A downhole antenna tool is disclosed for downhole well-logging or other downhole operations. Antenna bars are provided for winding of coils through associated coil carriers of individual ones of the antenna bars. The antenna bars with the wound coils are coated with a protection layer and are releasably coupled to a substrate of the downhole antenna tool using, for example, a silicone cushion layer.

A downhole antenna tool is disclosed for downhole well-logging or other downhole operations. Antenna bars are provided for winding of coils through associated coil carriers of individual ones of the antenna bars. The antenna bars with the wound coils are coated with a protection layer and are releasably coupled to a substrate of the downhole antenna tool using, for example, a silicone cushion layer.

An imaging device included in an assembly located in a wellbore during drilling operations may include a cylindrical housing that extends along a central axis thereof. The imaging device may include at least one gradient coil configured to produce a unique magnetic field weaker than a main magnetic field. The at least one gradient coil may create a variable field that is increased or decreased by changing a direction of the unique magnetic field with respect to a direction of the main magnetic field to allow a specific part of a rock formation to be scanned by altering and adjusting the main magnetic field. The imaging device may include at least one radio frequency coil configured to transmit radio frequency waves into the rock formation. The imaging device may include at least one magnet disposed in the cylindrical housing that resonates against the unique magnetic field.

An imaging device included in an assembly located in a wellbore during drilling operations may include a cylindrical housing that extends along a central axis thereof. The imaging device may include at least one gradient coil configured to produce a unique magnetic field weaker than a main magnetic field. The at least one gradient coil may create a variable field that is increased or decreased by changing a direction of the unique magnetic field with respect to a direction of the main magnetic field to allow a specific part of a rock formation to be scanned by altering and adjusting the main magnetic field. The imaging device may include at least one radio frequency coil configured to transmit radio frequency waves into the rock formation. The imaging device may include at least one magnet disposed in the cylindrical housing that resonates against the unique magnetic field.

A resistivity imaging device and a method of operating the resistivity imaging device in a wellbore. The resistivity imaging device includes a first electrode, a second electrode, and a circuit electrically coupled to the first electrode and the second electrode. An impedance is measured of a formation surrounding the wellbore. Based on the impedance, the circuit is configured into one of a first circuit configuration for operating the resistivity imaging device in a first mode and a second circuit configuration for operating the resistivity imaging device in a second mode. The resistivity imaging device is operated using the circuit in the one of the first circuit configuration and the second circuit configuration.

A resistivity imaging device and a method of operating the resistivity imaging device in a wellbore. The resistivity imaging device includes a first electrode, a second electrode, and a circuit electrically coupled to the first electrode and the second electrode. An impedance is measured of a formation surrounding the wellbore. Based on the impedance, the circuit is configured into one of a first circuit configuration for operating the resistivity imaging device in a first mode and a second circuit configuration for operating the resistivity imaging device in a second mode. The resistivity imaging device is operated using the circuit in the one of the first circuit configuration and the second circuit configuration.

Certain logging method and system embodiments obtain multi-component signal measurements from an electromagnetic logging tool conveyed along a borehole through a formation, and invert the measurements for a single frequency using an anisotropic formation model having at least dip, horizontal and vertical resistivity, and horizontal and vertical permittivity, as parameters. A resulting log is provided to represent a position dependence of at least one of said parameters or a formation property derived from at least one of said parameters. Illustrative formation properties include water saturation, rock type, and presence of pyrite or other such materials having anisotropic polarization. Inversions may be performed on measurements acquired at other frequencies to determine a representative dispersion curve for further characterization of the formation.

A method for detecting a beacon signal using an above-ground tracker. The tracker comprises an antenna assembly comprising a plurality of antennas. Each antenna is oriented in a different direction. During operation, if the beacon signal is interrupted due to a local noise source, transmission of the beacon signal is stopped. The tracker then detects radiation from the local noise source and the processor determines a direction from which peak ambient noise arrives at the tracker. The beacon signal is then resumed. A processor included in the tracker excludes any signals generated by the antenna assembly that are representative of radiation that arrived at the tracker from the same direction the peak ambient noise arrived at the tracker. The tracker then detects the beacon signal using the non-excluded signals.

A method for detecting a beacon signal using an above-ground tracker. The tracker comprises an antenna assembly comprising a plurality of antennas. Each antenna is oriented in a different direction. During operation, if the beacon signal is interrupted due to a local noise source, transmission of the beacon signal is stopped. The tracker then detects radiation from the local noise source and the processor determines a direction from which peak ambient noise arrives at the tracker. The beacon signal is then resumed. A processor included in the tracker excludes any signals generated by the antenna assembly that are representative of radiation that arrived at the tracker from the same direction the peak ambient noise arrived at the tracker. The tracker then detects the beacon signal using the non-excluded signals.

Methods, systems and devices for evaluating an earth formation, including an electromagnetic (EM) well logging apparatus for investigating a formation from a fluid-filled borehole intersecting the formation. Apparatus include a carrier body having a pocket formed in an outer surface, the pocket being defined by a plurality of walls and a bottom; a pad configured to emit EM energy, the pad having an outer face, a plurality of sides complementary to the plurality of walls, and an inner face positioned adjacent to the bottom, wherein the pad is movably disposed in the pocket such that a gap separates at least one wall of the plurality of walls and at least one side of the plurality of sides; and at least one electrically conductive member forming an electrical connection between the carrier body and the pad and covering the gap. The pad may be slideably disposed in the pocket.