Abstract: Techniques for calibrating an electromagnetic logging tool equipped with a plurality of antennas, with at least one antenna having its axis at an angle with respect to a tool axis, include disposing a test loop about the tool such that an axis of the tool and a plane on which the test loop lies form a tilt angle that is between about 0 and 90 degrees. An induced signal is measured at one of the antennas by energizing another of the antennas. Embodiments analyze the induced signal corresponding to a max or min extrema associated with a coupling effect due to the test loop. In other embodiments a corrected signal is compared with a calculated signal.

Abstract: The invention refers to antenna configurations for electromagnetic logging tools. The antennas have one or more electrical conductors disposed on a dielectric substrate wrapped around a core or disposed directly on the core. The conductor or conductors are arranged such that the antenna has a first magnetic dipole moment substantially perpendicular to a longitudinal axis of the core. The invention also refers to antennas adapted for mutual balancing using interleaved conductive paths or disks to alter the magnetic dipole moments to mutually balance the antenna system.

Abstract: Shield apparatus are provided for use with logging instruments equipped with transverse magnetic dipole antennas. Flexible dielectric strips and dielectric cylindrical bodies are implemented with conductive elements in various patterns to form Faraday shield structures. The shields provide an extended conductive surface to the instrument support member and redirect axial currents along the borehole, protecting the underlying antennas from the undesired effects of these currents.

Abstract: Shield apparatus are provided for use with logging instruments equipped with transverse magnetic dipole antennas. Flexible dielectric strips and dielectric cylindrical bodies are implemented with conductive elements in various patterns to form Faraday shield structures. The shields provide an extended conductive surface to the instrument support member and redirect axial currents along the borehole, protecting the underlying antennas from the undesired effects of these currents.

Abstract: The invention refers to antenna configurations for electromagnetic logging tools. The antennas have one or more electrical conductors disposed on a dielectric substrate wrapped around a core or disposed directly on the core. The conductor or conductors are arranged such that the antenna has a first magnetic dipole moment substantially perpendicular to a longitudinal axis of the core. The invention also refers to antennas adapted for mutual balancing using interleaved conductive paths or disks to alter the magnetic dipole moments to mutually balance the antenna system.

Abstract: A shield apparatus for use in conjunction with a well tool to selectively attenuate one or more electromagnetic energy field components as the components interact with the shield. The shield composed of a flexible strip or conductive body and comprising at least one sloped slot or sloped conductive element therein. The shield being adapted to surround an antenna mounted on a well tool. A method for rotating the axis of the magnetic dipole of a transmitter or receiver coil. A method for winding and shielding an electric coil such that the resultant coil emits or receives selected electromagnetic energy field components.

Abstract: A shield apparatus for use in conjunction with a well tool to selectively attenuate one or more electromagnetic energy field components as the components interact with the shield. The shield composed of a flexible strip or conductive body and comprising at least one sloped slot or sloped conductive element therein. The shield being adapted to surround an antenna mounted on a well tool. A method for rotating the axis of the magnetic dipole of a transmitter or receiver coil. A method for winding and shielding an electric coil such that the resultant coil emits or receives selected electromagnetic energy field components.

Abstract: A shield apparatus for use in conjunction with a well tool to selectively attenuate one or more electromagnetic energy field components as the components interact with the shield. The shield composed of a flexible strip or conductive body and comprising at least one sloped slot or sloped conductive element therein. The shield being adapted to surround an antenna mounted on a well tool. A method for rotating the axis of the magnetic dipole of a transmitter or receiver coil. A method for winding and shielding an electric coil such that the resultant coil emits or receives selected electromagnetic energy field components.

Abstract: A shield apparatus for use in conjunction with a well tool to selectively attenuate one or more electromagnetic energy field components as the components interact with the shield. The shield composed of a flexible strip or conductive body and comprising at least one sloped slot or sloped conductive element therein. The shield being adapted to surround an antenna mounted on a well tool. A method for rotating the axis of the magnetic dipole of a transmitter or receiver coil. A method for winding and shielding an electric coil such that the resultant coil emits or receives selected electromagnetic energy field components.

Abstract: A shield apparatus for use in conjunction with a well tool to selectively attenuate one or more electromagnetic energy field components as the components interact with the shield. The shield composed of a flexible strip or conductive body and comprising at least one sloped slot or sloped conductive element therein. The shield being adapted to surround an antenna mounted on a well tool. A method for rotating the axis of the magnetic dipole of a transmitter or receiver coil. A method for winding and shielding an electric coil such that the resultant coil emits or receives selected electromagnetic energy field components.

Abstract: Methods and apparatus for making directional measurements of earth formations surrounding a borehole. New antenna coil shield designs are utilized to provide selective attenuation of at least one electromagnetic energy field component as the component interacts with the shield. The new shields are implemented in several downhole tool configurations to provide azimuthally focused formation measurements. In effect, the new shield filters interacting electromagnetic energy field components to pass those components corresponding to a magnetic dipole oriented at an angle from the tool axis. The shields thereby alter a coil's envelope of influence to electromagnetic energy. The new shields also form part of a system for making directional measurements while drilling.