Abstract: A system for guiding a well comprises a current source, a ground terminal electrically connected to the current source and grounded at the surface of the Earth, a reference wellbore comprising an intermediate casing (IC) that includes an IC electrical discontinuity and is electrically conductive between that the IC discontinuity and the IC bottom hole, a reference conductor electrically connected to the current source, a tubular that includes a tubular string electrical discontinuity (TSED), is electrically conductive between the TSED and the tubular bottom hole end (TBHE), and is inserted into the reference wellbore through the IC. Electrical connections exist between the tubular, the reference conductor, and the reference wellbore between the TSED and the TBHE, whereby current flowing through the reference conductor produces a magnetic field; magnetic sensors to sense the magnetic field and a guided wellbore is steered in response to the sensed magnetic field.

Abstract: A well completion system includes a current source, a ground terminal, and a reference conductor. The reference conductor is electrically connected to the current source, and is inserted into a reference wellbore having a tubular therein. The tubular has a tubular bottom hole end, and the tubular is electrically conductive between an electrical discontinuity and the bottom hole end. The tubular between the tubular string electrical discontinuity and the tubular bottom hole end is electrically connected to the reference conductor. The tubular between the tubular string electrical discontinuity and the tubular bottom hole end is electrically connected to the reference wellbore. Magnetic sensors are located outside the reference wellbore.

Abstract: An artificial toolface reference system includes a power supply providing current to a ground lead and a reference lead. A ground point is coupled to the ground lead and in electrical connection with the ground. A reference wellbore includes a reference conductor in electrical connection with the ground. The reference conductor is in electrical connection with the reference lead. A guidance sensor positioned outside the reference wellbore includes at least one magnetometer. The power supply may be used to provide a current through the reference conductor, the ground, and the ground point such that a reference magnetic field is generated along the reference conductor. The guidance sensor may measure the reference magnetic field with a magnetometer. An artificial magnetic toolface may be calculated therefrom.

Abstract: An artificial toolface reference system includes a power supply providing current to a ground lead and a reference lead. A ground point is coupled to the ground lead and in electrical connection with the ground. A reference wellbore includes a reference conductor in electrical connection with the ground. The reference conductor is in electrical connection with the reference lead. The reference conductor includes an uninsulated portion and an insulated portion having an insulating layer positioned thereabout. A guidance sensor positioned outside the reference wellbore includes at least one magnetometer. The power supply may be used to provide a current through the reference conductor, into the ground through the uninsulated portion, and the ground point such that a reference magnetic field is generated along the reference conductor. The guidance sensor may measure the reference magnetic field with a magnetometer. An artificial magnetic toolface may be calculated therefrom.

Abstract: A feedback-controlled force measuring apparatus with a force input element, a piezoelectric force generating element and a precision motion detection element in a feedback-controlled loop. Two embodiments are described. In one the force-generating element is a supported proof mass to sense linear acceleration, and in the other the force-generating element is a diaphragm supported to sense external pressure. The precision motion detection element employs resistance and inductance of a case-fixed coil of wire modulated by the distance from the coil to an electrically-conductive member connected to a force-generating element. The piezoelectric force generating element may be either a bimorph, or a piezoelectric stack.

Abstract: A downhole drill bit drive motor assembly which provides a bilateral low resistance path from the upper end of a downhole drill bit drive motor to the lower end of such a motor by employing an insulated wire or group of several wires through the rotor of the motor. The drive motors provide a drive torque to a drill bit based on the flow of drilling fluids through the motor and includes an outer case, a motor stator, a motor rotor, a coupling to connect the motor rotor to an output shaft and a bearing to support both axial and radial loads. Fixed electrical contacts are provided at the upper end of the drill bit drive motor to provide connection to wireline for transmission of data from that point to the surface or other higher points. Rotary electrical contacts that provide continuous electrical contact as a rotary portion rotates with respect to a stationary portion are provided at the upper, lower, or both ends of the rotor.

Abstract: A borehole instrument that detects the joints of successive axial lengths of magnetic material enclosing a borehole while traveling along the inside of the enclosure by detecting anomalous magnetic fields indicative of the enclosure's joints.

Abstract: A magnetohydrodynmic angular rate sensor is described. A housing supports first and second coaxial proof masses in respective annular channels, permitting relative motion between the axis of the proof masses and the housings. First and second magnets associated with each annular channel result in an electric potential being generated across each channel proportional to the relative circumferential velocity between the proof masses and the housing. The annular channels are connected together to form a continuous pumped fluid circuit which introduces a radial flow velocity in each channel. At low rotational frequencies, a circumferential velocity component is induced in the proof masses due to Coriolis acceleration which results in a measurable electrical voltage across the annular channels. The low frequency response of the sensor is therefor extended to lower frequencies.

Abstract: An electronic motion sensor is described, wherein a cavity formed in a case of high flux density material supports a permanent magnet at the bottom. The permanent magnet has a north/south pole orientation in line with the cavity axis. A circular channel is located above, having an axis coincident with the cavity axis and which is filled with mercury. A center contact post is located long the cavity axis in contact with the mercury, extending upwards through the top of the channel. An amplifier circuit supported on a header of high flux density material is placed on top of the channel. The amplifier amplifies the potential difference between the center contact and the case. The header effectively seals the cavity of the case.

Abstract: A solid electrode in the core of an angular motion sensor has a body of conductive fluid confined therein within an annular flux gap between axially spaced magnets. An arrangement of slots in the walls of the electrode modifies the current, induced in the fluid by inertial displacement, into a circumferential component, which is inductively coupled to an output winding from which an output signal is obtained.