WO2018217196A1

WO2018217196A1 - Downhole drilling motor

Info

Publication number: WO2018217196A1
Application number: PCT/US2017/034252
Authority: WO
Inventors: Michael Kuhlman; Gregory R. ALTIMAS; Albert Odell
Original assignee: Weatherford Technology Holdings, Llc
Priority date: 2017-05-24
Filing date: 2017-05-24
Publication date: 2018-11-29

Abstract

A drilling motor operated with flow of drilling fluid therethrough includes an elongated shaft having integrally formed sections and includes a housing having a plurality of separate sections inserted on the elongated shaft and interconnected to one another. The elongated shaft includes a stem at the first end, a rotor body extending from the stem, a shaft body extending from the stem, and a head extending from the shaft body at the second end. The housing includes a top sub inserted on the stem, a stator section inserted on the rotor body, a shaft section inserted on the shaft body, and a bearing section inserted on the head. A bearing assembly is disposed in between the head and the bearing section. The elongated shaft is rotatable in the housing with the flow of the drilling fluid, and a fluid passageway of the elongated shaft can deliver the drilling fluid out of the head.

Description

Downhole Drilling Motor

BACKGROUND

[0001] In drilling a borehole, the path of the borehole can be drilled using a downhole drilling motor (mud motor), and the motor can be used to steer the drilling direction. As shown in Fig. 1A, for example, a drillstring 30 deploys in a borehole 12 from a drilling rig 20 and has a bottom hole assembly 40 disposed thereon. The rig 20 has drawworks and other systems to control the drillstring 30 as it advances and has pumps (not shown) that circulate drilling fluid or mud through the drillstring 30. The bottom hole assembly 40 has a mud motor 50 and can have an electronics section 42 and an instrument section 44.

[0002] Drilling fluid flows from the drillstring 30 to a rotor-stator element in the mud motor 50. Powered by the pumped fluid, the motor 50 imparts torque to the drill bit 34 to rotate the bit 34 and advance the borehole 12. The drillstring 30 may also rotate the mud motor 50, thereby imparting additional rotation to the drill bit 34. If the mud motor 50 includes a bent housing, then the mud motor 50 can be used for directional drilling. In any event, the drilling fluid exits through the drill bit 34 and returns to the surface via the borehole annulus. The circulating drilling fluid removes drill bit cuttings from the borehole 12, controls pressure within the borehole 12, and cools the drill bit 34.

[0003] A typical mud motor 50 is shown in Fig. 1 B. The motor 50 is built in subassemblies including a power section 52, a transmission section 54, and a bearing section 56. Each of these sections have housing members threaded together for assembly and disassembly as needed. The motor section 52 has a stator 60 and a rotor 62. In turn, the rotor 62 connects by a universal joint 72 to a transmission shaft 70, and the transmission shaft 70 connects by a universal joint 74 to a drive mandrel 80 supported by bearings 82. In an alternative, a flexible shaft connected between the rotor 62 and the mandrel 80 can be used for the transmission shaft 70, negating the use of the joints 72, 74.

[0004] Drilling fluid from the drillstring (30) rotates the rotor 62 within the stator 60. Rotated by the rotor 62, the transmission shaft 70 transmits power from the rotor 62 to the drive mandrel 80 for rotating the drill bit (not shown) on the end of the mandrel 80. [0005] Operators constantly strive to reduce the cost of drilling by reducing time to drill wells (i.e., increasing rate-of-penetration) and by increasing the length of a producing section of the borehole. As of late, these factors have increased the severity of the operating loads, torque at bit, downhole vibration, cyclic bending loads, temperature, downhole fluids, etc. to which the drilling motor is exposed, while also increasing the time the drilling motor is used downhole for drilling. These factors have pushed existing downhole drilling motors to the limit, which has increased the likelihood of issues and failures.

[0006] Many service providers rent their downhole drilling motors to operators and treat the drilling motors as reusable assets intended to have an extended life. Yet, maintaining the drilling motors for additional reuse proves difficult due to the costs incurred from fatigue, chemical, erosion, and other damage experienced by the motors even in a single run. Historically, drilling service providers have addressed this by continuously increasing the limits that the downhole motors can withstand by improving the power section, connection, driveline, axial and thrust bearing design, and the like. This has increased the complexity of the drilling motors, increasing their maintenance costs and operating costs.

[0007] The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

SUMMARY

[0008] According to the present disclosure, a drilling motor is operated with flow of drilling fluid therethrough. The motor comprises an elongated shaft, a housing, and a bearing assembly. In one configuration, the elongated shaft has integrally-formed sections between first and second ends. The integrally-formed sections at least includes: a rotor body, and a shaft body extending with a first integral transition from the rotor body. A head extends from the shaft body. As noted herein, this head can be a separate component of the elongated shaft or can be one of the integrally-formed sections.

[0009] The housing has a plurality of separate sections inserted on the elongated shaft and interconnected to one another. The housing at least includes a stator for the rotor body of the elongated shaft. The bearing assembly is disposed in between the head and the housing. The elongated shaft is rotatable in the housing with the flow of the drilling fluid in between the rotor body and the stator.

[0010] The separate sections of the housing can comprise a top sub inserted on a stem of the elongated shaft. As noted herein, this stem can be a separate component of the elongated shaft or can be one of the integrally-formed sections. For example, in one configuration, the integrally-formed sections of the elongated shaft at least include a stem at the first end of the elongated shaft from which the rotor body extends. A cap can be separately connected to the stem and can have a shoulder engageable with a seat of the top sub.

[0011] The separate sections of the housing can comprise a stator section inserted on the rotor body and having the stator, a shaft section inserted on the shaft body, and/or a bearing section inserted on the head. In one configuration, a portion of the shaft section inserted on the shaft body may define a bend. The bend can be fixed or adjustable. The bend in the shaft section may be press-formed anywhere along the length and can be press-formed after the drilling motor is fully assembled.

[0012] The shaft body can convert orbital motion at the rotor body to rotational motion at the head.

[0013] As noted above, the integrally-formed sections of the elongated shaft can at least include the head, which can extend with a second integral transition from the shaft body. Alternatively, a jointed connection can be used at the second transition between the shaft body and the head. In other arrangements, the shaft body of the elongated shaft can instead extend with a jointed connection at the first transition from the rotor body. As such, two jointed connections can be used at both ends of the shaft body, or a jointed connection to one end and an integral transition on another end can be used on the shaft body.

[0014] As one example, the jointed connection at the second transition can include a first end of the shaft body shrunk fit to a second end of the head, a first end of the shaft body interference fit to a second end of the head, a first end of the shaft body connected by a continuous velocity joint to a second end of the head, or a first end of the shaft body connected by a universal joint to a second end of the head.

[0015] Housing connections of the separate sections of the housing to one another can comprises one or more of threaded, welded, brazed, and compression fit connections. [0016] In one configuration, the separate sections of the housing comprise: a shaft section inserted on the shaft body; a bearing section inserted on the head; and a union section interconnecting the bearing section to the shaft section and separating an annular space between the shaft section and the shaft body from the bearing assembly.

[0017] The motor can further be comprised of: a bit joint connected to the head and extending beyond the housing; and a bit connected to the bit joint. The motor can further be comprised of radial bearing sleeves disposed between the bit joint and the housing.

[0018] As one alternative, the motor can further comprise a bit connected to the head and extending beyond the housing.

[0019] In one configuration, the bearing assembly which can be used with any combination of the elongated shaft and housing disclosed herein comprises a plurality of inner and outer race rings being stacked in between the head and the housing and carrying a plurality of ball bearings.

[0020] An uphole end the inner race rings can be biased longitudinally with one or more upper springs; and a downhole end of the inner race rings can be fixed

longitudinally with a lower shoulder associated with the elongated shaft. The one or more upper springs can be held longitudinally with a sleeve disposed on the head against an upper shoulder associated with the elongated shaft.

[0021] A downhole end of the outer race rings can be biased longitudinally with one or more lower springs; and an uphole end of the outer race rings are fixed longitudinally with an upper shoulder associated with the housing. The one or more lower springs are held longitudinally against a lower shoulder associated with the housing.

[0022] In one configuration, the elongated shaft at least partially defines a fluid passageway delivering fluid from an annular space between the elongated shaft and the housing out of the head. As an alternative, the elongated shaft can define the fluid passageway from the first end to the second end, and the fluid passageway can define a cross port communicating with the annular space.

[0023] According to the present disclosure, a drilling motor operated with flow of drilling fluid therethrough comprises an elongated shaft, a housing; and a bearing assembly. The elongated shaft at least including a rotor body, a shaft body extending from the rotor body, and a head extending from the shaft body. As disclosed herein, one, more, or all of these can be separate components or integrally formed together. The housing is disposed on the elongated shaft and at least includes a stator. As disclosed herein, the housing can have a number of housing components.

[0024] The bearing assembly is disposed in between the head and the housing. The bearing assembly comprises inner and outer race rings stacked in between the head and the housing and carrying a plurality of ball bearings. A first uphole end of the outer race rings is fixed longitudinally by a first upper shoulder associated with the housing, which a first downhole end of the inner race rings is fixed longitudinally by a first lower shoulder associated with the elongated shaft. One or more upper springs longitudinally biases a second uphole end of the inner race rings relative to a second upper shoulder associated with the elongated shaft, while one or more lower springs longitudinally bias a second lower end of the outer race rings relative to a second lower shoulder associated with the housing. The elongated shaft is rotatable in the housing with the flow of the drilling fluid in between the rotor body and the stator.

[0025] According to the present disclosure, a drilling motor operated with flow of drilling fluid therethrough comprises an elongated shaft, a housing, and a bearing assembly. The elongated shaft has integrally-formed sections between first and second ends. The integrally-formed sections at least include a stem at the first end, a rotor body extending from the stem, a shaft body extending with a first integral transition from the rotor body, and a head extending with a second integral transition from the shaft body at the second end of the elongated shaft. The housing has a plurality of separate sections inserted on the elongated shaft and interconnected to one another. The separate sections at least include a top sub inserted on the stem, a stator section inserted on the rotor body, a shaft section inserted on the shaft body, and a bearing section inserted on the head. The bearing assembly is disposed in between the head and the bearing section. The elongated shaft is rotatable in the housing with the flow of the drilling fluid in between the rotor body and the stator section.

[0026] According to the present disclosure, a method of assembling a drilling motor operated with flow of drilling fluid therethrough involves providing an elongated shaft of the drilling motor having integrally-formed sections between first and second ends, the integrally-formed sections at least including a stem at the first end, a rotor body extending from the stem, a shaft body extending from the stem, and a head extending from the shaft body at the second end; inserting a plurality of separate sections of a housing on the elongated shaft and interconnecting the separate sections to one another; and installing a bearing assembly in between the head of the elongated shaft and a bearing section of the separate sections.

[0027] The disclosed drilling motor and assembly has a number of advantages. The motor can offer a one piece motor shaft for rotating the bit. The drill bit and radial bearings can be integrated into the assembly for rotating the bit, and a catch

mechanism can be integrated into the one piece motor shaft. A number of susceptible connection points can be eliminated on the motor. The connections in the motor relative to the radial bearing can reduce side forces on the assembly, and the length of the assembly can reduce the bit to bend length. Forming a bend in the shaft section housing after assembly will simplify the assembly process and reduce cost by eliminating machining on two axes.

[0028] The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Fig. 1A conceptually illustrates a prior art drilling system disposed in a borehole.

[0030] Fig. 1 B illustrates a prior art drilling motor in cross-section.

[0031] Fig. 2A illustrates a cross-sectional view of a drilling motor according to the present disclosure.

[0032] Fig. 2B illustrates a bearing arrangement of the drilling motor of Fig. 2A in more detail.

[0033] Figs. 3A-3F illustrate portions of the drilling motor during stages of assembly.

[0034] Figs. 4A, 4B-1 , and 4B-2 illustrate cross-sectional views of different transitions in the drilling motor of the present disclosure.

[0035] Fig. 5A-5B illustrate unassembled and assembled views of another drilling motor according to the present disclosure having an integrated drill bit.

DETAILED DESCRIPTION

[0036] A downhole drilling motor 100 (or mud motor) of the present disclosure illustrated in Fig. 2A connects to a drill string (not shown) and other components of a bottom hole assembly in a known manner. The drilling motor 100 has a motor section 105, a transmission section 107, and a bearing section 109 and is operated with flow of drilling fluid therethrough.

[0037] In contrast to a standard arrangement, the motor 100 has mechanisms integrated into a single-piece (or integrated) elongated shaft 200 instead of separate rotor, transmission, and drive components. In particular, the motor 100 integrates features of a rotor catch, a rotor, a transmission shaft, and axial/thrust bearing mandrel into one unitary piece of material as the elongated shaft 200. This minimizes the number of components and connections required in the drilling motor 100.

[0038] In this way, the drilling motor 100 can be built as a single assembly. Moreover, rather than being configured for reuse and an extended life, the drilling motor 100 is configured to be disposable. In fact, the drilling motor's arrangement can reduce the manufacturing costs to a level where the entire motor 100 can be expensed for a single use.

[0039] Internally, the motor 100 includes the elongated shaft 200 that extends the length of the motor 100. The elongated shaft 200 has a number of integrally-formed sections between proximal and distal ends. In the current configuration, the integrally- formed sections at least include a stem 210 at the proximal end, a rotor body 220 extending from the stem 210, a shaft body 230 extending from the rotor body 220, and a head 260 extending from the shaft body 230 at the distal end of the elongated shaft 200. (As noted later, the elongated shaft 200 can have other combinations with more or less of the integrally-formed sections 210, 220, 230, and 260.)

[0040] The stem 210 constitutes part of a rotor catch on which an end cap 212 attaches. This end cap 212 provides a catch lip and can be expandable, threaded, or otherwise affixed on the stem 210. For example, teachings of a suitable end cap are disclosed in U.S. Patent Pub. 2015/0068810, which is incorporated herein by reference. Although the stem 210 can be one of the integrally-formed sections of the elongated shaft, other configurations are possible in which the stem 210 is a separate component attached at the proximal end of the shaft 200.

[0041] The rotor body 220 extending from the proximal stem 210 has various rotor vanes 222 defined along the rotor body 220. For example, the rotor body 220 uses multiple helical vanes 222, around the circumference and extending the full length of the rotor body 220 of the elongated shaft 200. (Any suitable number and configuration of the vanes 222 could be used for the purposes of the drilling motor 100.) In the current configuration, the shaft body 230 extends with a first integral transition 232 from the rotor body 220, and the head 260 extends with a second integral transition 234 from the shaft body 230 at the distal end of the elongated shaft 200. Finally, a bit joint 190 attaches to the head 260 for connecting the distal end of the motor 100 to a drill bit or other downhole components (not shown) of a bottom hole assembly.

[0042] The entire elongated shaft 200 can be a unitary piece of material forged, machined, and/or otherwise formed to have the external/internal features of the integrally-formed sections without using mating connections along the axial extent of the shaft 200 between the sections as is typically done. For example, the elongated shaft 200 can be formed by hot extrusion, molecular decomposition, machining a billet, hydro- forming, coating, additive material deposition, casting, and the like. A complete billet bar can be formed with the desired length (i.e., several hundred inches) of the shaft 200. Alternatively, bars of intermediate length can be resistance welded together to provide a base billet of the required length for the elongated shaft 200.

[0043] In one method of forming the shaft 200, the helical vanes 222 can be formed by hot metal extrusion along the entire elongated shaft 200 in near net geometry. Metal of the shaft 200 is heated to reach a highly formable solid condition, and then the shaft 200 is forced through a die. The die has a near-identical helical vane geometry to the desired vanes 220 to be formed on the rotor body 220. The die is held fixed, while the shaft 200 is twisted with the desired helical pitch of the rotor body 220 as the shaft 200 begins to protrude from the die.

[0044] As the shaft 200 progresses, the metal cools, becoming stiffer. When a sufficient length of the shaft 200 protrudes from the die during the forming process, portion of the shaft 200 will be clamped for support, and the supporting clamp moves axially and circumferentially timed to the forming speed and helical pitch of the vanes 222. Depending on the length of the shaft 200, multiple support clamps may be used.

[0045] Once the hot metal extrusion is completed, the ends of the elongated shaft 200 can then be machine turned and milled to create the required geometry for the integrally-formed sections noted herein relative to the formed rotor body 220. In this forming process, the rotor body 220 does not require further machine milling, but only surface finishing processes such as peening, hard coating, and grinding.

[0046] The elongated shaft 200 can be composed of ordinary material, such as 4140 steel, although any suitable material could be used. In the end, the elongated shaft 200 provides strength by eliminating connections, thereby reducing failure modes. In the present example, the shaft body 230 is a flexible driveline having the integral transitions 232 and 234 without joints. In alternative configurations, the shaft body 230 can include joints or can combine an integral transition and a joint. As such, the integrally-formed sections of the elongated shaft 200 may not include the head 260, which can instead be a separate component of the shaft 200 connected by a jointed connection; and/or the integrally formed sections of the elongated shaft 200 may not include the rotor body 220, which can instead be a separate component of the shaft 200 connected by a jointed connection. Examples of using jointed and integral connections are discussed later with reference to Figs. 4B-1 and 4B-2, showing how a box-pin connection, a universal joint, a constant-velocity joint, or the like can be used to terminate the transmission section to the head 260.

[0047] Externally, the motor 100 includes a housing 102 defining an internal bore 104 in which the elongated shaft 200 is positioned. In the present configuration of Fig. 2A in which the elongated shaft 200 includes all of the noted integrally-formed sections, the housing 102 has a plurality of separate sections 1 10, 120, 130, and 160 inserted on the elongated shaft 200 and interconnected to one another. In particular, the separate housing sections include a top sub 1 10 inserted on the stem 210, a stator housing 120 inserted on the rotor body 220, a shaft housing 130 inserted on the shaft body 230, and a bearing housing 160 inserted on the head 260. (Any given one of these housing sections may or may not overlap other adjacent portions of the elongated shaft 200.)

[0048] The various housing connections can be threaded connections. However, the housing connections could also be welded, brazed, compression fit, or the like, and other type of connections can be used that are not necessarily suited for disassembly. As will be appreciated, in other configurations in which one or more separate sections of the elongated shaft 200 are used, one or more of the separate sections of the housing 102 can be integrated or combined with one another as assembly may allow.

[0049] At the proximal end in the current configuration of Fig. 2A, the top sub 1 10 couples to uphole drilling components, such as drillstring, stabilizer, or collar (not shown) of the bottom hole assembly. The top sub 1 10 includes a seat 1 12 for engagement with the rotor catch 212 should portions of the housing 102 become disconnected during operation. This can prevent lower portion of the drilling motor 100 detaching completely from the drillstring and lodging in the borehole. [0050] The stator housing 120 has a stator 122 with the various lobes disposed therein to form the power section of the motor 100. As is common, the stator 122 can be composed of an elastomer disposed in the bore of the housing 120 and defining the various lobes. (Any suitable number and configuration of lobes could be used for the purposes of the drilling motor 100.)

[0051] The shaft housing 130 can use one or more housing members that can extend from the stator housing 120 depending on the desired configuration of the motor 100. For example, the motor 100 can have a fixed bend, which can define a particular angle for the purposes of directional drilling according to techniques known in the art. To accommodate assembly and to configure the motor 100 as desired, the stator housing 130 acts as an adapter connected to a fixed bend housing 140. (The bend in the fixed bend housing 140 is not shown here.) In an alternative arrangement, features of the fixed bend housing 140 can be integrated into the stator housing 130 as one housing component.

[0052] Overall, the motor 100 can be easily configured using a different fixed bend housing 140, or the housing 140 may include an adjustable bend mechanism, such as found on bent subs for mud motors. Also, the bend may be press-formed into the fixed bend housing 140 to eliminate machine turning on two axes and to minimize material wastage. In fact, multiple bends can be press-formed into one or more of the housing sections of the drilling motor 100. A pipe bending assembly with opposing roller clamps can be used to press form the bend. Ideally, the press-formed bend(s) in the housing 102 will be formed after the drilling motor's assembly as one of the final manufacturing steps. In general, the bend in the drilling motor 100 may be about 3-degrees or so.

[0053] Beyond the fixed bend housing 140, the motor housing 102 includes a number of components for accommodating a bearing assembly 170 of the motor 100 disposed in between the head 260 and a bearing section of the housing 102. In particular, a union housing 150 attaches to the fixed bend housing 140. The union housing 150 interconnects a bearing housing 160 to the fixed bend housing 140 and separates an annular space between the fixed bend housing 140 and the shaft body 230 from the bearing assembly 170.

[0054] The bearing housing 160 connects to the union housing 150 and contains the bearing assembly 170, which supports the head 260 at the downhole end of the motor 100. The bearing assembly 170 can provide radial and/or axial support of the head 260. In general, the bearing assembly 170 can have conventional ball bearings, journal bearings, polycrystalline diamond (PDC) bearings, or the like. In turn, the head 260 couples to the other components including the drill bit (not shown). For instance, the bit joint 190 fits separately to head 260, and a radial sleeve 180 fits between the bit joint 190 and the lower end of the bearing housing 160.

[0055] As shown in Fig. 2A, the elongated shaft 200 defines an internal bore or passageway 202 at least partially therethrough for delivering fluid from the motor's annular space and out of the head 260 to the bit joint 190 and drill bit (not shown). In the present example, the internal bore 202 passes all the way through from the proximal end to the distal end, extending through the elongated shaft 200 from the catch 212 all the way to the drive head 260. The passageway 202 can be used for passage of drilling mud, conductors for downhole electronics, or the like. The drilling motor 100 is preferably mud-lubricated, allowing some of the drilling fluid to pass into the bearing assembly 170. Yet, cross-ports 204 let the drilling fluid from around the shaft body 130 to pass into the drive head 260, where the fluid can continue on to the drill bit (not shown).

[0056] For example, at least some of the drilling mud flowing from the drill string entering the motor's internal bore 104 can pass through this internal passageway 202 to the drill bit (not shown) toward the distal end of the motor 100. Additionally, at least some of the drilling mud also flows external to the elongated shaft 200 in the annular space between the rotor body 220 and the stator housing 120. The cross ports 204 on the elongated shaft 200 near the head 260 may then allow for passage of drilling mud outside the shaft 200 to enter the passageway 202.

[0057] During use, the motor 100 deploys in a borehole from a drilling rig (not shown). Mud flow through the motor 100 from the drill string operates the motor 100 to rotate the drill bit (not shown) connected beyond the bit box connection 190 on the end of the motor 100 so the motor 100 can drill the borehole during operation. The drillstring can also or separately impart rotation to the motor 100 for drilling straight ahead, or the drillstring may not be rotated so the bend in the motor 100 can be oriented for

directional drilling while the drill bit drills ahead under the power of the drilling motor 100.

[0058] As noted, the elongated shaft 200 is rotatable in the housing 102 with the flow of the drilling fluid in between the rotor body 220 and the stator housing 120. Downhole flowing drilling fluid rotates the rotor body 220 within the stator 122. In turn, the rotor body 220 rotates the integrally connected shaft body 230, which itself is integrally connected to the head 260 supported by the bearing assembly 170. The shaft body 230 transmits power from the rotor body 220 to the head 260 and converts elliptical or orbital motion at the rotor body 220 to rotational motion at the head 260, which rotates in the bearing assembly 170.

[0059] At the downhole end of the motor 100 as noted, the bearing assembly 170 supports the head 260. The bearing assembly 170 can provide radial and/or axial support of the head 260. Although the bearing assembly 170 can have conventional ball bearings, journal bearings, PDC bearings, or the like, the bearing assembly 170 is preferably of a compact nature that facilitates assembly while providing the necessary axial and/or radial thrust control.

[0060] In particular and as shown in more detail in Fig. 2B, the bearing assembly 170 is disposed in the annular space between the head 260 and a portion of the housing (namely, the bearing housing 160). The bearing assembly 170 includes a stack of inner race rings 172a and outer race rings 172b that carry ball bearings 174. The bearing assembly 170 is held between opposing shoulders 155, 165 associated with the housing 102 as well as between opposing shoulders 195, 265 associated with the elongated shaft 200.

[0061] To retain the bearing assembly 170 at its uphole end, for example, a mandrel spacer or sleeve 152 installed on the head 260 has an upper end engaging a shoulder 265 on the head 260. (As noted previously, this drilling motor 100 is mud lubricated, allowing some of the drilling fluid to pass into the bearing assembly 170. To that end, the sleeve 152 can provide a flow passage/restriction to permit/restrict flow between the transmission section 107 and the bearing assembly 170.)

[0062] One or more upper springs 154a, such as a set of Belleville springs, are installed on the head 260 against the lower end of the sleeve 152. A mandrel shim 156a installs on the head 260 between the assembly 170 and the upper springs 154a, while a housing shim 156a' fits between the assembly 170 and a shoulder 155 of the union housing 150.

[0063] To retain the assembly 170 at its downhole end, one or more lower springs 154b, such as a set of a set of Belleville springs, are installed in the bearing housing 160 against the lower end of the assembly 170. A split ring compressor 156b fits against the lower springs 154b, and a split ring lower catch 158 fits between the compressor 156b and an internal shoulder 165 of the bearing housing 160. This feature acts as a catch to reduce parts left downhole if fracture occurs in the elongated shaft 200.

[0064] The outer race rings 172b of the stacked assembly 170 are

positionally/longitudinally fixed by the shoulder 155 of the union housing 150 via the housing shim 156a', but are positionally/longitudinally biased by the lower springs 154b. The inner race rings 172a of the stacked assembly 170 are positionally/longitudinally fixed by a shoulder 195 of the joint 190, but are positionally/longitudinally biased by the upper springs 154a.

[0065] The bearing assembly 170 of Fig. 2B in the current configuration is used with the elongated shaft 200 having each the integrally-formed sections 210, 220, 230, and 260 as noted. It is possible that the bearing assembly 170 can have benefits when used with the elongated shaft 200 have other combinations with more or less of these sections or even when used with an elongated shaft having all separate components coupled together in conventional ways.

[0066] With the elongated shaft 200 of the drilling motor 100 having the integrally formed sections noted above in Fig. 2A and with the bearing assembly 170 having the compact configuration noted above in Fig. 2B, assembling the drilling motor 100 involves inserting the separate sections of the housing 102 on the elongated shaft 200 and interconnecting the separate sections to one another. The bearing assembly 170 is also installed in between the head 260 and the bearing housing 160.

[0067] For example, Figs. 3A-3F illustrate portions of the drilling motor 100 during stages of assembly. As shown in Fig. 3A, the shaft housing 130, the fixed bend housing 140, and the union housing 150 slide independently on the elongated shaft 200, which in this case has the integrally-formed sections noted. The bearing assembly 170 slides on the head 260 of the elongated shaft 200. As shown in Figs. 3B-3C, the lower catch split ring and compressor 158 install in the bearing housing 160, which slides on the bearing assembly 170 and connects to the union housing 150. The bit box joint 190 having the sleeve 180 threads onto the head 260.

[0068] As shown in Fig. 3D, the fixed bend housing 140 connects to the union housing 150, and the shaft housing 130 connects to the fixed bend housing 140, which is connected to the union housing 150. The stator housing 120 slides onto the rotor body 220 of the elongated shaft 200 from the other end and connects to the shaft housing 130. As shown in Fig. 3E, the top sub 1 10 connects to the upper end of the stator housing 120, and the cap 212 affixes to the shaft's stem 210. For example, the rotor catch cap 212 is inserted through the top sub 1 10 and threads in blind using a socket extension tool onto the stem 210.

[0069] Finally, Fig. 3F shows the full assembly. All of the external components are separately sectioned, but the elongated shaft 200 of the integrated rotor inside the motor 100 is not. The interconnections of the separate housing sections 1 10, 120, 130, 140, 150, and 160 to one another can use one or more of threaded, welded, brazed, adhered, and compression fitted connections between the separate sections. For example, the housing sections 1 10, 120, 130, 140, 150, and 160 can utilizes permanent housing connections, which can be accomplished by bonding threaded connections using brazing, welding, adhesive, and the like. Alternatively, rotary shouldered housing connections may use a stir friction, butt, or taper weld around part or all of the

circumference. Because the motor 100 is intended for single or limited use, the connections do not necessarily need to be uncoupleable.

[0070] The processes for building/assembling the drilling motor 100 is simplified over what is currently required for assembly of an existing drilling motor. Preferably, external features are not used on the motor 100 to thread on lower stabilizers, blades, pads, or the like. Instead, any of these features can be already integrated into the housing sections or added using additive welding.

[0071] Preferably as shown in Fig. 3F and noted with respect to Fig. 2A, the upper transition 232 between the rotor body 220 and the transmission shaft 230 is integrally- formed. In particular, Fig. 4A shows an upper portion of the motor 200 having the upper transition 232 between the rotor body 220 and the transmission shaft 230. This upper transition 232 is integrally-formed with the rotor body 220 and the transmission shaft 230 and transitions the orbital or elliptical motion of the rotor body 220 to a more rotational motion of the transmission shaft 230. The upper transition 232 can be similar in diameter to the remainder of the transmission shaft 230, or the upper transition 232 may include a taper or other profile from the wider rotor body 220 to the flexible transmission shaft 230. Having the integrally-formed connection at the upper transition 232 provides strength to the elongated shaft 200 where the elliptical motion from the rotor body 220 first translates to the circular rotation provided by the transmission shaft 230.

[0072] As shown previously in Fig. 2A, the lower transition 234 between the

transmission shaft 230 and the head 260 can also preferably be integrally-formed. This lower transition 234, however, can include a jointed connection. For example, Fig. 4B-1 shows a jointed connection in the form of a shrink fit, an interference fit, box-pin connection, or the like at the lower transition 234 from the transmission shaft 230 to a separate drive head 270. As particularly shown, an end 236 of the transmission shaft 230 can shrink fit or press with an interference fit into an adapter 276 of the separate drive head 270.

[0073] In another alternative, Fig. 4B-2 shows another jointed connection in the form of a continuous velocity or universal joint at the lower transition 234. In this particular example, knuckles 238 (or separate bearings) on the transmission shaft 230 can fit in sockets 278 of a separate drive head 270. To protect the bearing surfaces from eroding due to flow or from damage due to debris, an external flexible seal 275 can seal the space between the shaft 230 and the sockets 278. This external seal 275 keeps flow and debris from passing in the area between the knuckles 238 and sockets 278.

Additionally, for sealing the flow through the elongated shaft 200, an internal flexible seal or beam 277 can span the gap between the shaft 230 and the drive head 270 to seal off the internal flow through the internal passageway 202 of the elongated shaft 200. Teachings of such internal flexible seals can be found in U.S. Patent Pub.

2015/0053485, which is incorporated herein by reference.

[0074] Finally, although not expressly illustrated, it will be appreciated with the benefit of the present disclosure that the upper transition 232 can have a jointed connection, such as a shrink fit, an interference fit, box-pin connection, continuous velocity joint, universal joint, or the like. In fact, the upper transition 232 can use a reverse of the arrangements in Fig. 4B-1 and 4B-2. This jointed connection at the upper transition 232 can be used with another jointed connection at the lower transition 234 (as in Figs. 4B-1 and 4B-2) or can be used with the integrally-formed transition 234 (as disclosed herein with reference to Fig. 2A). Various combinations are possible along these teachings.

[0075] In the previous examples, a separate box joint (i.e., joint 190 in Fig. 2A, 3B, etc.) is provided for connecting to a pin of a drill bit. As an alternative, a drill bit for the disclosed motor 100 may connect directly to the integral head 260 (or separate drive head 270) of the elongated shaft 200 so that a separate box joint is not needed. For example, Fig. 5A shows a drill bit 282 for the motor 100 having an integrated box connection 280 in an unassembled state for threading to the pin end of the head 260 outside the bearing housing 160. Fig. 5B illustrates an assembled view of the drilling motor 100 having the integrated drill bit 282.

[0076] The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.

[0077] In exchange for disclosing the inventive concepts contained herein, the

Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.

Claims

WE CLAIM:

1. A drilling motor operated with flow of drilling fluid therethrough, the motor comprising:

an elongated shaft having integrally-formed sections between first and second ends, the integrally-formed sections at least including: a rotor body, and a shaft body extending with a first integral transition from the rotor body; a head extending from the shaft body;

a housing having a plurality of separate sections inserted on the elongated shaft and interconnected to one another, the housing including a stator; and a bearing assembly disposed in between the head and the housing,

wherein the elongated shaft is rotatable in the housing with the flow of the drilling fluid in between the rotor body and the stator.

2. The motor of claim 1 , where the separate sections of the housing comprises a top sub inserted on a stem of the elongated shaft, a stator section inserted on the rotor body and having the stator, a shaft section inserted on the shaft body, and a bearing section inserted on the head.

3. The motor of claim 2, wherein a portion of the shaft section inserted on the shaft body defines a bend.

4. The motor of claim 2 or 3, further comprising a cap separately connected to the stem and having a shoulder engageable with a seat of the top sub.

5. The motor of any one of claims 1 to 4, wherein the shaft body converts orbital motion at the rotor body to rotational motion at the head.

6. The motor of any one of claims 1 to 5, wherein the integrally-formed sections of the elongated shaft at least include a stem at a first end of the elongated shaft from which the rotor body extends.

7. The motor of any one of claims 1 to 6, wherein the integrally-formed sections of the elongated shaft at least include the head extending with a second integral transition from the shaft body.

8. The motor of any one of claims 1 to 6, comprising a jointed connection between the shaft body and the head.

9. The motor of claim 8, wherein the jointed connection comprises a first end of the shaft body shrunk fit to a second end of the head, a first end of the shaft body interference fit to a second end of the head, a first end of the shaft body connected by a continuous velocity joint to a second end of the head, or a first end of the shaft body connected by a universal joint to a second end of the head.

10. The motor of any one of claims 1 to 9, wherein housing connections of the separate sections of the housing to one another comprise one or more of threaded, welded, brazed, and compression fit connections.

1 1 . The motor of any one of claims 1 to 10, wherein the separate sections of the housing comprise:

a shaft section inserted on the shaft body;

a bearing section inserted on the head; and

a union section interconnecting the bearing section to the shaft section and

separating an annular space between the shaft section and the shaft body from the bearing assembly.

12. The motor of any one of claims 1 to 1 1 , further comprising:

a bit joint connected to the head and extending beyond the housing; and a bit connected to the bit joint.

13. The motor of claim 12, further comprising a radial sleeve disposed between the bit joint and the housing.

14. The motor of any one of claims 1 to 1 1 , further comprising a bit connected to the head and extending beyond the housing.

15. The motor of any one of claims 1 to 14, wherein the bearing assembly comprises a plurality of inner and outer race rings being stacked in between the head and the housing and carrying a plurality of ball bearings.

16. The motor of claim 15, wherein an uphole end the inner race rings are biased longitudinally with one or more upper springs; and wherein a downhole end of the inner race rings are fixed longitudinally with a lower shoulder associated with the elongated shaft.

17. The motor of claim 16, wherein the one or more upper springs are held longitudinally with a sleeve disposed on the head against an upper shoulder associated with the elongated shaft.

18. The motor of claim 15, 16, or 17, wherein a downhole end of the outer race rings are biased longitudinally with one or more lower springs; and wherein an uphole end of the outer race rings are fixed longitudinally with an upper shoulder associated with the housing.

19. The motor of claim 18, wherein the one or more lower springs are held longitudinally with a snap ring against a lower shoulder associated with the housing.

20. The motor of any one of claims 1 to 19, wherein the elongated shaft at least partially defines a fluid passageway delivering fluid from an annular space between the elongated shaft and the housing out of the head.

21 . The motor of claim 20, wherein the elongated shaft defines the fluid passageway from the first end to the second end, the fluid passageway defining a cross port communicating with the annular space.

A drilling motor operated with flow of drilling fluid therethrough, the motor prising:

an elongated shaft at least including a rotor body, a shaft body extending from the rotor body, and a head extending from the shaft body;

a housing disposed on the elongated shaft and at least including a stator; and a bearing assembly disposed in between the head and the housing, the bearing assembly comprising:

a plurality of inner and outer race rings stacked in between the head and the housing and carrying a plurality of ball bearings; a first uphole end of the outer race rings fixed longitudinally by a first upper shoulder associated with the housing;

a first downhole end of the inner race rings fixed longitudinally by a first lower shoulder associated with the elongated shaft; one or more upper springs longitudinally biasing a second uphole end of the inner race rings relative to a second upper shoulder associated with the elongated shaft; and

one or more lower springs longitudinally biasing a second lower end of the outer race rings relative to a second lower shoulder associated with the housing;

an elongated shaft having integrally-formed sections between first and second ends, the integrally-formed sections at least including a stem at the first end, a rotor body extending from the stem, a shaft body extending with a first integral transition from the rotor body, and a head extending with a second integral transition from the shaft body at the second end of the elongated shaft;

a housing having a plurality of separate sections inserted on the elongated shaft and interconnected to one another, the separate sections at least including a top sub inserted on the stem, a stator section inserted on the rotor body, a shaft section inserted on the shaft body, and a bearing section inserted on the head; and

a bearing assembly disposed in between the head and the bearing section, wherein the elongated shaft is rotatable in the housing with the flow of the drilling fluid in between the rotor body and the stator section.

24. A method of assembling a drilling motor operated with flow of drilling fluid therethrough, the method comprising:

providing an elongated shaft of the drilling motor having integrally-formed

sections between first and second ends, the integrally-formed sections at least including a stem at the first end, a rotor body extending from the stem, a shaft body extending from the stem, and a head extending from the shaft body at the second end;

inserting a plurality of separate sections of a housing on the elongated shaft and interconnecting the separate sections to one another; and

installing a bearing assembly in between the head of the elongated shaft and a bearing section of the separate sections.

25. The method of claim 24, comprising press-forming at least one bend in a portion of the drilling motor either before or after assembly of the drilling motor is completed.

26. The method of claim 24 or 25, comprising adding one or more stabilizers externally to one or more portions of the drilling motor using weld deposition.

27. The method of claim 24, 25, or 26, comprising welding one or more of the interconnections of the separate sections of the housing together.