U.S. patent application number 12/373938 was filed with the patent office on 2010-05-27 for helical chisel insert for rock bits.
This patent application is currently assigned to Ulterra Drilling Technology L.P.. Invention is credited to Michael Burl Crawford, Richard August Flak, Pele Jason Nunley.
Application Number | 20100126775 12/373938 |
Document ID | / |
Family ID | 38982310 |
Filed Date | 2010-05-27 |
United States Patent
Application |
20100126775 |
Kind Code |
A1 |
Crawford; Michael Burl ; et
al. |
May 27, 2010 |
HELICAL CHISEL INSERT FOR ROCK BITS
Abstract
An insert for an earth boring drill bit, such as a PDC rock bit
or a roller cone rock bit, is provided. The insert includes a base
integrally joined to a top section, the top section having a first
flank that curves in a substantially helical manner about a
longitudinal axis of the insert to join a crest.
Inventors: |
Crawford; Michael Burl;
(Montgomery, TX) ; Nunley; Pele Jason; (Mansfield,
TX) ; Flak; Richard August; (Mansfield, TX) |
Correspondence
Address: |
WINSTEAD PC
P.O. BOX 50784
DALLAS
TX
75201
US
|
Assignee: |
Ulterra Drilling Technology
L.P.
Forth Worth
TX
|
Family ID: |
38982310 |
Appl. No.: |
12/373938 |
Filed: |
July 25, 2007 |
PCT Filed: |
July 25, 2007 |
PCT NO: |
PCT/US2007/074357 |
371 Date: |
February 12, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60833174 |
Jul 25, 2006 |
|
|
|
Current U.S.
Class: |
175/61 ; 175/327;
175/420.1 |
Current CPC
Class: |
E21B 10/52 20130101;
E21B 10/567 20130101 |
Class at
Publication: |
175/61 ;
175/420.1; 175/327 |
International
Class: |
E21B 7/04 20060101
E21B007/04; E21B 10/36 20060101 E21B010/36; E21B 10/00 20060101
E21B010/00 |
Claims
1. An insert for an earth boring drill bit having a base integrally
joined to a top section, the top section having a first flank that
curves in a substantially helical manner about a longitudinal axis
of the insert to join a crest.
2. The insert of claim 1, further comprising a polycrystalline
diamond compact (PDC) insert.
3. The insert of claim 2, wherein the earth boring device is a PDC
rock bit.
4. The insert of claim 1, further comprising a second flank that
curves in a substantially helical manner about the longitudinal
axis of the insert to join the crest.
5. The insert of claim 4, further comprising a degree of twist in a
range from about 0.degree. to about 90.degree..
6. The insert of claim 5, wherein the flanks curve in either a
substantially clockwise manner or a substantially counterclockwise
manner.
7. The insert of claim 6, further comprising a tungsten carbide
insert (TCI).
8. The insert of claim 6, further comprising a diamond enhanced
TCI.
9. The insert of claim 6, wherein the earth boring device is a
rotary cone rock bit.
10. The insert of claim 6, wherein the earth boring device is a PDC
rock bit.
11. The insert of claim 5, further comprising a timing mark.
12. A drill bit for boring an earth formation, the drill bit
comprising a plurality of helical chisel inserts.
13. The drill bit of claim 12, wherein the drill bit further
comprises a PDC drill bit.
14. The drill bit of claim 12, further comprising a rotary cone
rock bit having a plurality of cutters for plowing the formation in
a selected direction, wherein each cutter has a circumferential
outermost heel row with helical chisel inserts positioned
thereon.
15. The drill bit of claim 14, wherein each cutter has a
circumferential second row with helical chisel inserts positioned
thereon
16. The drill bit of claim 15, wherein the helical chisel insert
further comprises a base integrally joined to a top section, the
top section having a leading flank and a trailing flank that curve
in a substantially helical manner about a longitudinal axis of the
insert to join an elongated crest.
17. The drill bit of claim 16, wherein the elongated crests of the
helical chisel inserts positioned on the heel row are substantially
in line with the direction of plowing of the formation.
18. The drill bit of claim 17, wherein the elongated crests of the
helical chisel inserts positioned on the second row are
substantially in line with the direction of plowing of the
formation.
19. The drill bit of claim 16, wherein a broad side of the
elongated crests of the helical chisel inserts positioned on the
heel row substantially face the direction of plowing of the
formation.
20. The drill bit of claim 19, wherein a broad side of the
elongated crests of the helical chisel inserts positioned on the
second row substantially face the direction of plowing of the
formation.
21. A method for drilling an earth formation, comprising the steps
of: providing a rotary cone cutter having a plurality of cutters,
wherein each cutter has an axis of rotation for plowing the
formation in a direction, and comprises an outermost heel row and a
second row; positioning a first set of helical chisel inserts on
the heel row; and positioning a second set of helical chisel
inserts on the second row, wherein the helical chisel inserts each
comprise a base integrally joined to a top section, the top section
having a leading flank and a trailing flank that curve in a
substantially helical manner about a longitudinal axis of the
insert to join an elongated crest.
22. The method of claim 21, further comprising the steps of:
aligning the elongated crests of the first set of helical chisel
inserts at an azimuth direction from about 30 degrees to about 60
degrees from the axis of rotation of the cutter; and aligning the
elongated crests of the second set of helical chisel inserts at an
azimuth direction from about 300 degrees to about 330 degrees from
the axis of rotation of the cutter.
23. The method of claim 21, further comprising the steps of:
aligning the elongated crests of the first set of helical chisel
inserts at an azimuth direction from about 300 degrees to about 330
degrees from the axis of rotation of the cutter; and aligning the
elongated crests of the second set of helical chisel inserts at an
azimuth direction from about 30 degrees to about 60 degrees from
the axis of rotation of the cutter.
24. The method of claim 21, further comprising the steps of:
aligning the elongated crests of the first set of helical chisel
inserts and the second set of helical inserts substantially in line
with the direction of plowing of the formation.
25. The method of claim 21, further comprising the steps of:
aligning the elongated crests of the first set of helical chisel
inserts and the second set of helical chisel inserts substantially
perpendicular to the direction of plowing of the formation.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/833,174 filed Jul. 25, 2006.
FIELD OF THE INVENTION
[0002] This invention relates in general to earth boring devices
used in oil field applications, and, more particularly, to inserts
for earth boring rotary cone rock bits.
BACKGROUND
[0003] Conventional earth boring rotary cone rock bits are commonly
used in oil field applications. Rotational energy and weight
applied to the bit by the drill pipe force the rotary cutters into
earth formations. The borehole is formed as the punching and
scraping action of the rotary cutters remove chips of formation.
The rate at which borehole is formed is largely a result of the
design of the rotary cutters. One main category of rotary cutters
is tungsten carbide insert (TCI) cutters. The teeth on TCI cutters
are made of tungsten carbide and are press fit (inserted) into
undersize apertures on the cone. The teeth on the cutters
functionally break up the formation to form new borehole by
punching into it vertically and scraping horizontally. The amount
of punching action is governed primarily by the weight on the bit.
The horizontal scraping motion is a resultant of the position and
shape of the cone cutter.
[0004] Medium and soft formation bits usually drill through varied
formations in a single well. Recording devices which show
instantaneous rates of penetration will often show rates as high as
four feet per minute and rates as slow as one foot in ten minutes
on the same bit run. As a rule, the formations tend to become
harder as depth increases but there are large variations in
hardness at all depths.
[0005] Bits having long inserts are typically most efficient for
fast drilling in soft formations. Long inserts are relatively weak
though, and are subject to breakage in the slower drilling hard
formations. Short blunt inserts are better suited for the harder
formations because they are less subject to breakage, but they
limit a bit's penetration rate in soft formations.
[0006] Accordingly, there is a need for wear resistant inserts for
drilling bits that provide a high rate of penetration in both soft
and hard formations while providing resistance to insert
breakage.
SUMMARY OF THE INVENTION
[0007] An insert for an earth boring drill bit is provided. The
insert includes a base integrally joined to a top section, the top
section having a first flank that curves in a substantially helical
manner about a longitudinal axis of the insert to join a crest.
[0008] A drill bit for boring an earth formation is provided. The
drill bit includes a plurality of helical chisel inserts.
[0009] A method for drilling an earth formation is provided. The
method includes the steps of providing a rotary cone cutter having
a plurality of cutters, wherein each cutter has an axis of rotation
for plowing the formation in a direction, and comprises an
outermost heel row and a second row, positioning a first set of
helical chisel inserts on the heel row, and positioning a second
set of helical chisel inserts on the second row. The helical chisel
inserts each include a base integrally joined to a top section, the
top section having a leading flank and a trailing flank that curve
in a substantially helical manner about a longitudinal axis of the
insert to join an elongated crest.
[0010] The foregoing has outlined rather generally the features and
technical advantages of one or more embodiments of the present
invention in order that the detailed description of the present
invention that follows may be better understood. Additional
features and advantages of the present invention will be described
hereinafter which may form the subject of the claims of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A better understanding of the present invention can be
obtained when the following detailed description is considered in
conjunction with the following drawings, in which:
[0012] FIG. 1 is a cross-sectional view of a portion of an
embodiment of a TCI tri-cone rock drill bit of the present
invention, showing one cone cutter rotatably mounted on a bearing
pin shaft;
[0013] FIG. 2 is a front elevational view of an embodiment of the
rock drill bit insert of the present invention;
[0014] FIG. 3 is a top view of the insert of FIG. 2;
[0015] FIG. 4 is a front elevational view of another embodiment of
the rock drill bit insert of the present invention;
[0016] FIG. 5 is a schematic view of a bore hole bottom showing
insert tracks left by an embodiment of the roller cone cutter,
wherein the helical chisel inserts have been positioned for
reducing insert breakage; and
[0017] FIG. 6 is a schematic view of a bore hole bottom showing
insert tracks left by an embodiment of the roller cone cutter,
wherein the helical chisel inserts have been positioned for
increasing penetration rate.
DETAILED DESCRIPTION
[0018] Refer now to the drawings wherein depicted elements are not
necessarily shown to scale and wherein like or similar elements are
designated by the same reference numeral through the several
views.
[0019] As used herein, the terms "up" and "down"; "upper" and
"lower"; "uphole" and "downhole" and other like terms indicating
relative positions to a given point or element are utilized to more
clearly describe some elements of the embodiments of the invention.
Commonly, these terms relate to a reference point as the surface
from which drilling operations are initiated as being the top point
and the total depth of the well being the lowest point.
[0020] The present invention is directed to a helical chisel insert
for a drill bit, such as a roller cone bit. The helical design of
the insert provides an aggressive shape for increased penetration
during drilling. In addition, the helical chisel insert is suitable
for positioning the inserts in a vectored manner on the drill bit
to achieve an orientation that provides increased resistance to
insert breakage and/or and increased rate of penetration.
[0021] FIG. 1 shows a drill bit in accordance with an embodiment of
the present invention, indicated by 2. Drill bit 2 has a threaded
section 4 on its upper end for securing to the drill string (not
shown). A frusto-conical roller cone cutter 8 is rotatably mounted
and secured on the bearing pin shaft 16 which extends downward and
inward, from the bottom of the journal segment arm 6. Cone cutter 8
has a cutting structure consisting of helical chisel inserts 22.
Helical chisel inserts 22 are mounted on either heel row 10, second
row 12, inner row 14, or any combination thereof Helical chisel
inserts 22 may be press fit into hole 9 or otherwise positioned on
cone cutter 8. Helical chisel inserts 22 may be made from any
suitable material including tungsten carbide, diamond enhanced
tungsten carbide, diamond or polycrystalline diamond compact (PDC).
Cone cutter 8 may include conventional inserts on those rows where
helical chisel inserts 22 are not mounted. The cone cutters 8 are
rotatably mounted on journals with sliding bearing surfaces. The
axis of rotation 18 of the cone cutter 8 extends inwardly through
the center of the bearing pin shaft 16 toward and offset from the
axis of rotation 20 of the drill bit 2. Although FIG. 1 depicts
drill bit 2 as a roller cone bit, it will be understood by those of
ordinary skill in the art that the helical chisel insert of the
present invention may be used in PDC bits and other types of drill
bits.
[0022] FIGS. 2 and 3 show front and top views, respectively, of an
embodiment of the helical chisel insert 22a of the present
invention. FIG. 4 shows the front view of another embodiment of
helical chisel insert 22b of the present invention. As shown in
FIGS. 2-4, helical chisel insert 22 has a cylindrical base 24 which
may be inserted in hole 9 with its longitudinal axis 26 being
normal to the surface 21 of cutter 8 (hole 9 and surface 21 shown
in FIG. 1). A top portion 50, which is connected to cylindrical
base 24, includes a cutting tip 28 and an elongated crest 36 having
a length 52 along its broad side and a width 53. Top portion 50 has
two faces or flanks, leading flank 30 and trailing flank 32. Flanks
30 and 32 commence at the joinder of the top portion 50 and
cylindrical base 24, shown as corners 42 and 44, respectively, and
curve upwards in a substantially helical manner about longitudinal
axis 26, to join crest 36 at corners 38 and 40, respectively.
Flanks 30 and 32 define substantially concave surfaces 46 and 48.
As is apparent from FIGS. 2-4, flanks 30 and 32 define a contoured
surface that is continuously twisted from the top of base 24 to the
crest 36 such that iterative cross sections of top portion 50 will
describe a helix at their outermost points.
[0023] The contoured surface of helical chisel insert 22 provides a
more aggressive cutting surface than convention chisel inserts and
may provide a greater rate of penetration than conventional chisel
inserts. The shape of helical chisel insert 22 may allow insert 22
to plow through the formation, as opposed to merely striking the
formation. As a result, helical chisel insert 22 may remove more
rock for a given position in the drill bit than a conventional
insert. For example, helical chisel inserts 22 may provide a more
aggressive insert in soft formation drilling by orientating the
elongated crest 36 of the cutting tip 28 preferentially with the
cutting or plowing action of the drilled formation relative to the
chisel rolling direction. The result may be faster rates of
penetration for the drill bit 2 as a whole. Helical chisel inserts
22 may add improved plowing action to the insert over conventional
inserts as helical chisel insert 22 describes its arc into, through
and out of the formation being drilled.
[0024] Helical chisel insert 22 has a degree of twist .theta.,
measured from the longest axis of the bottom cross section to the
longest axis of the elongated crest 36. The degree of twist .theta.
may be selected based on the desired characteristics including, for
example, penetration rate and resistance to breakage. The
embodiment of helical chisel insert 22a shown in FIGS. 2 and 3 has
a degree of twist .theta. of about 90.degree., for example. The
embodiment of helical chisel insert 22b shown in FIG. 4, has a
degree of twist .theta. of about 15.degree., for example. Flanks 30
and 32 may curve either substantially clockwise or substantially
counterclockwise. Flanks 30 and 32 may have a twist from about
90.degree. clockwise to about 90.degree. counterclockwise, thus
describing the entire 360.degree. radius. Flanks 30 and 32 may be
selectively shaped to provide different crest 36 geometries that
describe the degree of twist in variations of an "s" shape, but
within the same insert diameter. Helical chisel insert 22 may
incorporate timing mark 54 to assist a user with positioning
helical chisel inserts 22 on drill bit 2 in a precise manner.
[0025] Although FIGS. 2-4 depict helical chisel bit 22 with two
flanks, it will be understood by those of ordinary skill in the art
that other embodiments of the helical chisel insert of the present
invention may include only one flank, or may include more than two
flanks. Similarly, while FIGS. 2-4 depict helical chisel bit 22
with an substantially elongated crest, it will be understood by
those of ordinary skill in the art that other embodiments of the
helical chisel insert of the present invention may include
different crest formations depending on the number of flanks and
the selected contour geometry, among other factors.
[0026] Helical chisel inserts 22 may be positioned on rolling cone
cutter 8 in a vectored manner such that the elongated crests 36 are
selectively oriented with respect to the direction of plowing
action. By vectoring helical chisel inserts 22 in this manner, a
drill bit 2 may be selectively configured to provide a greater rate
of penetration, improved resistance to breakage, or a combination
thereof. Embodiments of this vectored positioning are shown in
FIGS. 5 and 6.
[0027] FIG. 5 is a schematic view of a borehole bottom showing the
impression left by helical chisel inserts 22 on the two outer rows
of a cone cutter, selected and positioned thereon to reduce insert
breakage. The direction of bit rotation is indicated by arrow 56.
By orienting (vectoring) the elongated crests 36 of the inserts 22
in line with the insert movement a helical chisel insert 22
presents a very small face to the formation. The insert 22 can
withstand higher forces (or harder formations) in this situation.
The helical chisel inserts 22 on the outermost heel row have a
selected angle of twist .theta. such that crests 36 are oriented at
an angle from about 30.degree. to about 60.degree. from the axis of
rotation of the cone toward the leading side of the cone. The
helical chisel inserts 22 on the second row have a selected angle
of twist .theta. such that crests 36 are oriented at an angle from
30.degree. to 60.degree. from the axis of the cone toward the
trailing side of the cone. Stated another way, the elongated crests
on the heel row are oriented at an azimuth direction ranging from
300.degree. to 330.degree. from the axis of rotation of the cone
with the axis being equal to 360.degree.. The elongated crests on
the second row are oriented at an azimuth direction of 30.degree.
to 60.degree. from the axis of the cone.
[0028] With such an orientation, the insert 22 moves in formation
in a direction in line with the elongated crest 36 so that a
relatively small area, about width 53 of the insert 22, contacts
the formation and relatively small chips are formed. The relatively
thick section of tungsten carbide, for example, along the length 54
of the crest 36 provides a very high resistance to insert
breakages. This type of insert orientation provides a cone cutter
with much higher resistance to breakage than a similar cutter with
conventional insert orientation.
[0029] The direction of bit rotation is indicated by arrow 56. The
initial engagement of the elongated crests of the heel row inserts
is indicated by 58. The disengagement of the elongated crests of
the heel row inserts is indicated by 66 with the direction of the
plowing of formation represented by arrow 62. The elongated crests
of the second row inserts engage 60 and disengage 68 the formation
in the direction indicated by arrow 64.
[0030] Alternatively, the angle of twist .theta. may be selected to
orient or vector the crest 36 so that the broad side 52 of the
insert crest 36 faces the direction of the plowing action. In this
case, each insert 22 removes more formation, resulting in a faster
penetration rate. This configuration is illustrated in FIG. 6,
which is a schematic view of a borehole bottom showing insert
tracks left by inserts 22 on the two outer rows of a cone cutter,
where the inserts are oriented for increasing penetration rate. As
shown in FIG. 6, the elongated crests 36 of the helical chisel
inserts 22 are relatively perpendicular to the direction of the
plowing action, indicated by arrow 88. The elongated crests 36 of
the inserts 22 positioned on heel row 10 are oriented at an angle
of 30.degree. to 60.degree. toward the trailing side of the cone.
The elongated crests 36 of the inserts 22 on second row 12 are
oriented at an angle of 30.degree. to 60.degree. toward the leading
side of the cone. Stated another way, the elongated crests of the
heel row inserts are oriented at an azimuth direction ranging from
about 30.degree. to 60.degree. from the axis of rotation of the
cone. The elongated crests of the second row inserts are oriented
at an azimuth direction of 300.degree. to 330.degree. from the axis
of rotation of the cone with the axis being equal to 360.degree..
This orientation may break formation along a wider path, making
more chips and larger chips than orientation of standard TCI bits,
resulting in an increase penetration rate.
[0031] The direction of bit rotation is indicated by arrow 82. The
initial engagement of the elongated crests of the heel row inserts
is indicated by 84. The disengagement of the elongated crests of
the heel row inserts is indicated by 86 with the direction of the
plowing of formation represented by arrow 88. The elongated crests
of the second row inserts engage 90 and disengage 92 the formation
in the direction indicated by arrow 94.
[0032] The embodiments shown in FIGS. 5 and 6 show an angle of
twist .theta. of about .+-.30.degree.. Other embodiments of the
helical chisel inserts of the present invention, however, may have
a twist from about 90.degree. clockwise to about 90.degree.
counterclockwise, thus describing a greater range. As a result, the
helical chisel inserts allow for an increased degree of freedom in
configuring the drill bit to improve resistance to insert breakage,
rate of penetration, or a balance of both.
[0033] The helical chisel inserts of the present invention may
provide a more aggressive cutting surface than convention chisel
inserts and may provide a greater rate of penetration than
conventional chisel inserts. The helical chisel inserts may add
improved plowing action to the insert over conventional inserts as
the helical chisel insert describes its arc into, through and out
of the formation being drilled. If the insert life is given
priority over the rate of penetration, the helical chisel insert
may be described in reverse rotation. The helical chisel inserts
also provide an insert designer with another degree of freedom to
optimize chisel contour geometries to accommodate the particular
stresses and wear patterns observed downhole.
[0034] From the foregoing detailed description of specific
embodiments of the invention, it should be apparent that a helical
chisel insert for rock bits that is novel has been disclosed.
Although specific embodiments of the invention have been disclosed
herein in some detail, this has been done solely for the purposes
of describing various features and aspects of the invention, and is
not intended to be limiting with respect to the scope of the
invention. It is contemplated that various substitutions,
alterations, and/or modifications, including but not limited to
those implementation variations which may have been suggested
herein, may be made to the disclosed embodiments without departing
from the spirit and scope of the invention as defined by the
appended claims which follow.
* * * * *