System for producing a uniform rubble bed for in situ processes

A method of producing shale oil from an oil shale deposit, comprising the steps of:

• drilling at least one substantially vertical pilot hole in the oil shale deposit;
• reaming the pilot hole into an enlarged cavity, thereby producing rubblized oil shale and oil shale fines;
• drawing a flushing fluid out of the cavity to withdraw the oil shale fines, leaving a bed of rubblized oil shale in the cavity;
• heating the rubblized oil shale in the cavity to produce shale oil;
• and
• withdrawing the shale oil from the cavity.

A raise drill head for producing in an underground formation a cavity filled with a bed of rubblized material, comprising:

• a hollow body having a substantially circular base and sloping upper surface;
• a plurality of spaced cutter teeth mounted on the upper surface of the body, the body having a plurality of spaced relatively small holes located between the cutter teeth to flush out fines from the cavity when suction is applied to the hollow body, the body also having a plurality of relatively large peripheral flutes spaced around the base to allow rubblized material to drop into the cavity below the raise drill head;
• and
• a hollow shaft attached to the hollow body and opening into the hollow body.