| 摘要 |
A source of fast neutrons and a detector responsive to the thermal neutron population decay rate are utilized in a well logging instrument. The instrument is placed within a sample retention chamber. The neutron generator is periodically pulsed and the neutron detector is gated on at intervals of 100-150, 150-200, and 800-850 microseconds, respectively, following the termination of each burst of fast neutrons. The detected radiations within these intervals are used to indicate the apparent absorption cross section of the small fluid sample within the chamber. The absorption cross section is measured for a number of small samples of known salinity and calculatable true absorption cross section. A relationship is constructed of the true absorption cross section of the samples versus the measured absorption cross sections of the samples. When the chamber is filled with an unknown fluid sample the measured absorption cross section is correlated with the reference curve which will yield single unique true absorption cross section substantially free of diffusion effects for the measured absorption cross section value of the unknown small quantity sample.
|
