ASTM International

Standard Guide for Conducting Borehole Geophysical Logging-Neutron
 N D6727/D6727M

Annotation

This guide is focused on the general procedures necessary to conduct neutron or neutron porosity (hereafter referred to as neutron) logging of boreholes, wells, access tubes, caissons, or shafts (hereafter referred to as boreholes) as commonly applied to geologic, engineering, groundwater and environmental (hereafter referred to as geotechnical) explorations. Neutron soil moisture measurements made using neutron moisture gauges, are excluded. Neutron logging for minerals or petroleum applications is excluded, along with neutron activation logs where gamma spectral detectors are used to characterize the induced gamma activity of minerals exposed to neutron radiation.

This guide defines a neutron log as a record of the rate at which thermal and epithermal neutrons are scattered back to one or more detectors located on a probe adjacent to a neutron source.

Induction logs are treated quantitatively and should be interpreted with other logs and data whenever possible.

Neutron logs are commonly used to: (1) delineate lithology, and (2) indicate the water-filled porosity of formations.

This guide is restricted to neutron logging with nuclear counters consisting of scintillation detectors (crystals coupled with photomultiplier tubes), or to He3-tube detectors with or without Cd foil covers or coatings to exclude thermalized neutrons.

This guide provides an overview of neutron logging including:(1) general procedures; (2) specific documentation; (3) calibration and standardization, and(4) log quality and interpretation.

To obtain additional information on neutron logs see References section in this guide.