What Is Guard Log

1. n. [Formation Evaluation] A measurement made by a type of electrode device in which the current flow and hence the measurement is focused in a disk that is concentric with and perpendicular to the sonde. The term usually refers to a Laterolog-3 device.

What is Laterlog?

(lat, ∂r ō’ log) A resistivity log generally used in salt muds, made with a sonde that is focused by use of guard or bucking electrodes which forced the ”surveying current” to flow nearly at right angles to the logging sonde. Also called guard log or focused log.

How does a resistivity tool work?

Resistivity logging is a method of well logging that works by characterizing the rock or sediment in a borehole by measuring its electrical resistivity. … In these logs, resistivity is measured using four electrical probes to eliminate the resistance of the contact leads.