Patent ID: 7723991
Filing Date: 2010-05-25
Classification: G01V

Abstract:
1. An apparatus for evaluating an earth formation, the apparatus comprising: (a) a logging tool configured to be conveyed into a borehole; (b) a first sensor arrangement on the logging tool configured to produce first measurements responsive to a propagating electromagnetic wave indicative of a resistivity property of the earth formation at a first plurality of rotational positions of the logging tool during continued rotation of the tool; (c) a second sensor arrangement on the logging tool, the second sensor arrangement including two axially oriented receiver antennas having axes on a single side of a longitudinal axis of the logging tool and two axially oriented transmitter antennas symmetrically disposed about the two axially oriented receiver antennas, the second sensor arrangement configured to produce second measurements responsive to a propagating electromagnetic wave indicative of the resistivity property of the earth formation having a depth of investigation greater than a depth of investigation than that of the first measurements at a second plurality of rotational positions; (d) a processor configured to: