multipoint Resistivity


(8’’, 16’’,32’’, 64’’, SP & SPR)

This digital probe measures simultaneously 8, 16, 32 and 64 inch normal resistivity, single point resistance (SPR) and spontaneous potential (SP). Using one injection electrode and four sense electrodes users can log resistivity profiles with different depths of investigation and gain information about permeability, porosity, water quality and geological formation properties.

Four resistivity measurements are recorded compared to two offered by most other manufacturers.

The QL40 ELOG is an in line sub. It can be combined with other logging tools of the QL (Quick Link) product line or operated as a standalone tool. It is possible to extend the application of the QL40 ELOG to a QL40 IP induced polarization probe through a simple firmware upgrade. The QL40 IP configuration allows to record in addition the chargeability of the formations.

Temperature – Pressure

0 -70°C (32-158°F)
200 bar (2900 psi)

Diameter – Length

43 mm (1.7”)
1.9 m (75”)


9 kg (19.8 lbs)


8”, 16”, 32” and 64” Normal Resistivity in [Ohm-m]

SP in [mV]

SPR in [Ohm]


QL40 IS 1
QL40 IS 2
QL40 IS 4


Manufactured by Geotomographie GmbH

Technical Details

Generated wave types: SV
Signal frequencies: Up to 500 Hz (depending on geology and borehole distance)
Operational depth: Up to 100 m
Source length: 1015 mm
Source weight: 6 kg
Cable weight per metre: 377 g
Borehole diameter: 75-100 mm (or larger if spacers are used)
Clamping system: Infatable bladder
Depth indicator: Cable marking every 2 m
Connector: To impulse generator IPG800 or IPG5000
Storage: On drum
Switch box: Switch between two vertical shot directions

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