Method for measuring geophone distortion through linear frequency-raising scanning signals

Abstract

The invention discloses a method for measuring the distortion of a geophone through linear frequency-raising scanning signals, and belongs to the field of geophysical exploration, and the method comprises the following steps: 1, fixing a detected geophone; step 2, inputting working parameters; step 3, generating a linear frequency-raising scanning signal; 4, outputting an analog signal; step 5, automatically starting scanning to acquire response signals and timing to record length; 6, continuously collecting output signals; 7, automatically starting a data processing and analyzing process; 8, generating a reference signal; step 9, generating a pulse signal; step 10, generating an amplitude spectrum; step 11, calculating the total power of the amplitude spectrum; step 12, calculating a total power sum; step 13, obtaining passband distortion of the detected geophone; step 14, generating a passband distortion test result file; and step 15, displaying or outputting a test result. The sensing signal fidelity capability of the whole response frequency band of the geophone can be quickly and directly quantified.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration, specifically a method for measuring seismic detector distortion using linear up-frequency scanning signals. Background Technology

[0002] The discovery and exploration of underground minerals in recent decades have proven that seismic exploration is the most effective method for finding underground mineral deposits, especially oil and gas resources. As a result, oil and gas seismic exploration technology has developed rapidly, and high-precision, high-density, and broadband seismic exploration technology is currently emerging.

[0003] The key to acquiring geological data in oil and gas seismic exploration lies in the sensing, sampling, and recording of seismic wavelets, with seismic wavelet sensing being the most crucial. Typically, seismic wavelet sensing is achieved using seismic detectors. Therefore, the fidelity of the seismic detectors directly affects the quality of the geological data from seismic exploration. Thus, maximizing the fidelity of the seismic signal sensing from the seismic detectors is a fundamental condition for ensuring the effectiveness of seismic exploration.

[0004] To ensure the high-fidelity sensing performance of seismic detectors on seismic wavelets and to control the distortion introduced by seismic detectors within an acceptable range, it is usually necessary to perform distortion tests on seismic detectors. For the widely used electromagnetic induction velocity-type seismic detectors (accounting for over 90% of all detectors), the current method for testing distortion involves inputting a fundamental signal with a frequency slightly higher than the natural frequency into the detector, analyzing the harmonic energy of the response signal, and calculating the corresponding harmonic distortion. However, this traditional method only reflects the signal fidelity of the detector at a specific frequency point and cannot objectively measure its signal fidelity across the entire operating frequency band. This can lead to potential distortion risks; the tested distortion may be low, but the actual fidelity of the detector within the operating frequency band may be weak, resulting in a much higher actual distortion of the sensed seismic signal than the test result. Therefore, to improve the fidelity of the sensed seismic signal, controlling the distortion of the seismic detector within the acceptable range across the entire operating frequency band is crucial and necessary. Existing technologies cannot measure the signal fidelity of a seismic detector across the entire operating frequency band. Summary of the Invention

[0005] This invention provides a method for measuring the distortion of a seismic detector using a linear up-frequency scanning signal, thereby overcoming the deficiencies in the prior art.

[0006] This invention is achieved through the following technical solution: A method for measuring seismic detector distortion using a linear up-frequency scanning signal includes the following steps: Step 1: Vertically and tightly couple the seismic detector to be tested onto the fixture and connect it to the testing instrument; Step 2: Input the natural frequency, sensitivity, inertial body stroke, inertial body mass, coil resistance, coil parallel resistance, as well as the working parameters of start frequency, end frequency, harmonic order, and recording length; Step 3: Generate a linear up-frequency scanning signal represented by a digital signal from the database according to the set working parameters; Step 4: The driving circuit converts the digital signal output from the scan signal sample library into an analog signal with a distortion of ≤0.0005%; Step 5: Automatically start scanning to acquire response signals and record timing length according to the set working parameters; Step 6: Continuously acquire the response output signal of the seismic detector until the recording length is met; Step 7: Once the recording length is reached, the data acquisition and recording process ends, and the data processing and analysis workflow is automatically started; Step 8: Based on the frequency characteristics of the excitation scanning signal and the harmonic calculation, generate a reference signal with the same amplitude as the fundamental signal and a harmonic relationship; Step 9: The collected and stored inductive signal data are correlated with each frequency harmonic reference signal according to the calculation rules to generate corresponding correlation pulse signals; Step 10: According to the time-domain to frequency-domain conversion rules, perform Fourier transform on each relevant pulse to generate an amplitude spectrum with a frequency band consistent with the harmonic reference signal. Step 11: Calculate the total amplitude spectrum power corresponding to the fundamental wave and each harmonic in sequence according to the amplitude spectrum power calculation rules; Step 12: Calculate the total power of each harmonic based on its order; Step 13: Multiply the total power of each harmonic by 100% of the total power of the fundamental wave to obtain the passband distortion of the seismic detector under test; Step 14: Generate the passband distortion test result file and save it to the storage; Step 15: Display or output the test results.

[0007] In the linear up-frequency scanning signal method for measuring seismic detector distortion described above, if no working parameters are set in step 2, the system automatically enters the historical parameter or default parameter working mode.

[0008] As described above, in a method for measuring seismic detector distortion using a linear up-frequency scanning signal, step 3 generates a scanning signal satisfying the following formula, provided that the starting frequency is ≤ 0.5 times the natural frequency and the stopping frequency is ≥ 100Hz: s(t) = A*sin{2π*[f c +t*(fz -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

[0009] As described above, in a method for measuring seismic detector distortion using a linear upsampling scanning signal, step 3, in the default parameter operating mode, generates a scanning signal satisfying the following formula: s(t) = A*sin{2π*[f c +t*(f z -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

[0010] In the linear up-frequency scanning signal method for measuring seismic detector distortion described above, step 4 involves adjusting the analog signal to an excitation signal whose driving current satisfies the following formula based on the set operating parameters: I = [0.42995 * (R c +R d ) / R d ]*M*F0*(F0+f)*Z / S, where I is the drive signal current in µA; R c R is the coil resistance, in Ω. d Ω is the parallel resistance of the coil; g is the mass of the inertial body; Hz is the natural frequency of the seismic detector; Z is the maximum stroke of the inertial body; V / m / s is the output sensitivity of the seismic detector; the excitation signal is directly input to the seismic detector under test.

[0011] In the method for measuring seismic detector distortion using a linear up-frequency scanning signal as described above, step 5 involves timing the signal in 1-second increments, provided that the duration is at least 5 seconds and at most 20 seconds.

[0012] In the linear up-frequency scanning signal method for measuring seismic detector distortion described above, step 5 of the default parameter operating mode is timed according to a length of 10 seconds.

[0013] In the linear upsampling scanning signal method for measuring seismic detector distortion described above, step 6 has a bandwidth of 1600Hz, a sampling interval of 0.25ms, and the collected data is stored in a buffer according to the timing relationship.

[0014] As described above, in a method for measuring seismic detector distortion using linear upsampling signals, step 8 generates 1st, 2nd, and 3rd harmonic signals when the system operates in default parameter mode; otherwise, it generates corresponding harmonic signals according to a set number of times. These signals are used as the correlation modulus for calculating the distortion of each harmonic.

[0015] In the method for measuring seismic detector distortion using a linear up-frequency scanning signal as described above, the maximum number of cycles is 9.

[0016] The advantages of this invention are: This invention can quickly and directly quantify the sensing signal fidelity capability of a seismic detector across the entire response frequency band. For the first time, it identifies the fidelity effect and quality of a seismic detector from its frequency band characteristics, creating conditions for simplifying the methods and procedures for testing the passband distortion of seismic detectors and improving the efficiency of seismic detector performance testing. The passband distortion testing method and technique for seismic detectors provided by this invention are more scientific, reliable, and convenient than traditional single-frequency methods for testing seismic instrument distortion. The test results directly and comprehensively reflect the full-band signal fidelity of the seismic detector. Traditional seismic detector distortion testing methods generally analyze harmonic distortion in the vicinity of natural frequency points using single-frequency signal excitation, which cannot objectively reflect the signal fidelity capability of the entire frequency band (it only reflects the signal fidelity effect at one frequency point). The passband distortion measurement method and technique for seismic detectors provided by this invention are rigorous and meticulous, and the test results are global, enabling rapid and direct quantification of the sensor signal fidelity effect at continuous frequency points. This facilitates an objective and comprehensive evaluation of the seismic detector's fidelity capability and lays a foundation for improving the quality of seismic data. The test results of this invention have extremely high dynamic range and sensitivity. The cross-correlation process greatly suppresses uncorrelated broadband noise, making it possible to detect even very weak harmonic components. The measurement accuracy is far superior to that of traditional methods. This invention can quickly scan the entire frequency band information in one go, and obtain the distortion of all frequency points in the entire frequency band (fc to fz). It can be adapted to the testing of various types of seismic detectors. In contrast, traditional methods require separate measurement at each frequency point, which is not only extremely slow but also limits the single-frequency signal that can be generated, thus limiting the types of seismic detectors that can be adapted. The present invention can resolve instantaneous dynamics of more than 90 dB (<0.002%), while the traditional method for testing seismic detector distortion can resolve instantaneous dynamics of less than 75 dB (>0.02%), making it more suitable for testing high-fidelity seismic detectors. The test results of this invention can be plotted as a curve showing the relationship between distortion and frequency, intuitively demonstrating how the distortion of the seismic detector changes with frequency. It can also separate the proportion of each harmonic component, and simultaneously separate and measure the second, third, fourth, and other harmonics. All of these provide intuitive and quantitative guidance for identifying weak points in the fidelity of seismic detectors, improving seismic detector design, and diagnosing anomalies. This invention enriches the technical characteristic testing methods of seismic detectors, adapts to the relevant technical requirements put forward by the newly released industry standards, and only this invention can fully meet the passband distortion items and technical indicators clearly listed in the newly released industry standards. This invention also adds a new technical means for third-party organizations to test and evaluate the quality of seismic detectors. It can quantitatively verify the full-band fidelity of seismic detectors, thereby identifying the characteristic differences of different seismic detectors from the source, thus promoting the healthy development of seismic detector technology. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, a method for measuring seismic detector distortion using a linear up-frequency scanning signal includes the following steps: Step 1: Vertically and tightly couple the seismic detector to be tested onto the fixture and connect it to the testing instrument; Step 2: Input the natural frequency, sensitivity, inertial body stroke, inertial body mass, coil resistance, coil parallel resistance, as well as the working parameters of start frequency, end frequency, harmonic order, and recording length; Step 3: Generate a linear up-frequency scanning signal represented by a digital signal from the database according to the set working parameters; Step 4: The driving circuit converts the digital signal output from the scan signal sample library into an analog signal with a distortion of ≤0.0005%; Step 5: Automatically start scanning to acquire response signals and record timing length according to the set working parameters; Step 6: Continuously acquire the response output signal of the seismic detector until the recording length (scan length) is met; Step 7: Once the recording length (scan length) is reached, the data acquisition and recording process ends, and the data processing and analysis workflow is automatically started; Step 8: Based on the frequency characteristics of the excitation scanning signal and the harmonic calculation, generate a reference signal with the same amplitude as the fundamental signal and a harmonic relationship; Step 9: The collected and stored inductive signal data are correlated with each frequency harmonic reference signal according to the calculation rules to generate corresponding correlation pulse signals; Step 10: According to the time-domain to frequency-domain conversion rules, perform Fourier transform on each relevant pulse to generate an amplitude spectrum with a frequency band consistent with the harmonic reference signal. Step 11: Calculate the total amplitude spectrum power corresponding to the fundamental wave and each harmonic in sequence according to the amplitude spectrum power calculation rules; Step 12: Calculate the total power of each harmonic based on its order; Step 13: Multiply the total power of each harmonic by 100% of the total power of the fundamental wave to obtain the passband distortion of the seismic detector under test; Step 14: Generate the passband distortion test result file and save it to the storage; Step 15: Display or output the test results.

[0021] Preferably, in step 2 of this embodiment, if no working parameters are set, the system will automatically enter the working mode of historical parameters or default parameters.

[0022] Preferably, in step 3 of this embodiment, under the conditions that the starting frequency is ≤ 0.5 times the natural frequency and the stopping frequency is ≥ 100Hz, a scanning signal satisfying the following formula is generated: s(t) = A*sin{2π*[f c +t*(f z -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

[0023] Preferably, in step 3 of this embodiment, the default parameter operating mode generates a scanning signal that satisfies the following formula when running with a starting frequency of 0.5Hz, an ending frequency of 200Hz, and a scanning time of 10s: s(t)=A*sin{2π*[f c +t*(f z -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

[0024] Preferably, in step 4 of this embodiment, the analog signal is adjusted to an excitation signal whose drive current satisfies the following formula based on the set operating parameters (or historical data): I=[0.42995*(R c +R d ) / R d ]*M*F0*(F0+f)*Z / S, where I is the drive signal current (RMS), in µA; R c R is the coil resistance, in Ω. d Ω is the parallel resistance of the coil; g is the mass of the inertial body; Hz is the natural frequency of the seismic detector; Z is the maximum stroke of the inertial body; V / m / s is the output sensitivity of the seismic detector; the excitation signal is directly input to the seismic detector under test.

[0025] Preferably, in step 5 of this embodiment, timing is performed in 1-second increments, provided that the time is at least 5 seconds and at most 20 seconds.

[0026] Preferably, in step 5 of this embodiment, the default parameter working mode is timed in 10-second increments.

[0027] Preferably, in step 6 of this embodiment, the bandwidth is 1600Hz (to meet the needs of multiple harmonic calculations), the sampling interval is 0.25ms, and the collected data is stored in a buffer (storage circuit) according to the timing relationship.

[0028] Preferably, in step 8 of this embodiment, the default parameter working mode generates 1st, 2nd, and 3rd harmonic signals; otherwise, the corresponding harmonic signals are generated according to the set number of times, which are used as the correlation modulus for calculating the harmonic distortion of each order.

[0029] Preferably, the maximum number of times set in this embodiment is 9.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring seismic detector distortion using a linear up-frequency scanning signal, characterized in that: Includes the following steps: Step 1: Vertically and tightly couple the seismic detector to be tested onto the fixture and connect it to the testing instrument; Step 2: Input the natural frequency, sensitivity, inertial body stroke, inertial body mass, coil resistance, coil parallel resistance, as well as the working parameters of start frequency, end frequency, harmonic order, and recording length; Step 3: Generate a linear up-frequency scanning signal represented by a digital signal from the database according to the set working parameters; Step 4: The driving circuit converts the digital signal output from the scan signal sample library into an analog signal with a distortion of ≤0.0005%; Step 5: Automatically start scanning to acquire response signals and record timing length according to the set working parameters; Step 6: Continuously acquire the response output signal of the seismic detector until the recording length is met; Step 7: Once the recording length is reached, the data acquisition and recording process ends, and the data processing and analysis workflow is automatically started; Step 8: Based on the frequency characteristics of the excitation scanning signal and the harmonic calculation, generate a reference signal with the same amplitude as the fundamental signal and a harmonic relationship; Step 9: The collected and stored inductive signal data are correlated with each frequency harmonic reference signal according to the calculation rules to generate corresponding correlation pulse signals; Step 10: According to the time-domain to frequency-domain conversion rules, perform Fourier transform on each relevant pulse to generate an amplitude spectrum with a frequency band consistent with the harmonic reference signal. Step 11: Calculate the total amplitude spectrum power corresponding to the fundamental wave and each harmonic in sequence according to the amplitude spectrum power calculation rules; Step 12: Calculate the total power of each harmonic based on its order; Step 13: Multiply the total power of each harmonic by 100% of the total power of the fundamental wave to obtain the passband distortion of the seismic detector under test; Step 14: Generate the passband distortion test result file and save it to the storage; Step 15: Display or output the test results.

2. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: If no working parameters are set in step 2, the system will automatically enter the historical parameters or default parameters working mode.

3. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 3, under the conditions that the starting frequency is ≤ 0.5 times the natural frequency and the stopping frequency is ≥ 100Hz, a scanning signal is generated that satisfies the following formula: s(t) = A*sin{2π*[f c +t*(f z -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

4. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 3, the default parameter operating mode generates a scan signal that satisfies the following formula when running with a start frequency of 0.5Hz, an end frequency of 200Hz, and a scan time of 10s: s(t) = A*sin{2π*[f c +t*(f z -f c ) / (2T)]*t}, where t is the independent variable time, in seconds; A is the signal amplitude, in volts (V); f c f is the starting frequency, in Hz. z The terminator frequency is Hz; T is the scan length in seconds.

5. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 4, the analog signal is adjusted to an excitation signal whose drive current satisfies the following formula according to the set operating parameters: I = [0.42995 * (R)] c +R d ) / R d ]*M*F0*(F0+f)*Z / S, where I is the drive signal current in µA; R c R is the coil resistance, in Ω. d Ω is the parallel resistance of the coil; g is the mass of the inertial body; Hz is the natural frequency of the seismic detector; Z is the maximum stroke of the inertial body; V / m / s is the output sensitivity of the seismic detector; the excitation signal is directly input to the seismic detector under test.

6. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 5, timing is performed in 1-second increments, provided that the time is at least 5 seconds and at most 20 seconds.

7. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 5, the default parameter working mode operates on a 10-second timer.

8. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 6, the bandwidth is 1600Hz, the sampling interval is 0.25ms, and the collected data is stored in the buffer according to the timing relationship.

9. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: In step 8, the default parameter working mode generates 1st, 2nd, and 3rd harmonic signals; otherwise, it generates the corresponding harmonic signals according to the set number of times, which are used as the correlation modulus for calculating the distortion of each harmonic.

10. The method for measuring seismic detector distortion using a linear up-frequency scanning signal according to claim 1, characterized in that: The maximum number of times can be set is 9.

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