WRRCTR No.80 Determining Porosity with Neutron Logs from Hawaiian Basaltic Aquifiers

Abstract

Neutron count data for calibration purposes were collected by neutron logging in 4 boreholes, and porosity data were determined from photo logs run on the same 4 boreholes. A neutron count-porosity calibration curve was constructed and was found to take the form of the logarithm of neutron count versus porosity. The calibration curve was calculated by linear regression analysis, utilizing empirical field data. The calibration curve is valid within the expressed 95 percent confidence intervals only for neutron logs from (1) basaltic formations, (2) uncased hole8, and (3) borehole diameters from 20.32 to 30.48 cm (8 to 12 in.).