The data acquisition software operates the electronic cards enabling
the injection of a DC between two electrodes (A and B) and the measurement
of potential difference between two electrodes. (M and N).
By using Ohm’s law average resistivity of the physical environment
is then measured around the piezometre between the 4 electrodes.
Repeating this process all along the shaft enables a global measurement of resistivity around the piezometre.
Then by using Waxman-Smits’ equation (3)
conductivity of the aquifer’s water can be deduced. This equation requires knowledge of the formation factor (F)
and of surface conductivity (Cs) which are determined at the time of the installation of the SMD by use of
gamma ray loggings for clay grounds, electrical resistivity and sonic P-wave velocity loggings for porosity.
Finally, an electrical conductivity profile of aquifer water around the piezometre,
normalized in temperature, adjusted by sink effect is carried out at regular intervals (4).