SU1287073A1 - Multichannel mining-geophysical device - Google Patents

Abstract

The invention relates to the field of geophysics and can be used to obtain a complex of field geophysical data in the study of oil and gas wells. The aim of the invention is to improve the accuracy of measuring the complex of geophysical parameters. To do this, a phase-sensitive detector is introduced into the device in the open circuit between the frequency detector and the input of the demultiplexer, the control input of which is connected to the synchronization unit. A digital logic circuit of a reversible counter, the counting output of which is connected to the output of the amplifier S s /), is used as a carrier frequency and phase-sensitive detector.

Description

one

The invention relates to geophysics and can be used to obtain a complex of word-geophysical data in the study of oil and gas wells.

The purpose of the invention is to increase the accuracy of measuring the complex of geophysical parameters in the well.

The drawing shows a functional diagram of a multichannel industrial geophysical device.

The device contains single-core armored logging cable 1, current 2 and measuring 3-8 electrodes of electric logging probe, input matching transformers 9-11, electronic switch 12, frequency modulator 13, power amplifier 14, shunt 15, synchronization circuit 16, separation filter 17, a ground oscillator 18, a filter 19, a limiting amplifier 20, a reversible counter 21, a synchronization unit 22, and a channel memory device 23.

For the sake of simplicity, only three channel circuits in the downhole tool are shown, since the nodes of the other channels are identical.

When the device is turned on, the alternating current with frequency F from the surface generator 18 flows through the central core of the armored logging cable 1 into the downhole part of the device where it passes through the separating filter 17 and the shunt 15 into the current circuit 2 of the electrical logging probe, creating in the surrounding rocks. electric field. Information signals of the AMP type from the measuring electrodes 3-8 are driven by matching transformers 9-11 to the required level and fed to the inputs of the electronic switch 12, which alternately connects them to the input of the frequency modulator 13. Synchronization circuit 16 provides synchronous and in-phase switching switch 12. For this include

five

0

five

0

five

0

five

By means of its inputs to the power supply circuit of the probe (via shunt 15), circuit 16 generates selector switching pulses of switch 12 each in control inputs, each of which indicates that the first channel is turned on through power amplifier 14 to link 1. Structurally, the synchronization circuit 16 can be performed on the basis of a digital scheme of the shift register, binary, counter with decoder, multiphase multivibrator, etc. The sequence of information signals from the output of the switch 12 controls the oscillation frequency of the private modulator 13, the output of which through the power amplifier 14 and the separation filter 17 is fed through the logging cable 1 to the surface part of the device. The carrier selected here from the video signal by the filter 19 is amplified by the amplifier-limiter 20 and its further conversions are performed in digital form by a reversible counter 21. The synchronization unit 22 controlling the synchronization pulses (pulses corresponding to the switching points of the first channel) downhole switch 12) and taking into account the frequency of the generator 18 generates a reset pulse of the counter 21 (at the beginning of each period), the switching pulses of the counting direction of the counter 21 with a frequency F and a duty cycle of -2, and also selectable channel switching pulses for the channel memory node 23. The synchronization unit 22 can be performed similarly to the synchronization scheme 16, but additionally contains the circuits of the initial installation using a clock pulse in the position corresponding to the first channel. Structurally, the channel memory node can be made on the basis of binary random access memory (RAM) circuits. With the arrival at the entrance of the R counter

.21 resetting pulse. From this moment and during .1 / 2 T at the control input ± a logical level is set, which corresponds to the counter operation in the mode of pulse carrier frequency generation. During the next 1/2 T, the signal at the input: de + changes and the counter is switched to the subtraction mode of the carrier frequency pulses. As a result, at the end of each period, the digital output of the counter 21 generates the binary equivalent of the mean value of the deviation of the carrier frequency for the period related to a particular channel. Since the change in counting direction is phased with the probe supply current, when the counter 21 is operating, the reactive component of the ACp signal is suppressed. The process ends with overwriting the measured number at the output of the counter 21 into the corresponding cell of the channel memory device 23. Further, from the signals from the synchronization unit 22, the counter 21 is zeroed again and the digital reception of the FM data related to the next channel begins. Information on all channels stored in the channel memory 23 can be output to a digital recorder, computer, etc.

The exclusion from the multichannel geographical-geographical equipment of the analog frequency-carrier detecting and phase-sensitive AMP signal generation circuits increases the measurement accuracy of apparent electrical resistivities. This effect has been achieved without the complication of the downhole part of the equipment operating in severe thermobaric conditions.

fO

0

 -5 5 0

0

The invention can be tested in devices that use individual channel frequency modulators in the well part with alternate switching of outputs to the power amplifier, as well as devices for other logging methods, if they use the AM-data conversion principle.

Claims (1)

Invention Formula A multichannel field-geophysical device containing a well block, including electrical logging probes, input transformers, channel switch, sequentially connected frequency modulator and power amplifier, synchronization circuit, as well as single core armored logging cable and surface block, containing a series-connected oscillator, a filter and an amplifier-limiter, as well as a synchronization unit and a memory device, the synchronization unit, the filter and the generator being connected to the car with a cable that, in order to improve the accuracy of measurement of the complex of geophysical parameters, additionally contains a digital reversible counter, the counting input of which is connected to the output of the amplifier-limiter, the control input and the pre-installation input of which are associated with sync block outputs as well. the digital output of the reversible counter is connected to the information input of the channel memory device.