Novel salt cavern hydrogen storage reservoir shaft cement and preparation method and application thereof

Abstract

The invention provides novel salt-cavern hydrogen storage well shaft cement as well as a preparation method and application thereof. The novel salt-cavern hydrogen storage well shaft cement is prepared from cement, reinforced fibers, a filling material, clay, a water reducing agent and tap water, wherein the filling material is selected from one or more of fly ash, siliceous lime powder or quartz powder; the micron material is selected from one or more of micron clay, micron silica or carbon nanotubes. According to the formula of the novel salt-cavern hydrogen storage well shaft cement, the reinforced fibers, the filling material, the micron material and the water reducing agent are especially added, the advantages of all the components are fully played, all the components cooperate and interact with one another, and therefore the novel salt-cavern hydrogen storage well shaft cement has the advantages of low permeability, high mechanical strength and good crack resistance and chemical stability; and particularly, in a severe geological environment, the corrosion resistance is relatively high, so that the comprehensive performance is relatively excellent.

Description

Technical Field

[0001] This application relates to the field of cement technology, and in particular to a novel salt cavern hydrogen storage wellbore cement, its preparation method, and its application. Background Technology

[0002] Salt cavern underground hydrogen storage facilities, as a technology that stores hydrogen in salt caverns, can meet the needs of energy storage and distribution. The cement sheath in these facilities is a critical component ensuring wellbore integrity and the safety of the hydrogen storage facility. Otherwise, in harsh geological environments, salt cavern underground hydrogen storage facilities may face many challenges. For example, the salt cavern geology may contain dissolution problems, making the cement sheath highly susceptible to erosion by groundwater, leading to damage or leakage, which could threaten the integrity of the hydrogen storage facility. Secondly, the physical properties of different parts of the salt cavern underground hydrogen storage facility may vary, resulting in uneven salt cavern geology and increasing the risk of cement sheath rupture or damage in some areas. Furthermore, groundwater pressure may also exert pressure on the cement sheath, causing it to rupture or leak. Finally, the underground environment may contain chemicals such as salts and sulfides, which may threaten the chemical stability of the cement sheath, posing a risk of corrosion or degradation.

[0003] In addition to the aforementioned geological factors, existing cementing materials also have several drawbacks. For example, cement, as a brittle material, is highly susceptible to fracture due to impact or stress concentration, which can reduce the integrity of the cement sheath. Although cement is typically used to seal wellbores, it still retains some permeability in certain situations, potentially leading to leakage problems. Furthermore, cement may not be resistant to certain chemicals, especially in harsh underground environments, which could result in corrosion or degradation. Additionally, cement production typically involves high carbon emissions, failing to meet environmental protection requirements. Especially in the context of seeking more sustainable energy and materials, cement production processes need further optimization. To overcome these challenges, it is necessary to continuously improve the formulation of cementing materials, reduce carbon emissions and resource consumption, enhance their durability, chemical corrosion resistance, and sealing performance, and meet the specific requirements of underground hydrogen storage applications.

[0004] Therefore, given the problems of poor crack resistance, poor corrosion resistance, and poor stability of existing wellbore cement, there is an urgent need to provide a new salt cavern hydrogen storage wellbore cement formulation and its preparation method to improve these problems. Summary of the Invention

[0005] The main objective of this invention is to provide a novel salt cavern hydrogen storage wellbore cement, its preparation method, and its application, in order to solve the problems of poor crack resistance, poor corrosion resistance, or poor stability of existing wellbore cement.

[0006] To achieve the above objectives, according to one aspect of the present invention, a novel salt cavern hydrogen storage wellbore cement is provided, comprising: cement, reinforcing fibers, filler material, micronized material, water-reducing agent, and tap water; wherein the filler material is selected from one or more of fly ash, silica lime powder, or quartz powder; and the micronized material is selected from one or more of micronized clay, micronized silica, or carbon nanotubes.

[0007] Furthermore, the composition of the cement for the wellbore of the new salt cavern hydrogen storage facility is as follows: 100 parts cement, 1.8 to 2.2 parts micron-sized material, 23 to 26 parts filler material, 0.09 to 0.11 parts reinforcing fiber, 1.4 to 1.6 parts water-reducing agent, and 39 to 45 parts tap water.

[0008] Furthermore, the reinforcing fiber is selected from one or more of basalt fiber, carbon fiber or glass fiber; preferably, the reinforcing fiber is chopped basalt fiber.

[0009] Furthermore, the water-reducing agent is selected from one of lignin sulfonates, methacrylates, or polycarboxylates.

[0010] Furthermore, the filler material is fly ash, specifically type F fly ash.

[0011] Furthermore, the micron-sized clay is one or more of bentonite, kaolinite, illite, or montmorillonite.

[0012] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a novel salt cavern hydrogen storage wellbore cement is provided. The method includes: step S1, adding micron-sized materials to tap water for primary dispersion, then adding reinforcing fibers for secondary dispersion to obtain a dispersion; step S2, mixing cement and filler materials for primary mixing, then adding tap water and a water-reducing agent for secondary mixing to obtain a cement slurry; and step S3, adding the dispersion to the cement slurry for tertiary mixing to obtain the novel salt cavern hydrogen storage wellbore cement.

[0013] Further, in step S1, the primary dispersion includes: adding micron-sized material to tap water and stirring it in a mixer, and then performing ultrasonic treatment in an ultrasonic instrument.

[0014] Furthermore, the stirring speed for the stirring process is 3000–5000 rpm, and the stirring time is 3–5 min.

[0015] Furthermore, the ultrasonic frequency of the ultrasonic treatment is 20–100 kHz, and the ultrasonic time is 3–10 min.

[0016] Furthermore, in step S1, the secondary dispersion is performed in an ultrasonic instrument with an ultrasonic frequency of 20–100 kHz and an ultrasonic time of 3–10 min.

[0017] Furthermore, in step S1, the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

[0018] Further, in step S1, the weight ratio of micron-sized material to reinforcing fiber is (16-24):1 by weight percentage.

[0019] Further, in step S2, the mixture is mixed once in a stirrer at a speed of 100-300 rpm for 5-10 minutes.

[0020] Furthermore, in step S2, the secondary mixing is carried out in a stirrer at a speed of 100-300 rpm for 5-10 minutes.

[0021] Furthermore, in step S2, the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

[0022] Furthermore, in step S2, the amount of filler material added accounts for 23-26 wt% of the amount of cement added.

[0023] Furthermore, in step S2, the amount of water-reducing agent added accounts for 1.4 to 1.6 wt% of the amount of cement added.

[0024] Furthermore, in step S3, the three mixing processes are carried out in a stirrer at a speed of 300–500 rpm for a duration of 5–10 min.

[0025] According to another aspect of the present invention, a novel salt cavern hydrogen storage wellbore cement is provided, or the application of the salt cavern hydrogen storage wellbore cement obtained by the above-mentioned method for preparing the novel salt cavern hydrogen storage wellbore cement in the field of cementing salt cavern-type underground hydrogen storage reservoirs.

[0026] The novel salt cavern hydrogen storage wellbore cement formula prepared by applying the technical solution of this invention, especially with the addition of reinforcing fibers, fillers, micron-sized materials, and water-reducing agents, fully leverages the advantages of each component and their synergistic interaction, thereby giving the novel salt cavern hydrogen storage wellbore cement the characteristics of low permeability, high mechanical strength, good crack resistance, and excellent chemical stability. It also has good adaptability and reliability, and especially in harsh geological environments, it has strong corrosion resistance, making its overall performance superior. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. In the drawings:

[0028] Figure 1The image shows a SEM image (magnification 5000x) of the novel salt cavern hydrogen storage wellbore cement prepared according to Example 1 of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] As described in the background section of this invention, existing wellbore cements suffer from poor crack resistance, poor corrosion resistance, or poor stability. Based on this, this invention provides a novel salt cavern hydrogen storage wellbore cement comprising: cement, reinforcing fibers, filler material, micronized material, water-reducing agent, and tap water; wherein the filler material is selected from one or more of fly ash, silica lime powder, or quartz powder; and the micronized material is selected from one or more of micronized clay, micronized silica, or carbon nanotubes.

[0031] This invention addresses the problems of poor crack resistance, corrosion resistance, and stability associated with traditional wellbore cement. It improves upon traditional wellbore cement by first leveraging the high surface area and excellent surface activity of micron-sized materials. These materials can interact closely with the cement at the microscopic level, thereby improving the material's compactness and uniformity, reducing porosity, and significantly lowering the permeability of cement-based materials. Furthermore, the addition of micron-sized materials to the cement material, specifically selected from one or more of micron-sized clay, micron-sized silica, or carbon nanotubes, not only effectively prevents groundwater erosion and enhances its stability and safety, but also improves the purity and quality of hydrogen within the hydrogen storage facility during application.

[0032] Secondly, this invention utilizes the filling effect of the filler material to enhance the cohesion and compressive strength of the cement matrix, thereby enabling cement-based materials to have greater durability and a longer service life. In particular, the filler material is selected from one or more of fly ash, silica lime powder, or quartz powder, which can also effectively improve the cement-based materials' resistance to chemical erosion and increase their reliability in harsh geological environments.

[0033] Furthermore, addressing the issues of crackability and poor toughness in existing cement materials, which affect their stability and safety, this invention leverages the excellent tensile and crack-resistant properties of reinforcing fibers. These fibers form an effective reinforcing phase within cement-based materials, significantly improving their crack resistance and toughness, thus mitigating the aforementioned problems. This allows cement-based materials to better cope with internal stresses caused by the unevenness of the salt cavern structure (in the application area), preventing crack formation and propagation, and further ensuring the structural integrity and operational safety of salt cavern-type underground hydrogen storage facilities. Moreover, the addition of a water-reducing agent further optimizes the fluidity and plasticity of the cement paste, reducing water consumption. This results in cement-based materials that not only possess higher strength and durability but are also more environmentally friendly and economical.

[0034] In summary, the novel salt cavern hydrogen storage wellbore cement formula provided by this invention, especially with the addition of reinforcing fibers, fillers, micron-sized materials, and water-reducing agents, fully leverages the advantages of each component and their synergistic interaction, resulting in a novel wellbore cement characterized by low permeability, high mechanical strength, good crack resistance, and excellent chemical stability. It also exhibits good adaptability and reliability, and particularly in harsh geological environments, it demonstrates strong corrosion resistance, thus possessing superior overall performance.

[0035] In a preferred embodiment, the novel salt cavern hydrogen storage wellbore cement comprises the following components: 100 parts cement, 1.8–2.2 parts micron-sized material, 23–26 parts filler, 0.09–0.11 parts reinforcing fiber, 1.4–1.6 parts water-reducing agent, and 39–45 parts tap water. More preferably, the novel salt cavern hydrogen storage wellbore cement comprises the following components: 100 parts cement, 1.9–2.1 parts micron-sized material, 24.5–25 parts filler, 0.09–0.1 parts reinforcing fiber, 1.45–1.55 parts water-reducing agent, and 40–42 parts tap water, thereby further enhancing the synergistic effect of each component and improving the low permeability, high mechanical strength, good crack resistance, and chemical stability of the novel salt cavern hydrogen storage wellbore cement.

[0036] To further improve the crack resistance and toughness of cement, enabling cement-based materials to better cope with the internal stress caused by the uneven structure of salt caverns, prevent the generation and propagation of cracks, and further ensure the structural integrity and operational safety of salt cavern-type underground hydrogen storage facilities, the reinforcing fibers are preferably selected from one or more of basalt fibers, carbon fibers, or glass fibers; more preferably, basalt short-cut fibers.

[0037] To further improve the fluidity and plasticity of cement paste, and enhance the strength and durability of cement-based materials, the preferred water-reducing agent is one of lignin sulfonate, methacrylate, or polycarboxylate. To further enhance the cohesion and compressive strength of the cement matrix, provide cement-based materials with greater durability and longer service life, and effectively improve the ability of cement-based materials to resist chemical attack, the preferred filler is fly ash, and more preferably, type F fly ash.

[0038] To further improve the compactness and uniformity of the cement in the wellbore of the salt cavern hydrogen storage facility, reduce porosity, and thus significantly reduce the permeability of the cement-based material, thereby avoiding the risk of groundwater erosion, and also to improve the stability and safety of the salt cavern underground hydrogen storage facility, and help maintain the purity and quality of hydrogen in the facility, micron-sized clay is preferred as the micron-sized material.

[0039] Another aspect of the present invention provides a method for preparing a novel salt cavern hydrogen storage wellbore cement. The method includes: step S1, adding micron-sized materials to tap water for primary dispersion, then adding reinforcing fibers for secondary dispersion to obtain a dispersion; step S2, mixing cement and filler materials for primary mixing, then adding tap water and a water-reducing agent for secondary mixing to obtain a cement slurry; and step S3, adding the dispersion to the cement slurry for tertiary mixing to obtain the novel salt cavern hydrogen storage wellbore cement.

[0040] Those skilled in the art first add micron-sized materials to tap water for a primary dispersion treatment, then add reinforcing fibers for a secondary dispersion treatment to obtain a dispersion. Next, cement and filler materials are mixed once, then tap water and a water-reducing agent are added for a secondary mixing treatment to obtain a cement slurry. Finally, the dispersion is added to the cement slurry for a tertiary mixing treatment, ultimately yielding a novel salt cavern hydrogen storage wellbore cement. This novel salt cavern hydrogen storage wellbore cement formulation, especially with the addition of reinforcing fibers, filler materials, micron-sized materials, and a water-reducing agent, fully leverages the advantages of each component and their synergistic effects, resulting in low permeability, high mechanical strength, good crack resistance, and excellent chemical stability. It also exhibits good adaptability and reliability, especially in harsh geological environments, demonstrating strong corrosion resistance, thus resulting in superior overall performance.

[0041] In a preferred embodiment, step S1, the primary dispersion includes: adding micron-sized material to tap water and stirring it in a mixer, and then performing ultrasonic treatment in an ultrasonic instrument to ensure that the micron-sized material is evenly and stably dispersed in the tap water. More preferably, the stirring speed for the stirring treatment is 3000-5000 rpm and the stirring time is 3-5 min, more preferably, the stirring speed is 4000-5000 rpm and the stirring time is 4-5 min; the ultrasonic frequency for the ultrasonic treatment is 20-100 kHz and the ultrasonic time is 3-10 min.

[0042] To further ensure that the reinforcing fibers are evenly dispersed in tap water containing micron-sized materials, in step S1, secondary dispersion is carried out in an ultrasonic instrument. Preferably, the ultrasonic frequency is 20-100 kHz and the ultrasonic time is 3-10 min. More preferably, the ultrasonic frequency is 80-100 kHz and the ultrasonic time is 4-5 min. Preferably, the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

[0043] In a preferred embodiment, the weight ratio of micron-sized material to reinforcing fiber is (16-24):1, more preferably (19-23):1, which gives the wellbore cement for salt cavern hydrogen storage a low permeability, high mechanical strength, good crack resistance and excellent chemical stability. It also has good adaptability and reliability, and strong corrosion resistance, especially in harsh geological environments.

[0044] To further improve the uniformity and stability of the cement paste, and to ensure that each component functions effectively and coordinates with the others to improve the overall performance of the cement, it is preferable that in step S2, the first mixing is carried out in a mixer at a speed of 100-300 rpm for 5-10 min; it is also preferable that the second mixing is carried out in a mixer at a speed of 100-300 rpm for 5-10 min; more preferably, the speed of mixing is 200-300 rpm for 8-10 min; and it is even more preferable that the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

[0045] In order to further improve the cohesion and compressive strength of the new cement, bring it stronger durability and longer service life, further effectively improve the ability of cement-based materials to resist chemical erosion, and increase its application reliability in harsh geological environments, the preferred amount of filler material is 23-26 wt% of the cement content, more preferably 24.5-25 wt%.

[0046] In order to further improve the fluidity and plasticity of cement paste, reduce water consumption, and make the new cement not only have higher strength and better durability, but also be more environmentally friendly and economical, the preferred amount of water-reducing agent is 1.4 to 1.6 wt% of the cement content, and more preferably 1.45 to 1.55 wt%.

[0047] In a preferred embodiment, in step S3, the mixing is carried out three times in a mixer at a stirring speed of 300-500 rpm for 5-10 min, more preferably at a stirring speed of 400-500 rpm for 8-10 min. This results in the new salt cavern hydrogen storage wellbore cement having the characteristics of low permeability, high mechanical strength, good crack resistance and excellent chemical stability, as well as good adaptability and reliability, especially in harsh geological environments, enhancing its corrosion resistance.

[0048] Another aspect of the present invention provides a novel salt cavern hydrogen storage wellbore cement, or the application of the salt cavern hydrogen storage wellbore cement obtained by the above-mentioned method for preparing the novel salt cavern hydrogen storage wellbore cement in the field of cementing salt cavern-type underground hydrogen storage reservoirs.

[0049] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0050] Example 1

[0051] First, add 2 parts of micronized clay to 20 parts of tap water, stir at 5000 rpm for 5 minutes, and then ultrasonically vibrate for 10 minutes at a frequency of 100 kHz to ensure the micronized clay is fully dispersed, obtaining a micronized clay (bentonite) suspension. Then, add 0.1 parts of basalt chopped fibers and ultrasonically vibrate for another 10 minutes at a frequency of 100 kHz to obtain a dispersion. Mix 100 parts of cement with 25 parts of grade F fly ash in a mixer for 10 minutes at 300 rpm, then add 20 parts of tap water and 1.5 parts of a water-reducing agent (lignosulfonate), and stir at 300 rpm for 5 minutes to initially prepare a cement slurry. Finally, add the above dispersion and stir at 500 rpm for 10 minutes to obtain a novel salt cavern hydrogen storage wellbore cement. The composition of the cement for this novel salt cavern hydrogen storage wellbore is as follows: 100 parts cement, 2 parts micron-sized material, 25 parts filler, 0.1 parts reinforcing fiber, 1.5 parts water-reducing agent, and 40 parts tap water. Finally, it is cured in a curing chamber for 28 days. Figure 1 Here is the SEM image of the cement.

[0052] Comparative Example 1

[0053] Mix 100 parts cement with 40 parts tap water, stir at 300 rpm for 5 minutes, then stir at 500 rpm for 10 minutes to obtain cement paste. Finally, cure in a curing chamber for 28 days.

[0054] Comparative Example 2

[0055] First, add 2 parts of micronized clay to 20 parts of tap water, stir at 5000 rpm for 5 minutes, and then ultrasonically vibrate for 10 minutes at a frequency of 100 kHz to ensure the micronized clay is fully dispersed, resulting in a micronized clay suspension. Mix 100 parts of cement with 25 parts of F-grade fly ash, and mix in a mixer for 10 minutes at 300 rpm. Then add 20 parts of tap water and 1.5 parts of water-reducing agent, and stir at 300 rpm for 5 minutes to initially prepare a cement slurry. Finally, add the above dispersion to the slurry and stir at 500 rpm for 10 minutes to obtain a novel salt cavern hydrogen storage wellbore cement. The composition of this novel salt cavern hydrogen storage wellbore cement is as follows: 100 parts cement, 2 parts micronized material, 25 parts filler material, 0.1 parts reinforcing fiber, 1.5 parts water-reducing agent, and 40 parts tap water. Finally, cure in a curing chamber for 28 days.

[0056] Comparative Example 3

[0057] First, 2 parts of micronized clay were added to 20 parts of tap water and stirred at 5000 rpm for 5 minutes. Then, the mixture was ultrasonically vibrated for 10 minutes at a frequency of 100 kHz to ensure thorough dispersion of the micronized clay, resulting in a micronized clay suspension. Next, 0.1 parts of basalt chopped fibers were added, and the mixture was ultrasonically vibrated for another 10 minutes at a frequency of 100 kHz to obtain a dispersion. 100 parts of cement were added to 20 parts of tap water and 1.5 parts of water-reducing agent, and stirred at 300 rpm for 5 minutes to initially prepare a cement slurry. Finally, the above dispersion was added, and the mixture was stirred at 500 rpm for 10 minutes to obtain a novel salt cavern hydrogen storage wellbore cement. The composition of this novel salt cavern hydrogen storage wellbore cement is as follows: 100 parts cement, 2 parts micronized material, 25 parts filler material, 0.1 parts reinforcing fiber, 1.5 parts water-reducing agent, and 40 parts tap water. Finally, the cement was cured in a curing chamber for 28 days.

[0058] Comparative Example 4

[0059] First, 0.1 parts of basalt chopped fibers were added to 20 parts of tap water and stirred at 5000 rpm for 5 minutes, followed by ultrasonic vibration for 10 minutes at a frequency of 100 kHz to obtain a dispersion. Then, 100 parts of cement and 25 parts of F-grade fly ash were mixed and stirred in a mixer for 10 minutes at 300 rpm. Next, 20 parts of tap water and 1.5 parts of water-reducing agent were added, and the mixture was stirred at 300 rpm for 5 minutes to initially prepare a cement slurry. Finally, the above dispersion was added to the slurry, and the mixture was stirred at 500 rpm for 10 minutes to obtain a novel salt cavern hydrogen storage wellbore cement. The composition of this novel salt cavern hydrogen storage wellbore cement is as follows: 100 parts cement, 2 parts micron-sized material, 25 parts filler, 0.1 parts reinforcing fiber, 1.5 parts water-reducing agent, and 40 parts tap water. Finally, the cement was cured in a curing chamber for 28 days.

[0060] Performance testing:

[0061] 1) Mechanical properties:

[0062] Sample Size: Use cubic specimens with sides of 150 mm. Quantity: At least 3 specimens for each test age (7 days and 28 days). Specimens should be cured under standard curing conditions (temperature 20±2℃, relative humidity not less than 95%). Compression Testing Machine: Meets the accuracy requirements of relevant standards (e.g., ISO 679). Testing Procedure: At 28 days, remove the specimens from the curing chamber and wipe off surface moisture; place the specimens in the compression testing machine and apply uniform pressure until the specimen fails. Record the maximum load at failure. Calculate the compressive strength using the formula: maximum load / specimen area under pressure.

[0063] 2) Permeability and porosity testing:

[0064] Specimen Preparation: Before testing, the specimen needs to be prepared. Secure the specimen with a rigid material to prevent slippage or deformation during testing. Clean the specimen surface thoroughly, ensuring it is free of impurities and coatings. Operating Procedures: Insert a syringe into the probe head to inflate the probe's air bladder. Place the probe firmly against the specimen surface and open the instrument's valve. After a period of stabilization, record the internal pressure value. Based on the readings, concrete performance indicators such as permeability and porosity can be calculated using appropriate formulas.

[0065] 3) Corrosion resistance test:

[0066] Preparation of the test solution: Prepare a 5% sodium sulfate (Na₂SO₄) solution according to ASTM C1012, maintaining the solution temperature at 23±2℃. Immersion of the specimen: Immerse the cured specimen in the prepared sulfate solution. The specimen should be completely submerged in the solution and maintained under constant environmental conditions, typically 23±2℃. Observation and recording: Periodically check the length change of the specimen using vernier calipers. Measurements should be taken weekly. Evaluation of results: Record the length change of the specimen during immersion ("+" indicates growth, "-" indicates shortening). The length change data is used to evaluate the sulfate resistance of the cement mortar.

[0067] The products prepared in the above embodiments and comparative examples were subjected to the above performance tests, and the test results are shown in Table 1.

[0068] Table 1

[0069] Compressive strength (MPa) Permeability (μD) 8-week length change (%) Example 1 68±4 6±2 +0.007 Comparative Example 1 67±2 97±67 +0.009 Comparative Example 2 59±7 23±6 +0.012 Comparative Example 3 61±3 38±9 +0.015 Comparative Example 4 68±4 31±4 +0.011

[0070] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0071] Compared with the comparative test results, the embodiments of the present invention show that the new salt cavern hydrogen storage wellbore cement formula provided by the present invention, especially the addition of reinforcing fibers, fillers, micron-sized materials and water-reducing agents, fully leverages the advantages of each component and their synergistic interaction. As a result, the new salt cavern hydrogen storage wellbore cement has the characteristics of low permeability, high mechanical strength, good crack resistance and excellent chemical stability. It also has good adaptability and reliability, especially in harsh geological environments, where it has strong corrosion resistance, making its overall performance superior.

[0072] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather are primarily intended to describe features of specific embodiments of a particular invention. Certain features described in the various embodiments herein may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented separately in various embodiments or in any suitable sub-combination. Furthermore, while features may function in certain combinations as described above and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and a claimed combination may refer to a sub-combination or a variation thereof.

[0073] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or sequentially, or requiring all illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0074] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A novel type of cement for salt cavern hydrogen storage wellbore, characterized in that, The novel salt cavern hydrogen storage wellbore cement comprises: cement, reinforcing fibers, filler material, micronized material, water-reducing agent, and tap water; wherein, the filler material is selected from one or more of fly ash, silica lime powder, or quartz powder; and the micronized material is selected from one or more of micronized clay, micronized silica, or carbon nanotubes.

2. The novel salt cavern hydrogen storage wellbore cement according to claim 1, characterized in that, The composition of the new salt cavern hydrogen storage wellbore cement is as follows: 100 parts of the cement, 1.8 to 2.2 parts of the micron material, 23 to 26 parts of the filler material, 0.09 to 0.11 parts of the reinforcing fiber, 1.4 to 1.6 parts of the water-reducing agent, and 39 to 45 parts of tap water.

3. The novel salt cavern hydrogen storage wellbore cement according to claim 1 or 2, characterized in that, The reinforcing fiber is selected from one or more of basalt fiber, carbon fiber, or glass fiber; and / or The reinforcing fiber is basalt short-cut fiber.

4. The novel salt cavern hydrogen storage wellbore cement according to any one of claims 1 to 3, characterized in that, The water-reducing agent is selected from one of lignin sulfonates, methacrylates, or polycarboxylates.

5. The novel salt cavern hydrogen storage wellbore cement according to any one of claims 1 to 4, characterized in that, The filling material is fly ash, and the fly ash is type F fly ash.

6. The novel salt cavern hydrogen storage wellbore cement according to claim 1, characterized in that, The micron-sized clay is selected from one or more of bentonite, kaolinite, illite, or montmorillonite.

7. A method for preparing a novel salt cavern hydrogen storage wellbore cement according to any one of claims 1 to 6, characterized in that, The preparation method includes: Step S1: After adding micron-sized materials to tap water for primary dispersion, reinforcing fibers are added for secondary dispersion to obtain a dispersion. Step S2: After mixing cement and filler materials once, add tap water and water-reducing agent for a second mixing to obtain cement paste; Step S3: Add the dispersion to the cement slurry and mix three times to obtain the novel salt cavern hydrogen storage wellbore cement.

8. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S1, the primary dispersion includes: adding micron-sized materials to the tap water, stirring in a mixer, and then performing ultrasonic treatment in an ultrasonic instrument.

9. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 8, characterized in that, The stirring speed for the stirring process is 3000-5000 rpm, and the stirring time is 3-5 min.

10. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 8, characterized in that, The ultrasonic frequency of the ultrasonic treatment is 20–100 kHz, and the ultrasonic time is 3–10 min.

11. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S1, the secondary dispersion is performed in an ultrasonic instrument with an ultrasonic frequency of 20-100 kHz and an ultrasonic time of 3-10 min.

12. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S1, the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

13. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S1, the weight ratio of the micron material to the reinforcing fiber is (16-24):1 by weight percentage.

14. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S2, the initial mixing is carried out in a mixer at a speed of 100-300 rpm for 5-10 minutes.

15. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S2, the secondary mixing is carried out in a stirrer at a speed of 100-300 rpm for 5-10 minutes.

16. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S2, the amount of tap water added accounts for 50 wt% of the total amount of tap water added.

17. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S2, the amount of filler material added accounts for 23-26 wt% of the amount of cement added.

18. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S2, the amount of water-reducing agent added accounts for 1.4 to 1.6 wt% of the amount of cement added.

19. The method for preparing the novel salt cavern hydrogen storage wellbore cement according to claim 7, characterized in that, In step S3, the three mixing processes are carried out in a stirrer at a speed of 300-500 rpm for 5-10 minutes.

20. The application of a novel salt cavern hydrogen storage wellbore cement according to any one of claims 1 to 6, or the salt cavern hydrogen storage wellbore cement obtained by the preparation method of the novel salt cavern hydrogen storage wellbore cement according to any one of claims 7 to 19, in the field of cementing salt cavern-type underground hydrogen storage reservoirs.

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