This is the name of a log measured along a well bore (a well-log). The acronym
PPORC can be found in any (ASCII) log files provided by the logging company. The acronym stands for
'MRIL partial porosities'. The business value of this log is often deamed high. Use this log to investigate 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. At a more general level these values are measures of the apparent porosity. This is a measure of 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.
Simply said, this is a log that describes the pore volume per unit gross volume. Porosity is determined from measurements on cores or interpreted from logs.
Furthermore, this can be explained by looking at 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.
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: