Deepwater underwater decarburization method and S-waveform pipeline system applying same
By adopting an S-waveform pipeline system based on CO2 hydrate phase transition in deep water environment, the underwater separation and decarbonization of CO2 is achieved, solving the problems of high economic costs and engineering risks of existing offshore CCUS technology, and achieving submarine carbon The effect of sealing and cost reduction and efficiency improvement.
Patent Information
- Application Number
- CN202310947991.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-28
- Publication Date
- 2025-02-14
AI Technical Summary
The existing offshore CCUS technology has high economic costs, high engineering safety risks, complex process flow and high cost, especially in deep water environments, which are difficult to effectively separate and reinject CO2.
Deep water underwater decarbonization method is adopted, based on the phase change of CO2 hydrate, and the preset S-waveform pipeline system is used to control the temperature in the rising section and the falling section, so that the CO2 components are converted into hydrate, and the back-discharge branch pipeline is used to convert the CO2 components into hydrate. CO2 hydrates are discharged near the seabed to achieve subsea carbon sequestration.
Underwater separation and decarbonization of CO2 has been achieved, reducing the demand for carbon capture and reinjection equipment on offshore platforms, reducing economic costs and engineering risks, simplifying process flow, and improving efficiency.
Smart Images
Figure CN119434937A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of low-carbon development of marine oil and gas, and in particular to a deep-water underwater decarbonization method and an S-waveform pipeline system using the method. Background Art
[0002] At present, most offshore CCUS lifts the seabed oil and gas together with the associated CO2 gas to the platform, and then injects it back to the seabed after separation, compression and other process treatments. On the one hand, due to the limitations of economic costs, engineering safety and other factors, offshore platforms are usually designed to be relatively compact, and the modification and addition of carbon capture, processing and reinjection equipment will further compress the effective operating space; on the other hand, lifting the associated CO2 gas to the platform and then reinjecting it involves a complex process flow, which consumes a lot of manpower and material resources, and also buries more risks such as gas leakage and compressor explosion. Therefore, during the mining process, the product is first decarbonized underwater (partially or even completely), and then lifted to the offshore platform to reduce or even eliminate the process requirements for carbon capture, processing and reinjection on the platform. This is one of the effective ways to help the offshore CCUS industry reduce costs and increase efficiency.
[0003] Many small molecule gases, including CO2, will be captured by cage structures composed of water molecules under suitable low temperature and high pressure environments, and will be converted from gas to solid to form corresponding hydrates. Since the phase equilibrium conditions corresponding to different gas components are also different, hydrate phase change has also been proposed as a means of fine gas separation. Studies have shown that under the same pressure, the phase equilibrium temperature corresponding to CO2 hydrates is generally significantly higher than the phase equilibrium temperature corresponding to natural gas hydrates mainly composed of CH4, so they can be separated by hydrate phase change. The phase change rate can be regulated by supercooling and surfactants.
[0004] Deep water itself has the characteristics of low temperature, high pressure, and complex wave and current loads. Especially when combined with the water temperature gradient and the geothermal gradient, it can be seen that the temperature near the mud line on the seabed surface is the lowest, which is an ideal environment for the conversion of gaseous products into solid hydrates. Summary of the invention
[0005] The present invention aims to solve the above-mentioned technical problems to a certain extent.
[0006] In order to solve the above technical problems, the present invention provides a deepwater underwater decarbonization method and an S-waveform pipeline system using the method, which can achieve the purposes of CO2 separation, underwater decarbonization and seabed carbon storage.
[0007] A deepwater underwater decarbonization method, characterized in that the method is based on the phase change of CO2 hydrate and comprises the following steps:
[0008] a. Preset configuration: according to the seabed surface environment of the target sea area, including temperature, pressure, wave and current load parameters, the S-shaped configuration of the pipeline is preset, buoys are installed on the pipeline, and the pipeline is divided into ascending section, suspended section, descending section and recovery section according to its shape in deep water;
[0009] b. Finely control the phase change of CO2 hydrate, heat the ascending section pipeline to ensure the safe flow of submarine oil and gas products, and control the temperature of the descending section to ensure that only the CO2 component meets the conditions for hydrate formation and generate CO2 hydrate;
[0010] c. Reinjection of CO2 component hydrates, separating the CO2 hydrates in the oil and gas mixture at the tail of the descending section, allowing the solid phase CO2 hydrates to be re-discharged into the seawater near the seabed, and allowing the gas phase components in the oil and gas mixture to continue to flow upward along the rising section.
[0011] In this method, the S-shaped configuration of the pipeline includes the length and slope of the ascending section, the length of the suspended section, and the slope and length of the descending section. In practice, the lengths of the ascending section, the suspended section, and the slope and length of the descending section are calculated based on the output pressure of the oil and gas products at the wellhead, the flow rate in the pipeline, the density of the oil and gas products, and the reaction time and complete precipitation time of CO2 hydrate.
[0012] An S-wave pipeline system based on the above method comprises a pipeline, a plurality of buoys, a heating cable, a fine temperature control interlayer, a plurality of high-sensitivity pressure probes, a return branch pipeline, a one-way valve and a screen, wherein one end of the pipeline is connected to the wellhead, and the other end is connected to the offshore floating platform. The overall shape of the pipeline in deep water is an S-wave, and can be specifically divided into an ascending section, a suspended section, a descending section and a recovery section, wherein the associated cable is arranged on the outer wall of the ascending section, a plurality of the buoys are fixed on the outer wall of the suspended section, the fine temperature control interlayer is coated on the outer wall of the descending section, the high-sensitivity pressure probes are arranged at intervals in the lumen of the descending section, the bottom of the descending section is connected to the return branch pipeline that is interpenetrating with each other, a one-way valve is installed in the lumen of the return branch pipeline, and the screen is arranged in the lumen of the recovery section near the tail of the descending section.
[0013] Furthermore, a lifting pump is included, which is installed in the recovery section and is used to provide lifting power for the product after decarburization at the tail of the descending section.
[0014] Furthermore, a plurality of the high-sensitivity pressure probes are distributed on the circumferential surface of the pipeline, and a plurality of electric heating units corresponding to the high-sensitivity pressure probes are distributed in the fine temperature adjustment interlayer.
[0015] Furthermore, the high-sensitivity pressure probe is linked with the temperature control system of the fine temperature-adjusting interlayer, and the temperature control system of the fine temperature-adjusting interlayer can adjust the corresponding electric heating power of the electric heating unit according to the pressure value in the pipeline fed back by the high-sensitivity pressure probe in real time.
[0016] Furthermore, the electric heating units are distributed along the axial direction or around the pipeline.
[0017] Furthermore, the heating cable is spread over the pipeline of the ascending section in an S shape.
[0018] Beneficial effects of the present invention: A deep-water underwater decarbonization method has the following advantages: utilizing natural environmental conditions such as low temperature in deep ocean water to induce the CO2 in the product to convert into hydrates, which are deposited in a slurry form, thereby achieving the purpose of underwater separation and decarbonization, streamlining the supporting facilities and industrial processes on the floating body, saving operating space and time, and achieving the purpose of reducing costs and increasing efficiency.
[0019] An S-wave pipeline system based on a deepwater underwater decarbonization method utilizes the S-wave shape of the pipeline to buffer the product flow rate in the rising section and the suspended section, promotes the complete generation of CO2 hydrates in the descending section, and utilizes gravity to cause the generated CO2 hydrate slurry to slide down, thereby avoiding the risk of pipeline blockage caused by excessive accumulation and deposition of CO2 hydrates. At the same time, the slurry is discharged near the seabed surface through a return branch pipeline, and the oil and gas products separated from the CO2 hydrates continue to rise through a recovery pipeline. The structure is simple, easy to operate, and requires low special equipment. The S-shaped sea pipe structure itself is more fatigue-resistant and suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of the overall configuration of an S-waveform pipeline system of a deepwater underwater decarbonization method of the present invention;
[0021] Figure 2 It is a partial view of a rising section of an S-waveform pipeline system of a deepwater underwater decarbonization method of the present invention;
[0022] Figure 3 It is a partial view of a descending section of an S-waveform pipeline system of a deepwater underwater decarbonization method based on hydrate phase change of the present invention;
[0023] Figure 4 A schematic diagram of the connection between the descending section and the rising section of an S-shaped pipeline system of a deepwater underwater decarbonization method based on hydrate phase change according to the present invention;
[0024] In the figure, 1-seabed surface, 2-wellhead, 3-S-shaped corrugated pipe, 301-rising section, 302-suspended section, 303-descending section, 304-recovery section, 305-heating cable, 306-fine temperature adjustment interlayer, 307-high-sensitive pressure probe, 308-screen, 309-check valve, 4-buoy, 5-discharge branch pipe, 6-lifting pump, 7-CO2 hydrate slurry, 8-lifting direction of decarbonized product. DETAILED DESCRIPTION
[0025] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.
[0026] According to an embodiment of the present invention, a deep-water underwater decarbonization method is provided. Figure 1 As shown, the following steps are included:
[0027] a. Preset configuration: according to the seabed surface layer 1 environment of the target sea area, including temperature, pressure, wave and current load parameters, the configuration of the S-shaped pipe 3 is preset, a buoy 4 is installed on the S-shaped pipe 3, and the S-shaped pipe 3 is divided into a rising section 301, a suspended section 302, a descending section 303 and a recovery section 304 in sequence according to its shape in deep water;
[0028] b. Finely control the phase change of CO2 hydrate, heat the rising section 301 of the pipeline to ensure the safe flow of submarine oil and gas products, and control the temperature of the descending section 302 to ensure that only the CO2 component meets the conditions for hydrate formation and generate CO2 hydrate;
[0029] c. CO2 component hydrate reinjection, separating the CO2 component hydrate in the oil and gas mixture at the tail of the descending section 302, so that the solid phase CO2 component hydrate is re-discharged into the seawater near the seabed surface 1, and the gas phase component in the oil and gas mixture continues to flow upward along the rising section 304.
[0030] The configuration of the S-shaped pipe 3 in step a includes the length and slope of the rising section 301, the length of the suspended section 302, and the slope and length of the descending section 303. The lengths of the rising section 301 and the suspended section 302 can be calculated according to the output pressure of the oil and gas products at the wellhead 2, the flow rate in the pipe, and the density of the oil and gas products, and the key parameters affecting the overall configuration of the S-shaped pipe 3, including the height of the suspended section 302, the angles between the rising section 301, the suspended section 302, and the descending section 303, can be adjusted by setting the number, size, position, and buoyancy performance of the buoys 4.
[0031] This method uses natural environmental conditions such as deep ocean water and low temperature to induce the CO2 in the product to convert into hydrates and deposit in a slurry form, thereby achieving the purpose of underwater separation and decarbonization; using the ocean's efficient carbon balance self-regulation ability, CO2 hydrates are discharged near the surface of the seabed. CO2 hydrates are either deposited on the seabed in solid form or dissolved in seawater in a gaseous state after decomposition again, achieving seabed storage;
[0032] An S-wave pipeline system based on the above method, such as Figure 1 to Figure 4 As shown, it includes an S-shaped pipeline 3, a plurality of buoys 4, a heating cable 305, a fine temperature adjustment interlayer 306, a plurality of high-sensitivity pressure probes 307, a return branch pipeline 5, a one-way valve 309 and a screen 308. One end of the S-shaped pipeline 3 is connected to the wellhead 2, and the other end is connected to the offshore floating platform. The S-shaped pipeline 3 in deep water is generally in the form of an S-shaped steep waveform, which can be specifically divided into an ascending section 301, a suspended section 302, a descending section 303 and a rising section 304, wherein the ascending section 30 1 is provided with an associated cable, a plurality of buoys 4 are fixed on the outer wall of the suspended section 302, a fine temperature-adjusting interlayer 306 is coated on the outer wall of the descending section 303, a high-sensitivity pressure probe 307 is arranged at intervals in the lumen of the descending section 303, the bottom of the descending section 303 is connected with a circulating branch pipe 5, a one-way valve 309 is installed in the lumen of the circulating branch pipe 5, and a screen 308 is arranged in the lumen of the recovery section 304 near the tail of the descending section 303.
[0033] In the system, the ascending section 301: one end is connected to the wellhead 2, and the other end is connected to the suspension section 302, which is used to transport the product upward and buffer the product flow rate; the suspension section 302: connects the ascending section 301 and the descending section 303, and is used to construct an S-steep wave configuration and buffer the product flow rate; the descending section 303: connects the suspension section 302 and the rebound section 304, and is used to separate CO2 hydrates 7, and the descending section 303 is long, which provides sufficient reaction time for the precipitation and separation of CO2 in the form of hydrates; the rebound section 304: is located at the tail of the descending section 303, slightly before the return branch pipeline 5, and is used to transport the decarbonized oil and gas products to the sea surface; heating cable 305: S-shaped throughout the ascending section 301, used for proper heating to ensure safe flow of oil and gas products in the ascending section 301; fine temperature adjustment interlayer 306: surrounding the descending section 303, with high-sensitivity pressure probes 307 inserted into the lumen of the descending section 303 at intervals, adjusting the temperature field according to the real-time feedback of the internal pressure of the tube by the high-sensitivity pressure probe 307, so as to achieve the purpose of accurately regulating the phase change conditions and rate, and then separating the CO2 component in the product; high-sensitivity pressure probes 307: several, inserted into the lumen of the descending section 303 by the fine temperature adjustment interlayer 306, real-time monitoring of the pressure in the lumen of the descending section 303 and feedback to the fine adjustment Warm interlayer 306; Screen 308: located in the recovery section 304, near the tail of the descending section 303, to prevent hydrate slurry and a small amount of solid products such as accompanying silt from entering the recovery section 304; Check valve 309: located in the return branch pipeline 5, near the tail of the descending section 303, to prevent seawater from returning to the pipeline; Buoys 4: multiple, installed outside the suspended section 302, used to adjust the key parameters affecting the overall configuration of the S-shaped pipeline 3, including the height of the suspended section 302, the angle between the ascending section 301, the suspended section 302, and the descending section 303; Return branch pipeline 5: located at the tail of the descending section 303, slightly behind the recovery section 3 04, a one-way valve 309 is provided inside, which is used to discharge the CO2 hydrate 7 near the seabed surface 1; CO2 hydrate 7: the CO2 gas in the product combines with water to form hydrate particles under the high pressure and finely controlled low temperature environment in the pipe, and gathers and deposits into slurry near the pipe wall of the descending section 303, and continues to creep downward along the descending section 303 under the action of gravity, drag force, etc., and is finally discharged into the seawater near the seabed surface 1 from the return branch pipe 5 through the one-way valve 309, and the oil and gas products separated from the CO2 hydrate 7 continue to be recovered to the offshore floating platform along the lifting direction 8 of the decarbonized product, that is, the axial direction of the recovery section 304.
[0034] An S-wave pipeline system based on the above method, such as Figure 1 to Figure 4As shown, a lifting pump 6 is also included, which is installed in the lifting section 304 and is used to provide lifting power for the product after decarbonization at the tail of the descending section 303. Several high-sensitive pressure probes 307 are distributed on the circumferential surface of the S-shaped pipeline 3, and a plurality of electric heating units corresponding to the high-sensitive pressure probes 307 are distributed in the fine temperature adjustment interlayer 306. The temperature of the S-shaped pipeline 3 of the descending section 303 can be finely adjusted according to the pressure feedback from the high-sensitive pressure probe 307. In practical applications, the high-sensitive pressure probe 307 is linked with the temperature control system of the fine temperature adjustment interlayer 306, and the temperature control system of the fine temperature adjustment interlayer 306 can adjust the electric heating power of the corresponding electric heating unit according to the pressure value in the S-shaped pipeline 3 fed back by the high-sensitive pressure probe 307 in real time. Specifically, each electric heating unit is distributed along the axial direction of the pipeline 3 or around it, and the electric heating power of the electric heating unit is adjusted in real time and dynamically, thereby realizing timely adjustment of the temperature of the S-shaped pipeline 3, thereby accurately regulating the phase change conditions and rate, so that only the CO2 component in the product meets the hydrate formation conditions.
[0035] The system utilizes the steep wave shape of the S-shaped pipe 3 to buffer the flow rate of oil and gas products in the ascending section 301 and the suspended section 302, promotes the complete generation of CO2 hydrates in the descending section 303, and utilizes gravity to cause the generated CO2 hydrate slurry to slide down, thereby avoiding the risk of pipeline blockage caused by excessive accumulation and deposition of CO2 hydrates. At the same time, the CO2 hydrate slurry is discharged near the seabed surface 1 through the return branch pipe 5, and the oil and gas products separated from the CO2 hydrates continue to rise through the pipeline of the recovery section 304. The structure is simple, easy to operate, and has low equipment requirements. The S-shaped sea pipe structure itself is more fatigue-resistant and suitable for promotion.
[0036] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.
Claims
1. A deepwater underwater decarbonization method, characterized in that: The method is based on the phase transition of CO2 component hydrates and includes the following steps: a. Preset configuration: according to the seabed surface environment of the target sea area, including temperature, pressure, wave and current load parameters, the S-shaped configuration of the pipeline is preset, buoys are installed on the pipeline, and the pipeline is divided into ascending section, suspended section, descending section and recovery section according to its shape in deep water; b. Finely control the phase change of CO2 hydrate, heat the ascending section pipeline to ensure the safe flow of submarine oil and gas products, and control the temperature of the descending section to ensure that only the CO2 component meets the conditions for hydrate formation and generate CO2 hydrate; c. CO2 hydrate reinjection, separating the CO2 hydrate in the oil and gas mixture at the tail of the descending section, allowing the solid phase of CO2 hydrate to be re-discharged into the seawater near the seabed, and allowing the gas phase components in the oil and gas mixture to continue to flow upward along the rising section.
2. A deepwater underwater decarbonization method according to claim 1, characterized in that: The S-shaped configuration of the pipeline includes the length and slope of the ascending section, the length of the suspended section, and the slope and length of the descending section.
3. An S-wave pipeline system based on the above method, characterized in that: It includes a pipeline, a plurality of buoys, a heating cable, a fine temperature control interlayer, a plurality of high-sensitive pressure probes, a return branch pipeline, a one-way valve and a screen. One end of the pipeline is connected to the wellhead, and the other end is connected to the offshore floating platform. The overall shape of the pipeline in deep water is an S-wave shape, and can be specifically divided into an ascending section, a suspended section, a descending section and a recovery section. The outer wall of the ascending section is provided with the accompanying cable, a plurality of buoys are fixed on the outer wall of the suspended section, the outer wall of the descending section is covered with the fine temperature control interlayer, the high-sensitive pressure probes are arranged at intervals in the lumen of the descending section, the bottom of the descending section is connected to the return branch pipeline that is interconnected, a one-way valve is installed in the lumen of the return branch pipeline, and the screen is arranged in the lumen of the recovery section near the tail of the descending section.
4. The S-wave duct system according to claim 3, characterized in that: It also includes a lifting pump, which is installed in the recovery section and is used to provide lifting power for the product after decarbonization at the tail of the descending section.
5. The S-wave duct system according to claim 3, characterized in that: A plurality of the high-sensitivity pressure probes are distributed on the circumferential surface of the pipeline, and a plurality of electric heating units corresponding to the high-sensitivity pressure probes are distributed in the fine temperature adjustment interlayer.
6. The S-wave duct system according to claim 5, characterized in that: The high-sensitivity pressure probe is linked to the temperature control system of the fine temperature-adjusting interlayer, and the temperature control system of the fine temperature-adjusting interlayer can adjust the corresponding electric heating power of the electric heating unit according to the pressure value in the pipeline fed back by the high-sensitivity pressure probe in real time.
7. The S-wave duct system according to claim 6, characterized in that: The electric heating units are distributed along the axial direction of the pipeline or distributed around the pipeline.
8. The S-wave duct system according to claim 3, characterized in that: The heating cable is spread over the pipeline of the ascending section in an S shape.