SU1719627A1 - Turbodrill shaft rotation speed controller - Google Patents

Abstract

The invention relates to the drilling of wells and improves the accuracy of monitoring the frequency of rotation of a turbo-drill shaft. In the device, the vibration sensor 1 registers the vibrations of the drill string. Next, band-pass filter 3 allocates the frequency band in which the fundamental harmonic of the signal under study is contained. From the output of filter 3, the informative signal goes directly to the first input of the correlation analyzer 5, and to the second input through the unit 4 of the controlled delay line. Analyzer 5 determines the autocorrelation function of a vibro-acoustic signal. The frequency of variation of the maximum of this function with a linear increase in the time delay determines the frequency of the main harmonic of the shaft of the turbo-drill. The result is displayed by the display unit 10. The control unit 11 ensures synchronous operation of the controllable delay line unit 4, the analyzer 5 and the display unit 10. 2 Il. SP G o o th vj

Description

The invention relates to the telecontrol of downhole parameters in the process of turbine drilling of oil wells, in particular, to the monitoring of the frequency of rotation in a turbodrill.

Continuous monitoring of the frequency of revolutions of the bit makes it possible to maintain such loads on the bit that are optimal for the operation of the downhole motor and the bit, which ultimately contributes to an increase in the penetration rate, an increase in the penetration of the bit. Precise control over the bit turn is the most relevant for turbine directional drilling, in which it is very difficult to estimate the bit load from the surface and the bit rotation frequency is the most acceptable parameter for optimizing the drilling mode.

A device is known for controlling the frequency of rotation of a turbodrill shaft via a mechanical communication channel, in which the elastic vibrations of the drill string are converted into an electrical signal, which subsequently enters the measuring device, where the input band-pass filters divide this signal into low-frequency and high-frequency components with ranges of 20- 120 and 120-250 Hz respectively. Considering that the low-frequency components are caused by rolling the bit cones on a wave-shaped bottom surface, and high-frequency components are caused by rolling the cones from tooth to tooth on the bottom of a borehole, evaluation of the frequency of rotation of the turbo-drill shaft in the device is carried out using two algorithms — low or high frequencies. The choice of one or another algorithm is carried out by comparing the averaged values of the amplitudes of the signals in both ranges. If the signal is dominated by low-frequency components, the frequency is controlled at low frequencies by the number of drill string dips on the bumps, and if high frequencies prevail, by the number of blows of the roller cones about the bottomhole per unit time.

The disadvantage of this device is low accuracy and maintenance complexity, due to the fact that the bumps in the bottom, which explain the origin of low-frequency components, are inherent only in hard rocks and are not characteristic of relatively soft rocks. In addition, the hardware implementation of the device is complex and the required measurement accuracy implies the use of small computers or other computing devices for processing signals, which limits its use as a stand-alone device.

Closest to the proposed device is to control the frequency

rotation of a turbodrill shaft containing a vibration sensor mounted on a swivel and intended to convert mechanical vibrations of a drill string into an electrical signal whose output is sub key to the input of an amplifier intended to amplify and form an analyzed signal whose output is connected to the input of an analog-digital converter designed for a student of the digital form of the analyzed signal, the output of which is connected to a memory block intended for storing the ordinates of the analyzed signal process whose output is connected to the correlation

0 to the analyzer, which performs specialized processing of the initial process, one output of which is connected to the control unit, and the other output is connected to the input of the display unit, intended for visual display of current information. The control unit, the outputs of which are connected respectively to the control inputs of the analog-digital converter, the correlation analyzer and

0 of the reference signal generator, serves to generate control signals.

The reference signal generator is designed to form a reference frequency signal necessary for specialized processing of the original signal. The generator output is connected to the input of the correlation analyzer.

In the correlation analyzer, the signal from the control unit is calculated

0 values of the mutual correlation function between the original process coming from the memory unit and the reference signal produced by the reference signal generator, and the time shift between them

5 is implemented in a memory unit. The maximum value of the mutual correlation function is obtained when the frequency of the reference signal coincides with the frequency of the useful signal supplied to the device in a mixture with

Q random disturbance.

As the function is calculated for each frequency of the reference signal in the correlation analyzer, the maximum value of this function is selected and the frequency corresponding to this maximum is determined. The value of this frequency corresponds to the frequency of rotation of the bit in the bottomhole.

The selection of the frequency corresponding to the rotation frequency of the turbodrill shaft from the test signal using correlation processing eliminates the effect of the random frequency and phase on the measurement results, since the random signal is set in accordance with the most probable deterministic signal, and the final results are based on corresponding determining signal, which significantly improves the measurement accuracy compared to previously known devices.

The disadvantage of this device is low measurement accuracy due to the following reasons.

In this device, the frequency ranges of the signal being studied and the reference frequency generator are not limited. This can lead to the appearance of additional peaks in the cross-correlation function, for example, at frequencies caused by the rotation of bits of bits and the cutting of teeth of the cutters on the rock. Depending on which of these frequencies at a given moment of time corresponds to a larger value of the cross-correlation function, a particular frequency value is selected in the device, which at a constant coefficient of recalculation of it into the rotation frequency of the turbo-drill shaft leads to incorrect results.

In addition, the device does not take into account the phase relationships between the signal being analyzed and the signal produced by the reference generator.

Depending on the phase correspondence of the studied and reference signals, the value of their mutual correlation function is different. For example, when they are in phase, the mutual correlation function has a positive maximum, and when they are in antiphase, has a negative maximum. With an arbitrary phase relation, the mutual correlation function has some intermediate value. Thus, it is not possible to adequately estimate and compare among themselves two arbitrary values of the cross-correlation function for different values of the frequency of the reference oscillator.

The purpose of the invention is to improve the accuracy of controlling the rotational speed by using the time shifted test signal as a reference signal.

The goal is achieved by the device for monitoring the frequency of rotation of a turbodrill shaft, comprising a vibration sensor, the output of which is connected to an amplifier input, a correlation analyzer, a display unit and a control unit, including

The generator, the output of the correlation analyzer is connected to the input of the display unit, the output of the control unit is connected to the first control input of the correlation analyzer, equipped with a bandpass filter and a controllable delay unit. and a counter is entered into the control unit, the code transducer is a period-frequency divider, the first and second drivers, the amplifier output being connected to a bandpass filter input, the output of which is connected simultaneously with the first input of the correlation analyzer and the control delay block input, the output of the latter is connected to the second input of the correlation analyzer, and in the control unit, the generator output is connected to the input of the divider, the output of which, being simultaneously the first output of the control unit, is connected to the first control the correlation analyzer and the counter input, the first output of which is connected to the combined inputs of the first and second drivers, and the second output is connected to the converter input; the code is the duration, the output of which is simultaneously the second output of the control unit, connected to the control input of the control unit delays, the output of the second driver, which is simultaneously the fourth output of the control unit, is connected to the control input of the display unit.

The essential difference of this device is that it allows to measure the frequency corresponding to the main harmonic of the revolutions of the turbo-drill shaft in a certain frequency band, whereas in the known device the range of frequencies under study is not limited and the prevailing frequency having the maximum amplitude, and the frequency of rotation of the turbodrill is calculated from this dominant frequency, although this dominant frequency may be due to others, for example, geological or technological factors for them. In addition, in the known device, the given frequency is determined by the best correlation of the signal under study with the reference frequency of the tunable generator without taking into account the fzzopy relations between them, and in the proposed device, the time-shifted signal itself is used as a reference signal, and its autocorrelation a function that is already a function not of frequency, but of a time shift. The prevailing frequency, equal to the main harmonic of the turbodrill speed, is determined by the apparent frequency of repetition of the autocorrelation function maximum with a linear increase in the time delay. Thus, in this device, the frequency component that has the maximum spectral density is detected by the autocorrelation method in the band pass filter transparency.

Thus, the accuracy of the measurement of the frequency of revolutions of the turbo-drill shaft during the drilling process is improved.

FIG. 1 shows a block diagram of the proposed device; FIG. 2 is a time diagram of the operation of the device.

The device contains a vibration sensor 1, amplifier 2, a band-pass filter 3, a controllable delayed unit 4, a correlation analyzer 5, including a multiplier 6, an integrator 7, a comparator 8, a binary-decimal counter 9, an indication unit 10, a control unit 11 that includes a code-period converter 12, a generator 13, a frequency divider 14, a counter 15, a first pulse shaper 16 and a second pulse shaper 17.

Functional nodes are connected as follows.

The output of the vibration sensor 1 through the amplifier 2 is connected to the input of the band-pass filter 3. The output of the band-pass filter is connected simultaneously to the first input of the correlation analyzer 5 and the input of block 4 of the controlled delay, the output of which is connected to the second input of the correlation analyzer 5. First output of the block 11 of the control is connected to the first control input of the correlation analyzer, the second output is connected to the control input of the unit 4 of the controlled delay line, and the third and fourth outputs are connected respectively to the second control Valid yuschemu correlation analyzer 5 and to a control input of the display unit 10. The input of the latter is connected to the output of the correlation analyzer 5, and in the latter the output of multiplier 6 is connected to the input of integrator 7, the output of which is connected to the input of the comparator 8. The output of the latter is connected to the input of the binary-decimal counter 9. The first and second inputs of the multiplier 6 are respectively, the first and second inputs of the correlation analyzer 5, the control input of the integrator 7 is the first control input of the correlation analyzer 5, the control input of the binary decimal counter 9 is the second control input correlation

analyzer, and the output of the binary-decimal counter 9 is the output of the correlation analyzer 5. In the control unit 11, the output of the generator 13 is connected via frequency divider 14 to the input of counter 15, the first output of which is connected to the inputs of the first and second drivers 16 and 17 of the pulse, respectively and the second output - with the input of the converter 12 code - period. Output

the frequency divider 14 is the first output, the output of the code-period converter 12 is the second output, and the outputs of the first and second pulse shapers 16 and 17 of the pulse, respectively, are the third and fourth outputs of the control unit 11.

The device works as follows.

The electrical signal from the output of the sensor 1 vibration through the amplifier 2, where the signal

is normalized by the level depending on the value of the sigmal from the sensor, is fed to the input of the band-pass filter 3. The latter is intended to suppress the signal of the infrared pumping and high-frequency

tooth frequency components and allocation of a frequency band in which the main harmonic from the revolutions of the turbo-drill shaft is present. The transparency band of the filter is 2–15 Hz. Filtered informative

the signal from the output of the bandpass filter 3 is fed to the first input of the correlation analyzer 5, the second input of which receives the same signal through the controlled delay unit 4 with a certain time lag. The magnitude of the time shift t is determined by the value of the control frequency supplied from the first output of the control unit 11.

In the correlation analyzer 5, the autocorrelation function K (t, g) of the vibroacoustic signal U (t) under study is calculated with a linearly varying time shift:

K (t, T)

J t

t + t

/ U (t) -U (t-.T) dt, t

where T is the evaluation time of the autocorrelation function (or integration time),

With a linear in time change in the delay m (t), the visible period (frequency) of the autocorrelation function along the axis c. Corresponds to the prevailing period (frequency) of the analyzed signal U (t) in

real time i. the frequency of repetition of the maximum of the autocorrelation function along the time axis r is equal to the prevailing frequency of the signal. In one complete measurement cycle over which r (t) runs

values from tMin to gmah, the average frequency of rotation of the shaft of the turbo-drill F is determined by the expression

g

N

Gmax

where N is the number of periods of variation of the autocorrelation function.

In the comparator 8, the frequency of variation of the value of the autocorrelation function is converted into square pulses of the same frequency, which are subsequently read out by a binary-decimal counter 9.

The control unit 11 is designed to generate control signals that ensure the joint coordinated operation of the controllable delay unit 4, the correlation analyzer 5 and the display unit 10. Pulses with a frequency of 1 MHz from the output of the generator 13 are fed to the input of the divider 14, from the output of which pulses with a frequency of 1 Hz are fed to the input of the counter 15 and the integrator 7 (Fig. 1 and 2). The code on the second output of counter 15 after each pulse from divider 14 is incremented by one bit. . Accordingly, at the output of the code-period converter 12, the period of the control pulses - TUr also increases. As the period of the control pulses increases, the delay time in block 4 of the controlled delay also increases. After each 100th pulse, a rectangular pulse appears at the input of the first counter output, on the leading front of which the second pulse shaper 17 forms a short pulse. Overwrite, which information corresponding to the frequency value of the turbo-drill shaft speed during the measurement cycle, is output binary - the internal counter 9 is overwritten in the display unit 10. On the trailing edge of the indicated pulse, the counter 15 is reset to the zero state, and in the first driver 16 a short pulse is generated, which resets the binary-decimal counter 9. After this, the next measurement cycle automatically begins.

In the code-period converter 12, the counter code of the counter 15 is compared with the code of the internal counter, the value of which increases with a frequency of 100 kHz fC4 from zero. The period (frequency) of control pulses at the output of converter 12 varies with the rate of code change at the output of counter 15, i.e. once per second, and the change range is determined by the maximum possible code value

at the output of the counter 15 and the frequency of the counting pulses W at the input of the internal counter of the converter 12, and is determined by the formula

Tupr. Code (account 15) -

Ti

one

As in the proposed device, the code 10 of the counter 15 varies in the range of 1-100. and Tsch 100 kHz, the range of the period change

15

Tupr. (min) 1 10 / g S;

ten

1 TuPr (max) 100 1000m S. 10b

five

0

five

0

five

0

Controlled delay unit 4 includes two serially connected delay lines (the output of the first channel is connected to the output of the second channel). The delay in block 4 is determined by the period (frequency) of the control pulses Tupr:

g 1024-Tupra, from here

t „in 1024-10 10m5;

gmax 1024-1000-1 s.

In the device, the accuracy is improved by measuring the frequency corresponding to the revolutions of the turbo-drill shaft, by measuring the repetition period of the maximum of the autocorrelation function of the vibro-acoustic signal under study.

The high accuracy of measurements contributes to the successful solution of the problem of optimizing the turbine drilling mode, and allows obtaining higher technical and economic drilling performance. .

Claims (1)

Invention Formula A device for monitoring the rotational speed of a turbodrill shaft, comprising a vibration sensor, the output of which is connected to the amplifier input, a correlation analyzer, the output of which is connected to the input of the display unit, and a control unit, the first output of which is connected to the first control input of the correlation analyzer, The control unit contains a generator, characterized in that, in order to increase the accuracy of control of the rotational speed, the device is equipped with a bandpass filter and a controllable 5 delay unit, and entered into the control unit a frequency divider, a counter, a code converter — a period and two pulse shapers, while the amplifier output is connected to the broken input through a band-pass filter 0 correlation analyzer and with the input of the controllable delay line unit, the output of which is connected to the second input of the correlation analyzer, the second output of the control unit is connected to the control input of the controllable delay line unit, and the third and fourth outputs of the control unit are connected respectively to the second control unit input to the correlation analyzer and to the control input of the display unit, and in the control unit output 0 the generator through a frequency divider is connected to the input of the counter, the first output of which is connected to the inputs of the first and second pulse shapers, and the second output - to the converter input code - period, the output of the frequency divider is the first output, the output of the code converter - period is the second output and the outputs of the first and second pulse formers are respectively the third and fourth outputs of the control unit. Hw / h. / H Out 72 | | H I ass Reset scores 15 Reset Art. /five Ф№2