Method for identifying shallow pore fissure water flow field based on two-dimensional synchronous flow potential

Abstract

The application discloses a shallow pore fissure water flow field identification method based on two-dimensional synchronous flow potential, relates to hydrogeological exploration technology, and is used for identifying a shallow pore fissure water dominant flow direction under a salt water disturbance condition and comprises the following steps: acquiring data of a measurement area and selecting a salt water disturbance source; arranging an electrode array and a reference electrode with the salt water disturbance source as a center; synchronously collecting background potential sequences and response potential sequences of each measurement point relative to the reference electrode before and after salt water injection; calculating differential flow potential responses of each measurement point, eliminating abnormal data points to construct a purified differential sequence; performing sliding average denoising processing on the purified differential sequence to extract response data of each measurement point; and outputting a dominant flow field candidate direction, an apparent salt water disturbance response migration speed, a direction credibility and a potential response intensity map. The application eliminates time splicing errors through two-dimensional synchronous collection and differential processing before and after disturbance, and improves the reliability of the shallow pore fissure water dominant flow direction identification under the salt water disturbance condition.

Description

Technical Field

[0001] This invention relates to the field of hydrogeological exploration technology, and more particularly to the field of groundwater seepage monitoring technology, specifically a method for identifying shallow pore and fissure water flow fields based on two-dimensional synchronous flow potential. Background Technology

[0002] Groundwater flow direction and dominant water-conducting channels are important parameters in mine water hazard prevention, pollution migration assessment, engineering leakage diagnosis, and shallow hydrogeological evaluation. Traditional pumping tests, tracer tests, and borehole water level observations can obtain relatively reliable hydrogeological information, but they usually require drilling, sampling, long-term observation, or a large amount of fieldwork.

[0003] Flow potential is an electrical signal generated by the electrochemical interaction at the water-rock or water-soil interface when groundwater or pore water flows in a porous medium. This signal responds to seepage, water content, and pressure gradients, and can be used to identify groundwater flow, seepage channels, and water content anomalies. Flow potential is simultaneously affected by factors such as temperature, water content, medium properties, grounding status of the measuring point, and external electromagnetic interference; interpreting it solely based on the potential contour lines at a single moment can easily lead to multiple interpretations.

[0004] Current methods for measuring spontaneous potential or flowing potential often employ point-by-point measurements using a fixed reference electrode (also known as a reference electrode) and a moving measuring electrode, or time-division measurements along a measuring line followed by interpolation to obtain a two-dimensional potential map. While this method is usable in static sites, it becomes problematic under conditions of saline disturbance such as water injection, saline injection, rainfall infiltration, drainage, or ditch leakage. If measurements are not collected at the same time at different measuring points, the two-dimensional potential map is essentially a patchwork of data from different moments, easily leading to misinterpretation of temporal variations as spatial differences.

[0005] Therefore, there is an urgent need for a two-dimensional synchronous flow potential monitoring method for saline water disturbance conditions. This method does not rely on static potential mosaics formed by point-by-point measurements, but instead continuously acquires the dynamic response of multiple measurement points under a unified time reference, and uses the response arrival time, response amplitude, propagation relationship between internal and external arrays, and spatial continuity to identify the dominant response direction of shallow pore-fracture water. Summary of the Invention

[0006] The purpose of this invention is to provide a method for identifying shallow pore and fissure water flow fields based on two-dimensional synchronous flow potential, so as to solve the problems in the prior art where point-by-point potential measurement has time splicing errors under salt water disturbance conditions, and the potential contour lines at a single moment are difficult to reflect the disturbance response process.

[0007] To address the above objectives, this invention provides a method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential, comprising: S1. Obtain the data of the survey area, select the brine disturbance source according to the data of the survey area, and take the brine injection start time as the time zero point reference. S2. An electrode array is deployed on the ground with the brine disturbance source as the center, and a reference electrode is deployed at the potential stable location. S3. Before brine injection, the background potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. After brine injection, the response potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. S4. Based on the background potential sequence and the response potential sequence, calculate the differential flow potential response of each measuring point before and after the brine disturbance, remove abnormal data points, and construct the purification differential sequence. S5. Perform moving average noise reduction on the purified differential sequence and extract the response data of each measurement point; S6. Based on the response data of each measuring point extracted in S5, a score is obtained by comprehensively considering the arrival time of the response in each direction, the magnitude of the response, the effectiveness of the apparent disturbance response migration speed, and the spatial continuity of the response characteristics of adjacent directions. The brine disturbance score is obtained. Based on the brine disturbance score, the dominant response direction of the shallow pore fracture water flow field is determined, and the candidate dominant flow field direction, apparent brine disturbance response migration speed, direction confidence, and potential response intensity map are output.

[0008] The S1 measurement area data includes the boundary of the area to be measured, the location of saltwater disturbance sources, the location of existing wells, ditches, drainage points, water outlets, water injection points, and the surface area where electrodes can be deployed. Sources of brine disturbance include wells, injection points, and infiltration points in ditches; After selecting the brine disturbance source, record the brine concentration, injection volume, injection flow rate, start time, and duration of the brine disturbance source.

[0009] Electrode arrays include circular arrays, concentric circle arrays, linear measuring line arrays, and grid arrays; The reference electrode is positioned far from the area affected by brine disturbance and where the potential is relatively stable. When using an inner and outer concentric circle array, the inner circle radius is... The outer radius is The inner and outer circular measuring points in the same orientation constitute a response propagation identification pair, which is used to calculate the apparent disturbance response migration velocity.

[0010] In S4, the differential flow potential response is: ; In the formula, Indicates the first Each measuring point at time... The measured potential, Indicates the first Each measuring point during the background period The average electric potential inside, This represents the differential flow potential response relative to the background value after a disturbance.

[0011] The response data in S5 includes the response arrival time, peak response amplitude, average response amplitude, response polarity, and response duration for each measurement point. The response arrival time is the earliest time when the differential flow potential response, after smoothing, continuously exceeds the background noise threshold.

[0012] The background noise threshold is: ; ; ; In the formula, Indicates the first Minimum response threshold for each measurement point Indicates the first The standard deviation of the potential at each measuring point during the background period before the disturbance. Indicates the threshold multiple. For the first The response arrival time of each measuring point This represents the analysis time window after saline disturbance. Indicates the first time window within the analysis time window Each sampling time, Indicates the offset. This represents the number of consecutive sampling points exceeding the threshold required to determine a valid response. Indicates the first The measuring point at the ... The smoothed differential potential at each sampling time, Indicates the first Each measuring point at time... The differential potential, For the first The average response amplitude at each measuring point The number of consecutive sampling points exceeding a threshold is required to determine a valid response. This represents the number of valid sampling points within the statistical time window of the average response amplitude.

[0013] When the electrode array uses an inner and outer concentric circle array, the response migration speed is: ; ; In the formula, It is the azimuth angle. Azimuth The response arrival time of the measuring point on the outer circle, Azimuth The arrival time of the response at the upper inner circle measuring point.

[0014] Based on the response data of each measuring point extracted by S5, the response arrival time and response amplitude of each direction are weighted and scored. The effectiveness of the apparent disturbance response migration speed is used as the pre-screening condition for the scoring results, and the spatial continuity of the response characteristics of adjacent directions is used as the post-validation condition for the rationality of the scoring results. The dominant response direction of the shallow pore fracture water flow field is determined, and the candidate directions of the dominant flow field, the apparent brine disturbance response migration speed, the direction confidence and the potential response intensity map are output. ; In the formula, Indicates azimuth angle The normalized response arrival time metric Azimuth The average response amplitude normalization index, , They represent , The weighting coefficients.

[0015] The response arrival time index is calculated based on the principle that the earlier the response, the larger the value. The response amplitude index is calculated based on the principle that the larger the average absolute value of the differential current potential, the larger the value. The spatial continuity index is determined based on the degree of consistency between the response amplitude, response polarity, or arrival time of the target azimuth and adjacent azimuths.

[0016] Abnormal data includes external power pulses other than brine disturbances, sudden jumps between adjacent sampling points, instrument saturation, poor electrode contact, and abnormal sampling synchronization data. Abnormal data is removed or marked before calculating the response arrival time and response amplitude.

[0017] Compared with the prior art, the present invention has the following advantages: This invention avoids time splicing errors caused by time-division point-by-point measurement by synchronous acquisition of two-dimensional multi-point data. This invention reduces the impact of zero-point drift and site background differences by interpreting the absolute potential differently before and after the perturbation rather than directly. This invention identifies direction by combining arrival time and response amplitude, and can utilize the dynamic process after saltwater disturbance; This invention enables rapid on-site identification under low-cost disturbance conditions such as existing wellbores, shallow injection points, or trench infiltration points. Attached Figure Description

[0018] Figure 1 The flowchart shows a method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential. Figure 2A schematic diagram of the time series of flow potential in each channel under brine disturbance conditions provided by the present invention; Figure 3 The differential flow potential response intensity and dominant direction identification diagram provided by the present invention; Figure 4 The architecture diagram of the synchronous acquisition device provided by this invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] A method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential includes: S1. Obtain the data of the survey area, select the brine disturbance source according to the data of the survey area, and take the brine injection start time as the time zero point reference. S2. An electrode array is deployed on the ground with the brine disturbance source as the center, and a reference electrode is deployed at the potential stable location. S3. Before brine injection, the background potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. After brine injection, the response potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. S4. Based on the background potential sequence and the response potential sequence, calculate the differential flow potential response of each measuring point before and after the brine disturbance, remove abnormal data points, and construct the purification differential sequence. S5. Perform moving average noise reduction on the purified differential sequence and extract the response data of each measurement point; S6. Based on the response data of each measuring point extracted in S5, a score is obtained by comprehensively considering the arrival time of the response in each direction, the magnitude of the response, the effectiveness of the apparent disturbance response migration speed, and the spatial continuity of the response characteristics of adjacent directions. The brine disturbance score is obtained. Based on the brine disturbance score, the dominant response direction of the shallow pore fracture water flow field is determined, and the candidate dominant flow field direction, apparent brine disturbance response migration speed, direction confidence, and potential response intensity map are output.

[0021] The S1 measurement area data includes the boundary of the area to be measured, the location of saltwater disturbance sources, the location of existing wells, ditches, drainage points, water outlets, water injection points, and the surface area where electrodes can be deployed. The sources of brine disturbance include existing wells, injection points, and ditch infiltration points. The injection points are shallow injection points located within a first preset depth range below the surface. The first preset depth range is usually a depth range greater than 0 meters and less than or equal to 50 meters from the surface, which can be determined according to the actual working conditions. After selecting the brine disturbance source, record the brine concentration, injection volume, injection flow rate, start time, and duration of the brine disturbance source.

[0022] Electrode arrays include circular arrays, concentric circle arrays, linear measuring line arrays, and grid arrays; The reference electrode is positioned far from the area affected by brine disturbance and where the potential is relatively stable. When using an inner and outer concentric circle array, the inner circle radius is... The outer radius is The inner and outer radii are determined based on the survey area, the expected disturbance propagation distance, and the available deployment conditions on site. In this embodiment, the inner radius... It is 10m, and the outer radius is... The value is 20m. The inner and outer circular measuring points in the same orientation constitute a response propagation identification pair, which is used to calculate the apparent disturbance response migration velocity.

[0023] In S4, the differential flow potential response is: ; In the formula, Indicates the first Each measuring point at time... The measured potential, Indicates the first Each measuring point during the background period The average electric potential inside, This represents the differential flow potential response relative to the background value after a disturbance.

[0024] The background period is a continuous period of time in which the potential is relatively stable before the brine is injected, and the duration is preferably not less than 2 minutes; in this embodiment, the background period lasts for about 2 minutes and 20 seconds.

[0025] The measured potential includes the flow potential generated by the water flow, the diffusion potential generated by the salinity change, the background potential, the electrode bias, and external disturbances; the differential potential response caused by the salt water disturbance is obtained by subtracting the average background potential before the disturbance.

[0026] The response data in S5 includes the response arrival time, peak response amplitude, average response amplitude, response polarity, and response duration for each measurement point. The response arrival time is the earliest time when the differential flow potential response, after smoothing, continuously exceeds the background noise threshold.

[0027] The background noise threshold is: ; ; ; In the formula, Indicates the first Minimum response threshold for each measurement point Indicates the first The standard deviation of the potential at each measuring point during the background period before the disturbance. Indicates the threshold multiple. For the first The response arrival time of each measuring point This represents the analysis time window after saline disturbance. Indicates the offset. This indicates the number of consecutive sampling points that must exceed the threshold to determine a valid response. Indicates the first The measuring point at the ... The smoothed differential potential at each sampling time, Indicates the first Each measuring point at time... The differential potential, For the first The average response amplitude at each measuring point This represents the number of valid sampling points within the statistical time window of the average response amplitude. The corresponding statistical time window is set in specific implementations. In this embodiment, the statistical time window is 3 minutes after the response arrives. The threshold multiple is usually 2 to 3 times, preferably 3 times. The specific value can be adjusted according to the background noise level at the site. , Essentially, both are the result of averaging the original differential potential, but their statistical window lengths and application scenarios are completely different. It is the first The instantaneous signal level estimate obtained by performing moving average denoising on several adjacent sampling points before and after a sampling time is used to determine point-by-point on the time axis whether the brine disturbance has propagated to that measurement point, i.e., compared with the background noise threshold. Perform absolute value comparisons to determine response arrival time. , Indicates the first The arithmetic mean of the differential potential of all sampling points at a given measurement point within a preset statistical time window (e.g., 3 minutes after the response arrives) after the effective response arrives is a scalar statistical value that does not change with time. It is used to quantitatively characterize the average signal strength of the measurement point during the entire response duration and serves as the basis for calculating the response amplitude index in subsequent directional scoring.

[0028] When using an inner and outer concentric circle array, the response migration speed is: ; ; In the formula, It is the azimuth angle. Azimuth The response arrival time of the measuring point on the outer circle, Azimuth The arrival time of the response at the upper inner circle measuring point.

[0029] Based on the response data of each measuring point extracted by S5, the response arrival time and response amplitude of each direction are weighted and scored. The validity of the apparent disturbance response migration speed is used as the pre-screening condition for the scoring results. Only when the response arrival time of the inner circle measuring point in the same direction is earlier than that of the outer circle measuring point, the direction is included in the subsequent weighted scoring; otherwise, the direction is eliminated. The spatial continuity of the response characteristics of adjacent directions is used as the post-verification condition for the scoring. When the difference in response amplitude between the target direction and the adjacent direction exceeds a preset threshold or the response polarity is opposite, the scoring result of the direction is downweighted or eliminated. The dominant response direction of the shallow pore fracture water flow field is determined by the scoring results, and the candidate directions of the dominant flow field, the apparent brine disturbance response migration speed, the direction confidence and the potential response intensity map are output. The validity criteria for apparent disturbance response migration speed are as follows: the arrival time of the outer circle response must be later than that of the inner circle response; otherwise, the azimuth will not be included in the scoring. The spatial continuity verification criteria are as follows: the difference in response amplitude between the target azimuth and the adjacent azimuth must be within a preset range and the response polarity must be consistent; otherwise, the score of the azimuth will be reduced or eliminated.

[0030] The comprehensive score for saltwater disturbance response is determined by both the response arrival time index and the response amplitude index. ; In the formula, Indicates azimuth angle The normalized response arrival time metric Azimuth The average response amplitude normalization index, , They represent , The weighting coefficient. In this embodiment, the weighting coefficient... , All values ​​are set to 0.5, and the sum of the weighting coefficients is 1. In practical applications, the parameters should be adjusted according to the actual situation.

[0031] The response arrival time index is calculated based on the principle that the earlier the response, the larger the value. The response amplitude index is calculated based on the principle that the larger the average absolute value of the differential flowing potential, the larger the value. The spatial continuity index is determined by the degree of consistency between the response amplitude, response polarity, or arrival time between the target azimuth and adjacent azimuths. This method is preferentially applicable to concentric circular arrays, with other arrays as alternatives. However, the migration velocity is only calculated when a radial distance difference exists; otherwise, only the arrival time and amplitude are used for directional scoring. For single-ring circular arrays, the velocity can be estimated using the arrival time difference between different azimuths. When using non-concentric circular arrays (such as single-ring circular, linear, or grid arrays), due to the lack of a fixed radial distance difference, the apparent disturbance response migration velocity is not calculated, and the directional scoring is based solely on the response arrival time and amplitude. Spatial continuity is still used as an auxiliary verification condition.

[0032] Abnormal data includes external power pulses other than brine disturbances, sudden jumps between adjacent sampling points, instrument saturation, poor electrode contact, and abnormal sampling synchronization data. Abnormal data is removed or marked before calculating response arrival time and response amplitude. The sampling frequency is determined based on the rate of change of the brine disturbance response; in this embodiment, the sampling frequency is approximately 2Hz, which meets the requirements for determining response arrival time and continuous exceeding the threshold. Removed abnormal data points are marked as missing values ​​and are not imputed by interpolation; subsequent smoothing and index calculations use the remaining valid data. When the proportion of abnormal or missing data for a certain measurement point exceeds 20% during the analysis period, the data for that measurement point is considered invalid and not included in the direction scoring. Peak response amplitude, response polarity, and response duration do not directly participate in the direction scoring, but can be used as auxiliary features for abnormal data identification or qualitative analysis of results; the amplitude index used for scoring is the average response amplitude.

[0033] In S3, the stable time window before the brine disturbance begins is used as the background period. The average background potential is calculated for each measuring point and used for subsequent differential processing. The background period is a continuous period of relatively stable potential before brine injection, and the duration is preferably not less than 2 minutes; in this embodiment, the background period lasts for about 2 minutes and 20 seconds.

[0034] In S4, background subtraction is performed on the potential at each measuring point after brine disturbance to obtain the differential flow potential response. This processing is used to reduce the effects of original zero-point differences, electrode contact differences, and long-term background drift at the measuring points. The response potential sequence of each measuring point is subtracted from the average value of the corresponding measuring point during the background period before injection at each time step to obtain the differential flow potential response of each measuring point, and outlier data points are removed to construct the purification differential sequence.

[0035] In step S5, the effective response threshold is determined based on the average differential potential fluctuation within the reference floating time window before the target disturbance. When multiple consecutive sampling points of the differential flow potential response after moving average processing reach or exceed the effective response threshold, the moment when the condition is first met is recorded as the response arrival time of that measurement point. Within a set time window after the effective response arrival time of each measurement point, the average value of the absolute value of the smoothed differential flow potential response is calculated as the average response amplitude of that measurement point; simultaneously, the peak response amplitude and response polarity can be extracted as auxiliary features. The differential flow potential response is then subjected to moving average or low-pass filtering to obtain a smoothed differential flow potential response. In this embodiment, the moving average time window is 7 seconds.

[0036] In S6, the dominant response candidate direction refers to one or more azimuths with higher directional scores. When multiple adjacent azimuths have high directional scores, these adjacent azimuths are collectively identified as dominant response candidate sectors. When using concentric circle arrays, the response arrival times of the inner and outer circle measuring points in the same azimuth are compared. If the inner circle responds first and the outer circle responds later, the apparent disturbance response migration velocity is calculated. The apparent saltwater disturbance response migration velocity is determined based on the radial distance difference between the outer and inner circle measuring points in the same azimuth and the effective response arrival time difference. If the first response of the outer circle measuring point is earlier than or close to the response of the inner circle measuring point, the first response is judged as an abnormally early arrival response, and the apparent saltwater disturbance response migration velocity in that azimuth is not calculated. The effective response of the outer circle measuring point is then searched again within the subsequent analysis time window. If no subsequent effective response is found, the apparent disturbance response migration velocity in that azimuth is not calculated, and it is only marked as a complex boundary response, non-radial response, or background field interference direction. The relative reliability of a direction is obtained by normalizing the direction score for that direction (maximum-min normalization can be used). It is used to represent the relative reliability of the response results in different directions within the same brine disturbance test, and does not represent statistical confidence probability. The potential response intensity map is generated based on the location of each measuring point and the average differential potential response amplitude over a period of time after the response arrives, with different colors representing the response strength at different locations. A comprehensive score is calculated for each direction, determined by the response arrival time index, average response amplitude index, internal and external array migration relationship index, and spatial continuity index. Directions with higher comprehensive scores and spatially continuous responses are identified as the dominant hydroconductive and conductive response directions in the shallow pore-fracture water flow field. The validity of spatial continuity indicators and apparent disturbance response migration speed is not directly involved in the numerical calculation of the weighted summation formula, but is used as a pre-screening condition or a post-reasonableness verification criterion for the scoring results: when the spatial continuity of a certain direction is lower than the preset threshold, or its apparent migration speed exceeds the reasonable physical range (such as the abnormal early arrival response where the outer circle arrives earlier than the inner circle), the scoring result of that direction is downweighted or directly eliminated and is not included in the candidate direction of the dominant response.

[0037] The shallow pore-fracture water flow field identification method based on two-dimensional synchronous flow potential does not use time-division point-by-point measurement results to form a static potential map. Instead, it acquires a dynamic potential sequence of two-dimensional multi-measurement points under a unified time reference and identifies the spatiotemporal migration characteristics of potential disturbance based on the differential response before and after brine disturbance. Furthermore, measurement points at different radial distances in the same azimuth are formed into response propagation identification pairs. The validity of radial propagation is determined by the response sequence between inner and outer measurement points. When abnormal noise or an early arrival response occurs at an outer measurement point, the abnormal response is excluded, and a subsequent valid response is searched again. A comprehensive directional score is formed by considering response arrival time, response amplitude, validity of migration relationship, and spatial continuity in adjacent azimuths to reduce misjudgments caused by single response amplitude, single arrival time, or local abnormal signals.

[0038] Figure 1 The flowchart of the method of this invention includes, in sequence, the following steps: electrode array and reference electrode placement, saline injection, synchronous acquisition, background subtraction, abnormal data removal, smoothing, response arrival time determination, early-arriving response exclusion, average response amplitude and apparent migration velocity calculation, directional comprehensive scoring, and dominant response direction output. Abnormal data detection can employ the standard deviation method within a sliding window. For the difference sequence of each measurement point, M points (e.g., M=5) are taken before and after the current point, and the mean and standard deviation within the window are calculated. If the difference between the current point and the mean exceeds three times the standard deviation, it is determined to be an abnormal point. Saturated data is directly determined by the upper limit of the amplitude.

[0039] Figure 2 This diagram illustrates the change in potential at the CH6 measuring point on the outer ring over time. The horizontal axis represents the acquisition time, and the vertical axis represents the measured potential. During the test, electrode replacement was performed at 16:53, the first brine injection was conducted at 17:08, and the second brine injection was performed at 17:19. Recording the potential changes before and after different operations provides a basis for identifying operational interference and brine disturbance response.

[0040] Figure 3 This is a comprehensive scoring map of brine disturbance azimuth. In this embodiment, the second brine injection time of 17:19 is selected as the zero point of time. The background potential is calculated based on the stable period before brine injection, and the differential potential sequence after brine injection is smoothed and outlier data is removed. A comprehensive score is calculated based on the response arrival time, response amplitude, inner and outer circle response migration relationship, and spatial continuity of adjacent azimuths at each measuring point. The higher the comprehensive score, the more obvious the brine disturbance response at that azimuth, and the more likely it is to be considered as a candidate direction for the dominant flow field.

[0041] Figure 4The diagram shows the architecture of the synchronous acquisition device. The signals from the inner electrode, outer electrode, and far-end reference electrode enter the central synchronous acquisition control unit through the multi-channel input terminal, signal processing and anti-interference unit, and high-precision analog-to-digital conversion module. The synchronous clock module provides a unified time reference, and the acquired data is transmitted to the host computer processing software through local storage or communication module.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential, characterized in that, include: S1. Obtain the data of the survey area, select the brine disturbance source according to the data of the survey area, and take the brine injection start time as the time zero point reference. S2. An electrode array is deployed on the ground with the brine disturbance source as the center, and a reference electrode is deployed at the potential stable location. S3. Before brine injection, the background potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. After brine injection, the response potential sequence of each measuring point in the electrode array relative to the reference electrode is collected synchronously. S4. Based on the background potential sequence and the response potential sequence, calculate the differential flow potential response of each measuring point before and after the brine disturbance, remove abnormal data points, and construct the purification differential sequence. S5. Perform moving average noise reduction on the purified differential sequence and extract the response data of each measurement point; S6. Based on the response data of each measuring point extracted in S5, a score is obtained by comprehensively considering the arrival time of the response in each direction, the magnitude of the response, the effectiveness of the apparent disturbance response migration speed, and the spatial continuity of the response characteristics of adjacent directions. The brine disturbance score is obtained. Based on the brine disturbance score, the dominant response direction of the shallow pore fracture water flow field is determined, and the candidate dominant flow field direction, apparent brine disturbance response migration speed, direction confidence, and potential response intensity map are output.

2. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 1, characterized in that, The S1 measurement area data includes the boundary of the area to be measured, the location of saltwater disturbance sources, the location of existing wells, ditches, drainage points, water outlets, water injection points, and the surface area where electrodes can be deployed. Sources of brine disturbance include wells, injection points, and infiltration points in ditches; After selecting the brine disturbance source, record the brine concentration, injection volume, injection flow rate, start time, and duration of the brine disturbance source.

3. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 2, characterized in that, Electrode arrays include circular arrays, concentric circle arrays, linear measuring line arrays, and grid arrays; The reference electrode is positioned far from the area affected by brine disturbance and where the potential is relatively stable. When using an inner and outer concentric circle array, the inner circle radius is... The outer radius is The inner and outer circular measuring points in the same orientation constitute a response propagation identification pair, which is used to calculate the apparent disturbance response migration velocity.

4. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 3, characterized in that, In S4, the differential flow potential response is: ； In the formula, Indicates the first Each measuring point at time... The measured potential, Indicates the first Each measuring point during the background period The average electric potential inside, This represents the differential flow potential response relative to the background value after a disturbance.

5. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 4, characterized in that, The response data in S5 includes the response arrival time, peak response amplitude, average response amplitude, response polarity, and response duration for each measurement point. The response arrival time is the earliest time when the differential flow potential response, after smoothing, continuously exceeds the background noise threshold.

6. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 5, characterized in that, The background noise threshold is: ； ； ； In the formula, Indicates the first Minimum response threshold for each measurement point Indicates the first The standard deviation of the potential at each measuring point during the background period before the disturbance. Indicates the threshold multiple. For the first The response arrival time of each measuring point This represents the analysis time window after saline disturbance. Indicates the first time window within the analysis time window Each sampling time, Indicates the offset. This represents the number of consecutive sampling points exceeding the threshold required to determine a valid response. Indicates the first The measuring point at the ... The smoothed differential potential at each sampling time, Indicates the first Each measuring point at time... The differential potential, For the first The average response amplitude at each measuring point The number of consecutive sampling points exceeding a threshold is required to determine a valid response. This represents the number of valid sampling points within the statistical time window of the average response amplitude.

7. The method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential according to claim 6, characterized in that, When the electrode array uses an inner and outer concentric circle array, the response migration speed is: ； ； In the formula, It is the azimuth angle. Azimuth The response arrival time of the measuring point on the outer circle, Azimuth The arrival time of the response at the upper inner circle measuring point.

8. The method for identifying shallow pore-fracture water flow field based on two-dimensional synchronous flow potential according to claim 7, characterized in that, Based on the response data extracted from each measuring point by S5, the arrival time and amplitude of the response in each direction are weighted and scored. The validity of the apparent disturbance response migration velocity is used as a pre-screening condition for the scoring results, and the spatial continuity of the response characteristics of adjacent directions is used as a post-validation condition for the rationality of the scoring results. The dominant response direction of the shallow pore-fracture water flow field is determined, and the candidate dominant flow field direction, apparent brine disturbance response migration velocity, direction confidence, and potential response intensity map are output. ； In the formula, Indicates azimuth angle The normalized response arrival time metric Azimuth The average response amplitude normalization index, , They represent , The weighting coefficients.

9. The method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential according to claim 8, characterized in that, The response arrival time index is calculated based on the principle that the earlier the response, the larger the value. The response amplitude index is calculated based on the principle that the larger the average absolute value of the differential current potential, the larger the value. The spatial continuity index is determined based on the degree of consistency between the response amplitude, response polarity, or arrival time of the target azimuth and adjacent azimuths.

10. The method for identifying shallow pore-fracture water flow fields based on two-dimensional synchronous flow potential according to claim 9, characterized in that, Abnormal data includes external power pulses other than brine disturbances, sudden jumps between adjacent sampling points, instrument saturation, poor electrode contact, and abnormal sampling synchronization data. Abnormal data is removed or marked before calculating the response arrival time and response amplitude.

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