DE2743871A1 - METHOD AND EQUIPMENT FOR MEASURING A DRILLING HOLE DURING DRILLING - Google Patents

Description

Description of the patent application

from Schlumberger Technology Corporation, 5000 Gulf Freeway,

Houston ^ Texas ^^ OOI / ySA

concerning

"Method and device for measuring in a borehole during

of drilling

The invention relates to a method and a device for measuring in a borehole while drilling and in particular relates to a method and a device for transmitting telemetry data in such operations using an acoustic signal that is transmitted via the drilling fluid during drilling.

Various methods have been proposed for logging in boreholes while drilling in order to transmit remote logging data indicative of conditions below the borehole. In one method, a method is used in which an acoustic signal, which is modulated according to the sensed conditions, is given to the drilling fluid, e.g. the drilling mud, for transmission at the entrance of the borehole, where it is received and by electronic means provided outside the borehole Circuit arrangements is decoded. This basic process is described in detail in U.S. Patent No. 3,309,656. In this system, the modulated signal is applied to the drilling fluid using an acoustic signal generator which has a movable member to selectively interrupt the drilling fluid. To-

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at least part of the flow of drilling fluid passes through the acoustic Generator through, and by the movable part this flow is stopped selectively, with a continuous one acoustic wave is transmitted to the drilling fluid outside the borehole.

The acoustic signal is preferably phase-shifted (PSK) modulated as described in US Pat. No. 3,789,355. Corresponding of this PSK modulation, the data corresponding to the | felt condition down in the borehole, initially coded in binary form, and the acoustic signal generator is operated at appropriate speeds, see above that the phase of a constant frequency carrier wave generated in the drilling fluid indicates the data. In particular a PSK operation without a return to zero is used, with the phase of the carrier signal only on each reception is changed by data of a predetermined value. For example For binary-coded data, the phase of the carrier wave can be changed each time a data bit with a logical 1 occurs will.

Ideally, the phase change of the carrier signal should be instantaneous changed when the data with the special value occurs. That means that the facility is used to transmit from remote measurement data downhole continuously to the receiving devices located outside the borehole transmits, where the data is again continuously decoded. Delays in the implementation of the A phase change or when the acoustic signal is returned to its carrier frequency becomes errors and / or uselessnesses introduced into the system.

In practice, however, the phase of the acoustic signal according to the data of the predetermined value may not be instantaneous be changed. Simply by building the system

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Delays are introduced - The motor control circuit, which operates the motor-driven acoustic generator, is adjusted accordingly in order to bring about an optimal response of the generator. In previous proposals, such as in U.S. Patents 3,309,656, 3,789,355 and 3,820,063 various circuits to create the motor control circuit have been proposed. In the aforementioned documents, the speed of the motor had to be changed temporarily in such a way that when the motor speed was returned to the speed that created the carrier frequency, the required phase change was added. In U.S. Patent 3,820,063 this was accomplished by changing the speed of the motor in a first direction until a predetermined phase shift has been summed. The motor speed was then brought back to the carrier frequency generating speed for a predetermined period of time in the other direction, thereby attempting to sum the remainder of the required phase shift.

However, the above proposals have not been sufficient to overcome the difficulties encountered with changes in the environmental conditions of the system for measuring in boreholes while drilling. These changing conditions can adversely affect the accuracy with which the speed of the drive motor of the acoustic generator increases the speed which creates a constant carrier frequency (the carrier speed) is fed back during the phase change (during a modulation) . It has been proposed to coordinate the corresponding systems so that the return of the summation of the required change value was approximated and the return was almost ended when the speed of the motor has reached the carrier speed. The suggestions were also insufficient to feel the actual speed of the motor, since the feedback should be ended exactly when the carrier speed is reached. Since the suggestions weren't enough to feel the actual speed, they weren't enough to get a

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To create a system that would allow return in the shortest possible time; that is, they failed to create a system that would allow the drive motor to be controlled even at maximum excitation, which would prevent the carrier speed from overshooting in a positive or negative direction. The proposals relied on circuitry to separately adjust and hold the phase and frequency in order to adjust the phase and frequency to the correct values after an approximate return to the carrier speed. However, such a setting and holding circuit takes a relatively long time to change the engine speed significantly, and therefore is insufficient to minimize the duration of the feedback . Since it is not enough to reduce the time of returning to a minimum, leaving the proposals either that inaccuracies were introduced into the system or an unnecessarily slow encoding / data transmission system has been created.

Besides the above-mentioned difficulties in adjusting the engine speed and the quality of modulation suffers. For example, changes in the load on the drive motor of the acoustic generator, which are caused by changes in the pressure, the flow rate, the viscosity or the density of the drilling fluid, change the time required to reduce the motor speed to the speed that creates the carrier frequency . This change over time changes the phase value which has been summed during the feedback to the speed creating the carrier frequency, which in turn results in a longer period of time which is required to generate the correct phase change value at the carrier frequency. Due to this longer period of time, inaccuracies are again introduced into the system and / or the speed of the data transmission decreases, which would otherwise be obtainable.

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The approaches described in the aforementioned patents require an analog design of the motor control circuit. Since the motor control circuit operates at a relatively low frequency, the analog solution has resulted in a system that with a lower than the optimal data encoding / decoding speed is working. Furthermore, such an analog circuit has disadvantages in terms of instability over a large period Temperature ranges, which in turn results in a less than optimally reliable system. In particular, change the normal temperatures in a borehole during drilling from 25 ° C to more than 175 ° C, which in turn changes in the System characteristics of the analog circuit. Consequently the analogous solution fails due to the rough ambient conditions during drilling. The very strong vibrations and shocks absorbed by the analog circuit not only shorten its service life, but also tend to that the circuit is adjusted. In addition, analog circuits are relatively expensive to manufacture and test.

The invention is intended to overcome the disadvantages listed above and other disadvantages.

According to the invention, therefore, there is provided a method of measuring in a borehole while drilling, in which the speed of a motorized acoustic signal generator is instantaneously changed from its normally constant speed to effect a corresponding phase change in the acoustic signal , the speed the generator of the normal rotational speed of is changed, in which then a pair of digital signals corresponding to the change in the generator speed generated, wherein the difference between the digi tal signals indicating the phase change of the acoustic signal, which caused the motor of the generator by the change of has been , and at which the speed change of the generator away from its normal speed is finally stopped when the difference between the digital signals is a past

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reached a correct value, which indicates a predetermined phase shift.

Another object of the invention is to provide a system for measuring in a borehole while drilling to determine the conditions Measure down the borehole and send a modulated acoustic signal to the surface about the fluid in the borehole transmitted with the help of a motorized acoustic generator, which operates at a normally constant speed is operated, which is briefly changed according to the conditions to a change in the phase state of the to effect acoustic signal; here the system has the following devices: a device for changing the Speed of the generator based on normal speed; a device with at least one coupled, digital buffer to receive a signal which is the instantaneous Indicates the speed of the generator in order to generate a pair of digital signals corresponding to the change in speed, wherein the difference between the digital signals indicates the phase change of the acoustic signal caused by the change the engine speed has been caused; and a device for reducing the speed change of the generator, where the normal value is assumed when the difference between the digital signals is a selected value reached, which indicates a predetermined phase shift.

Furthermore, according to the invention, a method for measuring in a borehole while drilling is to be provided in order to obtain the Speed of a motorized, acoustic signal generator momentarily change from a normally constant speed by providing a carrier frequency signal to a selected phase change for modulating the carrier signal to effect, wherein (a) the generator speed is changed starting from the normal speeds to a part of the to accumulate or sum the selected phase change,

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and wherein (b) the generator speed to normal speed is fed back to thereby accumulate the remainder of the selected phase change, generating a control signal, when the phase change accumulated in any of steps (a) and (b) reaches a prescribed value, and wherein the prescribed value is set according to the phase change that occurs during at least one preceding step of the other steps (a) and (b) is accumulated.

Another object of the invention is to provide a system for measuring in a borehole while drilling to measure a parameter down the borehole and to transmit a modulated acoustic signal on the surface about the fluid in the borehole by means of a motorized acoustic generator which is operated at a normally constant speed to provide a carrier frequency which is momentarily changed according to conditions to effect a selected change in the phase state of the acoustic signal; Here the system has the following devices: a first device to change the generator speed, starting from the normal speed in order to accumulate or sum part of the selected phase change, and a second device to return the generator speed to the normal speed and to thereby accumulate the remainder of the selected phase change, the first device being coupled to one of the first and second devices and having a presettable accumulator circuit, uci generating a control signal when the value of the phase change reaches a predetermined value, and wherein the second device a phase accumulator for displaying the total value of the phase change accumulated in changing the engine speed and then returning to the normal speed to set the prescribed value corresponding to the total value of the phase change.

In addition, the invention also features a method for measuring

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during drilling, wherein a downhole arranged acoustic generator with a movable part is driven to emit an acoustic signal with a normally constant frequency to the fluid in the borehole, which is briefly changed to a required change in
effecting the phase state of the signal to thereby create encoded data states on the signal; In this case, the method has the following steps: (a) the speed of movement of the movable part is based on a first direction
changed by the speed creating a constant frequency; (b) the change in the first direction is stopped and interrupted when a predetermined phase shift,
which is smaller than the required phase change, has been accumulated or summed; the speed of movement
the portion is changed in a second direction towards the constant frequency creating speed to at least partially accumulate the remainder of the required value;

(d) an end of retraction signal is generated when the speed of the part has been returned to the constant frequency providing speed; and

(e) the change in the speed of movement of the part in the second direction is terminated in accordance with the signal indicating the end of the return.

Furthermore, according to the invention there is still a system for measuring while drilling is provided which comprises a motorized acoustic generator for transmitting an acoustic signal at a normally constant frequency to the fluid in the borehole, and having a speed change device to change the speed of the motor temporarily changing to effect a required change in the phase state of the signal, thereby creating modulated data states on the signal, the speed changing means comprising control circuitry including first means for changing the speed of the motor in a first direction; with a device for generating a signal pair, the difference of which is the phase change of the acoustic signal due to the change in the engine

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- Jir-

speed displays; comprising means for generating a control signal when the difference is a predetermined fourth reached, which is smaller than the required 'value of the phase change; with a second device that responds to the control signal is responsive to change the speed of the motor in a second direction, thereby at least partially doing the rest to accumulate the required value; and having means for generating an indicating the end of the return Signal when the speed of the motor has been reduced to the speed corresponding to the constant frequency, where the second means is responsive to the end of feedback signal and then to the change in speed stops or ends.

According to the invention, a system for measuring while drilling thus comprises a digitally implemented motor speed control circuit in order to control a motor-driven acoustic signal generator which is arranged downhole in the borehole. The acoustic generator is operated at appropriate speeds by means of the motor in order to transmit to the fluid in the borehole an acoustic signal with phase states which represent encoded data which have been obtained from the conditions measured below in the borehole. The digital motor control circuit controls the motor at a substantially constant, a carrier frequency creating speed in the absence of data of a (certain) logic state and temporarily changes the speed of the motor to a predetermined phase change in the carrier signal in the presence of data with a predetermined logic To effect state. When this data occurs, the engine speed is changed so as to deviate from the constant speed until a prescribed value of the predetermined phase change is reached. The engine speed is then brought back to constant speed to accumulate the remainder of the predetermined phase change. During operation, feedback is provided from the motor to determine the value of the prescribed amount

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27A3871

brought up to date according to the load conditions on the engine. A speed sensing circuit monitors the engine speed to generate a signal indicative of the engine speed change towards the constant speed ends exactly when the engine speed has returned to the constant speed or has reached it.

The invention is described below on the basis of preferred embodiments explained in detail with reference to the accompanying drawings. Show it:

Figure 1 is a schematic representation of a system according to the invention for drilling a wellbore and for measuring of data;

FIG. 2 is a block diagram of a system used in the system of FIG. 1 device used to transmit telemetry data from below from the borehole;

Fig. 3 is a block diagram of a logic circuit used in the device of Fig. 2;

4 shows examples of waveforms which illustrate the operation of the means for transmitting telemetry data from reproduce below from the borehole; and

5 is a functional block diagram of a compensation circuit, which is used in the device of FIG.

In Fig. 1, a system 10 for drilling a borehole is shown, associated with a system 12 according to the invention for measuring while drilling. For ease of presentation and Description, FIG. 1 shows a drilling system in use on land; of course one could also be on system usable in the sea.

When drilling a borehole 14 with the drilling system 10, feel

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the system 12, provided for measuring while drilling, the conditions downhole in the borehole and generates an acoustic signal Signal that is modulated according to the data created to represent conditions downhole. The acoustic Signal is transmitted to the drilling fluid, commonly referred to as drilling mud, in which the signal is transmitted to the surface of the borehole 14 is transmitted. At or near the surface of the borehole 14, the acoustic signal is sensed and processed to create recordable data that the Reproduce conditions downhole. The basic system is generally known and is described in detail in the aforementioned US Pat. No. 3,309,656, to which reference is hereby made,

The drilling system 10 is conventional and includes a drill string 20 and a derrick, not shown, which is secured by a hook 22 is shown carrying the drill pipe 20 in the borehole 14.

The drill pipe 20 includes a drill bit 24, one or more drill collars 26, and a length of drill pipe 28 that extends into the wellbore. The drill pipe 28 is connected to a square pipe 30 which extends through a revolving drive mechanism 32. Upon actuation of the drive mechanism 32 (by means not shown), the square tube 30 rotates, which in turn rotates the drill pipe 28 and drill bit 24. The square tube 40 is carried by the hook 22 via a swivel mount 34.

Near the entrance to the borehole 14 is a conventional system 40 which circulates the drilling fluid, commonly referred to as drilling mud, down the borehole . The drilling mud is circulated downwards via the drill pipe 28 during drilling, exits through nozzles in the drill bit 24 into the circular ring and is returned upwards.

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where it is resumed by the system 40. The circulation system 40 includes a drilling mud pump 42 that is provided to receive the drilling mud from a mud pit via a pipe 46. A shock absorbing Means 48 is connected to the output side of the mud pump 42 for any output from the pump 42 To remove shocks in the mud flow, so that then a continuous Sludge flow is discharged at the outlet 50. A line 52 connects the output 50 of the shock absorbing Device via an S-bend connected to the swivel mounting 34 with the square tube 30.

The mud coming back from the borehole occurs at the top End of "borehole 14 from an opening in casing 56, which creates a passage 58 between the walls of the borehole 14 and the drill pipe 28. A return line 60 transfers the returned sludge from the opening in the casing 56 to the sludge pit for recirculation 44.

The system 12 for measuring while drilling has nähme- a down downhole, an acoustic signal generating means 68 and a valve disposed outside the borehole and decoding data onto sys tea 70. The acoustic signal generating device 68 senses the downhole conditions and transmits coded acoustic signals to the drilling fluid. The acoustic signal is transmitted through the drilling fluid to the recording and decoding system 70 outside the borehole, where it is processed and displayed.

For this purpose, the recording and decoding system 70 has a signal processor 72 and a recording and display device . Processor 72 is coupled to hose lines 72 via line 76 and pressure transducer 78. The coded acoustic signal transmitted up through the drilling fluid is monitored by the transducer 78, which in turn generates electrical signals for the processor 72. This elec-

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tric signals are decoded into useful information, which reflects the downhole conditions, and the decoded information is recorded by means 74 and shown. One such data acquisition and decoding system 70 is described in U.S. Patent 3,886,495 which is hereby referred to.

The device generating the acoustic signal down in the borehole 68 is held in one of the drill collar 26 down the hole by means of a suspension mechanism 79 and generally includes a modulator 80 through which at least a portion of the mud flow passes. The modulator 80 is controllably driven to selectively control the flow of drilling fluid interrupt to activate the acoustic signal to transfer the drilling mud. An (interchangeable) insert 82 is provided to accommodate the various conditions below in To feel the borehole and to control the modulator 80 accordingly. The signal-pulling device 68 has a power supply 84 for feeding the insert 82. A number of centering devices 85 are provided, including the modulator 80, the Insert 82 and the power supply 84 in the middle of the pipe in the appropriate position.

The power supply 84 is well known and includes a turbine 86 located in the flow of drilling fluid around the To drive the rotor of an alternator or alternator 88. A voltage regulator 90 regulates the output voltage of the alternator 88 to a corresponding value for the insert 82.

The modulator 80 is also known and has a movable part in the form of a rotor 92 which is rotatable a stator 94 is supported. At least a portion of the mud flow passes through openings in the rotor 92 and the stator 94, and the rotating movement of the rotor selectively interrupts the flow of drilling fluid if the openings are not aligned which then sends the acoustic signal to the drilling

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fluid is transferred. The rotor 92 is coupled to a drive 96 with a reduction gear, which the rotor drives. The insert 82 is operatively connected to the drive 96 so that the rotor 92 is rotated at speeds, thereby creating an audible signal in the drilling fluid that (1) has a substantially constant carrier frequency which defines a reference phase value, and (2) an optionally producible phase shift with respect to the Creates reference phase value in the carrier frequency. The phase shift is indicated by coded data values reflecting the measured conditions downhole.

In the preferred embodiment, the drive is 96 and the designs of the rotor 92 and the stator 94 are chosen so that they are 1/5 of a carrier period in the acoustic signal for generate every revolution of the motor 102.

A corresponding modulator 80 is shown and described in detail in US Pat. No. 3,764,970, which goes back to the assignee of the present application. Other suitable modulators 5 3 are described in the aforementioned U.S. Patents 3,309,656 and 3,789,355 and in U.S. Patents 3,792,429 and 3,707,006, referred to hiermitbezug.

The insert 82 includes one or more sensors 100 and a data encoding circuit 101 associated therewith to measure the downhole conditions and to generate encoded data signals representative thereof. For example, the sensors 100 may be provided to monitor drilling parameters such as the direction of the borehole (the azimuth of the borehole deviation ), the load on the drill bit, the torque, and so on. The sensors can also be provided in order to monitor safety parameters, for example in order to sense overpressure zones (by means of specific resistance measurements) and fluid entry characteristic data by measuring the temperature of the drilling mud in the annulus 58. In addition , radiation detectors can

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teketoren can be provided, such as gamma-ray sensitive detectors for differentiating between slate and sand and for determining the depth correlation.

The data coding circuit 101 is conventional and has a multiplex arrangement in order to code the signals from the sensors into binary data and then to transmit these serially via a data line. A corresponding multiplex coding arrangement is described in detail in the aforementioned US Pat. No. 3,820,063, to which reference is hereby made. The insert 82 has a motor 102 coupled to the drive 96 and a motor control circuit 104 for controlling the speed of the motor 102, thereby rotating the rotor 92 of the modulator 80 at the appropriate speeds in order to effect the required modulation of the acoustic signal. The motor 102 is a conventional two-phase AC induction motor which, in the preferred embodiment, is controlled by the motor control circuit 102 at 60 Hz. The use of an induction motor for motor 102, although other types of motors, such as a DC servo, are suitable, is not critical.

The motor control circuit 104 is shown in FIG. 2 together with the motor 102, the sensors 100 and the encoder circuit 101 as well as the modulator 80. The motor control circuit 104 includes circuitry to (1) maintain the substantially constant carrier frequency of the acoustic signal transmitted to the drilling mud in phase, and (2) to change the frequency of the acoustic signal and change it to the carrier frequency to thereby change its phase by a predetermined value as quickly as possible in accordance with the encoded data. In the preferred embodiment in which the data from sensors 100 are binary coded, the phase change is 180 *.

The motor control circuit 104 has a motor switching arrangement 110, for example a conventional inverter, ta to supply two-phase power to the two-phase motor 102.

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A phase signal generator 112 and a voltage controlled oscillator (VCO) 144 are provided to generate a pair of phase signals 0A, 0B and their complements j? Ä ",] ΪΒ at the motor switching arrangement 110. The phase signals are 90 ° out of phase with one another. The voltage controlled oscillator 114 is of conventional embodiment and circuitry is conventional to generate 50% duty cycle waveforms and complements in phase signal generator 112. In the preferred embodiment, VCO circuit 114 operates at a frequency slightly higher than 240 Hz during This frequency causes the induction motor 102 to "slip" and provides a frequency multiplication factor of 4 which is necessary for the phase signal generator 112 to produce the phase signals 0A, 0B at the required frequency of 60 Hz. To simplify the description , the slip of the motor is assumed to be negligible in the following mmen.

In the preferred embodiment, the circuit for holding the carrier frequency and the phase of the acoustic signal in the absence of selected data signals in connection with the motor switching arrangement 110, the phase signal generator 112 and the voltage-controlled oscillator 114 advantageously represents a phase-locked circuit.

The phase and frequency holding circuit includes a tachometer 120 coupled to motor 102 to generate a series of pulses whose repetition rate indicates the frequency at which motor 102 is driven. In the preferred embodiment, the tachometer 102 is chosen to produce six periods per engine revolution. In conjunction with the design of the modulator 80, the design of the drive 96 and the speed of the motor 102 at 60Hz, this ratio leads to the generation of an acoustic signal in the drilling sump with a carrier frequency of 12Hz and the generation of a tachometer output signal.

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nals cj with a frequency of 360Hz.

A tachometer signal providing circuit 122 is coupled to the output of tachometer 120 to provide a loop frequency signal c having a relatively low frequency and a motor frequency signal 'having a relatively high frequency. For example, the loop _{frequency signal ^ x} is generated at a frequency of 24Hz and the motor frequency signal ei ,, at a frequency of 720Hz when the motor is operated at 60Hz. The circuit 122 is usually provided with a zero crossing circuit and a frequency multiplier / subcircuit.

The phase-locked loop circuit finally has a phase detector 124, which is responsive to the loop frequency signal to and to a loop reference frequency signal ^ _x ", in order to selectively generate a VCO control signal on a line 126, which via a loop switch 128 during operation with the voltage controlled oscillator 114 is connected. The phase detector 124 has a conventional embodiment and can have a set / reset flip-flop, not shown, which responds to the signals ti, t0, and a low-pass filter, not shown, which is coupled to the output of the flip-flop. At the output of the detector 124, the VCO control signal as a function of the difference per loop period between the ^t0 _T - and ^. -

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Signals are generated to thereby indicate that the motor 102 is deviating from the carrier frequency or phase. In accordance with the control signal on line 126, voltage-controlled oscillator 114 changes the excitation frequency supplied to motor 102 via inverter 110 in order to return the motor to phase and frequency entrainment or synchronization and to keep them there. In the aforementioned US Pat. No. 3,870,063 , another phase-locked loop circuit is shown and described which operates on similar principles.

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The circuit for changing the speed of the motor 102 to thereby changing the phase of the acoustic signal in accordance with data from sensors 100 is illustrated in FIG and preferred embodiment implemented digitally. The digital version causes a frequency and phase change in the acoustic signal quickly and extremely precisely. The size of the component for the motor control circuit is due to the digital version has been scaled down from the size of the previously used analog systems, and it is a high one Operational safety achieved over large environmental areas. But can the invention, if required, in a corresponding Way also in analog systems.

As already described, the circuit for changing the speed of the motor initially works in such a way that the speed of the motor 102 is decelerated and then accelerated to accumulate the total phase change of 180 to save. Although an acceleration / deceleration sequence is feasible, this sequence will result in motor 102 works with a higher rotation norm and consequently becomes the acoustic signal is more predictable and modulated in shorter time periods.

The speed change circuit operates switch 128 and a set of acceleration and deceleration switches 130 and 132 which control the voltage output on the voltage controlled oscillator 114 accordingly. In the illustrated Embodiment is the acceleration switch 130 with a Terminal connected to the input of the voltage controlled oscillator 114 and to one terminal of the loop switch 128. Its other connection is to a sawtooth voltage generating network and via a resistor R1 to the Delay switch 132 connected. The sawtooth voltage need not be limited to a linearly changing voltage. For example, it can change substantially exponentially over time. As shown, an RC generates timing circuit with a series circuit ^ consisting of a resistor R2

and a capacitor C between a voltage V1 and ground an exponentially increasing range voltage. If therefore loop switch 128 is open, acceleration switch 130 is closed, and deceleration switch 132 is open is, the input to the voltage controlled oscillator 114 is a sawtooth or ramp voltage that has an output the voltage controlled oscillator 114, which increases over time and thereby an acceleration of the motor causes what is an increasing function over time. This ensures that the phase change in the acoustic signal is carried out as soon as possible.

The acceleration switch 132 has a terminal which is connected to the resistor R1 and consequently to the switch 130. Its other terminal is connected to earth. When the acceleration switch 130 is closed and the deceleration switch 132 is also closed, the capacitor C, which has been discharged to earth via the resistor RI, since the switch 132 is closed, remains discharged. In the preferred embodiment, when the switch 130 is closed, the discharged capacitor C supplies a voltage level at the input of the voltage-controlled oscillator or the VCO circuit 114, which causes the output of the VCO circuit 114 to have an output from the otherwise constant carrier frequency of about 240Hz is transformed down to about 180Hz.

The speed change circuit includes a target phase accumulator 140, a motor frequency detector 142, and control logic 144 . In accordance with the input signals from the target phase accumulator 140 and from the motor frequency detector 142, the control logic 144 generates a group of control signals X, X and ~ Z on lines 145, 146 and 147 to the switches 128, 130 and 132, respectively. ie generated one after the other, which are accordingly triggered by data from the sensors, where (1) the loop switch first

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opened to remove control from the phase locked loop; (2) the acceleration switch 130 is closed (since the deceleration switch 132 is already closed) to apply a low voltage level to the VCO circuit, thereby causing the motor 102 to decelerate rapidly and thereby lower the frequency of the acoustic signal to about 180Hz change; (3) the acceleration switch 132 is opened while the acceleration switch 130 is left closed to begin accelerating the speed of the motor 102 back toward the carrier frequency creating speed, and (4) thereafter the acceleration switch 130 is opened and the Loop switch 128 is closed to return control of the motor 102 to the phase-locked loop when the speed of the motor 102 creating the carrier frequency has been reached.

This is described in detail with reference to the waveforms shown in FIG. The target phase accumulator 140 generates a TPA control signal on line 148 having a period referred to as the integration period IP corresponding to the accumulation of a predetermined phase change value after a transition start (TS timing signal) on a Line 149 has been generated. At the beginning of an integrating period IP, control logic circuit 144 is triggered to generate control signals X, X and ~ Z to open loop switch 128 and close acceleration switch 130, and to maintain the closure of deceleration switch 132, thereby the Motor 102 to decelerate.

The target phase accumulator 140 is a differential integrating circuit. That is, during the integration period, the target phase accumulator 140 effectively integrates the difference between a motor reference frequency signal Cj "_ of 720Hz on line 150 and the motor frequency signal

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'· ■> ■ on a line 152. In the illustrated embodiment, the signals - ^ and ^ - are integrated. The difference between these integrated signals provides an indication of the phase value to be accumulated as a result of changes in the speed of the motor 102. When the difference between the integrated values of the signals on lines 150 and 152 as a result of the delay in the engine speed reaches a predetermined value, the phase accumulator 140 generates the TPA signal on line 146, whereupon the control logic 144 opens the switch 132. This then allows the start of the rapid acceleration of the speed of the motor back to the speed generating the carrier frequency.

As outlined above for the illustrated embodiment, the engine Bazugsffreenzsignale cD on the line 150 is a signal of 720 Hz. This amounts to 60 periods of the motor reference frequency signal generated for each period of the carrier frequency of T 2Hz. Accordingly, 30 periods of the signal ^ 180 ° correspond to the phase of the 12 Hz-

¹ "MR

Carrier.

Since a finite time is required to bring the motor speed back to the speed generating a 60 Hz carrier frequency, the phase shift is accumulated or summed up during the feedback process in addition to the shift caused by the delay. With a typical load on the motor it has been found that about 60 ° of the phase change of the carrier falls during the return of the speed of the motor 102 from the frequency of 45 Hz back to the speed of 60 Hz generating the carrier frequency. Consequently, it is necessary to accumulate 115 ° of the phase change in the phase accumulator 140 before the generation of the TPA signal and hence from the start of the acceleration of the speed of the motor back to the 60 Hz. Since 30 periods of the signal CS “180 ° of the phase shift of the

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The target phase accumulator 140 must correspond to the carrier

115/180 χ 30 = 19 periods or counting processes Eq. 1

as the difference between the integrated signals · ~ and <- '"" accumulate or sum. The calculation in Eq. 1 is

MR
due to the characteristic linear relationship between a phase attenuation and a phase gain of the acoustic signal as a function of the change in the motor frequency signal ~ _M

The additional phase amount accumulated as a result of the motor speed feedback changes with the motor load. However, since the circuit holding the phase and frequency works with inputs with twice the carrier frequency of 12Hz, it acts to lock or pull the motor speed at 180 ° phase change, even if the phase change circuit on a. Range from 91 to 260 ° phase change amounts to. As will be described below, the setpoint of 115 ° phase change brought up to date and changed according to the load conditions on the engine 102. Because of this (i.e. because they is updated) the frequency changing circuit can make almost the exact amount of phase change required cause when it brings the speed of the motor back to the carrier frequency creating speed; to this At the point in time, it then returns control to the circuit holding the phase and frequency. This is the length of time is reduced to the minimum required for the phase locked loop circuit by the predetermined phase change amount to create accurate in the acoustic signal at the carrier frequency.

In the illustrated embodiment, in order to perform the differential integration, the phase accumulator 140 comprises a pair of digital accumulator or buffer circuits.

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genes in the form of a motor frequency counter 154 and a tachometer reference frequency counter 156 on. The motor frequency counter 154 can be preset to a value that provides a required phase damping (i.e. the target value of 115 °) due to the deceleration of the motor during the integration period. In the preferred embodiment, the counter 154 preset or updated after each coding by a targeting compensation circuit 157 Stand brought to set the target value according to the load conditions on your engine 102. To the To simplify the description of the target phase accumulator, it is assumed that the target compensation circuit 157 maintains the setpoint of 115 °, i.e. no changes in the load of the engine 102 occur.

The phase accumulator 140 has a digital comparator 158 which is coupled to the outputs of the counters 154 and 156 and determines when the tachometer reference frequency counter increments by a value of 19 more than the motor frequency counter 154. In this state, the comparator 158 outputs the TPÄ signal to the motor control logic 144 , which indicates that the desired value of 115 ° of the phase change has been accumulated or summed.

As shown in detail in FIG. 3, the motor frequency detector 142 and the control logic 144 cause the speed of the motor 102 to be accelerated back to the speed which creates a carrier frequency of 60 Hz. The detector 142 has a digital integrator which has a pair of adjustable counters 160 and 162 which are coupled to the output of an R / S flip-flop 164. The flip-flop 164 has a clock input which is connected to the line 152 to receive the motor frequency signal cd and to generate an enable signal via a pair of logic gates 166 and 168 via a line 170 to the counters 160 and 162 . Dais enable signal on line 170 is at fault

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len of the control signal Z on the line 147 at the reset terminal of the flip-flop 164 is generated. The control signal Έ on the line 147 is removed from the phase accumulator 140 by the control logic 144 when the TPA signal is generated (at the end of the integration period IP) on the line 148.

Since the motor 102 has been decelerated to a speed which is less than 60 Hz at the time of the occurrence of the TPA signal, the period of the motor frequency signal a> is longer than normal. The task of the presettable counters 160 and 162 is to determine when the period of the motor frequency signal ü) "indicates that the speed of the motor has been accelerated back to 60 Hz after the generation of the TPA signal. For this purpose, the counters 160 and 162 have preset lines, not shown, which define the number of counts that the counters 160 and 162 achieve when the period of the signal 10 is correct for operation at 60 Hz. The counters 160 and 162 also respond to a high frequency reference signal of 24kHs on a line 172 which provides a high frequency clock signal to the counters to increment them. The counters 160 and 162 are set to the value at which an MFD signal is generated on a line 174 when the reference signal of 24 kHz on the line 172 causes the number of counting processes, which are summed up by the counters 160 and 162: have been to exceed the preset value. The period of the enable signal on line 170 decreases over time as the motor accelerates. It is possible that the MFD signal on line 174 is not generated for a predetermined period of the enable signal, under this condition the motor 102 then operates again at the speed generating the carrier frequency.

The operation of the motor frequency detector 142 can be better understood in conjunction with the control logic illustrated in FIG. The control logic 144 has three R / S flip-flops 180,

809813/1114

182 and 184 and a NAND gate 186. The flip-flops 180 and 184 generate a Y signal on a line 187 and the Signals X and X on lines 146 and 145. The logic element 186 is connected to lines 146 and 187, around the signal Z ^ on line 147 as a function of the signals X and Y to generate.

The flip-flops 180 and 184 are responsive to the TS timing signal on line 149 and are activated upon the occurrence of data with a predetermined logic state sensed by the sensors 100. By setting of the flip-flop 184 a logical 1 and a logical 0 are generated as the signals X and X, whereby the acceleration and loop switches 130 and 128 are closed and opened, respectively. The flip-flop 180 generates a logic 0 as the Y signal on line 187 when asserted by the TS signal. The signal Y is then sent to the logic element 168 is applied to create a logic zero state of signal 55. When the TPA signal occurs at the end of the integration period IP, the flip-flop 180 is clock-controlled by the TPA signal on the line 148, whereby the signal Y in a logical 1 changed; will. During this interval, the signal Z has kept the delay switch 132 closed and has disabled operations of flip-flop 182 via the reset input.

When the TS timing signal was generated and consequently at the beginning of the integration period IP, the signals X, X and Έ each closed switch 130, opened switch 128 and kept switch 132 closed, causing motor 102 to decelerate.

At the end of the integration period, when the phase accumulator 140 has indicated that the required 115 ° phase has been accumulated, as indicated by the TPA signal on line 14t, the flip-flop 180 changes

809813/1114

its condition. This means that a logic 0 is applied to its data input and the TPA signal to its clock input will. This change in state generates a logical 1 as the signal Y on line 187, whereby a logic 0 is generated on line 147 as signal Ϊ. This opens the delay switch 132, which The deceleration phase of the motor change ended and the acceleration change or phase started.

In addition to the motor frequency detector 142, as is also shown in detail in FIG. 3, when the signal Z on the line 147 changes to a logic 0, the flip-flops 164 and 182 are triggered. A logic 1, which is applied to the data input of flip-flop 164, is then clocked by the motor frequency signal 'J , whereby a

logic 0 is generated at an input of the logic element 166. The other input of the element 166 receives the signal w ^: "on the line 152. The logic elements 166 and 168 generate the enable signal on the line 170 at the counters 160 and 162 in order to preset them at the beginning of each period of the signal u) _M. The counters then begin to count at a frequency of 24 kHz, as determined by the 24 kHz signal on line 172.

At the end of the release signal, that is to say at the end of a period of the motor frequency signal Ο «, when a transfer has taken place from the counter 162, ie when a logic 0 has been generated on the line 174 as the MFD signal, the flip- flop 182 remains in the reset state (which has been brought into the reset state by the signal ¹ L on the line 147 upon the occurrence of the signal X, which goes to the logic state zero, thereby indicating the end of the modulation.) Only under the conditions that a logic 1 is provided on the line 174 at the flip-flop 182, if an enable signal with the logic state 1 occurs, a clock signal is sent via a line 188 to the flip-flop 184

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create. When a clock signal is not established over line 188, flip-flop 184 holds signals X and X in the logical states 1 or 0, in which they are entered by the TS time control signals have been set.

If the counters 160 and 162 indicate that the period of the release signal, ie the duration of one period of the motor frequency signal '- _{M has been} reduced to a value which corresponds to a motor frequency of 60 Hz, no transfer from the counter 162 takes place. The logic 1 required to change the state of flip-flops 182 is then generated. This creates a clock signal and changes the state of flip-flop 184, which in turn changes the states of signals X and X, thereby closing loop switch 128 and opening acceleration switch 130.

In order to simplify the description of the circuit holding the phase and the frequency as well as the circuit holding the carrier frequency, it has so far been assumed that the targeting compensation circuit 187 sets the target value of the phase accumulator 140 at a constant phase 115 ° has been held. This does not correspond to a change in the load on the motor 102. During actual drilling operations in a borehole, however , load changes on the motor 102 occur. These load changes are quasi-static, so that they generally change only very slowly over time. The compensation circuit 157 senses these changes in the load on the motor 102 and sets the pre-setting of the phase accumulator 140, ie the setpoint previously identified as 115 °, so that the total phase shift is first caused by the deceleration and then by the acceleration of the motor during encoding is created in order to obtain the required total value . Since the compensation circuit works continuously , there is no previous knowledge of the load conditions

809813/1114

on the engine 102 is required.

In FIG. 5, the (targeting) compensation circuit 157 has a (targeting) correction circuit 190 and one end of the transition (EOT) phase accumulator 192 on. The EOT phase accumulator 192 calculates the total phase that has been summed up during each coding, i.e. that due to the deceleration and the acceleration of motor 102 and generates an EOT signal on line 194 to correction circuit 190, when the required total phase shift for coding has been summed. In the illustrated and preferred embodiment this phase shift is 180 ° for binary coded data. Correction circuit 190 responds to this EOT signal and sets the preset value of the phase accumulator 140 via a line 195 as a function thereof whether more or less than a phase of 180 ° has been summed by the accumulator 192.

The EOT phase accumulator 192 is actually another differential or Difference integrator, which corresponds to that which is provided for the phase accumulator 140 . The accumulator 192 generates the EOT signal when the difference between the integrated motor reference frequency signal ci _M _ and

MR

the motor frequency signal 'J _M exceeds a predetermined value which corresponds to the required total value of a phase change. In the illustrated and preferred embodiment, the differential integrator has a reference counter 196, a tachometer counter 198 and a comparator 200.

The reference counter 196 is responsive to the motor reference frequency signal uJwj on line 150 and to the TS timing signal on line 149 to generate an integrated motor reference frequency signal on line 202 at comparator 200. The integrated motor reference frequency signal reflects the value of the carrier frequency, which has been integrated over the period of time that occurs with the occurrence of the TS signal, ie with the occurrence of selected data from the coding

809813/1114

device 101 begins. The TS timing signal sets the counter 196 at the beginning of each integration period IP.

The tachometer counter 198 is responsive to the motor frequency signal i.0 "and the TS timing signal to generate an integrated motor frequency signal on a line 204. The integrated motor frequency signal - 'indicates the value of the instantaneous motor speed which has been integrated over the integration period IP which begins with the occurrence of each "" S timing signal. Corresponding to the reference counter 196, the tachometer counter 198 is also reset by the TS signal. Although not shown, the tachometer counter 198 is a programmable counter and has programming inputs which are set by a value which corresponds to a phase shift of 180 ° In the system described, this value is a count of 30. If the tachometer counter 193 is preset, a phase difference of 180 ° can be displayed when the integrated signals on lines 202 and 204 reach the same digital value.

The comparator 200 is pelt angekop to the lines 202 and 204 to sense when the digital values of inte th signals from the counters 196 and 198 are the same. This indicates that a 180 ° phase has been summed in the acoustic signal as a result of the operation of the frequency changing circuit. A blocking circuit ( not shown) is connected to the output of the comparator 200. Provided that the digital values become equal, the comparator 200 sets the inhibit circuit to produce the EOT signal on the line. The locking circuit is reset by the TS timing signal.

Correction circuit 100 includes preset counter 210, correction pulse generator 212, up / down control logic 214, and error pulse generator 216. the Correction circuit 190 responds to an EOT signal on the line

809813/1114

194 and on the signal X on line 145 to a signal on line 195 which is the preset value of motor frequency counter 154 in phase accumulator 140 updates depending on whether more or less than 180 ° phase shift during coding have been totaled. Accordingly, the motor load compensation for one coding is based on a previous one Coding or, in other words, the correction for an engine load during a given coding is the Compensation for the next coding that occurs.

The preset counter 210 is a conventional up / down counter, wherein a pair of series-connected is used up / down counter for 4 bits. The preset counter 210 receives a clock pulse on a line 217 from the correction pulse generator 212 if the total, summed phase shift during coding differs by more than a predetermined value from the nominal value of 180 °. In the illustrated. Embodiment, since each counter reading of the motor frequency counter 154 corresponds to 6 ° of a summed phase shift, each CP pulse that is generated at the preset counter 201 either increases or decreases the setpoint value of the motor frequency counter 154 by 6 ° (so that it becomes lower). Whether the counter 210 increases or decreases in value depends on a control pulse SP which is generated on a line 220 by the up / down control logic 214.

Correction pulse generator 212 includes a pair of serial four bit binary counters which are reset by the TS timing signal. The counters respond to a compensation reference frequency signal 'J _r on line 220 and to an error pulse EP from error pulse generator 216. If the error pulse EP lasts sufficiently long during the frequency of the signal cj_, a pulse is generated from the output of the counters to provide the clock pulse CP to the preset counter 210. The pulse CP

8Q9813 / 1114

is also coupled to the counters in generator 212 to reset them. Thus, by selecting one of several frequencies for the signal ^; ^ _TC the overflow or underflow value of the summed phase shift, by means of which a setting of the setpoint value of the preset counter 210 is controlled, adjustable. In the preferred embodiment, a frequency of about 380 Hz is used for the targeting compensation reference frequency signal Cv _TC .

The error pulse generator 216 is responsive to the X signal on line 145 and to the EOT signal on line 194 . In the preferred embodiment, the generator 216 is an exclusive OR circuit to generate an EP signal with a pulse width indicative of the time difference between the control feedback on the phase and frequency holding circuit (as indicated by the change in state of the X signal , and reaching the total phase of 180 ° (which is indicated by the EOT signal). The time difference is converted into a certain number of degrees of phase shift, which is either higher (exceeds the value) or lower than the nominal value of 180 °.

The up / down control logic 214 is responsive to the EOT signal on line 194 and the signal X on line 145 to generate the SP signal on line 220. The up / down Steuerlogikg in the preferred embodiment is to include an RS flip-flop having a clock input connected to the signal X, being a logic 1 applied to its data input, and which is reset by the EOT signal . Thus, the SP signal on line 210 is generated as either a logic 1 or a logic 0 depending on whether the X or EOT signals occurred first, thereby indicating whether control is being passed to the phase and frequency holding circuit has been that is returned to the phase-locked loop

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before or after a phase of 180 ° has been summed.

In Figure 2, the TS timing signal is in the usual way by means of a transition start circuit 230 is generated. The transition start circuit 230 generates a pulse as the TS timing signal upon the occurrence of data having a predetermined logic state, which is sensed by the sensors 100 and by means of the coding circuit 101 can be coded. In the illustrated In the preferred embodiment, the coding circuit codes 101 converts the data from the sensors 100 into binary data, and the transition start circuit 230 senses whether a signal with a logical 1 has been coded by the coding circuit 101 and generates the TS ~ timing signal accordingly.

The transition start circuit 230 is in that mentioned earlier US Pat. No. 3,820,063, to which reference has already been made. As stated above, this is feeling the motor speed during coding, whether it is done individually or in connection with the motor load, an excellent help to reduce system inaccuracies and / or to increase the speed of data transmission.

Claims

- 33 -

809813/1 1 U

L e r s e i f e

Claims (35)

- »ar- claims 1. Method of measuring in a borehole while drilling to determine the speed of a motorized acoustic signal generator to change from its normally constant speed from briefly to a corresponding phase change in the to effect an acoustic signal, the change in the speed of the generator from the normal speed takes place, thereby marked ichnet that a pair of digital signals corresponding to the generator speed change is generated, wherein the difference between the digital signals indicates the phase change of the acoustic signal caused by the change the engine speed of the generator has been effected; and that the change in the generator speed, if of its deviates from normal speed, is terminated when the difference between the digital signals reaches a predetermined value, which indicates a predetermined phase shift. 2. The method according to claim 1, characterized in that that when changing the speed of the generator initially the speed of the engine to a first relatively low value is decelerated, and that the speed of the motor is then accelerated, thereby bringing the speed to the normal bring back constant value. 3. The method according to any one of claims 1 or 2, characterized in that that data is generated in binary form for sensing parameters downhole, and that a change in the speed of the generator is only carried out when generating data with a certain logic state will. 4. The method according to any one of the preceding claims, characterized in that when generating a 809813/1114 ORIGINAL INSPECTED Pair of digital signals a first signal is generated which represents the normally constant generator speed, a second signal is generated which reflects the current speed of the acoustic signal generator, and that the first signal and the second signal are digitally integrated over a period of time that substantially coincides with the occurrence a parameter value felt down in the borehole begins. 5. The method according to claim 4, characterized in that that in the case of digital integration a programmable counter which reacts to either the first or the second signals responds, is preset to a predetermined value. 6. The method according to any one of the preceding claims, characterized characterized that when changing the generator speed a reduction in engine speed takes place, and that after Beenain the reduction in engine speed Speed of the motor is accelerated to the normally constant speed with a changing acceleration rate. 7. In-hole measuring device while drilling to measure conditions downhole and to the surface a modulated acoustic signal reflecting these circumstances about the fluid in the borehole transmitted with the help of a motorized, acoustic generator, which operates at a normally constant speed which is changed momentarily according to the conditions to a change in the phase state of the acoustic To effect a signal, the means comprising means for changing the speed of rotation of the generator when this deviates from the normal speed, in particular for carrying out the method according to one of the preceding claims, characterized by a device with at least one digital accumulator which is provided, to receive a signal that indicates the current speed of the generator to generate a pair of digital signals corresponding to 80981371114 COPV - ysr- accordingly to generate the speed change, the difference between the digital signals being the phase change of the acoustic Indicates the signal caused by the change in engine speed; and by a device for stopping and stop changing the generator speed as it is different from its normal value when the difference reaches a selected value between the digital values which indicates a predetermined phase shift. 8. Device according to claim 7, characterized in that that the digital accumulator provides at its output one of the pair of digital signals with a value equal to the indicates the instantaneous speed of the generator that has been integrated over a period of time that is essentially at the beginning the speed change with respect to the normal value begins, and that the digital signal generating device has a further digital accumulator which has the other signal of the pair of digital signals at its output with a Fourth, which indicates the normally constant acoustic signal frequency that is integrated over the time period. 9. Device according to claim 8, characterized in that the digital accumulators are digital counters show. 10. Device according to claim 9, characterized in that g e k e η η draw t that the predetermined phase shift is less than the full phase shift that is generated by the reflect conditions measured downhole together with the rest of the full phase shift, which is the case, when the engine is brought back to normal speed and that at least one of the counters is a programmable counter which is preset to a count which corresponds to the predetermined phase shift. 11. Device according to one of claims 7 to 10, characterized in that the stopping device 8 0 9 8 13/1 1 U COPY has a digital comparator that works on the first and responds to second digital signals. 12. Device according to one of claims 7 to 11, characterized indicated that the speed change, starting from the normal value, is a motor deceleration and that means for generating a sawtooth or ramp signal according to the selected value of the difference between the digital signals is provided what is achieved is used to cause the engine speed to accelerate as a function increasing with time. 13. Device according to one of claims 7 to 12, with a acoustic signal generator with a rotating transducer bit a rotor which is arranged to optionally 8en after interrupt the downward flow of drilling fluid, with a motor to turn the rotor, with one or more sensors to feel the conditions downhole and in order to generate coded signs representing these circumstances, and a control circuit connected to the sensor and the motor to control the operation of the motor accordingly to control the signals, characterized by a tachometer which is coupled to the motor in order to to establish the current engine speed on the digital signal generating device, with the digital signals generating device and the device which terminates the change in the engine speed is part of the control circuit, which has a phase and frequency holding circuit to keep the motor speed at the normally constant level according to the reference signal, the means for changing the speed of the motor if this is different from normal Speed differs, having means to the phase and frequency holding circuit of the motor separate. 14. method of measuring in a borehole while drilling, 809813 / 11U the speed of a motorized acoustic signal generator instantly change from a normally constant speed to generate a carrier frequency signal, to provide a selected phase change for modulating the carrier signal, where (a) is the generator speed with respect to normal speed is changed to sum a portion of the selected phase change; and (b) the generator speed is fed back to diohormal speed to thereby sum the remainder of the selected phase change, in particular according to one of claims 1 to 7, characterized in that a control signal is generated when the phase change summed up in one of method steps (a) and (b) reaches a prescribed value and that the prescribed value is set in accordance with the phase change which is summed up during at least one preceding step of the other method steps (a) and (b) is. 15. The method of claim 14, wherein the carrier signal is modulated accordingly intermittently occurring data, characterized in that when setting the prescribed value is addressed during a modulation to a phase change that occurred during the previous Modulation has been accumulated. 16. The method according to any one of claims 14 or 15, wherein the motor is initially decelerated and then accelerated to its normal speed wifa, characterized in that the prescribed value for a phase change accumulation is assigned to the delay stage. 17. The method according to any one of claims 14 to 16, characterized characterized in that when the control signal is generated, a signal is generated which represents the carrier frequency, another signal is generated, which reflects the current speed of the acoustic generator, the Trä- 809813/1114 gerfrequency signal and that reproducing the current speed Signal is integrated over a period of time that begins with the beginning of a speed change, and the control signal is generated when the difference between the integrated signals reaches a predetermined value. 18. The method according to claim 17, characterized in that the setting of the prescribed value is responsive to the difference between the integrated signals provided that the engine speed after generation of the control signal has been returned to its normal speed. 19. System for measuring a borehole while drilling to measure a parameter downhole and to the surface a modulated acoustic signal representing this parameter about the fluid in the borehole with the aid of a to transmit motorized acoustic generator, which is operated at a normally constant speed in order to to generate a carrier frequency which is instantaneously changed according to the conditions to a selected change of the phase state of the acoustic signal, the system having first means to determine the generator speed starting from normal speed to accumulate part of the selected phase change, and one second means to return the generator speed to the normal speed and thereby the rest of the to accumulate selected phase change, in particular for carrying out the method according to one of claims 1 to 7, characterized in that a first device is coupled to one of the first and second devices and has a presettable accumulator circuit to generate a control signal when the phase change is a prescribed value reached; and that second means comprises a phase accumulator for the total amount of the phase change the battery pack when changing the engine speed • 09813 / nU- has been mulated and. then brought back to normal speed accordingly to the prescribed value of the entire phase change. 20. System according to claim 19, characterized in that the setting device generates a correction signal at the device generating the control signal in order to set the presetting of the accumulator circuit when the total phase change differs from the selected phase by at least a predetermined value. 21. System according to any one of claims 19 or 20, characterized g e- denotes that the first means comprises a dif- ferentielle integrating circuit to generate the control signal when a predetermined value to the difference between (1) an integral carrier frequency signal, represents the value of the carrier frequency which has been integrated over a period of time which essentially begins with the occurrence of a particular value of a parameter measured downhole and (2) an integrated signal representing the instantaneous generator speed is exceeded which is the integral of the instantaneous Represents generator speed which has been integrated over the time period, the presettable accumulator providing one of the integrated signals. 22. System according to claims 20 and 21, characterized in that the setting device generates the correction signal corresponding to the difference between the integrated instantaneous generator speed and the integrated carrier frequency when the generator speed is fed back generated at its normal speed. 23. System according to claim 22, characterized by means for generating a signal in order to preset the accumulator circuit to the prescribed value, 809813/1114 which is a predetermined part of the selected phase change corresponds, the setting device providing the correction signal generated according to the phase that was accumulated during a previously occurring, brief speed change is. 24. System according to any one of claims 19 to 23, wherein the first and second means for changing the generator speed, means for decelerating the engine and, respectively Have devices for accelerating the engine, characterized in that the adjusting device on the engine speed responds to sense changing load conditions on the engine. 25. System according to one of claims 19 to 24, with one or more sensors in the borehole, with an acoustic generator which is arranged in the FIuB of the drilling fluid to the Interrupting fluid at a controlled speed with a motor connected between the sensor and the acoustic generator to stop the fluid flow at a speed to interrupt, which is controlled according to the output signal at the sensor, with a phase and frequency holding circuit that is effective to the generator at the normally constant speed in the absence of a sensor signal to control with a predetermined value, characterized in that the setting device corrects the prescribed value after the engine speed on their normal speed has been returned. 26. Method for measuring in a borehole while drilling Hit an acoustic generator located downhole in the borehole alt a moving part that is driven to An acoustic signal is sent to the drilling fluid at a normally constant frequency, which is changed is, uv to cause a required change in the phase state of the signal, thereby encoded data states in the • 09Ö13 / 11U To create a signal, in particular according to claim 1, characterized in that (a) the speed of rotation of the moving part in a first direction based on that generating the constant frequency Speed is changed; (b) the change in the first direction is terminated when a predetermined phase shift, which is smaller than the required phase change has been accumulated; (c) the speed of the part changed in a second direction towards the speed providing the constant frequency is to accumulate at least partially the remainder of the required value; (d) an end of feedback signal is generated when the speed of the part approaches the constant frequency generating speed has been fed back; and (e) the change in the speed of the part in the second direction corresponding to that indicating the end of the return Signal is terminated. 27. The method of claim 26, wherein the motor drives the acoustic generator and a control circuit drives the Keeps the motor at a normally constant speed in order to generate a reference phase, characterized in that that the operation of the control circuit is blocked during the speed change and the operation of the control circuit is enabled upon generation of the end-of-return signal. 28. The method of claim 27, wherein during the method steps (a) and (c) the motor is decelerated and then accelerated to its normal speed, characterized in that the acceleration of the motor this causes the motor to be energized with a function that changes over time. 809813/1114 ΊΟ 29. System for measuring in a borehole while drilling, with a motorized, acoustic generator to connect to the Drilling fluid to transmit an acoustic signal at a normally constant frequency, and with a speed change device, to change the speed of the motor briefly to make a required change in the phase state of the Signal to thereby create modulated data states in the signal, wherein the speed change means a control circuit with first means for changing the speed of the motor in a first direction, in particular for carrying out the method according to one of claims 1 to 7, identified by a device for generating a pair of signals, the difference of which indicates the phase change of the acoustic signal caused by Changing the engine speed has been caused; by means for generating a control signal when the difference reaches a predetermined value which is smaller than the required value of the phase change; through a second Means responsive to the control signal for changing the speed of the motor in a second direction to thereby accumulate at least partially the remainder of the required value; and through a facility to a the end of the Feedback indicating signal when the speed of the engine has been returned to the speed that the constant frequency, the second means being responsive to the end of feedback signal and the speed change ends. The system of claim 29, wherein the first means includes circuitry for retarding the speed of the engine to a first, has a relatively low value, and that the second device comprises a circuit for accelerating the speed of the Motor has to excite the motor with a function that changes with time, thereby increasing the speed to the constant speed. 809813/1114 31. The system of claim 29 or 30, wherein the one hold circuit for accurately adjusting the speed of the motor is provided to keep a reference phase at a constant frequency, characterized in that the first means includes circuitry for generating a signal that disables the hold circuit; and that the second Means comprising circuitry for generating a signal which the hold circuit upon generation of the end of the feedback the indicating signal. 32. System according to one of claims 29 to 31, characterized in that the means for generating of a control signal comprises an accumulator which is programmable to create the predetermined value and which responds to the pair of signals for generating the control signals and has a compensation means which is responsive to the difference responds to the pair of signals and which is connected to the accumulator by the predetermined value as a function of the phase accumulated during a previously occurring modulation of the acoustic signal is. 33. System according to one of claims 29 to 32, characterized in that that the means for generating a signal indicating the end of the feedback is an accumulator circuit responsive to a signal indicative of the speed of rotation of the part. 34. System according to claim 33, characterized in that the accumulator circuit has a programmable counter with a clock input which is provided to receive a high-frequency reference signal, and an enable connection to which the speed signal is coupled. 35. System according to claim 34, characterized in that the accumulator circuit further comprises a circuit 809813/1114 which is connected to the counter and is responsive to the speed and reference signals to an the end of the feedback to generate the indicative signal when the period of the speed signal is equal to a selected number of periods of the frequency signal is. 809813 / 11U