A method for forming a carbon dioxide hydrate reservoir

Abstract

The present invention relates to a method for forming a carbon dioxide hydrate reservoir, comprising the following steps: injecting liquid carbon dioxide into a container through a second valve port and discharging the liquid medium inside the container through a first valve port, maintaining the internal pressure of the container within a pressure threshold; when a large amount of gas appears at the first valve port, stop injecting and close the first valve port, and observe the formation of hydrates inside the container; when the formation rate decreases, open the first valve port to release the gas inside the container, the liquid carbon dioxide vaporizes and absorbs a large amount of heat, the temperature inside the container drops, promoting the formation of carbon dioxide hydrates inside the container, and continue to observe the formation of hydrates inside the container; when the formation rate decreases, close the first valve port and inject liquid carbon dioxide again, and stop injecting after the internal pressure of the container returns to the pressure threshold; repeat steps S40 - S50 until a carbon dioxide hydrate reservoir is obtained. Compared with the prior art, it has the advantage of a relatively fast formation rate.

Description

Technical Field

[0001] The present invention relates to the technical field of the formation of carbon dioxide hydrates, and particularly relates to a method for forming a carbon dioxide hydrate reservoir. Background Art

[0002] The technology of solid-state sequestration of carbon dioxide by hydrate method refers to using the property that carbon dioxide is easy to form solid hydrates (the formation pressure is about 2.082 MPa at 277.6K), injecting carbon dioxide into onshore permafrost zones, seawater or below the seabed mud line to generate solid hydrates, and sequestering carbon dioxide gas in the ocean in solid form. As a new technical direction, the solid-state sequestration of marine carbon dioxide hydrates has advantages such as good stability, huge reserves, and wide distribution of storage locations, and has recently received great attention from researchers. At present, the formation method of carbon dioxide hydrates is still not mature, and there is a problem of relatively low formation rate. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides a method for forming a carbon dioxide hydrate reservoir, which has the advantage of relatively fast formation rate.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for forming a carbon dioxide hydrate reservoir includes the following steps:

[0006] S10: Adjust the temperature and pressure inside the container to a preset temperature threshold and pressure threshold;

[0007] S20: Inject liquid carbon dioxide into the container and discharge the liquid medium inside the container through the first valve port, and keep the internal pressure of the container within the pressure threshold;

[0008] S30: When a large amount of gas appears at the first valve port, stop injecting and close the first valve port, and observe the formation of hydrates inside the container;

[0009] S40: When the formation rate decreases, open the first valve port to release the gas inside the container. The liquid carbon dioxide vaporizes and absorbs a large amount of heat, and the temperature inside the container drops, promoting the formation of carbon dioxide hydrates inside the container, and continue to observe the formation of hydrates inside the container;

[0010] S50: When the formation rate decreases, close the first valve port and inject liquid carbon dioxide again. Stop injecting after the internal pressure of the container returns to the pressure threshold;

[0011] S60: Repeat steps S40 - S50 until a carbon dioxide hydrate reservoir is obtained.

[0012] In one embodiment:

[0013] After the S60 obtains the carbon dioxide hydrate reservoir, carbon dioxide gas mixed with nitrogen is introduced into the bottom of the container; during the experiment, gas samples are taken from the first valve port at regular intervals to analyze whether the sample gas components contain nitrogen, determine the tightness of the carbon dioxide hydrate reservoir, and analyze the carbon dioxide sequestration volume.

[0014] In one embodiment:

[0015] The container is externally connected to a temperature control device through a pipeline, and the temperature control device circulates the liquid in the container for temperature adjustment.

[0016] In one embodiment,

[0017] The container is provided with a parameter monitor, and the parameter monitor detects the temperature, pressure, sound wave, and resistance in the container;

[0018] The parameter monitor is electrically connected to an external computer, and the detection data is displayed through the computer.

[0019] In one embodiment, the temperature threshold is 7 degrees Celsius.

[0020] In one embodiment, the pressure threshold is 10 MPa.

[0021] Due to the above technical solutions adopted by the present invention, it has the following advantages:

[0022] During the formation process of the hydrate, a dense carbon dioxide hydrate reservoir is formed by repeatedly injecting carbon dioxide and releasing pressure multiple times. During the pressure release process of liquid carbon dioxide, the vaporization of liquid carbon dioxide requires heat absorption, thereby further reducing the temperature of the container system, which can promote the further rapid conversion of liquid carbon dioxide in the system into carbon dioxide hydrate, thereby increasing the formation rate of carbon dioxide hydrate. Compared with the prior art, it has the advantage of a relatively fast formation rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the specific principle of the simulation device in an embodiment of the present invention;

[0024] The marks in the figure are as follows:

[0025] 1. Container; 2. Temperature control device; 3. Computer; 4. First valve port; 5. Second valve port; 6. Third valve port; 7. Parameter monitor; 8. Observation window. DETAILED DESCRIPTION OF THE INVENTION

[0026] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be described clearly and completely below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. The terms "first", "second", "third", "fourth" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0028] The technology of solid-state sequestration of carbon dioxide by hydrate method refers to the utilization of the property that carbon dioxide is prone to form solid hydrates (the formation pressure is about 2.082 MPa at 277.6 K), injecting carbon dioxide into onshore permafrost areas, seawater or below the seabed mud line to form solid hydrates, and sequestering carbon dioxide gas in the ocean in solid form. As a new technical direction, the solid-state sequestration of marine carbon dioxide hydrates has advantages such as good stability, huge reserves and wide distribution of sequestration sites, and has recently received great attention from researchers. At present, the formation method of carbon dioxide hydrates is still not mature, and there is a problem of relatively low formation rate. To address this technical problem, the present invention provides a method for forming a carbon dioxide hydrate reservoir, which has the advantage of relatively fast formation rate.

[0029] The technical solutions of the present invention will be described in detail below with specific examples.

[0030] Refer to Figure 1 As shown, a method for forming a carbon dioxide hydrate reservoir involved in the present invention. In this embodiment, in order to simulate undersea work, the whole method is applied to a simulation device.

[0031] The simulation device specifically includes a container, a temperature control device and a computer. Among them, the liquid medium inside the container is water, the container is connected to the temperature control device through a pipeline, and the temperature control device circulates to adjust the temperature of the liquid in the container. The container is specifically provided with a first valve port, a second valve port and a third valve port. The first valve port is located at the top of the container, the second valve port is located at the side, and the third valve port is located at the bottom of the container.

[0032] A method for forming a carbon dioxide hydrate reservoir specifically includes the following steps:

[0033] S10: Adjust the temperature and pressure inside the container to a preset temperature threshold and pressure threshold;

[0034] S20: Inject liquid carbon dioxide into the container through the second valve port and discharge the liquid medium inside the container through the first valve port, keeping the internal pressure of the container within the pressure threshold;

[0035] S30: When a large amount of gas appears at the first valve port, stop injecting and close the first valve port, and observe the formation of hydrates inside the container;

[0036] S40: When the formation rate decreases, open the first valve port to release the gas inside the container. The liquid carbon dioxide vaporizes and absorbs a large amount of heat, causing the temperature inside the container to drop, promoting the formation of carbon dioxide hydrates inside the container, and continue to observe the formation of hydrates inside the container;

[0037] S50: When the formation rate decreases, close the first valve port and inject liquid carbon dioxide again. Stop injecting after the internal pressure of the container returns to the pressure threshold;

[0038] S60: Repeat steps S40 - S50 until a carbon dioxide hydrate reservoir is obtained.

[0039] It should be noted that during the formation process of hydrates, a dense carbon dioxide hydrate reservoir is formed by repeatedly injecting carbon dioxide and releasing pressure multiple times. During the pressure release process of liquid carbon dioxide, the liquid carbon dioxide vaporizes and needs to absorb heat, thereby further reducing the temperature of the container system, which can prompt the liquid carbon dioxide in the system to be further rapidly converted into carbon dioxide hydrates, thereby increasing the formation rate of carbon dioxide hydrates. Compared with the prior art, it has the advantage of a faster formation rate.

[0040] In one embodiment, the temperature threshold and pressure threshold are further refined. To optimize the simulation effect, in this embodiment, the temperature threshold is specifically 7 degrees Celsius, and the pressure threshold is specifically 10 MPa. The specific preset values are close to the actual conditions of the offshore target area.

[0041] More preferably, in one embodiment, to facilitate observing the formation of hydrates inside the container, a parameter monitor is provided on the container. The parameter monitor detects the temperature, pressure, sound wave, and resistance inside the container. The parameter monitor is electrically connected to an external computer, and the detection data is displayed through the computer. The operator can know the formation status of hydrates inside the container by observing the real-time data displayed on the computer. In addition, to facilitate observing the inside of the container, an observation window is provided on the outside of the container.

[0042] In one embodiment, after obtaining the carbon dioxide hydrate reservoir in S60, at the bottom of the container, carbon dioxide gas mixed with nitrogen is introduced through the third valve port. Meanwhile, during the experiment, gas samples are taken from the first valve port at regular intervals to analyze whether the sample gas components contain nitrogen, determine the tightness of the carbon dioxide hydrate reservoir, and analyze the carbon dioxide storage volume.

[0043] It should be noted that this step can verify the sealing performance of the carbon dioxide hydrate reservoir. When the sealing performance is good, no nitrogen component will be detected in the composition of the sample gas, so as to conduct experimental verification on the carbon dioxide hydrate reservoir.

[0044] Refer to Figure 1 As shown, in this application embodiment, in order to facilitate temperature control of the container, the whole container is divided into three parts: upper, middle and lower. Each part is correspondingly provided with a second valve port, a parameter detector and a temperature control device. Among them, the first valve port is arranged at the top of the whole container, and the third valve port is arranged at the bottom of the whole container.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; 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 invention.

Claims

1. A method for forming a carbon dioxide hydrate reservoir, characterized in that, It includes the following steps: S10: Adjust the temperature and pressure inside the container to a preset temperature threshold and pressure threshold; S20: Inject liquid carbon dioxide into the container and discharge the liquid medium inside the container through the first valve port, keeping the internal pressure of the container within the pressure threshold; S30: When a large amount of gas appears at the first valve port, stop injection and close the first valve port, and observe the formation of hydrate inside the container; S40: When the generation rate decreases, open the first valve port to release the gas inside the container. The liquid carbon dioxide vaporizes and absorbs a large amount of heat, and the temperature inside the container drops, promoting the formation of hydrate of carbon dioxide inside the container, and continue to observe the formation of hydrate inside the container; S50: When the generation rate decreases, close the first valve port and inject liquid carbon dioxide again. Stop injection after the internal pressure of the container returns to the pressure threshold; S60: Repeat steps S40 - S50 until a carbon dioxide hydrate reservoir is obtained; After obtaining the carbon dioxide hydrate reservoir in S60, introduce carbon dioxide gas mixed with nitrogen at the bottom of the container; During the experiment, regularly take gas samples from the first valve port, analyze whether the sample gas components contain nitrogen to determine the tightness of the carbon dioxide hydrate reservoir, and analyze the carbon dioxide storage capacity.

2. The method according to claim 1, wherein: The container is externally connected to a temperature control device through a pipeline, and the temperature control device circulates the liquid inside the container for temperature adjustment.

3. The method according to claim 1, wherein: The container is provided with a parameter monitor, and the parameter monitor detects the temperature, pressure, sound wave and resistance inside the container; The parameter monitor is electrically connected to an external computer, and the detection data is displayed through the computer.

4. The method according to claim 1, characterized in that, The temperature threshold is 7 degrees Celsius.

5. The method according to claim 1, wherein The pressure threshold is 10 MPa.

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