A water treatment method for storing carbon dioxide in sandstone fractured aquifers

Abstract

The application discloses a water treatment method for storing carbon dioxide in sandstone fissure aquifer, and relates to the technical field of mine water disaster treatment. The method comprises the following steps: firstly, supercritical carbon dioxide is injected into a grouting area to drive out fissure water, so as to create good conditions for the diffusion of slurry and improve the diffusion distance of the slurry; then, the supercritical carbon dioxide is mixed with the slurry to perform grouting, and the good fluidity of the supercritical carbon dioxide is used to increase the fluidity of the slurry in a pipeline to avoid pipeline blockage; finally, the supercritical carbon dioxide can react with water to generate carbonic acid, and the carbonic acid reacts with deep mine water and Ca 2+ , Mg 2+ , etc. in the slurry to generate CaCO3, MgCO3 and other precipitates, so that the fissures in the sandstone stratum can be effectively plugged, the scientific directional storage of carbon dioxide is achieved, and the grouting reinforcement and water disaster treatment are realized. The directional grouting technology is used to realize the directional storage of CO2, and helps to realize the double-carbon target.

Description

Technical Field

[0001] This invention relates to the field of mine water hazard treatment technology, specifically to a water control method for sealing carbon dioxide in sandstone fissure aquifers. Background Technology

[0002] Human activities and production processes emit large amounts of CO2, leading to global warming, rising sea levels, and impacting human survival and development. There are three main pathways to reduce CO2 emissions: reducing CO2 production, CO2 conversion and utilization, and CO2 sequestration. Currently, the primary method for reducing CO2 is control and emission reduction, specifically Carbon Capture, Utilization, and Storage (CCUS). This involves collecting CO2 emitted from human production and daily life, then recycling it in new production processes or storing it underground. Geological CO2 sequestration is a crucial component of CCUS technology. The process involves separating CO2 from industrial emission sources, transporting it to a sequestration site, and injecting it in a supercritical state to seal it within the geological strata, achieving long-term isolation between CO2 and the atmosphere. When the stratum temperature exceeds 31.1℃ and the pressure exceeds 7.38MPa, CO2 enters a supercritical state, typically requiring a depth of over 800m below the Earth's surface. Supercritical CO2 has a density close to that of a liquid, about 400 times that of a standard atmosphere, which greatly reduces the storage space required; its viscosity is close to that of a gas, two orders of magnitude lower than that of a liquid, giving it a greater dissolving capacity.

[0003] In mining engineering, water hazard control has always been a hot topic and a difficult issue for experts and scholars both domestically and internationally. During construction and production, fissure water, pore water, and karst water pose numerous challenges to safe production, often causing disasters such as collapses, landslides, and water inrushes, resulting in casualties. Directional drilling and grouting technology, as a method for reinforcing loose sandy or water-bearing strata, fissured rock formations, karst caves, and fractured zones, is widely used in mining engineering construction and has become an important means of disaster prevention and mitigation.

[0004] Excessive emissions of greenhouse gases, primarily carbon dioxide, are causing global warming, a pressing environmental issue. Geological carbon dioxide sequestration is one of the most effective methods for reducing carbon dioxide emissions. Supercritical carbon dioxide has low viscosity and high fluidity, and mine water and slurries contain large amounts of calcium. 2+ Mg 2+ Plasma can react with CO2 and water to form precipitates such as CaCO3 and MgCO3, but these characteristics are not currently being fully utilized. Summary of the Invention

[0005] The purpose of this invention is to provide a water control method for sealing carbon dioxide in sandstone fracture aquifers. This method is based on directional grouting technology, which enables the directional sealing of carbon dioxide and the reaction of the grout to generate mineral products, making the grouting reinforcement and water control effect more obvious. This achieves the scientific directional sealing of carbon dioxide while simultaneously achieving grouting reinforcement and water hazard control.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A water control method for sealing carbon dioxide in sandstone fracture aquifers includes the following steps:

[0008] Step 1: Control the temperature and pressure to compress the collected carbon dioxide into supercritical carbon dioxide.

[0009] Step 2: Thoroughly mix supercritical carbon dioxide with the slurry;

[0010] Step 3: Use directional drilling grouting equipment to inject supercritical carbon dioxide into the aquifer that needs grouting treatment and remove fissure water; then inject the mixture obtained in Step 2 into the grouting and water control area of ​​the sandstone fissure aquifer in the mine with a burial depth greater than 800m.

[0011] Step 4: In the grouting and water control area of ​​the sandstone fissure aquifer in the mine, supercritical carbon dioxide dissolves in the mine water and reacts with metal ions in the mine water to form precipitates, which are used to seal the micro-fissures in the rock strata; a small amount of supercritical carbon dioxide that does not react with the grout is sealed in the grout in a supercritical state.

[0012] In the above-mentioned water control method for sealing carbon dioxide in sandstone fracture aquifers, in step one, the temperature of the collected carbon dioxide is controlled to be greater than 31.26℃ and the pressure to be greater than 72.9 atm.

[0013] The above-mentioned method for sealing carbon dioxide in sandstone fissure aquifers uses silicate cement slurry, magnesium gel slurry, or water glass as the slurry.

[0014] In the above-mentioned water control method for sealing carbon dioxide in sandstone fissure aquifers, when the slurry is silicate cement slurry, the Ca(OH)2 in its hydration products can react chemically with carbonate ions to form CaCO3 precipitate.

[0015] In the above-mentioned water control method for sealing carbon dioxide in sandstone fracture aquifers, when the slurry is a magnesium gel slurry, magnesium ions react chemically with carbonate ions to form magnesium carbonate precipitate.

[0016] The above-mentioned method for sealing carbon dioxide in sandstone fissure aquifers involves supercritical carbon dioxide solidifying and hardening the water glass to seal micro-fissures in the rock strata when the slurry is water glass.

[0017] This invention provides a method for sealing carbon dioxide in sandstone fracture aquifers. First, supercritical carbon dioxide is injected into the grouting area to displace fracture water, creating favorable conditions for grout diffusion and increasing the diffusion distance. Then, supercritical carbon dioxide is mixed with the grout for injection, utilizing the good fluidity of supercritical carbon dioxide to increase the grout's flowability in the pipes and prevent blockage. Finally, the supercritical carbon dioxide reacts extensively with water to generate carbonic acid, which reacts with the calcium in deep mine water and the grout. 2+ Mg 2+ The plasma reaction generates precipitates such as CaCO3 and MgCO3, which can effectively seal the cracks in the sandstone strata, achieving scientific and directional carbon dioxide sequestration while simultaneously reinforcing and controlling water hazards through grouting.

[0018] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0019] (1) This invention utilizes directional grouting technology to achieve directional CO2 sequestration, thereby contributing to the realization of dual-carbon goals.

[0020] (2) The present invention utilizes supercritical carbon dioxide to improve the fluidity of the slurry and avoid blockage of the slurry in the grouting pipe.

[0021] (3) The present invention first injects supercritical carbon dioxide into the aquifer to drive out the fracture water, thereby creating favorable conditions for the diffusion of the slurry and increasing the diffusion distance of the slurry.

[0022] (4) This invention can utilize carbon dioxide and Ca in mine water and slurry. 2+ Mg 2+ The plasma reaction generates precipitates that can seal micro-cracks in sandstone strata and enhance the consolidation strength of the grout, thereby improving the effectiveness of grouting for water control. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] Figure 1 This is a process flow diagram of a water control method for sealing carbon dioxide in sandstone fracture aquifers according to the present invention. Detailed Implementation

[0025] This invention proposes a water control method for sealing carbon dioxide in sandstone fracture aquifers. To make the advantages and technical solutions of this invention clearer and more explicit, the invention will be further described below with reference to specific embodiments.

[0026] The structure and usage of the "directional drilling grouting equipment" described in this invention can be implemented by those skilled in the art by referring to existing technologies.

[0027] A method for sealing carbon dioxide in sandstone fracture aquifers, such as... Figure 1 As shown, it includes the following steps:

[0028] Step 1: Carbon dioxide collection and liquefaction. Carbon dioxide emitted from carbon dioxide emission sources is collected in a carbon dioxide capture workshop. The temperature of the collected carbon dioxide is controlled to be greater than 31.26℃ and the pressure is greater than 72.9 atm. The carbon dioxide is then compressed into a supercritical state.

[0029] Step 2: Calculate the required mass of carbon dioxide according to the carbon dioxide to slurry ratio. Thoroughly stir the supercritical carbon dioxide and slurry until uniformly mixed. Different slurries can be selected as needed. For example, the preferred slurry in this invention is silicate cement slurry, magnesium gel slurry, or water glass. Thoroughly mixing the supercritical carbon dioxide and slurry improves the fluidity of the mixture, preventing blockage of the grouting pipes. Compared to existing technologies that directly inject both into the water treatment area, this invention thoroughly mixes the supercritical carbon dioxide and slurry. The resistance to diffusion of the mineral liquid by supercritical carbon dioxide is lower than that of water, thus increasing the diffusion distance of the slurry.

[0030] Step 3: Using directional drilling grouting equipment, supercritical carbon dioxide is injected into the aquifer requiring grouting treatment and the fissure water is expelled; then the mixture obtained in Step 2 is injected into the grouting and water control area of ​​the sandstone fissure aquifer in the mine with a burial depth greater than 800m; the present invention specifically selects to inject the mixture into the grouting and water control area of ​​the sandstone fissure aquifer in the mine with a burial depth greater than 800m because in this area, the carbon dioxide can be ensured to be in a supercritical state, which improves the diffusivity of the grout.

[0031] Step 4: Within the grouting and water control area of ​​the sandstone fissure aquifer in the mine, supercritical carbon dioxide dissolves in the mine water and reacts with metal ions in the mine water to form precipitates. These precipitates seal the micro-fissures in the rock strata. A small amount of supercritical carbon dioxide that does not react with the grout is sealed in the grout in a supercritical state. Details are as follows:

[0032] When supercritical carbon dioxide is mixed in the grout, it can dissolve in water in large quantities to produce carbonate ions, which can react chemically with calcium and magnesium ions in the grout to form precipitates, thus improving the grouting reinforcement effect.

[0033] Specifically, if silicate cement grout is used, the Ca(OH)2 in its hydration products can react chemically with carbonate ions to form CaCO3 precipitate, as shown in equations (1), (2), and (3).

[0034] 3CaO·SiO2+nH2O=xCaOSio2·yH2O+(3-x)Ca(OH)2 (1);

[0035] CaO·SiO2+H2CO3=CaCO3↓+H2SiO3 (2);

[0036] Ca(OH)2+H2CO3=CaCO3↓+2H2O (3);

[0037] If a magnesium gel slurry is used, magnesium ions react with carbonate ions to form a precipitate, as shown in formula (4):

[0038] CO3 2- +Mg 2+ =MgCO3↓ (4);

[0039] If water glass is used, carbon dioxide helps it to solidify and harden, as shown in equation (5):

[0040] Na2O·nSiO2+CO2+mH2O=NaCO3+nSiO2·mH2O (5).

[0041] In summary, this invention enables the simultaneous and scientifically targeted storage of carbon dioxide and the grouting reinforcement for water hazard control during the grouting modification of aquifers.

[0042] Example 1:

[0043] A method for sequestering carbon dioxide in sandstone fracture aquifers.

[0044] Grouting reinforcement of deep sandstone aquifers using silicate cement grout includes the following steps:

[0045] (1) Calculate the required mass of supercritical carbon dioxide and silicate cement slurry at a volume ratio of 1:9, and then prepare the mixed slurry.

[0046] (2) Calculate the volume V of the area to be grouted and reinforced based on the previous geological survey data, and inject 0.1V of supercritical carbon dioxide into the area to be grouted to drive out the sandstone fissure water and form a good grouting environment.

[0047] (3) Injecting the mixed slurry improves the fluidity of the mixed liquid, which can prevent the grouting pipe from getting blocked. At the same time, the resistance formed by supercritical carbon dioxide to the diffusion of mineral liquid is lower than that of water, which can increase the diffusion distance of the slurry.

[0048] (4) Supercritical carbon dioxide and Ca in water 2+ Mg 2+ Plasma reactions generate precipitates such as CaCO3 and MgCO3, which can seal micro-cracks and achieve carbon dioxide mineralization and storage.

[0049] (5) The Ca(OH)2 in the hydration products of supercritical carbon dioxide and silicate cement slurry can react chemically with carbonate ions to form CaCO3 precipitate, which can improve the consolidation strength of the slurry and achieve carbon dioxide mineralization and sequestration.

[0050] 3CaO·SiO2+nH2O=xCaO·Sio2·yH2O+(3-x)Ca(OH)2

[0051] CaO·SiO2+H2CO3=CaCO3↓+H2SiO3

[0052] Ca(OH)₂ + H₂CO₃ = CaCO₃↓ + 2H₂O

[0053] (6) A small amount of carbon dioxide that has not reacted chemically with the slurry is sealed in the slurry in a supercritical state.

[0054] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. A method for water control involving carbon dioxide sequestration in sandstone fracture aquifers, characterized in that, Includes the following steps: Step 1: Control the temperature and pressure to compress the collected carbon dioxide into supercritical carbon dioxide. Step 2: Thoroughly mix supercritical carbon dioxide with the slurry; Step 3: Use directional drilling grouting equipment to inject supercritical carbon dioxide into the aquifer that needs grouting treatment and remove fissure water; then inject the mixture obtained in Step 2 into the grouting and water control area of ​​the sandstone fissure aquifer in the mine with a burial depth greater than 800m. Step 4: In the grouting and water control area of ​​the sandstone fissure aquifer in the mine, supercritical carbon dioxide dissolves in the mine water and reacts with metal ions in the mine water to form precipitates, which are used to seal the micro-fissures in the rock strata; in the mixture, supercritical carbon dioxide reacts with the grout to form precipitates, and a small amount of supercritical carbon dioxide that does not react with the grout is sealed in the grout in a supercritical state. The slurry is silicate cement slurry, magnesium gel slurry, or water glass.

2. The water control method for sealing carbon dioxide in sandstone fracture aquifers according to claim 1, characterized in that: In step one, the temperature of the collected carbon dioxide is controlled to be greater than 31.26℃ and the pressure to be greater than 72.9 atm.

3. A water control method for sealing carbon dioxide in sandstone fracture aquifers according to claim 1, characterized in that: When the grout is silicate cement grout, the Ca(OH)2 in its hydration products can react chemically with carbonate ions to form CaCO3 precipitate.

4. A water control method for sealing carbon dioxide in sandstone fracture aquifers according to claim 1, characterized in that: When the slurry is a magnesium gel slurry, magnesium ions react chemically with carbonate ions to form magnesium carbonate precipitate.

5. A water control method for sealing carbon dioxide in sandstone fracture aquifers according to claim 1, characterized in that: When the slurry is water glass, supercritical carbon dioxide solidifies and hardens the water glass to seal micro-fractures in the rock strata.

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