Experimental device for studying the influence of multi-path leakage of carbon dioxide geological storage on soil environment

Abstract

The application discloses a kind of carbon dioxide geological storage multi-path leakage to soil environment influence experimental device, including experimental container, wellbore leakage simulation unit, fault zone leakage simulation unit and caprock leakage simulation unit are set in it and filled with soil after setting, three-in-one monitoring device and soil solution sampler are equipped in soil.Wellbore leakage simulation unit, fault zone leakage simulation unit and caprock leakage simulation unit are connected with gas supply device, and gas supply device is used for each simulation unit independently supplies carbon dioxide gas.Three-in-one monitoring device and soil solution sampler are connected with data acquisition device.Gas supply device and data acquisition device are connected with control device.The application solves the problem of single-path leakage simulation limitation and incomplete soil parameter monitoring in the prior art.

Description

Technical Field

[0001] This invention relates to an experimental apparatus for assessing the impact of multiple leakage pathways of carbon dioxide in geological sequestration on the soil environment, and belongs to the field of carbon dioxide geological sequestration. Background Technology

[0002] In the field of CO2 geological sequestration, the impact of carbon dioxide gas leakage on the soil environment is mainly assessed through experimental setups. Currently, most experimental setups simulating the impact of CO2 leakage on the soil environment employ single-pathway leakage simulation models, typically focusing on wellbore or caprock leakage, without integrating simulations of the impact of multiple leakage pathways. This single-pathway leakage simulation model has limitations: it cannot compare the differences in the impact of different leakage pathways on the soil environment under the same experimental conditions, making it difficult to reveal the characteristics and mechanisms of each leakage pathway. Furthermore, data from single-pathway leakage is insufficient to support environmental risk prediction under multi-pathway leakage scenarios, leading to misjudgments of the degree of soil environmental impact. Therefore, the single-pathway leakage simulation model limits the systematic assessment of CO2 sequestration leakage risks. In addition, most existing experimental setups can only monitor parameters such as pH, lacking simultaneous monitoring of key parameters such as conductivity, CO2 concentration, and soil pore water chemical composition. This results in insufficient soil parameter monitoring, failing to effectively reflect the changes in soil physicochemical properties caused by CO2 leakage, thus affecting the accuracy and comprehensiveness of CO2 sequestration environmental risk assessments. Summary of the Invention

[0003] The purpose of this invention is to provide an experimental device for the impact of multiple leakage pathways of carbon dioxide geological storage on the soil environment, which solves the problems of single-pathway leakage simulation and incomplete soil parameter monitoring in existing technologies.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An experimental apparatus for simulating the soil environment through multiple pathways of carbon dioxide geological sequestration leakage includes a cubic, open-topped experimental container. The container is filled with soil after accommodating a wellbore leakage simulation unit, a fault zone leakage simulation unit, and a caprock leakage simulation unit. A three-in-one monitoring device and a soil solution sampler are installed within the soil. The caprock leakage simulation unit is plate-shaped and horizontally arranged at the bottom of the experimental container. The fault zone leakage simulation unit is plate-shaped and inclinedly arranged above the caprock leakage simulation unit. The wellbore leakage simulation unit is cylindrical, vertically penetrating the fault zone leakage simulation unit and positioned above the caprock leakage simulation unit. The wellbore leakage simulation unit, the fault zone leakage simulation unit, and the caprock leakage simulation unit are connected to a gas supply device, which independently supplies carbon dioxide gas to each of the three simulation units to simulate leakage scenarios. The three-in-one monitoring device and the soil solution sampler are connected to a data acquisition device. The gas supply device and the data acquisition device are connected to a control device.

[0006] The advantages of this invention are:

[0007] This invention can independently simulate leakage through three pathways: wellbore, fault zone, and caprock. It can also simultaneously simulate these three pathways under the same experimental conditions, allowing for a comparison of their impacts on the soil environment and effectively revealing the characteristics and mechanisms of each pathway. Furthermore, this invention can simultaneously monitor parameters such as pH, conductivity, CO2 concentration, and soil pore water chemical composition, providing comprehensive soil parameter monitoring and valuable data support for soil environmental risk assessment in CO2 sequestration projects. It is particularly suitable for studying the soil environmental impact under multi-pathway leakage scenarios. This invention is structurally stable, operationally controllable, allows for repeatable experiments, and yields accurate and reliable results, making it suitable for widespread application. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the composition of the experimental apparatus of the present invention.

[0009] Figure 2 This is a schematic diagram of the components of a wellbore leakage simulation unit.

[0010] Figure 3 This is a schematic diagram of the components of a fault zone leakage simulation unit.

[0011] Figure 4 This is a schematic diagram of the components of the caprock leakage simulation unit.

[0012] Figure 5 This is a schematic diagram of the arrangement of the three-in-one monitoring device and the soil solution sampler from a vertical cross-section.

[0013] Figure 6 This is a schematic diagram of the three-in-one monitoring device arranged around the wellbore, viewed from a horizontal cross-section. Detailed Implementation

[0014] like Figures 1 to 6 As shown, this invention proposes an experimental apparatus for the impact of multiple leakage pathways from carbon dioxide geological sequestration on the soil environment. It includes a cubic, open-topped experimental container 10. The container 10 is filled with soil after accommodating a wellbore leakage simulation unit 20, a fault zone leakage simulation unit 30, and a caprock leakage simulation unit 40. The soil is from the location simulating carbon dioxide geological sequestration. A three-in-one monitoring device 50 and a soil solution sampler 60 are installed within the soil. The caprock leakage simulation unit 40 is plate-shaped and horizontally arranged at the bottom of the experimental container 10, while the fault zone leakage simulation unit 30 is plate-shaped and inclinedly arranged above the caprock leakage simulation unit 40. The wellbore leakage simulation unit 20 is cylindrical, vertically penetrating the fault zone leakage simulation unit 30 and located above the caprock leakage simulation unit 40; the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 are connected to the gas supply device 70, which is used to independently supply carbon dioxide gas to the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 to simulate leakage conditions; the three-in-one monitoring device 50 and the soil solution sampler 60 are connected to the data acquisition device (not shown) via cables; the gas supply device 70 and the data acquisition device are connected to the control device (not shown).

[0015] refer to Figure 1 In the actual design, the length, width and height of the experimental container 10 are all 1 meter, and the experimental container 10 is made of stainless steel.

[0016] refer to Figure 1 and Figure 2 The wellbore leakage simulation unit 20 includes a stainless steel wellbore 21. Multiple leakage ports are evenly distributed along the circumference of the lower part of the wellbore 21. A needle valve 22 is installed at each leakage port. The needle valve 22 is driven by a pneumatic drive device 25. The air injection port of the needle valve 22 is located inside the wellbore 21 and is connected to the air supply device 70 through the wellbore capillary tube 24. A wellbore pressure sensor 23 is installed inside the wellbore capillary tube 24. Preferably, the wellbore pressure sensor 23 is located close to the needle valve 22.

[0017] In practice, the lower part of the well shaft 21 can be equipped with multiple sets of leakage outlets, with each set of leakage outlets evenly distributed along the circumference.

[0018] In this invention, the wellbore leakage simulation unit 20 is used to simulate a short-term, large-scale leakage of carbon dioxide gas from the wellbore into the soil outside the wellbore during the injection of carbon dioxide gas to be sealed through the wellbore. It can also be used to simulate a small-scale leakage of carbon dioxide gas from the wellbore into the soil outside the wellbore during long-term sealing. In other words, the wellbore leakage simulation unit 20 can simulate carbon dioxide leakage at different locations and rates within the wellbore. The wellbore pressure sensor 23 is used to monitor the carbon dioxide gas pressure at the leak point, and the needle valve 22, driven by a pneumatic actuator 25, is used to control the flow rate of carbon dioxide gas leaking from the wellbore 21, for example, maintaining the gas flow rate at a single leak point between 0.1 L / min and 5 L / min.

[0019] In actual implementation, the diameter of the well shaft 21 is 50mm-80mm, the height is 800mm-1000mm, and the diameter of the leakage outlet is 2mm-5mm.

[0020] refer to Figure 1 and Figure 3 The fault zone leakage simulation unit 30 includes a top-opening, stainless steel tray 31. Multiple holes are evenly distributed on the bottom 311 of the tray 31. A perforated gas injection pipe 36 is located at the bottom of the inclined tray 31. One end of the gas injection pipe 36 is closed, and the other end is connected to a fault zone gas injection port 34 on the side wall of the tray 31. An inlet pipe 312 is provided inside the tray 31 for inserting and penetrating the wellbore 21 into the fault zone leakage simulation unit 30. The inlet pipe 312 is cylindrical, and its bottom opening communicates with an opening on the bottom 311 of the tray 31. The fault zone air injection port 34 is connected to the air supply device 70 via the fault zone capillary tube 39. The fault zone capillary tube 39 is equipped with a fault zone pressure sensor 37 and a fault zone flow regulating valve 38. Preferably, the fault zone pressure sensor 37 and the fault zone flow regulating valve 38 are located near the fault zone air injection port 34. After multiple baffles 33 are arranged vertically and vertically in the tray 31, the mixed filler 32 is filled in. After the mixed filler 32 is compacted by a compactor until the permeability of the mixed filler 32 reaches a preset value, the baffles 33 are removed.

[0021] In practical implementation, the tray 31 can be designed with a parallelogram cross-section. The dimensions of the tray 31 can be reasonably designed without limitations; typically, the height of the tray 31 is designed to be 200mm-300mm. A gap is usually left between the tray 31 and the experimental container 10 to allow for the proper distribution of the fault-bounded capillaries 39 within the soil. The bottom surface inside the tray 31 has slots (not shown) for installing and removing partitions 33. Two to four partitions 33 can be arranged in parallel inside the tray 31. The partitions 33 are used to form parallel cracks of 0.5mm-5mm (this can be achieved using partitions of different thicknesses).

[0022] Furthermore, the mixed filler 32 is composed of quartz sand and clay, with a ratio of quartz sand to clay of 7:3-9:1, and the two are mixed evenly. In practical applications, the particle size of the quartz sand is between 0.5mm and 2mm, and the clay can be kaolin or other materials. By adjusting the ratio of quartz sand to clay, fault zone matrices with different permeabilities can be simulated.

[0023] In practical implementation, for example, by compaction with a compactor, the dry density of the mixed filler 32 is made to be 1.4 g / cm³. 3 -1.8g / cm 3 Between, penetration rate is 10 -3 Darcy-10 -1 Between Darcy.

[0024] In this invention, the fault zone leakage simulation unit 30 is used to simulate a small amount of carbon dioxide gas leaking from the fault zone during long-term carbon dioxide gas storage. That is, the fault zone leakage simulation unit 30 can simulate carbon dioxide leaking from the fault zone at different rates. Specifically, the fault zone pressure sensor 37 is used to monitor the pressure of the carbon dioxide gas injected into the fault zone leakage simulation unit 30, and the fault zone flow regulating valve 38 is used to control the flow rate of the carbon dioxide gas injected into the fault zone leakage simulation unit 30, thereby simulating the process of CO2 slowly permeating and diffusing through the fault zone.

[0025] refer to Figure 1 and Figure 4 The caprock leakage simulation unit 40 includes an open top and a stainless steel container 41. The side wall of the horizontally arranged container 41 is provided with a caprock air injection port 44. The caprock air injection port 44 is connected to the air supply device 70 via a caprock capillary tube 47. A caprock pressure sensor 45 is provided inside the caprock capillary tube 47. A caprock flow regulating valve 46 is provided on the caprock capillary tube 47. Preferably, the caprock pressure sensor 45 and the caprock flow regulating valve 46 are located near the caprock air injection port 44. The container 41 is filled with gravel filler 42, and a cracked top plate 43 is laid on the top surface of the gravel filler 42.

[0026] Furthermore, the top plate 43 is a cement board (thickness of 50mm-100mm) or a natural mudstone board (thickness of 200mm-300mm) with a compressive strength between 10MPa and 30MPa and a permeability of <1mD. The top plate 43 is placed in a high-pressure reactor for fracturing, including the following steps: applying confining pressure (5MPa-20MPa) and axial pressure (10MPa-30MPa) to the high-pressure reactor to simulate the geostress environment, gradually increasing the CO2 pressure injected into the high-pressure reactor (controlled between 0.1MPa / h and 0.5MPa / h) until the top plate 43 fractures, recording the injection pressure and fracture distribution characteristics at the time of fracture, and completing the fracturing when the fracture distribution characteristics meet the simulation requirements.

[0027] In practice, the size of the receiving tray 41 can be designed reasonably without limitation. Typically, a gap is left between the receiving tray 41 and the experimental container 10 to allow the capillary tubes 47 of the cover layer to be properly distributed within the soil. The gravel particle size is 0.2mm-1.6mm.

[0028] In this invention, the caprock leakage simulation unit 40 is used to simulate the situation where carbon dioxide gas continuously leaks from the caprock in small amounts during long-term carbon dioxide gas storage. That is, the caprock leakage simulation unit 40 can simulate the continuous leakage of carbon dioxide from the caprock at different rates. Specifically, the caprock pressure sensor 45 is used to monitor the pressure of the carbon dioxide gas injected into the caprock leakage simulation unit 40, and the caprock flow regulating valve 46 is used to control the flow rate of the carbon dioxide gas injected into the caprock leakage simulation unit 40 (controlled between 0.5 L / min and 10 L / min) to simulate the process of CO2 slowly permeating and diffusing through the caprock.

[0029] In the actual design, the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 are detachably installed inside the experimental container 10. Specifically: the bottom of the experimental container 10 is provided with a slot for securing the caprock leakage simulation unit 40; more preferably, the receiving tray 41 of the caprock leakage simulation unit 40 is provided with handles (not shown) on both sides; the side wall of the experimental container 10 is provided with a clamping groove (not shown) for securing the fault zone leakage simulation unit 30. The shape of the clamping groove should be adapted to the shape of the top tip of the tray 31 of the fault zone leakage simulation unit 30 so as to secure it; the upper part of the experimental container 10 is provided with a bracket (not shown) for holding the upper part of the wellbore leakage simulation unit 20. That is, the wellbore leakage simulation unit 20 is kept vertical by its lower part being inserted through the fault zone leakage simulation unit 30 and its upper part being supported by the bracket.

[0030] In practical applications, the wellbore capillary 24 of the wellbore leakage simulation unit 20, the fault zone capillary 39 of the fault zone leakage simulation unit 30, and the caprock capillary 47 of the caprock leakage simulation unit 40 are preferably led out from the top of the soil. Of course, they can also be led out from the side wall of the experimental container 10 (attention should be paid to the air leakage prevention and sealing treatment), without limitation. The wellbore capillary 24, fault zone capillary 39, and caprock capillary 47 are made of stainless steel capillary tubes.

[0031] In practical implementation, the gas supply device 70 may include a steel high-pressure gas storage tank. The outlet of the gas storage tank is sequentially connected to a primary pressure reducing valve (pressure adjusted to 2MPa-5MPa) and a secondary pressure regulating valve (pressure adjusted to 0.1MPa-2MPa, with an accuracy of ±0.01MPa), and then connected to the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40. The configuration of the gas supply device 70 is based on well-known technology and is not subject to the above limitations.

[0032] In this invention, the data acquisition device can be set as an industrial-grade data acquisition device with an adjustable sampling frequency. It can connect to various sensors via a wired bus, and the data can be stored in a local database (such as MySQL) in real time. It can also be equipped with a threshold alarm function, and can perform long-term storage and visualization analysis of the data.

[0033] In this invention, the control device is a well-known technology and generally includes a microprocessor, without limitation. The control device is used to receive data fed back from the data acquisition device, control the external gas supply of the gas supply device 70, and perform data analysis and processing, etc.

[0034] In actual design, the three-in-one monitoring device 50 includes a housing, inside which are installed a pH sensor, a conductivity sensor, and a carbon dioxide sensor. The probes of the pH sensor, conductivity sensor, and carbon dioxide sensor extend from the housing and are used to insert into the soil for detection.

[0035] In practical applications, a fixing frame (not shown) can be provided on the experimental container 10 for fixing the three-in-one monitoring device 50 and the soil solution sampler 60, so that after the soil is filled into the experimental container 10, the three-in-one monitoring device 50 and the soil solution sampler 60 can be stably placed in the soil in a preset position.

[0036] Furthermore, the three-in-one monitoring device 50 is arranged in four distribution methods: The first distribution method is to set multiple layers in the vertical direction, with multiple three-in-one monitoring devices 50 arranged in a matrix in each layer to monitor parameters at different depth positions; The second distribution method is to set multiple groups at predetermined depth positions with the axis of the well shaft 21 of the well shaft leakage simulation unit 20 as the center, and each group includes multiple three-in-one monitoring devices 50 evenly distributed in the circumferential direction (the predetermined depth position can be multiple); The third distribution method is to set multiple three-in-one monitoring devices 50 in the soil filled in the experimental container 10 and above the fault zone leakage simulation unit 30, with each three-in-one monitoring device 50 spaced apart along the tilt direction of the fault zone leakage simulation unit 30. This distribution method can share one or more three-in-one monitoring devices 50 with the first distribution method; The fourth distribution method is to set multiple three-in-one monitoring devices 50 in the soil filled in the experimental container 10 and above the cap layer leakage simulation unit 40, with each three-in-one monitoring device 50 arranged in a grid form.

[0037] Furthermore, a soil solution sampler 60 is set near the outside of the wellbore leakage simulation unit 20, and a soil solution sampler 60 is set near the top surface of the fault zone leakage simulation unit 30 and the caprock leakage simulation unit 40, respectively, without limitation.

[0038] The arrangement of the aforementioned three-in-one monitoring device 50 and soil solution sampler 60 ensures effective coverage of the leakage plume diffusion range.

[0039] In practical applications, the pH sensor can be an industrial-grade piercing sensor (e.g., the SEN0161 model, with a measurement range of 0-14 pH and an accuracy of ±0.1 pH), which is resistant to moist soil environments. The conductivity sensor can be a four-electrode sensor (e.g., the DJS-1C model, with a range of 0-20 mS / cm), reducing interference from soil salinity. The carbon dioxide sensor can be an infrared gas sensor (e.g., the MG811 model, with a detection range of 0-5000 ppm and a response time <10 s). The soil solution sampler 60 can be a negative pressure soil solution sampler (e.g., the SU-800 model, with a sampling capacity of 50 mL), and should also be equipped with an ion chromatograph to analyze cations (such as Ca). 2+ Mg 2+ ) and anions (such as HCO3-) - Cl - The ion chromatograph is connected to the control device.

[0040] In addition, a heat preservation device (not shown) can be installed on the experimental container 10 to maintain the soil temperature inside the experimental container 10 within the required range. Specifically, the heat preservation device includes an annular constant-temperature heating jacket wrapped around the outer wall of the experimental container 10. A temperature sensor (such as Pt100, with an accuracy of ±0.1℃) is embedded in the soil. The temperature sensor feeds back the collected temperature data to a temperature controller. The temperature controller (with a temperature control range of 20℃-30℃) adjusts the heating power of the annular constant-temperature heating jacket in real time to ensure that the soil ambient temperature fluctuation is ≤ ±0.5℃, thus meeting the experimental requirements.

[0041] Before the experiment, the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 were assembled according to the simulation requirements. Then, the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 were installed in the experimental container 10. The three-in-one monitoring device 50 and the soil solution sampler 60 were fixed in the experimental container 10. Then, soil was filled in to complete the experimental preparation.

[0042] Then, according to the experimental requirements, the gas supply device 70 is activated via the control device to supply gas to the corresponding simulation unit to perform the simulation. For example, if it is necessary to simulate the leakage of carbon dioxide through the caprock, the gas supply device 70 supplies carbon dioxide gas to the caprock leakage simulation unit 40. During the supply process, pH value, conductivity, CO2 concentration, and soil pore water are collected periodically via the three-in-one monitoring device 50 and the soil solution sampler 60. The collected data are transmitted to the control device for analysis and processing via the data acquisition device. For example, the collected soil pore water is processed simply by the control device and then transmitted to the ion chromatograph to obtain the chemical composition of the pore water. In practical applications, spatiotemporal distribution maps can be plotted based on the collected parameters to assist in assessing the impact of carbon dioxide leakage on the soil environment.

[0043] In practice, the wellbore leakage simulation unit 20, the fault zone leakage simulation unit 30, and the caprock leakage simulation unit 40 can be used to simulate leakage through the three pathways of wellbore, fault zone, and caprock separately. Alternatively, the three pathways of wellbore, fault zone, and caprock can be simulated simultaneously under the same experimental conditions, thereby effectively comparing the differences in the impact of the three pathways of leakage on the soil environment.

[0044] The following example illustrates the experimental preparation and process.

[0045] First, the stability of the experimental apparatus of the present invention is determined through the following process.

[0046] Platform setup: The experiment was conducted on a 1m×1m×1m cubic stainless steel experimental container 10, which was equipped with an insulation device. The inner wall of the experimental container 10 could be lined with a 0.5mm thick fluororubber gasket to prevent air leakage.

[0047] Fabricate and assemble each simulation unit:

[0048] The wellbore leakage simulation unit 20 is made of a 316 stainless steel wellbore 21 with a diameter of 50mm and a length of 900mm. Four leakage ports with a diameter of 3mm are opened at a height of 0.3m on the side wall of the wellbore 21. A needle valve 22 is installed on each leakage port. The air injection port of the needle valve 22 is located inside the wellbore 21 and is connected to the wellbore capillary tube 24. A wellbore pressure sensor 23 (range 0-2MPa) is installed inside the wellbore capillary tube 24 near the air injection port. The drive end of the needle valve 22 is located outside the wellbore 21 and is connected to the pneumatic drive device 25.

[0049] The fault zone leakage simulation unit 30 uses a tray 31 with an open top and an internal perforated air injection pipe 36 and an inlet pipe 312. The bottom 311 of the tray 31 has evenly distributed perforations (such as a grid). Four 2mm thick partitions 33 are inserted into the tray 31, forming four 2mm wide cracks. Then, a mixed filler 32 is filled in, consisting of quartz sand and clay. The quartz sand particle size is 0.5mm-1mm, and the ratio of quartz sand to clay is 8:2. It is then compacted to a dry density of 1.5g / cm³ using a compactor. 3 After meeting the permeability requirements, the partition 33 is removed. The gas injection port 34 of the fault zone on the side wall of the tray 31 is connected to the fault zone capillary tube 39. A fault zone pressure sensor 37 (range 0-2MPa) is installed inside the fault zone capillary tube 39 near the gas injection port 34.

[0050] The caprock leakage simulation unit 40 uses an open-topped container 41 filled with gravel filler 42, the gravel particle size being 0.8mm-1mm. A top plate 43, pre-fractured by a high-pressure reactor, is then laid on top of the gravel filler 42. This top plate 43 is made of cement board with a compressive strength of 20MPa, a permeability of <1mD, and a thickness of 50mm. A caprock gas injection port 44 on the side wall of the container 41 is connected to a caprock capillary tube 47. A caprock pressure sensor 45 (range 0-2MPa) is installed inside the caprock capillary tube 47, near the caprock gas injection port 44.

[0051] Then, the aforementioned simulation units are installed inside the experimental container 10: the caprock leakage simulation unit 40 is fixed to the bottom of the experimental container 10, and the fault zone leakage simulation unit 30 is fixed at an angle at a depth of 0.4m-0.6m inside the experimental container 10, above the caprock leakage simulation unit 40. The wellbore 21 is then inserted into the inlet pipe 312 and fixed, with the wellbore 21 vertically positioned at the center of the experimental container 10. The wellbore capillary 24, fault zone capillary 39, and caprock capillary 47 are then connected to the gas supply device 70, and fault zone flow regulating valve 38 and caprock flow regulating valve 46 are respectively installed on the fault zone capillary 39 and caprock capillary 47.

[0052] Then, the three-in-one monitoring device 50 and the soil solution sampler 60 are fixed in the experimental container 10 according to the monitoring requirements, and the three-in-one monitoring device 50 and the soil solution sampler 60 are connected to the data acquisition device. Here, in the vertical direction, the three-in-one monitoring devices 50 are arranged in layers of 0.1m, 0.3m, 0.5m, 0.7m, and 0.9m, with each layer arranged in a 3×3 matrix. Figure 5 In the horizontal direction, two groups of monitoring devices 50 are set up around the well shaft 21 with radii of 0.2m and 0.4m, respectively. Each group consists of four three-in-one monitoring devices 50 evenly distributed in a circular direction. Figure 6Above the fault zone, three three-in-one monitoring devices 50 are arranged at equal intervals, one of which is positioned 0.9m vertically. Figure 1 Above the caprock, nine three-in-one monitoring devices 50 (not shown) are arranged in a 3×3 grid. In addition, a soil solution sampler 60 is installed near the outside of the wellbore 21, near the fault zone, and near the caprock.

[0053] Then, fill experimental container 10 with air-dried soil (particle size 0.05mm-2mm, moisture content 18%), and compact it in layers until the dry density is 1.6g / cm³. 3 This is to ensure that the soil is uniform and without gaps.

[0054] During the experiment, the soil temperature was preheated for 30 minutes to stabilize at 25±0.5℃. The corresponding simulation unit was then activated to conduct the experiment according to the experimental requirements.

[0055] When simulating single-path leakage, a wellbore leakage is used as an example:

[0056] Close the fault zone flow regulating valve 38 and the caprock flow regulating valve 46. Open the needle valve 22 and adjust the CO2 injection flow rate to 1 L / min. Simultaneously, adjust the CO2 injection pressure to 0.5 MPa using the wellbore pressure sensor 23. Start the data acquisition device to collect samples: pH value and conductivity are sampled every 1 hour; CO2 concentration is sampled every 0.5 hours; and soil pore water is sampled once daily at 9:00 AM (50 mL each time). After low-temperature (4℃) storage, Ca is analyzed using an ion chromatograph within 48 hours. 2+ HCO3 - Concentration. Continuous monitoring for 24 hours.

[0057] Similarly, when simulating fault zone leakage alone, the CO2 injection pressure was maintained at 0.3 MPa and the CO2 injection flow rate was adjusted to 0.8 L / min. When simulating caprock leakage alone, the CO2 injection pressure was maintained at 0.8 MPa and the CO2 injection flow rate was adjusted to 1.2 L / min. Each individual simulation scenario was monitored for 24 hours.

[0058] During the simultaneous simulation of multi-path leakage, the fault zone flow regulating valve 38, the caprock flow regulating valve 46, and the needle valve 22 were simultaneously opened. The CO2 injection flow rate in the wellbore was adjusted to 1 L / min and the injection pressure to 0.5 MPa; the CO2 injection flow rate in the fault zone was adjusted to 0.8 L / min and the injection pressure to 0.3 MPa; and the CO2 injection flow rate in the caprock was adjusted to 1.2 L / min and the injection pressure to 0.8 MPa. The sampling frequency of the data acquisition device was consistent with that of the individual simulation, and continuous monitoring was conducted for 48 hours, recording the superimposed changes of the parameters collected at each sampling point (such as the CO2 concentration gradient at the intersection of the wellbore and the fault zone (0.5 m depth)).

[0059] In actual experiments, under the same soil conditions (e.g., moisture content 18%, dry density 1.6 g / cm³), 3 Under the same CO2 parameters (such as pressure and flow rate), the above experimental process was repeated multiple times (e.g., 3 times), with the soil refilled and the sensor calibrated before each experiment.

[0060] Based on the above repeated experiments, the average value and standard deviation of the collected parameters at the same sampling point and time point were calculated to determine whether there was any data bias. The allowable deviation ranges were set as follows: pH measurement deviation ±0.1, conductivity measurement deviation ±0.2 mS / cm, CO2 concentration measurement deviation ±50 ppm, and pore water composition (Ca... 2+ HCO3 - The concentration measurement deviation is ±5 mg / L. If the standard deviation of each collected data is within the allowable range, the stability of the experimental apparatus of this invention is deemed qualified. If the deviation of a certain parameter exceeds the range, check the sensor connection status and the stability of the CO2 supply pressure, etc., recalibrate and repeat the experiment until the deviation requirement is met.

[0061] Once the stability of the experimental device of the present invention is determined to be qualified, a formal experiment can be carried out based on the above experimental process, which will not be described in detail here.

[0062] The present invention has the following beneficial effects:

[0063] First, the leakage simulation breaks through the limitations of a single path: This invention independently controls the CO2 supply for three leakage paths—well shaft, fault zone, and caprock—within the same 1m×1m×1m experimental container. It can perform individual or simultaneous simulations of leakage through these three paths without changing the simulation unit, and can quantify the differences in the impact of different leakage paths on the soil environment (such as the comparison of CO2 diffusion rates between caprock and well shaft leakage). Compared with the existing single-path leakage simulation mode, this invention greatly reduces the number of experiments, significantly improves experimental efficiency, and makes the experiment less cumbersome.

[0064] Second, parameter monitoring addresses the issue of incompleteness: This invention proposes simultaneous monitoring of four parameters—pH, electrical conductivity, CO2 concentration, and soil pore water chemical composition—in both vertical and horizontal directions, achieving comprehensive monitoring. This effectively captures the spatiotemporal changes in soil physicochemical properties (such as the CO2 concentration gradient between well leakage at 0.3m and caprock leakage at 0.9m), ensuring the accuracy and comprehensiveness of CO2 sequestration environmental risk assessment.

[0065] Third, modular design ensures effective implementation: The wellbore, fault zone and caprock leakage simulation unit designed in this invention is modular, which is easy to install and disassemble, and the sensors are easy to install and disassemble. The experimental process can be repeated, the operation is controllable, the experimental results are accurate and reliable, and it is easy to maintain and manage. In addition, the types of sensors used for parameter monitoring can be expanded to adapt to different scenario requirements.

[0066] The above description describes the preferred embodiments of the present invention and the technical principles applied thereto. For those skilled in the art, any obvious changes such as equivalent transformations or simple substitutions based on the technical solutions of the present invention, without departing from the spirit and scope of the present invention, shall fall within the protection scope of the present invention.

Claims

1. A device for testing the influence of multi-path leakage of carbon dioxide geological storage on the soil environment, characterized in that, The experimental container includes a cubic shape, a top open container, a wellbore leakage simulation unit, a fault zone leakage simulation unit and a caprock leakage simulation unit are arranged in the container, and the container is filled with soil, a three-in-one monitoring device and a soil solution sampler are arranged in the soil, wherein: the caprock leakage simulation unit is arranged horizontally on the bottom of the experimental container, the fault zone leakage simulation unit is arranged obliquely on the caprock leakage simulation unit, and the wellbore leakage simulation unit is vertically arranged in the fault zone leakage simulation unit and above the caprock leakage simulation unit; the wellbore leakage simulation unit, the fault zone leakage simulation unit and the caprock leakage simulation unit are connected with a gas supply device, the gas supply device is used for independently supplying carbon dioxide gas for simulating leakage conditions to the wellbore leakage simulation unit, the fault zone leakage simulation unit and the caprock leakage simulation unit; the three-in-one monitoring device and the soil solution sampler are connected with a data acquisition device; the gas supply device and the data acquisition device are connected with a control device; the three-in-one monitoring device includes a shell, a pH sensor, a conductivity sensor and a carbon dioxide sensor are arranged in the shell, and the probes of the pH sensor, the conductivity sensor and the carbon dioxide sensor are arranged in the shell.

2. The experimental apparatus for soil environmental impact of multi-path leakage of carbon dioxide geological storage according to claim 1, wherein, The wellbore leakage simulation unit includes a wellbore, a plurality of leakage ports are uniformly distributed in the circumferential direction of the lower part of the wellbore, a needle valve is installed at each leakage port, the needle valve is driven by a pneumatic driving device, and the air injection port of the needle valve is in the wellbore and connected with the gas supply device through a wellbore capillary tube, and a wellbore pressure sensor is arranged in the wellbore capillary tube.

3. The experimental apparatus for soil environmental impact of multi-path leakage of carbon dioxide geological storage according to claim 2, wherein, The fault zone leakage simulation unit includes a top open tray, a plurality of holes are uniformly distributed on the tray bottom, a hole injection pipe is arranged on the bottom of the obliquely arranged tray, one end of the hole injection pipe is closed and the other end is connected with the fault zone air injection port of the tray side wall, a guide pipe is arranged in the tray for inserting and penetrating the fault zone leakage simulation unit, the fault zone air injection port is connected with the gas supply device through a fault zone capillary tube, a fault zone pressure sensor is arranged in the fault zone capillary tube, and a fault zone flow regulating valve is arranged on the fault zone capillary tube, wherein a plurality of partitions are arranged in the tray, and mixed filling material is filled in the tray after the partitions are removed.

4. The apparatus according to claim 3, wherein the apparatus is characterized by: The mixed filling material is composed of quartz sand and clay, and the ratio of quartz sand to clay is 7:3-9:

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5. The apparatus according to claim 3, wherein the apparatus is characterized by: The caprock leakage simulation unit includes a top open container, a caprock air injection port is arranged on the side wall of the horizontally arranged container, the caprock air injection port is connected with the gas supply device through a caprock capillary tube, a caprock pressure sensor is arranged in the caprock capillary tube, and a caprock flow regulating valve is arranged on the caprock capillary tube, wherein the gravel filling material is filled in the container, and the top plate with cracks is arranged on the top surface of the gravel filling material.

6. The apparatus according to claim 5, wherein the apparatus is characterized by: The top plate is a cement plate or natural mudstone plate with a compressive strength of 10-30 MPa and a permeability of <1 mD, wherein: the top plate is placed in a high-pressure reaction kettle for fracturing, including the steps of: the high-pressure reaction kettle applies confining pressure and axial pressure to simulate the stress environment, gradually increases the CO2 pressure injected into the high-pressure reaction kettle to the top plate rupture, records the injection pressure and crack distribution characteristics at the time of rupture, and completes the fracturing when the crack distribution characteristics meet the simulation requirements.

7. The apparatus according to claim 5, wherein the apparatus is characterized by: The wellbore leakage simulation unit, the fault zone leakage simulation unit and the caprock leakage simulation unit are detachably installed in the experimental container, wherein: the bottom of the experimental container is provided with a clamping groove for clamping the caprock leakage simulation unit; the sidewall of the experimental container is provided with a clamping groove for clamping the fault zone leakage simulation unit; and the upper part of the experimental container is provided with a support for holding the upper part of the wellbore leakage simulation unit.

8. The apparatus according to claim 1, wherein the apparatus is used for testing the influence of carbon dioxide geological storage multi-path leakage on the soil environment. The three-in-one monitoring device is arranged in four distribution modes: the first distribution mode is to arrange multiple three-in-one monitoring devices in a matrix form in each layer in the vertical direction; the second distribution mode is to arrange multiple groups of three-in-one monitoring devices at a predetermined depth position around the wellbore axis of the wellbore leakage simulation unit, each group including multiple three-in-one monitoring devices uniformly distributed in the circumferential direction; the third distribution mode is to arrange multiple three-in-one monitoring devices in the soil filled in the experimental container above the fault zone leakage simulation unit, and each three-in-one monitoring device is arranged in the direction of the fault zone leakage simulation unit; and the fourth distribution mode is to arrange multiple three-in-one monitoring devices in the soil filled in the experimental container above the caprock leakage simulation unit, and each three-in-one monitoring device is arranged in a grid form. A soil solution sampler is arranged near the outside of the wellbore leakage simulation unit, and a soil solution sampler is arranged near the top surface of the fault zone leakage simulation unit and the caprock leakage simulation unit.

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