Biological control method for geological storage of CO2 leakage

Abstract

The present application aims to provide a geological sequestration CO2 leakage biological control method, belonging to the technical field of carbon dioxide sequestration and emission reduction, by pre-injection of artificial disturbance zone near the wellbore and stratum with a biological mineralization bacterial agent composed of mineralized nutrient solution and enhanced bacterial population with denitrification induction capacity, biochemical reaction among microorganisms, calcium source and CO2 is utilized to form carbonate minerals to cement stratum pore and fracture structure, block CO2 leakage channel, and provide an effective biological control scheme for leakage from a biological perspective. The disclosed microbial repair method is green, efficient, economical, simple to operate, has strong adaptability and wide application range, and the generated carbonate minerals can effectively enter the pore and fracture structure of the leakage point stratum, which is an excellent biological method for responding to CO2 leakage, and is suitable for promotion and application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon dioxide storage and emission reduction, and particularly relates to a biological prevention method for CO2 leakage in geological storage. BACKGROUND

[0002] CO2 migration leakage is the most threatening risk in the geological storage process. On the one hand, during the well pipe laying and CO2 injection process, a large expansion pressure is generated due to the phase change of CO2, thereby causing a large number of secondary fractures in the formation near the wellbore, and increasing the risk of CO2 escape. On the other hand, the organic and inorganic components in the reservoir and cap rock are dissolved due to the diffusion and extraction activation ability of supercritical CO2, thereby increasing the channel of CO2 escape diffusion. After CO2 leakage, it will again escape into the atmosphere, resulting in the failure of the geological storage project.

[0003] Injecting cement slurry, gel and chemical reagents is the most commonly used technical means for repairing formation leakage. However, the traditional grouting technology has high cost, and the problems of large viscosity and easy accumulation of slurry also lead to poor formation repair effect, and have significant negative effects on the formation environment. SUMMARY

[0004] The purpose of the present application is to provide a biological prevention method for CO2 leakage in geological storage, which pre-injects a microbial repair liquid composed of a mineralized nutrient solution and an in-situ formation strengthening bacterial group with denitrification induction ability into the artificial disturbance zone and the formation, utilizes the biochemical reaction among microorganisms, calcium sources and CO2 to form carbonate minerals to cement the pore and fracture structure of the formation, and blocks the leakage channel of CO2, thereby providing an effective anti-leakage scheme from the biological point of view.

[0005] The present application adopts the following technical scheme:

[0006] A biological prevention method for CO2 leakage in geological storage, comprising the following steps:

[0007] Step 1: use a basic culture medium to perform multiple rounds of enrichment and passage of the mixed bacterial group, obtain an enriched bacterial group with denitrification induction mineralization ability, optimize the best culture conditions, obtain the composition of the mineralization nutrient solution that can stimulate the bacterial group to achieve the strongest mineralization effect, and stably culture the mixed bacterial group according to the nutrient solution to obtain a strengthened bacterial group. Mix the mineralization nutrient solution and the strengthened bacterial solution in proportion to obtain a biological mineralization bacterial agent;

[0008] Step 2: before the start of CO2 geological storage project injection, with the increase of the vertical injection well construction depth, simultaneously inject the biological mineralization bacterial agent into the formation at different depths to avoid leakage in the artificial disturbance zone near the wellbore;

[0009] Third step: select a suitable stratum above the reservoir to arrange a horizontal well, establish an artificial modified stratum as a mineralization layer, inject a biological mineralization agent into the artificial modified stratum through the horizontal well, strengthen the density and strength of the artificial modified stratum, and prevent CO2 leakage.

[0010] Fourth step: when the CO2 geological storage project is running, if CO2 leakage occurs in the mineralization layer, it indicates that the efficiency of the microbial repair liquid cannot guarantee the plugging of the leakage point, and the mineralization nutrient liquid is injected through the horizontal well.

[0011] Further, the mixed bacteria group in the first step is enriched from any one of activated sludge, hot springs, lake bottom sediments, the reservoir or the upper stratum of the CO2 geological storage project.

[0012] Further, the base medium in the first step comprises 2.5 g / L CaCl2, 5 g / L C4H4Na2O4·6H2O, 1 g / L NaNO3, 0.05 g / L KH2PO4 and MgSO4·7H2O, and 2 mL / L of a trace element solution.

[0013] Further, the trace element solution comprises 1 g / L EDTA, 1 g / L ZnSO4, 0.8 g / L MgSO4·7H2O, 0.8 g / L FeSO4·7H2O and 0.8 g / L CuSO4·5H2O, and 0.2 g / L CoCl2·6H2O.

[0014] Further, the mineralization nutrient liquid and the strengthening bacteria liquid are mixed in a volume ratio of 9:1 in the first step.

[0015] Further, the vertical injection well in the second step has a wellhead diameter of 0.3 m, and the biological mineralization agent in the artificial disturbance zone is injected from the vertical well every 200 m of well depth, with an injection amount of 500 L per place, and after the injection is completed, wellbore sealing and reinforcement are performed, and the distance between different vertical injection wells is 400-800 m.

[0016] Further, the stratum in which the horizontal well is arranged in the third step comprises an overburden layer, a thin coal seam, a shale layer, a basalt layer or an aquifer.

[0017] Further, the horizontal well in the third step has a wellhead diameter of 0.3 m, a single well length of 200-400 m, and an injection amount of the biological mineralization agent of 2000 L / horizontal well, so as to ensure that the injected biological mineralization agent can cover the artificial modified stratum.

[0018] Further, the mineralization nutrient liquid in the fourth step is a mineralization nutrient liquid without a strengthening bacteria group, and the injection amount is 500 L / horizontal well·time.

[0019] The beneficial effects of the present application are as follows:

[0020] The present application provides a way of microbial induced mineralization to improve the safety of CO2 geological storage. By introducing the biological mineralization ability of microorganisms, both the carbonate minerals and the biofilm formed can block the pore space and the cracks existing in the cap rock, hindering the migration and leakage of CO2, while CO2 can be converted into carbonate minerals to achieve carbon sequestration, which has a multi-purpose significance. Therefore, using the microbial mineralization method to plug the CO2 leakage path is an important supplement to CO2 geological storage.

[0021] 1. The present application can prevent CO2 leakage in artificially disturbed areas and potential CO2 leakage in the formation and repair CO2 leakage channels, improving the effectiveness of CO2 storage.

[0022] 2. The present application can convert leaked CO2 into carbonate minerals, accelerate the mineralization and conversion of CO2, and help achieve the negative carbon target.

[0023] 3. The denitrification pathway used in the present application is clean, the microbial community source is extensive, and the reproducibility is strong, which has good environmental and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Figure 1 is a schematic diagram of the biological control method for CO2 leakage of the present application; wherein 1 is a vertical injection well; 2 is a mineralization treatment area near the wellbore; 3 is a horizontal well; 4 is a mineralization layer; and 5 is a reservoir.

[0025] Figure 2 Figure 3 is a comparison chart of mineralization efficiency before and after enrichment of the microbial community.

[0026] Figure 3 Figure 4 is an X-ray diffraction pattern of carbonate minerals generated after 21 days of mineralization culture of the microbial community.

[0027] Figure 4 Figure 5 is a mercury intrusion graph of the influence of biogenic calcium carbonate on pore development after mineralization. (a) is the mercury intrusion and extrusion curve graph; (b) is the pore distribution curve graph of coal before and after mineralization; and (c) is a local enlarged view of the pore distribution curve graph. DETAILED DESCRIPTION

[0028] A biological control method for CO2 leakage in geological storage, comprising the following steps:

[0029] The first step involved enriching and subculturing the mixed bacterial population multiple times using a basal culture medium to obtain an enriched bacterial population with denitrification-induced mineralization capabilities. The optimal culture conditions were then optimized to obtain a mineralizing nutrient solution composition that stimulated the bacterial population to achieve the strongest mineralization effect. Based on this nutrient solution, the mixed bacterial population was stably cultured to obtain a strengthened bacterial population. The mineralizing nutrient solution and the strengthened bacterial solution were combined at a volume ratio of 9:1 to form a biomineralizing agent.

[0030] The second step is to inject biomineralizing agents into the formation at different depths simultaneously as the depth of the vertical injection well increases before the CO2 geological storage project is started, in order to avoid leakage in the artificially disturbed area near the wellbore.

[0031] The third step is to select a suitable stratum above the reservoir (such as overburden, thin coal seam, shale layer, basalt layer, aquifer, etc.) and arrange horizontal wells to establish an artificially modified stratum as a mineralized layer. Biomineralizing agents are injected into the stratum through the horizontal well to enhance the density and strength of the modified stratum and prevent CO2 leakage.

[0032] The fourth step is to inject nutrient replenishment solution into the horizontal well when CO2 leakage is detected in the mineralized layer during the operation of the CO2 geological storage project, which means that the effectiveness of the microbial remediation solution cannot guarantee the continued sealing of the leakage point.

[0033] The enhanced microbial community mentioned in the first step can be enriched from activated sludge, hot springs, lakebed sediments, and the reservoir or overlying strata where the CO2 geological sequestration project is located. Among these, microbial communities from the reservoir or overlying strata where the CO2 geological sequestration project is located are a superior choice, as they are better able to adapt to in-situ geological conditions.

[0034] When no CO2 leak occurs, the enhanced microbial community can utilize the small amounts of CO2 naturally occurring underground and produced by microbial metabolism to carry out mineralization reactions, reinforcing the strata and preventing CO2 leaks. When a CO2 leak does occur, the enhanced microbial community exhibits a tendency towards CO2, enabling it to directionally seal and repair CO2 seepage channels.

[0035] Strengthening microbial communities can accelerate the mineralization and transformation of CO2 by producing minerals to seal and plug escape and diffusion channels, thus helping to permanently reduce the total amount of CO2 in geological storage projects.

[0036] The enhanced microbial community can automatically capture CO2 and mineralize it. Since the CO2 concentration is higher at the leak point, the enhanced microbial community is attracted to the CO2 at the leak point and can accurately form carbonate minerals with cementing and sealing capabilities at the leak point.

[0037] The base medium used in the first step for enriching the bacterial population consists of 2.5 g / L CaCl2, 5 g / L C4H4Na2O4·6H2O, 1 g / L NaNO3, 0.05 g / L KH2PO4 and MgSO4·7H2O, and 2 mL / L of a trace element solution. The trace element solution includes 1 g / L EDTA, 1 g / L ZnSO4, 0.8 g / L MgSO4·7H2O, 0.8 g / L FeSO4·7H2O, and 0.8 g / L CuSO4·5H2O, and 0.2 g / L CoCl2·6H2O.

[0038] In the first step, the base medium can be optimized using orthogonal methods, response surface methods, genetic algorithms, BP neural networks, and the like to obtain the optimal nutrient solution composition.

[0039] In the second step, the wellhead diameter of the vertical injection well is 0.3 m, and the bio-mineralization bacterial agent in the artificially disturbed zone is injected every 200 m of well depth from the vertical well at an injection amount of 500 L per location. After the injection is completed, the wellbore is sealed and reinforced. The distance between different vertical injection wells is 400-800 m.

[0040] In the third step, when selecting the position of the mineralization layer, in addition to considering the formation physical properties, hydrogeological conditions, and rock mechanical properties, an organic layer should be selected as much as possible to provide a certain substrate for microbial growth and metabolism, maintain the stability of the bacterial population, and reduce the economic cost caused by repeated injection of growth and metabolism substrates.

[0041] In the third step, the wellhead diameter of the horizontal well is 0.3 m, the single well length is 200-400 m, and the microbial remediation liquid injection amount is 2000 L / horizontal well. It is ensured that the injected bio-mineralization bacterial agent can cover the artificially modified formation.

[0042] In the second and third steps, the strengthened bacterial population can create an alkaline environment for the conversion of CO2 to CO3 2- by denitrification without producing toxic byproducts. 2+ The carbonate precipitate is formed in combination with Ca

[0043] In the second and third steps, the strengthened bacterial population injected through the vertical injection well or the horizontal well can use the small amount of CO2 originally present in the formation and metabolized by the microorganisms to perform the mineralization reaction when there is no CO2 leakage, ensuring the basic growth and reproduction of the bacteria and enhancing the compactness of the disturbed zone and the formation to prevent CO2 leakage. When CO2 leakage occurs, the strengthened bacterial population has a tendency for CO2 and can directionally seal and repair the CO2 escape and leakage channels.

[0044] In the second and third steps, the enhanced bacterial flora can accelerate the mineralization of CO2 while sealing the escape diffusion channel by generating carbonate minerals, which helps to reduce the total amount of CO2 in the geological storage project and achieve the negative carbon goal.

[0045] In the fourth step, a vibration sensor sealed in the horizontal well cement is used to monitor CO2 leakage. If CO2 leakage occurs in the mineralization layer and no improvement is made within 3 days, it indicates that the effectiveness of the biological mineralization bacteria cannot guarantee the sealing and repair of the leakage point. In this case, a nutrient supplement liquid is injected through the horizontal well, with an injection amount of 500 L / horizontal well / time.

[0046] The nutrient supplement liquid in the fourth step is a mineralization nutrient liquid without enhanced bacterial flora. Since the enhanced bacterial flora has long-term effectiveness, it does not need to be repeatedly injected into the ground.

[0047] Example

[0048] A CO2 geological storage project stores the stratum at a depth of 2000 m underground. Above the storage stratum, there are basalt layers, coal layers, mudstone layers, and aquifers. Through comprehensive analysis of the physical properties, hydrogeological conditions, rock mechanics properties, and organic and inorganic components of the stratum, the coal layer at a depth of 800 m above the storage stratum is modified as an artificial stratum to lay horizontal wells.

[0049] The original bacterial flora obtained from the in-situ stratum is enriched and passed in the laboratory using a basic medium, which includes 2.5 g / L CaCl2, 5 g / L C4H4Na2O4·6H2O, 1 g / L NaNO3, 0.05 g / L KH2PO4 and MgSO4·7H2O, and 2 mL / L of a trace element solution. The trace element solution includes 1 g / L EDTA, 1 g / L ZnSO4, 0.8 g / L MgSO4·7H2O, 0.8 g / L FeSO4·7H2O, and 0.8 g / L CuSO4·5H2O, and 0.2 g / L CoCl2·6H2O.

[0050] The Design-Expert 13 software is used to design a CCD response surface test for the culture conditions, with 3 factors and 5 levels. The factors selected are Ca 2+ concentration, NO3 - concentration, and the carbon-nitrogen ratio, as shown in Table 1. The Ca 2+ mineralization efficiency of each group of experiments is used as the response value to establish a quadratic regression model. The CCD-RSM model is iteratively optimized using the genetic algorithm toolbox in MATLAB R2022b software, with an iteration number of 300. When the other components in the basic medium remain unchanged, the Ca 2+ concentration is 899.20 mg / L, the NO3 -When the concentration of N is 354.41 mg / L and the ratio of carbon to nitrogen is 9.94, Ca 2+ The mineralization efficiency can reach the highest, at which the mineralization efficiency is increased by 1022.46% compared with the original bacterial solution, for example Figure 2 The component ratio of the mineralization nutrient solution is obtained, and the bio-mineralization bacteria agent is obtained by mixing the mineralization nutrient solution with the enhanced bacteria group at a volume ratio of 9:1.

[0051] Table 1: Encoding of factors and levels of CCD response surface test

[0052]

[0053] The obtained bio-mineralization bacteria agent can generate calcite minerals with stable physicochemical properties and gelling characteristics, for example Figure 3 .

[0054] When the vertical injection well is constructed, 500L of bio-mineralization bacteria agent is injected from the vertical well every 200m to avoid CO2 leakage in the artificial disturbance zone near the wellbore as the drilling depth increases, and the wellbore is sealed and reinforced. When the distance from the reservoir is 800m, the bio-mineralization bacteria agent is injected from the horizontal well to establish an artificial modified formation as a reinforced cap layer, and the injection amount is 2000L / horizontal well.

[0055] After the well construction is completed, CO2 is injected into the reservoir to start the geological storage project.

[0056] The mineralization of the microbial repair solution can generate calcium carbonate in the pore space of the artificial modified formation, which can cement and plug the pore space. The pore development of the mineralized layer can be significantly reduced, and the total pore volume is decreased by 44.51%, for example Figure 4 .

[0057] After the project is started, the CO2 leakage of the formation is monitored in real time. When CO2 leakage occurs in the mineralized layer and no improvement is observed within 3 days, it is considered that the effectiveness of the bio-repair solution cannot guarantee the plugging and repair of the leakage point, and at this time, the nutrient supplement solution is injected from the horizontal well, and the injection amount is 500L / horizontal well·time.

Claims

1. A method of bioremediation of CO2 leakage from geological storage, characterized by: The method comprises the following steps: The first step is to use a basic medium to enrich and pass the mixed bacteria for multiple times to obtain an enriched bacteria with denitrification-induced mineralization capacity, and to optimize the best culture conditions to obtain a mineralization nutrient solution composition that can stimulate the bacteria to achieve the strongest mineralization effect, and to culture the enriched bacteria with the nutrient solution to obtain a strengthened bacteria, and to mix the mineralization nutrient solution and the strengthened bacteria solution in a certain proportion to obtain a biological mineralization bacteria agent; The second step is to inject the biological mineralization bacteria agent into the strata at different depths simultaneously as the vertical injection well is built to a greater depth before the CO2 geological storage project is started to avoid leakage in the artificial disturbance zone near the wellbore; The third step is to select a suitable stratum above the reservoir to arrange a horizontal well to establish an artificial modified stratum as a mineralization layer, and to inject the biological mineralization bacteria agent into the stratum through the horizontal well to strengthen the density and strength of the modified stratum to prevent CO2 leakage; The fourth step is to monitor the CO2 leakage in the mineralization layer when the CO2 geological storage project is running, and to inject the mineralization nutrient solution into the horizontal well if the efficiency of the microbial repair solution cannot guarantee the plugging of the leakage point.

2. A method of biological control of CO2 leakage from geological storage according to claim 1, characterized in that: The enriched bacteria in the first step are obtained from any one of activated sludge, hot springs, lake sediments, the reservoir or the upper strata of the CO2 geological storage project.

3. The method of biological control of CO2 leakage from geological storage according to claim 1, characterized in that: The basic medium in the first step comprises 2.5 g / L CaCl2, 5 g / L C4H4Na2O4·6H2O, 1 g / L NaNO3, 0.05 g / L KH2PO4 and MgSO4·7H2O, and 2 mL / L of a trace element solution.

4. A method of biological control of CO2 leakage from geological storage according to claim 3, characterized in that: The trace element solution comprises 1 g / L EDTA, 1 g / L ZnSO4, 0.8 g / L MgSO4·7H2O, 0.8 g / L FeSO4·7H2O and 0.8 g / L CuSO4·5H2O, and 0.2 g / L CoCl2·6H2O.

5. The method of biological control of CO2 leakage from geological storage according to claim 1, characterized by the fact that: The mineralization nutrient solution and the strengthened bacteria solution are mixed in a volume ratio of 9:1 in the first step.

6. The method of biological control of CO2 leakage from geological storage according to claim 1, characterized by that: The wellhead diameter of the vertical injection well is 0.3 m, and the biological mineralization bacteria agent is injected into the artificial disturbance zone every 200 m of well depth in the second step, and the injection amount is 500 L per place, and the wellbore is closed and reinforced after the injection is completed, and the distance between different vertical injection wells is 400-800 m.

7. The method of biological control of CO2 leakage from geological storage according to claim 1, characterized by that: The stratum where the horizontal well is arranged in the third step comprises an overburden layer, a thin coal seam, a shale layer, a basalt layer or an aquifer.

8. The method of biological control of CO2 leakage from geological storage according to claim 1, characterized by that: The wellhead diameter of the horizontal well is 0.3 m, and the single well length is 200-400 m, and the injection amount of the biological mineralization bacteria agent is 2000 L per horizontal well to ensure that the injected biological mineralization bacteria agent can cover the artificial modified stratum.

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