SU1130819A1 - Device for magnetic well-logging - Google Patents

Abstract

A device for magnetic logging, containing a wellbore, consisting of an inductive sensor and a clamping electromagnet and connected via a logging cable to the surface unit of the transducer and recording the signal containing the circuit. control of the clamping electromagnet, connected through a wireline cable with a clamping electromagnet, measured. low-frequency auto-oscillator, whose output is connected to the first input of the indicator and to the first input of the mixer, a reference auto-generator, whose output is connected to the second inputs of the indicator and mixer, the third input of the latter is connected to the output of the meter footage, and the output through a bipolar, switch to the magnetic storage input device, also connected via an input via another pole of a two-pole switch with an encoder output, and along an output - with an input of a magnetic reproducing device included in in the signal processing unit, which also contains the first low-pass filter, the modulator and the second low-pass filter connected in series between the first; magnetic sensor and the recording input of the frequency converter — code, as well as the narrowband filter and the first pulse detector connected in series between the output of the magnetic transponder and the input of the converter of the frequency converter - a code whose output is connected to the input of the computing unit, characterized in that, in order to increase its sensitivity, the signal conversion and registration unit contains a second amplitude detector, a third low-pass filter, a frequency detector and a quality factor multiplier, containing negative, inductance with a control input, and a capacitor, feedback resistor with input, a nonlinear element and an auto-bias circuit, at 90 this the inductance is negative and the capacitor is connected to each other and via a logging cable with an inductive sensor A to form an oscillating circuit of the measuring a A generator whose output is connected to the control input of a negative inductance through a second amplitude detector, and the nonlinear element is connected via an auto-bias circuit to the body and connected in series with a feedback resistor, forming a circuit connected to the capacitive circuit, with a feedback resistor zi is shunted by an attenuator, and his

Description

The control input is connected to the mixer via a low-pass filter and a frequency detector.

The invention relates to geophysics, in particular to magnetic measurements in wells, and is intended for the logging of deposits of ores of ferrous metals and other minerals.

A logging device is known that contains a surface part and a borehole connected by a logging cable. The ground part contains an oscillator with an oscillating circuit, the inductance of which is connected to the feedback circuit of the oscillator. The inductance sensor of the downhole oscillator is included in the oscillator circuit of the terrestrial oscillator.

The disadvantage of this device is the low sensitivity and difficulty of signal processing due to the use of a dial gauge.

. The closest to the technical essence of the invention is a downhole logging device comprising a borehole projectile consisting of an inductive sensor and a clamping electromagnet and connected via a logging cable to a surface conversion and recording unit, containing a control clamping electromagnet connected through a logging cable with a pinch solenoid, measuring low-frequency oscillator, the output of which is connected to the first input of the indicator and to the first input mix , the reference oscillator, the output of which is connected to the second inputs of the indicator and mixer, the third input of which is connected to the output of the meter footage, and the output through a two-pole switch is connected to the input of a magnetic storage device, also connected to the input via another pole of the two-pole switch with the output of the encoder, and output - with the input of a magnetic reproducing device, which is part of the signal processing unit, which also contains

the first low-pass filter, the modulator and the second low-pass filter, connected in series between the output of the magnetic reproducing device and the write input of the transform. the frequency clock — a code, as well as a narrow filter and a first amplitude detector connected in series between the output of the magnetic reproducing device and the frequency converter input — the code whose output is connected to the input of the computing unit 23.

A disadvantage of the known device is the low sensitivity due to the low frequency overlap of the low-frequency oscillating circuit.

The purpose of the invention is sensitivity.

This goal is achieved by the fact that in a magnetic logging device containing a borehole projectile consisting of an inductive sensor and a pressure electromagnet and connected via a logging cable to a surface conversion unit and recording a signal containing a control circuit of a clamping electromagnet connected via a logging cable: spruce with a clamping electromagnet, measuring low-frequency auto-oscillator, the output of which is connected to the first input of the indicator and the first input of the mixer, the reference auto-oscillator you the stroke of which is connected to the second inputs of the indicator and the mixer, the third input of the latter is connected to the output of the meter footage, and the output via a bipolar switch to the input of a magnetic storage device, also connected at the input via another pole of the bipolar switch with the encoder output, and at the output to the input a magnetic reproducing device, part of the signal processing unit, which also contains the first low-pass filter, the modulator and the second low-pass filter, connected in series between the output of the magnetic reproducing device and the recording input of the frequency converter — the code as well as the narrow-band filter and the first amplitude detector connected in series with the output of the magnetic reproducing device and the frequency converter input — the code whose output is connected to the input of the computing unit, the conversion unit and signal acquisition contains a second amplitude detector, a third low-pass filter, a frequency detector, and a smart Q-factor, containing a negative inductive control capacitor; feedback resistor to control input; attenuator; nonlinear element and auto-bias circuit; in this case, negative inductance and capacitor are connected to each other and through a logging cable with an inductive sensor, forming the oscillatory circuit of the measuring auto-oscillator, the output of which is connected to the control input of the negative inductance through the second amplitude detector, and the non-linear element is connected via an auto-bias circuit to the housing and connected in series with a resistor m feedback to form a circuit connected to the oscillation circuit, wherein the feedback resistor is shunted by the attenuator, while its control input connected to the output of the mixer through a third low-pass filter and the frequency detector.

The drawing shows a block diagram of the device.

The device comprises a wellbore I, a surface signal conversion and recording unit 2 and a signal processing unit 3. The borehole hole 1 consists of an inductive sensor 4 and a pressure electromagnet 5, connected to the output of the well screen and through the logging cable 6 to the ground conversion and recording unit 2, which contains the electromagnet control circuit 7, the reference oscillator 8 with frequency b ) measuring oscillator 9 with frequency tJ indicator 10, mixer And, meter 12 meter, bipolar

switch 13, encoder 14, second amplitude detector 15, third low-pass filter 16., frequency detector 17, good quality multiplier 18 that contains a co-loop circuit 19 formed from a controlled negative inductance 20, a capacitor 21 and an inductive sensor 4, a controlled resistor 22 connection, shunted by an attenuator 23, a nonlinear element 24, an auto-bias circuit 25, a magnetic storage device 26. The processing unit signal 3 contains a magnetic recording device 27, the first low-pass filter 28, the modulator 29, the second low-pass filter 30, the narrow-band filter 31, the second amplitude detector 32, the frequency converter - code 33 and the computing unit 34.

The device for magnetic logging works as follows.

Before starting the measurements, inductive sensor 4 is located outside the well. Using the indicator 10 set the zero device by adjusting the frequency of the measuring oscillator 9 to the frequency of the reference oscillator 8, the frequency of which is stabilized. Using an attenuator 23, set the required value of the quality factor of the measuring oscillator 9, switch on the magnetic storage device 26 for a few seconds, record the zero readings of the device. Set the bipolar switch 13 in a position in which the input of the magnetic storage device 26 is connected to the encoder 14, which fixes the code of the well being carted. Then, the bipolar switch 13 returns to its original position. For logging, downhole tools 1 are lowered onto the logging cable 6 to the bottom of the well, turn on a pressure electromagnet 5 using an electromagnet control circuit 7, turn on a cable winding device and magnetic memory 26, and record. the signals of the reference and measuring oscillators 8 and 9. At the same time, the signals of the marker 12 meters representing the generator, ;; and for a short time (up to 100 ms are switched on every meter depth of the well using the contact block of the cable winding device. At the same time, the oscillation frequency of the marker 12 is selected higher than the frequency of the reference oscillator 8. Signals from the reference and measuring oscillators 8 and 9 and the meter 12 are fed to the magnetic input of the device 26 through the mixer 11. Lrn motion in The length of the borehole axis after the inductive sensor interacts with the ore formations intersected by the borehole, and its inductance depends on the magnetic and electrical properties of the rocks.Controlled negative inductance 20, connected in series with the inductive sensor 4, increases the frequency overlap ratio of the measuring oscillator 9, then device sensitivity. Multiplier 18 with a controlled resistor 22 feedback increases the quality factor of the oscillatory measurement system in generator 9, which contributes to an increase in the sensitivity of the device with a significant amount of electrical conductivity of rocks. Cross-feedbacks from the output of the measuring oscillator 9 through the second amplitude detector 15 to the control input of a controlled negative inductance 20 and from the third low-frequency output (r 16 through the frequency detector I7 to the control input of a controlled Q feedback feedback resistor 22 increases the sensitivity of the device , reducing the error due to the mutual magnetic and electrically conductive properties of rocks. The oscillation frequency of the measuring oscillator 9 is changed under the influence of The inductance and inductive sensor, - The frequency of the count of the reference oscillator 8 remains unchanged. After the wellbore 1 comes out of the wellhead, the device is turned on, thus accumulating a record of the logging results of a series of wells (for example, logging results 40 wells, start in the laboratory conditions for signal processing. The signal processing unit 3 has two channels: a channel for recording a useful signal and an event marker channel. The signal of the meter 12 meter from the magnetic recorder 27 is fed to the narrow-band filter 31, tuned to the frequency)) (r meter meter 12). Simultaneously recorded from the measuring and reference oscillators 9 and 8, the signals arrive at the modulator 29 through the first low-pass filter 28. Since the cJoi frequency is selected above the frequency of the onopHOio of the auto-oscillator 8, the signal with the JOM frequency is not passed by the first low-pass filter 28 to the input of the modulator 29. In the modulator 29, the current has a constant component CA. and 0) 2, their second harmonics 2 cj, 1 2 o) and two side frequencies: lower () and upper (cjj, -f + j} i). When the frequencies of the measuring and reference autogenerators 9 and 8 are equal in the oscillation spectrum, the side components are absent, and the voltage at the output of the second low-pass filter 30 is zero. In the process of measurements, under the action of positive increments of inductance of inductive sensor 4, the oscillation frequency cj of the measuring oscillator 9 decreases, deviating from the frequency (x) of the reference oscillator 8. The frequency increment causes the appearance in the spectrum of the modulated oscillation of the lateral components from which the bottom containing the difference is used (x) j -cJ), When voltage tj and cJj are recorded during the measurement process, the unevenness of the speed of the magnetic tape in the memory device (detonation phenomenon) in the same m It affects both vibrations. At the same time, the frequency difference (remains unchanged when the magnetic tape speed fluctuates. The overlap coefficient for the resonance frequency in LC circuits is expressed by the formula 1 gdes, Oc is the resonant frequency at Cp (d1); 3 the overlap frequency coefficient; the initial inductance value; inductance under the influence of the environment.

With successive switching on, the negative inductance contour L coefficient 4 "overlap frequency is determined by the formula

177

THAH iH

toCLHiuL)} - (2)

where 6L is the resonant frequency of the circuit with negative inductance.

From (2) it follows that when L - L d1,, t, e. Obviously, when, there is a negative inductance in the circuit with equal effects of the magnetic medium, the change in the resonant frequency increases. An increase in the coefficient of overlap in frequency is explained by a decrease in the initial value of the loop inductance at. inclusion in the circuit of negative inductance. The quality factor multiplier 18, which compensates for the effect of the electrical conductivity of the controlled medium, operates in a stable mode, since the selectivity requirements are limited to an effective quality factor on the order of 50 to 00, which allows measuring the electrical conductivity with an amplitude detector

medium to reduce, correlation links between the reactive and active parts of the contour to be introduced into the contour, isolate the signal, proportional magnetic properties

environment.

The invention increases the sensitivity of magnetic logging. Thank you. an increase in the range of the overlapped frequency of the resonance of the oscillating circuit, which makes it possible to increase the resonance frequency from the HFfe at equal effects of the magnetic medium.

Claims (1)

A MAGNETIC LOGGING DEVICE comprising a downhole projectile consisting of an inductive sensor and a clamping electromagnet and connected via a wireline cable to a ground-based signal conversion and recording unit containing a clamping electromagnet control circuit connected through a logging cable to a clamping electromagnet, a measuring low-frequency oscillator, the output of which connected to the first input of the indicator and to the first input of the mixer, a reference oscillator, the output of which is connected to the second inputs and indicator and mixer, the third input of the latter is connected to the meter indicator output, and the output is through a two-pole meter, the switch is connected to the input of the magnetic storage device, also connected through the input through the other pole of the two-pole switch to the encoder output, and by the output of the magnetic reproducing device input a signal processing unit also comprising a first low-pass filter, a modulator and a second low-pass filter, connected in series between the outputs of the magnetic reproducing device frequency converter and the recording input of the frequency - code converter, as well as a narrow-band filter and the first amplitude detector, connected in series between the output of the magnetic reproducing device and the input of the frequency converter marker - the code, the output of which is connected to the input of the computing unit, which differs in that in order to increase its sensitivity, the block transform | Signal acquisition and registration contains a second amplitude detector, a third L · ·· low-pass filter, a frequency detector .J *** · Q-factor detector and multiplier, containing a negative inductance with a control input, and a capacitor, a feedback resistor with a control input, an attenuator, a nonlinear element and an auto bias circuit, while the negative inductance and capacitor are interconnected and through a wireline cable with an inductive ζφ sensor, forming an oscillatory circuit of the measuring oscillator, the output of which is connected the negative inductance is controlled by the second amplitude detector, and the nonlinear element is connected through the autodisplacement circuit to the housing and connected in series with the feedback resistor, forming a circuit connected to the oscillation circuit, while the feedback resistor is shunted by the attenuator, and its control input is connected to . mixer output through a low-pass filter and a frequency detector.