Calibration of Neutron and Density Logs at the Nevada Test Site
Joseph R. Hearst
A new calibrator for neutron logs in large-diameter holes has been built at the Nevada Test Site. It consists of two cylinders, each made of six wedge-shaped cells. The outside diameter of each cylinder is 4.8 m, and the inside diameter is 2.4 m; the hight is 2.3 m. The cells were filled with mixtures of hydrated alumina, tabular alumina, sand, and water to achieve a large range of bulk density and hydrogen index. A new calibration algorithm, using three-dimensional interpolation in hydrogen index-gap-density space has been developed to determine hydrogen index from log data. There is evidence that the new algorithm is slightly more accurate than the previous algorithm.
Density-log calibrators have not been changed in many years, but a
new algorithm, developed in 1993, appears to be more satisfactory than
the one used routinely in the past.
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