Abstract: A down-hole signal generator for a mud-pulse telemetry system comprises a flow constrictor defining a throttle orifice for the mud passing along a drill string, a throttling member displaceable with respect to a casing to modulate the mud pressure for the purpose of transmitting measurement data up the drill string, and a turbogenerator incorporating an electrical generator within the casing. The flow constrictor and casing form an integrated unit which is installed within a drill collar and is retrievable by drawing it up the inside of the drill string. The throttling member is displaced by a pump according to the torque required to drive the rotor of the generator which is dependent on the electrical load of the generator. The pump incorporates a rotary valve member which supplies the output of the pump to one or other side of a double-acting ram according as to whether the valve member is rotating with a first phase of rotation or a second phase of rotation.

Abstract: A magnetostrictive generator includes a magnetostrictive transducer having a vanadium permandur core and series connected primary and secondary windings, the secondary winding having more turns that the primary winding. A commutating capacitor is connected in parallel with the primary and secondary windings of the transducer and a switch is connected in series with the primary winding. A storage capacitor, which is connected in parallel with the switch and the primary winding of the inductive transducer, is charged by a remotely located low voltage power supply when the switch is open. When the switch is closed, the storage capacitor discharges through the primary winding of the transducer to charge the commutating capacitor until the transducer reaches saturation, the commutating capacitor discharging thereupon to drive the transducer into hard saturation to produce magnetostrictive action in the core and physically deform the transducer and produce an acoustic signal.

Abstract: A nonconducting pipe thread lubricating composition for use in a drill string capable of transmitting electrical signals from a downhole location to the surface of the earth. The composition includes hard and soft moderately deforming materials such as polyphenylene sulfide and talc, and a lubricating solid such as polytetrafluoroethylene dispersed in a viscous lubricating base preferably a lithium based grease.

Abstract: A gamma ray density sub and method useful for measurement-while-drilling applications utilizing three pairs of gamma ray sources and detectors located symmetrically about the axis of the sub and computation of the product of the counting rates obtained from the three detectors to indicate the average density of a formation sample surrounding a borehole traversing an earth formation. The sub is able to measure the density of the sample, independent of the location of the sub within the borehole and the chemical composition of the interfering materials lying between the formation sample and the detectors.

Abstract: An external gauge carrier for use in tubing-conveyed drill stem testing comprises a protective housing for locating and securing the pressure measuring and recording system. The gauge carrier may be manufactured from drill collar bar stock but provides a 1--1 interface with ordinary drill pipe, other measurement subs, perforating guns and the like; i.e., to the complete system it "looks" like a drill collar. The gauge measures and records drill stem bore pressure while providing "full bore" testing capabilities, i.e., the gauge carrier allows unimpeded wireline operation therethrough and causes essentially no pressure drop throughout its length. Special machining and gauge placement is required in order to provide the above capabilities and features while still maintaining sufficient wall thickness to ensure structural integrity. A unique system for protecting the relatively delicate gauges from damage due to shocks from pressure surges is also disclosed.

Abstract: Determination of drilling mud thermal conductivity for estimation of earth formation temperature through a well bore thermal model. Borehole annulus and drill pipe bore temperature measurements are taken over a relatively short period of time when circulation of drilling mud is interrupted and temperature differentials maximized. The dynamic temperature response characteristics related to the heat transfer and storage parameters of the drill pipe, mud and bit are integrated into a mathematical borehole model incorporating the thermal resistance, heat capacity, and heat generation of the mud and drill pipe and the drill bit. The maximum temperature differential is then determined and the response characteristics used to establish the requisite parameters for the thermal conductivity and temperature calculations. In this manner, formation temperatures can be estimated to monitor downhole mud behaviour and geothermal gradients.

Abstract: Method and apparatus are provided for determining the formation pressure. The magnitude of formation pressure may be derived as a function of changes in bottomhole pressure following swabbing the borehole to draw formation fluids into the borehole, monitoring the borehole for influx of formation fluids, determining the reduced pressure due to swabbing, repeating the swabbing and monitoring steps until an influx of formation fluids is detected thereby determining the pressure of the formation.

Abstract: In a borehole telemetry system for acoustically transmitting data over a pipe suspended in a borehole, the level of noise in the data stream is inherently high due to the environment existing in a drilling operation and to the physical characteristics of a drill string. It has been discovered that certain discrete frequency passbands exist in a drill string which permit transmission of an acoustic signal with a minimum level of attenuation. In addition, it is now known that a fine structure exists within these frequency passbands which presents gaps or voids that attenuate the signal at a much higher rate. These gaps are on the order of 20 Hz.By generating an acoustic signal at a precise frequency spectrum within these passbands and then phase shifting the signal before its transmission, the energy spectrum of the transmitted signal is spread out over a sufficient frequency range to bridge these gaps.

Abstract: In accordance with an illustrative embodiment of the present invention, a seal or bearing lubricating system adapted for use in a downhole tool such as a drilling motor includes chamber means packed with grease for lubricating said seal and/or bearing, and centrifugal separator means responsive to rotation of a shaft included in said tool for separating and trapping solid particles suspended in the well fluids to prevent contamination of the grease by such solid particles. Pressure equalization across a principal rotating shaft seal also is disclosed.

Abstract: A down-hole signal transmitter for a mud pulse telemetry system comprises a flow constrictor defining a throttle orifice for the mud flow, a throttling member displaceable to vary the throughflow cross-section of the throttle orifice, and a pump for displacing the throttling member against the mud flow in order to modulate the mud flow. The displacement of the throttling member is controlled by a hydraulic amplifier, comprising a main pressure relief valve and a subsidiary control valve, and a solenoid to which the output signal of a measuring instrument is supplied. When the main valve is close, the pump displaces a ram, coupled to the throttling member, upwardly.

Abstract: Method and apparatus for measuring the flow velocity of drilling mud returning from the annulus of a borehole. At least two parametric acoustic pulse transducers are longitudinally disposed with respect to a conduit with a pair of acoustic receivers positioned therebetween. The transducers each generate strong, focused acoustic waves comprised of combined dual frequencies directed at the center of the conduit area in which fluid flow is to be measured. The transducers are actuated alternately and produce time variant signals permitting measurement of fluid flow by employing the Doppler effect on the parametric secondary acoustic pulses. The utilization of combined dual frequency acoustic transducers provides a primary signal having sufficient strength to produce a non-linear response in the liquid and produce secondary, low frequency wave propagation directly from within the mud itself. The low frequency waves enhance wave propagation through gas cut muds and enhance signal recognition in the receivers.

Abstract: A high pressure seal assembly for use with an insert cover positioned in a downhole tubular housing, the assembly having a flange which is deformable by the pressure differential between higher pressure on the exterior of the insert cover and the lower pressure on the interior of the insert cover. A portion of the flange is deformed to mate against the tubular housing. In a preferred embodiment, the flange has two legs, one being attached to the insert cover and the second being the deformable portion having deformable spacer material positioned between the second leg of the flange and the housing.

Abstract: A drilling mud flow rate detector, including a sub adapted for being positioned in the drill string, having a sonic signal generator located near the center of the sub in both the incoming mud flow path and the return mud flow path. A set of sonic signal receivers is located at both ends of the sub in both the mud input flow path and the mud return flow path and corresponding sets of sonic signal transmitters are located near the center of the sub. The distance between the transmitting transducers at the center of the sub and the receiving transducers located at each end of the sub are equal so that under a condition of no mud flow, the sonic signals arrive at each end of the sub simultaneously. During mud flow, "doppler effect" will produce phase shifts in the sonic signals which are proportional to the direction and the rate of mud flow. Signals received by the receiving transducers are processed to produce an input mud flow rate signal and an output mud flow rate signal which are then compared.

Abstract: A device for determining the stuck point of a drill pipe in a borehole consisting of two relatively movable sections, anchoring means for each section, a sensing means for detecting relative movement of the two sections and producing an inductance representative of the movement. The inductance is transformed into a frequency modulated signal which is transmitted to the surface and converted from a non-linear direct current voltage representation of relative movement to a linear direct current voltage.

Abstract: When surveying a borehole using an instrument responsive to the earth's magnetic field, a length of non-magnetic drill collar is necessary to house means for measuring the magnetic field in the borehole perpendicular to the direction of the borehole axis. The instrument determines the inclination angle and the highside angle from the gravitation measurements, with these measurements and the magnetic measurements, the azimuth angle is determined. Using the method of this invention a minimum length of non-magnetic material necessary for an accurate measurement may be calculated and used.

Abstract: A borehole is surveyed by positioning at the mouth of the borehole a survey instrument having a casing and a three-axis rate gyroscope unit mounted within the casing, and sensing at least two components of gravity in at least two mutually transverse directions with respect to the survey instrument by means of a gravity sensor unit. The survey instrument is then moved along the borehole with the start and finish of the run being at the mouth of the borehole or at some known reference along the path of the borehole. During the run the rates of rotation about three non-coplanar axes are sensed at a series of locations along the length of the borehole by means of the rate gyroscope unit.

Abstract: Disclosed is a method and apparatus for mechanically and metallurgically holding a cutter in a drill bit pocket. The method includes using powder metallurgy techniques in the formation of a drill bit member having a plurality of pockets configured to inhibit displacement of cutters out of the pockets in a direction transverse to the drill bit working surface. The method further includes the steps of metallurgically bonding and mechanically engaging the cutter with the cutter pocket. The drill bit manufactured in accordance with the methods of the present invention include a carbide menstrum drill bit head having a working surface with a plurality of fluid courses and nozzles thereon in adjacent relationship with a plurality of cutter blade bands comprising a series of cutter pockets having cutters disposed therein in a fashion parallel with the working surface.

Abstract: Apparatus is disclosed for releasably connecting first and second space objects, such as a spacecraft and a space vehicle, in predetermined spaced relationship. The apparatus comprises at least one probe member (10) mounted on the first object (1), having an elongated shank portion (11), the distal end of which is provided with a tapered nose portion (12). At least one drogue assembly (20) is mounted on the second space object (2) for releasably capturing the probe member 10 upon the first and second objects (1 and 2) being brought into close proximity with each other.The drogue assembly (20) may comprise a housing (21, 28) which carries a cone subassembly (40, 41) having inwardly tapered conical surfaces (42, 43) for receiving the probe member (10).

Abstract: Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements. Received between each crank pin (C) and connecting rod (D) is an eccentric sleeve (F) selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod (D) to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl (F) carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve (J) responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

Abstract: Measuring apparatus for determining changes in the volume of limbs or other body extremities by determining the cross-sectional area of such limbs may comprise a transmitter (10) including first and second transducers (11, 12) for positioning on the surface of the limb at a predetermined distance therebetween, and a receiver (20) including a receiver crystal (21) for positioning on the surface of the limb. The distance between the receiver crystal and the first and second transducers are represented by respective first and second chords (d.sub.1, d.sub.2) of the cross-section of the limb (C) and the predetermined distance between the first and second transducers is represented by a third chord (d.sub.3) of the limb cross-section (C).The measuring apparatus may also include a Pinger (10) and associated electrical circuitry for generating acoustic pulses at the first and second transducers (11, 12) for propagation along the first and second chords (d.sub.1, d.sub.