Abstract: A method of preventing flow of formation fluid and crude oil into a well bore during an electric resistivity logging operation. A readily flowable liquid gellation composition containing a breaker is of contrasting resistivity to that of the formation water. Fluids in the well bore are displaced by the liquid composition and the composition is allowed to gel. The gel may be of a highly viscous, moderately flowable state, which prevents ingress of formation fluids and crude oil but permits logging equipment to be moved therethrough. Alternatively, the gel in the well bore may be removed while leaving the gel in the adjoining formation in place, and the removed gel replaced with fresh water prior to the logging operation. After effecting the log a breaker in the gel composition causes the gel to revert to a liquid, which is removed from the well bore.

Abstract: A sensor for sensing magnetic fields. A single mode optical fiber has a core which is wound into a helical shape. The fiber is formed with a former and a core, and the core is preferably attached to the inner surface of the former and wound into a helical shape tracing its inner periphery. The core is also offset from the central axis of the fiber former.

Abstract: A device and process for programmatically controlled in-circuit pin checks and gross functionality tests of analog to digital converters. The tests provide deterministic bit checks for higher order bits and non-deterministic bit checks of lower order bits independent of other circuitry on the printed circuit board of which the digital to analog converter is a component.

Abstract: A sensor (10) for sensing the magnitude of current flowing in a conductor (12) based upon the Faraday effect is disclosed. The invention utilizes a magneto-optic material having one or more layers (32) in which alignment with an optical fiber is not critical in achieving accurate current measurements. A magneto-optic material (28) in accordance with the invention includes one or more layers (32) each having a substrate having opposed surfaces coated with a material exhibiting the Faraday effect in which light from a light source is transmitted through the magneto-optic element without substantial internal reflection and is incident upon a surface area of the coating which is greater than the surface area of the beam of light.

Abstract: A method is disclosed for detecting the T.sub.1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T.sub.1 phase may be detected.

Abstract: A speed detector, for use with a tone wheel having metal teeth, employs two coils positioned in offset relation near the tone wheel for interacting with the tone wheel teeth and thus changing their respective inductances. The coils preferably include iron cores to enhance magnetic coupling. One coil is in a phase sense oscillator circuit and the other is an a tuned sensor network. The oscillator is coupled to, and drives, the tuned network. The change in coil inductances effects a phase shift of the resulting signals in the oscillator and the tuned network, the magnitude of that phase shift typically being double that for a comparable single coil system. The output signals of the oscillator and tuned network provide inputs to a phase condition detector which looks for a reversal in their phase sequence and uses such event to provide timing reference pulses for a final determination of speed in a known manner.

Abstract: A geophysical prospecting method of measuring potentials existing in the air in the area of the lower atmosphere between about one and ten meters above the surface of the earth in order to detect petroleum accumulations and mineral deposits below the surface of the earth. The method mounts a detector device is mounted on the front bumper of an off-the-road vehicle and moves the vehicle across the surface of a given area of earth in a more or less continuous fashion. Changes in the electron flow through the ion field at the surface of the earth to increased and decreased resistivity values in the crust of the earth are recorded.

Abstract: An improved non-contact type pattern sensor includes a magnetic resistor element arranged facing a pattern track on a recoridng medium having a magnetized pattern in the pattern track. A clearance sensor is arranged to face the pattern track on the recording medium and generates a detection signal as a function of the distance between the clearance sensor and the pattern track. The control unit connected to the clearance sensor generates an output signal which varies as a function of the detection signal. A magnetic field generator connected to the control unit is arranged near the magnetic sensor element and generates a bias magnetic field whose intensity varies as a function of the output signal.

Abstract: A liquid level detector of the type in which a magnetostrictive wire extends through the liquid level measurement range and is captured in a tensioned vertical orientation within a stainless steel tube. Liquid level is measured as a function of the time required for a torsional disturbance imparted the wire near the top to travel along the wire to a magnet which is contained within a liquid level float which slides up and down along the tube. The torsional disturbances imparted to the wire by means of a piezoelectric crystal to which the wire is easily clamped. Accuracy is enhanced by measuring liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.

Abstract: A conducting metal discriminating detection apparatus which uses at least two different frequencies and in preference 3 to interrogate a target. The detection apparatus distinguishes reactive and resistant components of each of the received signals and combines these in such a way as to avoid effects of background such as ironstone in one case or salt water in another.

Abstract: Method and apparatus for measuring apparent earth resistivity, by determining potential drop produced by electric current injected into the ground. Periodic, or very low frequency polarity reversal of direct current is used to eliminate induced voltage errors that might otherwise occur with higher frequency polarity reversal or alternating current. Synchronizing pulses are used to gather and separately store information from each half cycle. A calibrated readout is obtained in which values of the voltages in the two half-cycles are algebraically subtracted and divided by two to measure the potential drop, with automatic compensation for effects of earth currents.

Abstract: A pulser ring has cylindrical inner and outer rings nested together. The inner ring is formed at its one end with protrusions arranged at equal angular intervals. The outer ring is in the shape of a round comb and has its teeth engaged at a portion near the tip thereof in the grooves defined between the adjacent protrusions formed on the inner ring. The tip of each tooth protruding from the grooves is bent radially inwardly so as to engage the end face of the protrusion on the inner ring, thus coupling the inner ring and the outer ring together.

Abstract: A sensor is connectable with a load circuit via two conductors. The sensor receives its electrical power from the load circuit via the two conductors and similarly provides its output signal indicative of the sensed phenomenon via the same conductors. An unregulated source potential is provided to a terminal of the sensor from a supply potential via the load circuit. Voltage regulating circuitry in the sensor converts the unregulated source potential to a regulated operating potential for its active circuit elements. Certain output circuitry in the sensor is connected to the terminal having the unregulated source potential for conveying an output signal from the sensor to the load circuit.

Abstract: A method for detecting a geologic deposit of a selected substance. In the method, the intensity of the local geomagnetic field at one or more measurement sites at a first location is resolved. During selected time intervals, at each site, the amplitude of the indigenous terrestial alternating electromagnetic radiation is measured at a frequency in the vicinity of a frequency equal to the local geomagnetic field intensity multiplied by the Larmor constant of the selected substance and divided by 2.pi.. Each measurement is intergated over a respective time interval to yield one or more integrated values. The integrated values are analyzed.

Abstract: A magnetic sensor is provided for use in detecting an external magnetic field, typically geomagnetism. Pulse or alternating current is applied across a wire or strip-shaped electrically conductive, magnetic body in its longitudinal direction to create an internal magnetic field in the magnetic body. A pick-up winding is wound around the magnetic body. The sensor detects an electric signal developed in the winding as a result of interaction of the internal and external magnetic fields.

Abstract: The SQUID magnetometer for a device for the single-channel or multi-channel measurement of very weak magnetic fields caused by at least one field source to be detected contains at least two super-conducting gradiometer loops which, with two Josephson tunnel elements form a d-c SQUID. This magnetometer should have high sensitivity with good interference suppression. At least one detection loop and at least one compensation loop are located as the gradiometer loops as well as the Josephson tunnel elements together with superconducting connecting conductors between these parts one behind the other on a three-dimensional surface of a carrier and the mutual distance between the detection loop and the compensation loop is chosen sufficiently large that the magnetic flux, also picked up by the compensation loop of the field source to be detected, amounts to at most 20% of the magnetic flux picked up by the detection loop.

Abstract: A Hall elements and magnet assembly for use as a proximity detector includes a magnet, a pole piece mounted to one pole end of the magnet and an integrated circuit having two side-by-side Hall elements, an amplifier, interconnecting wiring providing the difference voltage between the two Hall output voltages at the input of the amplifier, and a Schmitt trigger circuit. The integrated circuit is mounted to the pole piece at the pole end of the magnet. The pole piece is a ferromagnetic member which is thinner in the center than at the periphery for achieving a highly uniform field strength across the surface of the magnet pole end toward reducing the criticality of the position of mounting of the integrated circuit in manufacturing and for extending the range of gap dimensions between a passing ferromagnetic article and the assembly for which proper detection of the passing article can be made to occur.

Abstract: A method and apparatus for generating and detecting magnetization responses from ferromagnetic, ferrimagnetic, paramagnetic, or diamagnetic materials comprises a means for generating an alternating magnetic field. The cycle of the alternating magnetic field includes a first magnetization pulse and a second demagnetization pulse, the energy content of the magnetization pulse and the demagnetization pulse being approximately equal, the time duration of the magnetization pulse being substantially longer than the time period of the magnetization pulse, the demagnetization pulse having a higher magnetic field strength than the magnetization pulse magnetic field strength. The effect of the alternating magnetic field on the material to be tested is measured by magnetic field detectors. The field detectors generate electrical signals which are fed to an oscilloscope, a comparator, or a computer for analysis.

Abstract: The method of measuring local rock inhomogeneities on the wall of a borehole is disclosed. The method of measurement includes the step of generating microelectric fields in a conductive way on an area of the wall of the borehole insulated from the drilling mud by an insulating pad which carries electrodes and excludes direct electrical contact between the electrodes and the conductive borehole liquid. The local current intentities are measured at, at least two, different places perpendicularly to the wall of the borehole and the measured current intensities are compared to each other. Alternatively, a local voltage difference created by current flowing first parallel to the wall of the borehole and then an absolute voltage created by the same current in another section of flow where the current is perpendicular to the wall of the borehole may be measured and the measured voltages compared to each other.

Abstract: An apparatus for sensing the electrical potential of a positive electrostatic field which is primarily below the surface of the earth, and observing the changes in a series of each reading is accomplished by means of an instrument employing a column of mercury in a small-diametered quartz tube, which is open on its lower end with means connecting to the other end for changing the level of mercury within the tube. A conductive coating on the exterior of the tube is connected to an electrometer and the coating is arranged to be selectively grounded or ungrounded in conjunction with changing the level of the mercury column. The readings for the electrometer provide a measure of the electrostatic field.