Abstract: A borehole survey method and apparatus for use in drilling substantially horizontal boreholes through a mineral deposit wherein a dip accelerometer, a roll accelerometer assembly and a fluxgate are disposed near the drill bit, which is mounted on a bent sub, and connected to a surface computation and display unit by a cable which extends through the drill string. The dip angle of the borehole near the drill bit, the azimuth of the borehole near the drill bit and the roll angle or orientation of the bent sub are measured and selectively displayed at the surface while the drill string is in the borehole for utilization in guiding the drill bit through the mineral deposit along a predetermined path.

Abstract: The circuitry and structure of a levitated ball inclinometer are disclosed. A ferromagnetic ball is centerized between pairs of electromagnets by electromagnetic forces of magnitudes sufficient to offset the gravitational forces imposed on the ball. The electric currents required are therefore proportional to the forces and can be used as measurements to determine inclination.

Abstract: A stiff, straight spar is allowed to pivot about an anchor on the seafloor. he location of the bottom with respect to the top is then determined by measuring the tilt of the spar and computing the offset of the bottom relative to the top. The straight member uses its internal buoyancy to remain erect and stable while the weight of the anchor keeps it in place on the seafloor. The top of the spar is tracked by shore stations while the tilt and heading of the spar is monitored by an instrumentation system. Simultaneous readings of the shore instruments and the spar's tilt and heading indicators allow direct determination of the anchor location relative to the shore. An air ballast control enables the apparatus to be easily maneuvered on the ocean bottom by divers or on the surface and an internal plumb bob system allows calibration of the overall system.

Abstract: Apparatus used for the directional surveying of deep wells, i.e., 20,000-25,000 feet (6,096 meters-7,620 meters), and which is specifically identified as a gyroscopic directional surveying instrument having a high pressure and a high temperature capability, e.g., 24,000 pounds per square inch (1,632.65 atmospheres) and 450.degree. F. (232.22.degree. C.). While in its fully assembled configuration, the apparatus may be described as being exceptionally long (or at times unwieldy), e.g., 12-16 feet long (3.66 meters-4.88 meters), it is quite remarkable that it does not exceed three inches (76.2 millimeters) in diameter. Therefore, it may readily be lowered into the small diameter steel casing normally defining the walls of these deep wells. In view of its cumbersomeness, it is significant to note that the apparatus may readily be broken-down into upper and lower sub-assemblies when being transported to or from the well site.

Abstract: A flux gate magnetometer system utilizes three independent flux gates for measuring the three mutually orthogonal components of the earth's magnetic field. A sensor for each flux gate includes a ring core with a toroidal winding as the drive winding and a differential winding for sensing the difference in saturation due to the earth's flux linkages in the core. The operation of the flux gate magnetometer system is stabilized by a second harmonic servo type null circuit. The output of the differential sense winding is beat with a signal twice the frequency of the drive signal and in phase with the sensor output. This demodulated signal is the error signal for an integration stage. The integration stage drives a high impedance current source which sums into the flux gate sense winding and eliminates the effect of the earth's field in the sensor. An error signal is generated only when the high impedance current source does not null the earth's flux linkages in the core.

Abstract: A borehole mapping and navigational instrument which travels up and down in a well. The instrument includes a housing which supports at least a rate gyroscope, accelerometer, and an electric motor to rotate the accelerometer about an axis which is canted about the axis of the housing. Since the accelerometer is rotated, its tilt sensitive axis then effectively has components along the X and Y directions normal to the Z axis, whereby components along all three axis are provided.

Abstract: The invention relates to devices for measuring the azimuth and the slope of drilling line. These devices comprise, in a container 1, a gyroscope 5 having two principal axes of sensitivity X--X and Y--Y and an accelerometer 12 having two principal axes of sensitivity parallel to those of the gyroscope 5; this gyroscope 5 is connected to a circuit to determine the component of the Earth's rotation vector along the axis of the drilling line.

Abstract: A device for continuously measuring the azimuth and slope of a drilling l includes a gyroscope and an accelerometer station disposed in a container suspended from a cable. The gyroscope and the accelerometer station are mounted on an inner frame pivotally mounted on an outer frame on an axis which is perpendicular both to the axis of rotation of the gyroscope and the axis of the drilling line. The outer frame is pivotally mounted in the container on the longitudinal axis of the container. An angular position detector measures the angular movements of the inner frame in relation to the outer frame. A first motor controlled by stabilization error information delivered by the gyroscope and corresponding to one axis of gyroscope sensitivity rotates the inner frame in relation to the outer frame, and a second motor controlled by stabilization error information delivered by the gyroscope and corresponding to a second axis of sensitivity rotates the outer frame in relation to the container.

Abstract: An electrical circuit device comprises an integrating amplifier arrangement that provides a circuit output signal in response to an input signal from a differential amplifier. The differential amplifier receives at one of its input terminals the circuit input signal and at its other input terminal the circuit output signal. The circuit limits its output signal to change at less than a predetermined rate, and the device is particularly useful in a pendulum unit of a gyroscompass, where the rate limitation can be arranged such that the compass does not respond to acceleration due to motion of the craft or vehicle in which the compass is mounted.

Abstract: Apparatus for borehole surveying employing remote reading electro-optical sensors for providing digital signals represenatative of azimuth and multi-axis inclination for direct transmission to the surface for recording or use.

Abstract: Apparatus for conducting measurements of displacement, deflection, tilting, nd/or rotation of structures such as floodwalls, retaining walls, dam piers, buildings, embankments and the like is disclosed. The apparatus of this invention has the capability of simultaneously making measurements in two planes, parallel and perpendicular, with respect to an axis or other predetermined reference. Further, the apparatus of this invention includes means for determining the azimuthal bearing of the apparatus relative to the axis or other predetermined reference when the aforementioned measurements are conducted. The apparatus of this invention includes a measuring unit having a housing that houses first and second servo-accelerometers; first, second and third amplifiers; and a rotational variable differential transformer. The amplifiers are electrically coupled to a meter by means of a cable having electrical conductors.

Abstract: An instrument for measuring the direction of a borehole in order to carry out a spatial survey thereof comprises a gyro-stabilized single-axis platform having its axis coincident with the axis of the borehole and three gravity sensors for measuring three components of gravity in the direction of the borehole axis and in two mutually perpendicular directions in a plane perpendicular to said axis.

Abstract: Information as to borehole inclination is provided by a pendulum in combination with an elastomeric material whose resistance varies with compression. The pendulum is arranged in a housing to compress the elastomer whenever the housing deviates from the vertical, or other predetermined attitude. The change in resistance is measured by a circuit including an ohmmeter and the pendulum and elastomer as conductive elements.

Abstract: Apparatus for use in a rotary drill string to maintain electric continuity therethrough includes an externally insulated electric conductor tube having an electric cable mounted therein. The cable is telescopically movable with respect to the tube, and its lower end is in sliding contact with the interior of the tube. As drilling progresses, the cable may be extended relative to the tube, the sliding contact of the lower end of the cable maintaining electric continuity in the system.

Abstract: The apparatus includes a housing in which a frame is rotationally mounted, an instrument which is pivotally mounted about two axes within said frame, level sensing devices on the instrument to detect the tilt of the instrument about said two axes, and means for tilting the instrument within the frame so that the instrument's reference axis may be brought to a substantially vertical position when the apparatus is within an inclined well bore. The instrument is mounted unsymmetrically within the frame so that the instrument may be tilted in one direction on one axis a much greater amount than on the other axis and in the other direction.

Abstract: Apparatus is provided for measuring both the angle between the vertical and a particular axis of a body and the azimuth angle of the displacement of such axis from the vertical. The body houses a trasnducer having a bar magnet mounted on the free end of a pendulum beam and confronting four solenoids forming two differential fluxgate pairs disposed symmetrically with respect to the neutral position of the pendulum beam. The two differential fluxgate pairs are preferably so interconnected that the magnetic flux in each fluxgate pair is equal to zero.

Abstract: For the directional drilling of boreholes, the orientation or roll angle of the drill head or mud-motor in the borehole has to be ascertained for steering purposes. The roll angle is determined, during drilling, by sensing at the location of the drilling tool in the borehole the values of the earth's magnetic field strength in two axes transverse to the main tool axis, signalling these values to the drilling station and translating them according to the direction and inclination of the borehole axis, which are known and normally updated at intervals between drilling runs. The down-hole assembly, located in a fixed attitude to the mud-motor, requires only static magnetic sensors. A resolver in a surface indicating unit provides for the indication of the roll angle as the angle determined by the sensors, translated according to the borehole information by the addition of an angle precalculated and selected from tables, calculated in a computation center, or calculated by computation in the indicating unit.

Abstract: A tiltable coupling has one end thereof connected to a down-hole drill and has the other end thereof connected to a section of drill rod. By using that tiltable coupling, it is possible to cause a down-hole drill to drill curved holes in subterranean formations. That tiltable coupling serves to connect the section of drill rod to the down-hole drill, and also serves as a conduit for the compressed air which must be supplied to that down-hole drill.One preferred embodiment of the tiltable coupling has a fulcrum at one side thereof and has a piston at the opposite side thereof; and that piston will be left inactive whenever a straight section of the hole is to be drilled, but that piston will be actuated whenever a curved section of that hole is to be drilled.