A method for enhancing geological sequestration through carbon dioxide self-emulsification

Abstract

This invention provides a method for enhanced geological sequestration of carbon dioxide through self-emulsification. The method includes: establishing an injection well in a seafloor sedimentary layer; injecting a penicillin-based chemical agent and CO2 into the seafloor sedimentary layer through the injection well; the CO2 carrying the penicillin-based chemical agent and seawater fluid flowing within the sediments of the seafloor sedimentary layer, whereby the CO2 undergoes self-emulsification to form a water-in-water CO2 microemulsion; under the impetus of injection pressure and buoyancy, the mixed fluid containing the water-in-water CO2 microemulsion displaces pore seawater and diffuses within the seafloor sedimentary layer, achieving geological sequestration of carbon dioxide. This method, by injecting the penicillin-based chemical agent and CO2 into the target layer, enables the CO2 to undergo self-emulsification within the target seafloor layer, transforming the pore fluid into a water-in-water CO2 microemulsion with good dispersibility and stability, thereby improving displacement capacity and sweep range.

Description

Technical Field

[0001] This invention relates to a method for enhanced geological sequestration of carbon dioxide through self-emulsification, belonging to the field of carbon dioxide geological sequestration technology. Background Art

[0002] Currently, CO2 geological storage technologies mainly include onshore and offshore storage. Onshore storage includes abandoned oil and gas fields, coal seams, and deep brackish water formations. Oil and gas reservoir CO2 storage is one of the most mature storage technologies, capable of improving oil and gas recovery while storing CO2 within the oil and gas field. Coal seam CO2 storage involves injecting CO2 into the coal seam to increase coalbed methane production efficiency and store the CO2 within the coal seam. Deep brackish water formation CO2 storage technology is relatively mature and simple, and is considered an excellent approach to CO2 storage. However, these methods have very demanding geographical requirements, and their storage efficiency and capacity are relatively low, with a high risk of CO2 leakage. Compared to onshore storage, offshore storage has advantages such as a wide range of storage locations, large storage capacity, simple operation, and lower cost. Marine CO2 storage is mainly divided into two types. One method involves injecting CO2 into seawater at depths greater than 3000 meters. The CO2 becomes liquid and has a density far greater than seawater, causing it to sink and accumulate in low-lying areas, forming a special "carbon lake." This method may be accelerated by the presence of undersea currents, which could cause the CO2 carbon lake to dissolve and dissipate more quickly. Another method involves injecting CO2 into low-temperature, high-pressure deep-sea sedimentary layers. Here, the CO2 forms hydrates, reducing both CO2 dissolution and the porosity and permeability of the seabed sediments, preventing CO2 from diffusing upwards and thus achieving CO2 sequestration.

[0003] However, during the CO2 injection process on the seabed, cross-flow and fingering are prone to occur, leading to problems such as low displacement efficiency and low sequestration density, which seriously limits the process of CO2 sequestration in seabed reservoirs.

[0004] Therefore, developing a novel method for geological carbon dioxide sequestration remains one of the urgent problems to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method for enhancing geological sequestration through carbon dioxide self-emulsification. This method involves injecting penicillin-like chemicals and CO2 into the target layer, causing CO2 to undergo self-emulsification within the seabed target layer. The pore fluid is transformed into a water-in-water CO2 microemulsion with good dispersibility and stability, thereby improving displacement capacity and sweep range.

[0006] To achieve the above objectives, the present invention provides a method for enhanced geological storage of carbon dioxide through self-emulsification, comprising the following steps:

[0007] S1: Establish an injection well in the seabed sedimentary layer;

[0008] S2: Penicillin-type chemicals and CO2 are injected into the seabed sedimentary layer through an injection well;

[0009] S3: CO2 carrying penicillin-like chemicals and seawater flow in the sediments of the seabed sedimentary layer, and the CO2 undergoes self-emulsification to form a water-in-water CO2 microemulsion. Under the impetus of injection pressure and buoyancy, the mixed fluid containing the water-in-water CO2 microemulsion displaces the porous seawater and diffuses in the seabed sedimentary layer, thereby achieving geological sequestration of carbon dioxide.

[0010] In the above method, preferably, in step S1, the wellhead location of the injection well includes the seafloor CO2 hydrate stable zone and the area below the seafloor CO2 hydrate stable zone. That is, the seafloor sedimentary layer includes, but is not limited to, the seafloor CO2 hydrate stable zone and the area below the seafloor CO2 hydrate stable zone.

[0011] In the above method, preferably, in step S1, the temperature range of the seabed CO2 hydrate stabilization zone is 3-10℃, and the pressure range is 6-12MPa; the minimum temperature of the area below the seabed CO2 hydrate stabilization zone is 12℃.

[0012] According to a specific embodiment of the present invention, in step S1, those skilled in the art can adjust the depth of the injection well based on the target layer of the present invention, namely the seabed sedimentary layer.

[0013] In the above method, preferably, in step S1, the injection well includes a CO2 injection well and a penicillin-type chemical agent injection well, or the injection well includes a mixture of CO2 and penicillin-type chemical agent injection well.

[0014] In some specific embodiments of the present invention, the horizontal section of the penicillin-type chemical injection well is higher than the horizontal section of the CO2 injection well. The height difference between the horizontal sections of the penicillin-type chemical injection well and the CO2 injection well can be conventionally adjusted by those skilled in the art, but all adjustments must be made within the seabed sedimentary layer. In this invention, a penicillin-type chemical injection well is positioned above the CO2 injection well, allowing the CO2 to come into contact with the penicillin-type chemical during its ascent, achieving an emulsification effect.

[0015] In the above method, preferably, the penicillin-type chemical agent includes, but is not limited to, penicillin G. More preferably, the penicillin-type chemical agent includes one or a combination of penicillin potassium, penicillin sodium, and oxacillin.

[0016] In the above method, preferably, in step S2, the injected CO2 is liquid CO2.

[0017] In the above method, preferably, in step S2, the penicillin-type chemical agent injected is a solution of penicillin-type chemical agent.

[0018] In the above method, preferably, in step S2, the concentration of penicillin-based chemical in the seabed sediment layer after injection is 0.5 wt%-1.0 wt%. The inventors of this invention have discovered that, under conditions of penicillin-based chemical concentrations above 0.5 wt%, the injected CO2 can achieve self-emulsification, and the degree of CO2 self-emulsification increases with increasing penicillin-based chemical concentration. However, when the concentration of penicillin-based chemical exceeds 1.0 wt%, the increase in the degree of CO2 self-emulsification becomes less significant.

[0019] In the above method, preferably, in step S2, the penicillin chemical agent and CO2 are injected in a mixed injection, injected one by one, or injected alternately.

[0020] In some specific embodiments of the present invention, the mixed injection includes: mixing a solution of penicillin-type chemical agent with CO2 and then injecting it into the target layer on the seabed (i.e., the seabed sedimentary layer) through an injection well.

[0021] In some specific embodiments of the present invention, the step-by-step injection includes: first injecting a solution of penicillin-type chemical agent into the target seabed layer (i.e., the seabed sediment layer) through an injection well, and then injecting CO2 into the target seabed layer (i.e., the seabed sediment layer).

[0022] In some specific embodiments of the present invention, the alternating injection includes: injecting a solution of a certain total amount of penicillin-type chemical agent into the target seabed layer (i.e., the seabed sedimentary layer) in multiple injections through an injection well; and injecting CO2 into the target seabed layer (i.e., the seabed sedimentary layer) multiple times during the intervals between solution injections. This alternating injection method can reduce the amount of penicillin-type chemical agent used.

[0023] It should be noted that in step S2, the injection pressure of penicillin-type chemical agents and CO2 injected into the seabed sediment layer through the injection well can be adjusted by those skilled in the art according to different injection areas. The present invention does not impose any special limitation on the injection pressure.

[0024] In the above method, preferably, when the injection well in step S1 is located in the seabed CO2 hydrate stable zone, in step S3, some CO2 combines with seawater to form solid CO2 hydrate, and is sealed in the form of solid CO2 hydrate. At the same time, CO2 that does not form solid CO2 hydrate is sealed in liquid form. When the injection well in step S1 is located in the area below the seabed CO2 hydrate stable zone, in step S3, CO2 does not form solid CO2 hydrate.

[0025] According to a specific embodiment of the present invention, in the stable zone of CO2 hydrate on the seabed, after CO2 forms solid CO2 hydrate, it can reduce the permeability of the seabed sediment layer and inhibit CO2 from continuing to rise, thereby achieving the effect of stable CO2 sequestration; at the same time, due to the difference in the ratio of CO2 and seawater in the pores, CO2 cannot be completely converted, and some CO2 is sequestered in liquid form.

[0026] According to a specific embodiment of the present invention, in the region below the seabed CO2 hydrate stability zone, CO2 does not form solid CO2 hydrate, but liquid CO2 may rise to the seabed CO2 hydrate stability zone and then form solid CO2 hydrate, and may eventually be sealed in the form of partially liquid and partially solid CO2 hydrate.

[0027] According to a specific embodiment of the present invention, when the concentration of penicillin-based chemical agents in the seabed sediment layer after injection is less than 0.5 wt%, the penicillin-based chemical agents (especially sodium penicillin) promote the formation kinetics of solid CO2 hydrate; while when the concentration of penicillin-based chemical agents in the seabed sediment layer after injection is greater than 0.5 wt%, the penicillin-based chemical agents (especially sodium penicillin) inhibit the formation kinetics of solid CO2 hydrate.

[0028] In the above method, preferably, in step S3, the droplet size of the water-in-CO2 microemulsion is less than 360 μm.

[0029] In the above method, preferably, in step S3, the mixed fluid containing the water-infused CO2 microemulsion diffuses in the seabed sedimentary layer in a bowl-shaped distribution.

[0030] This invention provides a method for enhanced geological sequestration of carbon dioxide through self-emulsification. The method involves injecting penicillin-like chemicals and liquid CO2 into sediments of a target seafloor layer (i.e., a sedimentary layer) via mixed injection, sequential injection, or alternating injection. This causes the liquid CO2 to self-emulsify during its flow within the seafloor sedimentary layer, transforming the pore fluid into a water-in-coated CO2 microemulsion with good dispersibility and stability. This significantly enhances the ability of CO2 to displace pore water and its horizontal sweep range. Simultaneously, this method significantly increases the contact area between CO2 and seawater in the fluid phase. In the stable CO2 hydrate zone on the seafloor, CO2 can rapidly and extensively transform into solid hydrates, primarily achieving sequestration in the form of solid CO2 hydrates. In areas below the stable CO2 hydrate zone, CO2 does not form solid CO2 hydrates, but may ultimately be sequestered as a mixture of partially liquid and partially solid CO2 hydrates. Therefore, the method of the present invention does not aim to form solid CO2 hydrates, but rather improves the displacement capacity and sweep range through the self-emulsification behavior of CO2, and increases the contact area between CO2 and seawater, thereby significantly increasing the amount of CO2 injected.

[0031] The technical solution of the present invention has at least the following beneficial effects:

[0032] (1) The method of the present invention uses penicillin-type chemical agents to cause liquid CO2 to undergo self-emulsification during the flow of seabed sediments. The CO2 droplets are automatically dispersed into highly dispersed, more uniform in size and stable water-encapsulated CO2 fluid, which greatly improves the CO2 displacement efficiency and makes the distribution in the reservoir more uniform.

[0033] (2) The method of the present invention achieves a significant increase in the amount of liquid CO2 injected into the reservoir, while realizing efficient, uniform and stable CO2 storage.

[0034] (3) The CO2 droplets formed during the injection process of the method of the present invention greatly increase the contact area between seawater and liquid CO2, which is conducive to the rapid and large-scale conversion of CO2 into solid form of CO2 hydrate after entering the hydrate stability zone. This sealed state is more stable and beneficial to the geological framework structure of the reservoir.

[0035] (4) The penicillin-type chemical agent used in the method of the present invention is an environmentally friendly and safe penicillin-type antibiotic that is highly soluble in water. Different concentrations of penicillin-type chemical agents can promote or inhibit the formation of CO2 hydrates. When using this method to inject liquid CO2 into the seabed reservoir, there is no need to use additional promoters or inhibitors, thus saving on additive costs.

[0036] In summary, the carbon dioxide self-emulsification enhanced geological sequestration method of the present invention effectively solves the problems of cross-flow and fingering during CO2 injection into seabed sediments, leading to low displacement efficiency and low sequestration density. This method is a novel approach for efficient CO2 injection, long-distance propagation, and high-proportion solid-state sequestration in seabed sediments, improving the stability of CO2 sequestration and having significant implications for long-term stable CO2 sequestration. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the carbon dioxide self-emulsification enhanced geological sequestration process in Example 1.

[0038] Figure 2 This is a schematic diagram of the physical simulation experimental device for carbon dioxide self-emulsification enhanced geological sequestration in Example 2.

[0039] Figure 3 The CO2 injection and conversion amounts correspond to different concentrations of sodium penicillin in the seabed sediment layer in Example 2.

[0040] Figure 4 The self-emulsification phenomenon of liquid CO2 in the seabed sediment layer without added sodium penicillin and in the seabed sediment layer with added 0.5 wt% sodium penicillin in Example 2.

[0041] Figure 5 This is a schematic diagram of the physical simulation experimental device for carbon dioxide self-emulsification enhanced geological sequestration in Example 3.

[0042] Figure 6 The CO2 injection amounts are those of the seabed sediment layer without added sodium penicillin in Example 3 and those of the seabed sediment layer after seawater was displaced with 0.5 wt% sodium penicillin.

[0043] The reference numerals in the attached figures are as follows: 1-Injection pump; 2-Liquid CO2 storage tank; 3-Penicillin-based chemical solution storage tank; 4-Seabed sediment model; 5-Visual reaction vessel; 6-High-speed camera. DETAILED DESCRIPTION

[0044] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for enhanced geological storage of carbon dioxide through self-emulsification, which includes the following steps:

[0047] S1: An injection well is established in the seabed sedimentary layer. The wellhead location of the injection well includes the seabed CO2 hydrate stable zone and the area below the seabed CO2 hydrate stable zone.

[0048] The temperature range of the seabed CO2 hydrate stability zone is 3-10℃, and the pressure range is 6-12MPa; the lowest temperature in the area below the seabed CO2 hydrate stability zone is 12℃.

[0049] The injection well includes a CO2 injection well and a penicillin-type chemical injection well, or the injection well includes a mixture of CO2 and penicillin-type chemical injection well; and the horizontal section of the penicillin-type chemical injection well is higher than the horizontal section of the CO2 injection well.

[0050] S2: Penicillin-type chemical agents and liquid CO2 are injected into the seabed sedimentary layer through an injection well;

[0051] The penicillin-type chemical agents include, but are not limited to, penicillin G class, specifically including one or more of penicillin potassium, penicillin sodium and oxacillin;

[0052] The injected penicillin-type chemical agent is a solution of penicillin-type chemical agent;

[0053] The concentration of penicillin-based chemicals in the seabed sediment layer after injection was 0.5 wt%-1.0 wt%.

[0054] The injection methods for penicillin-type chemical agents and liquid CO2 are mixed injection, sequential injection, or alternating injection;

[0055] The mixed injection includes: mixing a solution of penicillin-type chemical agent with liquid CO2 and then injecting it into the target seafloor layer through an injection well;

[0056] The step-by-step injection includes: first injecting a solution of penicillin-type chemical agents into the seabed target layer through injection wells, and then injecting liquid CO2 into the seabed target layer;

[0057] The alternating injection includes: injecting a solution of a certain total amount of penicillin-type chemical agent into the seabed target layer in multiple injections through an injection well; and injecting CO2 into the seabed target layer multiple times during the intervals between solution injections.

[0058] S3: CO2 carrying penicillin-like chemicals and seawater flow in the sediments of the seabed sedimentary layer, and the CO2 undergoes self-emulsification to form a water-in-water CO2 microemulsion. The droplet size of the water-in-water CO2 microemulsion is less than 360 μm. Under the impetus of injection pressure and buoyancy, the mixed fluid containing the water-in-water CO2 microemulsion displaces the porous seawater and diffuses in the seabed sedimentary layer in a bowl-shaped distribution, thereby achieving geological sequestration of carbon dioxide.

[0059] It should be noted that this invention does not specifically limit the end point of carbon dioxide sequestration. Those skilled in the art will understand that if injection occurs in the hydrate stability zone, the injection pressure will be too high due to hydrate formation, therefore the sequestration end point depends on the maximum injection pressure of the equipment used in the project; if injection occurs in the region below the hydrate stability zone, then the sequestration end point need not be considered.

[0060] A schematic diagram of the CO2 self-emulsification enhanced geological sequestration process in this embodiment is shown below. Figure 1 As shown.

[0061] Example 2

[0062] This embodiment provides a method for enhanced geological sequestration of carbon dioxide through self-emulsification. The method involved physical simulation experiments, targeting the CO2 hydrate stability zone (i.e., the hydrate formation zone). The physical simulation experimental apparatus used is as follows: Figure 2 As shown.

[0063] The physical simulation experimental device includes an injection pump 1, a liquid CO2 storage tank 2, a penicillin-type chemical agent solution storage tank 3, a seabed sediment layer model 4, a visual reaction vessel 5, and a high-speed camera 6.

[0064] The method in this embodiment includes the following steps:

[0065] (1) A seabed reservoir similar to the seabed sedimentary layer was pre-prepared in a one-dimensional model to obtain a seabed sedimentary layer model 4 (6℃, 8.7MPa). The sodium penicillin solution in the penicillin chemical agent solution storage tank 3 was injected into the seabed sedimentary layer model 4 using the injection pump 1 to obtain a simulated seabed reservoir with added sodium penicillin. The injection end and the production end of the seabed sedimentary layer model 4 are distributed at its upper and lower ends.

[0066] (2) Liquid CO2 is continuously injected into the reservoir from the injection end of the seabed sedimentary layer model 4 using injection pump 1 at a constant rate;

[0067] (3) The extraction end of the seabed sedimentary layer model 4 is connected to the visual reaction vessel 5, and the product morphology at the extraction end is recorded in real time using a high-speed camera 6.

[0068] (4) When CO2 leakage is observed at the extraction end, the injection end shall be shut off;

[0069] (5) Open the constant pressure pipeline to keep the reservoir at a constant pressure.

[0070] In contrast, the step of injecting sodium penicillin solution in step (1) of the above method is omitted, and the seabed sedimentary layer model 4, which is similar to the seabed sedimentary layer, is used as the simulated seabed reservoir (6℃, 8.7MPa) to perform the above steps (2)-(5).

[0071] In addition, as a comparison, different amounts of sodium penicillin were injected in step (1) above to obtain simulated seabed reservoirs with different concentrations of sodium penicillin, and experiments on injecting liquid CO2 were carried out on the simulated seabed reservoirs with different concentrations of sodium penicillin (as described in steps (2)-(5) above).

[0072] The experimental results of this embodiment are as follows: Figure 3 and Figure 4 As shown.

[0073] Figure 3 This represents the CO2 injection and conversion rates (hydrate formation zone) corresponding to different concentrations of sodium penicillin in seabed sediments. For example... Figure 3 As shown, for the initial subsea reservoir (without added sodium penicillin), the liquid CO2 injection amount is 0.5789 mol, and the CO2 hydrate conversion amount is 0.2899 mol; in the subsea reservoir with added 0.5 wt% sodium penicillin, the liquid CO2 injection amount can be increased to 1.1688 mol, and the CO2 hydrate conversion amount can be increased to 0.4163 mol; while the liquid CO2 injection amount of the subsea reservoir with added 0.3 wt% sodium penicillin is significantly lower than that of the subsea reservoir with added 0.5 wt% sodium penicillin.

[0074] It can be seen that the method of this embodiment increases the amount of liquid CO2 injected by 102% and the amount of CO2 hydrate conversion by 43.6%, effectively improving the CO2 displacement efficiency and hydrate sequestration capacity of the seabed reservoir. However, the addition of 0.3 wt% sodium penicillin does not increase the amount of CO2 injected. Therefore, it can be seen that only within the concentration range of the penicillin-like chemical agent of this invention can the injected CO2 achieve self-emulsification and thus significantly increase its injection volume. Conversely, below the concentration range of the penicillin-like chemical agent of this invention, CO2 cannot achieve self-emulsification.

[0075] Figure 4 The image shows the self-emulsification phenomenon of liquid CO2 in a seabed sediment layer without added sodium penicillin (left image) and in a seabed sediment layer with added 0.5 wt% sodium penicillin (right image). For example... Figure 4 As shown, the droplet diameter of liquid CO2 after passing through the initial seabed reservoir is about 4.4 mm. After passing through the seabed reservoir with 0.5 wt% added penicillin sodium, due to the self-emulsification phenomenon, a water-in-CO2 microemulsion is formed with a droplet diameter of less than 360 μm, which greatly increases the contact area between CO2 and pore water, resulting in a significant increase in displacement efficiency and a significant increase in CO2 injection volume.

[0076] Example 3

[0077] This embodiment provides a method for enhanced geological sequestration of carbon dioxide through self-emulsification. The method involved physical simulation experiments, targeting the region below the CO2 hydrate stability zone (i.e., the non-hydrate formation zone), and considered the injection methods of sodium penicillin and liquid CO2 (injection one at a time). The physical simulation experimental apparatus used is as follows: Figure 5 As shown.

[0078] The physical simulation experimental setup includes: an injection pump 1, a liquid CO2 storage tank 2, a penicillin-type chemical solution storage tank 3, and a seabed sedimentary layer model 4.

[0079] The method in this embodiment includes the following steps:

[0080] (1) A seabed reservoir similar to the seabed sedimentary layer was pre-prepared in a one-dimensional model to obtain seabed sedimentary layer model 4 (12℃, 12MPa), and the injection end and production end of seabed sedimentary layer model 4 are distributed at its upper and lower ends.

[0081] (2) Using injection pump 1, penicillin sodium solution (the volume ratio of penicillin sodium solution to pore seawater is 1:1) is continuously injected into the reservoir from the injection end of the seabed sedimentary layer model 4 at a constant rate.

[0082] (3) Liquid CO2 is continuously injected into the reservoir from the injection end of the seabed sedimentary layer model 4 using injection pump 1 at a constant rate;

[0083] (4) When CO2 leakage is observed at the extraction end, shut down the injection end.

[0084] In contrast, step (2) of the above method is omitted, that is, the step of injecting penicillin sodium solution is omitted, and only steps (1), (3) and (4) are performed.

[0085] The experimental results of this embodiment are as follows: Figure 6 As shown.

[0086] Figure 6 The figures represent CO2 injection rates in seafloor sediments without added sodium penicillin and CO2 injection rates in seafloor sediments after seawater displacement with 0.5 wt% sodium penicillin (non-hydrate formation zone). Figure 6 As shown, for the initial subsea reservoir, the liquid CO2 injection rate is 1.3336 mol; in the subsea reservoir after displacing seawater with 0.5 wt% sodium penicillin, the liquid CO2 injection rate can be increased to 2.1469 mol. Therefore, the method of this embodiment can increase the liquid CO2 injection rate by 61% in the non-hydrate-forming zone.

Claims

1. A method for enhanced geological sequestration of carbon dioxide through self-emulsification, comprising the following steps: S1: Establish an injection well in the seabed sedimentary layer; S2: Penicillin-type chemical agent and CO2 are injected into the seabed sedimentary layer through an injection well, wherein the injected CO2 is liquid CO2, the penicillin-type chemical agent is penicillin G, the concentration of penicillin-type chemical agent in the seabed sedimentary layer after injection is 0.5 wt%-1.0 wt%, and the penicillin-type chemical agent inhibits the formation kinetics of solid CO2 hydrate; S3: CO2 carrying penicillin-like chemicals and seawater flow in the sediments of the seabed sedimentary layer, and the CO2 undergoes self-emulsification to form a water-in-water CO2 microemulsion. Under the impetus of injection pressure and buoyancy, the mixed fluid containing the water-in-water CO2 microemulsion displaces the porous seawater and diffuses in the seabed sedimentary layer, thereby achieving geological sequestration of carbon dioxide.

2. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S1, the wellhead location of the injection well includes the seabed CO2 hydrate stable zone and the area below the seabed CO2 hydrate stable zone.

3. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 2, wherein, In step S1, the temperature range of the seabed CO2 hydrate stable zone is 3-10 ℃, and the pressure range is 6-12 MPa; the minimum temperature of the area below the seabed CO2 hydrate stable zone is 12 ℃.

4. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S1, the injection well includes a CO2 injection well and a penicillin-type chemical injection well, or the injection well includes a mixture of CO2 and penicillin-type chemical injection well.

5. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 4, wherein, The horizontal section of the penicillin-type chemical injection well is higher than the horizontal section of the CO2 injection well.

6. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, The penicillin-type chemical agents include one or a combination of penicillin potassium, penicillin sodium, and oxacillin.

7. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S2, the injected penicillin-type chemical agent is a solution of penicillin-type chemical agent.

8. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S2, the penicillin-type chemical agent and CO2 are injected in a mixed injection, one-by-one injection, or alternating injection manner.

9. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 8, wherein, In step S2, the mixed injection includes: mixing a solution of penicillin-type chemical agent with CO2 and then injecting it into the target seabed layer through an injection well.

10. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 8, wherein, In step S2, the sequential injection includes: first injecting a solution of penicillin-type chemical agent into the seabed target layer through an injection well, and then injecting CO2 into the seabed target layer.

11. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 8, wherein, In step S2, the alternating injection includes: injecting a solution of a certain amount of penicillin-type chemical agent into the seabed target layer in multiple injections through an injection well; and injecting CO2 into the seabed target layer multiple times during the intervals between solution injections.

12. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S3, the droplet size of the water-in-CO2 microemulsion is less than 360 μm.

13. The method for enhanced geological sequestration of carbon dioxide through self-emulsification according to claim 1, wherein, In step S3, the mixed fluid containing the water-infused CO2 microemulsion diffuses in the seabed sediment layer in a bowl-shaped distribution.

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