Formation Density Sonde


The QL40 DEN measures the density in g/cc of the formation crossed by a borehole.

Density is a typical property of minerals, fluids and rocks. Density measurement is often used in geophysics, petrophysics, sedimentology and geotechnics. The technique requires a 137Cs or 60Co radioactive source attached at the bottom of the tool to excite the formation with gamma radiation. In addition the QL40 DEN is implementing a single arm caliper used to record a continuous  diameter log and to push the gamma detectors against the borehole wall while measuring the density.

The QL40-DEN is supplied as a bottom sub. It can be combined with other logging tools of the QL40 (Quick Link) product line or can be operated as a standalone tool. It is compatible with Matrix, Scout and ALTlogger acquisition systems.


CSI (Tl) crystals
SSD (20cm) and
LSD (35cm)

Temperature – Pressure

0-70°C (32-158°F)
200 bar (2900 psi)

Diameter – Length

50.8 mm (2”) – 1.85 m (73”)


19.2 kg (42 lbs)


SSD : in CPS

LSD : in CPS

SSD density : in g/cc

LSD density : in g/cc

Compensated density : in g/cc

Caliper : in mm or inch

PE option


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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