This is a well log used in the oil and gas industry. You could find this abbreviation
MPHEB in your log evaluation software or any (ASCII) log files provided by the logging company. The official name for this log is
'Array of partial porosities from second process'. The usage of this log is well established. The values of this log represent the contribution of porosity from a given "bin" (with certain characteristics) to the total porosity; e.g., in nuclear magnetic resonance data processing, the "bins" typically correspond to different pore size ranges.
Furthermore, this can be explained by looking at 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 is a measurement of the volume fraction. This is a measure of 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 nmr logging technique and can be used to investigate the porosity of the formation. Similar logs are listed below: