(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. One type used three electrodes plus guard electrodes.
In the laterolog-7, sufficient current was fed into the bucking electrodes A1 and A2 so that the current from electrode A flowed nearly at right angles to the sonde (cross-hatched area in Figure L-3). Sensing electrodes M1ʹ, M1, M2, and M2ʹ were used to adjust the bucking-electrode currents until this flow condition existed. The dual laterolog measured resistivity at different depths of penetration.
The array laterolog determines resistivities by processing the data from an array of detectors rather than by focusing the current.
Laterolog is a Schlumberger trade name.