The Compensated Dual Resistivity tool (CDR) acquires measurements similar to those of the conventional wireline induction tool that measures formation conductivity. Using a 2-MHz electromagnetic wave, two receivers detect the phase shift (shallow measurement) and amplitude attenuation (deeper measurement) of the transmitted signal. Two pairs of transmitters and receivers are used for borehole compensation in washouts and irregular boreholes.

The resistivity phase shift (Rps) measurement is equivalent to the spherically focused log (SFL) on the induction tool. The average depth of investigation of the (Rps) is 75 cm. The resistivity attenuation deep (Rad) measurement is equivalent to the dual-induction medium measurement, with an average depth of investigation of 125 cm. The highest vertical resolution of these measurements is 15 cm.

A natural gamma-ray tool is integrated into the CDR tool. Under controlled penetration rates of approximately 15 n/hr, reliable spectral data may be obtained. Higher penetration rates will degrade the resolution of the spectral data, but will provide total gamma-ray counts similar to those recorded by the wireline tool.