Method and apparatus for well logging using an accelerator neutron source.

摘要

A method of determining a characteristic comprising irradiating the formation with high energy neutrons and detecting neutrons scattered by the formation having energies above epithermal to determine the nature of the formation matrix. Epithermal neutrons can also be detected to determine formation porosity. Apparatus comprises a high energy neutron source, typically a D-T accelerator (32) producing 14 MeV neutrons, and detectors (34, 38) comprising <4>He filled proportional counters far detecting neutrons having energies above epithermal and <3>He filled proportional counters (37) for detecting epithermal neutrons. <IMAGE>