Mine water recharge reservoir scaling trend prediction, descaling and permeation enhancement method

Abstract

The invention discloses a mine water recharge reservoir scaling trend prediction, scale removal and permeation enhancement method, and the trend prediction method comprises the steps: carrying out the conventional physicochemical index analysis of the water quality of mine water and a monitoring well according to the hydrogeological information of a recharge reservoir, and calculating the scaling trend of the mine water recharge reservoir based on a Retino index method and the relative saturation R.S. The scaling conditions of carbonate, sulfate and silicate are rapidly judged respectively; when scaling occurs, the ion concentration change on a path is revealed through a Transport module and an Equilibrium Phases module in the PHREEQC software, and verification is carried out through a measured value of a monitoring well; and then according to the mineral dissolution precipitation reaction and the percentage of the reservoir rock sample composition, calculating the reaction dose and the void ratio so as to formulate a mine water recharge reservoir permeation enhancement optimization scheme. According to the method, the scaling trend of the mine water recharge reservoir can be effectively predicted, the recharge process is monitored, and continuous operation of deep well recharge sealing work of mine water is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality detection, and particularly relates to a method for predicting the scaling tendency of mine water recharge into a reservoir and removing scale and enhancing permeability. Background Art

[0002] As an important unconventional water resource, mine water is of great significance in the safe production of coal mines and the ecological environment protection. According to statistics, the discharge of mine water accounts for 1% of the total national groundwater resources. The water quality characteristics of mine water are mainly characterized by high TDS (total dissolved solids), high suspended solids, high sulfate, and high Na + as the main features. With the implementation of relevant national and local environmental protection policies, strict requirements have been imposed on the discharge of mine water, and some regions clearly require zero discharge of mine water. Re-injecting and sealing the mine water generated during mineral extraction is a solution. However, during the long-term recharge of high-salt mine water into the reservoir aquifer, water-rock interaction occurs after the mine water is mixed with the reservoir groundwater. At the same time, as the reservoir temperature and pressure change, the solubility of various minerals in the reservoir groundwater changes, thus destroying the ion balance state of easily scaling ions such as Ca 2+ and Mg 2+ and HCO3 - and SO4 2- in the reservoir groundwater. Some of the minerals originally dissolved in the groundwater will precipitate and scale, such as the precipitation and scaling phenomena of minerals such as calcite, gypsum, and quartz. Eventually, problems such as poor permeability of the recharge layer and increased injection pressure will occur, which will greatly affect the sustainable operation of the mine water recharge system. Therefore, it is very necessary to study the scaling tendency during the mine water recharge process. Summary of the Invention

[0003] To solve the above problems, the present invention proposes a method for predicting the scaling tendency of mine water recharge into a reservoir and removing scale and enhancing permeability. By collecting the analysis data of the water samples in the recharge reservoir and combining the Ryzner index method and the relative saturation R.S. method, the scaling tendency of the water quality can be quickly judged. According to the water quality characteristics of the mine water and the monitoring wells, with the help of the PHREEQC numerical simulation software, the changes in the concentrations of various ions on the migration path of the mine water are revealed. Through the mineral dissolution and precipitation reaction and the percentage of the reservoir rock sample composition, the mineral precipitation amount and the reservoir porosity are calculated, so as to formulate a corresponding optimization plan for enhancing the permeability of the mine water recharge reservoir.

[0004] The technical solution adopted by the present invention is as follows:

[0005] In the first aspect, the present invention discloses a method for predicting the scaling tendency of mine water recharge into a reservoir, including the following steps:

[0006] Step S1, obtaining the key hydrogeological parameters of the mine water recharge reservoir;

[0007] Step S2: Set up monitoring wells around the recharge well to obtain the conventional physical and chemical indexes of the water samples in the recharge well and the monitoring wells; Step S3: For the conventional physical and chemical indexes of the water samples in the recharge well and the monitoring wells, use the Ryznar index method to quickly determine the carbonate scaling situation therein, and use the relative saturation R.S. to quickly determine the sulfate and silicate scaling situations therein to obtain the scaling situation; If it is determined that there is no scaling in the water sample, return to Step S2 for continuous monitoring; If there is scaling in the water sample, execute Step S4;

[0008] Step S4: Predict the ion concentrations and scaling amounts at different positions of the recharge reservoir, and analyze the change of the porosity of the recharge reservoir.

[0009] As a further improvement of the present invention, in Step S1, the key hydrogeological parameters include reservoir depth, reservoir medium permeability coefficient, rock density, porosity, reservoir rock mineral composition, and reservoir pressure and temperature.

[0010] As a further improvement of the present invention, in Step S2, the conventional physical and chemical indexes include the temperature, salinity, pH value and ion concentration of the water sample.

[0011] As a further improvement of the present invention, in Step S3, the specific method for rapid prediction is as follows: Step S31: Carbonate scaling situation: Use the Ryznar index method to determine calcite, a representative of carbonates. The formula is as follows:

[0012] RI = 2pH s - pH a (1)

[0013] pH s = -log[Ca 2+ - log[ALK] + K c (2)

[0014] In the formula, pH s is the calculated pH value, pH a is the measured pH value of the geothermal fluid experiment, [ALK] is the molar concentration of HCO3 - ion, [Ca 2+ is the molar concentration of calcium ion, K c —constant;

[0015] Step S32: Sulfate scaling situation: Qualitatively estimate the relative saturation R.S. of gypsum, a representative of sulfates. The formula for the relative saturation R.S. is as follows:

[0016]

[0017] In the formula, ppm Ca is Ca expressed in ppm2+ Content, ppmSO4 is SO4 expressed in ppm 2- Content, logK 石膏 is the solubility product of gypsum;

[0018] Step S33, Silicate scaling situation: It is judged by the relative saturation R.S. of amorphous SiO2 quartz, and the formula is as follows:

[0019]

[0020] In the formula, T is the absolute temperature (K) of the recharge reservoir, and SiO2 is the content (mg / L) of soluble silicon in water.

[0021] As a further improvement of the present invention, in step S4, the ion concentrations and scaling amounts at different positions of the recharge reservoir are predicted, and the change situation of the porosity of the recharge reservoir is analyzed, specifically:

[0022] Step S41, Based on the key hydrogeological parameters of the recharge reservoir obtained in step S1, use the hydrogeochemical numerical simulation software PHREEQC to construct a conceptual model, and generalize the process of the recharge mine water entering the recharge reservoir as a one-dimensional water flow migration process expanding outward with the recharge well as the center;

[0023] Step S42, Establish a one-dimensional convection-dispersion equation to simulate the process of mine water entering the reservoir water, and the equation is as follows:

[0024]

[0025] In the formula: c is the concentration of the solute, mol / L; t is the time; x is the spatial coordinate; v is the groundwater seepage velocity, m / s, representing the overall flow velocity of groundwater in the groundwater layer; D L is the hydrodynamic dispersion coefficient, m 2 / s; is the solute transport caused by convection, mol / (m 3 ·s); is the concentration change caused by dispersion, mol / (m 3 ·s); is the concentration change caused by water-rock reaction, mol / (m 3 ·s);

[0026] Step S43: Based on the conventional physical and chemical index information collected by the recharge well obtained in Step S2, use the Transport module of the hydrogeochemical numerical simulation software PHREEQC to calculate the change in ion concentration caused by the reaction term; use the Equilibrium_Phases module to obtain the mineral saturation index to verify the precipitation and dissolution of calcite, gypsum, and quartz, and use the measured values of the monitoring well and the numerical simulation data for comparison and verification to improve the accuracy of the simulation;

[0027] Step S44: Substitute the ion concentration calculated by simulation in Step S43 into the chemical equation of mineral precipitation-dissolution equilibrium to obtain the reaction mass of mineral precipitation, and then substitute this reaction mass into Formula (6) to calculate the porosity in the recharge reservoir. The formula is as follows:

[0028] M 岩 = ρ 岩 (V 水 ÷ ∈ p (1 - ∈ p )) (6)

[0029] In the formula, M 岩 and ρ 岩 are the mass and density of the rock respectively; V 水 is the volume of the water in the reaction; ∈ p represents the rock porosity.

[0030] On the second aspect, the present invention also discloses a scale removal and permeability enhancement method. Based on the above-mentioned mine water recharge reservoir scaling trend prediction method, the method includes:

[0031] (1) Hydraulic fracturing for permeability enhancement: For low-permeability formations, improve the permeability of the formation through fracturing technology;

[0032] (2) Acidification for permeability enhancement: For carbonate rocks and sandstones containing acid-soluble cements, inject acidic solutions or gases to dissolve the mineral components in the rock and increase the permeability of the formation;

[0033] (3) Injection-pumping-injection cyclic flushing: Regularly inject water in the reverse direction or perform gas-water mixed flushing to remove particulate matter in the fractures.

[0034] The technical effects of the present invention are:

[0035] (1) The present invention sets up recharge wells and monitoring wells, collects water samples from both wells simultaneously, measures the scaling indices of carbonates, sulfates, and silicates in the water samples respectively by the Resnoff method and the relative saturation method, makes a comprehensive and rapid judgment on the scaling situation of the recharge reservoir medium under long-term recharge conditions, so as to realize the regular monitoring of the recharge water; in the case of judging that the recharge reservoir medium has a scaling tendency, uses the conventional physical and chemical index information of the recharge well water sample, simulates the ion changes in the recharge mine water of the recharge reservoir through a hydrogeochemical numerical simulation software, reveals the changes in the concentrations of various ions on the migration path of the mine water, and obtains the scaling amount of the injected mine water and the void changes in the reservoir permeability, and then verifies with the conventional physical and chemical indices of the water sample in the monitoring well to improve the accuracy of the simulation and provide a scientific data basis for the formulation and implementation of the reservoir permeability plan;

[0036] (2) Since the construction of monitoring wells requires high costs, the present invention saves the engineering costs of mine water recharge and ensures the continuous operation of the recharge work by establishing one (instead of multiple) monitoring well, conducting regular monitoring through rapid scaling prediction, combining hydrogeochemical analysis to judge the ion concentration changes and porosity changes, and then verifying with the water sample data of the monitoring well. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0038] Figure 1 is the flow chart of the method for predicting the scaling tendency and removing scale and increasing permeability of the mine water recharge reservoir of the present invention;

[0039] Figure 2 is the schematic diagram of the conceptual model of mine water recharge in the embodiment;

[0040] Figure 3 is the change diagram of the mineral saturation index SI of mine water recharge in the embodiment;

[0041] Figure 4 is the change diagram of the concentrations of various ions in the water samples at different positions in the embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] As Figure 1 shown, the method for predicting the scaling tendency of the mine water recharge reservoir of the present invention specifically includes the following steps:

[0043] Step S1, obtain the key hydrogeological parameters of the recharge reservoir.

[0044] This time, the mine water recharge project in Coal Mine M in Region M was adopted. According to the borehole information, the borehole information of the recharge well and the monitoring well was obtained. The vertical depth of the recharge well and the monitoring well is 1300 m. The distance between the monitoring well and the recharge well is 50 m. The thickness of the recharge reservoir is 199 - 203 m. The permeability coefficient of the reservoir is about 2 - 2.4 m / d. The density of the reservoir rock sample is 2.84 g / cm 3 , the porosity is 3.06%. The main mineral of the reservoir rock is calcite (accounting for 65%). The water level of the monitoring hole is measured to be stable at -31 to -30.5 m, and the reservoir temperature is 40. °C

[0045] Step S2: Obtain the conventional physical and chemical indexes of the water samples from the recharge well and the monitoring well.

[0046] Regularly monitor and obtain water samples and test their conventional physical and chemical indexes, including the pH value of the water sample and the concentration of each ion. The water quality characteristics of the Ordovician limestone water and the mine water are mainly high sulfate water dominated by SO4 2- , Ca 2+ , Na + +K + . The two waters have similar characteristics and the mine water is better than the reservoir groundwater. The specific physical and chemical indexes of the water samples are shown in Table 1.

[0047] Table 1 Conventional Physical and Chemical Indexes of Mine Water and Reservoir Water in Coal Mine M in the East

[0048]

[0049] Step S3: Use the conventional physical and chemical indexes of the water samples in the recharge well and adopt the Ryzner index method and relative saturation R.S. to judge the scaling situation.

[0050] Step S31: Predict carbonate scaling, and the representative substance is calcium carbonate in calcite. The formula of the Ryzner index method is as follows:

[0051] RI = 2pH s -pH a (1)

[0052] pH s = -log[Ca 2+ -log[ALK]+K c (2)

[0053] In the formula: pH s —Calculated pH; pH a —Experimentally measured pH value of the recharge reservoir water; [ALK]—Molar concentration of HCO3 - ion (mol / L); [Ca 2+ —Molar concentration of calcium ion (mol / L); K c —Constant.

[0054] Substitute the data in Table 1 into the above formula for calculation to obtain the RI index, and make a scaling judgment according to Table 2:

[0055] Table 2 Calcium carbonate scaling trend discrimination table

[0056] Rezno Index (RI) Scaling tendency RI < 4.0 Very severe 4.0 < RI < 5.0 Severe scaling 5.0 < RI < 6.0 Moderate scaling 6.0 < RI < 7.0 Slight scaling RI > 7.0 No scaling

[0057] Step S32. Predict sulfate scaling: Mine water usually has the characteristic of high sulfate, and the generation trend of calcium sulfate scale in its recharge into the reservoir can be qualitatively estimated by the relative saturation R.S. of gypsum (CaSO4·2H2O). The relative saturation R.S. is defined as follows:

[0058]

[0059] In the formula: ppm Ca—the content of Ca expressed in ppm 2+ content; ppmSO4—the content of SO4 expressed in ppm 2- content; logK 石膏 —Solubility product of gypsum, calculated by converting according to the relative solids TDS (expressed in ppm) and temperature.

[0060] Basis for judging sulfate scaling trend: When the R.S. of gypsum ≤ 1, it means unsaturated and no gypsum scale will be formed; when R.S. > 1, it means supersaturated and sulfate scale will be generated.

[0061] Step S33. Predict silicate scaling: It is judged by the magnitude of the relative saturation R.S. of amorphous SiO2 quartz. The formula is as follows:

[0062]

[0063] Basis for judging silicate scaling trend: When R.S. ≤ 1, no silicate scale is formed; when R.S. > 1, it means supersaturated and silicate scale will be generated.

[0064] In this embodiment, the silicate content in the water sample composition is relatively low. Therefore, there is no need to predict the silicate scaling trend, and the final scaling situation is shown in Table 3. In Table 3, the water samples of the injection well and the monitoring well are the mixed water of mine water and the original reservoir water.

[0065] Table 3 Scaling trend prediction

[0066]

[0067] Step S4. Calculate the scaling amount at different positions of the recharge reservoir and analyze the change of its porosity.

[0068] Step 41: In the PHREEQC software, use the key hydrogeological parameters obtained in Step S1, that is, the borehole information of the recharge well and the monitoring well, including the reservoir depth, the permeability coefficient of the reservoir medium, the rock density, the porosity, and the information of the reservoir rock mineral composition, pressure and temperature, to construct a conceptual model, and generalize the process of the recharged mine water entering the reservoir as a one-dimensional water flow migration process expanding outward centered on the recharge well, as shown in Figure 2 shown. In the figure, 1D refers to one-dimensional, and r is the diffusion radius of mineral ions centered on the recharge well.

[0069] Step S42: Establish a one-dimensional advection-dispersion equation to simulate the process of solutes in mine water entering the reservoir water. The equation is as follows:

[0070]

[0071] In the formula: c is the concentration of the solute (unit: mol / L), t is the time, x is the spatial coordinate, v is the groundwater seepage velocity (unit: m / s), representing the overall flow velocity of groundwater in the groundwater layer, D L is the hydrodynamic dispersion coefficient (unit: m 2 / s);

[0072] is the solute transport caused by advection, mol / (m 3 ·s); is the concentration change caused by dispersion, mol / (m 3 ·s); is the concentration change caused by water-rock reaction, mol / (m 3 ·s).

[0073] Step S43: Use the conventional physical and chemical index information of the recharge well and the monitoring well obtained in Step S2, and use the Transport module of the hydrogeochemical numerical simulation software PHREEQC to calculate the ion concentration change caused by the reaction term using formula (5). Use the Equilibrium_Phases module to obtain the mineral saturation index (SI) to verify the precipitation and dissolution of calcite and gypsum. In this step, the numerical simulation obtains the mineral saturation index SI, which is an index used to measure whether a certain mineral in the aqueous solution reaches the saturation state. When SI > 0.5, it means that a certain mineral is in a saturated state in the groundwater and will precipitate from the water; otherwise, it is in a dissolved state. When SI is between -0.5 and 0.5, it is in a dissolution equilibrium state. As shown in Figure 3As shown, the mineral saturation index SI of calcite > 0.5, which indicates that calcite precipitation occurs, consistent with the scaling situation in step S3 above. The calcite obtained from this simulation is in a precipitation state, while gypsum and sodium salts are in a dissolution equilibrium state. Comparing the measured values of the monitoring wells with the numerical simulation results, as shown in Table 4, the smallest simulation error is for SO4 2- at 0.14%, and the largest error is for HCO3 - . The error between the measured values of the monitoring wells and the numerical simulation results is less than 5%. It can be seen that the numerical simulation results of this embodiment have high accuracy.

[0074] Table 4 Error between Measured Values of Monitoring Wells and Numerical Simulation Results

[0075]

[0076] Error = |Measured Value - Simulated Value| / Measured Value * 100%

[0077] According to the simulation results, the changes in the concentrations of various ions within the range from the recharge well to the monitoring well are obtained, as Figure 4 shown. From Figure 4 , it can be seen that along the distance from the recharge well to the monitoring well, the concentrations of Ca 2+ , Mg 2+ , Na + , SO4 2- , Cl - first decrease and then increase. Among them, within the distance of 0 - 30m, the concentration of Ca 2+ decreases the fastest, the concentration of Na + decreases the most gently, and the concentration of HCO3 - is overall in an upward stage.

[0078] Step S44: Substitute the ion concentrations calculated by simulation in step S43 into the chemical equation of mineral precipitation - dissolution equilibrium (see Table 5) to obtain the reaction mass M of mineral precipitation 岩 ;

[0079] Table 5 Common Dissolution - Precipitation Reactions in Mine Water Recharge

[0080]

[0081] **T(K) = °C + 273.15

[0082] Then substitute this mineral mass into formula (6) to calculate the change in porosity in the recharge reservoir. The formula is as follows:

[0083] M 岩 = ρ 岩 (V 水 ÷ ∈ p (1 - ∈ p )) (6)

[0084] Where: M 岩 and ρ 岩 are the mass and density of the rock respectively; V 水 is the volume of water involved in the reaction; ∈ p is the porosity of the rock.

[0085] The volume of the hydrochemical simulation reaction is calculated based on 1 L of water. The range of the change in mineral mass is limited to the area within a radius of 0.5 m from the well. The mass of the mineral precipitation is calculated according to the mineral precipitation-dissolution equilibrium reaction and the percentage of the mineral in the composition of the in-situ reservoir rock sample. The mass of the calcium carbonate precipitation generated is 38.7 mg. In this embodiment, the measured porosity is corresponding to the porosity. According to formula (6), it is calculated that the maximum porosity will be reduced to 1.84%. The porosity (porosity) before recharge is 3.06%. This kind of mineral precipitation transformation may lead to an increase in the degree of reservoir heterogeneity. The porosity is used to characterize the permeability of the recharge layer. The smaller the porosity, the smaller the permeability.

[0086] As Figure 4 shown, from the effect of this simulation, it can be found that the precipitation occurring during the mine water recharge mainly concentrates in the area centered on the recharge well, and the influence is relatively small. However, the influence of scaling needs to be considered in actual engineering. Therefore, the present invention also discloses a method for scale removal and permeability enhancement, which specifically includes:

[0087] Hydraulic fracturing for permeability enhancement: For low-permeability formations, the permeability of the formation is increased through fracturing technology;

[0088] Acidification for permeability enhancement: For carbonate rocks, the mineral components in the rock are dissolved by injecting acidic solutions (gases) to increase the permeability of the formation;

[0089] Injection-withdrawal-injection cycle: Periodic backwashing, regular reverse water injection or gas-water mixed flushing to remove particulate matter in the fractures.

[0090] By setting up a recharge well and a monitoring well, the present invention can quickly judge the scaling situation of the water sample, so as to realize the regular monitoring of the mine water recharge process to ensure the smooth progress of the recharge work; when it is judged that scaling occurs, the ion change situation, precipitation mass and porosity of the recharge reservoir water sample are obtained by means of hydrogeochemical numerical simulation analysis, which can provide scientific guidance for subsequent permeability enhancement operations. And the routine physical and chemical indexes of the water sample are obtained through the monitoring well to verify the data of the hydrogeochemical numerical simulation analysis to ensure the accuracy of the simulation.

[0091] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. All various changes that can be made within the knowledge of those skilled in the art without departing from the gist of the present invention are within the scope of protection of the claims of the present invention.

Claims

1. A method for predicting the scaling trend of a mine water recharge reservoir, characterized in that: The following steps are involved: Step S1, obtaining key hydrogeological parameters of the mine water recharge reservoir; Step S2, setting monitoring wells around the recharging wells, and obtaining conventional physical and chemical indicators of water samples from the recharging wells and monitoring wells; Step S3: for the conventional physical and chemical indicators of the water samples in the recharging well and the monitoring well, the carbonate scaling condition is quickly determined by the Reznor index method, and the sulfate and silicate scaling conditions are quickly determined by the relative saturation RS to obtain the scaling conditions; if it is determined that the water sample does not have scaling, return to step S2 to continue monitoring; if the water sample has scaling, execute step S4; Step S4: predicting the ion concentration and scaling amount at different positions of the recharged reservoir, and analyzing the change of the porosity of the recharged reservoir.

2. The method for predicting reservoir scaling trend of mine water reinjection according to claim 1, characterized in that: In step S1, the key hydrogeological parameters include reservoir depth, reservoir medium permeability, rock density, porosity, reservoir rock mineral composition, and reservoir pressure and temperature.

3. The method for predicting reservoir scaling trend of mine water reinjection according to claim 1, characterized in that: In step S2, the conventional physical and chemical indicators include temperature, mineralization, pH value and ion concentration of the water sample.

4. The method for predicting reservoir scaling trend of mine water reinjection according to claim 1, characterized in that: In step S3, the method of rapid prediction is specifically as follows: Step S31, carbonate scaling: the Reznor index method is used to determine the carbonate representative calcite, and the formula is as follows: RI=2pH s -pH a (1) pH s =-log[Ca 2+ ]-log[ALK]+K c (2) Where, pH s is the calculated pH value, pH a It is the pH value measured by geothermal fluid experiment, [ALK] is HCO3 - Ion molar concentration, [Ca 2+ ] is the molar concentration of calcium ions, K c -constant; Step S32, sulfate scaling: qualitatively estimate the relative saturation RS of gypsum, a representative of sulfate. The relative saturation RS formula is as follows: Where ppm Ca is Ca expressed in ppm 2+ Content, ppmSO4 is SO4 expressed in ppm 2- Content, logK 石膏 is the solubility product of gypsum; Step S33, silicate scaling: judged by the relative saturation RS of amorphous SiO2 quartz, the formula is as follows: Where T is the absolute temperature of the recharged reservoir (K), and SiO2 is the content of soluble silicon in water (mg / L).

5. The method for predicting reservoir scaling trend of mine water reinjection according to claim 1, characterized in that: In step S4, the ion concentration and scaling amount at different positions of the recharged reservoir are predicted, and the change of the porosity of the recharged reservoir is analyzed, specifically: Step S41: Based on the key hydrogeological parameters of the recharge reservoir obtained in step S1, a conceptual model is constructed using the hydrogeochemical numerical simulation software PHREEQC, and the process of the recharged mine water entering the recharge reservoir is generalized as a one-dimensional water flow migration process extending outward from the recharge well as the center; Step S42: Establish a one-dimensional convection-diffusion equation to simulate the process of mine water entering reservoir water. The equation is as follows: Where: c is the concentration of the solute, mol / L; t is the time; x is the spatial coordinate; v is the groundwater seepage velocity, m / s, which represents the overall flow velocity of groundwater in the groundwater layer; D L is the hydrodynamic dispersion coefficient, m 2 / s; is the solute transport caused by convection, mol / (m 3 s); is the concentration change caused by diffusion, mol / (m 3 s); is the concentration change caused by water-rock reaction, mol / (m 3 s); Step S43: Based on the conventional physical and chemical index information collected from the recharge wells obtained in step S2, the Transport module of the hydrogeochemical numerical simulation software PHREEQC is used to calculate the change in ion concentration caused by the reaction term; the Equilibrium_Phases module is used to obtain the mineral saturation index to verify the precipitation and dissolution of calcite, gypsum and quartz, and the measured values ​​of the monitoring wells and the numerical simulation data are used for comparison and verification to improve the accuracy of the simulation; Step S44: Substitute the ion concentration calculated by simulation in step S43 into the equilibrium chemical equation of mineral precipitation dissolution to obtain the reaction mass of mineral precipitation generation, and then substitute the reaction mass into formula (6) to calculate the porosity in the recharged reservoir, which is as follows: M 岩 =ρ 岩 (V 水 ÷∈ p (1-∈ p )) (6) Where M 岩 and ρ 岩 are the mass and density of the rock respectively; V 水 is the volume of water in the reaction; ∈ p Represents the porosity of rock.

6. A method for descaling and increasing permeability, based on the method for predicting scaling trend of mine water recharge reservoir according to any one of claims 1 to 5, characterized in that: The method comprises: (1) Hydraulic fracturing to increase permeability: For low permeability formations, the permeability of the formation is increased through hydraulic fracturing technology; (2) Acidification and permeability enhancement: For carbonate rocks and sandstones containing acid-soluble cements, acidic solutions or gases are injected to dissolve the mineral components in the rocks and increase the permeability of the formation; (3) Injection-extraction-injection cycle flushing: Regularly reverse water injection or air-water mixed flushing to remove particulate matter in the cracks.

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