Mine water recharge multi-field coupling simulation experiment system and method

Abstract

The application discloses a kind of mine water recharging multi-field coupling simulation experiment system and method, it is related to mine water utilization technical field.The experimental system includes reservoir simulation box, mine water supply system, production water collection and detection system and microbial culture and injection system;Reservoir simulation box is filled with reservoir medium area, cooperate pressure pump, temperature control jacket simulation deep formation pressure and temperature, mine water supply system provides controllable mine water, microbial culture and injection system injects specific microorganism, and production water collection and detection system detect water quality and microbial characteristics.The experimental method is simulated reservoir condition, injects mine water and microorganism, monitors the change of multiple parameters, establishes composite jamming mathematical model and multi-field coupling partial differential equation.The application can realize stress field, hydrodynamic field and so on five-field coupling simulation, provides technical means for groundwater environment evolution and permeability mechanism research.

Description

Technical Field

[0001] This invention relates to the field of mine water utilization technology, specifically to a simulation experimental system and method for multi-field coupling effect of mine water reinjection. Background Technology

[0002] In the process of coal mine safety production, mine water, as a byproduct, can easily cause harm to the ecological environment if discharged directly without treatment. Deep mine water reinjection has become an emerging treatment method due to its high cost-effectiveness, low cost, and strong operability, and more coal mines are expected to implement this project in the future. With the advancement of deep mine water reinjection projects, the hydrogeological effects it drives have become a key research focus and challenge, with multi-field coupling effects being the core of the analysis. The high temperature and pressure, complex fluid activity, hydrogeochemical behavior, and microbial activity of the deep geological environment are key factors restricting reservoir systems. However, due to the complexity of deep geological conditions, the difficulty of investigation, and the high cost of borehole monitoring, it is difficult to obtain field data. Therefore, multi-field coupling simulation experiments have become an important approach to solving related problems. Existing indoor simulation devices have significant shortcomings: they mostly rely on reaction vessels such as water-water mixing and water-rock interaction reactors, which isolate the in-situ geological field effects and only consider single factors or changes in some indicators; groundwater recharge leaching column tests focus on shallow recharge issues and do not involve the multi-field effects of long-term deep recharge; while devices such as water-rock reaction vessels consider temperature and pressure factors, they ignore the overall reservoir characteristics and the influence of microorganisms. Therefore, there is an urgent need to develop a realistic indoor simulation system to provide technical means for evaluating multi-field coupling effects and studying related mechanisms. Summary of the Invention

[0003] The purpose of this invention is to propose a simulation experimental system and method for multi-field coupling effects of mine water reinjection. Addressing the shortcomings of existing technologies in simulating multi-field coupling, ignoring microbial influences, and being detached from deep-seated scenarios, this invention develops a realistic indoor simulation system through pressure and temperature control in a reservoir simulation chamber, a microbial injection system, and multi-parameter monitoring. This system evaluates multi-field coupling effects and provides a technical means for studying groundwater environmental evolution and permeability mechanisms.

[0004] The technical solution adopted by this invention is as follows: Firstly, this invention proposes a simulation experimental system for multi-field coupling effect of mine water reinjection, including a reservoir simulation box, comprising a box body, a reservoir medium filling area in the middle of the box body for placing the reservoir medium; water-proof layers are provided above and below the reservoir medium filling area, and rubber sleeves are provided above the upper water-proof layer and below the lower water-proof layer; temperature control jackets are provided above the upper rubber sleeve and below the lower rubber sleeve, wherein a pressure piston is provided between the upper temperature control jacket and the upper rubber sleeve, and the pressure piston is connected to a pressure pump pipeline for applying pressure to the reservoir medium; The mine water supply system includes a raw water storage tank and a flow pump. The raw water storage tank is connected to the flow pump pipeline, and the flow pump is connected to the reservoir medium filling area pipeline. The produced water collection and testing system includes a produced water collection tank and a water quality analyzer. The produced water collection tank is connected to the reservoir medium filling area pipeline, and the water quality analyzer is connected to the produced water collection tank pipeline. The microbial culture and injection system includes a microbial storage tank and a microbial injection pump. The microbial storage tank is connected to the microbial injection pump pipeline, and the microbial injection pump is connected to the reservoir medium filling area pipeline.

[0005] As a further improvement of the present invention, the reservoir medium filling area is divided into a first medium zone, a second medium zone, and a third medium zone, with a water-proof layer between each medium zone, and reservoir media of the same or different lithologies placed in each medium zone; the mine water supply system also includes a graded filtration unit, which includes a first filter, a second filter, and a third filter connected in series from bottom to top, each of which contains a filter membrane, with the pore size of the three filter membranes decreasing sequentially to form a three-stage filtration; one end of the first filter is connected to the raw water storage tank pipeline, and the other end is connected to a first flow pump. The first medium zone is connected to the second medium zone via a pipeline; the second filter is connected to the second medium zone via a second flow pump, and the third filter is connected to the third medium zone via a third flow pump; the effluent collection and testing system includes three outlet pipes, one end of which is connected to the first medium zone, the second medium zone, and the third medium zone respectively, and the other end of which is connected to the first water sample collection tank, the second water sample collection tank, and the third water sample collection tank respectively. The first water sample collection tank, the second water sample collection tank, and the third water sample collection tank are connected to the water quality analyzer pipeline; each medium zone is equipped with a temperature sensor, which is connected to a temperature controller.

[0006] As a further improvement of the present invention, an insulation sleeve is provided at the bottom of the raw water storage tank, and the insulation sleeve is connected to a temperature controller.

[0007] As a further improvement of the present invention, the raw water storage tank stores real mine water, or simulated mine water with different suspended solids and water chemical characteristic components is artificially prepared according to experimental needs.

[0008] As a further improvement of the present invention, sampling ports are respectively provided in the first medium zone, the second medium zone and the third medium zone, and back pressure valves are provided on the sampling ports.

[0009] Secondly, this invention also proposes a simulation experiment method for the multi-field coupling effect of mine water reinjection. Based on the aforementioned simulation experiment system for the multi-field coupling effect of mine water reinjection, the method includes the following steps:

[0010] Step S1: Based on the hydrogeological structure characteristics of the reservoir, representative rock cores or artificially prepared reservoir media from the target reservoir are placed into the first media zone, the second media zone, and the third media zone according to the same or different media pore sizes.

[0011] Step S2: Use an insulation jacket to heat the mine water in the raw water storage tank, and use a thermostat to adjust the temperature of the mine water to the set temperature.

[0012] Step S3: The mine water in the raw water storage tank is sent into the reservoir medium filling area through the graded filtration unit. The mine water first passes through the first filter and then enters the first medium area. At the same time, the unfiltered mine water enters the second filter through the first filter and then enters the second medium area. At the same time, the unfiltered mine water enters the third filter through the second filter and then enters the third medium area.

[0013] Step S4: Turn on the pressure pump and apply vertical pressure to the reservoir medium through the pressure piston. Open the temperature control jacket to heat the reservoir medium so that the pressure and temperature of the reservoir medium are the same as those of the in-situ reinjection formation. The real-time temperature is fed back to the temperature controller through the temperature sensor.

[0014] Step S5: Turn on the microbial injection pump and pass the microbial liquid in the microbial storage tank into the pipelines leading to the reservoir medium filling area through the first filter, the second filter and the third filter respectively.

[0015] Step S6: Obtain water samples, flow rate and pressure changes during the reinjection process through three sampling ports.

[0016] Step S7: Use a water quality analyzer to monitor the water samples output from the first medium zone, the second medium zone, and the third medium zone, and obtain the water temperature, pH, conductivity, redox potential, dissolved oxygen, and turbidity, and perform routine water chemical component analysis.

[0017] Step S8: Conduct microbial testing and analysis on the water sample, including 16S rDNA sequencing, diversity analysis and species composition analysis, to obtain the characteristics of microbial changes in the reservoir medium under the reinjection drive.

[0018] Step S9: Simplify the flow process of mine water within a medium zone into a one-dimensional horizontal movement process of mine water in the reservoir medium and a blockage process in the reservoir medium, and establish a mathematical model of the composite blockage process driven by reinjection, specifically including the following steps:

[0019] Step S911: Under the drive of mine water reinjection, the Reynolds number is used to determine the flow state of mine water in the reservoir medium. The formula is as follows: Equation (1), In the formula: Re is the Reynolds number when water flows through the pores of the reservoir medium; ρ is the fluid density, kg / m³. 3 u is the pore velocity of the fluid in the reservoir medium, m / s; μ is the dynamic viscosity coefficient of the fluid, Pa·s; R is the hydraulic radius, m.

[0020] Step S912: Under laminar flow conditions, the equation for water flow in the reservoir medium is expressed using Darcy's law, and the equation characterizing the relationship between groundwater flow and permeability coefficient is as follows:

[0021] Equation (2), In the formula: Kx is the horizontal permeability coefficient, MT -1 μ s For water release rate, L -1 ; ∂H / ∂x represents the rate of change of water head per unit distance moved in the horizontal direction; ∂H / ∂t represents the rate of change of water head over time.

[0022] As a further improvement of the present invention, when microorganisms are present in the reservoir medium, the determination of the blockage of the reservoir medium by microorganisms specifically includes the following steps: Step S913, firstly, construct mathematical equations for the transport of microorganisms and nutrients, and clarify the transport range of microorganisms and nutrients, wherein equation (3) is the microbial transport equation and equation (4) is the nutrient transport equation:

[0023] Equation (3)

[0024] Equation (4), In the formula: D is the dispersion coefficient, L 2 / T; v is the pore water flow velocity, L / T; n is the porosity; F B and F S These are the source and sink terms for changes in suspended microbial biomass and substrate concentration, respectively, MV -1 T -1 B represents the concentration of suspended microorganisms, M / V; S represents the concentration of nutrients, M / V.

[0025] Step S914: Construct a microbial growth and death model to calculate changes in microbial population. The specific formula is as follows: Equation (5), The Monod equation is used to calculate microbial growth. The specific formula is as follows: Equation (6), Microbial death is calculated using the first-order kinetic equation (7), and the specific formula is as follows: Equation (7); In equations (5), (6), and (7): r G MV represents the growth rate of microorganisms. -1 T -1 , which is the ratio of microbial growth rate to microbial concentration; μ g The specific growth rate of microorganisms; μ g max For the maximum specific growth rate, T -1 ;X c For microbial concentration, MV -1 ;K S MV is the half-saturation constant. -1 r1 represents the microbial death rate, MV -1 T -1 k1 is the microbial death rate coefficient, T -1 .

[0026] Step S915: Microorganisms grow by consuming nutrients. The relationship between their growth and nutrient consumption is as follows: Equation (8), In the formula: r s It is the matrix degradation rate, MV -1 T -1 Y is the yield coefficient, MM -1 This refers to the amount of microorganisms produced by the degradation of a unit mass of organic matter.

[0027] Step S916: According to the law of conservation of mass, the amount of suspended matter flowing in and out horizontally is equal to the cumulative change in suspended matter per unit time. Therefore, the suspended matter transport process under one-dimensional conditions is as follows: Equation (9), In the formula: n is the porosity of the reservoir medium; C is the concentration of suspended solids in the solution, MV -1 Cs represents the mass of suspended matter deposited per unit pore space, and MV represents the mass of suspended matter deposited per unit pore space. -1 ;v x For Darcy speed, LT -1 The amount of suspended matter deposited in the medium can be described as: Equation (10), In the formula: δ is the adsorption coefficient of suspended matter in the medium, T -1 ε is the desorption coefficient of suspended solids, T -1 Step S917: Establish a mineral dissolution and precipitation model in the aqueous chemical components: Use the dissolution and precipitation equilibrium theory of minerals in the reaction phase combined with a one-dimensional convection-diffusion equation to simulate the migration of minerals in the reservoir medium.

[0028] Equation (11), In the formula: C che MV represents the cation concentration of mineral dissolved components in the solution after reinjection. -1 ;F d MV is the amount of mineral deposits per unit reservoir medium space. -1 .

[0029] Step S918: Construct the relationship between changes in media porosity caused by microbial accumulation, suspended solids deposition, and mineral dissolution and precipitation. The specific formulas are as follows: Equation (12), Equation (13), Equation (14), where: n0 is the initial porosity; M is the mass of microorganisms per unit volume of medium, MV -1 ρ represents microbial density, MV -1 b ss The packing factor of suspended particles reflects the influence of particle deposition morphology on porosity in the reservoir medium and is related to particle deposition morphology; σ ss VM is the volume occupied by a unit mass of suspended particles. -1 b Ca σ is the precipitate accumulation factor for calcite. Ca VM represents the volume occupied by a unit mass of calcite precipitate. -1 ;F d MV represents the amount of calcite precipitated per unit volume of medium. -1 .

[0030] Step S919: The relationship between medium porosity and permeability is expressed by the Kozeny-Carmen formula:

[0031] Equation (15), In the formula: K is the permeability coefficient, m / d; K0 is the initial permeability coefficient, m / d; n is the porosity, dimensionless; n0 is the initial porosity, dimensionless.

[0032] As a further improvement to the present invention, a partial differential equation of the form of multi-field coupling interaction coefficient is constructed as follows:

[0033] Equation (16), In the formula: w is the dependent variable; c is the diffusion coefficient; α is the absorption coefficient; f is the source term; e a y is the mass coefficient; da is the attenuation coefficient; a is the conserved flux convection coefficient; β is the convection coefficient; γ is the conserved flux source.

[0034] Compared with the prior art, the present invention has the following technical effects: Based on the water pressure, water quality test and analysis data and microbial community characteristics obtained during the test, the present invention can further analyze the physical, chemical and biological processes in the process of deep mine water reinjection reservoir media, thereby revealing the multi-field coupling effect, specifically reflected in the following aspects: (1) Physical process level: It can simulate the injection process of mine water under specific reservoir pressure and temperature conditions, monitor the dynamic changes of pressure gradient during the injection process, control and monitor the interaction between the reservoir temperature field and the injected water temperature field, and simulate the groundwater dynamic field (including changes in flow velocity, flow direction and permeability).

[0035] (2) Chemical process level: By simulating different types of mine water for reinjection, the changes of water chemical components (such as K⁺, Na⁺, Ca²⁺, Mg²⁺, SO₄²⁻, HCO₃⁻, Cl⁻) and mineral components during the migration process can be tracked, as well as the reactions and mutual influences of precipitation, dissolution, adsorption, ion exchange and other reactions that occur between them.

[0036] (3) Biological process level: It can study the activities of microbial communities (including native and exogenously injected microorganisms) under specific pressure, temperature and hydrochemical environment (such as metabolism, growth, death and biofilm formation), and their reaction to the above fields (especially hydrochemical field and hydrodynamic field) (such as bioblocking and biodegradation).

[0037] (4) This invention combines reservoir medium channels, uses Reynolds number to determine mine water flow state, and uses Darcy's law to determine laminar flow equations to build a physical flow modeling framework; for scenarios where there are microorganisms in the reservoir, it supplements models such as microbial migration and growth and death, suspended matter deposition, and mineral dissolution and precipitation, and associates porosity and permeability to improve the modeling of composite blockage; it abstracts multi-field coupling general coefficient partial differential equations from the specific process of composite blockage, providing scientific support for multi-field coupling research on mine water reinjection. Attached Figure Description

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a schematic diagram of the structural principle of the mine water reinjection multi-field coupling simulation experimental system of the present invention.

[0040] Figure 2This is a diagram of the internal structure of the reservoir simulation chamber.

[0041] Explanation of reference numerals in the attached drawings: 1-Reservoir simulation chamber, 11-Chamber body, 12-Reservoir medium filling zone, 121-First medium zone, 122-Second medium zone, 123-Third medium zone, 13-Imperile layer, 14-Rubber sleeve, 15-Pressure piston, 16-Temperature control jacket, 17-Temperature controller, 18-Pressure pump, 19-Sampling port, 2-Mine water supply system, 21-Water inlet. 22-Raw water storage tank, 23-Insulation jacket, 24-First filter, 25-Second filter, 26-Third filter, 27-First flow pump, 28-Second flow pump, 29-Third flow pump, 3-Output water collection and testing system, 31-First water sample collection tank, 32-Second water sample collection tank, 33-Third water sample collection tank, 34-Water quality analyzer, 4-Microbial culture and injection system, 41-Microbial storage tank, 42-Microbial injection pump, DV-Check valve, BV-Back pressure valve, PG-Pressure gauge, TS-Temperature sensor. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0043] like Figure 1 and Figure 2As shown, a multi-field coupling simulation experimental system for mine water reinjection includes a reservoir simulation box 1, a mine water supply system 2, a produced water collection and detection system 3, and a microbial culture and injection system 4. Specifically, the reservoir simulation box 1 includes a box body 11 made of stainless steel, with an open top and a lid. A reservoir medium filling area 12 is provided in the middle of the box body 11 for placing the reservoir medium. Water-proof layers 13 are provided above and below the reservoir medium filling area 12 to simulate the water-proof layers above and below the real target reservoir. Rubber sleeves 14 are provided above the upper water-proof layer 13 and below the lower water-proof layer 13 to prevent mine water from leaking between the water-proof layer 13 and the inner wall of the box body 11. Temperature control jackets 16 are provided above the upper rubber sleeve 14 and below the lower rubber sleeve 14. The temperature control jackets 16 are connected to a temperature controller 17. The temperature control jackets 16 are waterproof jackets with internal resistance wires. Controlled by the temperature controller 17, the temperature of the reservoir medium filling area can be regulated to simulate the actual temperature changes of the target reservoir, providing a temperature field for the reservoir medium filling area 12. A pressure piston 15 is provided between the upper temperature control jacket 16 and the upper rubber sleeve 14. The pressure piston 15 is connected to a pressure pump 18 to apply vertical pressure to the reservoir medium, providing the original formation stress state of the reservoir medium. The mine water supply system 2 includes a raw water storage tank 22 and a flow pump. The raw water storage tank 22 has an inlet 21 on one side and is connected to the flow pump via a pipeline on the other side. The flow pump is connected to the pipeline of the reservoir medium filling area 12. The produced water collection and testing system 3 includes a produced water collection tank and a water quality analyzer 34. The produced water collection tank is connected to the pipeline of the reservoir medium filling area 12, and the water quality analyzer 34 is connected to the pipeline of the produced water collection tank.

[0044] Specifically, the reservoir medium filling zone 12 is divided into three medium zones: the first medium zone 121, the second medium zone 122, and the third medium zone 123. A water-resistant layer 13 is provided between each medium zone. The pore size of the reservoir medium in each medium zone may be the same or different. The mine water supply system 2 also includes a graded filtration unit, comprising a first filter 24, a second filter 25, and a third filter 26 connected sequentially from bottom to top via pipelines. Each of the three filters contains a filter membrane with progressively smaller pore sizes, forming a three-stage filtration system. One end of the first filter 24 is connected to the raw water storage tank 22 via a pipeline, and the other end is connected to the first medium zone 121 via a pipeline through a first flow pump 27. The second filter 25 is connected to the second medium zone 122 via a pipeline through a second flow pump 28, and the third filter 26 is connected to the third medium zone 123 via a pipeline through a third flow pump 29. The produced water collection and testing system 3 includes three outlet pipes, one end of which is connected to the first medium zone 121, the second medium zone 122, and the third medium zone 123 respectively, and the other end is connected to the first water sample collection tank 31, the second water sample collection tank 32, and the third water sample collection tank 33 respectively. The first water sample collection tank 31, the second water sample collection tank 32, and the third water sample collection tank 33 are connected to the water quality analyzer 34 via pipelines. Each medium zone is equipped with a temperature sensor TS, which is connected to a temperature controller 17. This system, through a combination of graded filtration and zoned injection, can simulate the infiltration process of mine water at different depths and filtration levels in real reservoirs, more closely resembling the contact state between mine water and reservoir media during actual reinjection, avoiding the problem that a single filtration or single medium cannot reproduce complex reservoir conditions.

[0045] Sampling ports 19 are respectively set in the first medium zone 121, the second medium zone 122 and the third medium zone 123, and connected to back pressure valves. By connecting to measuring instruments such as flow meters, pressure gauges and temperature sensors, the changes in water quality, temperature and pressure of mine water during the flow of water samples from the reservoir medium filling zone can be obtained in real time. The reservoir medium can also be sampled during the process for subsequent research.

[0046] The microbial culture and injection system 4 includes a microbial storage tank 41 and a microbial injection pump 42. Nutrient solution and microbial culture solution can be injected into the microbial storage tank 41 at regular intervals and then introduced into the first medium zone 121, the second medium zone 122 and the third medium zone 123 respectively via the microbial injection pump 42.

[0047] Specifically, an insulation sleeve 23 is installed outside the raw water storage tank 22 to heat the mine water in the raw water storage tank 22. The heating temperature is adjusted by the temperature controller 17 so that the mine water meets the set temperature.

[0048] Specifically, the raw water storage tank 22 stores real mine water or simulated mine water artificially prepared according to the chemical characteristics of the target mine water. The reservoir medium filling zone 12 contains representative rock cores of the target reservoir or artificially prepared reservoir medium.

[0049] Specifically, a one-way valve DV is installed on the output pipeline of the microbial injection pump 42, which can determine whether microorganisms need to be injected into the reservoir medium filling zone 12 according to experimental needs. A one-way valve DV, a back pressure valve BV, and a pressure gauge PG are installed on the pipeline from the staged filtration unit to the reservoir medium filling zone 12, and the same measuring components are also installed on the three outlet pipes.

[0050] The experimental system of this invention systematically integrates the interaction of stress field, groundwater dynamic field, hydrochemical field, temperature field, and microbial field, breaking through the limitations of traditional devices that simulate only one field. It visualizes and simulates the synergistic effects of multiple fields under complex geological conditions. For example, it can simulate the injection process of mine water under specific reservoir pressure and temperature conditions, monitor the dynamic changes of the pressure gradient during injection, control and monitor the reservoir temperature field and its interaction with the injected water temperature field; and track the hydrochemical composition (K... + Na + Ca 2+ Mg 2+ SO4 2- HCO3 - Cl - It can simulate the changes, reactions (precipitation, dissolution, adsorption, ion exchange) and interactions of mineral components during migration; it can simulate groundwater dynamic fields (flow velocity, flow direction, permeability changes); it can study the activities (metabolism, growth, death, biofilm formation) of microbial communities under specific pressure, temperature, and hydrochemical environments and their reactions to the above fields (especially hydrochemistry and hydrodynamics) (such as bioblocking and biodegradation).

[0051] This invention also proposes a simulation experiment method for the multi-field coupling effect of mine water reinjection, comprising the following steps:

[0052] Step S1: Based on the hydrogeological structure characteristics of the reservoir, representative rock cores or artificially prepared reservoir media from the target reservoir are placed into the first media zone 121, the second media zone 122, and the third media zone 123 according to the same or different pore sizes. Step S2: The mine water in the raw water storage tank 22 is heated using the insulation jacket 23, and the temperature is adjusted to the set temperature using the temperature controller 17. Step S3: The mine water in the raw water storage tank 22 is sent into the reservoir media filling zone 12 through a graded filtration unit. The mine water first passes through the first filter 24 and then enters the first media zone 121. Simultaneously, unfiltered mine water enters the second filter 25 through the first filter 24 and is then filtered... After filtration, the water is introduced into the second medium zone 122; simultaneously, unfiltered mine water enters the third filter 26 through the second filter 25, and after filtration, it is introduced into the third medium zone 123; in step S4, the pressure pump 18 is turned on, and the pressure piston 15 applies vertical pressure to the reservoir medium, and the temperature control jacket 16 is turned on to heat the reservoir medium, so that the pressure and temperature of the reservoir medium are consistent with those of the in-situ reinjection formation, and the real-time temperature is fed back to the temperature controller 17 through the temperature sensor TS; in step S5, the microbial injection pump 42 is turned on, and the microbial liquid in the microbial storage tank 41 is introduced into the pipelines leading to the reservoir medium filling zone 12 through the first filter 24, the second filter 25 and the third filter 26 respectively; Step S6: Obtain water samples, flow rate, and pressure changes during the reinjection process through three sampling ports 19; Step S7: Monitor water samples output from the first medium zone 121, the second medium zone 122, and the third medium zone 123 using a water quality analyzer 34, obtain water temperature, pH, conductivity, redox potential, dissolved oxygen, and turbidity, and perform routine water chemical component analysis; Step S8: Conduct microbial testing and analysis on the water samples, including 16S rDNA sequencing, diversity analysis, and species composition analysis, to obtain the microbial change characteristics in the reservoir medium under reinjection drive; Step S9: Simplify the flow process of mine water in one medium zone into a one-dimensional movement process of mine water in the reservoir medium and a blockage process of the reservoir medium, and establish a mathematical model of the composite blockage process under reinjection drive, specifically including the following steps:

[0053] Step S911: Under the drive of mine water reinjection, the Reynolds number is used to determine the flow state of mine water in the reservoir medium. The formula is as follows: Equation (1), In the formula: Re is the Reynolds number when water flows through the pores of the reservoir medium; ρ is the fluid density, kg / m³. 3 u is the pore velocity of the fluid in the reservoir medium, m / s; μ is the dynamic viscosity coefficient of the fluid, Pa·s; R is the hydraulic radius, m.

[0054] Step S912: Under laminar flow conditions, the equation for water flow in the reservoir medium is expressed using Darcy's law, and the equation characterizing the relationship between groundwater flow and permeability coefficient is as follows:

[0055] Equation (2), In the formula: Kx is the horizontal permeability coefficient, MT -1 μ s For water release rate, L -1 ∂H / ∂x represents the rate of change of water head per unit distance moved in the horizontal direction, and ∂H / ∂t represents the rate of change of water head over time.

[0056] When microorganisms are present in the reservoir medium, the blockage of the reservoir medium by microorganisms is determined, which includes the following steps: Step S913: First, construct mathematical equations for the transport of microorganisms and nutrients to clarify the transport range of microorganisms and nutrients, where equation (3) is the microbial transport equation and equation (4) is the nutrient transport equation:

[0057] Equation (3)

[0058] Equation (4), In the formula: D is the dispersion coefficient, L 2 / T; v is the pore water flow velocity, L / T; n is the porosity; F B and F S These are the source and sink terms for changes in suspended microbial biomass and substrate concentration, respectively, MV -1 T -1 B represents the concentration of suspended microorganisms, M / V; S represents the concentration of nutrients, M / V.

[0059] Step S914: Construct a microbial growth and death model to calculate changes in microbial population. The specific formula is as follows:

[0060] Equation (5), The Monod equation is used to calculate microbial growth. The specific formula is as follows: Equation (6), Microbial death is calculated using the first-order kinetic equation (7), and the specific formula is as follows: Equation (7); In formulas (5), (6), and (7): r G MV represents the growth rate of microorganisms. -1 T -1 , which is the ratio of microbial growth rate to microbial concentration; μ g The specific growth rate of microorganisms; μ g maxFor the maximum specific growth rate, T -1 ;X c For microbial concentration, MV -1 ;K S MV is the half-saturation constant. -1 r1 represents the microbial death rate, MV -1 T -1 k1 is the microbial death rate coefficient, T -1 .

[0061] Step S915: Microorganisms grow by consuming nutrients. The relationship between their growth and nutrient consumption is as follows: Equation (8), In the formula: r s It is the matrix degradation rate, MV -1 T -1 Y is the yield coefficient, MM -1 This refers to the amount of microorganisms produced by the degradation of a unit mass of organic matter.

[0062] Step S916: According to the law of conservation of mass, the amount of suspended matter flowing in and out horizontally is equal to the cumulative change in suspended matter per unit time. Therefore, the suspended matter transport process under one-dimensional conditions is as follows:

[0063] Equation (9), where: n is the porosity of the reservoir medium, C is the concentration of suspended solids in the solution, and MV -1 Cs represents the mass of suspended matter deposited per unit pore space, and MV represents the mass of suspended matter deposited per unit pore space. -1 v x For Darcy speed, LT -1 The amount of suspended matter deposited in the medium can be described as:

[0064] Equation (10), In the formula: δ is the adsorption coefficient of suspended matter in the medium, T -1 ε is the desorption coefficient of suspended solids, T -1 .

[0065] Step S917: Establish a mineral dissolution and precipitation model in the aqueous chemical components: Use the dissolution and precipitation equilibrium theory of minerals in the reaction phase combined with a one-dimensional convection-diffusion equation to simulate the migration of minerals in the reservoir medium.

[0066] Equation (11), In the formula: C che MV represents the cation concentration of mineral dissolved components in the solution after reinjection. -1 ;F d MV is the amount of mineral deposits per unit reservoir medium space.-1 .

[0067] Step S918: Construct the relationship between changes in media porosity caused by microbial accumulation, suspended solids deposition, and mineral dissolution and precipitation. The specific formulas are as follows:

[0068] Equation (12), Equation (13), Equation (14), where: n0 is the initial porosity; M is the mass of microorganisms per unit volume of medium, MV -1 ρ represents microbial density, MV -1 b ss The packing factor of suspended particles reflects the influence of particle deposition morphology on porosity in the reservoir medium and is related to particle deposition morphology; σ ss VM is the volume occupied by a unit mass of suspended particles. -1 b Ca Calcite sedimentation factor; σ Ca VM represents the volume occupied by a unit mass of calcite precipitate. -1 ;F d MV represents the amount of calcite precipitated per unit volume of medium. -1 .

[0069] Step S919: The relationship between medium porosity and permeability is expressed by the Kozeny-Carmen formula:

[0070] Equation (15), In the formula: K is the permeability coefficient, m / d; K0 is the initial permeability coefficient, m / d; n is the porosity, dimensionless; n0 is the initial porosity, dimensionless.

[0071] Construct a partial differential equation of the form of multi-field coupling interaction coefficients, as follows:

[0072] Equation (16), Where: w—dependent variable; c—diffusion coefficient; α—absorption coefficient; f—source term; e a y is the mass coefficient; da is the attenuation coefficient; a is the conserved flux convection coefficient; β is the convection coefficient; γ is the conserved flux source.

[0073] The experimental method of this invention provides a favorable technical means for further in-depth research on the permeability variation law of deep mine water recharge reservoirs and the groundwater environment evolution mechanism under the five-field coupling effect. It can assess the long-term impact of different recharge schemes (water quality, temperature, rate) on reservoir properties (permeability) and water quality (potential pollution), providing a guarantee for the long-term safe recharge of deep mine water. In summary, this invention reveals the evolution law of groundwater environment and permeability evolution mechanism driven by deep mine water recharge. This invention uses Reynolds number to determine the flow regime and Darcy's law to determine the laminar flow equation, providing a physical flow basis for modeling the flow of mine water in the reservoir medium, supporting subsequent plugging and multi-field coupling analysis. It supplements the models related to microorganisms, suspended solids, and minerals and correlates porosity with permeability, improving the modeling of composite plugging and accurately revealing the physical-biological-chemical coupling plugging mechanism and its impact on permeability when microorganisms are present in the reservoir. This paper abstracts a general equation for multi-field coupling, elevates the specific blockage process to a macroscopic multi-field interaction framework, provides a general mathematical tool for the analysis of multi-field coupling effects, and helps to comprehensively explore the multi-field evolution law of reservoirs under reinjection.

[0074] 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. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes are within the protection scope of the claims of the present invention.

Claims

1. A simulation experimental system for multi-field coupling effects of mine water reinjection, characterized in that, include The reservoir simulation box (1) includes a box body (11), and a reservoir medium filling area (12) is provided in the middle of the box body (11) for placing the reservoir medium; a water-proof layer (13) is provided above and below the reservoir medium filling area (12), and a rubber sleeve (14) is provided above the upper water-proof layer (13) and below the lower water-proof layer (13); a temperature control jacket (16) is provided above the upper rubber sleeve (14) and below the lower rubber sleeve (14), wherein a pressure piston (15) is provided between the upper temperature control jacket (16) and the upper rubber sleeve (14), and the pressure piston (15) is connected to a pressure pump (18) pipeline for applying pressure to the reservoir medium; The mine water supply system (2) includes a raw water storage tank (22) and a flow pump. The raw water storage tank (22) is connected to the flow pump pipeline, and the flow pump is connected to the reservoir medium filling area (12) pipeline. The produced water collection and testing system (3) includes a produced water collection tank and a water quality analyzer (34). The produced water collection tank is connected to the pipeline of the reservoir medium filling area (12), and the water quality analyzer (34) is connected to the pipeline of the produced water collection tank. The microbial culture and injection system (4) includes a microbial storage tank (41) and a microbial injection pump (42). The microbial storage tank (41) is connected to the microbial injection pump (42) by pipeline, and the microbial injection pump (42) is connected to the reservoir medium filling area (12) by pipeline. The reservoir medium filling area (12) is divided into a first medium area (121), a second medium area (122) and a third medium area (123). A water-proof layer (13) is provided between each medium area. The same or different lithological reservoir medium is placed in each medium area. The mine water supply system (2) also includes a graded filtration unit. The graded filtration unit includes a first filter (24), a second filter (25) and a third filter (26) connected by pipelines from bottom to top. The first filter (24), the second filter (25) and the third filter (26) are all equipped with filter membranes. The pore size of the three filter membranes decreases in sequence to form a three-stage filtration. One end of the first filter (24) is connected to the raw water storage tank (22) by pipeline, and the other end is connected to the first medium area (121) through pipeline via the first flow pump (27). The second filter (25) is connected to the second medium zone (122) via the second flow pump (28), and the third filter (26) is connected to the third medium zone (123) via the third flow pump (29). The effluent collection and detection system (3) includes three outlet pipes. One end of each outlet pipe is connected to the first medium zone (121), the second medium zone (122), and the third medium zone (123), respectively, and the other end is connected to the first water sample collection tank (31), the second water sample collection tank (32), and the third water sample collection tank (33), respectively. The first water sample collection tank (31), the second water sample collection tank (32), and the third water sample collection tank (33) are connected to the water quality analyzer (34) via pipeline. Each medium zone is equipped with a temperature sensor (TS), which is connected to a temperature controller (17). Sampling ports (19) are provided in the first medium zone (121), the second medium zone (122) and the third medium zone (123), and a back pressure valve is provided on the sampling port (19); An insulation sleeve (23) is provided at the bottom of the outside of the raw water storage tank (22), and the insulation sleeve (23) is connected to the temperature controller (17).

2. The mine water reinjection multi-field coupling simulation experimental system according to claim 1, characterized in that, The raw water storage tank (22) stores real mine water, or simulated mine water with different suspended solids and water chemical characteristics is artificially prepared according to experimental needs.

3. A simulation experimental method for multi-field coupling effects of mine water reinjection. The mine water reinjection multi-field coupling simulation experimental system according to claim 1 or 2 is characterized by comprising the following steps: Step S1: Based on the hydrogeological structure characteristics of the reservoir, representative rock cores or artificially prepared reservoir media of the target reservoir are placed into the first media zone (121), the second media zone (122), and the third media zone (123) according to the same or different media pore sizes. Step S2: Heat the mine water in the raw water storage tank (22) using the insulation jacket (23), and adjust the mine water temperature to the set temperature using the temperature controller (17); Step S3: The mine water in the raw water storage tank (22) is sent into the reservoir medium filling area (12) through the graded filtration unit. The mine water first passes through the first filter (24) and then enters the first medium area (121). At the same time, the unfiltered mine water enters the second filter (25) through the first filter (24) and then enters the second medium area (122). At the same time, the unfiltered mine water enters the third filter (26) through the second filter (25) and then enters the third medium area (123). Step S4: Turn on the pressure pump (18), apply vertical pressure to the reservoir medium through the pressure piston (15), open the temperature control jacket (16) to heat the reservoir medium, so that the pressure and temperature of the reservoir medium are consistent with those of the in-situ reinjection formation, and feed back the real-time temperature to the temperature controller (17) through the temperature sensor (TS). Step S5: Turn on the microbial injection pump (42) and pass the microbial liquid in the microbial storage tank (41) into the pipelines leading to the reservoir medium filling area (12) through the first filter (24), the second filter (25) and the third filter (26); Step S6: Obtain water samples, flow rate and pressure changes during the reinjection process through three sampling ports (19); Step S7: Use a water quality analyzer (34) to monitor the water samples output from the first medium zone (121), the second medium zone (122) and the third medium zone (123), obtain water temperature, pH, conductivity, redox potential, dissolved oxygen and turbidity, and perform routine water chemical component analysis. Step S8: Conduct microbial testing and analysis on the water sample, including 16S rDNA sequencing, diversity analysis and species composition analysis, to obtain the characteristics of microbial changes in the reservoir medium under the reinjection drive. Step S9: Simplify the flow process of mine water within a medium zone into a one-dimensional horizontal movement process of mine water in the reservoir medium and a blockage process in the reservoir medium, and establish a mathematical model of the composite blockage process driven by reinjection, specifically including the following steps: Step S911: Under the drive of mine water reinjection, the Reynolds number is used to determine the flow state of mine water in the reservoir medium. The formula is as follows: Equation (1), In the formula: Re is the Reynolds number when water flows through the pores of the reservoir medium; ρ is the fluid density, kg / m³. 3 u is the pore velocity of the fluid in the reservoir medium, m / s; μ is the dynamic viscosity coefficient of the fluid, Pa·s; R is the hydraulic radius, m; Step S912: Under laminar flow conditions, the equation for water flow in the reservoir medium is expressed using Darcy's law, and the equation characterizing the relationship between groundwater flow and permeability coefficient is as follows: Equation (2), Where: Kx is the horizontal permeability coefficient, L / T; μ s For water release rate, L -1 ; ∂H / ∂x represents the rate of change of water head per unit distance moved in the horizontal direction; ∂H / ∂t represents the rate of change of water head over time; When microorganisms are present in the reservoir medium, determining the extent of microbial blockage includes the following steps: Step S913: First, construct mathematical equations for the transport of microorganisms and nutrients to clarify the transport range of microorganisms and nutrients. Equation (3) is the microbial transport equation, and equation (4) is the nutrient transport equation. Equation (3), Equation (4), In the formula: D is the dispersion coefficient, L 2 / T; v is the pore water flow velocity, L / T; n is the porosity; F B and F S These are the source and sink terms for changes in suspended microbial biomass and substrate concentration, respectively, MV -1 T -1 B represents the concentration of suspended microorganisms (M / V); S represents the concentration of nutrients (M / V). Step S914: Construct a microbial growth and death model to calculate changes in microbial population. The specific formula is as follows: Equation (5), The Monod equation is used to calculate microbial growth. The specific formula is as follows: Equation (6), Microbial death is calculated using the first-order kinetic equation (7), and the specific formula is as follows: Equation (7), In equations (5), (6), and (7): r G MV represents the growth rate of microorganisms. -1 T -1 , which is the ratio of microbial growth rate to microbial concentration; μ g The specific growth rate of microorganisms; μ g max For the maximum specific growth rate, T -1 ;X c For microbial concentration, MV -1 ;K S MV is the half-saturation constant. -1 r1 represents the microbial death rate, MV -1 T -1 k1 is the microbial death rate coefficient, T -1 ; Step S915: Microorganisms grow by consuming nutrients. The relationship between their growth and nutrient consumption is as follows: Equation (8), In the formula: r s It is the matrix degradation rate, MV -1 T -1 Y is the yield coefficient, MM -1 This refers to the amount of microorganisms produced by the degradation of a unit mass of organic matter. Step S916: According to the law of conservation of mass, the amount of suspended matter flowing in and out horizontally is equal to the cumulative change in suspended matter per unit time. Therefore, the suspended matter transport process under one-dimensional conditions is as follows: Equation (9), In the formula: n is the porosity of the reservoir medium; C is the concentration of suspended solids in the solution, MV -1 Cs represents the mass of suspended matter deposited per unit pore space, and MV represents the mass of suspended matter deposited per unit pore space. -1 ;v x For Darcy speed, LT -1 ; The amount of suspended matter deposited in the medium can be described as: Equation (10), In the formula: δ is the adsorption coefficient of suspended matter in the medium, T -1 ε is the desorption coefficient of suspended solids, T -1 ; Step S917: Establish a mineral dissolution and precipitation model in the aqueous chemical components: Use the dissolution and precipitation equilibrium theory of minerals in the reaction phase combined with a one-dimensional convection-diffusion equation to simulate the migration of minerals in the reservoir medium. Equation (11), In the formula: C che MV represents the cation concentration of mineral dissolved components in the solution after reinjection. -1 ;F d MV is the amount of mineral deposits per unit reservoir medium space. -1 ; Step S918: Construct the relationship between changes in media porosity caused by microbial accumulation, suspended solids deposition, and mineral dissolution and precipitation. The specific formulas are as follows: Equation (12), Equation (13), Equation (14), In the formula: n0 is the initial porosity; M is the mass of microorganisms per unit volume of medium, MV -1 ρ represents microbial density, MV -1 b ss The packing factor of suspended particles reflects the influence of particle deposition morphology on porosity in the reservoir medium and is related to particle deposition morphology; σ ss VM is the volume occupied by a unit mass of suspended particles. -1 b Ca σ is the precipitate accumulation factor for calcite. Ca VM represents the volume occupied by a unit mass of calcite precipitate. -1 ;F d MV represents the amount of calcite precipitated per unit volume of medium. -1 ; Step S919: The relationship between medium porosity and permeability is expressed by the Kozeny-Carmen formula: Equation (15), In the formula: K is the permeability coefficient, m / d; K0 is the initial permeability coefficient, m / d; n is the porosity, dimensionless; n0 is the initial porosity, dimensionless.

4. The experimental method for simulating the multi-field coupling effect of mine water reinjection according to claim 3, characterized in that, Construct a partial differential equation of the form of multi-field coupling interaction coefficients, as follows: Equation (16), In the formula: w is the dependent variable; c is the diffusion coefficient; α is the absorption coefficient; f is the source term; e a y is the mass coefficient; da is the attenuation coefficient; a is the conserved flux convection coefficient; β is the convection coefficient; γ is the conserved flux source.

Images