U.S. patent application number 10/533046 was filed with the patent office on 2006-07-06 for tool insert.
Invention is credited to Roy Derrick Achilles, Raymond Albert Chapman, Klaus Tank.
Application Number | 20060144621 10/533046 |
Document ID | / |
Family ID | 32231603 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060144621 |
Kind Code |
A1 |
Tank; Klaus ; et
al. |
July 6, 2006 |
Tool insert
Abstract
A tool insert comprises a substrate (40), a layer of ultra-hard
abrasive material (52) bonded to the substrate and presenting a
primary cutting edge (54) for the tool insert, and a protective
layer (56) bonded to the ultra-hard abrasive material so as to
protect the primary cutting edge thereof. The protective layer
provides a secondary cutting edge (58) for the tool insert, the
depth of the protective layer being selected so as to be sufficient
to protect the primary cutting edge whilst cutting, milling or
drilling a window through a first substance, such as a casing or
lining of a borehole or shaft, but to expose the primary cutting
edge upon encountering a second substance, such as a rockbed. The
invention extends to a method of drilling a horizontal or angled
hole in a sub-terranean rock formation using a rotary drill string
and bit incorporating a tool insert of the invention.
Inventors: |
Tank; Klaus; (Johannesburg,
ZA) ; Chapman; Raymond Albert; (Johannesburg, ZA)
; Achilles; Roy Derrick; (Bedfordview, ZA) |
Correspondence
Address: |
Ronald R Santucci;Frommer Lawrence & Haug
745 Fifth Avenue
New York
NY
10151
US
|
Family ID: |
32231603 |
Appl. No.: |
10/533046 |
Filed: |
September 12, 2003 |
PCT Filed: |
September 12, 2003 |
PCT NO: |
PCT/IB03/03892 |
371 Date: |
February 28, 2006 |
Current U.S.
Class: |
175/61 ; 175/426;
175/80 |
Current CPC
Class: |
E21B 29/06 20130101;
E21B 10/5676 20130101 |
Class at
Publication: |
175/061 ;
175/080; 175/426 |
International
Class: |
E21B 7/04 20060101
E21B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2002 |
ZA |
2002/8777 |
Claims
1. A tool insert comprising: a substrate; a layer of ultra-hard
abrasive material bonded to the substrate, the layer of ultra-hard
abrasive material having a side surface and a top surface, a
portion of the periphery of the top surface of the ultra-hard
abrasive material providing a primary cutting edge for the tool
insert; and a protective layer, a surface of the protective layer
being bonded to the top surface and/or the side surface of the
ultra-hard abrasive material so as to protect the primary cutting
edge thereof, a periphery of the protective layer providing a
secondary cutting edge for the tool insert, the depth of the
protective layer being selected so as to be sufficient to protect
the primary cutting edge whilst cutting, milling or drilling a
window through a first substance but to expose the primary cutting
edge upon encountering a second substance.
2. A tool insert according to claim 1, wherein the substrate is a
tungsten carbide substrate.
3. A tool insert according to claim 1, wherein the protective layer
is integrally formed with the substrate and is formed of the same
material as the substrate.
4. A tool insert according to claim 1, wherein the protective layer
is formed as a separate component in situ.
5. A tool insert according to claim 1, wherein the protective layer
is formed as a separate component which is bonded to the top
surface and/or the side surface of the ultra-hard abrasive
material.
6. A tool insert according to claim 1, wherein the protective layer
is provided in the form of a ring which is located about the
periphery of the layer of ultra-hard abrasive material.
7. A tool insert according to claim 1, wherein the protective layer
is an overlayer bonded to the top surface of the ultra-hard
abrasive material.
8. A tool insert according to claim 1, wherein the protective layer
forms a segment which is bonded to the substrate adjacent the layer
of ultra-hard abrasive material.
9. A tool insert according to any claim 1, wherein a plurality of
alternating ultra-hard abrasive material strips and protective
layer strips are located on the substrate, the successive strips of
ultra-hard abrasive material providing a series of primary cutting
edges and the successive protective layer strips providing a series
of secondary cutting edges.
10. A tool insert according to claim 1, wherein the protective
layer is formed of the same type of material as the substrate but
of a different grade to that of the substrate, or of tool steel or
of another suitable material dependent on the first substance.
11. A tool insert according to claim 1, wherein the first substance
is a casing or lining of a borehole or shaft in a bedrock and the
second substance is the bedrock.
12. A method of drilling a horizontal or angled hole in a
subterranean rock formation includes the steps of: 1) preparing the
site for horizontal or angled drilling by a) using an existing
borehole or, if not available, drilling a borehole into a
subterranean rock formation to an appropriate depth and b) lining
the borehole, at least in the region where horizontal or angled
drilling is to take place, with a casing or lining having a passage
and a deflector means mounted in the passage; 2) providing a drill
bit with at least one cutting tool insert, the or each cutting tool
insert comprising a substrate, a layer of ultra-hard abrasive
material bonded to the substrate, the ultra-hard abrasive material
providing a primary cutting edge for the tool insert, and a
protective layer for protecting the primary cutting edge and for
providing a secondary cutting edge; 3) guiding the drill bit down
the borehole until it contacts the deflector and is deflected
towards the casing or lining; 4) milling a window through the
casing or lining to the subterranean rock formation; and 5)
drilling a hole in the subterranean rock formation, wherein the
depth of the protective layer is such as to protect the primary
cutting edge whilst milling through the casing or lining and to
expose the primary cutting edge upon encountering the subterranean
rock formation.
13. A method according to claim 12, which is used for the drilling
of multiple directional holes from a central vertical borehole.
14. A method according to claim 12, wherein the cutting tool insert
is as defined in claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] THIS invention relates to tool inserts and more particularly
tool inserts which can be used as cutting elements in rotary
drilling bits intended for subterranean rock drilling.
[0002] The use of diamond compacts, also known as PCD, as cutters
in drilling operations is well known due to the high abrasion
resistant properties of diamond cutters. It is also well
established that diamond cutters cannot be used satisfactorily for
milling or drilling through ferrous substrates such as steel.
Therein lies a problem in the use of diamond cutters in certain
down the hole drilling operations, particularly with regard to
subterranean directional drilling, such as drilling horizontally
into a rockbed from an underground location in a vertical borehole
or shaft.
[0003] In order to drill horizontally into a rockbed from an
underground location, it is necessary to change the direction of
movement of the drill bit from a vertical direction to a horizontal
direction. To do so, a steel casing is typically positioned down
the vertical borehole or shaft, creating a lining therefor in the
region requiring horizontal drilling. Located within the steel
casing is a deflector which is positioned adjacent the position
where horizontal drilling is to be carried out. The function of the
deflector, which is generally wedge-shaped, is to cause the drill
to change direction and begin milling through the steel casing to
create a window to the bedrock.
[0004] As PCD is not suitable for drilling through the steel casing
due to reactions with the ferrous materials, an alternative drill
bit insert is required. Accordingly, tungsten carbide cutters are
typically used in the drill bit to mill through the steel casing.
Once through the casing, the tungsten carbide inserts have to be
replaced with abrasive resistant cutters such as diamond cutters in
order to drill into the bedrock. This means that the drill bit has
to be removed and replaced with an appropriate bit. As the drill
strings that have to be removed are very long, this is a time
consuming exercise that results in costly downtime.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the invention, a tool insert
comprises: [0006] a substrate; [0007] a layer of ultra-hard
abrasive material bonded to the substrate, the layer of ultra-hard
abrasive material having a side surface and a top surface, a
portion of the periphery of the top surface of the ultra-hard
abrasive material providing a primary cutting edge for the tool
insert; and [0008] a protective layer, a surface of the protective
layer being bonded to the top surface and/or the side surface of
the ultra-hard abrasive material so as to protect the primary
cutting edge thereof, a periphery of the protective layer providing
a secondary cutting edge for the tool insert, the depth of the
protective layer being selected so as to be sufficient to protect
the primary cutting edge whilst cutting, milling or drilling a
window through a first substance, such as a casing or lining of a
borehole or shaft, but to expose the primary cutting edge upon
encountering a second substance, such as a rockbed.
[0009] According to a further aspect of the invention, a method of
drilling a horizontal or angled hole in a subterranean rock
formation includes the steps of: [0010] 1) preparing the site for
horizontal or angled drilling by a) using an existing borehole or,
if not available, drilling a borehole into a subterranean rock
formation to an appropriate depth and b) lining the borehole, at
least in the region where horizontal or angled drilling is to take
place, with a casing or lining having a passage and a deflector
means mounted in the passage; [0011] 2) providing a drill bit with
at least one cutting tool insert, the or each cutting tool insert
comprising a substrate, a layer of ultra-hard abrasive material
bonded to the substrate, the ultra-hard abrasive material providing
a primary cutting edge for the tool insert, and a protective layer
for protecting the primary cutting edge and for providing a
secondary cutting edge; [0012] 3) guiding the drill bit down the
borehole until it contacts the deflector and is deflected towards
the casing or lining; [0013] 4) milling a window through the casing
or lining to the subterranean rock formation; and [0014] 5)
drilling a hole in the subterranean rock formation,
[0015] wherein the depth of the protective layer is such as to
protect the primary cutting edge whilst milling through the casing
or lining and to expose the primary cutting edge upon encountering
the subterranean rock formation.
[0016] The above method can also be used for the drilling of
multiple directional holes from a central vertical borehole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The invention will now be described in more detail, by way
of example only, with reference to the accompanying drawings in
which:
[0018] FIG. 1 is a schematic sectional side view of a rotary drill
bit in a subterranean rock drilling operation;
[0019] FIG. 2 is a sectional side view of a first embodiment of a
tool insert of the invention;
[0020] FIG. 3 is a plan view of the tool insert of FIG. 2;
[0021] FIG. 4 is a sectional side view of a second embodiment of a
tool insert of the invention;
[0022] FIG. 5 is a sectional side view of a third embodiment of a
tool insert of the invention;
[0023] FIG. 6 is a plan view of the tool insert of FIG. 5;
[0024] FIG. 7 is a sectional side view of a fourth embodiment of a
tool insert of the invention;
[0025] FIG. 8 is a plan view of the tool insert of FIG. 7;
[0026] FIG. 9 is a sectional side view of a fifth embodiment of a
tool insert of the invention; and
[0027] FIG. 10 is a plan view of the tool insert of FIG. 9.
DESCRIPTION OF EMBODIMENTS
[0028] Referring to FIG. 1 a drill assembly 10 consists of a rotary
drill string 12 and a rotary drill bit 14, of the drag bit kind in
this case.
[0029] The drill bit 14 is directed down a passage 16 within a
steel tubular casing 18. The steel casing 18 is anchored in a
borehole or shaft 20 drilled into a subterranean bedrock or rock
formation 22.
[0030] In order for the rotary drill bit 14 to drill a horizontal
or angled hole in the bedrock 22 in the region indicated by an `X`,
it is necessary for the drill bit 14 to be redirected from a
vertical direction of movement to a horizontal or angled direction
of movement, along the arrow 24. A deflector 26, which is attached
to the casing 18 and which has previously been positioned adjacent
the region `X`, causes the bit 14 to change direction in this
manner. The deflector 26 is supported by an anchor 28.
[0031] As mentioned previously, in order to drill through the
casing 18, typically cemented tungsten carbide cutters have
traditionally been used. Once a window 30 has been milled through
the casing 18, the drill bit 14 is withdrawn and replaced with a
drill bit having abrasion resistant cutters such as PCD cutters.
This time consuming operation is obviated by using tool inserts or
cutters of the invention.
[0032] The layer of ultra-hard abrasive material will generally be
a layer of PCD, although under appropriate conditions PCBN may also
be used. The layer may also be a layer of diamond produced by
chemical vapour deposition, called CVD diamond.
[0033] The substrate of the tool insert will generally be a
cemented carbide substrate. Such substrates are well known in the
art and are generally cemented tungsten carbide substrates.
[0034] The protective layer, which may be an extension of the
substrate or a separate layer, will also generally be of cemented
tungsten carbide, although it may be of a different grade to that
of the substrate. In certain instances, the protective layer may be
formed of tool steel or other appropriate material suited to
milling through steel or other material used for the casing or
lining.
[0035] Referring to FIGS. 2 and 3, a first embodiment of a tool
insert of the invention is illustrated. A cemented carbide
substrate 40 has a planar base surface 42 and an upper surface 44.
A centrally located recess 46 is formed in the upper surface 44.
The recess 46 is surrounded by an annular region 48 and has a
surface 50. Although the recess 46 is centrally located in this
embodiment, it could also be positioned off centre.
[0036] The recess 46 is filled with diamond particles. Thereafter,
the diamond-filled substrate 40 is placed in a reaction capsule and
the reaction capsule placed in the reaction zone of a conventional
high pressure/high temperature apparatus. The capsule is exposed to
conditions of high pressure and temperature suitable to produce a
diamond abrasive compact (PCD) 52. Under these conditions the PCD
52 will form and bond to the cemented carbide substrate over the
entire surface which defines the recess 46. A cutting edge 54, the
primary cutting edge of the tool insert, is defined by the
periphery of the PCD 52.
[0037] The cemented carbide/PCD body is then removed from the
reaction capsule using known techniques. As such the cemented
carbide/PCD body forms a precursor of a tool insert of the
invention.
[0038] To produce a tool insert of the invention, the annular
region 48 of the substrate 40 is ground or otherwise removed so as
to leave a predetermined depth, indicated by the numeral 56, of
tungsten carbide material. This depth of material 56 is selected so
as to correspond to the amount of tungsten carbide material
required to mill through the wall of a steel casing or lining of a
borehole, as described above. To this end, the depth of tungsten
carbide 56 provides a protective layer for the primary cutting edge
54 of the PCD 52, and also a secondary cutting edge 58 for milling
through the steel casing. Once a window has been milled through the
steel casing, ideally the layer 56 should be almost expended so as
to expose the cutting edge 54 for drilling into the rockbed.
[0039] In some applications, the tungsten carbide substrate 40,
whilst having the desired properties for forming the PCD layer 52,
may not have the desired properties for milling through a steel
casing or lining. In view thereof, the annular protective layer 48
may be replaced by tungsten carbide of a different grade or by
another suitable material, such as tool steel, for example. The
annular region 48 in such a case could be formed as a ring in situ
or, alternatively, could be formed as a separate ring component
which is attached to the tool insert. The ring 48 may be attached
to the tool insert, which has been machined to accept the ring, by
for example brazing, press fitting, shrink fitting or any other
convenient method.
[0040] As the function of the protective layer is to protect the
cutting edge of the PCD and provide a cutting edge for drilling
through a steel substrate, it need not be an extension of the
substrate of the tool insert as described above. As shown in FIG.
4, a second embodiment of a tool insert of the invention comprises
a tungsten carbide substrate 60, a PCD layer 62 having a cutting
edge 64, and a tungsten carbide protective overlayer 66 having a
cutting edge 68. As before, the depth 70 of the protective
overlayer 66 is selected so as to mill a window through the steel
casing or lining of a borehole in a subterranean bedrock whilst
exposing the PCD cutting edge 64 once through the steel casing.
[0041] A third embodiment of a tool insert of the invention is
illustrated in FIGS. 5 and 6 of the accompanying drawings. The tool
insert consists of a cemented carbide substrate 80, a PCD layer 82,
having a cutting edge 84, and a tungsten carbide protective segment
86, having a cutting edge 88, bonded to the substrate 80. The
tungsten carbide segment 86 could be an extension of the substrate
80. Alternatively, if the grade of the tungsten carbide substrate
80 is not appropriate for the cutting of a particular grade of
steel, the tungsten carbide segment 86 could be formed of a
tungsten carbide material of a different grade that is adapted to
the particular substrate to be milled. The depth of the tungsten
carbide segment 86 is once again selected so as to protect the
cutting edge 84 whilst drilling through a steel casing, but to
expose the cutting edge 84 soon after encountering the subterranean
bedrock.
[0042] Referring to FIGS. 7 and 8, which illustrate a fourth
embodiment of a tool insert of the invention, a tungsten carbide
substrate 90 includes a number of parallel recesses 92 in which
parallel PCD segments or strips 94 are formed. The PCD segments 94
are protected by respective tungsten carbide segments or strips 96.
In this arrangement, the cutting edges 98 of respective PCD
segments 94 are protected by the tungsten carbide segments 96,
which in turn have cutting edges 100. This arrangement allows the
tool insert to be used for cutting through successive layers of
steel and subterranean bedrock and can therefore be used multiple
times.
[0043] Referring to FIGS. 9 and 10, a fifth embodiment of a tool
insert of the invention comprises a substrate 110 on which is
formed a PCD layer 112. Typically, the substrate 110 and PCD layer
112 would be formed in a conventional high pressure/high
temperature apparatus, whereafter the relevant portion of the
substrate would be ground away to expose the primary cutting edge
114 of the PCD layer 112. In order to protect the cutting edge 114
in a subterranean rock drilling process of the invention, the
substrate 110 and PCD layer 112 are brazed into a cup 116 which is
typically formed of a high speed tool steel, which cup 116 includes
a cutting edge 118 for milling through the steel casing or lining
of a borehole in a subterranean rockbed.
[0044] As should be evident from the above, a number of different
configurations of the tool insert of the invention are possible in
order to achieve the desired purpose of protecting the primary
cutting edge of a PCD or PCBN layer whilst milling a window through
the steel casing or lining of a borehole in a subterranean bedrock,
and exposing the PCD or PCBN cutting edge once through the steel
casing.
* * * * *