A method and system for controlling the switching of operation modes of an underwater dual-pipe gathering and transportation system

Abstract

The invention discloses a method for switching control of an underwater double-pipe gathering and transportation system operation mode, comprising: collecting real-time flow rates of oil, gas and water monitored by multiphase flowmeters on each wellhead pipeline, and collecting the switch states of outlet valves on two submarine pipelines; acquiring the collected flow data of each wellhead pipeline, and calculating the flow rates of each phase of oil, gas and water at the inlet of a manifold; collecting data on the components of a mixed fluid transported by the manifold to a downstream submarine pipeline; acquiring the mixed fluid component data, flow data and the calculation result of the manifold flow rate, and determining a boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system according to submarine pipeline specification data and external ocean current environment data; calculating a gas phase converted flow rate and a liquid phase converted flow rate at the outlet of the manifold according to the calculated flow rates of each phase of oil, gas and water, and judging and controlling whether the underwater double-pipe gathering and transportation system adopts a single-pipe operation mode or a double-pipe operation mode in combination with the boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system.

Description

Technical Field

[0001] The invention relates to an underwater double-pipe gathering and transportation system operation mode switching control method and system, belonging to the technical field of oil and gas field development. Background Art

[0002] The development of my country's offshore oil and gas resources has fully entered the deepwater era. Deepwater oil and gas production has the characteristics of high output, but large fluctuations in output. In order to adapt to the fluctuations in output and the comprehensive investment costs of deepwater oil and gas production, more and more offshore oil and gas field development adopts underwater dual-pipe gathering and transportation systems (such as Figure 1 In actual production, when underwater dual-pipe gathering and transportation is used to transport oil, gas and water, uneven flow distribution and unstable flow often occur. In severe cases, all fluids flow in a certain pipeline, while no fluid flows in the other pipeline. Uneven flow distribution and unstable flow will easily cause the downstream oil, gas and water treatment facilities to overload and cause safety accidents.

[0003] At present, the conventional practice is to balance the pressure distribution along the two pipelines by adjusting the valve openings arranged on the two pipelines, thereby achieving control of the flow stability and uniformity of the underwater dual-pipe gathering and transportation system. However, in the actual offshore oil and gas production process, the output fluctuates frequently, which can easily lead to hysteresis in valve adjustment on the one hand, and severe wear of the valves due to frequent adjustment of the valve opening on the other hand, which cannot meet the actual production needs. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an underwater double-pipe gathering and transportation system operation mode switching control method, which aims to achieve real-time prediction of the flow stability of the underwater double-pipe gathering and transportation system and provide real-time feedback control scheme according to the prediction results.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for controlling the switching of operation modes of an underwater dual-pipe gathering and transportation system, comprising:

[0007] Collect the real-time flow of oil, gas and water monitored by multiphase flowmeters on each wellhead pipeline, and collect the switch status of the outlet valves on the two submarine pipelines;

[0008] Obtain the collected flow data of each wellhead pipeline and calculate the flow of each phase of oil, gas and water at the manifold inlet;

[0009] Collect data on the composition of the mixed fluid transported from the manifold to the downstream submarine pipeline;

[0010] Obtain the mixed fluid component data, flow data and manifold flow calculation results, and determine the boundary curve where unstable flow occurs in the underwater dual-pipe gathering and transportation system based on the submarine pipeline specification data and external ocean current environment data;

[0011] According to the calculated flow rates of oil, gas and water phases, the gas phase converted flow rate and liquid phase converted flow rate at the manifold outlet are calculated. Combined with the boundary curve of unstable flow in the underwater double-pipe gathering and transportation system, it is judged and controlled whether the underwater double-pipe gathering and transportation system adopts single-pipe operation mode or double-pipe operation mode.

[0012] In the underwater double-pipe gathering and transportation system operation mode switching control method, preferably, the step of determining the boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system comprises the following process:

[0013] S100. According to the mixed fluid component data, the density, viscosity, surface tension and specific heat capacity of the mixed fluid in the range of -30 to 120°C and 0.1 MPa to 30 MPa are obtained by interpolation through the fluid physical property data table;

[0014] S200. Determine the calculation range of the unstable flow boundary curve;

[0015] S300. Determine the operating points required for unstable flow boundary curve calculation;

[0016] S400. For each operating point, calculate in turn whether unstable flow occurs in the dual-pipe operation mode, and fit a boundary curve of unstable flow in the underwater dual-pipe gathering and transportation system according to the calculation results of whether unstable flow occurs at each operating point.

[0017] In the underwater dual-pipe gathering and transportation system operation mode switching control method, preferably, in the above step S400, the calculation process of whether unstable flow occurs at a certain operating point is as follows:

[0018] S401. Assuming that the underwater dual-pipe gathering and transportation system adopts a single-pipe operation mode, calculate the pressure drop F (V) generated by the underwater dual-pipe gathering and transportation system when transporting oil, gas and water mixture from the manifold to the platform. SG ,V SL );

[0019] S402. Assuming that the underwater dual-pipe gathering and transportation system adopts dual-pipe operation mode and the oil, gas and water flow rates of the two pipelines are the same, calculate the pressure drop F (V) generated by the underwater dual-pipe gathering and transportation system when transporting the oil, gas and water mixture from the manifold to the platform. SG / 2,V SL / 2);

[0020] S403. Compare F(V SG ,U SL ) and F(V SG / 2,VSL / 2) of size, if F(V SG ,V SL )≤F(V SG / 2,V SL / 2), it means that unstable flow will occur during double-tube operation, otherwise it means that unstable flow will not occur during double-tube operation.

[0021] The underwater dual-pipe gathering and transportation system operation mode switching control method, preferably, in the above step S401, calculates the transmission pressure drop F (V SG ,V SL ) process is:

[0022] ① Calculate the flow rate V of the gas-liquid mixture M :

[0023] V M =V SG +V SL

[0024] Where V SG V is the gas phase converted flow rate; SL is the liquid phase converted flow rate;

[0025] ② Calculate the pressure drop F(V SG ,V SL ):

[0026]

[0027] Where α is the cross-sectional air content; c is the empirical coefficient, which is 16 for laminar flow and 0.046 for turbulent flow; n is the empirical coefficient, which is 1 for laminar flow and 0.2 for turbulent flow; ρ L is the liquid density; L is the pipe length; μ L is the liquid viscosity; D is the inner diameter of the pipe; g is the acceleration of gravity; θ is the inclination angle of the pipe.

[0028] The underwater dual-pipe gathering and transportation system operation mode switching control method, preferably, in the above step S402, calculates the transmission pressure drop F (V SG / 2,V SL / 2) is:

[0029]

[0030] The underwater double-pipe gathering and transportation system operation mode switching control method, preferably, the judgment and control of the underwater double-pipe gathering and transportation system to adopt the single-pipe operation mode or the double-pipe operation mode is specifically: whether the current flow condition occurs unstable flow: when the flow condition is in the unstable flow occurrence area, close one of the submarine pipelines, and the underwater double-pipe gathering and transportation system adopts the single-pipe operation mode; when the flow condition is in the stable flow area, open the two submarine pipelines, and the underwater double-pipe gathering and transportation system adopts the double-pipe operation mode.

[0031] In a second aspect, the present invention provides an underwater dual-pipe gathering and transportation system operation mode switching control system, comprising:

[0032] The production data acquisition module is used to collect the real-time flow of oil, gas and water monitored by the multiphase flowmeters on each wellhead pipeline, and to collect the switch status of the outlet valves on the two submarine pipelines;

[0033] A manifold flow calculation module is used to obtain the flow data of each wellhead pipeline collected by the production data collection module, and calculate the flow of each phase of oil, gas and water at the manifold inlet;

[0034] Fluid physical property acquisition module, used to collect data on the composition of mixed fluids transported from the manifold to the downstream submarine pipeline;

[0035] A flow stability prediction module is used to obtain the mixed fluid component data collected by the fluid physical property collection module, the flow data collected by the production data collection module and the calculation results of the manifold flow calculation module, and determine the boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system based on the submarine pipeline specification data and the external ocean current environment data;

[0036] The valve switch control module is used to calculate the gas phase converted flow rate and the liquid phase converted flow rate at the manifold outlet according to the flow rates of the oil-gas-water phases calculated by the manifold flow calculation module, and judge and control the underwater double-pipe gathering and transportation system to adopt the single-pipe operation mode or the double-pipe operation mode in combination with the boundary curve of unstable flow in the underwater double-pipe gathering and transportation system provided by the flow stability prediction module.

[0037] In a third aspect, the present invention provides a computer storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the underwater dual-pipe gathering and transportation system operation mode switching control method described in the first aspect of the present invention.

[0038] In a fourth aspect, the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the underwater dual-pipe gathering and transportation system operation mode switching control method described in the first aspect of the present invention.

[0039] The present invention adopts the above technical solution, which has the following advantages:

[0040] 1. The present invention can realize the real-time prediction of the flow stability of the underwater double-pipe gathering and transportation system, and provide real-time feedback control scheme according to the prediction results, thus avoiding the problem of lag in valve adjustment.

[0041] 2. The present invention proposes a method for calculating the boundary curve of the stable flow of the underwater double-pipe gathering and transportation system, which solves the problem of quantitative control of the flow instability of the double-pipe gathering and transportation system.

[0042] 3. The present invention proposes a single / dual pipe operation mode switching control principle for an underwater dual-pipe gathering and transportation system, which can ensure the safe and stable operation of the gathering and transportation system and avoid inefficient or overloaded operation of downstream oil and gas processing facilities connected to the two submarine pipeline outlets due to unstable flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations of the present invention, as shown in the figure:

[0044] Figure 1 It is a structural schematic diagram of the underwater double-pipe gathering and transportation system;

[0045] Figure 2 A schematic diagram of an underwater dual-pipe gathering and transportation system operation mode switching control system provided by an embodiment of the present invention;

[0046] Figure 3 It is the boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc., are used to define components, only for the convenience of distinguishing the above components, and unless otherwise stated, the above terms have no special meanings and cannot be understood as indicating or implying relative importance.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The underwater dual-pipe gathering and transportation system operation mode switching control system provided by the present invention includes: a production data acquisition module, which is used to collect the real-time flow of oil, gas and water monitored by the multiphase flowmeter on each wellhead pipeline; a manifold flow calculation module, which is used to obtain the flow data of each wellhead pipeline collected by the production data acquisition module, and calculate the flow of each phase of oil-gas-water at the manifold inlet; a fluid physical property acquisition module, which is used to collect the mixed fluid component data transported by the manifold to the downstream submarine pipeline; a flow stability prediction module, which is used to obtain the mixed fluid component data of the fluid physical property acquisition module, the flow data of the production data acquisition module and the calculation results of the manifold flow calculation module, and determine the boundary curve of unstable flow in the underwater dual-pipe gathering and transportation system according to the submarine pipeline specification data and the external ocean current environment data; a valve switch control module, which is used to judge and control the underwater dual-pipe gathering and transportation system to adopt a single-pipe operation mode or a dual-pipe operation mode. The present invention can realize the real-time prediction of the flow stability of the underwater dual-pipe gathering and transportation system, and provide real-time feedback control scheme according to the prediction results.

[0051] The following is a detailed description of the underwater dual-pipe gathering and transportation system operation mode switching control method and system provided by the embodiments of the present invention in conjunction with the accompanying drawings.

[0052] Embodiment 1:

[0053] like Figure 2 As shown, the underwater dual-pipe gathering and transportation system operation mode switching control system provided in this embodiment includes a production data acquisition module, a manifold flow calculation module, a flow stability prediction module, a fluid physical property acquisition module and a valve switch control module.

[0054] The method for controlling the switching of the operation mode of the underwater dual-pipe gathering and transportation system provided in this embodiment comprises the following steps:

[0055] Step 1: The production data acquisition module collects the real-time flow of oil, gas and water monitored by the multiphase flowmeters on each wellhead pipeline, and collects the data of the outlet valves on the two submarine pipelines (i.e. Figure 1 The switch status of valve #1 and valve #2 in the control panel.

[0056] Step 2: The manifold flow calculation module obtains the flow data of each wellhead pipeline collected by the production data collection module, and calculates (sums the flow of each wellhead pipeline) the flow of each phase of oil-gas-water at the manifold inlet.

[0057] Step 3: The fluid physical property acquisition module collects the mixed fluid component data (including the molar proportion of each phase such as CO2, H2O, H2S, CH4, C2H6, C3H8, etc.) transported from the manifold to the downstream submarine pipeline, and transmits the mixed fluid component data to the flow stability prediction module.

[0058] Step 4: The flow stability prediction module obtains the mixed fluid component data collected by the fluid physical property acquisition module, the flow data collected by the production data acquisition module, and the calculation results of the manifold flow calculation module, and determines the boundary curve of the unstable flow of the dual-pipe gathering and transportation system based on the submarine pipeline specification data and the external ocean current environment data. The specific process includes the following:

[0059] S100. According to the mixed fluid component data, obtain the density, viscosity, surface tension, specific heat capacity and other physical property data of the mixed fluid in the range of -30 to 120°C and 0.1 MPa to 30 MPa through interpolation of the fluid physical property data table;

[0060] S200. Determine the calculation range of the unstable flow boundary curve: the gas phase conversion velocity is 0-30m / s, and the liquid phase conversion velocity is 0-10m / s;

[0061] S300. Determine the operating points required for calculating the unstable flow boundary curve: the gas phase converted velocity and the liquid phase converted velocity are both discrete points of 0.5 m / s, the gas phase converted velocity operating conditions: 0, 0.5, 1, 1.5...29, 29.5, 30 m / s, the liquid phase converted velocity operating conditions: 0, 0.5, 1, 1.5...9, 9.5, 10 m / s; according to the combination of the gas phase converted velocity and the liquid phase converted velocity, 671 operating points can be formed;

[0062] S400. For each operating point, calculate in turn whether unstable flow occurs in the dual-pipe operation mode, and fit the boundary curve of unstable flow in the dual-pipe gathering and transportation system according to the calculation results of whether unstable flow occurs at each operating point (such as Figure 3The calculation process of whether unstable flow occurs at a certain operating point is as follows:

[0063] S401. Assuming that the dual-pipeline gathering and transportation system adopts a single-pipe operation mode (i.e., only one pipeline is in operation), calculate the pressure drop F (V SG ,V SL ):

[0064] ① Calculate the flow rate V of the gas-liquid mixture M :

[0065] V M =V SG +V SL

[0066] Where V SG V is the gas phase converted flow rate; SL is the liquid phase converted flow rate;

[0067] ② Calculate the transmission pressure drop F(V SG ,V SL ):

[0068]

[0069] Where α is the cross-sectional air content; c is the empirical coefficient, which is 16 for laminar flow and 0.046 for turbulent flow; n is the empirical coefficient, which is 1 for laminar flow and 0.2 for turbulent flow; ρ L is the liquid density; L is the pipe length; μ L is the liquid viscosity; D is the inner diameter of the pipe; g is the acceleration of gravity; θ is the inclination angle of the pipe;

[0070] S402. Assuming that the dual-pipe gathering and transportation system adopts dual-pipe operation mode (i.e., two pipelines are operated simultaneously) and the oil, gas and water flow rates of the two pipelines are the same, calculate the pressure drop F (V SG / 2,V SL / 2), the specific calculation formula is as follows:

[0071]

[0072] S403. Compare F(V SG ,U SL ) and F(V SG / 2,V SL / 2) of size, if F(V SG ,V SL )≤F(V SG / 2,V SL / 2), it means that unstable flow will occur during double-tube operation, otherwise it means that unstable flow will not occur during double-tube operation.

[0073] The valve switch control module calculates the gas phase converted flow rate (obtained by dividing the gas phase flow rate by the pipeline cross-sectional area) and the liquid phase converted flow rate (obtained by dividing the sum of the oil-water phase flow rates by the pipeline cross-sectional area) at the manifold outlet according to the flow rates of each phase of oil, gas and water calculated by the manifold flow calculation module. Combined with the boundary curve of unstable flow in the dual-pipe gathering and transportation system provided by the flow stability prediction module, it determines whether unstable flow occurs in the current flow condition: when the flow condition is in the unstable flow occurrence area, the dual-pipe gathering and transportation system is recommended to adopt a single-pipe operation mode, that is, to close one of the submarine pipelines (at this time, the valve switch control module closes the 1# valve of the 1# submarine pipeline and opens the 2# valve of the 2# submarine pipeline); when the flow condition is in the stable flow area, the dual-pipe gathering and transportation system is recommended to adopt a dual-pipe operation mode, that is, both submarine pipelines are operating normally (at this time, the valve switch control module opens the 1# valve of the 1# submarine pipeline and opens the 2# valve of the 2# submarine pipeline at the same time).

[0074] Embodiment 2:

[0075] This embodiment provides a processing device for implementing the underwater dual-pipe gathering and transportation system operation mode switching control method provided in this embodiment 1. The processing device can be a processing device for a client, such as a mobile phone, a laptop computer, a tablet computer, a desktop computer, etc., to execute the underwater dual-pipe gathering and transportation system operation mode switching control method of embodiment 1.

[0076] The processing device includes a processor, a memory, a communication interface and a bus, and the processor, the memory and the communication interface are connected through the bus to complete mutual communication. The memory stores a computer program that can be run on the processor, and the processor executes the underwater double-pipe gathering and transportation system operation mode switching control method provided in this embodiment 1 when running the computer program.

[0077] Preferably, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0078] Preferably, the processor may be a central processing unit (CPU), a digital signal processor (DSP) or other general-purpose processors of various types, which are not limited here.

[0079] Embodiment 3:

[0080] The underwater dual-pipe gathering and transportation system operation mode switching control method of this embodiment 1 can be specifically implemented as a computer program product, which may include a computer-readable storage medium carrying computer-readable program instructions for executing the underwater dual-pipe gathering and transportation system operation mode switching control method described in this embodiment 1.

[0081] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.

[0082] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for switching operation modes of an underwater dual-pipe gathering and transportation system, characterized in that: include: Collect the real-time flow of oil, gas and water monitored by multiphase flowmeters on each wellhead pipeline, and collect the switch status of the outlet valves on the two submarine pipelines; Obtain the collected flow data of each wellhead pipeline and calculate the flow of each phase of oil, gas and water at the manifold inlet; Collect data on the composition of the mixed fluid transported from the manifold to the downstream submarine pipeline; Obtain the mixed fluid component data, flow data and manifold flow calculation results, and determine the boundary curve where unstable flow occurs in the underwater dual-pipe gathering and transportation system based on the submarine pipeline specification data and external ocean current environment data; According to the calculated flow rates of oil, gas and water phases, the gas phase converted flow rate and liquid phase converted flow rate at the manifold outlet are calculated. Combined with the boundary curve of unstable flow in the underwater double-pipe gathering and transportation system, it is judged and controlled whether the underwater double-pipe gathering and transportation system adopts single-pipe operation mode or double-pipe operation mode.

2. The method for switching the operation mode of the underwater dual-pipe gathering and transportation system according to claim 1 is characterized in that: The process of determining the boundary curve where unstable flow occurs in the underwater dual-pipe gathering and transportation system includes the following steps: S100. According to the mixed fluid component data, the density, viscosity, surface tension and specific heat capacity of the mixed fluid in the range of -30 to 120°C and 0.1 MPa to 30 MPa are obtained by interpolation through the fluid physical property data table; S200. Determine the calculation range of the unstable flow boundary curve; S300. Determine the operating points required for unstable flow boundary curve calculation; S400. For each operating point, calculate in turn whether unstable flow occurs in the dual-pipe operation mode, and fit a boundary curve of unstable flow in the underwater dual-pipe gathering and transportation system according to the calculation results of whether unstable flow occurs at each operating point.

3. The method for controlling the switching of the operation modes of the underwater dual-pipe gathering and transportation system according to claim 2 is characterized in that: In the above step S400, the calculation process of whether unstable flow occurs at a certain operating point is as follows: S401. Assuming that the underwater dual-pipe gathering and transportation system adopts a single-pipe operation mode, calculate the pressure drop F (V) generated by the underwater dual-pipe gathering and transportation system when transporting oil, gas and water mixture from the manifold to the platform. SG ,V SL ); S402. Assuming that the underwater dual-pipe gathering and transportation system adopts dual-pipe operation mode and the oil, gas and water flow rates of the two pipelines are the same, calculate the pressure drop F (V) generated by the underwater dual-pipe gathering and transportation system when transporting the oil, gas and water mixture from the manifold to the platform. SG / 2,V SL / 2); S403. Compare F(V SG ,U SL ) and F(V SG / 2,V SL / 2) of size, if F(V SG ,V SL )≤F(V SG / 2,V SL / 2), it means that unstable flow will occur during double-tube operation, otherwise it means that unstable flow will not occur during double-tube operation.

4. The method for controlling the switching of the operation modes of the underwater dual-pipe gathering and transportation system according to claim 3 is characterized in that: In the above step S401, the pressure drop F (V SG ,V SL ) process is: ① Calculate the flow rate V of the gas-liquid mixture M : V M =V SG +V SL Where V SG V is the gas phase converted flow rate; SL is the liquid phase converted flow rate; ② Calculate the pressure drop F(V SG ,V SL ): Where α is the cross-sectional air content; c is the empirical coefficient, which is 16 for laminar flow and 0.046 for turbulent flow; n is the empirical coefficient, which is 1 for laminar flow and 0.2 for turbulent flow; ρ L is the liquid density; L is the pipe length; μ L is the liquid viscosity; D is the inner diameter of the pipe; g is the acceleration of gravity; θ is the inclination angle of the pipe.

5. The underwater dual-pipe gathering and transportation system operation mode switching control method according to claim 4 is characterized in that: In the above step S402, the pressure drop F (V SG / 2,V SL / 2) is:

6. The underwater dual-pipe gathering and transportation system operation mode switching control method according to claim 5 is characterized in that: The judgment and control of whether the underwater double-pipe gathering and transportation system adopts the single-pipe operation mode or the double-pipe operation mode is specifically as follows: whether unstable flow occurs in the current flow condition: when the flow condition is in the unstable flow occurrence area, one of the submarine pipelines is closed, and the underwater double-pipe gathering and transportation system adopts the single-pipe operation mode; when the flow condition is in the stable flow area, the two submarine pipelines are opened, and the underwater double-pipe gathering and transportation system adopts the double-pipe operation mode.

7. An underwater dual-pipe gathering and transportation system operation mode switching control system, characterized in that: include: The production data acquisition module is used to collect the real-time flow of oil, gas and water monitored by the multiphase flowmeters on each wellhead pipeline, and to collect the switch status of the outlet valves on the two submarine pipelines; A manifold flow calculation module is used to obtain the flow data of each wellhead pipeline collected by the production data collection module, and calculate the flow of each phase of oil, gas and water at the manifold inlet; Fluid physical property acquisition module, used to collect data on the composition of mixed fluids transported from the manifold to the downstream submarine pipeline; A flow stability prediction module is used to obtain the mixed fluid component data collected by the fluid physical property collection module, the flow data collected by the production data collection module and the calculation results of the manifold flow calculation module, and determine the boundary curve where unstable flow occurs in the underwater double-pipe gathering and transportation system based on the submarine pipeline specification data and the external ocean current environment data; The valve switch control module is used to calculate the gas phase converted flow rate and the liquid phase converted flow rate at the manifold outlet according to the flow rates of the oil-gas-water phases calculated by the manifold flow calculation module, and judge and control the underwater double-pipe gathering and transportation system to adopt the single-pipe operation mode or the double-pipe operation mode in combination with the boundary curve of unstable flow in the underwater double-pipe gathering and transportation system provided by the flow stability prediction module.

8. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the underwater dual-pipe gathering and transportation system operation mode switching control method described in any one of claims 1-6 are implemented.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the underwater dual-pipe gathering and transportation system operation mode switching control method according to any one of claims 1 to 6 are implemented.

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