Curing and sealing device and method for flowable CO2 hydrate slurry

Abstract

The invention relates to a solidifying and sealing device and method for flowable CO2 hydrate slurry, and the device comprises a casing pipe which is assembled in a shaft of a vertical well or a horizontal well, and the tail end of the casing pipe is perforated to form a perforation section; the oil pipe is arranged in the casing pipe in a sleeved mode, a gap is reserved between the oil pipe and the casing pipe to form an annular space, an oil pipe one-way valve is arranged at the position, close to a wellhead, of the oil pipe, and an injection hole is formed in the pipe wall of the downstream end of the oil pipe; a gap is reserved between the downstream end of the oil pipe and the downstream end of the sleeve so as to form a sleeve bottom space. Preferably, the solidifying and sealing device for the flowable CO2 hydrate slurry further comprises a monitoring assembly, and the monitoring assembly is connected with the oil pipe. According to the method, CO2 slurry which is not easy to solidify can be formed underground, the problem that CO2 hydrate is formed in a near-wellbore zone to block a migration channel and the like is effectively avoided, and the purposes of long-term, continuous and huge carbon injection, solidification and storage are achieved.

Description

Technical Field

[0001] The present invention relates to a device and method for solidifying and storing a flowable CO2 hydrate slurry, and belongs to the technical field of carbon dioxide capture and storage. Background Art

[0002] Injecting CO2 into the ocean floor formation to form hydrates can achieve long-term solidification and storage of carbon dioxide, which is an important method in geological storage of CCUS. After CO2 solidifies to form hydrates, its volume is compressed to 1 / 164 of the volume of a gas with the same molar mass, which is equivalent to establishing a high-density carbon reservoir underground and storing CO2 in solid form, thus attracting the attention of experts at home and abroad. China has a vast sea area, and the ocean floor formations with a temperature below 10°C and a pressure above 3 MPa meet the basic conditions for the formation of the stable zone of carbon dioxide hydrates, providing a good foundation for the solidification and storage of CO2.

[0003] The primary problem faced by the large-scale implementation of CO2 solidification and storage is to achieve long-term and large-scale carbon injection. In the traditional carbon injection process, after CO2 enters a reservoir with suitable temperature and pressure, it combines with formation water to form solid CO2 hydrates, which easily block the channels for CO2 to enter the formation, leading to the termination of carbon injection and restricting the application and popularization of CO2 solidification and storage technology. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a device and method for solidifying and storing a flowable CO2 hydrate slurry. This method can form a CO2 slurry that is not easily solidified underground, effectively avoid problems such as the formation of CO2 hydrates in the near-wellbore zone blocking the migration channels, and achieve the purpose of long-term, continuous, and massive carbon injection and solidification and storage.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A device for solidifying and storing a flowable CO2 hydrate slurry, comprising: A casing, assembled in a vertical well or horizontal wellbore, and the end of the casing is perforated to form a perforated section; A tubing, sleeved inside the casing, and there is a gap between the two to form an annulus space. A tubing check valve is provided at the near-wellhead position of the tubing, and injection holes are provided on the tube wall at the downstream end of the tubing; There is a gap between the downstream end of the tubing and the downstream end of the casing to form a bottom space of the casing.

[0006] Preferably, the device for solidifying and storing a flowable CO2 hydrate slurry further includes a monitoring component, and the monitoring component is connected to the tubing.

[0007] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, the monitoring component includes a pressure sensing system.

[0008] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, further includes a ground adjustment component, and the ground adjustment component is communicatively connected with the monitoring component through an optical cable.

[0009] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, the tubing is a CO2 injection channel, and the annulus space is an aqueous solution injection channel. When injecting, the pressure of the tubing and the annulus space is kept consistent and higher than the formation fluid pressure.

[0010] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, the CO2 injected through the tubing and the aqueous solution injected into the annulus space form a CO2 hydrate slurry in the bottom space of the casing.

[0011] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, the bottom hole pressure is monitored through the ground adjustment component to regulate the injection pressures of CO2 and the aqueous solution.

[0012] The solidification and storage device for the flowable CO2 hydrate slurry, preferably, the ratio of the aqueous solution injected into the annulus space and the CO2 injected into the tubing is controlled to ensure that the CO2 hydrate slurry formed in the bottom space of the casing can flow and will not form a blockage.

[0013] The second aspect of the present invention provides a method for solidifying and storing a flowable CO2 hydrate slurry, including the following steps: Open the tubing check valve, inject CO2 into the tubing, and at the same time inject an aqueous solution into the annulus space. The CO2 enters the bottom space of the casing through the injection holes and mixes with the aqueous solution to form a flowable CO2 hydrate slurry; The bottom hole pressure is monitored in real time through the ground adjustment component, and the ratio of the injected aqueous solution and CO2 is controlled to ensure that the CO2 hydrate slurry formed in the bottom space of the casing has fluidity; The CO2 hydrate slurry is injected into the formation through the perforated section.

[0014] Due to the adoption of the above technical solutions, the present invention has the following advantages: 1. The CO2 solidification and storage method disclosed in the present invention, which uses the tubing and the annulus of the same vertical well or horizontal well to inject carbon dioxide and aqueous solution into the formation respectively, can form a CO2 slurry that is not easily solidified underground, effectively avoiding problems such as the formation of CO2 hydrate blockage in the near-wellbore zone and migration channels, and achieving the purpose of long-term, continuous, and massive carbon injection and solidification and storage.

[0015] 2. The carbon injection implementation method disclosed by the present invention can not only solve the problem of pore plugging in the near-wellbore zone during solidification and storage, but also save engineering costs to the greatest extent, and achieve the goal of carbon-water injection while basically not changing the original facilities. Description of the Drawings

[0016] Figure 1 Schematic diagram of a CO2 solidification and storage device for carbon-water injection using the annulus between the tubing and the casing provided by an embodiment of the present invention; The reference numerals in the figure are as follows: 1 - casing, 11 - perforated section; 2 - tubing, 21 - injection hole; 3 - annulus space; 4 - bottom space of the casing; 5 - tubing check valve; 6 - monitoring component; 7 - ground adjustment component, 71 - optical cable. Detailed Embodiment

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] 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 technical field to which the present invention belongs. 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 "including" or "comprising" and similar terms mean that the elements or items appearing before the term cover the elements or items listed after the term and their equivalents, without excluding other elements or items. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0019] For the convenience of description, spatial relative relationship terms can be used in the text to describe the relationship between one element or feature shown in the figure and another element or feature. These relative relationship terms such as "inner", "outer", "inner side", "outer side", "below", "above", etc. are intended to include different orientations of the device during use or operation in addition to the orientations depicted in the figure.

[0020] The primary challenge facing large-scale implementation of CO2 solidification and storage is achieving long-term, large-scale carbon injection. During traditional carbon injection, upon entering a reservoir at a suitable temperature and pressure, CO2 combines with formation water to form solid CO2 hydrates. This can easily block the passage of CO2 into the formation, leading to blockage and termination of carbon injection, thus hindering the application and promotion of CO2 solidification and storage technology.

[0021] Based on the above technical problems, the present invention provides a solidification and sealing device and method for forming a flowable CO2 hydrate slurry by carbon-water injection in the annulus of oil pipes and casings. This method can form CO2 slurry that is not easy to solidify underground, effectively avoiding the formation of CO2 hydrates in the near-well zone that block the migration channel, and achieve the purpose of long-term, continuous, and large-scale carbon injection and solidification and sealing.

[0022] like Figure 1 As shown, the present invention provides a solidification and storage device for forming a flowable CO2 hydrate slurry by injecting carbon-water into the annulus of the oil pipe and casing, comprising: Casing 1 is installed in a vertical or horizontal wellbore, with the distal end of casing 1 perforated to form a perforated section 11. A tubing 2 is sleeved within casing 1 with a gap between the two to form an annulus 3. A tubing check valve 5 is provided near the wellhead of tubing 2, and an injection hole 21 is provided on the wall of the downstream end of tubing 2. A gap is left between the downstream end of tubing 2 and the downstream end of casing 1 to form a casing bottom space 4.

[0023] In a preferred embodiment of the present invention, a monitoring component 6 is further included. The monitoring component 6 is connected to the oil pipe 2 and includes a pressure sensing system.

[0024] In a preferred embodiment of the present invention, a ground adjustment component 7 is further included, and the ground adjustment component 7 is communicatively connected to the monitoring component 6 via an optical cable 71 .

[0025] Further, if Figure 1 As shown, the oil pipe 2 is a CO2 injection channel, and the annular space 3 is a water solution injection channel. During injection, the pressure of the oil pipe 2 and the annular space 3 is kept consistent and higher than the formation fluid pressure.

[0026] Further, if Figure 1 As shown, CO2 injected into the oil pipe 2 and the aqueous solution injected into the annular space 3 form a CO2 water slurry in the bottom space 4 of the casing.

[0027] Further, if Figure 1 As shown, the bottom hole pressure is monitored by the surface adjustment component 7 to adjust the injection pressure of CO2 and aqueous solution.

[0028] Further, if Figure 1As shown, control the ratio of the aqueous solution injected into the annulus space 3 and CO2 injected into the tubing 2 to ensure that the CO2 hydrate slurry formed in the bottom space 4 of the casing can flow and no blockage will occur.

[0029] The second aspect of the present invention provides a method for solidifying and storing a flowable CO2 hydrate slurry, including the following steps: Open the tubing one-way valve 5, inject CO2 into the tubing 2, and at the same time inject an aqueous solution into the annulus space 3. The CO2 enters the bottom space 4 of the casing through the injection holes 21 and mixes with the aqueous solution to form a flowable CO2 hydrate slurry; Real-time monitor the bottom hole pressure through the ground adjustment assembly 7, control the ratio of the injected aqueous solution and CO2 to ensure the fluidity of the CO2 hydrate slurry formed in the bottom space 4 of the casing; the CO2 hydrate slurry is injected into the formation through the perforation section 11.

[0030] The CO2 solidification and storage method disclosed by the present invention, which uses the same vertical well or horizontal well tubing and casing annulus to inject carbon dioxide and aqueous solution into the formation respectively, can form a CO2 slurry that is not easily solidified underground, effectively avoid problems such as the formation of CO2 hydrate blockage in the near-wellbore zone and the migration channel, and achieve the purpose of long-term, continuous, and massive carbon injection and solidification and storage.

[0031] The carbon injection implementation method disclosed by the present invention can not only solve the problem of pore blockage in the near-wellbore zone during solidification and storage, but also save engineering costs to the greatest extent, and achieve the goal of carbon-water separate injection without basically changing the original facilities.

[0032] 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 solidification and storage device for a flowable CO2 hydrate slurry, characterized in that, Comprising: A casing (1) assembled in a vertical well or a horizontal wellbore, and the end of the casing (1) is perforated to form a perforated section (11); A tubing string (2) sleeved inside the casing (1), with a gap left between the two to form an annulus space (3). A tubing check valve (5) is provided at a position near the wellhead of the tubing string (2), and an injection hole (21) is provided on the pipe wall at the downstream end of the tubing string (2); A gap is left between the downstream end of the tubing string (2) and the downstream end of the casing (1) to form a bottom space (4) of the casing; 2. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 1, characterized in that, It further includes a monitoring assembly (6), and the monitoring assembly (6) is connected to the tubing string (2); 3. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 2, characterized in that, The monitoring assembly (6) includes a pressure sensing system; 4. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 3, characterized in that, It further includes a ground adjustment assembly (7), and the ground adjustment assembly (7) is communicatively connected to the monitoring assembly (6) through an optical cable (71); 5. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 1, wherein The tubing string (2) is a CO2 injection channel, and the annulus space (3) is an aqueous solution injection channel. During injection, the pressure of the tubing string (2) is kept consistent with that of the annulus space (3), and is higher than the formation fluid pressure; 6. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 1, wherein The CO2 injected through the tubing string (2) and the aqueous solution injected through the annulus space (3) form a CO2 hydrate slurry in the bottom space (4) of the casing; 7. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 6, characterized in that, The bottom hole pressure is monitored through the ground adjustment assembly (7) to regulate the injection pressures of CO2 and the aqueous solution; 8. The solidification and storage device for the flowable CO2 hydrate slurry according to claim 7, characterized in that, The ratio of the aqueous solution injected into the annulus space (3) and the CO2 injected into the tubing string (2) is controlled to ensure that the CO2 hydrate slurry formed in the bottom space (4) of the casing can flow and will not form a blockage; 9. A method for solidifying and storing a flowable CO2 hydrate slurry, characterized in that, Including the following steps: Open the tubing check valve (5), inject CO2 into the tubing string (2), and simultaneously inject an aqueous solution into the annulus space (3). The CO2 enters the bottom space (4) of the casing through the injection hole (21) and mixes with water to form a flowable CO2 hydrate slurry; The bottom hole pressure is monitored in real time through the ground adjustment assembly (7), and the ratio of the injected aqueous solution and CO2 is controlled to ensure the fluidity of the CO2 hydrate slurry formed in the bottom space (4) of the casing; The CO2 hydrate slurry is injected into the formation through the perforated section (11).

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