Cooperative device and method for seafloor carbon dioxide sequestration and reservoir reinforcement

Abstract

The invention is applicable to the technical field of carbon dioxide sequestration, and provides a seafloor carbon dioxide sequestration and reservoir reinforcement collaborative device and method.The method comprises the steps that a sequestration target region is determined according to a seafloor hydrate stable region; an injection well is designed according to the seabed geological conditions of the sealing target area, and a first liquid outlet hole, a second liquid outlet hole and a third liquid outlet hole are sequentially reserved in the injection well from bottom to top; liquid carbon dioxide is injected into the first liquid outlet hole by means of the layered injection device for carbon sequestration, steel slag-slag mixed slurry is injected into the second liquid outlet hole to absorb free carbon dioxide, high-bentonite-proportion slurry is injected into the third liquid outlet hole to form a low-permeability curing layer, and escape of carbon dioxide is effectively prevented. According to the method, through the well-designed solidification layer structure, carbon dioxide around a wellhead can be effectively isolated and prevented from being diffused to the surrounding environment, solid waste is ingeniously utilized for absorbing and fixing the carbon dioxide, and the overall stability of a reservoir is further enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide sequestration, and in particular relates to a coordinated device and method for seabed carbon dioxide sequestration and reservoir reinforcement. Background Art

[0002] To address the challenges of global warming, carbon dioxide storage and capture (CCUS) has emerged. While traditional geological storage technology is relatively mature, offering advantages such as large storage capacity and resource recovery, it relies heavily on natural caprocks, imposes stringent site selection requirements, and, due to limited land resources, hinders large-scale CO2 storage.

[0003] In contrast, the ocean, with its vast surface area and sparse population, offers a vast area for CO2 storage. Storing CO2 in the form of hydrates, in particular, has gained widespread support due to its large storage capacity and minimal impact on the marine environment. However, this method lacks practical operational experience and data to assess its long-term effectiveness, and CO2 leakage into the ocean could pose serious risks. Furthermore, the storage process could disturb the soil and trigger marine geological hazards. These factors have collectively constrained its further development.

[0004] Therefore, in order to advance the technology of storing carbon dioxide using seabed hydrates, it is urgent to develop a method that can prevent carbon dioxide leakage and strengthen the reservoir to accelerate the process of carbon dioxide ocean storage. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a coordinated device and method for seabed carbon dioxide storage and reservoir reinforcement, aiming to solve the problems raised in the above background technology.

[0006] The embodiment of the present invention is implemented as follows: a coordinated device for seabed carbon dioxide storage and reservoir reinforcement includes a working platform located on the sea surface and a wellhead device located in the seabed sediment layer; An injection well is provided at the bottom of the wellhead device, a liquid supply pipe is installed in the injection well, a third liquid outlet hole, a second liquid outlet hole and a first liquid outlet hole are sequentially opened on the side wall of the injection well from top to bottom, and a one-way reverse resistor is provided at each of the third liquid outlet hole, the second liquid outlet hole and the first liquid outlet hole. Two cylindrical sealing plugs are sleeved from bottom to top on the bottom of the liquid supply pipe, and the outer diameter of the sealing plugs is smaller than the inner diameter of the injection well. A liquid supply space is reserved between the two sealing plugs. A liquid supply hole is opened on the pipe body of the liquid supply pipe located in the liquid supply space; The sealing plug includes an external shell and an internal elastic sealing cavity, and the working platform is also provided with a pressure supply module for adjusting the air pressure of the internal elastic sealing cavity; The working platform is provided with a liquid supply module for conveying steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry into the liquid supply pipe.

[0007] A further technical solution is that the liquid supply module includes a four-way valve arranged at the top of the liquid supply pipe, and the other three ports of the four-way valve are respectively connected to the steel slag-slag mixed curing agent slurry storage tank, the liquid carbon dioxide storage tank and the high bentonite ratio curing agent slurry storage tank, which are used to transport the steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry to the liquid supply pipe respectively.

[0008] A further technical solution is that the external shell includes a coaxially distributed upper cover, multiple middle partitions and a lower cover, all of which are fixedly mounted on the liquid supply pipe, the upper cover includes a transverse circular plate and an annular vertical enclosure arranged at the bottom of the edge of the transverse circular plate, the middle partition includes a transverse circular plate and annular vertical enclosures arranged at the top and bottom of the edge of the transverse circular plate, the lower cover includes a transverse circular plate and an annular vertical enclosure arranged at the top of the edge of the transverse circular plate, the top of the transverse circular plate of the upper cover is designed to be an upwardly raised spherical surface, the thickness radius of the remaining transverse circular plates are the same, the exposed edges of all annular vertical enclosures are designed to be arc-shaped, and the thickness and height of all annular vertical enclosures are the same.

[0009] A further technical solution is that the internal elastic sealing cavity includes a plurality of cylindrical elastic sealing cavities which are sleeved on the liquid supply pipe and have an outer diameter the same as the inner diameter of the annular vertical enclosure. A cylindrical elastic sealing cavity is respectively arranged between the upper cover and the adjacent middle partition, between two adjacent middle partitions, and between the lower cover and the adjacent middle partition. The distance between the bottom of the upper cover and the top of the adjacent middle partition, the distance between the two adjacent middle partitions, and the distance between the top of the lower cover and the bottom of the adjacent middle partition are all the same as the thickness of the cylindrical elastic sealing cavity.

[0010] A further technical solution is that the two adjacent cylindrical elastic sealing cavities in the sealing plug are connected by a connecting pipe, each connecting pipe is also provided with a pressure relief valve, and the pressure required for the cylindrical elastic sealing cavity to expand to contact the inner wall of the injection well is less than the pressure required to open the pressure relief valve.

[0011] According to a further technical solution, the pressure supply module includes a pressure supply device arranged on a working platform, the pressure supply device is connected to an air supply pipe, and two branch pipes are arranged at the bottom of the air supply pipe, each branch pipe is respectively connected to a cylindrical elastic sealing cavity at the bottom of the sealing plug.

[0012] According to a further technical solution, the working platform is also provided with a cleaning system for cleaning the sealing plug.

[0013] A further technical solution is that the cleaning system includes an oil supply device installed on the upper working platform, the oil supply device is connected to an oil supply pipe, the bottom end of the oil supply pipe passes through the sealing plug located above and is fixedly connected to the top of the sealing plug located below, a first oil outlet hole is opened on the oil supply pipe located between the two sealing plugs, and a second oil outlet hole is opened on the oil supply pipe located above the upper sealing plug.

[0014] According to a further technical solution, a water-resistant casing is connected between the wellhead device and the work platform, and the upper parts of the liquid supply pipe, the air supply pipe and the oil supply pipe are all installed in the water-resistant casing.

[0015] Another object of an embodiment of the present invention is to provide a method for coordinating subsea carbon dioxide storage and reservoir reinforcement, based on the above-mentioned coordinating device, comprising the following steps: Step 1: Determine the seabed storage target area; Step 2: Build a working platform on the sea surface of the corresponding storage target area, install a watertight casing and wellhead device between the working platform and the seabed sediment layer, and design an injection well based on the seabed geological conditions of the storage target area. The injection well extends into or below the storage target area. At the same time, prepare the curing agent slurry or liquid carbon dioxide required for injection into the storage target area on the working platform; Step 3: Lower the liquid supply pipe and two sealing plugs from the working platform to the top of the seabed injection well, and lower them along the injection well until they reach the first liquid outlet, then stop lowering and fix the top of the liquid supply pipe; Step 4: The pressure supply device on the working platform inputs high-pressure air into the air supply pipe. The high-pressure air flows through two branch pipes and enters the cylindrical elastic sealing cavity at the bottom of each sealing plug. When the corresponding cylindrical elastic sealing cavity expands to contact the inner wall of the injection well and the pressure relief valve is not opened, the air supply is stopped; Step 5: Open the oil supply device on the working platform, and drain oil from the oil supply pipe through the first oil outlet and the second oil outlet to the top of each seal plug. Stop the oil supply after the oil level reaches the top of each seal plug, and open the pressure supply device again. Step 6: The pressure in each cylindrical elastic sealing cavity is made greater than the opening pressure of the pressure relief valve above it, so that each cylindrical elastic sealing cavity is expanded to fit tightly against the inner wall of the injection well. After the pressure in each cylindrical elastic sealing cavity is greater than the pressure of the injection liquid, the pressure supply device is closed; Step 7: Turn the four-way valve toward the liquid carbon dioxide storage tank to supply liquid into the liquid supply pipe. The liquid carbon dioxide flows into the liquid supply space through the liquid supply hole, and then flows into the sediment layer of the sealed target area through the first liquid outlet hole and the one-way reverse resistor until the injection volume reaches the target injection volume. Step 8: The pressure supply device generates negative pressure to extract the air from each cylindrical elastic sealing cavity and shrink it into the corresponding sealing plug. Then, the liquid supply tube is controlled to move upward, so that the two sealing plugs move to the next liquid outlet. Step 9: Repeat steps 3-8 until all the outlet holes are filled with liquid.

[0016] The embodiments of the present invention provide a coordinated device and method for submarine carbon dioxide storage and reservoir reinforcement, which have the following beneficial effects: (1) A layered injection method is used, with injection in three layers from the seabed downward. A high-bentonite-ratio solidifying agent is injected near the seabed to reduce the porosity of the seabed surface and prevent CO2 leakage. A steel slag-slag mixture solidifying agent is injected into the intermediate transition layer to absorb dissolved CO2 and prevent it from further upward migration. Liquid CO2 is directly injected into the deep layer to form a hydrate caprock to store CO2. The layered injection technology is highly flexible and allows for flexible adjustment of the injection timing of each layer according to the needs of the actual storage site.

[0017] (2) The main component of the solidifying agent used is solid waste. This material not only stores carbon dioxide but also indirectly solves the problem of solid waste disposal. In addition, the carbonate substances generated by the reaction of solid waste and carbon dioxide can neutralize the alkalinity of the solid waste, ensuring that the carbon dioxide storage process will not affect the seabed ecological environment. The solidified soil formed by the combination of the solidifying agent and the marine soil can also enhance the stability of the sediment layer and maintain the mechanical stability of the seabed carbon dioxide storage area.

[0018] (3) The interaction between soil solidifiers and hydrates is cleverly utilized to achieve dual benefits. The carefully designed solidification layer structure not only effectively isolates the carbon dioxide around the wellhead and prevents it from diffusing into the surrounding environment, but also utilizes the special properties of solid waste-based solidifiers to absorb and fix carbon dioxide, further enhancing the overall stability of the reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a coordinated device for seabed carbon dioxide storage and reservoir reinforcement provided by an embodiment of the present invention; Figure 2 It is a cross-sectional view of the expansion state of the internal elastic sealing cavity when the sealing plug is working; Figure 3 The completed rendering of CO2 storage and reservoir reinforcement; Figure 4 Schematic diagram of temperature and pressure conditions in the target area for storage of carbon dioxide hydrate; Figure 5 A flow chart of a collaborative method for seabed carbon dioxide storage and reservoir reinforcement provided in an embodiment of the present invention.

[0020] In the figure: sea surface 1; working platform 2; pressure supply device 3; steel slag-slag mixed curing agent slurry storage tank 4; liquid carbon dioxide storage tank 5; four-way valve 6; high bentonite ratio curing agent slurry storage tank 7; oil supply device 8; liquid supply pipe 9; air supply pipe 10; water-proof casing 11; oil supply pipe 12; wellhead device 13; third liquid outlet 14; second liquid outlet 15; first liquid outlet 16; sealing plug 17; injection well 18; one-way reverse resistor 19; seabed sediment layer 20; branch pipe 21; second oil outlet 22; upper cover 23; cylindrical elastic sealing cavity 24; clean oil 25; annular vertical enclosure 26; lower cover 27; curing agent slurry or liquid carbon dioxide 28; first oil outlet 29; middle partition 30; connecting pipe 31; pressure relief valve 32; high bentonite ratio solidified soil 33; steel slag-slag mixed solidified soil 34; free carbon dioxide 35; carbon dioxide hydrate cap layer 36; liquid supply space 37; liquid supply hole 38. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0023] like Figure 1 and Figure 2 As shown, a coordinated device for seabed carbon dioxide storage and reservoir reinforcement provided by one embodiment of the present invention includes a working platform 2 located on the sea surface 1 and a wellhead device 13 located in a seabed sediment layer 20; An injection well 18 is provided at the bottom of the wellhead device 13, and a liquid supply pipe 9 is installed in the injection well 18. A third liquid outlet 14, a second liquid outlet 15, and a first liquid outlet 16 are sequentially provided on the side wall of the injection well 18 from top to bottom, and a one-way reverse resistor 19 is provided at each of the third liquid outlet 14, the second liquid outlet 15, and the first liquid outlet 16. Two cylindrical sealing plugs 17 are sleeved from bottom to top at the bottom of the liquid supply pipe 9, and the outer diameter of the sealing plugs 17 is smaller than the inner diameter of the injection well 18. A liquid supply space 37 is reserved between the two sealing plugs 17. A liquid supply hole 38 is provided on the pipe body of the liquid supply pipe 9 within the liquid supply space 37; The sealing plug 17 includes an external shell and an internal elastic sealing cavity, and the working platform 2 is also provided with a pressure supply module for adjusting the air pressure of the internal elastic sealing cavity; The working platform 2 is provided with a liquid supply module for conveying steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry into the liquid supply pipe 9 .

[0024] In the embodiment of the present invention, the working platform 2 may include various forms, specifically a fixed drilling platform, a jack-up drilling platform, a semi-submersible drilling platform, a drilling ship, and the like.

[0025] like Figure 2 As shown, as a preferred embodiment of the present invention, the liquid supply module includes a four-way valve 6 arranged at the top of the liquid supply pipe 9, and the other three ports of the four-way valve 6 are respectively connected to the steel slag-slag mixed curing agent slurry storage tank 4, the liquid carbon dioxide storage tank 5 and the high bentonite ratio curing agent slurry storage tank 7, which are used to respectively transport the steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry to the liquid supply pipe 9.

[0026] like Figure 2 As shown, as a preferred embodiment of the present invention, the external shell includes a coaxially distributed upper cover 23, multiple middle partitions 30 and a lower cover 27, all of which are sleeved on the liquid supply pipe 9 and connected to its outer wall flange, the upper cover 23 includes a transverse circular plate and an annular vertical enclosure 26 arranged at the bottom of the edge of the transverse circular plate, the middle partition 30 includes a transverse circular plate and annular vertical enclosures 26 arranged at the top and bottom of the edge of the transverse circular plate, the lower cover 27 includes a transverse circular plate and an annular vertical enclosure 26 arranged at the top of the edge of the transverse circular plate, the top of the transverse circular plate of the upper cover 23 is designed to be an upwardly raised spherical surface, and the thickness radius of the remaining transverse circular plates are the same, the exposed edges of all annular vertical enclosures 26 are designed to be arc-shaped, and the thickness and height of all annular vertical enclosures 26 are the same.

[0027] like Figure 2 As shown, as a preferred embodiment of the present invention, the internal elastic sealing cavity includes a plurality of cylindrical elastic sealing cavities 24 which are sleeved on the liquid supply pipe 9 and have an outer diameter the same as the inner diameter of the annular vertical enclosure 26. A cylindrical elastic sealing cavity 24 is respectively provided between the upper cover 23 and the adjacent middle partition 30, between two adjacent middle partitions 30, and between the lower cover 27 and the adjacent middle partition 30. The distance between the bottom of the upper cover 23 and the top of the adjacent middle partition 30, the distance between the two adjacent middle partitions 30, and the distance between the top of the lower cover 27 and the bottom of the adjacent middle partition 30 are all the same as the thickness of the cylindrical elastic sealing cavity 24.

[0028] like Figure 2As shown, as a preferred embodiment of the present invention, the two adjacent cylindrical elastic sealing cavities 24 in the sealing plug 17 are connected by a connecting pipe 31, and each connecting pipe 31 is also provided with a pressure relief valve 32, and the pressure required for the cylindrical elastic sealing cavity 24 to expand to contact the inner wall of the injection well 18 is less than the pressure required to open the pressure relief valve 32.

[0029] like Figure 2 As shown, as a preferred embodiment of the present invention, the pressure supply module includes a pressure supply device 3 arranged on the working platform 2, the pressure supply device 3 is connected to the air supply pipe 10, and two branch pipes 21 are provided at the bottom of the air supply pipe 10, and each branch pipe 21 is respectively connected to a cylindrical elastic sealing cavity 24 at the bottom of a sealing plug 17.

[0030] like Figure 1 and 2 As shown, as a preferred embodiment of the present invention, the working platform 2 is further provided with a cleaning system for cleaning the sealing plug 17 .

[0031] In an embodiment of the present invention, the cleaning system includes an oil supply device 8 installed on the upper working platform 2, and the oil supply device 8 is connected to an oil supply pipe 12. The bottom end of the oil supply pipe 12 passes through the upper sealing plug 17 and is fixedly connected to the top of the lower sealing plug 17. A first oil outlet hole 29 is provided on the oil supply pipe 12 between the two sealing plugs 17, and a second oil outlet hole 22 is provided on the oil supply pipe 12 above the upper sealing plug 17.

[0032] During use, the first oil outlet 29 needs to be closed in time when the device is in the liquid injection state (i.e., when the liquid supply space 37 begins to be filled with slurry) to prevent the injected slurry from flowing back into the oil supply pipe 12. The main function of the oil supply device 8 is to provide pressure to the clean oil 25 so that it can flow out smoothly.

[0033] The purpose of equipping the cleaning system is to take into account that during the expansion and contraction process of the cylindrical elastic sealing cavity 24, it will inevitably come into contact with the curing agent slurry, which may adhere to the outer wall of the cylindrical elastic sealing cavity 24. When it expands again, some solidified slurry may exist, affecting its expansion and sealing effect. At the same time, when it contracts, some solidified slurry may affect its effective contraction and destroy the smoothness of its outer wall. At the same time, solidified slurry may also exist on the inner wall of the injection well 18, which will also affect the sealing effect between it and the inner wall of the injection well 18 when the cylindrical elastic sealing cavity 24 expands. Furthermore, liquid carbon dioxide may also corrode the inner wall of the injection well 18 or the sealing plug 17, affecting their service life and sealing effect. Therefore, before injecting liquid, it will be fully oiled to achieve the effect of isolating the slurry.

[0034] like Figure 1As shown in the figure, as a preferred embodiment of the present invention, a water-resistant casing 11 is connected between the wellhead device 13 and the work platform 2, and the upper parts of the liquid supply pipe 9, the air supply pipe 10 and the oil supply pipe 12 are all installed in the water-resistant casing 11. The water-resistant casing 11 is used to provide installation space for the liquid supply pipe 9, the air supply pipe 10 and the oil supply pipe 12 to prevent them from direct contact with seawater.

[0035] like Figure 5 As shown, another embodiment of the present invention provides a method for coordinating submarine carbon dioxide storage and reservoir reinforcement, based on the above-mentioned cooperative device, including the following steps: Step 1: Determine the seabed storage target area; First, factors such as the temperature and pressure of the seabed sediment layer are evaluated to determine whether the thermodynamic stability conditions for hydrate storage are met. Secondly, the seabed geology is evaluated, including the evaluation of geological properties such as porosity, permeability, and heterogeneity to ensure the stability of the geological layer and its ability to accommodate the specified amount of CO2 and maintain storage stability. The storage target area should have good mechanical stability to prevent formation instability during CO2 injection, and should also have appropriate porosity and permeability to ensure smooth CO2 injection. Finally, based on the geological conditions, reservoir thickness, and storage temperature and pressure conditions, the storage capacity is evaluated, and the storage target area where CO2 hydrates can be stably stored is ultimately determined.

[0036] Step 2: Build a work platform 2 on the sea surface 1 of the corresponding storage target area, install a watertight casing 11 and a wellhead 13 between the work platform 2 and the seabed sediment layer 20, and design an injection well 18 based on the seabed geological conditions of the storage target area. The injection well 18 extends into or below the storage target area. At the same time, prepare the curing agent slurry or liquid carbon dioxide required for injection into the storage target area on the work platform 2; Step 3: Lower the liquid supply pipe 9 and two sealing plugs 17 from the working platform 2 to the top of the seabed injection well 18, and lower them along the injection well until they reach the first liquid outlet 16, then stop lowering and fix the top of the liquid supply pipe 9.

[0037] Step 4: The pressure supply device 3 on the working platform 2 inputs high-pressure airflow into the air supply pipe 10. The high-pressure airflow enters the cylindrical elastic sealing cavity 24 at the bottom of each sealing plug 17 through the two branch pipes 21. When the corresponding cylindrical elastic sealing cavity 24 expands to contact the inner wall of the injection well 18 and the pressure relief valve 32 is not opened, the air supply is stopped.

[0038] The reason for allowing the cylindrical elastic sealing cavity 24 at the bottom of the sealing plug 17 to expand and contact the inner wall of the injection well 18 first is to pre-fix the sealing plug 17, and then expand the remaining cylindrical elastic sealing cavities 24 after sufficient oil injection, thereby effectively utilizing the gaps between the expanded exposed parts of adjacent cylindrical elastic sealing cavities 24 to achieve effective sealing. In order to achieve the expansion of the cylindrical elastic sealing cavity 24 from bottom to top, a pressure relief valve 32 is provided on each connecting pipe 31.

[0039] Step 5: Open the oil supply device 8 on the working platform 2, and discharge oil to the top of each sealing plug 17 through the oil supply pipe 12 via the first oil outlet hole 29 and the second oil outlet hole 22. Stop the oil supply after the oil level exceeds the top of each sealing plug 17, and open the pressure supply device 3 again.

[0040] Step 6: Make the pressure inside each cylindrical elastic sealing cavity 24 greater than the opening pressure of the pressure relief valve 32 above it, so that each cylindrical elastic sealing cavity 24 expands to fit tightly with the inner wall of the injection well. After the pressure inside each cylindrical elastic sealing cavity 24 is greater than the pressure of the injection liquid, close the pressure supply device 3.

[0041] Step 7: Turn the four-way valve 6 toward the liquid carbon dioxide storage tank 5 to supply liquid into the liquid supply pipe 9. The liquid carbon dioxide flows into the liquid supply space 37 through the liquid supply hole 38, and then flows into the sediment layer of the storage target area through the first liquid outlet 16 and the one-way reverse resistor 19 until the injection volume reaches the target injection volume, thereby forming a carbon dioxide hydrate cap layer 36. Step 8: The pressure supply device 3 generates negative pressure to extract the air in each cylindrical elastic sealing cavity 24 and shrink it into the corresponding sealing plug 17. Then, the liquid supply pipe 9 is controlled to move upward, so that the two sealing plugs 17 move to the next liquid outlet. Step 9: Repeat steps 3-8 until all the outlet holes are filled with liquid. Finally, the finished effect is as follows: Figure 3 shown.

[0042] In the embodiment of the present invention, the process of step 7 is for the first liquid outlet 16. When changing to the second liquid outlet 15 or the third liquid outlet 14, it is only necessary to turn the four-way valve 6 to the steel slag-slag mixed curing agent slurry storage tank 4 or the high bentonite ratio curing agent slurry storage tank 7.

[0043] In practice, the injection sequence of each outlet is not strictly limited. It primarily depends on the rising velocity of the free carbon dioxide 35 dissolved in the water. This ensures that by the time the free carbon dioxide 35 reaches the second outlet 15, the second outlet 15 has been completely filled. Ultimately, a high-bentonite-ratio solidified soil 33 and a steel slag-slag mixed solidified soil 34 are formed.

[0044] After grouting of all the outlet holes is completed, the injection well 18 can also be used as a detection well to detect the long-term storage stability of carbon dioxide hydrate. If later detection finds that the concentration of free carbon dioxide 35 in the sediment layer is too high or free carbon dioxide 35 dissolved in water is detected in the steel slag-slag mixed solidified soil 34, steel slag-slag mixed solidifying agent slurry can be injected again through the second outlet hole 15 or only the activator can be injected to activate the alkaline substances in the steel slag and slag to accelerate the carbonation reaction rate.

[0045] like Figure 4 As shown in the figure, as a preferred embodiment of the present invention, the storage site is selected as an area in the South China Sea, with the target area at a depth of approximately 1,300 meters from sea level. Specifically, the target area is 120 meters below the seabed, with a pressure of 13-15 MPa and a temperature between 4-11°C. This means that the intersection of the seabed sediment temperature and pressure versus depth curves and the CO2 hydrate phase equilibrium stability zone meets the thermodynamic stability conditions for CO2 hydrates and can be identified as a CO2 hydrate storage target area.

[0046] In the embodiment of the present invention, the porosity of the selected storage target area is 0.3-0.6, the permeability is 1 mD-2000 mD, and the permeability anisotropy is 1-10, which can accommodate a specified amount of CO2 and have appropriate porosity and permeability to ensure smooth CO2 injection. Limiting the porosity, permeability, and permeability anisotropy within the above ranges can effectively improve the CO2 storage efficiency.

[0047] As a preferred embodiment of the present invention, during specific implementation, multiple injection wells 18 may be provided. If multiple injection wells 18 are provided, the optimal spacing between adjacent injection wells 18 must be considered to optimize injection efficiency and resource conservation. When multiple injection wells 18 are provided, the spacing between adjacent injection wells 18 may range from 20 m to 60 m.

[0048] The diameter of injection well 18 can range from 0.1 m to 0.4 m, and the length can range from 100 m to 140 m (extending into or beneath the target storage area). In practice, the diameter and length of injection well 18 are optimized to accommodate the geological conditions of different storage targets, while also improving CO2 injection and storage efficiency. This step facilitates rapid injection, seepage, and diffusion of CO2 or a solidifying agent, achieving comprehensive and efficient CO2 hydrate formation within the target storage area and smooth solidifying agent injection.

[0049] In the embodiment of the present invention, the injection well 18 may be a vertical well, a horizontal well, a multi-branch well, or a well pattern system.

[0050] As a preferred embodiment of the present invention, in step 2, in order to accelerate the formation of CO2 hydrates, the position of the first liquid outlet 16 can be set within the range of 90 m-120 m below the seabed surface, and the position of the second liquid outlet 15 can be set at 30-50 m below the seabed surface. Within this range, the free CO2 dissolved in the water can be maximized. The position of the third liquid outlet 14 is set at 10-30 m below the seabed surface, which can serve as the last protective layer to prevent the dissolved CO2 from being freed above the seabed surface, and is also separated from the seabed surface by a distance so as not to affect the ecological environment of the seabed. In the specific implementation process, the first liquid outlet 16, the second liquid outlet 15 and the third liquid outlet 14 can all be set in multiple numbers, and CO2 and the curing agent can be injected at intervals.

[0051] In the specific implementation process, the target liquid injected into the first liquid outlet 16 is liquid carbon dioxide, the target slurry injected into the second liquid outlet 15 is steel slag-slag mixed curing agent slurry, and the target slurry injected into the third liquid outlet 14 is high bentonite ratio curing agent slurry.

[0052] The liquid carbon dioxide injected into first liquid outlet 16 originates from locations or processes where large amounts of CO2 are generated. This CO2 is a major source of elevated atmospheric CO2 concentrations, including tail gas emissions from coal-fired power plants, steel production, and cement production. This CO2 is collected, liquefied, and stored in liquid carbon dioxide storage tanks 5 before being transported to an offshore storage location.

[0053] As a preferred embodiment of the present invention, the slurry injected into the second liquid outlet 15 or the third liquid outlet 14 is prepared by a curing agent and seawater in a certain proportion; The main components of the curing agent in the steel slag-mineral slag mixed curing agent slurry are (by mass percentage): 50%-60% steel slag powder, 5%-15% slag powder, 2%-5% bentonite, 1%-3% polymer and 1%-3% activator.

[0054] The main components of the curing agent in the high bentonite ratio curing agent slurry are: 10%-20% bentonite, 30%-50% steel slag, 5%-15% slag powder and 1%-3% polymer.

[0055] The steel slag has an average particle size of 10-20 μm, wherein the SiO2 content is 5-10%, the CaO content is 50-70%, and the MgO content is 5-10%; The slag powder has an activity index of S95 or above, an average particle size of 1-100 μm, and a specific surface area of more than 400 m 2 / kg; The average particle size of the bentonite is greater than 38 μm, and the montmorillonite content is greater than 83%.

[0056] In an embodiment of the present invention, the polymer may be polyacrylamide (PAM) or carboxymethyl cellulose, which serves as a gelling material to improve the bonding force between soil particles, enhance the anti-scouring ability, and adapt to the marine undercurrent environment; The activator can be sodium silicate or sodium hydroxide to activate the alkaline substances in steel slag and ore slag and accelerate the carbonation reaction rate.

[0057] The carbonation reaction is mainly the reaction between CaO / MgO in the slag and dissolved CO2: ; ; This reaction can fix CO2 and generate stable minerals, and each ton of steel slag can store about 0.3 tons of CO2.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A coordinated device for seabed carbon dioxide storage and reservoir reinforcement, characterized in that: Including a working platform located on the sea surface and a wellhead device located in the seabed sediment layer; An injection well is provided at the bottom of the wellhead device, a liquid supply pipe is installed in the injection well, a third liquid outlet hole, a second liquid outlet hole and a first liquid outlet hole are sequentially opened on the side wall of the injection well from top to bottom, and a one-way reverse resistor is provided at each of the third liquid outlet hole, the second liquid outlet hole and the first liquid outlet hole. Two cylindrical sealing plugs are sleeved from bottom to top on the bottom of the liquid supply pipe, and the outer diameter of the sealing plugs is smaller than the inner diameter of the injection well. A liquid supply space is reserved between the two sealing plugs. A liquid supply hole is opened on the pipe body of the liquid supply pipe located in the liquid supply space; The sealing plug includes an external shell and an internal elastic sealing cavity, and the working platform is also provided with a pressure supply module for adjusting the air pressure of the internal elastic sealing cavity; The working platform is provided with a liquid supply module for conveying steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry into the liquid supply pipe.

2. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 1, characterized in that: The liquid supply module includes a four-way valve arranged at the top of the liquid supply pipe, and the other three ports of the four-way valve are respectively connected to the steel slag-slag mixed curing agent slurry storage tank, the liquid carbon dioxide storage tank and the high bentonite ratio curing agent slurry storage tank, which are used to transport the steel slag-slag mixed curing agent slurry, liquid carbon dioxide and high bentonite ratio curing agent slurry to the liquid supply pipe respectively.

3. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 2, characterized in that: The external shell includes a coaxially distributed upper cover, multiple middle partitions and a lower cover, all of which are fixedly mounted on the liquid supply pipe. The upper cover includes a transverse circular plate and an annular vertical enclosure arranged at the bottom of the edge of the transverse circular plate. The middle partition includes a transverse circular plate and annular vertical enclosures arranged at the top and bottom of the edge of the transverse circular plate. The lower cover includes a transverse circular plate and an annular vertical enclosure arranged at the top of the edge of the transverse circular plate. The top of the transverse circular plate of the upper cover is designed to be an upwardly raised spherical surface, and the thickness radius of the remaining transverse circular plates are the same. The exposed edges of all annular vertical enclosures are designed to be arc-shaped, and the thickness and height of all annular vertical enclosures are the same.

4. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 3, characterized in that: The internal elastic sealing cavity includes a plurality of cylindrical elastic sealing cavities which are sleeved on the liquid supply pipe and whose outer diameter is the same as the inner diameter of the annular vertical enclosure. A cylindrical elastic sealing cavity is respectively arranged between the upper cover and the adjacent middle partition, between two adjacent middle partitions, and between the lower cover and the adjacent middle partition. The distance between the bottom of the upper cover and the top of the adjacent middle partition, the distance between the two adjacent middle partitions, and the distance between the top of the lower cover and the bottom of the adjacent middle partition are all the same as the thickness of the cylindrical elastic sealing cavity.

5. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 4, characterized in that: The two adjacent cylindrical elastic sealing cavities in the sealing plug are connected by a connecting pipe, each of which is also provided with a pressure relief valve, and the pressure required for the cylindrical elastic sealing cavity to expand to contact the inner wall of the injection well is less than the pressure required to open the pressure relief valve.

6. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 5, characterized in that: The pressure supply module includes a pressure supply device arranged on a working platform, the pressure supply device is connected to an air supply pipe, and two branch pipes are arranged at the bottom of the air supply pipe, each branch pipe is respectively connected to a cylindrical elastic sealing cavity at the bottom of the sealing plug.

7. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 6, characterized in that: The working platform is also provided with a cleaning system for cleaning the sealing plug.

8. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 7, characterized in that: The cleaning system includes an oil supply device installed on the upper working platform, the oil supply device is connected to an oil supply pipe, the bottom end of the oil supply pipe passes through the sealing plug located above and is fixedly connected to the top of the sealing plug located below, a first oil outlet hole is opened on the oil supply pipe located between the two sealing plugs, and a second oil outlet hole is opened on the oil supply pipe located above the upper sealing plug.

9. The coordinated device for seabed carbon dioxide storage and reservoir reinforcement according to claim 8, characterized in that: A water-resistant casing is connected between the wellhead device and the working platform, and the upper parts of the liquid supply pipe, the air supply pipe and the oil supply pipe are all installed in the water-resistant casing.

10. A method for coordinating submarine carbon dioxide storage and reservoir reinforcement, based on the cooperative device for submarine carbon dioxide storage and reservoir reinforcement according to claim 9, characterized in that: The following steps are involved: Step 1: Determine the seabed storage target area; Step 2: Build a working platform on the sea surface of the corresponding storage target area, install a watertight casing and wellhead device between the working platform and the seabed sediment layer, and design an injection well based on the seabed geological conditions of the storage target area. The injection well extends into or below the storage target area. At the same time, prepare the curing agent slurry or liquid carbon dioxide required for injection into the storage target area on the working platform; Step 3: Lower the liquid supply pipe and two sealing plugs from the working platform to the top of the seabed injection well, and lower them along the injection well until they reach the first liquid outlet, then stop lowering and fix the top of the liquid supply pipe; Step 4: The pressure supply device on the working platform inputs high-pressure air into the air supply pipe. The high-pressure air flows through two branch pipes and enters the cylindrical elastic sealing cavity at the bottom of each sealing plug. When the corresponding cylindrical elastic sealing cavity expands to contact the inner wall of the injection well and the pressure relief valve is not opened, the air supply is stopped; Step 5: Open the oil supply device on the working platform, and drain oil from the oil supply pipe through the first oil outlet and the second oil outlet to the top of each seal plug. Stop the oil supply after the oil level reaches the top of each seal plug, and open the pressure supply device again. Step 6: The pressure in each cylindrical elastic sealing cavity is made greater than the opening pressure of the pressure relief valve above it, so that each cylindrical elastic sealing cavity is expanded to fit tightly against the inner wall of the injection well. After the pressure in each cylindrical elastic sealing cavity is greater than the pressure of the injection liquid, the pressure supply device is closed; Step 7: Turn the four-way valve toward the liquid carbon dioxide storage tank to supply liquid into the liquid supply pipe. The liquid carbon dioxide flows into the liquid supply space through the liquid supply hole, and then flows into the sediment layer of the sealed target area through the first liquid outlet hole and the one-way reverse resistor until the injection volume reaches the target injection volume. Step 8: The pressure supply device generates negative pressure to extract the air from each cylindrical elastic sealing cavity and shrink it into the corresponding sealing plug. Then, the liquid supply tube is controlled to move upward, so that the two sealing plugs move to the next liquid outlet. Step 9: Repeat steps 3-8 until all the outlet holes are filled with liquid.

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