top of page

4AC60 : Four-arm caliper probe

The 4AC60 borehole geometry probe incorporates two pairs of caliper arms giving independent, perpendicular X-Y diameter measurements, while a magnetometer/accelerometer orientation system provides the borehole azimuth, inclination and X-Y arm directions.


In a non-circular borehole, because of differing spring tensions in the two pairs of arms, the tool will rotate in the borehole until the X-Y directions coincide with the maximum and minimum diameter axes.


Where a borehole becomes ovalised or develops breakout-type features, it can provide information on stress magnitudes and directions within the geological formations.


As an option, the probe can be supplied with a natural gamma detector to provide additional lithological information or for horizon correlation purposes.

Contact us to get a quote or request more information.

4AC probe



Technical specifications

✓ Diameter : 60 mm

Length : 3100 mm

Weight : 18 kg

 Max. temperature. : 70°C

max. Pressure: 200 bar

✓ Power: 70 to 100 Vdc


Data / sensor parameters

Diameter range: 60 to 450 mm

 Diameter resolution: 0.1 mm

Orientation sensor: triple magnetometers : accelerometers

 Measurement range: Full 360°inclin./ azimuth

  Orientation precision : +/- 0,1° inclination, +/-0,5° azimuth


Accessories & options

Natural Gamma detector: ø25x50 mm NaI(Tl) crystal

Non magnetic centralisers

 Calibration Jig 




Dry or fluid-filled borehole

✓ Open hole or PVC casing if azimuth required

 Steel casing if azimuth not required

bottom of page