SU1337852A1 - Device for suppressing over-housing wave in acoustic well logging devices - Google Patents

Abstract

The invention relates to acoustic logging and a mopping tool used in well instruments with hard probes. The goal is to increase the accuracy of the measured parameters n (). Of useful waves by eliminating the distortions of the io. The device contains a pressure receiver, a mixing speed receiver, a matching unit, a delay BpeveHiioii device, a phase-amplitude function generator, a subtraction circuit, an information transmission channel, an emitter, a well bottom device. To receive n (), 1 s but (w), a receiver is used. After matching, delaying and inverting, the received signal is subtracted from the signal received by the pressure receiver, which increases the reliability of the measured parameters. 2 Il. S (L with OO OO ate CCHE

Description

This invention relates to acoustic logging equipment and can be used in downhole tools with rigid probes.

The aim of the invention is to increase the quality and reliability of the measured parameters of elastic waves by suppressing the wave through the probe body.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 oscillograms for his work.

The device includes a pressure receiver I, a shift speed receiver 2, a matching unit 3, a time delay device 4, a phase-amplitude conversion unit 5, a subtraction circuit 6, an information transmission channel 7, an emitter 8, and a housing 9 for a downhole tool.

In the drawing, the arrows indicate: 10, but completely empty, extending from the radiator 8 to the receivers 1 and 2 in the rock and the washing liquid, And - the rays of the noise-interference and propagation waveform

housing 9.

In order to ensure device operation, it is necessary that the axis of symmetry of the diagrams of the receiver's directivity and the displacement and probe velocities coincide, and the amplitude-frequency characteristics of the pressure and displacement receivers are uniform throughout the spectrum of the emitted frequencies. This is achieved by selecting a design choice and receiver orientation. So, for a receiver of pressure, in the form of a sphere from 11ezo:,; 1 of a critical () material, such a diameter of a sphere must be selected, at which pc the resonant frequency of such a receiver is higher than the maximum frequency of the spectrum of the radiated and pulsed pulse. For the receiver of the speed of displacement, the rigidity of the catuki c () suspension should be such that the resonance frequency of the sub-range is lower than the lowest frequency in the spectrum of the emitted acoustic imp; 1s.

The device works as follows.

Radiate. 1-8 excites elastic oscillations in the flushing fluid, which propagate toward receivers 1 and 2 through the flushing fluid and the surrounding well (useful waves) and through the well. housing 9 (wave-disturbance). Useful waves are perceived by receivers 1 and 2 only through the washing liquid, i.e., in the form of a wave, a wave. 1eni, and the wave-to-noise is received at first reception) with 1x2 of the velocity of displacement through the rigid body 9 in the form of a compression wave, and then by the pressure receiver I through the liquid already in the form of a pressure wave.

The output signal from the receiver 2 of the speed of mixing (Fig. 2a) enters the 3 coAg, block of 1, where it is converted into a form that is used to perform its time delay, for example, an amplitude-modulated high-frequency signal. From the output of the matching unit 3, the converted signal enters the time delay device 4 (this may be, for example, an ultrasonic delay line), where it is delayed by the wave propagation time through the body between receivers 2 and 1. From the output of the time delay device 4, the signal arrives at block 5 phase-amplitude transformations, where its original shape is restored (Fig. 2b), and the phase and amplitude are adjusted to the wave signal across the body in the common signal of pressure receiver 1.

Phase-amplitude transform unit 5 can be made in the form of a demodulator, to the output of which a voltage amplifier loaded with a resistive motor is connected. The signal from the output of phase amplitude conversion unit 5 (Fig. 2b) is fed to one of the inputs of the subtraction circuit 6, and the signal from the pressure receiver 1 is supplied to the other input (Fig. 2c). In the subtraction circuit 6, one signal is subtracted from the other. Since one signal

represents mainly a wave through the body, then at the output of the subtraction circuit 6 (FIG. 2 c) the resulting signal does not contain a wave signal through the body. The simplest implementation of a subtraction circuit can be a differential amplifier. From the output of the subtractor 6 of the subtraction signal, the signal cleared from the signal circuit through the body enters the input of the information transfer channel 7. It is amplified in power and transmitted to the surface for processing.

The use of the invention allows to increase the reliability of determining the parameters of elastic waves, especially in low-speed sections and when registering shear and tube waves, as well as to simplify the design and increase the rigidity of acoustic insulators, hence the quality of the acoustic logging primary materials increases. beam alignment in the well.

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Claims (1)

Invention Formula An apparatus for suppressing a wave over a housing in an acoustic logging tool, comprising a pressure receiver for receiving a full acoustic signal and a receiver acoustic oscillations caused by the wave but the body of the downhole tool connected to the same information transmission channel, characterized in that, in order to improve the reliability of the measured parameters of the useful waves by eliminating wave pattern distortions caused by the wave on the body, the device is equipped with a matching unit, a device the time delay, the phase-amplitude conversion unit and the subtraction circuit, the wave receiver on the body is made in the form of a displacement velocity receiver having amplitude-frequency characteristic The characteristics are the same as for the pressure receiver, uniform in the spectrum of the acoustic signal, both receivers are located axisymmetrically with the casing of the downhole tool at one end of it, the displacement velocity receiver is rigidly fixed to the casing so that $ 17 the symmetry of its directional diagram and the downhole tool coincide, bb) the input of the displacement velocity receiver is connected to the input of the matching unit, the output of the KOTopoi-o is connected to the input of the time delay device, and its output is connected to one of the inputs of the subtraction circuit, to the other input of which is connected the output of the pressure receiver, the output of the subtraction circuit is connected to the input of the information transmission channel. 2