Borehole Geometry

The 4-Arm Dipmeter measures microresistivity and tool orientation data.

These can be processed to determine formation dips.

Principle of Measurement:

The probe consists of a microresistivity section and a detachable verticality module. Microresistivity data is acquired by four highresolution, button electrodes mounted on motorised XY caliper arms and maintained in contact with the borehole walls. A planar formation feature that does not lie perpendicular to the borehole axis is detected by each electrode at a different apparent depth.

The four microresistivity measurements are correlated and combined with the verticality data to calculate the dip and dip direction.

Specification : 


Small diameter for slim-hole operations

Operates in all orientations


Formation dip and azimuth


Borehole verticality and drift

True vertical depth

Borehole volume

Natural Gamma





Identification of faults and folding

Fracture identification

Correlation between wells

Operating Conditions

Borehole type  :  open, water-filled

Centralisation  :  non-magnetic centralisers required for inclined

boreholes and/or diameters above 150mm

Recommended Logging Speed  :  3m/min


Diameter  :  61mm (when closed 66mm)

Length  :  5.17m

Weight  :  52kg (combined)

Temperature  :  0-70⁰C (extended ranges available)

Max. pressure  :  20MPa

Resistivity range  :  1 to 10,000 ohm-m

Borehole inclination  :  any

Caliper range  :  62-380mm

Part Numbers

I002171    4-Arm Dipmeter probe with natural gamma