Method and system for determining formation anisotropic resistivity with reduced borehole effects from tilted or transverse magnetic dipoles

A method for determining a property of a subsurface formation, with reduced borehole effects, from electromagnetic signal data associated with a transmitter antenna and obtained with a receiver antenna disposed within a borehole traversing said formation, comprising:

• a) determining the orientation of a magnetic dipole moment of said transmitter antenna using said signal data;
• b) determining the coupling, using said signal data, between said transmitter antenna and said receiver antenna having its magnetic dipole moment transverse or tilted with respect to the axis of said borehole with said transmitter dipole moment oriented substantially perpendicular with respect to the wall of the borehole;
• and
• c) using the coupling between said antennas to determine the formation property.

A well logging system including a well tool adapted for deployment through a borehole traversing an earth formation and an apparatus adapted for coupling to said well tool, the well tool including a transmitter antenna and a receiver antenna disposed thereon, the apparatus comprising:

• means for determining when a magnetic dipole moment of said transmitter antenna is oriented substantially perpendicular with respect to the wall of said borehole;
• means for determining the coupling between said transmitter antenna and said receiver antenna when said receiver has a mangetic dipole moment transverse or tilted with respect to the axis of said borehole with said transmitter dipole moment in said substantially perpendicular orientation;
• and
• means for determining a property of said formation using the determined coupling between said antennas.