemplary embodiment allows for all three of the deflection angles θ1-θ3to be non-zero in magnitude. For example, in some embodiments, the first deflection angle corresponding to the first configuration707of bend adjustment assembly705is approximately 1.5 degrees, the second deflection angle corresponding to the second configuration709of bend adjustment assembly705is approximately 2.12 degree, and the third deflection angle corresponding to the third configuration711of bend adjustment assembly705is approximately 1.15 degrees.

In this exemplary embodiment, bend adjustment assembly705may be shifted from the third configuration711to the second configuration709by ceasing the rotation of drillstring21by rotary system24while also ceasing the pumping of drilling fluid from surface pump23at a second flowrate to thereby shift locking piston380of the bend adjustment assembly705into the unlocked position. With locking piston380disposed in the unlocked position, surface pump23may resume pumping drilling fluid into drill string21while rotary system24remains inactive, thereby rotating lower adjustment mandrel710in a second rotational direction, opposite the first rotational direction, to shift bend adjustment assembly705into the second configuration709. With bend adjustment assembly705now disposed in second configuration709, the flowrate of drilling fluid from surface pump23is increased from the second flowrate to a third flowrate to shift locking piston380into the locked position, thus locking bend adjustment assembly705in the second configuration709. Additionally, a pressure signal provided by flow restrictor123may provide a surface indication of the actuation of bend adjustment assembly705switching from the third configuration711to the second configuration709.

In an alternative embodiment, bend adjustment assembly705may not include actuator assembly400. In this alternative embodiment, first deflection angle θ1is equal or substantially equal to the second deflection angle θ2. For example, in this alternative embodiment, the first deflection angle θ1is approximately 2.1 degrees, the second deflection angle θ2is approximately 2.15 degrees, and the third deflection angle θ3is approximately 1.5 degrees. For applications that only require unlocking and two distinct deflection angles and no need to return to the first or second deflection angle the actuator assembly400in this alternative embodiment may be eliminated.

Referring toFIG.40, an embodiment of a method750for adjusting a deflection angle of a downhole mud motor disposed in a borehole is shown. It may be understood that in at least some embodiments method750may be performed using the mud motor700shown inFIG.34. Method750includes features in common with the method600shown inFIG.33. Particularly, in addition to previously described blocks652-658, method750includes block752where a flowrate of drilling fluid is increased through the bend adjustment assembly to lock the bend adjustment assembly in the second configuration. Block752may be performed when the BHA comprising the mud motor is “off-bottom” where WOB is not applied to the BHA. Alternatively, block752may be performed when the BHA comprising the mud motor is “on-bottom” with WOB being actively applied to the BHA.

At block756, method750includes reducing the flowrate of the drilling fluid to shift the bend adjustment assembly from the second configuration to a third configuration providing a third deflection angle that is different from the first deflection angle and/or the second deflection angle. In some embodiments, the first deflection angle is approximately 1.5 degrees, the second deflection angle is approximately 2.12 degree, and the third deflection angle is approximately 1.15 degrees. In other embodiments, the first deflection angle is approximately 2.1 degrees, the second deflection angle is approximately 2.15 degree, and the third deflection angle is approximately 1.5 degrees. However, it may be understood the magnitude of each deflection angle may vary in other embodiments. At block758, method750includes increasing the flowrate of drilling fluid to lock the bend adjustment assembly in the third configuration. In some embodiments, the first configuration corresponds to the first configuration707(shown inFIGS.36and37) of bend adjustment assembly705shown inFIG.34, the second configuration corresponds to the second configuration709of bend adjustment assembly705, and the third configuration corresponds to the third configuration711of bend adjustment assembly705.