The borehole-geometry probe consists of a four-arm caliper combined with a verticality measurement. The probe can replace the standard three-arm caliper with advantage where the borehole cross-section departs from circular and where directional information is required for well-completion studies and formation stress analysis.
Principle of Measurement:
The XY caliper provides continuous measurements of borehole diameter from two independent pairs of linked arms. The verticality section includes a triaxial magnetometer and three accelerometers. Data from these are combined by a downhole microprocessor to provide real-time, continuous logs of probe orientation and borehole inclination and direction.