Similar material simulation test device and method for co2 geological storage in deep mining space

Abstract

This invention discloses a similar material simulation test device and method for CO2 geological sequestration in deep mining spaces, belonging to the field of underground engineering simulation test technology. It mainly includes a base, outer cylinder, inner liner, rotating connecting rod, pressurizing device, mining simulation component, and horizontal gas sealing device. The inner liner can rotate with the rotating connecting rod, and an electromagnetic self-locking structure ensures reliable angle positioning. The entire device is made of CO2-resistant corrosion-resistant material, and multiple sealing structures ensure airtightness. Composite geostress can be applied through the pressurizing device and nitrogen-type horizontal gas sealing structure. The mining simulation component can simulate coal seam mining at different depths, injecting a mixed gas containing a fluorescent tracer, and using a transparent structure to achieve visualized monitoring of gas migration. This invention can simulate the entire process of mining, abandonment, and CO2 sequestration, with high simulation accuracy and convenient operation, providing reliable experimental support for research related to CO2 geological sequestration in deep mining spaces and abandoned mines.

Description

Technical Field

[0001] This invention relates to the technical fields of geotechnical model testing devices, underground engineering, and gas storage testing, and particularly to a similar material simulation testing device and method for CO2 geological storage in deep mining spaces. Background Technology

[0002] Carbon dioxide geological sequestration is an important research direction in the field of underground space resource utilization. Deep mining spaces and abandoned mining tunnels can serve as high-quality sequestration carriers, while indoor physical simulation experiments are the core means to explore sequestration mechanisms, analyze rock mass response and gas migration patterns, and provide data support for the research and implementation of related technologies.

[0003] Current experimental studies on carbon dioxide geological storage mostly rely on small-scale core samples to evaluate the storage performance of the rock mass through mechanical and seepage tests. However, the size of such test models differs significantly from the actual underground mining space, resulting in obvious deviations in the test results. Furthermore, core tests cannot reproduce the dynamic evolution of stress and fluid flow fields caused by mining disturbances, making it difficult to recreate complex on-site conditions and thus limiting the practical reference value of the test results.

[0004] Large-scale similar material simulation devices are well-established in the fields of geotechnical and underground engineering, and are often used in research on rock strata failure patterns, surrounding rock stability, and engineering disaster prevention. However, existing similar devices are designed around the needs of traditional underground engineering, and there is currently a lack of integrated simulation devices specifically adapted to the geological storage of carbon dioxide in mining spaces, which makes it difficult to meet the specific requirements of gas storage-related experiments.

[0005] In summary, existing experimental equipment and technical solutions are no longer sufficient to meet the research needs of detailed simulation of the entire process of carbon dioxide geological storage in deep mining spaces. There is an urgent need to develop an indoor similar material simulation test device to realize the simulation of the entire process of carbon dioxide geological storage under different dip angle strata and composite geostress conditions, effectively improve the accuracy of the test and the reliability of operation, and provide complete test conditions for related technical research. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a similar material simulation test device and method for CO2 geological sequestration in deep mining spaces.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a similar material simulation test device for CO2 geological sealing in deep mining space, including a base, an outer cylinder, an inner liner, a rotating connecting rod and a horizontal sealing device; The outer cylinder has openings at both ends and is fixed to the base; one end of the inner liner is inserted into the outer cylinder and seals the opening of the outer cylinder in contact with it; the rotating connecting rod is connected to the end of the inner liner away from the outer cylinder and is used to drive the inner liner to rotate 0-90° relative to the outer cylinder; the rotating connecting rod is equipped with a self-locking device to lock the relative angle position of the inner liner and the outer cylinder. The inner liner includes a rear baffle, an upper pressurizing device, and a lower pressurizing device. The upper and lower pressurizing devices have the same structure and are both fixed to the end face of the rear baffle near the outer cylinder. The upper and lower pressurizing devices are arranged opposite to each other and are both located inside the outer cylinder, and are used to apply vertical stress to similar materials inside. The outer cylinder and the inner liner form a filling space for filling with similar materials; the rear baffle has an air inlet and an air outlet communicating with the filling space, for injecting or discharging mixed gas into the filling space and adjusting the CO2 pressure. The rear baffle is equipped with several mining simulation components, each including a pull-out metal strip, a control rod, and a movable sealing piston. A sliding groove communicating with the filling space is formed through the rear baffle. The pull-out metal strip, movable sealing piston, and control rod of the mining simulation components are all inserted into the sliding groove. One end of the control rod is detachably connected to the pull-out metal strip, and the other end extends out of the inner liner. The control rod can drive the pull-out metal strip to slide horizontally, inserting or withdrawing from the filling space. The movable sealing piston is detachably connected to the control rod and moves synchronously with the control rod. The movable sealing piston is used to prevent CO2 gas from escaping from the position where the pull-out metal strip engages. The horizontal sealing device is detachably installed at the end of the outer cylinder away from the inner liner. The horizontal sealing device is used to apply horizontal ground stress to the inner liner, block CO2 gas, and realize the visualization and observation of the mining space.

[0008] Furthermore, the filling space is also provided with a left filling alloy and a right filling alloy. The left filling alloy and the right filling alloy extend into the filling space by a predetermined distance to support similar materials in the filling space. The left filling alloy and the right filling alloy are fixedly connected to the inside of the outer cylinder and are located outside the two pull-out metal strips located at the outermost edge, respectively.

[0009] Furthermore, the pull-out metal strip is a replaceable structure; the ratio of the minimum mining height to the maximum mining height of the pull-out metal strip is not less than 1 / 2.

[0010] Furthermore, the rear baffle has several circular holes communicating with the filling space, and each of the circular holes is equipped with a gas sealing pipeline assembly; the gas sealing pipeline assembly includes a gas sealing piston, a gas sealing hose, and a gas sealing valve. The gas sealing piston is embedded in the end of the circular hole near the filling space, the gas sealing hose is a flexible tube resistant to CO2 corrosion, one end of the gas sealing hose is embedded in the end of the circular hole away from the filling space, and the other end of the gas sealing hose is connected to the gas sealing valve.

[0011] Furthermore, a through hole is provided at the center of the sealing piston, which is used for the sensor circuit to pass through, while sealing the round hole to prevent CO2 from escaping; the upper end of the sealing valve is provided with an outlet for the sensor measuring line to pass through.

[0012] Furthermore, filters are installed at the connection points of the air inlet, air outlet, and rear baffle to prevent similar materials in the filling space from entering the external pipeline; the air inlet is used to inject mixed gas into the inner liner and regulate the CO2 gas pressure in the cavity, and the air outlet is used to extract CO2 gas from the inner liner; the mixed gas consists of 98% CO2 by volume and 2% hexafluoroethane fluorescent tracer by volume.

[0013] Furthermore, the horizontal sealing device includes a transparent acrylic baffle, a transparent sealing film, and sealing bolts; The transparent acrylic baffle is fixed to the end face of the outer cylinder by sealing bolts. The transparent sealing film is located on the side of the transparent acrylic baffle near the outer cylinder, and its outer periphery is fixedly connected to the transparent acrylic baffle. The transparent sealing film is filled with nitrogen. The transparent acrylic baffle has an injection hole for communicating with the inside of the transparent sealing film. The injection hole is connected to a nitrogen cylinder and is used to fill or discharge nitrogen into the transparent sealing film to adjust the gas pressure inside the transparent sealing film.

[0014] Furthermore, the radial dimension of the transparent acrylic baffle is larger than the radial dimension of the outer cylinder, and the radial dimension of the transparent sealing film is larger than the radial dimension of the inner liner; the transparent sealing film is made of a flexible sealing material with pressure resistance.

[0015] This invention also provides a similar material simulation test method for CO2 geological sequestration in deep mining spaces. Based on the aforementioned simulation test device, the test method includes the following steps: S1. Investigate the geological parameters of the test area, prepare similar materials that match the geological characteristics, and select pull-out metal strips of appropriate specifications according to the preset coal seam mining height, and pre-install the pull-out metal strips at the bottom of the filling space. S2. Fill the filling space with similar materials according to the sedimentary pattern of the strata, and lay the sensor measuring lines through the round holes of the rear baffle into the similar materials. Check the airtightness of all gas sealing pipeline components and close the gas sealing valve. S3. Control the rotating linkage to rotate the inner liner of the device to the target stratum dip angle, and activate the self-locking device of the rotating linkage to lock the position of the inner liner of the device. S4. Install the horizontal sealing device to the front end of the outer cylinder, and fill the transparent sealing film with nitrogen through the air injection hole to complete the application of horizontal stress. S5. Activate the upper and lower pressurization devices and apply vertical ground stress to similar materials in combination with the stratum dip angle parameters; S6. The control lever is used to horizontally pull the metal strip to simulate the coal seam mining process, and stress and displacement test data are collected simultaneously through sensors. S7. After the simulation is completed, inject a CO2 mixture containing hexafluoroethane fluorescent tracer into the inner liner of the device through the air inlet, observe the gas transport status and collect gas parameter data. S8. After the sealing simulation is completed, CO2 gas is extracted through the extraction port, and then nitrogen gas inside the transparent sealing film is discharged to complete the two-stage depressurization. S9. Close the upper and lower pressurization devices, remove the horizontal sealing device, empty the similar material in the filling space and reset the pull-out metal strip, release the self-locking device of the rotating linkage, remove all sensor circuits, organize and process the test data, and complete the test.

[0016] The beneficial effects of this invention are: The inner liner of this invention can be angle-adjusted relative to the outer cylinder and is equipped with an electromagnetic self-locking device, enabling it to adapt to simulated working conditions of strata with different dip angles, and ensuring stable and reliable angle positioning. It integrates a vertical pressurization mechanism and a nitrogen-driven horizontal sealing structure, allowing for the simultaneous application of vertical and horizontal composite geostress to replicate the real stress environment of deep strata, effectively improving the realism of the experimental simulation. The replaceable pull-out metal strip, combined with the matching mining simulation components, can simulate the coal seam mining process at different mining heights. Combined with the air inlet and outlet, it can completely simulate the entire lifecycle of mining, waste disposal, and CO2 gas injection and storage. The experiment is highly continuous; the entire equipment is made of CO2-resistant materials, combined with a multi-seal structure, a movable gas-sealing piston, and gas-sealing pipeline components, ensuring excellent airtightness and effectively preventing gas leakage. It also facilitates sensor deployment and data monitoring. By incorporating fluorescent tracers into CO2, combined with a transparent gas-sealing film and acrylic baffles, visual observation of gas migration can be achieved, significantly reducing monitoring costs. The entire device has a reasonable structure, is easy to operate, and provides accurate experimental data, which can provide strong support for experimental research and engineering applications in the field of CO2 geological storage in deep mining spaces and abandoned mines. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Figure 2 This is a perspective view used in this invention to illustrate the internal structure of the outer cylinder.

[0019] Figure 3 This is a structural attempt used to embody the inner liner in this invention.

[0020] Figure 4 This is a front view of the structure used to fill the space in this invention.

[0021] Figure 5 This is a schematic diagram illustrating the structure of the mining simulation component in this invention.

[0022] Figure 6 This is a perspective view illustrating the structure of the horizontal sealing device in this invention.

[0023] In the diagram: 1. Base; 2. Outer cylinder; 21. Filling space; 22. Left filling alloy; 23. Right filling alloy; 3. Inner liner; 31. Rear baffle; 311. Air inlet; 312. Air outlet; 313. Circular hole; 32. Upper pressurization device; 33. Lower pressurization device; 4. Rotating connecting rod; 5. Horizontal sealing device; 51. Transparent acrylic baffle; 52. Transparent sealing film; 53. Air injection hole; 6. Simulation assembly; 61. Pull-out metal strip; 62. Control rod; 63. Moving sealing piston; 7. Sealing pipeline assembly; 71. Sealing piston; 72. Sealing hose; 73. Sealing valve. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] This invention discloses a similar material simulation test device for CO2 geological sequestration in deep mining spaces.

[0026] Reference Figure 1A similar material simulation test device for CO2 geological sequestration in deep mining spaces mainly consists of a base 1, an outer cylinder 2, an inner liner 3, a rotating connecting rod 4, and a horizontal sealing device 5. The outer cylinder 2 is made of a CO2-resistant alloy material and is a cylindrical structure open at both ends. Its bottom is fixedly mounted on the base 1. Angle markings are engraved on the circumference of the outer cylinder 2 to visually indicate the rotation angle of the inner liner 3, providing a precise reference for tilt adjustment. One end of the inner liner 3 is inserted into the outer cylinder 2, and the contact point between the two is flexibly sealed to prevent leakage of the internal gaseous medium, ensuring the overall airtightness of the device without affecting the rotation of the inner liner 3. The rotating connecting rod 4 is connected to the end of the inner liner 3 furthest from the outer cylinder 2. The operator can drive the inner liner 3 to rotate relative to the outer cylinder 2 within a range of 0-90° using the rotating connecting rod 4, thus adapting to simulated working conditions of coal seams with different dip angles and inclined strata. The rotating connecting rod 4 integrates a self-locking device; in this embodiment, an electromagnetic self-locking device is used, which is a known technology, therefore its specific structure and working principle will not be described in detail here. When the inner liner 3 rotates to the preset angle required for the test, the self-locking device locks the relative position of the inner liner 3 and the outer cylinder 2, preventing angular deviation due to equipment vibration, stratum stress reaction, or other factors during the test.

[0027] Reference Figures 2 to 4 The inner liner 3 includes a rear baffle 31, an upper pressurizing device 32, and a lower pressurizing device 33. The upper pressurizing device 32 and the lower pressurizing device 33 have identical structures and are both fixedly installed on the end face of the rear baffle 31 near the outer cylinder 2. The two pressurizing devices are arranged opposite each other and are located inside the outer cylinder 2. Deep underground rock masses are subjected to vertical ground stress for a long time. The two pressurizing devices work together to uniformly and stably apply vertical ground stress to the similar materials inside the device, restoring the real vertical stress environment of deep strata and ensuring that the simulated working conditions are consistent with the actual geological conditions on site. The inner liner 3 and the outer cylinder 2 together form a filling space 21. This space is the core area for filling with similar materials such as gypsum, cement, and sand. By filling similar materials in layers, the original underground strata and coal seam structure can be simulated.

[0028] The rear baffle 31 is made entirely of CO2 corrosion-resistant materials, such as 304 stainless steel, 316L stainless steel, and nickel-based alloys; it can be exposed to CO2 mixed gas for a long time without rusting or aging, and continuously maintains structural strength and sealing performance. The rear baffle 31 has several sets of circular holes 313 that connect to the filling space 21. Each circular hole 313 is equipped with a sealing gas routing pipeline assembly 7, which mainly consists of a sealing gas piston 71, a sealing gas hose 72, and a sealing gas valve 73.

[0029] The sealing piston 71 is embedded in the end of the circular hole 313 near the filling space 21. A through-hole is located in the center of the sealing piston 71. This through-hole allows the wiring of stress and displacement sensors to pass into the filling space 21 for comprehensive formation monitoring. Simultaneously, the sealing piston 71 seals the main area of ​​the circular hole 313, preventing CO2 gas from escaping from the hole. The sealing hose 72 is made of a flexible material resistant to CO2 corrosion, such as polytetrafluoroethylene (PTFE). One end is embedded in the end of the circular hole 313 furthest from the filling space 21, and the other end is sealed to the sealing valve 73. The flexible material can accommodate minor deformations of the equipment during testing, preventing pipe breakage and seal failure. An outlet is provided at the top of the sealing valve 73 to allow sensor wiring to pass through.

[0030] The rear baffle 31 is also equipped with an air inlet 311 and an air outlet 312, both of which are connected to the filling space 21. Filters are installed at the connection points between the two ports and the rear baffle 31. The similar materials in the filling space 21 are mostly granular or powdery mixtures. During gas flow, these materials can easily carry fine particles into external pipelines and gas cylinders. The filters act as physical barriers, protecting external gas supply and extraction equipment from blockage and damage. The air inlet 311 is mainly used to inject mixed gas into the inner liner 3 and simultaneously adjust the CO2 pressure within the cavity in real time. The air outlet 312 is used to extract residual CO2 gas from the inner liner 3 after the experiment. The mixed gas used in the experiment is composed of 98% CO2 and 2% hexafluoroethane fluorescent tracer by volume. Without altering the physicochemical properties of CO2 or interfering with the study of the sealing mechanism, the fluorescent tracer enables visual observation of the gas transport path and diffusion range, reducing the cost of using high-precision monitoring equipment.

[0031] Reference Figure 5 The rear baffle 31 is also equipped with several sets of mining simulation components 6. Each mining simulation component 6 includes a pull-out metal strip 61, a control rod 62, and a movable sealing piston 63. A sliding long groove communicating with the filling space 21 is opened through the outer cylinder 2. The pull-out metal strip 61, the movable sealing piston 63, and the control rod 62 in the mining simulation component 6 are all inserted into the sliding long groove. The pull-out metal strip 61 is made of an alloy material resistant to CO2 corrosion. It has a replaceable structure, and the ratio of the minimum mining height to the maximum mining height of the pull-out metal strip 61 is not less than 1 / 2. The replaceable design can adapt to the simulation requirements of different coal seam mining heights, and the reasonable mining height ratio ensures that the equipment can cover conventional underground mining conditions.

[0032] One end of the control rod 62 is detachably connected to the pull-out metal strip 61, while the other end extends outside the inner liner 3. The test personnel can push or pull the control rod 62 to drive the pull-out metal strip 61 to slide horizontally, thus inserting or withdrawing the metal strip 61 into the filling space 21, dynamically simulating the entire process of underground coal seam mining and overburden disturbance. The movable sealing piston 63 is detachably connected to the control rod 62 and can move synchronously with it. Since the pull-out metal strip 61 creates a gap during horizontal sliding, CO2 gas can easily leak out through this gap. The movable sealing piston 63 can dynamically seal the sliding fit position, maintaining the airtightness of the cavity throughout the process and preventing gas leakage from distorting the test data.

[0033] The filling space 21 is also fixedly equipped with a left filling alloy 22 and a right filling alloy 23. Both types of filling alloys are fixedly connected to the inner wall of the outer cylinder 2 and are respectively arranged on the outside of the two pull-out metal strips 61 at the outermost edge, while extending into the filling space 21 by a predetermined distance. Since the similar material in the filling space 21 has a large volume after being filled, the left filling alloy 22 and the right filling alloy 23 can provide lateral support for the similar material, avoiding lateral collapse and local deformation of the similar material during stress loading and mining simulation, and effectively improving the structural integrity and working condition stability of the simulated strata.

[0034] Reference Figure 6 The horizontal sealing device 5 is a detachable structure, installed as a whole at the end of the outer cylinder 2 away from the inner liner 3. Its main functions are to apply horizontal ground stress to the inner liner 3, block CO2 gas, and enable visual observation of the mining space. The horizontal sealing device 5 mainly consists of a transparent acrylic baffle 51, a transparent sealing film 52, and sealing bolts. The radial dimension of the transparent acrylic baffle 51 is larger than that of the outer cylinder 2. A total of four sealing bolts are evenly distributed along the circumference of the transparent acrylic baffle 51, with the outer diameter of the bottom sealing bolt being larger than the other three. Because the transparent acrylic baffle 51 has its own weight, increasing the size of the bottom bolts can improve the bottom bearing capacity, offset the local load caused by its own weight, prevent stress concentration from causing bolt deformation and damage, and ensure the long-term stability of the connection structure.

[0035] A transparent sealing film 52 is positioned on the side of the transparent acrylic baffle 51 near the outer cylinder 2. Its outer periphery is sealed and fixed to the transparent acrylic baffle 51. The radial dimension of the transparent sealing film 52 is larger than that of the inner liner 3, and it is made of a flexible sealing material with pressure resistance, such as transparent polyurethane film, vapor phase transparent silicone rubber film, or pressure-resistant PVC transparent film. The transparent sealing film 52 is filled with nitrogen gas. An injection hole 53 is provided on the transparent acrylic baffle 51, which is connected to the interior of the transparent sealing film 52 and externally connected to a nitrogen gas cylinder.

[0036] During the experiment, nitrogen can be injected or discharged into the transparent sealing membrane 52 through the injection hole 53 to adjust the internal air pressure of the membrane. The nitrogen pressure is used to apply uniform horizontal stress to the simulated strata inside the outer cylinder 2, accurately restoring the complex stress field environment of the deep rock mass. At the same time, the transparent sealing membrane 52, after being inflated, can fit tightly against the front end of the cavity, further enhancing the overall sealing effect and preventing CO2 gas from escaping to the front end. The transparent acrylic baffle and sealing membrane allow for direct observation of the morphology of the excavated cavity and the gas distribution inside the filling space 21, making the experimental process visible.

[0037] This invention also discloses a similar material simulation test method for CO2 geological sequestration in deep mining spaces.

[0038] The similar material simulation test method for CO2 geological sequestration in deep mining spaces is based on the above-mentioned simulation test device and specifically includes the following steps: S1. First, conduct a survey of the geological parameters of the test target area, and prepare similar materials that match the mechanical and physical properties of the in-situ strata according to similarity theory to ensure that the simulated medium is consistent with the actual strata conditions. Then, in combination with the coal seam mining height parameters preset for the test, select the corresponding specifications of pull-out metal strips 61, and pre-install the pull-out metal strips 61 at the bottom of the filling space 21 to complete the preparation of the medium and core simulation components in the early stage of the test.

[0039] S2. Following the natural sedimentary patterns of underground strata, similar materials are filled into the filling space 21 in layers to restore the original stratification structure of the strata. Subsequently, various sensor lines are sequentially passed through the round holes 313 of the rear baffle 31 and laid to the preset monitoring points inside the similar materials via the gas sealing pipeline assembly 7. After the sensors are laid out, the sealing status of all gas sealing pipeline assemblies 7 is thoroughly checked. After confirming that there is no risk of leakage, the gas sealing valve 73 is closed.

[0040] S3. Control the rotating linkage 4 to drive the inner liner 3 to rotate relative to the outer cylinder 2. Refer to the angle scale on the circumference of the outer cylinder 2 to adjust the inner liner 3 to the stratum dip angle set in the test plan. After the angle is adjusted to the correct position, activate the self-locking device inside the rotating linkage 4 to lock the relative position of the inner liner 3 and the outer cylinder 2 to prevent angle deviation in subsequent test steps.

[0041] S4. Assemble the horizontal sealing device 5 as a whole to the front end of the outer cylinder 2 and tighten the sealing bolts to complete the fixation; fill the transparent sealing film 52 with nitrogen through the nitrogen cylinder connected to the injection port 53, and adjust the nitrogen pressure inside the transparent sealing film 52 according to the preset horizontal stress value of the test. The application of simulated horizontal stress of the formation is completed by relying on the pressure. The flexible film can ensure that the horizontal stress is uniformly applied to the end face of the formation.

[0042] S5. Activate the upper pressurization device 32 and the lower pressurization device 33, and calculate the vertical stress value in combination with the current tilt angle of the inner liner 3. Apply vertical stress to the similar material in the filling space 21 in a step-by-step loading manner. The step-by-step loading mode can avoid sudden damage to the similar material caused by instantaneous stress change, and the tilt angle conversion further improves the simulation accuracy of deep complex stress environment.

[0043] S6. Smoothly operate the control lever 62 to drive the pull metal strip 61 to slide gradually in the horizontal direction, simulating the actual process of gradual mining of coal seams on site; throughout the entire process of the pull metal strip 61 moving, keep the sensor continuously powered on and continuously collect test data such as stratum stress and surrounding rock displacement, and fully record the dynamic evolution law of stratum stress field and deformation field under mining disturbance.

[0044] S7. After the action of pulling out the metal strip 61 is completed and the coal seam mining simulation is finished, the air inlet 311 is opened and a mixed gas consisting of 98% CO2 and 2% hexafluoroethane fluorescent tracer is introduced into the inner liner 3. The transport status of the mixed gas in the rock mass fissures and mining cavities is continuously observed, and the CO2 transport law is intuitively observed with the help of the fluorescent tracer.

[0045] S8. After the CO2 geological storage simulation test is completed, first open the vent 312 to gradually extract the CO2 gas remaining inside the inner liner 3, monitor the gas concentration in the chamber in real time, and after the CO2 concentration inside the inner liner 3 drops to a safe range, then discharge the nitrogen gas inside the transparent sealing film 52 through the injection port 53 to complete the two-stage depressurization of the entire equipment, avoid sudden changes in gas pressure from impacting the equipment structure and similar materials, and ensure on-site operation safety.

[0046] S9. Sequentially shut down the upper pressurization device 32 and the lower pressurization device 33, release the sealing bolts and completely dismantle the horizontal sealing device 5; empty the similar material inside the filling space 21, reset the pull-out metal strip 61 to its initial position, and release the self-locking device of the rotating connecting rod 4; then extract all sensor lines from the sealing pipeline assembly 7, organize, statistically analyze the test data collected throughout the process, and at this point, the entire simulation test of similar materials for CO2 geological sealing in deep mining space is completed.

[0047] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A similar material simulation test device for CO2 geological sequestration in deep mining spaces, characterized in that: It includes a base (1), an outer cylinder (2), an inner liner (3), a rotating connecting rod (4), and a horizontal sealing device (5); The outer cylinder (2) has openings at both ends and is fixed to the base (1); one end of the inner liner (3) is inserted into the outer cylinder (2) and seals the opening of the outer cylinder (2) in contact with it; the rotating connecting rod (4) is connected to the end of the inner liner (3) away from the outer cylinder (2) and is used to drive the inner liner (3) to rotate 0-90° relative to the outer cylinder (2); the rotating connecting rod (4) is equipped with a self-locking device to lock the relative angular position of the inner liner (3) and the outer cylinder (2); The inner liner (3) includes a rear baffle (31), an upper pressurizing device (32), and a lower pressurizing device (33). The upper pressurizing device (32) and the lower pressurizing device (33) have the same structure and are both fixed to the end face of the rear baffle (31) near the outer cylinder (2). The upper pressurizing device (32) and the lower pressurizing device (33) are arranged opposite to each other and are both located inside the outer cylinder (2) to apply vertical stress to similar materials inside. The outer cylinder (2) and the inner liner (3) form a filling space (21) for filling similar materials; the rear baffle (31) is provided with an air inlet (311) and an air outlet (312) communicating with the filling space (21) for injecting or discharging mixed gas into the filling space (21) and adjusting the CO2 pressure. The rear baffle (31) is provided with several mining simulation components (6), each of which includes a pull-out metal strip (61), a control rod (62), and a movable sealing piston (63). A sliding long groove communicating with the filling space (21) is provided through the rear baffle (31). The pull-out metal strip (61), the movable sealing piston (63), and the control rod (62) of the several mining simulation components (6) are all inserted into the sliding long groove. One end of the control rod (62) is detachably connected to the pull-out metal strip (61), and the other end extends out of the inner liner (3). The control rod (62) can drive the pull-out metal strip (61) to slide horizontally and insert into or exit the filling space (21). The movable sealing piston (63) is detachably connected to the control rod (62) and moves synchronously with the control rod (62). The movable sealing piston (63) is used to prevent CO2 gas from escaping from the position where the pull-out metal strip (61) is engaged. The horizontal sealing device (5) is detachably installed at the end of the outer cylinder (2) away from the inner liner (3). The horizontal sealing device (5) is used to apply horizontal ground stress to the inner liner (3), block CO2 gas, and realize the visualization observation of the mining space.

2. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 1, characterized in that: The filling space (21) is also provided with a left filling alloy (22) and a right filling alloy (23). The left filling alloy (22) and the right filling alloy (23) extend into the filling space (21) by a predetermined distance to support similar materials in the filling space (21). The left filling alloy (22) and the right filling alloy (23) are fixedly connected to the inside of the outer cylinder (2) and are located outside the two pull-out metal strips (61) located at the outermost edge, respectively.

3. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 2, characterized in that: The pull-out metal strip (61) is a replaceable structure; the ratio of the minimum mining height to the maximum mining height of the pull-out metal strip (61) is not less than 1 / 2.

4. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 3, characterized in that: The rear baffle (31) has several circular holes (313) communicating with the filling space (21), and each of the circular holes (313) is equipped with a sealing gas routing pipeline assembly (7); the sealing gas routing pipeline assembly (7) includes a sealing gas piston (71), a sealing gas hose (72) and a sealing gas valve (73). The sealing gas piston (71) is embedded in the end of the circular hole (313) near the filling space (21). The sealing gas hose (72) is a flexible pipe resistant to CO2 corrosion. One end of the sealing gas hose (72) is embedded in the end of the circular hole (313) away from the filling space (21), and the other end of the sealing gas hose (72) is connected to the sealing gas valve (73).

5. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 4, characterized in that: The sealing piston (71) has a through hole at its center, which is used for the sensor line to pass through, and at the same time, the round hole (313) is sealed to prevent CO2 from escaping; the sealing valve (73) has a wire outlet at its upper end, which is used for the sensor measuring line to pass through.

6. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 5, characterized in that: The air inlet (311), air outlet (312), and rear baffle (31) are all equipped with filters to prevent similar materials in the filling space (21) from entering the external pipeline; the air inlet (311) is used to inject mixed gas into the inner liner (3) and adjust the CO2 gas pressure in the cavity; the air outlet (312) is used to extract CO2 gas from the inner liner (3); the mixed gas consists of CO2 with a volume percentage of 98% and hexafluoroethane fluorescent tracer with a volume percentage of 2%.

7. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 6, characterized in that: The horizontal sealing device (5) includes a transparent acrylic baffle (51), a transparent sealing film (52), and sealing bolts; The transparent acrylic baffle (51) is fixed to the end face of the outer cylinder (2) by sealing bolts. The transparent sealing film (52) is located on the side of the transparent acrylic baffle (51) close to the outer cylinder (2), and its outer periphery is fixedly connected to the transparent acrylic baffle (51). The transparent sealing film (52) is filled with nitrogen. The transparent acrylic baffle (51) has an injection hole (53) for communicating with the inside of the transparent sealing film (52). The injection hole (53) is connected to a nitrogen cylinder. The injection hole (53) is used to fill or discharge nitrogen into the transparent sealing film (52) to adjust the gas pressure inside the transparent sealing film (52).

8. The similar material simulation test device for CO2 geological sequestration in deep mining spaces according to claim 7, characterized in that: The radial dimension of the transparent acrylic baffle (51) is greater than that of the outer cylinder (2), and the radial dimension of the transparent sealing film (52) is greater than that of the inner liner (3); the transparent sealing film (52) is made of a flexible sealing material with pressure resistance.

9. A method for simulating CO2 geological sequestration in deep mining spaces using similar materials, characterized in that: Based on the simulation test apparatus according to claim 8, the test method includes the following steps: S1. Investigate the geological parameters of the test area, prepare similar materials that match the geological characteristics, and select pull-out metal strips (61) of the corresponding specifications according to the preset coal seam mining height, and pre-install the pull-out metal strips (61) at the bottom of the filling space (21). S2. Fill similar materials into the filling space (21) according to the sedimentary pattern of the strata, and lay the sensor measuring line through the round hole (313) of the rear baffle (31) into the similar material. Check the air tightness of all sealing pipeline components (7) and close the sealing valve (73). S3. Control the rotating linkage (4) to drive the inner liner (3) of the device to rotate to the target stratum dip angle, and activate the self-locking device of the rotating linkage (4) to lock the position of the inner liner (3); S4. Install the horizontal sealing device (5) to the front end of the outer cylinder (2), and fill the transparent sealing film (52) with nitrogen through the air injection hole (53) to complete the application of horizontal stress. S5. Start the upper pressurization device (32) and the lower pressurization device (33) to apply vertical ground stress to similar materials in combination with the stratum dip angle parameters; S6. The control lever (62) is used to horizontally pull the metal strip (61) to simulate the coal seam mining process and simultaneously collect stress and displacement test data through sensors. S7. After the simulation is completed, CO2 mixed gas containing hexafluoroethane fluorescent tracer is injected into the inner liner (3) of the device through the air inlet (311) to observe the gas transport state and collect gas parameter data. S8. After the sealing simulation is completed, CO2 gas is extracted through the extraction port (312), and then nitrogen gas in the transparent sealing film (52) is discharged to complete the two-stage depressurization. S9. Close the upper pressurization device (32) and the lower pressurization device (33), remove the horizontal sealing device (5), empty the similar material in the filling space (21) and reset the pull-out metal strip (61), release the self-locking device of the rotating linkage (4), take out all sensor lines, organize and process the test data, and complete the test.

Images