Design of New Combination Caliper Log Tool

The linkage arm and single caliper log tools have some disadvantages in higher inclined and horizontal well logging, such as loose contact between arm-pads and borewall, untrue caliper curves, etc. Based on the analyzes of the circuit in 3-arm caliper log tool, proposed is a design scheme of new caliper, namely, an unlinkage 4-arm caliper with 4 independent arms and providing 4 caliper curves that present the true borehole sizes. Data communication adopts PCM mode; the caliper can acquire 4 caliper curves or X-Y curves.