Neutron-gamma borehole logging method and apparatus for identifying elements in borehole formations

Claim 1

A METHOD OF RADIOACTIVITY WELL LOGGING THAT COMPRISES THE STEPS OF TRAVERSING THE FORMATIONS PENETRATED BY A WELL WITH A SOURCE OF NEUTRONS TO THEREBY IRRADIATE THE FORMATIONS WITH NEUTRONS, SIMULTANEOUSLY AND BY THE SAME TRAVERSING STEP SEPARATELY DETECTING AT A FIRST POINT SPACED FROM SAID SOURCE GAMMA RADIATION RESULTING FROM NEUTRON CAPTURE IN THE FORMATIONS WITHOUT DETECTING GAMMA RADIATION RESULTING FROM THE INELASTIC SCATTERING OF NEUTRONS IN THE FORMATIONS BY PRODUCING PROPORTIONALLY RELATED ELECTRICAL PULSES, SIMULTANEOUSLY AND BY THE SAME TRAVERSING STEP SEPARATELY DETECTING AT A SECOND POINT NEARER SAID SOURCE THAN SAID FIRST POINT GAMMA RADIATION INCLUDING GAMMA RADIATION RESULTING FROM THE INELASTIC SCATTERING OF NEUTRONS IN THE FORMATIONS BY PRODUCING PROPORTIONALLY RELATED ELECTRICAL PULSES, SEPARATELY TRANSMITTING THE ELECTRICAL PULSES TO THE SURFACE OF THE EARTH, SEPARATELY DIVIDING THE PULSES INTO GROUPS ACCORDING TO PULSE HEIGHT, SEPARATELY DERIVING DIRECT-CURRENT SIGNALS PROPORTIONAL TO THE RATE OF OCCURRENCE OF PULSES IN EACH GROUP, AND SEPARATELY RECORDING THE DERIVED SIGNALS IN CORRELATION WITH THE DEPTH IN THE WELL AT WHICH DETECTION OCCURRED WHEREBY COMPARISONS OF THE RECORDS ARE INDICATIVE OF THE NATURE OF THE FORMATIONS.

Claim 2

A METHOD OF RADIOACTIVITY WELL LOGGING THAT COMPRISES THE STEPS OF TRAVERSING THE FORMATIONS PENETRATED BY A WELL WITH A SOURCE OF NEUTRONS TO THEREBY IRRADIATE THE FORMATIONS WITH NEUTRONS, SIMULTANEOUSLY AND BY THE SAME TRAVERSING STEP SEPARATELY DETECTING AT A FIRST POINT SPACED FROM SAID SOURCE GAMMA RADIATION RESULTING FROM NEUTRON CAPTURE IN THE FORMATIONS WITHOUT DETECTING GAMMA RADIATION RESULTING FROM THE INELASTIC SCATTERING OF NEUTRONS IN THE FORMATIONS BY PRODUCING PROPORTIONALLY RELATED ELECTRICAL PULSES, SIMULTANEOUSLY AND BY THE SAME TRAVERSING STEP SEPARATELY DETECTING AT A SECOND POINT NEARER SAID SOURCE THAN SAID FIRST POINT GAMMA RADIATION INCLUDING GAMMA RADIATION RESULTING FROM THE INELASTIC SCATTERING OF NEUTRONS IN THE FORMATIONS BY PRODUCING PROPORTIONALLY RELATED ELECTRICAL PULSES, SEPARATELY TRANSMITTING THE ELECTRICAL PULSES TO THE SURFACE OF THE EARTH, SEPARATELY DIVIDING THE PULSES INTO GROUPS ACCORDING TO PULSE HEIGHT, SEPARATELY DERIVING DIRECT-CURRENT SIGNALS PROPORTIONAL TO THE RATE OF OCCURRENCE OF PULSES IN EACH GROUP, AND SEPARATELY RECORDING THE DERIVED SIGNALS IN CORRELATION WITH THE DEPTH IN THE WELL AT WHICH DETECTION OCCURRED WHEREBY COMPARISONS OF THE RECORDS ARE INDICATIVE OF THE NATURE OF THE FORMATIONS.