Patent ID: 6998844

Claim:
A well logging system for determining from propagation measurements an anisotropy parameter of a subsurface formation, comprising: an elongated support having a longitudinal axis and adapted for subsurface disposal while drilling a borehole through said formation; a plurality of transmitter antennas disposed on the support, at least one of said antennas having its magnetic moment oriented at an angle with respect to the longitudinal axis, each of said antennas adapted to transmit electromagnetic energy, and at least two of the plurality of transmitter antennas do not have their magnetic moments oriented in a same direction; a pair of receiver antennas disposed on the support with their magnetic moments each oriented at an angle with respect to the longitudinal axis, said antennas adapted to detect electromagnetic signals associated with the energy transmitted from said transmitter antennas; wherein the magnetic moment of the at least one transmitter antenna or one of said receiver antennae is at a ninety-degree angle with respect to the longitudinal axis; and processor means adapted to combine detected electromagnetic signals associated with said transmitter or receiver antenna oriented at the ninety-degree angle with detected electromagnetic signals received from another antenna of said plurality of transmitter antennas to determine the anisotropy parameter, wherein the detected electromagnetic signals relate to a phase difference or a magnitude ratio.