US 3587176 A
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United States Patent Pierre Schnerb lnventor  ReferencesCited [N gg g g UNITED STATES PATENTS P 1,399,423 12/1921 Cunningham 33/206 PM 3010214 11/1961 P 11 '1 33/215 Patented June28,l97l Priority Aug. 17, 1967 FOREIGN PATENTS France 1,248,887 11/1960 France 118007 1,540,476 8/1968 France Primary Examiner Robert B. Hull Attorney-Stevens, Davis, Miller and Mosher APPARATUS FOR DETERMINATION OF THE ORIENTATION OF A MOVING MEMBER, PARTICULARLY A DRILLING HEAD tion of a moving member, such as a drilling head used in well drilling, including a pair of pendulum units carried by the moving member, each being mounted orthogonally to the 8 Claims 7 Drawmg other and to the vertical axis of the member, and each adapted U.S. Cl 33/205, to transmit a signal representative of angular inclination to the /215 horizontal. An azimuthal direction sensing device provides a Int.Cl G01c 9/16, signal representative of the azimuthal orientation of a pivot E2 1 b 47/00 axis of one of the pendulum units. Calculating means and re- Field of Search ..33/215 (.2), lated instrumentation provide a resultant signal representative 215 (.3), 205.5 (E), 205 of the amount and direction of inclination of the member.
12, Pi/VDd/L UM ABSTRACT: Apparatus for determining the physical orienta- PATENTEUJU-28|91| 34587176 sum 1 or 5 PIERRE sum 5R1;
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Q9 Q 3 WW ATTORNEYS PATENTEflJuuzslsn 3.1581176 sum 5 BF 5 INVENTOR ATTORNEYS APPARATUS FOR DETERMINATION OF THE ORIENTATION OF A MOVING MEMBER, PARTICULARLY A DRILLING I-IEAD This invention relates to an apparatus or facility which makes it possible to know the direction of a borehole at any time without the need to lower and pull up a recording instrument.
Borehole direction can be defined by two anglesthe inclination of borehole direction to the vertical-i.e., the inclination of the drilling head to the vertical toand the bearing-Le, the angle which the vertical inclination plane makes with a known fixed horizontal direction which is taken as the datum direction and which is e.g. north.
The invention makes it possible to discover the amount of such inclination and such bearing from two other directly measurable angles, namely the angles a and B which two reference straight lines, associated with the drilling head, make with the horizontal plane, such lines both being perpendicular to the head axis and being perpendicular to one another.
Calculation shows that the sine of the inclination of the drilling head axis relatively to the vertical is obtained by vectorial breakdown of the sines of the two angles a and Bi.e., the resultant of two vectors extending along two straight lines and having the lengths sin a and sin [3 respectively is a vector oflength sin 0 in the vertical plane ofinclination of the drilling head (the vertical plane containing the drilling head axis).
Consequently, if i]; is the angle which such plane makes with the plane containing the drilling axis and one of the reference straight lines:
sina=sin0cosill (l) sinfi=sin0sin (2) thus completely determining the orientation of the vertical relatively to the drilling headi.e., to the drilling head axis and to the reference straight lines, from formulas l and (2):
sin 0=sin a+sin B (3) sin [3 tan Sin a Angles a and B can be measured by pendulums. Angle a may be determined by a pendulum which oscillates in a vertical plane, the plane containing a first reference horizontal straight line. Then, as the reference line changes its position from a horizontal position to one of inclination, the pendulum may be taken as having rotated relative to that line thru an angle 0:. However, for the plane of oscillation to be vertical the pendulum must be of the kind having 2 of freedom-Le, it
must be connected by a first shaft or spindle, called the inner shaft or spindle, to an intermediate member which is connected to the drilling head by a second shaft or spindle which is called the outer shaft or spindle and which extends parallel to the reference line. With the system in the balanced state, the inner shaft is horizontal and the plane of oscillation therearound is vertical.
To determine the bearing, a reference direction associated with the drilling head, such as the first reference line, is not a proper datum direction for the reason that torsion of the drilling rod makes the orientation of the drilling head unknown. Also, the angle which the datum horizontal direction makes with the direction associated with the head must be measured and this angle 41,, indicates rotation of the head in space. The bearing is then substantially:
z= l l o '11,, being measured by an extra instrument such as a magnetic compass or a directional gyroscope.
The apparatus according to the invention, which is based on the foregoing, comprises in combination two pendulums which have 2 of freedom and which are borne by the drilling head each of which is provided with an intermediate member or universal joint suspended on the drilling head around an outer shaft or spindle, and comprises a heavy mass oscillating around an inner shaft or spindle borne by the intermediate member, the inner shaft or spindle being perpendicular to the outer shaft or spindle, the outer shafts or spindles of the two pendulum mountings being perpendicular to one another and also being both perpendicular to the drilling head. Resolvers or other inductive transmitters are disposed one each on the inner shaft of one of the pendulums and deliver a signal representing the sine of the angle of inclination to the horizontal of the outer shaft of the corresponding pendulum. A calculating apparatus receives the signals from the transmitters of the two pendulums and delivers a signal proportional to the sine of drilling head inclination to the vertical, such signal being transmitted to ground level. A galvanometric indicator measures such signal or an indicator comprising a controlled instrument gives the angle of inclination.
The computer also delivers the angle r11 which the vertical plane of inclination of the drilling head makes with the first reference line. To determine the bearing of the vertical plane of inclination of the drilling head to a datum direction, such as north, the apparatus also comprises a directional instrument, such as a magnetic compass or a gyroscope, which delivers the angle made by the datum direction with a plane which is associated with the drilling head and which is parallel to the first reference line. The directional instrument is suspended by a universal mounting in such head. The apparatus also comprises a differential which receives the angle between the vertical plane of inclination of the drilling head with the first reference line as delivered by the computer, and the angle indicated by the directional instrument, the differential deliverin g the difference between these two angles. Provided that the inclination angle 0 of the drilling head is relatively small, the resulting angle is a good approximation to the bearing.
If the computer delivers the angle ill as rotation of a shaft and if the signal 41,, transmitted by the directional instrument goes to a repeater which operates a shaft rotating through the angle 41,, the differential can be conventional mechanical differential and is then mounted between the two shafts and comprises a third shaft which rotates through th -ill and drives an electric transmitter whose signal is transmitted to ground level.
Alternatively, the differential can be a differential transmitter which is disposed on the shaft which the computer rotates through the angle ([1 and which receives from the directional instrument electrical signals representing the angle h indicated by the directional instrument. This differential transmitter transmits signals representing the bearing to ground level.
If drilling head inclination 6 is fairly large, formula (5) becomes inconvenient, for the bearing, in the form of the angle made by the datum direction with the vertical plane passing through the drilling head axis, is an angle in the horizontal plane. Also, the angle 41,, between the datum direction and the locating direction associated with the head is measured in the horizontal plane. To this end, the measuring instrument, such as a compass, is suspended pendulumfashion and the locating direction associated with the head, the zero alignment of the compass, is bound to be horizontal. If the compass suspension were such that rotations of the head around its axis caused equal rotations of the compass casing and of its zero alignment around the vertical, the angle between the zero alignment and the vertical plane of inclination of the drilling axis, such angle being in the horizontal plane, would be equal to the angle ill between the first reference line and such plane of inclination, and a compass indication would be such that formula (5) would be applicable. Actually, however, the compass is mounted-universally and its indication is not as in the previous case but is:
l 'fil o in which e denotes the universal-joint error (nonhomokineticity), which increases in proportion as the angle 6 increases. Consequently, if the universal joint error is not allowed for- -and it can be neglected only when the angle 0 is small-what is measured is llllll' and so the value obtained for the bearing differs from the true value by e.
IfilJ'=1l1e, the azimuth is given correctly by the formula:
The suspension system can be chosen with a view to simplifying calculation. For instance, if the compass suspension is devised like the suspension of a pendulum whose outer shaft is the first reference line, and if the zero alignment direction is parallel to such line when the head axis is vertical-ie, when the compass indicates the angle of north with the vertical plane passing through such line, then:
The system further requires an electrical or electromechanical computer which can deal with this formula and help to determine ill and which can, for instance, comprise tangent calculators of the kind described in the applicant's French Pat. application No. PV 3390 (8&0) of7 Aug. 1967 for Tangent calculating facility."
Each of the pendulums can take the form of a weight suspended universally in a casing containing a high-density liquid, so that the weight of the pendulum mass is substantially compensated for by buoyancy. In such case, as will be perceived, pendulum density must be nonuniform in order to respond as a pendulum under gravity force.
The calculator can take the form of a slave resolver whose two stator windings in quadrature are connected to the two transmitters disposed on the inner shafts of the two pendulums so as to produce two AC fields in quadrature whose amplitudes represent the sines of the angles of horizontal inclination of the outer shafts of each of the two pendulums, and they therefore produce a resultant field whose amplitude represents the sine of vertical inclination of the drilling head and whose angles with the axes of the two stator windings are equal to the vertical angles made by the head with the respective outer shafts of the corresponding pendulums. The receiver then comprises an amplifier whose input receives the signal of a first rotor winding of the resolver, a servomotor energized by the amplifier output and driving the resolver shaft via a reducer, and, if need be, a tachometer generator providing to the amplifier input a signal proportional to the speed of rotor rotation so as to damp motor and resolver movement. Consequently, the resolver rotor is always so positioned that the signal delivered by its first winding remains zero, so that the first winding keeps its axis perpendicular to the resultant field, whereas the second rotor winding, which is in quadrature to the first rotor winding, has its axis parallel to the resultant field and delivers a signal proportional to the amplitude of such field and therefore to the sine of the vertical inclination angle of the drilling head axis. The position of the controlled resolver shaft indicates the angle ill since its second rotor winding, whose axis is parallel to the resultant field, cooperates with the first stator winding to form an angle reproducing the vertical angle between the drilling head axis and the first pendulum outer shaft. In the absence of cardan error correction, the resolver shaft is connected to the differential. If such a corrector is provided, the resolver shaft is connected to the corrector.
An exemplary nonlimitative description of an embodiment of the drilling control apparatus according to the invention is given hereinafter with reference to the accompanying drawings wherein:
FIG. 1 is a diagrammatic sectioned view of the drilling head;
FIG. 2 is a diagrammatic sectioned view of the complete apparatus according to the invention;
FIG. 3 is a view of a pendulum sectioned in a plane containing its inner suspension shaft or spindle;
FIG. 4 is a view in section in a plane containing the outer suspension shaft of the pendulum;
FIG. 5 is the circuit diagram of the apparatus, and
FIG. 6 is the circuit diagram of the connection to a magnetic compass;
FIG. 6a is the diagram of an embodiment including a mechanical differential.
Referring to FIG. I, a drilling head 1 comprises an electric motor 2 for driving a tool 3. Motor 2 has a hollow shaft 4 connected to a tube 5 which forms a drilling rod and which is extended by a flexible tube through which liquid goes to shaft 4. The motor is loaded by a cylindrical member 6, called the rod weight, which extends like a ring around the rod. Motor supply wiring 7 extends in the thickness of the wall of tube 5 and of the subsequent flexible tube. 1
The control facility according to the invention has the general reference 8 and is embedded in the weight 6. Wiring 9 for energizing the facility 8 and transmitting signals therefrom extends in the thickness of the wall of a flexible tube just like the motor supply wiring 7.
Referring now more particularly to FIG. 2, the facility 8 comprises a tube 10 which helps to protect the facility against high pressure and which is hermetically closed at the top by a plug 10a; a lead-through for wiring is provided at a place 11.
The tube 10 receives two pendulum units 12a, 12b. The moving part of each pendulum unit comprises an inner shaft or spindle l3 pivotally mounted in a skeletonized casing 14 visible in FIGS. 3 and 4. Rotor 15 of an inductive transmitter 16a and 16b respectively is rigidly secured to shaft 13, and two hollow members 17 which are FIGS. of revolution around the shaft 13 and which are unbalanced by weights 18 are disposed symmetrically on both sides of the rotor 15.
The casing 14 acts as an intermediate suspension member or gimbal ring. The casing 14 is rotatable, with the interposition of two bearings 20 disposed in instrument casing 22 and of two journals 19, around an outer shaft or spindle which is perpendicular to the inner shaft or spindle. Casing 22 is filled with a liquid and communicates with expansion bellows 23 for accommodating the expansion of the liquid when the temperature rises. A cover 24 protects bellows 23. Advantageously, the weights l8 and the density of the liquid are such that the weight of the moving system is exactly compensated for by buoyancy at an average temperature.
The outer shafts of the two pendulum units 12a, 12b are both perpendicular to the axis of the tube 10 and therefore to the drilling head axis, as well as being perpendicular to one another.
Spiralled wires (not shown) energize rotor winding 25a of transmitter 16a from conductors borne by casing 14. The stator 26 of transmitter 16a is borne by casing 14 and has a winding 270 which can be seen in FIG. 5 and the windings are so arranged that rotor winding 25a and stator winding 27a have their field axes perpendicular to one another when the outer suspension shaft is horizontal (a then being zero). The connections between the windings of the transmitter 161: and the rotating casing 14 are made by way of a number of conductive rings 29 disposed on two insulating cylindrical sleeves 21 which are coaxial of casing 14 and on which rub sliders 30. Winding 25a is taken to an adjustable tap 31a of an AC supply 31. Tap 31a is adjusted so that the voltage induced in winding 27a is equal to a voltage taken as unity, defined by another tap 310 of supply 31, when the axes of winding 25a and winding 27a are parallel to one another. Winding 27a therefore delivers a voltage which, measured with the unit as just defined, is equal to sin a.
Pendulum unit 12b is mounted similarly, its inner shaft or spindle 13 being rigidly secured to rotor winding 25b of inductive transmitter 16b which is energized from a tap 31b of supply 31, so that stator winding 27b of transmitter 16b delivers an AC voltage equal to sin 6 when unity is defined by tap 31c of supply 31.
The inductive transmitters 16a, 16b are connected to a unit 32 (FIG. 2) comprising a resolver 33 having two stator windings 34a, 34b (FIG. 5) in quadrature, winding 34a being connected to winding 27a and winding 34b being connected to winding 27b. The rotor of resolver 33 comprises two rotor windings 35a, 35b in quadrature. Winding 35a is connected to the input of an amplifier 36 whose output energizes a motor 37 driving the rotor of resolver 33 via a reducer 37a, said motor, if necessary for damping purposes, driving a tachometer generator 37b whose output is connected to the input of the amplifier 36. Motor, reducer and tachometer generator are commonly sold in the same block.
Windings 34a, 34b therefore produce AC fields at right angles to one another and with amplitudes representing the signals sin a and sin B. Their resultant has an amplitude representing sin and makes with the direction of the sin a field an angle equal to the angle ill made by the plane of inclination of the drilling head axis with the outer shaft of pendulum unit 12a.
The rotor of resolver 33 takes up an angular position such that winding 350 has its axis perpendicular to the resultant stator field, the current which energizes motor 37 then being zero. Winding 35b therefore has its axis extending in the direction of the resultant stator field and measures the same exactly. Conductor 38 connected to winding 35b therefore carries a signal representing sin 0; conductor 38 extends in the thickness of the wall of the flexible tube connected to the drilling head and energizes an indicating or recording facility at ground level. Another conductor 38a also disposed in the thickness of the tube serves to transmit to ground level the unit voltage delivered by tap 310 of power supply 31. if the impedances which the conductors 38, 38a supply at ground level are equal, currents are proportional to voltages and to line losses. Consequently, the relationship between the two voltages as measured at ground level is the same as the relationship between the voltages transmitted from the boreholei.e., sin 0despite line losses. The voltage supplied via conductor 380 can be used to calibrate a galvanometric indicator or recorder so that the same indicates the sine of the inclination without any line error.
An instrument comprising an inductive sine transmitter can also be used at ground level, being energized via conductor 38 and delivering, if the unit is the voltage delivered by conductor 38a, a signal equal to the sine of the angle displayed by its rotor. The transmitter is so controlled that the deviation of this signal from the signal carried by conductor 38i.e., sin 6- stays zero, so that the rotor of the transmitter indicates the drilling head inclination angle 0 on a linear scale.
Also, the axis of winding 35b makes with the axis of winding 34a an angle equal to the angle 1!; between the plane of inclination of the drilling head axis and the outer shaft of pendulum unit 12a, and the angle so made is signaled by the rotation angle of resolver shaft 33 and is corrected by a universal joint or cardan error corrector 39 which drives through the angle 11: the rotor of a'differential synchro 40.
The stator of synchro generator 40 comprises, as can be seen in FIG. 6, three stator windings 4850 connected to the three stator windings l53 of a synchro 54 whose rotor is driven by the coupling 55 to the magnetic compass or by a repeater reproducing the indication thereof. The three stator windings 48-50 produce an AC field which makes with the axis of one of the windings, for instance, the winding 48, the same angle as thedirection of north makes with the axis of the corresponding winding 51 of the stator of synchro 54. The compass and its synchro 54 are also so adjusted that the field axis of winding 51 which serves as zero alignment of the compass, is parallel to the outer suspension shaft of pendulum unit 120. Consequently, the indication transmitted to the three windings 48-50 of the stator of transmitter 40 represents the angle ill, which north makes with the vertical plane of the outer shaft of pendulum unit 12a, such angle including the cardan error 2. Since the rotor of the transmitter 40 has rotated relatively to its stator through the angle ill including the cardan error and thus represents the angle which the plane of inclination of the drilling head makes with the outer shaft of pendulum unit 120, one of the windings 5557 of the rotor of transmitter 40, for instance, the winding 55 makes the angle ill ili with the stator field. Synchro 40 therefore delivers a signal representing this difference which is the bearing from north of the vertical plane passing through the drilling head axis, synchro 40 transmitting such signal to ground level via conductor 58. As previously indicated and as shown by FIG. 6a, the position of the resolver shaft 33 (corrected in 39) may be transmitted to one sun gear of a mechanical differential 60, the other sun gear of which rotates with the system 55. Thus, the azimuth may be picked up from the planetary carrier of the differential and transmitted by a further synchro 61.
The transmitter disposed on the compass need not necessarily be a synchro and can be some equivalent facility, such as a transmitter having instead of a rotor a stationary winding combined with a rotating magnetic circuit.
The compass need not necessarily comprise a separate transmitter and in that case is embodied by a facility directly sensitive to the earths magnetic field and delivering signals equivalent to the signals delivered by a synchro.
If the instrument delivering a directional reference is a gyroscope and not a magnetic compass, the bearing data, instead of being north, can be any predetermined direction.
The invention must not of course be considered as being limited to the embodiment described and shown but covers all variants. For instance, the computer, the cardan error corrector or some of their parts can be disposed at ground level and not below ground near the measuring instruments, in which event the input values of the elements concerned are transmitted to ground level.
Similarly, electrical transmissions with or without slave features can be used instead of direct mechanical transmissions; conversely, appropriate electrical transmissions can be' used instead of mechanical connections. Also, electrical transmissions can, for instance, for installation or available power reasons, be supplemented by supplementary relays or slave systems. For instance, the magnetic compass installation can comprise a repeater which reproduces the indication and drives the transmitter delivering this information to the computer.
1. An apparatus for determining the physical orientation of a moving member, of use more particularly for controlling drilling operations, such apparatus comprising two pendulum units, each having outer shafts or spindles mounted on the moving member along an axis orthogonal to an axis of the member whose orientation is to be determined, a suspension member mounted for rotation about the axis of said shafts or spindles, a pendulum and an inner shaft connected to the pendulum and mounted on said suspension member for rotation about an axis orthogonal to the first-named axis and normally orthogonal to the second named axis; two inductive transmitters connected each to the inner shaft of one of the pendulum units and delivering a signal representing the sine of the angle of inclination from the horizontal of the outer shaft of the corresponding pendulum; and a calculating device receiving the signals from the two transmitters and providing a signal representing the sine of the angle of inclination from the vertical of the second named axis.
2. The apparatus specified in claim 1 further comprising a cardan error corrector which receives said signal from the calculating device and which calculates the bearing correction.
3. The apparatus specified in claim 1 wherein each of the pendulum units comprises a casing enclosing said suspension member and pendulum containing a liquid to reduce the weight of the pendulum on the shaft mountings.
4. The apparatus specified in claim 1 wherein the calculating device comprises a resolver having two rotor windings in quadrature and also two stator windings in quadrature which receive, from the two transmitters disposed on the pendulum inner shafts respectively said signals representing the sines of the angles of inclination from the horizontal of the pendulum outer shafts, the calculating device further comprising an amplifier whose input receives the signal from the first rotor winding of the resolver, a servomotor energized by the amplifier output and driving the resolver shaft; the output of the second rotor winding supplying a signal representing the sine of the said angle of inclination of the second named axis.
5. The apparatus specified in claim 1 wherein the calculating device is borne by the moving member.
6. The apparatus specified in claim 1 further comprising an azimuthal direction sensing instrument, which is gimbalmounted in the moving member; and a differential which receives from the calculating device the angle between the vertical plane of inclination of the second named axis and the of the azimuthal.
8. The apparatus specified in claim 6 wherein the differential is a differential synchro whose rotor is disposed on a shaft connected to the calculator to rotate like the plane of inclination of the moving member axis and which receives from the azimuthal direction sensing instrument signals representing the azimuthal orientation of a predetermined transverse axis fixed in saidmoving member.
UNITED STATES PATENT ()FE1ICE CERTIFICATE OF CORRECTION 3,587,176 Dated June 28, 1971 Patent No.
Inve t Pierre Schnerb It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
 Assignee Association Des Ouvriers En Instruments De Precision,
Signed and sealed this 2nd day of May 1972.
ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR.
Commissioner of Patents Attesting Officer FORM POI-1050 (IO-69] USCOMM-DC 60376-P69 u 5 GOVERNMENT PRINTING OFFICE 1969 0-356-334