Salt cavern dry-wet cycle crack repairing system and repairing method

Abstract

The invention discloses a salt cavern dry-wet cycle crack repairing system and method, the salt cavern dry-wet cycle crack repairing system comprises a gas channel, a gas injection pipeline, a gas production pipeline, a pressure control module and a temperature-humidity monitoring module, the gas channel is an internal space of a salt cavern shaft for gas circulation; the gas injection pipeline is communicated with the gas channel and is used for injecting high-pressure gas into the salt cavern; the gas production pipeline is communicated with the gas channel and is used for producing gas from the salt cavern; the pressure control module is communicated with the gas injection pipeline, the gas production pipeline and the gas path channel so as to control the gas injection and production pressure and adjust gas injection and production to enable the gas pressure in the salt cavern to change within an allowable range; the temperature and humidity changes in the salt cavern are monitored in real time through the temperature-humidity monitoring module so as to ensure that the relative humidity in the salt cavern reaches a set target range in a dry-wet cycle; the crack repairing speed of the damaged surrounding rock in the salt cavern can be increased, the repairing capacity is enhanced, and the repairing uniformity is improved.

Description

Technical Field

[0001] The present application relates to the field of salt cavern energy storage technology, and in particular to a salt cavern dry-wet cycle crack repair system and repair method. Background Art

[0002] At present, underground salt caverns have been widely used in the field of energy storage, especially in the storage of gas energy storage media such as natural gas, compressed air and hydrogen. The high sealing property of salt rock makes it an ideal energy storage site. However, during the construction of salt caverns, due to the redistribution of stress and the introduction of local deviatoric stress, the surrounding rock will be damaged, leading to the initiation and expansion of cracks. As the cracks further develop and become interconnected, micro-permeable layers may appear in the surrounding rock, posing a threat of leakage to the storage medium, causing energy storage loss, and even causing serious accidents such as surface fires in extreme cases.

[0003] At present, the mainstream method for dealing with the problem of micro-leakage in salt caverns is to soak the damaged parts with saturated brine and rely on the self-healing ability of salt rock to repair the crack structure. This method seals and fills the cracks through the diffusion mass transfer and recrystallization of brine inside the salt rock. However, the existing technology has significant defects:

[0004] Slow repair speed: The self-healing process of saturated brine relies on long-term immersion, which usually takes several months or even longer to achieve significant results in improving the sealing of salt caverns. For energy storage projects that require rapid repair, this method is inefficient and cannot cope with high-intensity industrial needs.

[0005] Limited repair ability: When the surrounding rock is severely damaged, especially when the crack width is large, the self-healing mechanism has limited repair effect and it is difficult to effectively seal the crack, resulting in leakage problems. Especially in an environment with complex crack development, the difficulty of repair is further increased.

[0006] In addition, existing methods rely too much on the natural healing process and lack additional motivation or external environmental regulation. Due to natural conditions such as temperature and pressure, the rate and effect of brine repair will vary significantly at different depths and in different areas.

[0007] To this end, developing faster, more efficient and more adaptable salt cave restoration technology has become a key task in current research. Summary of the invention

[0008] In order to solve the above problems, the present application provides a salt cavern dry-wet cycle crack repair system and repair method, which can accelerate the crack repair speed of damaged surrounding rocks in salt caverns, enhance the repair ability and improve the repair uniformity, so as to overcome the shortcomings of the prior art. The technical solution is as follows:

[0009] A first aspect of the present application provides a salt cavern dry-wet cycle fracture repair system, comprising an air passage, an injection pipeline, a gas production pipeline, a pressure control module and a temperature-humidity monitoring module, wherein the air passage is the internal space of the salt cavern wellbore for gas circulation; the injection pipeline is connected to the air passage and is used to inject high-pressure gas into the salt cavern; the gas production pipeline is connected to the air passage and is used to produce gas from the salt cavern; the pressure control module is connected to the injection pipeline, the gas production pipeline and the air passage to control the gas injection and production pressure and adjust the injected and produced gas so that the gas pressure in the salt cavern changes within an allowable range; the temperature and humidity changes in the salt cavern are monitored in real time by the temperature-humidity monitoring module to ensure that the relative humidity in the salt cavern reaches the set target range during the dry-wet cycle.

[0010] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, a compressor is also included, and the compressor is connected to the air inlet of the air injection pipeline to control the air injection rate.

[0011] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, a turbine is also included, and the turbine is connected to the gas outlet of the gas production pipeline to control the gas production rate.

[0012] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, the pressure control module and the temperature-humidity monitoring module are located at the wellhead at the top of the wellbore.

[0013] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, a heat exchanger and a humidification-dehumidification device are provided in the gas injection pipeline to achieve precise control of temperature and humidity.

[0014] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, the high-pressure gas injected into the salt cavern is compressed air, nitrogen or helium.

[0015] The second aspect of the present application provides a salt cavern dry-wet cycle crack repair method, which uses the above-mentioned salt cavern dry-wet cycle crack repair system for repair, including the following steps:

[0016] According to the fracture structure and damage degree of the target salt cavern surrounding rock, set appropriate gas injection and production pressure and humidity cycle parameters;

[0017] Injecting high-pressure gas into the salt cavern causes a drying effect inside the salt cavern, and then extracting gas from the salt cavern causes a humid effect inside the salt cavern;

[0018] Repeated high-frequency gas injection-gas production cycle operations are carried out alternately. By dynamically controlling the periodic dry-wet cycles in the salt cavern, the coupling effect of the air pressure, temperature and humidity inside the salt cavern is used to form a dry-wet cycle environment, as well as the airflow field and thermal gradient formed during the gas injection and production process, to complete the dynamic repair of the cracks.

[0019] For example, in the salt cavern dry-wet cycle fissure repair method provided in one embodiment, when high-pressure gas is injected into the salt cavern, the high-pressure state is maintained for several hours after the gas injection is completed; when gas is extracted from the salt cavern, the low-pressure state is maintained for several hours after the gas extraction is completed.

[0020] For example, in the salt cavern dry-wet cycle crack repair method provided in one embodiment, high-pressure gas is injected into the salt cavern through the gas injection pipeline to increase the internal pressure of the salt cavern, thereby increasing the temperature and decreasing the relative humidity in the salt cavern, and causing evaporation on the surface of the salt rock; gas is extracted from the salt cavern through the gas extraction pipeline to reduce the internal pressure of the salt cavern, thereby reducing the temperature and increasing the relative humidity in the salt cavern, and causing deliquescence-imbibition-self-healing on the surface of the salt rock.

[0021] The beneficial effects of a salt cavern dry-wet cycle crack repair system and repair method provided in some embodiments of the present application are as follows: the present application can accelerate the crack repair speed of damaged surrounding rocks in salt caverns, enhance the repair ability and improve the repair uniformity:

[0022] 1. Faster repair speed: By introducing a high-frequency dry-wet cycle process, this application significantly shortens the self-healing time of salt cavern fissures. Compared with the traditional saturated brine immersion method, it can significantly improve the sealing and mechanical properties within a few days, meeting the needs of rapid recovery in engineering.

[0023] 2. Enhanced repair ability: This application utilizes the dynamic changes in humidity in the dry-wet cycle, especially the introduced drying effect, to improve the self-healing power of salt rock, strengthen the salt transport inside the cracks and the salt rock recrystallization process, especially for surrounding rocks with severe damage and larger crack widths, and can achieve more efficient and deeper repairs.

[0024] 3. More uniform repair effect: This application controls the gas flow field and thermal gradient inside the salt cavern so that the repair effect of weak sealing links such as injection and production pipes and casing shoes is enhanced due to more intense local thermal and humidity fluctuations, ensuring the uniform sealing of the entire salt cavern structure is restored and improving the safety and stability of long-term operation.

[0025] In general, the present application is significantly superior to the existing technology in terms of repair speed, effect and applicability, and provides a more reliable and efficient solution for the sealing restoration of salt cavern energy storage projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a schematic diagram of the structure of the salt cavern dry-wet cycle fissure repair system of the present application. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] The following are the main problems existing in the existing salt cave restoration technology:

[0031] 1. The repair speed is too slow: the existing technology mainly relies on saturated brine to soak the cracks to promote the self-healing of salt rock. However, this process often takes several months to show the effect, and the repair cycle is too long to meet the demand for rapid restoration of sealing of energy storage salt caverns.

[0032] 2. Insufficient repair ability: The existing saturated brine repair method has limited effect on severely damaged surrounding rocks, especially when the crack width is large or the crack structure is complex, the self-healing ability is limited, and it is difficult to achieve effective sealing and repair.

[0033] 3. Unstable repair effect: The existing repair methods have different effects in different areas, especially in the weak sealing links such as injection and production pipes and casing shoes, which are prone to leakage. The repair effect lacks pertinence and cannot ensure that the sealing of the entire salt cavern is fully restored.

[0034] The present application provides a salt cavern dry-wet cycle crack repair method, which aims to quickly and efficiently repair cracks in salt rock surrounding rocks, thereby improving the sealing and long-term stability of the salt cavern, and includes the following steps:

[0035] According to the fracture structure and damage degree of the target salt cavern surrounding rock, appropriate gas injection and production pressure and humidity cycle parameters are set; usually, the pressure after gas injection and production is set within the allowable operating pressure range of the salt cavern, so as to effectively adjust the humidity of the salt cavern while ensuring the mechanical stability of the salt cavern.

[0036] Injecting high-pressure gas into the salt cavern causes a drying effect inside the salt cavern, and then extracting gas from the salt cavern causes a humid effect inside the salt cavern;

[0037] Repeated high-frequency gas injection-gas production cycle operations are carried out alternately. By dynamically controlling the periodic dry-wet cycles in the salt cavern, the coupling effect of the air pressure, temperature and humidity inside the salt cavern is used to form a dry-wet cycle environment, as well as the airflow field and thermal gradient formed during the gas injection and production process, to complete the dynamic repair of the cracks.

[0038] The salt cavern dry-wet cycle fissure repair method of the present application realizes dynamic repair of salt rock fissures by periodically regulating the gas humidity in the salt cavern, adopts high-frequency gas injection-gas extraction cycle operation, and utilizes the coupling effect of air pressure, temperature and humidity inside the salt cavern to form a dry-wet cycle environment, thereby accelerating the healing process of salt rock fissures.

[0039] During the gas injection process, the gas pressure and temperature in the salt cavern rise, causing the relative humidity to drop, creating a dry environment; while during the gas production process, the pressure and temperature decrease, the relative humidity rises, creating a humid environment. Through the above-mentioned periodic dry-wet changes, the processes of brine dissolution, diffusion, imbibition, evaporation and recrystallization in the cracks are accelerated, and the cracks can be quickly closed and repaired. During the injection and production process, the flow field in the salt cavern will lead to the existence of thermal gradients inside. Due to geometric distortion, the position near the injection and production pipe has the largest amplitude of gas dry-wet cycle. Among them, the junction between the casing shoe and the salt rock formation near the injection and production pipe is also a weak link in the airtightness. The higher amplitude of dry-wet cycle here will also enhance the interface healing behavior of the salt rock at this position and strengthen the overall repair effect.

[0040] The present application also provides a salt cavern dry-wet cycle crack repair system, such as Figure 1As shown, it includes a gas path channel 10, a gas injection pipeline 2, a gas production pipeline 4, a pressure control module and a temperature-humidity monitoring module, and uses the space in the wellbore 11 of the salt cavern 8 as the gas path channel 10 for gas circulation; the gas injection pipeline 2 is connected to the gas path channel 10 for injecting high-pressure gas into the salt cavern 8; the gas production pipeline 4 is connected to the gas path channel 10 for extracting gas from the salt cavern 8; the pressure control module is connected to the gas injection pipeline 2, the gas production pipeline 4 and the gas path channel 10 to control the gas injection and production pressure and adjust the injection and production gas so that the gas pressure in the salt cavern 8 changes within the allowable range; the temperature and humidity changes in the salt cavern 8 are monitored in real time through the temperature-humidity monitoring module to ensure that the relative humidity in the salt cavern 8 reaches the set target range in the dry-wet cycle, providing stable support for the dynamic healing behavior in the salt rock fissures.

[0041] A control box 3 is provided at the wellhead at the top of the wellbore 11 , and a pressure control module and a temperature-humidity monitoring module are arranged in the control box 3 . The pressure control module and the temperature-humidity monitoring module are located at the wellhead at the top of the wellbore 11 .

[0042] The gas injection pipeline 2 and the gas production pipeline 4 are arranged on the ground, and the gas injection pipeline 2 and the gas production pipeline 4 are respectively located on both sides of the injection and production port at the top of the wellbore 11.

[0043] The salt cavern 8 is located in the underground salt rock formation 6. There are sediment and brine 9 at the bottom of the salt cavern 8. The connection between the bottom of the wellbore 11 and the salt cavern 8 is the casing shoe 7. The area near the wellbore 11 and the casing shoe 7 is the geometric distortion area of ​​the salt cavern, which is also a weak sealing area and is prone to cracks.

[0044] The present application utilizes the space inside the wellbore 11 of the salt cavern 8 as the gas path 10 for gas circulation, and fully utilizes the internal space of the wellbore to create a common pipeline for gas injection and gas production, which can achieve the maximum diameter, fully reduce the friction of the gas in the pipeline, and improve the energy recovery efficiency.

[0045] For example, in the salt cavern dry-wet cycle crack repair system provided in one embodiment, Figure 1 As shown, a compressor 1 is also included, and the compressor 1 is connected to the air inlet of the air injection pipeline 2 for controlling the air injection rate.

[0046] According to the above embodiment, the high-pressure gas is injected into the underground salt cavern by using the power provided by the compressor 1 , and the gas injection rate can be adjusted by adjusting the power of the compressor 1 .

[0047] For example, in the salt cavern dry-wet cycle crack repair system provided in one embodiment, Figure 1 As shown, a turbine 5 is also included, and the turbine 5 is connected to the gas outlet of the gas production pipeline 4 for controlling the gas production rate.

[0048] According to the above embodiment, the gas extraction rate is adjusted by adjusting the turbine resistance in the turbine 5 .

[0049] Regarding temperature and humidity control, for example, in the salt cavern dry-wet cycle crack repair system provided in one embodiment, a heat exchanger and a humidification-dehumidification device are provided in the gas injection pipeline to achieve more precise temperature and humidity control, and flexibly adjust according to the size and distribution of the cracks to ensure the optimal repair effect.

[0050] For example, in the salt cavern dry-wet cycle fracture repair system provided in one embodiment, the high-pressure gas injected into the salt cavern is compressed air, or an inert gas such as nitrogen or helium.

[0051] When the salt cavern dry-wet cycle crack repair system of the present application is used for repair, the specific repair method is as follows:

[0052] Initial preparation stage: according to the fracture structure and damage degree of the target salt cavern surrounding rock, set the appropriate gas injection and production pressure and humidity cycle parameters. Usually, the pressure after gas injection and gas production is set within the allowable operating pressure range of the salt cavern, so as to effectively adjust the humidity of the salt cavern while ensuring the mechanical stability of the salt cavern.

[0053] Wet-dry cycle operation:

[0054] Step 1: Gas Injection

[0055] High-pressure gas is injected into the salt cavern 8 through the gas injection pipeline 2, and the internal pressure of the salt cavern rises rapidly, resulting in an increase in temperature, a decrease in relative humidity, and the brine in the cracks begins to evaporate. This drying stage helps to increase the supersaturation of brine in the surrounding rock cracks, promote the dissolution, migration and recrystallization of salt therein, and enhance the healing effect.

[0056] Step 2: Maintain high pressure

[0057] After the gas injection is completed, the high pressure state is maintained for several hours to ensure that the processes such as brine evaporation, salt migration and recrystallization in the fractures are fully carried out.

[0058] Step 3: Gas Collection

[0059] By releasing gas through the gas production pipeline 4, the pressure and temperature inside the salt cavern drop, and the relative humidity rises to above 90%. Extensive deliquescence will occur on the surface of the salt rock. Under the action of capillary force, the brine generated by deliquescence penetrates into the crack structure inside the salt rock, providing a solution environment for self-healing mechanisms such as salt diffusion and recrystallization in the cracks.

[0060] Step 4: Maintain low pressure

[0061] Maintaining a low-pressure environment for several hours ensures that the brine in the cracks is fully absorbed and that diffusion, mass transfer and recrystallization occur in the crack structure, thereby achieving the effect of crack healing.

[0062] By repeatedly alternating high-frequency gas injection-gas production cycles, dynamic control of the salt cavern's wet-dry cycle is achieved through high-frequency gas injection and production operations, which greatly improves the efficiency and effect of salt cavern restoration. This effectively solves the problems of slow restoration speed, limited capacity and uneven effect in existing technologies, and has broad engineering application prospects.

[0063] The salt cavern dry-wet cycle crack repair system and repair method of the present application are based on the crack self-healing acceleration technology of high-frequency dry-wet cycle. By controlling the gas pressure and humidity in the salt cavern, a periodic dry-wet cycle environment is introduced, thereby accelerating the healing processes of salt rock cracks such as diffusion mass transfer and recrystallization. Compared with the existing saturated brine static immersion repair method, the present application significantly improves the speed and effect of crack self-healing; combined with the temperature and humidity coupling control technology of gas injection and production, the present application innovatively utilizes the coupling effect between the air pressure, temperature and humidity in the salt cavern, and the drying effect during gas injection and the moist effect during gas production alternately act to accelerate the evaporation, infiltration and crystallization process of the brine in the crack, thereby improving the repair efficiency; the crack repair technology using the dynamic control of the thermal gradient and flow field in the salt cavern, by utilizing the airflow field and thermal gradient formed during the gas injection and gas production process, enhances the self-healing effect of the cracks in the geometric distortion areas close to the wellbore 11 injection and production pipes, casing shoes 7 and other areas that are also weak sealing areas, ensuring the uniformity of the repair and the integrity of the sealing recovery.

[0064] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes, and it can be fully applicable to various fields suitable for the present application. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A salt cavern dry-wet cycle crack repair system, characterized in that: include: A gas passage, wherein the gas passage is an internal space of the salt cavern shaft for gas circulation; a gas injection pipeline, connected to the gas path, for injecting high-pressure gas into the salt cavern; A gas extraction pipeline, connected to the gas path, for extracting gas from the salt cavern; A pressure control module is connected to the gas injection pipeline, the gas production pipeline and the gas path to control the gas injection and production pressure and adjust the injection and production gas so that the gas pressure in the salt cavern changes within an allowable range; The temperature and humidity monitoring module monitors the temperature and humidity changes in the salt cavern in real time to ensure that the relative humidity in the salt cavern reaches the set target range during the dry-wet cycle.

2. According to claim 1, the salt cavern dry-wet cycle crack repair system is characterized in that: A compressor is also included, and the compressor is connected to the gas inlet of the gas injection pipeline to control the gas injection rate.

3. According to claim 1, the salt cavern dry-wet cycle crack repair system is characterized in that: It also includes a turbine, which is connected to the gas outlet of the gas production pipeline and is used to control the gas production rate.

4. According to claim 1, the salt cavern dry-wet cycle crack repair system is characterized in that: The pressure control module and the temperature-humidity monitoring module are located at the wellhead at the top of the wellbore.

5. According to claim 1, the salt cavern dry-wet cycle crack repair system is characterized in that: A heat exchanger and a humidification-dehumidification device are arranged in the gas injection pipeline to realize precise control of temperature and humidity.

6. The salt cavern dry-wet cycle crack repair system according to claim 1 is characterized in that: The high-pressure gas injected into the salt cavern is compressed air, nitrogen or helium.

7. A method for repairing cracks in salt caverns by wet-dry cycles, characterized in that: The salt cavern dry-wet cycle crack repair system according to any one of claims 1 to 6 is used for repair, comprising the following steps: According to the fracture structure and damage degree of the target salt cavern surrounding rock, set appropriate gas injection and production pressure and humidity cycle parameters; Injecting high-pressure gas into the salt cavern causes a drying effect inside the salt cavern, and then extracting gas from the salt cavern causes a humid effect inside the salt cavern; Repeated high-frequency gas injection-gas production cycle operations are carried out alternately. By dynamically controlling the periodic dry-wet cycles in the salt cavern, the coupling effect of the air pressure, temperature and humidity inside the salt cavern is used to form a dry-wet cycle environment, as well as the airflow field and thermal gradient formed during the gas injection and production process, to complete the dynamic repair of the cracks.

8. The method for repairing cracks in salt caverns by wet-dry cycles according to claim 7, characterized in that: When injecting high-pressure gas into a salt cavern, the high-pressure state is maintained for several hours after the injection is completed; when extracting gas from a salt cavern, the low-pressure state is maintained for several hours after the extraction is completed.

9. The method for repairing cracks in salt caverns by wet-dry cycles according to claim 8, characterized in that: High-pressure gas is injected into the salt cavern through the gas injection pipeline to increase the internal pressure of the salt cavern, thereby increasing the temperature and decreasing the relative humidity in the salt cavern, and causing evaporation on the surface of the salt rock; gas is extracted from the salt cavern through the gas extraction pipeline to reduce the internal pressure of the salt cavern, thereby decreasing the temperature and increasing the relative humidity in the salt cavern, and causing deliquescence-imbibition-self-healing on the surface of the salt rock.

Images