Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SUPERHARD GOUGING CUTTER OR SHOCK STUD FOR FIXED CUTTER DRILL
BIT
BACKGROUND OF THE DISCLOSURE
Field of the Disclosure
[0001] The present disclosure generally relates to a superhard gouging
cutter or
shock stud for a fixed cutter drill bit.
Description of the Related Art
[0002] US 6,510,910 discloses cutting elements for incorporation in a drill
bit having
a body with an end face interfacing with an ultra hard material cutting layer.
A main
depression having a nonplanar surface is formed on the substrate and extending
to the
peripheral edge of the substrate subjected to the highest impact loads during
drilling.
This edge is immediately below the edge of the cutting layer which makes
direct contact
with the earth formations during drilling. The main depression is formed by
forming a
plurality of secondary depressions or steps. A second main depression is
formed by
forming a plurality of secondary depressions or steps. The second main
depression also
extends to the peripheral edge of the substrate. An ultra hard material layer
is bonded to
the end face of the cutting element body over the main depressions.
[0003] US 7,798,258 discloses a drill bit for cutting a borehole and
including a bit
body having a bit axis. In addition, the drill bit includes a rolling cone
cutter mounted on
the bit body. Further, the drill bit includes a cutter element having a base
portion with a
diameter and a cutting portion extending therefrom. The cutting portion
including a first
pair of flanking surfaces that taper towards one another to form a first
elongate chisel
crest, and a second pair of flanking surfaces that taper towards one another
to form a
second elongate chisel crest that intersects the first elongate chisel crest
in top view.
The first crest tangent angle at 10 percent of the diameter measured radially
from the
central axis on the first elongate chisel crest in profile view is greater
than 75 degrees
and less than or equal to 90 degrees.
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[0004] US 8,365,845 discloses a high impact resistant tool including a
sintered
polycrystalline diamond body bonded to a cemented metal carbide substrate at
an
interface, the body including a substantially pointed geometry with an apex,
the apex
including a curved surface that joins a leading side and a trailing side of
the body at a
first and second transitions respectively, an apex width between the first and
second
transitions is less than a third of a width of the substrate, and the body
also includes a
body thickness from the apex to the interface greater than a third of the
width of the
substrate.
[0005] US 8,794,356 discloses an earth-boring tool including a body, one or
more
blades projecting outwardly from the body, and cutting elements carried by the
blade.
The cutting elements include at least one shearing cutting element and at
least one
gouging cutting element. Methods of forming an earth-boring tool include
mounting a
shearing cutting element including an at least substantially planar cutting
face to a body
of an earth-boring tool, and mounting a gouging cutting element including a
non-planar
cutting face to the body of the earth-boring tool. The gouging cutting element
may be
positioned on the body of the earth-boring tool such that the gouging cutting
element will
gouge formation material within a kerf cut in the formation material by the
shearing
cutting element, or between kerfs cut in the formation material by a plurality
of shearing
cutting elements.
[0006] US 8,839,888 discloses a fixed bladed drill bit including a working
surface
having a plurality of blades converging at a center of the working surface and
diverging
towards a gauge of the bit. Each blade includes a plurality of pointed cutting
elements
and another plurality of shearing cutters. The plurality of shearing cutters
includes a first
shearing cutter on each blade that tracks the first shearing cutter on other
blades along
a common circular cutting path.
[0007] US 8,887,837 discloses a downhole cutting tool including: a tool
body; a
plurality of blades extending azimuthally from the tool body; and a plurality
of cutting
elements disposed on the plurality of blades, the plurality of cutting
elements including:
at least two non-planar cutting elements comprising a substrate and a diamond
layer
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having a non-planar cutting end, wherein at least one of the at least two
conical cutting
elements has a positive back rake angle or positive side rake angle, and at
least one of
the at least two non-planar cutting elements has a negative back rake angle or
a
negative side rake angle.
[00os] US 9,062,505 discloses a method of laser cutting polycrystalline
diamond
tables and polycrystalline diamond compacts.
[0009] US 2018/0087325 discloses a cutting element including a supporting
substrate exhibiting a three-dimensional, laterally elongate shape, and a
cutting table of
a polycrystalline hard material attached to the supporting substrate and
comprising a
non-planar cutting face.
SUMMARY OF THE DISCLOSURE
[cam The present disclosure generally relates to a superhard gouging
cutter or
shock stud for a fixed cutter drill bit. In one embodiment, a gouging cutter
or shock stud
for mounting in a drill bit includes: a substrate being cylindrical for at
least a portion
thereof; and a cap or head made from a superhard material, mounted to the
substrate at
an interface, having a working face formed in an end thereof opposite to the
interface,
and having a round periphery connecting the interface and the substrate. The
working
face has a central tip elevated at a height above a maximum height of the
periphery.
The working face has a plurality of plows and a plurality of ribs arranged
therearound in
an alternating fashion. The plows and the ribs each extend from the periphery
of the
cap inward and upward to the tip. The plows and ribs each have a pair of sides
and an
apical edge. The plows have a different shape than a shape of the ribs.
[cum] In another embodiment, a gouging cutter or shock stud for mounting in
a drill
bit includes: a cylindrical substrate; and a head made from a superhard
material,
mounted to the substrate at an interface, and having a working face formed in
an end
thereof opposite to the interface. The working face has a central tip having a
maximum
height of the working face above the substrate. A plurality of pads and a
plurality of
slots are arranged around the head in an alternating fashion. The pads each
extend
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from a periphery of the substrate inward and upward to the tip. The working
face has
protruding borders formed between the pads. The slots each extend from the
periphery
inward. Each border extends from an inner end of the respective slot to the
central tip.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features of the
present
disclosure can be understood in detail, a more particular description of the
disclosure,
briefly summarized above, may be had by reference to embodiments, some of
which
are illustrated in the appended drawings. It is to be noted, however, that the
appended
drawings illustrate only typical embodiments of this disclosure and are
therefore not to
be considered limiting of its scope, for the disclosure may admit to other
equally
effective embodiments.
[0013] Figures 1A-1D illustrate a superhard polycrystalline gouging cutter
for a fixed
cutter drill bit, according to one embodiment of the present disclosure.
[mu] Figures 2A-2D illustrate a superhard impregnated gouging cutter for a
fixed
cutter drill bit, according to another embodiment of the present disclosure.
[0015] Figures 3A-3D and 4A-4D illustrate a first drill bit having either
one of the
superhard gouging cutters, according to another embodiment of the present
disclosure.
[0016] Figures 5A and 5B illustrate a second drill bit having either one of
the
superhard gouging cutters, according to another embodiment of the present
disclosure.
[0017] Figures 6A-6D illustrate a superhard shock stud for a fixed cutter
drill bit,
according to another embodiment of the present disclosure.
[0018] Figures 7A and 7B illustrate a third drill bit having either one of
the superhard
gouging cutters and the superhard shock stud, according to another embodiment
of the
present disclosure.
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[0191 Figures 7C and 7D illustrate a fourth drill bit having either one of
the
superhard gouging cutters and the superhard shock stud, according to another
embodiment of the present disclosure.
[0020] Figures 8A and 8B illustrate a fifth drill bit having a modified
gouging cutter,
according to another embodiment of the present disclosure.
DETAILED DESCRIPTION
[0021] Figures 1A-1D illustrate a superhard polycrystalline gouging cutter
1p for a
fixed cutter drill bit 11 (Figure 3A), according to one embodiment of the
present
disclosure. The gouging cutter 1 p may include a substrate 2 and a cap 3
mounted to
the substrate. The cap 3 may be made from a polycrystalline superhard
material, such
as polycrystalline diamond (PCD), and the substrate may be made from a hard
material,
such as a cermet. The cermet may be a cemented carbide, such as a group VIIIB
metal-tungsten carbide. The group VIIIB metal may be cobalt. The gouging
cutter 1p
may be manufactured by a high pressure, high temperature (HPHT) sintering
operation
using either a belt press or a cubic press. A working face 3w may then be
formed in the
cap 3 such as by laser cutting or electrical discharge machining.
[0022] The cap 3 may have an interface 4 with the substrate 2, the working
face 3w
at an end thereof opposite to the interface, and a round periphery 3s
connecting the
interface and the working face. The substrate 2 may have the interface 4 with
the cap 3
and a mounting end opposite to the interface for being received in a pocket of
the drill
bit 11. The mounting end of the substrate 2 may have a chamfer 2c formed in a
periphery thereof. The interface 4 may have a planar base 4b, a planar central
tip 4p,
and a conical shoulder 4s connecting the base and the tip. The interface 4 may
be
located in a conical portion of the substrate 2 and the mounting end may be
located in a
cylindrical portion of the substrate.
[0023] The cap 3 may have a central tip 3t formed in the working face 3w
thereof
and elevated at a height above a maximum height of the periphery 3s. A height
of the
tip 3t above the base 4b of the interface 4 may range between one-fifth and
four-fifths of
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a length of the gouging cutter 1 p. The cap 3 may include a plurality of plows
5 (four
shown) formed in the working face 3w thereof and a plurality of ribs 6 (four
shown)
formed in the working face thereof. The plows 5 and the ribs 6 may be arranged
around
the working face 3w in an alternating fashion. The plows 5 and the ribs 6 may
each
extend from the periphery 3s of the cap 3 transversely inward and
longitudinally upward
to the tip 3t. The tip 3t may be flat, may have a round-rectangular, such as
round-
square, shape, and may have rounded edge with a radius 7a ranging between one-
tenth of a millimeter and one-half of a millimeter. The tip 3t may have a
diagonal
extending between the round corners with a length 7b ranging between ten
percent and
forty percent of a diameter of the cap 3.
[0024] At the periphery 3s of the cap 3, each rib 6 may have a triangular
shape. At
the periphery 3s of the cap 3, each rib 6 may have a pair of base edges 6b and
an
apical edge 6a elevated above the base edges. Each rib 6 may also have a pair
of sides
6s formed between the respective base edges 6b and the respective apical edge
6a.
The sides 6s may each be triangular and each apical edge 6a may be convex.
Each
apical edge 6a may also be elevated above the respective sides 6s at the
periphery 3s
of the cap 3. Each base edge 6b and each side 6s may converge toward the
apical
edge 6a as the respective rib 6 extends from the periphery 3s of the cap 3 to
a
respective junction 6j located between the periphery of the cap and the tip 3t
thereof.
Each apical edge 6a may extend with a constant shape and with a constant
radial slope
from the periphery 3s to the respective junction 6j. Each apical edge 6a may
then
radially converge and extend with an exponential radial slope from the
respective
junction 6j to the tip 3t. Each apical edge 6a may then terminate at a side of
the tip 3t.
Each apical edge 6a may be round with a radius 7c ranging between one-quarter
of a
millimeter and one millimeter.
[0025] The plows 5 may have a different shape from a shape of the ribs 6.
At the
periphery 3s of the cap 3, each plow 5 may have a sinusoidal shape. Each plow
5 may
share one of the base edges 6b of each adjacent rib 6 and may have an apical
edge 5a
elevated above the base edges. At the periphery 3s of the cap 3, a height of
each rib
apical edge 6a above the interface 4 may be greater than a height of each plow
apical
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edge 5a there-above and a circumferential width of each rib may be greater
than a
circumferential width of each plow. Each plow 5 may also have a pair of sides
5s and
each plow apical edge 5a may also be elevated above the respective sides 5s at
the
periphery 3s of the cap 3. From the periphery 3s of the cap 3 to the junctions
6j, the
sides 5s of each plow 5 may be formed between the respective base edges 6b and
the
respective apical edge 5a. Each plow side 5s may be concave and the apical
edge 5a
thereof may be convex. Each plow apical edge 5a may extend from the periphery
3s to
the tip 3t with a constant shape and with a constant radial inclination angle
7d. The
radial inclination angle 7d may range between twenty degrees and sixty
degrees. Each
plow apical edge 5a may then terminate at a respective round corner of the tip
3t. Each
plow apical edge 5a may be round with a radius 7e ranging between three-
eighths of a
millimeter and one point five millimeters.
[0026] Each plow side 5s may extend with a constant shape and with a
constat
radial slope from the periphery 3s of the cap 3 to the respective junction 6j.
Each plow
side 5s may then be formed between the adjacent rib apical edge 6a and the
adjacent
plow apical edge 5a from the respective junction 6j to the tip 3t. Each plow
side 5s may
then terminate at a side of the tip 3t. Each plow side 5s may have a fillet
with a radius 7f
ranging between one millimeter and four millimeters. Each plow 5 may have a
maximum thickness 7g at the apical edge 5a ranging between one millimeter and
four
millimeters. The maximum thickness 7g may be constant except for portions
thereof
adjacent to the periphery 3s of the cap 3 and the tip 3t of the working face
3w.
[0027] Alternatively, the tip 3t may be rounded or sharp. Alternatively,
each plow
side 5s may be polygonal instead of concave with a circumferential inclination
angle
ranging between thirty degrees and eighty degrees.
[0028] Figures 2A-2D illustrate a superhard impregnated gouging cutter 1g
for a
fixed cutter drill bit 11, according to another embodiment of the present
disclosure. The
gouging cutter 1g may include a cylindrical substrate 8 and a head 9 mounted
to the
substrate. The head 9 may be made from a composite material, such as a cermet
impregnated with superhard material, such as monocrystalline or thermally
stable
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polycrystalline diamond. The cermet may be a cemented carbide and the diamond
may
be dispersed therein at a content ranging between twenty-five percent and
sixty percent
by volume. The substrate 8 may be similar to the substrate 2, discussed above.
The
gouging cutter 1g may be manufactured by a hot isostatic pressing operation.
The
working face 3w may then be formed in the head 9 such as by laser cutting or
electrical
discharge machining.
[0029] The head 9 may have an interface 10 with the substrate 8, the
working face
3w at an end thereof opposite to the interface, and the periphery 3s
connecting the
interface and the working face. The substrate 8 may have the interface 10 with
the
head 9 and a mounting end opposite to the interface for being received in a
pocket of
the drill bit 11. The mounting end of the substrate 8 may have a chamfer 8c
formed in a
periphery thereof. The interface 10 may be planar. To facilitate
manufacturing, the
substrate 8 may have a lip 8p extending along a periphery thereof between the
interface
and the chamfer 8c. The head 9 may have the central tip 3t formed in the
working face
3w thereof and elevated at a height above a maximum height of the periphery
3s. The
height of the tip 3t above the interface 10 may range between one-third and
one
hundred percent of a length of the substrate 8. The head 9 may include the
plurality of
plows 6 (four shown) formed in the working face 3w thereof and the plurality
of ribs 5
(four shown) formed in the working face thereof.
[0030] Figures 3A-3D and 4A-4D illustrate a first drill bit 11 having
either one 1 of the
gouging cutters 1p,g, according to another embodiment of the present
disclosure. The
drill bit 11 may include a cutting face 12, a bit body 13, a shank 14, and a
gage section
15. A lower portion of the bit body 13 may be made from a composite material,
such as
a ceramic and/or cermet matrix powder infiltrated by a metallic binder, and an
upper
portion of the bit body 13 may be made from a softer material than the
composite
material of the upper portion, such as a metal or alloy shoulder powder
infiltrated by the
metallic binder. The bit body 13 may be mounted to the shank 14 during molding
thereof. The shank 14 may be tubular and made from a metal or alloy, such as
steel,
and have a coupling, such as a threaded pin, formed at an upper end thereof
for
connection of the drill bit 11 to a drill collar (not shown). The shank 14 may
have a flow
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bore formed therethrough and the flow bore may extend into the bit body 13 to
a plenum
(not shown) thereof. The cutting face 12 may form a lower end of the drill bit
1 and the
gage section 15 may form at an outer portion thereof.
[0031] Alternatively, the bit body 13 may be metallic, such as being made
from steel,
and may be hardfaced. The metallic bit body may be connected to a modified
shank by
threaded couplings and then secured by a weld or the metallic bit body may be
monoblock having an integral body and shank.
[0032] The cutting face 12 may include one or more (three shown) primary
blades
16p, one or more (four shown) secondary blades 16s, fluid courses formed
between the
blades, leading cutters 17, backup gouging cutters 1, and shock studs 18. The
cutting
face 12 may have one or more sections, such as an inner cone 12c, an outer
shoulder
12s, and an intermediate nose 12n between the cone and the shoulder sections.
The
blades 16 may be disposed around the cutting face and each blade may be formed
during molding of the bit body 13 and may protrude from a bottom of the bit
body. The
primary blades 16p and the secondary blades 16s may be arranged around the
cutting
face 12 in an alternating fashion. The primary blades 16p may each extend from
a
center of the cutting face 12, across the cone 12c and nose 12n sections,
along the
shoulder section 12s, and to the gage section 15. The secondary blades 16s may
each
extend from a periphery of the cone section 12c, across the nose section 12n,
along the
shoulder section 12s, and to the gage section 15. Each blade 16 may extend
generally
radially across the cone 12c (primary only) and nose 12n sections with a
slight spiral
curvature and along the shoulder section 12s generally longitudinally with a
slight helical
curvature.
[0033] Each blade 16 may be made from the same material as the lower
portion of
the bit body 13. The leading cutters 17 may be pre-formed, such as by high
pressure
and temperature sintering, and mounted, such as by brazing, in respective
leading
pockets formed in the blades 16 adjacent to the leading edges thereof. The
leading
cutters 17 may be mounted into the leading pockets after infiltration of the
bit body 13.
Each blade 16 may have a bearing face 16f extending between a leading edge and
a
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trailing edge thereof. Each leading cutter 17 may be a shear cutter and
include a
superhard cutting table, such as polycrystalline diamond, attached to a hard
substrate,
such as a cermet, thereby forming a compact, such as a polycrystalline diamond
compact (PDC). The cermet may be a carbide cemented by a Group VIIIB metal,
such
as cobalt. The substrate and the cutting table may each be solid and
cylindrical and a
diameter of the substrate may be equal to a diameter of the cutting table.
[0034] Starting in the nose section 12n, each blade 16 may have a row of
backup
pockets formed in the bearing face 16f thereof and extending therealong
through most
of the shoulder section 12s. Each backup pocket may be aligned with or
slightly offset
from a respective leading pocket. The gouging cutters 1 may be mounted into
the
backup pockets after infiltration of the bit body 13 and may be mounted by
brazing or
interference fit. Each blade 16 may have an orientation guide 19, such as a
hole,
formed in the bearing face 16f thereof adjacent to each backup pocket. During
mounting, a technician or robot may align one of the plows 5 of each gouging
cutter 1
with the respective orientation guide 19, thereby ensuring the proper
orientation of the
gouging cutter. The proper orientation may be where the plow 5 adjacent to the
respective leading cutter 17 has a two-dimensionally projected centerline
tangent to a
circle concentric with a center of the cutting face 12 and intersecting a
center of a two-
dimensional projection of the working face 3w.
[0035] The shock studs 18 may protrude from the bearing face 16f of each
primary
blade 16p in the cone section 12c and may be aligned with or slightly offset
from a
respective leading cutter 17. The shock studs 18 may be inserted into a mold
(not
shown) used to infiltrate the bit body 13 and blades 16 such that the shock
studs are
mounted to the blades by bonding during infiltration thereof or the shock
studs may be
mounted into pockets formed in the bearing 16f face thereof, such as by
brazing or
interference fit. Each shock stud 18 may include a cylindrical base portion
(not shown)
and a non-planar working portion. The non-planar working portion may be dome
shaped. The cylindrical base portion may be disposed in the respective pocket
and the
working portion may extend therefrom. Each shock stud may be from a cermet,
such as
a cemented carbide.
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[0036] Each of the cutters 1,17 and shock studs 2 may have an exposed
portion
extending below the bearing faces 16f. The gouging cutters 1 and almost all of
the
leading cutters 17 may have equal exposure 20e demarcated by a primary
exposure
line 20n in Figures 3C (profile of one of the primary blades 16p) and 4C
(profile of all of
the blades 16). The shock studs 18 and a first leading cutter 17 on each
primary blade
may have an exposure 20e slightly less than the primary exposure 20n.
Positions of the
cutters 1,17 may be staggered across the blades 16 to obtain complete and
overlapping
coverage (Figure 4C).
[0037] Each leading cutter 17 may be tilted about a radial rake axis from
the center
of the cutting face 12 to the center thereof (perpendicular to the page in
Figure 4D) by a
back rake angle 22b. The back rake angle 22b may range between ten degrees and
thirty degrees. Each gouging cutter 1 may be tilted about the radial rake axis
by a
forward rake angle 22f which may range between one degree and ten degrees or a
back rake angle (not shown) ranging between one degree and ten degrees.
[0038] Alternatively, each gouging cutter 1 may not be tilted about the
radial rake
axis.
[0039] One or more (seven shown) ports 21p may be formed in the bit body 13
and
each port may extend from the plenum and through the bottom of the bit body to
discharge drilling fluid (not shown) along the fluid courses. A nozzle 21n may
be
disposed in each port 21p and fastened to the bit body 13. Each nozzle 21p may
be
fastened to the bit body 13 by having a threaded coupling formed in an outer
surface
thereof and each port 21p may be a threaded socket for engagement with the
respective threaded coupling. The ports 21p may include an inner set of one or
more
(three shown) ports disposed in the cone section 12c and an outer set of one
or more
(four shown) ports disposed in the nose section 12n and/or shoulder section
12s. Each
inner port 21p may be disposed between an inner end of a respective secondary
blade
16s and the center of the cutting face 12.
[0040] The gage section 15 may define a gage diameter of the drill bit 11.
The gage
section 15 may include a plurality of gage pads 15p, such as one gage pad for
each
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blade 16, and junk slots formed between the gage pads. The junk slots may be
in fluid
communication with the fluid courses formed between the blades 16. The gage
pads
15p may be disposed around the gage section 15 and each pad may be formed
during
molding of the bit body 13 and may protrude from the outer portion of the bit
body.
Each gage pad 15p may be made from the same material as the bit body 13 and
each
gage pad may be formed integrally with a respective blade 16. Each gage pad
15p may
extend upward from an end of the respective blade 16 in the shoulder section
12s to an
exposed outer surface of the shank 14. Each gage pad 15p may include a
transition
portion located adjacent to the shoulder section 12s, a full diameter portion
extending
from the transition portion, and a tapered portion extending from the full
diameter
portion to the shank 14.
[0041] The tapered portion of each gage pad 15p may have a pocket formed in
a
leading edge thereof. An up-drill cutter 15u may be mounted in each pocket of
the
tapered portion. Each up-drill cutter 15u may be mounted into the respective
pocket by
brazing. Each up-drill cutter 15u may be a shear cutter, similar to the
leading cutters 17,
discussed above. Positions of the up-drill cutters 15u may be staggered across
the
gage pads 15p to obtain complete and overlapping coverage.
[0042] Alternatively, the gage pads 15p may have gage protectors embedded
therein. Each gage protector may be a thermally stable polycrystalline
daimond.
[0043] In use (not shown), the drill bit 11 may be assembled with one or
more drill
collars, such as by threaded couplings, thereby forming a bottomhole assembly
(BHA)
(not shown). The BHA may be connected to a bottom of a pipe string, such as
drill pipe
or coiled tubing, thereby forming a drill string. The BHA may further include
a steering
tool, such as a bent sub or rotary steering tool, for drilling a deviated
portion of the
wellbore. The pipe string may be used to deploy the BHA into the wellbore. The
drill bit
1 may be rotated, such as by rotation of the drill string from a rig (not
shown) and/or by
a drilling motor (not shown) of the BHA, while drilling fluid, such as mud,
may be
pumped down the drill string. A portion of the weight of the drill string may
be set on the
drill bit 1. The drilling fluid may be discharged by the nozzles 21n and carry
cuttings up
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an annulus formed between the drill string and the wellbore and/or between the
drill
string and a casing string and/or liner string.
[0044] As the drill bit 11 engages a rock formation (not shown) adjacent to
the
wellbore, each leading cutter 17 may shear the formation while the respective
gouging
cutter 1 may gouge and/or crush the formation, thereby resulting in a dual-
mode attack
on the formation.
[0045] Figures 5A and 5B illustrate a second drill bit 23 having either one
1 of the
superhard gouging cutters 1p,g, according to another embodiment of the present
disclosure. The second drill bit 23 may be similar to the first drill bit 11
except for having
an alternative cutting face. The alternative cutting face may be similar to
the cutting
face 12 except for having modified primary blades 23p instead of the primary
blades
16p, modified shock studs 23d instead of the shock studs 18, and modified
secondary
blades 23s instead of the secondary blades 16s. The modified primary blades
23p may
be similar to the primary blades 16p except for having additional backup
pockets
extending across the nose section thereof and even into the cone section
thereof and
additional gouging cutters 1 mounted into the additional backup pockets.
Further, the
modified primary blades 23p may have the modified shock studs 1d molded into
or
mounted into the cone section thereof instead of the shock studs 18.
[0046] The modified shock studs 23d may be similar to either one of the
gouging
cutters 1 p,d except for having a smaller diameter and length in order to fit
in the more
confined cone section of the modified primary blades 23p. As with the shock
studs 18,
the modified shock studs 23d may have an exposure 20e slightly less than the
primary
exposure 20n. The modified shock studs 23d may be placed in the second drill
bit 23
with a random orientation. The modified secondary blades 23s may be similar to
the
secondary blades 16s except for having the gouging cutters 1 with an exposure
20e
slightly less than the primary exposure 20n. The exposure 20e of the gouging
cutters 1
may also be slightly less than the primary exposure 20n for the modified
primary blades
23p.
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[0047] Figures 6A-6D illustrate a superhard shock stud 24 for a fixed
cutter drill bit
32, according to another embodiment of the present disclosure. The shock stud
24 may
include a cylindrical substrate 25 and a head 26 mounted to the substrate. The
head 26
may be made from the impregnated material, discussed above for the head 9. The
substrate 25 may be similar to the substrate 2, discussed above. The shock
stud 24
may be manufactured by a hot isostatic pressing operation. A working face 26w
may
then be formed in the head 26 such as by laser cutting or electrical discharge
machining.
[0048] The head 26 may have an interface 27 with the substrate 25, the
working face
26w at an end thereof opposite to the interface. The substrate 25 may have the
interface 27 with the head 26 and a mounting end opposite to the interface for
being
received in a pocket of the drill bit 32. The mounting end of the substrate 25
may have
a chamfer 25c formed in a periphery thereof. The interface 27 may be planar.
To
facilitate manufacturing, the substrate 25 may have a lip 25p extending along
a
periphery 25s thereof between the interface and the chamfer 25c.
[0049] The head 26 may include a plurality of pads 28 (four shown) and a
plurality of
slots 29 (four shown). The pads 28 and the slots 29 may be arranged around the
head
26 in an alternating fashion. Each pad 28 may extend from the periphery 25s of
the
substrate 25 transversely inward and longitudinally upward to a tip 26t of the
working
face 26w. The tip 26t may be flat or slightly convex, may have a rectangular,
such as
square, shape, and may have rounded edge with a radius 30a ranging between one-
tenth of a millimeter and one-half of a millimeter. If the tip is 26t slightly
convex, the tip
may have a large radius 30b, such as greater than or equal to one-half of a
diameter of
the substrate 25. The tip 26t may have a width 30c ranging between five
percent and
twenty-five percent of a diameter of the substrate 25. An elevation of the tip
26t above
the interface 27 may be a maximum height of the working face 26w. The height
of the
tip 26t above the interface 27 may range between one-third and one hundred
percent of
a length of the substrate 25.
14
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[0050] The pads 28 may be separated by the slots 29 and by protruding
borders 31
formed in the working face 26w. Each pad 28 may have a rectangular outer
portion 280
and a triangular inner portion 28n. The outer portions may be separated by the
slots 29
and the inner portions 28n may be separated by the protruding borders 31. The
protruding borders 31 may each be rounded or chamfered. The working face of
each
pad 28 may extend from the periphery 25s of the substrate 25 to the tip 26t
with a
constant radial inclination angle 30d. The radial inclination angle 30d may
range
between twenty degrees and sixty degrees. Each pad 28 may then terminate at a
side
of the tip 26t. Each pad 28 may have a round base edge extending from the
interface 27
and having a radius 30e ranging between one-tenth and one-half of a
millimeter. Each
outer portion 280 of the respective pad 28 may have a round outer edge
conforming to
the periphery 25s of the substrate 25, a pair of transversely extending sides,
and
rounded corners connecting the edge and the sides. The base edge of each pad
28 at
the rounded corners may have a radius 30f ranging between one-quarter of a
millimeter
and one millimeter.
[0051] Each slot 29 may extend from the periphery 25s of the substrate 25
transversely inward by a radial distance 30g ranging between one-tenth and
four-tenths
of a diameter of the substrate 25s. Each slot 29 may expose an upper face of
the
substrate 25 and have a maximum height 30h located adjacent to a respective
border
31. The maximum height 30h may range between three-tenths and eight-tenths of
the
height of the tip 26t above the interface 27. The base edge of each pad 28
adjacent to
the respective slot 29 may have a parabolic shape with a lower vertex having a
radius
30j ranging between five-eighths of a millimeter and two point five
millimeters. Each slot
may also have an upper vertex adjacent to the working face of the respective
pad.
Each border 31 may extend from the upper vertex of the respective slot 29 and
may
terminate at a respective rounded corner of the tip 26t.
[0052] Figures 7A and 7B illustrate a third drill bit 32 having either one
1 of the
superhard gouging cutters 1p,g and the superhard shock stud 24, according to
another
embodiment of the present disclosure. The third drill bit 32 may be similar to
the first
drill bit 11 except for having an alternative cutting face. The alternative
cutting face may
CA 3041503 2019-04-29
be similar to the cutting face 12 except for having modified primary blades
32p instead
of the primary blades 16p and the superhard shock studs 24 instead of the
shock studs
18. The modified primary blades 32p may be similar to the primary blades 16p
except
for having the superhard shock studs 24 molded into or mounted into the cone
section
thereof instead of the shock studs 18. As with the shock studs 18, the
superhard shock
studs 24 may have an exposure 20e slightly less than the primary exposure 20n.
The
superhard shock studs 24 may be placed in the third drill bit 32 with a random
orientation.
[0053] Figures 7C and 7D illustrate a fourth drill bit 33 having either one
1 of the
superhard gouging cutters 1p,g and the superhard shock stud 24, according to
another
embodiment of the present disclosure. The fourth drill bit 33 may be similar
to the first
drill bit 11 except for having an alternative cutting face. The alternative
cutting face may
be similar to the cutting face 12 except for having modified primary blades
33p instead
of the primary blades 16p, the superhard shock studs 24 instead of the shock
studs 18,
and modified secondary blades 33s instead of the secondary blades 16s. The
modified
primary blades 33p may be similar to the primary blades 16p except for each
having
only a pair of backup pockets in the nose section thereof and a pair of
gouging cutters 1
disposed therein. Further, the modified primary blades 33p may have the
superhard
shock studs 24 molded into or mounted into the cone section thereof instead of
the
shock studs 18.
[0054] Instead of being aligned with a respective leading cutter 17, each
gouging
cutter 1 and an outer one of the shock studs 24 on each modified primary blade
33p
may be located at an interruptive position between a respective pair of
leading cutters.
As with the shock studs 18, the superhard shock studs 24 may have an exposure
20e
slightly less than the primary exposure 20n. The superhard shock studs 24 may
be
placed in the fourth drill bit 33 with a random orientation. The modified
secondary
blades 33s may be similar to the secondary blades 16s except for having the
gouging
cutters 1 and their associated backup pockets omitted. The exposure 20e of an
inner
one of the gouging cutters 1 on each modified primary blade 33p may also be
slightly
less than the primary exposure 20n for the modified primary blades. The
exposure 20e
16
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of an outer one of the gouging cutters 1 on each modified primary blade 33p
may be
equal to the primary exposure 20n for the modified primary blades 23p.
[0055] Figures 8A and 8B illustrate a fifth drill bit 34 having a modified
gouging cutter
35, according to another embodiment of the present disclosure. The fifth drill
bit 34 may
be similar to the first drill bit 11 except for having an alternative cutting
face 34f and an
alternative gage section. The alternative cutting face may 34f be similar to
the cutting
face 12 except for having modified primary blades 36p instead of the primary
blades
16p, the modified gouging cutters 35 instead of the gouging cutters 1, and
modified
secondary blades 36s instead of the secondary blades 16s.
[cow The modified blades 36p,s may be similar to the blades 16 except for
having
additional backup pockets extending across the shoulder and nose sections
thereof,
having the modified gouging cutters 35 mounted into the backup pockets in the
shoulder
section, and having backup shear cutters 37 mounted into the backup pockets in
the
nose section, such as by brazing. Further, each blade blades 36p,s may have a
second
row of backup pockets formed in the bearing face thereof along most of the
shoulder
section thereof. Backup shear cutters 37 may also be mounted into the second
row of
backup cutters, such as by brazing. Each second backup pocket may be aligned
with
or slightly offset from a respective leading pocket and a respective (first)
backup pocket.
Each backup cutter 37 may be a shear cutter similar to the leading cutter 17,
discussed
above.
[0057] The modified gouging cutters 35 may be similar to the superhard
shock studs
24 except for having a larger diameter and greater length accommodated by the
more
spacious shoulder section of the modified blades 36p,s. Further, each first
backup
pocket in the shoulder section may have the orientation guides 19 formed in
the bearing
face thereof adjacent to the respective first backup pockets. The orientation
guides 19
may be used to align one of the pads of each modified gouging cutters 35 with
the
respective orientation guide, thereby ensuring the proper orientation of the
gouging
cutter. The proper orientation may be where the pad adjacent to the respective
leading
cutter 17 has a two-dimensionally projected centerline tangent to a circle
concentric with
17
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a center of the cutting face 34f and intersecting a center of a two-
dimensional projection
of the working face. The modified gouging cutters 35 may have an exposure
slightly
less than the primary exposure.
[0058] The alternative gage section may be similar to the gage section 15
except for
the omission of the up-drill cutters, having extended transition portions, and
having a
pocket formed in a leading edge of each transition portion. A gage trimmer 38
may be
mounted in each pocket of the transition portion, such as by brazing and may
have a flat
formed therein to adjust a size of the fifth drill bit 34. Each gage trimmer
38 may be a
shear cutter similar to the leading cutter 17, discussed above.
[0059] In another embodiment (not shown), a sixth drill bit may have either
one 1 of
the superhard gouging cutters 1p,g or the superhard shock stud 24 as leading
cutters.
A plurality of any of these cutters 1p,g or shock studs 24 may be disposed in
the leading
pockets instead of the leading cutters 17. These cutters may be oriented at
the forward
rake angle 22f (or back rake angle) as discussed above.
[0060] While the foregoing is directed to embodiments of the present
disclosure,
other and further embodiments of the disclosure may be devised without
departing from
the basic scope thereof, and the scope of the invention is determined by the
claims that
follow.
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