123 6. Borehole electrical panels:an experiment Acquisition The five electrical resistivity panels produced are shown as apparent resistivities in Figure 4. According to the porous levels identified by Mari and Porel (2008): • the 30-meter depth level could not be studied, as electrical measurements in the boreholes only started at best at 35 meters for panels M04 and M20; • the 50-meter depth level was studied for panels M04 and M20; • the 85-meter depth level is covered by all five vertical panels; • finally, the 115-meter depth level is covered by all panels except M04, which ends at 105 meters. Figure 5 presents a comparison between electrical resistivity measurements obtained from long normal logs (Chapellier, 2001b) and those from the electrical panels. In the electrical panels, the apparent resistivity of the limestones is generally above 180 ohm·m down to approximately 110 meters. An exception is observed in panel Figure 4 Vertical resistivity panels measured from boreholes M20, M04, M07, M11, and M08. Dotted boxes indicate the location of karstic levels.
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