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Borehole Geophysical Surveys / +44 (0)1939 210 710

Caliper Tools

These tools measure the mean diameter of boreholes. They are used to check the integrity of borehole linings, and where a borehole is unlined to identify zones of washout, breakout or fissures.

For narrower boreholes (<400mm) the 2 or 3 arm calipers give greater resolution than a 4 arm caliper.


2 or 3 Arm Caliper
4 Arm Caliper
Tool size 1150 x 38 mm 1180 x 80 mm
Tool weight 6kg 18kg
Range 50 – 600mm 100 – 1500mm
Max Temperature 80˚C 80˚C
Max. Pressure 20MPa 20MPa

Logging Conditions

  • 2 – 9 m / min
  • Free running

Borehole Conditions

  • Dry or fluid filled
  • Unlined or lined
Example caliper log showing fractures in sandstone seen in the optical image