Reference signal extraction device and method for azimuth electromagnetic wave resistivity instrument while drilling

Abstract

The invention discloses a while-drilling azimuth electromagnetic wave resistivity instrument reference signal extraction device and method, and the device comprises a current sampling transformer, a pre-amplification circuit, a multiplication mixer, a filter circuit, a program control amplification circuit, a differential drive circuit, an analog-to-digital conversion circuit and a controller DSP which are electrically connected together in sequence. The output of the transmitter resonance circuit is connected to the primary of the current sampling transformer, the secondary of the current sampling transformer is electrically connected with the sampling resistor, and the pre-amplification circuit extracts a reference signal from the sampling resistor, carries out fixed gain amplification and then sends the reference signal to the multiplication mixer. According to the device and the method disclosed by the invention, the instrument power consumption and the reference signal extraction noise are reduced, the amplitude of the reference signal and the phase measurement precision are improved, and the application range is wider.

Description

Technical Field

[0001] The present invention belongs to the field of oil and coal exploration, and particularly relates to a reference signal extraction device and method for a small-diameter azimuth electromagnetic wave resistivity logging-while-drilling tool in this field. Background Art

[0002] Logging-while-drilling technology installs measurement instruments near the drill bit to measure the petrophysical parameters (resistivity, dielectric constant, lithology, porosity, etc.) of the surrounding formation in real time during drilling. Azimuth electromagnetic wave resistivity logging-while-drilling is one of the key technologies of logging-while-drilling, which realizes the detection of formation resistivity parameters and the judgment of formation interface positions during drilling. Its principle is based on the propagation effect of electromagnetic waves in the medium. Due to the differences in the influence of formations with different resistivities on the propagation speed of electromagnetic waves and the influence of formation interfaces on electromagnetic waves, by measuring the amplitude ratio (attenuation) and phase difference (lag) of electromagnetic waves between at least a pair of receiving coils and the phase difference and amplitude ratio of at least one receiving antenna in different azimuths, the measurement of formation resistivity and the judgment of formation interface positions are realized. This method avoids the influence of mud invasion on measurement parameters, improves the accuracy of logging data, and effectively improves the logging operation efficiency at the same time, and has become the mainstream trend of resistivity logging in the future.

[0003] Traditional electromagnetic wave resistivity logging-while-drilling tools use a high-precision sampling resistor method to extract reference signals. The disadvantage is that due to the large transmitter power, it will bring a large amount of noise to the extraction and subsequent processing circuits of the reference signals, reducing the signal-to-noise ratio of the reference signals while increasing the power consumption of the tool, affecting the measurement range and accuracy of the phase resistivity and amplitude resistivity of far and near signals. Therefore, there is an urgent need for a reference signal extraction device and method for an azimuth electromagnetic wave resistivity logging-while-drilling tool. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a reference signal extraction device and method for an azimuth electromagnetic wave resistivity logging-while-drilling tool.

[0005] The present invention adopts the following technical solutions:

[0006] A device for extracting reference signals of a borehole azimuth electromagnetic resistivity instrument while drilling, the improvement being: comprising a current sampling transformer, a preamplifier circuit, a multiplication mixer, a filter circuit, a programmable gain amplifier circuit, a differential driver circuit, an analog-to-digital conversion circuit and a controller DSP, which are electrically connected in sequence; the output of the transmitter resonant circuit is connected to the primary of the current sampling transformer, the secondary of the current sampling transformer is electrically connected to a sampling resistor, the preamplifier circuit extracts a reference signal from the sampling resistor and performs fixed-gain amplification and then sends it to the multiplication mixer, the multiplication mixer mixes the input signal of the preamplifier circuit and the local oscillator signal to generate a sum frequency signal and a difference frequency signal, the filter circuit filters the output signal of the multiplication mixer, the programmable gain amplifier circuit amplifies the filtered signal, and finally the amplified signal is output through the differential driver circuit, and the analog-to-digital conversion circuit, under the control of the controller DSP, performs digital conversion on the output signal that meets the requirements by means of low-frequency sampling.

[0007] Further, in the current sampling transformer and the preamplifier circuit, the first pin of chip 2N1 is the signal output pin, connected to one end of resistor 2R3, the second pin of chip 2N1 is connected to one end of resistor 2R2 and one end of resistor 2R3, the third pin of chip 2N1 is connected to one end of resistor 2R4 and one end of resistor 2R5, the fourth pin of chip 2N1 is connected to the negative end of polar capacitor 2C3, one end of capacitor 2C4 and the third pin of three-terminal filter 2L2, the fifth, sixth, seventh, eighth and ninth pins of chip 2N1 are left floating, the tenth pin of chip 2N1 is connected to the positive end of polar capacitor 2C1, one end of capacitor 2C2 and the third pin of three-terminal filter 2L1, the first pin of three-terminal filter 2L1 is externally connected to the +5V power supply, the second pin of three-terminal filter 2L1 is connected to the analog ground AGND, the first pin of three-terminal filter 2L2 is externally connected to the -5V power supply, the second pin of three-terminal filter 2L2 is connected to the analog ground AGND, the first pin of transformer T1 is connected to the differential negative polarity signal, the second pin of transformer T1 is connected to the differential positive polarity signal, the third pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R2, the fourth pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R4, the negative end of polar capacitor 2C1, one end of capacitor 2C2, the positive end of polar capacitor 2C3, one end of capacitor 2C4 and one end of resistor 2R5 are connected to the analog ground AGND.

[0008] Further, in the multiplication mixer circuit, the first pin of chip 3N1 is the signal input pin, connected to one end of resistor 3R8 and one end of resistor 3R10; the second pin of chip 3N1 is connected to one end of resistor 3R4; the third pin of chip 3N1 is connected to one end of resistor 3R4; the fourth pin of chip 3N1 is connected to one end of resistor 3R9 and one end of resistor 3R11; the fifth pin of chip 3N1 is connected to one end of resistor 3R12; the sixth pin of chip 3N1 is connected to one end of resistor 3R6 and one end of capacitor 3C10; the seventh pin of chip 3N1 is connected to one end of resistor 3R3; the eighth pin of chip 3N1 is connected to one end of resistor 3R2 and one end of capacitor 3C5; the ninth pin of chip 3N1 is connected to one end of resistor 3R7 and one end of capacitor 3C9; the tenth pin of chip 3N1 is connected to one end of resistor 3R8, one end of resistor 3R9, the negative end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, and the third pin of three-terminal filter 3L2. The first pin of three-terminal filter 3L1 is externally connected to the +5V power supply; the second pin of three-terminal filter 3L1 is connected to analog ground AGND; the third pin of three-terminal filter 3L1 is connected to the positive end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C4, one end of resistor 3R5, one end of resistor 3R6, and one end of resistor 3R7. The first pin of three-terminal filter 3L2 is externally connected to the -5V power supply; the second pin of three-terminal filter 3L2 is connected to analog ground AGND. The negative end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C3, one end of capacitor 3C4, the positive end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, one end of resistor 3R1, one end of resistor 3R10, one end of resistor 3R11, one end of resistor 3R12, and one end of resistor 3R13 are connected to analog ground AGND. One end of capacitor 3C5 is externally connected to the local oscillator signal FL; one end of capacitor 3C9 is connected to one end of resistor 3R13; one end of capacitor 3C10 is connected to the output signal.

[0009] Further, in the filter circuit, the first pin of chip 4N1 is the signal output pin and is connected to the second pin of chip 4N1. The third pin of chip 4N1 is connected to one end of resistor 4R1, one end of resistor 4R4, and one end of capacitor 4C3, and is also connected to the seventh pin of chip 4N1. The fourth pin of chip 4N1 is externally connected to the +5V power supply and one end of inductor 4L2. The fifth pin of chip 4N1 is connected to one end of resistor 4R4 and one end of resistor 4R5. The sixth pin of chip 4N1 is connected to one end of resistor 4R3 and one end of capacitor 4C4. The eighth, ninth, and tenth pins of chip 4N1 are left floating. The eleventh pin of chip 4N1 is externally connected to the -5V power supply and one end of inductor 4L3. The twelfth pin of chip 4N1 is externally connected to the input signal. The thirteenth pin of chip 4N1 is connected to one end of resistor 4R2 and is also connected to the fourteenth pin of chip 4N1. One end of inductor 4L1 is connected to the analog ground AGND and the other end is connected to the digital ground DGND. One end of inductor 4L2 is connected to one end of capacitor 4C1 and the positive terminal of polarized capacitor 4C2. One end of inductor 4L3 is connected to one end of capacitor 4C5 and the positive terminal of polarized capacitor 4C6. One end of capacitor 4C1, the negative terminal of polarized capacitor 4C2, one end of capacitor 4C4, one end of resistor 4R5, one end of capacitor 4C5, and the negative terminal of polarized capacitor 4C6 are connected to the analog ground AGND. One end of resistor 4R1 is connected to the digital ground DGND.

[0010] Further, in the programmable gain amplifier circuit, the first pin of chip 5N1 is connected to one end of resistor 5R3, one end of capacitor 5C1, the digital ground DGND, and the tenth pin of chip 5N1. The second pin of chip 5N1 is connected to one end of resistor 5R2 and one end of capacitor 5C2. The third pin of chip 5N1 is connected to one end of resistor 5R3 and one end of resistor 5R4. The fourth pin of chip 5N1 is externally connected to the +5V power supply. The fifth, sixth, and seventh pins of chip 5N1 are left floating. The eighth pin of chip 5N1 is the output signal pin and is connected to the ninth pin of chip 5N1. The eleventh pin of chip 5N1 is externally connected to the -5V power supply. The twelfth, thirteenth, and fourteenth pins of chip 5N1 are left floating. The first pin of chip 5N2 is connected to one end of resistor 5R1. The second pin of chip 5N2 is connected to the analog ground AGND. The third pin of chip 5N2 is connected to the input signal. The fourth pin of chip 5N2 is externally connected to the -5V power supply. The fifth pin of chip 5N2 is externally connected to the control signal G0. The sixth pin of chip 5N2 is externally connected to the control signal G1. The seventh pin of chip 5N2 is externally connected to the control signal G2. The eighth pin of chip 5N2 is externally connected to the +5V power supply. One end of resistor 5R4 and one end of capacitor 5C2 are connected to the analog ground AGND.

[0011] Further, in the differential drive circuit, the first pin of chip 6N1 is connected to one end of resistor 6R3 and resistor 6R4, the second pin of chip 6N1 is connected to analog ground AGND, the third pin of chip 6N1 is connected to the external +5V power supply, the positive end of polar capacitor 6C3 and one end of capacitor 6C4, the fourth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R4, the fifth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R1, the sixth pin of chip 6N1 is connected to the external -5V power supply, the negative end of polar capacitor 6C1 and one end of capacitor 6C2, the seventh pin of chip 6N1 is left floating, the eighth pin of chip 6N1 is connected to one end of resistor 6R1 and one end of resistor 6R2, the input signal is connected to one end of resistor 6R2, and the positive end of polar capacitor 6C1, one end of capacitor 6C2, the negative end of polar capacitor 6C3 and one end of capacitor 6C4 are connected to analog ground AGND.

[0012] A method for extracting a reference signal of a measurement-while-drilling azimuth electromagnetic wave resistivity instrument, using the above device, is characterized in that: a low-frequency sampling frequency fs is designed according to the frequency f0 after down-conversion of the measured high-frequency reference signal; the measured signal within the target signal period tx is sampled using the sampling frequency fs to obtain a discrete sequence x[k], where k is the k-th sampling point within the corresponding sampling time, and k is an integer between 0 and p - 1; fx is the frequency of the signal recovered after low-frequency sampling; the discrete sequence x[k] obtained by low-frequency sampling is transmitted to the controller DSP for subsequent storage and processing by the digital circuit.

[0013] Further, according to the low-frequency sampling frequency fs, the corresponding discrete Fourier coefficients are determined; A, f0, and Φ are respectively the amplitude, frequency, and phase of the measured signal. If it is sampled at the sampling frequency of fs, the discrete digital signal obtained is: A*sin(2*pi*n*f0 / fs + Φ); the collected discrete signal is multiplied by the corresponding discrete Fourier coefficients respectively to obtain the real part and the imaginary part of the measured signal; the amplitude A and phase Φ of the target signal are calculated using the real part and the imaginary part of the measured signal.

[0014] The beneficial effects of the present invention are:

[0015] The device and method disclosed by the present invention reduce the instrument power consumption and the reference signal extraction noise, improve the measurement accuracy of the amplitude and phase of the reference signal, and have a wider practical range. Description of the Drawings

[0016] Figure 1 is the block diagram of the device disclosed by the present invention;

[0017] Figure 2 is the schematic diagram of the current sampling transformer and the preamplifier circuit in the device disclosed by the present invention;

[0018] Figure 3It is a schematic diagram of the multiplication mixer circuit in the device disclosed by the present invention;

[0019] Figure 4 It is a schematic diagram of the filter circuit in the device disclosed by the present invention;

[0020] Figure 5 It is a schematic diagram of the programmable gain amplifier circuit in the device disclosed by the present invention;

[0021] Figure 6 It is a schematic diagram of the differential drive circuit in the device disclosed by the present invention. Specific embodiments

[0022] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] Embodiment 1. This embodiment discloses a reference signal extraction device for a logging-while-steering azimuth electromagnetic resistivity instrument, as Figure 1 shown, which includes a current sampling transformer, a preamplifier circuit, a multiplication mixer, a filter circuit, a programmable gain amplifier circuit, a differential drive circuit, an analog-to-digital conversion circuit, and a controller DSP that are electrically connected in sequence; the output of the transmitter resonant circuit is connected to the primary of the current sampling transformer, the secondary of the current sampling transformer is electrically connected to the sampling resistor, the preamplifier circuit extracts the reference signal from the sampling resistor and performs fixed-gain amplification and then sends it to the multiplication mixer. The multiplication mixer mixes the input signal of the preamplifier circuit and the local oscillator signal to generate a sum-frequency signal and a difference-frequency signal. The filter circuit filters the output signal of the multiplication mixer. The filter circuit includes two low-pass filters with different frequencies; the programmable gain amplifier circuit amplifies the filtered signal, and finally outputs the amplified signal through the differential drive circuit to improve the anti-interference ability. The analog-to-digital conversion circuit digitally converts the output signal that meets the requirements by means of low-frequency sampling under the control of the controller DSP.

[0024] The current sampling transformer adopts a high-frequency band design, has good amplitude-frequency characteristics and phase-frequency characteristics, can obtain high measurement accuracy within a wide range of amplitudes, frequencies, and phases, and suppresses the noise introduced by the transmitter.

[0025] The preamplifier circuit adopts an operational amplifier with low power consumption, low noise, high gain-bandwidth product (1500M), high dynamic range, and high precision, which improves the signal-to-noise ratio and measurement accuracy.

[0026] The multiplication mixer adopts a double-balanced modulator, with a frequency band range up to 100M. It is simpler and more stable than using discrete devices, and has the advantages of wide operating frequency band, good temperature stability, high operation accuracy, high speed, and low cost.

[0027] The programmable gain amplifier circuit is controlled by the controller DSP. By controlling the feedback resistors connected to the amplifier through a multiplexer, the purpose of programmable gain is achieved.

[0028] The differential drive circuit converts the single-ended signal into a differential drive signal, improving the driving ability and anti-interference ability of the signal.

[0029] The analog-to-digital conversion circuit uses low-frequency acquisition technology to detect the amplitude and phase of high-frequency signals.

[0030] The controller DSP realizes flexible control of the programmable gain amplifier circuit and the analog-to-digital conversion circuit.

[0031] As Figure 2 shown, in the current sampling transformer and the preamplifier circuit, the first pin of chip 2N1 is the signal output pin, connected to one end of resistor 2R3. The second pin of chip 2N1 is connected to one end of resistor 2R2 and one end of resistor 2R3. The third pin of chip 2N1 is connected to one end of resistor 2R4 and one end of resistor 2R5. The fourth pin of chip 2N1 is connected to the negative end of polar capacitor 2C3, one end of capacitor 2C4, and the third pin of three-terminal filter 2L2. The fifth, sixth, seventh, eighth, and ninth pins of chip 2N1 are left floating. The tenth pin of chip 2N1 is connected to the positive end of polar capacitor 2C1, one end of capacitor 2C2, and the third pin of three-terminal filter 2L1. The first pin of three-terminal filter 2L1 is externally connected to the +5V power supply. The second pin of three-terminal filter 2L1 is connected to the analog ground AGND. The first pin of three-terminal filter 2L2 is externally connected to the -5V power supply. The second pin of three-terminal filter 2L2 is connected to the analog ground AGND. The first pin of transformer T1 is connected to the differential negative polarity signal. The second pin of transformer T1 is connected to the differential positive polarity signal. The third pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R2. The fourth pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R4. The negative end of polar capacitor 2C1, one end of capacitor 2C2, the positive end of polar capacitor 2C3, one end of capacitor 2C4, and one end of resistor 2R5 are connected to the analog ground AGND.

[0032] As Figure 3As shown, in the multiplication mixer circuit, the first pin of chip 3N1 is the signal input pin, connected to one end of resistor 3R8 and one end of resistor 3R10. The second pin of chip 3N1 is connected to one end of resistor 3R4. The third pin of chip 3N1 is connected to one end of resistor 3R4. The fourth pin of chip 3N1 is connected to one end of resistor 3R9 and one end of resistor 3R11. The fifth pin of chip 3N1 is connected to one end of resistor 3R12. The sixth pin of chip 3N1 is connected to one end of resistor 3R6 and one end of capacitor 3C10. The seventh pin of chip 3N1 is connected to one end of resistor 3R3. The eighth pin of chip 3N1 is connected to one end of resistor 3R2 and one end of capacitor 3C5. The ninth pin of chip 3N1 is connected to one end of resistor 3R7 and one end of capacitor 3C9. The tenth pin of chip 3N1 is connected to one end of resistor 3R8, one end of resistor 3R9, the negative end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, and the third pin of three-terminal filter 3L2. The first pin of three-terminal filter 3L1 is externally connected to the +5V power supply. The second pin of three-terminal filter 3L1 is connected to analog ground AGND. The third pin of three-terminal filter 3L1 is connected to the positive end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C4, one end of resistor 3R5, one end of resistor 3R6, and one end of resistor 3R7. The first pin of three-terminal filter 3L2 is externally connected to the -5V power supply. The second pin of three-terminal filter 3L2 is connected to analog ground AGND. The negative end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C3, one end of capacitor 3C4, the positive end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, one end of resistor 3R1, one end of resistor 3R10, one end of resistor 3R11, one end of resistor 3R12, and one end of resistor 3R13 are connected to analog ground AGND. One end of capacitor 3C5 is externally connected to the local oscillator signal FL. One end of capacitor 3C9 is connected to one end of resistor 3R13. One end of capacitor 3C10 is connected to the output signal.

[0033] As Figure 4As shown, in the filtering circuit, the first pin of chip 4N1 is the signal output pin and is connected to the second pin of chip 4N1. The third pin of chip 4N1 is connected to one end of resistor 4R1, one end of resistor 4R4, and one end of capacitor 4C3, and is also connected to the seventh pin of chip 4N1. The fourth pin of chip 4N1 is externally connected to the +5V power supply and one end of inductor 4L2. The fifth pin of chip 4N1 is connected to one end of resistor 4R4 and one end of resistor 4R5. The sixth pin of chip 4N1 is connected to one end of resistor 4R3 and one end of capacitor 4C4. The eighth, ninth, and tenth pins of chip 4N1 are left floating. The eleventh pin of chip 4N1 is externally connected to the -5V power supply and one end of inductor 4L3. The twelfth pin of chip 4N1 is externally connected to the input signal. The thirteenth pin of chip 4N1 is connected to one end of resistor 4R2 and is also connected to the fourteenth pin of chip 4N1. One end of inductor 4L1 is connected to analog ground AGND and the other end is connected to digital ground DGND. One end of inductor 4L2 is connected to one end of capacitor 4C1 and the positive terminal of polarized capacitor 4C2. One end of inductor 4L3 is connected to one end of capacitor 4C5 and the positive terminal of polarized capacitor 4C6. One end of capacitor 4C1, the negative terminal of polarized capacitor 4C2, one end of capacitor 4C4, one end of resistor 4R5, one end of capacitor 4C5, and the negative terminal of polarized capacitor 4C6 are connected to analog ground AGND. One end of resistor 4R1 is connected to digital ground DGND.

[0034] As Figure 5 shown, in the programmable amplification circuit, the first pin of chip 5N1 is connected to one end of resistor 5R3, one end of capacitor 5C1, digital ground DGND, and the tenth pin of chip 5N1. The second pin of chip 5N1 is connected to one end of resistor 5R2 and one end of capacitor 5C2. The third pin of chip 5N1 is connected to one end of resistor 5R3 and one end of resistor 5R4. The fourth pin of chip 5N1 is externally connected to the +5V power supply. The fifth, sixth, and seventh pins of chip 5N1 are left floating. The eighth pin of chip 5N1 is the output signal pin and is connected to the ninth pin of chip 5N1. The eleventh pin of chip 5N1 is externally connected to the -5V power supply. The twelfth, thirteenth, and fourteenth pins of chip 5N1 are left floating. The first pin of chip 5N2 is connected to one end of resistor 5R1. The second pin of chip 5N2 is connected to analog ground AGND. The third pin of chip 5N2 is connected to the input signal. The fourth pin of chip 5N2 is externally connected to the -5V power supply. The fifth pin of chip 5N2 is externally connected to control signal G0. The sixth pin of chip 5N2 is externally connected to control signal G1. The seventh pin of chip 5N2 is externally connected to control signal G2. The eighth pin of chip 5N2 is externally connected to the +5V power supply. One end of resistor 5R4 and one end of capacitor 5C2 are connected to analog ground AGND.

[0035] As Figure 6As shown, in the differential drive circuit, the first pin of chip 6N1 is connected to one end of resistor 6R3 and resistor 6R4, the second pin of chip 6N1 is connected to analog ground AGND, the third pin of chip 6N1 is connected to the external +5V power supply, the positive end of polar capacitor 6C3 and one end of capacitor 6C4, the fourth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R4, the fifth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R1, the sixth pin of chip 6N1 is connected to the external -5V power supply, the negative end of polar capacitor 6C1 and one end of capacitor 6C2, the seventh pin of chip 6N1 is left floating, the eighth pin of chip 6N1 is connected to one end of resistor 6R1 and one end of resistor 6R2, the input signal is connected to one end of resistor 6R2, and the positive end of polar capacitor 6C1, one end of capacitor 6C2, the negative end of polar capacitor 6C3 and one end of capacitor 6C4 are connected to analog ground AGND.

[0036] This embodiment also discloses a method for extracting a reference signal of a logging-while-steering azimuth electromagnetic wave resistivity instrument. Using the above device, based on the low-frequency acquisition circuit and method, the low-frequency sampling frequency fs is designed according to the frequency f0 after down-conversion of the measured high-frequency reference signal. According to the Nyquist criterion, the fs needs to satisfy fs >= 2f0; the measured signal within the target signal period tx is sampled using the sampling frequency fs to obtain a discrete sequence x[k], where k is the k-th sampling point within the corresponding sampling time, and k is an integer between 0 and p - 1; fx is the frequency of the signal restored after low-frequency sampling; the discrete sequence x[k] obtained by low-frequency sampling is transmitted to the controller DSP for subsequent storage and processing by the digital circuit.

[0037] According to the low-frequency sampling frequency fs, the corresponding discrete Fourier coefficients are determined; A, f0, and Φ are respectively the amplitude, frequency, and phase of the measured signal. If it is sampled at the sampling frequency of fs, the discrete digital signal is obtained: A * sin(2 * pi * n * f0 / fs + Φ); the collected discrete signal is multiplied by the corresponding discrete Fourier coefficients respectively to obtain the real part and the imaginary part of the measured signal; the amplitude A and the phase Φ of the target signal are calculated using the real part and the imaginary part of the measured signal.

Claims

1. A reference signal extraction device for azimuthal electromagnetic resistivity while drilling instrument, characterized in that: It includes a current sampling transformer, a preamplifier circuit, a multiplication mixer, a filter circuit, a programmable gain amplifier circuit, a differential driver circuit, an analog-to-digital conversion circuit and a controller DSP that are electrically connected together in sequence; the output of the transmitter resonant circuit is connected to the primary of the current sampling transformer, the secondary of the current sampling transformer is electrically connected to a sampling resistor, the preamplifier circuit extracts a reference signal from the sampling resistor and performs fixed-gain amplification before sending it to the multiplication mixer, the multiplication mixer mixes the input signal of the preamplifier circuit and the local oscillator signal to generate a sum frequency signal and a difference frequency signal, the filter circuit filters the output signal of the multiplication mixer, the programmable gain amplifier circuit amplifies the filtered signal, and finally the amplified signal is output through the differential driver circuit. The analog-to-digital conversion circuit digitally converts the output signal that meets the requirements by means of low-frequency sampling under the control of the controller DSP.

2. The reference signal extraction device for the azimuthal electromagnetic wave resistivity instrument while drilling according to claim 1, wherein: In the current sampling transformer and the preamplifier circuit, the first pin of chip 2N1 is the signal output pin, connected to one end of resistor 2R3, the second pin of chip 2N1 is connected to one end of resistor 2R2 and one end of resistor 2R3, the third pin of chip 2N1 is connected to one end of resistor 2R4 and one end of resistor 2R5, the fourth pin of chip 2N1 is connected to the negative end of polar capacitor 2C3, one end of capacitor 2C4 and the third pin of three-terminal filter 2L2, the fifth, sixth, seventh, eighth and ninth pins of chip 2N1 are floating, the tenth pin of chip 2N1 is connected to the positive end of polar capacitor 2C1, one end of capacitor 2C2 and the third pin of three-terminal filter 2L1, the first pin of three-terminal filter 2L1 is externally connected to the +5V power supply, the second pin of three-terminal filter 2L1 is connected to analog ground AGND, the first pin of three-terminal filter 2L2 is externally connected to the -5V power supply, the second pin of three-terminal filter 2L2 is connected to analog ground AGND, the first pin of transformer T1 is connected to the differential negative polarity signal, the second pin of transformer T1 is connected to the differential positive polarity signal, the third pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R2, the fourth pin of transformer T1 is connected to one end of resistor 2R1 and one end of resistor 2R4, the negative end of polar capacitor 2C1, one end of capacitor 2C2, the positive end of polar capacitor 2C3, one end of capacitor 2C4 and one end of resistor 2R5 are connected to analog ground AGND.

3. The reference signal extraction device for azimuthal electromagnetic wave resistivity while drilling instrument according to claim 1, characterized in that: In the multiplication mixer circuit, the first pin of chip 3N1 is the signal input pin, connected to one end of resistor 3R8 and one end of resistor 3R10. The second pin of chip 3N1 is connected to one end of resistor 3R4. The third pin of chip 3N1 is connected to one end of resistor 3R4. The fourth pin of chip 3N1 is connected to one end of resistor 3R9 and one end of resistor 3R11. The fifth pin of chip 3N1 is connected to one end of resistor 3R12. The sixth pin of chip 3N1 is connected to one end of resistor 3R6 and one end of capacitor 3C10. The seventh pin of chip 3N1 is connected to one end of resistor 3R3. The eighth pin of chip 3N1 is connected to one end of resistor 3R2 and one end of capacitor 3C5. The ninth pin of chip 3N1 is connected to one end of resistor 3R7 and one end of capacitor 3C9. The tenth pin of chip 3N1 is connected to one end of resistor 3R8, one end of resistor 3R9, the negative end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, and the third pin of three-terminal filter 3L2. The first pin of three-terminal filter 3L1 is externally connected to the +5V power supply. The second pin of three-terminal filter 3L1 is connected to analog ground AGND. The third pin of three-terminal filter 3L1 is connected to the positive end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C4, one end of resistor 3R5, one end of resistor 3R6, and one end of resistor 3R7. The first pin of three-terminal filter 3L2 is externally connected to the -5V power supply. The second pin of three-terminal filter 3L2 is connected to analog ground AGND. The negative end of polarized capacitor 3C1, one end of capacitor 3C2, one end of capacitor 3C3, one end of capacitor 3C4, the positive end of polarized capacitor 3C6, one end of capacitor 3C7, one end of capacitor 3C8, one end of resistor 3R1, one end of resistor 3R10, one end of resistor 3R11, one end of resistor 3R12, and one end of resistor 3R13 are connected to analog ground AGND. One end of capacitor 3C5 is externally connected to the local oscillator signal FL. One end of capacitor 3C9 is connected to one end of resistor 3R13. One end of capacitor 3C10 is connected to the output signal.

4. The reference signal extraction device for the azimuthal electromagnetic wave resistivity instrument while drilling according to claim 1, wherein: In the filtering circuit, the first pin of chip 4N1 is the signal output pin, which is connected to the second pin of chip 4N1. The third pin of chip 4N1 is connected to one end of resistor 4R1, one end of resistor 4R4, and one end of capacitor 4C3, and is also connected to the seventh pin of chip 4N1. The fourth pin of chip 4N1 is externally connected to the +5V power supply and one end of inductor 4L2. The fifth pin of chip 4N1 is connected to one end of resistor 4R4 and one end of resistor 4R5. The sixth pin of chip 4N1 is connected to one end of resistor 4R3 and one end of capacitor 4C4. The eighth, ninth, and tenth pins of chip 4N1 are floating. The eleventh pin of chip 4N1 is externally connected to the -5V power supply and one end of inductor 4L3. The twelfth pin of chip 4N1 is externally connected to the input signal. The thirteenth pin of chip 4N1 is connected to one end of resistor 4R2 and is also connected to the fourteenth pin of chip 4N1. One end of inductor 4L1 is connected to the analog ground AGND, and the other end is connected to the digital ground DGND. One end of inductor 4L2 is connected to one end of capacitor 4C1 and the positive terminal of polarized capacitor 4C2. One end of inductor 4L3 is connected to one end of capacitor 4C5 and the positive terminal of polarized capacitor 4C6. One end of capacitor 4C1, the negative terminal of polarized capacitor 4C2, one end of capacitor 4C4, one end of resistor 4R5, one end of capacitor 4C5, and the negative terminal of polarized capacitor 4C6 are connected to the analog ground AGND. One end of resistor 4R1 is connected to the digital ground DGND.

5. The reference signal extraction device for azimuthal electromagnetic wave resistivity while drilling instrument according to claim 1, characterized in that: In the programmable gain amplifier circuit, the first pin of chip 5N1 is connected to one end of resistor 5R3, one end of capacitor 5C1, the digital ground DGND, and the tenth pin of chip 5N1. The second pin of chip 5N1 is connected to one end of resistor 5R2 and one end of capacitor 5C2. The third pin of chip 5N1 is connected to one end of resistor 5R3 and one end of resistor 5R4. The fourth pin of chip 5N1 is externally connected to the +5V power supply. The fifth, sixth, and seventh pins of chip 5N1 are floating. The eighth pin of chip 5N1 is the output signal pin and is connected to the ninth pin of chip 5N1. The eleventh pin of chip 5N1 is externally connected to the -5V power supply. The twelfth, thirteenth, and fourteenth pins of chip 5N1 are floating. The first pin of chip 5N2 is connected to one end of resistor 5R1. The second pin of chip 5N2 is connected to the analog ground AGND. The third pin of chip 5N2 is connected to the input signal. The fourth pin of chip 5N2 is externally connected to the -5V power supply. The fifth pin of chip 5N2 is externally connected to the control signal G0. The sixth pin of chip 5N2 is externally connected to the control signal G1. The seventh pin of chip 5N2 is externally connected to the control signal G2. The eighth pin of chip 5N2 is externally connected to the +5V power supply. One end of resistor 5R4 and one end of capacitor 5C2 are connected to the analog ground AGND.

6. The reference signal extraction device for azimuthal electromagnetic wave resistivity while drilling instrument according to claim 1, characterized in that: In the differential drive circuit, the first pin of chip 6N1 is connected to one end of resistor 6R3 and resistor 6R4, the second pin of chip 6N1 is connected to analog ground AGND, the third pin of chip 6N1 is connected to the external +5V power supply, the positive end of polarized capacitor 6C3 and one end of capacitor 6C4, the fourth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R4, the fifth pin of chip 6N1 is the differential signal output pin and is connected to one end of resistor 6R1, the sixth pin of chip 6N1 is connected to the external -5V power supply, the negative end of polarized capacitor 6C1 and one end of capacitor 6C2, the seventh pin of chip 6N1 is left floating, the eighth pin of chip 6N1 is connected to one end of resistor 6R1 and one end of resistor 6R2, the input signal is connected to one end of resistor 6R2, and the positive end of polarized capacitor 6C1, one end of capacitor 6C2, the negative end of polarized capacitor 6C3 and one end of capacitor 6C4 are connected to analog ground AGND.

7. A method for extracting a reference signal of an azimuthal electromagnetic wave resistivity instrument while drilling, using the device described in claim 1, characterized in that: Design the low-frequency sampling frequency fs according to the frequency f0 after down-conversion of the measured high-frequency reference signal; use the sampling frequency fs to sample the measured signal within the period tx of the target signal to obtain a discrete sequence x[k], where k is the k-th sampling point within the corresponding sampling time, and k is an integer between 0 and p - 1; fx is the frequency of the signal recovered after low-frequency sampling; transmit the discrete sequence x[k] obtained by low-frequency sampling to the controller DSP for subsequent storage and processing by the digital circuit.

8. The method for extracting a reference signal of an azimuthal electromagnetic wave resistivity instrument while drilling according to claim 7, characterized in that: Determine the corresponding discrete Fourier coefficients according to the low-frequency sampling frequency fs; A, f0, and Φ are respectively the amplitude, frequency, and phase of the measured signal. If it is sampled at the sampling frequency of fs, the discrete digital signal obtained is: A * sin(2 * pi * n * f0 / fs + Φ); multiply the collected discrete signal by the corresponding discrete Fourier coefficients respectively to obtain the real part and the imaginary part of the measured signal; calculate the amplitude A and phase Φ of the target signal using the real part and the imaginary part of the measured signal.

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