U.S. patent application number 11/619418 was filed with the patent office on 2008-07-03 for apparatus and method for vibrating a drill bit.
Invention is credited to Scott Dahlgren, David R. Hall.
Application Number | 20080156536 11/619418 |
Document ID | / |
Family ID | 39561034 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080156536 |
Kind Code |
A1 |
Hall; David R. ; et
al. |
July 3, 2008 |
Apparatus and Method for Vibrating a Drill Bit
Abstract
In one aspect of the invention a drill bit comprises an axis of
rotation a body and a working face. The body comprises a fluid
passageway with a first seat and houses a jack element
substantially coaxial with the axis. A stop element is disposed
within the passageway and has a first near-sealing surface. The
jack element has a shaft intermediate an indenting end and a valve
portion. The valve portion has a second near-sealing surface
disposed adjacent the first near-sealing surface and a second seat
disposed adjacent the first seat. As a formation strongly resists
the jack element, the distance between the sealing surfaces
narrows. This causes an increase in fluid pressure within the
passageway and forces the indenting end down into the formation.
This movement of the jack element relieves the pressure build up
such that the formation pushes the jack element back, thereby
oscillating the jack element.
Inventors: |
Hall; David R.; (Provo,
UT) ; Dahlgren; Scott; (Alpine, UT) |
Correspondence
Address: |
TYSON J. WILDE;NOVATEK INTERNATIONAL, INC.
2185 SOUTH LARSEN PARKWAY
PROVO
UT
84606
US
|
Family ID: |
39561034 |
Appl. No.: |
11/619418 |
Filed: |
January 3, 2007 |
Current U.S.
Class: |
175/57 ; 175/389;
175/425 |
Current CPC
Class: |
E21B 10/38 20130101;
E21B 4/14 20130101; Y10T 408/9095 20150115 |
Class at
Publication: |
175/57 ; 175/389;
175/425 |
International
Class: |
E21B 10/40 20060101
E21B010/40; E21B 7/24 20060101 E21B007/24; E21B 10/62 20060101
E21B010/62; E21B 1/00 20060101 E21B001/00 |
Claims
1. A drill bit, comprising: an axis of rotation and drill bit body
intermediate a threaded end and a working face; the drill bit body
comprising a fluid passageway comprising a first seat and housing a
jack element substantially coaxial with the axis of rotation; a
stop element disposed within the passageway comprising a first
near-sealing surface; the jack element comprising a shaft
intermediate an indenting end and a valve portion, the indenting
end extending through the working face; the valve portion
comprising a second near-sealing surface disposed adjacent the
first near-sealing surface and a second seat disposed adjacent the
first seat; wherein as the formation being drilled strongly resists
the jack element, the distance between the respective sealing
surfaces narrows causing an increase in fluid pressure within the
passageway and forcing the indenting end down into formation, which
movement of the jack relieves the pressure build such that the
formation pushes the jack element back thereby oscillating the jack
element.
2. The drill bit of claim 1, wherein when the formation being
drilled lightly resists the jack element the valve portion
approximates the respective seats.
3. The drill bit of claim 1, wherein the second near-sealing
surface comprises a rounded geometry.
4. The method of claim 1, wherein a nozzle is disposed within an
opening in the working face.
5. The drill bit of claim 1, wherein the second near-sealing
surface comprises a surface with a hardness of at least 58 HRc.
6. The drill bit of claim 1, wherein the first near-sealing surface
comprises a surface with a hardness of at least 58 HRc.
7. The drill bit of claim 1, wherein the near-sealing surfaces
comprise a material selected from the group consisting of chromium,
tungsten, tantalum, niobium, titanium, molybdenum, carbide, natural
diamond, polycrystalline diamond, vapor deposited diamond, cubic
boron nitride, TiN, AlNi, AlTiNi, TiAlN, CrN/CrC/(Mo, W)S2,
TiN/TiCN, AlTiN/MoS2, TiAlN, ZrN, diamond impregnated carbide,
diamond impregnated matrix, silicon bounded diamond, and/or
combinations thereof.
8. The drill bit of claim 1, wherein the indenting end comprises a
superhard material.
9. The drill bit of claim 1, wherein the indenting end comprises an
asymmetric geometry.
10. The drill bit of claim 1, wherein the jack element is
rotationally isolated from the fluid passageway of the drill
bit.
11. The drill bit of claim 1, wherein a non-contact seal disposed
in the fluid passageway is formed to inhibit fluid passage.
12. The drill bit of claim 1, wherein the drill bit is attached to
a downhole tool string, wherein the downhole tool string comprises
a sensor adapted to receive acoustic reflections produced by the
movement of the jack element.
13. The drill bit of claim 1, wherein at least a portion of the
jack element is laterally supported by a bearing.
14. The drill bit of claim 1, wherein the bearing comprises a
material selected from the group consisting of chromium, tungsten,
tantalum, niobium, titanium, molybdenum, carbide, natural diamond,
polycrystalline diamond, vapor deposited diamond, cubic boron
nitride, TiN, AlNi, AlTiNi, TiAlN, CrN/CrC/(Mo, W)S2, TiN/TiCN,
AlTiN/MoS2, TiAlN, ZrN, diamond impregnated carbide, diamond
impregnated matrix, silicon bounded diamond, and combinations
thereof.
15. The drill bit of claim 1, wherein a spring coaxial with the
jack element proximal the drill bit is positioned within the fluid
passageway and adapted to contact the jack element.
16. A method for drilling a well bore, comprising the steps of:
providing a drill bit with an axis of rotation and a drill bit body
intermediate a threaded end and a working face; the drill bit body
comprising a fluid passageway housing a jack element; a stop
element disposed within the passageway comprising a first
near-sealing surface; the jack element comprising a valve portion
and an indenting end extending through the working face; the valve
portion comprising a second near-sealing surface disposed adjacent
the first near-sealing surface; applying a first axial force by
pressurizing the fluid passageway of the drill bit; and applying an
opposing force to the jack element. wherein the first near-sealing
surface and the second near-sealing surface form a restriction in a
fluid passage from the fluid passageway to at least one opening
disposed in the working face; wherein the restriction causes the
pressure in the fluid passageway to build up until it overcomes the
opposing force and displaces the jack element in the direction of
the first axial force, opening the restriction and thereby
relieving the pressure in the fluid passageway, wherein after
relieving the pressure in the fluid passageway, the opposing force
overcomes the first axial force and substantially returns the jack
element to its original position and reforms the restriction.
17. The method of claim 15, wherein the jack element is rotated by
a motor or a turbine.
18. The method of claim 15, wherein the restriction restricts all
flow within the fluid passage.
19. The method of claim 15, wherein the restriction restricts a
portion of the flow within the fluid passage.
20. The method of claim 15, wherein the opposing force is generated
by contacting the indenting end of the jack element against a
subterranean formation.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to the field of percussive tools used
in drilling. More particularly, the invention relates to the field
of downhole hammers which are actuated by the pressure of the
drilling fluid. Some of these tools are generally known in the
petroleum drilling industry simply as "downhole mud hammers".
[0002] Typically, downhole hammers are used to affect periodic
mechanical impacts upon a drill bit. Through this percussion, the
drill string is able to more effectively apply drilling power to
the formation, thus aiding penetration into the formation.
[0003] The prior art has addressed the operation of a downhole
hammer actuated by drilling mud. Such issues have been addressed in
the U.S. Pat. No. 5,396,965 to Hall, which is herein incorporated
by reference for all that it contains. The '965 patent discloses
improvements in downhole mud actuated hammers. According to its
broadest aspect the invention is a downhole mud actuated hammer for
use in a drill string, which includes a housing with an upper end
having means for connecting to the drill string. A throat is
located within the housing which throat includes a main flow
passage to allow high pressure drilling mud to pass therethrough. A
piston is provided which is adapted to move axially within the
housing means to thereby reciprocate between an up position and a
down position. The piston is moved between the up and down position
by a minor portion of the high pressure mud which portion passes
from the main flow passage into at least one piston actuating
chamber. This minor portion of mud is exhausted from the piston
actuating chamber to a low pressure region out of the housing
without being returned to the main flow passage.
[0004] U.S. Pat. No. 6,367,565 to Hall, which is also herein
incorporated by reference for all that it contains, discloses a
method of creating an electric signal that describes the motion of
a downhole, fluid-driven percussive tool. The signal is obtained by
attaching an electromagnetic transducer to the percussive tool, the
member impacted by it, or the drill string. The rebound
characteristics of the tool yield a measurement of the physical
characteristics of the subterranean formation being penetrated. The
tool's position over time is useful for diagnosing and regulating
the operation of the tool. The transducer can also be configured to
generate a signal large enough to be used as a power source.
BRIEF SUMMARY OF THE INVENTION
[0005] In one aspect of the present invention a drill bit comprises
an axis of rotation and a drill bit body intermediate a threaded
end and a working face. The drill bit body comprises a fluid
passageway that has a first seat and houses a jack element
substantially coaxial with the axis of rotation. A stop element is
disposed within the passageway and has a first near-sealing
surface. The jack element has a shaft intermediate an indenting end
and a valve portion. The indenting end extends through the working
face. The valve portion has a second near-sealing surface disposed
adjacent the first near-sealing surface and a second seat disposed
adjacent the first seat. As the formation being drilled strongly
resists the jack element, the distance between the respective
sealing surfaces narrows. This causes an increase in fluid pressure
within the passageway and forces the indenting end down into the
formation. This movement of the jack relieves the pressure build
such that the formation pushes the jack element back, thereby
oscillating the jack element.
[0006] In some embodiments, a nozzle may be disposed within an
opening in the working face to control and direct the drilling
fluid as well as control the flow of debris from the subterranean
formation. The second near-sealing surface of the jack element may
have a rounded geometry. It may also have a hard surface of at
least 58 HRc. Materials suitable for the near-sealing surfaces may
be selected from the group consisting of chromium, tungsten,
tantalum, niobium, titanium, molybdenum, carbide, natural diamond,
polycrystalline diamond, vapor deposited diamond, cubic boron
nitride, TiN, AlNi, AlTiNi, TiAlN, CrN/CrC/(Mo, W)S2, TiN/TiCN,
AlTiN/MoS2, TiAlN, ZrN, diamond impregnated carbide, diamond
impregnated matrix, silicon bounded diamond, and combinations
thereof. The indenting end of the jack element may be comprised of
a superhard material. It may also have an asymmetric geometry used
to guide the drill bit during a drilling operation
[0007] In some embodiments, a drill bit is attached to a downhole
tool string component for use in oil, gas, and/or geothermal
drilling; however, the present invention may be used in drilling
applications involved with mining coal, diamonds, copper, iron,
zinc, gold, lead, rock salt, and other natural resources, as well
as for drilling through metals, woods, plastics and related
materials. The downhole tool string may have a sensor that is
adapted to receive acoustic reflections produced by the movement of
the jack element. The sensor is used to determine the location of
reflectors in subterranean formations. Examples of reflectors
include boundaries between different sedimentary formations;
faults, cracks, or cavities; zones permeated with different fluids
or gases; and zones exhibiting a gradient in pore pressure.
[0008] In another aspect of the invention a method has steps for
drilling a well bore with a drill bit having an axis of rotation
and drill bit body intermediate a threaded end and a working face.
The drill bit body may have a fluid passageway comprising a first
seat and housing a jack element. The drill bit may also have a stop
element disposed within the passageway comprising a first
near-sealing surface. The jack element has a valve portion and an
indenting end that extends through the working face. The valve
portion may have a second near-sealing surface adjacent to the
first near-sealing surface.
[0009] When a first axial force is applied by pressurizing the
fluid passageway and an opposing force is also applied to the jack
element, the near-sealing surfaces may form a restriction in the
fluid passage from the fluid passageway to at least one opening
disposed in the working face. Drilling mud may pressurize the fluid
passageway, causing the first axial force. The opposing force may
be generated by contacting the indenting end of the jack element
against a subterranean formation. The restriction causes the
pressure in the fluid passageway to build up until it overcomes the
opposing force and displaces the jack element in the direction of
the first axial force, opening the restriction and thereby
relieving the pressure in the fluid passageway. The jack element
may be displaced 0.010 to 0.100 inches. After relieving the
pressure in the passageway, the opposing force overcomes the first
axial force and substantially returns the jack element to its
original position. This reestablishes the restriction in which the
first axial force is reformed by pressurizing the fluid passageway.
The building up and relieving of the pressure causes the jack
element to oscillate. As a result, the drill bit is able to
percussively fail a formation in a fluid environment.
[0010] In one embodiment of a method, the restriction may restrict
all flow within the fluid passage. In other embodiments, the
restriction may restrict a portion of the flow within the fluid
passage. The jack element may be rotated by a motor or turbine. The
jack element may also be rotationally isolated from the fluid
passageway of the drill bit. A non-contact seal, such as a
labyrinth seal, may be disposed in the fluid passageway to inhibit
fluid passage. The jack element may also be laterally supported by
a bearing that comprises a material with a hardness of at least 58
HRc. A spring coaxial with the jack element and proximal the drill
bit may be positioned within the fluid passageway so as to engage
the jack element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective diagram of an embodiment of a drill
string suspended in a bore hole.
[0012] FIG. 2 is a cross-sectional diagram of an embodiment of a
drill bit.
[0013] FIG. 3 is a cross-sectional diagram of an embodiment of an
adjustable restriction
[0014] FIG. 4 is a cross-sectional diagram of another embodiment of
an adjustable restriction
[0015] FIG. 5 is a cross-sectional diagram of another embodiment of
a drill bit.
[0016] FIG. 6 is a cross-sectional diagram of another embodiment of
a drill bit.
[0017] FIG. 7 is a cross-sectional diagram of another embodiment of
a drill bit.
[0018] FIG. 8 is a cross-sectional diagram of another embodiment of
an adjustable restriction.
[0019] FIG. 9 is a cross-sectional diagram of another embodiment of
an adjustable restriction.
[0020] FIG. 10 is a cross-sectional diagram of an embodiment of a
drill bit showing paths of energy emitted at the indenting end.
[0021] FIG. 11 is a diagram of an embodiment of a method for
drilling a well bore.
DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED
EMBODIMENT
[0022] FIG. 1 is a cross-sectional diagram of an embodiment of a
drill string 100 suspended by a derrick 101. A bottom-hole assembly
102 is located at the bottom of a bore hole 103 and comprises a
drill bit 104. As the drill bit 104 rotates downhole the drill
string 100 advances farther into the earth. The drill string 100
may penetrate soft or hard subterranean formations 105. The bottom
hole assembly 102 and/or downhole components may comprise data
acquisition devices which may gather data. The data may be sent to
the surface via a transmission system to a data swivel 106. The
data swivel 106 may send the data to the surface equipment.
Further, the surface equipment may send data and/or power b
downhole tools and/or the bottom-hole assembly 102. U.S. Pat. No.
6,670,880 which is herein incorporated by reference for all that it
contains, discloses a telemetry system that may be compatible with
the present invention; however, other forms of telemetry may also
be compatible such as systems that include mud pulse systems,
electromagnetic waves, radio waves, and/or short hop. In some
embodiments, no telemetry system is incorporated into the drill
string.
[0023] FIG. 2 is a cross-sectional diagram of a preferred
embodiment of a drill bit 104. The drill bit 104 comprises an axis
of rotation 200, a working face 201, a threaded end 202, and a jack
element 203. In this embodiment, a fluid passageway 204 has a first
seat 205 and houses the jack element 203. A stop element 206
disposed within the passageway 204 has a first near-sealing surface
207. In this embodiment, the jack element 203 is generally coaxial
with the axis of rotation 200 and comprises a shaft 208
intermediate an indenting end 209 extending from the working face
201 and a valve portion 210. The jack element 203 also comprises a
second near-sealing surface 211 in fluid communication with the
fluid passageway 204 of the drill bit 104. The second near-sealing
surface 211 may be adjacent to the first near-sealing surface 207.
A second seat 212 formed in the jack element 203 may be adjacent
the first seat 205.
[0024] A portion of the jack element 203 forms an adjustable
restriction 213 in a fluid passage intermediate the fluid
passageway 204 and an opening 214 disposed in the working face 201.
The adjustable restriction 213 is adapted to move to relieve
pressure build up in the passageway when a fluid is passed through
the fluid passageway 204. When a fluid is passed through the fluid
passageway 204, the jack element 203 is pushed against the
formation which resists the jack element axially loading it in a
direction depicted by arrow 215. The first and second near-sealing
surfaces may contact each other, restricting fluid passage and
therefore causing a pressure to build up in the fluid passageway
204. The pressure build up produces a first axial force. An
opposing force may also be applied in the opposite direction. This
force may be generated by contacting the indenting end 209 against
a subterranean formation 105. If the first axial force overcomes
the opposing force, the jack element 203 may displace in the
direction of the first axial force in which the first seat 205 may
contact the second seat 212. The opposing force may then overcome
the first axial force causing the jack element 203 to substantially
return to its original position, reforming the restriction. The
continual displacing of the jack element 203 and reforming of the
restriction 213 may produce an oscillation. The oscillation may
provide the drill bit with some of the advantages found in a
typically percussion bit, which may increase the bit's rate of
penetration.
[0025] When drilling in soft formations, the first axial force may
be greater than the opposing force wherein the jack element 203 may
not necessarily oscillate, but rather the valve portion 210 will
approximate the respective seats. However, when drilling in hard
formations, the jack element 203 may oscillate since the formation
will be able to substantially return the jack element to its
original position In some embodiments, the restriction 213 may
inhibit all fluid passage, and in other embodiments, the
restriction 213 may always allow fluid passage. If the restriction
213 inhibits all fluid passage, the pressure will build up in the
fluid passageway 204 at a rate greater than if the restriction 213
allows some fluid passage.
[0026] The drill bit 104 may comprise a spring 216 coaxial with the
jack element 203 and proximal the drill bit 104. The spring 216 may
be positioned within the fluid passageway 204 adapted to engage the
jack element 203. The spring 216 may be a coil spring, a Belleville
spring, a compression spring, a tension spring, or a gas spring. In
some embodiments the spring may be the stop element.
[0027] The second near-sealing surface 211 may have a rounded or
flat geometry and may have a hardness of at least 58 HRc. The
surface 211 may comprise a material selected from the group
consisting of chromium, tungsten, tantalum, niobium, titanium,
molybdenum, carbide, natural diamond, polycrystalline diamond,
vapor deposited diamond, cubic boron nitride, TiN, AlNi, AlTiNi,
TiAlN, CrN/CrC/(Mo, W)S2, TiN/TiCN, AlTiN/MoS2, TiAlN, ZrN, diamond
impregnated carbide, diamond impregnated matrix, silicon bounded
diamond, and combinations thereof. The restriction 213 also
comprises a surface with a hardness of at least 58 HRc.
[0028] The drill bit 104 may also comprise an axle 217 generally
coaxial with the axis of rotation 200. The axle 217 may be rotated
by a motor or turbine. The an end of the axle 217 which may
interlock with the jack element 203 may be generally cylindrically
shaped, generally rectangular, or generally polygonal. In some
embodiments, the jack element 203 is rotationally isolated from the
fluid passageway 204 of the drill bit 104 and the axle 217 may
rotate the jack element 203.
[0029] Preferably, the indenting end 209 comprises a superhard
material and an asymmetric geometry. During a drilling operation,
the rotational velocity of the jack element 203 may be adjusted so
that the indenting end 209 may steer the drill bit 104 in a desired
direction. Thus in drilling applications where a changed direction
is preferred, the jack element 203 may not rotate and thereby the
indenting end 209 may guide the drill bit 104 in the preferred
direction. Further, when the current direction is preferred, the
jack element 203 will rotate at a given velocity so that the
indenting end 203 may guide the drill bit 104 in the current
direction.
[0030] A non-contact seal 218 may be disposed in the fluid
passageway 204 of the drill bit 104 to inhibit fluid passage. The
non-contact seal 218 may allow some fluid passage or may restrict
all fluid passage. The non-contact seal 218 may generally be a
labyrinth seal. A portion of the jack element 203 may be laterally
supported by a bearing 219. The bearing 219 comprises a material
with a hardness of at least 58 HRc. The bearing 219 may support the
jack element 203 when it is subjected to lateral loads.
[0031] FIGS. 3 and 4 are cross-sectional diagrams of an embodiment
of an adjustable restriction 213. During a drilling operation, a
first axial force, indicated by arrow 300, may be applied by
pressurizing the fluid passageway 204 of the drill bit 104. The
fluid passageway 204 may be pressurized generally by drilling mud,
generally by air or generally by water. In this embodiment, the
restriction 213 restricts a portion of a fluid flow indicated by
arrow 301 within the fluid passage. One or more fluid ports 302 may
allow fluid to pass through the fluid passageway 204 into a space
303 adjacent the spring 216. During a drilling operation as shown
in FIG. 4 an opposing force, indicated by arrow 400 may be applied
to the jack element 203. The restriction 213 causes the pressure in
the fluid passageway 204 to build up until it overcomes the
opposing force 400 and displaces the jack element 203 in the
direction of the first axial force 300, opening the restriction 213
and thereby relieving the pressure in the fluid passageway 204 by
allowing the fluid flow 301 to pass by the restriction 213 into the
opening 214. The jack element 203 may be displaced 0.010 to 0.100
inches when relieving the pressure in the fluid passageway 204.
After relieving the pressure in the fluid passageway 204, the
opposing force 400 overcomes the first axial force 300 and
generally returns the jack element 203 to its original position and
reestablishes the restriction 213.
[0032] FIG. 5 is a cross-sectional diagram of another embodiment of
a drill bit 104. This embodiment is a close up of a portion of a
restriction 213 that inhibits fluid passage when closed. During a
drilling operation, fluid passes through the fluid passageway 204.
Fluid may pass through one or more fluid ports 302 into an opening
214. A first near-sealing surface 207 and a second near-sealing
surface 211 may be in contact, restricting fluid passage into an
opening 214. However, as fluid is forced into the fluid passageway
204, pressure builds up and eventually causes the first and second
near-sealing surfaces to separate, displacing the jack element 203.
Fluid within the fluid passageway 204 and within the space 303
adjacent the spring 216 will pass through the separated surfaces,
directed by an insert element 500, until the pressure is
substantially relieved, wherein the jack element 203 will be
restored to its original position and the first and second
near-sealing surfaces will be in contact again. The insert element
may be made of a material with a hardness of at least 58 HRc to
prevent its erosion from pressurized fluid passage. In the
embodiment of FIG. 5, the near sealing surfaces are made of a super
hard material such as silicon carbide, diamond, or cubic boron
nitride. In some embodiments, a cemented metal carbide may also be
used. The superhard material may be formed in segments with a high
temperature high pressure press and then ground to a preferred
geometry. In some embodiments the use of an electric discharge
machine may be used to further shape the super hard material. A
chamfer 550 on the side of the superhard material which experiences
the highest pressure may be used to reduce wear. The super hard
material may be brazed or pressure fit into the jack element or the
spring.
[0033] FIG. 6 is a cross-sectional diagram of another embodiment of
a drill bit 104. This embodiment may contain a coiled spring 216
that engages the jack element 203. The second near-sealing surface
211 may comprise a washer 600 with a surface of at least 58 HRc
that inhibits fluid communication with the spring 216. The second
near-sealing surface 211 of the jack element 203 may have a
hardness of at least 58 HRc. A first near-sealing surface 207 may
contact the second near-sealing surface 211 of the jack element
203. The first near-sealing surface 207 may comprise a material of
at least 58 HRc. The jack element 203 may also have a second seat
212 that may contact a first seat 205 to limit the displacement of
the jack element 203. The first seat 205 and the second seat 212
may comprise a material of at least 58 HRc. The jack element 203
may be laterally supported by a bearing 219 comprising a material
of at least 58 HRc. The drill bit 104 may also contain a nozzle 601
disposed within the opening 214 to control the fluid flow that may
exit the working face 201 of the drill bit 104.
[0034] FIG. 7 is a cross-sectional diagram of another embodiment of
a drill bit 104. This embodiment may contain at least one gas
spring 216 that responds to the displacement of the jack element
203. The gas spring 216 is activated by compressing a gas,
preferably nitrogen, in a gas compartment 700 with a piston 701.
The gas spring 216 may allow fluid passage through a least one
fluid port 702. Another variation of the gas spring 216 may allow
fluid passage through channels intermediate the gas compartment 700
and the second near-sealing surface 211 of the jack element 203.
The second near-sealing surface 211 and the first near-sealing
surface 207 may comprise materials of at least 58 HRc. In this
embodiment the drill bit 104 may contain a nozzle 601 disposed
within the opening 214. The jack element 203 may be laterally
supported by a bearing 219 comprising a material of at least 58
HRc.
[0035] FIGS. 8 and 9 are cross-sectional diagrams of another
embodiment of an adjustable restriction 213. This embodiment
comprises a jack element 203 substantially coaxial with the axis of
rotation 200 and comprising an indenting end 209 extending from the
working face 201. The second near-sealing surface 211 is in fluid
communication with the fluid passageway 204 of the drill bit 104.
The second near-sealing surface 211 may also comprise a rounded
geometry. A portion of the jack element 203 forms a restriction 213
in a fluid passage from the fluid passageway 204 to at least one
opening 214 disposed in the working face 201. As shown in FIG. 8,
the restriction 213 is formed intermediate the first near-sealing
surface 207 and the second near-sealing surface 211 and restricts
all fluid flow 301 within the fluid passage. A first axial force
300 may be applied by pressurizing the fluid passageway 204 of the
drill bit 104 with drilling fluid. The restriction causes pressure
in the fluid passageway to build up. The accumulated pressure
causes the jack element 203 to displace in the direction of the
first axial force 300, opening the restriction 213 and thereby
relieving the pressure in the fluid passageway 204. As indicated in
FIG. 9, an opposing force 400 may be applied to the jack element
203, which may be generated by contacting the indenting end 209 of
the jack element 203 against a subterranean formation 105. A second
seat 212 may contact a first seat 205, restricting fluid flow 301
to the opening 214. The opposing force 400 may overcome the first
axial force and substantially return the jack element 203 to its
original position and reform the restriction 213.
[0036] FIG. 10 is a cross-sectional diagram of an embodiment of a
drill bit 104 showing paths of energy emitted at the indenting end
209 as it oscillates. In this embodiment, acoustic waves 1000 may
be emitted from the indenting end 209 and may reach an acoustic
impedance boundary 1001. Acoustic impedance boundaries 1001 may be
a result from a feature in the subterranean formation 105 such as a
fault, a salt body, change in formation hardness, change in
formation material, a hydrocarbon formation, a change in density or
other changes in the formation. Acoustic waves 1000 reflect off of
such acoustic impedance boundaries 1001 and may be sensed by energy
receivers 1002 in the drill bit 104. The receivers may be
geophones, hydrophones or other seismic sensors. Physical
attributes of acoustic boundaries 1001 such as its spatial location
and dimensional or surface attributes, acoustic properties and
composition may be realized by interpreting the waves received by
the energy receivers 1002. These attributes may then be used to
direct the drill bit 104 along an economic trajectory with respect
to the acoustic boundaries 1001.
[0037] Sensors 1002 may be located in the drill bit itself, at some
location along the tool string or at the surface. In some
embodiments, the sensors may be located in a tool string component
attached to the drill bit 104. Other sensors (not shown) may be
used to record the frequency of the jack element's oscillations and
as well as time stamp at least some of jack element's impacts into
the formation. This information may be correlated with the time and
frequency of acoustic reflections received, which may help identify
the distance from the bit and type of acoustic boundary that is
encountered. Also the used inclination and direction package may
help determine the location of the acoustic impedance boundary.
[0038] FIG. 11 is a diagram of an embodiment of a method 2000 for
drilling a well bore. The method 2000 includes providing 2001 a
drill bit with a jack element that comprises a valve portion in
fluid communication with a fluid passageway of the drill bit. A
portion of the jack element forms a restriction so that fluid may
not pass from the fluid passageway to an opening disposed in a
working face. The method also includes applying 2002 a first axial
force by pressurizing the fluid passageway of the drill bit. The
first axial force may be generated by pressure build up in the
fluid passageway from the restriction of fluid passage. Further the
method 2000 includes applying 2003 an opposing force by contacting
a subterranean formation with an indenting end of the jack element.
The jack element may be displaced in the direction of the first
axial force and then returned to its original position, causing the
jack element to oscillate.
[0039] Whereas the present invention has been described in
particular relation to the drawings attached hereto, it should be
understood that other and further modifications apart from those
shown or suggested herein, may be made within the scope and spirit
of the present invention.
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