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Density/Gamma Probe with Inclination

The trisonde offers a convenient alternative to the standard RG sidewall density probe whenever borehole diameter is restricted and qualitative density measurements are acceptable. One common application is in logging through drill pipe when unstable borehole conditions prevent use of unprotected nuclear probes. The probe is unfocussed and indicates the average density of material surrounding the borehole.

Principle of Measurement:

The probe contains a detachable gamma source and two high-sensitivity scintillation gamma detectors. Gamma radiation from the source is backscattered by the formation (Compton effect) and reaches the two detectors where the count-rates provide an indication of formation bulk density.


  • Long-spacing detector (LSD) for deep penetration
  • High-resolution detector (HRD) for accurate bed-boundary detection
  • Optional borehole-inclination measurement


  • Long-spacing density (cps)
  • High-resolution density (cps)
  • Natural gamma
  • Borehole inclination (option)


  • Minerals
  • Bulk-density variations
  • Lithology
  • Correlation with other logs
  • Bed thickness and boundary location
  • Borehole inclination and true vertical depth
  • Engineering
  • Detection of weathered or fractured zones
  • Ground compaction studies
  • Water
  • Location of aquifer and aquitard


Diameter: 38mm
Weight: 7.6kg
Temperature: 0-70⁰C (extended ranges available)
Max. pressure: 20MPa
Inclination range: 0 to 30°

Operating Conditions

  • Borehole type: all (qualitative measurement only)

Sales Information

I002010 Density-gamma probe
I002012 – with inclination

Download Density/Gamma Probe with Inclination sheet


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Robertson Geologging Ltd., 2017

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