RU2521144C1 - Remote testing method for acoustic logging units in field conditions - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: modelling of actual acoustic wave signal and complete remote testing method for acoustic logging units in field conditions is made by decomposition of the input acoustic wave signal into spectral components and comparison of the obtained spectral response curve with the reference one.

EFFECT: improvement of logging data accuracy by remote testing method for acoustic logging units in field conditions.

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Description

The invention relates to oilfield geophysics, and in particular to acoustic logging equipment.

A well-known simulator of the signals of a borehole acoustic logging tool [US patent No. 3191142, class. 340-17, 1965], which is intended for the formation of acoustic and electrical impulses for the purpose of checking, tuning and calibrating the receiving path of downhole tools and the recording part of ground-based sonic equipment for longitudinal waves. The signal from the master oscillator, simulating the frequency of radiation and the repetition rate of radio pulses, as well as the signal power, is fed to an acoustic emitter (or emitters, depending on the structure of the downhole tool), from the output of which an elastic pulse is transmitted through the acoustic path to an acoustic receiver (s) and further into the recording part of the surface acoustic logging equipment. The specified device checks, adjusts, and calibrates the longitudinal wave acoustic logging equipment, since it only requires parameters such as the propagation time and amplitude of the first wave packet of the longitudinal wave from the full signal recorded by the receiver of the downhole tool.

In connection with the advent of wave acoustic logging equipment, it became necessary to simulate the parameters of the complete signal from the acoustic receiver — the optimal number of wave packets, their arrival time, frequency, amplitude, envelope envelope and its duration.

Part of this task is solved by an electronic simulator of downhole tool signals for acoustic logging [USSR AS No. 295870, class. ЕВВ 47/00, 1972], which contains a master oscillator, two shock excitation generators, a noise generator, a mixer, a cycle generator and an interval time meter. The signal from the simulator output is an approximate copy of the electrical signal from the acoustic receiver of the downhole tool.

The disadvantage of this simulator is that the simulated signal for each channel contains only one wave packet (synthesized longitudinal wave), the frequency of the signal in the packet is constant, its duration is fixed, therefore it does not correspond to the complete real signal from the borehole acoustic logging tool - the wave pattern.

Closest to the proposed method is a method of an electronic simulator of the signals of a borehole acoustic logging tool, by means of which a real acoustic wave signal is modeled [USSR AS No. 557339, class. G01V 1/40, 1977], implemented by a device comprising a wave pattern mixer and several wave pattern generators.

The disadvantage of this method is the lack of reliability of the device, the low accuracy of the measurement and the need for constant monitoring of the radiation parameters of the acoustic signals by direct manual tuning.

The objective of the invention is to increase the reliability and accuracy of the measurement method.

The technical result is the provision of remote testing for acoustic logging tools in the field.

The problem is solved, and the technical result is achieved by the fact that the method of testing acoustic logging instruments, which simulate a real acoustic wave signal, according to the invention, realize it in the field, and before modeling the acoustic wave signal, measure acoustic signals reproduced by the emitting probes of the device under test which provide the necessary transformations and direct to the measuring probes of the device under test in e real acoustic signals, then by means of the device under test, these signals are sent to the computer via a geophysical cable, and the signals received from the emitting probes of the device under test are transmitted wirelessly to the same computer, after which these signals are decomposed into spectral components and the spectral components are compared the components of the measuring signals with the spectral components of the reference signals, and the discrepancy of the spectral characteristics is used to judge the performance of the test under ora.

The invention is illustrated by drawings. In Fig.1 shows a structural diagram of the device, Fig.2 is a diagram of the operation of the device with an acoustic logging tool.

The acoustic logging testing device comprises a series-connected circuit consisting of a first ultrasonic wave receiver 1, a first band-pass filter 2, a first input amplifier 3 and the same series-connected circuit from a second ultrasonic wave receiver 4, a second band-pass filter 5, and a second input amplifier 6. Both circuits are connected to two inputs of an analog-to-digital converter (ADC) unit 7, which in turn is connected in series with a microcontroller (MK) 8, to which a Wi-Fi 9 module and a digital-analog unit are connected ovogo converter (DAC) 10. The two outputs of the DACs are connected in series within the chain, the first of which contains a first output amplifier 11 and a first source of ultrasonic waves 12, and the second output includes a second amplifier 13 and a second source of ultrasonic waves 14.

The device for remote testing of acoustic logging tools works as follows: the acoustic signal emitted by the probe of the tested device, arriving at the first receiver of ultrasonic waves 1, passes through the first bandpass filter 2 and the first input amplifier 3 to the ADC unit 7. Then the received signal is converted into a digital signal and received to the microcontroller (MK) 8. From the microcontroller 8, the digitized signal via the Wi-Fi 9 wireless module is transmitted to the computer for further analysis. Meanwhile, the same signal after a time delay, depending on the parameters of the device and the number of receivers, from the microcontroller 8 comes to the DAC unit 10, where it is converted into an analog signal and amplified by the first output amplifier 11. Next, an acoustic signal is reproduced from the output of the first ultrasonic wave source 12 , which ultimately comes to the measuring probes of the device under test and from the output of the device under test through a geophysical cable is transmitted to the computer. The computer database stores the protocols of earlier device tests. And according to the data obtained on a computer, the spectral characteristics of the device are compared with the spectral characteristics protocols stored in the database.

Based on the results of comparison and analysis of the obtained spectral characteristics with the protocols of the computer database, a conclusion is drawn about possible malfunctions in the operation of the instrument probes.

To organize wireless communication with a computer, the XBEE module is used, which makes it possible to use the ZigBee standard for wireless data transmission.

An example of a specific implementation of the method.

An acoustic signal is supplied to the ultrasonic wave receiver, then, through the ADC block, the signal arrives at the computer, where the acoustic signal is processed in the Lab View development and execution environment.

As a receiver of acoustic vibrations, a virtual Formula Waveform device (VP) is used, which allows you to set the shape of the output signal using mathematical expressions. At the output, we have damped harmonic oscillations:

, $$x(t)=e^{-w_{0}t}({\alpha }_{\mathrm{one}}\cos (wt)+{\alpha }_2\sin (wt))\text{(one)}$$

,

where x (t) is the input signal,

α ₁ , α ₂ - the amplitudes of the components of the input signal,

w is the frequency of the input signal (should be, as a rule, in the range from 10 to 30 kHz).

To simulate the action of the noise component of the signal, White Noise Waveform VIs are used.

To add an information signal with interference, use Formula VP:

, $$x_y(t)=e^{-w_{0}t}({\alpha }_{\mathrm{one}}\cos (wt)+{\alpha }_2\sin (wt))+h(t)\text{(2)}$$

,

where x _y (t) is the sum of the input signal and its noise component.

Using the Filter VI, the signal is filtered in the frequency range from 10 kHz to 30 kHz.

As a result of this conversion, the interference components that are not included in the filter passband are removed:

, $$x_F(t)=e^{-w_{0}t}({\alpha }_{\mathrm{one}}\cos (wt)+{\alpha }_2\sin (wt))+\text{h (t) (3)}$$

,

where x _F (t) is the filtered signal.

After that, the signal is converted from analog to digital form using the Analog to Digital VI, in which the bit depth of the used ADC is set to 10. Such bit depth allows to obtain a signal conversion error of not more than 3%.

Using the Get Waveform Components virtual instrument, the digital signal is decomposed into spectral components, after which the information is written to the Write to Binary File, where the input wave pattern is directly saved.

The digital signal from the ADC is fed to the DAC, presented as a Digital to Analog ID. After conversion, the signal enters the emitters.

The operation of the device with an acoustic logging tool is shown in the diagram (figure 2).

From the obtained diagram, we see that the RESULT signal, which is a filtered version of the SUM signal, almost completely coincides with the SIGNAL diagram. The signal conversion error in amplitude did not exceed 2%, in frequency it was 2.5%. Thus, the device for remote testing of acoustic logging instruments fully fulfills the task assigned to it, and the tested acoustic logging instrument passed the test with a positive result.

So, the claimed invention improves the accuracy and reliability of the method, as well as expand the functionality through the use of remote testing in the field.

Claims (1)

A method for testing acoustic logging instruments, which simulate a real acoustic wave signal, characterized in that it is realized in the field, and before modeling the acoustic wave signal, measure acoustic signals reproduced by the emitting probes of the instrument under test, which provide the necessary transformations and direct them to the measuring ones probes of the device under test in the form of real acoustic signals, then through the device under test These signals are sent to the computer via a geophysical cable, and the signals received from the emitting probes of the device under test are transmitted wirelessly to the same computer, after which these signals are laid out on the spectral components and the spectral components of the measuring signals are compared with the spectral components of the reference signals and the difference in spectral characteristics is used to judge the performance of the device under test.

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