Abstract: A method and a system implementing the method, are disclosed for computing magnetic interferences in measurement while drilling operations, using the retrieved lateral, and axial magnetic interferences of the measurement while drilling downhole tool system. With the disclosed method and system of implementing the method, it can be determined whether the source of the magnetic interference is from the measurement while drilling downhole tool system lateral direction or its axial direction. When magnetic field strength is abnormal, the lateral and axial magnetic interferences are monitored, and then compared against their values before the abnormal magnetic field strength. This way the direction of the magnetic interference is analyzed to eliminate or judge the cause of the interference, and properly guide the measurement while drilling downhole tool system towards its reservoir or well location.

Abstract: A formation tester tool includes an extendable probe having an extendable member configured to extend from a retracted position to an extended position such that an end of the extendable probe is in fluid communication with a wall of a borehole during an operation to capture a fluid from a formation. The formation tester tool also includes a sealing pad positioned circumferentially around the extendable probe, wherein a face of the sealing pad is configured to sealingly engage the wall of the borehole while the extendable member is in the extended position. The formation tester tool also includes a shield to cover the sealing pad in a covered position between the sealing pad and the wall of the borehole.

Abstract: A caliper finger for use as part of a multi-finger caliper logging tool has a body formed substantially of a first material and a finger tip formed substantially of a second material which has greater mechanical durability than the first material. The first material and second material are fused directly together at a joint between the first material and the second material. The finger tip may comprise a plurality of successively-fused layers of the second material, which can then be machined at its outer surface after fusion of the plurality of layers. The second material may be a composite material of tungsten carbide combined with a base material in which the tungsten carbide is embedded and securely bonded to the finger.

Abstract: Techniques for controlling a bottom hole assembly (BHA) to follow a planned wellbore path include determining sensor measurements from the BHA; determining a model of BHA dynamics based on the sensor measurements from the BHA; determining a weighting factor that corresponds to a drilling objective; determining an objective function comprising the drilling objective, weighted by the weighting factor, and one or more constraints; determining a control input to the BHA that satisfies the objective function and the one or more constraints; and applying the control input to the BHA.

Abstract: A logging tool or sub (10) for downhole use comprises an elongate logging tool body (11); one or more moveable reaction members; and a locking member for the reaction members. At least one arm (12) at a first location is pivotably secured to the body (11) to be extensible therefrom and compressible towards the body (11); and at a second location spaced from the first location is pivotably secured to a locking member (18); and a stop member (22) fixed or fixable relative to the body (11). The locking member (18) defines a moveable end (19) remote from the second location and moveable relative to the arm (12) between at least a first position in which force tending to compress the arm (12) towards the body (11) causes the end (19) to move away from the stop member (22), and a second position in which force tending to compress the arm (12) towards the body (11) causes the stop member (22) to resist movement of the locking member (19) thereby preventing compression of the arm (12) towards the body (11).

Abstract: The present invention relates to an apparatus for providing an azimuth angle, i.e., an apparatus for calculating an azimuth angle using an angular rate sensed by a gyro sensor, which has rotated by an arbitrary angle, and an angle of rotation. The apparatus for providing an azimuth angle in accordance with one embodiment of the present invention may comprise a rotating member, an angular rate sensor mounted on the rotating member, and a driving unit configured to rotate the rotating member by a first angle. The angular rate sensor may be configured to sense an angular rate of the rotating member. The apparatus may further comprise an azimuth angle estimation unit configured to estimate an azimuth angle of the apparatus based on the sensed angular rate and the first angle.

Abstract: An alignment apparatus for aligning drilling machines, the alignment apparatus comprising a casing and mounting means. The mounting means allowing, in use, for a true north seeking sensing means to be aligned with the drilling machinery to be aligned. The alignment apparatus being capable of displaying azimuth and pitch information to a user, so that the drilling machinery can be aligned as required.

Abstract: A hand-held power tool device comprises an impact tool unit, an impact detection unit, and a blocking detection unit. The impact tool unit is configured to drive an insertion tool at least partially in at least one of a rotational fashion and a translatory fashion. The impact detection unit is configured to detect at least one impact parameter, such as linear acceleration running at least substantially parallel to a processing axis of the insertion tool. The blocking detection unit is configured to detect at least one blocking parameter, such as at least one an angular acceleration about the processing axis of the insertion tool. The impact detection unit and the blocking detection unit are formed at least partially as one-piece.

Abstract: Systems and methods for monitoring the tool rotation of a survey tool within a wellbore during a gyrocompassing survey measurement are provided. A plurality of signals from at least one accelerometer module of the survey tool is indicative of measurements of the Earth's gravitation vector taken by the at least one accelerometer module during the gyrocompassing survey measurement. The plurality of signals is used to calculate a tool face rate of change of the survey tool with respect to the wellbore during the gyrocompassing survey measurement.

Abstract: A numerical control device according to the invention is a numerical control device for a multi-spindle machine tool including a rotation axis and controlling a tool attitude relative to a machining workpiece, including a first storage device capable of recording a machining program; a second storage device capable of storing coordinate systems; and a central processing unit capable of executing the machining program, selecting a coordinate system suitable for machining from among the coordinate systems stored in the second storage device based on the tool attitude set by the machining program or an external input, and outputting data for machining the workpiece on the selected coordinate system.

Abstract: Systems and methods for well-drilling operations involving magnetic ranging with a rotating magnetic source are provided. In one embodiment, a system for determining a relative location of a magnetic source includes a three-axis magnetometer and data processing circuitry. The three-axis magnetometer may measure a time-dependent magnetic field caused by a magnetic source rotating about an axis, which may include two transverse components transverse to the axis and the data processing circuitry may determine a transverse angle of rotation of the measurements such that one of the two transverse components is ±?/2 radians out-of-phase with the other when the measurements are transformed by the transverse angle of rotation. The data processing circuitry may determine a spatial relationship between the magnetic source and the three-axis magnetometer based at least in part on the transverse angle of rotation.

Abstract: Methods and related systems are described for use for determining orientation of a measurement tool in a cased borehole. The measurement tool is deployed in a cased section of a borehole. The tool includes a volume containing a reference fluid having a first density, and a marker within the fluid having a different density. The position of the marker within volume containing the reference fluid is senses, and orientation information of the measurement tool is determined based at least in part on combining information relating to the position of the marker with prior recorded data representing orientation measurements made while the section of the borehole was not yet cased.

Abstract: Downhole tools are provided for measuring the inclination of a portion of a drill string. In certain embodiments, downhole tools for measuring inclination comprise a catch system for measuring inclination and a pressure pulse signaling system for communicating inclination measurement information to the surface. Catch systems for measuring inclination include a series of disc mounted on an upper shaft, each disc having a ball disposed thereon.

Abstract: A wireless communication network and method are described for enhancing cell-edge performance of a wireless transmit/receive unit (WTRU). The WTRU may establish a connection with a plurality of sites via respective downlinks (DLs). Each DL may include at least one DL component carrier (CC) that operates on a frequency that is the same or different than one or more of the other CCs. The sites may manipulate their transmit power for a particular CC operating frequency such that the distance from a particular one of the sites to its cell boundary may become larger by increasing its transmit power on the particular frequency, and the distance from at least one of the other sites to its respective cell boundary may become smaller by decreasing its transmit power on the particular frequency. Thus, a coverage overlap between different CC frequencies may be created while maintaining a frequency reuse pattern of one.

Abstract: A method and apparatus for estimating an orientation of a downhole device conveyed into a well on a conveyance device is disclosed. The apparatus includes a first sensor and a second sensor placed circumferentially spaced apart on the device to provide measurements relating to a selected downhole parameter. A processor is configured to estimate the orientation of the downhole device using a phase difference between the measurements of the first sensor and the second sensor.

Abstract: Downhole tools are provided for measuring the inclination of a portion of a drill string. In certain embodiments, downhole tools for measuring inclination comprise a catch system for measuring inclination and a pressure pulse signaling system for communicating inclination measurement information to the surface. Catch systems for measuring inclination include a series of disc mounted on an upper shaft, each disc having a ball disposed thereon.

Abstract: Methods and related systems are described for use for determining orientation of a measurement tool in a cased borehole. The measurement tool is deployed in a cased section of a borehole. The tool includes a volume containing a reference fluid having a first density, and a marker within the fluid having a different density. The position of the marker within volume containing the reference fluid is senses, and orientation information of the measurement tool is determined based at least in part on combining information relating to the position of the marker with prior recorded data representing orientation measurements made while the section of the borehole was not yet cased.

Abstract: A method of determining the dip or apparent dip of a section of a subterranean formation is described using the measurements of a borehole gravity meter and a dip-dependent model for the response of the gravity meter.

Abstract: An excavation device (1) and profile analysis of the excavation includes a device (1) realizing excavations of prismatic shape and having a frame (3) and a plurality of excavation wheels (2). The frame (3) includes a first upper section (3c), a second intermediate section (3b) and a third lower section (3a. The excavation wheels (2) are positioned at least within said third section (3a). Sensors (4) carry out the measurement of the section and/or the shape of said excavation; the sensors of measure (4) are directed towards the walls of said excavation and measure the profile of said excavation on at least two opposite walls. A method of analysis of a shape and/or a section of an excavation of prismatic shape in the soil includes excavation of the soil through a device (1) having a frame (3) and a plurality of excavation wheels (2).

Abstract: Methods and related systems are described for downhole positioning of sensors such as accelerometers, gyroscopes, tiltmeters and geophones. The sensor or sensors are mounted within the spherical rotor of a spherical motor such that the device can be actively positioned in one or more orientations by activating the spherical motor.

Abstract: Tools and methods for subsurface operations. Circuit arrangements providing a damping effect against undesired vibration effects on inertial data signals derived from inertial sensors disposed in a downhole tool.

Abstract: A method of monitoring verticality of a sinking caisson having a tip. A pole is inserted into the earth to a pole depth substantially corresponding to a desired final depth of the caisson tip, one or more levels are coupled to the pole, and an elevation of the levels(s) is established. Scales are carried on an interior surface of the caisson in spaced circumferential locations and in reference to the caisson tip, and the level(s) is applied to the scales to indicate heights from the caisson tip corresponding to the circumferential locations of the scales. Tip elevations corresponding to the circumferential locations of the scales are determined by subtracting the indicated heights from the established elevation of the level(s). Any tilt of the caisson is calculated from any differences among the determined tip elevations.

Abstract: A method for obtaining location information about a well as it is being drilled through a subsurface, comprises: providing at least one fiber optic cable deployed in a borehole within acoustic range of the well, the proximal end of the cable being coupled to a light source and a photodetector, the fiber optic cable being acoustically coupled to the subsurface formation so as to allow acoustic signals in the subsurface to affect the physical status of the cable, providing an acoustic source in the well, transmitting at least one light pulse into the cable, receiving at the photodetector a first light signal indicative of the physical status of at least one first section of the cable. The first section is selected so that the first light signal provides information about the position of the acoustic source, and outputting at least the information to a display.

Abstract: An orientation sensing apparatus includes a rotatable first member, an orientation sensor device fixed with the first member for generating orientation data relating to an orientation sensor device orientation, and a rotation sensor device for generating rotation data relating to rotation of the first member. A method for determining an orientation includes assembling a set of sensor data including the orientation data and rotation data and processing the set of sensor data to generate a set of corrected orientation data. The set of corrected orientation data includes the orientation data which has been corrected using the rotation data to reduce the effects of rotation of the first member and misalignment of the gravity sensor device. One or more sets of corrected orientation data may be processed to determine an inclination orientation of the first member or a toolface orientation of a second member which is connected with the first member.

Abstract: A gyroscopically-oriented survey tool, includes a housing having an axis. Three accelerometers are mounted in the housing with their axes set orthogonally. A first of the axes is aligned to the axis of the housing. A second of the axes is perpendicular to the first A third of the axes is perpendicular to both of the first and the second. Three gyroscopes are mounted pseudo-orthogonally in the housing with their axes set at relative angles of other than 90 degrees. None of the axes of the gyroscopes are mounted parallel to the axes of the accelerometers. This configuration permits data from the accelerometers to be used to check the quality of data from the gyroscopes.

Abstract: Casing or work string orientation indicating apparatus and methods. A system for indicating orientation of a structure in a wellbore includes an orientation indicating device responsive to fluid flow through the device, whereby fluid flow through the device at a selected flow rate produces a reduced pressure differential across the device when the device is at a preselected azimuthal orientation, compared to an increased pressure differential across the device produced by fluid flow through the device at the selected flow rate when the device is not at the azimuthal orientation. A method of detecting orientation of a structure in a wellbore includes the steps of: flowing fluid at a selected flow rate through an orientation indicating device interconnected to the structure; and observing a substantially constant pressure differential across the device during the flowing step, thereby indicating that the structure is at a predetermined azimuthal orientation.

Abstract: The present invention relates to a method of measuring the difference in alignment between a first plan position of an element (1) and a second plan position of an element, the method comprising the use of: i) at least one rigid or taut connection (4) extending between a first point (2) at the level of the first plan position and a second point (3) at the level of the second plan position, the first and second points being at an identical displacement from the element; and ii) one or more electrolevel gauges (5) provided on the or each rigid or taut connection, so as to measure the inclination of the rigid or taut connection.

Abstract: A method for determining an amount of creep for a tool on a cable and positioned in a well at an oilfield. The method includes moving a winch at a surface of the oilfield to effect movement of the tool below the surface in the well. The winch may then be stopped with the tool still in the well, but frequently the tool will continue to move, or “creep”, for some time after the winch is stopped. After the winch is stopped, data may be recorded indicative of movement of the tool. This data may then be used for the determining of the amount of creep.

Abstract: An apparatus for determining the orientation of a borehole at a point along the borehole, includes a tiltmeter for measuring the inclination of the borehole relative to the vertical, a vector magnetic sensor for measuring the amplitude of the component of the Earth's magnetic field along the axis of the borehole, and means for computing the orientation of the tubular sonde from the measurements of inclination and amplitude of the component of the Earth's magnetic field aligned with axis of the sonde.

Abstract: A device to measure minute displacement in rocks, including anchor deployment means, anchor registration means, and frame release means. Further including anchor units comprising a fixed anchor point, a reversible anchor actuator and a deployable anchor face capable of being deployed with a force of up to 2000 lbs.

Abstract: A method for surveying a subterranean borehole is provided. The method includes determining tool face angles at first and second longitudinal positions in the borehole. The method further includes processing the tool face angles to determine a change in borehole azimuth between the first and second positions. Exemplary embodiments of this invention provide a direct mathematical solution for the change in azimuth and therefore provide for improved accuracy and reliability of azimuth determination (as compared to the prior art) over nearly the entire range of possible borehole inclination, azimuth, tool face, and dogleg values.

Abstract: An alignment tool for adjustably positioning a boring bar relative to a spaced apart fixed location on a structural member including an elongated bar formed of a plurality of axially aligned and separable tubular members and having its opposite ends mounted to the boring bar and the fixed location, respectively. The length of the bar, hence the distance between the boring bar and the fixed location is adjustably selectable by means of telescopically mounted one of the tubular members. A first one of the tubular members receives therein a second one of the tubular members employing a thread interconnection whereby rotational movement of one tubular member relative to the other provides selection of the overall length of the tool. Multiple indicia associated with the outer circumference of each of the threadably interconnected tubular members provide a visual indication of the extent of the insertion of said second tubular member within said first tubular member, hence the overall length of the tool.

Abstract: The invention relates to a method of obtaining a developed two-dimensional image of the wall of a borehole. The method comprises the steps consisting in: measuring a primary physical magnitude in said borehole as a function both of depth and of azimuth; measuring a secondary physical magnitude in said borehole as a function of depth; establishing a relationship (ƒ) between said primary physical magnitude and said secondary physical magnitude; and deducing from said relationship values for said secondary physical magnitude as a function both of depth and of azimuth, which method makes it possible to reconstruct a two-dimensional image developed over the wall of a borehole concerning a secondary physical magnitude which is measured in said borehole as a function of depth only. The invention is particularly applicable to density imaging.

Abstract: A method and apparatus for use in creating a magnetic declination profile for a borehole. The method includes the steps of making a magnetic directional measurement at a longitudinal location in the borehole and at a magnetic measurement orientation, making a reference directional measurement at a reference measurement orientation, wherein there is a known orientation relationship between the magnetic measurement orientation and the reference measurement orientation, and obtaining a value of magnetic declination at the longitudinal location in the borehole using the magnetic directional measurement, the reference directional measurement and the orientation relationship.

Abstract: An apparatus for measuring the internal diameter of a wellbore for a wireline formation sample taking instrument, including an hydraulically actuated probe and back up shoe for selective engagement with the wall of a wellbore, an hydraulic pump and selectively controllable valves for selectively controlling extension and retraction of the probe and back up shoe, and an hydraulic fluid reservoir to supply hydraulic fluid to the pump for extending and retracting the probe and back up shoe. The reservoir includes a pressure compensator for balancing the pressure in the reservoir to an hydrostatic pressure in the wellbore. A position sensor is coupled to the compensator to determine its position. The position of the compensator corresponding to the fluid volume in the reservoir, the extension distance of the probe and back up shoe, and the internal diameter of the wellbore at the location of the probe and back up shoe.

Abstract: A method and apparatus are provided for estimating the cross-sectional shape and orientation of an earth borehole and the motion of a tool therein. The method and apparatus involve measuring the distance from the tool to the borehole wall at a plurality of locations around the periphery of the tool and fitting those measured distances to a predetermined shape function using a nonlinear parameter estimation technique to minimize the error between the estimated shape of the borehole and the measured distances. The method and apparatus may be used to estimate elliptical and higher order borehole shapes. Additionally, the method and apparatus may be used while drilling the borehole.

Abstract: The invention relates to a logging method and apparatus adapted for use in non-circular boreholes which, in one embodiment, comprises the use of a first and a second sonde, each sonde having: a pad adapted for contact with the borehole wall, at least a sensor on each pad, and an extendable arm for keeping the pad against the wall of the borehole. The first and second sonde produce measurements related to the same property of the formations, and the first and the second sonde are connected so as to keep the pads aligned with a 90.degree. azimuthal spacing therebetween.

Abstract: Methods and apparatus for mapping pipe and valve bores in a reactor pressure vessel (RPV) of a nuclear reactor are described. In one embodiment of the apparatus, a main bar and an adjustable chuck facilitate positioning of a digital indicator inside a valve bore. In the one embodiment, the main bar is rotatably coupled to the chuck, and the chuck includes four movable jaws. A data acquisition element, which includes a digital indicator, is movably coupled to the main bar and configured to move substantially coaxially to the main bar. To map the circumference of the bore, the main bar and the chuck are inserted into the valve bore, and the chuck is used to center the main bar coaxially within the valve bore. The data acquisition element is positioned at a first location along the main bar, and the main bar is rotated so that the digital indicator maps the circumference of the bore.

Abstract: A borehole survey is conducted at a drilling site S by a so-called Interpolated In-Field Referencing (IIFR) method in which: (a) absolute local geomagnetic field data is obtained by spot measurement of the earth's magnetic field at a local measurement site R which is sufficiently close to the drilling site S that the measurement data is indicative of the earth's magnetic field at the drilling site S but which is sufficiently remote from the drilling site S that the measurement data is unaffected by magnetic interference from the drilling site and other man-made installations; (b) time-varying geomagnetic field data is obtained by combining the absolute local geomagnetic field data with data indicative of variation of the geomagnetic field with respect to time obtained by monitoring variation of the earth's magnetic field with respect to time at a remote monitoring site P1, P2; (c) downhole magnetic field data is obtained by monitoring by means of a surveying instrument the magnetic field in the vicinity of th

Abstract: An eddy current device for inspecting a component, such as a closed surface area of a gas turbine engine or the like, includes an eddy current array circuit having an active face for positioning on a surface portion of the component during an inspection operation and backing on a surface of the eddy current array circuit opposite to the active face. The eddy current array circuit and backing are disposed over the operating face and expandable sides of an extendible pin. The extendible pin has a slot formed therein with interior side edges which narrow toward the operating face of the pin at a predetermined slope. The expanding pin is positioned to cause the angled sides to mate while engaging the interior angled sides of the round or shaped hole to cause the exterior sides of the expandable pin to expand outwardly a greater distance as the pin is pushed deeper into the hole. This causes the eddy current circuit to conform with the shape of the surface to be inspected.

Abstract: A method for well borehole survey is set out. A sonde supports X and Y accelerometers and X and & sensors on a rate gyro having a Z axis aligned with the sonde. On a slickline, or within a drill string, the sonde is used to measure four variables, these being G.sub.x and G.sub.y, A.sub.x and A.sub.z. This enables well azimuth and inclination to determined. Measuring depth enables a survey to be made.

Abstract: A method for well borehole survey is set out. A sonde supports X and Y accelerometers and X and & sensors on a rate gyro having a Z axis aligned with the sonde. On a slickline, or within a drill string, the sonde is used to measure four variables, these being G.sub.x and G.sub.y, A.sub.x and A.sub.z. This enables well azimuth and inclination to determined. Measuring depth enables a survey to be made.

Abstract: The present invention relates to a moving device for intervening inside small-diameter pipework. The technical field of the invention lies in constructing measurement apparatus for monitoring pipework and capable of moving along the inside of the pipework in substantially independent manner driven by thrust from the substance conveyed by the pipework acting on the device. According to the present invention, the device comprises a drive piston itself made up of at least two flexible and strong annular tractor cups and defining a sealed section of inside surface, and at least one third centering cup disposed between said two tractor cups. The supports for said cups are interconnected axially in pairs by respective traction cables associated with respective springs surrounding said cables, each spring bearing at each end against said supports of two consecutive cups, and serving to keep said cable under tension.

Abstract: A method is disclosed for determining wellbore azimuth accurately, notwithstanding the corrupting influence of axial and transverse magnetic field biasing error components.A reliable value of the axial magnetic field component (B.sub.x) is determined by minimizing the vector distance between B (as measured) and its expected value B. Preferably, this is accomplished utilizing a method of radicals to solve a quadratic equation.Given a reliable B.sub.x, the transverse magnetic field components (B.sub.x and B.sub.x) can be determined from taking a number of surveys as the drillstring is rotated about. B.sub.x and B.sub.x can be determined by utilizing the assumption that the transverse magnetic field components should remain invariant as the drillstring is rotated.

Abstract: In a downhole measuring caliper for oil well casings, comprising a circumferential array of radially extensible sensing fingers (30) between upper and lower sets of centralizing arms, the fingers are actuated through integral pre-stressed spring arms (34) engaged with an actuating member on the axis of the instrument; relative axial movement between the array of fingers and the actuating member causes the fingers to pivot into measuring contact with the tube wall. The number of sensing fingers is maximized and maintenance is simplified.

Abstract: A compound type cone mirror installed inside a sonde moving up and down in a borehole for observing the whole circumference of the hole wall at an arbitrary depth at a time, a combined mirror for locally observing the hole wall in detail, and an elevating sonde equipped with these mirrors are provided for observing the wall surface of a borehole In the ground. In the compound type cone mirror, a transparent truncated cone block the surface of which is finished by polishing is inserted into a concave portion or pierced hole having the same shape as said truncated cone block and formed coaxially in the axial direction in a transparent column block the surface of which is finished by polishing, and said inserting face is a mirror finished face. Moreover, in the combined mirror, a plane mirror slanted upward at 45.degree. to the axial direction is mounted onto the top face of the truncated cone block or column block of the compound type cone mirror.

Abstract: An apparatus and a method are provided for measuring the caliper of a borehole, and the standoff of a drilling tool from the walls of a borehole during a drilling operation. The apparatus includes three or more sensors, such as acoustic transducers arranged circumferentially around a downhole tool or drill collar. The transducers transmit ultrasonic signals to the borehole wall through the drilling fluid surrounding the drillstring and receive reflected signals back from the wall. Travel times for these signals are used to calculate standoff data for each transducer. The standoff measurements may be used to calculate the caliper of the borehole, the eccentricity of the tool in the borehole, and the angle of eccentricity with respect to the transducer position. The eccentricity and angle computations may be used to detect unusual movements of the drillstring in the borehole, such as sticking, banging, and whirling.

Abstract: In a method of inspecting heat exchanger tubes of a heat exchanger in which the heat exchanger tubes are fixed in position by spacers and serve to transfer heat from a first medium to a second medium that is fluid-tightly separated from the first medium, a measuring probe is introduced into an heat exchanger tube to be inspected. A wall section of the heat exchanger tube is subjected to an electromagnetic alternating field generated by the measuring probe resulting in local eddy currents within the subjected wall section. An eddy current sensor that is rotatable in the circumferential direction of the heat exchanger tube is guided in the longitudinal direction of the subjected wall section of the heat exchanger tube. A voltage signal induced by the eddy currents within the wall section is picked up with the eddy current sensor. The voltage signal varies locally as a function of the condition of the material of the wall section, the thickness of the wall section, and the presence of a spacer.

Abstract: A measuring tool including a device (4) for measuring the terrestrial magnetic field is inserted in a drill string (2) linking a drilling tool (3) to a surface installation. The method allows to be free from the disturbance affecting the measured terrestrial magnetic field and which is due for example to the drill string. It comprises stopping the tool during the progression thereof in the well in successive stop positions longitudinally spaced out in relation to one another, the angular position of measuring device (4) in these positions being random, and using a statistic calculation method for combining the different measurements and determining the disturbing field.

Abstract: In an automatic fastening machine 10 comprising a frame 12 for operating a workpiece 16 along a work centerline and having a drilling tool for drilling a hole in the workpiece, a bucking ram 26, and a milling tool 30 having a hole inspection assembly 22 mounted on the upper ram 88 thereof. The hole inspection assembly includes a hole probe assembly 24 that is movable axially along the work centerline to insert a probe member 25 into a position inside the hole in the workpiece. The probe is provided with a plurality of capacitor plates 25B that measure the peripheral extent of the hole to insure that the hole is drilled within a tolerance range and is also properly positioned on the workpiece before a fastener is inserted.