Bi-center drill bit
View Patent ↗In one aspect of the present invention a drill bit assembly comprises a working portion opposite a shank of the bit. The working portion has a plurality of cutting elements. The drill bit assembly also has a central axis eccentric to its axis of rotation. A jack element protrudes from an opening formed in the working portion and has a distal end that is adapted to contact a formation at the axis of rotation.
1. A drill bit assembly, comprising:
a working portion opposite a shank of the bit, the working portion comprising a plurality of cutting elements;
a central axis eccentric to an axis of rotation of the drill bit assembly; and
a jack element protruding from an opening formed in the working portion and comprising a distal end adapted to contact a formation at the axis of rotation.
2. The drill bit assembly of claim 1 , wherein two or more openings disposed in the working portion are adapted to house separate jack elements.
3. The drill bit assembly of claim 1 , wherein the drill bit comprises two or more movable jack elements.
4. The drill bit assembly of claim 1 , wherein the jack element protrudes from an opening formed in a blade of the working portion.
5. The drill bit assembly of claim 1 , wherein the jack element protrudes from an opening formed in a junk slot area of the working portion.
6. The drill bit assembly of claim 1 , wherein an actuator disposed in a bore of the drill bit is adapted to retract the jack element.
7. The drill bit assembly of claim 6 , wherein the actuator comprises a stepper motor, an electrical motor, an electrically controlled valve, or combinations thereof.
8. The drill bit assembly of claim 6 , wherein the actuator is in communication with a downhole telemetry system.
9. The drill bit assembly of claim 6 , wherein the actuator comprises two or more rods adapted to engage concentric rings in communication with the jack element.
10. The drill bit assembly of claim 1 , wherein the working face is eccentric to the central axis.
11. The drill bit assembly of claim 1 , wherein a reamer is fixed to the drill bit.
12. The drill bit assembly of claim 1 , wherein the jack element is rotationally isolated from the drill bit.
13. The drill bit assembly of claim 1 , wherein the jack element is rotationally fixed to the working portion.
14. The drill bit assembly of claim 1 , wherein the shank portion is adapted for connection to a downhole drill string component.
15. The drill bit assembly of claim 1 , wherein the drill bit is kinked.
16. The drill bit assembly of claim 1 , wherein the jack element comprises a distal end comprising a hard material selected from the group consisting of diamond, cubic boron nitride, carbide, nitride, or combinations thereof.
17. The drill bit assembly of claim 1 , wherein the jack element comprises a base material comprising a hard material selected from the group consisting of hardened steel, tungsten carbide, niobium carbide, silicon carbide, cemented metal carbide, or combinations thereof.
18. The drill bit assembly of claim 1 , wherein the jack element comprises an outer layer comprising a hard material selected from the group consisting of diamond, cubic boron nitride, carbide, nitride, or combinations thereof.
19. The drill bit assembly of claim 1 , wherein the jack element is coaxial with the axis of rotation.
20. The drill bit assembly of claim 1 , wherein the jack element is press fit into a sleeve bonded to the working face.