Deep sea multiphase pump pipe flow guarantee system and method based on foam flow

Abstract

The invention discloses a foam flow-based deep sea mixed transportation pump pipe flow guarantee system and method. The system is formed by a medicament injection system, an underwater foam mixed transportation system and a central platform defoaming system in a synergetic manner, wherein the medicament injection system provides a bifunctional composite medicament for foaming and hydrate inhibition; the underwater foam mixed transportation system is a core function unit, mixing of chemicals and oil-gas products is achieved through an underwater manifold, the flow pattern is adjusted to be stable foam flow through a flow pattern adjusting device, the device can meet different foaming requirements through three working modes, and on-demand pressurization is achieved by matching a mixed transportation pump and bypass redundancy design. And the central platform defoaming system completes defoaming and gas-liquid separation. Through the synergistic effect of foam flow characteristics and agents, the multi-flow guarantee problem is synchronously solved, the system structure and the operation process are remarkably simplified, the deep sea installation and maintenance cost and energy consumption are reduced, the service life of equipment is prolonged, and the oil and gas conveying stability and economical efficiency are improved.

Description

Technical Field

[0001] This invention relates to the technical field of deep-sea oil and gas extraction, and in particular to a deep-sea mixed-transport pump pipe flow assurance system and method based on foam flow. Background Technology

[0002] In the field of deep-sea oil and gas resource development, the long-term and efficient exploitation of deep-sea oil and gas fields and the economic development of marginal oil and gas fields heavily rely on the pump-pipeline transportation system consisting of subsea mixed-transport pumps and pipelines. This system serves as the core transmission carrier, used to transport the multiphase mixture of oil, gas, and water produced from subsea wellheads to the surface processing platform. However, the unique low-temperature, high-pressure environment and multiphase flow characteristics of the deep sea cause the mixed-transport pump-pipeline system to face challenges such as hydrate blockage, liquid accumulation, severe slugging, and unstable inflow conditions during operation.

[0003] Flow assurance is a key technical approach to solving the aforementioned challenges faced by deep-sea oil and gas mixed-transfer pumps and pipelines. Existing technologies have developed a series of targeted solutions, such as: for hydrate blockage, injecting thermodynamic or kinetic inhibitors such as methanol or ethylene glycol to suppress hydrate formation; for liquid accumulation, periodically cleaning the pipeline to drain the accumulated liquid; for severe slug flow, optimizing pipeline layout or adding slug flow traps; and for mixed-transfer pump inflow problems, adding a buffer tank at the pump inlet to stabilize the flow field.

[0004] Currently, each flow assurance problem requires a corresponding solution. While these solutions are highly targeted, they also have the following shortcomings: First, solutions to different problems conflict. For example, injecting large amounts of hydrate thermodynamic inhibitors to prevent hydrate formation increases liquid flow, which in turn increases the risk of liquid accumulation and severe slugging. The pressurization operation of mixed-transport pumps to meet long-distance transport needs further increases pipeline pressure, shortens the hydrate formation induction period, and significantly increases the risk of hydrate blockage. Second, flow assurance systems are highly complex. Existing solutions require designing separate subsystems for each flow assurance problem, resulting in a system consisting of multiple subsystems, with complexity increasing with the number of subsystems. Third, flow assurance methods are cumbersome and have poor compatibility. The implementation of flow assurance methods depends on the flow assurance system. It is necessary not only to ensure that the parameter settings of individual subsystems meet their functional requirements but also to repeatedly debug the parameter matching relationships between different subsystems, making the operation process cumbersome and prone to control deviations.

[0005] In summary, existing flow assurance solutions for deep-sea mixed-transport pump-pipe systems suffer from drawbacks such as conflicting solutions, high system complexity, and cumbersome implementation methods. These solutions are no longer adequate to meet the demands of deep-sea oil and gas development moving towards deeper waters and more complex operating conditions. There is an urgent need for an innovative technical solution that can collaboratively address multiple flow assurance challenges and simplify system structure and operation procedures. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a deep-sea mixed-transport pump pipe flow assurance system and method based on foam flow. By leveraging the characteristics of foam flow and the synergistic effect of reagents, it simultaneously solves multiple flow assurance challenges, significantly simplifies the system structure and operation process, reduces deep-sea installation and maintenance costs and energy consumption, extends equipment lifespan, and improves the stability and economy of oil and gas transportation.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a deep-sea mixed transport pump pipe flow protection system based on foam flow, including a chemical injection system, an underwater foam mixed transport system and a central platform defoaming system; The chemical injection system is used to provide chemical agents with foaming and hydrate control functions, including a first chemical storage tank, a first chemical pump, a first chemical valve, a second chemical storage tank, a second chemical pump, a second chemical valve, an umbilical cable, an umbilical cable terminal, and a chemical injection pipeline; The first chemical storage tank, the first chemical pump, and the first chemical valve are connected in series via pipelines to the umbilical cable. The second chemical storage tank, the second chemical pump, and the second chemical valve are connected in series via pipelines to the umbilical cable. The terminal of the umbilical cable is connected to the underwater foam mixing and transport system via a chemical injection pipeline. The underwater foam mixing and transport system is used to receive chemical agents and adjust the flow pattern of deep-sea oil and gas products into foam flow. It includes an underwater production tree, an upstream pipeline, an underwater manifold, a chemical injection unit, a flow pattern adjustment device, a mixing pump, a mixing pipeline, a first bypass pipe, a first bypass valve, a second bypass pipe, and a second bypass valve. The subsea wellhead is connected to the subsea manifold via an upstream pipeline, the subsea manifold is connected to the chemical injection pipeline via a chemical injection unit, and the subsea manifold is connected to the defoaming system of the central platform via a mixed-transport pipeline. The mixed transport pipeline is arranged with a flow pattern adjustment device and a mixed transport pump in sequence along the fluid transport direction. An upstream valve of the flow pattern adjustment device is set upstream of the flow pattern adjustment device and a downstream valve of the flow pattern adjustment device is set downstream of the flow pattern adjustment device. The first bypass pipe is connected in parallel with the flow pattern adjustment device, and the first bypass valve is set on the first bypass pipe. An upstream valve of the mixed transport pump is set upstream of the mixed transport pump and a downstream valve of the mixed transport pump is set downstream of the pump. The second bypass pipe is connected in parallel with the mixed transport pump, and the second bypass valve is set on the second bypass pipe. The central platform defoaming system is used to eliminate foam and achieve gas-liquid separation. It includes a third reagent storage tank, a third reagent pump, a third reagent valve, a platform reagent pipeline, an oil-gas separator, a liquid storage tank, a gas storage tank, and a platform gas pipeline. The third reagent storage tank, the third reagent pump, and the third reagent valve are connected in series via pipelines. The third reagent valve is connected to the mixed transport pipeline via the platform reagent pipeline. The upstream of the oil-gas separator is connected to the mixed transport pipeline, and the downstream of the oil-gas separator is connected to the liquid storage tank and the gas storage tank, respectively. The downstream of the gas storage tank is connected to the platform gas pipeline.

[0008] Furthermore, the chemical agent stored in the first reagent storage tank is a foaming agent, which includes a main agent with surface activity and hydrate kinetic inhibition and a foam stabilizer with hydrate inhibition; the main agent is a derivative of polyvinylpyrrolidone, and the foam stabilizer is xanthan gum.

[0009] Furthermore, the chemical agents stored in the second reagent storage tank are auxiliary chemical agents for flow protection, including corrosion inhibitors and / or scale inhibitors, and the auxiliary chemical agents are compatible with the foaming agents in the first reagent storage tank.

[0010] Furthermore, the flow pattern adjustment device includes a first flow pattern adjustment tube, a second flow pattern adjustment tube, and a third flow pattern adjustment tube connected in series; the first flow pattern adjustment tube, the second flow pattern adjustment tube, and the third flow pattern adjustment tube are all integrally formed from an upward-sloping tube, a horizontal tube, and a downward-sloping tube in the same vertical plane; The flow pattern adjustment device further includes a valve group, which includes a first valve, a second valve, a third valve, a fourth valve, a fifth valve, a sixth valve, a seventh valve, and an eighth valve. The first valve is located at the upstream end of the first flow pattern adjustment pipe, and the second valve is located at the downstream end of the first flow pattern adjustment pipe. The third valve is located at the upstream end of the second flow pattern adjustment pipe, and the fourth valve is located at the downstream end of the second flow pattern adjustment pipe. The fifth valve is located at the upstream end of the third flow pattern adjustment pipe, and the sixth valve is located at the downstream end of the third flow pattern adjustment pipe. The seventh valve is located on the pipeline connecting the third valve and the sixth valve, and the eighth valve is located on the pipeline connected in parallel with the third flow pattern adjustment pipe.

[0011] Furthermore, the flow pattern adjustment device is a skid-mounted structure, and the flow pattern adjustment device is detachably connected to the mixing pipeline through the upstream valve and the downstream valve of the flow pattern adjustment device.

[0012] Furthermore, the chemical agent stored in the third agent storage tank is a defoamer, the third agent pump is used to adjust the injection flow rate and injection pressure of the defoamer, and the third agent valve is used to control the on / off delivery of the defoamer.

[0013] Furthermore, the underwater foam mixing and transport system also includes pressure sensors, which are installed upstream and downstream of the flow pattern adjustment device and electrically connected to the control unit of the flow pattern adjustment device. These pressure sensors are used to determine the flow pattern characteristics upstream and downstream of the flow pattern adjustment device and then adjust the working mode of the flow pattern adjustment device.

[0014] This invention also provides a flow assurance method for deep-sea mixed-transport pump pipes based on foam flow, applicable to a flow assurance system for deep-sea mixed-transport pump pipes based on foam flow, comprising the following steps: S1. Chemical injection scheme design: Based on the composition and flow rate of deep-sea oil and gas products and deep-sea environmental parameters, select surfactants with foaming and hydrate kinetic inhibition functions as foaming agents, and determine the types, concentrations, injection pressures and injection flow rates of foaming agents, defoamers and auxiliary chemicals. S2. Flow pattern adjustment device control: Based on the flow pattern characteristics upstream and downstream of the flow pattern adjustment device, determine whether the flow pattern can automatically transform into foam flow after the addition of foaming agent; if so, adjust the flow pattern adjustment device to the closed state and open the first bypass valve; if not, adjust the flow pattern adjustment device to the open state, close the first bypass valve, and determine the number of working first flow pattern adjustment pipes, second flow pattern adjustment pipes, and third flow pattern adjustment pipes in the flow pattern adjustment device according to the degree of enhancement required to adjust the flow pattern into foam flow. S3. Mixed Pump Control: The state of the mixed pump is determined by whether the flow system in the pump pipe system can be transported to the central platform defoaming system on its own. If the flow system in the pump pipe system can be transported to the central platform defoaming system on its own, the mixed pump is controlled to be in the closed state and the second bypass valve is opened. If not, the mixed pump is controlled to be in the open state, the second bypass valve is closed, and the mixed pump is used for pressurization.

[0015] Furthermore, in step S2, the flow pattern adjustment device has three operating modes based on the degree of enhancement required to adjust to a foam flow: Operating Mode I: Only the first flow-type regulating pipe is opened, controlling the first, second, and seventh valves to open, and the third, fourth, fifth, sixth, and eighth valves to close; Operating Mode II: Open the first and second flow-type regulating pipes, and control the first, second, third, fourth, and eighth valves to open, while the fifth, sixth, and seventh valves to close; Operating Mode III: Open the first flow regulating pipe, the second flow regulating pipe, and the third flow regulating pipe, and control the first valve, the second valve, the third valve, the fourth valve, the fifth valve, and the sixth valve to open, and the seventh valve and the eighth valve to close; The enhancement of the flow pattern adjustment to foam flow increases progressively from working mode I to working mode II to working mode III.

[0016] The beneficial effects of this invention are: 1. This invention, based on the characteristics of foam flow and the synergistic design of reagents, breaks through the bottlenecks of traditional solutions that are limited by single approaches and conflicting effects, achieving multiple solutions to multiple problems with a single approach: First, the uniform gas-liquid mixing in foam flow can prevent liquid accumulation in low-lying sections of the pipeline, thus achieving effective liquid transport and avoiding the intermittent and high-cost nature of traditional pipeline cleaning operations; Second, the foaming agent is a surface-active hydrate kinetic inhibitor, which can block blockages from both the perspectives of delaying hydrate nucleation and inhibiting crystal growth, eliminating the need for large-scale injection of traditional thermodynamic inhibitors and achieving low-cost hydrate control; Third, the homogeneity and hydraulic stability of foam flow are significantly better than traditional gas-liquid two-phase flow, and its uniform gas-liquid distribution can eliminate drastic fluctuations in pressure and flow rate within the pipeline, avoiding the impact damage of slug flow to valves and pumps; Fourth, the uniform gas-liquid mixing in foam flow creates uniform inlet conditions for mixed-transport pumps, avoiding the adverse effects of traditional non-uniform flow on pump operating efficiency and safety; Fifth, the strong shear force and sand-carrying capacity of foam flow can effectively carry sand particles within the pipeline, preventing sand particles from depositing inside the pipeline.

[0017] 2. Traditional flow support systems consist of multiple subsystems, have complex structures and redundant underwater equipment, while this invention greatly simplifies the system through functional integration and modular design; the flow pattern adjustment device consists of only pipes and valves, and three working modes can be achieved by opening and closing the valves; the flow pattern adjustment device can create uniform inflow conditions for the mixed-transfer pump, thereby replacing the buffer tank.

[0018] 3. The operation process of this invention is simple and intelligent, adaptable to complex working conditions, and the method only requires three core operations: reagent scheme design, flow pattern device regulation, and mixed pump control. Moreover, relying on the linkage of sensors and control units, it can achieve adaptive regulation of working conditions and reduce manual intervention. The parameters can be dynamically adjusted according to the characteristics of oil and gas production and the deep-sea environment. It can be adapted to different development scenarios without replacing the core equipment, and has strong versatility. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the deep-sea mixed-transport pump pipe flow protection system based on foam flow of the present invention.

[0020] Figure 2 This is a schematic diagram of the flow pattern adjustment device in this invention.

[0021] In the diagram: 1. First chemical storage tank; 2. First chemical pump; 3. First chemical valve; 4. Second chemical storage tank; 5. Second chemical pump; 6. Second chemical valve; 7. Umbilical cable; 8. Umbilical cable terminal; 9. Chemical injection pipeline; 10. Subsea Christmas tree; 11. Upstream pipeline; 12. Subsea manifold; 13. Chemical injection unit; 14. First bypass pipe; 15. First bypass valve; 16. Upstream valve of flow pattern adjustment device; 17. Flow pattern adjustment device; 18. Downstream valve of flow pattern adjustment device; 19. Second bypass pipe; 20. Second bypass valve; 21. Upstream valve of mixed transfer pump; 22. Mixed transfer pump; 23. Downstream valve of mixed transfer pump 24. Mixed transport pipeline; 25. Third chemical storage tank; 26. Third chemical pump; 27. Third chemical valve; 28. Platform chemical pipeline; 29. ​​Oil-gas separator; 30. Liquid storage tank; 31. Gas storage tank; 32. Platform gas pipeline; 33. Central platform; 1701. First valve; 1702. First flow pattern regulating pipe; 1703. Second valve; 1704. Third valve; 1705. Second flow pattern regulating pipe; 1706. Fourth valve; 1707. Fifth valve; 1708. Third flow pattern regulating pipe; 1709. Sixth valve; 1710. Seventh valve; 1711. Eighth valve. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] This invention discloses a deep-sea mixed-transport pump pipe flow protection system based on foam flow.

[0024] Reference Figure 1 and Figure 2 A deep-sea mixed transport pump pipe flow protection system based on foam flow includes a chemical injection system, an underwater foam mixed transport system, and a central platform defoaming system; The chemical injection system is fundamental to foam flow control. Its core function is to deliver chemical agents with both foaming and hydrate control functions to the underwater mixed transport system, avoiding the conflicting issues caused by traditional single-function agents. The chemical injection system includes a first chemical storage tank 1, a first chemical pump 2, a first chemical valve 3, a second chemical storage tank 4, a second chemical pump 5, a second chemical valve 6, an umbilical cable 7, an umbilical cable terminal 8, and a chemical injection pipeline 9.

[0025] The first chemical storage tank 1, the first chemical pump 2, and the first chemical valve 3 are connected in series via pipelines to the umbilical cable 7. The second chemical storage tank 4, the second chemical pump 5, and the second chemical valve 6 are connected in series via pipelines to the umbilical cable 7. The umbilical cable terminal 8 is connected to the underwater foam mixing and transport system via the chemical injection pipeline 9.

[0026] The first chemical storage tank 1 stores foaming agents, including a main agent with surface activity and hydrate kinetic inhibition properties, and a foam stabilizer with hydrate inhibition properties. The main agent is a derivative of polyvinylpyrrolidone, which possesses both surface activity and hydrate kinetic inhibition properties. Surface activity reduces the interfacial tension of oil-gas-water multiphase flow, providing conditions for foam formation; hydrate kinetic inhibition delays the nucleation and growth of natural gas hydrates, providing a solution for hydrate control. The foam stabilizer is xanthan gum, which not only extends the foam half-life by increasing liquid phase viscosity, ensuring the stability of the foam system, but also has hydrate inhibition capabilities, forming a dual hydrate protection with the main agent. The second chemical storage tank 4 stores auxiliary chemicals for flow assurance, including corrosion inhibitors and / or scale inhibitors, and these auxiliary chemicals are compatible with the foaming agent in the first chemical storage tank 1. Through the coordinated control of the second chemical pump 5 and the second chemical valve 6, corrosion and scaling problems in deep-sea pipelines can be specifically addressed.

[0027] The subsea foam mixing and transport system is used to receive chemical agents and adjust the flow pattern of deep-sea oil and gas products into foam flow. It includes a subsea production tree 10, an upstream pipeline 11, a subsea manifold 12, a chemical injection unit 13, a flow pattern adjustment device 17, a mixing pump 22, a mixing pipeline 24, a first bypass pipe 14, a first bypass valve 15, a second bypass pipe 19, and a second bypass valve 20. The subsea production tree 10 is connected to the subsea manifold 12 through the upstream pipeline 11. The subsea manifold 12 is connected to the chemical injection pipeline 9 through the chemical injection unit 13. The subsea manifold 12 is connected to the central platform defoaming system through the mixing pipeline 24. The subsea wellhead 10 serves as the outlet of the production well. Through the upstream pipeline 11, the oil, gas and water multiphase mixtures from different wellheads are collected and sent to the subsea manifold 12. The chemical injection unit 13 mixes the foaming agent and auxiliary chemical agents delivered by the chemical injection system with the products in the manifold. The surface activity of the foaming agent facilitates the dispersion of the gas phase into bubbles in the liquid phase, laying the foundation for the formation of foam flow.

[0028] The mixing pipeline 24 is arranged sequentially along the fluid transport direction, with a flow pattern adjustment device 17 and a mixing pump 22. The flow pattern adjustment device 17 is a key component for enhancing foam flow formation, and it adopts a three-pipe series + multi-valve control structure design: the flow pattern adjustment device 17 includes a first flow pattern adjustment pipe 1702, a second flow pattern adjustment pipe 1705, and a third flow pattern adjustment pipe 1708 connected in series; the first flow pattern adjustment pipe 1702, the second flow pattern adjustment pipe 1705, and the third flow pattern adjustment pipe 1708 are all integrally formed from an upward-sloping pipe, a horizontal pipe, and a downward-sloping pipe in the same vertical plane. This structure can utilize gravity and fluid dynamics to create vertical disturbances in the gas-liquid mixture within the pipe, significantly enhancing the mixing intensity of the gas and liquid, and thus transforming the gas-liquid flow pattern into a uniform and stable foam flow; the flow pattern adjustment device 17 can achieve different enhancement levels through precise control of the valve group.

[0029] The flow pattern adjustment device 17 also includes a valve group, which includes a first valve 1701, a second valve 1703, a third valve 1704, a fourth valve 1706, a fifth valve 1707, a sixth valve 1709, a seventh valve 1710, and an eighth valve 1711. The first valve 1701 is located at the upstream end of the first flow pattern adjustment pipe 1702, and the second valve 1703 is located at the downstream end of the first flow pattern adjustment pipe 1702. The third valve 1704 is located at the upstream end of the second flow pattern adjustment pipe 1705, and the fourth valve 1706 is located at the downstream end of the second flow pattern adjustment pipe 1705. The fifth valve 1707 is located at the upstream end of the third flow pattern adjustment pipe 1708, and the sixth valve 1709 is located at the downstream end of the third flow pattern adjustment pipe 1708. The seventh valve 1710 is located on the pipeline connecting the third valve 1704 and the sixth valve 1709, and the eighth valve 1711 is located on the pipeline connected in parallel with the third flow pattern adjustment pipe 1708.

[0030] Upstream of the flow pattern adjustment device 17 is equipped with an upstream valve 16 and downstream of the flow pattern adjustment device 18. The flow pattern adjustment device 17 is a skid-mounted structure. The flow pattern adjustment device 17 is detachably connected to the mixing pipeline 24 through the upstream valve 16 and the downstream valve 18, which reduces the difficulty of installation and maintenance in the deep-sea environment.

[0031] The first bypass pipe 14 is connected in parallel with the flow pattern adjustment device 17, and the first bypass valve 15 is installed on the first bypass pipe 14; thus forming a redundant path for the flow pattern adjustment device 17. When the reagent and the product can form a stable foam flow on their own after mixing, the upstream valve 16 and the downstream valve 18 of the flow pattern adjustment device can be closed, and the first bypass valve 15 can be opened to allow the fluid to be transported through the first bypass pipe 14, thus avoiding the ineffective operation of the flow pattern adjustment device 17; otherwise, the first bypass valve 15 is closed, and the flow pattern adjustment device 17 is opened to achieve foam flow enhancement.

[0032] The mixed-transfer pump 22 serves as a booster device, with an upstream valve 21 and a downstream valve 23. A second bypass pipe 19 is connected in parallel with the mixed-transfer pump 22, and a second bypass valve 20 is installed on the second bypass pipe 19, forming a dual-pathway for boosting and bypassing. When the fluid in the mixed-transfer pipeline 24 has sufficient energy to overcome the friction resistance and can be transported to the central platform 33 on its own, the upstream valve 21 and the downstream valve 23 of the mixed-transfer pump are closed, and the second bypass valve 20 is opened, achieving unboosted transport through the second bypass pipe 19. When the fluid energy is insufficient, such as when the transport distance is long or the pressure loss along the flow path is large, the second bypass valve 20 is closed, and the mixed-transfer pump 22 is turned on to boost the pressure, ensuring that the fluid arrives at the central platform 33 stably.

[0033] In addition, the underwater foam mixing and transport system also includes pressure sensors, which are installed upstream and downstream of the flow pattern adjustment device 17 and electrically connected to the control unit of the flow pattern adjustment device 17. The pressure sensors are used to determine the flow pattern characteristics upstream and downstream of the flow pattern adjustment device 17 and then adjust the working mode of the flow pattern adjustment device 17.

[0034] When the pressure measured by the upstream and downstream pressure sensors of the flow pattern adjustment device 17 is stable, the reagent and the product can form a stable foam flow on their own after mixing. The first bypass valve 15 is opened, and the flow pattern adjustment device 17 is adjusted to the closed state. When the pressure measured by the upstream pressure sensor of the flow pattern adjustment device 17 fluctuates, the reagent and the product cannot form a stable foam flow on their own after mixing. The first bypass valve 15 is closed, and the flow pattern adjustment device 17 is adjusted to the open state. The working mode of the flow pattern adjustment device is determined according to the pressure distribution measured by the upstream pressure sensor of the flow pattern adjustment device 17.

[0035] The central platform defoaming system is used to eliminate foam and achieve gas-liquid separation. It includes a third reagent storage tank 25, a third reagent pump 26, a third reagent valve 27, a platform reagent pipeline 28, an oil-gas separator 29, a liquid storage tank 30, a gas storage tank 31, and a platform gas pipeline 32. The third reagent storage tank 25, the third reagent pump 26, and the third reagent valve 27 are connected in series via pipelines. The chemical reagent stored in the third reagent storage tank 25 is a defoamer. The third reagent pump 26 is used to regulate the injection flow rate and injection pressure of the defoamer, and the third reagent valve 27 is used to control the on / off supply of the defoamer. The third reagent valve 27 is connected to the mixed transport pipeline 24 via the platform reagent pipeline 28. After the defoamer is injected into the mixed transport pipeline 24, it reduces foam stability, transforming the foam flow into a gas-liquid two-phase flow, laying the foundation for subsequent separation.

[0036] The upstream of the oil-gas separator 29 is connected to the mixed-transport pipeline 24. Its core function is to efficiently separate the defoamed gas-liquid mixture. Utilizing the density difference between the gas and liquid phases, it separates the liquid phase from the gas phase through principles such as gravity sedimentation and centrifugal separation. The downstream of the oil-gas separator 29 is connected to the liquid storage tank 30 and the gas storage tank 31, respectively. The downstream of the gas storage tank 31 is connected to the platform gas pipeline 32. The separated liquid phase is stored in the liquid storage tank 30 and can be further transported to the crude oil processing system; the gas phase is stored in the gas storage tank 31 and transported to the natural gas processing system through the platform gas pipeline 32.

[0037] This invention also discloses a flow assurance method for deep-sea mixed-transport pump pipes based on foam flow, applied to the aforementioned deep-sea mixed-transport pump pipe flow assurance system, comprising the following steps: S1. Chemical injection scheme design: Based on the composition and flow rate of deep-sea oil and gas products and deep-sea environmental parameters, select surfactants with foaming and hydrate kinetic inhibition functions as foaming agents, and determine the types, concentrations, injection pressures, and injection flow rates of foaming agents, defoamers, and auxiliary chemicals; among them, deep-sea environmental parameters include deep-sea water temperature, deep-sea pressure, and seawater salinity.

[0038] S2. Flow pattern adjustment device 17 control: Based on the flow pattern characteristics upstream and downstream of the flow pattern adjustment device 17, determine whether the flow pattern can automatically transform into foam flow after the addition of foaming agent; if so, adjust the flow pattern adjustment device 17 to the closed state and open the first bypass valve 15; if not, adjust the flow pattern adjustment device 17 to the open state, close the first bypass valve 15, and determine the working quantity of the first flow pattern adjustment pipe 1702, the second flow pattern adjustment pipe 1705, and the third flow pattern adjustment pipe 1708 in the flow pattern adjustment device 17 according to the enhancement degree required for the flow pattern to be adjusted into foam flow.

[0039] The flow pattern adjustment device 17 has three operating modes depending on the degree of enhancement required to adjust to a foam flow: Operating Mode I: Only the first flow pattern regulating pipe 1702 is opened, controlling the opening of the first valve 1701, the second valve 1703, and the seventh valve 1710, and the closing of the third valve 1704, the fourth valve 1706, the fifth valve 1707, the sixth valve 1709, and the eighth valve 1711. This mode corresponds to the operating condition where the pressure fluctuation measured by the upstream pressure sensor of the flow pattern regulating device 17 is low, the flow system transforms into foam flow after passing through one regulating pipe, and the pressure measured by the downstream pressure sensor of the flow pattern regulating device 17 is stable.

[0040] Operating Mode II: Open the first flow pattern regulating pipe 1702 and the second flow pattern regulating pipe 1705, controlling the opening of the first valve 1701, second valve 1703, third valve 1704, fourth valve 1706, and eighth valve 1711, and the closing of the fifth valve 1707, sixth valve 1709, and seventh valve 1710. In this mode, the pressure fluctuation measured by the upstream pressure sensor of the flow pattern regulating device 17 is moderate, the flow system transforms into foam flow after passing through the two regulating pipes, and the pressure measured by the downstream pressure sensor of the flow pattern regulating device 17 is stable.

[0041] Operating Mode III: The first flow pattern regulating pipe 1702, the second flow pattern regulating pipe 1705, and the third flow pattern regulating pipe 1708 are opened, controlling the first valve 1701, the second valve 1703, the third valve 1704, the fourth valve 1706, the fifth valve 1707, and the sixth valve 1709 to open, and the seventh valve 1710 and the eighth valve 1711 to close. This mode corresponds to the operating condition where the pressure fluctuation measured by the upstream pressure sensor of the flow pattern regulating device 17 is high, the flow system transforms into foam flow after passing through the three regulating pipes in sequence, and the pressure measured by the downstream pressure sensor of the flow pattern regulating device 17 is stable.

[0042] The increasing degree of enhancement of flow pattern adjustment to foam flow from working mode I to working mode II to working mode III is essentially achieved by increasing the number of working flow pattern adjustment tubes, strengthening the disturbance effect of gravity and fluid dynamics, and achieving full coverage of working conditions with different foaming difficulties, thus avoiding the shortcomings of a single mode being unable to adapt to complex deep-sea working conditions.

[0043] S3. Mixed Pump 22 Control: The state of the mixed pump is determined by whether the flow system in the pump pipe system can be transported to the central platform defoaming system on its own. If the flow system in the pump pipe system can be transported to the central platform defoaming system on its own, the mixed pump 22 is controlled to be in the closed state and the second bypass valve 20 is opened. If not, the mixed pump 22 is controlled to be in the open state and the second bypass valve 20 is closed, and the mixed pump 22 is used for pressurization.

[0044] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A deep-sea mixed-transport pump pipe flow assurance system based on foam flow, characterized in that: This includes a chemical injection system, an underwater foam mixing and delivery system, and a central platform defoaming system; The chemical injection system is used to provide chemical agents with foaming and hydrate control functions, including a first chemical storage tank (1), a first chemical pump (2), a first chemical valve (3), a second chemical storage tank (4), a second chemical pump (5), a second chemical valve (6), an umbilical cable (7), an umbilical cable terminal (8), and a chemical injection pipeline (9). The first chemical storage tank (1), the first chemical pump (2), and the first chemical valve (3) are connected in series to the umbilical cable (7) via pipelines. The second chemical storage tank (4), the second chemical pump (5), and the second chemical valve (6) are connected in series to the umbilical cable (7) via pipelines. The umbilical cable terminal (8) is connected to the underwater foam mixing and transport system via a chemical injection pipeline (9). The underwater foam mixing system is used to receive chemical agents and adjust the flow pattern of deep-sea oil and gas products into foam flow. It includes an underwater production tree (10), an upstream pipeline (11), an underwater manifold (12), a chemical injection unit (13), a flow pattern adjustment device (17), a mixing pump (22), a mixing pipeline (24), a first bypass pipe (14), a first bypass valve (15), a second bypass pipe (19), and a second bypass valve (20). The subsea tree (10) is connected to the subsea manifold (12) via the upstream pipeline (11), the subsea manifold (12) is connected to the chemical injection pipeline (9) via the chemical injection unit (13), and the subsea manifold (12) is connected to the central platform defoaming system via the mixed transport pipeline (24); The mixing pipeline (24) is arranged with a flow pattern adjustment device (17) and a mixing pump (22) in sequence along the fluid transport direction. The upstream valve (16) of the flow pattern adjustment device (17) is set upstream and the downstream valve (18) of the flow pattern adjustment device is set downstream. The first bypass pipe (14) is connected in parallel with the flow pattern adjustment device (17), and the first bypass valve (15) is set on the first bypass pipe (14). The upstream valve (21) of the mixing pump (22) is set upstream and the downstream valve (23) of the mixing pump is set downstream. The second bypass pipe (19) is connected in parallel with the mixing pump (22), and the second bypass valve (20) is set on the second bypass pipe (19). The central platform defoaming system is used to eliminate foam and achieve gas-liquid separation. It includes a third agent storage tank (25), a third agent pump (26), a third agent valve (27), a platform agent pipeline (28), an oil-gas separator (29), a liquid storage tank (30), a gas storage tank (31), and a platform gas pipeline (32). The third agent storage tank (25), the third agent pump (26), and the third agent valve (27) are connected in series through pipelines. The third agent valve (27) is connected to the mixed transport pipeline (24) through the platform agent pipeline (28). The upstream of the oil-gas separator (29) is connected to the mixed transport pipeline (24), and the downstream of the oil-gas separator (29) is connected to the liquid storage tank (30) and the gas storage tank (31), respectively. The downstream of the gas storage tank (31) is connected to the platform gas pipeline (32).

2. The deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to claim 1, characterized in that: The chemical agent stored in the first pharmaceutical storage tank (1) is a foaming agent. The foaming agent includes a main agent with surface activity and hydrate kinetic inhibition and a foam stabilizer with hydrate inhibition. The main agent is a derivative of polyvinylpyrrolidone and the foam stabilizer is xanthan gum.

3. The deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to claim 1, characterized in that: The chemical agent stored in the second chemical storage tank (4) is an auxiliary chemical agent for flow protection. The auxiliary chemical agent includes corrosion inhibitors and / or scale inhibitors, and the auxiliary chemical agent is compatible with the foaming agent in the first chemical storage tank (1).

4. A deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to any one of claims 1-3, characterized in that: The flow pattern adjustment device (17) includes a first flow pattern adjustment tube (1702), a second flow pattern adjustment tube (1705), and a third flow pattern adjustment tube (1708) connected in series; the first flow pattern adjustment tube (1702), the second flow pattern adjustment tube (1705), and the third flow pattern adjustment tube (1708) are all integrally formed from an upward-sloping tube, a horizontal tube, and a downward-sloping tube in the same vertical plane; The flow pattern adjustment device (17) further includes a valve group comprising a first valve (1701), a second valve (1703), a third valve (1704), a fourth valve (1706), a fifth valve (1707), a sixth valve (1709), a seventh valve (1710), and an eighth valve (1711); the first valve (1701) is located at the upstream end of the first flow pattern adjustment pipe (1702), the second valve (1703) is located at the downstream end of the first flow pattern adjustment pipe (1702), and the third valve (1704) is located at the downstream end of the second flow pattern adjustment pipe (1702). The fourth valve (1706) is located at the upstream end of the flow pattern regulating pipe (1705), the fifth valve (1707) is located at the upstream end of the third flow pattern regulating pipe (1708), the sixth valve (1709) is located at the downstream end of the third flow pattern regulating pipe (1708), the seventh valve (1710) is located on the pipeline connecting the third valve (1704) and the sixth valve (1709), and the eighth valve (1711) is located on the pipeline connected in parallel with the third flow pattern regulating pipe (1708).

5. A deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to claim 4, characterized in that: The flow pattern adjustment device (17) is a skid-mounted structure, and the flow pattern adjustment device (17) is detachably connected to the mixing pipeline (24) through the upstream valve (16) and the downstream valve (18) of the flow pattern adjustment device.

6. A deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to claim 5, characterized in that: The chemical agent stored in the third agent storage tank (25) is an antifoaming agent. The third agent pump (26) is used to adjust the injection flow rate and injection pressure of the antifoaming agent. The third agent valve (27) is used to control the delivery of the antifoaming agent.

7. A deep-sea mixed-transport pump pipe flow assurance system based on foam flow according to claim 6, characterized in that: The underwater foam mixing and transport system also includes a pressure sensor, which is installed upstream and downstream of the flow pattern adjustment device (17) and electrically connected to the control unit of the flow pattern adjustment device (17) to determine the flow pattern characteristics upstream and downstream of the flow pattern adjustment device (17) and then adjust the working mode of the flow pattern adjustment device (17).

8. A method for ensuring flow in deep-sea mixed-transport pump pipes based on foam flow, characterized in that, The deep-sea mixed-transport pump pipe flow assurance system based on foam flow, as described in claim 7, includes the following steps: S1. Chemical injection scheme design: Based on the composition and flow rate of deep-sea oil and gas products and deep-sea environmental parameters, select surfactants with foaming and hydrate kinetic inhibition functions as foaming agents, and determine the types, concentrations, injection pressures and injection flow rates of foaming agents, defoamers and auxiliary chemicals. S2. Flow pattern adjustment device (17) control: Based on the flow pattern characteristics of the upstream and downstream of the flow pattern adjustment device, determine whether it can automatically transform into foam flow after adding foaming agent; if so, adjust the flow pattern adjustment device (17) to the closed state and open the first bypass valve (15); if not, adjust the flow pattern adjustment device (17) to the open state, close the first bypass valve (15), and determine the working quantity of the first flow pattern adjustment pipe (1702), the second flow pattern adjustment pipe (1705), and the third flow pattern adjustment pipe (1708) in the flow pattern adjustment device (17) according to the enhancement degree required for the flow pattern to be adjusted into foam flow. S3. Mixed pump (22) control: The state of the mixed pump is determined by whether the flow system in the pump pipe system can be transported to the central platform defoaming system by itself. If the flow system in the pump pipe system can be transported to the central platform defoaming system by itself, the mixed pump (22) is adjusted to the closed state and the second bypass valve (20) is opened. If not, the mixed pump (22) is adjusted to the open state and the second bypass valve (20) is closed, and the mixed pump (22) is pressurized.

9. A method for ensuring flow in deep-sea mixed-transport pump pipes based on foam flow according to claim 8, characterized in that: In step S2, the flow pattern adjustment device (17) has three operating modes according to the degree of enhancement required to adjust to foam flow: Operating mode I: Only the first flow-type regulating pipe (1702) is opened, controlling the first valve (1701), the second valve (1703), and the seventh valve (1710) to open, and the third valve (1704), the fourth valve (1706), the fifth valve (1707), the sixth valve (1709), and the eighth valve (1711) to close; Operating Mode II: Open the first flow regulating pipe (1702) and the second flow regulating pipe (1705), and control the first valve (1701), the second valve (1703), the third valve (1704), the fourth valve (1706), and the eighth valve (1711) to open, and the fifth valve (1707), the sixth valve (1709), and the seventh valve (1710) to close; Operating Mode III: Open the first flow regulating pipe (1702), the second flow regulating pipe (1705) and the third flow regulating pipe (1708), and control the first valve (1701), the second valve (1703), the third valve (1704), the fourth valve (1706), the fifth valve (1707) and the sixth valve (1709) to open, and the seventh valve (1710) and the eighth valve (1711) to close; The enhancement of the flow pattern adjustment to foam flow increases progressively from working mode I to working mode II to working mode III.

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