A method for predicting the influence range of a groundwater circulation well

Abstract

The application discloses a kind of prediction methods of groundwater circulation well influence range, it is related to groundwater pollution remediation technical field, including the following steps: determining the groundwater background flow rate when research area circulation well is not operated;Run circulation well, obtain the groundwater circulation flow rate of circulation well;According to the medium condition where groundwater is located, select permeability coefficient;Obtain the groundwater flow when circulation well is operated;According to permeability coefficient, flow, time, monitoring well site and circulation flow rate, multiple nonlinear fitting is carried out, and fitting equation is obtained;The minimum circulation speed is determined using boundary condition formula, and the maximum influence radius of circulation well is obtained;Establish the finite element numerical model of research area circulation well, according to the maximum influence radius of circulation well, estimate the maximum influence area and maximum influence volume of circulation well.The determination method of the application is convenient to detect the change condition of circulation flow rate at different time and different sites, and is suitable for field and simulation research in groundwater seepage process.

Description

Technical Field

[0001] This invention relates to the field of groundwater pollution remediation technology, and in particular to a method for predicting the impact range of groundwater circulation wells. Background Technology

[0002] In recent years, with the development of industrial and agricultural production and urbanization in my country, various organic and inorganic pollutants and pathogenic microorganisms have entered groundwater, causing varying degrees of pollution to groundwater resources. In some cities, even carcinogenic, mutagenic, and teratogenic pollutants have been detected in groundwater. Once groundwater resources are polluted, it not only restricts safe industrial and agricultural production but also seriously threatens human health, potentially leading to cancer. Therefore, groundwater pollution control is urgently needed.

[0003] Groundwater Circulation Wells (GCWs), as an emerging in-situ remediation technology, creates a three-dimensional circulation pattern in groundwater, generating pressure differential disturbances. This increases the radius of influence of groundwater and accelerates the transport of pollutants, allowing the remediation agent injected into the well to quickly reach the target location, thereby improving the removal efficiency of pollutants and achieving in-situ remediation of groundwater. With the development of GCW remediation technology, its remediation function has gradually evolved from a single-drive approach to being coupled with novel remediation technologies such as in-situ chemical oxidation, electrochemical remediation, and bioremediation. This can effectively shorten remediation time, improve remediation efficiency, and achieve comprehensive groundwater management.

[0004] like Figure 1 As shown, a circulating well includes a main circulating well and several rows of monitoring wells. The main circulating well consists of five parts: an inner well, an outer well, an aeration pump, an upper screen pipe, and a lower screen pipe. The circulating well is formed by nesting the inner and outer well pipes. Currently, my country's groundwater circulating well remediation technology is still in the exploratory stage. Most related research is limited to indoor experiments and numerical simulations, and there are no mature application cases of GCW remediation technology. When circulating wells are applied to actual remediation projects, it often involves the optimization design of process parameters such as circulation efficiency and degradation efficiency. The main technical problems to be solved are: three-dimensional flow field calculation and fine characterization, calculation of the radius of influence of remediation indication, and prediction of the remediation area. The key to these problems is to clarify the influence mechanism of various groundwater circulation parameters on the in-situ remediation range of the circulating well.

[0005] Most current groundwater flow field simulation studies rely on circulating well seepage models, using numerical calculations to obtain analytical drawdown, or employing simulation software with traditional finite difference methods, finite element methods, boundary element methods, and particle tracking methods to establish GCW flow field numerical models to obtain accurate circulating well influence radii. Furthermore, due to the characteristic of circulating wells driving solute transport within aquifers, and the ease of collecting concentration data within the wellbore, circulating well tracer tests possess irreplaceable advantages in characterizing the range of solute transport in actual aquifers. Based on the convection-dispersion equation theory, many scholars have established numerous analytical and numerical models to study radial solute transport laws. Sutton et al. (2000), who first proposed the concept of circulating well tracer tests (DFTT), solved the solute transport model under steady-flow conditions in circulating wells, transforming three-dimensional radial axisymmetric solute transport into a one-dimensional convection-dispersion case along the flow tube. Subsequently, more and more scholars have considered different hydrogeological constraints to establish new reaction-transport models, extending DFTT and improving the accuracy of solute transport models.

[0006] Due to the divergent and convergent nature of the flow field in circulating wells, which exhibits multiphase flow characteristics, the numerical models mentioned above face significant challenges, such as numerical dispersion, numerical oscillation, and convergence. Existing groundwater circulating well migration models often neglect numerous actual influencing factors, and relying solely on seepage models cannot clearly reflect the changes in the circulating well's influence range under the combined effects of aquifer factors and well process parameters. Furthermore, during field tracer tests of circulating wells, the high concentration of tracer required for instrument detection necessitates the addition of large quantities of tracer to ensure accuracy, increasing economic costs and potentially affecting groundwater quality in the region due to excessive concentrations.

[0007] In summary, current technology does not provide a method for predicting the influence range of groundwater circulation wells without adding additional tracers, while considering the influence of different aquifer factors. Therefore, it is necessary to rationally solve the problem of predicting the influence radius of circulation wells from the perspective of combining theory with practical application. Summary of the Invention

[0008] This invention provides a method for predicting the influence range of groundwater circulation wells, which can solve the problems existing in the prior art.

[0009] This invention provides a method for predicting the influence range of groundwater circulation wells, comprising the following steps:

[0010] The background groundwater velocity in the study area when the circulating wells were not in operation was measured using a velocity probe. ;

[0011] Run the circulating well and record different times. TDifferent monitoring well sites L The groundwater circulation velocity is obtained from the groundwater circulation velocity of the circulation well. u ;

[0012] Select the permeability coefficient based on the condition of the groundwater medium. K ;

[0013] Using a flow meter to obtain the groundwater flow rate during the operation of a circulating well Q ;

[0014] Based on permeability coefficient K ,flow Q ,time T Monitoring well sites L and circulation flow rate u Perform multivariate nonlinear fitting to obtain the fitting equation;

[0015] Determine the groundwater circulation velocity u The critical value is used to determine the minimum cycle speed using boundary condition equations. Based on minimum cycle speed The maximum influence radius of the circulating well is obtained from the fitted equation. ;

[0016] To simulate the groundwater seepage process in the study area, a finite element numerical model of the circulating wells was established. The maximum influence radius of the circulating wells was then used in the finite element numerical model. Estimate the maximum affected area of ​​the circulating well. S and maximum impact volume V .

[0017] Preferably, the fitting equation is as follows:

[0018]

[0019] In the formula, All are constant terms. for t time L The circulation velocity at that location.

[0020] The boundary condition is expressed as follows:

[0021] .

[0022] Preferably, the maximum impact area of ​​the circulating well is estimated according to the area estimation formula. S The area estimation formula is shown below:

[0023]

[0024] In the formula, S This represents the maximum impact area of ​​the circulating well.V The maximum impact volume of the circulating well. The maximum radius of influence of the circulating well. h This is the distance between the opening of the upper sieve tube and the opening of the lower sieve tube.

[0025] Preferably, the maximum impact volume of the circulating well is estimated according to the volume estimation formula. V The volume estimation formula is shown below:

[0026] .

[0027] Preferably, the velocity probe is installed inside the monitoring well, and the temperature difference signal is converted into an electrical signal by a transmitter to obtain the groundwater circulation velocity at the monitoring well site.

[0028] Preferably, the water level of the main well of the circulation well is measured using a water level gauge.

[0029] Preferably, the circulating well is operated by an aeration pump.

[0030] Preferably, the flow meter is installed inside the main well of the circulation well.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) The measurement method proposed in this invention does not require the addition of tracers to the groundwater circulation well, which facilitates the detection of changes in circulation velocity at different times and locations, and is suitable for field and simulation studies of groundwater seepage processes.

[0033] (2) The prediction method proposed in this invention is simple to operate, requiring only the recording of the permeability coefficient. K ,flow Q ,time T Monitoring well sites L and circulation flow rate u By performing nonlinear fitting on these parameters, the influence range of groundwater circulation wells can be predicted using simple calculation formulas without involving complex data processing, making it easy to solve.

[0034] (3) The present invention can effectively handle solute transport under various flow conditions and provide a reference for the reasonable prediction of the maximum influence radius of circulating wells. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of circulating well technology;

[0037] Figure 2 This is a flowchart illustrating the technical process of a method for predicting the influence range of a groundwater circulation well according to the present invention.

[0038] Figure 3 This is a flowchart of a method for predicting the influence range of a groundwater circulation well according to the present invention;

[0039] Figure 4 A simplified structural diagram of the main view of the sand box simulation tank and the circulating well operation;

[0040] Figure 5 A simplified structural schematic diagram of the sand box simulation tank and the top view of the circulating well operation;

[0041] Figure 6 This is a schematic diagram of the circulating flow field in a circulating well according to an embodiment of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Reference Figure 2 and Figure 3 This invention discloses a method for predicting the influence range of groundwater circulation wells, comprising the following steps:

[0044] Step 1: Use a velocity probe to measure the background groundwater velocity in the study area when the circulating wells are not in operation. .

[0045] In this embodiment, a velocity probe is installed inside multiple monitoring wells. The velocity probe can convert the temperature difference signal into an electrical signal through a transmitter and send it to a computer for analysis and calculation to obtain the groundwater circulation velocity at the monitoring well location.

[0046] Step 2: Run the circulation well and record different times. T Different monitoring well sites L The groundwater circulation velocity is obtained by measuring multiple circulation velocities of the groundwater during the operation of the circulation well. u .

[0047] In this embodiment, a water level gauge is installed inside the main well of the circulation well to measure the water level. An aeration pump operates the circulation well. The aeration pump creates negative pressure in the lower part of the inner well, and then the screen pipes at the top and bottom of the outer well are connected to construct a three-dimensional circulating flow field around it.

[0048] Step 3: Refer to Table 1 and select the permeability coefficient based on the different flow conditions of groundwater in different media. K .

[0049] Table 1: Permeability Coefficient Range for Different Soil Types

[0050]

[0051] Step 4: Install the flow meter inside the main shaft of the circulation well to obtain the groundwater flow rate during the operation of the circulation well. Q .

[0052] Step 5: Based on the permeability coefficient K ,flow Q ,time T Monitoring well sites L and the corresponding circulation velocity u By performing multivariate nonlinear fitting, the fitting equation is obtained:

[0053]

[0054] In the formula, All are constant terms. for t time L The circulation velocity at that location.

[0055] Step 6: Determine the groundwater circulation velocity u The critical value is used to determine the minimum cycle speed using boundary condition equations. ,

[0056] The boundary condition equation is as follows:

[0057] .

[0058] Minimum cycle speed Substituting into the fitted equation, the maximum radius of influence of the circulating well is obtained. .

[0059] Step 7: Simulate the groundwater seepage process in the study area and establish a COMSOL finite element numerical model of the study area. The model can assume that the groundwater circulation well flow is an approximately elliptical flow field, based on the maximum influence radius of the circulation well. This allows for further estimation of the maximum affected area of ​​the circulating well. S and maximum impact volume V .

[0060] Estimate the maximum impact area of ​​the circulating well using the area estimation formula. S The area estimation formula is shown below:

[0061]

[0062] In the formula, S This represents the maximum impact area of ​​the circulating well. V The maximum impact volume of the circulating well. The maximum radius of influence of the circulating well. h This is the distance between the opening of the upper sieve tube and the opening of the lower sieve tube.

[0063] Estimate the maximum impact volume of the circulating well using a volume estimation formula. V The volume estimation formula is shown below:

[0064] .

[0065] Example

[0066] Reference Figure 4 and Figure 5 The circulating well model in this invention simulates a real circulating well, and is a scaled-down version of the actual circulating well, capable of circulating groundwater. The driving mechanism is a peristaltic pump, providing the driving force for pumping and injecting water. The circulating well includes at least a pumping pipe and an injection pipe. Several perforated screens are provided at the bottom of the well body, allowing groundwater to enter the well body through these screens. The pumping pipe penetrates the sealing plate and pumps the groundwater from the bottom of the well body, injecting it into the upper part of the well body. Several perforated screens, communicating with the outside, are provided in the upper part of the well body, allowing the injected water to flow into the gravel through these screens. The water flowing out of the screens flows downwards and at an angle due to gravity. Because the peristaltic pump drives the pumping pipe to extract groundwater and creates negative pressure, the groundwater in the gravel accumulates at the bottom of the circulating well due to the negative pressure and re-enters the bottom of the circulating well through the perforated screens, forming a groundwater circulation.

[0067] Turn on the peristaltic pump, run the circulating well simulation experiment equipment, and record the circulation flow rate at different times and locations. u The sand box of the circulating well simulation equipment is filled with fine sand, with a permeability coefficient K = 0.726 cm / min. The flow rate displayed by the drive pump is the flow rate Q during the operation of the circulating well simulation equipment. Using the above-obtained circulation parameters (L, t, K, Q) and their corresponding circulation velocities... u Multivariate nonlinear fitting was performed, and the obtained cyclic parameters and cyclic speeds are shown in Table 2 below.

[0068] Table 2: Circulation Parameters of the Circulation Well Experiment Simulation Equipment

[0069]

[0070] Select P1-P11 to establish the multivariate nonlinear regression equation:

[0071]

[0072]

[0073] Multiple regression model prediction: The multiple regression model was tested using P12, as shown in Table 3 below. It can be seen that the multiple regression model can predict the circulation velocity of the circulation well relatively well.

[0074]

[0075] Determining the minimum cycle rate using boundary condition equations ,Will Substituting into the fitted equation obtained above, the maximum influence radius of the circulating well at a certain moment is obtained. .

[0076] COMSOL finite element numerical model shows the groundwater seepage process in aquifers, such as... Figure 6 As shown, assuming the groundwater circulation flow in the well is approximately elliptical, the maximum influence radius of the circulation well is calculated. This allows for further estimation of the maximum affected area of ​​the circulating well. S and maximum impact volume V .

[0077] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0078] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for predicting the influence range of a groundwater circulation well, characterized in that, Includes the following steps: The background groundwater velocity in the study area when the circulating wells were not in operation was measured using a velocity probe. ; Run the circulating well and record different times. T Different monitoring well sites L The groundwater circulation velocity is obtained from the groundwater circulation velocity of the circulation well. u ; Select the permeability coefficient based on the condition of the groundwater medium. K ; Using a flow meter to obtain the groundwater flow rate during the operation of a circulating well Q ; Based on permeability coefficient K ,flow Q ,time T Monitoring well sites L and circulation flow rate u Perform multivariate nonlinear fitting to obtain the fitting equation; Determine the groundwater circulation velocity u The critical value is used to determine the minimum cycle speed using boundary condition equations. Based on minimum cycle speed The maximum influence radius of the circulating well is obtained from the fitted equation. ; To simulate the groundwater seepage process in the study area, a finite element numerical model of the circulating wells was established. The maximum influence radius of the circulating wells was then used in the finite element numerical model. Estimate the maximum affected area of ​​the circulating well. S and maximum impact volume V ; The fitting equation is shown below: In the formula, All are constant terms. for t time L The circulation velocity at the location; The boundary condition is expressed as follows: 。 2. The method for predicting the influence range of a groundwater circulation well as described in claim 1, characterized in that, Estimate the maximum impact area of ​​the circulating well using the area estimation formula. S The area estimation formula is shown below: In the formula, S This represents the maximum impact area of ​​the circulating well. V The maximum impact volume of the circulating well. The maximum radius of influence of the circulating well. h This is the distance between the opening of the upper sieve tube and the opening of the lower sieve tube.

3. The method for predicting the influence range of a groundwater circulation well as described in claim 1, characterized in that, Estimate the maximum impact volume of the circulating well using the volume estimation formula. V The volume estimation formula is shown below: 。 4. The method for predicting the influence range of a groundwater circulation well as described in claim 1, characterized in that, The velocity probe is installed inside the monitoring well. The temperature difference signal is converted into an electrical signal by a transmitter to obtain the groundwater circulation velocity at the monitoring well site.

5. The method for predicting the influence range of a groundwater circulation well as described in claim 1, characterized in that, The circulating well is operated by an aeration pump.

6. The method for predicting the influence range of a groundwater circulation well as described in claim 1, characterized in that, The flow meter is installed inside the main shaft of the circulation well.

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