Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: Slotted dipole antennas for use in an antenna system on a drill collar segment is presented. Dipoles may be placed in slots on the drill collar segment. A dipole consists of a ferrite rod with electric wires placed above and below the ferrite rod. Wires may be connected such that wire current forms a loop around the ferrite rod. When a group of slots are used for an antenna, wire holes are constructed between slots. Effectively a single wire may be used to go above all ferrite rods in the group and then turn to go below all the ferrite rods. Two wire segments are in a wire hole connecting two adjacent slots. Currents in the two segments are the same in magnitudes and flow in opposite directions. There is no net current in wires in a wire hole.

Abstract: Methods for sensing formation properties while drilling a well are described. An antenna system and transceiver electronics system are disposed on a drill collar segment. The antenna system includes at least one transmitter antenna for creating an electromagnetic field and at least one receiver antenna for detecting the electromagnetic field. At least one antenna in the antenna system is a magnetic dipole based antenna having at least two slot based magnetic dipoles. The slot based magnetic dipoles include slots in an outer surface of the drill collar segment, wire holes beneath the outer surface connecting the slots with each other and with the transceiver electronics system, a ferrite rod placed in each slot, and, at least one continuous antenna wire passing through the slots and the wire holes.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: An electromagnetic tool using slotted dipole antennas is presented. The dipoles may be placed in slots on a drill collar. A receiver or transmitter antenna consists of one or more slots. A dipole consists of a ferrite rod with electric wires placed above and below the ferrite. Wires may be connected such that wire current forms a loop around the ferrite rod. When a group of slots are used for an antenna, wire holes are constructed between slots. Effectively a single wire may be used to go above all ferrite rods in the group and then turn to go below all the rods. Two wire segments are in a wire hole connecting two adjacent slots. Currents in the two segments are the same in magnitudes and flow in opposite directions. There is no net current in wires in a wire hole.

Abstract: A DC to DC power converter device includes a controller, and a DC to DC resonant converter that includes first and second full bridge chopper circuits (FBCCs) and an LLC resonant converter coupled between the first and second FBCCs. To cause the DC to DC resonant converter to operate in a conversion mode where an input voltage received by the second FBCC is converted to an output voltage provided by the first FBCC, the controller controls switches of the second FBCC and switches of the first FBCC to transition between an ON state and an OFF state with the ON state reoccurring at a frequency lower than a resonant frequency of the DC to DC resonant converter, so that the output voltage can be higher than the input voltage.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: An electromagnetic tool using slotted dipole antennas is presented. The dipoles may be placed in slots on a drill collar. A receiver or transmitter antenna consists of one or more slots. A dipole consists of a ferrite rod with electric wires placed above and below the ferrite. Wires may be connected such that wire current forms a loop around the ferrite rod. When a group of slots are used for an antenna, wire holes are constructed between slots. Effectively a single wire may be used to go above all ferrite rods in the group and then turn to go below all the rods. Two wire segments are in a wire hole connecting two adjacent slots. Currents in the two segments are the same in magnitudes and flow in opposite directions. There is no net current in wires in a wire hole.

Abstract: Methods for sensing formation properties while drilling a well are described. An antenna system and transceiver electronics system are disposed on a drill collar segment. The antenna system includes at least one transmitter antenna for creating an electromagnetic field and at least one receiver antenna for detecting the electromagnetic field. At least one antenna in the antenna system is a magnetic dipole based antenna having at least two slot based magnetic dipoles. The slot based magnetic dipoles include slots in an outer surface of the drill collar segment, wire holes beneath the outer surface connecting the slots with each other and with the transceiver electronics system, a ferrite rod placed in each slot, and, at least one continuous antenna wire passing through the slots and the wire holes.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: Systems and methods for the measurement of geomagnetic field and an axial magnetic interference field using a directional sensor at a survey point are described. Generally, the directional sensor is used to make axial magnetic field measurements at three or more separate locations inside the directional sensor along the sensor tool axis. A computing system receives the axial magnetic field measurements and solves a set of simultaneous equations to obtain the axial component of the geomagnetic field.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor that includes orthonormal accelerometers and orthonormal magnetometers is disclosed. The method includes measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna.

Abstract: A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna.

Abstract: A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. A method of calibrating a tri-axial directional sensor comprising orthonormal accelerometers and orthonormal magnetometers, comprises measuring Earth's magnetic and gravity fields with said directional sensor in at least 4 sensor orientations; obtaining at least one reference field value of dip drift of Earth's magnetic field from at least one source independent of said directional sensor corresponding to said orientations; and, determining and applying rotational misalignments between said magnetometers and said accelerometers so that measured magnetic dip drifts are substantially equal to said reference values. The calibration process can be performed without monitoring the declination change during the calibration process.

Abstract: An improved total field calibration system and method is disclosed for reducing the rotational misalignment between magnetic and gravity sensors in a directional sensing system. The effect of variation of surface components of the Earth's magnetic field during the calibration process on magnetometer misalignment may be completely eliminated by requiring the magnetic dip derived from the sensing system to match that of the Earth's field obtained from a reference source. The calibration process can be performed without monitoring the declination change during the calibration process. Directional sensing systems can be calibrated accurately during a period when the Earth's magnetic field changes rapidly.

Abstract: A steerable or non-steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna. The antenna can also be embodied to be more sensitive to resistivity in a particular azimuthal direction.