This is an acronym for a well log used in the oil and gas industry. The acronym
TNPB is a unique identifier to recognize this particular log and can be encountered in your log evaluation software or your corporate datastores. The official name for this log is
'Thermal Neutron Porosity, Bottom'. This log is not often acquired after (or during) drilling a well. This log can be used to evaluate the porosity as measured with a thermal neutron logging device.
Simply said, this is a log that describes the porosity as measured with an neutron logging device. At a higher level, this can be seen as a measure of the apparent porosity. Better said, 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.
Furthermore, this can be explained by looking at the volume fraction. This can be explained as being 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: