Abstract: A method for signal communication between a well drilling instrument and the Earths surface includes generating an electromagnetic field in an instrument disposed in drill string used to drill a wellbore. The electromagnetic field includes encoded measurements from at least one sensor associated with the instrument. A signal corresponding to an amplitude and/or phase of the electromagnetic field is measured between the drill string and a surface electrode when the drill string is substantially electrically isolated from a well casing. A signal corresponding to the amplitude and/or phase is measured between the casing and a surface electrode when the casing and the drill string are in electrical contact with each other.

Abstract: A saver sub includes a hollow, tubular body having an upper portion and a lower portion. The upper portion is coupled to a kelly or a top drive, and the lower portion is coupled to a drill string. An insulation layer is positioned between the upper portion and the lower portion.

Abstract: An EMI-Seismic logging tool for use in a subterranean formation penetrated by a well bore, wherein the system makes electromagnetic and seismic measurements simultaneously using an EM receiver array for both measurements. A method of simultaneously making electromagnetic and seismic measurements in a subterranean formation is also provided.