RADIOACTIVITY WELL LOGGING SYSTEM HAVING A PAD MOUNTED NEUTRON SOURCE AND A CENTRALIZED RADIATION DETECTOR THAT PROVIDES COMPENSATION FOR BOREHOLE FLUID DENSITY AND BOREHOLE DIAMETER VARIATIONS

摘要

A well logging instrument adapted for traversing an earth borehole has a plurality of neutron sources mounted in pads which contact the wall of the earth borehole. The radiation detector is centralized in the borehole and the system provides compensation for natural gamma radiation and variations in borehole fluid density and borehole diameter.