Physical visualization system for simulating construction of single-well retreating type horizontal salt cavern

Abstract

The invention discloses a physical visualization system for single-well retreating type horizontal salt cavern simulation construction. The physical visualization system comprises a salt rock entity model, an embedded shaft module, a casing retreating control module, a constant-flow water injection and brine discharge and salt rock segmented corrosion cavity forming module and a visual observation and imaging module. The embedded shaft module is embedded into the salt rock entity model; the casing retreating control module is connected with a water injection casing in the embedded shaft module; the constant-flow water injection and brine discharge and salt rock segmented corrosion cavity forming module is used for injecting fresh water, performing water-soluble salt rock cavity forming operation on the salt rock entity model and discharging brine formed by dissolving salt rock in the fresh water outwards; and the visual monitoring and imaging module is connected with the sleeve retreating control module. According to the method, the salt cavern building process of the SWRH salt cavern building method can be simulated, key process parameters during salt cavern building can be determined and verified, and the problems that a traditional SWRH salt cavern building method is long in construction parameter optimization period, low in salt cavern form prediction precision and the like are solved.

Description

Technical Field

[0001] This invention relates to the fields of hydrogen energy emerging energy engineering construction, energy geology engineering and underground hydrogen storage salt cavern construction technology, and in particular to a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, which can be applied to the construction design and safety research of hydrogen storage salt caverns. Background Technology

[0002] With the rapid development of large-scale hydrogen energy systems, deep salt caverns are widely regarded as ideal underground hydrogen storage spaces that combine economy and safety due to their excellent sealing performance, damage self-healing ability, and controllable dissolution characteristics.

[0003] However, hydrogen molecules are extremely small and have strong diffusion capabilities, making them more sensitive to the smoothness of the salt cavern's shape, the sealing of the surrounding rock, and local stress concentration. The soluble and corrosive properties of salt rock allow for the construction of salt caverns using water injection dissolution techniques and by rationally controlling the cavity's shape and size. However, in actual engineering projects, significant differences exist in salt layer burial depth, bedding structure, impurity content, and dissolution rates among salt rocks of different compositions, resulting in significant uncertainty in the final salt cavern's morphology.

[0004] Traditional salt cavern construction methods mainly include the single-well vertical method (SWV), the two-well horizontal method (TWH), and the two-well retreat method (TWRH). Among these, the SWV method is widely used in salt dome structures, but in layered salt rocks, the presence of interlayers and their high permeability often lead to irregular cavern shapes and uneven tops and bottoms, severely affecting the long-term operational stability of hydrogen storage facilities. While the TWH and TWRH methods can improve the shape of salt caverns, they require drilling two wells, resulting in high construction costs and a significant risk of leakage.

[0005] In recent years, the single-well retreating horizontal (SWRH) salt cavern construction method has achieved plasticity in salt cavern morphology through segmented retreating water injection and erosion of a single well, offering significant advantages in reducing the number of wells and improving cavity efficiency. SWRH salt cavern construction technology uses directional drilling and segmented retreating cavity technology to form horizontally extending salt caverns (horizontal section length 100-300m, diameter 3-8m) in salt layers, improving space utilization by 15-20% and reducing construction costs by 30% compared to vertical salt caverns. However, currently, for the single-well retreating horizontal (SWRH) salt cavern construction method, there is a lack of scientifically effective verification schemes for determining key process parameters during salt cavern construction, resulting in problems such as long optimization cycles for construction parameters and low accuracy in predicting salt cavern morphology.

[0006] Key process parameters include: freshwater injection flow rate, brine discharge flow rate and concentration, dissolution time, and injection casing retraction step length. Detailed explanations are as follows: 1. Freshwater injection flow rate (m³) 3 / h): This represents the amount of freshwater entering the salt layer per unit time. It determines the renewal rate of the salt rock dissolution interface, controls the volume expansion rate of the salt rock cavity, and affects the uniformity of dissolution and the cavity morphology.

[0007] 2. Brine discharge flow rate (m³) 3 / h) and concentration ( c : represents the rate of brine discharge and the concentration of brine (i.e., salt water) in the salt rock cavity, respectively. The concentration of brine determines the driving force of salt rock dissolution; the lower the brine concentration, the faster the dissolution.

[0008] 3. Dissolution time (t): Represents the duration of each cavity formation. Controls the rate of volume growth of the salt rock cavity.

[0009] 4. Water injection casing retraction step length (ΔL): This represents the distance the water injection casing moves within the salt layer. It controls the geometric characteristics of the salt rock cavity. If the retraction step length is too small, the salt rock cavity will be excessively dissolved locally. If the retraction step length is too large, the shape of the salt rock cavity will be discontinuous, and stress concentration will easily occur.

[0010] Therefore, there is an urgent need to develop a technology that can solve the above-mentioned technical problems. Summary of the Invention

[0011] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern.

[0012] To this end, the present invention provides a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, which includes a salt rock solid model, an embedded wellbore module, a casing retreating control module, a constant flow water injection and brine discharge and salt rock segmented dissolution cavity formation module, as well as a visualization observation and imaging module. Embedded wellbore module, embedded in the salt rock solid model; The casing retraction control module is connected to the water injection casing in the embedded well module and is used to drive the water injection casing to move to the right in the horizontal direction within the prefabricated channel of the salt rock solid model. The constant flow water injection and brine drainage and salt rock segmented dissolution cavity-forming module is used to perform water-dissolving salt rock cavity-forming operation on the salt rock solid model by injecting fresh water into the salt rock solid model, forming a hollow salt cavern inside the salt rock solid model, and after the salt cavern is formed, injecting fresh water into the salt cavern inside the salt rock solid model to drain the brine formed by the fresh water dissolving salt rock during the water-dissolving salt rock cavity-forming operation. The visualization monitoring and imaging module is connected to the casing retraction control module to monitor the formation process of salt caverns within the salt rock entity model and to feed back the monitoring results to the casing retraction control module.

[0013] As can be seen from the technical solution provided by the present invention above, compared with the prior art, the present invention provides a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern. The system is scientifically designed and can simulate the process of salt cavern construction using the single-well retreating horizontal (SWRH) salt cavern construction method. It can reliably determine and verify the key process parameters during salt cavern construction, which is beneficial to further solving the problems of long construction parameter optimization cycle and low salt cavern morphology prediction accuracy in the traditional SWRH salt cavern construction method. It has significant practical significance. Attached Figure Description

[0014] Figure 1 A simplified schematic diagram of the overall structure of a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, provided by the present invention; Figure 2 A simplified structural diagram of the embedded wellbore module and related sealing components in a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, provided by the present invention. Figure 3 This is a schematic diagram of the casing retraction control module in a physical visualization system for simulating the construction of a single-well retraction-type horizontal salt cavern, provided by the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, 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 this invention.

[0017] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0019] The technical solution of the present invention will be further described below through specific embodiments. Details not specified in the embodiments are all conventional technologies in the industry.

[0020] See Figures 1 to 3 This invention provides a physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, including a salt rock solid model 1, an embedded wellbore module 2, a casing retreating control module 3, a constant flow water injection and brine discharge and salt rock segmented dissolution cavity formation module, and a visualization observation and imaging module. Embedded well module 2 is embedded (specifically inserted from left to right) in salt rock solid model 1; The casing retraction control module 3 is connected to the water injection casing 201 in the embedded well module 2, and is used to drive the water injection casing 201 to perform segmented retraction (i.e., rightward movement) in the prefabricated channel 100 of the salt rock solid model 1 in the horizontal direction. The constant flow water injection and brine drainage and salt rock segmented dissolution cavity-forming module 4 is used to perform water-dissolving salt rock cavity-forming operation on the salt rock solid model 1 by injecting fresh water into the salt rock solid model 1, forming a hollow salt cave 104 inside the salt rock solid model 1, and after forming the salt cave 104, injecting fresh water into the salt cave 104 inside the salt rock solid model 1, and draining out the brine (i.e., sodium chloride NaCl solution, also known as brine) formed by the fresh water dissolving the salt rock during the water-dissolving salt rock cavity-forming operation. The visualization monitoring and imaging module is connected to the casing retraction control module 3 to monitor the formation process of salt caverns in the salt rock entity model 1 and to feed back the monitoring results to the casing retraction control module 3.

[0021] It should be noted that, for this invention, as shown in Table 1 below, it is assumed that the fluid properties and temperature remain constant during the salt rock dissolution process. Based on the π similarity theory proposed by American physicist Backingham, the geometric dimensions, flow rates, and time similarity relationships between the on-site (i.e., the actual constructed single-well retreating salt cavern) and the salt rock entity model (i.e., the single-well retreating salt cavern model) are constructed. The process of water injection dissolving salt rock is simulated through constant flow injection and brine discharge modules, and the salt cavern construction evolution process is recorded in real time. Changes in brine flow rate and concentration are measured, thereby achieving dynamic reconstruction and parameter inversion of the salt cavern morphology. This invention can realistically reproduce (i.e., simulate and reproduce) the single-well retreating salt cavern construction process, providing a scientific basis for the design, safety assessment, and operational optimization of deep salt cavern hydrogen storage facilities.

[0022] Table 1. Similarity ratio between the field and the model constructed using Buckingham's π theorem.

[0023] In this invention, specifically, the salt rock entity model 1 is a salt rock entity model that meets preset conditions; The preset conditions include the following conditions: First condition: The salt rock entity model is a cuboid-shaped salt rock entity (e.g., a salt rock block); a hollow prefabricated channel 100 is opened on the front side of the salt rock entity along the horizontal length direction, and the prefabricated channel 100 is used to set the embedded well module; Second condition: A tempered glass 101 is provided on the front surface of the salt rock solid model 1, which serves as a transparent observation window; In practice, the solid salt rock model can be made of natural Pakistani salt rock with dimensions of 500 mm × 300 mm × 200 mm (length × width × height), or an artificially pressed, integrated salt rock block with a prefabricated simulated well shaft inside. After the surface of the solid salt rock model is ground smooth, a prefabricated channel with a width of 10 mm, a height of 10 mm, and a length of 180 mm is opened along its length to embed the embedded well shaft module.

[0024] In terms of specific implementation, in order to facilitate high-definition recording and monitoring of the simulated construction process of the salt cavern, a 5 mm thick tempered glass is set on the front side of the salt rock physical model as a transparent observation window.

[0025] Furthermore, the transparent observation window adopts a sealing combination of "structural support + adhesive sealing + flange frame" to ensure that the device can maintain a stable seal for a long time under high flow rate, salt solution corrosion environment and certain internal pressure conditions.

[0026] The tempered glass 101, serving as a transparent observation window, is designed and installed on the solid salt rock model as follows: First design: Tempered glass 101 is fixed to the front side of the salt rock solid model 1 through metal frame 102; Specifically, the tempered glass 101, which serves as a transparent observation window, is located inside the rectangular metal frame 102, which is fixedly mounted on the front side of the salt rock physical model 1.

[0027] It should be noted that the outer edge of the 5 mm tempered glass is machined into a smooth, flat surface, 10 mm larger than the actual size of the salt rock model, and is fixed to the front side of the model by a 316L stainless steel ring frame. The metal frame is 8 mm thick, forming a flat and uniform pressing surface, providing reliable structural support for the sealing material.

[0028] Second design: The contact gap between the four edges of the tempered glass 101, which serves as a transparent observation window, and the four edges of the front side of the salt rock solid model 1 is filled with silicone sealant. Third design: O-rings of fluororubber are embedded between the four edges of the metal frame 102 and the four edges of the salt rock solid model 1. Fourth design feature: The inner side of the metal frame is provided with a surrounding polytetrafluoroethylene sealing strip; A polytetrafluoroethylene (PTFE) sealing strip is located in the gap between the metal frame 102 and the salt rock solid model 1.

[0029] It should be noted that a three-layer sealing system is used between the tempered glass 101, which serves as the transparent observation window, and the salt rock model 1: adhesive sealing, O-ring sealing, and sealing strip. The first primary seal involves filling the contact gap between the tempered glass (the transparent observation window) and the front side of the salt rock model with a 1-2 mm thick layer of salt-resistant neutral silicone sealant to prevent salt solution leakage. The second seal involves embedding a salt-resistant O-ring with minimal permanent compression deformation between the metal frame and the salt rock model to prevent brine from seeping into the glass edges and causing corrosion. The third seal is an additional layer of absolutely salt-resistant PTFE sealing strip inside the metal frame as a supplementary sealing measure to enhance salt corrosion resistance and improve the long-lasting sealing of the flange clamping surface.

[0030] The above three sealing measures ensure that the transparent observation window maintains a stable seal under high-flow salt solution scouring, slight pressure changes, and long-term corrosive environments.

[0031] In practice, a window sealing assembly is provided on the front side of the tempered glass 101, which serves as a transparent observation window, near the metal frame 102. The observation window sealing assembly 103 includes a stainless steel annular flange frame and a fluororubber O-ring. The flange frame is located on the front side of the tempered glass 101, and the outer edges of the flange frame abut against the inner edges of the metal frame 102 (i.e., they are in close contact). A fluororubber O-ring is provided between the flange frame and the front side of the transparent observation window.

[0032] It should be noted that a 5 mm thick 316L stainless steel ring flange sealing assembly (i.e., the observation window sealing assembly) is installed on the outside of the transparent observation window. This assembly includes a stainless steel ring flange and an embedded fluororubber O-ring. The flange is connected to the metal frame on the front of the salt rock model via bolts and nuts. Axial clamping force is applied to the flange by evenly distributed bolts, causing elastic compression of the O-ring and forming a stable contact seal between the tempered glass surface and the flange sealing surface, thereby achieving long-term reliable isolation from the salt solution.

[0033] In this invention, for specific implementation, see [link to relevant documentation]. Figure 2 As shown, the embedded well module 2 is embedded in the prefabricated channel 100 within the salt rock solid model 1; Embedded well module 2 includes a hollow water injection casing 201 and a hollow brine discharge casing; Water injection sleeve 201 is located inside the brine discharge sleeve; It should be noted that the gap between the brine discharge casing and the water injection casing (i.e., the intermediate annulus) is used to discharge the brine generated during the simulated construction of a single-well retreating horizontal (SWRH) salt cavern in the salt rock solid model.

[0034] In practice, the inner diameter of the brine discharge sleeve is larger than the inner diameter of the water injection sleeve.

[0035] It should be noted that the water injection sleeve 201 and the brine discharge sleeve are cylindrical in shape.

[0036] It should be noted that, as Figure 2 As shown, the embedded well casing module 2 consists of a water injection casing and a brine discharge casing. The water injection casing has an inner diameter of 6 mm, and the brine discharge casing has an inner diameter of 10 mm. The annular space between the two pipes is used to discharge brine. Both the water injection and brine discharge casings are embedded along prefabricated channels in the salt rock model (e.g., a natural salt rock model) and fixed using transparent resin sealing components.

[0037] In practice, the transparent resin sealing assembly includes a main sealing adhesive layer and an auxiliary adhesive layer. The main sealing adhesive layer is made of transparent epoxy resin, which is used to bond the brine discharge sleeve to the inner wall of the prefabricated channel in the solid salt rock model. The auxiliary adhesive layer is a silane coupling agent, which is pre-coated on the inner wall of the prefabricated channel.

[0038] It should be noted that, for the embedded well module of this invention, firstly, a two-component curable transparent epoxy resin is used as the main sealing layer. This resin has strong adhesion, allowing it to firmly bond with salt rock and glass. After curing, it forms a high-strength solid, which can firmly fix the brine discharge sleeve embedded in the prefabricated channel to the surface of the salt rock. Simultaneously, it has good fluidity, completely filling the prefabricated channel, and exhibits excellent salt corrosion resistance and long-term water resistance. Secondly, to improve the bonding reliability between the transparent resin and the salt rock, a layer of silane coupling agent (a type of adhesive) can be applied to the inner wall of the prefabricated channel. This enhances the chemical bonding and adhesion between the resin and the salt rock crystal surface, preventing interface peeling caused by the salt rock absorbing water and swelling.

[0039] In this invention, for specific implementation, see [link to relevant documentation]. Figure 3 As shown, the casing retraction control module 3 is connected to the water injection casing 201 in the embedded well module 2, and is used to drive the water injection casing 201 to perform segmented retraction operations (i.e., multiple rightward movement operations performed successively) in the prefabricated channel 100 of the salt rock solid model 1 along the horizontal direction.

[0040] It should be noted that the casing retraction control module 3 is a key component for realizing the controllable simulation of the single-well retraction salt cavern construction process. It is used to drive the water injection casing 201 to achieve precise segmented retraction operation along the horizontal axis in the salt rock solid model.

[0041] In this invention, for specific implementation, see [link to relevant documentation]. Figure 3 As shown, the casing retraction control module 3 includes a linear guide unit and a power drive unit; A linear guide component is used to support and constrain the movement direction of the water injection casing 201 in the embedded well module 2; The power drive unit, whose power output end is linked to the water injection casing 201 in the embedded well module 2, is used to realize the smooth advancement or pulling out of the water injection casing 20.

[0042] In specific implementation, the power drive unit is a stepper motor 300; The linear guide component includes a linear slide rail 301 and a slider 302; A slider 302 is provided on the linear slide rail 301, which can move horizontally left and right; A support base 303 is provided at the top left end of the slider 302; A horizontally distributed connecting rod 304 is placed on the top of the slider 302; The right end of the connecting rod 304 is connected to the left end of the water injection sleeve 201; The left end of the connecting rod 304 passes laterally through the central through hole of the support base 303 and is connected to the output end (i.e., the output shaft) of the stepper motor 300 (for example, through a coupling). The water inlet at the left end of the water injection sleeve 201 is connected to one end of the water supply hose 402; The other end of the water supply hose 402 is connected to the outlet of the constant flow pump 401 in the constant flow water injection and brine discharge and salt rock segmented dissolution cavity module.

[0043] It should be noted that the slider 302 is installed in the groove at the top of the linear guide rail 301, and the slider 302 can slide within the groove at the top of the linear guide rail 301. The sliding fit design between the slider and the groove is a mature and conventional design in existing technology, and will not be elaborated further here. For example, the groove can be a T-shaped, horizontally distributed recess, and one end of the slider can be a T-shaped protrusion. The T-shaped protrusion is located in the T-shaped groove, and the two are slidably connected, with corresponding shapes and sizes. The sliding fit design between the T-groove and the slider is a well-known and conventional design, and will not be elaborated further here.

[0044] Furthermore, a sealing connection component is provided at the connection between the water injection sleeve 201 and the water supply hose 402.

[0045] It should be noted that the sealing connection components specifically include a PTFE dynamic sealing ring and a salt corrosion resistant O-ring, which are installed at the connection between the water injection sleeve and the water supply hose. The PTFE dynamic sealing ring and the salt corrosion resistant O-ring 306 are arranged inside the connection between the water injection sleeve and the water supply hose, which can effectively prevent salt solution leakage while ensuring continuous fluid injection.

[0046] Furthermore, the stepper motor drive module built into the stepper motor 300 is connected to the displacement controller 305; The displacement controller 305 is used to set the backward step length, speed and dwell time of the water injection sleeve 201, and to control the stepper motor 300 to perform a backward operation on the water injection sleeve 201 (i.e., move to the right, that is, move deeper into the prefabricated channel 100 away from the stepper motor 300), so as to realize the smooth advancement or pulling out of the water injection sleeve 201, and thus realize the automated and precise control of the backward distance of the water injection sleeve 201.

[0047] In this invention, specifically, the retraction step length (ΔL) of the water injection sleeve can be obtained through the displacement controller 305.

[0048] It should be noted that, in the process of simulating the construction of salt caverns by dissolving salt rock, the water injection casing, while maintaining a constant fresh water flow rate, triggers a retraction command based on the monitoring signal of salt rock dissolution rate or brine concentration. A stepper motor drives the slider 302 to move smoothly backward along the linear slide rail 301, causing the water injection casing 201 to retract segment by segment into the depth of the salt rock model 1, thus forming a continuous "retraction-type" cavity-building process. This casing retraction control module 3 ensures stable water supply, reliable sealing, and accurate positioning throughout the entire operation, significantly improving the controllability and repeatability of single-well retraction-type horizontal salt cavern simulation construction, and providing experimental support for the study of the formation mechanism and morphological optimization of hydrogen storage salt cavern cavities.

[0049] In this invention, specifically, the constant flow water injection and brine discharge and salt rock segmented dissolution cavity forming module 4 includes a constant flow pump 401; The outlet of the constant flow pump 401 is connected to the inlet of the water injection sleeve 201 in the embedded well module 2 through the water supply hose 402. The constant flow pump 401 is used to perform salt cavern construction and brine discharge operations. The salt cavern construction operation is as follows: the fresh water stored in the external fresh water tank 403 is extracted, and then the fresh water is injected into the salt rock solid model 1 through the water supply hose 402 and the water injection sleeve 201, so that the fresh water dissolves the salt rock inside the salt rock solid model 1 and forms a hollow salt cavern. The brine discharge operation is as follows: after the salt cavern is formed, fresh water pre-stored in the external fresh water tank is extracted as the dispersing fluid and pumped into the salt cavern, so that the brine obtained from dissolving the salt rock is discharged outward through the annular space between the brine discharge sleeve and the water injection sleeve 201.

[0050] Depending on the different stages of the work, fresh water can be used as a liquid to dissolve salt rocks or as a separating fluid.

[0051] It should be noted that in this invention, for the constant flow water injection and brine discharge and the segmented dissolution cavity module of salt rock: fresh water is injected through a constant flow pump, and the NaCl solution formed after the fresh water dissolves the salt rock is called brine. Since the fresh water injection pressure inside the salt cavern cavity is higher than the brine discharge outlet (the outlet at the left end of the annular space between the brine discharge sleeve and the water injection sleeve 201), under the action of the water injection pressure, the brine generated by dissolving the salt rock is discharged from the inside of the cavity to the outside along the low resistance channel of the annular space (i.e., the annular space between the brine discharge sleeve and the water injection sleeve 201), thereby forming a stable cycle of water injection and brine discharge.

[0052] It should be noted that the salt cavern system employs a "double-pipe structure." The inner pipe, the water injection pipe, is used to inject fresh water into the salt rock model. The outer pipe, the brine discharge pipe, forms an annular space between its inner wall and the outer wall of the water injection pipe. This annular space is designed as a brine flow channel. This annular space, serving as a brine discharge channel, is specially designed. The inner pipe independently handles water injection, while the outer ring handles brine discharge, without interference between the two.

[0053] In practice, the outlet of the water supply hose 402 is connected to the inlet of the water injection sleeve 201 in the embedded well module 2. The inlet of the water supply hose 402 is connected to the outlet of the second rotor flow meter 4042; The inlet of the second rotor flowmeter 4042 is connected to the outlet of the constant flow pump 401 through a hollow connecting pipe. The inlet of the constant flow pump 401 is connected to the outlet at the lower end of the fresh water tank 403.

[0054] The second rotor flowmeter 4042 is used to detect the freshwater injection flow rate, a process parameter in the salt cavern construction process.

[0055] It should be noted that the water supply hose 402 is used to stably deliver constant flow fresh water to the inlet of the water injection sleeve 201. The water supply hose 402 is connected to the second rotor flow meter 4042 to form a flow control unit. The second rotor flow meter 4042 is used to monitor the water injection flow in real time, and then further adjust the water injection flow through the constant flow pump.

[0056] In practice, the outlet at the left end of the annular space between the brine drain sleeve and the water injection sleeve 201 is connected to the inlet of the first brine drain pipe 4051. The outlet of the first brine pipe 4051 is connected to the inlet of the first rotor flow meter 4041; The outlet of the first rotor flowmeter 4041 is connected to the inlet of the brine tank 406 through the second brine pipe 4052. The brine in the brine tank 406 is in contact with the detection end (i.e., probe) of an ion concentration meter 407; the detection end (i.e., probe) of the ion concentration meter 407 is specifically located on the inner side of the bottom of the brine tank 406.

[0057] Among them, the first rotor flowmeter 4041 is used to detect the brine discharge flow rate, a process parameter in the salt cavern construction process.

[0058] It should be noted that the brine generated from the salt rock in the freshwater dissolution model 1 is drained into brine tank 406 through the left-hand outlet of the annular space between the brine discharge sleeve and the water injection sleeve 201. Brine tank 406 is a brine collection tank used to collect the discharged brine. Brine tank 406 also serves as a stable sampling container for the probe of ion concentration meter 407 to be immersed for measurement. Ion concentration meter 407 obtains the brine concentration based on changes in solution conductivity or ion activity. The above components constitute the monitoring of the salt rock dissolution process. Through flow control and concentration measurement, the real-time reflection of the salt rock dissolution state is achieved, providing key feedback for the segmented retreat control of the cavity-building process.

[0059] In the double-tube injection and discharge structure of the present invention, the water injection tube is located inside the brine discharge tube, and the two form a continuous annular space. Since the fluid pressure inside the salt cavern cavity is higher than the pressure at the brine discharge outlet (the outlet at the left end of the annular space between the brine discharge tube and the water injection tube 201), under the action of external force (including water injection pressure and natural pressure difference), the brine generated by dissolving the salt rock is discharged from the inside of the salt cavern cavity along the annular space between the brine discharge tube and the water injection tube, thereby forming a stable cycle of water injection and brine discharge.

[0060] It should be noted that, for this invention, it is assumed that the temperature changes caused by salt rock erosion have a negligible impact on the transport of fresh water and brine. During the simulated construction of the salt cavern, a constant flow pump is started and the initial time is recorded. Fresh water is injected into the salt rock solid model 1 through the water injection sleeve 201. At this time, the injection rate of fresh water must be precisely controlled from 0-10 mL / min, and the constant flow pump can stably maintain an error of ±1%. For example, when the injection rate of fresh water is 10 mL / min, it corresponds to a 120 m depth in the actual engineering site. 3 / h. Driven away by fresh water used as an isolation fluid, the brine obtained from the dissolution of salt rock by fresh water during the initial salt cavern construction process is discharged outwards through the annular space between the brine discharge sleeve and the water injection sleeve 201, and then collected in the external brine tank 406. During this process, two flow meters (a first rotor flow meter and a second rotor flow meter) are used to monitor the brine discharge and fresh water injection respectively. The outlet position of the brine discharge sleeve is 0.1-0.2 m higher than the upper surface of the salt rock model to maintain a stable brine outlet pressure. An ion concentration meter with a resolution of mmol / L is used to measure the Na+ in the brine (sodium chloride NaCl solution) in real time. + or Cl - The concentration and sampling frequency can be set to 1 time / min to 1 time / h to measure the change in freshwater dissolution rate and the saturation of discharged brine.

[0061] In addition, before simulating the construction of salt caves by dissolving salt rocks, it is necessary to calibrate the ion concentration meter using sodium chloride solutions of different concentrations.

[0062] It should be noted that after the water injection (fresh water injection) in a single salt rock dissolution stage reaches the design time (i.e., dissolution time t) or the length and height of the salt cavern physical model reach the predetermined threshold (for example, the first stage of salt rock physical model dissolution lasts 0.144 hours (i.e., dissolution time t), corresponding to 240 days in actual field engineering), the fresh water injection is stopped and the casing retraction control module 3 is activated to retract the water injection casing 201 to the predetermined step length (for example, the salt rock physical model retraction step length is 0.75 m, corresponding to 150 m in the field). After the water injection casing 201 is fixed again, fresh water injection continues to dissolve the salt rock, thus entering the next salt rock dissolution stage.

[0063] During the dissolution process, the mass of dissolved salt per unit time (which is equal to the product of the concentration and flow rate of the discharged brine) is calculated based on the concentration and flow rate of the discharged brine. The dissolution rate of the salt rock per unit area is then calculated and its consistency with the observed growth rate of the salt cave shape is verified.

[0064] By analyzing the brine ion concentration versus time curve, it is determined whether the brine has reached local saturation (for example, when the ambient temperature is 20 ℃, if the brine concentration approaches or exceeds the initial boundary concentration of 5.641 mol / L, or if the brine concentration increase tends to stabilize, then the brine has reached local saturation; stabilization means that the brine concentration increase rate is less than the preset value). This serves as the criterion for whether the water injection sleeve 201 should continue to retract or stop water injection. The above-mentioned staged water injection and retraction operations are repeated until the salt cavern within the salt rock entity model 1 reaches the designed salt cavern shape.

[0065] In this invention, specifically, the dissolution rate of salt rock per unit area is calculated based on mass balance. R .

[0066] Dissolution rate R Mass flux dissolved per unit area per unit time, commonly measured in kg·m³. -2 ·s -1 , formula (1); in, R Dissolution rate, unit: kg·m -2 ·s -1 : Mass of salt dissolved per unit time, expressed in kg·s -1 It can be calculated from the concentration and flow rate of the effluent; ; Q Volumetric flow rate, unit: m³ 3 ·s -1 Measurement method: The value is read by the rotor flow meter (i.e., the first rotor flow meter 4041); C out Mass concentration of solute in discharged brine, in kg·m³ -3 Measurement method: using an ion concentration meter 407; C in The initial concentration of the injected freshwater can be approximated as 0. A : Exposed area participating in the dissolution reaction, in meters 2 Measurement method: The surface area of ​​the salt cavern cavity is obtained by image reconstruction.

[0067] In this invention, specifically, the instantaneous growth rate of the salt cavern morphology (i.e., the salt cavern shape growth rate) is obtained by extracting the cavity contour frame by frame from a continuously acquired image sequence during salt rock karstification and converting the pixel coordinates into physical coordinates. The operation of obtaining the instantaneous growth rate of the salt cavern morphology (i.e., the salt cavern shape growth rate) specifically includes the following steps: Step S1: Perform distortion correction and calibration on the images collected during the salt rock karstification process, and use an optical scale to determine the conversion factor from pixels to actual length; Step S2: Subsequently, Gaussian filtering and background removal are performed on the grayscale image. Then, the boundaries of the salt cavern are extracted using the Canny edge detection and contour tracking algorithm (a mature and well-known algorithm in the current technology). Subpixel fitting and smoothing are then performed on the boundaries of the salt cavern. Step S3: Based on the extracted salt cavern boundaries, calculate the cross-sectional area of ​​the salt cavern over time. A ( t The instantaneous growth rate of the salt cavern morphology was obtained by using polynomial fitting and differentiation.

[0068] The acquisition of the instantaneous growth rate of the salt cavern morphology (i.e., the growth rate of the salt cavern shape) (steps S1 to S3) can be specifically performed by the image processing unit in the visualization monitoring and image processing module. That is, the image processing unit is used to perform the acquisition of the instantaneous growth rate of the salt cavern morphology. Through the industrial camera in the visualization monitoring and image processing module, images during the salt rock dissolution can be acquired.

[0069] In step S3, specifically, at each time step... t Using the salt cavern boundaries extracted from the image, under the assumption of axis symmetry, the equivalent radius is... r (z,t), calculate the actual cross-sectional area of ​​the cavity on the specified section. A ( z , t ). (The remaining text appears to be incomplete and contains several grammatical errors. A more accurate translation would require the full context A ( z , tArranging them in chronological order yields a sequence showing the change in the cross-sectional area of ​​the salt cavern cavity over time. A ( t The sequence of cross-sectional area of ​​salt cavern over time. A ( t The calculation formula for ) is as follows: , formula (2); in, A ( z , t () represents the axisymmetric equivalent cross-sectional area, in meters. 2 ; r ( z , t () represents the equivalent radius of the salt cavern cavity, in meters. This is achieved by extracting the same location from the image. z Distance between upper and lower boundaries D ( z , t The calculation yielded the following: , formula (3).

[0070] In step S3, specifically, to obtain the instantaneous growth rate of the salt cavern morphology, a low-order polynomial is first used to fit the cross-sectional area of ​​the salt cavern over time to approximate the continuous change of the cross-sectional area of ​​the salt cavern over time. Then, the fitted polynomial is analytically differentiated, and its first derivative is calculated at a specified time to obtain the instantaneous growth rate at that time.

[0071] The instantaneous growth rate of the salt cavern morphology is calculated by differentiating the fitting function of the cross-sectional area of ​​the salt cavern with respect to time. The formula is as follows: , formula (4).

[0072] In this invention, specifically, the visualization monitoring and image processing module includes an industrial camera 501, an illumination component 502, and an image processing unit. Industrial camera 501 is used to capture images of salt caverns inside the salt rock solid model 1 through tempered glass 101, which serves as a transparent observation window on the salt rock solid model 1. The image processing unit is connected to the industrial camera to receive images captured by the working camera and analyze them to obtain the size (specifically, the volume) of the salt cavern. The lighting component 502 is used to illuminate the salt cave locations within the salt rock entity model 1, providing supplemental lighting to the salt caves.

[0073] In practice, the lighting components are LED planar backlights or reflectors, or other light sources that can provide uniform light.

[0074] It should be noted that the visualization monitoring and imaging module is used to visualize and monitor the salt cavern dissolution process, and includes a high-resolution industrial camera, lighting components, and an image processing unit.

[0075] In this invention, a high-resolution industrial camera (minimum 1080p, 30 fps) is used to continuously record the salt caverns inside the salt rock physical model 1 by facing the front side of the salt rock physical model 1 through the tempered glass 101, which serves as a transparent observation window. A high-brightness LED flat backlight panel is used to provide uniform supplementary lighting, making the outline of the salt cavern cavity edge clearer and improving the recognition rate of the salt cavern boundary by the high-definition camera.

[0076] In specific implementation, the image processing unit is connected to the industrial camera to receive images acquired by the working camera. It uses image reconstruction and volume integration to automatically identify and calculate the boundary, length and volume changes of the salt cave formed in the salt rock entity model 1, identify the size of the salt cave cavity (specifically the volume size), and generate the corresponding time series evolution curve to realize the quantitative and visual expression of the salt cave dissolution process.

[0077] The image processing unit communicates with the displacement controller in the casing retraction control module 3 to feed back the identified salt cavern size and boundary to the casing retraction control module 3, thereby allowing the casing retraction control module 3 to further control the timing and distance of the water injection casing retraction.

[0078] For example, the displacement controller in the casing retraction control module 3 is used to receive the size of the salt cavern cavity identified by the image processing unit. When the size of the salt cavern cavity identified by the image processing unit reaches (i.e., is greater than or equal to) the preset size of the salt cavern cavity, a stop working signal is sent to the constant flow pump in the constant flow water injection and brine discharge and salt rock segmented dissolution cavity forming module, so that the constant flow pump stops working, and a pull-out control signal is sent to the stepper motor drive module matched with the stepper motor 300 to move the water injection casing 201 to the left by a preset distance.

[0079] For example, the displacement controller in the casing retraction control module 3 is used to receive the size of the salt cavern cavity identified by the image processing unit. When the size of the salt cavern cavity identified by the image processing unit is smaller than the preset size of the salt cavern cavity, a control signal to continue moving to the right (i.e. retraction) is sent to the stepper motor drive module matched with the stepper motor 300, so that the water injection casing 201 continues to move to the right (i.e. retraction).

[0080] It should be noted that the image processing unit can be a programmable logic controller (PLC), a central processing unit (CPU), a digital signal processor (DSP), or a microcontroller (MCU).

[0081] It should be noted that, currently, in the fields of engineering and visualization measurement, "image reconstruction and volume integration method" generally refers to a volume integration calculation method based on geometric image reconstruction. By extracting edges, tracing contours, and reconstructing geometry from continuously acquired images of salt caverns during the dissolution process, pixel coordinates are converted to physical scales, thereby obtaining the two-dimensional cross-sectional area and three-dimensional volume of the salt cavern at different time points. The cavity shape is approximately axisymmetric, and the volume evolution curve of the salt cavern can be obtained in real time based on the rotational integration of the contour curve. This method can accurately reflect the spatial expansion characteristics of salt rock dissolution, providing a reliable basis for determining the retreat step length of the water injection casing, monitoring the dissolution rate, and automating the cavity-building process.

[0082] Two-dimensional profile curves Perform rotational integration: , formula (5); In formula (5), V Let m be the volume of the salt cavern. 3 It is the total volume of a three-dimensional cavity formed by rotating a two-dimensional contour around an axis; π Pi; z max and z min These are the starting and ending coordinates of the salt cave along the axial direction, respectively, in meters; r ( z Let be the equivalent radius function of the salt cavern, and let be the axial position of the salt cavern. z The equivalent radius at that location. This is determined by extracting the same location from the image. z Distance between upper and lower boundaries D ( z The calculation yielded the following: r ( z )= D ( z ) / 2.

[0083] dz The length of the axial infinitesimal element is in meters (m), representing the axial thickness of a single thin layer in the volume integral.

[0084] It should be noted that image reconstruction methods, edge detection algorithms, and volume integral formulas are known technologies in the current field of computer vision. They are mature and widely used technologies, and will not be elaborated upon here.

[0085] It should be noted that, for this invention, the time series evolution curve uses a uniform time axis (relative experimental time, unit: min) as the x-axis and the salt cavern cross-sectional area (m²) as the y-axis. 2 The equivalent cross-sectional area of ​​the salt cavern cavity.A ( t The contours are obtained from the continuous images: distortion correction, edge detection and contour tracking are performed on each frame of the image, and the contour coordinates are converted into the actual area by converting the pixel scale to the physical scale calibration; the volume is calculated using the volume integral formula of the solid of revolution (5) under the assumption of axisymmetry.

[0086] In this invention, specifically, the fresh water injected into the salt rock solid model 1 by the constant flow water injection and brine discharge and salt rock segmented dissolution cavity module contains an inert tracer dye.

[0087] In practice, the inert tracer dye, such as a black or dark-colored non-reactive dye, has a volume concentration of approximately 0.01%.

[0088] It should be noted that, for this invention, an inert tracer dye can be added to the injected fresh water for salt cave dissolution boundary identification, thereby improving the accuracy of image recognition.

[0089] In summary, compared with existing technologies, the physical visualization system for simulating the construction of single-well retreating horizontal salt caverns provided by this invention has the following beneficial effects: 1. Innovative overall system architecture: The established SWRH salt cavern simulation and construction physical visualization system provides a visual, quantifiable, and verifiable foundation for the construction of deep salt rock salt caverns; 2. Innovative casing retraction control equipment: The precise casing retraction control device can automatically retract according to the erosion requirements of the salt cave shape, realizing automated and precise retraction control of the water injection casing; 3. Innovative linkage control method of visual monitoring + image analysis + water injection casing retreat: The transparent tempered glass observation window collects images of the salt cavern dissolution interface in real time, and realistically visualizes and restores the dissolution evolution process of the single-well retreating horizontal hydrogen storage salt cavern, revealing the spatial expansion law of SWRH salt cavern cavity formation.

[0090] In summary, compared with existing technologies, this invention provides a physical visualization system for simulating the construction of single-well retreating horizontal salt caverns. The system is scientifically designed and can simulate the salt cavern construction process using the single-well retreating horizontal (SWRH) salt cavern construction method. It can reliably determine and verify key process parameters during salt cavern construction, which helps to further solve problems such as long optimization cycles for construction parameters and low accuracy in predicting salt cavern morphology in traditional SWRH salt cavern construction methods. This has significant practical implications.

[0091] To address the issues of uncontrollable salt cavern morphology during SWRH salt cavern formation, the inability of traditional "black box" physical dissolution experiments to achieve three-dimensional dynamic visualization, and the inability to accurately quantify the retreat distance of the injection casing, the salt rock dissolution rate, and the geometric evolution of the salt cavern, this invention provides a physical visualization system for studying the simulated construction process of a single-well retreating horizontal salt cavern. This system has significant theoretical and engineering value in revealing the evolution law of the cavity shape during the water dissolution construction of horizontal salt caverns and improving the reliability of engineering design.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern, characterized in that, It includes a solid model of salt rock (1), an embedded wellbore module (2), a casing retraction control module (3), a constant flow water injection and brine discharge and salt rock segmented dissolution cavity module, as well as a visualization observation and imaging module; An embedded wellbore module (2) is embedded in the salt rock solid model (1); The casing retraction control module (3) is connected to the water injection casing (201) in the embedded well module (2) and is used to drive the water injection casing (201) to move to the right in the prefabricated channel (100) of the salt rock solid model (1) in the horizontal direction. The constant flow water injection and brine discharge and salt rock segmented dissolution cavity module is used to perform water dissolution salt rock cavity creation operation on the salt rock solid model (1) by injecting fresh water into the salt rock solid model (1), forming a hollow salt cave (104) inside the salt rock solid model (1), and after the salt cave (104) is formed, the brine formed by the fresh water dissolving the salt rock during the water dissolution salt rock cavity creation operation is discharged outward by injecting fresh water into the salt cave (104) inside the salt rock solid model (1); The visualization monitoring and imaging module is connected to the casing retraction control module (3) to monitor the formation process of salt caverns in the salt rock entity model (1) and to feed back the monitoring results to the casing retraction control module (3).

2. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, The salt rock entity model (1) is a salt rock entity model that meets the preset conditions; The preset conditions include the following conditions: First condition: The salt rock entity model is a cuboid salt rock entity; a hollow prefabricated channel (100) is opened on the front side of the salt rock entity along the horizontal length direction, and the prefabricated channel (100) is used to set the embedded well module; Second condition: A tempered glass (101) is provided on the front surface of the salt rock solid model (1), which serves as a transparent observation window; The tempered glass (101) serving as a transparent observation window is designed and installed on the solid salt rock model as follows: First design: Tempered glass (101) is fixed to the front side of the salt rock solid model (1) by a metal frame (102); Second design: The contact gap between the four edges of the tempered glass (101) which serves as a transparent observation window and the four edges of the front side of the salt rock solid model (1) is filled with silicone sealant. Third design: O-rings of fluororubber are embedded between the four edges of the metal frame (102) and the four edges of the salt rock solid model (1); Fourth design feature: The inner side of the metal frame is provided with a surrounding polytetrafluoroethylene sealing strip; A polytetrafluoroethylene sealing strip is located in the gap between the metal frame (102) and the salt rock solid model (1).

3. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 2, characterized in that, On the front side of the tempered glass (101) that serves as a transparent observation window, near the metal frame (102), there is an observation window sealing assembly (103). The observation window sealing assembly (103) includes a stainless steel annular flange frame and a fluororubber O-ring. The flange frame is located on the front side of the tempered glass (101), and the outer edges of the flange frame abut against the inner edges of the metal frame (102). A fluororubber O-ring is provided between the flange frame and the front side of the transparent observation window.

4. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, An embedded wellbore module (2) is embedded in a prefabricated channel (100) within a salt rock solid model (1); An embedded well module (2) includes a hollow water injection casing (201) and a hollow brine discharge casing; Water injection sleeve (201) is located inside brine discharge sleeve.

5. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, The casing retraction control module (3) is connected to the water injection casing (201) in the embedded well module (2) and is used to drive the water injection casing (201) to move to the right in the prefabricated channel (100) of the salt rock solid model (1) in the horizontal direction. The casing retraction control module (3) includes a linear guide unit and a power drive unit; A linear guide component is used to support and constrain the direction of movement of the water injection casing (201) in the embedded well module (2); The power drive unit has its power output end connected to the water injection casing (201) in the embedded well module (2); The power drive unit is a stepper motor (300); The linear guide component includes a linear slide rail (301) and a slider (302). A slider (302) is provided on the linear guide rail (301) so as to move laterally left and right. A support base (303) is provided at the top left end of the slider (302). A horizontally distributed connecting rod (304) is placed on the top of the slider (302). The right end of the connecting rod (304) is connected to the left end of the water injection sleeve (201); The left end of the connecting rod (304) passes horizontally through the central through hole of the support base (303) and is connected to the output end of the stepper motor (300); The left end of the water injection sleeve (201) has a water inlet that is connected to one end of the water supply hose (402); The other end of the water supply hose (402) is connected to the outlet of the constant flow pump (401) in the constant flow water injection and brine discharge and salt rock segmented dissolution cavity module.

6. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 5, characterized in that, The stepper motor drive module built into the stepper motor (300) is connected to the displacement controller (305); The displacement controller (305) is used to set the backward step length, speed and dwell time of the water injection sleeve (201) and control the stepper motor (300) to move the water injection sleeve (201) to the right.

7. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, The constant flow water injection and brine discharge and salt rock segmental dissolution cavity module (4) includes a constant flow pump (401). The outlet of the constant flow pump (401) is connected to the inlet of the water injection sleeve (201) in the embedded well module (2) through the water supply hose (402); A constant flow pump (401) is used to perform salt cavern construction and brine discharge operations; The salt cave construction operation is as follows: extract the fresh water stored in the external fresh water tank (403) in advance, and then inject the fresh water into the salt rock solid model (1) through the water supply hose (402) and the water injection sleeve (201) so that the fresh water dissolves the salt rock inside the salt rock solid model (1) to form a hollow salt cave. The brine discharge operation is as follows: after the salt cavern is formed, the fresh water pre-stored in the external fresh water tank is extracted as the dispersing fluid and pumped into the salt cavern, so that the brine obtained by dissolving the salt rock is discharged outward through the annular space between the brine discharge sleeve and the water injection sleeve (201).

8. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, The outlet of the water supply hose (402) is connected to the inlet of the water injection sleeve (201) in the embedded well module (2); The inlet of the water supply hose (402) is connected to the outlet of the second rotor flow meter (4042); The inlet of the second rotor flowmeter (4042) is connected to the outlet of the constant flow pump (401) through a hollow connecting pipe; The inlet of the constant flow pump (401) is connected to the outlet at the lower end of the fresh water tank (403); The left end outlet of the annular space between the brine drain sleeve and the water injection sleeve (201) is connected to the inlet of the first brine drain pipe (4051); The outlet of the first brine pipe (4051) is connected to the inlet of the first rotor flowmeter (4041); The outlet of the first rotor flowmeter (4041) is connected to the inlet of the brine tank (406) through the second brine pipe (4052); The brine in the brine tank (406) comes into contact with the detection probe of an ion concentration meter (407).

9. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 1, characterized in that, The visualization monitoring and image processing module includes an industrial camera, lighting components, and an image processing unit; An industrial camera is used to capture images of salt caverns inside the salt rock physical model (1) through a tempered glass (101) that serves as a transparent observation window on the salt rock physical model (1); The image processing unit is connected in communication with the industrial camera to receive images captured by the working camera and analyze them to obtain the size of the salt cavern. The lighting component is used to illuminate the salt cave locations within the salt rock physical model (1) to provide supplemental lighting to the salt caves.

10. The physical visualization system for simulating the construction of a single-well retreating horizontal salt cavern as described in claim 9, characterized in that, Visual monitoring and image processing module, including industrial camera and image processing unit; An industrial camera is used to capture images of salt caverns inside the salt rock physical model (1) through a tempered glass (101) that serves as a transparent observation window on the salt rock physical model (1); The image processing unit is used to perform the acquisition operation of the instantaneous growth rate of the salt cavern morphology; The process of obtaining the instantaneous growth rate of salt cavern morphology includes the following steps: Step S1: Perform distortion correction and calibration on the images collected during the salt rock karstification process, and use an optical scale to determine the conversion factor from pixels to actual length; Step S2: Subsequently, Gaussian filtering and background removal are performed on the grayscale image, and the boundaries of the salt cavern cavity are extracted using the Canny edge detection and contour tracking algorithm. Subpixel fitting and smoothing are then performed on the boundaries of the salt cavern cavity. Step S3: Based on the extracted salt cavern boundaries, calculate the cross-sectional area of ​​the salt cavern over time. A ( t The instantaneous growth rate of the salt cavern morphology was obtained by using polynomial fitting and differentiation. In step S3, the cross-sectional area of ​​the salt cavern cavity changes with time. A ( t The calculation formula for ) is as follows: Formula (2); in, A ( z , t () represents the axisymmetric equivalent cross-sectional area, in meters. 2 ; r ( z , t ) represents the equivalent radius of the salt cavern cavity, in meters.

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