THE SUSPENSION CORE DRILL

CONVENTIONAL ROCK CORE DRILLING AT GREAT DEPTHS IS EXTREMELY EXPENSIVE AND TIME CONSUMING. ITS MAJOR DRAWBACK IS THE REQUIRED LENGTH OF DRILL PIPE. THE SUSPENSION CORE DRILL IS SUPPORTED BY CONTINUOUS FLEXIBLE LEADS HELD ON ONE OR MORE HIGH-SPEED REELS. WITHDRAWALS AND REPLACEMENT TIMES CAN BE REDUCED BY AN ORDER-OF-MAGNITUDE. COMMERCIAL USES INCLUDE STANDARD CORING APPLICATIONS AS WELL AS INTERMITTANT CORE SAMPLING FROM THE BOTTOM OR SIDES OF HOLES PRODUCED BY HIGHER SPEED DRILLS. AN INTRIGUING USE IS THE DETERMINATION OF ROCK TYPE BENEATH THICK GLACIERS AND ICE CAPS. ALSO, IT MAY PROVE THE KEY TO SUCCESSFUL FLAME-JET DRILLING ALLOWING PASSAGE OF THE DRILL THROUGH NON-SPALLABLE ZONES. PHASE I IS CONCERNED WITH DEFINING AND MEASURING VARIABLES GOVERNING CORE DRILLING IN HARD ROCK USING CONVENTIONAL CYLINDRICAL DIAMOND-FACED BITS. THESE VARIABLES INCLUDE ROTATIONAL SPEED, THRUST FORCES, AND VIBRATION EFFECTS ON BIT LIFE AND DRILLING SPEEDS. FROM THESE, THE BASIC ELEMENTS OF AN OPERABLE SYSTEM CAN BE DETERMINED.