Drill bit for downhole electrocrushing drilling

A electrocrushing drill bit, comprising:

• a bit body;
• an electrode coupled to a power source and the bit body, the electrode having a distal portion for engaging with a surface of a wellbore;
• a ground ring coupled to the bit body proximate to the electrode and having a distal portion for engaging with the surface of the wellbore, the ground ring surrounding the electrode and having a diameter approximately equal to a diameter of the bit body;
• and
• an insulator coupled to the bit body between the electrode and the ground ring.

A downhole drilling system, comprising:

• a drill string;
• a power source;
• and
• a drill bit coupled to the drill string and the power source, the drill bit including:
• a bit body;
• an electrode coupled to a power source and the bit body, the electrode having a distal portion for engaging with a surface of a wellbore;
• a ground ring coupled to the bit body proximate to the electrode and having a distal portion for engaging with the surface of the wellbore, the ground ring surrounding the electrode and having a diameter approximately equal to a diameter of the bit body;
• and
• an insulator coupled to the bit body between the electrode and the ground ring.

A method, comprising:

• placing a drill bit downhole in a wellbore, the drill bit including:
• a bit body;
• an electrode coupled to a power source and the bit body, the electrode having a distal portion for engaging with a surface of a wellbore;
• a ground ring coupled to the bit body proximate to the electrode and having a distal portion for engaging with the surface of the wellbore, the ground ring surrounding the electrode and having a diameter approximately equal to a diameter of the bit body;
• and
• an insulator coupled to the bit body between the electrode and the ground ring.
• supporting the weight of the drill bit and a drill string with a drill string support;
• providing electrical energy to the drill bit;
• providing electrocrushing drilling fluid to the drill bit;
• forming an electrical arc between the portion of the electrode proximate to the distal portion of the electrode and the portion of the ground ring proximate to the distal portion of the ground ring of the drill bit;
• fracturing a rock formation at an end of the wellbore with the electrical arc;
• and
• removing fractured rock from the end of the wellbore with the electrocrushing drilling fluid.