Abstract: A transducer is described especially for use in providing acoustic transmission in a borehole. The transducer includes a multiple number of magnetic circuit gaps and electrical windings that have been found to provide the power necessary for acoustic operation in borehole while still meeting the stringent dimensional criteria necessitated by boreholes. Various embodiments conforming to the design are described. Moreover, the invention includes transition and reflector sections, as well as a directional coupler and resonator arrangement particularly adapted for borehole acoustic communication.

Abstract: A transducer is described especially for use in providing acoustic transmission in a borehole. The transducer includes a multiple number of magnetic circuit gaps and electrical windings that have been found to provide the power necessary for acoustic operation in a borehole while still meeting the stringent dimensional criteria necessitated by boreholes. Various embodiments conforming to the design are described. Moreover, the invention includes transition and reflector sections, as well as a directional coupler and resonator arrangement particularly adapted for borehole acoustic communication.An acoustic communication system is described especially designed for use in providing acoustic transmission of information in a borehole. The communication system comprises a surface transceiver and at least one downhole transceiver. The surface transceiver operates in conjunction with a host computer that sends commands to the downhole transceiver.

Abstract: A transducer is described especially for use in providing acoustic transmission in a borehole. The transducer includes a multiple number of magnetic circuit gaps and electrical windings that have been found to provide the power necessary for acoustic operation in a borehole while still meeting the stringent dimensional criteria necessitated by boreholes. Various embodiments conforming to the design are described. Moreover, the invention includes transition and reflector sections, as well as a directional coupler and resonator arrangement particularly adapted for borehole acoustic communication.An acoustic communication system is described especially designed for use in providing acoustic transmission of information in a borehole. The communication system comprises a surface transceiver and at least one downhole transceiver. The surface transceiver operates in conjunction with a host computer that sends commands to the downhole transceiver.

Abstract: The present invention relates to a method and apparatus for measuring current resulting from a magnetic field source (i.e., a transmitter) positioned on a drill collar. A plurality of current detectors are carried on the surface of the drill collar in an insulated relationship thereto. Each of the detectors is positioned to detect the value of current being received by the same from the formation. In this connection, the detectors are positioned at differing longitudinally displaced positions relative to the axis of the drill collar and the transmitting antenna(s), whereby each detects a different value of current. These currents will respectively flow through successively deeper layers of the formation. The longitudinal displacement is directly proportional to the depth of investigation, whereby the depth of investigation is many times the longitudinal distance between the current detector and the corresponding transmitting antenna.

Abstract: A transducer is described especially designed for use in providing acoustic transmission in a borehole. The transducer includes a multiple number of magnetic circuit gaps and electrical windings that have been found to provide the power necessary for acoustic operation in a borehole while still meeting the stringent dimensional criteria necessitated by boreholes. Various embodiments conforming to the design are described. Moreover, the invention includes transition and reflector sections, as well as a directional coupler and resonator arrangement particularly adapted for borehole acoustic communication.

Abstract: The method and apparatus relies on a modified induction approach and preferably is incorporated into a metal drill collar for MWD measurements. A primary changing magnetic field is formed in a formation by a transmitting antenna which is in a groove on the surface of a drilling collar. Such drill collar also carries a plurality of detecting antennas and/or current detectors which detect the value of current induced in the formation to provide a resistivity profile immediately adjacent the borehole. An embodiment uses a hybrid modified induction and electrical approach.

Abstract: The short hop communication link includes a sensor module positioned downhole from a motor in a well. The module includes sensors that monitor operational, directional and environmental parameters downhole and provide an electrical data signal indicative thereof. Sensors may also be positioned in the drill bit for obtaining parameters related to the bit, and communicating data signals reflecting the sensed parameters to the sensor module. The sensor module includes a transceiver, with an annular anrenna, for transmitting electromagnetic sensor data signals to a point above the motor. A control module, which also includes a transceiver with an annular antenna, is located above the motor, and receives the electromagnetic signals from the sensor module reflecting the sensed parameters. In addition, the control module is capable of transmitting command signals to the sensor module requesting data regarding desired parameters.

Abstract: The method and apparatus relies on a modified induction approach and preferably is incorporated into a metal drill collar for MWD measurements. Directional nulls are created in a primary changing magnetic field formed in a formation by a transmitting antenna which is in a groove on the surface of the drilling collar. Detecting antennas are placed at the directional nulls to enable the primary magnetic field to be decoupled from the same and allow it to be distinguished from the secondary field caused by the current induced in the formation by such primary field. The drill collar also carries a plurality of current detectors which detect the value of current induced in the formation to provide a resistivity profile immediately adjacent the borehole. A preferred embodiment uses a hybrid modified induction and electrical approach.

Abstract: A unipolar, RZ, constant width pulse telemetry is achieved in the combinatorial set, or any desired subset of pulse sequences thereof. Each input datum W is in one-to-one correspondence with a particular pulse sequence and the correspondence of datum with pulse sequence and vice versa is implemented by any selected ordering of the pulse sequences of the combinatorial set together with a successive comparison of the magnitude of the datum with the cumulative combinatorial capacity of the set.

Abstract: A modified subterranean antenna structure for use in boreholes that pivotally balances a separate core member within the hollow interior of a fixed winding member in order to filter out mechanically induced vibrations from the core. The mechanical natural resonant frequency of the core is reduced and becomes less than the lowest electromagnetic signal frequency intended to be transmitted to and received by the subterranean antenna. In this way, mechanically induced vibrations will not create mechanically generated frequency signals sympathetic to the frequencies chosen for the antenna communication band frequencies.

Abstract: A modified subterranean antenna structure for use in boreholes that pivotally balances a separate core member within the hollow interior of a fixed winding member in order to filter out mechanically induced vibrations from the core. The mechanical natural resonant frequency of the core is reduced and becomes less than the lowest electromagnetic signal frequency intended to be transmitted to and received by the subterranean antenna. In this way, mechanically induced vibrations will not create mechanically generated frequency signals sympathetic to the frequencies chosen for the antenna communication band frequencies.

Abstract: A unipolar, RZ, constant width pulse telemetry is achieved in the combinatorial set, or any desired subset of pulse sequences thereof. Each input datum W is in one-to-one correspondence with a particular pulse sequence and the correspondence of datum with pulse sequence and vice versa is implemented by any selected ordering of the pulse sequences of the combinatorial set together with a successive comparison of the magnitude of the datum with the cumulative combinatorial capacity of the set.

Abstract: A subsurface valve-actuator combination for well production tubing is described. The valve is urged to closed position but held open by a battery-operated latch of the actuator. A receiver-relay in the battery-actuator circuit maintains a switch closed to permit the latch to be energized as long as the receiver-relay receives an electromagnetic signal transmitted from the earth's surface. The latch is deenergized upon interruption of the signal and/or if the battery power is insufficient to energize the same.

Abstract: A method and apparatus for stabilizing a communication sensor in a borehole is described. The principle embodiment described includes a pair of centralizers at opposite ends of the housing for the communication sensor to maintain each of such respective ends at a constant lateral displacement from the borehole casing. A pair of flexible joints are provided to isolate the communication sensor to decouple the component to be protected from any motion and/or forces secured to the same urging it from the centralized position.

Abstract: A unipolar, RZ, constant width pulse telemetry is achieved in the combinatorial set, or any desired subset of pulse sequences thereof. Each input datum W is in one-to-one correspondence with a particular pulse sequence and the correspondence of datum with pulse sequence and vice versa is implemented by any selected ordering of the pulse sequences of the combinatorial set together with a successive comparison of the magnitude of the datum with the cumulative combinatorial capacity of the set.

Abstract: A subsurface valve-actuator combination for well production tubing is described. The valve is urged to closed position but held open by a battery-operated latch of the actuator. A receiver-relay in the battery-actuator circuit maintains a switch closed to permit the latch to be energized as long as the receiver-relay receives an electromagnetic signal transmitted from the earth's surface. The latch is deenergized upon interruption of the signal and/or if the battery power is insufficient to energize the same.

Abstract: The location method uses relatively low frequency electromagnetic fields, e.g., 1-1000 Hz, for determining the relative position and/or orientation of a transmitting magnetic dipole antenna by using a vector field receiver. The transmitting antenna for subterranean location, is preferably a single axis, elongated solenoid with a ferromagnetic core. The receiving sensor may be a precise three-axis magnetic field detector of either a magnetometer or search coil type. Measurements are made for one or more positions of either the transmitter or receiver, or with one or more transmitters or receivers. The relative location of the transmitter and the receiver is calculated with respect to some known survey station by a method of successive approximations. The operating frequency is chosen to minimize field distortion from common steel structures, such as pipe, casing or railroad tracks, and to minimize field scattering such as from conducting inhomogeneities in the earth.

Abstract: For the directional drilling of boreholes, the orientation of accelerometer modules, magnetometer modules and gyroscopes or other directional sensing devices must be accurately known and maintained with respect to each other and to external mounting devices. This is accomplished by a self-aligning segmented cylindrical connection which accurately maintains modules in rotational alignment with each other for all three directions of rotation, even if the mating surfaces of the connection experience wear due to rough use in the drilling application or repeated calibration in a calibration fixture. Wedged surfaces on each of the male and female portions of the connection constitute the mating surfaces, and are the only surfaces at which the male and female portions contact one another. A depression between the mating surfaces defined by the female portion permits reproducible angular displacement of one portion with respect to the other even if one or both portions are worn.

Abstract: An inclinometer includes a toroidal race containing a spherical ball free to move therein under the influence of gravity. Signal source and collector electrode assemblies are provided on opposite sides of the toroidal race, and the ball functions to capacitively couple signals on the source electrode to the collector electrode. In one embodiment the source electrode is shaped so that the amplitude of coupling varies with ball position in the race so that the signal on the collector electrode is indicative of ball position. In other embodiments the source electrode is continuous and symmetrical, and signals applied thereto are selected such that a property of the signal coupled to the collector electrode, such as signal phase, varies in accordance with ball position in the race. Three such inclinometers can be combined in a borehold sensor for drilling applications.

Abstract: A relatively low frequency wireless electromagnetic communication link is established through a subterranean lossy medium such as ground or water by launching and propagating magnetic waves of generally vertical magnetic polarization through the intervening subterranean region of earth or water between a pair of magnetic dipole antennas. A suitable subterranean dipole magnetic antenna includes an elongated electrical solenoid having a ferromagnetic core, as of ferrite or laminated iron. Relatively low frequency magnetic waves are utilized wherein the frequency is related to the conductivity of the subterranean region and distance between transmitter and receiver such that the range is less than 10 skin depths at the carrier frequency.