This probe provides a classic triple-spacing sidewall focussed formation density
measurement, with the additional advantage of a incorporating a photo-electric
effect energy detection window on the medium-spacing detector.
The photoelectric effect (Pe) measurement is a reliable indication of the
apparent formation atomic number, meaning that formation lithology and an
accurate porosity can often be deduced directly from the results given by the
probe. When the Pe log results are combined with those obtained from other
probes (eg. spectral gamma) a considerable number of specific « heavy » minerals
can be identified.
A gamma ray source (Cs137, typically 3.7 GBq), is fixed to the lower extremity
of the probe during logging. The source capsule itself is supplied separately
by a specialist partner.
The mechanical side-walling arm provides a caliper measurement, useful for
diameter correction purposes and mud-cake evaluation, and a natural gamma log
is also obtained by means of a scintillation detector located in the uppermost
part of the probe body.
Lim designs, produces and commercializes measuring instruments and solutions dedicated to drilling.