Patent ID: 8035392
Filing Date: 2011-10-11
Classification: G01V

Abstract:
1. An apparatus for use in a borehole in an earth formation, comprising: a conducting tubular; at least one transmitter on said conducting tubular for propagating an electromagnetic field in the earth formation; at least one receiver on said conducting tubular for receiving a transient signal resulting from interaction of said electromagnetic field with said earth formation; each of said at least one transmitter and said at least one receiver having a separate localized magnetostatic shielded region associated therewith; each of said at least one transmitter and said at least one receiver having a separate localized electromagnetic shielded region associated therewith; and processing circuitry for determining a bucking coefficient and for determining from said transient signal and said bucking coefficient a resistivity measurement of said earth formation, wherein said bucking coefficient K(t) is computed according to where C