U.S. patent application number 14/331761 was filed with the patent office on 2016-01-21 for reduced length and low cobalt content cutters and drill bit made therewith.
The applicant listed for this patent is Shear Bits, Ltd.. Invention is credited to Timothy P. Beaton.
Application Number | 20160017665 14/331761 |
Document ID | / |
Family ID | 55074152 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160017665 |
Kind Code |
A1 |
Beaton; Timothy P. |
January 21, 2016 |
REDUCED LENGTH AND LOW COBALT CONTENT CUTTERS AND DRILL BIT MADE
THEREWITH
Abstract
A cutter for a fixed cutter drill bit includes a substrate and a
cutting material surface affixed to one end of the substrate. The
substrate comprises tungsten carbide having at least six percent by
weight and at most ten percent by weight of cobalt. An overall
length of the cutter is at most 10 millimeters. In one embodiment
an overall length of the cutter is at most 8 millimeters.
Inventors: |
Beaton; Timothy P.;
(Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shear Bits, Ltd. |
Calgary |
|
CA |
|
|
Family ID: |
55074152 |
Appl. No.: |
14/331761 |
Filed: |
July 15, 2014 |
Current U.S.
Class: |
175/432 |
Current CPC
Class: |
B22F 2005/001 20130101;
E21B 10/573 20130101; E21B 10/43 20130101; B22F 7/06 20130101; C22C
29/08 20130101; C22C 26/00 20130101 |
International
Class: |
E21B 10/55 20060101
E21B010/55; E21B 10/573 20060101 E21B010/573 |
Claims
1. A cutter for a fixed cutter drill bit comprising: a substrate;
and a cutting material surface affixed to one end of the substrate,
wherein the substrate comprises tungsten carbide having at least
six percent by weight and at most ten percent by weight of cobalt,
and wherein an overall length of the cutter is at most 10
millimeters.
2. The cutter of claim 1 wherein the cutting material surface
comprises at least one of polycrystalline diamond and cubic boron
nitride.
3. The cutter of claim 1 wherein a length of the substrate is about
eight millimeters.
4. The cutter of claim 1 wherein an overall length of the cutter is
at most 8 millimeters.
5. The cutter of claim 4 wherein a length of the substrate is about
6 millimeters.
6. The cutter of claim 1 wherein the cutter is a primary cutter
disposed on a drill bit body radially outside a cone of the bit and
radially inside a gage of the bit.
7. A fixed cutter drill bit comprising: a bit body; and a plurality
of cutters affixed to the bit body, each of the cutters comprising
a substrate and a cutting material surface affixed to one end of
the substrate, wherein the substrate comprises tungsten carbide
having at least six percent by weight and at most ten percent by
weight of cobalt, and wherein an overall length of each cutter is
at most 10 millimeters.
8. The bit of claim 7 wherein the bit body comprises a plurality of
blades.
9. The bit of claim 7 wherein the cutting material surface of each
cutter comprises at least one of polycrystalline diamond and cubic
boron nitride.
10. The bit of claim 7 wherein an overall length of each of the
plurality of cutters is at most 10 millimeters.
11. The bit of claim 10 wherein a length of the substrate of each
of the plurality of cutters is about eight millimeters.
12. The bit of claim 7 wherein an overall length of each of the
plurality of cutters is at most 8 millimeters.
13. The bit of claim 11 wherein a length of the substrate of each
cutter is about 6 millimeters.
14. The bit of claim 7 wherein each of the plurality of cutters is
a primary cutter disposed on a drill bit body radially outside a
cone of the bit and radially inside a gage of the bit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND
[0003] This disclosure is related to the field of fixed cutter
drill bits used to drill wellbores through subsurface rock
formations. More specifically, the disclosure relates to structures
and compositions of cutters used on such drill bits.
[0004] Fixed cutter drill bits known in the art include a plurality
of cutters affixed to a bit body. The bit body has features to
enable coupling to a drill string or other drilling tool that
rotates the bit and applies axial force so that the bit drills
through rock formations to create a wellbore.
[0005] The cutters are typically formed from a substrate in the
form of a right cylinder. A diamond "table" made of polycrystalline
diamond, or a layer of other "super hard" material, e.g., cubic
boron nitride, is affixed to one end of the substrate to for the
cutting surface of the cutter.
[0006] Cutters of the foregoing type known in the art have about 12
to 15 percent cobalt content in the substrate. An overall length of
the cutter is typically about 13 millimeters, including both the
substrate and the diamond table or super hard material layer.
Shorter cutters are known in the art, however, they generally are
only used either in the very center of the bit, called the "cone"
(where torsional loading and work rates are a lot lower) or in
either backup positions or gage positions. What are known as
"primary" cutter positions are positions where the cutters are
subjected to the most loading (the positions where the cutters are
at the front of the blade and are between the center of the bit and
the gage of the bit). Primary cutters may be considered any cutter
located radially inwardly of the gage and outwardly of the cone. It
is not known in the art to use short cutters (i.e., cutters shorter
than about 13 mm overall length) in the above-defined primary
cutter locations as it is generally believed that there will not be
enough surface area for brazing and that will lead to cutters
falling out while drilling.
[0007] The cobalt content of cutter substrates known in the art is
believed to be necessary to provide the cutters with sufficient
resistance to brittle fracture during drilling. The overall length
is believed to be necessary to provide sufficient surface area to
attach the cutter, typically by brazing the substrate to the bit
body, so that the cutters will be attached to the bit body strongly
enough to avoid being removed from the bit body during
drilling.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows an example of a fixed cutter drill bit
according to the present disclosure.
[0009] FIGS. 2 and 3 show different views of a cutter according to
the present disclosure.
DETAILED DESCRIPTION
[0010] An example fixed cutter drill bit is shown at 10 in FIG. 1.
The bit 10 may include a bit body 12 of any configuration known in
the art for fixed cutter bits. The bit body 12 may include one or
more blades 13, but such configuration of the bit body 10 is not
intended to limit the scope of the present disclosure. The bit body
10 may have attached thereto one or more cutters 14. The cutter(s)
will be further explained with reference to FIGS. 2 and 3. As
explained in the Background section herein, the so-called "primary"
cutters 14 are disposed in an area of the bit face wherein the
cutters 14 are subjected to the most loading (the positions where
the cutters are at the front of the blade and are between the
center or cone of the bit and the gage of the bit). Such cutters
may be referred to as "primary cutters." Other cutters 14A may be
disposed proximate an outer edge of the bit body 12, and may be
referred to as "gage cutters." Still other cutter 14B may be
disposed on the "cone" section of the bit proximate the axial
center of the bit 10. Both the gage cutters 14A and center cutters
14B are subject to much lower loading than the primary cutters 14,
and may have different material composition and dimensional
requirements than the primary cutters 14. FIG. 2 shows a side view
of an example cutter 14 according to the present disclosure. The
cutter 14 may include a substantially cylindrical substrate 16 with
a cutting material surface 18 affixed to one end of the substrate
16. The substrate 16 and cutting material surface 18 may be
substantially cylindrical, but the particular shape of the cutter
14 is not intended to limit the scope of the present disclosure.
The cutting material surface 18 may be made from polycrystalline
diamond, cubic boron nitride or other "super hard" material known
in the art for cutters on fixed cutter drill bits.
[0011] In the present example, the substrate 16 may be made from
tungsten carbide and have a cobalt content of at most ten percent
by weight. In the present example, the substrate 16 may have a
cobalt content of at least six percent by weight.
[0012] An overall length of the cutter 14 may be about 10
millimeters, including both the substrate 16 and the cutting
material surface 18. The thickness of the cutting material surface
may be about 2 millimeters in the present example. The substrate is
thus about six millimeters in length. In other examples, the
overall length of the cutter may be about 8 millimeters, wherein
the substrate is about 6 millimeters in length.
[0013] An oblique view of the cutter 14 is shown in FIG. 3, wherein
the substantially cylindrical shape of the present example cutter
14 is clearly visible.
[0014] It has been found through testing that having a cobalt
content in the substrate between six and ten percent by weight
increases the resistance of the substrate 16 to wear during
drilling, but has not resulted in increased incidence of brittle
failure. Correspondingly, the overall length of the cutter 14 of
about 8 millimeters has been found to provide sufficient bonding
surface area to affix the cutter to the bit body (12 in FIG. 1)
without cutters becoming removed from the bit body during
drilling.
[0015] A fixed cutter drill bit made according to the various
aspects of the present disclosure may have reduced costs of
manufacture, and may have longer usable life span than fixed cutter
bits known in the art prior to the bit and cutters of the present
disclosure.
[0016] While the invention has been described with respect to a
limited number of embodiments, those skilled in the art, having
benefit of this disclosure, will appreciate that other embodiments
can be devised which do not depart from the scope of the invention
as disclosed herein. Accordingly, the scope of the invention should
be limited only by the attached claims.
* * * * *