Multi-pipe gas-liquid cyclone separation device and method for deepwater oil and gas development

Abstract

According to the multi-pipe gas-liquid cyclone separation device and method for deepwater oil and gas development, efficient separation of gas-liquid two-phase flow in the deepwater environment is achieved through the synergistic effect of multi-pipe rectification, flow division, cyclone and gravity separation. The device adopts a plurality of small-diameter pipelines to replace a large-diameter pressure container, and consists of an inlet rectifying pipe, a plurality of shunting pipes, a plurality of cyclone pipes, a gas-phase outlet pipe, a liquid-phase outlet pipe, a gas-phase gathering pipe and a liquid-phase gathering pipe. An inlet rectifying pipe is arranged in the center of the device, the top of the inlet rectifying pipe is connected with the flow dividing pipes, and the flow dividing pipes are evenly arranged in the circumferential direction and tangentially connected with the rotational flow pipes. And the plurality of rotational flow pipes are symmetrically arranged in pairs and are annularly arranged at equal intervals. The gas-phase outlet pipe at the top of each cyclone pipe is connected to the gas-phase manifold, and the liquid-phase outlet pipe at the bottom of each cyclone pipe is connected to the liquid-phase manifold. The device has the advantages of being high in separation efficiency, high in pressure bearing capacity, compact in structure, easy and convenient to manufacture, convenient to install and maintain and the like, and has wide application prospects in the field of deepwater oil and gas development.

Description

Technical Field

[0001] The invention belongs to the technical field of gas-liquid separation devices, and in particular relates to a multi-tube gas-liquid cyclone separation device and method for deepwater oil and gas development. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the long-term exploitation of onshore oil and gas resources, high-quality reserves have gradually decreased, resulting in a continuous increase in the difficulty and cost of exploitation. In contrast, deepwater and ultra-deepwater areas contain a large amount of untapped oil and gas resources. Of the proven marine oil and gas reserves, about 80% are distributed in waters with a depth of more than 500m, of which ultra-deepwater areas (water depth ≥ 1500m) account for more than 40%. Therefore, the efficient development of deepwater and ultra-deepwater oil and gas resources is of great strategic significance for ensuring a stable supply of oil and gas. However, with the increase in the depth of exploitation, oil and gas production faces many technical challenges. For example, the pipeline tie-back distance from the deepwater wellhead to the platform has increased significantly, resulting in increased wellhead back pressure and difficulty in oil and gas lifting, which in turn affects production efficiency.

[0004] To meet this challenge, subsea gas-liquid separation and pressurized transportation technology has become one of the important means to improve deepwater oil and gas recovery. Through subsea gas-liquid separation and single-phase pressurized transportation, the wellhead back pressure can be effectively reduced, the recovery rate can be improved, and the economic life of the oil field can be extended. In addition, this technology can reduce the occurrence of severe slugging flow, improve the operating stability of the underwater production system, and reduce the risk of hydrate formation and pipeline blockage problems. Therefore, subsea gas-liquid separation and pressurized transportation technology provides an efficient, flexible and economically feasible solution for deepwater oil and gas development.

[0005] At present, deepwater gas-liquid separation technology is mainly based on the two principles of gravity separation and cyclone separation. For example, patent publication number US11713664B2 discloses a submarine separator, which uses the density difference between gas and liquid phases to achieve gas-liquid separation through gravity. In order to meet the separation quality requirements, the separator uses a large-diameter pressure vessel to ensure sufficient residence time; however, in a deepwater environment, the separator needs to withstand extremely high hydrostatic pressure, resulting in a significant increase in the thickness of the container wall, making the manufacturing process complicated, the equipment weight increased, and the transportation and underwater installation costs significantly increased. Patent publication number CN104453838A discloses a caisson-type underwater gas-liquid separator, which consists of an upper gas-liquid cyclone separation module and a lower long-scale caisson. The upper cyclone separation module is used for preliminary separation of gas and liquid phases, while the lower long-scale caisson is used to buffer the plug flow and store the liquid phase; however, the manufacture and underwater installation of the separator are difficult, and the deployment and maintenance costs of the overall system are high, which limits its application in deepwater environments. Therefore, the existing deep-water gas-liquid separation technology still has problems such as thick separator walls, complex manufacturing processes, and high transportation and installation costs. Summary of the invention

[0006] In response to the above problems, the present invention provides a multi-tube gas-liquid cyclone separation device and method for deepwater oil and gas development. Through the synergistic effect of multi-tube rectification, diversion, cyclone and gravity separation, efficient separation of gas-liquid two-phase flow in deepwater environment is achieved. By reducing the pressure-bearing cross-section of the separator, the wall thickness requirement is effectively reduced, and it can withstand higher hydrostatic pressure. The modular structure is adopted to improve the adaptability and transportation flexibility of the separator.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In the first aspect, the present invention provides a multi-tube gas-liquid cyclone separation device for deepwater oil and gas development, comprising: an inlet straightening tube, a plurality of branch tubes, a plurality of cyclone tubes, a gas phase outlet tube, a liquid phase outlet tube, a gas phase manifold and a liquid phase manifold; the plurality of cyclone tubes are arranged uniformly in an annular direction; the inlet straightening tube is arranged between the relatively symmetrical cyclone tubes, the top of the inlet straightening tube is connected to one end of the branch tube, and the other end of the branch tube is tangentially connected to the cyclone tube at a set downward angle, the plurality of branch tubes are uniformly arranged along the circumference of the inlet straightening tube, and each branch tube corresponds to a cyclone tube; the top of the cyclone tube is connected to the gas phase manifold through the gas phase outlet tube, and the bottom of the cyclone tube is connected to the liquid phase manifold through the liquid phase outlet tube.

[0009] Furthermore, the inlet rectifier tube is arranged vertically, the bottom end of the inlet rectifier tube is connected to the inlet horizontal tube through an elbow, and the middle part of the inlet rectifier tube is provided with an expanded diameter section for dissipating the slug flow, making the flow tend to be stable, and improving the subsequent separation efficiency.

[0010] Furthermore, the vortex tube is composed of a hemispherical head, a vortex tube body, a tapered head and a reinforcement ring; the hemispherical head is arranged at the top of the vortex tube body, the tapered head is arranged at the bottom end of the vortex tube, and there are multiple reinforcement rings that are evenly arranged on the outer wall of the vortex tube body, which are used to improve the pressure-bearing capacity of the vortex tube and enhance the structural stability of the device in deep water environment.

[0011] Furthermore, the top of the cyclone tube is connected to the gas phase outlet pipe through a hemispherical head; the bottom of the cyclone tube is connected to the liquid phase outlet pipe through a tapered head.

[0012] Furthermore, the gas phase outlet pipe is located above each of the cyclone tubes and is connected to the hemispherical head at the top of the cyclone tube to collect the separated gas phase.

[0013] Furthermore, the gas phase manifold is located above the gas phase outlet pipes and is used to collect the gas phases discharged from all the gas phase outlet pipes.

[0014] Furthermore, the liquid phase outlet pipe is located below each cyclone tube, connected to the tapered head at the bottom of the cyclone tube, and has a certain downward angle with the horizontal plane to ensure that the separator has self-emptying ability and prevent solid phase deposition such as sand particles.

[0015] Furthermore, the liquid phase manifold is located below the liquid phase outlet pipes and is used to collect the liquid phases discharged from all the liquid phase outlet pipes.

[0016] Furthermore, the separation device also includes a plurality of mounting seats, the number of the mounting seats is the same as the number of reinforcement rings on each of the cyclone tubes, a plurality of mounting holes are opened on the mounting seats, the number of the mounting holes is the same as the number of the cyclone tubes, the diameter of the mounting holes is larger than the diameter of the cyclone tubes and smaller than the outer ring diameter of the reinforcement rings; the edge position of the mounting seat is connected to the skid-mounted frame.

[0017] In a second aspect, the present invention also provides a separation method of a multi-tube gas-liquid cyclone separation device for deepwater oil and gas development, comprising the following steps:

[0018] S1. First, the gas-liquid two-phase enters the inlet rectifier tube, and is rectified in the dissipation section in the expansion section to form a relatively stable fluid. The fluid enters the diverter tube with a certain downward inclination angle, where the gas-liquid two-phase is evenly distributed and forms a relatively stable stratified flow through pre-separation to enter each cyclone tube;

[0019] S2. After rectification and diversion, the gas-liquid two-phase flow enters each cyclone tube tangentially. In the cyclone tube, the gas-liquid two-phase flow generates a cyclone under the action of centrifugal force. Based on the density difference between the gas and liquid phases, the gas phase forms an upward cyclone in the center of the cyclone tube, while the liquid phase forms a downward cyclone along the inner wall of the cyclone tube, achieving a preliminary separation of the gas and liquid phases; under the action of gravity, the droplets in the gas flow settle downward, while the bubbles in the liquid phase float upward, finally completing the efficient separation of the gas and liquid phases;

[0020] S3. The gas phase separated in the cyclone tube flows to the gas phase outlet pipe at the top of the cyclone tube and is collected and discharged through the gas phase manifold; the liquid phase is stored at the bottom of the cyclone tube and enters the liquid phase manifold through the liquid phase outlet pipe to be collected and discharged.

[0021] Compared with the prior art, the present invention has the following advantages and positive effects:

[0022] The present invention uses multiple small-diameter separation tubes to replace traditional large-diameter pressure vessels. By reducing the pressure-bearing section of the separator, the wall thickness requirement is effectively reduced, so that it can withstand higher hydrostatic pressure and is suitable for deep-water high-pressure environments. At the same time, the overall weight of the device is light, the structural stability is high, and it can be manufactured using standard pipelines, thereby reducing manufacturing costs and shortening the manufacturing cycle.

[0023] The present invention dissipates the slug flow through the inlet rectifying tube to make the flow tend to be stable, and uses the diverter tube with a certain downward inclination angle to evenly distribute the gas-liquid two-phase flow, and forms a stratified flow into the cyclone tube through pre-separation. In the cyclone tube, the gas-liquid two-phase is efficiently separated under the combined action of centrifugal force and gravity. Through the synergistic effect of multi-tube rectification, diversion, cyclone and gravity separation, the separation efficiency is effectively improved, and the adaptability to flow fluctuations and slug flow is enhanced.

[0024] The present invention adopts a modular structure, and can optimize the number of cyclone tubes according to parameters such as the inlet gas-liquid flow rate, ensuring efficient separation under different working conditions (such as high gas content, high water content or high viscosity fluid). The modular structure not only improves the flexibility and adaptability of the system, but also facilitates manufacturing, installation and maintenance; the skid-mounted design improves the stability of the device in deepwater environments, and can be assembled with underwater booster pumps and pipes, which is convenient for modular transportation, installation and maintenance. This design reduces the difficulty and cost of underwater operations and meets the development needs of deepwater oil and gas fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding 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 on the present invention.

[0026] Figure 1 It is a schematic diagram of the structure of the separation device of the present invention;

[0027] Figure 2 It is a schematic diagram of a cyclone tube assembly of the present invention;

[0028] Figure 3 This is a schematic diagram of the skid-mounted separation device of the present invention.

[0029] In the figure: 1. Inlet rectifier tube; 11. Expanded diameter section; 2. Diverter tube; 3. Cyclone tube; 31. Hemispherical head; 32. Tapered head; 33. Reinforcement ring; 4. Gas phase outlet pipe; 5. Gas phase manifold; 6. Liquid phase outlet pipe; 7. Liquid phase manifold; 8. Mounting seat; 9. Skid-mounted frame. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0032] Example 1

[0033] This embodiment provides a multi-tube gas-liquid cyclone separation device for deepwater oil and gas development, such as Figure 1-Figure 2 As shown, it includes: an inlet rectifying tube 1, multiple branching tubes 2, multiple cyclone tubes 3, a gas phase outlet tube 4, a liquid phase outlet tube 6, a gas phase manifold 5 and a liquid phase manifold 7; the multiple cyclone tubes 3 are evenly arranged in the circumferential direction, and each cyclone tube 3 is symmetrically arranged to ensure uniform distribution of the fluid; the inlet rectifying tube 1 is arranged between the relatively symmetrical cyclone tubes 3, the top of the inlet rectifying tube 1 is connected to one end of the branching tube 2, and the other end of the branching tube 2 is tangentially connected to the cyclone tube 3 at a set downward angle, and efficient separation is achieved by the combined action of centrifugal force and gravity, the multiple branching tubes 2 are evenly arranged along the circumference of the inlet rectifying tube 1, and each branching tube 2 corresponds to a cyclone tube 3; the top of the cyclone tube 3 is connected to the gas phase manifold 5 through the gas phase outlet tube 4, and the bottom of the cyclone tube 3 is connected to the liquid phase manifold 7 through the liquid phase outlet tube 6. The separation device adopts a modular structure. By adjusting the number of the diversion tube 2, the cyclone tube 3, the gas phase outlet pipe 4 and the liquid phase outlet pipe 6, it can adapt to different gas-liquid flow requirements, significantly improving the adaptability and flexibility of the separator.

[0034] The inlet rectifier tube 1 is arranged vertically, and the bottom end of the inlet rectifier tube 1 is connected to the inlet horizontal tube through an elbow. The middle part of the inlet rectifier tube 1 is provided with an expanded diameter section 11, which is used to dissipate the slug flow, stabilize the flow, and improve the subsequent separation efficiency; the diverter tube 2 is located at the top of the inlet rectifier tube 1, is evenly arranged along the circumference, and is tangentially connected to each of the cyclone tubes 3 at a set downward angle, which is used to evenly distribute the gas-liquid two-phase flow, and form a stratified flow through pre-separation to enter the cyclone tube.

[0035] The swirl tube 3 is composed of a hemispherical head 31, a swirl tube 3 body, a tapered head 32 and a reinforcement ring 33; the hemispherical head 31 is arranged at the top of the swirl tube 3 body, the tapered head 32 is arranged at the bottom of the swirl tube 3, and there are multiple reinforcement rings 33 that are evenly arranged on the outer wall of the swirl tube 3 body, which are used to improve the pressure bearing capacity of the swirl tube and enhance the structural stability of the device in a deep water environment.

[0036] The top of the cyclone tube 3 is connected to the gas phase outlet pipe 4 through a hemispherical head 31 ; the bottom of the cyclone tube 3 is connected to the liquid phase outlet pipe 6 through a tapered head 32 .

[0037] The gas phase outlet pipe 4 is located above each of the cyclone tubes 3 and is connected to the hemispherical head 31 at the top of the cyclone tube 3 to collect the separated gas phase.

[0038] The gas phase manifold 5 is located above the gas phase outlet pipes 4 and is used to collect the gas phases discharged from all the gas phase outlet pipes 4 .

[0039] The liquid phase outlet pipe 6 is located below each cyclone tube 3, connected to the tapered head 32 at the bottom of the cyclone tube 3, and has a certain downward angle with the horizontal plane to ensure that the separator has self-emptying ability and prevent solid phase deposition such as sand particles.

[0040] The liquid phase manifold 7 is located below the liquid phase outlet pipe 6 and is used to collect the liquid phase discharged from all the liquid phase outlet pipes 6 .

[0041] like Figure 3 As shown, it also includes a plurality of mounting seats 8, the number of the mounting seats 8 is the same as the number of the reinforcement rings 33 on each of the cyclone tubes 3, a plurality of mounting holes are opened on the mounting seats 8, the number of the mounting holes is the same as the number of the cyclone tubes 3, the diameter of the mounting holes is larger than the diameter of the cyclone tubes 3 and smaller than the outer diameter of the reinforcement rings 33; the edge position of the mounting seat 8 is connected to the skid-mounted frame 9; the skid-mounted design is adopted to enhance the stability of the device in a deep-water environment, and at the same time facilitate modular transportation, installation and maintenance, thereby reducing the difficulty and cost of underwater operations.

[0042] Example 2

[0043] This embodiment also provides a separation method of a multi-tube gas-liquid cyclone separation device for deepwater oil and gas development, which utilizes the synergistic effects of multi-tube rectification, flow division, cyclone and gravity separation to achieve efficient separation of gas-liquid two-phase flow in a deepwater environment, including the following steps:

[0044] S1. First, the gas-liquid two-phase enters from the inlet rectifier tube 1, and the dissipation section is rectified in the expansion section 11 to form a relatively stable fluid. The fluid enters the diverter tube 2 with a certain downward inclination angle, and the gas-liquid two-phase is evenly distributed in the diverter tube 2, and forms a relatively stable stratified flow through pre-separation to enter each cyclone tube 3;

[0045] S2. The gas-liquid two-phase flow after rectification and diversion enters each cyclone tube 3 tangentially, and the gas-liquid two-phase generates cyclone in the cyclone tube 3 under the action of centrifugal force. Based on the density difference between the gas and liquid phases, the gas phase forms an upward cyclone in the center of the cyclone tube 3, while the liquid phase forms a downward cyclone along the inner wall of the cyclone tube 3, achieving preliminary separation of the gas and liquid phases; under the action of gravity, the droplets in the gas flow settle downward, while the bubbles in the liquid phase float upward, finally completing the efficient separation of the gas and liquid phases;

[0046] S3. The gas phase separated in the cyclone tube 3 flows to the gas phase outlet pipe 4 at the top of the cyclone tube 3 and is collected and discharged through the gas phase manifold 5; the liquid phase is stored at the bottom of the cyclone tube 3 and enters the liquid phase manifold 7 through the liquid phase outlet pipe 6 to be collected and discharged.

[0047] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development, characterized in that: include: An inlet rectifying tube, a plurality of flow dividing tubes, a plurality of swirl tubes, a gas phase outlet tube, a liquid phase outlet tube, a gas phase manifold and a liquid phase manifold; The plurality of cyclone tubes are evenly arranged in an annular direction; The inlet rectifying tube is arranged between the symmetrical cyclone tubes, the top of the inlet rectifying tube is connected to one end of the diverter tube, the other end of the diverter tube is tangentially connected to the cyclone tube at a set downward angle, and multiple diverter tubes are evenly arranged along the circumference of the inlet rectifying tube, and each diverter tube corresponds to a cyclone tube; the top of the cyclone tube is connected to the gas phase manifold through the gas phase outlet pipe, and the bottom of the cyclone tube is connected to the liquid phase manifold through the liquid phase outlet pipe.

2. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 1, characterized in that: The inlet rectifier tube is arranged vertically, the bottom end of the inlet rectifier tube is connected to the inlet horizontal tube through an elbow, and the middle part of the inlet rectifier tube is provided with an expansion section for dissipating the slug flow, making the flow tend to be stable and improving the subsequent separation efficiency.

3. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 1, characterized in that: The vortex tube is composed of a hemispherical head, a vortex tube body, a tapered head and a reinforcement ring; the hemispherical head is arranged at the top of the vortex tube body, the tapered head is arranged at the bottom of the vortex tube, and there are multiple reinforcement rings that are evenly arranged on the outer wall of the vortex tube body, which are used to improve the pressure bearing capacity of the vortex tube and enhance the structural stability of the device in a deep water environment.

4. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 3, characterized in that: The top of the cyclone tube is connected to the gas phase outlet pipe through a hemispherical head; the bottom of the cyclone tube is connected to the liquid phase outlet pipe through a tapered head.

5. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 4, characterized in that: The gas phase outlet pipe is located above each of the cyclone tubes and is connected to the hemispherical head at the top of the cyclone tube to collect the separated gas phase.

6. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 5, characterized in that: The gas phase manifold is located above the gas phase outlet pipes and is used for collecting the gas phases discharged from all the gas phase outlet pipes.

7. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 5, characterized in that: The liquid phase outlet pipe is located below each cyclone tube, connected to the tapered head at the bottom of the cyclone tube, and has a certain downward inclination angle with the horizontal plane to ensure that the separator has self-emptying ability and prevent solid phase deposition such as sand particles.

8. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 7, characterized in that: The liquid phase manifold is located below the liquid phase outlet pipes and is used to collect the liquid phases discharged from all the liquid phase outlet pipes.

9. A multi-tube gas-liquid cyclone separation device for deepwater oil and gas development as claimed in claim 7, characterized in that: The separation device also includes a plurality of mounting seats, the number of the mounting seats is the same as the number of reinforcement rings on each of the cyclone tubes, a plurality of mounting holes are provided on the mounting seats, the number of the mounting holes is the same as the number of the cyclone tubes, the diameter of the mounting holes is larger than the diameter of the cyclone tubes and smaller than the outer ring diameter of the reinforcement rings; the edge position of the mounting seat is connected to the skid-mounted frame.

10. A separation method of a multi-tube gas-liquid cyclone separation device for deepwater oil and gas development according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. First, the gas-liquid two-phase enters the inlet rectifier tube, and is rectified in the dissipation section in the expansion section to form a relatively stable fluid. The fluid enters the diverter tube with a certain downward inclination angle, where the gas-liquid two-phase is evenly distributed and forms a relatively stable stratified flow through pre-separation to enter each cyclone tube; S2. The gas-liquid two-phase flow after rectification and diversion enters each cyclone tube tangentially. In the cyclone tube, the gas-liquid two-phase generates cyclone under the action of centrifugal force. Based on the density difference between the gas-liquid two-phase, the gas phase forms an upward cyclone in the center of the cyclone tube, while the liquid phase forms a downward cyclone along the inner wall of the cyclone tube, thus achieving the preliminary separation of the gas-liquid two-phase. Under the action of gravity, the droplets in the gas flow settle downward, while the bubbles in the liquid phase float upward, finally completing the efficient separation of the gas-liquid two-phase. S3. The gas phase separated in the cyclone flows to the gas phase outlet pipe at the top of the cyclone and is collected and discharged through the gas phase manifold; The liquid phase is stored at the bottom of the cyclone tube and enters the liquid phase manifold through the liquid phase outlet pipe for collection and discharge.

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