SU404033A1 - ACCESSORIES FOR ACOUSTIC TANNING - Google Patents

Description

I

The invention relates to well field geophysical well testing by acoustic methods.

A known apparatus that solves similar problems and consists of a borehole projectile containing an acoustic probe, an amplifier and an excitation circuit, and a ground device comprising a clock pulse selector, a synchronization unit, an amplitude meter and an analog interval time meter.

However, in the known apparatus, the interval time meter is made according to a single cycle scheme with a storage capacitor, which determines its substantial inertia and the associated dynamic error in measuring the interval time during the movement of the siad in the well.

The aim of the invention is to reduce the dynamic, inaccurate measurement of time when a projectile moves in a well.

For this purpose, the interval time meter is made according to a push-pull circuit with alternating reset, using controlled parametric current stabilizers as the reset keys to ensure the equality of the measured time and the reset time.

The invention is illustrated in the drawings.

FIG. I shows a block diagram of an anapture; in fig. 2 is a block diagram of an interval time meter; in fig. 3 - voltage plots on the elements of the interval time meter.

The apparatus consists of a downhole projectile and a surface device (Fig. I).

In the borehole de located. an acoustic probe consisting of emitter I and receiver 2. Emitter I is connected to the excitation circuit 3, and the receiver is connected to amplifier 4. The ground device has a clock pulse selector 5, synchronization unit 6, amplitude meter 7 and analog time meter 8 During operation, the wellhead and the surface device are connected by a carotid cable.

The interval time meter contains a trigger-divider 9 and two symmetric channels, each of which has a reset key 10, AND, a storage capacitor 12, 13, and a key stabilizer of charging current 14, 15, 16 — common output, 17 measurement input.

In the wellbore, the excitation circuit 3 (Fig. I) periodically starts the emitter, which, at the start of each excitation, generates into the environment a series of un-oscillations. The latter, after passing through the elements of the medium, enter the receiver 2. Receiver 2 transforms electrical oscillations in-oscillations, which, together with the mixed clock pulse corresponding to the excitation moment, flow through the logging cable to the input of the surface device. In a surface device, a borehole signal is fed to an amplitude meter 7 and a clock pulse selector 5. In the latter, a clock pulse is extracted from the signal that arrives at the input of the ground device. The selected clock pulse 18 (Fig. 3) is fed to the synchronization unit 6. In the synchronization unit 6, signals defining the working interval of the amplitude meter and rectangular pulses 19 are generated, the beginning and end of which are associated with the moment of arrival of the clock pulse and the moment the arrival of the measured signal. the duration of this pulse, T, is equal to the transit time of the acoustic signal from the radiator to the receiver. Pulses of duration T are fed to the measuring input 17 (Fig. 2) of the analog interval time meter 8. At the time of supplying the measuring input 17 of the pulse 19, the charging current stabilizers 14 and 15 turn on and during the time T the storage capacitors 12 and 13 are supplied by charging current, and that of accumulative capacitors 12 or 13 is charged, the reset key of which W or I is in the open state. Due to the constancy of the charge current, the voltage on the storage capacitor increases to a value of f / c max. proportional to the charging time T. The storage capacitor of the second channel is discharged, since its reset key is closed at this time. During the next clock cycle, the channel functions are reversed. The alternating closure of reset keys in each of the channels is provided by trigger splitter 9, applying a voltage of opposite sign (20 and 21) to each of the keys (Fig. 3), and the cycle of operation of the trigger splitter Hz corresponds in time to two clock cycles Gt of operation of the radiator. The flip-flop of the trigger-divider is performed at the moment of arrival of the clock pulse 18. A key is used as a reset key. Its mode is chosen such that: to a collector it depends little on the collector voltage (parametric tabilization mode). As a result, a cumulative condensate discharge is provided, and the discharge time is equal to the charging time and, consequently, to the measured time T. at the discharge - charge. Thus, the voltage pulses 22 and 3 on each of the storage capacitors have the form of an equilateral trapezium. , and the shift between the pulses on the storage capacitors of different channels is equal to half the cycle duration (180 °). The impulse voltage of the storage capacitors can be decomposed into constant f / nocT and variable f / nep components. At the common output 16, the constant components add up, and the variable components (pulsations) due to their shift by 180 ° and equality in amplitude are mutually compensated, i.e. lane 1 -} - ler.2 0. Thus, by using a two-stroke interval time meter with alternating reset provides the output parameter in the form of a constant voltage (current 24), which does not have pulsations and does not possess inertia, which reduces the measurement error of the temporal parameter associated with the dynamic state of the well Nogo projectile, ie. with its movement in the borehole and to change the moving speed during logging. Subject of the Invention Acoustic well logging equipment consisting of a wellbore containing an acoustic probe, an amplifier and an excitation circuit, and a surface device comprising a clock and pulse selector, a block of synchronization, an amplitude meter and an analog interval time meter, characterized by By the fact that, in order to reduce the dynamic measurement error of the time when the projectile moves in the well, the interval time meter is made according to a push-pull circuit with alternating reset, as the key whose reset which used controlled parametric current stabilizers, ensuring the equality of the measured time and time reset.

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