dual spaced focused resistivity


The QL40 DLL3 tool provides a time multiplex dual spacing focused resistivity measurement with two different depths of investigation, Shallow LL3-S and Deep LL3-D resistivity in Ohm.m. 

It is characterised by an excellent vertical resolution in comparison with the traditional Normal Resistivity tool that makes it ideal for bed-boundary and thickness analysis. The QL40 DLL3 can be operated as a stand-alone probe with an  Isolation bridle and bottom plug or can be stacked with other tool subs. The QL40 DLL3 is compatible with Matrix, ALT logger and Scout acquisition systems.

Temperature – Pressure

70°C (158°F)
200 bar (2900 psi)

Diameter – Length

43 mm (1.7”) w/ neoprene insulator
2.75 m (108,2”)


14 kg (30.9 lbs)


Time Multiplex dual spacing focused resistivity LL3-S & LL3-D in [Ohm.m]

Potential value on measuring and guard electrodes in [V]

Current value on measuring and guard electrodes in [mA]


Isolation bridles
QL40 IS 1 (mono-MS1)
QL40 IS 2 (mono-GO1)
QL40 IS 4 (4 conductor-GO4)
Calibration box


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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