The microresistivity probe provides a focussed pad resistivity measurement with high vertical resolution combined with a caliper and natural gamma.
Principle of Measurement:
The resistivity measurement is based on the guard principle where a ring electrode maintained at the same potential as the central measurement electrode focusses the measure current into a narrow beam. The electrodes are contained within a flexible pad mounted on a motor-driven arm and maintained in contact with the borehole wall during logging. The same arm also operates the caliper mechanism. A natural-gamma measurement is included to aid correlation with other logs.