U.S. patent application number 15/828725 was filed with the patent office on 2018-06-07 for steerable downhole hammer bit.
The applicant listed for this patent is Earth Tool Company LLC. Invention is credited to Robert F. Crane, Mark D. Randa, Steven W. Wentworth.
Application Number | 20180155985 15/828725 |
Document ID | / |
Family ID | 62240428 |
Filed Date | 2018-06-07 |
United States Patent
Application |
20180155985 |
Kind Code |
A1 |
Wentworth; Steven W. ; et
al. |
June 7, 2018 |
Steerable Downhole Hammer Bit
Abstract
A drill bit for use with a pneumatic hammer used in horizontal
directional drilling operations. A compact forward face is formed
on the first end of the drill bit. The forward face reciprocates
against a face of a borehole. A steering face is disposed behind
the forward face and is concave adjacent its first end and convex
adjacent its second end, with a smooth transition between the two
regions. The body has a circular profile at its second end. The
drill bit displaces cobble and small rocks encountered, rather than
breaking them, enhancing steering in mixed conditions.
Inventors: |
Wentworth; Steven W.;
(Scottsdale, AZ) ; Crane; Robert F.; (Nekoosa,
WI) ; Randa; Mark D.; (Summit, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Earth Tool Company LLC |
Lake Mills |
WI |
US |
|
|
Family ID: |
62240428 |
Appl. No.: |
15/828725 |
Filed: |
December 1, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62429166 |
Dec 2, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 7/064 20130101;
E21B 4/14 20130101; E21B 10/38 20130101 |
International
Class: |
E21B 7/06 20060101
E21B007/06; E21B 10/38 20060101 E21B010/38; E21B 4/14 20060101
E21B004/14 |
Claims
1. A method comprising: providing a drill bit comprising a body
having opposed first and second ends and opposed steering and
external faces formed between the first and second end, in which
the steering face has a concave portion that transitions into a
convex portion, in which the concave portion starts at the first
end and the convex portion terminates at the second end; attaching
the drill bit to an end of a downhole tool comprising a fluid
driven hammer; positioning the drill bit within an underground
zone; thrusting the drill bit forward in a first direction while
rotating the drill bit; thrusting the drill bit forward in a second
direction without rotation; and thrusting the drill bit forward in
the second direction while rotating the drill bit.
2. The method of claim 1 in which the underground zone contains
cobblestones.
3. The method of claim 1 further comprising reciprocating the drill
bit against a face of the underground zone using the fluid driven
hammer.
4. The method of claim 1 further comprising venting air from the
drill bit into the underground zone.
5. The method of claim 1 further comprising venting an air-foam
mixture from the drill bit into the underground zone.
6. A system comprising: a fluid driven hammer; and a drill bit
disposed in force-transmitted relationship to the hammer,
comprising: a body having opposed first and second ends and opposed
steering and external faces formed between the first and second
end, in which the steering face has a concave portion that
transitions into a convex portion, in which the concave portion
starts at the first end and the convex portion terminates at the
second end.
7. The system of claim 6 further comprising a drilling machine and
a drill string having opposed first and second ends, the first end
being operatively connected to the drilling machine and the second
end being connected to the hammer.
8. The system of claim 6 further comprising a magnetic dipole
transmitter installed within a housing connected to the hammer.
9. The system of claim 6 in which a chuck is positioned between the
hammer and the drill bit.
10. The system of claim 6 in which the second end of the body is
symmetric about a longitudinal axis of the drill bit and the first
end is asymmetric with respect to that axis.
11. The system of claim 6 in which the steering face is positioned
at a non-zero angle relative a longitudinal axis of the drill
bit.
12. The system of claim 6 in which at least one fluid port is
formed on the external face.
13. The system of claim 12 in which a flow passage is formed along
a longitudinal axis of the drill bit, in which the flow passage is
connected to at least one passage that extends at a non-zero angle
to at least one fluid port formed on the external face.
14. The system of claim 12 in which the at least one fluid port is
formed in a channel that extends from the first end to the second
end of the body.
15. The system of claim 6 further comprising a shank joined to the
second end of the body.
16. The system of claim 15 in which the second end of the body has
a maximum cross-sectional dimension that exceeds the maximum
cross-sectional dimension of the shank.
17. The system of claim 6 in which a rectilinear passage within the
body interconnects the external face and the steering face.
18. The system of claim 17 in which the rectilinear passage opens
on the steering face proximate the zone of transition between the
convex portion and the concave portion.
19. The system of claim 6 in which a forward face is positioned at
the first end of the body, in which the forward face is bounded by
a leading edge and a trailing edge, wherein the leading edge has a
width less than a width of the trailing edge.
20. The system of claim 19 in which the leading edge and the
trailing edge extend at a non-zero angle between the first end and
the second end of the drill bit.
21. The system of claim 6 in which the second end of the body has a
circular profile.
22. The system of claim 6 further comprising an underground terrain
containing cobblestones and having a borehole formed therethrough,
in which the hammer and drill bit are situated within the
borehole.
23. The system of claim 6 in which the transition from the concave
portion to the convex portion is made closer to the first end than
the second end.
Description
SUMMARY
[0001] The present invention is directed to a method comprising
providing a drill bit comprising a body having opposed first and
second ends and opposed steering and external faces formed between
the first and second ends. The steering face has a concave portion
that transitions into a convex portion. The concave portion starts
at the first end and the convex portion terminates at the second
end. The method further comprises attaching the drill bit to an end
of a downhole tool comprising a fluid driven hammer, lowering the
drill bit underground, thrusting the drill bit forward in a first
direction while rotating the drill bit, thrusting the drill bit
forward in a second direction without rotation, and thrusting the
drill bit forward in the second direction while rotating the drill
bit.
[0002] The present invention is directed to a system comprising a
drill bit and a fluid driven hammer connected to the drill bit. The
drill bit comprises a body having opposed first and second ends and
opposed steering and external faces formed between the first and
second ends. The steering face has a concave portion that
transitions into a convex portion. The concave portion starts at
the first end and the convex portion terminates at the second
end.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 is a schematic view of a horizontal directional
drilling operation.
[0004] FIG. 2 is a front perspective view of a drill bit of the
present invention.
[0005] FIG. 3 is a front elevation view of the drill bit of FIG.
2.
[0006] FIG. 4 is a cross-sectional view of the drill bit of FIG. 3
taken along line A-A.
[0007] FIG. 5 is a side elevation view of a body of the drill bit
of FIG. 2.
[0008] FIG. 6 is a cross-sectional view of FIG. 5, taken along line
B-B.
[0009] FIG. 7 is a cross-sectional view of FIG. 5, taken along line
C-C.
[0010] FIG. 8 is a cross-sectional view of FIG. 5, taken along line
D-D.
[0011] FIG. 9 is a top plan view of the drill bit of FIG. 2.
[0012] FIG. 10 is a top plan view of the drill bit of FIG. 2. The
drill bit is attached to a downhole tool.
DETAILED DESCRIPTION
[0013] With reference to FIGS. 1-2, a drill bit 10 for use in
horizontal directional drilling operations is shown. The drill bit
10 is attached to a front end 12 of a downhole tool assembly 14.
The downhole tool assembly 14 includes a chuck 86, a fluid driven
hammer 16, a transmitter housing 17, and a bent sub 94 (FIG. 10).
The hammer 16 operates by repeatedly striking a face 18 of an
underground borehole 20 with the drill bit 10 to form the borehole
20.
[0014] The drilling operations are powered by a directional
drilling machine 22 at a ground surface 24. The drilling machine 22
connects pipe sections together at the ground surface 24 to form a
drill string 26. A first end 28 of the drill string 26 is connected
to the drilling machine 22 and a second end 30 of the drill string
26 is connected to the downhole tool 14. In operation, the drilling
machine 22 will send air, an air-foam mixture, or fluid through the
drill string 26 to the downhole tool 14 to power the hammer 16. As
will be further described below, the drill bit 10 is configured to
allow the drill bit 10 to steer while drilling in rocky conditions
using the hammer 16.
[0015] Continuing with FIG. 2, the drill bit 10 comprises a body 32
attached to a shank 34. The drill bit 10 may be made of a wear
resistant metal, such as steel. The body 32 has a first end 36 and
an opposed second end 38. The shank 34 is joined to the second end
38 of the body 32. The shank 34 and body 32 may be formed as
separate pieces, or as a single piece. A steering face 40 and an
opposed external face 42 are formed between the first and second
ends 36, 38 of the body 32. The external face 42 has a rounded
outer surface. A longitudinal axis 44 of the drill bit 10 is also
shown via a dashed line in FIG. 2. The second end 38 of the body 32
is symmetric about the longitudinal axis 44 of the drill bit 10 and
the first end 36 is asymmetric with respect to the longitudinal
axis.
[0016] With reference to FIGS. 2-4, a forward face 46 is formed on
the first end 36 of the body 32. The forward face 46 makes first
contact with the face 18 of the borehole 20 (FIG. 1) during
drilling operations. The forward face 46 is bounded by a narrow
leading edge 48 and a wider trailing edge 50. The forward face 46
is also oriented at an angle between 0-15 degrees to a plane that
is orthogonal to an axis of rotation of the drill bit 10. The
drilling machine 22 rotates the drill string in a clockwise
direction, which in turn rotates the drill bit 10 in a clockwise
direction about its longitudinal axis 44. This allows the leading
edge 48 to contact the face 18 of the borehole 20 before the
trailing edge 50 during operation. Allowing the leading edge 48 to
make first contact with the face 18 of the borehole 20 prevents
churning that can impede forward progress by the drill bit 10.
Allowing the leading edge 48 to make first contact with the face 18
of the borehole 20 also helps to prevent disturbances of the
surrounding underground formation during operation.
[0017] The edges 48, 50 extend at a non-zero angle between the
first end 36 and the second end 38. Due to this, the area of the
external face 42 increases from the first end 36 to the second end
38. This is because the distance between the leading edge 48 and
the trailing edge 50 increases as the edges move from the first end
36 to the second end 38. The feature allows the edges 48, 50 of the
drill bit 10 to bite into the surrounding rock formation during
operation.
[0018] A brow 52 is formed on the external face 42 of the body 32
proximate the forward face 46 (FIG. 2). The drill bit 10 is wider
at its brow 52 than at other regions of its external face 42 (FIG.
5). The wider brow 52 provides a larger surface area for the
forward face 46 and deflects debris or rocks within the borehole 20
away from the remainder of the external face 42. A plurality of
carbide inserts 54 are also attached to the forward face 46. The
carbide inserts 54 help enhance cutting during boring and help
reduce wear on the drill bit 10. Carbide inserts 54 may also be
attached to the leading edge 48, as shown in FIG. 3. The
longitudinal axis 44 and the steering face 40 are also shown in
FIG. 3.
[0019] Turning now to FIGS. 4-8, the steering face 40 of the body
32 is shown in more detail. The drill bit 10 transitions smoothly
from a forward face 46 to a second end 38 having a circular
profile. The steering face 40 does not have a hollowed out center.
Rather, the steering face 40 has a concave portion 58 that extends
from the first end 36 and transitions into a convex portion 60. The
convex portion 60 terminates at the second end 38. The steering
face 40 has a circular profile at its second end 38, as shown in
FIG. 8. This shaping of the steering face 40 allows a relatively
compact forward face 46 to be formed at the first end 36. A rear
view of the forward face 46 is shown in FIG. 6.
[0020] The concave portion 58 transitions into the convex portion
60 at a transition zone or inflection 62. The transition zone 62 is
formed on or proximate the longitudinal axis 44 of the drill bit
10, as shown in FIGS. 5 and 7. The transition 62 is also positioned
closer to the first end 36 than the second end 38. In alternative
embodiments, the transition zone 62 may extend above or below the
longitudinal axis 44, rather than in alignment with that axis. Or
the transition zone 62 may coincide with the center of the steering
face 40. Or the transition zone 62 may be situated closer to the
second end 38 than the first end 36.
[0021] Viewed from ahead of the bit along its longitudinal axis,
the concave portion 58 presents a footprint that is fully contained
within the footprint of the convex portion 60. Thus, as the drill
bit 10 is thrust forward during drilling operations, the
cross-sectional area of the borehole 20 surrounding the drill bit
10 gradually increases.
[0022] The relatively small area of the forward face 46 aids in
drilling into rocky or mixed soil conditions, such as cobblestone.
Cobblestones are hard rocks typically surrounded by compacted sand.
The forward face 46 makes up less than 35% of the drill bit's 10
maximum cross-sectional area. The sizing allows the forward face 46
to break into fines or sand between cobblestones, rather than
chipping or cutting the stones themselves. High frequency
percussion against the fines allows the bit 10 to move the stones
radially out of the bore path. Orderly rearrangement of the mixed
rock formation, rather than cutting through the rock helps prevent
the borehole from collapsing during operation and requires less
torque and energy. Movement is possible because the percussion
rearranges the cobbles into a tighter formation, by allowing the
sand between the cobbles to drop into the borehole 20 and be
removed from the bore by the exhaust stream from the drill bit 10.
The drill bit 10 may also be used in loamy or sandy conditions.
[0023] Once the forward face 46 breaks between the stones, the
concave portion 58 of the drill bit 10 pushes or reorients the
position of the cobbles in order to make way for the rest of the
drill bit 10. Because the distance of the edges 38, 40 increases
between the first end 36 and the second end 38, the area of the
drill bit 10 that bites into the surrounding formation increases
towards the second end 38. By the second end 38, at least 40% of
the drill bit 10 is breaking into the surrounding rock formation.
The drill bit 10 creates a circular borehole 20 (FIG. 1) because
the second end 38 of the drill bit 10 has a circular profile.
[0024] Turning back to FIG. 2, the steering face 40 and external
face 42 are slanted or angled at a non-zero angle relative the
longitudinal axis 44 of the drill bit 10. Having a slanted steering
face 40 allows the drill bit 10 to steer during operation. While
drilling, the drill bit 10 is rotated at a steady rate while it
reciprocates against the face 18 of the borehole 20 (FIG. 1). The
drill bit 10 produces a straight bore path while it is rotated. In
order to change the direction the bore path, the steering face 40
is rotated to face the direction an operator desires to drill. The
drill bit 10 is then reciprocated against the face 18 of the
borehole 20 without being rotated. The slant of the steering face
40 will direct the drill bit 10 towards the desired direction. Once
the drill bit 10 is positioned in the desired direction, the drill
bit 10 may be rotated again in order to return to a straight bore
path.
[0025] Unlike traditional hammer drill bits, the drill bit 10 does
not require any rocking or carving motion to achieve steering.
Portions of the borehole 20 are more likely to collapse when
carving against the rock to achieve steering. The collapsed
borehole 20 may cause the drill bit 10 to tend to rise upward
during operation even as they are steered in a downward
direction.
[0026] With reference to FIGS. 4 and 8-9, the drill bit 10 has an
internal flow passage 64 formed along its longitudinal axis 44. The
flow passage 64 is connected to a plurality of passages 66 formed
in the body 32 of the drill bit 10. The passages 66 open into
exhaust ports 68, 70 formed on the external face 42 of the drill
bit 10 (FIG. 9). The passage 66 shown in FIG. 4 extends at a
non-zero angle relative to the flow passage 64.
[0027] Continuing with FIG. 9, the ports 68 vent exhaust from the
hammer 16 towards the forward face 46. The air may escape by
passing around the forward face 46 of the drill bit 10 and back
towards the opening of the borehole 20 at the ground surface 24.
The rear facing exhaust port 70 vents air directly towards the
opening of the borehole 20 at the ground surface 24. In other
embodiments, not shown in the Figures, one or more or all of the
ports formed in the external face may discharge toward the first
end. Alternatively, one or more or all of these ports may discharge
towards the second end. The drill bit 10 may not reciprocate
properly if the air cannot vent from the bit. The drill bit 10 is
provided with multiple ports 68, 70 so that venting of air is not
interrupted should a single port become clogged.
[0028] The exhaust ports 68 are formed within channels 72 formed in
the external face 42. The channels 72 are open-ended, and extend
between the first end 36 and the second end 38 of the body 32. The
rear facing exhaust port 70 is positioned within a channel 74. The
channel 74 only opens on the second end 38 of the body 32. The
channels 72, 74 help direct air venting from the drill bit 10 into
the borehole 20.
[0029] A through-hole 76 may also be formed in the body 32 of the
drill bit 10. The through-hole 76 is an open-ended rectilinear
passage that interconnects the steering face 40 and the external
face 42. The through-hole 76 opens on the steering face 40
proximate the transition zone 62. A pull-back adapter (not shown),
such as that described in U.S. Pat. No. 9,611,696 issued to Crane
et al., and incorporated herein for reference, may be installed
within the through-hole 76.
[0030] Continuing with FIG. 4, a foot valve 78 may be positioned
within the shank 34 of the drill bit 10, and a shuttle valve 80 may
be positioned above the foot valve 78. The valves 78, 80 control
pneumatic timing of the hammer 16 by regulating the flow of air
into the flow passage 64. When the hammer 16 is operating, the
shuttle valve 80 moves forward towards the body 32 and allows air
to pass through the drill bit 10. When the hammer 16 is not
operating, the shuttle valve 80 moves rearward and seals fluid from
entering the hammer 16 through the drill bit 10.
[0031] With reference to FIG. 9, the shank 34 of the drill bit 10
includes front and rear external splines 82, 84. The splines 82, 84
mate with internal splines (not shown) formed in a chuck 86 (FIG.
10) attached to the front end 12 of the downhole tool 14. The
splines 82, 84 prevent the drill bit 10 from rotating relative to
the downhole tool 14, while allowing the drill bit 10 to move
longitudinally relative to the tool 14. The drill bit 10 moves
longitudinally relative the downhole tool 14 so that it may
reciprocate against the face 18 of the borehole 20. The maximum
cross-sectional dimension of the second end 38 of the drill bit 10
is greater than the maximum cross-sectional dimension of the shank
34. The larger area of the second end 38 prevents the chuck 86 from
moving pas the second end 38 of the drill bit 10.
[0032] Turning now to FIG. 10, the downhole tool 14 may also
include a beacon or transmitter housed within the transmitter
housing 17. The beacon is preferably a magnetic dipole transmitter.
The beacon transmits a locating signal to an above ground tracker
during operation. The signal may contain information such as the
location, pitch, roll, and yaw orientation of the drill bit 10 and
housing 17. The signal may also provide the temperature and battery
life of the beacon to the above-ground tracker. The transmitter
housing 17 may have a cover 90 to permit access to the beacon, if
needed.
[0033] The hammer 16 may be attached to the chuck 86 and the
transmitter housing 17 may be attached to a rear end of the hammer
16, as shown in FIG. 10. The housing 17 may comprise an internal
passage (not shown) that is in fluid communication with the hammer
16, the drill bit 10, and the drill string 26.
[0034] At its brow 52, the drill bit 10 has a greater width than
either the downhole tool 14 or the drill string 26. This
configuration results in the drill bit 10 cutting a borehole 20
that has a cross-sectional dimension that is greater than the
cross-sectional dimension of the downhole tool 14. Clearance
between the downhole tool 14 and the walls of the borehole 20
reduces friction during drilling.
[0035] With reference to FIGS. 1 and 10, the drill bit 10 may be
used with the drill string 26 comprising a single rod or a two-pipe
drill string comprising an inner and an outer rod. If the drill bit
10 is used with a two pipe drill string 26, the inner rod rotates
the drill bit 10 relative to the housing 17 and the hammer 16.
[0036] The sub assembly 94 is attached to the rear end 92 of the
transmitter housing 17 in FIG. 10. Alternatively, the sub assembly
94 may be positioned between the transmitter housing 17 and the
hammer 16. The sub assembly 94 may be bent at an angle of 1-2
degrees relative the housing 17 and hammer 16. The sub assembly 94
enhances the steering capabilities of the drill bit 10 during
drilling operations.
[0037] Drilling through rock under mixed conditions without the use
of a hammer 16 may require the use of large drilling machines and
large quantities of drilling mud. Such machines typically weigh
over 7,000 pounds and have a large footprint. Large drilling
machines may not fit well in urban or semi-urban areas and it may
not be possible to use large quantities of drilling mud in such
areas.
[0038] In contrast, a hammer 16 can drill through rock or mixed
conditions when used with a small drilling machine, which may weigh
7,000 pounds or less. Use of a smaller machine is possible because
an underground hammer 16 requires less power than might be required
to push a drill string 22 from above ground.
[0039] Changes may be made in the construction, operation and
arrangement of the various parts, elements, steps and procedures
described herein without departing from the spirit and scope of the
invention as described in the following claims.
* * * * *