Ultra-deepwater gas field development two-stage recovery efficiency optimization method, system, equipment and medium

Abstract

The invention relates to an ultra-deepwater gas field development two-stage recovery efficiency optimization method, system, equipment and medium, and the method comprises the following steps: calculating through a pressure gradient to obtain a pipeline starting point pressure, obtaining a relation among a pipeline transportation amount, the pipeline pressure and a liquid retention amount according to a pipeline transportation amount change, and determining a suggested minimum transportation amount; and designing the underwater production system, and controlling the ultra-deep water underwater production system to adopt different conveying modes to carry out oil and gas conveying in different stages of ultra-deep water gas field development based on the suggested minimum conveying amount so as to improve the recovery efficiency. The method can be widely applied to the field of ultra-deepwater gas field development.

Description

Technical Field

[0001] The present invention relates to a method, system, equipment and medium for optimizing the recovery rate in two stages of ultra-deepwater gas field development, and belongs to the field of ultra-deepwater gas field development. Background Art

[0002] With the continuous growth of global energy demand, the development of ultra-deepwater gas fields has increasingly become an important part of the offshore oil and gas development in China. Due to its special geological and environmental conditions, such as extreme high temperature and high pressure environments, the ultra-deepwater gas field poses higher requirements for extraction technologies. In this context, how to ensure the flow safety during the oil and gas transportation process is the main challenge in the development of ultra-deepwater gas fields. Among them, the slug problem in the pipeline is representative: ① When the pipeline throughput is less than the recommended minimum throughput, the slug causes the logistics in the pipeline to be unable to be discharged normally, which has an adverse impact on production; ② The liquid accumulation in the pipeline is usually treated by pigging, but when the wellhead pressure is insufficient, the pig cannot operate normally. Therefore, slug control during pigging and ensuring a safe throughput are essential links in the development of ultra-deepwater gas fields.

[0003] For ultra-deepwater gas fields with different characteristics, adopting a suitable transportation mode is the key to solving the above problems. As Figure 1 and Figure 2 shown, traditional ultra-deepwater gas fields usually adopt single-pipe or double-pipe transportation modes for oil and gas transportation, but each has its limitations: Although the single-pipe transportation mode has low investment costs and a short construction period, when faced with problems such as ensuring a safe throughput and slug control during pigging, it lacks the flexibility of a double-pipe loop, often resulting in low transportation efficiency.

[0004] The double-pipe transportation mode realizes the logistics transportation by constructing a loop between the support platform and the subsea production manifold. Under normal operating conditions, both pipes are transported from the subsea production manifold to the support platform; when the throughput is less than the recommended minimum throughput, the double-pipe transportation mode can use one pipeline to transport natural gas in the reverse direction, increasing the flow rate of the other pipeline and cleaning the liquid accumulation in this pipeline to promote the efficient flow of oil and gas. In addition, during the pigging process, if the pressure of one pipeline in the double-pipe transportation mode is insufficient, the other pipeline can provide pressure through the compressor on the support platform, and the two pipes form a loop to ensure the smooth operation of the pig. However, as the gas field development advances to deeper and farther waters, the high construction and maintenance costs have become the main bottleneck of the double-pipe transportation. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a method, system, equipment and medium for optimizing the recovery rate in two stages of ultra-deepwater gas field development, which realizes the maximization of cost-benefit during the entire development stage and improves the pipeline transportation efficiency by integrating the advantages of single-pipe and double-pipe transportation modes.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a two-stage recovery optimization method for ultra-deepwater gas field development, comprising the following steps: The starting pressure of the pipeline is obtained by calculating the pressure gradient, and the relationship between the pipeline flow rate, pipeline pressure and liquid retention volume is obtained according to the change of pipeline flow rate, so as to determine the recommended minimum flow rate; The subsea production system is designed and controlled based on the recommended minimum flow rate. Different transportation methods are used to transport oil and gas at different stages of ultra-deepwater gas field development to improve the recovery rate.

[0007] Furthermore, the pipeline starting pressure is obtained by pressure gradient calculation, and the relationship between pipeline flow rate, pipeline pressure and liquid retention volume is obtained according to the change of pipeline flow rate, and the recommended minimum flow rate is determined, including: Determine the energy conservation equation for a gas-liquid two-phase mixture flowing along a pipeline under steady flow; The energy conservation equation is transformed to obtain the pressure gradient calculation formula, and the starting pressure of the pipeline is solved; Based on the starting pressure and pressure drop gradient of the pipeline, the relationship between pipeline flow rate, pressure and liquid retention volume is obtained according to the change of pipeline flow rate, and the recommended minimum flow rate is determined.

[0008] Further, the calculation formula of the pressure drop gradient is:

[0009] In the formula, express The average pressure of the flowing medium in the pipe section, Pa; Indicates the length of the pipe section, m; Indicates the flow rate of gas-liquid mixture, m / s; g represents the acceleration due to gravity, m / s 2 ; Indicates the inner diameter of the pipe, m; It represents the hydraulic friction coefficient of two-phase mixed transportation; Indicates the gas phase density under pipeline conditions, kg / m 3 ; Indicates the gas phase converted velocity, m / s; Indicates the liquid density under pipeline conditions, kg / m 3 ; A Indicates the cross-sectional area of ​​the pipe, m 2 ; Indicates the elevation angle of the pipe section; Indicates the mass flow rate of gas-liquid mixture, kg / s; Indicates the liquid content of the cross section.

[0010] Further, the design of the subsea production system is carried out, and based on the recommended minimum throughput, the subsea production system in ultra-deepwater gas fields is controlled to adopt different transportation methods for oil and gas transportation in different development stages to improve the recovery rate, including: Design the subsea production system in ultra-deepwater to enable it to switch the transportation method according to the development stage of the ultra-deepwater oil and gas field; Determine the development stage of the ultra-deepwater oil and gas field according to the relationship between the current throughput of the pipeline and the recommended minimum throughput, and control the subsea production system in ultra-deepwater to adopt a single-pipe transportation method or a double-pipe transportation method for oil and gas transportation.

[0011] Further, the subsea production system in ultra-deepwater includes: subsea production manifolds, pipeline end manifolds, pipeline end termination devices, lifting pipelines, and supporting platforms; One end of the subsea production manifolds is connected to one end of the pipeline end manifolds through a horizontal section pipeline, and the other end of the pipeline end manifolds is connected to the supporting platform through a riser section pipeline. The subsea production manifolds, pipeline end manifolds, and the supporting platform cooperate to achieve the single-pipe transportation method in the early stage of exploitation; One end of the pipeline end termination device is connected to the pipeline end manifolds, and the other end is connected to the supporting platform through the lifting pipeline. The subsea production manifolds, pipeline end manifolds, pipeline end termination devices, lifting pipelines, and supporting platforms cooperate to achieve the double-pipe transportation method in the later stage of exploitation.

[0012] Further, the determination of the development stage of the ultra-deepwater oil and gas field according to the relationship between the current throughput of the pipeline and the recommended minimum throughput, and the control of the subsea production system in ultra-deepwater to adopt a single-pipe transportation method or a double-pipe transportation method for oil and gas transportation includes: Determine the installation location and installation time of the pipeline end manifolds and the lifting pipeline according to the process constraint conditions and actual production requirements; In different development stages, control the subsea production system in ultra-deepwater to adopt a single-pipe transportation method or a double-pipe transportation method for oil and gas transportation.

[0013] Further, the installation location and installation time of the pipeline end manifolds and the lifting pipeline need to meet the following constraint conditions:

[0014] Among them, represents the volume flow rate of condensate oil, m 3 / d; represents the condensate oil treatment capacity of the platform, m 3 / d; represents the volume flow rate of liquid, m 3 / d; represents the ethylene glycol recovery capacity of the platform, m3 / d; represents the volumetric flow rate of natural gas, m 3 / d; represents the natural gas processing capacity of the platform, m 3 / d; represents the export capacity of the platform compressor, m 3 / d; represents the flow velocity of natural gas, m / s; represents the outlet temperature of the slug catcher, °C; represents the minimum temperature required for the steel, °C.

[0015] In a second aspect, the present invention provides an optimization system for the two-stage recovery rate of ultra-deepwater gas field development, comprising: a recommended minimum throughput determination module, configured to obtain the pipeline starting pressure through pressure gradient calculation, and determine the relationship between the pipeline throughput, pipeline pressure, and liquid holdup according to the change of the pipeline throughput, so as to determine the recommended minimum throughput; a recovery rate optimization module, configured to design the subsea production system, and control the subsea production system in different stages of ultra-deepwater gas field development to adopt different transportation methods for oil and gas transportation based on the recommended minimum throughput, so as to improve the recovery rate.

[0016] In a third aspect, the present invention provides a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions that, when executed by a computing device, cause the computing device to execute any of the methods.

[0017] In a fourth aspect, the present invention provides a computing device, comprising: one or more processors and a memory, wherein the memory stores one or more programs and is configured to be executed by the one or more processors, and the one or more programs include instructions for executing any of the methods.

[0018] Due to the above technical solutions adopted by the present invention, it has the following advantages: The present invention combines the advantages of the single-pipe transportation mode and the double-pipe transportation mode. On the one hand, by using the lifting pipeline as the reverse transportation pipeline for natural gas in the double-pipe transportation, the slug phenomenon in the slope and riser sections can be effectively alleviated, ensuring that the pipeline throughput can always be higher than the recommended minimum throughput, and enabling the system to operate in a highly efficient state. On the other hand, the lifting pipeline is added only in the later stage of the project and the pipeline length is short, saving the project investment cost and improving the economic feasibility of the project.

[0019] Therefore, the present invention can be widely applied to the field of ultra-deepwater gas field development. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Upon reading the following detailed description of the preferred embodiments, various other advantages and benefits will become apparent to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is the existing single-pipe transportation mode; Figure 2 is the existing double-pipe transportation mode; Figure 3 is the flowchart of the two-stage recovery rate optimization method for ultra-deepwater gas field development provided by the embodiment of the present invention; Figure 4 is the correlation between throughput, pressure, and liquid holdup provided by the embodiment of the present invention; Figure 5a and Figure 5b is the deepwater transportation mode of single-pipe transportation + lifting pipeline provided by the embodiment of the present invention, where, Figure 5a is the stage where the throughput is greater than the recommended minimum throughput, Figure 5b is the stage where the throughput is less than the recommended minimum throughput. Detailed Embodiments

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0022] It should be noted that the terms used here are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used here, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] With the continuous expansion of ultra-deepwater gas field development, its development boundary has gradually extended to marginal gas fields, resulting in a significant increase in the physical distance between the gas field and the existing supporting platforms. Based on existing research findings, in the bottom area of the riser, the slugging phenomenon is particularly severe, resulting in a drastic fluctuation in the liquid flow rate at the outlet of the subsea pipeline.

[0024] In view of the challenges faced in the development of ultra-deepwater gas fields, in some embodiments of the present invention, an optimization method for the two-stage recovery factor in the development of ultra-deepwater gas fields is proposed. By configuring a lifting pipeline at a preset position between the horizontal section and the riser section, the development of ultra-deepwater gas fields is divided into two stages. The present invention adopts a transportation strategy that is implemented in stages and combines pipeline transportation efficiency and cost-effectiveness. According to the characteristics of different development stages, appropriate transportation methods are adopted to address problems such as pipeline liquid holdup and slugging, ensuring the safety and efficiency of the oil and gas transportation process.

[0025] Correspondingly, in some other embodiments of the present invention, an optimization system, equipment, and medium for the two-stage recovery factor in the development of ultra-deepwater gas fields are provided.

[0026] Embodiment 1 As Figure 3 shown, the present invention proposes an optimization method for the two-stage recovery factor in the development of ultra-deepwater gas fields, which includes the following steps: 1) Calculate the pipeline starting pressure through the pressure gradient, and obtain the relationship between the pipeline throughput, pipeline pressure, and liquid holdup according to the change in pipeline throughput, and then determine the recommended minimum throughput. 2) Design the subsea production system, and control the subsea production system of ultra-deepwater to adopt a single-pipeline transportation method or a double-pipeline transportation method for oil and gas transportation based on the recommended minimum throughput, so as to improve the recovery factor.

[0027] Further, in the above step 1), the following steps are included: 1.1) Determine the energy conservation equation when the gas-liquid two-phase mixture flows along the pipeline under steady flow.

[0028] Specifically, the energy conservation equation is expressed as: (1) In the formula, represents the average pressure (absolute) of the flowing medium in the pipe section, Pa; represents the density of the gas-liquid mixture; represents the pipe section length, m; represents the gas-liquid mixture flow velocity, m / s; g represents the gravitational acceleration, m / s 2 ; represents the inner diameter of the pipeline, m; represents the two-phase mixed transportation hydraulic friction coefficient.

[0029] 1.2) Transform the energy conservation equation to obtain the pressure gradient calculation formula, and solve the pipeline starting pressure.

[0030] Each item in formula (1) is the pressure energy, kinetic energy, potential energy, and along the pipe length of the unit mass gas-liquid mixtured Energy lost due to friction during flow. Rewriting formula (1) into the form of pressure drop gradient, we have: (2) It can be seen from formula (2) that the total pressure drop gradient of the pipeline can be expressed as the sum of the kinetic energy per unit length of the pipeline, the change in potential energy and the friction loss.

[0031] The calculation formula of the kinetic energy change term is: (3) (4) In the formula, Indicates gas mass flow rate, kg / s; Indicates the gas phase density under pipeline conditions, kg / m 3 ; Indicates the gas phase converted velocity, m / s.

[0032] Substituting equation (4) into equation (2), and considering the true density calculation formula (5) of the gas-liquid mixture, the cross-sectional liquid content is Replacement cross-sectional air content , then the kinetic energy change term can be expressed as: (5) (6) In the formula, Indicates the liquid density under pipeline conditions, kg / m 3 ; A Indicates the cross-sectional area of ​​the pipe, m 2 ; Indicates the change in length.

[0033] The calculation formula for the potential energy change term is: (7) In the formula, Indicates the elevation angle of the pipe section, with upslope being positive and downslope being negative (°).

[0034] According to the fluid density of the gas-liquid mixture , the calculation formula of friction loss term is: (8) In the formula, Indicates the mass flow rate of gas-liquid mixture, kg / s.

[0035] Substituting the expressions (6), (7) and (8) of each loss into (2), the calculation formula of the pressure drop gradient after considering the influence of pipeline fluctuation is obtained as follows: (9) 1.3) Based on the pipeline starting pressure and pressure drop gradient, obtain the relationships among pipeline throughput, pressure, and liquid holdup according to the change in pipeline throughput, and determine the recommended minimum throughput.

[0036] As Figure 4 shown, when the throughput is on the right side of the recommended minimum throughput, both the pipeline liquid holdup and slug volume meet the requirements for safe and stable production. At this time, the single - pipe transportation mode can be adopted. As the development project progresses, the throughput gradually shifts to the left side of the recommended minimum throughput, resulting in an increase in pipeline pressure and liquid holdup, which is not conducive to the normal operation of the pipeline.

[0037] Furthermore, in the above - mentioned step 2), it includes the following steps: 2.1) Design the ultra - deep - water subsea production system so that it can switch the transportation mode according to the development stage of the ultra - deep - water oil and gas field. 2.2) Determine the development stage of the ultra - deep - water oil and gas field according to the relationship between the current pipeline throughput and the recommended minimum throughput, and control the ultra - deep - water subsea production system to adopt the single - pipe transportation mode or the double - pipe transportation mode for oil and gas transportation.

[0038] Furthermore, in the above - mentioned step 2.1), as Figure 5a and Figure 5b shown, it is a schematic diagram of the ultra - deep - water subsea production system proposed by the present invention. The main facilities and equipment of this system include a subsea production manifold, PLEM (Pipeline End Manifold), PLET (Pipeline End Termination), lifting pipelines, and a support platform. Among them, the subsea production manifold is connected to one end of the PLEM through a horizontal pipeline, and the other end of the PLEM is connected to the support platform through a riser pipeline. The cooperation of the support platform, PLEM, and subsea production manifold can achieve the single - pipe transportation mode in the early stage of exploitation; one end of the PLET is connected to the PLEM, and the other end is connected to the support platform through a lifting pipeline. The cooperation of the PLET, PLEM, subsea production manifold, lifting pipelines, and support platform can achieve the double - pipe transportation mode in the later stage of exploitation.

[0039] In this embodiment, the subsea production manifold, as one of the core equipment of the ultra - deep - water subsea production system, has the functions of collecting and distributing fluids, regulating pressure and flow rate, and performing preliminary separation and treatment in some cases. The PLEM is a system composed of branch pipelines for fluid gathering and distribution. The PLET is a connection bridge between the pipeline and subsea production facilities, usually connected to the end of the pipeline, and is interconnected with other subsea production facilities through jumper pipes.

[0040] Furthermore, in the above - mentioned step 2.2), it includes the following steps: 2.2.1) Determine the installation location and installation time of the PLEM and lifting pipelines according to the process constraint conditions and actual production requirements.

[0041] In the stage where the throughput is greater than the recommended minimum throughput, a single - pipe transportation mode is adopted, and a PLEM is installed in advance so as to add lifting pipelines later when needed.

[0042] In the stage where the throughput is less than the recommended minimum throughput, in order to solve the problems of rising pipeline pressure and increasing liquid holdup, in this embodiment, a lifting pipeline is added between the horizontal section and the riser section, and the problems of rising pressure and increasing liquid accumulation are solved through a double - pipe transportation mode. On the premise of meeting the requirements of pipeline transportation technology, the key of the present invention lies in determining the installation position and installation time of the lifting pipeline. This position needs to comprehensively consider various factors, including the pressure distribution of the pipeline, the flow characteristics of the fluid, and the technological requirements of production facilities, etc. When determining the installation position of the lifting pipeline, the position of the lifting pipeline should be able to relieve the slugging phenomenon in the riser section to the greatest extent; the construction and operation of the lifting pipeline should not cause interference or impact on the existing production facilities; the installation position of the lifting pipeline should be convenient for later maintenance and repair.

[0043] Specifically, in this embodiment, the installation position of the lifting pipeline needs to meet the following constraint conditions:

[0044] Among them, represents the volume flow rate of condensate oil, m 3 / d; represents the condensate oil treatment capacity of the platform, m 3 / d; represents the volume flow rate of the liquid, m 3 / d; represents the ethylene glycol recovery capacity of the platform, m 3 / d; represents the volume flow rate of natural gas, m 3 / d; represents the natural gas treatment capacity of the platform, m 3 / d; represents the external transportation capacity of the platform compressor, m 3 / d; represents the flow velocity of natural gas, m / s; represents the outlet temperature of the slug catcher, °C; represents the lowest required temperature of the steel, °C.

[0045] 2.2.2) In different development stages, control the ultra - deep - water subsea production system to adopt single - pipe or double - pipe transportation modes for oil and gas transportation.

[0046] Example 2 Example 1 provided an optimization method for the two-stage recovery factor of ultra-deepwater gas field development. Correspondingly, this example provides an optimization system for the two-stage recovery factor of ultra-deepwater gas field development. The system provided in this example can implement the optimization method for the two-stage recovery factor of ultra-deepwater gas field development in Example 1, and this system can be implemented in a software, hardware, or software-hardware combination manner. For example, the system can include integrated or separate functional modules or functional units to execute the corresponding steps in each method of Example 1. Since the system in this example is basically similar to the method example, the description process in this example is relatively simple, and the relevant parts can refer to the partial description in Example 1. The example of the system provided in this example is only illustrative.

[0047] The optimization system for the two-stage recovery factor of ultra-deepwater gas field development provided in this example includes: A recommended minimum throughput determination module, configured to obtain the pipeline starting pressure through pressure gradient calculation, and determine the relationship between pipeline throughput, pipeline pressure, and liquid holdup according to the change of pipeline throughput, so as to determine the recommended minimum throughput; A recovery factor optimization module, configured to design an underwater production system, and control the ultra-deepwater underwater production system to adopt different transportation methods for oil and gas transportation in different stages of ultra-deepwater gas field development based on the recommended minimum throughput, so as to improve the recovery factor.

[0048] Example 3 This example provides a processing device corresponding to the optimization method for the two-stage recovery factor of ultra-deepwater gas field development provided in Example 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 method in Example 1.

[0049] The processing device includes a processor, a memory, a communication interface, and a bus. The processor, the memory, and the communication interface are connected through the bus to complete mutual communication. A computer program that can run on the processor is stored in the memory, and when the processor runs the computer program, it executes the optimization method for the two-stage recovery factor of ultra-deepwater gas field development provided in Example 1.

[0050] Preferably, the memory can be a high-speed random access memory (RAM: Random Access Memory), and may also include a non-volatile memory, such as at least one disk memory.

[0051] Preferably, the processor can be a general-purpose processor of various types such as a central processing unit (CPU) and a digital signal processor (DSP), which is not limited here.

[0052] Example 4 The optimization method for the two-stage recovery rate of ultra-deepwater gas field development in this Embodiment 1 can be specifically implemented as a computer program product. The computer program product may include a computer-readable storage medium, on which computer-readable program instructions for executing the optimization method for the two-stage recovery rate of ultra-deepwater gas field development described in this Embodiment 1 are uploaded.

[0053] The computer-readable storage medium can be a tangible device that holds and stores instructions used by an instruction execution device. The computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination of the above.

[0054] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for realizing in the process Figure 1 one process or multiple processes and / or blocks Figure 1 a device for the functions specified in one block or multiple blocks. These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device realizes in the process Figure 1 one process or multiple processes and / or blocks Figure 1 a device for the functions specified in one block or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide for realizing in the process Figure 1 one process or multiple processes and / or blocks Figure 1Steps of the functions specified in one or more boxes.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A two-stage recovery optimization method for ultra-deepwater gas field development, characterized in that: The following steps are involved: The starting pressure of the pipeline is obtained by calculating the pressure gradient, and the relationship between the pipeline flow rate, pipeline pressure and liquid retention volume is obtained according to the change of pipeline flow rate, so as to determine the recommended minimum flow rate; The subsea production system is designed and controlled based on the recommended minimum flow rate. Different transportation methods are used to transport oil and gas at different stages of ultra-deepwater gas field development to improve the recovery rate.

2. The two-stage recovery optimization method for ultra-deepwater gas field development according to claim 1, characterized in that: The pipeline starting point pressure is obtained by pressure gradient calculation, and the relationship between pipeline flow rate, pipeline pressure and liquid retention volume is obtained according to the change of pipeline flow rate, and the recommended minimum flow rate is determined, including: Determine the energy conservation equation for a gas-liquid two-phase mixture flowing along a pipeline under steady flow; The energy conservation equation is transformed to obtain the pressure gradient calculation formula, and the starting pressure of the pipeline is solved; Based on the starting pressure and pressure drop gradient of the pipeline, the relationship between pipeline flow rate, pressure and liquid retention volume is obtained according to the change of pipeline flow rate, and the recommended minimum flow rate is determined.

3. The two-stage recovery optimization method for ultra-deepwater gas field development according to claim 2, characterized in that: The calculation formula of the pressure drop gradient is: In the formula, express The average pressure of the flowing medium in the pipe section, Pa; Indicates the length of the pipe section, m; Indicates the flow rate of gas-liquid mixture, m / s; g represents the acceleration due to gravity, m / s 2 ; Indicates the inner diameter of the pipe, m; It represents the hydraulic friction coefficient of two-phase mixed transportation; Indicates the gas phase density under pipeline conditions, kg / m 3 ; Indicates the gas phase converted velocity, m / s; Indicates the liquid density under pipeline conditions, kg / m 3 ; A Indicates the cross-sectional area of ​​the pipe, m 2 ; Indicates the elevation angle of the pipe section; Indicates the mass flow rate of gas-liquid mixture, kg / s; Indicates the liquid content of the cross section.

4. The two-stage recovery optimization method for ultra-deepwater gas field development according to claim 1, characterized in that: The subsea production system is designed and based on the recommended minimum flow rate, the ultra-deepwater subsea production system adopts different transportation methods to transport oil and gas at different stages of ultra-deepwater gas field development to improve the recovery rate, including: Designing the ultra-deepwater underwater production system so that it can switch the transportation mode according to the development stage of the ultra-deepwater oil and gas field; Based on the relationship between the current pipeline output and the recommended minimum output, the development stage of the ultra-deepwater oil and gas field is determined, and the ultra-deepwater underwater production system is controlled to use a single-pipeline or dual-pipeline transportation method for oil and gas transportation.

5. The two-stage recovery optimization method for ultra-deepwater gas field development according to claim 4, characterized in that: The ultra-deepwater underwater production system includes: underwater production manifold, pipeline end manifold, pipeline end termination device, lifting pipeline and supporting platform; The underwater production manifold is connected to one end of the pipeline end manifold through a horizontal section pipeline, and the other end of the pipeline end manifold is connected to the supporting platform through a riser section pipeline. The underwater production manifold, the pipeline end manifold and the supporting platform cooperate to realize a single-pipe transportation method in the early stage of mining; One end of the pipeline end termination device is connected to the pipeline end manifold, and the other end is connected to the supporting platform through the lifting pipeline. The underwater production manifold, pipeline end manifold, pipeline end termination device, lifting pipeline and supporting platform cooperate to realize a dual-pipe transportation method in the later stage of mining.

6. A two-stage recovery optimization method for ultra-deepwater gas field development as claimed in claim 5, characterized in that: The method of determining the development stage of the ultra-deepwater oil and gas field based on the relationship between the current pipeline capacity and the recommended minimum capacity, and controlling the ultra-deepwater underwater production system to use a single-pipeline transportation method or a dual-pipeline transportation method for oil and gas transportation, includes: Determine the installation location and time of the pipeline end manifold and lifting pipeline according to process constraints and actual production needs; At different development stages, the ultra-deepwater underwater production system is controlled to use a single-pipe or dual-pipe transportation method for oil and gas transportation.

7. A two-stage recovery optimization method for ultra-deepwater gas field development as claimed in claim 6, characterized in that: The installation location and time of the pipeline end manifold and lifting pipeline must meet the following constraints: in, Indicates the volume flow rate of condensate oil, m 3 / d; Indicates the condensate processing capacity of the platform, m 3 / d; Indicates the volume flow rate of the liquid, m 3 / d; Indicates the platform glycol recovery capacity, m 3 / d; Indicates the volume flow rate of natural gas, m 3 / d; Indicates the platform's natural gas processing capacity, m 3 / d; Indicates the external transmission capacity of the platform compressor, m 3 / d; Indicates the flow rate of natural gas, m / s; represents the outlet temperature of the slug catcher, °C; Indicates the minimum temperature required for steel, ℃.

8. A two-stage recovery optimization system for ultra-deepwater gas field development, characterized in that: include: The recommended minimum flow rate determination module is used to obtain the starting pressure of the pipeline by pressure gradient calculation, and obtain the relationship between the pipeline flow rate and the pipeline pressure and the amount of liquid stagnation according to the change of pipeline flow rate, so as to determine the recommended minimum flow rate; The recovery factor optimization module is used to design the subsea production system and control the ultra-deepwater subsea production system based on the recommended minimum delivery rate to use different transportation methods to transport oil and gas at different stages of ultra-deepwater gas field development to improve the recovery factor.

9. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform any one of the methods of claims 1 to 7.

10. A computing device, characterized in that: include: One or more processors and a memory, wherein the memory stores one or more programs and is configured to be executed by the one or more processors, wherein the one or more programs include instructions for executing any one of the methods described in claims 1 to 7.

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