Exhaust Port in a Protruding Element of a Downhole Drill Bit
In one aspect of the present invention, a drill bit comprises an axis of rotation and a drill bit body that comprises a central bore and a working face, the working face comprising a plurality of fixed element cutting elements, a jack element extending from the working face and being coaxial with the axis of rotation, the jack element comprising a proximal end in mechanical communication with an oscillating hammer mechanism, the jack element also comprising a channel in fluid communication with the central bore, the channel directing a fluid flow into a formation, wherein a fluid volume defined by the hammer mechanism and the central bore is evacuated through the channel.
The present invention relates to the field of downhole oil, gas and/or geothermal exploration and more particularly to the field of percussive tools used in drilling. More specifically, the invention relates to the field of downhole jack hammers and vibrators which may be actuated by drilling fluid or drilling mud.
Percussive jack hammers are known in the art and may be placed at the end of a bottom hole assembly (BHA). There they act to more effectively apply drilling power to the formation, thus aiding penetration into the formation.
U.S. Pat. No. 7,424,922 to Hall, et al., which is herein incorporated by reference for all that it contains, discloses a jack element which is housed within a bore of a tool string and has a distal end extending beyond a working face of the tool string. A rotary valve is disposed within the bore of the tool string. The rotary valve has a first disc attached to a driving mechanism and a second disc axially aligned with and contacting the first disc along a flat surface. As the discs rotate relative to one another at least one port formed in the first disc aligns with another port in the second disc. Fluid passed through the ports is adapted to displace an element in mechanical communication with the jack element.
Percussive vibrators are also known in the art and may be placed anywhere along the length of the drill string. Such vibrators act to shake the drill string loose when it becomes stuck against the earthen formation or to help the drill string move along when it is laying substantially on its side in a nonvertical formation. Vibrators may also be used to compact a gravel packing or cement lining by vibration, or to fish a stuck drill string or other tubulars, such as production liners or casing strings, gravel pack screens, etc., from a bore hole.
U.S. Pat. No. 4,890,682 to Worrall, et al., which is herein incorporated by reference for all that it contains, discloses a jarring apparatus provided for vibrating a pipe string in a borehole. The apparatus thereto generates at a downhole location longitudinal vibrations in the pipe string in response to flow of fluid through the interior of said string.
U.S. Pat. No. 7,419,018 to Hall, et al., which is herein incorporated by reference for all that it contains, discloses a downhole drill string component which has a shaft being axially fixed at a first location to an inner surface of an opening in a tubular body. A mechanism is axially fixed to the inner surface of the opening at a second location and is in mechanical communication with the shaft. The mechanism is adapted to elastically change a length of the shaft and is in communication with a power source. When the mechanism is energized, the length is elastically changed.
Notwithstanding the preceding patents regarding downhole jack hammers and vibrators, there remains a need in the art for more powerful mud actuated downhole tools. There is also a need in the art for means to easily adjust the force of the downhole tool. Thus, further advancements in the art are needed.
BRIEF SUMMARY OF THE INVENTIONIn one aspect of the present invention, a drill bit comprises an axis of rotation and a drill bit body that comprises a central bore and a working face, the working face comprising a plurality of fixed element cutting elements, a jack element extending from the working face and being coaxial with the axis of rotation, the jack element comprising a proximal end in mechanical communication with an oscillating hammer mechanism, the jack element also comprising a channel in fluid communication with the central bore, the channel directing a fluid flow into a formation, wherein a fluid volume defined by the hammer mechanism and the central bore is evacuated through the channel.
In some embodiments, the channel terminates at one or more nozzles disposed proximate the distal end of the jack element. The one or more nozzles may comprise a cross sectional area less than the cross sectional area of the channel. The one or more nozzles may comprise a wear resistant material such as polycrystalline diamond, cubic boron nitride, or tungsten carbide. In some embodiments, the nozzles may be threaded, pressed, or brazed into the jack element, or fastened by other methods or combinations thereof. The nozzles may comprise an adjustable trajectory.
In some embodiments, the jack element may be connected to the hammer mechanism by a shaft. The jack element may be connected to the shaft by a key and keyway, a bolted flange, a press fit, or combinations thereof. The shaft may be rotated by a turbine driven by the flow of drilling fluid, or by an electric motor. Torque from the turbine or electric motor may be directed through a gear assembly to increase or decrease the angular velocity of the shaft and thus the jack element.
The drill bit may rotate at a first angular velocity about the axis of rotation while the jack element rotates at a second angular velocity about the same axis of rotation. The second angular velocity may be equal in magnitude and opposite the direction of the first angular velocity. The second angular velocity may be variable in time, and may comprise a regular variation that repeats with every revolution of the jack element. The average angular velocity of the drill bit may or may not be equal to the average angular velocity of the jack element.
The jack element may comprise a hard material insert, and the insert may be disposed coaxial to the axis of rotation. In other embodiments, the insert may be disposed offset from the axis of rotation.
In some embodiments, the jack element may comprise an inclination instrumentation device in electrical communication with an electronic processing device disposed on the drill string.
Referring now to the figures,
A rotary valve assembly 207 may be disposed above the upper chamber 205. The rotary valve may comprise a stationary plate 208 and a rotating plate 209. Ports 210 in the rotating plate may alternately align and misalign with ports in the stationary plate, alternately allowing and blocking a fluid flow from entering the upper chamber 204.
The rotating plate 209 may be connected to a turbine 217 driven by the flow of drilling fluid or other fluid. Alternatively, the rotating plate may be driven by an electric motor, a positive displacement fluid device, or another method.
An anvil 211 may be in mechanical communication with a jack element 212. The jack element 212 may comprise a fluid channel 213 having an inlet 214 and an outlet 215. The jack element may slide freely in a bushing 216 or other bearing disposed in the drill bit body 200. The jack element translates between a fully extended position and a fully retracted position. The bushing may be made from brass, bronze, Babbitt metal, a polymer, other materials, or combinations of the above materials. Outlet 215 may comprise a nozzle fixed to the jack element. In some embodiments, the nozzle may comprise a cross-sectional area smaller than a cross-sectional area of the fluid channel 213, thus increasing the velocity of the fluid as it passes through the nozzle. The nozzle may be positioned to direct the fluid flow into the formation, or may be positioned to direct the fluid flow toward a working face to remove drilling chips, debris, and to cool the bit.
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In some embodiments, the angular velocity of the jack element may vary in time according to a repeating pattern. In one embodiment, the drill bit comprises a constant angular velocity 801. The jack element comprises an angular velocity that varies in time. In this embodiment, the jack element rotates quickly while the cutting element is in quadrants 804, 805 806, and slowly while the cutting element is in quadrant 807. Thus, in the time period of one revolution of the jack element, the offset cutting element is located within quadrant 807 for more than one quarter of the time period. It is believed that by varying the rotation of the jack element in this manner, the offset cutter will guide the drill bit in a direction corresponding to the quadrant through which the jack element rotates slowly through. Thus, directional drilling can be achieved by varying the angular velocity of the jack element.
The drill string may comprise inclination instrumentation devices that transmit information about the position, velocity, and direction of the drill bit, as well as instruments that provide information about the formation and drilling conditions. The data may be transmitted to the surface of the drilling operation for analysis and review through a communication system disposed in the drill string.
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.
Claims
1. A drill bit, comprising:
- an axis of rotation and a drill bit body comprising a central bore and a working face, the working face comprising a plurality of fixed cutting elements;
- a jack element extending from the working face and being coaxial with the axis of rotation;
- the jack element comprising a proximal end in mechanical communication with anaxially oscillating hammer mechanism;
- the jack element also comprising a channel in fluid communication with the central bore, the channel directing a fluid flow into a formation; wherein
- a fluid volume defined by the hammer mechanism and the central bore is evacuated through the channel.
2. The bit of claim 1, wherein the channel terminates at one or more nozzles disposed proximate the distal end of the jack element.
3. The bit of claim 2, wherein the one or more nozzles comprise a combined cross-sectional area less than the cross-sectional area of the channel.
4. The bit of claim 2, wherein the one or more nozzles comprise a wear resistant material such as polycrystalline diamond or cubic boron nitride.
5. The bit of claim 2, wherein the one or more nozzles are threaded into the jack element.
6. The bit of claim 2, wherein the one or more nozzles are pressed into the jack element.
7. The bit of claim 2, wherein the one or more nozzles are brazed into the jack element.
8. The bit of claim 2, wherein the one or more nozzles comprise an adjustable trajectory.
9. The bit of claim 1, wherein the jack element is connected to the hammer mechanism by a shaft.
10. The bit of claim 9, wherein the jack element is connected to the shaft by a key and keyway, a bolted flange, a press fit, threads, or combinations thereof.
11. The bit of claim 10, wherein the shaft is rotated by a fluid-driven turbine or an electric motor.
12. The bit of claim 11, wherein a gearbox is disposed intermediate the shaft and the turbine or electric motor.
13. The bit of claim 1, wherein the drill bit rotates at a first angular velocity about the axis of rotation and the jack element rotates at a second angular velocity about the axis of rotation.
14. The bit of claim 13, wherein the second angular velocity is equal in magnitude and opposite the direction of the first angular velocity.
15. The bit of claim 13, wherein the second angular velocity is variable in time.
16. The bit of claim 13, wherein the second angular velocity varies according to a pattern that repeats with every revolution of the jack element.
17. The bit of claim 1, wherein the jack element comprises a hard material insert.
18. The bit of claim 17, wherein the hard material insert is disposed coaxial to the axis of rotation.
19. The bit of claim 17, wherein the hard material insert is disposed offset from the axis of rotation.
20. The bit of claim 1, wherein the jack element comprises an inclination instrumentation device in electrical communication with an electronic processing device disposed on the drill string.
Type: Application
Filed: Apr 7, 2010
Publication Date: Oct 13, 2011
Inventors: David R. Hall (Provo, UT), Scott Dahlgren (Alpine, UT), Jonathan Marshall (Provo, UT)
Application Number: 12/755,534