Water-soluble cavity-building simulation test device and method for deep salt layer gas storage

Abstract

The invention belongs to the technical field of petroleum industrial equipment, and discloses a deep salt bed gas storage water-soluble cavity construction simulation test device and method.The deep salt bed gas storage water-soluble cavity construction simulation test device comprises a test bed, a gas storage model, a test assembly and a water tank, and the test bed is sequentially provided with a rack, a control panel and a test cavity from top to bottom; the gas reservoir model comprises a pressure-bearing cylinder and a salt brick, and a blind hole is formed in the top surface of the salt brick; the test assembly comprises a pump body, an inner sleeve, an outer sleeve and a pressure module, the bottom ends of the outer sleeve and the inner sleeve are open and located in the blind hole, and the pressure module is communicated with the inner sleeve and the pressure cavity to control the pressure inside and outside the salt brick. By arranging the salt bricks, the heterogeneity of the salt layer is simulated. The gas reservoir model is matched with the test assembly, so that the water-soluble cavity-building process of the deep-salt-bed gas reservoir can be simulated at high precision, and reliable technical support is provided for design, construction and safe operation of the deep-salt-bed gas reservoir.

Description

Technical Field

[0001] This invention relates to the field of petroleum industry equipment technology, and in particular to a simulation test device and method for water-soluble cavity creation in deep saline gas storage tanks. Background Technology

[0002] Deep saline aquifer gas storage is a novel and efficient natural gas storage solution, one of its core technologies being pressurized water-dissolution cavity construction. This process involves injecting fresh water into underground saline layers, utilizing the dissolving effect of water on the salt to form cavities with specific shapes and sizes for natural gas storage. In practical engineering, due to the complexity and heterogeneity of saline geological conditions, controlling the morphology of the cavities is quite challenging. The morphology of the cavities directly affects the storage capacity, sealing performance, and operational safety of the gas storage facility, necessitating the development of precise cavity morphology control methods. Currently, research on pressurized water-dissolution cavity construction technology for deep saline aquifer gas storage both domestically and internationally mainly focuses on numerical simulation and field testing. Numerical simulation can predict the morphological evolution of cavities, but its accuracy depends on the precision of the model parameters. Only some proven field tests can provide accurate data, and this approach suffers from drawbacks such as high cost, long development cycles, and difficulty in reproducibility. Therefore, the current market primarily employs physical experimental models for cavity morphology control research.

[0003] However, most existing physical model testing devices cannot realistically simulate the high-pressure environment of deep salt layers, resulting in significant deviations between experimental results and actual conditions. In addition, the testing devices lack the ability to simulate the heterogeneity of salt layers, making it difficult to reflect the influence of complex geological conditions on the morphology of solution cavities.

[0004] Therefore, there is an urgent need for a water-soluble cavity simulation test device and method for deep saline gas storage to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a simulation test device for water-soluble cavity construction in deep saline gas storage tanks, which can simulate the high-pressure environment and heterogeneity of deep saline layers, and accurately study the evolution law of cavity morphology during pressurized water-soluble cavity construction.

[0006] To achieve this objective, the present invention adopts the following technical solution: a water-soluble cavity simulation test device for deep saline gas storage, comprising a test platform, a gas storage model, test components, and a water tank. The test platform is provided with a frame, a control panel, and a test cavity from top to bottom. The gas storage model includes a transparent pressure cylinder and a salt brick. The pressure cylinder is located inside the test cavity and has a pressure chamber. The salt brick is fixed inside the pressure chamber and is rectangular in shape. A transparent plate is fixed to one side wall of the salt brick. A blind hole is opened on the top surface of the salt brick, and the blind hole is filled with salt powder. Along the radial direction of the blind hole, the minimum distance between the center line of the blind hole and the transparent plate is less than the radius of the blind hole. The test components include a pump body, an inner sleeve, an outer sleeve, and a pressure module. The inner sleeve and the outer sleeve... The tubes are slidably connected to the frame in the vertical direction. The inner sleeve and the outer sleeve are coaxially arranged and pass through the outer sleeve. The outer sleeve is sealed to the salt brick and abuts against the transparent plate. The bottom ends of the outer sleeve and the inner sleeve are both open and located in the blind hole. The pressure module is electrically connected to the control panel. The pressure module is connected to the inner sleeve and the pressure chamber to control the pressure inside and outside the salt brick. The output end of the pump body is connected to the inner sleeve. The water tank is installed in the test chamber and has two inner cavities. One inner cavity is selectively connected to one of the inner sleeve and the outer sleeve through the pump body, and the other inner cavity is connected to the other of the inner sleeve and the outer sleeve.

[0007] Preferably, the pressure cylinder includes a mounting base and a cover, the cover being able to be sealed to the mounting base to form the pressure chamber, both the mounting base and the cover being provided with sealing seats, and the two sealing seats being arranged opposite each other to position the salt brick in the vertical direction.

[0008] Preferably, the pressure module includes a hydraulic cylinder and a constant flow pump. The mounting base is provided with a pressure channel. The hydraulic cylinder is connected to the pressure chamber through the pressure channel. The constant flow pump is installed on the test bench and is connected to the inner sleeve.

[0009] Preferably, the gas storage model also includes a slide table with a wheel assembly at the bottom, and the pressure cylinder is detachably connected to the slide table.

[0010] Preferably, the top sidewall of the inner sleeve is provided with a first interface, and the top sidewall of the outer sleeve is provided with a second interface. Both the first interface and the second interface are detachably connected to the water tank. The first interface and the second interface have the same shape and are equal in size.

[0011] Preferably, the test assembly further includes a laser probe, which is electrically connected to the control panel via a wire. The laser probe is located inside the blind hole, and the wire passes through the inner sleeve and is sealed to the first interface.

[0012] Preferably, the test assembly further includes two Baumé concentration meters, one of which is installed at the first interface and the other at the second interface. The test bench is equipped with two cameras, which are respectively positioned facing the two Baumé concentration meters and are both electrically connected to the control panel.

[0013] Preferably, the test chamber is equipped with a lighting element.

[0014] Preferably, the control panel also includes a display.

[0015] Another objective of this invention is to provide a simulation test method for water-soluble cavity formation in deep saline gas storage tanks, which simulates the evolution of cavity morphology under different cavity formation conditions by precisely controlling experimental parameters.

[0016] To achieve this objective, the present invention adopts the following technical solution: a water-soluble cavity-forming simulation test method for deep saline gas storage, implemented using the aforementioned water-soluble cavity-forming simulation test device for deep saline gas storage, comprising the following steps: constructing a test device and installing the salt bricks according to the actual saline depth and thickness of the gas storage, such that both the inner sleeve and the outer sleeve extend into the salt bricks; determining the test scale according to the geometric ratio between the salt bricks and the actual gas storage, and setting test parameters according to the test scale and the cavity-forming parameters of the actual gas storage; injecting water into the salt bricks to drain brine according to the test parameters to form a cavity; adjusting the water injection flow rate, water injection time, and the distance between the bottom openings of the inner sleeve and the outer sleeve, and recording the morphological changes of the cavity in real time.

[0017] The beneficial effects of this invention are as follows: Before using the experimental device, salt bricks are prepared. Blind holes are drilled on the salt bricks to simulate the actual drilling conditions, including the drilling location and route. After inserting the outer casing into the blind hole, the outer casing is cemented. Then, salt powder is filled under the unsealed outer casing. After attaching a transparent plate, the salt brick is fixedly installed in the pressure chamber. Simultaneously, the inner casing is installed, and the outer casing is installed on the frame, thus completing the salt brick installation. When using the experimental device, the pressure module and pump are started. The pressure module injects high pressure into the solution cavity inside the salt brick and the pressure chamber outside the salt brick. At the same time, under the action of the pump, one of the inner and outer casings injects water towards the location where the salt powder is filled, forming a solution cavity. The other casing discharges excess brine from the solution cavity, allowing the solution cavity to expand regularly and stably. At this time, the user can observe and record the morphological changes of the solution cavity through the transparent pressure cylinder and transparent plate. Afterward, the user can adjust parameters such as the distance between the pipe openings of the inner and outer casings, the water injection flow rate, and the water injection time to study the influence of different parameters on the solution cavity expansion law. By setting up salt bricks, users can simulate the heterogeneity of salt layers by using salt bricks of different specifications and filling them with different types and qualities of salt powder, thus improving the simulation accuracy of the salt bricks. By setting up experimental components, the pressure module of the experimental components can precisely control the internal and external pressures of the salt bricks, realistically simulating the high-pressure environment of deep salt layers and improving the fit between experimental results and actual conditions. The inner and outer sleeves work together to achieve water injection and brine drainage for cavity creation, realistically reproducing the water-soluble cavity creation process under high-pressure conditions in deep salt layers, ensuring the structural stability of the cavity. The gas storage model and experimental components work together to accurately simulate the water-soluble cavity creation process of deep salt layer gas storage. Based on this, by precisely controlling parameters such as pipe opening distance, water injection flow rate, and water injection time, it is possible to efficiently simulate the evolution of cavity morphology under different cavity creation conditions and ensure cavity stability, providing reliable technical support for the design, construction, and safe operation of deep salt layer gas storage.

[0018] This invention also provides a simulation test method for water-soluble cavity building in deep saline gas storage tanks. Based on similarity theory, the method designs salt bricks and test devices to ensure that the test devices can accurately simulate the pressurized water-soluble cavity building process in actual deep saline gas storage tanks under actual working conditions. By comprehensively considering three parameters, namely the distance between the two pipe openings, the water injection time, and the water injection flow rate, a more scientific and reasonable cavity building scheme can be formulated, which can improve the cavity building efficiency and ensure the regularity and stability of the cavity morphology. Attached Figure Description

[0019] Figure 1 This is a front view of the deep saline gas storage water-soluble cavity simulation test device according to an embodiment of the present invention;

[0020] Figure 2 This is a side view of the deep saline gas storage water-soluble cavity simulation test device according to an embodiment of the present invention;

[0021] Figure 3 This is a flowchart illustrating the steps of the water-soluble cavity simulation test method for a deep saline gas storage tank according to an embodiment of the present invention.

[0022] In the picture:

[0023] 1. Test bench; 11. Frame; 12. Control panel; 121. Monitor; 13. Test chamber; 131. Locking device; 132. Lighting device;

[0024] 2. Gas storage model; 21. Pressure cylinder; 211. Pressure chamber; 212. Mounting base; 2121. Sealing seat; 2122. Pressure channel; 2123. Pressure valve; 213. Cover; 22. Salt brick; 221. Melting chamber; 23. Slide table;

[0025] 3. Test components; 31. Pump body; 32. Inner sleeve; 321. First interface; 33. Outer sleeve; 331. Second interface; 34. Pressure module; 341. Hydraulic cylinder; 342. Constant flow pump; 343. Flow meter;

[0026] 4. Water tank; 41. Valve. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0028] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0030] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0031] Reference Figure 1 and Figure 2 As shown in the embodiment of this application, a water-soluble cavity simulation test device for a deep saline gas storage facility includes a test bench 1, a gas storage model 2, test components 3, and a water tank 4. The test bench 1 is provided with a frame 11, a control panel 12, and a test cavity 13 from top to bottom. Guide rails are provided on the frame 11, and a control mechanism is integrated within the control panel 12. In this embodiment, the control mechanism can be a centralized or distributed controller. For example, the controller can be a single microcontroller or composed of multiple distributed microcontrollers. The microcontroller can run a control program to control the subsequent electrical modules to achieve their functions.

[0032] The gas chamber model 2 includes a transparent pressure cylinder 21 and a salt brick 22. The pressure cylinder 21 is located inside the test chamber 13 and has a pressure chamber 211. The salt brick 22 is detachably fixed inside the pressure chamber 211. The salt brick 22 is cuboid in shape, and a transparent plate is fixed to one side wall of the salt brick 22 with glue. The transparent plate and the corresponding side wall of the salt brick 22 have the same shape and size. A blind hole is opened on the top surface of the salt brick 22. Along the radial direction of the blind hole, the minimum distance between the center line of the blind hole and the transparent plate is less than the radius of the blind hole, that is, part of the side wall of the blind hole is composed of a transparent plate. The cross-section of the blind hole is an ellipse with one side being a straight line. It should be noted that the salt brick 22 adopts a half-structure design, that is, the salt brick 22 only simulates half of the structure of the gas storage tank in actual working conditions. The salt brick 22 can be regarded as a salt rock model obtained by cutting the gas storage tank in half and scaling it down proportionally. The symmetrical surface of the salt brick 22 corresponding to the symmetrical cutting of the gas storage tank is covered by a transparent plate and sealed with epoxy resin. In this embodiment, the transparent plate is an acrylic component.

[0033] Test assembly 3 includes a pump body 31, an inner sleeve 32, an outer sleeve 33, and a pressure module 34. The inner sleeve 32 and the outer sleeve 33 are slidably connected to the frame 11 in the vertical direction. Specifically, both the outer sleeve 33 and the inner sleeve 32 are fitted with sliders, which are slidably connected to slide rails on the frame 11. The frame 11 is also equipped with a linear module that drives the two sliders to move. The inner sleeve 32 and the outer sleeve 33 are coaxially arranged and pass through the outer sleeve 33. The top of the outer sleeve 33 is provided with a first rubber plug, and resin is filled between the first rubber plug and the inner wall of the outer sleeve 33. The inner sleeve 32 is fitted into the first rubber plug to achieve a sliding connection between the outer sleeve 33 and the inner sleeve 32, i.e., a top seal on the outer sleeve 33. The outer sleeve 33 is sealed to the salt brick 22 and abuts against the transparent plate. Specifically, a second rubber plug is provided at the top of the blind hole, and the outer sleeve 33 passes through the second rubber plug. After the outer sleeve 33 passes through the second rubber plug, it is cemented with epoxy resin to ensure the sealing and stability of the blind hole and prevent leakage or structural failure during the experiment. The bottom ends of both the outer sleeve 33 and the inner sleeve 32 are open and located inside the blind hole. The bottom of the inner sleeve 32 is lower than the bottom of the outer sleeve 33 and there is a gap between it and the bottom wall of the blind hole. Salt powder is filled between the inner sleeve 32 and the bottom wall of the blind hole to simulate the heterogeneity and interlayer distribution of the salt layer. After filling with salt powder, epoxy resin AB glue is evenly applied to the side wall of the salt brick 22 through which the blind hole is connected, and a transparent plate is placed on top of the glue to ensure the sealing of the subsequently formed solution cavity 221 and the visualization observation function. The pressure module 34 is electrically connected to the control panel 12. The pressure module 34 is connected to the inner sleeve 32 and the pressure cavity 211 to control the pressure inside and outside the salt brick 22. The output end of the pump body 31 is connected to the inner sleeve 32. In this embodiment, the pump body 31 is selected as a peristaltic pump with high reliability, good sealing performance and high control precision.

[0034] Water tank 4 is installed in test chamber 13 and has two inner cavities. One inner cavity is selectively connected to one of the inner sleeve 32 and outer sleeve 33 via pump body 31, and the other inner cavity is connected to the other of the inner sleeve 32 and outer sleeve 33. Valves 41 are provided on the side walls of both inner cavities. Specifically, one inner cavity is filled with test water, which is usually set as salt water containing a certain amount of salt. At the start of the experiment, the user can connect the inner cavity containing test water to the input end of the pump body 31, connect the output end of the pump body 31 to the inner sleeve 32, and connect the other inner cavity to the outer sleeve 33, thus achieving positive circulation cavity building with water injection into the inner sleeve 32 and brine discharge into the outer sleeve 33. After positive circulation cavity building for a certain period of time, the user can then connect the output end of the pump body 31 to the outer sleeve 33 and the other inner cavity to the inner sleeve 32, thus achieving reverse circulation cavity building with water injection into the outer sleeve 33 and brine discharge into the inner sleeve 32. The user can then switch the water injection and brine discharge ports according to the experimental design and continue the cavity building operation to simulate the influence of different water injection modes on the morphology of the solution cavity 221. In addition, during the early water injection, the user can also simultaneously introduce a certain amount of protective gas (inert gas). The protective gas moves upward under the compression of the solution cavity 221 and eventually forms a protective layer above the solution cavity 221, thereby limiting the degree of dissolution in the solution cavity 221 and further improving the structural stability of the solution cavity 221.

[0035] Understandably, before using the test device, salt brick 22 is prepared, and blind holes are drilled on the salt brick 22 to simulate the drilling position and drilling route of the actual working conditions. After inserting the outer sleeve 33 into the blind hole, the outer sleeve 33 is fixed (corresponding to cementing under the actual working conditions). Then, salt powder is filled under the unsealed outer sleeve 33, and after attaching the transparent plate, the salt brick 22 is fixedly installed in the pressure chamber 211. At the same time, the inner sleeve 32 is installed and the outer sleeve 33 is installed on the frame 11 to realize the installation of salt brick 22.

[0036] When using the experimental apparatus, the pressure module 34 and pump 31 are activated. The pressure module 34 injects high pressure into the dissolution cavity 221 inside the salt brick 22 and the pressure cavity 211 outside the salt brick 22. Simultaneously, under the action of the pump 31, one of the inner sleeve 32 and the outer sleeve 33 injects water towards the location where the salt powder is filled, forming the dissolution cavity 221. The other sleeve discharges excess brine from the dissolution cavity 221, causing the dissolution cavity 221 to expand regularly and stably. At this time, the user can observe and record the morphological changes of the dissolution cavity 221 through the transparent pressure cylinder 21 and the transparent plate. Afterwards, the user can adjust parameters such as the distance between the pipe openings of the inner sleeve 32 and the outer sleeve 33, the water flow rate, and the water injection time to study the influence of different parameters on the expansion law of the dissolution cavity 221. It should be noted that the user can either observe and record the morphological changes of the dissolution cavity 221 by manually drawing a scheme with the naked eye, or set up a high-definition camera system to capture the morphological changes of the dissolution cavity 221 with a time delay.

[0037] By setting up salt bricks 22 filled with salt powder to simulate a gas storage tank, users can simulate the heterogeneous characteristics of different gas storage tanks, such as salt layer thickness, salt rock purity, and interlayer distribution, by setting salt bricks 22 of different specifications and filling them with different types and qualities of salt powder. This allows for the study of their impact on the cavity morphology and improves the simulation accuracy of the salt bricks 22. By setting up experimental component 3, the pressure module 34 of experimental component 3 can precisely control the internal and external pressures of the salt bricks 22, realistically simulating the high-pressure environment of deep salt layers and improving the fit between experimental results and actual conditions. The inner sleeve 32 and the outer sleeve 33 work together to realize water injection and brine drainage for cavity creation, and the injection and drainage ports can be exchanged, realistically reproducing the water-soluble cavity creation process under high-pressure conditions in deep salt layers, ensuring the structural stability of the cavity 221. The gas storage model 2 and the experimental component 3 work together to simulate the water-soluble cavity-building process of deep saline gas storage facilities with high precision. Based on this, by precisely controlling parameters such as pipe outlet distance, water injection flow rate, and water injection time, the device can efficiently simulate the morphological evolution of cavity 221 under different cavity-building conditions and ensure the stability of cavity 221, providing reliable technical support for the design, construction, and safe operation of deep saline gas storage facilities. Through the above experimental device, users can conduct multiple sets of comparative experiments to verify the cavity expansion effect under different water injection times, providing a scientific basis for practical engineering. Furthermore, considering the characteristics of deep, thin saline layers, the device can improve the control precision of saline layer utilization, cavity-building rate, and cavity morphology by optimizing cavity-building parameters, significantly shortening the cavity-building cycle and reducing energy consumption, providing technical support for the efficient construction of deep saline gas storage facilities.

[0038] Furthermore, the top sidewall of the inner sleeve 32 is provided with a first interface 321, and the top sidewall of the outer sleeve 33 is provided with a second interface 331. Both the first interface 321 and the second interface 331 are detachably connected to the water tank 4. The first interface 321 and the second interface 331 are the same shape and equal in size. In this embodiment, both the inner sleeve 32 and the outer sleeve 33 are made of stainless steel or copper pipes coated with a corrosion-resistant coating. The first interface 321 is an external thread pagoda connector integrally formed with the inner sleeve 32, and the second interface 331 is an external thread pagoda connector integrally formed with the inner sleeve 32.

[0039] By setting the same first interface 321 and second interface 331, not only can the inner sleeve 32 and the outer sleeve 33 be quickly assembled and used, but the interchangeability of the first interface 321 and the second interface 331 can also be improved, making it convenient for users to quickly switch the water inlet and the brine outlet, and improving the ease of installation and removal of the inner sleeve 32 and the outer sleeve 33.

[0040] It should be added that, in some embodiments, the outer walls of the inner sleeve 32 and the outer sleeve 33 are provided with protruding handles, which allow users to manually adjust the height of the inner sleeve 32 and the distance between the pipe openings in the event of a failure of the linear module, thereby improving the fault tolerance of the test device.

[0041] Reference Figure 1 As shown, it can be understood that the pressure cylinder 21 includes a mounting base 212 and a cover 213. The cover 213 is composed of five transparent acrylic plates. The cover 213 can be sealed to the mounting base 212 to form a pressure chamber 211. The top surface of the mounting base 212 and the inner top surface of the cover 213 are both provided with sealing seats 2121. After the cover 213 and the mounting base 212 are connected, the two sealing seats 2121 are arranged opposite to each other to position the salt brick 22 in the vertical direction.

[0042] By incorporating a detachable mounting base 212 and a cover 213, and a modular design for the pressure cylinder 21, along with the cooperation of the sealing seats 2121 within the mounting base 212 and cover 213, the salt brick 22 can be quickly positioned and installed. Users can design and prepare different salt bricks 22 to simulate different gas storage chambers, facilitating rapid assembly and reuse of the experimental device, reducing experimental costs, and improving research efficiency. Furthermore, in addition to the pressure cylinder 21, the frame 11, pressure module 34, and other components also adopt a modular design, thereby facilitating the inspection, maintenance, and replacement of the inner sleeve 32, outer sleeve 33, and pressure module 34, further reducing experimental costs and improving research efficiency.

[0043] Furthermore, the pressure module 34 includes a hydraulic cylinder 341 and a constant flow pump 342. The hydraulic cylinder 341 is installed inside the test chamber 13, and the constant flow pump 342 is installed on the top of the control panel 12. The mounting base 212 is provided with a pressure channel 2122. The hydraulic cylinder 341 is sealed to the mounting base 212 and communicates with the pressure chamber 211 through the pressure channel 2122. A pressure-bearing valve 2123 is provided in the pressure channel 2122. The constant flow pump 342 is installed on the test bench 1 and communicates with the inner sleeve 32. In some embodiments, a flow meter 343 is also provided on the pipe between the constant flow pump 342 and the inner sleeve 32.

[0044] By setting up a constant flow pump 342 and a hydraulic cylinder 341, the constant flow pump 342 can pressurize the melting cavity 221 during the positive circulation cavity formation of the salt brick 22, simulating the internal pressure of the gas storage tank under actual working conditions. The hydraulic pump can pressurize the pressure cavity 211 between the outer wall of the salt brick 22 and the inner wall of the pressure cylinder 21, simulating the external pressure of the gas storage tank under actual working conditions. The constant flow pump 342 has a stable flow rate and is easy to adjust, which can further improve the structural stability of the melting cavity 221. In addition, the hydraulic cylinder 341, water tank 4 and other components are all built into the test chamber 13, which can effectively improve the portability and aesthetics of the test device.

[0045] Furthermore, the gas chamber model 2 also includes a slide 23, with a wheel assembly at its bottom. The pressure cylinder 21 is detachably connected to the slide 23. Correspondingly, a clamping component is provided inside the test chamber 13. When the wheel assembly at the bottom of the slide 23 moves to a preset position, the clamping component can clamp and lock the wheel assembly, thereby fixing the slide 23, i.e., the pressure cylinder 21, and ensuring accurate alignment between the outer sleeve 33 and the guide rail.

[0046] By setting up the slide table 23, the user can install the salt brick 22 and build the pressure cylinder 21 outside the test chamber 13, and then slide the slide table 23 to install and fix the pressure cylinder 21 into the pressure chamber 211, which further improves the ease of loading and unloading the salt brick 22 and the ease of use of the test device.

[0047] Reference Figure 2 As shown, it can be understood that the test chamber 13 is equipped with an illumination element 132, which is electrically connected to the control panel 12. Optionally, the illumination element 132 may be an LED tube or light panel disposed on the top surface of the test chamber 13, or it may be a light bead installed on the inner side wall of the test chamber 13, etc., which will not be described in detail here.

[0048] By setting up the lighting element 132, a stable and bright lighting environment can be provided, which is more conducive to the morphological monitoring of the cavity 221. When the light is dim, the lighting element 132 is turned on, and the high-definition camera system can record the morphological changes of the cavity 221 normally through the transparent pressure cylinder 21, ensuring that the test device can operate stably for a long time, improving the continuity of the test, and improving the observability of the cavity 221.

[0049] Furthermore, the test assembly 3 also includes two Baumé concentration meters, one installed at the first interface 321 and the other at the second interface 331. The test bench 1 is equipped with two cameras, each facing one of the two Baumé concentration meters and electrically connected to the control panel 12. It should be noted that the connections between the first interface 321 and the water tank 4, and between the second interface 331 and the water tank 4, are designed with drip-proofing to ensure that the test saline solution in the first interface 321 and the brine in the second interface 331 (the brine in the first interface 321 and the test saline solution in the second interface 331) drips onto the corresponding Baumé concentration meters at regular intervals and in measured quantities, guaranteeing the normal operation of the Baumé concentration meters.

[0050] To ensure stable molding of the solution cavity 221, the test water injected into the salt brick 22 is typically a brine solution with a certain salt content, and the brine concentration within the cavity may increase sequentially from top to bottom. By setting up Baumé concentration meters, with the Baumé concentration meters at the first interface 321 and the second interface 331 working in conjunction, the concentration of water injected into the salt brick 22 and the concentration of brine produced can be detected. This facilitates users in detecting and recording the impact of the water injection concentration and the brine production concentration on the molding of the solution cavity 221, and improves the comprehensiveness of the test data.

[0051] In some embodiments, the test assembly 3 further includes a laser probe, which is electrically connected to the control panel 12 via a wire. The laser probe is located within a blind hole and within the solution cavity 221 formed by the dissolution of salt powder. The wire passes through the inner sleeve 32 and is sealed to the first interface 321. Optionally, the side wall of the inner sleeve 32 has an opening for the wire to pass through, and the wire can be sealed to the opening using components such as silicone or a sealing connector.

[0052] A laser probe inserted into the cavity 221 is used to scan and model the overall morphology of the cavity 221, further improving the accuracy of the testing device in studying the morphological changes of the cavity 221 and enhancing the comprehensiveness of the experimental data. The first interface 321 is concealed within a tubular sleeve to store the wires, preventing wire exposure and reducing the risk of aging and leakage.

[0053] Understandably, the control panel 12 is also equipped with a display 121, and the linear module connected to the outer sleeve 33 and the inner sleeve 32 is equipped with a displacement sensor. Both the outer sleeve 33 and the inner sleeve 32 are equipped with flow sensors, and both the flow sensors and the displacement sensors are communicatively connected to the control panel 12.

[0054] By setting up the display 121, the display 121 can display parameters such as the shape of the cavity 221 captured by the high-definition camera system, the internal shape of the cavity 221 scanned by the laser probe, the water injection concentration / brine discharge concentration captured by the camera (detected by the Baumé concentration meter), the water injection flow rate detected by the flow sensor, and the water injection time, which can effectively improve the user experience.

[0055] Reference Figure 3 As shown, a water-soluble cavity simulation test method for a deep saline gas storage tank according to an embodiment of this application includes the following steps:

[0056] S100, build a test device and install salt bricks 22 according to the actual salt layer depth and thickness of the gas storage tank, so that both the inner sleeve 32 and the outer sleeve 33 extend into the salt bricks 22;

[0057] The depth and thickness of the salt layer in the actual gas storage facility directly affect its size and external high pressure. Users can design salt bricks 22 of corresponding dimensions based on the actual salt layer depth and thickness, and prepare pressure modules 34 that meet pressure standards. Then, the following steps are performed sequentially: preparing salt bricks 22, installing salt bricks 22, fixing the pressure cylinder 21, assembling the inner sleeve 32 and outer sleeve 33, connecting the pressure module 34, and connecting the pump body 31 and water tank 4. This completes the construction of the test device, ensuring that the inner sleeve 32 extends into the salt bricks 22 and directly contacts the salt powder. This ensures that the gas storage model 2 simulated by the salt bricks 22 matches the geometric proportions and physical characteristics of the actual gas storage facility.

[0058] S200, determine the test scale based on the geometric ratio between salt brick 22 and the actual gas storage tank, and set the test parameters based on the test scale and the cavity-making parameters of the actual gas storage tank;

[0059] For the simulation test of water-soluble cavity construction in deep salt layer gas storage, since the size of the salt brick 22 in the test device is much smaller than the size of the on-site gas storage, it is necessary to adjust other parameters during the test, including water injection volume, tubing size, pipe spacing, and dissolution time, to meet the requirements of similarity theory. In this application, dimensional analysis is used for analysis and adjustment. According to the technical characteristics of water-soluble cavity construction, the parameters affecting salt rock water-soluble cavity construction include: geometric dimensions l, dissolution time t, dissolution rate ω, water injection flow rate q, brine concentration c, temperature T, and salt rock density ρ. The dimensions of each parameter are shown in Table 1.

[0060] Table 1 Parameter Dimension Table

[0061]

[0062]

[0063] There are four fundamental dimensions (L, M, T, θ), where the fundamental dimension r = 4, L is the dimension of length, M is the dimension of mass, T is the dimension of time, and θ is the dimension of temperature. According to the second similarity theorem, this system has three similarity criteria. Let l[L], t[T], and ω[ML] be selected. -2 T -1 If C[θ] and C[θ] are fundamental physical quantities, then the other three physical quantities can be expressed using fundamental physical quantities. If the physical quantity to be determined in this experiment is the water injection flow rate, it can be expressed as:

[0064] q = l α t β ω λ T γ (1)

[0065] By the principle of homogeneity of dimensions in equations, we have α = 3, β = -1, λ = 0, γ = 0. Therefore, the π terms related to q are:

[0066]

[0067] Similarly:

[0068]

[0069] When the similarity ratio of the parameters is represented by K, the geometric similarity ratio can be expressed as:

[0070]

[0071] Among them l p Indicates the prototype size, lm This represents the model dimensions. The similarity ratios of other parameters are similar, so the relationship between the similarity ratios of the parameters in equations (1) and (3) can be expressed as:

[0072]

[0073] In this embodiment, if the actual salt chamber diameter is 60m, and the inner diameter of the inner sleeve 32 in the experimental device is 30cm, i.e., the scale ratio is 1:200, then the three terms in the above formula can be understood as follows:

[0074] i) The ratio of flow rate to time, i.e., the ratio of total injection volume to total on-site injection volume, is the cube of the length ratio, which is 1 / 200 of the on-site volume. 3 .

[0075] ii) Since the density and dissolution rate of the salt rock (i.e., salt bricks) in the field and the experimental setup are the same, the time is 1 / 200 of the field dissolution time. If the field dissolution time is 600 days, then the laboratory time should be 3 days. Furthermore, combining this with the conclusion in (i), the injection flow rate should be 1 / 200 of the field flow rate. 2 If the site is 60m 3 If the value is / h, then the laboratory temperature should be 0.0015m. 3 / h, which is 25mL / min.

[0076] iii) The concentration and on-site scale ratio is 1:1.

[0077] Based on the above analysis, it can be seen that as long as the geometric ratio between the salt brick 22 in the test device and the actual gas storage tank is known, the test parameters such as the required water injection flow rate in the test device can be calculated based on the cavity-making parameters of the actual gas storage tank, and the simulation degree of the test device can be ensured.

[0078] S300, according to the test parameters, water is poured into the salt brick 22 to form a solution cavity 221;

[0079] In this embodiment, at the start of the experiment, the inner cavity containing test water is connected to the input end of the pump body 31, the output end of the pump body 31 is connected to the inner sleeve 32, and the other inner cavity is connected to the outer sleeve 33, thereby realizing positive circulation cavity building with water injection into the inner sleeve 32 and brine discharge into the outer sleeve 33. After positive circulation cavity building for a certain period of time, the output end of the pump body 31 is connected to the outer sleeve 33, and the other inner cavity is connected to the inner sleeve 32, thereby realizing reverse circulation cavity building with water injection into the outer sleeve 33 and brine discharge into the inner sleeve 32. According to the experimental design, the water injection and brine discharge ports are exchanged, and the cavity building operation continues to simulate the influence of different water injection modes on the morphology of the solution cavity 221.

[0080] S400 allows for the adjustment of water injection flow rate, water injection time, and the distance between the bottom openings of the inner sleeve 32 and the outer sleeve 33, while also recording the morphological changes of the melting cavity 221 in real time.

[0081] The experimental setup allows for the study of the influence of key parameters such as pipe distance, water injection flow rate, and alternating water injection and brine discharge methods on the cavity expansion pattern. The specific effects of these parameters and the optimization process are as follows:

[0082] (a) The effect of the distance between the two nozzles on cavity expansion

[0083] The distance between the two pipe openings determines the distribution range and flow characteristics of freshwater in salt rock. When the distance between the two openings is small, the flow area of ​​freshwater is relatively concentrated, and the cavity expands faster, but the overall shape of the cavity may be relatively narrow, making it difficult to form an ideal large-sized cavity. When the distance between the two openings is large, the flow area of ​​freshwater is more dispersed, and the expansion speed of the cavity may be slower, but the shape of the cavity is more uniform, which is conducive to the formation of a regular cavity structure.

[0084] Optimized design of the distance between the two pipe openings

[0085] To investigate the effect of the distance between the two nozzles on cavity expansion, this experimental setup allows for simulation of the cavity-building process at different distances by adjusting the positions of the outer sleeve 33 and the inner sleeve 32. The experiment allows observation of the cavity's morphological evolution under different nozzle distances, thus optimizing the design of the nozzle distance to meet both the cavity expansion speed requirements and the regularity and stability of the cavity's morphology.

[0086] Experimental verification and application

[0087] In practical applications, the optimized design of the distance between the two pipe openings needs to comprehensively consider factors such as the thickness of the salt layer, the purity of the salt rock, and the economics of the project. This experimental setup allows for multiple comparative experiments to verify the cavity expansion effect under different pipe opening distances, providing a scientific basis for practical engineering.

[0088] (b) Water injection time

[0089] The injection time is another important parameter affecting the cavity morphology and brine concentration during pressurized water-soluble cavity construction in deep saline layers. The injection time directly determines the amount of fresh water injected, the amount of brine discharged, and the extent of cavity expansion.

[0090] The effect of water injection time on cavity expansion

[0091] The longer the injection time, the greater the amount of fresh water injected, and the larger the expansion range of the cavity. However, excessively long injection times may lead to over-expansion of the cavity, resulting in irregular shapes and even instability of the salt layer structure. On the other hand, insufficient injection time may result in inadequate cavity expansion, making it difficult to meet the design capacity requirements.

[0092] Optimization design of water injection time

[0093] To investigate the effect of water injection time on cavity expansion, this experimental setup allows for adjustment of the water injection time by controlling the operating time of the water pump. Experiments allow observation of the cavity's morphological evolution under different water injection times, thus optimizing the water injection time design to both meet the cavity expansion requirements and avoid problems caused by over-expansion.

[0094] Experimental verification and application

[0095] In practical applications, the optimized design of water injection time needs to comprehensively consider factors such as the dissolution rate of the salt layer, the discharge efficiency of the brine, and the economics of the project. This experimental device allows for multiple comparative experiments to verify the cavity expansion effect under different water injection times, providing a scientific basis for practical engineering.

[0096] (c) Water injection flow rate

[0097] The water injection flow rate is one of the key parameters affecting the cavity expansion rate and brine concentration during pressurized water-soluble cavity construction in deep saline aquifers. The magnitude of the water injection flow rate directly determines the freshwater injection rate, the brine discharge rate, and the cavity expansion efficiency.

[0098] The effect of water injection flow rate on cavity expansion

[0099] A larger water injection flow rate can accelerate the injection of fresh water, improve the expansion efficiency of the cavity, and shorten the cavity construction time. However, an excessively large water injection flow rate may result in too low a brine concentration, reducing the utilization value of brine for salt chemical enterprises, and may also lead to irregular cavity shapes, affecting the operational safety of the gas storage facility. On the other hand, a smaller water injection flow rate may result in too slow a cavity expansion speed, making it difficult to meet the requirements of the project schedule.

[0100] Optimized design of water injection flow rate

[0101] To investigate the effect of water injection flow rate on cavity expansion, this experimental setup allows for control of the water injection flow rate by adjusting the water pump flow rate. Experiments allow observation of the cavity morphological evolution under different water injection flow rates, thereby optimizing the water injection flow rate design to meet both the cavity expansion speed requirements and ensure the rationality of brine concentration and cavity morphology.

[0102] Experimental verification and application

[0103] In practical applications, the optimized design of the water injection flow rate needs to comprehensively consider factors such as the dissolution characteristics of the salt layer, the discharge efficiency of the brine, and the economics of the project. This experimental setup allows for multiple comparative experiments to verify the cavity expansion effect under different water injection flow rates, providing a scientific basis for practical engineering.

[0104] Comprehensive optimization design

[0105] In practical engineering, there is an interrelationship among the distance between the two pipe openings of the outer sleeve 33 and the inner sleeve 32, the water injection time, and the water injection flow rate. Changes in the distance between the two pipe openings affect the flow path of fresh water and the discharge efficiency of brine, thus affecting the optimal design of the water injection time and flow rate. The duration of water injection and the magnitude of the water injection flow rate directly affect the expansion speed and shape of the cavity.

[0106] (d) Comprehensive optimization design

[0107] By comprehensively considering three parameters—the distance between the two pipe openings, the water injection time, and the water injection flow rate—a more scientific and reasonable cavity-building scheme can be formulated, which can improve cavity-building efficiency while ensuring the regularity and stability of the cavity shape. This experimental device allows for the study of the cavity expansion effect under different combinations of the two pipe opening distances, water injection time, and water injection flow rates through multiple sets of comparative experiments. By analyzing the experimental results, the optimal combination of cavity-building parameters can be determined, providing a scientific basis and technical support for practical engineering.

[0108] Understandably, the design of salt brick 22 and the experimental device based on similarity theory ensures that the experimental device can accurately simulate the pressurized water-soluble cavity-building process in deep salt cavern gas storage under actual working conditions. By comprehensively considering three parameters—the distance between the two pipe openings, the water injection time, and the water injection flow rate—a more scientific and reasonable cavity-building scheme can be formulated, which can improve cavity-building efficiency and ensure the regularity and stability of the cavity 221 morphology. Furthermore, the experimental method implemented using the aforementioned experimental device verifies the accuracy of the mathematical control equations and the cavity-building model through physical model experiments, providing a scientific basis for the formulation of single-well cavity-building technology schemes for deep salt cavern gas storage. The experimental data can improve and refine existing mathematical models, enhance their predictive accuracy, and provide more precise guidance for practical engineering.

[0109] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A water-soluble cavity simulation test device for deep saline gas storage, characterized in that, include: The test bench (1) is provided with a frame (11), a control panel (12) and a test chamber (13) from top to bottom; The gas storage model (2) includes a transparent pressure cylinder (21) and a salt brick (22). The pressure cylinder (21) is located in the test chamber (13) and has a pressure chamber (211). The salt brick (22) is fixed in the pressure chamber (211). The salt brick (22) is rectangular. A transparent plate is fixed to one side wall of the salt brick (22). A blind hole is opened on the top surface of the salt brick (22). The blind hole is filled with salt powder. Along the radial direction of the blind hole, the minimum distance between the center line of the blind hole and the transparent plate is less than the radius of the blind hole. The test assembly (3) includes a pump body (31), an inner sleeve (32), an outer sleeve (33), and a pressure module (34). The inner sleeve (32) and the outer sleeve (33) are slidably connected to the frame (11) in the vertical direction. The inner sleeve (32) and the outer sleeve (33) are coaxially arranged and pass through the outer sleeve (33). The outer sleeve (33) is sealed to the salt brick (22) and abuts against the transparent plate. The bottom end of the outer sleeve (33) and the bottom end of the inner sleeve (32) are both open and located in the blind hole. The pressure module (34) is electrically connected to the control panel (12). The pressure module (34) is connected to the inner sleeve (32) and the pressure chamber (211) to control the pressure inside and outside the salt brick (22). A water tank (4) is installed in the test chamber (13) and has two inner cavities. One of the inner cavities is selectively connected to one of the inner sleeve (32) and the outer sleeve (33) through the pump body (31), and the other inner cavity is connected to the other of the inner sleeve (32) and the outer sleeve (33).

2. The deep saline gas storage water-soluble cavity simulation test device according to claim 1, characterized in that, The pressure cylinder (21) includes a mounting base (212) and a cover (213). The cover (213) can be sealed to the mounting base (212) to form the pressure chamber (211). Both the mounting base (212) and the cover (213) are provided with sealing seats (2121). The two sealing seats (2121) are arranged opposite to each other to position the salt brick (22) in the vertical direction.

3. The deep saline gas storage water-soluble cavity simulation test device according to claim 2, characterized in that, The pressure module (34) includes a hydraulic cylinder (341) and a constant flow pump (342). The mounting base (212) is provided with a pressure channel (2122). The hydraulic cylinder (341) is connected to the pressure chamber (211) through the pressure channel (2122). The constant flow pump (342) is installed on the test bench (1) and is connected to the inner sleeve (32).

4. The deep saline gas storage water-soluble cavity simulation test device according to claim 1 or 2, characterized in that, The gas storage model (2) also includes a slide (23), the bottom of which is provided with a wheel set, and the pressure cylinder (21) is detachably connected to the slide (23).

5. The deep saline gas storage water-soluble cavity simulation test device according to claim 1, characterized in that, The inner sleeve (32) has a first interface (321) on its top side wall, and the outer sleeve (33) has a second interface (331) on its top side wall. Both the first interface (321) and the second interface (331) are detachably connected to the water tank (4). The first interface (321) and the second interface (331) are the same shape and the same size.

6. The deep saline gas storage water-soluble cavity simulation test device according to claim 5, characterized in that, The test assembly (3) also includes a laser probe, which is electrically connected to the control panel (12) via a wire. The laser probe is located inside the blind hole, and the wire passes through the inner sleeve (32) and is sealed to the first interface (321).

7. The deep saline gas storage water-soluble cavity simulation test device according to claim 5, characterized in that, The test assembly (3) also includes two Baumé concentration meters, one of which is installed at the first interface (321) and the other is installed at the second interface (331). The test bench (1) is equipped with two cameras, which are respectively positioned facing the two Baumé concentration meters and are electrically connected to the control panel (12).

8. The deep saline gas storage water-soluble cavity simulation test device according to claim 1, characterized in that, The test chamber (13) is equipped with a lighting element (132).

9. The deep saline gas storage water-soluble cavity simulation test device according to claim 1, characterized in that, The control panel (12) is also equipped with a display (121).

10. A method for simulating water-soluble cavity construction in deep saline gas storage, implemented using the water-soluble cavity construction simulation test apparatus for deep saline gas storage as described in any one of claims 1-9, characterized in that, Includes the following steps: The test device was built according to the actual salt layer depth and thickness of the gas storage tank and the salt brick (22) was installed so that the inner sleeve (32) and the outer sleeve (33) both extended into the salt brick (22); The test scale is determined based on the geometric ratio between the salt brick (22) and the actual gas storage tank, and the test parameters are set based on the test scale and the cavity-making parameters of the actual gas storage tank. According to the test parameters, water is injected into the salt brick (22) to drain the brine and form a solution cavity (221); Adjust the water injection flow rate, water injection time, and the distance between the bottom openings of the inner sleeve (32) and the outer sleeve (33) respectively, and record the morphological changes of the melting cavity (221) in real time.

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