Abstract: The invention concerns a probe for analysis of a collection of rods or tubes comprising an elongated casing which bears, at a first end, at least one first magnetometer and, at a position sufficiently remote from the magnetometer, a permanent magnet, the north-south axis of which is perpendicular to the axis of the rods.

Abstract: An electromagnetic imaging apparatus and method for electromagnetically measuring physical parameters of a pipe CJ, CC by means of a plurality of measuring arrangement ZMA, MCMA, MonMa, ImMA comprising a plurality of transmitter coil ZTX, LFTX, DTX and a plurality of receiver coil ZRX1, ZR2, MRX, MC, PRX1, PRX2, PRX3, PRX4, PRX5, PRX6, PRX7, PRX8, PRX9, PRX10, PRX11, PRX12, PRX13, PRX14, PRX15, PRX16, PRX17, PRX18, the transmitter coils and receiver coils being associated so as to form the plurality of measuring arrangement, the plurality of measuring arrangement being adapted to be positioned into the pipe and displaced through the pipe, the physical parameters being measured for a plurality of position along the pipe.

Abstract: The present invention relates to methods for determining the location of the sticking point Pc of a hollow rod or pipe 1 located in a shaft 30 subjected to the Earth's magnetic field, the point Pc being located in a part 3 defined between two points H and B of the pipe. The method according to the invention is essentially characterized in that it consists in continuously performing via the inside 2 of pipe 1, a first measurement of the magnetic field inside the part 3 of the pipe, by indexing it relative to the distance to one of the two points H and B, in applying a mechanical stress to the pipe at one of the two points H, B, in performing a second measurement of the Earth's magnetic field inside the part 3 of the pipe, by indexing it relative to the distance to one of the two points H and B, and in comparing the results R1-R2 of the two measurements in order to determine the location of the point Pc. The invention also relates to a device for implementing this method.

Abstract: A system and method for optically determining the rate and/or direction of fluid flow in a conduit within wellholes, using the diffraction effect of Faraday crystals through which continuous light is transmitted within optical fibers.

Abstract: The invention concerns a probe for analysis of a collection of rods or tubes comprising an elongated casing which bears, at a first end, at least one first magnetometer and, at a position sufficiently remote from the magnetometer, a permanent magnet, the north-south axis of which is perpendicular to the axis of the rods.

Abstract: A casing position locator for detecting structural features of a borehole casing, the locator including: a plurality of field generators for generating respective dynamic magnetic fields which combine to provide a dynamic test magnetic field to interact with the casing, where the test field includes a magnetic field null point located where the respective dynamic magnetic fields substantially cancel each other out; and a sensor for detecting a change in the position of the null point, relative to the sensor, due to the interaction.

Abstract: A magneto-optic sensor for oilfield application, the sensor (1, 1?, 101, 101?) receives an incident beam IB, IBA, IBB, IBC, IBD and comprises a polarizing element (3, 103) for providing a determined state of polarization beam and a Faraday rotator (4, 104) for providing a response beam having a modified state of polarization. The sensor provides a response beam (RB, RBA, RBB, RBC, RBD having an intensity dependent on an external magnetic field representative of a particular characteristic of a well-bore casing CC, CR applied on the Faraday rotator (4, 104).

Abstract: A casing inspection device with magnets and flux sensors. Measurements of axial motion of the device are used to get better definition of the axial extent of casing defects. A contact device may be used for motion measurement. The output of the contact device may be used to control the acquisition of flux measurements direction.

Abstract: An electromagnetic imaging method for electromagnetically measuring physical parameters of a pipe CJ, CC by means of a plurality of measuring arrangement ZMA, MCMA, MonMa, ImMA comprising a plurality of transmitter coil ZTX, LFTX, DTX and a plurality of receiver coil ZRX1, ZR2, MRX, MC, PRX1, PRX2, PRX3, PRX4, PRX5, PRX6, PRX7, PRX8, PRX9, PRX10, PRX11, PRX12, PRX13, PRX14, PRX15, PRX16, PRX17, PRX18, the transmitter coils and receiver coils being associated so as to form the plurality of measuring arrangement, the plurality of measuring arrangement being adapted to be positioned into the pipe and displaced through the pipe, the physical parameters being measured for a plurality of position along the pipe, the method comprising the steps of: a) determining a first value of an average ratio of magnetic permeability to electrical conductivity and a first value of an average inner diameter of the pipe Z-MES, b) determining an average electromagnetic thickness of the pipe MC-MES, c) determining a second value of

Abstract: A system for mapping a surface defect in an electrically-conducting material by measuring a change in the resonance of the material includes a flexible printed circuit board and a two dimensional array of transducers printed on the flexible circuit board, wherein each element of the array includes two transducer coils in a paired arrangement. A receive circuit connected to the coils is tuned to a resonant frequency, and the transducer coils operate in a send/receive mode. In another feature of the invention, there are means for converting a change in measured resonance to a visual display of the depth and width of the surface defect.

Abstract: A system and method for optically determining the rate and/or direction of fluid flow in a conduit within wellholes, using the diffraction effect of Faraday crystals through which continuous light is transmitted within optical fibers.

Abstract: Systems and methods for optically determining casing collar and/or corrosion locations within boreholes, using the diffraction effect of Faraday crystals through which depolarized continuous light is transmitted within optical fibers.

Abstract: A casing inspection device with magnets and flux sensors. The sensors provide measurements of absolute levels of magnetic flux that are indicative of changes in casing thickness and/or permeability.

Abstract: A casing position locator for detecting structural features of a borehole casing, the locator including: a plurality of field generators for generating respective dynamic magnetic fields which combine in use to provide a dynamic test magnetic field to interact with the casing, wherein the test field includes a magnetic field null point where the respective dynamic magnetic fields substantially cancel each other out; and a sensor for detecting in use a change in the position of the null point, relative to the sensor, due to said interaction.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: The invention subject of this application pertains to a method and apparatus for measuring the subterranean lithology using electromagnetic energy. The invention is applicable to the measurement from within uncased boreholes, i.e., and open-holes. The present invention transmits and receives electromagnetic energy deep into a geologic formation from a borehole, while also providing high resolution for distant measurements and the ability to control the direction in which the measurements are taken. The invention does not require a receiver to be located at the ground surface or in another borehole. In simple terms, the apparatus of this invention is able to “look around” into the surrounding geologic formation from a stationary position.

Abstract: An inspection system for detecting flaws in oil and gas well borehole ferromagnetic tubulars. The inspection device operates inside the tubular by first saturating tubular wall with magnetic flux. Flaws in the wall causes flux leakage, and the magnitude of the flux leakage are measured with Hall effect sensors disposed within the inspection device. The magnitude of flux leakage is then related to the amount of ferromagnetic material loss resulting from the flaw. Eddy currents induced in the wall are also measured and combined with the Hall effect sensor measurements to define location and geometric shape of the flaw.

Abstract: The present invention relates to a dual sensitivity eddy current test probe for inspecting a tubular member made of electrically conducting material in order to detect and localize defects in the tubular member, comprising a probe body for movement about a surface of the tubular member, a first test coil assembly for detecting and localizing defects within the tubular member, a first support for the first test coil assembly, a second test coil assembly for acquiring historical data about defects in the tubular member, a second support for the second test coil assembly, and a magnetic coupling interference eliminating system interposed between the first and second test coil assemblies. The first support is mounted on the probe body for holding the first test coil assembly at a first predetermined distance from the surface of the tubular member while the probe body moves about this surface of the tubular member.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: A magnetic induction device mounted at the wellhead that is capable of measuring changes in magnetic flux can recognize when a tubing joint or casing collar passes in or out of the well. The number of changes in magnetic flux directly correlates to the number of joints and collars that have passed, and therefore an accurate inventory of the number of lengths of casing or tubing that are run into the well can be automatically maintained.

Abstract: An apparatus that is usable with a subterranean well includes a magnetometer and a circuit. The magnetometer indicates a strength of a magnetic field that at least partially extends through a portion of a downhole pipe. The circuit is coupled to the magnetometer to indicate a feature present in the pipe based on the indication from the magnetometer.

Abstract: Detector circuitry for detecting magnetic field disturbances resulting from the movement of equipment through a pipe of magnetic material, the detector circuitry comprising a difference circuit fed with the outputs of two longitudinally spaced sensor means via respective DC blocking means, a saturating difference amplifier feeding an integrator and fed with the outputs of the difference circuit and the integrator, and indicating means fed from the integrator. The detector circuitry may also including level setting means and a comparator fed with the outputs of the integrator and the level setting means and feeding the indicating means. A second comparator may be connected in parallel with the first comparator and fed with the inverse of the output of the level setting means and the output of the integrator.

Abstract: An inspection system for detecting flaws in oil and gas well borehole ferromagnetic tubulars. The inspection device operates inside the tubular by first saturating tubular wall with magnetic flux. Flaws in the wall causes flux leakage, and the magnitude of the flux leakage are measured with Hall effect sensors disposed within the inspection device. The magnitude of flux leakage is then related to the amount of ferromagnetic material loss resulting from the flaw. Eddy currents induced in the wall are also measured and combined with the Hall effect sensor measurements to define location and geometric shape of the flaw.

Abstract: An apparatus that is usable with a subterranean well includes a magnetometer and a circuit. The magnetometer indicates a strength of a magnetic field that at least partially extends through a portion of a downhole pipe. The circuit is coupled to the magnetometer to indicate a feature present in the pipe based on the indication from the magnetometer.

Abstract: A detector for detecting magnetic field disturbances resulting from the movement of equipment 11 through a pipe 10 of magnetic material. A pair of linear ferrite magnetic elements 22A, 23A are positioned end to end and aligned with the axis of the pipe, and a Hall effect device 21A is positioned between the magnetic elements. The ferrite rods concentrate magnetic field changes due to the equipment 11 through the Hall effect device. Two pairs of elements 22A-23A and 22B-23B are spaced around the pipe, and a second set of pairs of elements 25B-27B, 26B is spaced along the pipe. The detector can be attached to an existing pipe, or mounted in an instrument package which passes through the pipe.

Abstract: An inspection apparatus for inspecting welds in a nuclear reactor jet pump includes a probe subassembly rotatably and linearly movably coupled to a frame structure configured to attach to a top flange of the reactor pressure vessel. The probe subassembly includes a plurality of probe arms pivotably coupled to a housing, with each probe arm including a sensor. The probe arms are pivotably movable between a first position where the probe arms are parallel to a longitudinal axis of the probe subassembly, and a second position where the probe arms are at an angle to the longitudinal axis of the probe subassembly. An insertion subassembly couples to the jet pump suction inlet. The insertion subassembly is sized to receive the probe subassembly and guide the probe subassembly into the jet pump through the jet pump suction inlet.

Abstract: A detector assembly and methods including a magnetoresistive sensor capable of detecting anomalies in the wall of a casing string disposed in a wellbore. Examples of anomalies include gaps between casings such as due to casing joints, air gaps in casing threads such as due to flush casing joints, enlarged casing wall thickness such as due to external casing collars, damaged casing, perforations, and other discontinuities or deformities in the casing. The detector assembly and methods detect perturbations in the earth's magnetic field caused by the anomalies. The detector assembly generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: A casing joint locator device and methods of use are described. The locator device includes a giant magnetoresistive (GMR) sensor that is capable of detecting joints between sections of casing in a wellbore. The methods and devices described detect perturbations in the earth's magnetic field caused by air gaps and discontinuities associated with a casing joint or with an external casing joint collar. As a result, they are capable of detecting flush and standard collared joints. The casing joint locator generates essentially no magnetic or electromagnetic field so that other downhole instrumentation is not affected by its presence.

Abstract: The invention relates particularly to sensing devices and techniques which may be used to provide measurement data to aid an inertial navigation system, or attitude and heading reference system, and so bound the growth of errors which increase with time in such systems when operating autonomously. In one aspect, the invention relates to a method of determining the path length along a borehole from a known reference point to a probe or tool which progresses through a drillpipe or tubular string, to provide data to aid an inertial navigation system. A sensing device 15 is used to detect joints 11 between sections of drillpipe or tubular string within the borehole and the path length is determined from the number of joints detected and a known length of each section of drillpipe or tubular string. In another aspect, a flow measuring device, such as an impeller, is used to measure the velocity of the probe or tool through the drillpipe or tubular string.

Abstract: An inductive collar locator tool is provided that provides improved sensitivity and precision in locating collars and other discontinuities in a casing string. In a preferred embodiment, the collar locator includes a transmitter coil that produces an oscillating magnetic field, which couples to the casing string proximate the tool. The tool also includes a pair of spaced receiver coils connected to signal processing circuitry which provides an output signal representing the difference in the phase of the magnetic field detected by the receiver coils. The phase difference is relatively constant when the tool is in plain casing pipe, but it changes rapidly when the tool passes through pipe that includes discontinuities, such as joints or collars. The collar locator tool may include an on-board oscillator and digital signaling capabilities. The collar locator is preferably enclosed in a titanium pressure housing that is adapted for through-tubing operations.

Abstract: There is provided a transient electromagnetic method and apparatus for inspecting objects. The apparatus includes a sensing portion, which has a transmitting antenna and at least one receiving antenna thereon. The sensing portion is located adjacent to the object which is to be inspected such that the antennas are adjacent to the object. There is also a magnet located adjacent to the sensing portion. The magnet has poles located adjacent to the object, so as to provide a steady-state magnetic field to the object. By applying a steady-state magnetic field to the object during inspection, increased inspection speeds and improved spatial resolutions can be achieved. In addition, casing can be inspected from inside of tubing.

Abstract: A detector structure is used to sense and log the joints in a downhole jointed tubular structure, such as a well bore casing or production tubing, in a subterranean well. The detector is moved through the jointed tubular structure on an elongated positioning member, representatively a slick line, through a series of joints to be logged. As the detector passes through each joint it electromagnetically senses the joint and responsively generates an electric output signal. The output signal is used to momentarily cause a drag structure portion of the detector, in cooperation with the interior side surface of the tubular structure, to momentarily create a detectable tension change in the elongated positioning member. Alternatively, a pyrotechnic or compressed gas device may be used to create the detectable changes in response to the generation of the electrical output signals.

Abstract: Well logging method and apparatus which provides a magnetic saturation signal to at least a transmitter and one receiver mounted in a well casing of a well so as to open "windows" in the casing to allow the impedances of the formations outside the casing to be logged and recorded and also to detect faults in the casing.

Abstract: Apparatus for 360.degree. azimuthal imaging of steel casing employs a transducer that is rotated around the inside wall of the casing for inducing and measuring variations in induced flux density within the casing as an indication of changes in casing thickness.

Abstract: Apparatus and method for inspecting a tubular member for degradation, which tubular member may be a control rod drive mechanism (CRDM) penetration tube of the kind typically found in nuclear power reactor pressure vessels. The CRDM penetration tube includes a thermal sleeve concentrically disposed therein, the sleeve being radially rotatable and axially translatable within the tube. However, the sleeve may be nonhomogeneous, which nonhomogeneity could undesirably mask the inspection signal as the inspection sensor is radially and axially moved in order to inspect the tube.

Abstract: An electromechanical detector structure is used to sense and log the joints in a downhole jointed tubular structure, such as a well bore casing or production tubing, in a subterranean well. The detector is lowered into the tubular structure on an elongated positioning member, representatively a slick line, through a series of joints to be logged, and then pulled upwardly through the joints. As the detector passes upwardly through each joint it electromagnetically senses the joint and responsively generates an electric output signal. The output signal is used to momentarily drive a drag structure portion of the detector into forcible, motion inhibiting contact with the interior surface of the tubular structure. This, in turn, momentarily creates a detectable tension increase in the elongated positioning member.

Abstract: A pipeline inspection vehicle comprises a body 18 an electromagnet 20 for generating magnetic flux, and two foil packs 24, 26 for conducting the flux into and out of the pipewall 10. An array of defect sensors is arranged around the body 18, each sensor being mounted on a respective assembly 28. Each assembly 28 comprises a steel sledge 40 which runs along the pipewall and which is secured to a sensor housing 42. A length of belting 44 is sandwiched between the two and end portions form a leading member 46 and a trailing member 48 linking the sledge to the vehicle. Each assembly 28 is positioned against a spring 64 which is also positioned against the vehicle. The assembly collapses out of the way when the vehicle traverses a sharp bend and the foil pack 24 is deflected to the right. The two members 46 and 48 both counteract the force of the spring 64 when the sledge crosses a void in the pipewall.

Abstract: In use, the probe (1) is dropped into a ground-hole (3), for the purpose of detecting the depth of the steel casing (16) of the hole. The probe comprises a long, slim, tubular housing (2) made of stainless steel. Attached inside the housing is a springy stalk (10) made of PVC. The stalk is deflectable laterally, and carries a magnet (11) at its free end. The magnet responds to the steel, and causes the stalk to deflect while in the presence of the steel. The housing, and a stainless steel sleeve (12) around the magnet, comprise a pair of electrical contacts, which break apart and send a signal to the surface when the magnetic influence disappears. The probe is suspended on a cable (4) which is calibrated to indicate the depth of the probe when the signal is received.

Abstract: A method and apparatus for measuring casing wall thickness using an axial main coil for generating a flux field enveloping the casing wall, and sensing actual field distribution by means of plural radial sensing coils each disposed at a radial position within the casing thereby to derive data sufficient to model a reference calibration for good casing wall structure; and, sensing flux leakage from the casing wall to detect anomalies of wall structure relative to the established reference calibration for output indication versus position along the casing.

Abstract: For use with casing having flush joint collars, a detection system is set forth which comprises a tool body made of nonmagnetic material and enclosing abutted first, second and third permanent magnets. The magnets are axially aligned, abutted so that opposing poles are in contact with one another, thereby forming a magnetic field from the center magnet which is focused out into the metal of the casing. Separate detection coils spaced along the tool body detect signals induced by variations in magnetic reluctance as the tool traverses the cased well.

Abstract: A moveable magnetic carriage on which is mounted inspection equipment for inspecting the stator of an electrical generator without removal of the generator rotor. An associated positioning device positions the carriage on the generator.

Abstract: A single-shot or multi-shot measurement probe incorporates a magnetic field sensor for sensing the earth's magnetic field, a processing unit for determining from the output of the sensor that the probe has moved from within a section of a drill pipe made predominantly of magnetizable material to within a collar made of substantially non-magnetizable material, and a switching unit for initiating the taking of one or more survey measurements by the probe when an output is received from the processing unit indicating that the probe has entered the collar. The probe further incorporates a gravity sensor for sensing the earth's gravitational field and a further processing unit for determining from the output of the gravity sensor that movement of the probe has stopped and for controlling the switching unit such that the taking of one or more survey measurements by the probe is not initiated until after receipt of an output from the further processing unit indicating that movement of the probe has stopped.

Abstract: A method for determining the type of corrosion present in deteriorating pipes. An inspection instrument is passed through a length of casing to determine the extent of corrosive deterioration. The resulting measurements generated by the inspection instrument are processed to exclude those responses caused by the structural configuration of the casing length under inspection. The remaining responses of one of the measurements are then analyzed to provide useful information regarding the type of corrosion present at defects in the casing length under inspection and to further provide information necessary to make a detailed analysis of the defects present in the casing length under inspection.

Abstract: Method and apparatus for nondestructive inspection of oilfield piping includes first and second pole pieces and a electromagnetic core therebetween for emitting a unidirectional magnetic flux field into the piping. A plurality of detector shoes each house a flux leakage coil assembly and a corresponding eddy current coil assembly. Circuits receive, process and transmit signals from the individual flux leakage coil assemblies to the surface. At the surface each signal is processed individually to provide indications of mass loss and/or gain as detected by each flux leakage coil assembly.

Abstract: Method and apparatus for nondestructive inspection of oilfield piping includes first and second elongated nonmagnetic housing members having an elongated magnetic core therebetween. A first coil assembly for emitting a unidirectional flux field is coupled to the core member. Detector shoes are coupled to said core member proximate the first coil assembly and are based into contact with the interior surface of the piping. Second and third coil assemblies are coupled to the core member for emitting unidirectional fields in opposition to the field emitted from the first coil assembly.

Abstract: A combination of magnetics and a special geometric environment is employed to distinguish whether an instrument is positioned within a pipe formed of magnetizable or non-magnetizable material, and is the basis, in part, for a method and an apparatus used in controlling picture taking at the bottom of a well bore. A coil is energized repetitively in a circuit in which the voltage across the coil, or the current that flows through the coil, can be measured. Whether the coil is in a magnetic or non-magnetic environment is determined by the magnitude of the change in coil voltage or current.

Abstract: A device to be lowered into a string of well drilling pipe to the location of a non-magnetic section of the pipe near its lower end, with the device including a compass assembly or other instrument for making a photograph or other record at that location. The device includes a detector which responds to arrival of the device within the non-magnetic section of the drill pipe to automatically energize the instrument for making the photograph or other record. The present invention provides a test circuit for this type of device enabling it to be quickly and easily checked at the surface of the earth before being lowered into the drill string to make certain both that the detector which responds to arrival of the device in the non-magnetic section of pipe is in working condition and that the batteries which energize the device are at a sufficiently high voltage level to assure effective operation of the device in the well.

Abstract: A monitoring device for monitoring an interior conduit wall includes a plurality of sliding members each resiliently urged by equal amounts away from the device body toward the conduit wall, so that the device can be used in conduits of different diameters while always remaining substantially centered within the conduit.

Abstract: Bore hole instrument and methods of manufacturing and using the same. The instrument includes an elongated flexible probe which is inserted into a bore hole and can travel freely around bends of relatively short radius in the hole. The probe includes a plurality of sensors, explosive charges or the like which are spaced apart and embedded in a flexible body comprising a mass of cushioning material, with a flexible outer casing of fabric having a high tensile strength. The probe is driven into a bore hole in piston-like fashion, and the flexible body enables the probe to travel freely around bends of relatively short radius. Instrumentation for processing signals from the probe is located at the surface of the earth, and a flexible cable interconnects the instrumentation with the probe.