Anordning og fremgangsmåte for måling av elektromagnetiske egenskaper ved en jordformasjon som penetreres av et borehull.

摘要

A resistivity logging tool suitable for downhole use includes a transmitter, two spaced apart receivers. The measured resistivities at the two receivers are corrected for differences in receiver characteristics based on measuring the responses of the receivers to a calibration signal passed through calibration circuits. The logging tool may be used in reservoir navigation. A calibration antenna positioned between the two receivers may be used to identify factors other than the distance to a bed boundary that may effect the receiver signals.