Dictionary:Laterolog

FIG. L-3. Laterolog. (a) Schematic of laterolog-7 showing current flow lines. (b) Laterolog plotted on hybrid scale. (Courtesy Schlumberger.) (c) The array laterolog records the response to an unfocused current at many receivers and determines resistivities in processing. (Courtesy Kurt Strack.)

(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 M₁^ʹ, M₁, M₂, and M₂^ʹ 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.

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