1. n. [Formation Evaluation]

The resistive (R) signal, or that part of the alternating signal at the receiver of an induction-logging tool that is in phase with the transmitter current. This signal depends on the formation conductivity and is the main or, in older tools, the only source of the induction log. It must be separated from the out-of-phase, or reactive (X) signal, which depends in a different way on formation conductivity and may contain a large component from direct coupling between transmitter and receiver.

See: 6FF40,  skin effect