Note: Descriptions are shown in the official language in which they were submitted.
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MATRIX DRILL BIT WITH DUAL SURFACE COMPOSITIONS AND METHODS OF
MANUFACTURE
RELATED APPLICATION
This application claims the benefit of United States
provisional application Serial No. 61/148,665 entitled "Matrix
Drill Bit With Dual Surface Compositions And Methods of
Manufacture" filed January 30, 2009.
TECHNICAL FIELD
The present disclosure relates in general to matrix drill
bits and other well tools with matrix bodies having one or
more layers of hard material disposed at selected locations on
exterior portions thereof and, more particularly, to forming
one or more layers of hard material at selected locations
during manufacture of a matrix body or applying one or more
layers of hard material at selected locations on exterior
portions of a used matrix body.
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BACKGROUND OF THE DISCLOSURE
Rotary drill bits are frequently used to drill oil and
gas wells, geothermal wells and water wells. Rotary drill bits
may be generally classified as rotary cone or roller cone
drill bits and fixed cutter drill bits or drag bits. Fixed
cutter drill bits or drag bits may be formed with a matrix bit
body having cutting elements or inserts disposed at select
locations of exterior portions of the matrix bit body. Fluid
flow passageways are typically formed in the matrix bit body
to allow communication of drilling fluids from associated
surface drilling equipment through a drill string or drill
pipe attached to the matrix bit body. Such fixed cutter drill
bits or drag bits may sometimes be referred to as "matrix
drill bits."
Matrix drill bits are typically formed by placing loose
matrix material (sometimes referred to as "matrix powder")
into a mold and infiltrating the matrix material with a hot,
liquid binder such as a copper alloy. The mold may be formed
by various techniques including, but not limited to, milling a
block of material such as graphite to define a mold cavity
with features that correspond generally with desired features
of the resulting matrix drill bit. Various features of the
resulting matrix drill bit such as blades, cutter pockets,
and/or fluid flow passageways may be provided by shaping the
mold cavity, positioning one or more mold inserts within the
mold cavity and/or by positioning temporary displacement
materials within the mold cavity. Since machining hard,
abrasion, erosion and/or wear resistant materials is generally
both difficult and expensive, it is common practice to form
some metal parts with a desired configuration and subsequently
treat one or more portions of the metal part to provide
desired abrasion, erosion and/or wear resistance. Examples may
include directly hardening such surfaces (carburizing and/or
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nitriding) one or more surfaces of a metal part or applying a
layer of hard, abrasion, erosion and/or wear resistant
material (hardfacing) to one or more surfaces of a metal part
depending upon desired amounts of abrasion, erosion and/or
wear resistance for such surfaces. For applications when
resistance to extreme abrasion, erosion and/or wear of a
working surface and/or associated substrate is desired, a
layer of hard, abrasion, erosion and/or wear resistant
material (hardfacing) may be applied to the working surface to
protect the associated substrate. Applying hard facing to
matrix materials such as a matrix bit body is often more
difficult and technically challenging as compared with
applying the same hardfacing to a generally uniform, non-
matrix metal surface.
Hardfacing may be generally defined as a layer of hard,
abrasion resistant material applied to a less resistant
surface or substrate by plating, welding, spraying or other
well known deposition techniques. Hardfacing is frequently
used to extend the service life of drill bits and other
downhole tools used in the oil and gas industry. Tungsten
carbide and various alloys of tungsten carbide are examples of
hardfacing materials widely used to protect drill bits and
other downhole tools associated with drilling and producing
oil and gas wells.
A wide variety of hard materials have been applied to
exterior portions of rotary drill bits and other downhole
tools. Frequently used hard materials include, but are not
limited to, sintered tungsten carbide particles in a steel
alloy matrix deposit. Tungsten carbide particles may include
grains of monotungsten carbide, ditungsten carbide and/or
macrocrystalline tungsten carbide. Spherical cast tungsten
carbide may typically be formed with no binding material.
Examples of binding materials used to form tungsten carbide
particles may include, but are not limited to, cobalt, nickel,
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boron, molybdenum, niobium, chromium, iron and alloys of these
elements.
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SUMMARY
The present disclosure provides matrix bit bodies for
rotary drill bits or matrix bodies for other downhole tools
5 with one or more layers of hard material disposed at selected
locations to provide substantially enhanced resistance to
erosion, abrasion, wear, impact and/or fatigue forces as
compared with prior matrix bodies without such layers of hard
material. In accordance with teachings of the present
disclosure, such layers of hard material may include tungsten
carbide particles, formed with an optimum amount of binding
material, particles of other superabrasive and/or superhard
materials. Examples of such hard materials satisfactory for
use with the present disclosure may include, but are not
limited to, encrusted diamond particles, coated diamond
particles, silicon nitride (Si3N4), silicon carbide (SiC),
boron carbide (34C) and cubic boron nitride (CBN). Such hard
materials may also be used to rebuild exterior portions of
used drill bits (sometimes referred to as "dull bits") in
accordance with teachings of the present disclosure.
One or more layers of hard material may be disposed at
selected locations on exterior portions of a matrix bit body
associated with a matrix drill bit or at selected locations on
other downhole tools in accordance with teachings of the
present disclosure during molding of an associated matrix body
and/or after molding of the associated matrix body. The
resulting matrix body may be described as having a dual phase
exterior or dual surface composition.
One aspect of the present disclosure may include placing
one or more layers of one or more hard materials at selected
locations in a mold corresponding generally with respective
selected locations on exterior portion of blades, cutter
pockets, junk slots and/or other components of an associated
matrix bit body. A preformed hollow bit blank or casting
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mandrel may be disposed in the mold. One or more matrix
materials may be added to the mold. The matrix materials may
be selected to form a hard, matrix bit body. A binder material
may also be added to the mold. During heating of the mold,
liquid binder material may flow through the matrix materials
and the one or more layers of the hard material. The layer or
layers of hard material may provide desired enhancement to
resist erosion, abrasion, wear, impact and/or fatigue forces
at respective selected locations on exterior portions of the
matrix bit body.
For some applications, a composite layer of hard material
may be disposed at selected locations on exterior portions of
a matrix bit body in accordance with teachings of the present
disclosure. Each composite layer of hard material may include
two, three or more smaller (thinner) layers or sublayers of
hard material. Each sublayer of hard material may include a
plurality of large hard particles including, but not limited
to, low alloy sintered materials in the form of pellets and/or
low alloy sintered material in the form of crushed powder.
Other forms of low alloy sintered material may also be used to
enhance downhole drilling performance and/or associated matrix
drill bit life.
For some applications, a low percentage of binder
material (4% plus or minus l% Co, Ni, B, Mo, Cr or Se binder
or any combination thereof) may be used to bind fine tungsten
carbide grains to form generally spherical tungsten carbide
particles or pellets. The use of such particles or pellets may
provide substantially increased carbide content at one or more
selected locations on exterior portions of an associated
matrix body as compared to hard materials with twenty to
thirty percent (20% to 30%) binder. For some applications, the
size of the resulting tungsten carbide particles or pellets
may be substantially enlarged such that only one layer of the
second hard material is required to provide satisfactory
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resistance to erosion, abrasion, impact and/or fatigue forces
at a selected location. Used matrix drill bits may be repaired
by forming one or more layers of hard material at selected
locations on exterior portions of an associated matrix bit
body.
For some applications, one or more layers of the low
alloy sintered material may also include matrix materials used
to form an associated matrix bit body. Various binding
processes including, but not limited to, sintering and/or
sinter-hipping may be used to form spherical tungsten carbide
particles or pellets in a sintering furnace. For some
applications a sintered tungsten carbide pellet may be used in
combination with conventional matrix materials to form a
matrix drill bit. Such materials may be used to rebuild a
matrix bit body in accordance with teachings of the present
disclosure.
Various techniques may be satisfactorily used to
determine the location or locations for forming one or more
layers of hard material on exterior portions of an associated
matrix body. For example, simulation of fluid flow over
exterior portions of a matrix drill bit or other downhole
tools having a matrix body in combination with analysis of
wear patterns on exterior portions of an associated matrix
drill bit and/or other downhole tools may help to identify one
or more locations for forming such layers of hard material.
Three dimensional (3D) scanning of used drill bits, visual
inspection or other techniques may also be used to select
locations for forming one or more layers of hard material with
enhanced erosion, war, abrasion, impact and/or fatigue
resistance on exterior portions of a matrix bit body during
manufacture of an associated matrix drill bit.
Matrix materials including, but are not limited to,
cemented carbides of tungsten, macrocrystalline tungsten
carbide, tungsten cast carbide, titanium, tantalum, niobium,
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chromium, vanadium, molybdenum, hafnium independently or in
combination and/or spherical carbides may be used to form one
or more layers of hard material at selected locations matrix
bodies in accordance with teachings of the present disclosure.
However, the present disclosure is not limited to cemented
tungsten carbides, spherical carbides, macrocrystalline
tungsten carbide and/or cast tungsten carbides or mixtures
thereof.
Some embodiments one or more layers of hard material may
be disposed on exterior portions of a matrix body with at
least one layer having both large particles or pellets and
small particles or pellets. The ratio of larger pellets to
small pellets may vary from approximately one to one or fifty
percent large pellets and fifty percent small pellets to
approximately three (3) large pellets for every small pellet
(3 to 1) or seventy five percent (75%) large pellets and
twenty five percent (25%) small pellets. The size of a typical
small pellet of hard material may be approximately 20 mesh
(850p) to 30 mesh (600p). The size of a typical large pellet
of hard material may be approximately 16 mesh (1180p) to 20
mesh (850p).
Additional features, steps, technical advantages and/or
benefits of the present disclosure may be discussed in the
Detailed Description and/or Claims. The above Summary is not
intended to be a comprehensive listing of all features, steps,
technical advantages and/or benefits of the present
disclosure.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present
disclosure and its advantages thereof, reference is now made
to the following brief descriptions, taken in conjunction with
the accompanying drawings and detailed description, wherein
like reference numerals represent like parts, in which:
FIGURE 1 is a schematic drawing showing an isometric view
of one example of a matrix drill bit having a matrix bit body
with one or more layers of hard material disposed at selected
locations on exterior portions of the matrix bit body;
FIGURE 2A is a schematic drawing in section with portions
broken away showing a mold assembly satisfactory to form a
matrix body in accordance with teachings of the present
disclosure;
FIGURE 2B is a schematic drawing showing multiple layers
of hard material or a composite layer of hard material which
may be disposed at one or more locations on interior portions
of the mold shown in FIGURE 2A;
FIGURE 2C is a schematic drawing in section with portions
broken away showing a single layer of hard material which may
be disposed at one or more locations on interior portions of
the mold shown in FIGURE 2A;
FIGURE 3A is a schematic drawing in elevation with
portions broken away showing a welding rod with hard materials
disposed therein in accordance with teachings of the present
disclosure;
FIGURE 35 is an enlarged schematic drawing in section
with portions broken away showing tungsten carbide pellets and
other hard materials disposed within the welding rod of FIGURE
3A;
FIGURE 3C is an enlarged schematic drawing in section
with portions broken away showing tungsten carbide pellets
formed with an optimum weight percentage of binding material
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and bonded to a matrix deposit disposed on and bonded to a
substrate or matrix body in accordance with teachings of the
present disclosure;
FIGURE 4A is a schematic drawing in elevation with
5 portions broken away showing a welding rod with hard materials
disposed therein in accordance with teachings of the present
disclosure;
FIGURE 43 is an enlarged schematic drawing in elevation
and in section with portions broken away showing tungsten
10 carbide pellets, encrusted diamond particles and other hard
materials disposed within the welding rod of FIGURE 4A;
FIGURE 4C is an enlarged schematic drawing in section
with portions broken away showing tungsten carbide pellets
formed with an optimum weight percentage of binding material
along with encrusted diamond particles and bonded to a matrix
deposit disposed on and bonded to a substrate or matrix body
in accordance with teachings of the present disclosure;
FIGURE 5 is a schematic drawing in section with portions
broken away showing a mold assembly with mold inserts, matrix
materials and other materials disposed therein satisfactory to
form a matrix bit body in accordance with teachings of the
present disclosure; and
FIGURE 6 is a schematic drawing in section with portions
broken away showing a matrix bit body with recesses formed in
exterior portions thereof in accordance with teachings of the
present disclosure.
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DETAILED DESCRIPTION OF THE DISCLOSURE
Preferred embodiments and various advantages may be
understood by referring in more detail to FIGURES 1-6 of the
drawings, in which like numerals refer to like parts. The
terms "matrix bit", "matrix drill bit" and "matrix rotary
drill bit" may be used in this application to refer to "rotary
drag bits", "drag bits", "fixed cutter drill bits" or any
other drill bit incorporating teaching of the present
disclosure. Such drill bits may be used to form well bores or
boreholes in subterranean formations.
Matrix drill bits incorporating teachings of the present
disclosure may include a matrix bit body formed by one or more
matrix materials. For other embodiments (not expressly shown)
a matrix bit body may be formed with at least a first matrix
material and a second matrix material. For some applications
the first matrix material may have increased toughness or high
resistance to fracture and also provide erosion, abrasion and
wear resistance. The second matrix material (not expressly
shown) with only a limited amount of alloy materials or other
contaminates may also be used to form the matrix bit body. The
first matrix material may include, but is not limited to,
cemented carbides or spherical carbides. The second matrix
material may include, but is not limited to, macrocrystalline
tungsten carbides and/or cast carbides. One or more layers of
hard material may be disposed at selected locations on matrix
bodies formed from matrix materials in accordance with
teachings of the present disclosure.
Various types of binder materials may be used to
infiltrate matrix materials disposed in a mold to form a
matrix bit body. Binder materials may include, but are not
limited to, copper (Cu), nickel (Ni), cobalt (Co), iron (Fe),
molybdenum (Mo) individually or alloys based on these metals.
The alloying elements may include, but are not limited to, one
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or more of the following elements - manganese (Mn), nickel
(Ni), tin (Sn), zinc (Zn), silicon (Si), molybdenum (M0),
tungsten (W), boron (B) and phosphorous (P). The matrix bit
body may be attached to a hollow bit blank or casting mandrel.
A generally hollow shank or hollow tool joint with a threaded
connection may be attached to the hollow bit blank or casting
mandrel for use in releasably engaging the associated matrix
drill bit with a drill string, drill pipe, bottom hole
assembly or downhole drilling motor (not expressly shown).
The terms "cemented carbide" and "cemented carbides" may
be used within this application to include WC, MoC, TiC, TaC,
NbC, Cr302, VC and solid solutions of mixed carbides such as
WC-TiC, WC-TiC-TaC, WC-TiC-(Ta,Nb)C in a metallic binder
(matrix) phase. Typically, Co, Ni, Fe, Mo and/or their alloys
may be used to form the metallic binder. Cemented carbides may
sometimes be referred to as "composite" carbides or sintered
carbides. Some cemented carbides may also be referred to as
spherical carbides. However, cemented carbides may have many
configurations and shapes other than spherical.
Cemented carbides may be generally described as powdered
refractory carbides which have been united by compression and
heat with binder materials such as powdered cobalt, iron,
nickel, molybdenum and/or their alloys. Cemented carbides may
also be sintered, crushed, screened and/or further processed
as appropriate. Cemented carbide pellets may be used to form a
matrix bit body. The binder material may provide ductility and
toughness which often results in greater resistance to
fracture (toughness) of cemented carbide pellets, spheres or
other configurations as compared to cast carbides,
macrocrystalline tungsten carbide and/or formulates thereof.
Binder materials used to form cemented carbides may
sometimes be referred to as "bonding materials" in this
Application to help distinguish between binder materials used
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to form cemented carbides and binder materials used to form a
matrix drill bit.
The terms "computational fluid dynamics" and/or "CFD" may
be used in this application to include various commercially
available computer programs and algorithms used to simulate
and evaluate complex fluid interactions. Such simulations may
include calculating mass transfer, turbulence, velocity
changes and other characteristics associated with multiphase,
complex fluid flow associated with a matrix drill bit forming
a wellbore. Such fluids may often be a mixture of liquids,
solids and/or gases with varying concentrations depending on
associated downhole drilling conditions. Simulations using CFD
programs may be used to determine optimum locations for
forming one or more layers of hard material on exterior
portions of a matrix body based on anticipated fluid flow for
the type/size of pump used on an associated drilling rig (not
expressly shown), size of associated drill string (not
expressly shown), size and configuration of an associated
matrix drill bit or other downhole tool and/or anticipated
downhole drilling conditions.
The term "digital scanning" may be used to describe a
wide variety of equipment and techniques satisfactory for
measuring exterior dimensions of a matrix drill bit and other
downhole tools with a very high degree of accuracy and to
create a three dimensional image of exterior portions of such
well tools. The results of digital scanning may be used with
other computer programs such as "computational fluid dynamics"
selected to correspond with desired dimensions and
configuration for resulting gage pads (notbits and other
downhole tools.
Some examples of digital scanning equipment and
techniques are discussed in copending U.S. Patent Application
Serial Number: 60/992,392; Filing Date: December 5, 2007,
entitled "Method and Apparatus to Improve Design, Manufacture,
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Performance and/or Use of 10 Well Tools" now U.S. Patent No.
8,374,835. CFD programs are available from various vendors.
One example of a CFD program satisfactory for use with the
present invention is FLUENT, available from ANSYS, Inc.
located in Canonsburg, PA.
Various computer programs and computer models may be used
to design blades, cutting elements, fluid flow paths and/or
associated rotary drill bits. Examples of such methods and
systems which may be used to design and evaluate performance
of cutting elements and rotary drill bits are shown in
copending U.S. Patent Applications entitled "Methods and
Systems for Designing and/or Selecting Drilling Equipment
Using Predictions of Rotary Drill Bit Walk," Application
Serial No. 11/462,898, filing date August 7, 2006, (now U.S.
Patent No. 7,778,777); copending U.S. Patent Application
entitled "Methods and Systems of Rotary Drill Bit Steerability
Prediction, Rotary Drill Bit Design and Operation,"
Application Serial No. 11/462,918, filed August 7, 2006, (now
U.S. Patent No. 7,729,895) and copending U.S. Patent
Application entitled "Methods and Systems for Design and/or
Selection of Drilling Equipment Based on Wellbore
Simulations," Application Serial No. 11/462,929, filing date
August 7, 2006, (now U.S. Patent No. 7,827,014).
The terms "dual surface compositions", "dual exterior
composition", dual phase surface" and/or "dual phase exterior"
may be used to describe a matrix body having one or more
layers of hard material disposed at selected locations on
exterior portions of the matrix body. The matrix body may be
formed from one or more matrix materials. Hard materials
forming the layer or layers at the selected locations on
exterior portions of the matrix body may generally have a
hardness greater than the hardness of matrix materials used to
form the associated matrix body.
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The term "gage pad" as used in this application may
include a gage, gage segment or gage portion disposed on
exterior portion of a blade. Gage pads may often contact
adjacent portions of a wellbore formed by an associated rotary
5 drill bit. Exterior portions of blades and/or associated gage
pads may be disposed at various angles, either positive or
negative and/or parallel, relative to adjacent portions of a
straight wellbore. A gage pad may include one or more layers
of material formed in accordance with teachings of the present
10 disclosure. One or more gage pads may be disposed on a blade.
The terms "matrix deposit" and/or "metallic matrix
deposit" may refer to a layer or layers of hard material
disposed at selected exterior portions of a matrix body and/or
substrate to protect the matrix body and/or the substrate at
15 the selected locations from abrasion, erosion, wear, impact
and/or fatigue forces. A matrix deposit may also sometimes be
referred to as "metallic alloy material" or as a "deposit
matrix." Various binders and/or binding materials such as
cobalt, nickel, copper, iron and alloys thereof may be used to
form a matrix deposit with hard, abrasion resistant materials
and/or particles dispersed therein and bonded thereto. Nickel
based alloys with increased ductility may be used at locations
subject to erosion and/or abrasion.
Various types of tungsten carbide particles and/or
pellets having an optimum size and/or optimum weight
percentage of binder or binding material may be included as
part of a matrix deposit or layer of hard material
incorporating teachings of the present disclosure. One or more
layers of hard material may be formed on a matrix body from a
wide range of hard metal alloys and other hard materials.
The term "tungsten carbide" may include monotungsten
carbide (WC), ditungsten carbide (W2C), macrocrystalline
tungsten carbide.
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The terms "tungsten carbide pellet," "WC pellet,"
"tungsten carbide pellets" and "WC pellets" may refer to
nuggets, spheres and/or particles of tungsten carbide formed
with an optimum size and/or weight percentage of binding
material in accordance with the teachings of the present
disclosure. The terms "binder", "binding material" and/or
"binder materials" may be used interchangeably in this
Application.
FIGURE 1 is a schematic drawing showing one example of a
fixed cutter drill bit or matrix drill bit having one or more
layers of hard material disposed on exterior portion thereof
in accordance with teachings of the present disclosure. Matrix
drill bit 20 as shown in FIGURE 1 may sometimes be referred to
as a "rotary drill bit," "fixed cutter drill bit" or "drag
bit". Matrix drill bit 20 may include matrix bit body 50
having a plurality of blades 54 extending radially therefrom.
Respective fluid flow paths (sometimes referred to as "junk
slots") 56 may be disposed between adjacent blades 54. Each
blade 54 may include respective leading surface 51 and
trailing surface 52. Arrow 24 indicates the general direction
of rotation of rotary drill bit 20 relative to an associated
bit rotational axis (not expressly shown) during formation of
a wellbore (not expressly shown).
First end or downhole end 21 of matrix drill bit 20 may
include a plurality of cutting elements 60 operable to engage
downhole formation materials and remove such materials to form
a wellbore. Each cutting element 60 may be disposed in
respective pocket 62 formed on exterior portion 58 of
respective blade 54. Each cutting element 60 may include
respective cutting surface 64 formed from hard materials
satisfactory for engaging and removing adjacent downhole
formation materials (not expressly shown).
Cutting elements 60 may scrape and gouge formation
materials from the bottom and sides of a wellbore (not
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expressly shown) during rotation of matrix drill bit 20. For
some applications, various types of polycrystalline diamond
compact (PDC) cutters may be satisfactorily used as cutting
elements 60. A matrix drill bit having PDC cutters may
sometimes be referred to as a "PDC bit".
Second end 22 of matrix drill bit 20 may include shank or
tool joint 30 operable to releasably engage matrix drill bit
20 with a drill string (not expressly shown), bottom hole
assembly (not expressly shown) and/or a downhole drilling
motor (not expressly shown) to rotate matrix drill bit 20
during formation of a wellbore. Shank 30 and associated bit
blank 36 may be described as having respective generally
hollow cylindrical configurations defined in part by a fluid
flow passageway extending therethrough. See, for example fluid
flow passageway 32 in FIGURE 6. Various types of threaded
connections such as American Petroleum Institute (API) drill
pipe connection or threaded pin 34 may be formed on shank 30
proximate second end 22 of matrix drill bit 20. Shank 30 may
also include bit breaker slots 35.
Various techniques may be used to securely engage
generally hollow shank 30 with portions of bit blank 36
extending from matrix bit body 50. See for example FIGURES 1
and 6. For example, weld 39 may be formed in groove 38
disposed between and extending around the perimeter of shank
30 and bit blank 36.
For some applications each blade 54 may include
respective recess 70 formed in exterior portion 58 of each
blade 54. The location and dimensions of each recess 70 may be
selected to correspond generally with a selected location for
forming a gage pad on associated blade 54. FIGURES 5 and 6
show one example of techniques which may be satisfactorily
used to form respective recess 70 at selected locations on
exterior portion 58 of each blade 54. One or more layers of
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hard material may be disposed within each recess 70 in
accordance with teachings of the present disclosure.
FIGURES 3A and 35 and FIGURES 4A and 4B show examples of
welding rods 71 and 71a which may be used to form one or more
layers of hard material in recess 70 in accordance with
teachings of the present disclosure. Welding rods 71 and 71a
may also be used to repair or rebuild a used matrix drill bit
or matrix body in accordance with teachings of the present
disclosure.
One or more nozzle openings 66 may be formed in exterior
portions of matrix bit body 50. Respective nozzle 68 may be
disposed in each nozzle opening 66. Various types of drilling
fluid may be pumped from surface drilling equipment (not
expressly shown) through an associated drill string (not
expressly shown) attached to threaded connection 34 of shank
or tool joint 30 to fluid flow passageway 32 disposed within
matrix bit body. One or more fluid flow paths may be formed in
matrix bit body 50 to communicate drilling fluid and/or other
fluids to associated nozzle 68. See for example fluid
passageways 72 and 74 in FIGURE 6. For some embodiments, one
or more layers 101 of hard material may be disposed on
exterior portions of matrix bit body 50 adjacent to nozzle
opening 66. See for example FIGURE 1.
One or more layers of hard material 102 may be disposed
on exterior portions of one or more blades 54 proximate a
transition or junction between adjacent junk slot 56 and
associated leading surface 51. One or more layers 103 of hard
material may be disposed on trailing surface 52 of one or more
blades 54. In a similar manner, one or more layers 104 of hard
material may be disposed on exterior portion 58 of each blade
54 proximate associated pockets 62 and/or cutting elements 60.
One or more layers 105 of hard material may be disposed
exterior portions of selected pockets 62. Respective
locations, dimensions and configurations for layers 101, 102,
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103, 104 and 105 and associated hard materials on new matrix
drill bits and/or used matrix drill bits may be selected using
CFD analysis, digital scanning, visual scanning and drill bit
design techniques in accordance with teachings of the present
disclosure.
U.S. Patent 6,296,069 entitled Bladed Drill Bit with
Centrally Distributed Diamond Cutters and U.S. Patent
6,302,224 entitled Drag-Bit Drilling with Multiaxial Tooth
Inserts show various examples of blades and/or cutting
elements which may be used with a matrix bit body
incorporating teachings of the present disclosure. It will be
apparent to persons having ordinary skill in the art that a
wide variety of fixed cutter drill bits, drag bits and other
drill bits may be satisfactorily formed with a matrix bit body
incorporating teachings of the present disclosure. The present
disclosure is not limited to matrix drill bit 20 or any
specific features as shown in FIGURES 1-6.
A wide variety of molds may be satisfactorily used to
form a matrix bit body and associated matrix drill bit in
accordance with teachings of the present disclosure. Mold
assembly 200 shown in FIGURE 2A and mold assembly 200a shown
in FIGURE 5 represents only two examples of mold assemblies
satisfactory for use in forming a matrix bit body
incorporating teachings of the present disclosure. U.S. Patent
5,373,907 entitled Method And Apparatus For Manufacturing And
Inspecting The Quality Of A Matrix Body Drill Bit shows
additional details concerning mold assemblies and conventional
matrix bit bodies.
Layers 101, 102, 103, 104 and 105 of various hard
materials may be placed in mold assembly 200 at locations
101a, 102a, 103a, 104a and 105a corresponding generally with
selected locations for forming corresponding layers of hard
material on exterior portions of matrix drill bit 20. One or
more layers 101-105 of hard material may be disposed at each
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location in accordance with teachings of the present
disclosure. For some applications a composite layer or
multiple layers of hard material may be disposed at each
location in mold assembly 200. See for example FIGURE 2B. For
5 other applications a single layer of hard material may be
disposed at each location in mold assembly 200. See for
example FIGURE 2C.
Mold assemblies 200 and 200a as shown in FIGURES 2A, 5
and 6 represent only two examples of molds and/or mold
10 assemblies which may be satisfactorily used to form a matrix
body incorporating teachings of the present disclosure. Mold
assemblies 200 and 200a may be generally described as having
cylindrical configurations in part by respective first, opened
end 201 and second, closed end 202 with respective mold cavity
15 252 and 252a disposed there between. Mold cavities 252 and
252a may be generally described as negative images or inverse
images of a matrix bit body formed by the respective mold
assemblies 200 and 200a.
For some embodiments, interior portions of mold cavities
20 252 and/or 252a may be coated with a mold wash to prevent
gasses, produced by heating and/or cooling of associated mold
assemblies 200 and 200a, from entering into matrix materials
disposed within respective mold cavities 252 and 252a. Various
commercially available mold washes may be satisfactorily used.
Mold assemblies 200 and/or 200a may also be placed within a
container (not expressly shown). Interior portions of such
containers may be designed to receive exterior portions of
mold assemblies 200 and/or 200a. Such containers may sometimes
be referred to as a "housing", "crucible" and/or "bucket".
Mold assembly 200 as shown in FIGURE 2A may include a
plurality of displacements 208 disposed on interior portions
of mold cavity 252. The configuration and dimensions
associated with each displacement 208 may be selected to
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generally correspond with blades 54 and fluid flow paths 56
formed on exterior portions of matrix bit body 50.
Depending on the type of materials used to form mold
assembly 200 and/or heating and cooling cycles associated with
forming matrix bit body 50, out gassing may occur. For such
applications, a plurality of internal flow paths (not
expressly shown) may be formed within mold assembly 200. Such
fluid flow paths may communicate gasses associated with
heating and cooling of mold assembly 200 through fluid flow
channels 206 and/or exterior portions of mold assembly 200.
Mold cavity 252 as shown in FIGURE 2A may be formed with
a plurality of negative blade profiles 210 disposed between
respective displacements 208. For some applications, mold
assembly 200 and associated components may be formed using a
3D printer in combination with 3D design data. A plurality of
negative pocket recesses or pocket profiles 262 may be formed
within each negative blade profile 210. Negative pocket
recesses 262 may have complex configurations and/or
orientations as desired for respective pocket 62 and
associated cutting element 60.
Locations 101a-105a within mold assembly 200 may be
selected to correspond generally with locations on exterior
portions of associated matrix drill bit 20 where high erosion,
abrasion, wear, impact and/or fatigued forces may be applied.
For example, one or more layers of hard material may be
disposed at location 101a to minimize erosion from fluid
flowing from associated nozzle 68. One or more layers of hard
material may be disposed at locations 102a and 103a to
minimize abrasion and/or wear associated with fluid flowing
through associated flow path or junk slot 56. One or more
layers of a second hard material may be disposed at locations
104a to minimize erosion, abrasion, wear, impact and/or
fatigue forces applied to exterior portions 58 of associated
blade 54 during engagement of associated cutting elements 60
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22
with adjacent downhole formation materials. One or more layers
of hard material may be disposed at location 105a on exterior
portions of associated pocket 62 to minimize erosion,
abrasion, wear, impact and/or fatigue forces resulting from
respective cutting element 60 engaging and removing downhole
formation materials.
FIGURES 2B and 2C show examples of layers of hard
materials which may be disposed at one or more locations 101a-
105a in accordance with teachings of the present disclosure.
FIGURE 23 shows first layer or sublayer 111, second layer or
sublayer 112 and third layer or sublayer 113 disposed at
location 101a in mold assembly 200. The resulting
configuration of layers or sublayers 111, 112 and 113 may
sometimes be referred to as "composite layer" 101. Each
sublayer 111, 112 and 113 may have approximately the same
general configuration and dimensions including thickness. Each
layer 111, 112 and 113 may include a plurality of large
pellets 130 and/or 140. Also, a plurality of smaller pellets
and matrix material 131 used to form associated matrix drill
bit 20 may also be disposed within layers 111, 112 and/or 113.
For embodiments such as shown in FIGURE 2B, first layer
111 may start with a layer of glue disposed at location 101a.
Various types of glue and/or adhesive materials including, but
not limited to, aerosol adhesives such as Super 77
Multipurpose Adhesive available from 3M Company located in St.
Paul, Minnesota may be satisfactorily used. Hard particles or
hard pellets 130 as shown in FIGURES 23 and 3C and/or hard
pellets 140 as shown in FIGURES 43 and 4C may then be
disbursed within the glue of first layer 111. Matrix material
131 may also be disbursed within first layer 111. The ratio of
hard pellets or hard particles with respect to matrix material
may be selected to provide desired uniformity of the resulting
first layer 111 and desired hardness.
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A second layer of glue may be disposed on first layer 110
at location 101a. Additional hard pellets 130 and/or 140 may
then be distributed within the glue at second layer 112.
Matrix material 131 may be disbursed within the glue at second
layer 112. Similar procedures may be used to form third layer
113 and additional layers of glue, hard pellets and/or matrix
material as desired for each selected location on exterior
portions of matrix drill bit 20.
The dimensions and configuration of each layer of glue
may be selected to correspond with desired dimensions and
configuration of corresponding layers 101-105 of hard material
disposed at selected locations on exterior portions of matrix
drill bit 20. For some applications, the total thickness of
the hard material disposed at respective locations 101a-105a
may be between approximately 0.25 inches and 0.5 inches.
FIGURE 20 is a schematic drawing showing single layer 114
and hard materials which may also be disposed at location 101a
or any other desired location in mold assembly 200. The
overall configuration and dimensions of layer 114 in FIGURE 20
may be approximately the same as composite layer 101 in FIGURE
2B. For some applications, pellets 130 and/or 140 as shown in
FIGURE 20 20 may be larger than corresponding pellets 130
and/or 140 as shown in FIGURE 2E. For some applications
increasing the size of the pellets may accommodate forming
layer 114 in FIGURE 20 in a "single pass" of adhesive material
and a "single pass" to disperse hard materials therein as
compared with composite layer 101 formed by using three
separate layers or sublayers 111, 112 and 113 of glue and
respective distribution of hard materials within each layer or
sublayer.
The types of hard materials used to form layers 111, 112,
113 and 114 may be selected to be compatible with infiltration
of binder material therethrough during infiltration of matrix
materials 131 and 132 to form matrix bit body 50. Some
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examples of hard materials which may be satisfactory used to
form one or more layers of hard material disposed on exterior
portions of a matrix drill bit in accordance with teachings of
the present disclosure are shown in FIGURES 35, 30, 45 and 413.
FIGURES 30 and 40 are schematic representations of
respective layers of hard material disposed on matrix material
131 in accordance with teachings of the present disclosure.
For purposes of explanation, surface 122 as shown in FIGURES
30 and 40 may be representative of respective exterior
surfaces 122 associated with layers 101-105 of hard material
disposed at selected locations on exterior portions of matrix
drill bit 50. See FIGURE 1. Respective surfaces 122 of layers
101-105 may conform with and be tightly bonded to adjacent
matrix materials used to form matrix bit body 50. The cross
sections of a layer of hard material disposed on matrix
material as shown in FIGURES 30 and 40 may also be
representative of one or more layers of hard material disposed
in recesses 70 to form a gage pad (not expressly shown) on
respective blades 54.
Layer 103 as shown in FIGURE 30 may include tungsten
carbide particles or pellets 130 disposed in matrix 146 in
accordance with teachings of the present disclosure. Other
hard materials and/or hard particles selected from a wide
variety of metals, metal alloys, ceramic alloys and/or cermets
may also be used to form one or more layers 103 of hard
material. As a result of using tungsten carbide particles 130
having an optimum weight percentage of binder material, layer
103 may enhance erosion, abrasion, wear, impact and/or fatigue
resistance as compared with exterior portions of matrix bit
body 50 which do not include such layers of hard material.
Layer 104 as shown in FIGURE 40 may include tungsten
carbide particles or pellets 130 and encapsulated diamond
particles 140. In accordance with teachings of the present
disclosure. Other hard materials and/or hard particles
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selected from a wide variety of metals, metal alloys, ceramic
alloys and/or cermets may also be used to form one or more
layers 104 of hard material. By including both a combination
of tungsten carbide pellets 130 and diamond encrusted
5 particles or pellets 140, layer 104 may have enhanced erosion,
abrasion, wear, impact and/or fatigues resistance as compared
with exterior portions of matrix bit body 50 which do not
include such layers of hard material.
FIGURES 3A and 4A shows examples of welding rods which
10 may be satisfactory used to form one or more layers of hard
material on exterior portions of matrix bit body 50 such as
respective recesses 70 formed on blades 54 following removal
of matrix bit body 50 from as associated mold assembly. The
welding rods 71 and 71a may also be used to form one or more
15 layers of hard material to repair a used matrix drill bit in
accordance with teachings of the present disclosure.
For some applications both new matrix bit bodies and used
matrix drill bits may be heated to a desired temperature such
as approximately seven hundred degrees Fahrenheit (700 F) and
20 allowed to "soak" prior to forming one or more layers of hard
material on exterior portions thereof using welding rods 71 or
71a. The desired temperature may vary depending on materials
used to form an associated matrix bit body and hard particles
used to form the layers of hard material.
25 Heating a matrix bit body to an appropriate, relatively
uniform temperature may minimize potential cracking or damage
to the matrix bit body during welding. After one or more
layers of hard material have been disposed at selected
locations on the associated matrix bit body, the matrix bit
body may be slowly cooled at a desired rate to ambient
temperature. The cooling rate may be selected to prevent
cracking or damage to the matrix bit body and/or layers of
hard material.
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Welding rod 71 as shown in FIGURES 3A and 3B may be used
to form a layer of hard material with characteristics similar
to layer 103 as shown in FIGURE 3C. Welding rod 71a as shown
in FIGURES 4A and 4B may be used to form a layer of hard
material with characteristics similar to layer 104a shown in
FIGURE 40. Welding rods 71 and 71a may include respective
hollow steel tube 76 which may be closed at both ends with
filler 78 and hard particles 130 and/or 140 or other hard
materials disposed therein.
For some applications tungsten carbide pellets may have
generally spherical configurations (see FIGURES 30 and 40)
with a weight percentage of binder between approximately four
percent (496) plus or minus one percent (196) of the total
weight of each tungsten carbide pellet in accordance with
teachings of the present disclosure. Tungsten carbide pellets
may also be formed with an optimum weight percentage of binder
and various non-spherical or partially spherical
configurations (not expressly shown). For some applications
crushed tungsten carbide pellets may also be used.
Spherical tungsten carbide pellets formed with no binding
material or substantially 0% binder may tend to crack and/or
fracture during formation of a matrix deposit or hardfacing
layer containing such pellets. Tungsten carbide pellets formed
with no binding material or substantially 096 binder may also
fracture or crack when exposed to thermal stress and/or impact
stress. Spherical tungsten carbide pellets formed with
relatively high percentages (.5% or greater) by weight of
binding material or binder may tend to break down or dissolve
into solution during formation of an associated matrix deposit
or hardfacing layer. As a result, such spherical tungsten
carbide pellets and associated matrix deposit or hardfacing
layer may have less abrasion, erosion, wear, impact, and/or
fatigue resistance than desired. Spherical tungsten carbide
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pellets with more than 5% binder may crack when exposed to
thermal stress and/or impact stress.
Tungsten carbide pellets formed with an optimum
percentage of binding material or binder may neither crack nor
dissolve into solution in associated matrix material during
formation of one or more layers of hard material. Spherical
tungsten carbide pellets formed with an optimum percentage of
binding material and/or binder may also neither crack nor
fracture when exposed to thermal stress and/or impact stress.
Forming tungsten carbide pellets with an optimum weight
percentage of binding material in accordance with teachings of
the present disclosure may improve weldability of the tungsten
carbide pellets and may substantially improve temperature
stress resistance and/or impact stress resistance of the
tungsten carbide pellets to fracturing and/or cracking.
For some applications layers of hard material formed with
spherical tungsten carbide particles having an optimum weight
percentage of binder have shown improved wear properties
during testing of associated layers and/or matrix deposits.
For some applications improvement in wear properties may
increase approximately forty-five percent (45%) during wear
testing in accordance with ASTM B611 as compared with a matrix
deposits or layers of hard material having spherical tungsten
carbide particles with binding material representing five
percent (5%) or greater the total weight of each tungsten
carbide particle.
Layers of hard material may be formed with tungsten
carbide pellets having an optimum weight percentage of binding
material in a wide range of mesh sizes. For some applications
the size of such tungsten carbide pellets may vary between
approximately 12 U.S. mesh and 100 U.S. mesh. The ability to
use a wide range of mesh sizes may substantially reduce costs
of manufacturing such tungsten carbide pellets and costs
associated with forming a deposit matrix or hardfacing with
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such tungsten carbide pellets. For example, tungsten carbide
pellets 130 as shown in FIGURES 3C or 4C may have a size range
from approximately 12 to 100 U.S. Mesh.
Depending upon selected locations for depositing one or
more layers of hard material on a matrix bit body, tungsten
carbide pellets 130 may be selected within a more limited size
range such as 40 U.S. Mesh to 80 U.S. Mesh. For other
applications, tungsten carbide pellets 130 may be selected
from two or more different size ranges such as 30 to 60 mesh
and 80 to 100 mesh. Tungsten carbide pellets 130 may have
approximately the same general spherical configuration.
However, by including tungsten carbide pellets 130 or other
hard particles with different configurations and/or mesh
ranges, wear, erosion, abrasion, impact, and/or fatigue
resistance of resulting layers of hard material may be
modified to accommodate specific downhole operating
environments for an associated matrix drill bit. By increasing
the size of tungsten carbide pellets 130, a single layer of
hard material having optimum thickness may be deposited within
mold assembly 200 with a single pass. For some applications
the optimum size for tungsten carbide pellets may be
approximately sixteen (16) mesh to thirty (30) mesh.
Tungsten carbide pellets may be formed by cementing,
sintering, and/or HIP-sintering (sometimes referred to as
"sinter-hipping") fine grains of tungsten carbide with an
optimum weight percentage of binding material. Sintered
tungsten carbide pellets may be made from a mixture of
tungsten carbide and binding material such as cobalt powder.
Other examples of binding materials include, but are not
limited to cobalt, nickel, boron, molybdenum, niobium,
chromium, iron, and alloys of these elements. Various alloys
of such binding materials may also be used to form tungsten
carbide pellets in accordance with teachings of the present
disclosure. The weight percentage of the binding material may
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be approximately four percent (4%) plus or minus one percent
(1%) of the total weight of each tungsten carbide pellet.
A mixture of tungsten carbide and binding material may be
used to form green pellets. The green pellets may then be
sintered or HIP-sintered at temperatures near the melting
point of cobalt to form either sintered or HIP-sintered
tungsten carbide pellets with an optimum weight percentage of
binding material. HIP-sintering may sometimes be referred to
as "over pressure sintering" or as "sinter-hipping."
Sintering a green pellet generally includes heating the
green pellet to a desired temperature at approximately
atmospheric pressure in a furnace with no force or pressure
applied to the green pellet. HIP-sintering a green pellet
generally includes heating the green pellet to a desired
temperature in a vacuum furnace with pressure or force applied
to the green pellet.
A hot isostatic press (HIP) sintering vacuum furnace
generally uses higher pressures and lower temperatures as
compared to a conventional sintering vacuum furnace. For
example, a sinter-HIP vacuum furnace may operate at
approximately 1400 C with a pressure or force of approximately
800 psi applied to one or more hot tungsten carbide pellets.
Construction and operation of sinter-HIP vacuum furnaces are
well known. The melting point of binding material used to form
tungsten carbide pellets may generally decrease with increased
pressure. Furnaces associated with sintering and HIP-sintering
are typically able to finely control temperature during
formation of tungsten carbide pellets.
Layers of hard material disposed at selected locations on
exterior portions of a matrix body may include tungsten
carbide particles or pellets 130 having an optimum weight
percentage of binding material in accordance with teachings of
the present disclosure. Other hard materials and/or hard
particles selected from a wide variety of metals, metal
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alloys, ceramic alloys, and cermets may be used to form layers
101-105 of hard material. As a result of using tungsten
carbide particles 130 having an optimum weight percentage of
binding material, layers 101-105 of hard material may have
5 significantly enhanced abrasion, erosion, wear, impact, and/or
fatigue resistance.
A plurality of tungsten carbide pellets 130 having an
optimum weight percentage of binding material in accordance
with teachings of the present disclosure may be dispersed
10 within filler 78. A plurality of coated diamond particles 140
may also be dispersed within filler 78 of welding rod 71a.
Conventional tungsten carbide particles or pellets (not
expressly shown) which do not have an optimum weight
percentage of binder material may sometimes be included as
15 part of filler 78. For some applications, filler 78 may
include a deoxidizer and a temporary resin binder. Examples of
deoxidizers satisfactory for use with the present disclosure
may include various alloys of iron, manganese, and silicon.
For some applications, the weight of welding rods 71
20 and/or 71a may be approximately fifty-five percent to eighty
percent filler 78 and twenty to thirty percent or more steel
tube 76. Layers of hard material formed by welding rods with
less than approximately fifty-five percent by weight of filler
78 may not provide sufficient wear resistance. Welding rods
25 with more than approximately eighty percent by weight of
filler 78 may be difficult to use to form layers of hard
material with desired dimensions including thickness and/or
desired configurations.
Loose material such as powders of hard material selected
30 from the group consisting of tungsten, niobium, vanadium,
molybdenum, silicon, titanium, tantalum, zirconium, chromium,
yttrium, boron, carbon and carbides, nitrides, oxides, or
suicides of these materials may be included as part of filler
78. The loose material may also include a powdered mixture
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selected from the group consisting of copper, nickel, iron,
cobalt, and alloys of these elements to form matrix bit body
50. Powders of materials selected from the group consisting of
metal borides, metal carbides, metal oxides, metal nitrides,
and other superhard or superabrasive alloys may be included
within filler 78. The specific compounds and elements selected
for filler 78 will generally depend upon intended applications
for the resulting matrix drill bit and selected welding
technique.
When tungsten carbide pellets 130 are mixed with other
hard particles, such as coated diamond particles 140, both
types of hard particles may have approximately the same
density. One of the technical benefits of the present
disclosure may include varying the percentage of binding
materials associated with tungsten carbide pellets 130 and
thus the density of tungsten carbide pellets 130 to ensure
compatibility with coated diamond particles 140 and/or matrix
portion 146 of layers 101-105 of hard material.
Tungsten carbide pellets 130 with or without coated
diamond particles 140 and selected loose materials may be
included as part of a continuous welding rod (not expressly
shown), composite welding rod (not expressly shown), core wire
(not expressly shown) and/or welding rope (not expressly
shown). For some applications flexible, hard facing ropes may
be satisfactorily used to form one or more layers of hard
material at selected locations on exterior portions of a new
matrix drill bit or a used (dull) matrix drill bit. Flexible
welding rope or hard facing rope may be available from several
vendors including, but not limited to, Technogenia, Inc.
having offices in Conroe, Texas and Atlanta, Georgia. Some
welding ropes may include a central small diameter nickel wire
coated with a thick layer of hard particles and matrix
material such shown in FIGURES 3B and 4B.
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Oxyacetylene welding, atomic hydrogen welding techniques,
tungsten inert gas (TIG-GTA), stick welding, SMAW and/or GMAW
welding techniques may be satisfactorily used to form layers
of hard material at selected locations on used matrix drill
bit or new matrix bit bodies using welding rods, welding rope,
etc.
For some applications, a mixture of tungsten carbide
pellets 130 and coated diamond particles 140 may be blended
and thermally sprayed onto select portions of a matrix body of
a matrix body using techniques well known in the art. A laser
may then be used to densify and fuse the resulting powdered
mixture at selected locations on exterior portions of the
matrix body. U.S. Patent 4,781,770 entitled "A Process For
Laser Hardfacing Drill Bit Cones Having Hard Cutter Inserts"
shows one process satisfactory for use with the present
disclosure.
Layers of hard material 103 and 104 as shown in FIGURE 3C
and FIGURE 4C may include a plurality of tungsten carbide
particles 130 embedded or encapsulated in matrix portions 146
and 146a. Various materials including cobalt, copper, nickel,
iron, and alloys of these elements may be used to form matrix
portions 146 and 146a. For some applications matrix portions
146 and 146a may be similar to and operable to bond with
adjacent portion of matrix 131.
Coated diamond particles or encrusted diamond particles
140 may be formed using various techniques such as those
described in U.S. Patent 4,770,907 entitled "Method for
Forming Metal-Coated Abrasive Grain Granules" and U.S. Patent
5,405,573 entitled "Diamond Pellets and Saw Blade Segments
Made Therewith." Coated diamond particles 140 may include
diamond 144 with coating 142 disposed thereon. Materials used
to form coating 142 may be metallurgically and chemically
compatible with materials used to form both matrix portion
146a and binder for tungsten carbide pellets 130. For many
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33
applications, the same material or materials used to form
coating 142 will also be used to form matrix portion 146a and
associated matrix bit body.
Metallurgical bonds may be formed between coating 142 of
each coated diamond particle 140 and matrix portion 146a. As a
result of such metallurgical or chemical bonds coated diamond
particles 140 may remain fixed within layers of hard material
101-105 until the adjacent tungsten carbide pellets 130 and/or
other hard materials in matrix portion 146a have been worn
away. Coated diamond particles 140 may provide high levels of
abrasion, erosion and wear resistance to protect an associated
matrix body as compared with hardfacing formed from only
matrix portion 146a and tungsten carbide pellets 130. High
abrasion, erosion, wear, impact, and/or fatigue resistance of
the newly exposed tungsten carbide pellets 130 and/or coated
diamond particles 140 may increase overall abrasion, erosion,
wear, impact, and/or fatigue resistance of layers of hard
material 101-105. As surrounding matrix portion 146a continues
to be worn away, additional tungsten carbide pellets 130
and/or coated diamond particles 140 may be exposed to provide
continued protection and increased useful life of an
associated matrix drill bit.
Additional information about coated or encrusted diamond
particles and other hard particles may be found in U.S. Patent
6,469,278 entitled "Hardfacing Having Coated Ceramic Particles
Or Coated Particles Of Other Hard materials;" U.S. Patent
6,170,583 entitled "Inserts And Compacts Having Coated Or
Encrusted Cubic Boron Nitride Particles;" U.S. Patent
6,138,779 entitled "Hardfacing Having Coated Ceramic Particles
Or Coated Particles Of Other Hard Materials Placed On A Rotary
Cone Cutter" and U.S. Patent 6,102,140 entitled "Inserts And
Compacts Having Coated Or Encrusted Diamond Particles."
The ratio of coated diamond particles 140 or other hard
particles with respect to tungsten carbide pellets 130
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disposed within layers of hard material 101-105 may be varied
to provide desired erosion, abrasion, wear, impact, and
fatigue resistance for an associated matrix bit body depending
upon anticipated downhole operating environment. For some
extremely harsh environments, the ratio of coated diamond
particles 140 to tungsten carbide particles 130 may be 10:1.
For other downhole drilling environments, the ratio may be
substantially reversed.
Tube rod welding with an oxyacetylene torch (not shown)
may be satisfactorily used to form metallurgical bonds between
layers of hard material and adjacent portions of matrix bit
body 50 and metallurgical and/or mechanical bonds between
matrix portion 146 and tungsten carbide pellets 130. For other
applications, laser welding techniques may be used to form
layers of hard material on exterior portions of a matrix body.
Mold assembly 200a as shown in FIGURES 5 may include
several components such as mold 203a, gauge ring or connector
ring 204a, and funnel 220a. Mold 203a, gauge ring 204a, and
funnel 220a may be formed from graphite or other suitable
materials. Various techniques may be used including, but not
limited to, machining a graphite blank to form mold cavity
252a having a negative profile or a reverse profile of desired
exterior features for a resulting fixed cutter drill bit. For
example mold cavity 204a may have a negative profile which
corresponds with the exterior profile or configuration of
blades 54 and junk slots 56 as shown in FIGURE 1.
Various types of temporary displacement materials and
mold insert may be satisfactorily installed within mold cavity
252a depending on the desired configuration of a resulting
matrix drill bit. For example mold inserts 70a may be formed
from various materials such as consolidated sand and/or
graphite may be disposed within mold cavity 104. Various
resins may be satisfactorily used to form consolidated sand.
Mold inserts 70a may have configurations and dimensions
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corresponding with desired features of matrix bit body 50 such
as recess 70 formed in exterior portion 58 of blades 54. The
dimensions and configuration of mold inserts 70a and
associated recesses 70 may be selected to correspond with
5 desired dimensions and configuration for resulting gage pads
(not expressly shown) on respective blades 54.
Matrix bit body 50 may include relatively large fluid
cavity or chamber 32 with multiple fluid flow passageways 72
and 74 extending therefrom. See FIGURE 6. As shown in FIGURE
10 5, displacement materials such as consolidated sand may be
installed within mold assembly 200a at desired locations to
form portions of cavity 32 and fluid flow passages 72 and 74
extending therefrom. The orientation and configuration of
consolidated sand legs 172 and 174 may be selected to
15 correspond with desired locations and configurations of
associated fluid flow passageways 72 and 74 communicating from
cavity 32 to respective nozzles 68.
A relatively large, generally cylindrically shaped
consolidated sand core 150 may be placed on the legs 172 and
20 174. The number of legs extending from sand core 150 will
depend upon the desired number of nozzle openings in a
resulting matrix bit body.
After desired displacement materials, including core 150
and legs 172 and 174, have been installed within mold assembly
25 200a, matrix material 131 having desired characteristics for
matrix bit body 50 may be placed within mold assembly 200a.
The present disclosure allows the use of matrix materials
having characteristics of toughness and wear resistance for
forming a fix cutter drill bit or drag bit.
30 A generally hollow, cylindrical bit blank 36 may then be
placed within mold assembly 200a. Bit blank 36 preferably
includes inside diameter 37 which is larger than the outside
diameter of sand core 150. Various fixtures (not expressly
shown) may be used to position bit blank 36 within mold
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36
assembly 200a at a desired location spaced from first matrix
material 131.
For some applications second matrix material 132 such as
tungsten powder may then be placed in mold assembly 200a
between exterior portions of bit blank 36 and adjacent
interior portions of funnel 220a. Second matrix material 132
may be a relatively soft powder which forms a matrix that may
subsequently be machined to provide a desired exterior
configuration and transition between matrix bit body 50 and
bit blank 36. See FIGURE 6. Second matrix material 132 may
sometimes be described as an "infiltrated machinable powder."
Matrix material 131 may be cemented carbides and/or
spherical carbides as previously discussed. Alloys of cobalt,
iron, and/or nickel may be used to form cemented carbides
and/or spherical carbides. For some matrix drill bit designs
an alloy concentration of approximately six percent in the
first matrix material may provide optimum results. Alloy
concentrations between three percent and six percent and
between approximately six percent and fifteen percent may also
be satisfactory for some matrix drill bit designs. However,
alloy concentrations greater than approximately fifteen
percent and alloy concentrations less than approximately three
percent may result in less than optimum characteristics of a
resulting matrix bit body.
A typical infiltration process for forming matrix bit
body 50 may begin by forming mold assembly 200a. Gage ring
204a may be threaded onto the top of mold 203a. Funnel 220a
may be threaded onto the top of gage ring 204a to extend mold
assembly 200a to a desired height to hold previously described
matrix materials and binder material. Displacement materials
such as, but not limited to, mold inserts 70a, legs 172 and
174, and sand core 150 may then be loaded into mold assembly
200a if not previously placed in mold cavity 252a. Matrix
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materials 131 and 132 and bit blank 36 may be loaded into mold
assembly 200a as previously described.
As mold assemblies 200 or 200a are being filled with
matrix materials, a series of vibration cycles may be induced
in each mold assembly 200 or 200a to assist desired
distribution of each layer or zone of matrix materials 131 and
132. Vibrations help to ensure consistent density of each
layer of matrix materials 131 and 132 within respective ranges
required to achieve desired characteristics for matrix bit
body 50.
Binder material 160 may be placed on top of layer 132,
bit blank 36 and core 150. Binder material 160 may be covered
with a flux layer (not expressly shown). A cover or lid (not
expressly shown) may be placed over mold assembly 200a. Mold
assembly 200a and materials disposed therein may be preheated
and then placed in a furnace (not expressly shown). When the
furnace temperature reaches the melting point of binder
material 160, liquid binder material 160 may infiltrate matrix
materials 131 and 132 and layer 101-105 of hard material. See
FIGURE 2A.
Mold assembly 200a may then be removed from the furnace
and cooled at a controlled rate. Once cooled, mold assembly
200a may be broken away to expose matrix bit body 50. See for
example FIGURE 6.
Although the present disclosure has been described with
several embodiments, various changes and modifications may be
suggested to one skilled in the art. It is intended that the
present disclosure encompass such changes and modifications as
fall within the scope of the present appended claims.
