Method for correcting polarization effect of power supply electrode

Abstract

The application discloses a power supply electrode polarization effect correction method, which comprises the following steps: step 1, obtaining the correction coefficient of a tested electrode by using the electrode correction coefficient testing method in claim 1; step 2, determining the polarization potential difference decay curve of the electrode through experiments; step 3, selecting a suitable fitting formula according to the change characteristics of the polarization potential difference decay curve obtained in step 2, and obtaining the functional relationship between the polarization potential difference and time through curve fitting; the function expression can be used to calculate the polarization potential difference of the power supply electrode with the same material as the tested electrode at any time after power-off; and step 4, correcting the polarization effect of the power supply electrode with the same material as the tested electrode by using the functional relationship obtained in step 3. The application determines the polarization potential difference decay curve of the electrode through experiments, and corrects the potential difference data measured in the field by using the decay curve.

Description

Technical Field

[0001] This invention relates to a geophysical data correction method, belonging to the field of geophysical exploration, and specifically to a method for correcting the polarization effect of power supply electrodes. Background Technology

[0002] Electrical resistivity tomography (EPM) enables non-invasive, non-destructive detection of various geological targets, finding wide application in energy, mineral, and water resource exploration, geological hazard detection, and urban shallow surface engineering exploration. For DC resistivity methods, EPM equipment is increasingly evolving towards a distributed, multi-channel parallel, high-efficiency acquisition mode. With a single wiring and power supply cycle, data acquisition for various observation methods, such as electrical sounding, electrical profiling, and electrical radiography, can be completed using a single setup. Compared to traditional centralized, single-channel rolling acquisition methods, this significantly improves data acquisition efficiency.

[0003] In high-density electrical resistivity tomography (EPT) data acquisition, electrodes are typically used for both power supply and signal measurement. When one electrode is used for power supply, the remaining electrodes are used for signal measurement. Different electrodes rotate power supply throughout the data acquisition process. Physically, the power supply electrode and the measurement electrode are the same electrode, but they serve different functions at different times. However, experimental studies have revealed that electrodes exhibit polarization during power supply. This means that the positive and negative electrons in the electrode redistribute under the influence of current, concentrating at both ends of the electrode. This results in a voltage drop between the two ends of the electrode for a period after power is cut off, forming a polarization potential difference. EPT data acquisition focuses on the potential difference between the two electrodes. When an electrode previously used for power supply is used again for signal measurement, its own polarization potential difference can significantly impact data acquisition.

[0004] For electromagnetic exploration methods such as induced polarization methods, which are heavily influenced by polarization effects, non-polarized electrodes are generally used for data acquisition. A common non-polarized electrode consists of a copper rod placed in a saturated copper sulfate solution in a glazed ceramic container. The copper rod conducts electricity through ions from the copper sulfate solution permeating the ceramic container, reducing the polarization potential difference of the measuring electrode itself. This type of non-polarized electrode requires periodic replenishment of the copper sulfate solution, making construction and maintenance difficult. In recent years, solid non-polarized electrodes made of materials such as Pb / PbCl-2 and Ag / AgCl have emerged, as well as non-polarized electrodes made by coating the surface of metal electrodes with conductive microparticles. These all require special processing techniques, resulting in relatively high manufacturing costs. For parallel electrical methods, dual-mode electrodes are used, separating the power supply electrode and the measuring electrode. This method also requires special electrode processing, leading to relatively high manufacturing costs. In summary, current solutions to electrode polarization effects mainly involve improving the electrode itself, which generally results in high costs. These solutions are acceptable when the electrode can be reused. However, when electrodes cannot be reused, such as in monitoring water hazards in underground coal mine goaf areas or in borehole electrical discharge machining, the electrodes are difficult to recover. Reducing electrode costs is a key issue that needs to be considered during construction.

[0005] Furthermore, the Chinese invention patent "A Method for Planning Ultra-High Density Electrode Arrangements to Eliminate Polarization Interference" reduces polarization interference by re-planning the arrangement order of power supply and measurement electrodes. Since the polarization potential difference of electrodes decays over time, this method, after re-planning the electrode arrangement order using a global optimization method, can delay the time between when electrodes are used for power supply and when they are used for signal measurement, thus reducing polarization interference. However, the decay of the polarization potential difference over time is a relatively slow process. While the above method can reduce polarization interference to some extent, the influence of electrode polarization effects is still difficult to avoid in the acquired data, and the electrode utilization efficiency is relatively low.

[0006] If the polarization effect of the power supply electrode can be corrected through data processing, then there is no need to make special process improvements to the electrode, nor is it necessary to re-plan the electrode arrangement order through complex algorithms. However, there is currently no publicly available solution for this. Summary of the Invention

[0007] The present invention mainly addresses the technical problem of how to correct the polarization effect of the power supply electrode through data processing methods in the prior art, and provides a method for correcting the polarization effect of the power supply electrode, which is used in the data acquisition process of electrical resistivity tomography / monitoring.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] On one hand, the present invention provides a method for testing the correction coefficient of an electrode, specifically including the following steps:

[0010] Step 11: Use a single-pole-single-pole observation device to measure experimental data; designate the electrode to be tested as electrode 1. The material of electrode 1 can be conductive materials such as stainless steel, copper, or graphite, depending on the requirements; prepare 3 auxiliary electrodes, designated as electrode 2, electrode 3, and electrode 4 respectively. The material of the auxiliary electrodes should be the same as that of electrode 1.

[0011] Step 12: Following the unipolar transmission and unipolar reception mode, install electrode 1 at the position of the measuring electrode and electrode 3 at the position of the transmitting electrode, with a distance of about 100m between electrodes 1 and 3; use electrodes 2 and 4 as infinity electrodes.

[0012] Step 13: Electrode 1 and electrode 2 form a measurement circuit, and electrode 3 and electrode 4 form a power supply circuit; power is supplied to the power supply circuit formed by electrode 3 and electrode 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; the power supply current is kept stable, and the power supply current and power supply duration are consistent with the actual exploration equipment; the potential difference is measured using the measurement circuit formed by electrode 1 and electrode 2, and the measured value is recorded as U0. The measured value at this time is the measured value before electrode 1 is polarized;

[0013] Step 14, polarize the No. 1 battery: Replace the No. 3 electrode with the No. 1 electrode and install it at the emitter electrode position, so that the No. 1 and No. 4 electrodes form a power supply circuit; supply power to the power supply circuit formed by the No. 1 and No. 4 electrodes, with the No. 1 electrode connected to the positive terminal of the power supply and the No. 4 electrode connected to the negative terminal of the power supply; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; at this time, the polarization of the No. 1 electrode is achieved by supplying power to the No. 1 electrode;

[0014] Step 15: Reinstall electrode 1 back to its original measuring electrode position and electrode 3 back to its original emitting electrode position; electrodes 1 and 2 form a measuring circuit, and electrodes 3 and 4 form a power supply circuit; supply power to the power supply circuit formed by electrodes 3 and 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; measure the potential difference using the measuring circuit formed by electrodes 1 and 2, and record the measured value as U1. This measured value is the value after electrode 1 is polarized;

[0015] Step 16, define the correction coefficient α; compare the magnitudes of U1 and U0. If U1 > U0, α = 1; if U1 > U0, α = 1. <U0,α=-1。

[0016] Secondly, the present invention also provides a method for correcting the polarization effect of the power supply electrode, specifically including the following steps:

[0017] Step 1: Obtain the correction coefficient of the electrode under test using the electrode correction coefficient test method described in claim 1;

[0018] Step 2: Experimentally determine the attenuation curve of the polarization potential difference of the electrode;

[0019] Step 3: Based on the variation characteristics of the polarization potential difference decay curve obtained in Step 2, select a suitable fitting formula and obtain the functional relationship U between polarization potential difference and time through curve fitting. 极化 =f(t); This function expression can be used to calculate the polarization potential difference of a power supply electrode made of the same material as the electrode being tested at any time after power is turned off.

[0020] Step 4, use the functional relationship U obtained in step 3. 极化 =f(t) corrects the polarization effect of the power supply electrode, which is made of the same material as the electrode being tested. The specific steps are as follows:

[0021] During the acquisition of electrical detection / monitoring data, the electrodes used for power supply are marked, and the time interval t from when they are used for power supply to when they are used for signal measurement is recorded. During the completion of a complete data acquisition, each time an electrode participates in signal measurement, if it has been marked as a power supply electrode, the time interval t from when it is used for power supply to when it is used for signal measurement must be updated.

[0022] When performing signal measurements, determine whether the electrode involved in the measurement is marked as the power supply electrode. If not, polarization effect correction is not required; if so, perform correction as follows:

[0023] (1) When performing a unipolar measurement, the current electrode is denoted as M, and the U obtained in step 3 is used as the reference. 极化 =f(t) Calculate the polarization potential difference of electrode M The polarization effect correction formula is as follows:

[0024]

[0025] In the formula, U 测量 Indicates measurement data; U 校正 This represents the corrected measurement data; α represents the correction coefficient for the electrode.

[0026] (2) When performing dipole measurements, the electrode closer to the positive terminal of the power supply is denoted as M, and the electrode closer to the negative terminal is denoted as N. According to U... 极化 =f(t) Calculate the polarization potential difference between electrodes M and N respectively. and If only one electrode is used as the over-supply electrode, the polarization potential difference of the other electrode is 0; the polarization effect correction formula is as follows:

[0027]

[0028] Furthermore, step 2 includes the following operations:

[0029] Remove electrode 1 and allow it to stand for a sufficient period of time until the polarization potential difference between its two ends drops to 0. Re-polarize electrode 1 with electricity, then stop the power supply and record the moment of power failure as t0. Continuously measure the polarization potential difference between the two ends of electrode 1 using a potential difference measuring device and record the measurement time t. i and measured values Let t = t i -t0, with time t as the x-axis, polarization potential difference Plot the polarization potential difference decay curve over time on the ordinate.

[0030] The present invention also provides a method for correcting the polarization effect of the power supply electrode in a monopole-monopole observation device, comprising the following steps:

[0031] Step 1: If all electrodes are sequentially powered, proceed to either Step 2 or Step 3; if power is supplied across electrodes and all electrodes are involved in the measurement, proceed to Step 4.

[0032] Step 2, record the unipolar-to-unipolar measurement data as U 单极 (i), where i is the electrode number, i = 1, 2, 3, ..., N; N is the total number of electrodes. The measurement data includes the true potential difference and the polarization potential difference, i.e., U 单极 (i)=U 真实 (i)+αU 极化 (i), where α is the correction coefficient; the extraction formula for unipolar-dipole observation data is as follows:

[0033] U 偶极 (i)=U 单极 (i+1)-U 单极 (i)≈U 真实 (i+1)-U 真实 (i) (i = 1, 2, 3, ..., N-1);

[0034] Step 3, record the unipolar measurement data corresponding to the two different power supply electrodes as follows: and The following formula is used to extract dipole-dipole observation data:

[0035]

[0036] i = 1, 2, 3, ..., N-1;

[0037] Step 4, record the measurement data of the odd-numbered electrodes as U. 测量 (i1), where i1 is an odd-numbered electrode, i1 = 1, 3, 5, ... The measurement data of the even-numbered electrodes are denoted as U. 测量 (i2) (i2 is an even-numbered electrode, i2 = i1 + 1); odd-numbered electrodes participate in power supply, U 测量 (i1)=U 真实 (i1)+αU 极化 (i1); Even-numbered electrodes do not participate in power supply, U 测量 (i2)=U 真实 (i2).

[0038] The formula for extracting unipolar-dipole observation data is as follows:

[0039] U 偶极 (i1)=U 测量 (i2)-U 测量 (i1)=U 真实 (i2)-U 真实 (i1)-αU 极化 (i1)

[0040] U 偶极 (i2)=U 测量 (i1+2)-U 测量 (i2)=U 真实 (i1+2)-U 真实 (i2)+αU 极化 (i1+2),

[0041] i1=1,3,5,…;i2=i1+1

[0042] When U 极化 (i1)≈U 极化 When (i1+2), i1=1, 3, 5, ……, the formula for correcting the polarization effect of the power supply electrode is as follows:

[0043]

[0044]

[0045]

[0046]

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] 1. This invention experimentally determines the decay curve of the polarization potential difference of the electrode over time, and uses the decay curve to correct the potential difference data measured in the field.

[0049] 2. When adjacent electrodes participate in power supply at similar times, the polarization potential difference can be canceled by recombining the measurement data of adjacent electrodes, thereby achieving polarization effect correction of the power supply electrode.

[0050] 3. This invention reduces electrode manufacturing costs by eliminating the need for special process improvements to the electrodes; it also improves electrode utilization efficiency by eliminating the need for complex algorithms to re-plan the electrode arrangement order; and it can eliminate the influence of polarization effect of power supply electrodes, improve the quality of exploration / monitoring data, and lay a data foundation for high-precision interpretation of electrical exploration results. Attached Figure Description

[0051] Figure 1 This is a curve based on actual downhole measured data;

[0052] Figure 2 The data curves are obtained after the polarization effect of the power supply electrode has been corrected. Detailed Implementation

[0053] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0054] This invention provides a method for correcting the polarization effect of a power supply electrode. The polarization effect of the electrode is experimentally measured, and the measured results are used to correct actual observation data. The specific technical solution is as follows:

[0055] Step 1: Determine the correction coefficient of the electrode experimentally. The specific steps are as follows:

[0056] Step 11: Use a single-pole-single-pole observation device to measure experimental data; designate the electrode to be tested as electrode 1. The material of electrode 1 can be conductive materials such as stainless steel, copper, or graphite, depending on the requirements; prepare 3 auxiliary electrodes, designated as electrode 2, electrode 3, and electrode 4 respectively. The material of the auxiliary electrodes should be the same as that of electrode 1.

[0057] Step 12: Following the single-electrode transmission and single-electrode reception mode, install electrode 1 at the position of the measuring electrode and electrode 3 at the position of the transmitting electrode, with a distance of about 100m between electrodes 1 and 3; arrange electrodes 2 and 4 as infinity electrodes at a distance of more than 100 meters, ensuring sufficient distance between electrodes 2 and 4.

[0058] Step 13: Electrode 1 and electrode 2 form a measurement circuit, and electrode 3 and electrode 4 form a power supply circuit; power is supplied to the power supply circuit formed by electrode 3 and electrode 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; the power supply current is kept stable, and the power supply current and power supply duration are consistent with the actual exploration equipment; the potential difference is measured using the measurement circuit formed by electrode 1 and electrode 2, and the measured value is recorded as U0. The measured value at this time is the measured value before electrode 1 is polarized;

[0059] Step 14, polarize the No. 1 battery: Replace the No. 3 electrode with the No. 1 electrode and install it at the emitter electrode position, so that the No. 1 and No. 4 electrodes form a power supply circuit; supply power to the power supply circuit formed by the No. 1 and No. 4 electrodes, with the No. 1 electrode connected to the positive terminal of the power supply and the No. 4 electrode connected to the negative terminal of the power supply; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; at this time, no measurement is required, and the polarization of the No. 1 electrode is achieved simply by supplying power to the No. 1 electrode;

[0060] Step 15: Reinstall electrode 1 back to its original measuring electrode position and electrode 3 back to its original emitting electrode position; electrodes 1 and 2 form a measuring circuit, and electrodes 3 and 4 form a power supply circuit; supply power to the power supply circuit formed by electrodes 3 and 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; measure the potential difference using the measuring circuit formed by electrodes 1 and 2, and record the measured value as U1. This measured value is the value after electrode 1 is polarized;

[0061] Step 16, define the correction coefficient α; compare the magnitudes of U1 and U0. If U1 > U0, α = 1; if U1 > U0, α = 1. <U0,α=-1。

[0062] Step 2: The polarization potential difference decay curve of the electrode is measured experimentally. The specific steps are as follows:

[0063] Remove electrode 1 and allow it to stand for a sufficient period of time until the polarization potential difference between its two ends drops to 0. Re-polarize electrode 1 using the polarization method described in step 14, then stop supplying power. Record the moment of power cut-off (in actual exploration, electrodes are supplied alternately, and the power supply duration for a single electrode is fixed. After a certain duration, the power supply circuit for the current electrode is cut off, and another electrode is connected to the power supply circuit; the moment of power cut-off refers to the moment when the power supply circuit for the current electrode is cut off) as t0. Continuously measure the polarization potential difference between the two ends of electrode 1 using a potential difference measuring device and record the measurement time t. i and measured values Let t = t i-t0, with time t as the x-axis, polarization potential difference Plot the polarization potential difference decay curve over time on the ordinate.

[0064] Step 3: Based on the variation characteristics of the polarization potential difference decay curve obtained in Step 2, select a suitable fitting formula and obtain the functional relationship U between polarization potential difference and time through curve fitting. 极化 =f(t); This function expression can be used to calculate the polarization potential difference of a power supply electrode made of the same material as electrode 1 at any time after power is cut off.

[0065] Step 4, use the functional relationship U obtained in step 3. 极化 =f(t) corrects the polarization effect of the power supply electrode, which is made of the same material as electrode 1. The specific steps are as follows:

[0066] During the electrical resistivity tomography (EPR) data acquisition process, the control program marks the electrodes used for power supply and records the time interval t from when they are used for power supply to when they are used for signal measurement. In the process of completing a full data acquisition, each electrode will only participate in power supply once, and the power supply duration is fixed, but each electrode may participate in signal measurement multiple times. Each time an electrode participates in signal measurement, if it has already been marked as a power supply electrode, the time interval t from when it is used for power supply to when it is used for signal measurement needs to be updated.

[0067] When performing signal measurements, determine whether the electrode involved in the measurement is marked as the power supply electrode. If not, polarization effect correction is not required; if so, perform correction as follows:

[0068] (1) When performing a unipolar measurement, the current electrode is denoted as M, and the U obtained in step 3 is used as the reference. 极化 =f(t) Calculate the polarization potential difference of electrode M The polarization effect correction formula is as follows:

[0069]

[0070] In the formula, U 测量 Indicates measurement data; U 校正 This represents the corrected measurement data; α represents the correction coefficient of the electrode, obtained from step 1.

[0071] (2) When performing dipole measurements, the electrode closer to the positive terminal of the power supply is denoted as M, and the electrode closer to the negative terminal is denoted as N. According to U... 极化 =f(t) Calculate the polarization potential difference between electrodes M and N respectively. and If only one electrode is used as the over-supply electrode, the polarization potential difference of the other electrode is 0; the polarization effect correction formula is as follows:

[0072]

[0073] The above technical solution utilizes the polarization potential difference decay curve of the power supply electrode to correct the polarization effect, which can effectively eliminate the influence of electrode polarization effect and is a universal correction method.

[0074] When adjacent electrodes participate in power supply at similar times, the polarization potential difference can be canceled out by recombining the measurement data of adjacent electrodes, thus achieving polarization effect correction of the power supply electrodes. Since the electrode materials used in the data acquisition process are the same, the impact of polarization effect on different electrodes is theoretically consistent. The difference in polarization potential difference between different electrodes is mainly caused by different decay times. When adjacent electrodes participate in power supply at similar times, the difference in their decay times is small, and the difference in polarization potential difference is also relatively small. In this case, the polarization potential difference can be canceled out by recombining the measurement data of adjacent electrodes. The specific technical solution is as follows:

[0075] (1) When all electrodes are supplied with power in sequence, the monopole-to-monopole observation device measures the potential difference of a certain electrode relative to the electrode at infinity. The electrode at infinity at the measurement end is generally not supplied with power. Therefore, the polarization effect of the power supply electrode has a significant impact on the monopole-to-monopole measurement data. The technical scheme for correcting the polarization effect of the power supply electrode in the monopole-to-monopole observation device is as follows:

[0076] A. When using a monopole-monopole observation device for measurement, the influence of electrode polarization effect can be reduced by extracting monopole-dipole observation data. The monopole-monopole measurement data is denoted as U. 单极 (i), where i is the electrode number, i = 1, 2, 3, ..., N; N is the total number of electrodes. The measurement data includes the true potential difference and the polarization potential difference, i.e., U 单极 (i)=U 真实 (i)+αu 极化 (i), where α is the correction coefficient; the formula for extracting unipolar-dipole data is as follows:

[0077] U 偶极 (i)=U 单极 (i+1)-U 单极 (i)≈U 真实 (i+1)-U 真实 (i) (i = 1, 2, 3, ..., N-1)

[0078] The above formula applies to U 极化 (i+1)≈U 极化 (i) Correction for power supply electrode polarization effect in time-to-time single-pole observation data.

[0079] B. When using a monopole-monopole observation device for measurement, the influence of electrode polarization effect can be reduced by extracting dipole-dipole observation data. The monopole measurement data corresponding to two different power supply electrodes are respectively recorded as follows: and The formula for extracting dipole-dipole data is as follows:

[0080]

[0081] i = 1, 2, 3, ..., N-1.

[0082] The above formula applies to U 极化 (i+1)≈U 极化 (i) Correction for power supply electrode polarization effect in time-to-time single-pole observation data.

[0083] When all electrodes participate in power supply sequentially, and the timing of power supply for adjacent electrodes is relatively close, the polarization potential difference between adjacent electrodes is basically canceled out during the acquisition process because the monopole-dipole and dipole-dipole observation devices measure the potential difference between adjacent electrodes. Therefore, the polarization effect of the power supply electrode has a relatively small impact on the monopole-dipole and dipole-dipole measurement data. When dipole measurement is performed directly using exploration equipment, the influence of electrode polarization effect can be ignored.

[0084] (2) When power is supplied across electrodes and all electrodes participate in the measurement, the polarization effect of the power supply electrodes can cause a sawtooth-like anomaly in the measurement curve for different observation devices. In this case, the influence of the electrode polarization effect can be eliminated by averaging the superposition of adjacent observation data. Since monopole-dipole and dipole-dipole observation data can be obtained by superimposing adjacent electrode observation data on the basis of monopole-monopole observation data, the steps for correcting the polarization effect of the power supply electrodes when powering across electrodes are explained here, taking the case of power supply using only electrodes with odd numbers as an example, based on monopole-monopole observation data:

[0085] The measurement data of the odd-numbered electrodes are denoted as U. 测量 (i1) (i1 is an odd number, i1 = 1, 3, 5, ...), the measurement data of the even-numbered electrodes are denoted as U. 测量 (i2) (i2 is an even-numbered electrode, i2 = i1 + 1); odd-numbered electrodes participate in power supply, U 测量 (i1)=U 真实 (i1)+αU 极化 (i1); Even-numbered electrodes do not participate in power supply, U 测量 (i2)=U 真实 (i2).

[0086] The formula for extracting unipolar-dipole observation data is as follows:

[0087] U 偶极 (i1)=U 测量 (i2)-U 测量 (i1)=U 真实 (i2)-U 真实 (i1)-αU 极化 (i1)

[0088] U 偶极 (i2)=U 测量 (i1+2)-U 测量 (i2)=U 真实 (i1+2)-U 真实 (i2)+αU 极化 (i1+2)

[0089] (i1=1, 3, 5,...; i2=i1+1)

[0090] When U 极化 (i1)≈U 极化 When (i1+2) (i1=1, 3, 5, ……), the formula for correcting the polarization effect of the power supply electrode is as follows:

[0091]

[0092]

[0093]

[0094]

[0095] The above-described formula for correcting the polarization effect of power supply electrodes in monopole-monopole observation data when using only odd-numbered electrodes can be extended to the correction of electrode polarization effects in other forms of cross-electrode power supply, and can be further extended to the correction of the polarization effect of power supply electrodes in monopole-dipole and dipole-dipole observation data when using cross-electrode power supply. The beneficial effects of this invention are: by correcting the polarization effect of power supply electrodes through data processing methods, the influence of the polarization effect can be effectively eliminated, improving the quality of exploration / monitoring data and laying a data foundation for high-precision interpretation of electrical exploration results; this invention does not require special process improvements to the electrodes, reducing electrode manufacturing costs; this invention does not require replanning the electrode arrangement order through complex algorithms, improving electrode utilization efficiency; this invention fully considers the correction of power supply electrode polarization effects under different usage conditions, different observation devices, and different observation methods, and the method has universality.

[0096] In this embodiment, an engineering test of downhole electrical resistivity tomography was carried out. Electrofluoroscopy observation method and monopole-dipole observation device were used to collect monitoring data. The monitoring electrode material was stainless steel.

[0097] An electroluminescence (EMT) monitoring system was deployed at the test working face, with one measuring line arranged on the floor of the transport roadway (electrode numbers 1-60) and another on the floor of the return airway (electrode numbers 61-120). EMT collected the potential difference signal penetrating the working face. During data acquisition, the transport roadway electrode was first used for power supply, while the return airway electrode was used for signal measurement. After the transport roadway electrode completed one round of power supply, the return airway electrode was then used for power supply, and the transport roadway electrode was used for signal measurement. After each electrode in both roadways completed one round of power supply, a complete set of monitoring data was obtained. Due to hardware limitations, only odd-numbered electrodes could participate in power supply during the data acquisition process; all electrodes could be used for signal measurement. During data acquisition, odd-numbered electrodes participated in power supply sequentially in ascending order of their numbers; the electrodes used for measurement measured signals sequentially in ascending order of their numbers.

[0098] Figure 2 The figure shows the potential difference curves obtained by powering electrode 3 and measuring electrodes 61 to 120 at different time periods (data IDs: 20220315-001, 20220315-002, 20220315-012, 20220315-013). The original potential difference curves show a sawtooth shape of "low-high-low-high...", and the measured data are obviously affected by the polarization potential difference of the power supply electrode.

[0099] To correct the polarization effect of the power supply electrode, the polarization effect of the stainless steel electrode was measured experimentally on the ground.

[0100] First, the correction coefficient of the stainless steel electrode was determined experimentally. The specific steps are as follows:

[0101] Experimental data were measured using a single-pole-single-pole observation device; the electrode to be tested was designated as electrode 1, and the material of electrode 1 was stainless steel; three auxiliary electrodes were prepared and designated as electrode 2, electrode 3, and electrode 4, respectively, and the material of the auxiliary electrodes was the same as that of electrode 1.

[0102] Following the single-electrode transmission and single-electrode reception mode, electrode 1 is installed at the position of the measuring electrode, and electrode 3 is installed at the position of the transmitting electrode, with a distance of about 100m between electrodes 1 and 3; electrodes 2 and 4 are arranged as infinity electrodes at a distance of more than 100km, with sufficient distance between electrodes 2 and 4.

[0103] Electrodes 1 and 2 form a measurement circuit, and electrodes 3 and 4 form a power supply circuit. Power is supplied to the power supply circuit formed by electrodes 3 and 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal. The power supply current is kept stable, and the power supply current and duration are consistent with those of the downhole monitoring equipment. The potential difference is measured using the measurement circuit formed by electrodes 1 and 2, and the measured value is recorded as U0. This measured value is the value before electrode 1 is polarized.

[0104] Replace electrode 3 with electrode 1 and install it at the transmitting electrode position to form a power supply circuit between electrodes 1 and 4. Power the power supply circuit formed by electrodes 1 and 4, with electrode 1 connected to the positive terminal and electrode 4 connected to the negative terminal. Keep the power supply current stable, and keep the power supply current and power supply duration consistent with the downhole monitoring equipment. At this time, no measurement is required; polarization of electrode 1 is achieved simply by powering it.

[0105] Reinstall electrode 1 back to its original measuring electrode position, and reinstall electrode 3 back to its original transmitting electrode position; electrodes 1 and 2 form a measuring circuit, and electrodes 3 and 4 form a power supply circuit; supply power to the power supply circuit formed by electrodes 3 and 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the downhole monitoring equipment; measure the potential difference using the measuring circuit formed by electrodes 1 and 2, and record the measured value as U1. This measured value is the value after electrode 1 is polarized.

[0106] Define a correction coefficient α; compare the magnitudes of U1 and U0. If U1 > U0, α = 1; if U1 > U0, α = 1. <U0,α=-1。

[0107] Further experimental determination of the polarization potential difference decay curve of the stainless steel electrode was conducted, with the specific steps as follows:

[0108] Remove electrode 1 and allow it to stand for a sufficient period of time until the polarization potential difference between its two ends drops to 0. Re-polarize electrode 1, ensuring the power supply current and duration are consistent with the downhole monitoring equipment. Record the moment of power failure as t0. Continuously measure the polarization potential difference between the two ends of electrode 1 using a potential difference measuring device, and record the measurement time t. i and measured values Let t = t i -t0, with time t as the x-axis, polarization potential difference Plot the polarization potential difference decay curve over time on the ordinate.

[0109] Based on the changing characteristics of the polarization potential difference decay curve, a suitable fitting formula is selected, and the functional relationship U between polarization potential difference and time is obtained through curve fitting.极化 =f(t), the polarization potential difference of the power supply electrode at any time after power is cut off can be calculated through this function expression.

[0110] The polarization potential difference decay curve of the stainless steel electrode shows that the polarization potential difference decays rapidly in the early stage, and then the decay rate slows down after a period of time. In this embodiment, the downhole electrical monitoring engineering test uses electrofluorometry to collect monitoring data. The time interval between when the electrode is used for power supply and when it is used for signal measurement exceeds 1 hour, during which time the polarization potential difference has entered the slow decay period.

[0111] Since the electrode materials used in the data acquisition process are the same, the polarization effect on different electrodes is theoretically consistent. The difference in polarization potential difference between different electrodes is mainly caused by the different decay times. When adjacent electrodes participate in power supply at similar times, the difference in their decay times is small, and the difference in polarization potential difference is also relatively small. In this case, the polarization potential difference can be canceled out by recombining the measurement data of adjacent electrodes.

[0112] In this embodiment, during the acquisition of downhole test data, the time when adjacent electrodes participate in power supply is relatively close, and the polarization potential difference between adjacent electrodes is also relatively close. Therefore, the polarization potential difference can be canceled by recombining the measurement data of adjacent electrodes, thereby realizing the correction of the polarization effect of the power supply electrode.

[0113] In this embodiment, a monopole-dipole device is used for monitoring data acquisition. During the acquisition process, only electrodes numbered odd are used for power supply. The polarization effect of the power supply electrodes causes a sawtooth-shaped anomaly in the measurement curve (as shown in the attached figure). Figure 2 As shown in the figure, the influence of electrode polarization effect can be eliminated by superimposing and averaging nearby observation data. The specific technical solution is as follows:

[0114] Monopole-dipole observation data can be obtained by superimposing adjacent electrode observation data on monopole-monopole observation data. Here, based on monopole-monopole observation data, the steps for correcting electrode polarization effects when using only odd-numbered electrodes for power supply are explained as follows:

[0115] The measurement data of the odd-numbered electrodes are denoted as U. 测量 (i1) (i1 is an odd number, i1 = 1, 3, 5, ...), the measurement data of the even-numbered electrodes are denoted as U. 测量 (i2) (i2 is an even-numbered electrode, i2 = i1 + 1); odd-numbered electrodes participate in power supply, U 测量 (i1)=U 真实 (i1)+αU 极化 (i1); Even-numbered electrodes do not participate in power supply, U 测量 (i2)=U 真实 (i2).

[0116] The formula for extracting unipolar-dipole observation data is as follows:

[0117] U 偶极 (i1)=U 测量 (i2)-U 测量 (i1)=U 真实 (i2)-U 真实 (i1)-αU 极化 (i1)

[0118] U 偶极 (i2)=U 测量 (i1+2)-U 测量 (i2)=U 真实 (i1+2)-U 真实 (i2)+αU 极化 (i1+2)

[0119] (i1=1, 3, 5,...; i2=i1+1)

[0120] When U 极化 (i1)≈U 极化 When (i1+2) (i1=1, 3, 5, ……), the formula for correcting the polarization effect of the power supply electrode is as follows:

[0121]

[0122]

[0123]

[0124]

[0125] After correction of the polarization effect of the power supply electrode, the sawtooth anomaly caused by the polarization of the power supply electrode was effectively suppressed.

[0126] This embodiment corrects the polarization effect of the power supply electrode through data processing, effectively eliminating its influence and improving the quality of monitoring data. This lays a data foundation for high-precision interpretation of electrical exploration results. This embodiment eliminates the need for special process modifications to the electrodes, reducing manufacturing costs; simultaneously, it avoids the need for complex algorithms to re-plan the electrode arrangement, improving electrode utilization efficiency.

Claims

1. A method for testing the calibration coefficient of an electrode, characterized in that, Specifically, the steps include the following: Step 11: Use a single-pole-single-pole observation device to measure experimental data; designate the electrode to be tested as electrode 1. The material of electrode 1 can be conductive materials such as stainless steel, copper, or graphite, depending on the requirements; prepare 3 auxiliary electrodes, designated as electrode 2, electrode 3, and electrode 4 respectively. The material of the auxiliary electrodes should be the same as that of electrode 1. Step 12: Following the unipolar transmission and unipolar reception mode, install electrode 1 at the position of the measuring electrode and electrode 3 at the position of the transmitting electrode, with a distance of about 100m between electrodes 1 and 3; use electrodes 2 and 4 as infinity electrodes. Step 13: Electrode 1 and electrode 2 form a measurement circuit, and electrode 3 and electrode 4 form a power supply circuit; power is supplied to the power supply circuit formed by electrode 3 and electrode 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; the power supply current is kept stable, and the power supply current and power supply duration are consistent with the actual exploration equipment; the potential difference is measured using the measurement circuit formed by electrode 1 and electrode 2, and the measured value is recorded as U0. The measured value at this time is the measured value before electrode 1 is polarized; Step 14, polarize the No. 1 battery: Replace the No. 3 electrode with the No. 1 electrode and install it at the emitter electrode position, so that the No. 1 and No. 4 electrodes form a power supply circuit; supply power to the power supply circuit formed by the No. 1 and No. 4 electrodes, with the No. 1 electrode connected to the positive terminal of the power supply and the No. 4 electrode connected to the negative terminal of the power supply; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; at this time, the polarization of the No. 1 electrode is achieved by supplying power to the No. 1 electrode; Step 15: Reinstall electrode 1 back to its original measuring electrode position and electrode 3 back to its original emitting electrode position; electrodes 1 and 2 form a measuring circuit, and electrodes 3 and 4 form a power supply circuit; supply power to the power supply circuit formed by electrodes 3 and 4, with electrode 3 connected to the positive terminal and electrode 4 connected to the negative terminal; keep the power supply current stable, and keep the power supply current and power supply duration consistent with the actual exploration equipment; measure the potential difference using the measuring circuit formed by electrodes 1 and 2, and record the measured value as U1. This measured value is the value after electrode 1 is polarized; Step 16, define the correction coefficient α; compare the magnitudes of U1 and U0. If U1 > U0, α = 1; if U1 > U0, α = 1. <U0,α=-1。 2. A method for correcting the polarization effect of a power supply electrode, characterized in that, Specifically, the steps include the following: Step 1: Obtain the correction coefficient of the electrode under test using the electrode correction coefficient test method described in claim 1; Step 2: Experimentally determine the attenuation curve of the polarization potential difference of the electrode; Step 3: Based on the variation characteristics of the polarization potential difference decay curve obtained in Step 2, select a suitable fitting formula and obtain the functional relationship U between polarization potential difference and time through curve fitting. 极化 =f(); This function expression can calculate the polarization potential difference of a power supply electrode made of the same material as the electrode being tested at any time after power is turned off; Step 4, use the functional relationship U obtained in step 3 极化 =f(t) corrects the polarization effect of the power supply electrode, which is made of the same material as the electrode being tested. The specific steps are as follows: During the acquisition of electrical detection / monitoring data, the electrodes used for power supply are marked, and the time interval t from when they are used for power supply to when they are used for signal measurement is recorded. During the completion of a complete data acquisition, each time an electrode participates in signal measurement, if it has been marked as a power supply electrode, the time interval t from when it is used for power supply to when it is used for signal measurement must be updated. When performing signal measurements, determine whether the electrode involved in the measurement is marked as the power supply electrode. If not, polarization effect correction is not required; if so, perform correction as follows: (1) When performing a unipolar measurement, the current electrode is denoted as M, and the U obtained in step 3 is used as the reference. 极化 =f(t) Calculate the polarization potential difference of electrode M The polarization effect correction formula is as follows: In the formula, U 测量 Indicates measurement data; U 校正 This represents the corrected measurement data; α represents the correction coefficient for the electrode. (2) When performing dipole measurements, the electrode closer to the positive terminal of the power supply is denoted as M, and the electrode closer to the negative terminal is denoted as N. According to U... 极化 =f(t) Calculate the polarization potential difference between electrodes M and N respectively. and If only one electrode is used as the over-supply electrode, the polarization potential difference of the other electrode is 0; the polarization effect correction formula is as follows:

3. The power supply electrode polarization effect correction method as described in claim 2, characterized in that, Step 2 includes the following operations: Remove electrode 1 and allow it to stand for a sufficient period of time until the polarization potential difference between its two ends drops to 0. Re-polarize electrode 1 with electricity, then stop the power supply and record the moment of power failure as t0. Continuously measure the polarization potential difference between the two ends of electrode 1 using a potential difference measuring device and record the measurement time t. i and measured values Let t = t i -t0, with time t as the x-axis, polarization potential difference Plot the polarization potential difference decay curve over time on the ordinate.

4. A method for correcting the polarization effect of the power supply electrode in a monopole-to-monopole observation device, characterized in that, Includes the following steps: Step 1: If all electrodes are sequentially powered, proceed to either Step 2 or Step 3; if power is supplied across electrodes and all electrodes are involved in the measurement, proceed to Step 4. Step 2, record the unipolar-to-unipolar measurement data as U 单极 (i), where i is the electrode number, i = 1, 2, 3, ..., N; N is the total number of electrodes. The measurement data includes the true potential difference and the polarization potential difference, i.e., U 单极 (i)=U 真实 (i)+αI 极化 (i) α is the correction coefficient, which is measured by the electrode correction coefficient test method described in claim 1; the unipolar-dipole observation data are extracted using the following formula: U 偶极 (i)= 单极 (i+1)- 单极 (i)≈U 真实 (i+1)- 真实 (i)(i=1,2,3,……,N-1); Step 3, record the unipolar measurement data corresponding to the two different power supply electrodes as follows: and The following formula is used to extract dipole-dipole observation data: Step 4, record the measurement data of the odd-numbered electrodes as U. 测量 (i1), where i1 is an odd-numbered electrode, i1 = 1, 3, 5, ... The measurement data of the even-numbered electrodes are denoted as U. 测量 (i2), i2 is an even-numbered electrode, i2 = i1 + 1; odd-numbered electrodes participate in power supply, U 测量 (i1)= 真实 (i1)+U 极化 (i1); Even-numbered electrodes do not participate in power supply, U 测量 (i2)= 真实 (i2); The formula for extracting unipolar-dipole observation data is as follows: IN 偶极 (i1)= 测量 (i2)- 测量 (i1)= 真实 (i2)- 真实 (i1)- 极化 (i1) IN 偶极 (i2)= 测量 (i1+2)- 测量 (i2)= 真实 (i1+2)- 真实 (i2)+ 极化 (i1+2), i1=1,3,5,…;i2=i1+1 When U 极化 (i1)≈U 极化 When (i1+2), i1=1, 3, 5, ……, the formula for correcting the polarization effect of the power supply electrode is as follows:

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