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CN-115826066-B - Quality control flow for monitoring data by underground direct current method

CN115826066BCN 115826066 BCN115826066 BCN 115826066BCN-115826066-B

Abstract

The invention discloses a quality control flow for underground direct current method monitoring data, which comprises the steps of 1, using a single transmitting electrode as a group of evaluation units to evaluate the size and stability of transmitting current, removing unqualified data, 2, carrying out Fourier transformation on full waveform data of each measuring point, calculating the signal to noise ratio of the data of each measuring point, and removing the unqualified measuring point data, 3, directly entering into the step 4 if the ratio of the measuring points of the single group of evaluation units is kept small after the step 2, otherwise, forming an actual measurement curve for each measuring point data, evaluating the stability of the data from space, then entering the monitoring data processed in the step 2 into the step 4, repeatedly executing the steps 1-3 to obtain the monitoring data of a plurality of substations, and 5, using the single measuring point as the evaluation unit, calculating the relative mean square error of each measuring point, and evaluating the stability of the data from time. The invention can reflect the noise interference level relatively comprehensively and provides a reliable basis for the subsequent electrical data processing.

Inventors

  • YUAN BO
  • CUI WEIXIONG
  • LU JINGJIN
  • WANG BINGCHUN
  • CONG LIN
  • WANG PAN
  • Nan Hanchen
  • YAN WENCHAO

Assignees

  • 中煤科工西安研究院(集团)有限公司

Dates

Publication Date
20260508
Application Date
20221115

Claims (10)

  1. 1. The quality control flow for monitoring data by a downhole direct current method is characterized by comprising the following steps of: Step 1, evaluating emission current, namely selecting single substation monitoring data, presetting a maximum threshold value and a minimum threshold value of the emission current, taking the single emission electrode as a group of evaluation units, evaluating the magnitude and stability of the emission current of the group of evaluation units, removing unqualified data after all evaluation is completed, and enabling the qualified data to enter the next step; The maximum threshold I max of the emission current is the maximum emission current which can be achieved by the monitoring instrument, the minimum threshold I min is estimated through a field test in the layout stage of the monitoring system, the field test result is set according to experience when not ideal, when the emission current exceeds the threshold, potential or potential difference data corresponding to unqualified measuring points in the group of evaluation units are removed, and the equation for estimating I min through the field test is as follows: Wherein, I min is the minimum threshold value of the emission current, A min is the minimum signal which can be distinguished by a monitoring instrument, I s is the emission current of a field test, A smin is the minimum potential or potential difference received by each measuring point of the field test; Step 2, evaluating the noise level of original data, namely performing Fourier transform on the full waveform data of each measuring point to obtain frequency spectrums with different frequencies aiming at the monitoring data of the current substation processed in the step 1, further calculating the signal-to-noise ratio SNR of the data of each measuring point, evaluating the noise level of the original monitoring data of different measuring points one by one, removing potential or potential difference data corresponding to unqualified measuring points in the group of evaluation units, and enabling the qualified data to enter the next step; Step 3, evaluating the data stability from space, namely aiming at the monitoring data of the current substation processed in the step 2, taking a single transmitting electrode as a group of evaluation units, if the measurement points of the single group of evaluation units are kept small in the ratio after the step 2, directly entering the step 4, otherwise, forming an actual measurement curve by the potential V i or the potential difference DeltaV i of each measurement point, taking the single transmitting electrode as a group of evaluation units, evaluating the data stability from space, and then entering the monitoring data of the current substation processed in the step 2 into the step 4; step 4, repeatedly executing the steps 1-3 to obtain monitoring data of a plurality of substations; And 5, evaluating the data stability in time, namely selecting monitoring data of a plurality of substations adjacent in acquisition time in a certain time period from the monitoring data obtained in the step 4, drawing a potential or potential difference change curve of the monitoring data of the single measuring point along with time by taking the single measuring point as an evaluation unit, calculating the relative mean square error of each measuring point, and evaluating the data stability in time according to the relative mean square error.
  2. 2. The quality control flow for monitoring data by a downhole direct current method according to claim 1, wherein in the step1, the stability of the emission current is evaluated by the relative mean square error of the emission currents of the set of evaluation units, and if the stability is higher than the relative mean square error threshold, the emission current is considered to be unstable, and all data corresponding to the set of evaluation units are removed, wherein the calculation formula is as follows: Wherein m I is the relative mean square error of the group of emission currents, n is the number of the measurement points corresponding to the selected emission electrodes, I j is the emission current data of a single measurement point, The average value of the emission current data of n measuring points is obtained.
  3. 3. The quality control scheme for downhole dc monitoring data according to claim 1 or 2, wherein the emission current is 5% relative to the mean square error threshold.
  4. 4. The quality control flow for downhole dc monitoring data according to claim 1, wherein in the step 2, a signal-to-noise ratio calculation formula of the measurement point is as follows: Wherein V signal is the frequency spectrum of the transmitting frequency obtained by carrying out Fourier transform on the full waveform data, V noise is the frequency spectrum of the noise of the frequency band around the transmitting frequency obtained by carrying out Fourier transform on the full waveform data, and the frequency band around the transmitting frequency is the frequency band with a certain bandwidth taking the transmitting frequency as the center.
  5. 5. The flow of quality control for downhole dc monitoring data of claim 4, wherein the bandwidth of the frequency band around the transmit frequency is determined according to the sampling frequency and the sampling duration, and the signal-to-noise ratio threshold of the data is set to be not lower than 10dB.
  6. 6. The quality control flow for downhole dc monitoring data according to claim 1, wherein in the step 3, the measurement points of the single set of evaluation units are considered smaller when the retention ratio after the step 2 is smaller than a threshold value, and the threshold value can be set to be in a range of 60% -80%.
  7. 7. The quality control flow for monitoring data by a downhole direct current method according to claim 1, wherein in the step 5, the monitoring data of a plurality of sub-stations with adjacent acquisition time in a certain period of time is monitoring data under the same downhole production environment condition in 24 hours or 48 hours.
  8. 8. The quality control flow for monitoring data by a downhole direct current method according to claim 1, wherein in the step 5, the monitoring data under the same downhole production environment condition, namely, the data of the production shift and the maintenance shift are distinguished, and the period of time should not be the downhole production in part and the period of time should be the downhole shutdown in part.
  9. 9. The quality control flow for downhole dc monitoring data according to claim 1, wherein in the step 5, the calculation formula of the potential or potential difference of the single measuring point relative to the mean square error is: Wherein m s is the relative mean square error of the potential or potential difference of a single measuring point, n is the number of the selected substations, S i is the potential or potential difference monitoring data of the single substations, The data average is monitored for the potential or potential difference of n substations.
  10. 10. The quality control flow for downhole DC method monitoring data of claim 9, wherein the potential or potential difference of a single measurement point is 5% -10% of the mean square error threshold value.

Description

Quality control flow for monitoring data by underground direct current method Technical Field The invention relates to the technical field of underground direct current method monitoring, in particular to a quality control flow aiming at underground direct current method monitoring data. Background The water damage of the coal mine is one of the geological problems seriously affecting the safe stoping of the coal face, and the real-time dynamic monitoring of the hidden danger of the water damage and the evaluation of the risk of the water damage are needed urgently for the coal mine. The direct current method monitoring in the coal mine can find out the damage of the top and bottom plates of the coal face and the dynamic development process of the water guide channel in the mining process, realize the aim of evaluating the risk of water damage in the stoping process of the coal face, timely take control measures for preventing the water damage occurrence risk of the coal mine, provide accurate and reliable technical basis, and have extremely important significance for solving the problems of coal mine safety production and water damage occurrence, thereby achieving the aims of saving the cost of manpower and material resources, guaranteeing the safety stoping and improving the economic benefit. The underground direct current method monitoring has the advantages of automation, intellectualization, all-weather, full-waveform uninterrupted data acquisition and the like, but the unique electromagnetic field environment in the coal mine also increases the difficulty of the underground direct current method monitoring effective signal acquisition. Compared with the ground direct current method, the method has the advantages that the electromagnetic noise is complex in type, extremely high in intensity and greatly different along with the change of the space position in the underground monitoring process, and the adverse conditions of limitation of underground safety production on emission current, limitation of underground narrow space on electrode arrangement and the like can cause relatively weaker effective signals to be collected. Compared with underground direct current method detection, continuous and uninterrupted observation is needed for monitoring, the underground normal mining production activities cannot be avoided, and a large amount of monitoring data are easily influenced by strong electromagnetic noise. Therefore, the original data monitored by the underground direct current method needs to be managed and evaluated, so that the finally collected data meets the requirements of the subsequent direct current method for monitoring data processing and interpretation on the quality of the original data. Three methods for data management and control of the current direct current method are common. The first method is to perform data quality control by sampling the measuring points one by one, the principle is that random noise which is stable and meets Gaussian distribution can be suppressed by adopting a mathematical statistics method, and the method has the advantages that the data quality can be improved by arithmetic average, and the data quality of the measuring points can be evaluated one by relative mean square error. The more sampling times, the higher the improvement of the data quality, and the more accurate the management and evaluation. However, the method has the same disadvantages that firstly, the required acquisition time is long, the working efficiency is reduced, and the excessive sampling points can cause pressure on the storage space of the instrument due to the full waveform data acquisition mode, and secondly, the data quantity is lost to a certain extent. The second is to control the data quality of the original data by the system detection mode, according to the "coal electric prospecting procedure" (MT/T898-2000), the arithmetic average relative error is used as the result of evaluating the single measuring point system detection, the mean square relative error is used as the result of evaluating the detecting point (section) system detection, and the arithmetic average of the mean square relative error values of each detecting point (section) is used as the result of evaluating the whole area system detection. The disadvantage of this method is that the detection and original detection of the detection point should generally be performed by different operators at different times using different instruments, and the number of points to be paid out again should not be less than 2/3 of the total number of detection points. The requirements are incompatible with the characteristics of automation, intellectualization and uninterrupted data acquisition of the underground direct current method, and are difficult to meet in practical work. Thirdly, the original data is subjected to data quality control through survey line curve rating, the method is quite common in various electromagnet