Introduction

DETERMINING POROSITY WITH NEUTRON LOGS FROM HAWAIIAN BASALTIC AQUIFERS

DETERMINING POROSITY WITH NEUTRON LOGS FROM HAWAIIAN BASALTIC AQUIFERS

Technical Report No. 80
DETERMINING POROSITY WITH NEUTRON LOGS FROM HAWAIIAN BASALTIC AQUIFERS

Frarik I. Peterson, Man Mohan Sehgal
August 1974

ABSTRACT
Neutron count data for calibration purposes were collected by neutron logging in 4 boreholes, and porosity data were determined from photologs 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 holes, and (3) borehole diameters from 20.32 to 30.48 cm (8 to 12 in.).