Radial Electrical Resistivity Measurements of Rocks on Laboratory Core Samples Using an Electromagnetic Sensor: Macro and Micro Eddy Currents

Rocks subjected to weak alternating magnetic fields exhibit a magnetic hysteresis phenomenon due to the magnetic susceptibility and chemical composition of ferromagnetic or ferrimagnetic mineral grains. In order to characterize the physical properties of rocks, magnetic susceptibility and electrical resistivity measurements have been carried out. So a device has been developed in our laboratory as a highly sensitive sensor to measure the magnetic and electrical properties of rocks. This work deals with a nondestructive method to analyze these properties. A ballistic method has been considered by using a search coil in a sensitive alternating current bridge. Usually, the use of the complex ac magnetic susceptibility is convenient to reach the bulk magnetic susceptibility, where the imaginary component is often very weak and neglected. In this paper, we have considered this to determine the electrical resistivity of rocks