Drilling at a Resonant Frequency

Abstract

In one aspect of the invention, a method for drilling a bore hole includes the steps of deploying a drill bit attached to a drill string in a well bore, the drill bit having an axial jack element with a distal end protruding beyond a working face of the drill bit; engaging the distal end of the jack element against the formation such that the formation applies a reaction force on the jack element while the drill string rotates; and applying a force on the jack element that opposes the reaction force such that the jack element vibrates and imposes a resonant frequency into the formation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram of an embodiment of a drill string suspended in a bore hole

FIG. 2 is a cross-sectional diagram of an embodiment of a drill bit.

FIG. 3 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 4 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 5 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 6 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 7 is a cross-sectional diagram of an embodiment of a cutting element positioned on a drill bit.

FIG. 8 is a graph that shows an embodiment of a frequency.

FIG. 9 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 10 is a cross-sectional diagram of another embodiment of a drill bit.

FIG. 11 is a diagram of an embodiment of a method for drilling a bore hole.

Claims

1. A method for drilling a bore hole, comprising the steps of: deploying a drill bit attached to a drill string in a well bore, the drill bit comprising an axial jack element with a distal end protruding beyond a working face of the drill bit;engaging the distal end of the jack element against a formation such that the formation applies a reaction force on the jack element while the drill string rotates; andapplying a force on the jack element that opposes the reaction force such that the jack element vibrates and causes the formation to vibrate at its resonant frequency and degrade that formation.

2. The method of claim 1, wherein the force is a spring force or a hydraulic force.

3. The method of claim 2, wherein the spring force is adjusted by a spring mechanism comprising a compression spring, a tension spring, a coil spring, a Belleville spring, a gas spring, a wave spring, or combinations thereof.

4. The method of claim 3, wherein the spring mechanism comprises at least two springs engaged with the jack element.

5. The method of claim 2, wherein the spring force applies the force opposing the reactive force on the jack element.

6. The method of claim 2, wherein a motor or a piston adjusts the spring force on the jack element.

7. The method of claim 2, wherein the spring force is controlled hydraulically.

8. The method of claim 1, wherein approximately 15,000 lbs is loaded to the jack element.

9. The method of claim 1, wherein the jack element is rotationally isolated from the drill bit.

10. The method of claim 1, wherein a sensor proximate the jack element senses downhole vibrations.

11. The method of claim 1, wherein a stop disposed in the bore of the drill string restricts the oscillations of the jack element.

12. The method of claim 1, wherein a portion of the jack element is disposed in a wear sleeve comprising a hardness greater than 58 HRc.

13. The method of claim 1, wherein a portion of a nozzle is disposed around the jack element.

14. The method of claim 1, wherein the distal end comprises a pointed geometry.

15. The method of claim 1, wherein the distal end comprises a blunt geometry.

16. The method of claim 1, wherein the distal end is brazed to a carbide segment.

17. The method of claim 1, wherein the distal end 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/or combinations thereof.

18. The method of claim 1, wherein cutting elements disposed on the working face of the drill bit contact the formation at negative or positive rake angles.

19. The method of claim 1, wherein the drill string comprises a dampening system disposed on the drill string adapted to restrict vibrations from reaching a drill rig.

20. The method of claim 1, wherein the jack element protrudes out of a recess formed in a working portion of the drill bit.