Patent ID: 8234071

Claim:
An apparatus for estimating a property of a formation penetrated by a borehole, the apparatus comprising: a carrier configured to be conveyed through the borehole; a first electrode disposed at the carrier; a second electrode disposed at the carrier, the first electrode and the second electrode being configured to couple to a characteristic impedance of a material disposed in the borehole; a third electrode disposed at the carrier, the first electrode and the third electrode being configured to electrically couple to a characteristic impedance of the formation; a circuit element coupled to the first electrode and to the second electrode and having a characteristic impedance; a first sensing circuit coupled to the circuit element and configured to provide a first signal related to the impedance of the borehole material; and a second sensing circuit coupled to the first electrode and the third electrode and configured to provide a second signal related to the characteristic impedance of the formation; wherein the first signal and the second signal are used to estimate the property.