SU744415A1 - Apparatus for electromagnetic well logging - Google Patents

Description

one

The invention relates to the field of field geophysics and can be used in the study of wells using electromagnetic logging methods.

Device 1 is known, comprising a generator part, a probe with a generator and two receiving coils, a receiving part, including two identical amplification channels, amplitude limiters, a phase-measuring unit and a recorder. The device is intended to measure the phase difference between the signals in the receiving coils.

The closest technical solution to the invention is a device for electromagnetic well logging, containing, its generator part with an oscillator controlled oscillator, an oscillator with generator and two receiving coils, and a measuring part including two identical silytels, an amplitude limiter, phase-measuring unit, amplitude detector, tele-measuring system and recorder 2.

The phase difference Df, measured by such devices, generally depends on both the dielectric constant e and the resistivity of the rocks, i.e. these devices do not allow directly measuring e and to determine it, it is necessary to involve the measurement results other devices, which in general have different depths and different dependences of measurement results on others}.

The proposed device makes it possible to determine e and Y of rocks by measuring at one frequency and with the help of one

10 probes of various characteristics of an electromagnetic floor:

Y1 -AZ

D (I)

(P1),

(P),

and,

l

f (IV), (V),

15 (vi)

fi - fl.,

fllfl2

h, (VII), h, (VIII),

where hi and h are the signals in the first and second pickup wheels.

20

The aim of the invention is to increase the logging efficiency by simultaneously recording the phase difference of the signals in the pick-up coils, the ratio of the vector difference of these signals to the amplitude

25 one of them and the ratio of the amplitudes of these signals.

This goal is achieved by the fact that for registering relations (II) and (IV) or (III) and (V) the radiation power of a generator is 30

pa is recorded so that the amplitude of the signal in one of the receiving coils / or ftg remains constant, and the geometric part of the device of the outputs of identical amplifiers is entered into the measurement part of the device, and the output amplitude of one of the ideals is not constant, connected via a telemetering system with a recorder. In this case, the output signal of the adder will characterize the ratio (II) (at a constant value of hi) or the ratio (III) (at a constant hz). At the same time, the output of an identical amplifier, whose amplitude does not remain constant, will characterize the ratio (IV) or (V).

To control the generator's radiation power, a signal is used to exceed the signal from one of the identical amplifiers above the reference level. Under the condition of a constant with a given accuracy of the signal amplitude in this amplifier, the excess signal will have a small magnitude, which allows it to be amplified many times, and that, in turn, makes it possible to more accurately maintain a constant signal amplitude in this identical amplifier. Extraction is performed in a special unit, for example, by subtracting from the signal an identical amplifier in-phase with it stabilized reference voltage. The amplified and rectifying overshoot signal is used as a control for the generator.

To register the phase difference (I), the vector difference of the amplitudes (VI) and the magnitudes of the amplitudes (VII) and (VIII), the generator's automatic power control circuit is broken with an additional switch. In this case, the signals supplied to the recorder from the outputs of the phase-measuring unit, the additional vector adder and identical amplifiers will be characterized respectively: phase difference AF, difference hi- / i2, fti and / i2.

The drawing shows a block diagram of the proposed device.

The device consists of a generator 1, a probe 2 and a measuring part 3. The generator 1 includes a master oscillator 4, a stage 5 with a controlled amplitude of the output signal and an output device 5.

The probe consists of a generator coil 7, loading the generator, and the receiving coils 8 and 9. i

Measuring device 3 contains two identical amplifiers 10 and I, amplitude limiters 12 and 13, phase metering unit 14, vector adder 15, switch 16, boost and amplify signal amplification block 17, amplitude detector 18, switch control device 19, telemetering system 20 and recorder 21.

The device works as follows.

The generator 1 feeds the geyerator coil 7 with high frequency current. The high-frequency magnetic field created in the surrounding region induces in receivers

0 coils 8 and 9, the signals that come out to the outputs of amplifiers 10 and 11. The outputs of amplifiers 10 and 11 are connected via phase-limiters 12 and 13 to phase-measuring unit 14, where a signal is extracted,

5 proportional Der.

The output signal from the amplifier 11 through the switch 16 enters the block 17 for extracting and amplifying the signal, and the amplification of the output nanowire of the amplifier 11 over

0 given level. The excess signal is detected by the detector 18 and is applied to the controlled cascade 5 of the generator 1 as the shearing voltage. With sufficient gain of the block 17

5, the cranking voltage will change the amplitude of the output device 6 in such a way that, with 1 hi or h in the iriem coil 8 or 9, it will remain stable with a given accuracy.

0 The second outputs of amplifiers 10 and 11 are connected to the vector adder 15, the output of which is the iron equivalent of the vector difference (hi- / r2). The outputs of identical amplifiers 10 and 11, the output of the adder

5 15 and the output of the phase-measuring unit 14 through the telemeasuring system 20 are connected with the recorder 21. If the mode of automatic control of the radiation power of the geyrator 1 is selected so that

the output voltage ft of the amplifier 10 remains always constant, then the output voltage of the adder 15 is equal to -hz

-, and the output is nano relation

BUT,

power amplifier 10 is otooshennyu--

In this case, the registrar will register at the same time Af, - and

For simultaneously registering af,

- and - control required

voltage for generator 1 of signals from amplifier 10. In this case, H2 is const. If, on command from the control unit 19, using switch 16, disconnect the voltage circuit that is oscillating with the radiation power of generator 1, then the recorder will simultaneously detect the diagrams AF, (/ ii- / 12), AI and / i2.

Claims (2)

1. USSR author's certificate number 212387, cl. G 01 3/18, 1968. 2. USSR author's certificate number 427302, cl. G 01 3/18, 1974 (prototype).