U.S. patent application number 12/511233 was filed with the patent office on 2010-02-04 for earth boring drill bits with using opposed kerfing for cutters.
Invention is credited to Thorsten Schwefe.
Application Number | 20100025121 12/511233 |
Document ID | / |
Family ID | 41607183 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100025121 |
Kind Code |
A1 |
Schwefe; Thorsten |
February 4, 2010 |
EARTH BORING DRILL BITS WITH USING OPPOSED KERFING FOR CUTTERS
Abstract
A drill bit configured having eight blades thereon with
secondary cutters on four blades using opposed kerfing for the
secondary cutters located on four of the blades.
Inventors: |
Schwefe; Thorsten; (Spring,
TX) |
Correspondence
Address: |
TRASKBRITT, P.C.
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
41607183 |
Appl. No.: |
12/511233 |
Filed: |
July 29, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61084811 |
Jul 30, 2008 |
|
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Current U.S.
Class: |
175/431 |
Current CPC
Class: |
E21B 10/43 20130101 |
Class at
Publication: |
175/431 |
International
Class: |
E21B 10/43 20060101
E21B010/43; E21B 10/55 20060101 E21B010/55 |
Claims
1. A drill bit for drilling a subterranean formation comprising: a
bit body having a face, a plurality of primary blades, and a
plurality of secondary blades, each secondary blade of the
plurality of secondary blades located between two blades of the
plurality of primary blades; a first plurality of cutting elements
disposed on a first blade of the plurality of primary blades in
radial positions thereon; a second plurality of cutting elements
disposed on the first blade of the plurality of primary blades, the
second plurality of cutting elements being disposed in radial
position behind the first plurality of cutting elements being
located in radial position at one of substantially between the
cutting elements disposed in front thereof and substantially behind
the cutting elements disposed in front thereof; a third plurality
of cutting elements disposed in radial positions on a first blade
of the plurality of secondary blades, the first blade of the
plurality of secondary blades located adjacent the first blade; a
fourth plurality of cutting elements disposed on a second primary
blade of the plurality of blades; and a fifth plurality of cutting
elements disposed on the second blade of the plurality of primary
blades in radial positions thereon, the fifth plurality of cutting
elements being disposed in radial positions behind the fourth
plurality of cutting elements being located substantially between
the cutting elements disposed in front thereof, at least some of
the fifth plurality of cutting elements having substantially the
same radial positions on the drill bit as the radial positions of
the first plurality of cutting elements on the first blade of the
plurality of primary blades.
2. The drill bit of claim 1, wherein the drill bit includes one of
an even number of blades thereon and an odd number of blades
thereon.
3. The drill bit of claim 2, wherein a plurality of cutting
elements of the at least one type and a plurality of cutting
elements of at least another, different type are disposed on each
blade.
4. The drill bit of claim 1, wherein the first, second, third,
fourth, and fifth cutting elements are disposed in pockets formed
in the blades.
5. The drill bit of claim 1, wherein the first, second, third,
fourth, and fifth cutting elements comprise one of superabrasive
cutting elements and abrasive cutting elements.
6. The drill bit of claim 5, wherein the superabrasive cutting
elements comprise PDC cutting elements and the abrasive cutting
elements comprise tungsten carbide cutting elements.
7. The drill bit of claim 1, wherein a central portion of an outer
profile of the face is configured as an inverted cone and is
surrounded by a nose.
8. The drill bit of claim 1, wherein cutting elements are selected
from the group consisting of a PDC cutting element, a thermally
stable diamond cutting element, and a natural diamond cutting
element.
9. The drill bit of claim 1, wherein the cutting elements are
selected from the group consisting of a tungsten carbide cutting
element, another metal carbide cutting element and a ceramic.
10. The drill bit of claim 1, wherein the second primary blade of
the plurality of primary blades is located approximately
180.degree. circumferentially from the first blade of the plurality
of primary blades.
11. A drill bit for drilling a subterranean formation comprising: a
bit body having a face at a leading end thereof and a plurality of
blades; a first plurality of cutting elements disposed on a first
blade of the plurality of blades in radial positions thereon; a
second plurality of cutting elements disposed on the first blade of
the plurality of blades, the second plurality of cutting elements
being disposed in radial position behind the first plurality of
cutting elements being located in radial position at one of
substantially between the cutting elements disposed in front
thereof and substantially behind the cutting elements disposed in
front thereof; a third plurality of cutting elements disposed in
radial positions on a second blade of the plurality of blades, the
second blade located adjacent the first blade; a fourth plurality
of cutting elements disposed on a third blade located approximately
180.degree. circumferentially from the first blade of the plurality
of blades in radial positions thereon; and a fifth plurality of
cutting elements disposed on the third blade of the plurality of
blades in radial positions thereon, the fifth plurality of cutting
elements being disposed in radial positions behind the fourth
plurality of cutting elements being located substantially between
the cutting elements disposed in front thereof, at least some of
the fifth plurality of cutting elements having substantially the
same radial positions on the drill bit as the radial positions of
the first plurality of cutting elements on the first blade.
12. The drill bit of claim 11, wherein the drill bit includes one
of an even number of blades thereon and an odd number of blades
thereon.
13. The drill bit of claim 12, wherein a plurality of cutting
elements of the at least one type and a plurality of cutting
elements of at least another, different type are disposed on each
blade.
14. A drill bit for drilling a subterranean formation comprising: a
bit body having an even number of blades; a first plurality of
cutting elements disposed on a first blade of the plurality of
blades in radial positions thereon; a second plurality of cutting
elements disposed on the first blade of the plurality of blades,
the second plurality of cutting elements being disposed in radial
position behind the first plurality of cutting elements being
located in radial position substantially behind the cutting
elements disposed in front thereof; a third plurality of cutting
elements disposed in radial positions on a second blade of the
plurality of blades, the second blade located adjacent the first
blade; a fourth plurality of cutting elements disposed on a third
blade located approximately 180.degree. circumferentially from the
first blade of the plurality of blades in radial positions thereon;
and a fifth plurality of cutting elements disposed on the third
blade of the plurality of blades in radial positions thereon, the
fifth plurality of cutting elements being disposed in radial
positions behind the fourth plurality of cutting elements being
located substantially behind the cutting elements disposed in front
thereof, at least some of the fifth plurality of cutting elements
having substantially the same radial positions on the drill bit as
the radial positions of the first plurality of cutting elements on
the first blade.
15. The drill bit of claim 14, wherein the first, second, third,
fourth, and fifth cutting elements are disposed in pockets formed
in the blades.
16. The drill bit of claim 14, wherein the first, second, third,
fourth, and fifth cutting elements comprise one of superabrasive
cutting elements and abrasive cutting elements.
17. A drill bit for drilling a subterranean formation comprising: a
bit body having an even number of blades; a first plurality of
cutting elements disposed on a first blade of the plurality of
blades in radial positions thereon; a second plurality of cutting
elements disposed on the first blade of the plurality of blades,
the second plurality of cutting elements being disposed in one of a
radial position including one of substantially behind the cutting
elements disposed in front thereof and substantially behind the
cutting elements disposed in front thereof; a third plurality of
cutting elements disposed in radial positions on a second blade of
the plurality of blades, the second blade located adjacent the
first blade; a fourth plurality of cutting elements disposed on a
third blade located less than approximately 180.degree.
circumferentially from the first blade of the plurality of blades
in radial positions thereon; and a fifth plurality of cutting
elements disposed on the third blade of the plurality of blades in
radial positions thereon, the fifth plurality of cutting elements
being disposed in radial positions including one of substantially
behind the cutting elements disposed in front thereof and
substantially behind the cutting elements disposed in front
thereof, at least some of the fifth plurality of cutting elements
having substantially the same radial positions on the drill bit as
the radial positions of the first plurality of cutting elements on
the first blade.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/084,811, filed Jul. 30, 2008, the
disclosure of which is incorporated herein in its entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to drilling a
subterranean borehole and, more specifically, to drill bits using
opposed kerfing profiles for cutters.
BACKGROUND OF THE INVENTION
[0003] State of the Art: The drilling of wells for any reason, such
as oil and gas production, geothermal production, water production,
etc. conventionally may employ drill bits using diamond cutters
located on a variable number of blades of the drill bit. Typically,
drill bits having a fewer number of blades on the drill bit tend to
cut faster and have bigger junk slots for the removal of cutting
from the well bore than drill bits having more blades. However,
when the number of blades on the drill bit and the number of
cutters on the drill bit are increased, the loading on each cutter
can be reduced, thereby improving cutter life and drill bit life
during drilling a well bore.
[0004] It would be desirable to reduce the number of blades on a
drill bit to increase the rate of penetration of the drill bit in
comparison to that of a drill bit having more blades thereon, while
reducing individual cutter loading to increase cutter life and
drill bit life.
BRIEF SUMMARY OF THE INVENTION
[0005] A drill bit configured having multiple blades thereon with
secondary cutters on a reduced number of blades (secondary blades)
of the drill bit, using opposed kerfing for the secondary cutters
located on the secondary blades.
[0006] The features and advantages of the present invention will
become apparent to those of ordinary skill in the art through
consideration of the ensuing description, the accompanying
drawings, and the appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0007] In the drawings, which illustrate what is currently
considered to be the best mode for carrying out the invention:
[0008] FIG. 1 shows a perspective view of a drill bit;
[0009] FIG. 2A shows an enlarged perspective view of an embodiment
of the drill bit described herein;
[0010] FIG. 2B shows an enlarged perspective view of another
embodiment of the drill bit described herein;
[0011] FIG. 3A shows an enlarged view of a portion of the face of
the drill bit of FIG. 2;
[0012] FIG. 3B shows an enlarged view of a portion of the face of
the drill bit of FIG. 2;
[0013] FIG. 4A shows a schematic side cross-sectional view of a
cutting element placement design of a drill bit described herein
showing relative exposures of first and second types of cutting
elements disposed thereon;
[0014] FIG. 4B shows a schematic side cross-sectional view of a
cutting element placement design of a drill bit described herein
showing alternative relative exposures of first and second types of
cutting elements disposed thereon;
[0015] FIG. 5A is a perspective view of one configuration of a
cutting element for the drill bit;
[0016] FIG. 5B is a frontal view of the cutting element;
[0017] FIG. 5C is a cross-sectional view taken through line 5C-5C
on FIG. 5B;
[0018] FIG. 5D is an enlarged view of the cutting edge of the
cutting element in the circled area of FIG. 5C; and
[0019] FIGS. 6A-6H show schematically other configurations of the
cutting elements suitable for a drill bit, wherein FIGS. 6A, 6C, 6E
and 6G show transverse configurations of the cutting elements, and
FIGS. 6B, 6D, 6F and 6H show side views.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIGS. 1-3 illustrate an embodiment of a drill bit 12 in the
form of a fixed cutter or so-called "drag" bit described herein. As
shown in FIGS. 1-3, drill bit 12 includes a body 14 having a face
26 and generally radially extending blades 22, forming fluid
courses 24 therebetween extending to junk slots 35 between
circumferentially adjacent blades 22. Bit body 14 may comprise a
tungsten carbide matrix or a steel body, both as well known in the
art. Blades 22 may also include pockets 30, which may be configured
to receive cutting elements of one type such as, for instance,
superabrasive cutting elements in the form of PDC cutting elements
32. Generally, such a PDC cutting element may comprise a
superabrasive region that is bonded to a substrate. Rotary drag
bits employing PDC cutting elements have been employed for several
decades. PDC cutting elements are typically comprised of a
disc-shaped diamond "table" formed on and bonded under a
high-pressure and high-temperature (HPHT) process to a supporting
substrate such as cemented tungsten carbide (WC), although other
configurations are known. Drill bits carrying PDC cutting elements,
which, for example, may be brazed into pockets in the bit face,
pockets in blades extending from the face, or mounted to studs
inserted into the bit body, are known in the art. Thus, PDC cutting
elements 32 may be affixed upon the blades 22 of drill bit 12 by
way of brazing, welding, or as otherwise known in the art. It is
also contemplated that cutting elements 32 may comprise suitably
mounted and exposed natural diamonds, thermally stable
polycrystalline diamond compacts, cubic boron nitride compacts, or
diamond grit-impregnated segments, as known in the art and as may
be selected in consideration of the subterranean formation or
formations to be drilled.
[0021] Also, each of blades 22 may include a gage region 25 that is
configured to define the outermost radius of the drill bit 12 and,
thus the radius of the wall surface of a borehole drilled thereby.
Gage regions 25 comprise longitudinally upward (as the casing bit
12 is oriented during use) extensions of blades 22, extending from
nose portion 20 and may have wear-resistant inserts or coatings,
such as cutting elements in the form of gage trimmers of natural or
synthetic diamond, or hardfacing material, on radially outer
surfaces thereof as known in the art to inhibit excessive wear
thereto.
[0022] Drill bit 12 is also provided with pockets 34 in four of the
blades 22, which may be configured to receive abrasive cutting
elements 36 of similar type as those of the first type of cutting
elements 32, cutting elements 36 being located in a second row of
cutting elements located behind the cutting elements 32 of the
first row on four of the eight blades of the drill bit 12. It is
also contemplated that abrasive cutting elements 36 may comprise,
for example, a carbide material other than tungsten (W) carbide,
such as a Ti, Mo, Nb, V, Hf, Ta, Cr, Zr, Al, and Si carbide, or a
ceramic. Abrasive cutting elements 36 may be secured within pockets
34 by welding, brazing or as otherwise known in the art.
[0023] As depicted in FIGS. 1-3, abrasive cutting elements 36 may
be of substantially uniform or varying thickness, taken in the
direction of intended bit rotation. As shown in FIGS. 1-3, abrasive
cutting elements 32, 36 may be of varying thickness, taken in the
direction of bit rotation, wherein abrasive cutting elements 36 at
more radially outward locations (and, thus, which traverse
relatively greater distance for each rotation of drill bit 12 than
those, for example, within the cone of dill bit 12) may be thicker
to ensure adequate material thereof will remain for cutting.
[0024] Also as shown in FIGS. 1-3, cutting elements 36 may be
placed in an area from the cone of the bit on four blades 22
thereof out to the shoulder (in the area from the centerline L to
gage regions 25) to provide cutting elements in similar positions
as cutting elements 32, only opposed a desired variable number of
degrees rotation, typically 180.degree. rotation, from a
corresponding cutting element 32, which additionally allows the
cutters 36 in the second row on a blade 22 to sit between adjacent
cutters 32 in the row in front of the cutting elements 36 on the
blade 22. That is, cutting elements 36' have substantially the same
radial position on the drill bit 12 as the radial positions of
cutting elements 36'' only being positioned on blades 22 any
desired variable number of degrees of rotation; i.e., substantially
180.degree. from each other on the drill bit 12. Broadly, cutting
elements 32 on face 26, which may be defined as surfaces at less
than 90.degree., profile angles, or angles with respect to
centerline L. Cutting elements 36 are also placed selectively along
the profile of the face 26 to provide enhanced cutting of the drill
bit 12 and enhanced durability of the drill bit 12.
[0025] Superabrasive cutting elements 32 and superabrasive cutting
elements 36 are respectively dimensioned and configured, in
combination with the respective depths and locations of pockets 30
and 34, to provide cutting elements 36 with the same relative
exposure as cutting elements 32, although cutting elements 36 may
have a greater or lesser relative exposure than superabrasive
cutting elements 32, if desired. As used herein, the term
"exposure" of a cutting element generally indicates its distance of
protrusion above a portion of a drill bit, for example, a blade
surface or the profile thereof, to which it is mounted. However, in
reference specifically to the present invention, "relative
exposure" is used to denote a difference in exposure between a
cutting element 32 of the one type and a cutting element 36 of the
same type. More specifically, the term "relative exposure" may also
be used to denote a difference in exposure between one cutting
element 32 and another cutting element 36, which are proximately
located on drill bit 12 at similar radial positions relative to a
centerline L (see FIGS. 4A, 4B) of drill bit 12 but offset from
each other by 180.degree. on different blades 22 in a direction of
bit rotation.
[0026] In the embodiment depicted in FIGS. 1, 2, and 3, cutting
elements 36 may generally be described as rotationally "following"
some of the cutting elements 32 and in close rotational proximity
to on the blades 22 on four of the eight blades of the drill bit
12, as well as being located at substantially the same radius
although being offset 180.degree. therefrom another cutting element
32 on an exposed blade 22 of the four blades 22 of the eight blades
22 of the drill bit 12. However, if desired, abrasive cutting
elements 36 may also be located to rotationally "lead" associated
superabrasive cutting elements 32.
[0027] Referring to FIGS. 2A and 3A, in another embodiment of the
drill bit 12, cutting elements 36 may be placed in an area from the
cone of the bit on four blades 22 thereof out to the shoulder (in
the area from the centerline L to gage regions 25) to provide
cutting elements in similar positions as cutting elements 32, only
opposed 180.degree. from a corresponding cutting element 32, which
additionally allows the cutters 36 in the second row on a blade 22
to sit behind adjacent cutting elements 32 in the row in front of
the cutting elements 36 on the blade 22. That is, cutting elements
36' have substantially the same radial position on the drill bit 12
as the radial positions of cutting elements 36'' only being
positioned on blades 22 substantially 180.degree., an angular
distance along or around the drill bit 12, from each other on the
drill bit 12 and behind the cutting elements 32 located in front
thereof. Broadly, cutting elements 32 on face 26, which may be
defined as surfaces at less than 90.degree., profile angles, or
angles with respect to centerline L. Cutting elements 36 are also
placed selectively along the profile of the face 26 to provide
enhanced cutting of the drill bit 12 and enhanced durability of the
drill bit 12.
[0028] By way of illustration of the foregoing, FIG. 4A shows a
schematic side view of a cutting element placement design for drill
bit 12 showing cutting elements 32, 36 as disposed on a drill bit
(not shown) such as drill bit 12 of the present invention in
relation to the longitudinal axis or centerline L and drilling
profile P thereof for all 124 cutting elements 32, 36 on the drill
bit 12, as if all the cutting elements 32, 36 were rotated onto a
single blade (not shown). The plurality of cutting elements 32, 36
are sized, configured, and positioned to drill into any desired
subterranean formation. The reduction of drill bit 12 to an eight
blade configuration provides a drill bit having a greater rate of
penetration during drilling than a drill bit having twelve blades
with the durability of a drill bit having twelve blades by
substantially maintaining the cutting element loading as the same
by using the same number of cutting elements on the drill bit with
four of eight blades having two rows of cutting elements thereon
and by using opposed kerfing regarding the second row of cutting
elements and being located at the same radial position only located
180.degree. angularly as described herein from the same cutting
element.
[0029] By way of illustration of the foregoing, FIG. 4B shows a
schematic side view of a cutting element placement design for drill
bit 12 showing cutting elements 32, 36 as disposed on a drill bit
(not shown) such as drill bit 12 of the present invention in
relation to the longitudinal axis or centerline L and drilling
profile P thereof for all 124 cutting elements 32, 36 on the drill
bit 12, as if all the cutting elements 32, 36 were rotated onto a
single blade (not shown) when the cutting elements 36 in the second
row of cutting elements on the four blades of the eight blades are
located directly behind the cutting elements 32 on the four blades
having the same exposure as the cutting elements 32. The plurality
of cutting elements 32, 36 are sized, configured, and positioned to
drill into any desired subterranean formation. In this instance,
the reduction of drill bit 12 to an eight blade configuration
provides a drill bit having approximately the same rate of
penetration during drilling as a drill bit having twelve blades
with the durability of a drill bit having twelve blades by
substantially maintaining the loading on the cutting elements as
the same by using the same number of cutting elements on the drill
bit with four of eight blades having two rows of cutting elements
thereon and by using opposed kerfing regarding the second row of
cutting elements and being located at the same radial position only
located 180.degree. from the same cutting element.
[0030] FIGS. 5A-5D depict one example of a suitable configuration
for cutting elements 36, including a disc-like body 100 of tungsten
carbide or other suitable material and having a circumferential
chamfer 102 at the rear (taken in the direction of intended cutter
movement) thereof, surrounding a flat rear surface 104. A
cylindrical side surface 106 extends from chamfer 102 to an annular
flat 108 oriented perpendicular to longitudinal axis 110 and
extending inwardly to offset chamfer 112, which leads to flat
cutting face 114. An area from the junction of side surface 106
with annular flat 108 to the junction of offset chamfer 112 with
cutting face may be generally termed the cutting edge area, for the
sake of convenience. The angles of chamfer 102 and offset chamfer
112 may be, for example, 45.degree. to longitudinal axis 110.
However, other angles are contemplated and a specific angle is not
limiting of the present invention. Cutting elements 36 may be
disposed on the face 26 (as on blades 22) of drill bit 12 at, for
example, a forward rake, a neutral (about 0.degree.) rake or a back
rake of up to about 25.degree., for effective cutting of a casing
shoe, casing bit, cementing equipment components, and cement,
although a specific range of back rakes for cutting elements 36 is
not limiting of the present invention.
[0031] FIGS. 6A-6H depict other suitable configurations for cutting
elements 36. The cutting element 36 depicted in FIGS. 6A and 6B is
circular in transverse configuration and, as shown in FIG. 6B, has
a cutting edge area configured similar to that of cutting element
36 depicted in FIGS. 5A-5D. However, rear surface 104 is sloped
toward the front of the cutting element (in the intended cutting
direction shown by the arrow), providing a thicker base and a
thinner outer edge for cutting, to enhance faster wear when
formation material is engaged. The cutting element 36 depicted in
FIGS. 6C and 6D is also circular in transverse configuration and,
as shown in FIG. 6D, has a cutting edge area configured similar to
that of cutting element 36 depicted in FIGS. 5A-5D. However, rear
surface cutting face 114 is sloped toward the rear of the cutting
element, providing a thicker base and a thinner outer edge for
cutting, to enhance faster wear when formation material is engaged.
The cutting element 36 depicted in FIGS. 6E and 6F is also circular
in transverse configuration and, as shown in FIG. 6F, has a cutting
edge area configuration similar to that of cutting element 36
depicted in FIGS. 5A-5D. However, cutting face 114 is sloped toward
the rear of the cutting element from the cutting edge area,
providing a thinner base and a thicker outer edge for cutting, to
provide more cutting element material for extended cutting of
casing components and the like. The cutting element 36 depicted in
FIGS. 6G and 6H is ovoid or egg-shaped in transverse configuration
and, as shown in FIG. 6H, has a cutting edge area similar to that
of cutting element 36 depicted in FIGS. 5A-5D. Cutting face 114 and
rear surface 104 are mutually parallel. The ovoid configuration
provides enhanced loading of material being cut by the cutting
element to facilitate initial engagement thereby.
[0032] Although the foregoing description contains many specifics,
these should not be construed as limiting the scope of the present
invention, but merely as providing illustrations of some exemplary
embodiments. Similarly, other embodiments of the invention may be
devised that do not depart from the spirit or scope of the present
invention. Features from different embodiments may be employed in
combination. The scope of the invention is, therefore, indicated
and limited only by the appended claims and their legal
equivalents, rather than by the foregoing description. All
additions, deletions, and modifications to the invention, as
disclosed herein, which fall within the meaning and scope of the
claims, are to be embraced thereby.
* * * * *