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The micro-resistivity module provides a high- vertical-resolution micro-focused resistivity measurement within the flushed zone. The measurement electrodes are mounted on a flexible pad which is maintained in contact with the borehole wall by a motor-driven back-up/ caliper arm. The measurement pad is interchangeable to give a either micro-focused resistivity or micro-normal/ micro-lateral electrode geometries. The tool is stackable with all other RG slim oilfield probes. When combined with the dual laterolog it replaces the lower guard electrode.

Principle of measurement:

Micro-focused resistivity

A central current-injection electrode is surrounded by 3 concentric ring electrodes in a circular LL-7 configuration. The measure current is focused into a narrow beam which penetrates the mud-cake to give a resistivity measurement in the flushed zone (Rxo) beyond.

Micro-normal/ micro-lateral

Three in-line button electrodes, 1” apart, are configured to provide simultaneous 2” micro- normal and 1.5” micro-lateral measurements. Separation of the two measurement values due to their different depths of investigation gives an indication of mud-cake thickness.


  • High-vertical-resolution resistivity
  • Robust back-up arm ensures good pad contact
  • Pad interchangeable in field
  • Fully stackable with other RG oilfield probes


  • Resistivity of invaded zone (Rxo)
  • Borehole diameter


  • Determination of moveable hydrocarbons
  • Correction of Rt for invasion
  • Indication of permeability
  • Precise location of bed boundaries


Diameter (over pad): 97mm (3.9”)
Length: 3.53m (139”)
Weight: 56kg (123lb)
Max. temperature: 125°C
Max. pressure: 86MPa (12,500psi)
Range: 0.2 – 2000ohm-m
(micro-focused resistivity)
Caliper range: 96mm (3.9”) – 400mm (12”)

Operating Conditions

Borehole type:  4” to 12” open hole

Sales Information

I015642 Micro-resistivity probe
I015644 Spare micro-focused resistivity pad
I015646 Spare micro-normal/ micro-lateral pad

Download Micro-Resistivity sheet


...Practical Innovation with Global Service & Support...

Robertson Geologging Ltd., 2017

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