A method for mineralizing and plugging fissures in a hydrogen storage caprock based on microorganisms and composite materials

Abstract

The present invention belongs to the technical field of mineralization for repairing rock layer fractures, and specifically relates to a method for mineralizing and plugging fractures in a hydrogen storage caprock based on microorganisms and composite materials. It includes S100 pouring the prepared fly ash fluid into a part of the hydrogen storage caprock; S200 pouring the composite fluid composed of the prepared standard sand and granular activated carbon into a part of the hydrogen storage caprock; S300 obtaining a mineralized microbial liquid after activating and expanding the mineralized microbial strains through a liquid culture medium; S400 preparing a cementing liquid by adding urea and calcium lactate to water, fully mixing the mineralized microbial liquid with the cementing liquid to form a mixed microbial liquid, and pouring the prepared mixed microbial liquid into a part of the hydrogen storage caprock; S500 simulating the actual formation environment in the laboratory and supplementing the cementing liquid to the hydrogen storage caprock according to the experimental results. The present invention solves the problems of the diffusion and leakage of stored hydrogen caused by the original pore fractures in the hydrogen storage caprock, as well as the sealing and integrity of the hydrogen storage caprock.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineralization repair of rock layer fractures, and specifically relates to a method for mineralizing and plugging fractures in a hydrogen storage caprock based on microorganisms and composite materials. Background Art

[0002] With the significant breakthrough achievements in the technology of producing hydrogen from seawater without desalination in China's offshore areas, hydrogen, with its advantages of being clean, pollution-free, highly efficient and renewable, not only promotes the important strategic development of the transformation from fossil energy to clean energy, but also the comprehensive utilization of hydrogen energy will further become an important node in the transformation of human beings from resource-based "energy development" to technology-based "energy creation". At the same time, due to problems such as the wide explosion limit range of hydrogen and the difficulty of storage and transportation, large-scale underground hydrogen storage has gradually attracted attention. Underground hydrogen storage reservoirs are usually located in strata hundreds to thousands of meters underground, and generally include three types: salt caverns, aquifers and depleted oil and gas reservoirs. Depleted oil and gas reservoirs are considered to be the most potential underground hydrogen storage geological structures due to their large storage space and small degree of mining damage. In China, depleted oil and gas reservoirs are widely distributed, mainly concentrated in the northwest, north and northeast regions, geographically matching oil and gas fields and green power industries. Geologically, after comprehensive exploration and development of oil and gas, the information is completely preserved, and surface and underground facilities can be directly put into use, reducing the initial geological exploration and infrastructure investment.

[0003] However, to achieve efficient storage and production of hydrogen in depleted oil and gas reservoirs, it is required that the hydrogen storage caprock has good integrity and sealing performance to prevent economic losses caused by the outward diffusion of hydrogen. At the same time, due to the long-term storage of hydrogen and cyclic injection and production, the pressure in the hydrogen storage caprock will fluctuate, which may activate the original pore fractures that block the migration of reservoir fluids, or cause the dredging and expansion of the original pore structure, making the structure of the hydrogen storage caprock become loose, becoming a potential channel for hydrogen diffusion and leakage, and affecting the stability of the reservoir. Therefore, it is very necessary to enhance the sealing performance and integrity of the hydrogen storage caprock through plugging. However, traditional mud plugs may not be able to fully penetrate and completely seal micro-pores due to the influence of moisture content, viscosity, etc., resulting in a low success rate of plugging. Summary of the Invention

[0004] The present invention aims to solve the problems of the diffusion and leakage of stored hydrogen caused by the original pore fractures in the hydrogen storage caprock, and the problem of the pressure cyclic disturbance caused by the cyclic injection and production of hydrogen on the sealing performance and integrity of the hydrogen storage caprock, and provides a method for mineralizing and plugging fractures in a hydrogen storage caprock based on microorganisms and composite materials.

[0005] The present invention adopts the following technical solutions: A method for mineralizing and plugging fractures in a hydrogen storage caprock based on microorganisms and composite materials, comprising:

[0006] S100: Pour the prepared fly ash fluid into a part of the hydrogen storage caprock;

[0007] S200: After the fly ash fluid is completely poured, and the fracture structure in the hydrogen storage caprock is fully wetted, pour the composite fluid composed of the prepared standard sand and granular activated carbon into the hydrogen storage caprock part;

[0008] S300: Select mineralizing microbial strains, and after activation and amplification culture of the mineralizing microbial strains in a liquid medium, obtain a mineralizing microbial liquid;

[0009] S400: Add urea and calcium lactate to water to prepare a cementing liquid, fully mix the mineralizing microbial liquid with the cementing liquid to form a mixed microbial liquid, and pour the prepared mixed microbial liquid into the hydrogen storage caprock part;

[0010] S500: Simulate the actual formation environment in the laboratory, implement steps S100 - S300 on the actual formation environment simulated in this laboratory, and supplement the cementing liquid to the hydrogen storage caprock according to the experimental results.

[0011] In some embodiments, in step S100, the particle size range of fly ash in the fly ash fluid is 0.5 - 300 μm, and the density range is 1.4 g / cm 3 ~1.8 g / cm 3 。

[0012] In some embodiments, in step S200, the particle size range of the standard sand is 0.075 mm - 2 mm, the particle size range of the granular activated carbon is above 0.175 mm, and the density range of the composite fluid is 1.8 g / cm 3 ~2.2 g / cm 3 。

[0013] In some embodiments, in step S300, the mineralizing microbial strain selected is Sporosarcina pasteurii.

[0014] In some embodiments, in step S400, the ratio of the cementing liquid is urea and calcium lactate at 1:1. Among them, urea is used as the substrate for biological metabolic reactions, and calcium lactate is used as a nutrient and a Ca source.

[0015] In some embodiments, step S500 includes:

[0016] S501: Select a rock sample in the hydrogen storage caprock with a relatively large volume as the laboratory reference object, simulate the actual formation environment in the laboratory, convert the required volume of the mixed microbial liquid and the composite fluid to be poured according to the equal - proportion conversion of the exploration volume of the hydrogen storage caprock and the volume of the selected rock sample, and implement steps S100 - S300 on this rock sample;

[0017] S502: Use experimental means to regularly detect the cementing and repair degree of the loose particles and the original fractures in the rock sample;

[0018] S503: According to the implementation results of the rock samples, the cementing fluid is replenished into the hydrogen storage caprock multiple times.

[0019] In some embodiments, in step S501, according to the exploration volume of the hydrogen storage caprock and the volume of the selected rock samples, the conversion formula for the required volume of the mixed bacterial liquid and the composite fluid to be infused is as follows:

[0020]

[0021] In the formula: V1 represents the volume of the hydrogen storage caprock, m 3 ;

[0022] V2 represents the volume of the laboratory rock sample, m 3 ;

[0023] V1' represents the volume of the mixed bacterial liquid infused into the hydrogen storage caprock, m 3 ;

[0024] V2' represents the volume of the mixed bacterial liquid infused into the laboratory rock sample, m 3 ;

[0025] V1'' represents the volume of the composite fluid infused into the hydrogen storage caprock, m 3 ;

[0026] V2'' represents the volume of the composite fluid infused into the laboratory rock sample, m 3 .

[0027] In some embodiments, step S502 includes regularly detecting the parameters of the porosity, pore size distribution, and permeability of the rock sample by using experimental means such as CT scanning, BET specific surface area tester, and core permeability tester to describe the cementing and repair degree of the granular materials and the primary fractures in the rock sample.

[0028] In some embodiments, the hydrogen storage caprock is the upper rock layer of an exhausted oil and gas reservoir.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The method for mineralizing and plugging the fractures of the hydrogen storage caprock based on Sporosarcina pasteurii and composite fluid materials proposed by the present invention utilizes the strong cementing effect of the organic matter secreted by microorganisms, which can combine with the generated CaCO3 and adhere to the composite material and the inner wall of the fracture. By continuously generating CaCO3 and its expansibility, the fractures are gradually filled, making the entire caprock structure dense, thereby reducing the permeability of the caprock and ultimately achieving the goal of plugging and repairing the fractures. Furthermore, it hinders the loss caused by the outward diffusion and leakage of hydrogen through the caprock fractures. At the same time, due to the densification of the hydrogen storage caprock structure, its compressive, shear, and anti-disturbance capabilities are enhanced, ensuring the structural safety of hydrogen geological storage.

[0031] Compared with plugging pores with traditional fluid materials such as cement and mud, the self-healing ability of microorganisms is increased, avoiding the repeated plugging work of secondary cracks caused by pressure disturbance of the hydrogen storage caprock after traditional plugging, and the problem that traditional plugging fluids are difficult to reach micro-pores; compared with plugging cracks with the fluid of Bacillus pasteurii composite geotechnical materials, the urease produced by Sarcina pasteurii has higher urea degradation activity and almost reaches the maximum value of known species. Moreover, Sarcina pasteurii is an alkaliphilic bacterium and can produce spores that can remain dormant for decades and survive in harsh environments for several years until cracks appear, and then the cementing fluid can be injected again to activate its function.

[0032] The present invention proposes to select fly ash material as the first-injected fluid to plug micro-pores, which can effectively utilize the characteristics of fly ash, realize the plugging of micro-pores while making full and effective use of solid waste.

[0033] The different-particle-size composite fluid for plugging cracks proposed by the present invention first injects fly ash fluid to plug micro-pores, and then injects a composite fluid of standard sand and granular activated carbon with different particle sizes to plug larger cracks, which can form a dense "filter type" structure from large pores to small pores with large-particle-size fillers to small-particle-size fillers, and can reduce the fluid loss caused by the relatively low viscosity of the mixed bacterial solution to a certain extent.

[0034] The different-particle-size composite fluid for plugging cracks proposed by the present invention can realize the hierarchical use of fluids, improve the material utilization rate, avoid excessive material injection into the hydrogen storage caprock caused by completely filling with small particles, and also avoid the gaps between particles caused by completely filling with large particles, and prolong the time of mineralization plugging.

[0035] The addition of activated carbon in the composite fluid proposed in the present invention can utilize its good adsorption performance to provide adsorption sites for Sarcina pasteurii, reducing the loss of the quantity of Sarcina pasteurii caused by flow.

[0036] The urea and calcium lactate cementing fluid proposed in the present invention, compared with the existing urea and CaCl2 formula, replaces CaCl2 with calcium lactate as the bacterial nutrient and Ca 2+ raw material, which can avoid the reduction of bacterial activity and the death caused by the lack of nutrients in the caprock rock mass. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the mineralization plugging of cracks in the hydrogen storage caprock by Sarcina pasteurii and composite fluid materials;

[0038] Figure 2 It is a flowchart of the method for mineralization plugging of cracks in the hydrogen storage caprock by Sarcina pasteurii and composite fluid materials. DETAILED DESCRIPTION OF THE INVENTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] As Figure 2 shown, a method for mineralizing and plugging fissures in a hydrogen storage caprock based on microorganisms and composite materials includes:

[0041] S100: Pour the prepared fly ash fluid into a part of the hydrogen storage caprock, where the hydrogen storage caprock is located more than 800 meters underground, specifically described as the upper rock layer of an exhausted oil and gas reservoir;

[0042] Specifically, in step S100, the particle size range of fly ash in the fly ash fluid is 0.5 - 300 μm, and the prepared fly ash material with a density range of 1.4 g / cm 3 ~1.8 g / cm 3 is used as the first injection fluid.

[0043] S200: After the fly ash fluid injection is completed and the fissure structure in the hydrogen storage caprock is fully wetted, pour the prepared composite fluid composed of standard sand and granular activated carbon into the hydrogen storage caprock part.

[0044] In some embodiments, in step S200, the particle size range of the standard sand is 0.075 mm - 2 mm, the particle size range of the granular activated carbon is more than 0.175 mm, and the prepared fluid concentration range is 1.8 g / cm 3 ~2.2 g / cm 3 .

[0045] Fly ash is the fine ash collected from the flue gas after coal combustion and is the main solid waste discharged from coal-fired power plants. A large amount of fly ash will generate dust in the air, polluting the atmosphere; if discharged into water systems, it will cause river siltation, and the toxic chemical substances in it will harm humans and organisms. Its main oxide components are: SiO2, Al2O3, FeO, Fe2O3, CaO, TiO2, etc. These active components can chemically react with water to produce gelling substances, which is beneficial to the sealing of the fissure structure. At the same time, since the main components of fly ash are SiO2 and Al2O3, both have good hydrophilicity, and the particle sizes of SiO2 and Al2O3 in fly ash are extremely small, which can be adsorbed on the surface of the fissures in the hydrogen storage caprock to improve the wettability of the hydrogen storage caprock, facilitating the subsequent injection of fluids. At the same time, fly ash contains Ca elements, which can provide a Ca source for the mineralization reaction.

[0046] S300: Sporesarcinia pasteuriana is selected as the mineralizing microbial strain, and the mineralizing microbial strain is activated and expanded in a liquid culture medium to obtain a mineralizing microbial bacterial solution.

[0047] S400: adding urea and calcium lactate into water to prepare a cementing liquid, fully mixing the mineralized microbial liquid with the cementing liquid to form a mixed liquid, and injecting the prepared mixed liquid into the hydrogen storage cap layer.

[0048] Specifically, the binder liquid contains urea and calcium lactate in a ratio of 1:1, wherein urea serves as a substrate for biological metabolic reactions and calcium lactate serves as a nutrient and a Ca source.

[0049] The strong cementing effect of the organic matter secreted by Bacillus pasteurianus can be combined with the generated CaCO3 and adhered to the composite material and the inner wall of the crack. The cracks are gradually filled by continuously producing CaCO3 and its expansion property, making the entire caprock structure dense.

[0050] The urease produced by Sporosarcina pasteurianum has a higher urea degradation activity and almost reaches the maximum value of known species. Sporosarcina pasteurianum is an alkaliphilic bacterium and can produce spores that remain dormant for decades and survive in harsh environments for several years until cracks appear, and then cementing fluid can be injected again to activate its function.

[0051] S500: simulating an actual formation environment in a laboratory, and performing steps S100 to S300 on the actual formation environment simulated in the laboratory, and replenishing a cementing fluid into the hydrogen storage cap layer according to the experimental results.

[0052] like Figure 1 As shown, the implementation of this embodiment mainly relies on the fluid and binder liquid injection device 1, which is used to apply pressure to the fluid through a pump so that it can fully reach the pore and fracture structure deep in the hydrogen storage cap layer, wherein the pipeline is used to connect the pump body and the hydrogen storage cap layer and transport the fluid.

[0053] Specifically, step S500 includes:

[0054] S501: Select a rock sample from a hydrogen storage caprock with a relatively large volume as a laboratory reference object, simulate the actual formation environment in the laboratory, convert the volume of the mixed bacterial solution and the volume of the composite fluid required for injection in proportion to the volume of the hydrogen storage caprock exploration and the volume of the selected rock sample, and perform the steps S100 to S300 on the rock sample. The conversion formula is as follows:

[0055]

[0056] Where: V1 represents the volume of hydrogen storage cap layer, m 3 ;

[0057] V2 represents the volume of the laboratory rock sample, m 3 ;

[0058] V1’ represents the volume of the mixed bacterial solution injected into the hydrogen storage caprock, m 3 ;

[0059] V2’ represents the volume of the mixed bacterial solution injected into the laboratory rock sample, m 3 ;

[0060] V1’’ represents the volume of the composite fluid injected into the hydrogen storage caprock, m 3 ;

[0061] V2’’ represents the volume of the composite fluid injected into the laboratory rock sample, m 3 .

[0062] S502: Regularly detect the cementation and repair degree of the bulk particles and primary fractures in the rock sample by experimental means;

[0063] Use experimental means such as CT scanning, BET specific surface area tester, and core permeability tester to regularly detect the porosity, pore size distribution, and permeability parameters of the rock sample to describe the cementation and repair degree of the bulk particles and primary fractures in the rock sample. The improvement of the cementation and repair degree is reflected inside the rock sample, manifested as a decrease in the overall porosity, the pore size distribution will mainly concentrate in micropores, and with the passage of time, the number of pores of various pore sizes will continue to decrease, resulting in a significant decrease in the overall permeability, which is not conducive to the diffusion of fluids. When it is found through experimental monitoring that the cementation and repair process of the primary pores in the rock sample becomes slow, it can be judged that it is necessary to continue adding the cementing liquid.

[0064] The promotion rate of the cementation and repair degree of the bulk particles and primary fractures in the hydrogen storage caprock often decreases with the extension of time. The main reason is that with the extension of time, the concentration of the cementing liquid inside the hydrogen storage caprock decreases, the nutrients for maintaining the growth and development of microorganisms gradually disappear, the concentration of the bacterial substrate for cementation and repair decreases, and the mineralization reaction process of microorganisms stagnates. At the same time, since the laboratory reference rock sample used in this application has a large volume and is representative to a certain extent, it can reflect the cementation and repair degree in the actual hydrogen storage caprock. Therefore, when it is found through experimental monitoring that the cementation and repair process of the primary pores in the rock sample becomes slow, it can be judged that it is necessary to continue adding the cementing liquid.

[0065] S503: According to the implementation results of the rock sample, repeatedly supplement the cementing liquid into the hydrogen storage caprock for multiple times. Combining the implementation results of the rock sample reference object, if it is found that the porosity, permeability and other parameters of the rock sample still show large values after a long time after supplementing the cementing liquid, there may be problems of microbial inactivation and death, and timely supplementation should be carried out into the hydrogen storage caprock.

[0066] After long-term biomineralization metabolism, the positions filled with medium between the fissures will be blocked and connected together, making the hydrogen storage caprock dense, thereby reducing the permeability of the hydrogen storage caprock, hindering the passage of gas and fluid, and at the same time strengthening the mechanical properties of the hydrogen storage caprock, which is beneficial to the safe storage of hydrogen.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for plugging hydrogen storage cap rock cracks based on microbial and composite mineralization, characterized in that: include: S100: injecting the prepared fly ash fluid into the hydrogen storage cap layer; S200: After the fly ash fluid is injected and the fracture structure in the hydrogen storage cap layer is fully wetted, the composite fluid composed of the prepared standard sand and granular activated carbon is injected into the hydrogen storage cap layer; S300: selecting mineralized microbial strains, activating and expanding the mineralized microbial strains in a liquid culture medium to obtain a mineralized microbial bacterial solution; S400: adding urea and calcium lactate into water to prepare a cementing solution, fully mixing the mineralized microbial solution with the cementing solution to form a mixed solution, and injecting the prepared mixed solution into the hydrogen storage cap layer; S500: simulating an actual formation environment in a laboratory, and performing steps S100 to S300 on the actual formation environment simulated in the laboratory, and replenishing a cementing fluid into the hydrogen storage cap layer according to the experimental results.

2. The method for plugging hydrogen storage cap rock cracks based on microbial and composite mineralization according to claim 1, characterized in that: In step S100, the fly ash particle size in the fly ash fluid is in the range of 0.5-300 μm, and the density is in the range of 1.4 g / cm 3 ~1.8g / cm 3 .

3. The method for plugging hydrogen storage cap rock cracks based on microbial and composite material mineralization according to claim 1, characterized in that: In step S200, the particle size of the standard sand is in the range of 0.075 mm to 2 mm, the particle size of the granular activated carbon is in the range of 0.175 mm or more, and the density of the composite fluid is in the range of 1.8 g / cm 3 ~2.2g / cm 3 .

4. The method for plugging hydrogen storage cap rock cracks based on microbial and composite mineralization according to claim 1, characterized in that: In the step S300, the mineralized microorganism strain is selected from Sporosarcina pasteurii.

5. The method for plugging hydrogen storage cap rock cracks based on microbial and composite material mineralization according to claim 1, characterized in that: In step S400, the ratio of urea and calcium lactate in the binder liquid is 1:1, wherein urea serves as a substrate for biological metabolic reactions and calcium lactate serves as a nutrient and a Ca source.

6. The method for plugging hydrogen storage caprock cracks based on microbial and composite mineralization according to claim 1, characterized in that: The step S500 includes: S501: Select a rock sample of a larger volume in the hydrogen storage caprock as a laboratory reference object, simulate the actual formation environment in the laboratory, convert the volume of the mixed bacterial solution and the volume of the composite fluid required for injection in proportion to the exploration volume of the hydrogen storage caprock and the volume of the selected rock sample, and perform the steps S100 to S300 on the rock sample; S502: using experimental means to regularly detect the degree of cementation and repair of the bulk particles and primary cracks in the rock sample; S503: According to the rock sample implementation results, repeatedly add cementing fluid to the hydrogen storage cap layer.

7. The method for plugging hydrogen storage caprock cracks based on microbial and composite mineralization according to claim 6, characterized in that: In step S501, the conversion formula for converting the volume of the mixed bacterial solution and the volume of the composite fluid required for injection in proportion to the volume of the hydrogen storage cap rock and the volume of the selected rock sample is as follows: Where: V1 represents the volume of hydrogen storage cap layer, m 3 ; V2 is the volume of laboratory rock sample, m 3 ; V1' represents the volume of mixed bacterial solution injected into the hydrogen storage cap layer, m 3 ; V2' represents the volume of mixed bacterial solution injected into the laboratory rock sample, m 3 ; V1'' represents the volume of composite fluid injected into the hydrogen storage cap layer, m 3 ; V2'' represents the volume of composite fluid injected into the laboratory rock sample, m 3 .

8. The method for plugging hydrogen storage caprock cracks based on microbial and composite mineralization according to claim 6, characterized in that: The step S502 includes using CT scanning, BET specific surface area tester, and core permeability tester to regularly detect the porosity, pore size distribution, and permeability parameters of the rock sample to describe the degree of cementation and repair of the bulk particles and primary cracks in the rock sample.

9. The method for plugging hydrogen storage cap rock cracks based on microbial and composite material mineralization according to claim 1, characterized in that: The hydrogen storage cap rock is the upper rock layer of the depleted oil and gas reservoir.

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