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

Abstract

The invention discloses a mine water recharge multi-field coupling effect simulation experiment system and method, and relates to the technical field of mine water utilization. The experimental system comprises a reservoir simulation box, a mine water supply system, a produced water collection and detection system and a microorganism culture and injection system, the reservoir simulation box is provided with a reservoir medium filling area and is matched with the pressure pump and the temperature control jacket to simulate the pressure and temperature of a deep stratum, the mine water supply system provides controllable mine water, the microorganism culture and injection system injects specific microorganisms, and the produced water collection and detection system detects the water quality and microorganism characteristics. The experimental method comprises the following steps: simulating reservoir conditions, injecting mine water and microorganisms, monitoring multi-parameter changes, and establishing a composite blockage mathematical model and a multi-field coupling partial differential equation. According to the invention, five-field coupling simulation of a stress field, a hydrodynamic field and the like can be realized, and a technical means is provided for underground water environment evolution and permeability mechanism research.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine water utilization, and particularly relates to a mine water recharge multi-field coupling simulation experiment system and method. BACKGROUND

[0002] In the process of coal mine safety production, if mine water is directly discharged without treatment, it is easy to cause harm to the ecological environment. Deep mine water recharge has become a new treatment method due to its high cost performance, low cost and strong operability, and more coal mines will implement this project in the future. With the promotion of deep mine water recharge project, the hydrogeological effect driven by it has become a research focus and difficulty, and multi-field coupling is the core of analysis. The high temperature and high pressure of deep geological environment, complex fluid activity, hydrogeochemical behavior and microbial activity are the key factors restricting the reservoir system. However, due to the complexity of deep geological conditions, the difficulty of investigation and the high cost of drilling monitoring, it is difficult to obtain field data, and multi-field coupling simulation test has become an important way to solve related problems. The existing indoor simulation device has obvious shortcomings: it mainly depends on water-water mixing, water-rock interaction and other reaction containers, isolates the field effect of in-situ geological body, and only considers single factor or part of index change; the groundwater recharge leaching column test focuses on the problem of shallow recharge, and does not involve long-term deep recharge multi-field effect; although the water-rock reaction kettle considers the temperature and pressure factors, it ignores the overall characteristics of the reservoir and the influence of microorganisms. Therefore, it is urgent to develop an actual indoor simulation system to provide technical means for multi-field coupling evaluation and related mechanism research. SUMMARY

[0003] The present application aims to provide a mine water recharge multi-field coupling simulation experiment system and method, which can overcome the defects of the prior art such as being unable to simulate multi-field coupling, ignoring microbial influence and being detached from deep scene, and can develop an actual indoor simulation system through pressure and temperature control of the reservoir simulation box, microbial injection system and multi-parameter monitoring, so as to evaluate multi-field coupling and provide technical means for groundwater environment evolution and permeability mechanism research.

[0004] The technical scheme adopted by the present application is: in a first aspect, the present application provides a mine water recharge multi-field coupling simulation experiment system, which comprises a reservoir simulation box, a box body, a reservoir medium filling area arranged in the middle of the box body for placing the reservoir medium, a water-resisting layer arranged above and below the reservoir medium filling area, a rubber sleeve arranged above the upper water-resisting layer and below the lower water-resisting layer, a temperature control jacket arranged above the upper rubber sleeve and below the lower rubber sleeve, wherein a pressure piston is arranged between the upper temperature control jacket and the upper rubber sleeve, the pressure piston is connected with a pressure pump pipeline for applying pressure to the reservoir medium, a mine water supply system comprising a raw water storage tank and a flow pump, the raw water storage tank being connected with the flow pump pipeline, the flow pump being connected with the reservoir medium filling area pipeline, an output water collection and detection system comprising an output water collection box and a water quality analyzer, the output water collection box being connected with the reservoir medium filling area pipeline, and the water quality analyzer being connected with the output water collection box pipeline, and a microorganism culture and injection system comprising a microorganism storage tank and a microorganism injection pump, the microorganism storage tank being connected with the microorganism injection pump pipeline, and the microorganism injection pump being connected with the reservoir medium filling area pipeline.

[0005] As a further improvement of the present application, the reservoir medium filling area is divided into a first medium area, a second medium area and a third medium area, a water-resisting layer is arranged between each medium area, and the same or different lithology reservoir medium is placed in each medium area; the mine water supply system further comprises a graded filtration unit, the graded filtration unit comprises a first filter, a second filter and a third filter connected in sequence from bottom to top, a filter membrane is arranged in each of the first filter, the second filter and the third filter, the pore sizes of the three filter membranes decrease in sequence to form a three-stage filtration; one end of the first filter is connected with the raw water storage tank pipeline, and the other end is connected with the first medium area through the first flow pump via a pipeline; the second filter is connected with the second medium area pipeline through the second flow pump, and the third filter is connected with the third medium area pipeline through the third flow pump; the output water collection and detection system comprises three water outlet pipes, one end of each water outlet pipe is connected with the first medium area, the second medium area and the third medium area respectively, and the other end is connected with a first water sample collection box, a second water sample collection box and a third water sample collection box respectively, and the first water sample collection box, the second water sample collection box and the third water sample collection box are connected with the water quality analyzer pipeline; a temperature sensor is arranged in each medium area, and the temperature sensor is connected with a temperature controller.

[0006] As a further improvement of the present application, a heat preservation sleeve is arranged at the bottom outside the raw water storage tank, and the heat preservation sleeve is connected with the temperature controller.

[0007] As a further improvement of the present application, the raw water storage tank stores real mine water, or artificial simulation mine water with different suspended matters and water chemical characteristic components according to experimental requirements.

[0008] As a further improvement of the present application, a back pressure valve is arranged on the sampling port in the first medium area, the second medium area and the third medium area.

[0009] In a second aspect, the present application further provides a simulation experiment method for mine water recharge multi-field coupling effect, which is based on the simulation experiment system for mine water recharge multi-field coupling effect.

[0010] In step S1, the representative cores or artificial reservoir media of the target reservoir are placed in the first medium area, the second medium area and the third medium area according to the same or different medium pore diameters in combination with the reservoir hydrogeological structure characteristics.

[0011] In step S2, the mine water in the raw water storage tank is heated by the heat preservation sleeve, and the temperature of the mine water is regulated to the set temperature by the temperature controller.

[0012] In step S3, the mine water in the raw water storage tank is sent into the reservoir medium filling area through the graded filtration unit, and the mine water first passes through the first filter, then is filtered and introduced into the first medium area; at the same time, the unfiltered mine water enters the second filter from the first filter, is filtered and introduced into the second medium area; at the same time, the unfiltered mine water enters the third filter from the second filter, is filtered and introduced into the third medium area.

[0013] In step S4, the pressure pump is opened, the vertical pressure is applied to the reservoir medium by the pressure piston, the reservoir medium is heated by the temperature control jacket, the pressure and temperature of the reservoir medium are consistent with those of the in-situ recharge formation, and the real-time temperature is fed back to the temperature controller by the temperature sensor.

[0014] In step S5, the microbial injection pump is opened, and the microorganisms in the microbial storage tank are introduced into the pipelines of the first filter, the second filter and the third filter which lead to the reservoir medium filling area.

[0015] In step S6, the water samples, flow rates and pressure changes during the recharge process are obtained through the three sampling ports.

[0016] In step S7, the water quality analyzer is used to monitor the water samples output from the first medium area, the second medium area and the third medium area, to obtain the water quality temperature, pH, conductivity, oxidation-reduction potential, dissolved oxygen and turbidity, and to perform the routine water chemical component analysis.

[0017] In step S8, the microbial test analysis is carried out on the water samples, including 16S rDNA sequencing, diversity analysis and species composition analysis, to obtain the microbial variation characteristics in the reservoir medium under the recharge driving.

[0018] Step S9, the flow process of the mine water in a medium area is simplified as a mine water horizontal one-dimensional movement process in the reservoir medium and a reservoir medium plugging process, a mathematical model of the composite plugging process under the recharging driving is established, and the model specifically includes the following steps:

[0019] Step S911, under the mine water recharging driving, the flow state of the mine water in the reservoir medium is judged by using the Reynolds number, and the formula is as follows: Formula (1), in the formula, Re is the Reynolds number of the water flow in the reservoir medium pores; ρ is the fluid density, kg / m 3 ; u is the pore flow rate of the fluid in the reservoir medium, m / s; μ is the dynamic viscous coefficient of the fluid, Pa·s; R is the hydrodynamic radius, m.

[0020] Step S912, under the laminar flow state, the water flow movement equation of the reservoir medium is expressed by using the Darcy law, and the equation for characterizing the relationship between the underground water flow and the permeability coefficient is as follows:

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

[0022] As a further improvement of the present application, when the reservoir medium contains microorganisms, the plugging condition of the microorganisms to the reservoir medium is judged, and the method specifically includes the following steps: Step S913, first, the mathematical equations of the microorganism and nutrient substance migration are constructed, and the migration ranges of the microorganism and the nutrient substance are determined, wherein formula (3) is the microorganism migration equation, and formula (4) is the nutrient substance migration equation:

[0023] Formula (3)

[0024] Formula (4), in the formula, D is the dispersion coefficient, L 2 / T; v is the pore water flow rate, L / T; n is the porosity; F B and F S are the source and sink terms of the suspended microorganism amount and the substrate concentration change, respectively, MV -1 T -1 ; B is the suspended microorganism concentration, M / V; and S is the nutrient substance concentration, M / V.

[0025] Step S914, a microorganism growth and decay model is constructed, and the change of the microorganism amount is calculated, and the specific formula is as follows: Formula (5), the Monod equation is used to calculate the growth amount of the microorganism, and the specific formula is as follows: Equation (6), the microbial decay is calculated by using the first order kinetic equation (7), and the specific formula is: Equation (7); in Equation (5), Equation (6) and Equation (7): r G is the growth rate of microorganisms, MV -1 T -1 , that is, the ratio of the growth rate of microorganisms to the concentration of microorganisms; μ g is the specific growth rate of microorganisms; μ g max is the maximum specific growth rate, T -1 ; X c is the concentration of microorganisms, MV -1 ; K S is the half-saturation constant, MV -1 ; r1 is the decay rate of microorganisms, MV -1 T -1 ; k1 is the decay rate coefficient of microorganisms, T -1 .

[0026] Step S915, the microorganisms grow by consuming nutrients, and the relationship between their growth and nutrient consumption is as follows: Equation (8), wherein: r s is the substrate degradation rate, MV -1 T -1 ; Y is the yield coefficient, MM -1 , that is, the amount of microorganisms produced per unit mass of organic matter.

[0027] Step S916, according to the law of conservation of mass, the suspended solids flowing in and out in the horizontal direction are equal to the cumulative change of the suspended solids per unit time, so the one-dimensional condition of the suspended solids transport process is: Equation (9), wherein: n is the porosity of the reservoir medium; C is the concentration of suspended solids suspended in the solution, MV -1 ; Cs is the mass of suspended solids deposited per unit pore space, MV -1 ; v x is the Darcy velocity, LT -1 ; the deposition amount of suspended solids in the medium can be described as: Equation (10), wherein: δ is the adsorption coefficient of suspended solids in the medium, T -1 , and ε is the desorption coefficient of suspended solids, T -1 ; Step S917, a mineral dissolution and precipitation model in water chemical components is established: the dissolution and precipitation equilibrium theory of minerals in the reaction phase is combined with the one-dimensional convection-diffusion equation to simulate the migration of minerals in the reservoir medium:

[0028] Equation (11), wherein: C che is the cation concentration of the mineral dissolution component in the solution after the injection, MV-1 ; F d MV is the mineral deposition amount in unit reservoir medium space -1 .

[0029] Step S918, a relationship between the medium porosity and the microbial accumulation, the suspended matter deposition and the mineral dissolution precipitation is constructed, and the specific formulas are as follows: Equation (12), Equation (13), Equation (14), wherein: n0 is the initial porosity; M is the microbial mass in unit volume of medium, MV -1 ; ρ is the microbial density, MV -1 , b ss is the packing factor of the suspended particles, reflecting the influence of the deposition morphology of the particles in the reservoir medium on the porosity, and is related to the particle deposition morphology; σ ss is the volume occupied by unit mass of the suspended matter particles, VM -1 ; b Ca is the calcite precipitation packing factor; σ Ca is the volume occupied by unit mass of the calcite precipitation, VM -1 ; F d is the calcite precipitation amount in unit volume of medium, MV -1 .

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

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

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

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

[0034] Compared with the prior art, the present application has the following technical effects: based on the water pressure, water quality test analysis data and microbial community characteristics and other related information obtained during the test process, the physical, chemical and biological processes in the deep mine water recharge reservoir medium process can be further analyzed, so as to reveal the multi-field coupling effect, which is specifically embodied in the following aspects: (1) Physical process level: the injection process of mine water under specific reservoir pressure and temperature conditions can be simulated, the dynamic change of pressure gradient in the injection process is monitored, the interaction of reservoir temperature field and injected water temperature field is controlled and monitored, and the groundwater dynamic field (including flow velocity, flow direction and permeability change) is simulated.

[0035] (2) Chemical process level: by simulating the recharge of different types of mine water, the changes of water chemical components (such as K⁺, Na⁺, Ca²⁺, Mg²⁺, SO4²⁻, HCO3⁻, Cl⁻) and mineral components in the migration process, and the precipitation, dissolution, adsorption, ion exchange and mutual influence between them can be tracked.

[0036] (3) Biological process level: the activities (such as metabolism, growth, death, biofilm formation) of microbial community (including indigenous and exogenous injected microorganisms) under specific pressure, temperature and water chemical environment, and the reaction (such as biological clogging, biodegradation) of the above fields (especially water chemical field and hydrodynamic field) can be studied.

[0037] (4) The present application combines the reservoir medium channel, uses Reynolds number to judge the flow state of mine water, uses Darcy's law to determine the laminar flow equation, builds a physical flow modeling framework; for the scenario of reservoir with microorganisms, the models of microbial migration and growth and decline, suspended matter deposition, mineral dissolution and precipitation are supplemented, the porosity and permeability are related, and the composite clogging modeling is improved; the general coefficient type partial differential equation of multi-field coupling is abstracted from the specific process of composite clogging, which provides scientific support for the multi-field coupling research of mine water recharge. BRIEF DESCRIPTION OF DRAWINGS

[0038] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0039] Figure 1 is the structural principle diagram of the mine water recharge multi-field coupling simulation experiment system of the present application.

[0040] Figure 2 is the internal structure diagram of the reservoir simulation box.

[0041] Explanation of reference signs: 1 - reservoir simulation tank, 11 - tank body, 12 - reservoir medium filling area, 121 - first medium area, 122 - second medium area, 123 - third medium area, 13 - aquiclude, 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 - heat preservation sleeve, 24 - first filter, 25 - second filter, 26 - third filter, 27 - first flow pump, 28 - second flow pump, 29 - third flow pump, 3 - produced water collection and detection system, 31 - first water sample collection tank, 32 - second water sample collection tank, 33 - third water sample collection tank, 34 - water quality analyzer, 4 - microorganism culture and injection system, 41 - microorganism storage tank, 42 - microorganism injection pump, DV - check valve, BV - back pressure valve, PG - pressure gauge, TS - temperature sensor. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0043] As Figure 1 and Figure 2As shown, a mine water recharge multi-field coupling simulation experiment system includes a reservoir simulation box 1, a mine water supply system 2, a produced water collection and detection system 3, and a microorganism culture and injection system 4. Specifically, the reservoir simulation box 1 includes a box body 11 made of stainless steel, which is open at the top and provided with an upper cover. A reservoir medium filling area 12 is arranged in the middle of the box body 11 for placing the reservoir medium. A water-resisting layer 13 is arranged above and below the reservoir medium filling area 12 for simulating the water-resisting layers above and below the real target reservoir. A rubber sleeve 14 is arranged above the upper water-resisting layer 13 and below the lower water-resisting layer 13, which is used to prevent the mine water from leaking between the water-resisting layer 13 and the inner wall of the box body 11. A temperature control jacket 16 is arranged above the upper rubber sleeve 14 and below the lower rubber sleeve 14, which is connected with a temperature controller 17. The temperature control jacket 16 is a waterproof jacket with resistance wire inside. Through the control of the temperature controller 17, the temperature of the reservoir medium filling area can be adjusted to simulate the temperature change of the real target reservoir, thereby providing a temperature field for the reservoir medium filling area 12. A pressure piston 15 is arranged between the upper temperature control jacket 16 and the upper rubber sleeve 14, which is connected with a pressure pump 18 for applying vertical pressure to the reservoir medium to provide the in-situ 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 is provided with a water inlet 21 on one side and connected with the flow pump through a pipeline on the other side. The flow pump is connected with the pipeline of the reservoir medium filling area 12. The produced water collection and detection system 3 includes a produced water collection tank and a water quality analyzer 34. The produced water collection tank is connected with the pipeline of the reservoir medium filling area 12, and the water quality analyzer 34 is connected with the pipeline of the produced water collection tank.

[0044] Specifically, the reservoir medium filling area 12 is divided into three layers of medium areas, i.e., a first medium area 121, a second medium area 122 and a third medium area 123, and a water-resisting layer 13 is arranged between each layer of medium areas, and the reservoir medium pore sizes of each layer of medium areas are the same or different. The mine water supply system 2 further comprises a staged filtration unit, which comprises a first filter 24, a second filter 25 and a third filter 26 connected in sequence from bottom to top by pipelines, and each of the first filter 24, the second filter 25 and the third filter 26 is provided with a filter membrane, and the pore sizes of the three filter membranes are sequentially reduced to form a three-stage filtration. One end of the first filter 24 is connected with the raw water storage tank 22 by a pipeline, and the other end is connected with the first medium area 121 by a pipeline through a first flow pump 27; the second filter 25 is connected with the second medium area 122 by a pipeline through a second flow pump 28, and the third filter 26 is connected with the third medium area 123 by a pipeline through a third flow pump 29. The produced water collection and detection system 3 comprises three water outlet pipes, one end of each of which is connected with the first medium area 121, the second medium area 122 and the third medium area 123 respectively, and the other end of each of which is connected with a first water sample collection tank 31, a second water sample collection tank 32 and a third water sample collection tank 33 respectively, and the first water sample collection tank 31, the second water sample collection tank 32 and the third water sample collection tank 33 are connected with a water quality analyzer 34 by pipelines. Each layer of medium area is provided with a temperature sensor TS connected with a temperature controller 17. The system combines staged filtration with zonal injection, can simulate the infiltration process of mine water at different depths and different filtration degrees in a real reservoir, is closer to the actual contact state of mine water and reservoir medium during recirculation, and avoids the problem that single filtration or single medium cannot restore complex reservoir conditions.

[0045] Sampling ports 19 are arranged in the first medium area 121, the second medium area 122 and the third medium area 123 respectively, and back pressure valves are connected, so that by connecting flow meters, pressure gauges, temperature sensors and other measuring instruments, the changes of water quality, temperature and pressure of mine water during the water sample flow process from the reservoir medium filling area can be obtained in real time, and the reservoir medium during the process can also be sampled for subsequent research.

[0046] The microbial culture and injection system 4 comprises a microbial storage tank 41 and a microbial injection pump 42, and nutrient solution and microbial bacteria solution can be injected into the first medium area 121, the second medium area 122 and the third medium area 123 respectively through the microbial injection pump 42.

[0047] Specifically, a heat preservation sleeve 23 is arranged outside the raw water storage tank 22 to heat the mine water in the raw water storage tank 22, and 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 representative core of the target reservoir or the artificially prepared reservoir medium is arranged in the reservoir medium filling area 12.

[0049] Specifically, a one-way valve DV is arranged on the output pipeline of the microbial injection pump 42, and whether the microbial injection into the reservoir medium filling area 12 is needed can be determined according to the experimental requirements. The one-way valve DV, the back pressure valve BV and the pressure gauge PG are arranged on the pipeline of the graded filtration unit leading to the reservoir medium filling area 12, and the same measuring components are also arranged on the three water outlet pipes.

[0050] The test system of the present application systematically integrates the interaction of stress field, groundwater dynamic field, water chemical field, temperature field and microbial field, breaks through the limitation of single field simulation of traditional devices, and visualizes the simulation of multi-field synergistic effect under complex geological conditions. For example, the injection process of mine water under specific reservoir pressure and temperature conditions can be simulated, the dynamic change of pressure gradient in the injection process can be monitored, the reservoir temperature field and its interaction with the injection water temperature field can be controlled and monitored; the changes, reactions (precipitation, dissolution, adsorption, ion exchange) and mutual influences of water chemical components (K + , Na + , Ca 2+ , Mg 2+ , SO4 2- , HCO3 - , Cl - ) and mineral components during migration can be tracked; the groundwater dynamic field (flow rate, flow direction, permeability change) can be simulated; the activities (metabolism, growth, death, biofilm formation) of microbial communities under specific pressure, temperature and water chemical environment and their reactions (such as biological clogging, biodegradation) on the above fields (especially water chemistry and hydrodynamics) can be studied.

[0051] The present application also provides a mine water injection multi-field coupling simulation experiment method, which comprises the following steps:

[0052] Step S1, in combination with the reservoir hydrogeological structure characteristics, the representative core or artificial reservoir medium of the target reservoir is put into the first medium area 121, the second medium area 122 and the third medium area 123 according to the same or different medium pore size; Step S2, the mine water in the raw water storage tank 22 is heated by using the heat preservation sleeve 23, and the temperature of the mine water is adjusted to the set temperature by 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 staged filtration unit, the mine water first passes through the first filter 24, and then is filtered and introduced into the first medium area 121; at the same time, the unfiltered mine water enters the second filter 25 from the first filter 24, is filtered and introduced into the second medium area 122; at the same time, the unfiltered mine water enters the third filter 26 from the second filter 25, is filtered and introduced into the third medium area 123; Step S4, the pressure pump 18 is opened, the vertical pressure is applied to the reservoir medium by the pressure piston 15, the heat preservation sleeve 16 is opened to heat the reservoir medium, so that the pressure and the temperature of the reservoir medium are consistent with those of the in-situ recharging stratum, and the real-time temperature is fed back to the temperature controller 17 through the temperature sensor TS; Step S5, the microbial injection pump 42 is opened, and the microorganisms in the microbial storage tank 41 are introduced into the pipelines of the first filter 24, the second filter 25 and the third filter 26 respectively, which are connected to the reservoir medium filling area 12; Step S6, the water sample, flow rate and pressure change during the recharging process are obtained through the three sampling ports 19; Step S7, the water quality analyzer 34 is used to monitor the water sample output from the first medium area 121, the second medium area 122 and the third medium area 123, to obtain the water quality temperature, pH, conductivity, oxidation-reduction potential, dissolved oxygen and turbidity, and to perform the conventional water chemical component analysis; Step S8, the water sample is subjected to microbial test analysis, including 16S rDNA sequencing, diversity analysis and species composition analysis, to obtain the microbial change characteristics in the reservoir medium under the recharging driving; Step S9, the flow process of the mine water in one medium area is simplified as a one-dimensional horizontal motion process of the mine water in the reservoir medium and a plugging process of the reservoir medium, and a mathematical model of the composite plugging process under the recharging driving is established, which specifically includes the following steps:

[0053] Step S911, under the recharging driving of the mine water, the flow state of the mine water in the reservoir medium is judged by using the Reynolds number, and the formula is as follows: Formula (1), in the formula, Re is the Reynolds number of the water flow in the reservoir medium pores; p is the fluid density, kg / m 3 ; u is the pore flow rate of the fluid in the reservoir medium, m / s; μ is the dynamic viscous coefficient of the fluid, Pa·s; R is the hydrodynamic radius, m.

[0054] Step S912, in the laminar flow state, the reservoir medium water flow motion equation is represented by the Darcy law, and the equation representing the relationship between the underground water flow and the permeability coefficient is as follows:

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

[0056] When the reservoir medium has microorganisms, the plugging of the microorganisms to the reservoir medium is determined, specifically including the following steps: step S913, first, a mathematical equation for the migration of microorganisms and nutrients is constructed, and the migration range of the microorganisms and nutrients is determined, wherein equation (3) is the migration equation of the microorganisms, and equation (4) is the migration equation of the nutrients:

[0057] Equation (3)

[0058] Equation (4), where: D is the dispersion coefficient, L 2 / T; v is the pore water flow rate, L / T; n is the porosity; F B and F S are source and sink terms for the suspended microorganism amount and the substrate concentration, respectively, MV -1 T -1 ; B is the suspended microorganism concentration, M / V; and S is the nutrient concentration, M / V.

[0059] Step S914, a model for the growth and decline of the microorganisms is constructed, and the change in the number of the microorganisms is calculated, and the specific formula is:

[0060] Equation (5), the growth amount of the microorganisms is calculated by using the Monod equation, and the specific formula is: Equation (6), the decline of the microorganisms is calculated by using the first-order kinetic equation (7), and the specific formula is: Equation (7); in equations (5), (6) and (7): r G is the growth rate of the microorganisms, MV -1 T -1 , that is, the ratio of the growth rate of the microorganisms to the microorganism concentration; μ g is the specific growth rate of the microorganisms; μ g max is the maximum specific growth rate, T -1 ; X c is the microorganism concentration, MV -1 ; K S is the half-saturation constant, MV -1 ; r1 is the microorganism decline rate, MV -1 T -1 ; and k1 is the microorganism decline rate coefficient, T​-1 .

[0061] Step S915, the microorganism grows by consuming nutrients, and the relationship between its growth and nutrient consumption is as follows: Equation (8), wherein: r s is the substrate degradation rate, MV -1 T -1 ; Y is the yield coefficient, MM -1 , i.e., the amount of microorganism produced per unit mass of organic matter.

[0062] Step S916, according to the law of conservation of mass, the inflow and outflow of suspended solids in the horizontal direction is equal to the cumulative change of suspended solids per unit time, so the one-dimensional condition of the suspended solids transport process is:

[0063] Equation (9), wherein: n is the porosity of the reservoir medium, C is the concentration of suspended solids suspended in the solution, MV -1 , Cs is the mass of suspended solids deposited per unit pore space, MV -1 , v x is the Darcy velocity, LT -1 ; the deposition amount of suspended solids in the medium can be described as:

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

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

[0066] Equation (11), wherein: C che is the cation concentration of the mineral dissolution component in the solution after the recharge, MV -1 ; F d is the mineral deposition amount per unit reservoir medium space, MV -1 .

[0067] Step S918, the relationship between the change of the medium porosity caused by the accumulation of microorganisms, the deposition of suspended solids, and the dissolution and precipitation of minerals is constructed, and the specific formulas are as follows:

[0068] Equation (12), Equation (13), Equation (14), wherein: n0 is the initial porosity; M is the mass of microorganisms per unit volume of medium, MV-1 ; p is the microorganism density, MV -1 , b ss is the packing factor of suspended particles, reflecting the influence of the deposition morphology of particles in the reservoir medium on porosity, and is related to the particle deposition morphology; sigma ss is the volume occupied by unit mass of suspended particles, VM -1 ; b Ca is the calcite precipitation packing factor; sigma Ca is the volume occupied by unit mass of calcite precipitation, VM -1 ; F d is the amount of calcite precipitation in unit volume of medium, MV -1 .

[0069] Step S919, the relationship between the porosity of the medium and the permeability is represented by the Kozeny-Carmen formula:

[0070] Formula (15), wherein: 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] A multi-field coupling coefficient type partial differential equation is constructed as follows:

[0072] Formula (16), wherein: w is the dependent variable; c is the diffusion coefficient; alpha is the absorption coefficient; f is the source term; e a is the mass coefficient; da is the attenuation coefficient; a is the conservation flux convection coefficient; beta is the convection coefficient; gamma is the conservation flux source.

[0073] The test method of the present application provides a favorable technical means for further in-depth study of the change law of the permeability of the deep recharge reservoir of mine water and the evolution mechanism of the groundwater environment under the action of five fields, and can evaluate the long-term influence of different recharge schemes (water quality, temperature, and rate) on the reservoir properties (permeability) and water quality (potential pollution), and provide protection for the long-term safety of mine water deep well recharge. In combination with the above, the evolution law of the groundwater environment and the evolution mechanism of the permeability under the driving of mine water deep well recharge are further revealed. The present application determines the flow state by the Reynolds number and determines the laminar flow equation by Darcy's law, provides a physical flow basis for modeling the flow of mine water in the reservoir medium, and supports subsequent plugging and multi-field coupling analysis. The models related to microorganisms, suspended solids, and minerals are supplemented and related to porosity and permeability, the composite plugging modeling is improved, and the physical-biological-chemical coupling plugging mechanism and the influence on the permeability when there are microorganisms in the reservoir are accurately revealed. The general equation of multi-field coupling is abstracted, the specific plugging process is upgraded to a macro multi-field action framework, a general mathematical tool is provided for multi-field coupling effect analysis, and help is provided for comprehensively exploring the multi-field evolution law of the reservoir under recharge.

[0074] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited to this, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application, and all of them are within the scope of the claims of the present application.

Claims

1. A mine water recharge multi-field coupling simulation experimental system, characterized in that: include A reservoir simulation box (1) comprises a box body (11), wherein 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); 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); 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) pipeline for applying pressure to the reservoir medium; A mine water supply system (2) includes a raw water storage tank (22) and a flow pump, wherein the raw water storage tank (22) is connected to a flow pump pipeline, and the flow pump is connected to a reservoir medium filling area (12) pipeline; A produced water collection and detection system (3) includes a produced water collection box and a water quality analyzer (34), wherein the produced water collection box is connected to a pipeline of the reservoir medium filling area (12), and the water quality analyzer (34) is connected to the pipeline of the produced water collection box; The microorganism culture and injection system (4) includes a microorganism storage tank (41) and a microorganism injection pump (42). The microorganism storage tank (41) is connected to the microorganism injection pump (42) through a pipeline, and the microorganism injection pump (42) is connected to the reservoir medium filling area (12) through a pipeline.

2. The mine water recharge multi-field coupling simulation experimental system according to claim 1 is characterized in that: 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-blocking layer (13) is provided between each medium area, and reservoir medium of the same or different lithology is placed in each medium area; the mine water supply system (2) also includes a graded filtration unit, which includes a first filter (24), a second filter (25) and a third filter (26) connected in sequence from bottom to top by pipelines, the first filter (24), the second filter (25) and the third filter (26) are all provided with filter membranes, and the pore sizes of the three filter membranes decrease in sequence to form a three-stage filtration; one end of the first filter (24) is connected to the raw water storage tank (22) pipeline, and the other end is connected to the first medium area (121) through a pipeline via a first flow pump (27); The second filter (25) is connected to the second medium area (122) pipeline via the second flow pump (28), and the third filter (26) is connected to the third medium area (123) pipeline via the third flow pump (29); the produced water collection and detection system (3) includes three water outlet pipes, one end of the water outlet pipes is connected to the first medium area (121), the second medium area (122) and the third medium area (123), respectively, and the other end is connected to the first water sample collection box (31), the second water sample collection box (32) and the third water sample collection box (33), respectively. The first water sample collection box (31), the second water sample collection box (32) and the third water sample collection box (33) are connected to the water quality analyzer (34) pipeline; each layer of the medium area is provided with a temperature sensor (TS), and the temperature sensor (TS) is connected to the temperature controller (17).

3. The mine water recharge multi-field coupling simulation experimental system according to claim 1 is characterized in that: A heat-insulating sleeve (23) is provided on the outer bottom of the raw water storage tank (22), and the heat-insulating sleeve (23) is connected to the temperature controller (17).

4. The mine water recharge multi-field coupling simulation experimental system according to claim 1 is characterized in that: The raw water storage tank (22) stores real mine water, or simulated mine water with different suspended matter and water chemical characteristic components is artificially prepared according to experimental requirements.

5. The mine water recharge multi-field coupling simulation experimental system according to claim 2 is characterized in that: Sampling ports (19) are respectively provided in the middle of the first medium area (121), the second medium area (122) and the third medium area (123), and back pressure valves are provided on the sampling ports (19).

6. A method for simulating the multi-field coupling effect of mine water recharge, according to the multi-field coupling effect simulation experimental system of mine water recharge according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step S1: Based on the hydrogeological structural characteristics of the reservoir, representative rock cores of the target reservoir or artificially prepared reservoir media are placed into the first medium area (121), the second medium area (122), and the third medium area (123) according to the same or different medium pore sizes; Step S2: using the heat preservation jacket (23) to heat the mine water in the raw water storage tank (22), and regulating the temperature of the mine water to a set temperature through the thermostat (17); Step S3: The mine water in the raw water storage tank (22) is sent to the reservoir medium filling area (12) through the graded filtration unit. The mine water first passes through the first filter (24) and is filtered before entering the first medium area (121). At the same time, the unfiltered mine water passes through the first filter (24) and enters the second filter (25) and is filtered before entering the second medium area (122). At the same time, the unfiltered mine water passes through the second filter (25) and enters the third filter (26) and is filtered before entering the third medium area (123). Step S4: Turn on the pressure pump (18), apply vertical pressure to the reservoir medium via the pressure piston (15), turn on the temperature control jacket (16) to heat the reservoir medium, make the reservoir medium consistent with the pressure and formation temperature of the in-situ recharged formation, and feed back the real-time temperature to the temperature controller (17) via the temperature sensor (TS); Step S5: Turn on the microorganism injection pump (42) to pass the microorganism liquid in the microorganism 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, obtaining water samples, flow rate and pressure changes during the recharging process through three sampling ports (19); Step S7: using a water quality analyzer (34) to monitor the water samples output from the first medium area (121), the second medium area (122), and the third medium area (123), obtaining water quality temperature, pH, conductivity, redox potential, dissolved oxygen, and turbidity, and performing conventional water chemical component analysis; Step S8: conducting microbial testing and analysis on the water sample, including 16S rDNA sequencing, diversity analysis, and species composition analysis, to obtain characteristics of microbial changes in the reservoir medium under recharge; Step S9: Simplify the flow process of mine water in a medium area 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 driven by recharge, which specifically includes the following steps: Step S911: Under the driving force 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: Formula (1), Where: Re is the Reynolds number of water flowing in the pores of the reservoir medium; ρ is the fluid density, kg / m 3 ; u is the pore flow 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 reservoir medium water flow equation is expressed using Darcy's law, which represents the relationship between groundwater flow and permeability coefficient: Formula (2), Where: Kx is the horizontal permeability coefficient, MT -1 ;μ s is the water release rate, L -1 ; ∂H / ∂x represents the speed of change of water head per unit distance moved in the horizontal direction; ∂H / ∂t represents the rate of change of water head with time.

7. The multi-field coupling simulation experimental method for mine water recharge according to claim 6 is characterized in that: When microorganisms exist in the reservoir medium, determining the blockage of the reservoir medium by the microorganisms specifically includes the following steps: Step S913: First, construct a mathematical equation for the migration of microorganisms and nutrients to clarify the migration range of microorganisms and nutrients. Formula (3) is the microorganism migration equation, and formula (4) is the nutrient migration equation: Formula (3), Formula (4), Where: D is the diffusion coefficient, L 2 / T; v is the pore water velocity, L / T; n is the porosity; F B and F S are the source and sink items of suspended microbial biomass and substrate concentration changes, MV -1 T -1 ; B is the concentration of suspended microorganisms, M / V; S is the concentration of nutrients, M / V; Step S914: construct a microbial growth and decay model to calculate the change in microbial population. The specific formula is: Formula (5), The Monod equation was used to calculate the growth of microorganisms. The specific formula is: Formula (6), Microbial decay was calculated using the first-order kinetic equation (7), and the specific formula is: Formula (7), In formula (5), formula (6) and formula (7): r G is the growth rate of the microorganism, MV -1 T -1 , that is, the ratio of microbial growth rate to microbial concentration; μ g is the specific growth rate of microorganisms; μ g max is the maximum specific growth rate, T -1 ;X c is the microbial concentration, MV -1 ;K S is the half-saturation constant, MV -1 ; r1 is the microbial decay rate, MV -1 T -1 ; k1 is the microbial decay rate coefficient, T -1 ; Step S915: Microorganisms grow by consuming nutrients. The relationship between their growth and nutrient consumption is as follows: Formula (8), Where: r s is the matrix degradation rate, MV -1 T -1 ; Y is the yield coefficient, MM -1 , that is, the amount of microorganisms produced by degrading unit mass of organic matter; Step S916: According to the law of conservation of mass, the amount of suspended matter flowing in and out in the horizontal direction is equal to the cumulative change of suspended matter per unit time. Therefore, the suspended matter migration process under one-dimensional conditions is: Formula (9), Where: n is the porosity of the reservoir medium; C is the concentration of suspended matter in the solution, MV -1 ; Cs is the mass of suspended matter deposited per unit pore space, MV -1 ;v x is the Darcy speed, LT -1 ; The amount of suspended matter deposited in a medium can be described as: Formula (10), Where: δ is the adsorption coefficient of suspended matter in the medium, T -1 , ε is the suspended matter desorption coefficient, T -1 ; Step S917: Establish a mineral dissolution and precipitation model in the water chemical components: Use the dissolution and precipitation equilibrium theory of minerals in the reaction phase combined with the one-dimensional convection-diffusion equation to simulate the migration of minerals in the reservoir medium: Formula (11), Where: C che is the cation concentration of the mineral dissolved components in the solution after reinjection, MV -1 ; F d is the mineral deposition volume per unit reservoir medium space, MV -1 ; Step S918: Construct the relationship between the media porosity changes caused by microbial accumulation, suspended solids deposition, and mineral dissolution and precipitation. The specific formulas are: Formula (12), Formula (13), Formula (14), Where: n0 is the initial porosity; M is the mass of microorganisms per unit volume of medium, MV -1 ; ρ is microbial density, MV -1 , b ss is the accumulation factor of suspended particles, reflecting the effect of the deposition morphology of particles in the reservoir medium on the porosity, and is related to the particle deposition morphology; σ ss VM is the volume occupied by unit mass of suspended particles. -1 ; b Ca is the calcite precipitation accumulation factor; σ Ca is the volume occupied by unit mass of calcite precipitation, VM -1 ; F d is the amount of calcite precipitation per unit volume of medium, MV -1 ; Step S919: The relationship between medium porosity and permeability is expressed by the Kozeny-Carmen formula: Formula (15), Where: 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.

8. The multi-field coupling simulation experimental method for mine water recharge according to claim 7 is characterized in that: Construct the multi-field coupling coefficient type partial differential equation as follows: Formula (16), Where: w is the dependent variable; c is the diffusion coefficient; α is the absorption coefficient; f is the source term; e a 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