A method for forming a closed cap layer by simulation and then realizing CO2 storage

Abstract

The present application relates to a method for forming a closed cap layer and then realizing CO2 storage, which comprises the following steps: lowering the temperature of the top of the vertical pipeline and injecting CO2 to generate CO2 hydrate and form a closed hydrate cap layer; injecting CO2 from the bottom of the vertical pipeline, controlling the pressure by the monitoring unit to make the CO2 density less than the density of liquid water, making the injected CO2 expand upward, controlling the temperature and pressure of the vertical pipeline in the CO2 hydrate generation area, so that the CO2 injected from the bottom of the vertical pipeline does not overflow under the trapping effect of the hydrate cap layer, and finally generating solid hydrate to achieve the purpose of solidification storage. The method is to form a closed hydrate cap layer first, and then inject CO2 from the bottom of the vertical pipeline. The CO2 sealed by the hydrate cap layer is gradually converted into solid hydrate under the condition of segmented temperature control to realize the process of solidification storage.

Description

TECHNICAL FIELD

[0001] The application relates to a method for forming a closed upper cover layer and realizing CO2 storage in simulation, and belongs to the technical field of CO2 solidification and storage. BACKGROUND

[0002] The hydrate method solid-state storage CO2 technology refers to the characteristics that CO2 is easy to generate solid hydrates (the generation pressure is about 2.082 MPa at 277.6 K), and CO2 is injected into the onshore frozen land belt, seawater or the seabed below the mud line to generate solid hydrates, so that the CO2 gas is stored in the sea in the form of solid. As a new technical direction, the marine CO2 hydrate solid-state storage has the advantages of good stability, huge storage capacity and wide distribution of storage sites, and has been highly valued by researchers in recent years. An important subdivision direction of the technology development is to form a closed CO2 / CH4 hydrate cover layer first, which can ensure that the CO2 below the cover layer will not leak in a short time, and then inject CO2 below the cover layer, so that the CO2 is slowly converted into solid hydrates or is sealed by the closed upper cover layer to achieve the purpose of storage. However, there is no experimental method for simulating the CO2 hydrate solidification and storage at present. SUMMARY

[0003] In view of the above technical problems, the application provides a method for forming a closed upper cover layer in simulation and realizing CO2 storage. The method is to form a closed hydrate upper cover layer first, and then inject CO2 from the bottom of the vertical pipeline. The CO2 sealed by the hydrate upper cover layer is gradually converted into solid hydrates under the condition of segmented temperature control to realize the process of solidification and storage.

[0004] To achieve the above purpose, the application adopts the following technical scheme:

[0005] A method for forming a closed upper cover layer in simulation and realizing CO2 storage, the method is based on a CO2 hydrate solidification and storage experimental device, the device comprises a vertical pipeline, a rotating frame arranged on a turnover frame, and the vertical pipeline is composed of a plurality of pipeline units connected in series; a segmented temperature control device comprising a plurality of temperature control boxes, a plurality of temperature control boxes and a plurality of pipeline units are arranged one by one, and the temperature control boxes are used for independently controlling the temperature of each pipeline unit; a monitoring terminal and a plurality of monitoring units, a plurality of monitoring units are electrically connected with the monitoring terminal, and a plurality of monitoring units and a plurality of pipeline units are arranged one by one, and the monitoring units are used for monitoring each pipeline unit.

[0006] The method comprises the following steps:

[0007] Lowering the temperature at the top of the vertical pipeline and injecting CO2 to generate CO2 hydrates, and forming a closed hydrate upper cover layer;

[0008] Injecting CO2 from the bottom of the vertical pipe, controlling the pressure by the monitoring unit to make the density of CO2 less than the density of liquid water, making the injected CO2 expand upward, controlling the temperature and pressure of the vertical pipe in the CO2 hydrate formation area, so that the CO2 injected from the bottom of the vertical pipe is not overflowed under the trapping of the hydrate cap layer, and finally solid hydrate is formed to achieve the purpose of solidification and storage.

[0009] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, when the injection pressure of the vertical pipe is small and the density of CO2 is less than the density of water, CO2 is injected from the top of the vertical pipe to form a closed hydrate cap layer; when the injection pressure is large and the density of CO2 is greater than the density of water, CO2 is first injected from the bottom of the vertical pipe to form a closed hydrate cap layer, and then the vertical pipe is turned over by 180 degrees, with the bottom upward as the top, to achieve the goal of forming a closed hydrate cap layer.

[0010] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, further comprises the following steps: after the formation of the hydrate cap layer, a certain amount of N2 gas can be mixed into the injected CO2 when CO2 is injected from the bottom of the vertical pipe, and gas samples are taken from the top of the vertical pipe at regular intervals during the experiment to analyze whether the sample gas component contains N2, so as to judge the sealing performance of the hydrate cap layer.

[0011] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, the top and bottom of the vertical pipe are provided with a perspective window (5).

[0012] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, the top and bottom of the vertical pipe are provided with an injection and drainage port (6).

[0013] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, each of the pipe units (1) is provided with a gas injection port (7).

[0014] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, the monitoring unit comprises a temperature monitor, a pressure monitor, a sound wave monitor and a resistance detector.

[0015] The method of first simulating the formation of a closed cap layer and then realizing CO2 storage, preferably, the monitoring terminal is a computer (4).

[0016] The present application has the following advantages due to the above technical scheme:

[0017] 1. The vertical pipeline in the application adopts a segmented temperature control mode, and the same number of refrigerant circulation boxes as the number of segments of the vertical pipeline is correspondingly arranged, and the temperature of each refrigerant circulation box is controlled individually. In the experiment, one refrigerant circulation box controls the temperature of one segment (pipeline unit) of the vertical pipeline, and according to the experimental needs, whether each segment has the temperature and pressure conditions for generating CO2 hydrate is flexibly controlled, so as to respectively study the diffusion and hydrate generation law of CO2 in the vertical pipeline under the temperature and pressure conditions in which CO2 hydrate cannot be generated and can be generated.

[0018] 2. The method for forming a closed hydrate upper cover layer and then realizing CO2 storage provided by the application forms a closed hydrate upper cover layer first, and then injects CO2 from the bottom of the vertical pipeline. The CO2 sealed by the hydrate upper cover layer is gradually converted into solid hydrate to realize solidification and storage under the condition of segmented temperature control, and the sealing property of the upper cover layer can be analyzed at the same time, so that the method has good practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is a schematic view of a CO2 hydrate solidification and storage experiment device provided by an embodiment of the application;

[0020] The various marks in the figure are as follows:

[0021] 1-pipeline unit; 2-turnover frame; 3-temperature control box; 4-computer; 5-perspecitve window; 6-liquid injection and discharge port; 7-gas injection port. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the application more clear, the technical scheme in the application is described clearly and completely below. Obviously, the described embodiments are some embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0023] Unless otherwise defined, the technical terms or scientific terms used in the application should be understood as the usual meanings understood by those skilled in the art. The terms "first", "second", "third", "fourth" and similar words used in the application do not represent any order, number or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect.

[0024] For the convenience of description, spatial relative terms such as "inner", "outer", "inside", "outside", "below", "above", etc. can be used in the description to describe the relationship of one element or feature to another element or feature as shown in the drawings. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientations depicted in the drawings.

[0025] The existing hydrate method of solid-state storage of CO2 refers to the characteristics that CO2 is easy to form a solid hydrate (the generation pressure is about 2.082 MPa at 277.6 K), and CO2 is injected into the onshore frozen land belt, seawater or below the mud line of the seabed to generate a solid hydrate, so that CO2 gas is stored in the sea in a solid state. As a new technical direction, the marine CO2 hydrate solid-state storage has the advantages of good stability, huge storage capacity and wide distribution of storage sites, and has been highly valued by researchers in recent years. An important subdivision direction of the development of the technology is to form a closed CO2 / CH4 hydrate cap layer first, which can ensure that the CO2 below the cap layer will not leak in a short time, and then inject CO2 below the cap layer, so that the CO2 is slowly converted into a solid hydrate or is sealed by the closed cap layer to achieve the purpose of storage. However, there is no experimental device and method that can simulate the solidification and storage of CO2 hydrate at present.

[0026] Based on the above problems, the method for simulating the formation of a closed upper cap layer and then realizing the storage of CO2, which is based on a CO2 hydrate solidification and storage experimental device, the experimental device comprises a vertical pipeline, a rotating frame arranged on a turnover frame 2, and the vertical pipeline is composed of a plurality of pipeline units 1 connected in series; a segmented temperature control device comprising a plurality of temperature control boxes 3, the plurality of temperature control boxes 3 are arranged one by one corresponding to the plurality of pipeline units 1, and are used for independently controlling the temperature of each pipeline unit 1; a monitoring terminal and a plurality of monitoring units, the plurality of monitoring units are electrically connected with the monitoring terminal, and the plurality of monitoring units are arranged one by one corresponding to the plurality of pipeline units 1, and are used for monitoring each pipeline unit 1.

[0027] As shown in Figure 1 The method for simulating the formation of a closed upper cap layer and then realizing the storage of CO2 according to the present application is based on a CO2 hydrate solidification and storage experimental device, the experimental device comprises a vertical pipeline, a rotating frame arranged on a turnover frame 2, and the vertical pipeline is composed of a plurality of pipeline units 1 connected in series; a segmented temperature control device comprising a plurality of temperature control boxes 3, the plurality of temperature control boxes 3 are arranged one by one corresponding to the plurality of pipeline units 1, and are used for independently controlling the temperature of each pipeline unit 1; a monitoring terminal and a plurality of monitoring units, the plurality of monitoring units are electrically connected with the monitoring terminal, and the plurality of monitoring units are arranged one by one corresponding to the plurality of pipeline units 1, and are used for monitoring each pipeline unit 1.

[0028] The CO2 storage method of the present application comprises the following steps:

[0029] Lowering the temperature at the top of the vertical pipeline and injecting CO2 to generate CO2 hydrate, form a closed hydrate upper cap layer;

[0030] CO2 is injected from the bottom of the vertical pipe, and the pressure is controlled by the monitoring unit to make the density of CO2 less than the density of liquid water, so that the injected CO2 expands upward, the temperature and pressure of the vertical pipe are controlled in the CO2 hydrate formation region, so that the CO2 injected from the bottom of the vertical pipe is not overflowed under the trapping effect of the hydrate cap layer, and finally the solid hydrate is formed, so that the purpose of solidification and storage is achieved.

[0031] Further, when the injection pressure of the vertical pipe is small and the density of CO2 is less than the density of water, CO2 is injected from the top of the vertical pipe to form a closed hydrate cap layer; when the injection pressure is large and the density of CO2 is greater than the density of water, CO2 is first injected from the bottom of the vertical pipe to form a closed hydrate cap layer, and then the vertical pipe is turned over by 180 degrees, the bottom is upward as the top, to realize the purpose of forming a closed hydrate cap layer.

[0032] The CO2 storage method disclosed in the application further comprises the following steps: after the formation of the hydrate cap layer, a certain amount of N2 gas can be mixed into the injected CO2 when CO2 is injected from the bottom of the vertical pipe, and gas samples are taken from the top of the vertical pipe at regular intervals during the experiment to analyze whether the sample gas composition contains N2, so as to judge the sealing performance of the hydrate cap layer.

[0033] As shown in Figure 1 The vertical pipe adopts a segmented temperature control mode, and the same number of refrigerant circulating boxes (temperature control boxes 3) are arranged according to the number of segments of the pipe unit 1 in the vertical pipe, and the temperature of each refrigerant circulating box is controlled separately. During the experiment, one refrigerant circulating box controls the temperature of one segment (pipe unit 1) of the vertical pipe, and according to the experimental needs, whether each segment has the temperature and pressure conditions for CO2 hydrate formation is flexibly controlled, so as to respectively study the diffusion and hydrate formation law of CO2 in the vertical pipe under the temperature and pressure conditions that cannot form hydrate and can form hydrate.

[0034] In some specific examples, the top and bottom of the vertical pipe are provided with a perspective window 5, and the top and bottom of the vertical pipe are provided with an injection and discharge liquid port 6, and each pipe unit 1 is provided with a gas injection port 7.

[0035] Further, the monitoring unit comprises a temperature monitor, a pressure monitor, a sound wave monitor and a resistance detector, which records the temperature, pressure, sound wave and resistance data at different positions in real time during the experiment, and analyzes the CO2 hydrate formation position, formation speed and formation amount in the vertical pipe in combination with the phenomena directly observed from the perspective window 5. The monitoring terminal is a computer 4.

[0036] The method for forming a closed upper cover layer first and then realizing CO2 storage has better practical application value.

[0037] Finally, it should be noted that the above examples are used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of forming a seal cap layer by simulation and then realizing CO2 sequestration, characterized in that, The method is based on a CO2 hydrate solidification and storage experimental device, which comprises a vertical pipeline arranged on a turnover frame (2), wherein the vertical pipeline is formed by connecting a plurality of pipeline units (1) in series; a segmented temperature control device, which comprises a plurality of temperature control boxes (3), wherein the plurality of temperature control boxes (3) are arranged in one-to-one correspondence with the plurality of pipeline units (1) and are used to independently control the temperature of each pipeline unit (1); a monitoring terminal and a plurality of monitoring units, wherein the plurality of monitoring units are electrically connected to the monitoring terminal, the plurality of monitoring units are arranged in one-to-one correspondence with the plurality of pipeline units (1), and the plurality of monitoring units are used to monitor each pipeline unit (1); The method comprises the following steps: When the injection pressure is small and the CO2 density is less than the density of water, the temperature at the top of the vertical pipeline is reduced and CO2 is injected to generate CO2 hydrate and form a closed hydrate upper cap layer; when the injection pressure is large and the CO2 density is greater than the density of water, CO2 is first injected from the bottom of the vertical pipeline to generate a closed hydrate cap layer, and then the vertical pipeline is turned over by 180 degrees, with the bottom facing upwards as the top, to achieve the goal of forming a closed hydrate upper cap layer; CO2 is injected from the bottom of the vertical pipeline, the pressure is controlled by the monitoring unit to make the CO2 density less than the density of liquid water, the injected CO2 is expanded upwards, the temperature and pressure of the vertical pipeline are controlled in the CO2 hydrate generation region, so that the CO2 injected from the bottom of the vertical pipeline does not overflow under the trapping effect of the hydrate upper cap layer, and finally solid hydrate is generated to achieve the purpose of solidification and storage.

2. The method of claim 1, wherein the method further comprises, Further comprising the following steps: after the formation of the hydrate upper cap layer, a certain amount of N2 gas can be mixed into the injected CO2 when CO2 is injected from the bottom of the vertical pipeline, and gas samples are taken from the top of the vertical pipeline at regular intervals during the experiment to analyze whether the sample gas composition contains N2, so as to judge the sealing performance of the hydrate upper cap layer.

3. The method of claim 1, wherein the method further comprises, The top and bottom of the vertical pipeline are both provided with a perspective window (5).

4. The method of claim 1, wherein the method further comprises, The top and bottom of the vertical pipeline are both provided with a liquid injection and discharge port (6).

5. The method of claim 1, wherein the method further comprises: Each pipeline unit (1) is provided with a gas injection port (7).

6. The method of claim 1, wherein the method further comprises: The monitoring unit comprises a temperature monitor, a pressure monitor, a sound wave monitor and a resistance detector.

7. The method of claim 1, wherein the method further comprises: The monitoring terminal is a computer (4).

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