Core drilling apparatus

Claim 1

CORE DRILLING APPARATUS COMPRISING A TUBULAR DRILL STRING ADAPTED TO BE ROTATED AT THE SURFACE OF A WELL WHILE DRILLING FLUID IS CIRCULATED DOWN TO THE BOTTOM OF SAID WELL AND THEN BACK TO THE SURFACE THROUGH SAID TUBULAR DRILL STRING, AN ANNULAR DRILL BIT AT THE LOWER END OF SAID DRILL STRING ADAPTED TO CUT INTO A FORMATION LEAVING A CORE OF SAID FORMATION SUBSTANTIALLY OF A PREDETERMINED DIAMETER, A CAM MEMBER WITHIN SAID DRILL STRING A FIXED DISTANCE ABOVE SAID DRILL BIT EXTENDING INWARD FROM ONE SIDE THEREOF AN AMOUNT SUFFICIENT TO ENGAGE SAID CORE TO IMPART BENDING STRESSES THERETO TO BREAK SAID CORE INTO CORE SEGMENTS, AND THE INTERNAL DIAMETER OF SAID DRILL STRING BELOW SAID CAM MEMBER BEING GREATER THAN THE INTERNAL DIAMETER OF SAID DRILL BIT, MEANS DISPOSED LONGITUDINALLY WITHIN SAID DRILL STRING ON SAID ONE SIDE THEREOF BETWEEN SAID CAM AND SPACED INWARDLY FROM SAID ONE SIDE THEREOF AN AMOUNT SUFFICIENT TO REDUCE DIAMETRICAL DISTANCES TO THE OPPOSITE SIDE OF SAID DRILL STRING AN AMOUNT SUFFICIENT TO PREVENT TUMBLING OF ALL CORE SEGMENTS TOO LONG TO PASS LATERALLY BY SAID CAM.