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 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 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: A system for verifying the effectiveness of electromagnetic signal control of a subsurface safety valve installed in a well. Signals are transmitted from a surface station to actuate the subsurface installed valve. Signals received at the valve are decoded and information relating to them is stored. A sensor detects actual valve actuation and provides signals indicative thereof which are also stored. After the valve is removed from its downhole installation, the stored signals are read, and the data indicated thereby is compared with data recorded at the time of signal transmission from the surface.

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 thin superconductive magnetic shield, as of lead, is supported from a hollow support structure, as of aluminum or fiberglass by means of a multiplicity of spots of adhesive, as of epoxy, serving to bond the superconducting shield to the support structure. The shield and support structure is then positioned within a reentrant cryostat and cooled to liquid helium temperature to render the shield superconductive. Adjacent edges of the shield material are outwardly flanged and sealed together at the flanged portions, as by welding. The spot pattern of adhesive permits the shield to flex during thermal cycling to relieve strain and prevent fracture thereof while at the same time supporting the shield in a substantially nonmicrophonic manner.

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.

Abstract: One or more primary superconductive magnetic field pickup coils are trimmed by means of one or more auxiliary super-conductive trim coils coupled to a magnetic flux sensor for sensing the magnetic flux coupled to the sensor by said primary and auxiliary coil circuits. The trim coils preferably each have their respective magnetic axes oriented orthogonally to each other for independent adjustment. The trim coils are wound in the gradient configuration and an adjustable superconductive magnetic shield is provided surrounding each of the respective trim coils for varying the coupling between the respective trim coil and the magnetic field by varying the position of the magnetic shield relative to a null or symmetric position relative to the trim coil. In a preferred embodiment, there are three mutually orthogonal trim coils.

Abstract: A primary superconductive magnetic field component or gradient pickup coil circuit is trimmed by means of one or more auxiliary superconductive trim coil circuits electromagnetically coupled to a magnetic flux sensor for sensing the magnetic flux coupled to the sensor by said primary and auxiliary coil circuits. The trim coils each have their respective magnetic axes oriented orthogonally for independent adjustment of trim. An adjustable magnetic shield is provided surrounding each of the respective trim coils for varying the coupling between the respective trim coil and the magnetic field. In this manner transverse and axial balance or trimming of the primary pickup coil circuit is obtained by adjusting the positions of the respective magnetic shields around each of the respective trim coil circuits. In a preferred embodiment, there are three mutually orthogonal trim coil circuits.