Patent ID: 8129993

Claim:
A method to determine an electromagnetic coupling tensor of a formation traversed by a borehole, comprising: disposing a tool in the borehole, wherein at least a portion of the formation traversed by the borehole has substantially parallel boundaries, and further wherein the tool includes a first transmitter having a first transmitter dipole moment at an angle θ T1 with respect to a longitudinal axis of the tool, a second transmitter having a second transmitter dipole moment at an angle θ T2 with respect to the longitudinal axis of the tool, and a receiver having a receiver dipole moment at an angle θ R with respect to the longitudinal axis of the tool, the first transmitter and the receiver constituting a first transmitter-receiver pair, and the second transmitter and the receiver constituting a second transmitter-receiver pair; transmitting an electromagnetic signal from the first transmitter and/or second transmitter while rotating the tool; receiving the electromagnetic signal to produce measured signals from the first transmitter-receiver pair and the second transmitter-receiver pair; measuring an azimuth angle of tool rotation; and determining the electromagnetic coupling tensor for the portion of the formation having substantially parallel boundaries based on the measured signals from the first and second transmitter-receiver pairs.