Simulation test device and method for deep reinjection of high-salt mine well water under high-temperature and high-pressure conditions

Abstract

The invention provides a simulation test device and method for deep reinjection of high-salt mine well water under high-temperature and high-pressure conditions. The simulation test device comprises a confining pressure cabin, and a sealing cover is arranged at the top of the confining pressure cabin; in the confining pressure cabin, the upper end of a rubber sleeve is detachably and hermetically sleeved on the water injection pressure head, the lower end of the rubber sleeve is detachably and hermetically sleeved on the water outlet pressure head, and cavities among the water injection permeable plate, the water outlet permeable plate and the rubber sleeve form a water-rock reaction cavity. An oil inlet which is through inside and outside is formed in the side wall of the confining pressure cabin; the oil inlet is connected with a pressure control oil pump through an external oil inlet pipe; an oil outlet which is through inside and outside is formed in the side wall of the confining pressure cabin, the oil outlet is connected with an external oil outlet pipe, and an oil outlet valve is installed on the oil outlet pipe. And a temperature sensor and a temperature control heating sheet are mounted on the inner wall of the confining pressure cabin. The method comprises the following steps: step 1, preparing a mine water reinjection test; and 2, performing reinjection simulation and blockage judgment. And step 3, treatment and analysis after the test. According to the device, the confining pressure borne by rock can be controlled through oil pressure, oil can be heated, and the high-temperature condition of a deep stratum can be controlled through a temperature monitoring system when mine water is reinjected.

Description

Technical Field

[0001] This invention belongs to the field of deep mine water reinjection technology, and relates to a simulation test device, specifically a simulation test device and method for deep mine water reinjection under high temperature and high pressure conditions. Background Technology

[0002] During coal mining, groundwater is disturbed by mining operations, causing it to flow into the working face, roadways, and goaf along water-conducting fracture zones, forming mine water. In the aquifer stage, groundwater undergoes long-term water-rock interaction with the surrounding rock. During the coal mining stage, the mine water continues to interact with broken coal and rock, while also being affected by human factors such as coal mining machinery, ultimately resulting in mine water containing numerous ions, suspended solids, and other components.

[0003] In western my country's mining areas, due to the influence of original strata and coal seam deposition, groundwater and mine water often exhibit high salinity, with total dissolved solids in mine water generally exceeding 1000 mg / L, and reaching as high as 20000 mg / L. To prevent the direct discharge of high-salinity mine water from exacerbating soil salinization in western China, desalination treatment is generally performed. However, this method is costly and faces the challenge of disposing of even higher salinity tailwater. Therefore, based on research and demonstration practices by industry experts, a deep reinjection technology for high-salinity mine water has been proposed. This involves reinjecting high-salinity mine water into a deep aquifer at a depth of approximately 2000 meters for storage. This addresses the problem of high-salinity mine water treatment while simultaneously replenishing water resources lost due to mining. With increased mine water reinjection depth, temperatures and pressures rise compared to shallower layers, presenting unprecedented challenges. Under these high-temperature, high-pressure conditions, questions remain regarding the potential for blockage in the reinjection layer and how to select parameters such as reinjection pressure to avoid blockage. Furthermore, direct deep reinjection in the field carries significant unknown risks and incurred prohibitive costs for on-site testing. Therefore, conducting indoor physical simulations before deep reinjection is crucial. Simulating the high-temperature, high-pressure conditions at depth allows for the study of the target reinjection layer's water storage capacity, assessing the likelihood of blockage and determining the necessary reinjection parameters. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a simulation test device and method for deep reinjection of high-salt mine water under high temperature and high pressure conditions, thereby solving the technical problem that existing simulation test devices and methods are difficult to apply to blockage determination.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions includes a confining chamber with a sealed cover on top. A hollow, sealed water injection head is detachably installed inside the confining chamber, with its bottom surface configured as a permeable water injection plate. A base is fixedly installed at the bottom of the confining chamber, and a hollow, sealed water outlet head is installed on the base, with its top surface configured as a permeable water outlet plate. The water injection head and the water outlet head are coaxially arranged. The upper end of the water injection head is detachably sealed with a rubber sleeve, and the lower end of the water outlet head is also detachably sealed with a rubber sleeve. The cavity between the permeable water injection plate, the permeable water outlet plate, and the rubber sleeve forms a water-rock reaction chamber.

[0007] The confining chamber has an inlet pipe through-hole on its side wall, with an inlet pipe sealed inside the through-hole. One end of the inlet pipe is connected to an external injection water pump, and an external inlet valve is installed on the inlet pipe. The other end of the inlet pipe is connected to the hollow cavity inside the injection head. The confining chamber also has an outlet pipe through-hole on its side wall, with an outlet pipe sealed inside the through-hole. One end of the outlet pipe passes through a base and connects to the hollow cavity inside the outlet head.

[0008] The confining chamber has an oil inlet that runs through both the inside and outside of its side wall, and the oil inlet is connected to a pressure control oil pump via an external oil inlet pipe; the confining chamber also has an oil outlet that runs through both the inside and outside of its side wall, and the oil outlet is connected to an external oil outlet pipe, on which an oil outlet valve is installed.

[0009] The confining chamber has through holes on its side walls for wires to pass through, and signal and power lines are sealed through these holes. A temperature sensor and a temperature-controlled heating element are installed on the inner wall of the confining chamber. The temperature sensor is connected to the input of an external temperature controller via a signal line, and the temperature-controlled heating element is connected to the output of an external temperature controller via a signal line. The temperature-controlled heating element is connected to an external power source via a power line.

[0010] The present invention also has the following technical features.

[0011] The water injection head and the rubber sleeve are detachably sealed together by a sealing clamp; the water outlet head and the rubber sleeve are detachably sealed together by a sealing clamp.

[0012] The water inlet pipe is equipped with a water pressure gauge; the oil inlet pipe is equipped with an oil pressure gauge; and the water outlet pipe is equipped with an outlet pressure sensor and an outlet flow sensor.

[0013] The water pressure sensor is connected to the water pressure monitor, and the water flow sensor is connected to the water flow monitor.

[0014] A sealing ring is provided between the sealing cover and the confining chamber, and the sealing is achieved by sealing bolts.

[0015] This invention also protects a simulation test method for deep reinjection of high-salt mine water under high temperature and high pressure conditions. The method uses the simulation test device for deep reinjection of high-salt mine water under high temperature and high pressure conditions as described above. The method includes the following steps.

[0016] Step 1: Preparation for mine water reinjection test.

[0017] Step 101: Core collection and pretreatment of the target layer for mine water reinjection.

[0018] Step 102: Initialization of high temperature and high pressure environment.

[0019] Step 10201: Initialize confining pressure.

[0020] Step 10202: Initialize temperature.

[0021] Step 2: Reinjection simulation and blockage determination.

[0022] Step 201, simulation of mine water reinjection under high temperature and high pressure coupling conditions.

[0023] Step 202: Real-time monitoring and penetration rate calculation.

[0024] Step 3: Post-experiment processing and analysis.

[0025] Step 301, analysis of blockage.

[0026] Step 302, optimize the injection parameters.

[0027] Compared with the prior art, the present invention has the following technical effects.

[0028] (I) The device of the present invention can not only control the confining pressure on the rock through oil pressure, but also control the high temperature conditions of deep formations during mine water reinjection through a temperature monitoring system by heating the oil. In addition, water volume and pressure sensors are installed at the inlet and outlet of the mine water reinjection to monitor the reinjection volume and pressure, which facilitates the determination of the key parameter of mine water reinjection pressure.

[0029] (II) The device of the present invention simulates the situation of rocks being subjected to high pressure in deep strata by injecting hydraulic oil into the confining chamber, which is different from the previous reinjection device that did not take pressure into account.

[0030] (III) The device of the present invention heats the confining oil to simulate the high temperature of rocks in deep formations, which is different from the previous reinjection device that only considers the normal temperature.

[0031] (IV) The method of the present invention determines the blockage of rocks by the change characteristics of rock permeability, and then determines the optimal mine water injection pressure parameters, providing basic data and reference for deep mine water reinjection. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the simulation test device for deep reinjection of high-salt mine water under high temperature and high pressure conditions according to the present invention.

[0033] Figure 2(a) shows a CT scan of the rock after the plugging test.

[0034] Figure 2(b) shows the porosity of the rock cross section after the plugging test.

[0035] The labels in the diagram represent the following: 1-Ballastage chamber, 2-Sealing cover, 3-Water injection head, 4-Water injection permeable plate, 5-Base, 6-Water outlet head, 7-Water outlet permeable plate, 8-Rubber sleeve, 9-Water-rock reaction chamber, 10-Inlet pipe through hole, 11-Inlet pipe, 12-Pressure injection pump, 13-Inlet valve, 14-Outlet pipe through hole, 15-Outlet pipe, 16-Oil inlet, 17-Oil inlet pipe, 18-Pressure control oil pump, 19-Oil outlet, 20-Oil outlet. Pipe, 21-Oil outlet valve, 22-Wire through hole, 23-Temperature sensor, 24-Temperature control heating element, 25-Temperature controller, 26-Power supply, 27-Sealing clamp, 28-Inlet water pressure gauge, 29-Inlet oil pressure gauge, 30-Outlet water pressure sensor, 31-Outlet water flow sensor, 32-Outlet water pressure monitor, 33-Outlet water flow monitor, 34-Sealing ring, 35-Sealing bolt, 36-Bracket, 37-Support ring, 38-Boss.

[0036] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, all devices, instruments, sensors, and components in this invention are those known in the prior art. All locations requiring sealing in this invention are sealed using sealing methods commonly known in the art.

[0038] In this invention, high-salinity mine water refers to mine water with a salt concentration of 1000 mg / L or higher.

[0039] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0040] Example 1: This embodiment provides a simulation test device for deep reinjection of high-salt mine water under high temperature and high pressure conditions, including a confining chamber 1, with a sealing cover 2 on the top of the confining chamber 1; a hollow and sealed water injection head 3 is detachably installed inside the confining chamber 1, and the bottom surface of the water injection head 3 is set as a water injection permeable plate 4; a base 5 is fixedly installed at the bottom inside the confining chamber 1, and a hollow and sealed water outlet head 6 is installed on the base 5, with a water outlet permeable plate 7 on the top surface of the water outlet head 6; the water injection head 3 and the water outlet head 6 are coaxially arranged, and the upper end of the detachable sealing sleeve 8 is fitted on the water injection head 3, and the lower end of the detachable sealing sleeve 8 is fitted on the water outlet head 6; the cavity between the water injection permeable plate 4, the water outlet permeable plate 7, and the sleeve 8 forms a water-rock reaction chamber 9.

[0041] The confining chamber 1 has an inlet pipe through hole 10 that runs through both the inside and outside. An inlet pipe 11 is sealed inside the inlet pipe through hole 10. One end of the inlet pipe 11 is connected to an external injection water pump 12. An external inlet valve 13 is installed on the inlet pipe 11. The other end of the inlet pipe 11 is connected to the hollow cavity inside the injection head 3. The confining chamber 1 has an outlet pipe through hole 14 that runs through both the inside and outside. An outlet pipe 15 is sealed inside the outlet pipe through hole 14. One end of the outlet pipe 15 passes through the base 5 and is connected to the hollow cavity inside the outlet head 6.

[0042] The confining chamber 1 has an oil inlet 16 that runs through the inside and outside of the side wall. The oil inlet 16 is connected to the pressure control oil pump 18 through an external oil inlet pipe 17. The confining chamber 1 has an oil outlet 19 that runs through the inside and outside of the side wall. The oil outlet 19 is connected to an external oil outlet pipe 20. An oil outlet valve 21 is installed on the oil outlet pipe 20.

[0043] The confining chamber 1 has a through hole 22 on its side wall, through which signal wires and power wires pass. A temperature sensor 23 and a temperature-controlled heating element 24 are installed on the inner wall of the confining chamber 1. The temperature sensor 23 is connected to the input terminal of an external temperature controller 25 via a signal wire, and the temperature-controlled heating element 24 is connected to the output terminal of an external temperature controller 25 via a signal wire. The temperature-controlled heating element 24 is connected to an external power source 26 via a power wire.

[0044] In this embodiment, a bracket 36 is fixedly installed on the inner wall of the ballast chamber 1, a support ring 37 is provided in the middle of the bracket, a boss 38 is provided on the outer wall of the water injection head 3, the water injection head 3 is fitted inside the support ring 37, and the boss 38 contacts the upper surface of the support ring 37, so that the water injection head 3 can be detachably installed in the ballast chamber 1.

[0045] In this embodiment, the water injection head 3 is equipped with a sealing connector. One end of the sealing connector is sealed to the other end of the water inlet pipe 11, and the other end of the sealing connector is integrally formed with the water injection head 3 and connected to the hollow cavity inside the water injection head 3, thereby achieving a sealed connection between the other end of the water inlet pipe 11 and the hollow cavity inside the water injection head 3. The sealing connector adopts a commonly used sealing connector known in the art.

[0046] In this embodiment, both the water injection permeable plate 4 and the water outlet permeable plate 7 are permeable plates commonly known in the art, such as permeable plates with multiple evenly distributed permeable holes. The water injection permeable plate 4 and the water outlet permeable plate 7 can be fixedly connected to the water injection head 3 and the water outlet head 6 or detachably connected as needed, preferably detachably connected.

[0047] In a preferred embodiment, a detachable sealing assembly is achieved between the water injection head 3 and the rubber sleeve 8 via a sealing clamp 27; a detachable sealing assembly is also achieved between the water outlet head 6 and the rubber sleeve 8 via a sealing clamp 27. The sealing clamp 27 is used to ensure the sealing performance of the water-rock reaction chamber 9 under high pressure.

[0048] In a preferred embodiment, an inlet pressure gauge 28 is installed on the inlet pipe 11; an oil pressure gauge 29 is installed on the oil inlet pipe 17; and an outlet pressure sensor 30 and an outlet flow sensor 31 are installed on the outlet pipe 15. The outlet pressure sensor 30 is connected to the outlet pressure monitor 32, and the outlet flow sensor 31 is connected to the outlet flow monitor 33.

[0049] In this embodiment, the water flow sensor 31 is an electromagnetic flow sensor. This sensor has the advantages of high measurement accuracy, wide range ratio and no pressure loss. It is suitable for real-time measurement of mine water flow. Its measurement principle is based on Faraday's law of electromagnetic induction and can accurately measure water flow at different flow rates.

[0050] As a preferred embodiment, a sealing ring 34 is provided between the sealing cover 2 and the confining chamber 1, and the sealing is installed by sealing bolts 35.

[0051] In this embodiment, hydraulic oil is added to the confining chamber 1 by the pressure-controlled oil pump 18, and pressure is applied to the rock sample in the water-rock reaction chamber 9 by the hydraulic oil outside the rubber sleeve 8, so as to provide confining pressure to the rock sample.

[0052] In this embodiment, the device of the present invention can simulate the water-rock reaction that occurs when mine water enters deep formations. Rock samples from the target reinjection layer are placed into the water-rock reaction chamber 9 within a rubber sleeve 8, and the rubber sleeve 8 is sealed using a sealing clamp 27. The water-rock reaction chamber 9 is the core reaction chamber of the device. Water is injected into the injection head 3 via the inlet pipe 11, and then evenly distributed to the upper end of the rock sample within the water-rock reaction chamber 9 via the water permeable plate 4. Long-term water-rock reaction occurs between the rock sample from the target reinjection layer and the mine water supplied from the storage tank within the water-rock reaction chamber 9, simulating the long-term contact and reaction between mine water reinjected into the formation under high temperature and high pressure conditions. The reacted fluid is discharged from the outlet pipe 15 after passing through the outlet permeable plate 7 and the outlet head 6. The fluid in the outlet pipe 15 is monitored by the outlet pressure sensor 30 and the outlet flow sensor 31, thereby simulating and monitoring the entire reinjection process.

[0053] Example 2: This embodiment provides a simulation test method for deep reinjection of high-salt mine water under high temperature and high pressure conditions. The method uses the simulation test device for deep reinjection of high-salt mine water under high temperature and high pressure conditions given in Embodiment 1.

[0054] Specifically, in this embodiment, the Xiaobaodang Coal Mine is located in the southwest of Shenmu City, Yulin City, Shaanxi Province, and is administratively under the jurisdiction of Dabaodang Town, Shenmu City, Yulin City. The Xiaobaodang Coal Mine mining area is 101 km². 2 There are nine mineable coal seams, most of which contain multiple layers of interbedded gangue. Coal seam 2-2 is the main mining seam, with a simple structure and one to two layers of interbedded gangue. Currently, the mine has achieved a smart, efficient, and green mining model with a capacity of 15 million tons per mine face. The strata in the mining area, from oldest to newest, include: the Permian Upper Shihezi Formation and Shiqianfeng Formation; the Triassic Liujiagou Formation, Heshanggou Formation, Ermaying Formation, Yanchang Formation, and Yongping Formation; the Jurassic Fuxian Formation, Yan'an Formation, Zhiluo Formation, and Anding Formation; the Neogene (N) and Quaternary (Q) strata. Currently, the No. 2 coal seam is mainly mined. The average mineralization of the mine drainage is 1600 mg / L. To reduce desalination costs, the mine water is reinjected into the Liujiagou Formation.

[0055] The method includes the following steps.

[0056] Step 1: Preparation for mine water reinjection test.

[0057] Step 101: Core collection and pretreatment of the target layer for mine water reinjection.

[0058] During the drilling phase, core samples are collected from the target layer for mine water reinjection (such as sandstone, argillaceous sandstone, etc.) and processed into cylindrical rock samples with a diameter of 50 mm and a height of 100 mm. Subsequently, the processed rock samples are placed into the water-rock reaction chamber 9, which is fitted with a rubber sleeve 8, and sealed with a sealing cap 2 to ensure the airtightness of the water-rock reaction chamber 9.

[0059] In this specific embodiment, during the drilling phase, sandstone cores of the Liujiagou Formation were collected and processed into cylindrical rock samples with a diameter of 50 mm and a height of 100 mm. After processing, the samples were set aside for later use.

[0060] Step 102: Initialization of high temperature and high pressure environment.

[0061] Step 10201: Initialize confining pressure.

[0062] Start the pressure control oil pump 18 in the high temperature and high pressure control system, add hydraulic oil into the confining chamber 1 through the oil inlet pipe 17, and apply pressure to the rock sample in the water-rock reaction chamber 9 through the hydraulic oil outside the rubber sleeve 8; adjust the confining pressure according to the value displayed on the oil inlet pressure gauge 29, and control the initial value of the confining pressure to 48MPa to simulate the confining pressure of the actual reinjected formation at a depth of 2000m.

[0063] In step 10201, considering pressure transmission loss, the relationship between the displayed value on the inlet pressure gauge 29 and the confining pressure is: σ = η P; where σ represents the confining pressure value borne by the rock sample; η represents the pressure transmission coefficient, which, after multiple tests, is 0.85 for the pressure transmission coefficient of the simulation test device under high temperature and high pressure conditions for deep reinjection of high-salt mine water given in Example 1; P represents the displayed value on the oil inlet pressure gauge.

[0064] In this specific embodiment, the initial confining pressure of 48 MPa corresponds to a reading of 56.48 MPa on the inlet pressure gauge 29, so the control oil pressure is 56.48 MPa.

[0065] Step 10202: Initialize temperature.

[0066] The temperature of the temperature-controlled heating element 24 is adjusted to 65°C by the temperature controller 25 to simulate the temperature of the actual reinjected formation at a depth of 2000m.

[0067] Step 2: Reinjection simulation and blockage determination.

[0068] Step 201, simulation of mine water reinjection under high temperature and high pressure coupling conditions.

[0069] While maintaining the initial confining pressure and initial temperature conditions in step one, open the inlet valve 15 on the inlet pipe 11 and inject mine water from the injection head 3 into the water-rock reaction chamber 9 through the injection pump 12; control the initial reinjection water pressure to 0.5MPa, 1.0MPa and 1.5MPa respectively, and conduct multiple sets of comparative reinjection experiments.

[0070] Step 202: Real-time monitoring and penetration rate calculation.

[0071] In the mine water reinjection simulation in step 201, the pressure difference between the mine water reinjection inlet and outlet is obtained based on the inlet pressure monitored by the inlet pressure gauge 28 and the outlet pressure monitored by the outlet pressure sensor 30. The reinjection flow rate is monitored in real time by the outflow flow sensor 31. Then, using Darcy's law formula, every... Permeability of rock samples is calculated periodically. When the penetration rate If the drop rate is greater than 50%, it is determined that there is a serious blockage inside the rock sample.

[0072] In step 202, Darcy's law formula is: ; In the formula: Indicates the sample Average permeability over a period of time, expressed in m / s; express The reinjection flow rate through the rock sample within a given time, expressed in m³. 3 ; The viscosity coefficient of mine water is expressed in Pa·m. -1 ; This indicates the length of the seepage path of mine water in a rock sample, i.e., the height of the rock sample, in meters (m). This represents the cross-sectional area of ​​the rock sample, in m². 2 ; This indicates the pressure difference between the inlet and outlet water in mine water reinjection, expressed in Pa.

[0073] In this specific embodiment, based on the water-rock interaction between mine water and rock samples, the monitoring results are substituted into Darcy's law formula to calculate the change in permeability. The flow rate and pressure at the inlet and outlet were monitored in real time every 3 hours. Table 1 shows the change in permeability when the initial injection pressure of the mine water was 0.5 MPa.

[0074] Table 1. Changes in flow rate and pressure parameters at the outlet and calculation of permeability (initial injection pressure 0.5 MPa)

[0075] As shown in Table 1, from the 3rd hour to the 18th hour, the pressure difference between the mine water inlet and outlet remained at 0.31 MPa, and the permeability was 1.3 × 10⁻⁶. -6From 18 to 39 hours, the pressure at the mine water inlet and outlet continuously decreased, reaching 0.16 MPa at 39 hours, at which point the permeability was 2.5 × 10⁻⁶ m / s. -6 The permeability was approximately 50% of its original value, indicating that blockage had begun. With the passage of time, at 57 hours, the pressure difference between the inlet and outlet was 0.05 MPa, and the permeability stabilized at 8.2 × 10⁻⁶ m / s. -6 m / S.

[0076] To prolong the time before blockage occurs, the pressure of the mine water injection at the inlet is increased. When the pressure at the inlet is 1.0 MPa, observations are continued every 3 hours, and the permeability change is calculated, as shown in Table 2.

[0077] Table 2. Changes in flow rate and pressure parameters at the outlet and calculation of permeability (initial injection pressure 1 MPa)

[0078] As shown in Table 2, from the 3rd hour to the 12th hour, the pressure difference between the mine water inlet and outlet increased from 0.22 MPa to 0.58 MPa, and the permeability increased from 26.8 × 10⁻⁶ MPa. -6 m / S decreased to 10.1 × 10 -6 Although the permeability was 50% of the original, no blockage occurred. Subsequently, as time progressed, at 66 hours, the pressure difference was 0.99 MPa and the permeability was 5.95 × 10⁻⁶ m / s. -6 The permeability m / S is still greater than the minimum permeability of 8.2 × 10⁻⁶ when the injection pressure is 0.5 MPa. -6 m / S. This proves that when the water injection pressure is increased to 1.0 MPa, blockage no longer occurs, and 1.0 MPa can be used as the initial water injection condition.

[0079] Step 3: Post-experiment processing and analysis.

[0080] Step 301, analysis of blockage.

[0081] After determining the blockage in step two, the oil pressure is first slowly released through the oil outlet valve 21, and then the power to the temperature control heating element 24 is turned off to stop heating. After cooling, the sealing cover 2 is opened, the rubber sleeve 8 is removed, and the blocked rock sample is taken out. The spatial distribution of pore blockage and scale inside the rock sample is observed using a CT scanner. After pulverizing a portion of the rock sample, it is analyzed using an X-ray diffraction (XRD) instrument to determine the specific mineral type of the blockage.

[0082] Specifically, in this embodiment, when the initial injection pressure is 0.5 MPa, the permeability is 2.5 × 10⁻⁶. -6The sample showed a porosity of m / s, indicating blockage. Heating was stopped, and the core was removed. CT scans were used to determine the extent of the blockage, as shown in Figures 2(a) and 2(b). In Figure 2(a), the green shaded areas represent blockages, indicating blockages in the middle and lower parts of the sample. Furthermore, Figure 2(b) shows a per-bedding porosity variation, revealing a significant decrease in porosity at cross-sections of 230 and 1500, further confirming the blockage.

[0083] Mineral composition analysis was performed on the blocked rock sample, and the results are shown in Table 3.

[0084] Table 3 Mineral composition analysis results

[0085] Table 3 shows that the mineral composition analysis results indicate the following: quartz 36%, plagioclase 24.3%, potassium feldspar 5.1%, calcite 1%, siderite 1.8%, clay minerals 28.6%, all of which are present in the rock sample itself; CaSO4 3.6%, which is a blockage substance and represents SO4 in highly mineralized mine water. 2- With Ca in minerals 2+ Precipitated substances formed by combination.

[0086] Step 302, optimize the injection parameters.

[0087] By comprehensively comparing the permeability variation curves and final blockage conditions obtained from experimental groups with different initial reinjection water pressures (0.5MPa, 1.0MPa, 1.5MPa), the influence characteristics of reinjection pressure on the permeability decay rate under simulated high-temperature and high-pressure coupling effects in the formation were analyzed. Based on the influence characteristics, the optimal mine water reinjection pressure parameters that can maximally delay or mitigate blockage were determined.

[0088] In this embodiment, based on experimental data, the permeability changes under high temperature and high pressure coupling as the initial pressure increases, and the optimal initial pressure value is determined to reduce the occurrence of blockage.

[0089] In this embodiment, based on the changes in rock sample permeability under different initial injection pressures, it can be seen that when the initial injection pressure is 1.0 MPa, although the permeability decreases over time, it remains greater than the permeability at the point of blockage, and blockage no longer occurs. Therefore, 1.0 MPa is used as the initial injection parameter.

Claims

1. A simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions, characterized in that, The system includes a suffocation chamber (1), with a sealing cover (2) on the top of the suffocation chamber (1); a hollow, sealed water injection head (3) is detachably installed inside the suffocation chamber (1), and the bottom surface of the water injection head (3) is configured as a water injection permeable plate (4); a base (5) is fixedly installed at the bottom inside the suffocation chamber (1), and a hollow, sealed water outlet head (6) is installed on the base (5), with the top surface of the water outlet head (6) configured as a water outlet permeable plate (7); the water injection head (3) and the water outlet head (6) are coaxially arranged, and the upper end of the detachable sealing sleeve (8) is fitted on the water injection head (3), and the lower end of the detachable sealing sleeve (8) is fitted on the water outlet head (6), forming a water-rock reaction chamber (9) between the water injection permeable plate (4), the water outlet permeable plate (7), and the sleeve (8). The confining chamber (1) has an inlet pipe through hole (10) that runs through both the inside and outside. An inlet pipe (11) is sealed inside the inlet pipe through hole (10). One end of the inlet pipe (11) is connected to an external injection water pump (12). An inlet valve (13) is installed on the inlet pipe (11) located on the outside. The other end of the inlet pipe (11) is connected to the hollow cavity inside the injection head (3). The confining chamber (1) has an outlet pipe through hole (14) that runs through both the inside and outside. An outlet pipe (15) is sealed inside the outlet pipe through hole (14). One end of the outlet pipe (15) passes through the base (5) and is connected to the hollow cavity inside the outlet head (6). The confining chamber (1) has an oil inlet (16) that runs through the inside and outside of the side wall. The oil inlet (16) is connected to the pressure control oil pump (18) through an external oil inlet pipe (17). The confining chamber (1) has an oil outlet (19) that runs through the inside and outside of the side wall. The oil outlet (19) is connected to an external oil outlet pipe (20). An oil outlet valve (21) is installed on the oil outlet pipe (20). The confining chamber (1) has a through hole (22) on its side wall, through which a signal line and a power line pass. A temperature sensor (23) and a temperature control heating element (24) are installed on the inner wall of the confining chamber (1). The temperature sensor (23) is connected to the input terminal of an external temperature controller (25) via a signal line. The temperature control heating element (24) is connected to the output terminal of an external temperature controller (25) via a signal line. The temperature control heating element (24) is connected to an external power source (26) via a power line.

2. The simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 1, characterized in that, The water injection head (3) and the rubber sleeve (8) are connected by a sealing clamp (27) to form a detachable sealing assembly; the water outlet head (6) and the rubber sleeve (8) are connected by a sealing clamp (27) to form a detachable sealing assembly.

3. The simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 1, characterized in that, The water inlet pipe (11) is equipped with a water inlet pressure gauge (28); the oil inlet pipe (17) is equipped with an oil inlet pressure gauge (29); and the water outlet pipe (15) is equipped with an outlet pressure sensor (30) and an outlet flow sensor (31).

4. The simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 3, characterized in that, The outlet pressure sensor (30) is connected to the outlet pressure monitor (32), and the outlet flow sensor (31) is connected to the outlet flow monitor (33).

5. The simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 1, characterized in that, A sealing ring (34) is provided between the sealing cover (2) and the confining chamber (1), and the sealing is installed by sealing bolts (35).

6. A simulation test method for deep reinjection of high-salinity mine water under high temperature and high pressure conditions, characterized in that, This method employs the simulation test device for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in any one of claims 3 to 5; The method includes the following steps: Step 1: Preparation for Mine Water Reinjection Test Step 101, Core collection and pretreatment of the target layer for mine water reinjection: During the drilling phase, core samples of the target layer for mine water reinjection are collected and processed into rock samples. Subsequently, the processed rock samples are placed into the water-rock reaction chamber (9) inside the rubber sleeve (8) and sealed with a sealing cap (2). Step 102, Initialization of high temperature and high pressure environment: Step 10201, Initialize confining pressure: Start the pressure control oil pump (18) in the high temperature and high pressure control system, add hydraulic oil into the confining chamber (1) through the oil inlet pipe (17), and apply pressure to the rock sample in the water-rock reaction chamber (9) through the hydraulic oil outside the rubber sleeve (8); adjust the confining pressure according to the display value on the oil inlet pressure gauge (29) and control the initial value of the confining pressure to 48 MPa; Step 10202, Initialize temperature: The initial temperature of the temperature-controlled heating element (24) is adjusted to 65°C using the temperature controller (25); Step 2, Reinjection Simulation and Blockage Determination: Step 201, Simulation of mine water reinjection under high temperature and high pressure coupling conditions: Under the conditions of initial confining pressure and initial temperature in step one, open the water inlet valve (15) on the water inlet pipe (11) and inject mine water from the water injection head (3) into the water-rock reaction chamber (9) through the injection pump (12); control the initial reinjection water pressure to 0.5MPa, 1.0MPa and 1.5MPa respectively, and conduct multiple sets of comparative reinjection experiments; Step 202, Real-time monitoring and penetration rate calculation: In the mine water reinjection simulation in step 201, the pressure difference between the mine water reinjection inlet and outlet is obtained based on the inlet pressure monitored by the inlet pressure gauge (28) and the outlet pressure monitored by the outlet pressure sensor (30). The reinjection flow rate is monitored in real time by the outflow flow sensor (31). Then, using Darcy's law formula, every... Permeability of rock samples is calculated periodically. When the penetration rate If the drop rate is greater than 50%, it is determined that there is a serious blockage inside the rock sample.

7. The simulation test method for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 6, characterized in that, In step 101, the rock sample is a cylindrical rock sample with a diameter of 50 mm and a height of 100 mm.

8. The simulation test method for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 6, characterized in that, In step 10201, considering pressure transmission loss, the relationship between the displayed value on the oil inlet pressure gauge (29) and the confining pressure is: σ = η P; where σ represents the confining pressure value borne by the rock sample; η represents the pressure transmission coefficient; and P represents the displayed value on the oil inlet pressure gauge.

9. The simulation test method for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 6, characterized in that, In step 202, the Darcy's law formula is: ; In the formula: Indicates the sample Average permeability over a period of time, expressed in m / s; express The reinjection flow rate through the rock sample within a given time, expressed in m³. 3 ; The viscosity coefficient of mine water is expressed in Pa·m. -1 ; This indicates the length of the seepage path of mine water in a rock sample, i.e., the height of the rock sample, in meters (m). This represents the cross-sectional area of ​​the rock sample, in m². 2 ; This indicates the pressure difference between the inlet and outlet water in mine water reinjection, expressed in Pa.

10. The simulation test method for deep reinjection of high-salinity mine water under high temperature and high pressure conditions as described in claim 6, characterized in that, It also includes step three; Step 3, Post-experiment processing and analysis: Step 301, Blockage Analysis: After the blockage determination in step two, the oil pressure is first released through the oil outlet valve (21), and then the power supply of the temperature control heating element (24) is turned off to stop heating. After cooling, the sealing cover (2) is opened, the rubber sleeve (8) is removed, and the blocked rock sample is taken out. The pore blockage and scale spatial distribution inside the rock sample are observed using a CT scanner. After some rock samples are crushed, they are analyzed by X-ray diffraction to determine the specific mineral type of the blockage. Step 302, Injection Parameter Optimization: By comprehensively comparing the permeability change curves and final blockage conditions obtained from experimental groups with different initial reinjection water pressures, the influence characteristics of reinjection pressure on the permeability decay rate under simulated high temperature and high pressure coupling effects are analyzed. Based on the influence characteristics, the optimal mine water reinjection pressure parameters that can delay or mitigate blockage to the greatest extent are determined.

Images