CA2879905A1

CA2879905A1 - Eccentric adjustment coupling for mud motors

Info

Publication number: CA2879905A1
Application number: CA2879905A
Authority: CA
Inventors: William Murray; Samuel COLLETTE
Original assignee: Smith International Inc
Current assignee: Smith International Inc
Priority date: 2012-05-18
Filing date: 2013-05-17
Publication date: 2013-11-21
Also published as: CN104411912A; EP2850275A1; US20150167390A1; RU2014151367A; CN104411912B; WO2013173785A1; EP2850275A4

Abstract

According to one aspect, there is provided a drilling motor assembly having a power section configured to generate torque, a transmission section coupled to the power section, and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit. The transmission section includes a housing assembly having a bore formed therethrough, the housing assembly having a central axis defined therethrough and the bore having a central axis defined therethrough, in which the central axis of the bore is radially offset from the central axis of the housing assembly.

Description

ECCENTRIC ADJUSTMENT COUPLING FOR MUD MOTORS
BACKGROUND
Technical Field 100011 Embodiments disclosed herein relate generally to drilling motors having a transmission section for transmitting torque from a power section to a bearing section.
More specifically, the embodiments disclosed herein relate to a transmission section for drilling motors used in the oil and gas industry for drilling boreholes, particularly in applications requiring the transfer of large torque across the transmission section.
Background Art [0002] A drilling motor, also known as a mud motor, is a tool that is assembled on a drilling string that uses hydraulic force to turn a drill bit by pumping drilling fluid or air through the center of the drilling motor. The drilling motor includes three major sections:
a power section, a transmission section, and a bearing section. The power section is the section of a drilling motor that generates power by pumping fluid or air through a pump, such as a progressive cavity pump. This pump causes a rotation of the internal components, while the external components stay stationary, but the internal components could instead stay stationary while the external components rotate. The transmission section is the section of the drilling motor that translates the torque of the eccentric motion generated by the power section into the concentric motion that is used to drive the drill bit. The bearing section is the section of a drilling motor that handles all of the radial and axial loads produced by drilling operations. Drilling motors are designed such that a bent sub can be installed across the transmission section to be used to drill curved wells. An adjustable bent housing assembly is commonly used in lieu of a bent sub and allows a user to adjust the bend angle of the drilling motor while on the rig floor. Both methods of bending the motor are used in conjunction with a measurement while drilling tool in order to control the direction and inclination of a drill bit. This allows the operator to control the exact location and path of a well bore.

[0003] Referring to FIG. 1, a cross-sectional view of a conventional transmission section of a drilling motor is shown. As shown, the transmission section includes an adjustable bent housing assembly 100 having a central axis 150 defined therethrough.
Further, the adjustable bent housing assembly 100 has a bore 104 fonned therethrough and a transmission shaft 110 disposed within the bore 104 of the adjustable bent housing assembly 100. The transmission shaft 110 may be used to transmit torque generated from a power section of the drilling motor to a bearing section of the drilling motor. As shown, the bore 104 is a concentric bore that is formed through a center of the adjustable bent housing assembly 100. As such, a central axis (not shown) of the bore 104 is collinear with the central axis 150 of the adjustable bent housing assembly 100.
Furthettnore, as shown, insufficient clearance and potential interference exists between the transmission shaft 110 and an inner surface 106 of the adjustable bent housing assembly 100.
SUMMARY

[0004] According to one aspect, there is provided a drilling motor assembly having a power section configured to generate torque, a transmission section coupled to the power section, and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit. The transmission section includes a housing assembly having a bore formed therethrough, the housing assembly having a central axis defined therethrough and the bore having a central axis defined therethrough, in which the central axis of the bore is radially offset from the central axis of the housing assembly.

[0005] According to another aspect, there is provided a drilling motor assembly having a power section configured to generate torque, a transmission section coupled to the power section, and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit. The transmission section includes an adjustable housing assembly having a first sub coupled to a second sub and a bore fottned therethrough, the first sub having a first central axis defined therethrough, the second sub having a second central axis defined therethrough. The bore fanned through the adjustable housing assembly includes a first bore and a second bore, in which the first bore is fottned through the first sub and the second bore is faulted through the second sub, the first bore having a first central axis defined therethrough and the second bore having a second central axis defined therethrough. The first central axis of the first sub is radially offset from the first central axis of the first bore, in which the second central axis of the second sub is radially offset from the second central axis of the second bore.

[0006] According to another aspect, there is provided a method of manufacturing a drilling motor assembly, the method including foiming a bore through an adjustable housing assembly, the adjustable housing assembly having a first sub coupled to a second sub and a bore foimed therethrough, the first sub having a first central axis defined therethrough and the second sub having a second central axis defined therethrough. The bore formed through the adjustable housing assembly includes a first bore and a second bore, in which the first bore is formed through the first sub and the second bore is foimed through the second sub, the first bore having a first central axis defined therethrough and the second bore having a second central axis defined therethrough. The first central axis of the first sub is radially offset from the first central axis of the first bore, in which the second central axis of the second sub is radially offset from the second central axis of the second bore.

[0007] According to another aspect, there is provided a method of using a drilling motor assembly, the method including disposing the drilling motor assembly having a power section, a transmission section, and a bearing section downhole and transmitting torque from the power section to the bearing section through the transmission section. The transmission section includes an adjustable housing assembly having a central axis defined therethrough and a bore fanned therethrough, the bore having a central axis defined therethrough. The central axis of the bore is radially offset from the central axis of the adjustable housing assembly.

[0008] Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 shows a cross-sectional view of a conventional transmission section of a drilling motor.

[0010] FIG. 2 shows a cross-sectional view of an adjustable housing assembly of a transmission section according to embodiments disclosed herein.

[0011] FIG. 3 shows a cross-sectional view of a transmission section of a drilling motor according to embodiments disclosed herein.

DETAILED DESCRIPTION

[0012] In one aspect, embodiments disclosed herein relate to a transmission section for drilling motors used in the oil and gas industry for drilling boreholes, particularly in applications requiring the transfer of large torque across the transmission section.
Embodiments of the present disclosure also relate to a transmission section of a drilling motor having a housing assembly, such as an adjustable housing assembly, having a bore folined therethrough that is eccentric from a center of the housing assembly, rather than being a concentric bore formed through the housing assembly. Illustrations of each of these embodiments are shown.

[0013] As power sections are evolving to be stronger, the transmission shafts that transfer torque to the driveshaft are being subjected to significantly greater torques.
The additional force or torque requires that the transmission shaft be designed with a larger shaft diameter than it was previously. This larger diameter forces the bore formed through the bent housing assembly to be larger as well. This larger bore foimed through the housing assembly drastically decreases the strength of the housing assembly, as the outer diameter of the housing assembly must remain constant in order to fit within a specifically-sized borehole.

[0014] Certain terms are used throughout the following description and claims refer to particular features or components. As those having ordinary skill in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between. components or features that differ in name but not function. The figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic fatal_ and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0015] In the following discussion and in the claims, the terms "including" and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to ...." Further, the terms "axial" and "axially"
generally mean along or substantially parallel to a central or longitudinal axis, while the terms "radial"
and "radially" generally mean perpendicular to a central, longitudinal axis.

[0016] According to one or more embodiments, a drilling motor assembly may include a power section configured to generate torque, a transmission section coupled to the power section, and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit. In one or more embodiments, the power section may include a rotor that is configured to generate torque. In one or more embodiments, the transmission section may include a housing assembly having a bore Ruined therethrough, the housing assembly having a central axis defined therethrough and the bore having a central axis defined therethrough, in which the central axis of the bore is radially offset from the central axis of the housing assembly. In one or more embodiments, the bore formed through the housing assembly may be an eccentric bore that is formed eccentric to a center of the housing assembly, e.g., eccentric to an outer diameter or outer circumference of the housing assembly. For example, in one or more embodiments, the bore foinied through the housing assembly may be an eccentric bore that is formed through the housing assembly, in which the central axis of the bore is radially offset from the central axis of the housing assembly. In other words, the bore that is foimed through the housing assembly may not be concentric with the outer diameter of outer circumference of the housing assembly, which may result in the housing assembly having a variable wall thickness.

[0017] Further, according to one or more embodiments, the transmission section may include a transmission shaft disposed within the bore of the housing assembly.
In one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly may provide clearance between the transmission shaft and an internal surface of the housing assembly. In one or more embodiments, the transmission shaft may be configured to transfer torque generated by the power section of the drilling motor to the bearing section of the drilling motor, which may be coupled to a drill bit.

[0018] In one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly is up to 5mm. However, those having ordinary skill in the art will appreciate that in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly may be any amount greater than or less than 5mm. For example, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly may be lmm, 3mm, 5mm, 6mm, 1 Omm, or more. Further, in one or more embodiments, the housing assembly may be bent to a desired angle. Furthermore, as will be described below, in one or more embodiments, the housing assembly may be an adjustable housing assembly that may be bent to a desired angle.

[0019] Further, in one or more embodiments, a cross-section of the housing assembly may include a variable wall thickness. In other words, as a result of the radial offset between the central axis of the bore and the central axis of the housing assembly, in one or more embodiments, the thickness of the wall of the housing assembly may vary about the circumference of the housing assembly. In one or more embodiments, the thickness of the wall of the housing assembly may be measured by a distance between an outer diameter or radius and an inter diameter or radius of the housing assembly.

[0020] As a result of the radial offset between the central axis of the bore and the central axis of the housing assembly, in one or more embodiments, a transmission shaft having a larger diameter may be used. In one or more embodiments, the diameter of the transmission shaft may be increased by up to 50%. However, those having ordinary skill in the art will appreciate that the diameter of the transmission shaft may be increased by more than 50% as a result of a radial offset between the central axis of the bore and the central axis of the housing assembly. In one or more embodiments, the diameter of the transmission shaft may be increased by 30% or more.

[0021] A larger-diameter transmission shaft may be able to withstand a greater amount of torque generated by the power section of the drilling motor before failure when compared to a smaller-diameter transmission shaft of the same material. In other words, in one or more embodiments, radial offset between the central axis of the bore and the central axis of the housing assembly may allow the outer diameter of the housing assembly and the diameter of the bore formed through the housing assembly to remain constant, while being able to accommodate for a larger-diameter transmission shaft to be used and disposed within the bore formed through the housing assembly and while still maintaining sufficient clearance between the transmission shaft and an inner surface of the housing assembly.

[0022] Thus, the radial offset between the central axis of the bore and the central axis of the housing assembly may allow for a larger ratio between the diameter of the transmission shaft and the outer diameter of the housing assembly, i.e., the outer diameter of the transmission section of the drilling motor. In one or more embodiments, the ratio between the diameter of the transmission shaft and the outer diameter of the housing assembly may be 1:2.313.

[0023] Further, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly may allow for a larger ratio between the diameter of the transmission shaft and the diameter of the bore formed through the housing assembly, e.g., the diameters of each of the first bore and the second bore. In one or more embodiments, the ratio between the diameter of the transmission shaft and the diameter of the bore may be 1:1.314.

[0024] Referring to FIG. 2, a cross-sectional view of a housing assembly 200, specifically an adjustable housing assembly, of a transmission section of a drilling motor, in accordance with embodiments disclosed herein, is shown. As shown, the housing assembly 200 is a multi-piece assembly and includes a first sub 201 coupled to a second sub 202. Those having ordinary skill in the art will appreciate that more or less than two subs may be included in the housing assembly 200. For example, in one or more embodiments, one, two, three, four, or more subs may be included in the housing assembly 200. In one or more embodiments, the first sub 201 may be threadably coupled to the second sub 202. In one or more embodiments, in which a housing assembly includes only a single sub, the single-piece housing assembly may be used as described above and may also be bent to a desired angle. Alternatively, in one or more embodiments, each of the first sub 201 and the second sub 202 may be threadably coupled to either side of an indexing sleeve (not shown), in which either of the first sub 201 or the second sub 202 may be rotated relative to the indexing sleeve to create an offset angle between the first sub 201 and the second sub 202.

[0025] For example, as shown, the first sub 201 has a first central axis 251 defined therethrough, and the second sub 202 has a second central axis 252 defined therethrough.
In one or more embodiments, the first sub 201 may be coupled to the second sub such that no offset exists between the first sub 201 and the second sub 202.
In other words, in one or more embodiments, the first sub 201 may be coupled to the second sub 202 such that the first central axis 251 of the first sub 201 may be collinear with the second central axis 252 of the second sub 202.

[0026] Alternatively, in one or more embodiments, the first sub 201 may be coupled to the second sub 202 such that an offset angle a exists between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202. In other words, in one or more embodiments, the housing assembly 200 may be an adjustable housing assembly that may be bent such that the offset angle a exists between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202. In one or more embodiments, the offset angle a may be any angle up to three degrees.
However, those having ordinary skill in the art will appreciate that the offset angle a may be any angle greater than or less than three degrees. For example, in one or more embodiments, the offset angle a between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202 may be zero, one, two, three, four, five, or more degrees. Further, those having ordinary skill in the art will appreciate that the housing assembly 200 may be bent such that the offset angle is any fraction of a degree.

[0027] Further, in one or more embodiments, the offset angle a may be adjustable. For example, in one or more embodiments, the offset angle a between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202 may be adjusted between zero and three degrees.

[0028] For example, in one or more embodiments, the connection between the first sub 201 and the second sub 202 may be configured such that the offset angle a may be adjusted by rotating the first sub 201 relative to the second sub 202, or alternatively rotating the second sub 202 relative to the first sub 201, until a desired offset angle a is achieved. For example, in one or more embodiments, the connection between the first sub 201 and the second sub 202 may include pitched threads that may allow the offset angle a to be adjusted by rotating the first sub 201 relative to the second sub 201, or by rotating the second sub 202 relative to the first sub 201. Further, in one or more embodiments, one of the first sub 201 or the second sub 202 may include a tapered connecting portion, e.g., a tapered threaded pin connection, that may allow the first sub 201 to be offset at the angle a relative to the second sub 202. However, those having ordinary skill in the art will appreciate that the connection between the first sub 201 and the second sub 202 is not limited only to a pitched threaded connection and may be any connection means known in the art that may allow a predetermined offset angle a to be achieved between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202.

[0029] As discussed above, one or more embodiments may include the indexing sleeve (not shown), which may be disposed between the first sub 201 and the second sub 202, may be used to assist in achieving a desired offset angle a between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202. For example, in one or more embodiments, the indexing sleeve may include markings denoting fraction-of-a-degree increments for orientation reference between zero and three degrees. As such, in one or more embodiments, each of the first sub 201 and the second sub 202 may be threadably coupled to either side of the indexing sleeve, which may be used to create an offset angle a between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202, and to denote the offset angle a to a user so that a user may achieve an exact, predetermined offset angle.

[0030] Further, in one or more embodiments, a bore may be formed through the housing assembly 200. As shown, the housing assembly 200 includes the first sub 201 and the second sub 202. Further, as shown, the first sub 201 has a first bore 204 formed therethrough, and the second sub 202 has a second bore 205 formed therethrough. As discussed above, in one or more embodiments, the housing assembly 200 may be bent such that an offset angle a exists between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202. Alternatively, in one or more embodiments, the housing assembly 200 may completely straight, i.e., the offset angle a between the first central axis 251 of the first sub 201 and the second central axis 252 of the second sub 202 is zero, and a single bore may be formed through the first sub 201 and the second sub 202.

[0031] Still referring to FIG. 2, the first bore 204 has a first central axis 261 defined therethrough, and the second bore 205 has a second central axis 262 defined therethrough. As shown, the first central axis 261 of the first bore 204 may be radially offset from the first central axis 251 of the first sub 201 by a distance d.
Similarly, the second central axis 262 of the second bore 205 may be radially offset from the second central axis 252 of the second sub 202. As discussed above, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the housing assembly may be up to 5mm. However, those having ordinary skill in the art will appreciate that the radial offset between the central axis of the bore and the central axis of the housing assembly may include lower limits of 0.5mm, lmm, 2mm, 3mm, and 4mm and upper limits of 1 mm, 2mm, 3mm, 4mm, and 5mm, in which any lower limit described above can be used with any upper limit.

[0032] Similarly, the radial offset between the first central axis 261 of the first bore 204 and the first central axis 251 of the first sub 201 may be up to 5mm, and the radial offset between the second central axis 262 of the second bore 205 and the second central axis 252 of the second sub 202 may be up to 5mm. In one or more embodiments, the radial offset between the first central axis 261 of the first bore 204 and the first central axis 251 of the first sub 201 may be equal to the radial offset between the second central axis 262 of the second bore 205 and the second central axis 252 of the second sub 202, which may be the distance d.

[0033] Those having ordinary skill in the art will appreciate that in one or more embodiments, the radial offset between the first central axis 261 of the first bore 204 and the first central axis 251 of the first sub 201 and/or the radial offset between the second central axis 262 of the second bore 205 and the second central axis 252 of the second sub 202 may be any amount greater than or less than 5mm. For example, in one or more embodiments, the radial offset between the first central axis 261 of the first bore 204 and the first central axis 251 of the first sub 201 and the radial offset between the second central axis 262 of the second bore 205 and the second central axis 252 of the second sub 202 may be 1 mm, 3mm, 5mm, 6mm, lOmm, or more. Alternatively, the first central axis 261 of the first bore 204 may be collinear with the first central axis 251 of the first sub 201, and the second central axis 262 of the second bore 205 may be collinear with the second central axis 252 of the second sub 202 such that the radial offset is zero.

[0034] Referring now to FIG. 3, a cross-sectional view of a transmission section of a drilling motor, in accordance with embodiments disclosed herein, is shown. In one or more embodiments, a drilling motor assembly may include a power section (not shown) configured to generate torque, a transmission section coupled to the power section, and a bearing section (not shown) coupled to the transmission section, the bearing section configured to couple to a drill bit.

[0035] As shown, the transmission section includes a housing assembly 300.
In one or more embodiments, the housing assembly 300 may be a multi-piece assembly and may include a first sub 301 coupled to a second sub 302. As discussed above, in one or more embodiments, the housing assembly 300 may be an adjustable housing assembly.
Those having ordinary skill in the art will appreciate that more or less than two subs may be included in the housing assembly 300. For example, in one or more embodiments, one, two, three, four, or more subs may be included in the housing assembly 300. In one or more embodiments, the first sub 301 may be threadably coupled to the second sub 302.
Alternatively, in one or more embodiments, each of the first sub 301 and the second sub 302 may be threadably coupled to either side of an indexing sleeve 303, in which the indexing sleeve 303 may be rotated to create an offset angle between the first sub 301 and the second sub 302.

[0036] As shown, the first sub 301 has a first central axis 351 defined therethrough, and the second sub 302 has a second central axis 352 defined therethrough. In one or more embodiments, the first sub 301 may be coupled to the second sub 302 such that no offset exists between the first sub 301 and the second sub 302. In other words, in one or more embodiments, the first sub 301 may be coupled to the second sub 302 such that the first central axis 351 of the first sub 301 may be collinear with the second central axis 352 of the second sub 302.

[0037] Alternatively, in one or more embodiments, the first sub 301 may be coupled to the second sub 302 such that an offset angle, e.g., the offset angle a shown in FIG. 2, exists between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302. In other words, in one or more embodiments, the adjustable housing assembly 300 may be bent such that the offset angle exists between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302. In one or more embodiments, the offset angle may be any angle up to three degrees.
However, those having ordinary skill in the art will appreciate that the offset angle between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302 may be any angle greater than or less than three degrees.
For example, in one or more embodiments, the offset angle between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302 may be zero, one, two, three, four, five, or more degrees. Further, those having ordinary skill in the art will appreciate that the adjustable housing assembly 300 may be bent such that the offset angle is any fraction of a degree.

[0038] As discussed above, in one or more embodiments, the offset angle may be adjustable. For example, in one or more embodiments, the offset angle formed between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302 may be adjusted between zero and three degrees.

[0039] For example, in one or more embodiments, the connection between the first sub 301 and the second sub 302 may be configured such that the offset angle, e.g., the offset angle a shown in FIG. 2, may be adjusted by rotating the first sub 301 relative to the second sub 302, or alternatively rotating the second sub 302 relative to the first sub 301, until a desired offset angle is achieved. For example, in one or more embodiments, the connection between the first sub 301 and the second sub 302 may include pitched threads that may allow the offset angle to be adjusted by rotating the first sub 301 relative to the second sub 302, or by rotating the second sub 302 relative to the first sub 301. Further, in one or more embodiments, one of the first sub 301 or the second sub 302 may include a tapered connecting portion, e.g., a tapered threaded pin connection, that may allow the first sub 301 to be offset at an angle relative to the second sub 302.
However, those having ordinary skill in the art will appreciate that the connection between the first sub 301 and the second sub 302 is not limited only to a pitched threaded connection and may be any connection means known in the art that may allow a predetelinined offset angle to be achieved between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302.

[0040] As discussed above, one or more embodiments may include the indexing sleeve 303, which may be disposed between the first sub 301 and the second sub 302, may be used to assist in achieving a desired offset angle between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302. For example, in one or more embodiments, the indexing sleeve 303 may include markings denoting fraction-of-a-degree increments for orientation reference between zero and three degrees. As such, in one or more embodiments, each of the first sub 301 and the second sub 302 may be threadably coupled to either side of the indexing sleeve 303, which may be used to create an offset angle between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302, and to denote the offset angle to a user so that a user may achieve an exact, predetermined offset angle.

[0041] Further, in one or more embodiments, a bore may be foimed through the adjustable housing assembly 300. As shown, the adjustable housing assembly 300 includes the first sub 301 and the second sub 302. Further, as shown, the first sub 301 has a first bore 304 formed therethrough, and the second sub 302 has a second bore 305 formed therethrough. As discussed above, in one or more embodiments, the adjustable housing assembly 300 may be bent such that an offset angle, e.g., the offset angle a shown in FIG. 2, exists between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302. Alternatively, in one or more embodiments, the adjustable housing assembly 300 may completely straight, i.e., the offset angle between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302 is zero, and a single bore may be fomied through the first sub 301 and the second sub 302.

[0042] As shown, the first bore 304 has a first central axis 361 defined therethrough, and the second bore 305 has a second central axis 362 defined therethrough. As shown, the first central axis 361 of the first bore 304 may be radially offset from the first central axis 351 of the first sub 301, e.g., by a distance d shown in FIG. 2. Similarly, the second central axis 362 of the second bore 305 may be radially offset from the second central axis 352 of the second sub 302. As discussed above, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly may be up to 5mm. Similarly, the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 may be up to 5mm, and the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302 may be up to 5mm. In one or more embodiments, the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 may be equal to the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302, which may be any distance up to 5mm, as discussed above.

[0043] Those having ordinary skill in the art will appreciate that in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly may be any amount greater than or less than 5mm. For example, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly may be lmm, 3mm, 5mm, 6mm, 10mm, or more. Alternatively, the first central axis 361 of the first bore 304 may be collinear with the first central axis 351 of the first sub 301, and/or the second central axis 362 of the second bore 305 may be collinear with the second central axis 352 of the second sub 302 such that the radial offset is zero.

[0044] Still referring to FIG. 3, in one or more embodiments, the transmission section may include a transmission shaft 310 disposed within the bore of the adjustable housing assembly 300. As shown, the transmission shaft 310 is disposed within each of the first bore 304 formed through the first sub 301 and the second bore 305 formed through the second sub 302. In one or more embodiments, the transmission shaft 310 may be configured to transfer torque generated by the power section, e.g., a rotor shown on the left side of FIG. 3, of the drilling motor to the bearing section of the drilling motor shown on the right side of FIG. 3. In one or more embodiments, a drill bit (not shown) may be coupled to the bearing section, in which torque from the power section may be transferred through the transmission shaft 310 to the drill bit.

[0045] In one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300, e.g., the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 as well as the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302, may be sufficient to provide clearance between the transmission shaft 310 and an internal surface 306 of the adjustable housing assembly 300.

[0046] Further, in one or more embodiments, the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 as well as the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302 may be sufficient to provide clearance between the transmission shaft 310 and the internal surface 306 of the adjustable housing assembly 300 when the adjustable housing assembly 300 is bent such that an offset angle, e.g., the offset angle a shown in FIG. 2, is formed between the first central axis 351 of the first sub 301 and the second central axis 352 of the second sub 302.

[0047] In one or more embodiments, the clearance between the transmission shaft 310 and the internal surface 306 of the adjustable housing assembly 300 may be up to 5mm.

However, those having ordinary skill in the art will appreciate that the clearance between the transmission shaft 310 and the internal surface 306 of the adjustable housing assembly 300 may be any distance greater than or less than 5mm. For example, in one or more embodiments, the clearance between the transmission shaft 310 and the internal surface 306 of the adjustable housing assembly 300 may be up to 1 mm, 2mm, 3mm, 6mm, lOmm, or more, or within a range of any such values.

[0048] According to one or more embodiments, the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 as well as the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302 may allow a diameter of the transmission shaft 310 to be increased. In other words, the radial offset discussed above may allow a larger-diameter transmission shaft 310 to be used in the transmission section of the drilling motor.

[0049] In one or more embodiments, the diameter of the transmission shaft 310 may be increased by up to 30%, while the outer diameter of the adjustable housing assembly 300 and the diameter of the bore formed through the adjustable housing assembly 300 are unchanged. In other words, without changing the outer diameter of the adjustable housing assembly 300 or the diameter of the bore fonned through the adjustable housing assembly 300, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300 may allow a larger-diameter transmission shaft 310 to be used while still maintaining sufficient clearance between the transmission shaft 310 and the internal surface 306 of the adjustable housing assembly 300, even when the adjustable housing assembly 300 is bent, as described above.

[0050] Those having ordinary skill in the art will appreciate that the diameter of the transmission shaft 310 may be increased by more or less than 30%, while the outer diameter of the adjustable housing assembly 300 and the diameter of the bore formed through the adjustable housing assembly 300 are unchanged. For example, in one or more embodiments, the diameter of the transmission shaft 310 may be increased by 10%, 20%, 40%, 50%, or more, while the outer diameter of the adjustable housing assembly 300 and the diameter of the bore foimed through the adjustable housing assembly 300 are unchanged.

[0051] In one or more embodiments, a larger-diameter transmission shaft 310 may be able to withstand a greater amount of torque generated by the power section of the drilling motor before failure when compared to a smaller-diameter transmission shaft of the same material. In other words, in one or more embodiments, radial offset discussed above may allow the outer diameter of the adjustable housing assembly 300 and the diameter of the bore formed through the adjustable housing assembly 300 to remain constant, while being able to accommodate for a larger-diameter transmission shaft to be used and disposed within the bore formed through the adjustable housing assembly and while still maintaining sufficient clearance between the transmission shaft 310 and an inner surface 306 of the adjustable housing assembly 300.

[0052] Thus, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300 may allow for a larger ratio between the diameter of the transmission shaft 310 and the outer diameter of the adjustable housing assembly 300, i.e., the outer diameter of the transmission section of the drilling motor. In one or more embodiments, the ratio between the diameter of the transmission shaft 310 and the outer diameter of the housing assembly 300 may be 1:2.313. However, one or more embodiments may include other ratios between the diameter of the transmission shaft 310 and the outer diameter of the housing assembly 300.

[0053] Further, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300 may allow for a larger ratio between the diameter of the transmission shaft 310 and the diameter of the bore ft:limed through the adjustable housing assembly 300, e.g., the diameters of each of the first bore 304 and the second bore 305. In one or more embodiments, the ratio between the diameter of the transmission shaft and the diameter of the bore may be 1:1.314. However, one or more embodiments may include other ratios between the diameter of the transmission shaft and the diameter of the bore.

[0054] A larger ratio between the diameter of the transmission shaft 310 and the outer diameter of the adjustable housing assembly 300 and/or a larger ratio between the the diameter of the transmission shaft 310 and the diameter of the bore founed through the adjustable housing assembly may allow an outer diameter of a transmission section of a drilling motor to be minimized in order to fit within predetermined, specified borehole sizes, while increasing the torque threshold that the drilling motor is able to withstand by increasing the diameter of the transmission shaft 310.

[0055] The radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300 may allow the diameter of the transmission shaft 310 to be increased without increasing the diameter of the bore, e.g., the diameter of the first bore 304 and the second bore 305 formed through the adjustable housing assembly 300.
Increasing the diameter of the bore formed through the adjustable housing assembly 300 without also increasing the outer diameter of the adjustable housing assembly 300 may cause a wall-thickness of the adjustable housing assembly 300 to decrease.
Decreasing the wall-thickness of the adjustable housing assembly 300 may compromise the structural integrity of the adjustable housing assembly 300 under a load.

[0056] In one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300 may be skewed toward the high side of the bend, as the transmission shaft 310 may be skewed toward the high side of the bend if the adjustable housing assembly 300 is bent. For example, as shown, the second sub 302 is bent at an upward angle relative to the first sub 301.
As such, the first central axis 361 of the first bore 304 and the second central axis 362 of the second bore 305 are radially offset above the central axis 351 of the first sub 301 and the central axis 352 of the second sub 302, respectively, to accommodate the transmission shaft 310, which is skewed to a high side of the adjustable housing assembly 300 as a result of the bend.

[0057] According to another aspect, a method of manufacturing a drilling motor assembly may include forming a bore through an adjustable housing assembly, the adjustable housing assembly including a first sub coupled to a second sub and a bore foimed therethrough, the first sub having a first central axis defined therethrough and the second sub having a second central axis defined therethrough. In one or more embodiments, the bore formed through the adjustable housing assembly may include a first bore and a second bore, in which the first bore is formed through the first sub and the second bore is foimed through the second sub, the first bore having a first central axis defined therethrough and the second bore having a second central axis defined therethrough. In one or more embodiments, the first central axis of the first sub may be radially offset from the first central axis of the first bore, and in which the second central axis of the second sub is radially offset from the second central axis of the second bore.

[0058] As discussed above, in one or more embodiments, the adjustable housing assembly may have a bore formed therethrough, and the adjustable housing assembly may have a central axis defined therethrough and the bore may have a central axis defined therethrough, in which the central axis of the bore is radially offset from the central axis of the adjustable housing assembly.

[0059] Referring back to FIG. 3, the transmission section of the drilling motor may include the adjustable housing assembly 300, the adjustable housing assembly including the first sub 301 and the second sub 302. In one or more embodiments, the first sub 301 may have the first bore 304 ft:limed therethrough, and the second sub 302 may have the second bore 305 formed therethrough. In one or more embodiments, the first bore 304 has a first central axis 361 defined therethrough, and the second bore 305 has a second central axis 362 defined therethrough.

[0060] As shown, the first bore 304 may be fonned such that the first central axis 361 of the first bore 304 may be radially offset from the first central axis 351 of the first sub 301, e.g., by a distance d shown in FIG. 2. Similarly, the second bore 305 may be formed such that the second central axis 362 of the second bore 305 may be radially offset from the second central axis 352 of the second sub 302. As discussed above, in one or more embodiments, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly may be up to 5mm. Similarly, the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 may be up to 5mm, and the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302 may be up to 5mm. In one or more embodiments, each of the first bore 304 and the second bore 305 may be founed such that the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 may be equal to the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302, which may be any distance up to 5mm.

[0061] The method may also include coupling a power section configured to generate torque to a transmission section having the adjustable housing assembly.
Further, the method may include coupling a bearing section configured to couple with a drill bit to the transmission section having the adjustable housing assembly. As discussed above, in one or more embodiments, a cross-section of the adjustable housing assembly may include a variable wall thickness.

[0062] Further, as discussed above, the transmission section may include a transmission shaft, e.g., the transmission shaft 310, disposed within the bore of the adjustable housing assembly. As discussed above, the bore of the adjustable housing assembly may include a first bore and a second bore formed through the adjustable housing assembly, e.g., the first bore 304 formed through the first sub 301 and the second bore 305 formed through the second sub 302.

[0063] Furthermore, as discussed above, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300, e.g., the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 as well as the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302, may be sufficient to provide clearance between the transmission shaft 310 and an internal surface 306 of the adjustable housing assembly 300 while also allowing a larger ratio to exist between the diameter of the transmission shaft 310 and the outer diameter of the adjustable housing assembly 300 and/or a larger ratio to exist between the diameter of the transmission shaft 310 and the diameter of the bore formed through the adjustable housing assembly.

[0064] A larger ratio between the diameter of the transmission shaft 310 and the outer diameter of the adjustable housing assembly 300 and/or a larger ratio between the diameter of the transmission shaft 310 and the diameter of the bore fonned through the adjustable housing assembly may allow an outer diameter of a transmission section of a drilling motor to be minimized in order to fit within predetennined, specified borehole sizes, while increasing the torque threshold that the drilling motor is able to withstand by increasing the diameter of the transmission shaft 310.

[0065] According to another aspect, a method of using a drilling motor assembly may include disposing the drilling motor assembly having a power section, a transmission section, and a bearing section downhole, transmitting torque from the power section to the bearing section through the transmission section. In one or more embodiments, the transmission section may include an adjustable housing assembly having a central axis defined therethrough and a bore foimed therethrough, the bore having a central axis defined therethrough. In one or more embodiments, the central axis of the bore is radially offset from the central axis of the adjustable housing assembly.

[0066] As discussed above, in one or more embodiments, the adjustable housing assembly may include a first sub and a second sub, e.g., the first sub 301 and the second sub 302. Further, as discussed above, the bore formed through the adjustable housing assembly may include a first bore and a second bore formed through the adjustable housing assembly, e.g., the first bore 304 formed through the first sub 301 and the second bore 305 formed through the second sub 302.

[0067] Further, as discussed above, the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly 300, e.g., the radial offset between the first central axis 361 of the first bore 304 and the first central axis 351 of the first sub 301 as well as the radial offset between the second central axis 362 of the second bore 305 and the second central axis 352 of the second sub 302, may be sufficient to provide clearance between the transmission shaft 310 and an internal surface 306 of the adjustable housing assembly 300.

[0068] In one or more embodiments, having the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly may allow a larger-diameter transmissions shaft to be used. As discussed above, in one or more embodiments, the diameter of the transmission shaft may be increased by up to 30%, while the outer diameter of the adjustable housing assembly and the diameter of the bore formed through the adjustable housing assembly are unchanged. This larger-diameter transmission shaft may be used while still maintaining sufficient clearance between the transmission shaft and an internal surface of the adjustable housing assembly, even when the adjustable housing assembly is bent, as described above.

[0069] Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this invention.
Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words 'means for' together with an associated function.

Claims

What is claimed is:

1. A drilling motor assembly, comprising:
a power section configured to generate torque;
a transmission section coupled to the power section, comprising:
a housing assembly comprising a bore fanned therethrough, the housing assembly having a central axis defined therethrough and the bore having a central axis defined therethrough, wherein the central axis of the bore is radially offset from the central axis of the housing assembly; and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit.

2. The assembly of claim 1, wherein the transmission section comprises a transmission shaft disposed within the bore of the housing assembly.

3. The assembly of claim 2, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly provides clearance between the transmission shaft and an internal surface of the housing assembly.

4. The assembly of claim 1, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly is up to 5mm.

5. The assembly of claim 1, wherein a cross-section of the housing assembly comprises a variable wall thickness.

6. A drilling motor assembly, comprising:
a power section configured to generate torque;
a transmission section coupled to the power section, comprising:
a housing assembly comprising a bore formed therethrough, the housing assembly having a central axis defined therethrough and the bore having a central axis defined therethrough; and a transmission shaft disposed within the bore of the housing assembly, wherein the central axis of the bore is radially offset from the central axis of the housing assembly, wherein a ratio between the diameter of the transmission shaft and the outer diameter of the adjustable housing assembly is 1:2.313; and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit.

7. The assembly of claim 6, wherein a ratio between the diameter of the transmission shaft and the diameter of the bore formed through the adjustable housing assembly is 1:1.314.

8. The assembly of claim 6, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly provides clearance between the transmission shaft and an internal surface of the housing assembly.

9. The assembly of claim 6, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly is up to 5mm.

10. A drilling motor assembly, comprising:
a power section configured to generate torque;
a transmission section coupled to the power section, comprising:
an adjustable housing assembly comprising a first sub coupled to a second sub and a bore formed therethrough, the first sub having a first central axis defined therethrough, the second sub having a second central axis defined therethrough, wherein the bore formed through the adjustable housing assembly comprises a first bore and a second bore, wherein the first bore is formed through the first sub and the second bore is formed through the second sub, the first bore having a first central axis defined therethrough and the second bore having a second central axis defined therethrough, wherein the first central axis of the first sub is radially offset from the first central axis of the first bore, and wherein the second central axis of the second sub is radially offset from the second central axis of the second bore; and a bearing section coupled to the transmission section, the bearing section configured to couple to a drill bit.

11. The assembly of claim 10, wherein the adjustable housing assembly is configured to adjustably bend such that an offset angle is formed between the first central axis of the first sub and the second central axis of the second sub.

12. The assembly of claim 10, wherein the adjustable housing assembly is configured to adjustably bend such that an offset angle of up to 3 degrees is formed between the first central axis of the first sub and the second central axis of the second sub.

13. The assembly of claim 10, wherein the transmission section comprises a transmission shaft disposed within the bore of the adjustable housing assembly.

14. The assembly of claim 13, wherein the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly provides clearance between the transmission shaft and an internal surface of the adjustable housing assembly.

15. The assembly of claim 13, wherein the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly provides clearance between the transmission shaft and an internal surface of the adjustable housing assembly when the adjustable housing assembly is bent such that an offset angle is formed between the first central axis of the first sub and the second central axis of the second sub.

16. The assembly of claim 10, wherein the radial offset between each of the first central axis of the first sub and the first central axis of the first bore and the second central axis of the second sub and the second central axis of the second bore is up to 5mm.

17. The assembly of claim 13, wherein a ratio between the the diameter of the transmission shaft and outer diameter of the adjustable housing assembly is 1:2.313.

18. The assembly of claim 13, wherein a ratio between the diameter of the transmission shaft and the diameter of the bore formed through the adjustable housing assembly is 1:1.314.

19. A method of manufacturing a drilling motor assembly, the method comprising:
forming a bore through an adjustable housing assembly, the adjustable housing assembly comprising a first sub coupled to a second sub and a bore formed therethrough, the first sub having a first central axis defined therethrough and the second sub having a second central axis defined therethrough, wherein the bore formed through the adjustable housing assembly comprises a first bore and a second bore, wherein the first bore is formed through the first sub and the second bore is formed through the second sub, the first bore having a first central axis defined therethrough and the second bore having a second central axis defined therethrough, wherein the first central axis of the first sub is radially offset from the first central axis of the first bore, and wherein the second central axis of the second sub is radially offset from the second central axis of the second bore.

20. The method of claim 19, further comprising coupling a power section configured to generate torque to a transmission section having the adjustable housing assembly.

21. The method of claim 20 further comprising coupling a bearing section configured to couple with a drill bit to the transmission section having the adjustable housing assembly.

22. The method of claim 19, wherein a cross-section of the adjustable housing assembly comprises a variable wall thickness.

23. The method of claim 19, wherein the radial offset between each of the first central axis of the first sub and the first central axis of the first bore and the second central axis of the second sub and the second central axis of the second bore is up to 5mm.

24. The method of claim 19, wherein the transmission section comprises a transmission shaft disposed within the bore of the adjustable housing assembly.

25. The method of claim 24, wherein the radial offset between the central axis of the bore and the central axis of the adjustable housing assembly provides clearance between the transmission shaft and an internal surface of the adjustable housing assembly.

26. The method of claim 24, wherein a ratio between the diameter of the transmission shaft and the outer diameter of the adjustable housing assembly is 1:2.313.

27. The method of claim 24, wherein a ratio between the diameter of the transmission shaft and the diameter of the bore formed through the adjustable housing assembly is 1:1.314.

28. The method of claim 19, wherein the adjustable housing assembly is configured to adjustably bend such that an offset angle of up to 3 degrees is formed between the first central axis of the first sub and the second central axis of the second sub.

29. A method of using a drilling motor assembly, the method comprising:
disposing the drilling motor assembly having a power section, a transmission section, and a bearing section downhole; and transmitting torque from the power section to the bearing section through the transmission section, wherein the transmission section comprises an adjustable housing assembly having a central axis defined therethrough and a bore formed therethrough, the bore having a central axis defined therethrough, wherein the central axis of the bore is radially offset from the central axis of the adjustable housing assembly.

30. The method of claim 29, wherein the transmission section comprises a transmission shaft disposed within the bore of the housing assembly.

31. The method of claim 30, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly provides clearance between the transmission shaft and an internal surface of the housing assembly.

32. The assembly of claim 29, wherein the radial offset between the central axis of the bore and the central axis of the housing assembly is up to 5mm.

33. The method of claim 30, wherein a ratio between the diameter of the transmission shaft and the outer diameter of the adjustable housing assembly is 1:2.313.

34. The method of claim 30, wherein a ratio between the diameter of the transmission shaft and the diameter of the bore formed through the adjustable housing assembly is 1:1.314.

35. The method of claim 29, wherein the adjustable housing assembly comprises a first sub coupled to a second sub and a bore formed therethrough, the first sub having a first central axis defined therethrough and the second sub having a second central axis defined therethrough.

36. The method of claim 35, wherein the adjustable housing assembly is configured to adjustably bend such that an offset angle of up to 3 degrees is formed between the first central axis of the first sub and the second central axis of the second sub.