Natural Gamma & Casing Collar Locator


The QL40-GR-CCL is a combination of a natural gamma ray (GR) assembly and casing collar locator (CCL). The natural gamma ray (GR) module measures the amount of gamma radiations occurring naturally within the formations crossed by a borehole.  A scintillation Sodium Iodide crystal is used to detect the gamma rays.  Gamma rays are produced mainly by isotopes of potassium, thorium, uranium and their decay products. The gamma ray log is widely used in the mining and groundwater industry for the identification of lithology, correlation between boreholes and clay content analyses.

The casing collar locator (CCL) is a magnetic device sensitive to changes of metal thickness at casing or tubing collar. It is always run in steel cased boreholes to detect the position of casing collars. It is mainly used for depth control and depth correlation.

The QL40-GR-CCL is supplied as a stackable sub of the Quick Link (QL) product line or it can be run as a standalone tool.

Gamma Sensor: NaI(Tl) Crystal 2.22 cm x 7.62 cm (0.875 x 3.0 in.)
CCL Sensor: 32 x 280 mm Coil & Magnets Assembly


GR: NaI (Tl) crystal ( 1 x 3”)
CCL: 32 x 280 mm coils & magnets assembly

Temperature – Pressure

0-70°C (32-158°F)
200 bar (2900 psi)

Diameter – Length

40 mm (1.6”) – 1.16 m (46”)


6 kg (13 lbs)


Total gamma counts in CPS and/or API unit

CCL in mV


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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