UK T. (+44) 1492 582 323

Americas T. +1 (559) 456-1711

Asia T. (+852) 6503 3486

Sidewall Density, Density/Guard and Iron-ore Density

The sidewall density gamma probe uses dual shielded detectors to provide a borehole- compensated density measurement with good bed-boundary resolution. The sidewall-density/ guard probe offers an additional LL3 focussed electrical measurement with good vertical resolution and depth of investigation.

The iron-ore density probe includes extra collimation, different source-detector spacings and a higher activity source to extend the density range to 5g/cc for iron-ore logging.

Principle of Measurement:

The probes contain a detachable 137Cs gamma source and two scintillation gamma detectors. The active windows of the source and detectors are maintained in contact with the borehole wall by a motorised caliper arm. Gamma radiation back-scattered by the formation (Compton effect) reaches the detectors where the relative count rates provide a measure of formation density.


  • Compensated density output in engineering units (g/cc)
  • Short-spacing detector for high vertical resolution
  • Tungsten shielding reduces borehole effects
  • Standard calibration blocks for field or base use


  • Bulk density
  • High-resolution density (HRD)
  • Natural gamma
  • Caliper
  • Options:  Guard resistivity, Bed-resolution density (BRD), Temperature



  • Density and porosity
  • Lithology
  • Bed thickness and boundary location
    Coal ash and moisture content


  • Rock strength and elasticity parameters (with sonic log)
  • Detection of weathered or fractured zones


  • Location of aquifer and aquitard
  • Detection of cavities and missing cement


Diameter: 50mm
Weight: 20kg
Temperature: 0-70⁰C (extended ranges available)
Max. pressure: 20MPa
Density range: 1.1 to 2.95g/cc
(sidewall density and density/guard probes)
1.5 to 5.0g/cc (iron-ore density probe)
Caliper range: 50mm to 300mm
Resistivity range: 1 – 2,000 ohm-m

Operating Conditions

  • Borehole type: open-hole, water-filled

Sales Information

I002013 Sidewall density probe
I002016 – includes BRD and temperature
I014720 Sidewall density guard probe with BRD
I018309 Iron-ore density probe

Download Sidewall Density, Density/Guard and Iron-ore Density sheet


...Practical Innovation with Global Service & Support...

Robertson Geologging Ltd., 2017

how can we help you?

(+44) 1492 582 323