| 摘要 |
The invention relates to a method of determining the resistivity of a geological formation through which a metal-cased borehole passes, by means of at least three electrodes in contact with the casing and spaced apart in the longitudinal direction of the borehole. In order to eliminate the effect of any differences between the two sections of casing delimited by the electrodes, a circuit connected to the electrodes and forming a Wheatstone bridge is balanced, with said sections of casing constituting two of the resistances in said Wheatstone bridge circuit. <IMAGE> |
