In-situ monitoring method for exploitation effect of brine exploitation well

Abstract

This application proposes an in-situ monitoring method for the extraction effect of brine wells, belonging to the fields of geophysical exploration and hydrogeological monitoring. To overcome the shortcomings of existing technologies, such as high cost, long cycle time, and the ability to obtain only point-like information, this method utilizes a ground-based resistivity surveying network (a cross-shaped layout) to monitor the influence radius of the pumping well and the direction of salt replenishment by leveraging the resistivity differences between brine, formation media, and fresh and salt water. Specifically, a Wenner quadrupole device is used to measure the background apparent resistivity before brine extraction, constructing a background apparent resistivity matrix. During brine extraction, apparent resistivity measurements are continuously performed, and the spatiotemporal distribution characteristics of salt migration are inverted based on the changes in apparent resistivity. The influence radius of the brine well is determined based on the spatial range of apparent resistivity changes in the two cross-sections. A dominant direction discrimination index is calculated based on the difference in the amplitude of apparent resistivity changes between the two cross-sections, quantitatively determining the dominant direction of salt replenishment.

Description

Technical Field

[0001] This application relates to the fields of geophysical exploration and hydrogeological monitoring, and specifically proposes a method for in-situ determination of the mining effect of brine wells using ground resistivity monitoring technology. It is particularly suitable for real-time monitoring of the influence radius of pumping wells and the direction of salt migration in coastal brine mining areas. Background Technology

[0002] The underground brine areas distributed along my country's coast are important salt resource producing areas, rich in useful components such as sodium chloride, potassium chloride, and bromine, and are the raw material source for industries such as salt chemical industry and bromine extraction.

[0003] In brine extraction, accurately determining the influence radius of pumping wells and the direction of salt replenishment is crucial for optimizing well network layout, assessing resource reserves, and formulating reasonable extraction plans. Currently, the main method for monitoring the extraction effect of brine wells involves deploying multiple monitoring wells around the pumping wells, periodically collecting water samples from these wells, and sending them to a laboratory for chemical analysis, such as mineralization and ion concentration. By comparing water quality changes at different locations and times, the influence range of the pumping wells and the direction of salt migration can be inferred. This method has the following main problems: 1. Deploying dedicated monitoring wells requires significant drilling investment, resulting in high costs. Furthermore, the limited number of monitoring wells only provides discrete, point-like information, making it difficult to comprehensively reflect the continuous changes in salt distribution. 2. The water sampling and laboratory analysis cycles are long, leading to data lag and an inability to reflect dynamic changes during the extraction process in real time, hindering timely production adjustments. 3. Existing methods can only obtain water quality information from the location of monitoring wells; there is a lack of intuitive means to determine the dominant direction of salt replenishment, and well network optimization lacks a scientific basis.

[0004] Therefore, there is an urgent need to develop a method that can monitor the mining effect of brine wells in situ, in real time, and dynamically, so as to obtain spatiotemporally continuous salt distribution information at low cost and provide technical support for the sustainable development of brine resources. Summary of the Invention

[0005] In view of this, this application proposes a novel in-situ monitoring method for the extraction effect of brine wells, aiming to overcome the shortcomings of the existing technology, which requires the deployment of multiple monitoring wells around the well and the acquisition of data through sampling and testing, resulting in high costs, long cycles, and only point-like information. By deploying resistivity measuring lines in a cross pattern on the ground, and utilizing the resistivity differences between brine, formation medium, and fresh and salt water, in-situ, real-time, and dynamic monitoring of the radius of influence of the pumping well and the direction of salt replenishment can be achieved.

[0006] To achieve the aforementioned objectives, the in-situ monitoring method for the extraction effect of brine extraction wells involves deploying a cross-shaped electrode array on the ground centered on the brine extraction well. A Winner quadrupole device is used to measure the background apparent resistivity before brine extraction, constructing a background apparent resistivity matrix. During brine extraction, apparent resistivity measurements are continuously performed, and the rate of change of apparent resistivity at each measuring point is calculated based on the background apparent resistivity. The spatiotemporal distribution characteristics of salt transport are then inverted based on the apparent resistivity changes. The influence radius of the brine extraction well is determined based on the spatial range of apparent resistivity changes in the two cross-sections. A dominant direction discrimination index is calculated based on the difference in the magnitude of apparent resistivity changes between the two cross-sections, quantitatively determining the dominant direction of salt replenishment.

[0007] The in-situ monitoring method includes the following implementation process:

[0008] Step S1: Electrode placement;

[0009] Centered on the brine extraction well, a cable is laid on the ground in two mutually perpendicular horizontal directions to form a cross-shaped electrode array; several electrodes are laid at equal intervals on each cable, and the intersection of the cross is located directly above the brine extraction well.

[0010] Step S2: Measure the apparent resistivity of the background;

[0011] Before brine extraction, a complete apparent resistivity measurement is performed as a background value.

[0012] Current is supplied to the ground through the electrode array, the potential difference between each electrode is measured, the background apparent resistivity distribution of the underground medium is calculated, and the background apparent resistivity matrix ρ0 is constructed.

[0013] Step S3: Dynamic monitoring;

[0014] During brine extraction, apparent resistivity measurements were continuously performed at set time intervals. Each measurement used the same electrode array and power supply parameters as the background measurements to ensure data comparability, resulting in the following time-series apparent resistivity matrix:

[0015] ;

[0016] Among them, t k Let T be the time of the k-th monitoring session, and T be the total number of monitoring sessions.

[0017] Step S4: Data processing;

[0018] Using the background apparent resistivity matrix ρ0 as a benchmark, the rate of change of apparent resistivity at each measuring point and depth at different times is calculated, the spatiotemporal distribution characteristics of salt migration are inverted, the influence radius of brine extraction wells and the dominant direction of salt replenishment are determined, and dynamic monitoring is realized.

[0019] Step S5: Interpretation of results;

[0020] Based on a comprehensive interpretation of the data processing results, the following output is provided:

[0021] Comprehensive influence radius This reflects the effective range of influence of the well underground;

[0022] The dominant direction of salt replenishment, and the index determined by the dominant direction. Quantitative characterization to determine the main supply direction;

[0023] Spatiotemporal diagram of salt transport, using the relative change in salt concentration. The dynamic spatiotemporal distribution map is drawn based on this, reflecting the speed and path of salt migration.

[0024] Step S2 includes,

[0025] Step S2.1: Power supply and data acquisition;

[0026] During the measurement, a Wenner quadrupole device was used, with four adjacent electrodes grouped together, and a stable DC current I was supplied to the ground. At the same time, the potential difference ΔU between the two middle potential electrodes M and N was measured.

[0027] Step S2.2: Calculate the apparent resistivity;

[0028] For a Wenner device with an electrode spacing of 'a', the apparent resistivity is calculated using the following formula:

[0029] ;

[0030] Among them, device coefficient

[0031] Each time the electrode spacing is moved, data is collected sequentially to form a set of apparent resistivity data sequence;

[0032] Step S2.3, background apparent resistivity matrix;

[0033] All measurement data for the two cables were compiled into a background apparent resistivity matrix ρ0:

[0034] ;

[0035] in, The horizontal position is in meters (m); z j This corresponds to the detection depth; This represents the number of horizontal measurement points. The depth is the number of layers;

[0036] The aforementioned background apparent resistivity matrix reflects the original distribution of salt in each stratum before mining, serving as a benchmark dataset for subsequent dynamic monitoring.

[0037] Step S3 includes,

[0038] Step S3.1: Establishing the apparent resistivity profile;

[0039] Based on the apparent resistivity data of each measurement Based on this, a two-dimensional inversion algorithm is used to convert apparent resistivity data into a real resistivity profile. With horizontal distance as the horizontal axis and detection depth as the vertical axis, a two-dimensional resistivity profile map is drawn by color mark interpolation, which intuitively presents the spatial distribution of resistivity of underground media.

[0040] Step S3.2, Layer division;

[0041] Based on the characteristics of the apparent resistivity profile and combined with known geological data, the following stratigraphic levels are identified:

[0042] The boundary zone between freshwater and brine aquifers, located at the boundary of the monitoring area, has the lowest pore water salinity and the highest apparent resistivity.

[0043] The brine aquifer has high pore water salinity and moderate apparent resistivity.

[0044] The weakly permeable layer has small pores, and the pore water has the highest salinity, the strongest conductivity, and the lowest apparent resistivity.

[0045] Step S3.3: Data change trends and parameter correspondence;

[0046] By superimposing and comparing the apparent resistivity profiles at different times, the following variation patterns were observed:

[0047] The apparent resistivity continuously decreases over time, indicating that the salt concentration continuously increases and the brine supply is sufficient.

[0048] A continuous increase in apparent resistivity over time indicates a continuous decrease in salt concentration, either due to freshwater intrusion or the extraction of brine.

[0049] When the apparent resistivity changes tend to stabilize, it indicates that salt migration has reached a dynamic equilibrium.

[0050] Step S4 includes,

[0051] Step S4.1: Calculate the rate of change of apparent resistivity;

[0052] With background apparent resistivity matrix Based on this, calculate the first... The rate of change of apparent resistivity at each measuring point and at each depth during the second monitoring:

[0053] ;

[0054] If the apparent resistivity change rate is negative, it indicates that the apparent resistivity has decreased and the salt concentration has increased; if the apparent resistivity change rate is positive, it indicates that the apparent resistivity has increased and the salt concentration has decreased.

[0055] Step S4.2: Quantitative conversion of salt concentration changes;

[0056] According to Archie's law, the electrical conductivity of formation pore water... With formation apparent resistivity The following conditions must be met:

[0057] ;

[0058] Where F is a formation factor determined by porosity and tortuosity, which can be taken in this embodiment. ;

[0059] Sodium chloride mass concentration C in brine and pore water conductivity The approximate empirical relation is:

[0060] ;

[0061] The above approximate empirical relationship applies to NaCl solutions within a certain temperature range. Therefore, the rate of change of apparent resistivity at each measuring point is converted into the relative change in salt concentration. :

[0062] ;

[0063] All measuring points By plotting this as a spatiotemporal distribution map, the spatiotemporal distribution characteristics of salt transport can be obtained;

[0064] When a pumping well begins operation, high-salinity brine is extracted from the surrounding area. If low-salinity water is supplied, the resistivity will increase. When high-salinity brine in a poorly permeable layer is displaced and migrates towards the well, the apparent resistivity decreases. By comparing apparent resistivity profiles at different times, the dynamic process of salt migration can be tracked.

[0065] Step S4.3: Determining the radius of influence;

[0066] The maximum apparent resistivity change rate at each horizontal position is extracted from two different cross-sections along the cross-section of the two cables 3. The system scans point by point on both sides of the well as the mining well, and judges whether the absolute value of the apparent resistivity change rate exceeds the preset threshold.

[0067] Step S4.4: Determining the dominant direction of salt replenishment;

[0068] Compare the mean rate of change of apparent resistivity of the two sections at the same time and define the dominant direction discrimination index.

[0069] In step S4.3, The distance from the farthest measuring point to the well is recorded as the influence distance in that direction.

[0070] In step S4.3, the positive influence distance is taken along the cross-section of the east-west cable. and negative influence distance The positive influence distance on the cross-section of north-south cables is as follows: and negative influence distance The overall influence radius is taken as the average value of the four directions: .

[0071] In step S4.4, the average rate of change of apparent resistivity of the two sections at the same time is compared:

[0072] ;

[0073] ;

[0074] Define the dominant direction discriminant index D:

[0075] ;

[0076] Among them, if The dominant direction of salt replenishment is determined to be east-west; if The dominant direction of salt replenishment is determined to be north-south; if It was determined that the supply amounts from the two directions were similar, and there was no clear advantage in salt supply from any direction.

[0077] In summary, the beneficial effects and advantages of this application compared with the prior art include:

[0078] 1. Applying this application eliminates the need for dedicated monitoring wells, significantly reducing costs; utilizing ground resistivity measurement technology eliminates the need for drilling monitoring wells, requiring only the laying of cables and electrodes on the ground, resulting in lower equipment investment, simpler construction, and monitoring costs far lower than traditional methods.

[0079] 2. This application features in-situ, real-time, dynamic monitoring and rich information. During the mining process, resistivity measurements are continuously performed to obtain spatiotemporally continuous salt distribution information, avoiding the representativeness error of point sampling, and reflecting the dynamic process of salt migration in real time.

[0080] 3. This application can simultaneously and quantitatively determine the radius of influence and the dominant direction of salt replenishment. By using two cross sections that intersect, it can determine the radius of influence of the production well and quantitatively determine the dominant direction of salt replenishment through the dominant direction discrimination index, providing a scientific basis for well network optimization.

[0081] 4. This application is characterized by its simple operation and strong adaptability, and is applicable to various brine mining areas, especially to brine mining monitoring in coastal areas. Attached Figure Description

[0082] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. Some specific embodiments of this application will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference numerals in the drawings designate the same or similar parts or components. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale.

[0083] Figure 1 This is a schematic diagram of the electrode array and salt transport monitoring setup in the embodiment;

[0084] Figure 2 This is a flowchart illustrating the data acquisition and processing of the in-situ monitoring method described in this application;

[0085] In the above figures, 1-brine extraction well, 2-electrode, 3-cable, 4-influence radius, 5-boundary of the survey line range; Detailed Implementation

[0086] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0087] Example 1, such as Figure 1 and Figure 2 As shown, this application proposes a method for in-situ monitoring of the extraction effect of brine wells in coastal brine extraction areas. The geological conditions of this extraction area are multi-layered, consisting of a cover layer, an aquifer, and a weakly permeable layer from top to bottom. The brine is mainly found in the pores of the aquifer and the weakly permeable layer. There is a significant difference in apparent resistivity between the brine and the formation medium, which meets the physical prerequisites for apparent resistivity monitoring.

[0088] The method for in-situ monitoring of the extraction effect of brine extraction wells involves deploying a cross-shaped electrode array on the ground centered on the brine extraction well. Before brine extraction, a Wenner quadrupole device is used to measure the background apparent resistivity and construct a background apparent resistivity matrix. During brine extraction, apparent resistivity measurements are continuously performed, and the rate of change of apparent resistivity at each measuring point is calculated based on the background apparent resistivity. The spatiotemporal distribution characteristics of salt transport are inverted based on the apparent resistivity changes. The influence radius of the brine extraction well is determined based on the spatial range of apparent resistivity changes in the two cross sections. A dominant direction discrimination index is calculated based on the difference in the amplitude of apparent resistivity changes between the two sections to quantitatively determine the dominant direction of salt replenishment.

[0089] The implementation process includes the following:

[0090] Step S1: Electrode placement;

[0091] Centered on brine extraction well 1, a cable 3 is laid out on the ground along two mutually perpendicular horizontal directions to form a cross-shaped electrode array; if the depth of brine extraction well 1 is 100m, then the length of each cable 3 is 3 times the depth of the well, that is, 300m, to ensure that the measuring line covers the possible influence range of the pumping well.

[0092] Several (e.g., 30) electrodes 2 are arranged at equal intervals on each cable 3, so the distance between adjacent electrodes 2 is 10 m; the cross intersection is located directly above the brine extraction well 1;

[0093] Step S2: Measure the apparent resistivity of the background;

[0094] Before brine extraction, a complete apparent resistivity measurement is performed as a background value.

[0095] Current is supplied to the ground through the electrode array, the potential difference between each electrode is measured, the background apparent resistivity distribution of the underground medium is calculated, and the background apparent resistivity matrix ρ0 is constructed.

[0096] include,

[0097] Step S2.1: Power supply and data acquisition;

[0098] During the measurement, a Wenner quadrupole device was used, with four adjacent electrodes grouped together, and a stable DC current I was supplied to the ground. At the same time, the potential difference ΔU between the two middle potential electrodes M and N was measured.

[0099] Step S2.2: Calculate the apparent resistivity;

[0100] For a Wenner device with an electrode spacing of 'a', the apparent resistivity is calculated using the following formula:

[0101] ;

[0102] Among them, device coefficient In this embodiment ,but

[0103] Each time the electrode spacing is moved, data is collected sequentially to form a set of apparent resistivity data sequence;

[0104] Step S2.3, background apparent resistivity matrix;

[0105] All measurement data for the two cables were compiled into a background apparent resistivity matrix ρ0:

[0106] ;

[0107] in, The horizontal position is in meters (m); z j This corresponds to the detection depth; This represents the number of horizontal measurement points. The depth is the number of layers; the effective detection depth of the Wenner device is approximately 0.5 times the electrode spacing, and in this embodiment, the detection depth range is 5 to 50 m.

[0108] The aforementioned background apparent resistivity matrix reflects the original distribution of salt in each stratum before mining, serving as a benchmark dataset for subsequent dynamic monitoring.

[0109] Step S3: Dynamic monitoring;

[0110] During brine extraction, apparent resistivity measurements were continuously performed at set time intervals. Each measurement used the same electrode array and power supply parameters as the background measurements to ensure data comparability, resulting in the following time-series apparent resistivity matrix:

[0111] ;

[0112] Among them, t k Let T be the time of the k-th monitoring session, and T be the total number of monitoring sessions.

[0113] The dynamic monitoring process includes,

[0114] Step S3.1: Establishing the apparent resistivity profile;

[0115] Based on the apparent resistivity data of each measurement Based on this, a two-dimensional inversion algorithm is used to convert apparent resistivity data into a real resistivity profile. With horizontal distance as the horizontal axis and detection depth as the vertical axis, a two-dimensional resistivity profile map is drawn by color mark interpolation, which intuitively presents the spatial distribution of resistivity of underground media.

[0116] Step S3.2, Layer division;

[0117] Based on the characteristics of the apparent resistivity profile and combined with known geological data, the following stratigraphic levels are defined; specific thresholds can be adjusted according to actual geological conditions, and the following are reference values ​​for this embodiment:

[0118] The boundary zone between freshwater and brine aquifers, located at the boundary of the monitoring area, has the lowest pore water salinity and the highest apparent resistivity. In this embodiment, the reference value is greater than 20 Ω·m.

[0119] The brine aquifer has high pore water salinity and moderate apparent resistivity, with a reference value of 5–20 Ω·m in this embodiment.

[0120] The weakly permeable layer has small pores, and the pore water has the highest salinity, the strongest conductivity, and the lowest apparent resistivity. In this embodiment, the reference value is less than 5 Ω·m.

[0121] Step S3.3: Data change trends and parameter correspondence;

[0122] By superimposing and comparing the apparent resistivity profiles at different times, the following variation patterns were observed:

[0123] The apparent resistivity continuously decreases over time, indicating that the salt concentration in the area is continuously increasing and the brine supply is sufficient.

[0124] The apparent resistivity continuously increases over time, indicating that the salt concentration in the area is continuously decreasing, suggesting freshwater intrusion or brine extraction.

[0125] The stabilization of resistivity indicates that salt transport at that location has reached a dynamic equilibrium.

[0126] Step S4: Data processing;

[0127] Using the background apparent resistivity matrix ρ0 as a benchmark, the rate of change of apparent resistivity at each measuring point and depth at different times is calculated, the spatiotemporal distribution characteristics of salt migration are inverted, the influence radius of brine extraction wells and the dominant direction of salt replenishment are determined, and dynamic monitoring is realized.

[0128] Including,

[0129] Step S4.1: Calculate the rate of change of apparent resistivity;

[0130] With background apparent resistivity matrix Based on this, calculate the first... The rate of change of apparent resistivity at each measuring point and at each depth during the second monitoring:

[0131] ;

[0132] If the apparent resistivity change rate is negative, it indicates that the apparent resistivity has decreased and the salt concentration has increased; if the apparent resistivity change rate is positive, it indicates that the apparent resistivity has increased and the salt concentration has decreased.

[0133] Step S4.2: Quantitative conversion of salt concentration changes;

[0134] According to Archie's law, the electrical conductivity of formation pore water... With formation apparent resistivity The following conditions must be met:

[0135] ;

[0136] Where F is a formation factor determined by porosity and tortuosity, which can be taken in this embodiment. ;

[0137] The mass concentration C of sodium chloride in brine (in g / L) and the conductivity of pore water The approximate empirical relationship (in units of S / m) is as follows:

[0138] ;

[0139] The above approximate empirical relationship applies to NaCl solutions within a certain temperature range. Therefore, the rate of change of apparent resistivity at each measuring point is converted into the relative change in salt concentration. :

[0140] ;

[0141] All measuring points By plotting this as a spatiotemporal distribution map, the spatiotemporal distribution characteristics of salt transport can be obtained;

[0142] like Figure 2 As shown, when a pumping well begins operation, high-salinity brine is extracted from the surrounding area. If low-salinity water is supplied, the apparent resistivity will increase. When high-salinity brine in a poorly permeable layer is displaced and migrates towards the well, the apparent resistivity decreases. By comparing apparent resistivity profiles at different times, the dynamic process of salt migration can be tracked.

[0143] Step S4.3: Determining the radius of influence;

[0144] The maximum apparent resistivity change rate at each horizontal position is extracted from two different cross-sections along the cross-section of the two cables 3. The system scans point by point on both sides of the well, centering on the well, and checks whether the absolute value of the apparent resistivity change rate exceeds a preset threshold. The distance from the farthest measuring point to the production well is recorded as the influence distance in that direction;

[0145] like Figure 1 As shown, the positive influence distance is taken along the cross-section of the east-west cable 3. and negative influence distance The positive influence distance on the cross-section of the north-south cable 3 is respectively and negative influence distance The overall influence radius is taken as the average value of the four directions:

[0146] ;

[0147] In this embodiment, when the farthest influencing measuring point in the east-west direction is 150 m from the production shaft and the farthest influencing measuring point in the north-south direction is 120 m from the production shaft, the comprehensive influence radius is... ;

[0148] Step S4.4: Determining the dominant direction of salt replenishment;

[0149] Compare the average rate of change of apparent resistivity of the two sections at the same time:

[0150] ;

[0151] ;

[0152] Define the dominant direction discrimination index D:

[0153] ;

[0154] Among them, if The dominant direction of salt replenishment is determined to be east-west; if The dominant direction of salt replenishment is determined to be north-south; if The two directions were determined to have similar supply volumes, with no clear advantage in salt supply.

[0155] For example, if the cross-sectional resistivity of the east-west cable 3 changes significantly The cross-sectional changes of the north-south cable 3 were slight. ,but The information indicates that the salt is mainly replenished from the east-west direction, and this information can be used to guide the placement of infill wells.

[0156] Step S5, Interpretation of Results;

[0157] Based on a comprehensive interpretation of the data processing results, the following output is provided:

[0158] Comprehensive influence radius This reflects the effective range of influence of the well underground;

[0159] The dominant direction of salt replenishment, and the index determined by the dominant direction. Quantitative characterization to determine the main supply direction;

[0160] Spatiotemporal diagram of salt transport, with The dynamic spatiotemporal distribution map is drawn based on this, reflecting the speed and path of salt migration.

[0161] The in-situ monitoring method for the extraction effect of brine wells proposed in this application can be widely applied to coastal brine extraction areas, deep underground brine extraction areas, and salt lake brine extraction areas. It is particularly suitable for brine extraction projects that require real-time monitoring of the influence range of pumping wells and the direction of salt migration, optimization of well network layout, and evaluation of production enhancement effects. This invention method requires low equipment investment, is simple to operate, provides abundant monitoring information, and is cost-effective, making it highly valuable for widespread application.

[0162] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An in-situ monitoring method for the extraction effect of brine wells, characterized in that: A cross-shaped electrode array was deployed on the ground centered on the brine extraction well. Before brine extraction, the background apparent resistivity was measured using a Wenner quadrupole device to construct a background apparent resistivity matrix. During brine extraction, apparent resistivity measurements were continuously performed. The rate of change of apparent resistivity at each measuring point was calculated based on the background apparent resistivity, and the spatiotemporal distribution characteristics of salt transport were inverted based on the apparent resistivity changes. The influence radius of the brine extraction well was determined based on the spatial range of apparent resistivity changes in the two cross sections. The dominant direction discrimination index was calculated based on the difference in apparent resistivity changes between the two sections to quantitatively determine the dominant direction of salt replenishment. The process of determining the radius of influence involves extracting the maximum apparent resistivity change rate at each horizontal position from two different cross-sections along the cross-section of the two cables. The system scans point by point from the well to both sides, and judges whether the absolute value of the apparent resistivity change rate exceeds the preset threshold. Will The distance from the farthest measuring point to the production well is recorded as the influence distance in that direction. Along the cross-section of the east-west cable, the positive influence distance is taken respectively. and negative influence distance For the cross-section of north-south cables, the positive influence distance is taken respectively. and The overall influence radius is taken as the average value of the four directions: ； The process of determining the dominant direction of salt replenishment includes comparing the average rate of change of apparent resistivity of two cross sections at the same time and defining the dominant direction discrimination index; the average rate of change of apparent resistivity of the two cross sections at the same time is compared as follows: in, Let be the average rate of change of apparent resistivity along the east-west direction at the k-th monitoring time; Let be the average rate of change of apparent resistivity along the north-south direction at the k-th monitoring time; The position is horizontal; To detect depth; This represents the number of horizontal measurement points. This is the time of the kth monitoring session; The dominant direction discrimination index D is defined as follows: in, The average rate of change of apparent resistivity along the east-west direction. The average rate of change of apparent resistivity along the north-south direction; like The dominant direction of salt replenishment is determined to be east-west; if The dominant direction of salt replenishment is determined to be north-south; if It was determined that the supply amounts from the two directions were similar, and there was no clear advantage in salt supply from any direction.

2. The in-situ monitoring method for the extraction effect of brine extraction wells according to claim 1, characterized in that: The following implementation process is included. Step S1: Electrode placement; Centered on the brine extraction well, a cable is laid on the ground in two mutually perpendicular horizontal directions to form a cross-shaped electrode array; several electrodes are laid at equal intervals on each cable, and the intersection of the cross is located directly above the brine extraction well. Step S2: Measure the apparent resistivity of the background; Before brine extraction, a complete apparent resistivity measurement is performed as a background value. Current is supplied to the underground through the electrode array, the potential difference between each electrode is measured, the background apparent resistivity distribution of the underground medium is calculated, and a background apparent resistivity matrix is ​​constructed. ; Step S3: Dynamic monitoring; During brine extraction, apparent resistivity measurements were continuously performed at set time intervals. Each measurement used the same electrode array and power supply parameters as the background measurements to ensure data comparability, resulting in the following time-series apparent resistivity matrix: Among them, t k Let T be the time of the k-th monitoring session, and T be the total number of monitoring sessions. Step S4: Data processing; With background apparent resistivity matrix Based on this, the apparent resistivity change rate at each measuring point and depth at different times is calculated, the spatiotemporal distribution characteristics of salt migration are inverted, the influence radius of brine extraction wells and the dominant direction of salt replenishment are determined, and dynamic monitoring is achieved. Step S5: Interpretation of results; Based on a comprehensive interpretation of the data processing results, the following output is provided: Comprehensive influence radius This reflects the effective range of influence of the well underground; The dominant direction of salt replenishment, and the index determined by the dominant direction. Quantitative characterization to determine the main supply direction; Spatiotemporal diagram of salt transport, using the relative change in salt concentration. The dynamic spatiotemporal distribution map is drawn based on this, reflecting the speed and path of salt migration.

3. The in-situ monitoring method for the extraction effect of brine extraction wells according to claim 2, characterized in that: Step S2 includes, Step S2.1: Power supply and data acquisition; During the measurement, a Wenner quadrupole device was used, with four adjacent electrodes grouped together, and a stable DC current I was supplied to the ground. At the same time, the potential difference ΔU between the two middle potential electrodes M and N was measured. Step S2.2: Calculate the apparent resistivity; For a Wenner device with an electrode spacing of 'a', the apparent resistivity is calculated using the following formula: Among them, device coefficient Each time the electrode spacing is moved, data is collected sequentially to form a set of apparent resistivity data sequence; Step S2.3, background apparent resistivity matrix; All measurement data for the two cables were compiled into a background apparent resistivity matrix. : in, The position is horizontal; This corresponds to the detection depth; This represents the number of horizontal measurement points. The depth is the number of layers; The aforementioned background apparent resistivity matrix reflects the original distribution of salt in each stratum before mining, serving as a benchmark dataset for subsequent dynamic monitoring.

4. The in-situ monitoring method for the extraction effect of brine extraction wells according to claim 2, characterized in that: Step S3 includes, Step S3.1: Establishing the apparent resistivity profile; Based on the apparent resistivity data of each measurement Based on this, a two-dimensional inversion algorithm is used to convert apparent resistivity data into a real resistivity profile. With horizontal distance as the horizontal axis and detection depth as the vertical axis, a two-dimensional resistivity profile map is drawn by color mark interpolation, which intuitively presents the spatial distribution of resistivity of underground media. Step S3.2, Layer division; Based on the characteristics of the apparent resistivity profile and combined with known geological data, the following stratigraphic levels are identified: The boundary zone between freshwater and brine aquifers, located at the boundary of the monitoring area, has the lowest pore water salinity and the highest apparent resistivity. The brine aquifer has high pore water salinity and moderate apparent resistivity. The weakly permeable layer has small pores, and the pore water has the highest salinity, the strongest conductivity, and the lowest apparent resistivity. Step S3.3: Data change trends and parameter correspondence; By superimposing and comparing the apparent resistivity profiles at different times, the following variation patterns were observed: The apparent resistivity continuously decreases over time, indicating that the salt concentration in the area is continuously increasing and the brine supply is sufficient. The apparent resistivity continuously increases over time, indicating that the salt concentration in the area is continuously decreasing, suggesting freshwater intrusion or brine extraction. The stabilization of resistivity indicates that salt transport at that location has reached a dynamic equilibrium.

5. The in-situ monitoring method for the extraction effect of brine extraction wells according to claim 2, characterized in that: Step S4 includes, Step S4.1: Calculate the rate of change of apparent resistivity; With background apparent resistivity matrix Based on this, calculate the first... The rate of change of apparent resistivity at each measuring point and at each depth during the second monitoring: If the apparent resistivity change rate is negative, it indicates that the apparent resistivity has decreased and the salt concentration has increased; if the apparent resistivity change rate is positive, it indicates that the apparent resistivity has increased and the salt concentration has decreased. Step S4.2: Quantitative conversion of salt concentration changes; According to Archie's law, the electrical conductivity of formation pore water... With formation apparent resistivity The following conditions must be met: Where F is a formation factor determined by porosity and tortuosity. ; Sodium chloride mass concentration C in brine and pore water conductivity The approximate empirical relation is: The above approximate empirical relationship applies to NaCl solutions within a certain temperature range. Therefore, the rate of change of apparent resistivity at each measuring point is converted into the relative change in salt concentration. : All measuring points By plotting this as a spatiotemporal distribution map, the spatiotemporal distribution characteristics of salt transport can be obtained; When a pumping well begins operation, high-salinity brine is extracted from the surrounding area. If low-salinity water is supplied, the resistivity will increase. When high-salinity brine in a poorly permeable layer is displaced and migrates towards the well, the apparent resistivity decreases. By comparing apparent resistivity profiles at different times, the dynamic process of salt migration can be tracked. Step S4.3: Determining the radius of influence; Step S4.4: Determining the dominant direction of salt replenishment.

Images