Note: Descriptions are shown in the official language in which they were submitted.
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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
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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.
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[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.
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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.
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[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
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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
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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
202
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.
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[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
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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
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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
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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.
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[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.
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[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
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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.
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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.
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[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
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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
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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
300
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
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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
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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
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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.
21
