Patent ID: 6714014
Filing Date: 2004-03-30
Classification: E21B,G01V

Abstract:
An apparatus conveyed in a borehole for obtaining a resistivity parameter of an earth formation penetrated by the borehole, the apparatus comprising:(a) at least one measure electrode at a first electrical potential and in electrical contact with a fluid in the borehole, said at least one measure electrode operatively connected to a source of a modulated electrical current and conveying a measure current into the formation; (b) at least one focusing electrode at a second potential in proximity to said at least one measure electrode for focusing the measure currents into the formation, said second potential having a magnitude greater than the magnitude of the first potential; (c) at least one pad carrying said at least one measure electrode and said at least one focusing electrode, said at least one pad at a third electrical potential substantially equal to the first potential for maintaining the focusing of the measure currents in the formation.