This is a log of measurements along a well bore (a well-log). You could find this abbreviation SNSF
in your log evaluation software or any (ASCII) log files provided by the logging company. The full name for this log used in the industry is 'Smoothed Near Detector ONLY Porosity (Sandstone Matrix-Fixed Hole Size)'
. Usage of this log is not high and encountering it is a rare occasion. This log displays readings of the porosity derived from a neutron logging measurement, assuming that the rock matrix material is quartz.
Concluding, this is a measure of the porosity as measured with an neutron logging device. At a higher level, this can be seen as a measure of the apparent porosity. In other words, the initial estimate of porosity, normally from logs, not corrected for the (often large) effects of clays, gas, etc. Such estimates should only be used for qualitative interpretation of clean, gas-free intervals.
In general this log thus reflects units of the volume fraction. Better said, the ratio of the volumes occupied by two components, or by one component to the total volume of the system.This log usually has the unit 'Porosity'
. This is the pore volume per unit gross volume. Porosity is determined from measurements on cores or interpreted from logs.
Data for this log is produced by a tool that uses a neutron logging technique and can be used to investigate the porosity of the formation. Similar logs are listed below: