Patent ID: 6630831
Filing Date: 2003-10-07
Classification: G01V

Abstract:
The method of focusing or lensing an oscillating magnetic flux to measure the electrical resistivity of media within a geologic formation surrounding a cased well bore comprising the steps of:(1) generating at least one magnetic flux proximate to a non-magnetically permeable section of a casing; (2) oscillating the magnetic flux at least at one frequency suitable to pass through the segment of the well casing for entering a surrounding geological formation such that the flux engages with electrically conductive media contained within the surrounding formation to create eddy currents within the media; (3) inducing a separate oscillating magnetic flux created by the eddy currents in the electrically conductive media within the formation such that a field of the induced magnetic flux extends back to the well casing; (4) receiving, from within the casing, the induced magnetic flux of the geologic formation; (5) converting the induced flux into electrical signals that are filtered and processed; (6) determining the electrical resistivity of the media located in the geologic formation proximate to the well casing based on the electrical signals; and (7) determining the characteristics of the media located in the geologic formation proximate to the well casing by evaluating the electrical resistivity.