U.S. patent application number 15/704861 was filed with the patent office on 2019-03-14 for earth-boring tools including rotatable cutting elements and formation-engaging features that drive rotation of such cutting elements, and related methods.
The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Alexander Rodney Boehm, John Abhishek Raj Bomidi, Kegan L. Lovelace, William A. Moss, JR., Jon David Schroder.
Application Number | 20190078392 15/704861 |
Document ID | / |
Family ID | 65630667 |
Filed Date | 2019-03-14 |
United States Patent
Application |
20190078392 |
Kind Code |
A1 |
Boehm; Alexander Rodney ; et
al. |
March 14, 2019 |
EARTH-BORING TOOLS INCLUDING ROTATABLE CUTTING ELEMENTS AND
FORMATION-ENGAGING FEATURES THAT DRIVE ROTATION OF SUCH CUTTING
ELEMENTS, AND RELATED METHODS
Abstract
An earth-boring tool includes a body and cutting elements
rotatably mounted on the body. The earth-boring tool also includes
a formation-engaging feature attached to the body and exposed at a
face of the body. The formation-engaging feature may be configured
to rotate about an axis of rotation responsive to frictional forces
acting between the formation-engaging feature and a formation when
the body moves relative to the formation. The axis of rotation of
the formation-engaging feature may be oriented at an angle to an
axis of rotation of the cutting elements. The formation-engaging
feature may be operably coupled to the cutting elements such that
rotation of the formation-engaging feature causes rotation of the
cutting elements. Methods include drilling a subterranean formation
including engaging a formation with the cutting elements and the
formation-engaging features.
Inventors: |
Boehm; Alexander Rodney;
(Wheat Ridge, CO) ; Schroder; Jon David; (The
Woodlands, TX) ; Bomidi; John Abhishek Raj; (Spring,
TX) ; Moss, JR.; William A.; (Conroe, TX) ;
Lovelace; Kegan L.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Family ID: |
65630667 |
Appl. No.: |
15/704861 |
Filed: |
September 14, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 10/573 20130101;
E21B 10/55 20130101; E21B 10/62 20130101 |
International
Class: |
E21B 10/573 20060101
E21B010/573; E21B 10/55 20060101 E21B010/55 |
Claims
1. An earth-boring tool for drilling a subterranean formation,
comprising: a body; at least one cutting element rotatably mounted
on the body, the at least one cutting element comprising a table of
polycrystalline hard material having an end cutting surface and a
supporting substrate; a formation-engaging feature attached to the
body and exposed at a face of the body, the formation-engaging
feature configured to rotate about an axis of rotation responsive
to frictional forces acting between the formation-engaging feature
and a formation when the body moves relative to the formation,
wherein the axis of rotation of the formation-engaging feature is
oriented at an angle to an axis of rotation of the at least one
cutting element; and wherein the formation-engaging feature is
operably coupled to the at least one cutting element such that
rotation of the formation-engaging feature causes rotation of the
at least one cutting element.
2. The earth-boring tool of claim 1, further comprising: a first
shaft extending from the formation-engaging feature and carrying a
first gear; and a second shaft extending from the at least one
cutting element and carrying a second gear; and wherein the first
gear is engaged with the second gear.
3. The earth-boring tool of claim 2, wherein each of the first gear
and the second gear comprises a miter gear.
4. The earth-boring tool of claim 2, wherein the first gear has a
diameter greater than a diameter of the second gear.
5. The earth-boring tool of claim 2, wherein the first gear has a
first tooth pattern, and the second gear has a second tooth
pattern, the second tooth pattern differing from the first tooth
pattern.
6. The earth-boring tool of claim 2, wherein an axis of rotation of
the first shaft is substantially aligned with the axis of rotation
of the formation-engaging feature, and an axis of rotation of the
second shaft is substantially aligned with the axis of rotation of
the at least one cutting element, and wherein the axis of rotation
of the first shaft is generally perpendicular to the axis of
rotation of the second shaft.
7. The earth-boring tool of claim 1, wherein the body comprises at
least one blade having a recess therein, and the formation-engaging
feature is mounted at least partially within the recess.
8. The earth-boring tool of claim 1, wherein the formation-engaging
feature comprises a first rotational body and a second rotational
body, the first rotational body of the formation-engaging feature
being configured to rotate responsive to frictional forces acting
between the first rotational body and the formation when the body
moves relative thereto, and the second rotational body being
configured to rotate responsive to rotation of the first rotational
body.
9. The earth-boring tool of claim 8, wherein the first rotational
body of the formation-engaging feature is operably coupled to the
second rotational body of the formation-engaging feature by at
least one of grooves, teeth, or frictional.
10. The earth-boring tool of claim 1, wherein the
formation-engaging feature is operably coupled to the at least one
cutting element such that one full revolution of the
formation-engaging feature results in less than one full revolution
of the at least one cutting element.
11. An earth-boring rotary drill bit, comprising: a bit body; a
cutting element mounted on the bit body, the cutting element
comprising a table of polycrystalline hard material having an end
cutting surface and a supporting substrate, the cutting element
being rotatable about a rotational axis; a formation-engaging
feature attached to the bit body and exposed at a face of the bit
body and configured to rotate about an axis of rotation responsive
to frictional forces acting between the formation-engaging feature
and a subterranean formation when the bit body moves relative to
the subterranean formation, wherein the axis of rotation of the
formation-engaging feature is oriented at an angle to an axis of
rotation of the cutting element; and a flexible drive shaft
operably coupled between the formation-engaging feature and the
supporting substrate of the cutting element, the flexible drive
shaft configured to apply torque to the supporting substrate of the
cutting element so as to rotate the cutting element responsive to
rotation of the formation-engaging feature.
12. The earth-boring rotary drill bit of claim 11, further
comprising a plurality of rotatable cutting elements mounted on the
bit body and a plurality of rotatable formation-engaging features
attached to the bit body and exposed at a face of the bit body,
each rotatable formation-engaging feature of the plurality of
formation-engaging features being operably coupled with a
respective one of the plurality of rotatable cutting elements such
that rotation of each rotatable formation-engaging feature of the
plurality of formation-engaging features drives rotation of a
respective cutting element.
13. The earth-boring rotary drill bit of claim 11, wherein the face
of the bit body includes a cone region, a nose region, a shoulder
region, and a gage region, and wherein the cutting element is
located in the shoulder region or the gage region of the face of
the bit body.
14. The earth-boring rotary drill bit of claim 11, wherein the bit
body includes blades having a leading edge, the cutting element is
mounted at the leading edge of one of the blades, and the
formation-engaging feature is located rotationally behind the
cutting element.
15. The earth-boring rotary drill bit of claim 11, wherein the
flexible drive shaft comprises non-alloy carbon steel material.
16. A method of drilling a subterranean formation, comprising:
applying weight-on-bit to an earth-boring tool substantially along
a longitudinal axis thereof and rotating the earth-boring tool;
engaging a formation with a plurality of rotatable cutting elements
located on blades of a bit body of the earth-boring tool, wherein
the plurality of rotatable cutting elements are rotatably secured
within pockets of the blades; engaging the formation with a
formation-engaging feature attached to the bit body and exposed at
a face of the earth-boring tool and configured to rotate about an
axis of rotation thereof responsive to frictional forces acting
between the formation-engaging feature and the formation when the
earth-boring tool moves relative thereto; and driving rotation of
at least one cutting element of the plurality of rotatable cutting
elements responsive to rotation of the formation-engaging feature,
wherein the axis of rotation of the formation-engaging feature is
oriented at an angle to an axis of rotation of the at least one
cutting element.
17. The method of claim 16, wherein driving rotation of the
plurality of rotatable cutting elements comprises rotating a first
shaft extending from the formation-engaging feature and carrying a
first gear and rotating a second shaft extending from the at least
one cutting element and carrying a second gear, wherein the first
gear is engaged with the second gear.
18. The method of claim 17, wherein rotating the first shaft
extending from the formation-engaging feature and carrying the
first gear and rotating a second shaft extending from the at least
one cutting element and carrying the second gear comprises the
first gear having a diameter greater than a diameter of the second
gear.
19. The method of claim 16, wherein the axis of rotation of the
formation-engaging feature is perpendicular to an axis of rotation
of the at least one cutting element.
20. The method of claim 16, wherein rotating the formation-engaging
feature through one full revolution of the formation-engaging
feature results in less than one full revolution of the at least
one cutting element.
21. The method of claim 16, wherein engaging the formation with the
formation-engaging feature comprises controlling a rate at which
the formation-engaging feature extends and retracts from the face
of the earth-boring tool using a hydraulic actuation device.
Description
FIELD
[0001] Embodiments of the present disclosure relate to earth-boring
tools including rotatable cutting elements and formation-engaging
features that drive rotation of such cutting elements, and to
methods of drilling a subterranean formation using such
earth-boring tools.
BACKGROUND
[0002] Wellbores are formed in subterranean formations for various
purposes including, for example, extraction of oil and gas from the
subterranean formation and extraction of geothermal heat from the
subterranean formation. Wellbores may be formed in a subterranean
formation using a drill bit, such as an earth-boring rotary drill
bit. Different types of earth-boring rotary drill bits are known in
the art, including fixed-cutter bits (which are often referred to
in the art as "drag" bits), rolling-cutter bits (which are often
referred to in the art as "rock" bits), diamond-impregnated bits,
and hybrid bits (which may include, for example, both fixed cutters
and rolling cutters). The drill bit is rotated and advanced into
the subterranean formation. As the drill bit rotates, the cutters
or abrasive structures thereof cut, crush, shear, and/or abrade
away the formation material to form the wellbore. A diameter of the
wellbore drilled by the drill bit may be defined by the cutting
structures disposed at the largest outer diameter of the drill
bit.
[0003] The drill bit is coupled, either directly or indirectly, to
an end of what is referred to in the art as a "drill string," which
comprises a series of elongated tubular segments connected
end-to-end that extends into the wellbore from the surface of earth
above the subterranean formations being drilled. Various tools and
components, including the drill bit, may be coupled together at the
distal end of the drill string at the bottom of the wellbore being
drilled. This assembly of tools and components is referred to in
the art as a "bottom hole assembly" (BHA).
[0004] The drill bit may be rotated within the wellbore by rotating
the drill string from the surface of the formation, or the drill
bit may be rotated by coupling the drill bit to a downhole motor,
which is also coupled to the drill string and disposed proximate
the bottom of the wellbore. The downhole motor may include, for
example, a hydraulic Moineau-type motor having a shaft, to which
the drill bit is mounted, that may be caused to rotate by pumping
fluid (e.g., drilling mud or fluid) from the surface of the
formation down through the center of the drill string, through the
hydraulic motor, out from nozzles in the drill bit, and back up to
the surface of the formation through the annular space between the
outer surface of the drill string and the exposed surface of the
formation within the wellbore. The downhole motor may be operated
with or without drill string rotation.
[0005] A drill string may include a number of components in
addition to a downhole motor and drill bit including, without
limitation, drill pipe, drill collars, stabilizers, measuring while
drilling (MWD) equipment, logging while drilling (LWD) equipment,
downhole communication modules, and other components.
[0006] Cutting elements used in earth boring tools often include
polycrystalline diamond compact (often referred to as "PDC")
cutting elements, which are cutting elements that include so-called
"tables" of a polycrystalline diamond material mounted to
supporting substrates and presenting a cutting face for engaging a
subterranean formation. Polycrystalline diamond (often referred to
as "PCD") material is material that includes inter-bonded grains or
crystals of diamond material. In other words, PCD material includes
direct, intergranular bonds between the grains or crystals of
diamond material.
[0007] Cutting elements are typically mounted on the body of a
drill bit by brazing. The drill bit body is formed with recesses
therein, commonly termed "pockets," for receiving a substantial
portion of each cutting element in a manner which presents the PCD
layer at an appropriate back rake and side rake angle, facing in
the direction of intended bit rotation, for cutting in accordance
with the drill bit design. In such cases, a brazing compound is
applied between the surface of the substrate of the cutting element
and the surface of the recess on the bit body in which the cutting
element is received. The cutting elements are installed in their
respective recesses in the bit body, and heat is applied to each
cutting clement to raise the temperature to a point high enough to
braze the cutting elements to the bit body in a fixed position but
not so high as to damage the PCD layer.
[0008] Unfortunately, securing a PDC cutting element to a drill bit
restricts the useful life of such cutting element, as the cutting
edge of the diamond table wears down as does the substrate,
creating a so-called "wear flat" and necessitating increased weight
on bit to maintain a given rate of penetration of the drill bit
into the formation due to the increased surface area presented. In
addition, unless the cutting element is heated to remove it from
the bit and then rebrazed with an unworn portion of the cutting
edge presented for engaging a formation, more than half of the
cutting element is never used.
[0009] Rotatable cutting elements mounted for rotation about a
longitudinal axis of the cutting element can be made to rotate by
mounting them at an angle in the plane in which the cutting
elements are rotating (side rake angle). This will allow them to
wear more evenly than fixed cutting elements, having a more uniform
distribution of heat across and heat dissipation from the surface
of the PDC table and exhibit a significantly longer useful life
without removal from the drill bit. That is, as a cutting element
rotates in a bit body, different parts of the cutting edges or
surfaces of the PDC table may be exposed at different times, such
that more of the cutting element is used. Thus, rotatable cutting
elements may have a longer life than fixed cutting elements.
[0010] Additionally, rotatable cutting elements may mitigate the
problem of "bit balling," which is the buildup of debris adjacent
to the edge of the cutting face of the PDC table. As the PDC table
rotates, the debris built up at the edge of the PDC table in
contact with a subterranean formation may be forced away as the PDC
table rotates.
BRIEF SUMMARY
[0011] In one embodiment of the disclosure, an earth-boring tool
for drilling a subterranean formation includes a body and one or
more cutting elements rotatably mounted on the body. The cutting
elements may include a table of polycrystalline hard material
having an end cutting surface and a supporting substrate. The
earth-boring tool also includes a formation-engaging feature
attached to the body and exposed at a face of the body. The
formation-engaging feature may be configured to rotate about an
axis of rotation responsive to frictional forces acting between the
formation-engaging feature and a formation when the body moves
relative to the formation. The axis of rotation of the
formation-engaging feature may be oriented at an angle to an axis
of rotation of the cutting elements. The formation-engaging feature
may be operably coupled to the cutting elements such that rotation
of the formation-engaging feature causes rotation of the cutting
elements.
[0012] In another embodiment of the disclosure, an earth-boring
rotary drill bit includes a bit body and a cutting element mounted
on the bit body. The cutting element includes a table of
polycrystalline hard material having an end cutting surface and a
supporting substrate. The cutting element may be rotatable about a
rotational axis. The earth-boring rotary drill bit also includes a
formation-engaging feature attached to the bit body and exposed at
a face of the bit body. The formation-engaging feature may be
configured to rotate about an axis of rotation responsive to
frictional forces acting between the formation-engaging feature and
a subterranean formation when the bit body moves relative to the
subterranean formation. The axis of rotation of the
formation-engaging feature may be oriented at an angle to an axis
of rotation of the cutting element. The earth-boring rotary drill
bit may also include a flexible drive shaft operably coupled
between the formation-engaging feature and the supporting substrate
of the cutting element. The flexible drive shaft may be configured
to apply torque to the supporting substrate of the cutting element
so as to rotate the cutting element responsive to rotation of the
formation-engaging feature.
[0013] In a further embodiment of the disclosure, a method of
drilling a subterranean formation includes applying weight-on-bit
to an earth-boring tool substantially along a longitudinal axis
thereof and rotating the earth-boring tool. The method may include
engaging a formation with rotatable cutting elements located on
blades of a bit body of the earth-boring tool. The rotatable
cutting elements may be rotatably secured within pockets of the
blades. The method also includes engaging the formation with a
formation-engaging feature attached to the bit body and exposed at
a face of the earth-boring tool. The formation-engaging feature may
be configured to rotate about an axis of rotation thereof
responsive to frictional forces acting between the
formation-engaging feature and the formation when the earth-boring
tool moves relative thereto. The method may also include driving
rotation of one of the cutting elements of the rotatable cutting
elements responsive to rotation of the formation-engaging feature.
The axis of rotation of the formation-engaging feature may be
oriented at an angle to an axis of rotation of the cutting
element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a simplified perspective view of a fixed-blade
earth-boring rotary drill bit.
[0015] FIG. 2 is a simplified perspective view of a rotatable
cutting element that may be used in conjunction with a
formation-engaging feature as shown in FIG. 1.
[0016] FIG. 3 is a simplified top view of an embodiment of a
formation-engaging assembly that may be used in conjunction with a
rotatable cutting element, such as the one shown in FIG. 2.
[0017] FIG. 3A is a simplified end view of the formation-engaging
assembly shown in FIG. 3.
[0018] FIG. 3B is a simplified cross-sectional side view of the
formation-engaging assembly shown in FIG. 3.
[0019] FIG. 4A is a simplified end view of another embodiment of a
formation-engaging assembly that may be used in conjunction with a
rotatable cutting element, such as the one shown in FIG. 2.
[0020] FIG. 4B is a simplified cross-sectional side view of the
formation-engaging assembly shown in FIG. 4A.
[0021] FIG. 5 is a simplified end view of another embodiment of a
formation-engaging assembly that may be used in conjunction with a
rotatable cutting element, such as the one shown in FIG. 2.
[0022] FIG. 6 is a simplified perspective view of a portion of the
fixed-blade earth-boring rotary drill bit of FIG. 1.
DETAILED DESCRIPTION
[0023] The illustrations presented herein are not actual views of
any particular tool or drill string, but are merely idealized
representations that are employed to describe example embodiments
of the present disclosure. The following description provides
specific details of embodiments of the present disclosure in order
to provide a thorough description thereof. However, a person of
ordinary skill in the art will understand that the embodiments of
the disclosure may be practiced without employing many such
specific details. Indeed, the embodiments of the disclosure may be
practiced in conjunction with conventional techniques employed in
the industry. In addition, the description provided below does not
include all elements to form a complete structure or assembly. Only
those process acts and structures necessary to understand the
embodiments of the disclosure are described in detail below.
Additional conventional acts and structures may be used. Also note,
any drawings accompanying the application are for illustrative
purposes only, and are thus not drawn to scale. Additionally,
elements common between figures may retain the same numerical
designation.
[0024] As used herein, the terms "comprising," "including,"
"containing," "characterized by," and grammatical equivalents
thereof are inclusive or open-ended terms that do not exclude
additional, unrecited elements or method steps, but also include
the more restrictive terms "consisting of" and "consisting
essentially of" and grammatical equivalents thereof.
[0025] As used herein, the term "may" with respect to a material,
structure, feature or method act indicates that such is
contemplated for use in implementation of an embodiment of the
disclosure, and such term is used in preference to the more
restrictive term "is" so as to avoid any implication that other,
compatible materials, structures, features and methods usable in
combination therewith should or must be excluded.
[0026] As used herein, the term "configured" refers to a size,
shape, material composition, and arrangement of one or more of at
least one structure and at least one apparatus facilitating
operation of one or more of the structure and the apparatus in a
predetermined way.
[0027] As used herein, the singular forms following "a," "an," and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise.
[0028] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0029] As used herein, spatially relative terms, such as "beneath,"
"below," "lower," "bottom," "above," "upper," "top," "front,"
"rear," "left," "right," and the like, may be used for ease of
description to describe one element's or feature's relationship to
another element(s) or feature(s) as illustrated in the figures.
Unless otherwise specified, the spatially relative terms are
intended to encompass different orientations of the materials in
addition to the orientation depicted in the figures.
[0030] As used herein, the term "substantially" in reference to a
given parameter, property, or condition means and includes to a
degree that one of ordinary skill in the art would understand that
the given parameter, property, or condition is met with a degree of
variance, such as within acceptable manufacturing tolerances. By
way of example, depending on the particular parameter, property, or
condition that is substantially met, the parameter, property, or
condition may be at least 90.0% met, at least 95.0% met, at least
99.0% met, or even at least 99.9% met.
[0031] As used herein, the term "about" used in reference to a
given parameter is inclusive of the stated value and has the
meaning dictated by the context (e.g., it includes the degree of
error associated with measurement of the given parameter).
[0032] As used herein, the term "hard material" means and includes
any material having a Knoop hardness value of about 1,000
Kg.sub.f/mm.sup.2 (9,807 MPa) or more. Hard materials include, for
example, diamond, cubic boron nitride, boron carbide, tungsten
carbide, etc.
[0033] As used herein, the term "intergranular bond" means and
includes any direct atomic bond (e.g., covalent, metallic, etc.)
between atoms in adjacent grains of material.
[0034] As used herein, the term "polycrystalline hard material"
means and includes any material comprising a plurality of grains or
crystals of the material that are bonded directly together by
intergranular bonds. The crystal structures of the individual
grains of polycrystalline hard material may be randomly oriented in
space within the polycrystalline hard material.
[0035] As used herein, the term "earth-boring tool" means and
includes any type of bit or tool used for drilling during the
formation or enlargement of a wellbore and includes, for example,
rotary drill bits, percussion bits, core bits, eccentric bits,
bi-center bits, reamers, mills, drag bits, roller-cone bits, hybrid
bits, and other drilling bits and tools known in the art.
[0036] Embodiments of the present disclosure include cutting
elements rotatably mounted on a body of an earth-boring tool.
Formation-engaging features attached to the body and exposed at a
face of the body may be configured to drive rotation of the
rotatable cutting elements responsive to frictional forces acting
between the formation-engaging features and a subterranean
formation. Further, operably coupling such formation-engaging
features to the rotatable cutting elements may provide the
advantage of selecting mating surfaces therebetween to impart
increased torque to the rotatable cutting elements.
[0037] FIG. 1 is a perspective view of a fixed-cutter earth-boring
rotary drill bit 200. The drill bit 200 includes a bit body 202
that may be secured to a shank 204 having a threaded connection
portion 206 (e.g., an American Petroleum Institute (API) threaded
connection portion) for attaching the drill bit 200 to a drill
string. In some embodiments, the bit body 202 may be secured to the
shank 204 using an extension 208. In other embodiments, the bit
body 202 may be secured directly to the shank 204.
[0038] The bit body 202 may include internal fluid passageways that
extend between the face 203 of the bit body 202 and a longitudinal
bore, extending through the shank 204, the extension 208, and
partially through the bit body 202. Nozzle inserts 214 also may be
provided at the face 203 of the bit body 202 within the internal
fluid passageways. The bit body 202 may further include a plurality
of blades 216 that are separated by junk slots 218. In some
embodiments, the bit body 202 may include gage wear plugs 222 and
wear knots 228. A plurality of fixed cutting elements 210 may be
mounted on the face 203 of the bit body 202 in cutting element
pockets 212 that are located along each of the blades 216.
Rotatable cutting elements 302 may be rotatably mounted on the face
203 of the bit body 202 in respective cutting element pockets 212.
The fixed cutting elements 210 and the rotatable cutting elements
302 may include PDC cutting elements, or may include other cutting
elements. In addition, formation-engaging features 220 may be
fastened within respective recesses 221 at the face 203 of the bit
body 202. The formation-engaging features 220 may be configured to
drive rotation of at least some of the rotatable cutting elements
302 responsive to frictional forces acting between the
formation-engaging features 220 and a subterranean formation when
the bit body 202 moves relative thereto, as described below and
shown in FIGS. 2-5.
[0039] FIG. 2 is a simplified perspective view of one embodiment of
the rotatable cutting element 302. The rotatable cutting element
302 may be used, for example, in conjunction with
formation-engaging features 220 shown in FIG. 1. The rotatable
cutting element 302 may include a table 304 (e.g., a table of
polycrystalline hard material) bonded to a substrate 308 at an
interface 307. The table 304 may include diamond, cubic boron
nitride, or another hard material. The substrate 308 may include,
for example, cobalt-cemented tungsten carbide or another carbide
material. The table 304 may have an end cutting surface 306, and
may also have other surfaces, such as side surfaces, chamfers,
etc., at a peripheral cutting edge of the table 304, which surfaces
contact a subterranean formation when the rotatable cutting element
302 is used to form or service a wellbore. The table 304 may be
generally cylindrical, and the interface 307 may be generally
parallel to the end cutting surface 306. The substrate 308 may have
a bearing surface 309 on an end thereof, opposite the interface
307. In this embodiment, the bearing surface 309 may be planar and
annular. In addition, the end cutting surface 306 of the table 304
may be planar and annular. In other embodiments, the bearing
surface 309 may be nonplanar and/or the end cutting surface may
include a nonplanar, convex cutting table not having a flat cutting
face (e.g., dome-shaped, cone-shaped, chisel-shaped, etc.). In some
embodiments, the end cutting surface 306 may be treated (e.g.,
polished) to exhibit a reduced surface roughness.
[0040] Interior surfaces of the substrate 308 of the rotatable
cutting element 302 may define a longitudinally extending blind
hole 310 having a proximal end 312 at the bearing surface 309 of
the substrate 308 and having a distal end 314 within the substrate
308 proximate the interface 307 between the substrate 308 and the
table 304. In some embodiments, the blind hole 310 may not extend
to the table 304 (i.e., may terminate within the substrate 308).
The blind hole 310 is defined by an interior sidewall 316 of the
rotatable cutting element 302 and may be generally centered along a
longitudinal axis L.sub.302 of the rotatable cutting element 302.
The blind hole 310 may impart an annular cross-sectional shape to
the rotatable cutting element 302. In some embodiments, at least a
portion of the interior sidewall 316 may include structures (e.g.,
channels, grooves, protrusions, threads, etc.) formed therein to
facilitate retention and/or alignment of the rotatable cutting
element 302 with respect to features inserted within the blind hole
310. Such structures may align with complementary structures on
inserted features.
[0041] FIG. 3 shows a simplified top view of one embodiment of a
formation-engaging assembly 300. Elements shown in dashed lines may
not be visible from a top view of the blade 216, but are included
in FIG. 3 for clarity. The formation-engaging assembly 300 may
include cutting elements, such as the fixed cutting elements 210 as
well as one or more of the rotatable cutting elements 302 shown in
FIG. 2. The formation-engaging assembly 300 may also include
formation-engaging features 220 having a longitudinal axis
L.sub.220. In some embodiments, the formation-engaging feature 220
may be generally cylindrical and have an interior sidewall 322 and
an exterior sidewall 324. The formation-engaging feature 220 may
include an attachment feature 326 for fastening (e.g., brazing) at
least a portion of the formation-engaging feature 220 within the
recess 221. The formation-engaging feature 220 may also include an
engagement feature 330 having a shaft 330A and a mating surface
330B, for example. The rotatable cutting element 302 may include an
impelling feature 332 having a shaft 332A and a mating surface
332B, for example.
[0042] The fixed cutting elements 210 may be brazed or fastened
within respective cutting element pockets 212 of the blades 216. In
addition, the rotatable cutting elements 302 may be rotatably
fastened within respective cutting element pockets 212 configured
for retaining such elements. Of course, a person of ordinary skill
in the art would recognize that lateral support of the rotatable
cutting elements 302 would be desirable in order to protect against
impact damage and/or to support the rotatable cutting elements 302
located within the cutting element pockets 212 machined (e.g., in
steel bodies) or otherwise formed in the blades 216 of the bit body
202 (FIG. 1) or supported by preformed sleeves that have been
brazed or otherwise fastened within the respective cutting element
pockets 212 of the blades 216. The formation-engaging features 220
may be attached to the bit body 202 and exposed at the face 203 of
the bit body 202 (FIG. 1) and configured to engage a formation
during drilling operations. For example, the formation-engaging
feature 220 may be located proximate to (e.g., rotationally behind)
the rotatable cutting elements 302 on the blades 216. In some
embodiments, the exterior sidewall 324 of the formation-engaging
feature 220 may include features (e.g., grooves, veins, textured
surface finish, etc.) to enhance frictional forces acting thereon
to facilitate rotation of the formation-engaging feature 220 upon
interaction with the engaged formation. Materials of the
formation-engaging feature 220 may include a metal carbide or steel
material (e.g., high-strength steel alloy). For example, the
formation-engaging feature 220, including the attachment feature
326, may include materials such as tungsten carbide, tantalum
carbide, or titanium carbide. Additionally, various binding metals
may be included in the formation-engaging feature 220, such as
cobalt, nickel, iron, metal alloys, or mixtures thereof, such that
metal carbide grains may be supported within the metallic
binder.
[0043] The formation-engaging feature 220 may be fastened within a
respective recess 221 of the blades 216 utilizing the attachment
feature 326. In some embodiments, the attachment feature 326 may
include support members (e.g., sleeves) that retain the
formation-engaging feature 220 utilizing retention members (e.g.,
snap rings). Such support members may secure the formation-engaging
feature 220 to the blade 216 and enable the formation-engaging
feature 220 to move relative to the blades 216. It is to be
appreciated that any type of attachment feature 326 may be utilized
to facilitate attachment of the formation-engaging feature 220
within the recess 221 without interfering with rotation
thereof.
[0044] The shaft 330A of the formation-engaging feature 220 may be
affixed thereto (e.g., within a through hole or blind hole defined
by the interior sidewall 322). In other embodiments, the shaft 330A
may be integrally formed with the formation-engaging feature 220,
such that there is no physical interface between the shaft 330A and
the formation-engaging feature 220. The mating surface 330B may be
affixed to or integrally formed with the shaft 330A. In some
embodiments, the mating surface 330B may include a gear (e.g.,
bevel, miter, etc.). In other embodiments, the mating surface 330B
may include a spur gear (e.g., straight-cut gear). The engagement
feature 330, including the shaft 330A and/or the mating surface
330B, may be formed of the same material as the formation-engaging
feature 220. In yet other embodiments, the mating surface 330B may
not include a gear, but may include any other surface or interface
for operatively coupling the engagement feature 330 of the
formation-engaging feature 220 to features of the rotatable cutting
element 302. In addition, the shaft 332A of the impelling feature
332 may be affixed (e.g., brazed) to the interior sidewall 316
defining the blind hole 310. In other embodiments, the shaft 332A
of the impelling feature 332 may be integrally formed with the
substrate 308, such that there is no physical interface between the
shaft 332A and the substrate 308 of the rotatable cutting element
302. The mating surface 332B may be affixed to or integrally formed
with the shaft 332A. In some embodiments, the mating surface 332B
may include a gear (e.g., bevel, miter, etc.) that is complementary
to the mating surface 330B of the engagement feature 330. In other
embodiments, the mating surface 332B may include a spur gear (e.g.,
straight-cut gear) or other such surface or interface to be aligned
with the mating surface 330B. In some embodiments, the impelling
feature 332, including the shaft 332A and/or the mating surface
332B, may be formed of the same material as the engagement feature
330, while in other embodiments, the impelling feature 332 may be
formed of a different material than that of the engagement feature
330. Further, the impelling feature 332, including the shaft 332A
and/or the mating surface 332B, may or may not be formed of the
same material as that of the substrate 308 of the rotatable cutting
element 302.
[0045] In some embodiments, at least a portion of the rotatable
cutting element 302 may be retained within a sleeve (not shown) in
order to facilitate retention and rotation thereof within the
cutting element pocket 212. Such sleeves for rotatable elements are
described in, for example, U.S. patent application Ser. No.
15/662,626, "Rotatable Cutters and Elements for Use on Earth-Boring
Tools in Subterranean Boreholes, Earth-Boring Tools Including Same,
and Related Methods," filed Jul. 28, 2017, the entire disclosure of
which is hereby incorporated herein by reference. The sleeve may be
sized and shaped to circumferentially surround at least a portion
of the substrate 308. The sleeve may include grooves or similar
features to facilitate removable retention of the rotatable cutting
element 302 using various retention features. In other embodiments,
the rotatable cutting element 302 may be rotatably secured within
the cutting element pocket 212 utilizing the shaft 332A of the
impelling feature 332 alone and/or using alternative retention
elements. For example, the shaft 332A may be brazed to the
substrate 308 of the rotatable cutting element 302 to restrict
relative movement therebetween. In other embodiments, the retention
elements may include threaded fasteners having complementary
threaded surfaces on each of the shaft 332A and the interior
sidewall 316 of the substrate 308. Such threaded fasteners may also
include locking devices (e.g., nuts or washers) to prevent such
threaded fasteners from becoming loosened. It may be appreciated
that any type of retention elements may be utilized to support and
protect the rotatable cutting element 302 against forces
experienced while drilling. In particular, when the
formation-engaging feature 220 and/or the rotatable cutting element
302 engage a formation, the compressive forces acting thereon may
be absorbed and deflected in order to facilitate coupling between
the components of the formation-engaging assembly 300 without
inducing bending and/or angular misalignment of such
components.
[0046] In some embodiments, the longitudinal axis L.sub.220 of the
formation-engaging feature 220 and longitudinal axis L.sub.302 of
the rotatable cutting element 302 may be oriented at an angle to
one another. In some embodiments, the axis of rotation of the
formation-engaging feature 220 may be generally transverse (e.g.,
perpendicular) to an axis of rotation of the rotatable cutting
element 302. In such configurations, use of gears (e.g., miter) as
the mating surfaces 330B, 332B may facilitate such a transverse
relationship between the longitudinal axis L.sub.220 of the
formation-engaging feature 220 and longitudinal axis L.sub.302 of
the rotatable cutting element 302. In some embodiments, the
formation-engaging feature 220 may be operably coupled to more than
one rotatable cutting element 302. For example, multiple (e.g., two
or more) mating surfaces 330B may be located along the shaft 330A
of the engagement feature 330. Each of the mating surfaces 330B may
be associated and aligned with mating surfaces 332B of respective
impelling features 332 of multiple rotatable cutting elements 302.
For example, each of the rotatable cutting elements 302 located on
an individual blade 216 may be operatively coupled to a single
formation-engaging feature 220.
[0047] The formation-engaging feature 220 may be characterized as a
"rolling element" that interacts with a formation. The
formation-engaging feature 220 may be operatively coupled to one or
more of the rotatable cutting elements 320 to drive rotation
thereof. In some embodiments, the formation-engaging feature 220
may be configured to rotate about an axis of rotation thereof
(e.g., bearing axis) responsive to frictional forces acting between
the formation-engaging feature 220 and the engaged formation as the
bit body 202 moves relative thereto. In some embodiments, a
longitudinal axis L.sub.220 of the formation-engaging feature 220
may be oriented at an angle (e.g., perpendicular) to relative
movement of the engaged formation to enable rotation thereof upon
rotation of a drill string and application of weight-on-bit
(WOB).
[0048] In order to enhance (e.g., increase) torque transfer between
the formation-engaging feature 220 and the rotatable cutting
element 302 during drilling operations, the mating surface 330B of
the engagement feature 330 may be sized and shaped to operatively
engage the mating surface 332B of the impelling feature 332. For
example, a size of the mating surface 330B may be larger than a
size of the mating surface 332B. For example, the mating surface
330B may be considered the primary (i.e., carrier) gear and may
have a greater diameter than that of the mating surface 332B, which
may be considered the secondary (i.e., receiver) gear. Such an
offset in size, may function as a torque multiplier. In addition,
the tooth lines of the gears of the mating surfaces 330B, 332B may
include straight, spiral, or zerol (i.e., intermediate) tooth lines
and may be chosen for a specific configuration to distribute (e.g.,
increase) torque between the engagement feature 330 and the
impelling feature 332. In addition, the angles of the gears (e.g.,
bevel) may be complementary to that of opposing mating surfaces
330B, 332B and may be configured to facilitate a desired torque
transfer therebetween. By way of non-limiting example, the mating
surfaces 330B, 332B may include miter gears having a conical shape
and capable of transmitting rotational motion at a 90-degree angle
with a 1:1 tooth ratio. However, alternative angles and ratios are
contemplated, each of which may be adjusted in order to impart
increased torque to the impelling feature 332 to drive rotation of
the rotatable cutting element 302. In other words, the impelling
feature 332 may be configured to apply torque to the substrate 308
of the rotatable cutting element 302 to facilitate rotation of the
rotatable cutting element 302 relative to the blades 216 of the bit
body 202 (FIG. 1) utilizing the mating surfaces 330B, 332B that are
sized and shaped to maximize distribution of torque from the
engagement feature 330 to the impelling feature 332. Further, a
ratio of rotational frequency between the rotatable cutting element
302 and the formation-engaging feature 220 may be adjusted for a
desired torque transfer. By way of non-limiting example, the
rotational frequency ratio of the formation-engaging feature 220 to
the rotatable cutting element 302 may be between about 0.05:1 and
about 20:1. Thus, the formation-engaging feature 220 may be
operatively coupled to the rotatable cutting element 302 through
the engagement feature 330 (being fixedly coupled to the
formation-engaging feature 220) and the impelling feature 332
(being fixedly coupled to the substrate 308 of the rotatable
cutting element 302).
[0049] FIG. 3A shows a simplified end view of the embodiment of the
formation-engaging assembly 300 shown in FIG. 3. In particular, the
end view includes the formation-engaging feature 220 and the
rotatable cutting element 302 as viewed from an end of the blade
216. As shown in FIG. 3A, the exterior sidewall 324 of the
formation-engaging feature 220 may extend above the face 203 of the
bit body 202 (FIG. 1) to enable interaction with the engaged
formation. The rotatable cutting element 302 may be mounted to the
blade 216, as described in greater detail above with reference to
FIG. 3. Additional components of the formatting-engaging assembly
300 may be located within the recess 221 (FIG. 3) of the blade 216.
For example, the engagement feature 330, including the shaft 330A
(not shown) and the mating surface 330B, and the impelling feature
332, including the shaft 332A and the mating surface 332B, may be
located within the recess 221 of the blade 216 (i.e., below an
outer surface of the face 203) in order to protect such components
from harsh drilling conditions. In some embodiments, the engagement
feature 330 may not include a shaft 330A. Rather, the mating
surface 330B may be affixed directly to or integrally formed with a
distal end surface of the formation-engaging feature 220. In some
embodiments, the formation-engaging feature 220 may be sized such
that a diameter thereof may be relatively larger than a diameter of
the rotatable cutting element 302. By way of non-limiting example,
the formation-engaging feature 220 may have a diameter of between
about 0.5 in. and about 5 in. and the rotatable cutting element 302
may have a diameter of between about 0.3 in. and about 1.25 in.
[0050] FIG. 3B shows a simplified cross-sectional side view of the
embodiment of the formation-engaging assembly 300 shown in FIGS. 3
and 3A. In particular, the side view includes the
formation-engaging feature 220 and the rotatable cutting element
302 as viewed from behind (i.e., opposite a leading edge of) the
blade 216. As described with reference to FIG. 3A, additional
components of the formatting-engaging assembly 300 may be located
within the recess 221 (FIG. 3) of the blade 216. For example, the
engagement feature 330, including the attachment feature 326, the
shaft 330A, and the mating surface 330B, as well as the impelling
feature 332, including the shaft 332A and the mating surface 332B,
may be located within the recess 221 of the blade 216 (i.e., below
an outer surface of the face 203) in order to protect such
components from harsh drilling conditions. As best shown in FIGS.
3A and 3B, the longitudinal axis L.sub.220 of the
formation-engaging feature 220 and the longitudinal axis L.sub.302
of the rotatable cutting element 302 may be oriented at an angle
(e.g., perpendicular) with respect to one another. In addition, the
longitudinal axis L.sub.302 of the rotatable cutting element 302
may be angled (e.g., inclined) relative to a vertical plane
intersecting the formation-engaging feature 220. In such an
embodiment, a longitudinal axis of the shaft 332A of the impelling
feature 332 may be generally aligned with the longitudinal axis
L.sub.302 of the rotatable cutting element 302 when the shaft 332A
is retained within the blind bore 310 of the substrate 308. The
exterior sidewall 324 of the formation-engaging feature 220 may be
configured and positioned for direct contact with the engaged
formation, while the longitudinal axis L.sub.220 (e.g., bearing
axis) of the formation-engaging feature 220 is aligned with a
longitudinal axis of the engagement feature 330 and, thus, the
mating surfaces 330B, 332B. In other words, rotation of the
rotatable cutting element 302 is driven by rotation of a single
rotational body (i.e., the formation-engaging feature 220) being in
direct contact with the engaged formation while having a single
bearing axis directly aligned with the engagement feature 330 and
the mating surfaces 330B, 332B.
[0051] FIG. 4A shows a simplified end view of another embodiment of
the formation-engaging assembly 300 that may be used in conjunction
with the rotatable cutting element 302, such as the one shown in
FIG. 2. In the embodiment of FIGS. 4A and 4B, components and
alignment of the formation-engaging feature 220 may be different
than that of the embodiment of FIGS. 3, 3A, and 3B. For example,
the formation-engaging feature 220 may be separate from and located
proximate to the engagement feature 330. In such an embodiment, the
exterior sidewall 324 of the formation-engaging feature 220 may be
configured and positioned for direct contact with the engaged
formation. However, rather than the shaft portion 330A of the
engagement feature 330 being located within the interior sidewall
322 and along the longitudinal axis L.sub.220 of the
formation-engaging feature 220, the engagement feature 330 may be
configured as a separate rotational body located remote from the
engaged formation and in direct physical contact with the
formation-engaging feature 220. For example, the engagement feature
330 may be located directly below or alongside the
formation-engaging feature 220.
[0052] In some embodiments, the engagement feature 330 may not
include a shaft 330A. Rather, the mating surface 330B may be
affixed directly to or integrally formed with a distal end surface
of the engagement feature 330. As in the previous embodiment, the
shaft 332A of the impelling feature 332 may be affixed within the
blind bore 310 of the substrate 308 of the rotatable cutting
element 302. Additional components of the formatting-engaging
assembly 300 may be located within the recess 221 (FIG. 3) of the
blade 216. For example, the engagement feature 330, including the
shaft 330A (not shown) and the mating surface 330B, and the
impelling feature 332, including the shaft 332A and the mating
surface 332B, may be located within the recess 221 of the blade 216
(i.e., below an outer surface of the face 203) in order to protect
such components from harsh drilling conditions.
[0053] In some embodiments, the engagement feature 330 may be
configured as a cylindrical-shaped shaft and/or gear having grooves
or teeth mating with corresponding grooves or teeth on the exterior
sidewall 324 of the formation-engaging feature 220 along an
interface 328 therebetween. In other embodiments, the interface 328
may be a frictional interface such that friction alone (i.e.,
exterior surfaces lacking grooves or teeth) drives interaction
between the formation-engaging feature 220 and the engagement
feature 330. In some embodiments, the interface 328 may include a
hard material (e.g., polycrystalline hard material). In such an
embodiment, the external surfaces of the components may be allowed
to slide relative to one another during excessive opposing forces,
thus avoiding damage to various components of the system.
[0054] In addition, the formation-engaging assembly 300 may include
sealing elements associated with the recess 221 in order to prevent
entry of and/or flush cuttings and drilling debris from the
components within the recess 221. In some embodiments, drilling
fluids may be utilized to deflect and/or clear the recess 221 of
cuttings and drilling debris. In other embodiments materials (e.g.,
polymeric, rubber, etc.) may be applied to exterior surfaces of
certain components, such that the formation-engaging feature 220
and/or the engagement feature 330 may be self-cleaning during
rotation thereof. In yet other embodiments, grooves and/or teeth of
the formation-engaging feature 220 and the engagement feature 330
may be shaped and/or sized to facilitate removal of the cuttings
and drilling debris during drilling operations.
[0055] In some embodiments, rotation of the formation-engaging
feature 220 based on interaction with the engaged formation may
drive opposite rotation of the engagement feature 330. Rotation of
the engagement feature 330 may in turn drive rotation of the shafts
330A, 332A by way of the mating surfaces 330B, 332B and, thus,
drive rotation of the rotatable cutting element 302. In such a
configuration, sizes, shapes, and tooth patterns of each of the
formation-engaging feature 220 and the engagement feature 330 may
be adjusted to distribute (e.g., increase) torque between
components in order to enhance torque to the rotatable cutting
element 302. For example, the formation-engaging feature 220 may be
sized such that a diameter thereof may be relatively smaller than a
diameter of the engagement feature 330 in order to facilitate
torque distribution to the rotatable cutting element 302.
[0056] FIG. 4B shows a simplified cross-sectional side view of the
embodiment of the formation-engaging assembly 300 shown in FIG. 4A.
The side view includes the formation engaging feature 220 and the
rotatable cutting element 302 as viewed from behind (i.e., opposite
the leading edge of) the blade 216. As described with reference to
FIG. 4A, additional components of the formatting-engaging assembly
300 may be located within the recess 221 (FIG. 3) of the blade 216.
For example, the engagement feature 330, including the shaft 330A
and the mating surface 330B, as well as the impelling feature 332,
including the shaft 332A and the mating surface 332B, may be
located interior to the blade 216 (i.e., below an outer surface of
the face 203) in order to protect such components from harsh
drilling conditions.
[0057] In the embodiment of FIGS. 4A and 4B, the exterior sidewall
324 of the formation-engaging feature 220 may be configured and
positioned for direct contact with the engaged formation, while the
longitudinal axis L.sub.220 (e.g., bearing axis) of the
formation-engaging feature 220 is not aligned with a longitudinal
axis of the engagement feature 330. Rather, the engagement feature
330 may be configured as a separate shaft and/or gear configured to
rotationally interact with the formation-engaging feature 220 along
the interface 328 therebetween. In such an embodiment, each of the
formation-engaging feature 220 and the engagement feature 330 may
include separate and/or combined attachment features 326. In the
present embodiment, rotation of the rotatable cutting element 302
is driven by rotation of multiple bodies (e.g., two) including the
formation-engaging feature 220 and the engagement feature 330. For
example, the formation-engaging feature 220 may have one bearing
axis and may be in direct contact with the engaged formation while
the engagement feature 330 may have a second bearing axis directly
aligned with the mating surfaces 330B, 332B.
[0058] As with the embodiment of FIGS. 3, 3A, and 3B, the
longitudinal axis L.sub.220 of the formation-engaging feature 220
and the longitudinal axis L.sub.302 of the rotatable cutting
element 302 may be oriented at an angle (e.g., perpendicular) with
respect to one another. In addition, the longitudinal axis
L.sub.302 of the rotatable cutting element 302 may be angled (e.g.,
inclined) relative to the vertical plane intersecting the
formation-engaging feature 220. As with the previous embodiment,
the longitudinal axis of the shaft 332A of the impelling feature
332 may be generally aligned with the longitudinal axis L.sub.302
of the rotatable cutting element 302 when the shaft 332A is
retained within the blind bore 310 of the substrate 308. However,
in the embodiment of FIGS. 4A and 4B, the longitudinal axis
L.sub.220 of the formation-engaging feature 220 may not intersect
the longitudinal axis L.sub.302 of the rotatable cutting element
302 at the mating surfaces 330B, 332B. Rather, the longitudinal
axis L.sub.220 of the formation-engaging feature 220 is offset
(e.g., above) the longitudinal axis of the engagement feature 330,
which axis intersects the longitudinal axis L.sub.302 of the
rotatable cutting element 302 at the mating surfaces 330B,
332B.
[0059] FIG. 5 shows a simplified end view of yet another embodiment
of the formation-engaging assembly 300 that may be used in
conjunction with the rotatable cutting element 302, such as the one
shown in FIG. 2. In the embodiment of FIG. 5, the engagement
feature 330 may be different than that of previous embodiments. For
example, the engagement feature 330 may include a single continuous
element extending from the formation-engaging feature 220 directly
to the substrate 308 of the rotatable cutting element 302 to drive
rotation thereof. As in the previous embodiments, the rotatable
cutting element 302 may be mounted to the face 203 of the bit body
202 (FIG. 1). The exterior sidewall 324 of the formation-engaging
feature 220 may be exposed above the face 203 and may be configured
and positioned to rotate responsive to frictional forces acting
between the formation-engaging feature 220 and the engaged
formation. The formation-engaging feature 220 may be retained
within the recess 221 utilizing the attachment feature 326, for
example.
[0060] The difference of the embodiment of FIG. 5 lies in a
specific structure for transferring rotation from the
formation-engaging feature 220 to the rotatable cutting element
302. For example, rather than using a shaft and gear system, the
present embodiment utilizes a single engagement feature 330, such
as a flexible draft shaft. In such a configuration, the engagement
feature 330 may include a drive cable, belt, or chain, for example.
In some embodiments, the engagement feature 330 may include an
aircraft-grade steel cable, such as a galvanized or stainless wire
rope including non-alloy carbon steel material, for example.
Further, the engagement feature 330 may be configured to resist
tensile and compressive forces as well as resist torsional forces,
such that rotation of the formation-engaging feature 220 directly
drives rotation of the rotatable cutting element 302.
[0061] In some embodiments, a proximal end of the engagement
feature 330 may be fixedly coupled within a blind bore or through
hole defined by the interior sidewall 322 of the formation-engaging
feature 220, while a distal end of the engagement feature 330 may
be fixedly coupled within the blind bore 310 of the substrate 308
of the rotatable cutting element 302. In such an embodiment, the
engagement feature 330 may be configured to allow a gradual
curvature (e.g., bend) along at least a portion of the recess 221
to facilitate the transverse orientation between the longitudinal
axis L.sub.220 of the formation-engaging feature 220 and
longitudinal axis L.sub.302 of the rotatable cutting element 302.
Such recesses 221 having a gradual curvature may be manufactured
using, for example, 3D printing or casting in a matrix bit body,
for example. Further, the engagement feature 330 (i.e., flexible
drive shaft) of the embodiment of FIG. 5 may be utilized to drive
rotation of concentric elements, such as the rotatable cutting
element 302 of FIG. 2 or may, alternatively, be used to drive
rotation of eccentric elements, such as a cutting element having an
axis of rotation different than a central longitudinal axis of the
cutting element.
[0062] FIG. 6 shows a simplified perspective view of a portion of
the drill bit 200 shown in FIG. 1. In the embodiment of FIG. 6,
adaptive depth-of-cut control features may be included within the
bit body 202 for maintaining contact between the formation-engaging
feature 220 and the engaged formation while absorbing angular and
axial shock forces on the formation-engaging feature 220. An
actuation device 256 (e.g., hydraulic) may be operatively coupled
to the formation-engaging feature 220 and may be configured to
control rates at which the formation-engaging feature 220 extends
and retracts from the drill bit 200 relative to the face 203 of the
bit body 202. For example, posts and/or shafts of the actuation
device 256 may be coupled to the formation-engaging feature 220. In
some embodiments, the actuation device 256 may be oriented with a
longitudinal axis of the actuation device 256 oriented at an acute
angle (e.g., a tilt) relative to a direction of rotation of the
drill bit 200 in order to minimize a tangential component of a
friction force experienced by the actuation device 256. The
actuation device 256 may be disposed inside the blades 216
supported by the bit body 202 and may be secured to the bit body
202 with a press fit proximate the face 230 thereof, for example.
In some embodiments, at least a portion of the actuation device 256
may be disposed within or proximate to the recess 221 of the
formation-engaging feature 220, which in turn is located proximate
to the rotatable cutting element 302.
[0063] In some embodiments, the actuation device 256 may be passive
and may be self-adjusting. In other embodiments, the actuation
device 256 may be actively controlled. For example, a rate
controller may control a flowrate of a hydraulic fluid through
fluid flow paths associated with the actuation device. In some
embodiments, the actuation device may include a biasing member
(e.g., a spring) alternatively or in addition to utilizing
hydraulics. For example, the actuation device 256 may be similar to
the actuation devices described in U.S. Patent Publication No.
2017/0074047, published Mar. 16, 2017 and U.S. Patent Publication
No. 2017/0175454, published Jun. 22, 2017, the disclosure of each
of which is incorporated in its entirety herein by this reference.
Thus, shock forces may be absorbed by such adaptive depth-of-cut
control features, including the actuation device 256, while
ensuring continuing contact between the formation-engaging feature
220 and the engaged formation in order to facilitate consistent
engagement thereof.
[0064] In each of the embodiments of the present disclosure, the
formation-engaging assemblies 300 including the formation-engaging
features 220 and the rotatable cutting elements 302 may include
selective placement relative to the number and placement of the
fixed cutting elements 210 (as shown in FIG. 1). In other words, it
is contemplated that the fixed cutting elements 210 and the
rotatable cutting elements 302 may be selectively positioned
relative to one another on the blades 216. Further, the number of
cutters (i.e., cutter density) may remain the same or may differ
from that of conventional blades in order to accommodate selective
placement of the formation-engaging features 220 and the rotatable
cutting elements 302 among the fixed cutting elements 210. In some
embodiments, placement and exposure of the fixed cutting elements
210 may be maintained. In other words, an original bit design may
not change with the exception of replacing one or more of the fixed
cutting elements 210 with the rotatable cutting elements 302 in
selected locations (e.g., cone, nose, shoulder, or gage regions) of
the bit body 202.
[0065] In some embodiments, the rotatable cutting elements 302 may
be positioned proximate a front cutting edge of a respective blade
216 (e.g., at a rotationally leading edge of the blades 216) with
the formation-engaging features 220 proximate to (e.g.,
rotationally behind) the rotatable cutting elements 302 and/or the
fixed cutting elements 210. In some embodiments, one or more (e.g.,
two) of the rotatable cutting elements 302 may be positioned
proximate one another on selected blades 216 (e.g., primary blades)
and may be disposed at selected locations rotationally leading
secondary rows of the fixed cutting elements 210 and/or
depth-of-cut control features (e.g., ovoids) on the same blade 216.
Finally, selective placement of the rotatable cutting elements 302
may be utilized on other earth-boring tools, such as, for example,
drag bits having differing blade configurations, hybrid bits, and
other earth-boring tools employing fixed cutting elements and which
may include bodies and/or blades that are fabricated from either
steel or a hard metal "matrix" material.
[0066] Formation-engaging assemblies including rotatable cutting
elements disclosed herein may provide certain advantages over
conventional fixed cutting elements. For example, because the edge
of the cutting element contacting the formation changes as the
rotatable cutting element rotates, the cutting edge remains sharp,
avoiding the generation of a local wear flat. The sharp cutting
edge may increase the rate of penetration while drilling formation,
thereby increasing the efficiency of the drilling operation. The
formation-engaging assemblies including formation-engaging features
configured to drive rotatable cutting elements as disclosed herein
may have additional advantages over conventional rotatable cutting
elements. For example, such rotatable cutting elements may be
forced to rotate upon rotation of the drill string and application
of WOB. In addition, operably coupling such formation-engaging
features to the rotatable cutting elements may provide the
advantage of selecting mating surfaces therebetween to impart
increased torque to the rotatable cutting elements. Further,
revolutions per minute (RPM) of rotation of the rotatable cutting
elements may be determined, at least in part, by RPM of rotation of
the formation-engaging features along with torque transfer
therebetween rather relying solely on direct contact between
rotatable cutting elements and an engaged formation.
[0067] Additional non-limiting example embodiments of the
disclosure are described below.
Embodiment 1
[0068] An earth-boring tool for drilling a subterranean formation,
comprising: a body; at least one cutting element rotatably mounted
on the body, the at least one cutting element comprising a table of
polycrystalline hard material having an end cutting surface and a
supporting substrate; a formation-engaging feature attached to the
body and exposed at a face of the body, the formation-engaging
feature configured to rotate about an axis of rotation responsive
to frictional forces acting between the formation-engaging feature
and a formation when the body moves relative to the formation,
wherein the axis of rotation of the formation-engaging feature is
oriented at an angle to an axis of rotation of the at least one
cutting element; and wherein the formation-engaging feature is
operably coupled to the at least one cutting element such that
rotation of the formation-engaging feature causes rotation of the
at least one cutting element.
Embodiment 2
[0069] The earth-boring tool of Embodiment 1, further comprising: a
first shaft extending from the formation-engaging feature and
carrying a first gear; and a second shaft extending from the at
least one cutting element and carrying a second gear; and wherein
the first gear is engaged with the second gear.
Embodiment 3
[0070] The earth-boring tool of Embodiment 2, wherein each of the
first gear and the second gear comprises a miter gear.
Embodiment 4
[0071] The earth-boring tool of Embodiment 2 or Embodiment 3,
wherein the first gear has a diameter greater than a diameter of
the second gear.
Embodiment 5
[0072] The earth-boring tool of any of Embodiments 2 through 4,
wherein the first gear has a first tooth pattern, and the second
gear has a second tooth pattern, the second tooth pattern differing
from the first tooth pattern.
Embodiment 6
[0073] The earth-boring tool of any of Embodiments 2 through 5,
wherein an axis of rotation of the first shaft is substantially
aligned with the axis of rotation of the formation-engaging
feature, and an axis of rotation of the second shaft is
substantially aligned with the axis of rotation of the at least one
cutting element, and wherein the axis of rotation of the first
shaft is generally perpendicular to the axis of rotation of the
second shaft.
Embodiment 7
[0074] The earth-boring tool of any of Embodiments 1 through 6,
wherein the body comprises at least one blade having a recess
therein, and the formation-engaging feature is mounted at least
partially within the recess.
Embodiment 8
[0075] The earth-boring tool of Embodiment 1, wherein the
formation-engaging feature comprises a first rotational body and a
second rotational body, the first rotational body of the
formation-engaging feature being configured to rotate responsive to
frictional forces acting between the first rotational body and the
formation when the body moves relative thereto, and the second
rotational body being configured to rotate responsive to rotation
of the first rotational body.
Embodiment 9
[0076] The earth-boring tool of Embodiment 8, wherein the first
rotational body of the formation-engaging feature is operably
coupled to the second rotational body of the formation-engaging
feature by at least one of grooves, teeth, or frictional.
Embodiment 10
[0077] The earth-boring tool of any of Embodiments 1 through 9,
wherein the formation-engaging feature is operably coupled to the
at least one cutting element such that one full revolution of the
formation-engaging feature results in less than one full revolution
of the at least one cutting element.
Embodiment 11
[0078] An earth-boring rotary drill bit, comprising: a bit body; a
cutting element mounted on the bit body, the cutting element
comprising a table of polycrystalline hard material having an end
cutting surface and a supporting substrate, the cutting element
being rotatable about a rotational axis; a formation-engaging
feature attached to the bit body and exposed at a face of the bit
body and configured to rotate about an axis of rotation responsive
to frictional forces acting between the formation-engaging feature
and a subterranean formation when the bit body moves relative to
the subterranean formation, wherein the axis of rotation of the
formation-engaging feature is oriented at an angle to an axis of
rotation of the cutting element; and a flexible drive shaft
operably coupled between the formation-engaging feature and the
supporting substrate of the cutting element, the flexible drive
shaft configured to apply torque to the supporting substrate of the
cutting element so as to rotate the cutting element responsive to
rotation of the formation-engaging feature.
Embodiment 12
[0079] The earth-boring rotary drill bit of Embodiment 11, further
comprising a plurality of rotatable cutting elements mounted on the
bit body and a plurality of rotatable formation-engaging features
attached to the bit body and exposed at a face of the bit body,
each formation-engaging feature being operably coupled with a
respective one of the plurality of rotatable cutting elements such
that rotation of each formation-engaging feature drives rotation of
a respective cutting element.
Embodiment 13
[0080] The earth-boring rotary drill bit of Embodiment 11 or
Embodiment 12, wherein the face of the bit body includes a cone
region, a nose region, a shoulder region, and a gage region, and
wherein the cutting element is located in the shoulder region or
the gage region of the face of the bit body.
Embodiment 14
[0081] The earth-boring rotary drill bit of any of Embodiments 11
through 13, wherein the bit body includes blades having a leading
edge, the cutting element is mounted at the leading edge of one of
the blades, and the formation-engaging feature is located
rotationally behind the cutting element.
Embodiment 15
[0082] The earth-boring rotary drill bit of any of Embodiments 11
through 14, wherein the flexible drive shaft comprises non-alloy
carbon steel material.
Embodiment 16
[0083] A method of drilling a subterranean formation, comprising:
applying weight-on-bit to an earth-boring tool substantially along
a longitudinal axis thereof and rotating the earth-boring tool;
engaging a formation with a plurality of rotatable cutting elements
located on blades of a bit body of the earth-boring tool, wherein
the plurality of rotatable cutting elements are rotatably secured
within pockets of the blades; engaging the formation with a
formation-engaging feature attached to the bit body and exposed at
a face of the earth-boring tool and configured to rotate about an
axis of rotation thereof responsive to frictional forces acting
between the formation-engaging feature and the formation when the
earth-boring tool moves relative thereto; and driving rotation of
at least one cutting element of the plurality of rotatable cutting
elements responsive to rotation of the formation-engaging feature,
wherein the axis of rotation of the formation-engaging feature is
oriented at an angle to an axis of rotation of the at least one
cutting element.
Embodiment 17
[0084] The method of Embodiment 16, wherein driving rotation of the
plurality of rotatable cutting elements comprises rotating a first
shaft extending from the formation-engaging feature and carrying a
first gear and rotating a second shaft extending from the at least
one cutting element and carrying a second gear, wherein the first
gear is engaged with the second gear.
Embodiment 18
[0085] The method of Embodiment 17, wherein rotating the first
shaft extending from the formation-engaging feature and carrying
the first gear and rotating a second shaft extending from the at
least one cutting element and carrying the second gear comprises
the first gear having a diameter greater than a diameter of the
second gear.
Embodiment 19
[0086] The method of Embodiment 16 or Embodiment 17, wherein the
axis of rotation of the formation-engaging feature is perpendicular
to an axis of rotation of the at least one cutting element.
Embodiment 20
[0087] The method of any of Embodiments 16 through 19, wherein
rotating the formation-engaging feature through one full revolution
of the formation-engaging feature results in less than one full
revolution of the at least one cutting element.
Embodiment 21
[0088] The method of any of Embodiments 16 through 20, wherein
engaging the formation with the formation-engaging feature
comprises controlling a rate at which the formation-engaging
feature extends and retracts from the face of the earth-boring tool
using a hydraulic actuation device.
[0089] While the present invention has been described herein with
respect to certain illustrated embodiments, those of ordinary skill
in the art will recognize and appreciate that it is not so limited.
Rather, many additions, deletions, and modifications to the
illustrated embodiments may be made without departing from the
scope of the invention as hereinafter claimed, including legal
equivalents thereof. In addition, features from one embodiment may
be combined with features of another embodiment while still being
encompassed within the scope of the invention as contemplated by
the inventors. Further, embodiments of the disclosure have utility
with different and various types and configurations of earth-boring
tools.
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