MAGNETIC HEAD FOR CONDUCTIVITY IMAGING FOR USE IN BOREHOLES

摘要

A sensor for performing micro-conductivity measurements during well logging measurements in a borehole includes a magnetic core having a conductive insert wherein windings are driven with alternating current. Some embodiments include a sensor further having a conductive case. Various aspects of the sensor, such as dimensions and conductive properties of fabrication materials are selected to maximize performance of the sensor. Methods for using the sensor call for, among other things, placing the sensor in a well logging tool, and placing the tool in a well bore. A substantial focusing of the magnetic field on the wall of the borehole is achieved and provides for high quality data.