A construction method for salt cavern inner wall protective material coating

Abstract

The present invention discloses a method for applying a protective coating to the inner wall of a salt cavern. This method includes applying a coupling agent to the inner wall of the salt cavern, applying the coating to the bottom layer of the inner wall, and applying the coating to the middle and top layers of the inner wall. The method boasts a rational design and is easy to operate. By adjusting the brine level and combining a special process, the coating of the strength material onto the inner wall of the salt cavern is achieved, effectively improving the internal strength of the salt cavern, alleviating localized excessive stress, and extending the service life of the salt cavern.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen energy storage, and in particular to a method for constructing a salt cavern inner wall protective material coating. Background Art

[0002] Underground storage of hydrogen has been a subject of ongoing research and exploration worldwide. Initially, hydrogen was mixed with methane at a ratio of 50-60% to create artificial gas and injected into underground reservoirs. Later, underground storage of pure hydrogen (95% hydrogen plus 3-4% carbon dioxide) was also explored. In recent years, the construction of underground salt cavern hydrogen storage systems has rapidly developed in my country, offering crucial guidance for the future storage and application of hydrogen in the country.

[0003] Currently, no existing salt caverns have undergone internal reinforcement, primarily due to difficulties in construction. Salt caverns are typically located deep in the rock formation, hundreds to thousands of meters below the surface. Unreinforced salt caverns have low internal strength and a reduced service life. Moisture inside the caverns can easily erode the rock walls, significantly shortening their lifespan. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a method for constructing a salt cavern inner wall protective material coating that prolongs the service life of the salt cavern.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a construction method of a protective material coating on the inner wall of a salt cavern, which specifically includes the following steps:

[0006] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 3 to 5 days. Introduce gas into the salt cavern filled with brine to drain some of the brine, leaving the brine at the bottom of the salt cavern.

[0007] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for a week, then add epoxy resin curing agent and let it stand for 36 to 40 hours;

[0008] S3. Carry out coating operation on the middle layer and top of the inner wall of the salt cavern.

[0009] Furthermore, the S3 specifically includes the following steps:

[0010] S31, adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water;

[0011] S32, injecting the brine coating prepared in S31 into the salt cavern, and as the brine level gradually rises, the epoxy resin in the mixed oil floating layer containing epoxy resin slowly adheres to the inner surface of the salt cavern;

[0012] S33, extracting the mixed floating oil layer: The mixed floating oil layer is extracted by water injection and drainage method. Specifically, during the water-soluble method of cavity creation, two casings are used, the inner pipe for water intake and the outer pipe for brine drainage. To drain the floating oil layer, saturated brine is first injected into the salt cavity through the inner pipe. By raising the brine level, the top of the mixed floating oil layer is finally discharged from the salt cavern.

[0013] S34, adding the curing agent floating oil layer: after the mixed floating oil layer is completely pumped out, a portion of the saturated brine is pumped out through the inner tube, and then injected into the curing agent floating oil layer through the outer tube, thus completing the addition of the curing agent floating oil layer;

[0014] S35. Inject gas into the salt cavern to drain the brine, gradually lowering the level of the curing agent floating oil layer, allowing the epoxy resin coating to combine with the curing agent and complete curing. After standing for one week, the epoxy resin solidifies into a film on the surface of the salt cavern. Finally, all surface liquid in the salt cavern is pumped out. The gas used to drain the brine is pure hydrogen, pure carbon dioxide, or a mixture of the two.

[0015] Furthermore, the gas in S1 is hydrogen, carbon dioxide, or a mixture of the two.

[0016] Furthermore, the mass ratio of the epoxy resin emulsion to the brine in S2 is (3-5):100.

[0017] Furthermore, each hundred parts of the epoxy resin emulsion in S2 includes the following raw materials in parts by weight:

[0018] 60-70 parts of high molecular weight epoxy resin

[0019] 3-5 parts emulsifier

[0020] 5-10 parts of active diluent

[0021] 5-10 parts of plasticizer

[0022] Fiber reinforcement allowance;

[0023] Among them, the high molecular weight epoxy resin is one or two of high molecular weight bisphenol A epoxy resin, high molecular weight bisphenol F epoxy resin, and high molecular weight bisphenol F / A copolymer epoxy resin, and the molecular weight of the high molecular weight epoxy resin is not less than 400 and the density is not less than 1.26 g / mL; the emulsifier is alkylphenol polyethylene oxide; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; and the fiber reinforcement material is fiber powder.

[0024] Furthermore, the fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

[0025] Furthermore, the mixed oil floating layer containing epoxy resin in S31 comprises the following raw materials in parts by weight:

[0026] 60-70 parts of low molecular weight epoxy resin

[0027] 15-20 parts of active diluent

[0028] 5-10 parts of plasticizer

[0029] 5-10 parts of fiber reinforcement material;

[0030] Among them, the low molecular weight epoxy resin is one or two of low molecular weight bisphenol A epoxy resin, low molecular weight bisphenol F epoxy resin, and low molecular weight bisphenol F / A copolymer epoxy resin, the molecular weight of the low molecular weight epoxy resin is not higher than 260 and the density is not higher than 1.26 g / mL; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; and the fiber reinforcement material is chopped fiber.

[0031] Furthermore, the fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

[0032] Furthermore, the curing agent in S35 is a small molecule polyamine curing agent soluble in water.

[0033] Furthermore, the curing agent floating oil layer in S34 is alicyclic amine or aromatic amine.

[0034] The beneficial effects of the present invention are as follows: the present invention has a reasonable design and is easy to operate. By adjusting the liquid level of the brine and combining a special process, the coating of the strength material on the inner wall of the salt cavern is achieved, which can effectively improve the strength inside the salt cavern, improve the situation of excessive local stress, and enhance the service life of the salt cavern; at the same time, it can also reduce the slow erosion of the rock wall by water vapor in the salt cavern, further increasing the service life of the salt cavern. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and examples.

[0036] Figure 1 is the process diagram of S1 in Example 1;

[0037] Figure 2 is the process diagram of S2 in Example 1;

[0038] Figure 3 is a process diagram of S32 in Example 1;

[0039] Figure 4 It is a process diagram of S34 in Example 1;

[0040] Figure 5 It is a process diagram of S35 in Example 1;

[0041] Figure: 1. Salt cavern, 2. Technical casing, 3. Surface casing, 4. Technical casing inlet and outlet valves, 5. Surface casing inlet and outlet valves, 6. Brine solution, 7. Saturated brine, 8. Epoxy resin-containing mixed oil slick, 9. Curing agent oil slick, 10. Protective material coating. DETAILED DESCRIPTION

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0043] A method for applying a protective coating to the inner wall of a salt cavern comprises the following steps:

[0044] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 3 to 5 days. Introduce gas into the salt cavern filled with brine to drain some of the brine, leaving the brine at the bottom of the salt cavern.

[0045] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for a week, then add epoxy resin curing agent and let it stand for 36 to 40 hours;

[0046] S3. Carry out coating operation on the middle layer and top of the inner wall of the salt cavern.

[0047] S3 specifically includes the following steps:

[0048] S31, adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water;

[0049] S32, injecting the brine coating prepared in S31 into the salt cavern, and as the brine level gradually rises, the epoxy resin in the mixed oil floating layer containing epoxy resin slowly adheres to the inner surface of the salt cavern;

[0050] S33, extracting the mixed floating oil layer: The mixed floating oil layer is extracted by water injection and drainage method. Specifically, during the water-soluble method of cavity creation, two casings are used, the inner pipe for water intake and the outer pipe for brine drainage. To drain the floating oil layer, saturated brine is first injected into the salt cavity through the inner pipe. By raising the brine level, the top of the mixed floating oil layer is finally discharged from the salt cavern.

[0051] S34, adding the curing agent floating oil layer: after the mixed floating oil layer is completely pumped out, a portion of the saturated brine is pumped out through the inner tube, and then injected into the curing agent floating oil layer through the outer tube, thus completing the addition of the curing agent floating oil layer;

[0052] S35. Inject gas into the salt cavern to drain the brine, gradually lowering the level of the curing agent floating oil layer, allowing the epoxy resin coating to combine with the curing agent and complete curing. After standing for one week, the epoxy resin solidifies into a film on the surface of the salt cavern. Finally, all surface liquid in the salt cavern is pumped out. The gas used to drain the brine is pure hydrogen, pure carbon dioxide, or a mixture of the two.

[0053] The gas in S1 is hydrogen, carbon dioxide, or a mixture of the two.

[0054] The mass ratio of epoxy resin emulsion to brine in S2 is (3-5):100.

[0055] Every 100 parts of epoxy resin emulsion in S2 includes the following raw materials in parts by weight:

[0056] 60-70 parts of high molecular weight epoxy resin

[0057] 3-5 parts emulsifier

[0058] 5-10 parts of active diluent

[0059] 5-10 parts of plasticizer

[0060] Fiber reinforcement allowance;

[0061] Among them, the high molecular weight epoxy resin is one or two of high molecular weight bisphenol A epoxy resin, high molecular weight bisphenol F epoxy resin, and high molecular weight bisphenol F / A copolymer epoxy resin, and the molecular weight of the high molecular weight epoxy resin is not less than 400 and the density is not less than 1.26 g / mL; the emulsifier is alkylphenol polyethylene oxide; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; the fiber reinforcement material is fiber powder; the fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

[0062] The mixed oil floating layer containing epoxy resin in S31 includes the following raw materials in parts by weight:

[0063] 60-70 parts of low molecular weight epoxy resin

[0064] 15-20 parts of active diluent

[0065] 5-10 parts of plasticizer

[0066] 5-10 parts of fiber reinforcement material;

[0067] Among them, the low molecular weight epoxy resin is one or two of low molecular weight bisphenol A epoxy resin, low molecular weight bisphenol F epoxy resin, and low molecular weight bisphenol F / A copolymer epoxy resin, and the molecular weight of the low molecular weight epoxy resin is not higher than 260 and the density is not higher than 1.26 g / mL; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; the fiber reinforcement material is chopped fiber; the fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

[0068] The curing agent in S35 is a small molecule polyamine curing agent soluble in water.

[0069] The curing agent floating oil layer in S34 is alicyclic amine or aromatic amine.

[0070] Example 1

[0071] A method for applying a protective coating to the inner wall of a salt cavern comprises the following steps:

[0072] S1. Loading of coupling agent on the inner wall of salt cavern: Add silane coupling agent into salt cavern 1 filled with brine solution 6, such as Figure 1As shown; after standing for 48 hours, the brine solution 6 is discharged, and then it is allowed to stand for 3 days; then the salt cave 1 is refilled with the brine solution 6, and gas is introduced into the salt cave 1 to discharge a portion of the brine solution 6, retaining the brine at the bottom of the salt cave, and the gas is pure hydrogen;

[0073] S2. Coating the bottom layer of the salt cavern inner wall: add epoxy resin emulsion to the undischarged brine at the bottom layer of salt cavern 1 to obtain epoxy resin emulsion brine, let it stand for one week, then add epoxy resin curing agent and let it stand for 36 hours. Figure 2 As shown; the mass ratio of epoxy resin emulsion to brine is 3:100; wherein, every 100 parts of epoxy resin emulsion includes the following parts by weight of raw materials:

[0074] 60 parts of high molecular weight bisphenol A epoxy resin

[0075] 3 parts of alkylphenol polyethylene oxide

[0076] 5 parts of phenyl glycidyl ether

[0077] 6 parts of epoxidized cardanol

[0078] 26 parts of boron fiber;

[0079] S3, coating the middle layer and top of the inner wall of the salt cavern; this step specifically includes the following steps:

[0080] S31, adding a mixed oil floating layer 8 containing epoxy resin to saturated salt water 7 to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0081] 62 parts of low molecular weight bisphenol A epoxy resin

[0082] 15 parts of phenyl glycidyl ether

[0083] 5 parts of polymerized fatty acid polyglycidyl ester

[0084] 10 parts of ultra-high molecular weight polyethylene fiber;

[0085] S32, first drain the epoxy resin emulsion brine at the bottom of the salt cavern 1, then inject the brine coating prepared in S31 into the salt cavern 1. As the brine level gradually rises, the epoxy resin in the mixed oil floating layer 8 containing epoxy resin slowly adheres to the inner surface of the salt cavern, as shown in FIG. Figure 3 As shown, the arrow direction in the figure is the direction of liquid level rising;

[0086] S33. Extracting the mixed oil floating layer: The mixed oil floating layer is extracted using a water injection and drainage method. Specifically, during the water-soluble cavity creation process, two casings are used: a technical casing 2 and a surface casing 3. The inner technical casing 2 is used for water intake, and the outer surface casing 3 is used for brine drainage. To drain the mixed oil floating layer 8 containing epoxy resin, saturated brine 7 must first be injected into the salt cavity through the inner technical casing 2. By raising the brine level, the mixed oil floating layer is eventually drained out of the salt cavern through the top of the surface casing 3. The technical casing 2 is provided with a technical casing inlet and outlet valve 4, and the surface casing 3 is provided with a surface casing inlet and outlet valve 5.

[0087] S34, adding curing agent floating oil layer: after the mixed floating oil layer is cleaned, a part of saturated brine 7 is extracted through the inner tube technical casing 2, and then injected into the curing agent floating oil layer 9 through the outer tube surface casing 3, i.e., the addition of curing agent floating oil layer is completed. Figure 4 As shown, the arrow direction in the figure is the direction of liquid level decrease;

[0088] S35, introduce gas into the salt cavern 1 to discharge the saturated brine 7, gradually lowering the liquid level of the curing agent floating oil layer 9, so that the epoxy resin coating combines with the curing agent diethylenetriamine to complete the curing; after standing for 1 week, the epoxy resin is cured to form a film on the surface of the salt cavern; and the protective material coating 10 is obtained; finally, all the surface liquid in the salt cavern is extracted, as shown in FIG. Figure 5 As shown; the gas used to discharge brine is pure hydrogen.

[0089] Example 2

[0090] A construction method for a salt cavern inner wall protective material coating, which differs from Example 1 in that:

[0091] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 3 days; introduce gas into the salt cavern filled with brine to drain some of the brine and retain the brine at the bottom of the salt cavern. The gas is pure carbon dioxide.

[0092] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 38 hours. The mass ratio of epoxy resin emulsion to brine is 4:100. Among them, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0093] 62 parts of high molecular weight bisphenol F epoxy resin

[0094] 4 parts of alkylphenol polyethylene oxide

[0095] 10 parts of cresol glycidyl ether

[0096] 5 parts of polypropylene glycol diglycidyl ether

[0097] Boron fiber 19 parts;

[0098] S31. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0099] 60 parts of low molecular weight bisphenol F epoxy resin

[0100] 17 parts of allyl glycidyl ether

[0101] 7 parts of epoxidized cardanol

[0102] 6 parts of aramid fiber;

[0103] The curing agent floating oil layer in S34 is bis(4-aminocyclohexyl)methane.

[0104] The curing agent in S35 is triethylenetetramine, and the gas used to discharge the brine is pure carbon dioxide.

[0105] Example 3

[0106] A construction method for a salt cavern inner wall protective material coating, which differs from Example 1 in that:

[0107] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 4 days; introduce gas into the salt cavern filled with brine to drain some of the brine and retain the brine at the bottom of the salt cavern. The gas is pure hydrogen.

[0108] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 37 hours. The mass ratio of epoxy resin emulsion to brine is 5:100. Among them, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0109] 65 parts of high molecular weight bisphenol F / A copolymer epoxy resin

[0110] 4 parts of alkylphenol polyethylene oxide

[0111] 8 parts of n-butyl glycidyl ether

[0112] 9 parts of polymerized fatty acid polyglycidyl ester

[0113] 14 parts of carbon fiber;

[0114] S31. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0115] 65 parts of low molecular weight bisphenol F / A copolymer epoxy resin

[0116] 17 parts of n-butyl glycidyl ether

[0117] 7 parts of epoxidized cardanol

[0118] 6 parts of glass fiber;

[0119] The curing agent floating oil layer in S34 is bis(4-aminocyclohexyl)methane.

[0120] The curing agent in S35 is triethylenetetramine, and the gas used to discharge the brine is pure carbon dioxide.

[0121] Example 4

[0122] A construction method for a salt cavern inner wall protective material coating, which differs from Example 1 in that:

[0123] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 5 days; introduce gas into the salt cavern filled with brine to drain some of the brine and retain the brine at the bottom of the salt cavern. The gas is pure carbon dioxide.

[0124] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 40 hours; the mass ratio of epoxy resin emulsion to brine is 3.5:100; wherein, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0125] 70 parts of high molecular weight bisphenol F epoxy resin

[0126] 3 parts of alkylphenol polyethylene oxide

[0127] 7 parts of allyl glycidyl ether

[0128] 7 parts of epoxidized cardanol

[0129] 13 parts of aramid fiber;

[0130] S31. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0131] 67 parts of low molecular weight bisphenol F epoxy resin

[0132] 16 parts of cresol glycidyl ether

[0133] 9 parts of polymerized fatty acid polyglycidyl ester

[0134] 7 parts of carbon fiber;

[0135] The curing agent floating oil layer in S34 is m-xylenediamine.

[0136] The curing agent in S35 is diethylenetriamine, and the gas used to discharge the brine is pure hydrogen.

[0137] Example 5

[0138] A construction method for a salt cavern inner wall protective material coating, which differs from Example 1 in that:

[0139] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 5 days; introduce gas into the salt cavern filled with brine to drain some of the brine and retain the brine at the bottom of the salt cavern. The gas is pure carbon dioxide.

[0140] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 39 hours. The mass ratio of epoxy resin emulsion to brine is 4.5:100. Among them, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0141] 68 parts of high molecular weight bisphenol A epoxy resin

[0142] 5 parts of alkylphenol polyethylene oxide

[0143] 6 parts of phenyl glycidyl ether

[0144] 10 parts of polypropylene glycol diglycidyl ether

[0145] 11 parts of glass fiber;

[0146] S31. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0147] 70 parts of low molecular weight bisphenol A epoxy resin

[0148] 18 parts of allyl glycidyl ether

[0149] 10 parts of polypropylene glycol diglycidyl ether

[0150] 5 parts of ultra-high molecular weight polyethylene fiber;

[0151] The curing agent floating oil layer in S34 is diaminodiphenyl sulfone.

[0152] The curing agent in S35 is ethylenediamine, and the gas used to discharge the brine is pure hydrogen.

[0153] Comparative Example 1

[0154] A method for coating the inner wall of a salt cavern comprises the following steps:

[0155] S1. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the salt water at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 36 hours; the mass ratio of epoxy resin emulsion to salt water is 3:100; wherein, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0156] 60 parts of high molecular weight bisphenol A epoxy resin

[0157] 3 parts of alkylphenol polyethylene oxide

[0158] 5 parts of phenyl glycidyl ether

[0159] 6 parts of epoxidized cardanol

[0160] 26 parts of boron fiber;

[0161] S2. Coating the middle layer and top of the inner wall of the salt cavern. This step specifically includes the following steps:

[0162] S21. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0163] 62 parts of low molecular weight bisphenol A epoxy resin

[0164] 15 parts of phenyl glycidyl ether

[0165] 5 parts of polymerized fatty acid polyglycidyl ester

[0166] 10 parts of ultra-high molecular weight polyethylene fiber;

[0167] S22, injecting the brine coating prepared in S31 into the salt cavern, and as the brine level gradually rises, the epoxy resin in the mixed oil floating layer containing epoxy resin slowly adheres to the inner surface of the salt cavern;

[0168] S23, extracting the mixed floating oil layer: The mixed floating oil layer is extracted by water injection and drainage method. Specifically, during the water-soluble method of cavity creation, two casings are used, the inner pipe for water intake and the outer pipe for brine drainage. To drain the floating oil layer, saturated brine is first injected into the salt cavity through the inner pipe. By raising the brine level, the top of the mixed floating oil layer is finally discharged from the salt cavern.

[0169] S24, adding the curing agent floating oil layer: after the mixed floating oil layer is completely pumped out, a portion of the saturated brine is pumped out through the inner tube, and then injected into the curing agent floating oil layer through the outer tube, thus completing the addition of the curing agent floating oil layer;

[0170] S25. Inject gas into the salt cavern to drain the brine, gradually lowering the level of the curing agent floating oil layer, allowing the epoxy resin coating to combine with the curing agent diethylenetriamine to complete the curing. After standing for 1 week, the epoxy resin solidifies into a film on the surface of the salt cavern. Finally, all the surface liquid in the salt cavern is pumped out. The gas used to drain the brine is pure hydrogen.

[0171] Comparative Example 2

[0172] A method for applying a protective coating to the inner wall of a salt cavern comprises the following steps:

[0173] S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 3 days; introduce gas into the salt cavern filled with brine to drain some of the brine and retain the brine at the bottom of the salt cavern. The gas is pure hydrogen.

[0174] S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for one week, then add epoxy resin curing agent and let it stand for 36 hours. The mass ratio of epoxy resin emulsion to brine is 3:100. Among them, every 100 parts of epoxy resin emulsion contains the following raw materials in parts by weight:

[0175] 80 parts of high molecular weight bisphenol A epoxy resin

[0176] 2 parts of alkylphenol polyethylene oxide

[0177] 2 parts of phenyl glycidyl ether

[0178] 12 parts of epoxidized cardanol

[0179] 4 parts of boron fiber;

[0180] S3, coating the middle layer and top of the inner wall of the salt cavern; this step specifically includes the following steps:

[0181] S31. Adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; wherein the mixed oil floating layer containing epoxy resin comprises the following raw materials in parts by weight:

[0182] 50 parts of low molecular weight bisphenol A epoxy resin

[0183] 10 parts of phenyl glycidyl ether

[0184] 12 parts of polymerized fatty acid polyglycidyl ester

[0185] 18 parts of ultra-high molecular weight polyethylene fiber;

[0186] S32, injecting the brine coating prepared in S31 into the salt cavern, and as the brine level gradually rises, the epoxy resin in the mixed oil floating layer containing epoxy resin slowly adheres to the inner surface of the salt cavern;

[0187] S33, extracting the mixed floating oil layer: The mixed floating oil layer is extracted by water injection and drainage method. Specifically, during the water-soluble method of cavity creation, two casings are used, the inner pipe for water intake and the outer pipe for brine drainage. To drain the floating oil layer, saturated brine is first injected into the salt cavity through the inner pipe. By raising the brine level, the top of the mixed floating oil layer is finally discharged from the salt cavern.

[0188] S34, adding the curing agent floating oil layer: after the mixed floating oil layer is completely pumped out, a portion of the saturated brine is pumped out through the inner tube, and then injected into the curing agent floating oil layer through the outer tube, thus completing the addition of the curing agent floating oil layer;

[0189] S35. Inject gas into the salt cavern to drain the brine, gradually lowering the level of the curing agent floating oil layer, allowing the epoxy resin coating to combine with the curing agent diethylenetriamine to complete the curing. After standing for 1 week, the epoxy resin solidifies into a film on the surface of the salt cavern. Finally, all the surface liquid in the salt cavern is pumped out. The gas used to drain the brine is pure hydrogen.

[0190] The uniaxial compressive strength, elastic modulus and Poisson's ratio of Examples 1 to 5 and Comparative Examples 1 to 2 were tested, and the test results are shown in Table 1.

[0191] Table 1. Test results of Examples 1 to 5 and Comparative Examples 1 to 2

[0192]

[0193] The blank examples in Table 1 refer to the test results obtained by testing a salt cavern without coating.

[0194] In summary, as can be seen from Table 1, the performance of the embodiments is better than that of the comparative example and the blank example, and can effectively improve the strength inside the salt cavern, improve the situation of excessive local stress, and enhance the service life of the salt cavern. At the same time, it can also reduce the slow erosion of the rock wall by water vapor in the salt cavern, further extending the service life of the salt cavern.

[0195] The above description only describes specific embodiments of the present invention. Various examples do not limit the essential content of the present invention. After reading the description, ordinary technicians in the relevant technical field can make modifications or variations to the specific embodiments described above without departing from the essence and scope of the invention.

Claims

1. A method for applying a protective coating to the inner wall of a salt cavern, characterized by: The specific steps include: S1. Loading the coupling agent on the inner wall of the salt cavern: Add silane coupling agent to the salt cavern filled with brine, let it stand for 48 hours, then drain the brine, and then let it stand for 3 to 5 days. Introduce gas into the salt cavern filled with brine to drain some of the brine, leaving the brine at the bottom of the salt cavern. S2. Coating the bottom layer of the salt cavern inner wall: Add epoxy resin emulsion to the undischarged brine at the bottom layer of the salt cavern, let it stand for a week, then add epoxy resin curing agent and let it stand for 36 to 40 hours; S3. Coating the middle layer and top of the inner wall of the salt cavern; Wherein, the S3 specifically includes the following steps: S31, adding a mixed oil floating layer containing epoxy resin to saturated salt water to prepare a salt water coating, wherein the mixed oil floating layer containing epoxy resin initially floats on the surface of the saturated salt water; S32, injecting the brine coating prepared in S31 into the salt cavern, and as the brine level gradually rises, the epoxy resin in the mixed oil floating layer containing epoxy resin slowly adheres to the inner surface of the salt cavern; S33, extracting the mixed floating oil layer: The mixed floating oil layer is extracted by water injection and drainage method. Specifically, during the water-soluble method of cavity creation, two casings are used, the inner pipe for water intake and the outer pipe for brine drainage. To drain the floating oil layer, saturated brine is first injected into the salt cavity through the inner pipe. By raising the brine level, the top of the mixed floating oil layer is finally discharged from the salt cavern. S34, adding the curing agent floating oil layer: after the mixed floating oil layer is completely pumped out, a portion of the saturated brine is pumped out through the inner tube, and then injected into the curing agent floating oil layer through the outer tube, thus completing the addition of the curing agent floating oil layer; S35. Inject gas into the salt cavern to drain the brine, gradually lowering the level of the curing agent floating oil layer, allowing the epoxy resin coating to combine with the curing agent and complete curing. After standing for one week, the epoxy resin solidifies into a film on the surface of the salt cavern. Finally, all surface liquid in the salt cavern is pumped out. The gas used to drain the brine is pure hydrogen, pure carbon dioxide, or a mixture of the two.

2. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: The gas in S1 is hydrogen, carbon dioxide, or a mixture of the two.

3. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: The mass ratio of the epoxy resin emulsion to the brine in S2 is (3-5):

100.

4. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: Each hundred parts of the epoxy resin emulsion in S2 includes the following raw materials in parts by weight: Among them, the high molecular weight epoxy resin is one or two of high molecular weight bisphenol A epoxy resin, high molecular weight bisphenol F epoxy resin, and high molecular weight bisphenol F / A copolymer epoxy resin, and the molecular weight of the high molecular weight epoxy resin is not less than 400 and the density is not less than 1.26 g / mL; the emulsifier is alkylphenol polyethylene oxide; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; and the fiber reinforcement material is fiber powder.

5. The method for applying a protective coating on the inner wall of a salt cavern according to claim 4, wherein: The fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

6. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: The mixed oil floating layer containing epoxy resin in S31 comprises the following raw materials in parts by weight: Among them, the low molecular weight epoxy resin is one or two of low molecular weight bisphenol A epoxy resin, low molecular weight bisphenol F epoxy resin, and low molecular weight bisphenol F / A copolymer epoxy resin, the molecular weight of the low molecular weight epoxy resin is not higher than 260 and the density is not higher than 1.26 g / mL; the active diluent is one of phenyl glycidyl ether, allyl glycidyl ether, n-butyl glycidyl ether, and cresol glycidyl ether; the plasticizer is one of epoxidized cardanol, polypropylene glycol diglycidyl ether, and polymerized fatty acid polyglycidyl ester; and the fiber reinforcement material is chopped fiber.

7. The method for applying a protective coating on the inner wall of a salt cavern according to claim 6, wherein: The fiber reinforcement material is one of glass fiber, aramid fiber, carbon fiber, ultra-high molecular weight polyethylene fiber, and boron fiber.

8. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: The curing agent in S35 is a small molecule polyamine curing agent soluble in water.

9. The method for applying a protective coating on the inner wall of a salt cavern according to claim 1, wherein: The curing agent floating oil layer in S34 is alicyclic amine or aromatic amine.

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