Formation hydrogen content logging with fast neutron and scintillation detector

Claim 1

APPARATUS FOR CONDUCTING A RADIOACTIVITY WELL LOG OF THE FORMATIONS TRAVERSED BY A BORE HOLE THROUGH THE EARTH COMPRISING AN ELONGATED INSTRUMENT ADAPTED TO BE PASSED THROUGH A BORE HOLE, SAID INSTRUMENT INCLUDING A SOURCE OF FAST NEUTRONS FOR IRRADIATING THE FORMATIONS ALONG THE TRAVERSE OF THE BORE HOLE AND A DETECTOR OF FAST NEUTRONS RESULTING FROM IRRADIATION OF ADJACENT EARTH FORMATION BY NEUTRONS FROM SAID SOURCE, SAID SOURCE AND DETECTOR BEING SPACED A PREDETERMINED DISTANCE FROM ONE ANOTHER ALONG THE LONGITUDINAL AXIS OF SAID INSTRUMENT, SAID PREDETERMINED DISTANCE BEING THAT DISTANCE AT WHICH THE FAST NEUTRON FLUX REACHING THE DETECTOR AS A RESULT OF SAID SOURCE IS LEAST AFFECTED BY THE POSITION OF THE INSTRUMENT IN THE BORE HOLE AND BEING SUCH THAT THE FAST NEUTRON FLUX REACHING THE DECTOR IN RESPONSE TO MOVEMENT OF THE INSTRUMENT AWAY FROM THE SIDE OF THE BORE HOLE INCREASES AT LONGER SOURCE-TO-DETECTOR SPACINGS DUE TO INCRESED SCATTERING BY BORE HOLE FLUID BETWEEN THE DETECTOR AND THE SIDE OF THE BORE HOLE AND DECREASES AT SHORTER SOURCE-TO-DETECTOR SPACINGS DUE TO INCREASED SCATTERING IN THE FORWARD DIRECTION AWAY FROM THE DETECTOR.