Abrasive containing fluid jet drilling apparatus and process

A process for drilling holes in rock comprising:

• forming multiple fluid jet streams comprising abrasive particles in multiple nozzles spaced in the face of a rotary drill bit, said abrasive-fluid jet streams jetting from said nozzles at about 20 to about 90 degree angles to said face, said abrasive particles supplied through flexible hoses to a peripheral portion of each said nozzles separate from liquid pressurized to over 10,000 psi supplied through flexible hoses to liquid orifices in a central portion of each said nozzles;
• rotating said rotary drill bit in relation to an adjacent stationary drill head by a torque generation means within said drill head, said rotating drill bit with said abrasive-fluid jet streams cutting concentric grooves in said rock and removing rock between said grooves by mechanical cutters spaced on the face of said rotary drill bit between said fluid jet nozzles.

A process for drilling holes in rock comprising:

• forming multiple fluid jet streams comprising abrasive particles in multiple nozzles spaced in the face of a rotary drill bit, said abrasive-fluid jet streams jetting from said nozzles at about 20 to about 90 degree angles to said face, said abrasive particles supplied to said nozzles separately from pressurized fluid, each said multiple nozzles forming at least one fluid jet stream by introducing said abrasive particles through multiple orifices at an angle to and peripheral to said fluid jet stream, mixing said abrasive particles with said fluid jet stream, and passing said mixed abrasive particulate-fluid jet stream through a converging flow shaping nozzle, the throat of said flow shaping nozzle confining the output of said mixed abrasive-fluid jet stream;
• and
• rotating said rotary drill bit in relation to an adjacent stationary drill head by a torque generation means within said drill head, said rotating drill bit with said abrasive-fluid jet streams cutting concentric grooves in said rock and removing rock between said grooves by mechanical cutters spaced on the face of said rotary drill bit between said fluid jet nozzles.