Application of industrial ammonia water and carbon dioxide storage method

Abstract

The present invention provides an application of industrial ammonia water and a carbon dioxide storage method, which injects industrial ammonia water into the formation to modify the formation fluid to increase the storage capacity of carbon dioxide, and provides a specific storage method, including: selecting a geological storage site, and forming an injection well to connect the geological storage layer; injecting industrial ammonia water into the geological storage layer through the injection well by a pressure injection device, so that the concentration of industrial ammonia water and formation fluid after mixing reaches a specified range, and the formation fluid properties are changed; injecting carbon dioxide into the geological storage layer through the injection well by the pressure injection device again, and adjusting the injection pressure and injection amount to control the bottom hole pressure based on the pressure monitoring feedback curve during injection, and finally completing the carbon dioxide storage process. The present invention can use industrial ammonia water and related processes for geological storage layers that meet the conditions, so that the absorption of carbon dioxide by the formation fluid is increased by 3-5 times, the storage efficiency is improved, and the balance problem between the storage space and the storage capacity of carbon dioxide is solved.

Description

Technical Field

[0001] The invention belongs to the field of carbon dioxide sequestration, and specifically relates to an application of industrial ammonia water and a carbon dioxide sequestration method. Background Art

[0002] In the CCUS capture field, waste gas emitted by factories is often used to capture carbon dioxide through industrial ammonia water. The principle and process are relatively mature, but the existing technology does not mention the use of industrial ammonia water for carbon dioxide storage.

[0003] Regarding carbon dioxide storage, the main storage locations include: deep saline water layers, depleted oil and gas reservoirs, deep unmineable coal seams, etc. The current carbon dioxide storage methods mostly rely on the original conditions of the formation fluid, and the storage efficiency is relatively low.

[0004] At present, my country is carrying out a number of carbon dioxide storage projects. However, even the largest storage project in my country, the China Shenhua CO2 geological storage project, has a cumulative CO2 injection volume of only more than 300,000 tons, or 10 million tons per year. 9 The CO2 emission reduction target of 10,000 tons is equivalent to the storage capacity of more than 3,000 tons of carbon dioxide. Domestic and foreign countries are exploring technical methods to increase the storage capacity of carbon dioxide in limited space.

[0005] At present, there are relatively few methods for enhanced storage of carbon dioxide, mainly including: CO2 multi-layer synergistic extraction and injection technology, external electric field enhanced CO2 geological storage, and microbial enhanced CO2 storage. Table 1 lists the various methods for enhanced storage of carbon dioxide.

[0006] Table 1 Parameters of enhanced carbon dioxide storage method

[0007]

[0008] As can be seen from Table 1, the above-mentioned various enhanced carbon dioxide storage methods can increase the injection volume of CO2 and have a certain enhanced storage effect. However, in the CO2 multi-layer coordinated extraction and injection method: for the storage of carbon dioxide in saline water layers, it is necessary to drill wells to extract saline water and treat it, which is costly; and CO2 is stored in the reservoir space after the saline water is discharged in a molecular state. Molecular CO2 is very easy to flow, which will increase the risk of CO2 leakage. In the external electric field enhanced CO2 geological storage method: CO2 geological storage is usually located below 800m above the ground, so that the magnetic field is precisely perpendicular to the CO2 storage layer and can achieve the expected magnetic field strength, which is a difficulty in practical application. In the microbial enhanced CO2 storage method: the cost of underground microbial cultivation is high, and it is difficult to survive. Moreover, under the action of microorganisms, the CO2 storage volume can only be increased by one-fifth, and the enhanced storage effect is general.

[0009] Therefore, current enhanced carbon dioxide storage methods are very difficult to implement at the technical level, and almost all of them require the treatment of water in the carbon dioxide storage layer, which increases the storage cost. There is a lack of suitable methods that are compatible with water-based enhanced carbon dioxide storage. Summary of the invention

[0010] The present invention provides an application of industrial ammonia water and a carbon dioxide sequestration method to solve the problem that the current sequestration method lacks compatibility with water bodies in the sequestration layer to enhance carbon dioxide sequestration.

[0011] In the first aspect of the present invention, an application of industrial ammonia water is provided, wherein the industrial ammonia water is injected into formation fluid to enhance the storage capacity of carbon dioxide.

[0012] Furthermore, a high aquifer or a deep saline layer is selected as a geological storage layer, and the overlying layer of the geological storage layer is various rock formations. Based on industrial ammonia water, the formation fluid in the geological storage layer is combined to enhance carbon dioxide storage.

[0013] Furthermore, the carbon dioxide is in a supercritical state, and the absorption or blocking of carbon dioxide is achieved based on whether the temperature and pressure of the reaction site of carbon dioxide and industrial ammonia water exceeds the critical temperature and pressure of carbon dioxide.

[0014] In a second aspect of the present invention, a method for storing carbon dioxide is provided, comprising the following steps:

[0015] Step 100: selecting a geological storage site, and forming an injection well on the geological storage site until the geological storage layer;

[0016] Step 200, injecting industrial ammonia water into the geological storage layer through the injection well by means of pressure injection equipment, so that the concentration of the industrial ammonia water and the formation fluid after mixing reaches a specified range to change the properties of the formation fluid;

[0017] Step 300, injecting carbon dioxide into the geological storage layer through the injection well again by pressure injection equipment, and adjusting the injection pressure and injection volume of the carbon dioxide based on the pressure monitoring feedback curve until the bottom hole pressure is stable to complete the entire storage process.

[0018] Furthermore, the concentration of the fluid after the industrial ammonia water and the formation fluid are mixed is 4% to 8%, and after the injection of the industrial ammonia water is completed, the industrial ammonia water remaining in the wellbore and the bottom of the well is flushed with a small amount of water.

[0019] Furthermore, in step 300, when carbon dioxide is injected through the pressure injection device, the carbon dioxide is always in a continuous injection state.

[0020] Furthermore, during the injection of carbon dioxide, the temperature and pressure of the geological storage layer are greater than the critical temperature and critical pressure of carbon dioxide, so that the injected carbon dioxide is in a supercritical state;

[0021] The supercritical carbon dioxide reacts chemically with the industrial ammonia water, and the specific reaction is:

[0022]

[0023] The molar ratio of the reactants industrial ammonia and carbon dioxide to the product ammonium bicarbonate is 1:1:1.

[0024] Further, the geological sealing layer is a high aquifer or a deep saline layer, and the overlying layer of the geological sealing layer is various rock formations;

[0025] Wherein, the temperature of the geological sealing layer is a high temperature and high pressure environment greater than 60°C.

[0026] Furthermore, after the carbon dioxide is injected into the geological storage layer through the injection well, a concentration gradient is formed from near to far around the injection well, and a diffusion zone is formed from near to far under the action of the injection pressure;

[0027] in:

[0028] After being injected, the carbon dioxide first reacts with the industrial ammonia solution to form a sodium bicarbonate solution. During the migration process, the carbon dioxide and the sodium bicarbonate solution migrate synchronously and gradually depart from the critical temperature and pressure of the carbon dioxide. At this time, the ambient temperature and pressure of the carbon dioxide and the sodium bicarbonate solution are lower than the critical temperature and pressure of the carbon dioxide, and the ammonium bicarbonate solution gradually precipitates crystals to block the migration channel.

[0029] Furthermore, the diffusion zone extends outward along the concentration gradient in the geological storage layer as the injection amount of carbon dioxide increases.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention uses industrial ammonia water for carbon dioxide storage based on the chemical reaction between ammonia water and carbon dioxide. The industrial ammonia water is injected into the formation fluid of the geological storage layer, and the water in the storage layer can be used to reduce the cost of treating and discharging the water. At the same time, the supercritical state characteristics of carbon dioxide in the storage layer are utilized, and the storage capacity of carbon dioxide can be increased by 3-5 times based on industrial ammonia water.

[0032] 2. The present invention combines the environmental characteristics of the geological storage layer, and can realize the use of only injection wells to sequentially inject industrial ammonia and carbon dioxide (when the water body is large enough, the formation pressure remains basically unchanged), and combines the fluid in the storage layer to bury the carbon dioxide in the storage layer mainly in the form of the compound ammonium bicarbonate, which can enhance the safety of the storage layer. Moreover, even if carbon dioxide leaks, as the migration channel moves upward, the ammonium bicarbonate solution migrates synchronously. As the migration channel moves upward, the temperature and pressure further decrease, the ammonium bicarbonate will gradually precipitate crystals to block the migration channel, making the storage layer equally stable and safe.

[0033] 3. Based on the principle of ammonia water absorbing carbon dioxide, it is not limited to the storage of high-purity carbon dioxide, but can also be used to store industrial flue gas. It does not require the complex process of purifying carbon dioxide from flue gas. It can be used for direct storage of industrial flue gas, which increases the storage capacity of industrial flue gas while saving the high cost of CCUS capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0035] Figure 1 Schematic diagram of a process for storing carbon dioxide in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the field of carbon dioxide capture, carbon dioxide is mainly captured from factory exhaust gas through industrial ammonia. However, based on the chemical reaction between ammonia and carbon dioxide, industrial ammonia can be applied to the field of carbon dioxide storage.

[0038] Therefore, the present invention provides an application of industrial ammonia water, which is injected into the formation fluid to enhance the storage of carbon dioxide. The carbon dioxide is in a supercritical state, and the absorption or blocking of carbon dioxide is achieved based on the temperature and pressure changes of the reaction site of carbon dioxide and industrial ammonia water, that is, whether the temperature and pressure of the reaction site exceed the critical temperature and pressure of carbon dioxide. Carbon dioxide in a supercritical state can increase the chemical reaction absorption of industrial ammonia water. As the temperature decreases, the reactant ammonium bicarbonate of carbon dioxide and industrial ammonia water will precipitate and crystallize, which can block the migration channel to prevent the solution from continuing to migrate and carbon dioxide from escaping.

[0039] Regarding the carbon dioxide storage site, high aquifers or deep saline layers can be selected as geological storage layers, and the overlying layers of the geological storage layers are various rock formations. Based on industrial ammonia water, the fluid properties in the geological storage layer can be changed, and the comprehensive utilization of the fluid in the storage layer can enhance the carbon dioxide storage.

[0040] Because 80% of my country's crude oil production comes from water injection development, some oil fields have entered the late development stage of ultra-high water content with a water content of more than 95%, and there are also large amounts of water bodies such as deep saline layers. Therefore, high-water-content layers or deep saline layers such as high-water-content oil and gas reservoirs in the late stage of water drive development or abandoned are selected as geological storage layers. The use of industrial ammonia-based storage methods can make full use of these water bodies, increase the dissolution and storage of carbon dioxide in the reservoir, and improve the total storage volume and storage safety.

[0041] The present invention discloses a specific carbon dioxide storage method, such as Figure 1 As shown, the following steps are included:

[0042] Step 100: Select a geological storage site and form an injection well on the geological storage site until the geological storage layer.

[0043] The geological storage layer is a high aquifer or deep saline layer, and the upper covering layer of the geological storage layer is various rock layers, generally dense, complete, continuous, low-permeability rock layers such as shale, mudstone, and slate. This method is suitable for deep saline layers or late-stage water drive development or abandoned oil reservoirs containing a lot of water. The water in the storage layer is conducive to the geological storage of CO2.

[0044] Step 200: Inject industrial ammonia water into the geological storage layer through the injection well by means of pressure injection equipment, so that the concentration of the industrial ammonia water and the formation fluid after mixing reaches a specified range to change the properties of the formation fluid.

[0045] The concentration of the fluid after mixing industrial ammonia water and formation fluid is 4% to 8%, and the concentration of the fluid after mixing industrial ammonia water is generally preferably 6%. The amount of industrial ammonia water required to reach 6% concentration of ammonia water can be calculated based on the volume of water in the sealing layer, and the industrial ammonia water can be injected into the sealing layer through the injection well by pressure injection equipment. The pressure in the injection well needs to be higher than the formation pressure.

[0046] After the completion of the industrial ammonia injection, a small amount of water is used to flush the industrial ammonia remaining in the wellbore and the bottom of the well to prevent CO2 from reacting with the ammonia remaining in the wellbore, which will precipitate ammonium bicarbonate crystals at a lower temperature, block or even damage the wellbore. Therefore, after injecting ammonia into the sealing layer, a small amount of water is first injected to flush the ammonia remaining in the wellbore, and then CO2 is injected.

[0047] Step 300: inject carbon dioxide into the geological storage layer through the injection well again by the pressure injection equipment. When injecting carbon dioxide, the injection pressure and injection volume are adjusted based on the pressure monitoring feedback curve until the bottom hole pressure is stable to complete the entire storage process.

[0048] When carbon dioxide is injected through pressure injection equipment, it is in a continuous injection state to increase the storage capacity of carbon dioxide and maximize the utilization of underground reservoir space.

[0049] During the carbon dioxide injection process, the temperature and pressure of the geological storage layer are respectively greater than the critical temperature and critical pressure of carbon dioxide, making the injected carbon dioxide in a supercritical state.

[0050] It should be noted that the internal environment of the geological storage layer is complex, the radius of some pore channels is very small, and there is an obvious pressure gradient. A small amount of local carbon dioxide is not necessarily in a supercritical state, but the amount of carbon dioxide dissolved in the pore channels is negligible compared to the overall dissolved amount of the storage layer, so the carbon dioxide is generally in a supercritical state.

[0051] The density of supercritical CO2 is close to that of liquid, and the diffusion coefficient is close to that of gas. When ammonia water reacts with supercritical CO2, they are mixed first, and ammonia water and CO2 are easier to contact. Therefore, compared with normal temperature and pressure conditions, the reaction degree of ammonia water and CO2 under reservoir conditions will be higher.

[0052] The supercritical carbon dioxide reacts chemically with the industrial ammonia water, and the specific reaction is:

[0053]

[0054] The molar ratio of the reactants industrial ammonia and carbon dioxide to the product ammonium bicarbonate is 1:1:1.

[0055] After carbon dioxide is injected into the geological storage layer through the injection well, a concentration gradient is formed from near to far around the injection well, and a diffusion zone is formed from near to far under the injection pressure. The diffusion zone extends outward along the concentration gradient in the geological storage layer as carbon dioxide is injected. Continuous injection of CO2 will cause the formation pressure to rise. When the formation pressure reaches the safety pressure P1 (less than the formation fracture pressure), stop injecting CO2, wait for CO2 and ammonia to react, so that the formation pressure drops, and then continue to inject CO2 until the formation pressure stabilizes at P1.

[0056] Among them, after injection, carbon dioxide first reacts with industrial ammonia water to form sodium bicarbonate solution. During the migration process, carbon dioxide and sodium bicarbonate solution gradually leave the supercritical environment while migrating synchronously. At this time, the temperature and pressure of carbon dioxide and sodium bicarbonate solution are lower than that of the supercritical environment, and ammonium bicarbonate solution gradually precipitates and crystallizes to block the migration channel. Based on the environmental parameters of the geological storage layer, industrial ammonia water and carbon dioxide can automatically block the migration channel as the temperature and pressure change.

[0057] The working principle of the above-mentioned carbon dioxide storage method is:

[0058] Ammonia water, that is, ammonia water solution, is mainly composed of NH3·H2O, which is a weak base. The concentration of general industrial ammonia water is 25%-28%, which means that the mass fraction of ammonia is 25%-28%. The chemical equations for the reaction of ammonia water and CO2 are mainly the following two equations:

[0059]

[0060]

[0061] Ammonia water is highly volatile and easily volatilizes ammonia gas. Ammonia gas also reacts with carbon dioxide to generate ammonium carbamate, as shown in chemical equation (3). This reaction is a reversible reaction. Ammonium carbamate generates uric acid and water when heated, as shown in chemical equation (4). This reaction is used in industry to prepare urea.

[0062]

[0063]

[0064] The reaction between ammonia and CO2 is a chemical reaction, and the main parameters affecting the reaction are the concentration of reactants and the reaction temperature. However, this type of research is mainly aimed at the field of CO2 capture, and the ammonia method of capturing CO2 is mostly at normal temperature and pressure.

[0065] The geological storage of CO2 is a high-temperature and high-pressure environment. When the pressure is higher than 7.38MPa and the temperature is higher than 31.1℃, CO2 enters a supercritical state, at which time the gas-liquid interface disappears. The underground storage depth of CO2 is generally greater than 800m. At this time, the temperature and pressure of the reservoir are usually greater than the critical temperature and critical pressure of CO2, so CO2 is in a supercritical state. Unlike gaseous CO2, the density of supercritical CO2 is close to that of liquid, and the diffusion coefficient is close to that of gas. When ammonia water reacts with supercritical CO2, similar to the contact between crude oil and CO2, they will first be miscible, and ammonia water and CO2 are easier to contact. Therefore, compared with normal temperature and pressure conditions, the reaction degree of ammonia water and CO2 under reservoir conditions is higher.

[0066] Table 2 Comparison of properties of gases, liquids and supercritical fluids

[0067] Physical properties Gas (normal temperature, normal pressure) Liquid (normal temperature, normal pressure) Supercritical fluid <![CDATA[Density (g / cm 3 )]]> 0.0006-0.02 0.6-1.6 0.2-0.9 Viscosity (mPa·s) <![CDATA[10 -2 ]]> 0.2-3.0 0.03-0.1 <![CDATA[Diffusion coefficient (cm 3 / s)]]> <![CDATA[10 -1 ]]> <![CDATA[10 -3 ]]> <![CDATA[10 -1 ]]>

[0068] Under the conditions of CO2 geological storage, the solubility of CO2 in water is about 30:1, and 1 ml of 6% ammonia water can absorb about 100-160 ml of CO2, that is, ammonia-enhanced CO2 storage can increase the CO2 storage capacity by 3-5 times. Based on this principle, the present invention uses the formation fluid of the geological storage layer to improve the carbon dioxide storage efficiency, so as to solve the problem of balancing the carbon dioxide storage space and storage capacity.

[0069] At 80°C, the saturated vapor pressure of ammonia is 4.078MPa, and the saturated vapor pressure of water is 0.027MPa. According to Raoult's or Henry's law, the saturated vapor pressure of ammonia water of different concentrations can be calculated, but it will not be greater than the saturated vapor pressure of pure ammonia. The lower the temperature, the smaller the saturated vapor pressure. As long as the pressure is greater than 4MPa, ammonia water will basically not volatilize gaseous ammonia. General oil reservoirs meet this condition, so the reaction of ammonia and carbon dioxide (3) and (4) can be ignored.

[0070] In CO2 geological storage, when CO2 is injected, CO2 is in excess near the interface between the two phases. In order to maximize the use of underground reservoir space and increase the CO2 storage capacity, CO2 will be continuously injected into the reservoir. Therefore, in CO2 storage, the main consideration is reaction (2), the reaction product is ammonium bicarbonate, and the ratio of the reactant ammonia, CO2 and the reaction product ammonium bicarbonate is 1:1:1.

[0071] In the process of ammonia enhanced CO2 storage, when CO2 is injected into the geological storage layer through the injection well by pressure injection equipment, supercritical CO2 reacts with ammonia in the formation near the bottom of the well to generate ammonium bicarbonate. When the ammonium bicarbonate in the formation near the bottom of the well is supersaturated, ammonium bicarbonate crystals will not be generated due to the high reservoir temperature, but the injected CO2 at this time will not react with the ammonia in the formation near the bottom of the well, and the formation pressure will increase.

[0072] Therefore, the injection of CO2 is stopped at this time to prevent excessive formation pressure from causing formation or well wall rupture. As the pressure decreases, the unreacted CO2 in the formation near the bottom of the well will migrate along the diffusion zone in the opposite direction to the depth of the sealing layer. After leaving the ammonium bicarbonate supersaturated area, it will come into contact with the ammonia water in the deep sealing layer and react. At the same time, the pressure of the formation near the bottom of the well drops due to the migration of CO2, so CO2 can continue to be injected, and this process is repeated. After the injection of CO2 is stopped, the bottom hole pressure remains unchanged, indicating that the ammonia water in the sealing layer has basically reacted with CO2, and the ammonium bicarbonate is in a nearly saturated state, and the entire sealing process can be stopped.

[0073] Assuming that the overburden layer on the storage layer is ruptured and the CO2 in the storage layer leaks, the nearly saturated ammonium bicarbonate solution in the sealing layer will also leak upward. As the upward leakage distance increases, the formation temperature decreases, and the ammonium bicarbonate solution gradually precipitates and crystallizes, blocking the leakage path, thereby preventing CO2 from continuing to leak.

[0074] Since ammonium bicarbonate can be completely dissolved in the mixed solution under an environment greater than 60°C, the temperature environment of the geological storage layer can preferably be a high-temperature and high-pressure environment with a temperature greater than 60°C. On the basis of ensuring enhanced carbon dioxide storage, the selectable range of the geological storage layer is further clarified.

[0075] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. An application of industrial ammonia water, characterized in that: Injecting industrial ammonia water into formation fluid to enhance the storage of carbon dioxide, selecting a high aquifer or a deep saline layer as a geological storage layer, and the upper covering layer of the geological storage layer is various rock formations, based on industrial ammonia water, combined with the formation fluid in the geological storage layer to enhance the storage of carbon dioxide; The carbon dioxide is in a supercritical state, and the absorption or blocking of carbon dioxide is achieved based on whether the temperature and pressure of the reaction site of carbon dioxide and industrial ammonia water exceeds the critical temperature and pressure of carbon dioxide.

2. A method for storing carbon dioxide, characterized in that: The steps include: Step 100: selecting a geological storage site, and forming an injection well on the geological storage site until the geological storage layer; Step 200, injecting industrial ammonia water into the geological storage layer through the injection well by means of pressure injection equipment, so that the concentration of the industrial ammonia water and the formation fluid after mixing reaches a specified range to change the properties of the formation fluid; Step 300, injecting carbon dioxide into the geological storage layer through the injection well again by means of pressure injection equipment, wherein the injection pressure and injection amount of the carbon dioxide are adjusted based on the pressure monitoring feedback curve during injection until the bottom hole pressure is stable to complete the entire storage process; During the injection of carbon dioxide, the temperature and pressure of the geological storage layer are greater than the critical temperature and critical pressure of carbon dioxide, so that the injected carbon dioxide is in a supercritical state; The supercritical carbon dioxide reacts chemically with the industrial ammonia water, and the specific reaction is: ; The molar ratio of the reactants, industrial ammonia and carbon dioxide, to the product, ammonium bicarbonate, is 1:1:1; The geological sealing layer is a high aquifer or a deep saline layer, and the overlying layer of the geological sealing layer is various rock formations; Wherein, the temperature of the geological sealing layer is a high temperature and high pressure environment greater than 60°C.

3. A carbon dioxide storage method according to claim 2, characterized in that: The fluid concentration after the industrial ammonia water and the formation fluid are mixed is 4% to 8%, and after the industrial ammonia water injection is completed, a small amount of water is used to flush the industrial ammonia water remaining in the wellbore and the bottom of the well.

4. A carbon dioxide storage method according to claim 2, characterized in that: In step 300, when carbon dioxide is injected through the pressure injection device, the carbon dioxide is always in a continuous injection state.

5. A carbon dioxide storage method according to claim 4, characterized in that: After the carbon dioxide is injected into the geological storage layer through the injection well, a concentration gradient is formed from near to far around the injection well, and a diffusion zone is formed from near to far under the action of the injection pressure; in: After being injected, the carbon dioxide first reacts with the industrial ammonia solution to form a sodium bicarbonate solution. During the migration process, the carbon dioxide and the sodium bicarbonate solution migrate synchronously and gradually depart from the critical temperature and pressure of the carbon dioxide. At this time, the ambient temperature and pressure of the carbon dioxide and the sodium bicarbonate solution are lower than the critical temperature and pressure of the carbon dioxide, and the ammonium bicarbonate solution gradually precipitates crystals to block the migration channel.

6. A carbon dioxide storage method according to claim 5, characterized in that: The diffusion zone extends outward along the concentration gradient in the geological storage layer as the injection amount of carbon dioxide increases.

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