This is a log of measurements along a well bore (a well-log). The acronym RAAH is a unique identifier to recognize this particular log and can be encountered in your log evaluation software or your corporate datastores. The code stands for 'Resistivity Attenuation Compensated Apparent Long 2MHz'. Usage of this log is not high and encountering it is a rare occasion.

This log displays readings of the formation resistivity as measured by the attenuation of a high frequency (hundreds of KHz to several MHz) electromagnetic wave; these measurements are typically deeper than measurements based on phase shift, but their vertical resolution is less sharp and they often cannot be used reliably in high-resistivity formations. In general this log therefore displays units of the electromagnetic propagation resistivity. This can be explained as being the formation resistivity as measured by the attenuation or phase shift of a high frequency electromagnetic wave; the frequency range for these measurements is higher than that of induction measurements, typically hundreds of KHz to several MHz, and over 1 GHz in the case of the Schlumberger EPT tool.

This log usually has the unit 'Resistivity'. This is the property of a material which resists the flow of electrical current. The ratio of electric-field intensity to current density. The reciprocal of conductivity.

Data for this log is produced by a tool that uses a electromagnetic logging technique and can be used to investigate the resistivity of the formation. Similar logs are listed below:

• Resistivity Phase Difference Borehole Corrected (RPC)
• Resistivity Phase Difference Apparent (RPA)
• Resistivity Attenuation Apparent (RAA)
• Compensated Phase Shift Resistivity (PSR)
• Electromagnetic Propagation Resistivity (EPR)
• Resistivity Attenuation Borehole Corrected (RAC)
• CDR Attenuation Resistivity (ATR)