Pulsed Electric Rock Drilling Apparatus with Non-Rotating Bit and Directional Control

• US 20090050371A1
• Filed: 08/26/2008
• Published: 02/26/2009
• Est. Priority Date: 08/20/2004
• Status: Active Grant

• Current Assignee: SDG, LLC
• Original Assignee: Tetra Corporation
• Inventors: Moeny, William M.
• Granted Patent: US 8,172,006 B2
• Time in Patent Office: Days
• US Class Current: 175/57
• CPC Class Codes: E21B 10/00 Drill bits specially adapted for deflecting the direction of boring E21B7/064; with means for collecting substances E21B27/00
• CPC Class Codes: E21B 7/15 of electrically generated heat

Abstract

The present invention provides for pulsed powered drilling apparatuses and methods. A drilling apparatus is provided comprising a bit having one or more sets of electrodes through which a pulsed voltage is passed through a mineral substrate to create a crushing or drilling action. The electrocrushing drilling process may have, but does not require, rotation of the bit. The electrocrushing drilling process is capable of excavating the hole out beyond the edges of the bit with or without the need of mechanical teeth.

Claims

1. A pulsed power drilling apparatus for passing a pulsed electrical current through a substrate to break the substrate, the apparatus comprising:

a non-rotatable drill bit comprising an electrocrushing drill;

a pulsed power generator linked to said drill bit for delivering high voltage pulses; and

at least one set of at least two electrodes disposed on said drill bit defining therebetween at least one electrode gap, said electrodes of each said set oriented substantially along a front of said drill bit, at least one of said electrodes disposed so that it touches the substrate and another of said electrodes disposed so that it functions in close proximity to the substrate for current to pass through the substrate.

2. The apparatus of claim 1 wherein said non-rotatable drill bit is disposed in a symmetric array.

3. The apparatus of claim 2 wherein said non-rotatable drill bit is disposed in said symmetric array comprising an angled side.

4. The apparatus of claim 2 wherein said non-rotatable drill bit is disposed in said symmetric array comprising a flat center.

5. The apparatus of claim 1 wherein said non-rotatable drill bit is disposed in an asymmetric array.

6. The apparatus of claim 1 wherein said non-rotatable drill bit comprises a multi-conical angle.

7. The apparatus of claim 1 wherein said non-rotatable drill bit comprises a flat section and a conical section.

8. The apparatus of claim 1 wherein said non-rotatable drill bit comprises a conical section.

9. A method for breaking and drilling a substrate comprising:

providing a non-rotating drill bit comprising an electrocrushing drill bit;

disposing at least one set of two electrodes on the drill bit, at least one set of at least two electrodes disposed on the drill bit defining therebetween at least one electrode gap;

orienting the electrodes of each said set substantially along a front face of said drill bit;

disposing at least one of the electrodes so that it touches the substrate and disposing another of the electrodes so that it functions in close proximity to the substrate for current to pass through the substrate; and

delivering a pulsed power current between the electrodes and through the substrate, breaking the substrate;

10. The method of claim 9 further comprising drilling a hole out beyond edges of the hole without mechanical teeth.

11. The method of claim 9 further comprising providing pulse energy to groups of electrode sets by a single pulsed power system per group.

12. The method of claim 9 further comprising providing pulse energy for each electrode set.

13. A method for differentially excavating a substrate comprising:

arranging multiple electrode sets at the front of a bit;

delivering a high voltage;

differentially operating electrode sets or groups of electrode sets varying a pulse repetition rate or pulse energy to the different electrode sets; and

steering the bit through the substrate by excavating more substrate from one side of the bit than another side.

14. The method of claim 13 further comprising directionally controlling the bit by increasing the pulse repetition rate or pulse energy for those electrode sets toward which it is desired to turn the bit.

15. The method of claim 13 wherein at least one of the electrode sets is conical.

16. The method of claim 13 further comprising using a pulsed power system to power the bit.

17. The method of claim 13 wherein the bit is an electrocrushing bit.

18. The method of claim 13 wherein the bit is an electrohydraulic bit.

19. The method of claim 13 further comprising switching stored electrical energy into the substrate using a plurality of switches and pulsed power circuits.

20. The method of claim 19 wherein the switches comprise at least one switch selected from the group consisting of a solid state switch, gas or liquid spark gap, thyratron, vacuum tube, solid state optically triggered switch and self-break switch.

21. The method of claim 13 further comprising storing energy in either capacitors or inductors.

22. The method of claim 13 further comprising creating the high voltage by a pulse transformer.

23. The method of claim 13 further comprising creating the high voltage by charging capacitors in parallel and adding them in series.

24. The method of claim 16 further comprising locating the pulsed power system downhole in a bottom hole assembly.

25. The method of claim 16 further comprising locating the pulsed power system at a surface with the pulse sent over a plurality of cables.

26. The method of claim 16 further comprising locating the pulsed power system in an intermediate section of a drill string.

27. The method of claim 13 further comprising flowing fluid flow through electrohydraulic projectors or electrocrushing electrode sets at a back of a bottom hole assembly to balance flow requirements in the bottom hole assembly.

28. A pulsed power drilling apparatus for passing a pulsed electrical current through a substrate to break the substrate, the apparatus comprising:

an electrocrushing drill comprising a non-rotating bit;

a main power cable inside a fluid pipe for powering said non-rotating bit electrocrushing drill; and

a main power cable on an outside of said fluid pipe for powering said non-rotating bit electrocrushing drill.

29. The apparatus of claim 28 wherein said main power cable on said outside of said fluid pipe is disposed inside continuous coiled tubing or other protective tubing or covering.

30. The apparatus of claim 28 further comprising electrohydraulic projectors or electrocrushing electrode sets disposed on a back of a bottom hole assembly.

31. A method of backwards excavation comprising:

locating electrohydraulic projectors or electrocrushing electrode sets or both electrohydraulic projectors and electrocrushing electrode sets on a backside of a bottom hole assembly;

drilling out backwards;

diverting electrical pulses from a main forward electrocrushing bit to the back electrohydraulic projectors/electrocrushing electrode sets;

using a controllable valve; and

diverting more flow from the main electrocrushing bit to the back electrohydraulic/electrocrushing bits when backwards drill-out is required.

32. An apparatus to drill out backwards comprising:

electrohydraulic projectors or electrocrushing electrode sets or both electrohydraulic projectors and electrocrushing electrode sets located on a back side of a bottom hole assembly;

switches inside said bottom hole assembly diverting electrical pulses from a main forward electrocrushing bit to back electrohydraulic projectors/electrocrushing electrode sets; and

a controllable valve diverting more flow from said main electrocrushing bit to said back electrohydraulic/electrocrushing sets when backwards drill-out is required.

33. The apparatus of claim 32 further comprising:

a fluid pipe comprising a rotatable drill pipe;

a cable disposed inside said fluid pipe; and

mechanical teeth installed on said back side of said bottom hole assembly.

34. A method of backwards excavation comprising:

rotating a bottom hole assembly to assist an electrohydraulic or electrocrushing projector in cleaning substrate from behind a bottom hole assembly;

pulling out the bottom hole assembly;

rotating the bottom hole assembly as it is pulled out;

fracturing the substrate behind the bottom hole assembly with the projectors; and

flushing particles of the substrate up the hole.

35. The method of claim 34 further comprising:

producing a high power shock wave from the projectors;

propagating a pulse through slumped substrate;

breaking up the slumped substrate behind the bottom hole assembly;

disturbing the substrate above the bottom hole assembly;

enhancing fluid flow through the bottom hole assembly to carry the substrate particles up the hole to the surface; and

continually disrupting the slumped substrate by a pressure pulse to keep it from sealing the hole.