Skip to main content
Borehole Geophysical Surveys / +44 (0)1939 210 710

Formation Density Tool – Grout

The Formation Density Tool has three collimated detectors at different spacings from a source of gamma radiation. The collimated tool and sidewalled running minimise the effects of diameter variations and fluid type.

The logs from each detector indicate the apparent density of the formation within a radius of investigation related to the spacings. The Long Spaced Density has a spacing of 48cm, the High Resolution Density has a spacing of 24cm and the Bed Resolution Density has a spacing of 14cm.

The Bed Resolution Density (BRD) log has high resolution but very shallow penetration (2 – 3cm) and is very responsive to formation changes, diameter variations and borehole construction. The High Resolution Density (HRD) has a greater penetration than the BRD, up to around 10cms in medium density formations.


  • Size:
    1890 x 66mm
  • Weight:
  • Max. temperature:
  • Max. pressure:

Logging Conditions

  • 2 – 5 m / min
  • Side-walled

Borehole Conditions

  • 80 – 300mm
  • Fluid filled or dry*
  • Unlined or lined*
*In dry or lined sections of boreholes, these logs give qualitative information on the density of the material surrounding the tool, the logs are expressed in terms of apparent density in g.cm³.
Formation density log correlating with a natural gamma log. Note higher resolution in BRD log detecting thin beds.