WO2001011191A1 - Procede et dispositif de transmission de donnees dans un train de tiges - Google Patents

Procede et dispositif de transmission de donnees dans un train de tiges Download PDF

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Publication number
WO2001011191A1
WO2001011191A1 PCT/US2000/016293 US0016293W WO0111191A1 WO 2001011191 A1 WO2001011191 A1 WO 2001011191A1 US 0016293 W US0016293 W US 0016293W WO 0111191 A1 WO0111191 A1 WO 0111191A1
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WO
WIPO (PCT)
Prior art keywords
drill stem
drill
location
data
stress
Prior art date
Application number
PCT/US2000/016293
Other languages
English (en)
Inventor
Arthur F. Kuckes
Original Assignee
Vector Magnetics, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vector Magnetics, Inc. filed Critical Vector Magnetics, Inc.
Publication of WO2001011191A1 publication Critical patent/WO2001011191A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/01—Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
    • E21B47/14—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling using acoustic waves
    • E21B47/16—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling using acoustic waves through the drill string or casing, e.g. by torsional acoustic waves

Definitions

  • the present invention relates, in general, to data transmission in drilling systems, and will be described herein for convenience in drilling systems of the type used in gas and oil well drilling.
  • the invention also relates to the generation of electrical power downhole in such systems. More particularly, the invention relates to a method and apparatus for modulating the motion of a drill stem at one location on the stem and for detecting the modulation at a second location for establishing communication between the locations, and further to a method and apparatus for generating electrical power downhole and for supplying such power to downhole electronic equipment such as the foregoing communications apparatus.
  • the need for better telemetry methods and apparatus for communicating data downhole from surface equipment to downhole drilling equipment or for communicating uphole from such equipment is widely recognized.
  • drilling of deep boreholes is carried out with a pressurized drilling fluid which can be used to drive drilling equipment at the bottom hole assembly and to carry away the debris produced by the drilling operation.
  • the dominant method for borehole communication m use at the present time involves the generation of pressure pulses m this drilling fluid.
  • pressure pulses are generated downhole in the drilling fluid, as by periodically interrupting the fluid flow, and the resulting pressure pulses are carried m the fluid and are detected at the surface.
  • the most serious deficiency of such pressure pulse systems is the very slow data rate, at which information can be transmitted; in typical systems the rate is limited to approximately one bit per second.
  • Electromagnetic communication systems have been developed m which drill string currents are generated and modulated, and these have a higher data rate than is possible with pressure pulse systems; however, these systems have a very limited range.
  • a drill stem data communication system m accordance with the present invention has several aspects which may be utilized separately or m any combination to meet the particular needs of a borehole drilling situation.
  • the invention relates to a method and apparatus for transmitting data between locations along a drill stem.
  • the invention is directed to the transmission of data from a downhole location along the drill stem to a surface location.
  • the invention is directed to the transmission of data from a surface location along the drill stem to a location m the borehole.
  • the invention is directed to the transmission of data from a downhole location to a surface location, and then from the surface back to the downhole location to provide a feedback control of downhole equipment.
  • the invention includes a method and apparatus for generating electrical power for ⁇ ownhole electronic equipment wnich is used to sense downhole conditions, for communications equipment for receiving and transmitting data signals, and for downhole electronic controls for directional drilling m the borehole.
  • all these aspects are combined m a unique and novel drilling control system.
  • the present invention relates to methods and apparatus for producing or modulating torsional or axial stress and/or motion m a drill stem for transmitting data uphole and downnole m a oorehole being drilled.
  • the invention relates to methods and apparatus for producing or modulating torsional stress and/or rotation by varying the rate of rotation of a drill stem to transmit data between two spaced locations along the drill stem.
  • the invention also relates, m another embodiment, to methods and apparatus for producing axial stress waves m the form of axial motion or of variations m axial tension or compression m a drill stem to transmit data oetween locations.
  • the invention relates to methods and apparatus for generating electrical power downhole for the foregoing apparatus m response to the rotation of the drill stem.
  • the motion of the drill stem is modified at one location, such as at a downhole or an uphole location, to create motion or stress variations m accordance with the data that is to be transmitted, and sensors and circuits are provided at the other location which are responsive to such variations to recreate the transmitted data for monitoring and for control purposes .
  • a borehole communication system m accordance with one embodiment of the invention includes surface apparatus for generating data signals to be transmitted downhole.
  • a sensor at a second location along the drill stem such as at the bottom hole assembly, responds to the stress or motion variations to produce corresponding data signals which are used at the second location for control purposes.
  • the drill stem is rotated by a drive motor at the surface, and data signals are encoded and used to vary the rotational speed of the motor to impose torsional stress variations on the drill stem as its rate of rotation is modulated. The resulting changes m drill stem rotational speed can be detected at the downhole location and decoded for regulating the drilling operation.
  • the downhole sensor preferably includes accelerometers or apparent earth's field sensors.
  • the downhole sensor may be an alternator coupled to the drill stem and driven by the stem rotation to produce an alternating output current having a frequency corresponding to the rate of rotation.
  • an alternator may include a stator surrounding the drill stem and incorporated m a drill stem stabilizer which is fixed to the borehole wall at the downhole location.
  • a stabilizer is illustrated, for example, m U.K. Patent No. 2,177,738B entitled "Control of Drilling Courses m the Drilling of Boreholes" wherein stabilizers are utilized for dynamic control of the bend of the drill string to control the direction of drilling.
  • the alternator rotor may consist cf plural magnets located on the drill stem.
  • the rotation of the drill stem produces an AC current output from the stator windings, and this current is rectified to produce a direct current for powering downhole circuitry.
  • Changes m the rate of rotation due to varying torsional stresses produced at the surface for example m response to changes m the motor drive current, cause changes m the frequency of the output current from the downhole alternator, which changes can be detected and demodulated to produce data signals corresponding to the data oemg transmitted from the surface location.
  • the data signals may then be used to provide instructions to the downhole equipment.
  • the rotation of a rotary drill stem can be modulated by turning the drive motor on and off m a pattern corresponding to the control signals to be transmitted, and the on and off pattern is detected at the bottom of the drill hole to provide suitable control signals.
  • rotation of the drill string is modulated downhole by a brake or by an hydraulic or electromagnetic clutch arrangement.
  • the communication system includes a data source downhole which is responsive to selected downhole parameters to produce data signals to be transmitted to a surface location.
  • a data source may include sensors located at a drill collar, and at the drill head for example, to measure conditions of operation downhole and to produce corresponding output signals.
  • These data signals are processed to modulate the rotation of the drill stem, as by activating and deactivating a mechanical or electrical brake or clutch for applying or releasing a variable drag force to the drill stem to change its rate of rotation.
  • This creates torsional stress waves which are propagated along the length of the drill stem and are sensed at the surface, as by strain gauges, accelerometers or the like.
  • the surface sensor output is then demodulated to provide data signals at the surface location corresponding to the data signals produced downhole.
  • rotational, or torsional stress waves are generated by a hydraulic clutch connecting the drill stem to a rotary drill head.
  • the clutch is hydraulically or electrically energized to drive the drill head.
  • torsional systems for modulating and launching stress waves and rotational motion in the drill stem serve to propagate encoded digital information along the steel of the drill string. These waves are then detected at a remote location and are processed to recover the encoded digital data.
  • torsional waves can be transmitted along a drill string, for m the past the performance of drill bits has been studied by noting at the surface the time variation of torsional noise stresses generated by the drill bit during operation. Such noise stresses can be avoided while using the communication system of the present invention by removing the weight of the string from the drill bit while transmitting data.
  • the torsional stress modulation used for the transmission of data can be carried out m a narrow band frequency channel wnere there is little noise from the operation of the drill bit.
  • Axial stresses, whicn include axial stress waves as well as axial motion, may also be used for drill string communication, m accordance with another embodiment of the present invention.
  • both axial stress waves and axial and motion are generated at the earth' s surface by raising and lowe ⁇ n ⁇ the drill string m the borehole in prescribed incremental lifting or lowering steps.
  • the raising and lowering of the drill stem releases pressure or tension m bursts to produce axial stress pulses, or shock waves, which are detected as motion or stress variations at a remote location by axial accelerometers.
  • the output signals from the accelerometers are demodulated and twice integrated with respect to time to recover the encoded data from the surface.
  • Axial stress waves may also be produced downhole for use m transmitting data to the surface.
  • standard mud pulsing which conventionally is detected at the surface by measuring pressure variations m the drilling fluid, can also be sensed uphole by detecting associated axial stress changes m the drill stem.
  • sensors detect data relating to conditions and parameters of operation downhole and at the drill head and the data are converted to encoded electrical signals which are transmitted along the electrically conductive drill stem to a transducer located, for example, 100 meters above the sensors at the drill head.
  • the transducer may be an hydraulic pressure modulator which is controlled by the encoded data signals to mechanically produce axial stress pulses m the drill stem. These pulses can be m the form of axial motion imposed on the stem cr axial stress imposed on the stem, to produce variations m tension or compression. Such variations propagate along the drill stem and are sensed at a second location, such as at the surface.
  • the hydraulic pressure modulator preferably includes a pressure chamber and a release chamber, both containing hydraulic fluid. Downward pressure of the drill stem during drilling causes fluid to flow into the pressure chamber from the release chamber.
  • the drill stem is lifted at tne surface, causing the lower 100 meters of the stem to be supported by the transducer and thus to exert a force which pressurizes the hydraulic fluid m the pressure chamber.
  • This fluid can then be released from the pressure chamber m incremental bursts by a solenoid valve which is rapidly opened or closed under the control of the encoded data signals.
  • a solenoid valve which is rapidly opened or closed under the control of the encoded data signals.
  • the opening of the valve and consequent release of the 100 meter section of drill stem reduces the tension m the portion of the drill stem above the transducer, and closing the valve restores the tension.
  • a suitable sensor such as a strain gauge is located on the drill stem at the surface to measure received axial shock waves, and the resulting stress signals are then demodulated to reproduce at tne surface the downhole data signals.
  • the hydraulic pressure chamber m the transducer may be pressurized by a fluid pump, rather than by the weight of the drill stem.
  • data to be transmitted downhole is encoded at the surface, and is used to control a surface hydraulic transducer which generates axial stress or shock waves for transmission downhole.
  • a hydraulic pump is operable to pump hydraulic fluid into a pressure chamber at or near the earth's surface. The weight of the drill stem and drill head is carried by the hydraulic fluid m this chamber, thereby placing the fluid under high pressure.
  • a solenoid valve controlled by the encoded data is operated to release hydraulic fluid from the pressure chamber m incremental steps or bursts, each of which serves to drop the drill stem a short distance to produce corresponding axial shock waves, or pressure pulses.
  • shock waves travel along the length of the drill stem m an axial direction and are detected by accelerometers or by strain gauges located near the bottom of the borehole. The variations m stress so detected are converted to electrical signals which are demodulated to produce corresponding data control signals at the downhole location.
  • data communication m a borehole is carried out by variations m torsional stress waves produced by variations m drill stem rotation at the surface or downhole, by axial stress waves generated at the surface, by axial stress waves generated downnole, or by a combination of these tecnniques.
  • data transmission between the surface and a downhole location is preceded by a suitable command sent from the surface to signal the downhole electronics to start a data transmission, or to prepare to receive a data transmission.
  • a suitable command sent from the surface to signal the downhole electronics to start a data transmission, or to prepare to receive a data transmission.
  • a suitable command sent from the surface to signal the downhole electronics to start a data transmission, or to prepare to receive a data transmission.
  • a suitable command sent from the surface to signal the downhole electronics to start a data transmission, or to prepare to receive a data transmission.
  • a suitable command sent from the surface to signal the downhole electronics to start a data transmission, or to prepare to receive a data transmission.
  • a specific sequence of starting and stopping of the fluid pumps and/or drill stem rotation can be used, or a sequence of lifting or lowering the drill stem can be used to activate the downhole electronics.
  • the sequence is specific to the encoded command, and after the command is given, transmission of encoded data begins from the surface or from
  • the system of the present invention is particularly well suited to the establishment of communication links along a drill stem m the controlled rotary drilling of directional boreholes, not only because torsional or axial stress can easily be induced, but because the rotation of the drill stem can be used as e source of power for the control circuitry downhole.
  • Fig. 1 is a diagrammatic illustration of a rotary drilling system for oil/gas wells, incorporating a downhole stress modulator and a surface detector unit for data transmission m accordance with the present invention
  • Fig. 2 is a diagrammatic illustration of an hydraulically controlled drill stem stabilizer brake for producing torsion modulation for the system of Fig. 1;
  • Fig. 3 is a cross-sectional illustration of an MWD drill string control unit with an hydraulic controller for the drill stem torsion modulator of Fig. 2, and further illustrating the provision of a downhole alternator;
  • Fig. 4 is a cross-sectional illustration of a second embodiment of a torsional stress modulator for use m the system of Fig. 1, utilizing mertial stress modulation;
  • Fig. 5 is a cross-sectional view taken along line A-A of Fig. 4, showing a brake for producing stress modulation;
  • Fig. 6 is a cross-sectional illustration of a surface detector unit for the system of Fig. 1;
  • Fig. 7 is a diagrammatic illustration of an alternative surface detector unit;
  • Fig. 8 is a diagrammatic illustration of another embodiment of the invention, incorporating a surface axial stress modulator and a downhole sensor; and
  • Fig. 9 is a cross-sectional diagrammatic view of downhole electronics for an axial stress detector
  • Fig.10 is a cross-sectional view of a first embodiment of a downnole stress wave transducer for use m the system of Fig.l;
  • Fig.11 is a cross-sectional view of a second embodiment of a downnole stress wave transducer;
  • Fig. 12 is a cross-sectional view of a fluid pump for supplying hydraulic fluid to the stress wave transducer of the invention;
  • Fig. 13 is a cross-sectional view of a surface stress wave transducer
  • Fig. 14 illustrates m partial cross-section another embodiment of a torsional stress modulator utilizing a hydraulically actuated clutch
  • Fig. 15 is a cross-sectional view taken along lines 15-15 of Fig. 14;
  • Fig. 16 illustrates m partial section a modification of the embodiment of Fig. 14, wherein a torsional stress modulator utilizes an electrically actuated clutch; and
  • Fig. 17 illustrates m partial cross-section a torsional stress modulator utilizing another form of an hydraulic clutch.
  • a rotary deep well directional drilling system 10 such as that which may be used for drilling o l or gas wells.
  • the drilling system includes, for example, a drilling derrick 12 mounted on a drill platform 14 located on the earth's surface 16.
  • the derrick supports a drill string 18 which extends into a borehole 20 m the earth, the drill string being supported by a top drive motor 22 secured to the derrick 12 by a suitable cable and elevator lifting mechanism generally indicated at 24.
  • the top drive motor 22 receives power from an alternating current source 26 through a motor control circuit 28 by way of line 30, as is conventional m the petroleum industry.
  • the drill string 18 includes, at its distal end, a bottom hole assembly (BHA) 31, which includes a drill bit 32 driven by rotation of the drill stem 18 by the motor 22 to produce the borehole 20. Carried by the drill stem near the drill bit 32 is a measurement while drilling (MWD) control unit
  • the present invention provides a drill stem stress modulator 40 m a downhole location near the control unit 34.
  • the modulator 40 preferably consists of a mechanism for generating either axial or torsional stress waves on the drill stem m response to data signals produced by the control unit and whicn are to be transmitted to an uphole location.
  • a suitable detector 42 which may be m the form of a strain gauge or an accelerometer, for example, is located uphole, and produces corresponding output signals on line 44 representing the data signals generated at the modulator 40. These output signals are supplied to the computer 36 which processes the data m a well-known manner to provide outputs to a display 46 and/or by way of line 48 to the motor controller 28 for regulating the operation of the rotating drill string 18.
  • the computer 36 processes the data m a well-known manner to provide outputs to a display 46 and/or by way of line 48 to the motor controller 28 for regulating the operation of the rotating drill string 18.
  • the torsional stress modulator 40 can be transmitted accurately along the drill stem 18, data signals from the control unit 34 can be rapidly and accurately communicated to the surface. Examples of the torsional stress modulator 40 and the drill string control unit 34 are illustrated m Figs. 2 and 3, respectively, to which reference is now made.
  • the torsional stress modulator 40 m one embodiment is a hydraulically-actuated brake which includes a spiral
  • the stabilizer 40 is shown above the control unit 34, and is of conventional design, incorporating, for example, 18 hydraulically-activated pistons 54 located m spiral fins 55.
  • each spiral fin may carry six hydraulically-actuated piston buttons, each 1.75 inches m diameter.
  • a stabilizer with such a configuration is marketed as an adjustable stabilizer for drill stem stiffness control by Andergauge Drilling Systems.
  • the pistons when activated, engage the side wall of borehole 20 and serve to position the stabilizer body 50 with respect to the borehole.
  • an external hydraulic line 56 is connected to direct pressurized drilling fluid into the cylinders m which the pistons 54 are mounted.
  • the drilling fluid expands the pistons against the wall of the borenole 20, with the pistons being dimensioned to produce a significant drag on the borehole wall when they are activated.
  • the hydraulic line 56 By regulating the flow of drilling fluid m the hydraulic line 56, the pistons are expanded and contracted to cause the pistons to brake or release the drill stem and thus cause variable torsional stresses m the drill string. This braking action produces torsional waves in the drill stem 18 which can be detected at the surface detector 42. As illustrated m Fig.
  • the hydraulic line 56 is connected to an electronically controllable hydraulic valve 60 located m the drill string control unit 34 which is incorporated m a drill stem segment 62 connected below the modulator 40 but above the drill bit 32.
  • High pressure drilling fluid is supplied from the surface and flows downwardly through the drill stem core 64, flowing through both the drill string segment 52 illustrated m
  • a small portion of the high pressure drilling fluid is supplied from the core 64 through an inlet 66 and through the hydraulic valve 60 to the hydraulic line 56, with excess fluid being bled through outlet 68 to the exterior of the drill string segment 62 for return to the surface through the drill string annulus 70.
  • the hydraulic valve 60 is mounted m an MWD electronics cavity 72 within the segment 62. Also included m the cavity, m conventional manner, is a battery pack 74 connected to a sensor module 76 wnich may include accelerometers, magnetometers, and the like. The sensor module 76 is connected to a control electronics module 78 which produces output signals on line 80 for controlling the hydraulic valve 60.
  • the hydraulic control valve 60 is similar in design to tnose found m conventional MWD fluid pulse modulator systems which are used to generate fluid pressure pulses.
  • the hydraulic valve 60 is used to produce hydraulic fluid m line 56 under pressure to operate the pistons 54, as discussed above, to produce a torsional braking effect rather than to produce pressure pulses m the fluid flowing in core 64 or m the borehole 70.
  • the control electronics module 78 includes circuitry responsive to the sensors m module 76 to produce output data signals corresponding to acceleration values, magnetic field, gravity measurements, or any other desired parameter, the control electronics converting the detected parameters into data signals which are encoded and used to activate the hydraulic valve 60.
  • the opening and closing of valve 60 under the control of the data signals produces variations m the hydraulic pressure m line 56 to activate and deactivate the pistons m modulator 40 to thereby produce torsional stress modulation, or stress waves, m the drill string for detection at the surface.
  • the surface sensor 42 detects the stress waves and produces corresponding signals on line 44 wnicn are delivered to computer 36, where the data is utilized m conventional manner to obtain measurement of conditions m the borehole and to control the operation of the drill, among other things.
  • the control electronics module 78 is illustrated as controlling only the hydraulic valve
  • the signals may also be used to provide steering signals to the drill bit 32, and may be used for various other purposes as is known m the art.
  • the stress waves produced m the drill stem by modulator 40 are also measurable at the surface, but they are also measurable by the MWD sensors 76 to provide feedback signals to the control electronics 78.
  • These feedback signals enable the control electronics to regulate the hydraulic control valve 60 to adjust the amplitude of the stresses induced by the modulator 40.
  • the drill system MWD control unit 34 diagrammatically illustrated m Fig. 3 is of conventional design, and because it is adapted to rotary drilling systems t readily receives communication from the surface. Such communication may be provided by varying the drill stem rotary speed in a programmed manner, with the changes m RPM of the stem being detected by the accelerometers or magnetometers m the downhole sensors 76. The downhole sensors then produce control data signals for the control electronics 78 to enable the operator of the drill system at the surface to control the operation of the MWD control unit.
  • control unit is shown as being powered by a battery pack, the power for the control unit can be supplied by other conventional sources, such as by a fluid-driven turbine alternator m the drilling fluid flow stream, to be described.
  • the torsional stress modulator 40 described above and illustrated m Fig. 2 requires contact between the pistons 54 and the borehole wall to produce the required the stress waves.
  • an alternative form of the modulator is illustrated m Fig. 4 by an mertial modulator 90.
  • This modulator consists of a large annular mass 92 mounted for rotation about a drill stem segment 94.
  • the mass 92 is mounted on a set of bearings (not shown) to allow free rotation of the mass about the drill stem segment 94.
  • high pressure, high velocity drilling fluid flows through a central passageway 98 m the drill stem segment and, after flowing through and around the drill bit, flows upwardly around the drill stem m the annular space 70 m conventional manner.
  • the average motion of the mass 92 is governed by friction between it and the fluid 96 flowing upwardly m the borenole and by the proximity of the exterior surface of the mass to the borehole wall.
  • the mass 92 which may have a weight of about 1000 pounds, will tend to remain stationary as the drill stem is rotated so that modulation of the torsion m drill stem 18 can be accomplished by a brake mechanism, indicated at 100 m Fig. 4, operating between the mass 92 and the drill stem segment 94, as will be described below.
  • a preferred alternative to maintaining the mass 92 stationary by friction between it and the fluid within the borehole is illustrated m Fig. 4, wnerem the mass is driven to rotate at a speed faster than that of the drill stem by means of turbine blades 102 mounted on the interior surface of the rotating mass.
  • the drill stem segment 94 m this case will incorporate a diverter 104 m the path of the high-pressure, nigh velocity drilling fluid 96 flowing through passageway 98, this diverter serving to direct some or all of the downhole drilling fluid through the turbine blades 102.
  • a suitable brake assembly 100 is illustrated m cross- sectional view m Fig. 5, the assembly incorporating an hydraulically actuated brake band 110 secured at a first end 112 to the exterior of the drill stem 94, as by a suitable fastener 114.
  • the brake band extends around the circumference of the drill stem and is secured at its opposite end 116 to a piston 118 m a hydraulic cylinder 120.
  • the hydraulic cylinder is connected to tne hydraulic line 56, described above with respect to Fig. 3, which directs fluid into cylinder 120 through fluid inlet 122.
  • the introduction of fluid under pressure to cylinder 120 causes piston 118 to expand the brake band 110 against an interior surface 124 of the rotating mass 92.
  • the Drake band which may be a relatively thick elastic steel ring with an appropriate brake lining, when expanded brakes the rotating mass m accordance with the operation of the electronically controlled hydraulic valve 60 under the control of the electronic package 78.
  • Variation of the hydraulic pressure m line 56 causes the brake band to engage the rotating mass to induce corresponding torsional stress waves into the drill stem segment 94, which is rotating at a different speed than the mertial mass 92.
  • the brake assembly can produce relatively high frequency modulation on the drill stem using only simple and efficient hydraulics.
  • the drill stem itself need not be rotating for the system to function when the mass 92 is rotating.
  • the drill stem does not need to make contact with the wall of the borehole for the system to operate.
  • the drill head can be lifted off the bottom and the drill stem rotational drive turned off to permit transmission of data by torsional modulation m a virtually noise-free environment .
  • the torsional stress modulation waves generated by the modulators described above may be detected at the surface by the drill string detection unit 42.
  • Sucn a detection unit is illustrated m greater detail m Fig. 6 as including suitable strain gauge and accelerometer sensors 130 which are oriented on the drill stem 18 and balanced so as to measure torque.
  • Such sensors are of conventional design and produce output signals on line 132 which are delivered to a telemetry unit 134 which includes conventional strain gauge sensing electronics and, m a preferred form of the invention, a radio telemetry unit 136 for transmitting the measured stress changes to the computer 36 by way of radio receiver 138.
  • the accelerometer and the strain gauges have a large dynamic operating range so that small stress changes are readily measured.
  • noise signals produced by the drive motor 22 can be suppressed relative to those which are being propagated from the downhole modulators 40 or 90.
  • the sensitivity of measurement uphole will be limited by stresses induced by sources other than the downhole modulator.
  • the dominant sources of noise are the drill bit and the drill stem rotation drive.
  • Drill bit noise is usually relatively small, m most situations, but m those cases where it is not, data can be transmitted reliably by removing the weight from tne dr ⁇ _ bit by slightly lifting the drill string. Since the rotation drive motor 22 may operate at 1000 horsepower or more, the noise it induces may be important. However, the noise spectrum of the drilling motor can be measured and an optimum frequency channel selected for the transmission of data-carrying torsional stress waves .
  • FIG. 7 An alternative form of the surface detection unit 42 is illustrated m Fig. 7, wherein the detection unit utilizes an induction coil sensor 130 located on the motor control output line 30 which carries the drive current for drive motor 22.
  • the induction coil 130 is sensitive to changes m the current supplied to the drive motor. Torsional stresses induced downhole m the drill stem 18 vary the load on the drive motor 22 at the surface, causing the drive current to vary as the motor attempts to maintain a constant rotational speed. Such current variations correspond to the modulation of the drill stem, and accordingly the output of the sensor coil on line 132 corresponds to the data input.
  • This output is supplied to computer 36 for use m providing information to the system operator and for utilizing the transmitted data for controlling the operation of the system, as previously discussed.
  • Fig. 3 illustrates a solution to this problem, while at the same time providing an improved mechanism for reliably detecting control and data signals transmitted from the surface by modulation of the rotational speed of the drill stem, wherein, an electrical alternator 140 is provided at a downhole location.
  • This alternator is responsive to the rotation of the drill stem to produce an alternating current electrical output for providing power to the downhole control unit. Furthermore, the frequency of the AC output depends on the rate of rotation of the alternator, so changes m the rotational speed of the drill stem produce modulations m the alternator output frequency. Such modulations can be detected and then demodulated to reproduce the transmitted data that has been encoded m variations m drill stem rotation.
  • the alternator 140 includes a stator 142 incorporating a plurality of permanent magnets 143 supported on a collar 144 wnich is expandable against the inner wall of the borehole 20 by a plurality of bowed springs 145. These springs hold the collar stationary with respect to the rotating drill stem 18.
  • a rotor 146 includes conventional motor windings 147 wound on laminations 148 which produce an alternating current output on line 149. This AC output is connected to a rectifier 150, and the direct current output of the rectifier is applied by way of line 157 to the drill string control unit electronics module 78.
  • the DC current on line 150 acts as a power supply for the electronics module 78, replacing the battery pack 74 utilized m previously- described embodiments.
  • the AC output from the windings 142 is also supplied by way of line 149 directly to a frequency detector m the electronics module 78 by way of line 152.
  • the frequency of the alternator output is dependent upon the rate of rotation of the drill stem 18, as noted above, and the speed of rotation of the drill stem is controllable by the motor control 28 at the surface.
  • Control instructions and data provided at the surface by computer 36 are encodes, and the encoded signals regulate the speed of rotation of motor 22 by way of the motor control 28.
  • the resulting changes m rotation of the drill stem 18 produce corresponding cnanges m the frequency of the output signal on line 149 which is supplied to the electronics package 78 where the frequency modulation is decoded to reproduce the control instructions and data from the surface.
  • FIG. 8 and 9 An alternative embodiment to the rotational or torsional stress embodiments described above is illustrated m Figs. 8 and 9, to which reference is now made.
  • axial displacement modulation of the drill stem is utilized m place of rotational stress modulation through a controllable lift mechanism which moves the drill stem longitudinally m selected increments.
  • the embodiment of Figs. 8 and 9 includes a derrick 12 mounted on a platform 14 at the surface 16 of the earth, with the drill stem 18 being supported m a borehole 20 and driven by a top drive motor 22.
  • the motor 22 is secured m the der ⁇ c by a conventional pulley and cable arrangement 24 for raising and lowering the drill string, with the motor 22 being operated under the control of computer 36 by way of motor control circuit 28.
  • Fig. 8 incorporates a lift control mechanism 170 which is operated under the control of computer 36 by way of line 72 for raising or lowering the drill string 18 m increments of, for example, 3 feet, so that the drill stem can be moved the length of a conventional 30-foot long drill string segment m ten steps.
  • Data to be transmitted downhole is supplied to the computer 36, which provides corresponding modulation signals on line 172 to cause the drill stem to move upwardly or downwardly m one or more steps to encode the data m axial steps of the drill stem.
  • the drill stem is constructed of steel or other materials which are essentially inelastic in the axial direction, the vertical step motion of the support mechanism 170 and of the drill string at the surface is accurately and reliably transferred to corresponding steps at the drill string control unit 180, where the vertical motion is sensed and demodulated.
  • a suitable sensor for the axial position modulation of the drill stem 18 is illustrated in Fig. 9, wherein the control unit includes a Z-axis accelerometer 182 which produces an output on line 184 corresponding to the measured axial acceleration of the drill stem.
  • the output on line 184 is supplied through an integrator circuit 186 which produces output signals on line 188 for the controller module 190, which may be a computer.
  • the control unit may include additional sensors 192, the outputs of which are supplied through decoder 194 to the control module 190, for detecting other parameters such as drill string rotation, drilling fluid flow and the like. This information may be used to control the starting or stopping of the controller 190 or for other purposes, as is known m the art.
  • the axial position modulation solves the problem of inaccuracies that can occur m rotational modulation since in the latter case the stem can twist and thus provide inaccurate rotational data at the bottom of the drill string.
  • Axial stress waves can also be used to transmit data uphole through the provision of a downhole spring-loaded impact mechanism, somewhat analogous to the " ars", or shock tools, presently used for loosening stuck drill pipes.
  • a powerful spring is set m the downhole assembly by applying the weight of the drill stem to the bit. The bit is then lifted slightly off the bottom to initiate a timing sequence in the downhole modulator control circuit. After a time interval which varies m accordance with the encoded data to be transmitted, the spring is released by a hydraulic cylinder. This sequence is repeated to encode and transmit uphole data words of aroitrary length.
  • the release of the spring causes the drill stem to be impacted by an mertial weight associated with the spring device, and the resulting axial stress waves are detected uphole, using strain gauges and accelerometers m the detection unit 42.
  • the control circuit times the spring release after the drill stem is raised, and the time delay encodes the data to be transmitted m the resulting modulations of the axial stress m the drill stem. Since the timing of the impact after the drill spring is lifted can be done very precisely, data is transmitted accurately.
  • the transducer may consist of a modified joint between two adjacent segments of the drill stem 18, illustrated m Fig. 10 as a splmed, telescoping joint 260 between upper and lower drill stem segments 262 and 264.
  • the splmed joint includes a plurality of longitudinal, spaced grooves 266 on the interior surface of the upper segment 262 which receive corresponding spaced, elongated splines 268 formed on the exterior surface of lower segment 264.
  • the splines 268 slidably engage the grooves 266 to allow the drill segment 264 to move axially with respect to the drill segment 262 while preventing rotational motion therebetween. In this way, the drill stem can extend and contract at the transducer 40 while transmitting rotational motion from segment 262 to segment 264.
  • the upper and lower drill stem segments 262 and 264 are joined longitudinally by a piston and cylinder assembly 270 wnich includes a piston 272 movable within a cylinder 274.
  • the cylinder 274 is formed by a housing
  • the housing is generally cylindrical and surrounding the lower end of the drill stem segment.
  • the housing includes upper and lower radially-extending walls 277 and 277' which cooperate with the wall of the drill stem segment 262 to form the annular cylinder 274.
  • the piston 272 is also annular and is slidably mounted m the cylinder 274 to divide it into an upper chamber 278 and a lower chamber 280, the piston being sealed to the cylinder wall by O-ring 282 and to the surface of the drill stem segment 262 by O-ring 284.
  • Piston 272 is connected to, or formed as part of, the lower drill stem segment 264, and thus is secured to segment 264 by a connecting arm 286 m the form of a cylinder 286 and radial wall 288.
  • the annular piston 272 s positioned within housing 276 with the connecting cylinder 286 extending through the bottom wall 277' of that housing to connect the segment 264 to upper segment 262.
  • a pair of O-rings 290 and 292 are fixed m the lower wall 277' of housing 276 and engage the inner and outer surfaces of connecting cylinder 286 to provide a seal between the cavity 280 and the exterior of housing 276.
  • the upper and lower portions 278 and 280 of cylinder 274 are filled with nydraulic fluid and the two sections are interconnected through suitable valves to enable the piston 272 to move upwardly or downwardly with the cylinder.
  • the upper section 278 is connected by way of hydraulic line 300 through a one-way check valve 302 and througn hydraulic line 304 to the lower chamoer 280 of the cylinder.
  • the check valve 302 allows hydraulic fluid to flow freely from upper chamber 278 to lower chamber 280 so that when there is a compressive force on the drill string; that is, when drill string segment 262 is pressed downwardly onto drill string segment 264 to compress the transducer joint 260, hydraulic fluid will flow from chamber 278 through check valve 302 to chamber
  • Such a compressive force would be applied to the joint 260 when the drill string is used in its normal drilling operation, for during this time, the lift mechanism 24 on the derrick 12 lowers the drill string as it is being rotated by drive motor 22.
  • the weight of the drill string applies a compressive force on joint 260 and the piston 272 moves upwardly m cylinder 274.
  • the splmed connection between segments 262 and 264 transmits the rotation of the drill stem 18 to the drill head 32.
  • sensors 310 m the MWD control unit 34 produce output signals corresponding to various measured parameters, and these signals are supplied to a microprocessor 312 m the control unit.
  • the sensors may include fluxgate magnetometers, inclinometers, gravity detectors, or like devices for measuring parameters of interest, and the sensor output signals are converted by the microprocessor to data signals wnicn are to be transmitted to the surface.
  • the sensors 310 and the microprocessor (or computer) 312 are conventional and, m accordance with one embodiment of the present invention, supply output signals by way of line 314 to the drill stem 18, which is of an electrically conductive material such as steel.
  • the signals produce a corresponding electrical current m the drill stem which may be sensed at the transducer 40 by a torroidal coil 316 surrounding the drill stem segment 264.
  • These encoded signals are supplied by coil 316 through line 318 to activate the solenoid valve 306 to open and close this valve m accordance with the encoded signals.
  • the drill string 18 When data is to be transmitted uphole, the drill string 18 is lifted by the hydraulic lifters 24 at the surface so that the drill bit 32 is moved away from the bottom of the borehole.
  • the transducer 40 is spaced about 100 meters above the drill head and its associated MWD control unit 34. This causes the weight of the lower end of the drill stem below the modulator, which may be 5000 lbs., or more, to tend to extend the joint 260 and thus tend to pull the piston 272 downwardly, applying a high pressure to the hydraulic fluid m chamber 280. As long as valve 306 remains closed, the hydraulic fluid will be retained m chamber 280 and the joint will be neld m its collapsed or upward position, with the piston 272 at the top of cylinder 274.
  • the control signals from microprocessor 312 may then be used to activate and deactivate the solenoid valve m short, timed bursts, allowing pressurized hydraulic fluid to flow out of chamber 280, through valve 306 and line 308 to upper chamber 278. This releases segment 264 m incremental steps, and the portion of tne drill string 18 below the modulator drops freely until the valve is closed. Each burst of released fluid thus momentarily releases the tension or axial stress applied to the upper part 262 of the drill string 18 by the weight of the drill stem below the transducer, and thus reduces the apparent drill string weight that is detected by sensors 42 at the surface.
  • the change m axial stress caused by opening of valve 306 is transmitted along the length of the drill string above the transducer for detection at the surface, and such a release is referred to herein as an axial stress wave or a shock wave.
  • Repeated openings and closings of the valve 306 m accordance with encoded signals produced by microprocessor 312 produce corresponding stress pulses, or shock waves, which propagate along the length of the drill stem to the surface for detection at sensor 42 and for decoding m computer 36.
  • the drill string can be rotated during the transmission of shock waves uphole, so that the rotation eliminates the effects of stick slip friction between the upper part of the drill string and the oorehole wall, thereby increasing the efficiency of the modulated axial stress transmission.
  • the hydraulic cylinder 274 may be connected to an accumulator 330 which may be connected to the upper chamber 278 by way of a small passageway 332.
  • the accumulator 330 preferably is an elastomer that allows expansion to accommodate small ambient pressure changes.
  • the spline section cf tne drill stem snould be a significant distance above the drill bit so that a large drill string weight will be carried by the hydraulic cylinder fluid.
  • the control unit 34 can be connected to solenoid valve 306 by a direct wire, if desired.
  • Power for the control unit can be by way of a battery source, or can be supplied by an alternator m the manner described above.
  • a modified form of the downhole transducer is illustrated m Fig. 11 at 40'.
  • the piston and cylinder arrangement of the embodiment of Fig.10 is reversed so that hydraulic fluid is transferred between upper and lower chambers of the cylinder to charge the transducer by lifting the drill string.
  • the weight of the string applies high pressure to the fluid in the lower chamber of the cylinder so that release of that high pressure fluid by a solenoid-controlled valve produces short bursts of reduced pressure to lower the portion of the drill string incrementally and to generate axial stress waves which can be detected at the surface.
  • a solenoid-controlled valve produces short bursts of reduced pressure to lower the portion of the drill string incrementally and to generate axial stress waves which can be detected at the surface.
  • the modified transducer 40' incorporates a splmed joint 130 between an upper drill stem segment 332 and a lower segment 334.
  • the upper segment 332 is connected as a part of the drill stem 18 and leads to the surface, while segment 334 s connected through the control unit 34 (Fig.l) to the drill head 32.
  • the transducer 40 is separated from control unit 34 and drill head 32 by a distance of about 100 meters m order to provide sufficient weight to produce axial stress waves upon operation of the solenoid valve.
  • the transducer 40' can be close to the control unit 34 and drill head 32, since it is the weight of the drill string above the transducer that produces the desired stress signals upon the release of pressurized fluid by the solenoid valve.
  • segment 332 carries on its interior surface 336 a plurality of longitudinally extending grooves 338. These grooves receive corresponding splines 340 carried on the exterior surface of lower drill stem segment 334, thereby forming the splmed joint 330.
  • This joint permits relative longitudinal movement between the lower drill stem segment 334 the upper segment 332.
  • a cylindrical housing 342 Surrounding the spline joint 330 is a cylindrical housing 342 which is mounted on, or is integral with, the stem segment 334 at a lower wall portion 344 and extends upwardly to a top wall portion 346 which engages the outer surface of stem portion 332.
  • the wall 346 carries a suitable seal 348 such as an O-ring to provide a fluid tight transducer cylinder 350, defined by cylindrical housing 342.
  • annular piston 356 Located within cylinder 350 and dividing the cylinder into ⁇ pper and lower chambers 352 and 354 is an annular piston 356 which is secured to or is integral with the bottom end of the drill stem segment 332. As illustrated, the piston 356 incorporates an O-ring 358 which seals it against the wall of cylinder 350 to maintain a fluid-tight seal between chambers 352 and 354.
  • the two chambers are filled with hydraulic fluid such as oil, with the upper chamber being connected to the lower chamber by way of hydraulic lines 360 and 362, check valve 364, and hydraulic lines 366, 368 and 370.
  • the check valve 364 permits the fluid from chamber 352 to flow downwardly into chamber 354, the direction of arrow 372, so that when the drill stem 18 is lifted by the lift equipment 24 (Fig. 1) the piston 356 will tend to move upwardly cylinder 350 and force hydraulic fluid from chamber 352 down through checK valve 364 into chamber 354. This charges the transducer to make it ready for the transmission of data signals to the surface.
  • a solenoid-operated control valve 374 which is connected between hydraulic lines 360 and 368 by way of hydraulic lines 376 and 378.
  • the valve 374 is normally closed to prevent the flow of fluid between lines 376 and 378, but upon energization of the solenoid, the valve shifts into an open position to allow fluid flow.
  • the stem is lowered oy lift equipment 24 and, if desired, can be driven oy motor 22 (Fig.l) for continued drilling of the borehole.
  • the weight of the drill stem which is applied to the drill head 32 is applied through the hydraulic fluid chamber 354 by way cf piston 356, generating as much as 20,000 lbs./sq.m. of fluid pressure cnamber 354, which then serves as a pressure chamber.
  • the splmed joint 330 transmits the rotation of drill stem 18 through the transducer and to the drill head 32.
  • Downhole sensors 310 m the control unit 34 (Fig. 10) produce output signals corresponding to sensed parameters, and these signals are directed to a microprocessor or other suitable computer 312, as described above, which produces encoded data signals on line 314.
  • line 314 is shown as being directly connected to solenoid valve 374 so that the output signals from computer 312 control the operation of the valve.
  • the valve is energized by data signals to shift to an open position for a short period of time and then to shift back to the closed position, thereby releasing fluid under pressure from pressure chamber 354 and allowing it to flow through lines 370, 368, 378, 376, and 360 into the upper chamber 352, which serves as a release chamber.
  • the hydraulic system of Fig.11 may incorporate an accumulator 380 connected to hydraulic line 360 to accommodate variations in the temperature of the fluid, for example, and may include a pressure sensor 382 connected to hydraulic line 368 for measuring the pressure m chamber 354.
  • the electrical output from sensor 382 may be connected by way of line 384 to computer 312, so that the pressure chamber 354 may be one of the parameters included with tne data signals on line
  • the preferred method for charging the pressurized chamber 354 is by lifting the drill stem 18, charging of the chamber can also be accomplished by supplying hydraulic fluid under pressure to line 370, as from an hydraulic pump located downhole.
  • a suitable pump for this purpose is illustrated at 400 in Fig. 12, the pump including an hydraulic cylinder 402 mounted on and surrounding a section of drill pipe such as the drill stem segment 334.
  • the cylinder 402 receives a free piston 404 which is annular m shape, which surrounds the drill stem segment 334, and which is moved along the length of cylinder 402 by varying the fluid pressure m the cylinder.
  • the piston includes an inner annular surface 405 carrying an O-rmg 406 for sealing against the exterior of drill stem segment 334.
  • the piston also has an outer annular surface 407 incorporating an O-rmg 408 for sealing the piston against the wall of cylinder 402 so the piston divides the cylinder into an upper recharging chamber 410 and a lower pumping chamber 412.
  • the upper chamber contains hydraulic fluid to be supplied through outlet line 414, and through a check valve 416 to a gear-type pressure multiplier which provides a pressure increase in the hydraulic fluid.
  • This increased pressure fluid is supplied from the pressure multiplier through line 370 to the lower pressure chamber 354 m transducer 40' to recharge it. Pressurized fluid supplied from pump 400 thus may be used to charge chamber 354 to a desired pressure level.
  • the multiplier 418 is connected by way of a second outlet line 423 and a second check valve 424 to return excess fluid to chamber 410.
  • Pressure is generated recharging chamber 410 by means of the conventional drilling fluid, or drilling mud, used rotating drilling systems.
  • drilling fluid flows downwardly into the bottom of the borehole through the center of the drill stem 18 and is under about 500 psi at the bottom of the borehole.
  • drilling fluid is supplied from the interior of drill stem segment 334 through a feed line 430, through a solenoid valve 432, and through a supply line 434 to the pumping chamber 412 of cylinder 402.
  • solenoid 432 When the solenoid 432 is open, as illustrated, drilling fluid is supplied to chamber 412 to press piston 404 upwardly to thereby pressurize the hydraulic fluid m chamber 410. This causes hydraulic fluid to flow to pressure chamber 354 the transducer of Fig. 11 to charge the transducer .
  • the sensor unit 310 may incorporate a sensor for detecting the location of piston 404 m cylinder 402 to enable the computer 312 to regulate the operation of solenoid control valve 432. If the piston 404 shifts upwardly too far, valve 432 may be shifted to the left (as viewed m Fig. 12) to connect the fluid line 434 through the solenoid valve to an outlet line 436. This allows the drilling fluid m chamber 412 to bleed out of the system and to return to the borenole annulus surrounding drill stem 18. The piston 404 then falls to expand chamber 410, with fluid from accumulator 422 filling the chamber.
  • valve 432 When sufficient hydraulic fluid has been supplied to chamber 410, valve 432 is shifted to the right to open line 434 to inlet line 430 to thereby allow the drilling fluid to pressurize chamber 412.
  • the pump 400 thus is operated by means of the drilling fluid circulating into the borenole through the drill stem to keep the axial stress transducer 40' charged and activated.
  • Axial pressure waves generated Dy released pressure downhole transducers 40 or 40' may be detected at the surface by sensor 42, which may incorporate suitable strain gauges, as described above. However, axial stresses generated downhole can also be measured at the surface as pressure variations m a hydraulic transducer such as that illustrated at 42' m Fig. 13.
  • This transducer is similar to that describee above with respect to Fig.11, but utilizes a pressure sensor coupled to the upper chamber for detecting changes m hydraulic pressure due to axial stress waves received along drill string 18. The output of the pressure sensor may then be transmitted to the uphole computer 36 by way of line 44 or by any other conventional communications link.
  • the uphole transducer 42' includes a cylinder 440 surrounding a telescoping splmed joint 442 formed between adjacent upper and lower drill stem segments 444 and 446.
  • Segment 444 includes a plurality of longitudinal, spaced grooves 448 located at the lower end of its inner surface, while the upper end of segment 446 includes a corresponding plurality of longitudinal splines 450.
  • the splmed joint allows relative longitudinal motion between segments 444 and 446, while transmitting rotary motion from one to the other.
  • Cylinder 440 receives an annular piston 452 which may be integral with the bottom of drill stem segment 444 and which divides the cylinder 440 into an upper pressure chamber 454 and a lower chamber release chamber 456.
  • Suitable O-rmgs 457 and 458 seal the piston against the wall of cylinder 440 and seal the cylinder
  • the transducer 42' can also be used to transmit data downhole by generating axial stress waves.
  • the hydraulic fluid pressure m cylinder 440 is released m short, timed bursts under the control of a solenoid valve, operated by encoded signals from computer 36 generally in the manner described here above with respect to Figs. 2 and 3.
  • the resulting stress signals, or shock waves, are transmitted through the drill stem 18 to the downhole transducer 40 or 40'.
  • These stress signals produce pressure changes m the hydraulic fluid in the downhole transducer, such as the transducer 40' discussed with respect to Fig. 11, and such pressure changes are detectable by the pressure sensor 382 (Fig.11).
  • the resulting output signals from sensor 382 are supplied to computer 312 at the downhole location for demodulation to allow the computer to exercise control over the downhole operations.
  • Stress signals are generated m the drill string at the uphole transducer 41' by releasing the pressure chamber 454 by way of hydraulic lines 462 and 466, a solenoid-controlled spool valve 468, and hydraulic lines 470 and 464.
  • Encoded data or control signals to be transmitted downhole are provided by computer 36 on line 472, and these signals operate solenoid valve
  • the normally closed valve is activated by the encoded signals to allow fluid to flow from upper chamber 454 to lower cnamber 456 m timed bursts to produce incremental motion or variations m longitudinal tension or compression m drill stem segment 446 to produce axial stress signals.
  • Chamber 454 can be charged with hydraulic fluid and the location of piston 452 the cylinder 440 can be adjusted by lowering the drill stem 18 to the bottom of the borehole and then further lowering the upper drill segment 444 while opening solenoid valve 468, thereby allowing a reverse flow of fluid from chamber 456 to chamber 454. Fluid may also be transferred to chamber 454 from an accumulator 474 connected to line 470.
  • the upper chamber can be charged by means of an hydraulic pump 476 connected to the lower chamber 456 through accumulator 474 and hydraulic line 464, the pump delivering pressurized fluid through line 478 and a second solenoid- controlled spool valve 480, the output of which is connected by way of lines 482 and 462 to the upper chamber 454.
  • hydraulic fluid under pressure may be supplied to the upper chamber to raise the drill segment 446 with respect to drill segment 444 and to thereby charge the upper chamber 454. Sufficient power to operate such a pump s normally available at the surface.
  • the rapid communication between the surface and the drill controls at the bottom of the borehole provided by the present invention also permits conservation of the energy required for such communication, for if strong signals are received at the surface, computer 36 can transmit instructions to the downhole computer to change the frequency and strength of the pulses to reduce the energy required.
  • the downhole solenoid valves for controlling the above- described hydraulic systems are battery-operated, m the preferred form of the invention.
  • the downhole axial hydraulic units send data by releasing small volumes of hydraulic fluid timed increments using these solenoid-operated valves to impulsively lower the drill string and generate axial stress waves which propagate to the surface.
  • the stress waves are demodulated Dy strain gauges or by an axial stress transducer located at the top of the drill string.
  • the upper transducer is cf heavier construction than the downhole units because of the large weights which it must handle.
  • Incoming axial stress wave pulses to the uphole hydraulic transducer are sensed by pressure changes, with the pressure sensor sending corresponding signals to the computer for demodulation.
  • the hydraulic energy for the downhole transducer is provided by the downward pressure of the drill string or, m the alternative, by a secondary source of pressurized hydraulic fluid such as a pump driven by the drilling fluid which flows to the drill bit through the center of the drill string. This allows the downhole axial stress transducer to continually send data pulses to the surface while the drill is operating, without the need to re-energize the unit by lifting the drill string at the surface.
  • An important feature of the invention is that the intrinsic fast response and huge power gam which can be built into electrically-controlled hydraulic valves, coupled with the intrinsic high frequency wave propagation characteristics of the drill stem, enables drilling parameters to be controlled by a fast acting communication system.
  • This parameter can be transmitted uphole to the surface transducer, where it is received within a second, and can be used to change immediately the weight on the bit by activating the solenoid- controlled spool valve 480 which controls the position of the piston 452 m the uphole axial stress transducer 42' from which the drill stem hangs.
  • the velocity of propagation of compressive waves m steel is about 500 m./sec
  • the acoustic impedance of steel (density x velocity of propagation) is 4 x 10 7
  • the cross sectional area of a drill string is about 0.006 m- .
  • the wave power associated with 1000 lbs./ - (7xlO B newtons/m 2 ) stress waves on such a drill string is approximately 10,000 watts; that is, 13 horsepower.
  • 20,000 lbs. of force (which is a characteristic weight on a drilling bit) is 88,000 joules.
  • Measurement of drill bit vibrations at the earth' s surface show that compressional waves with frequencies as high as 100 Hz are readily transmitted on the drill stem.
  • the simplest hydraulic spool valve energized by 20 watts of electric power can control a flow of 30 gallons per minute at 3000 psi; that is, 44,000 watts of hydraulic power.
  • the response time of such valves is 0.003 seconds, so that 10 Hz waves are readily generated.
  • the peak drill string movement associated with a 10 Hz, 1000 psi wave is about 3 mm, thus indicating the practicality of the present communication system.
  • torsional stress waves are generated by hydraulically, electrically or magnetically controlling the relative rotation of the drill stem 18 with respect to the drill bit 32 as illustrated Figs. 14 through 17.
  • the drill stem 18 extends below the downhole control unit 34 where it is connected to a drill head 500 which supports drill bit 32.
  • the drill bit is mounted to rotate with respect to the drill head 500, with a brake or clutch mechanism (to be described) being energizable to connect the bit to the stem for rotation therewith.
  • the bit When the drill stem is rotated to drive the drill bit, the bit engages the earth and resists the rotation of the drill stem, creating a torsional force on the drill stem.
  • the torsional force on the drill stem can be modulated. This causes torsional drill bit stress waves to propagate along the length of the drill stem, and these can be detected uphole and demodulated as described above to thereby transmit data from the control unit to an uphole receiver .
  • the drill bit stress waves may be produced hydraulically by a clutch mechanism the manner illustrated Figs. 14 and 15, to which reference is now made.
  • the drill head 500 is secured to the lower end 502 of drill stem 18, as by a threaded connection 504.
  • the drill head forms an enlarged inner chamber 506 connected to the inner m which the drill bit 32 is mounted for relative rotation.
  • the drill bit includes an upper mounting shoulder 508 which engages a corresponding annular groove 510 formed the interior surface of chamber 506.
  • a ring 512 is secured to the interior of drill head 500 to hold the drill bit place while permitting relative rotation.
  • Spaced below the mounting shoulder 508 and the ring 512 is a hydraulic clutch assembly generally illustrated at 514 m Fig. 14 and shown in cross-section in Fig. 15.
  • the drill bit 32 includes a central passageway 516 for directing drilling fluid from drill stem 18 and drill head 500 through the lower end of the drill, near the teeth 518 of drill bit 32.
  • a clutch surface 520 Secured to or integral with, and forming a part of the outer surface of, drill bit 32 is a clutch surface 520 which is engageable Dy a clutch band 522.
  • the clutch band is anchored to the drill head 500 and thus to the rotary drill stem 18 and rotates with the drill stem. When act ⁇ vate4d, the clutch band
  • Fig. 15 illustrates m diagrammatic form a hydraulic actuator 530 for the clutch assembly 514.
  • the actuator includes an hydraulic cylinder 532 secured to the inner wall 534 of drill head 500.
  • a piston 536 is located the cylinder 532 and is secured by way of rod 538 to a first, free end 540 of clutch band 522.
  • the band is elongated and exten ⁇ s most of the way around the clutch surface 520, with a second, fixed end 542 of the band being secured to the drill head 500, as by bolting or welding end 542 to a shoulder 544 secured to or integral with the drill head.
  • a source of hydraulic fluid under pressure is connectable to an inlet 546 in the cylinder 530, as by way of hydraulic line 56 (see Fig.
  • the clutch band can alternatively be operated electrically, as by a solenoid 550 connected to the free end 540 of the clutch band.
  • the solenoid includes a coil 552 secured to the inner surface 534 of the drill nead 500 and a moveable, elongated core 554 secured to the free end of the clutch band and movable into and out of the core 552.
  • the core 554 is drawn into the coil 552 to draw the band 522 into engagement with surface 520 to ocuple the drill bit to the rotary drill stem.
  • a clutch assembly 560 may be in the form of multiple rotary plates 562,
  • the drill bit is rotatable with respect tot he drill head 500, and is secured m the inner cavity
  • annular shoulders 564, 564a and 564b which extend inwardly below corresponding rotary plates 562, 562a and 562b, respectively.
  • a corresponding hydraulic chamber illustrated at 566, 566a and 566b, carrying a corresponding clutch piston 568, 568a and 568b.
  • the pistons are movable to engage the tops of their adjacent plates 562, 562a and
  • Various other controllably releasaole clutch arrangements can be used to connect the drill bit 32 to the rotating drill head to modulate the torsional stress m the drill stem and to propagate signals representing downhole data to receivers at the surface. It will be understood that a similar clutch assembly can be provided at the surface; for example between the drive motor 22 and the drill stem 18, to intermittently release the torsional drilling stress m the drill stem to propagate torsional stress waves to a downnole receiver or sensor.
  • the sensor mechanism also serves as a power source for supplying operating power to downhole equipment, thus avoiding the need for batteries and extending the life of the equipment.

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Abstract

L'invention concerne un système de communication dans un train de tiges, ainsi qu'un procédé et un appareil servant à transmettre des données entre des emplacements placés le long d'un train de tige (18). Les données peuvent être transmises soit en fond de puits, soit en tête de puits, soit les deux, en modulant le mouvement et/ou la contrainte exercée. En outre, l'invention concerne un procédé et un appareil pour générer de l'électricité (140) pour les équipements électroniques de fonds de puits en réponse au mouvement rotatif du train de tiges (18). Dans un mode de réalisation préféré, toutes les caractéristiques sont incorporées dans le système de commande de forage.
PCT/US2000/016293 1999-08-05 2000-06-26 Procede et dispositif de transmission de donnees dans un train de tiges WO2001011191A1 (fr)

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CN111577260A (zh) * 2020-04-27 2020-08-25 湖南创远高新机械有限责任公司 天井钻机通信系统及其控制方法
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EP2318643A1 (fr) * 2008-07-09 2011-05-11 Weatherford/Lamb Inc. Appareil et procédé pour une transmission de données à partir d'un dispositif de commande de rotation
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US9726011B2 (en) 2010-05-24 2017-08-08 Schlumberger Technology Corporation Downlinking communication system and method
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