An evaluation device for the foam lubrication drag reduction performance near the wall of high-viscosity oil pipeline transportation

Abstract

The present invention relates to a device for evaluating the lubricating drag reduction performance of near-wall foam in high-viscosity oil pipeline transportation. The device consists of a compressor, a gas storage tank, a ball valve, a globe valve, a check valve, a pressure regulator, a pressure transmitter, a temperature transmitter, a vortex flowmeter, a turbine flowmeter, a filter, a water pump, a high-temperature gear pump, a foam liquid tank, a foam generator, a foam tank, a foam layer generator, a separation tank, a differential pressure transmitter, a gear flowmeter, an oil tank, a high-speed camera, a computer terminal and a data acquisition system. This device can test the lubricating drag reduction performance of the near-wall surface in high-viscosity oil pipeline transportation under the action of low-viscosity foam fluid, and simultaneously monitor the flow pattern characteristics and pressure drop laws of high-viscosity oil-foam flow at different flow rates and foam volumes. Among them, the foam is generated by the foam generator and stored in the foam storage tank. The foam layer generator generates a foam ring to wrap the high-viscosity oil to achieve drag reduction. The high-speed camera can take flow pattern diagrams, and the pressure drop can be measured by the differential pressure transmitter.

Description

Technical Field

[0001] The present invention belongs to the field of research on drag reduction of highly viscous oils, and relates to an evaluation device for the drag reduction performance of near-wall foam lubrication in the pipeline transportation of highly viscous oils. Background Art

[0002] With the continuous development of the economy, the demand for energy is also increasing day by day. Among them, fossil energy plays a decisive role in the development of the global industry and economy. At present, the production of conventional crude oil in the world has approached its peak and is showing a trend of gradual exhaustion. While highly viscous oil resources are rich and have great development potential. However, its special physical and chemical properties, such as high density, high viscosity, low fluidity, and high content of macromolecular asphaltenes and resins, also bring great difficulties and challenges to its exploitation and transportation.

[0003] Conventional methods for reducing the viscosity and drag of highly viscous oils can be divided into two categories. One is based on the viscosity reduction transportation of highly viscous oils, and the other is based on the drag reduction transportation of highly viscous oils. Viscosity reduction transportation generally requires overall treatment of highly viscous oils, and there are generally limitations such as large treatment volume, high energy consumption and operating costs, and a large amount of diluent oil or diluent. While the drag reduction transportation of highly viscous oils hardly changes the physical properties of highly viscous oils and can significantly reduce the pumping energy.

[0004] The transportation of highly viscous oil with a water ring is considered to be one of the most economical, energy-saving and efficient effective means for reducing the drag of viscous oil flow. Microbubbles have a drag reduction effect on the turbulent boundary layer of the water flow wall surface, and the fluidity of foam oil (heavy oil containing a large amount of microbubbles) is also several times higher than that of single-phase highly viscous oil. In addition, bubbles also have an obvious viscosity reduction effect on the foam oil flow. Based on the transportation mechanism of highly viscous oil with a water ring, the microbubble drag reduction theory and the foam oil production increase phenomenon, the present invention considers using a water-based foam ring to replace the water ring for pipeline transportation of highly viscous oil, aiming to fully isolate or lubricate the wall interface and reduce or even eliminate the adhesion of highly viscous oil on the pipe wall.

[0005] At the same time, considering the maximum amount of foam and the adjustable thickness of the foam layer, it is necessary to design a supporting foam generator and foam layer generator. Study the flow pattern characteristics and resistance characteristics of highly viscous oil-foam flow under different foam-to-oil phase flow ratios, foam layer thicknesses and pressures, analyze the effects of foam on the pipe wall and the central oil flow and the drag reduction effect, and explore the formation and control methods of the near-wall foam layer of highly viscous oil pipelines, so as to provide strong support for the research and development of new technologies for the exploitation and transportation of highly viscous oils. Summary of the Invention

[0006] The purpose of the present invention is to provide an evaluation device for the drag reduction performance of near-wall foam lubrication in the pipeline transportation of highly viscous oils, which can monitor the flow pattern characteristics and pressure drop laws of highly viscous oil-foam flow under different flow rates and foam amounts. By transporting highly viscous oil through a foam ring, the resistance in the process of transporting highly viscous oil can be effectively reduced, and the transportation efficiency of highly viscous oil can be improved.

[0007] To achieve the above functions, the technical method of the present invention is as follows:

[0008] An evaluation device for the foam lubrication drag reduction performance near the wall of high-viscosity oil pipelines. The device includes a compressor, a gas storage tank, a ball valve, a globe valve, a check valve, a pressure regulator, a pressure transmitter, a temperature transmitter, a vortex flowmeter, a turbine flowmeter, a filter, a water pump, a high-temperature gear pump, a foam liquid tank, a foam generator, a foam tank, a foam layer generator, a separation tank, a differential pressure transmitter, a gear flowmeter, an oil tank, a high-speed camera, a computer terminal and a data acquisition system.

[0009] Components such as the compressor, ball valve, globe valve, gas storage tank, pressure regulator, and vortex flowmeter constitute the air supply and purging system. The air supply and purging system provides the compressed air required for foam preparation and at the same time provides power when the foam is injected into the test section via the foam tank. Components such as the foam liquid tank, filter, water pump, ball valve, globe valve, pressure regulator, turbine flowmeter, and foam generator constitute the foaming system. The foam prepared by the foaming system is stored in the foam tank.

[0010] The foam generator is a self-made cylindrical sealed container filled with fine wire meshes in a cavity. The upper and lower parts on both sides of the container are respectively connected with inlet and outlet pipelines. The air and foam base liquid mixture enters the interior of the generator from the upper inlet. After the mixture passes through the tiny pores between the fine wire meshes in the cavity, the gas-liquid contact area increases sharply, and finally a large number of fine microfoams are formed and discharged from the lower outlet.

[0011] The foam tank for storing foam is a special cylindrical container with an internal piston. Two ball valves are symmetrically arranged on the left and right of the upper end cover of the foam tank for controlling the inlet and outlet of the foam and flow rate adjustment; a cut-off valve is installed at the center of the lower end cover and connected to the air storage tank. Compressed air pushes the internal piston disc of the storage tank through this valve to inject the foam in the tank into the test pipe section.

[0012] The pipeline test system includes components such as a foam layer generator, a test pipe section, an oil tank, and a high-temperature gear pump. Among them, the foam layer generator is the core component, and the foam ring generator consists of an inner cylinder and an outer cylinder. The inner cylinder serves as the oil flow channel, which from left to right is successively a disc, a boss, and a round pipe. There are grooves engraved on the boss, and a sealing ring is embedded to achieve sealing with the outer cylinder. The rightmost end of the round pipe is cut into a wedge shape. Flange plates are connected to both ends of the outer cylinder to achieve connection with the existing loop device. The inner diameters of the left and right pipe sections are different, and they are connected by a reducing pipe in the middle. There are small holes on the left pipe section as the foam inlet. The foam layer generated by the foam layer generator is mixed with the highly viscous oil and flows into the test pipe section. The pipe material used for the test pipe section is tempered borosilicate sight glass, and the inner wall is rough, which can not only be used to simulate the rough characteristics of the inner wall of the steel pipe during the transportation of highly viscous oil through pipelines, but also facilitate the observation of the flow pattern. Thus, the drag reduction effect of the injection-based foam transportation of highly viscous oil in the pipeline can be observed. Data acquisition mainly includes the testing of compressed air, foam liquid, and oil phase flow rates, the acquisition of the pressure difference in the test section, and the shooting of the pipeline flow pattern, etc. When measuring the drag reduction performance, the oil flow rate and the pressure differences of the single-phase oil flow and the highly viscous oil-foam two-phase flow in the test pipe section are collected in real time through the PCL control cabinet, and a high-speed camera can be used to continuously shoot the flow pattern of the foam-highly viscous oil pipeline flow.

[0013] During use, first turn on the compressor and ball valve A to fill the air storage tank with air to the working pressure, then turn on ball valve B and pressure regulator A. The compressed air is monitored for pressure, temperature, and flow rate through pressure transmitter A, temperature transmitter A, and vortex flowmeter. At the same time, turn on filter A, and the foam liquid in the foam liquid tank is filtered and then passes through the water pump. Turn on ball valve E and pressure regulator D, and the treated foam liquid flows through pressure transmitter B, temperature transmitter B, and turbine flowmeter under the action of the water pump and is mixed with the compressed air in the foam generator, and the prepared foam is stored in the foam tank. For the generation of the foam layer, the prepared foam enters the foam layer generator from the foam inlet, and a foam layer is generated in the annular space. At the same time, turn on ball valve I and ball valve K, and the highly viscous oil is injected into the center of the pipeline through the inner pipe of the foam layer generator. The highly viscous oil is mixed with the foam layer and flows into the test pipe section. At this time, turn on the high-speed camera and differential pressure transmitter, start shooting the flow pattern diagram, and the differential pressure transmitter can measure the pressure drop at both ends of the test pipe section. At a certain flow rate ratio, the foam layer can wrap around the outer part of the core oil flow and be transported together with the highly viscous oil, thereby isolating the highly viscous oil and the pipe wall, making the flow shear almost all concentrated in the annular region foam phase, and thus reducing the transportation friction resistance. Finally, the data acquisition system collects flow parameters such as flow rate and pressure drop to complete the evaluation of the near-wall foam lubrication drag reduction performance of highly viscous oil pipeline transportation.

[0014] The present invention adopts the above technical solutions and has the following characteristics:

[0015] 1. An evaluation method for the near-wall foam lubrication drag reduction performance of highly viscous oil pipeline transportation is established, which is used to study the drag reduction performance of the near-wall of highly viscous oil pipeline transportation under the action of foam. This is of great significance for the research on drag reduction in the production and transportation of highly viscous oil.

[0016] 2. The pipeline simulation system built in the present invention is convenient and flexible to operate. Due to the reasonable pipeline combination of the device, the injection of foam and oil phase can be achieved by switching valves. After injecting foam, the fluidity of high-viscosity oil is significantly improved, thus greatly reducing the energy consumption and transportation cost.

[0017] 3. The design of the foam layer generator is innovatively proposed. The main structure of the foam layer generator is mainly designed by referring to the water ring generator. Compared with the water ring drag reduction transportation method, foam drag reduction can minimize the water injection volume, reduce the liquid flow rate in the pipeline, and reduce the dehydration load at the oil transportation terminal, thus greatly improving the transportation efficiency of heavy oil.

[0018] 4. The low density and appropriate apparent viscosity of the foam contribute to its being dragged by the high-viscosity oil in the center of the pipeline and flowing forward as a whole. Therefore, the foam layer between the oil and the wall can effectively lubricate or isolate the pipe wall and the central oil core. Even if part of the foam in the gathering and transportation pipeline decays and drains under the action of the flow field or temperature, the foam and the drained liquid migrate along the pipe wall to the upper and lower parts of the pipeline respectively under the action of gravity, and the two can still complement each other organically to form a composite isolation layer with foam in the upper part and liquid film in the lower part.

[0019] 5. The device used in the present invention can also measure the flow pattern law and resistance characteristics of high-viscosity oil under different flow velocity ratios and foam amounts, and realize the synchronous study of flow pattern and pressure drop.

[0020] 6. In addition, the device built in the present invention also adopts a digital control and management system, which can realize the real-time monitoring and regulation of the drag reduction process, further improving the accuracy and reliability of drag reduction. This technological leadership and innovation give the device a unique competitive advantage in the field of high-viscosity oil drag reduction. Brief Description of the Drawings

[0021] Figure 1 It is a flow chart of the device for near-wall foam lubrication drag reduction performance of high-viscosity oil pipeline transportation in the present invention;

[0022] Figure 2 It is a three-dimensional view of the foam tank;

[0023] Figure 3 It is a sectional view of the foam tank;

[0024] Figure 4 It is a three-dimensional view of the foam layer generator;

[0025] Figure 5 It is a sectional view of the foam layer generator;

[0026] Figure 6 It is a three-dimensional view of the foam generator;

[0027] Figure 7 It is a sectional view of the foam generator;

[0028] Figure 8 It is a three-dimensional view of the wire mesh disk built into the foam generator.

[0029] Among them: 1. Compressor; 2. Ball valve A; 3. Gas storage tank; 4. Ball valve B; 5. Pressure regulator A; 6. Pressure transmitter A; 7. Temperature transmitter A; 8. Vortex flowmeter; 9. Pressure regulator B; 10. Ball valve C; 11. Globe valve A; 12. Ball valve D; 13. Globe valve B; 14. Pressure regulator C; 15. Turbine flowmeter; 16. Temperature transmitter B; 17. Pressure transmitter B; 18. Pressure regulator D; 19. Ball valve E; 20. Water pump; 21. Filter A; 22. Foam liquid tank; 23. Ball valve F; 24. Foam generator; 25. Ball valve G; 26. Foam tank; 27. Pressure regulator E; 28. Ball valve H; 29. Check valve A; 30. Data acquisition system; 31. Ball valve I; 32. Check valve B; 33. Foam layer generator; 34. Differential pressure transmitter; 35. High-speed camera; 36. Ball valve J; 37. Separation tank; 38. Oil tank; 39. Filter B; 40. High-temperature gear pump; 41. Ball valve K; 42. Pressure regulator F; 43. Pressure transmitter C; 44. Temperature transmitter C; 45. Gear flowmeter; 46. Globe valve C; 47. Pressure regulator D; 48. Ball valve L; 49. Ball valve M; 50. Globe valve D; 51. Piston disc; 52. Flange A; 53. Flange B; 54. Round hole A; 55. Inner cylinder; 56. Outer cylinder; 57. Round hole B; 58. Round hole C; 59. Wire mesh. Specific implementation mode

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] The device of the present invention relates to a device for evaluating the foam lubrication and drag reduction performance near the wall of high-viscosity oil pipeline transportation. The device includes a compressor, a gas storage tank, ball valves, globe valves, check valves, pressure regulators, pressure transmitters, temperature transmitters, vortex flowmeters, turbine flowmeters, filters, water pumps, high-temperature gear pumps, foam liquid tanks, foam generators, foam tanks, foam layer generators, separation tanks, differential pressure transmitters, gear flowmeters, oil tanks, high-speed cameras, computer terminals and data acquisition systems.

[0032] The device process for foam lubrication drag reduction performance near the wall of high-viscosity oil pipelines is shown in Figure (1). Components such as a compressor (1), a gas storage tank (3), and a vortex flowmeter (8) constitute the air supply and purging system. A ball valve A (2) is required to connect between the compressor and the gas storage tank. The foaming system consists of components such as a foam liquid tank (22), a filter A (21), a water pump (20), a turbine flowmeter (15), and a foam generator (24). Foam liquid and air are mixed in the foam generator (22) to generate foam, which is stored in the foam tank (26). A ball valve H (28) and a pressure regulator E (27) are connected between the foam tank and the foam layer generator. The foam layer generator is connected to a check valve A (29) and a check valve B (32) to prevent the backflow of foam and the oil phase. The oil tank (38) is filtered through a filter B (39) and flows into the foam layer generator (33) under the action of a high-temperature gear pump (40). After the foam is injected near the wall of the high-viscosity oil and flows through the test pipe section, it finally flows into the separation tank (37) for separation. The gas storage tank, the foam liquid tank, and the oil tank are all connected to pressure transmitters, temperature transmitters, and flowmeters. A pressure transmitter A (6), a temperature transmitter A (7), a pressure transmitter B (17), a temperature transmitter B (16), a pressure transmitter C (43), a temperature transmitter C (44), a vortex flowmeter (8), a turbine flowmeter (15), a gear flowmeter (45), a differential pressure transmitter (34), and a high-speed camera (35) are all connected to a computer terminal and a data acquisition system (22).

[0033] The foam tank device is shown in Figure (2), and its internal structure is shown in Figure (3). The foam tank is a special cylindrical container with a built-in piston. Ball valves L (48) and M (49) are symmetrically arranged on the left and right of the upper end cover of the foam tank, and a globe valve D (50) is installed at the center of the lower end cover, which is connected to an air storage tank. Compressed air passes through this valve to push the built-in piston disc (51) of the storage tank, injecting the foam in the tank into the test pipe section.

[0034] The foam layer generator is shown in Figure (4), and its internal structure is shown in Figure (5). The foam ring consists of two parts: an inner cylinder (55) and an outer cylinder (56). The inner cylinder (55) serves as the oil flow channel. Flange A (52) and flange B (53) are connected to both ends of the outer cylinder to achieve connection with the existing loop device. The middle is connected through a reducing pipe, and a round hole A (54) is opened on the left pipe section as the foam inlet.

[0035] The foam generator is shown in Figure (6), and its internal structure is shown in Figure (7). The foam generator (24) is a cylindrical closed container filled with wire mesh trays inside, which is used to generate foam. A round hole B (57) is provided in the upper right of the container for air and foam base liquid to enter the generator. After the air and foam base liquid mixture enters the generator, it passes through the built-in wire mesh tray (59), and the gas-liquid contact area increases sharply, and finally a large number of fine micro-foams are formed. The formed foam is discharged from the round hole C (58) at the lower left of the container.

[0036] During use, first turn on the compressor and ball valve A (2) to fill the air storage tank with air to the working pressure, then open ball valve B (4) and pressure regulator A (5). The compressed air is monitored for pressure, temperature and flow through pressure transmitter A (6), temperature transmitter A (7) and vortex flowmeter (8). At the same time, open filter A (21), and the foam liquid in the foam liquid tank (22) is filtered and then passes through the water pump (20). At the same time, open ball valve E (19) and pressure regulator D (18), and the treated foam liquid flows through pressure transmitter B (17), temperature transmitter B (16) and turbine flowmeter (15) and mixes with the compressed air in the foam generator (24). The prepared foam is stored in the foam tank (26). For the generation of the foam layer, the prepared foam enters the foam layer generator (33) from the round hole A (54), and a foam layer is generated in the annular space. At the same time, open ball valve I (31) and ball valve K (41), and the oil phase is injected into the center of the pipeline through the inner pipe (55) of the foam layer generator. The oil phase and the foam layer are mixed and flow into the test section. At this time, turn on the high-speed camera (35) and differential pressure transmitter (34), start taking the flow pattern diagram, and the differential pressure transmitter (34) can measure the pressure drop at both ends of the test section. At a certain flow rate ratio, the foam layer can wrap around the core oil flow and be transported together with the high-viscosity oil, thereby isolating the high-viscosity oil from the pipe wall, making the flow shear almost all concentrated in the annular foam phase, and thus reducing the transportation frictional resistance.

Claims

1. A device for evaluating the foam lubrication drag reduction performance near the wall of high-viscosity oil pipeline transportation, which is used to reduce the flow resistance near the wall during the transportation of high-viscosity oil pipeline, is characterized in that: The device includes a compressor, a gas storage tank, valves, a pressure regulator, a pressure transmitter, a temperature transmitter, a vortex flowmeter, a turbine flowmeter, a filter, a water pump, a foam liquid tank, a foam generator, a foam tank, a foam layer generator, a separation tank, a differential pressure transmitter, a gear flowmeter, an oil tank, a high-speed camera and a data acquisition system; the compressor, the gas storage tank and the vortex flowmeter constitute the air supply and purging system; a ball valve A is required to connect between the compressor and the gas storage tank; the foaming system consists of a foam liquid tank, a filter A, a water pump, a turbine flowmeter and a foam generator; the foam liquid and air are mixed in the foam generator to generate foam, which is stored in the foam tank; a ball valve H and a pressure regulator E are connected between the foam tank and the foam layer generator; the foam layer generator is connected with a check valve A and a check valve B to prevent the backflow of foam and oil phase; the oil tank is filtered through a filter B and transported to the foam layer generator under the action of a high-temperature gear pump; after the high-viscosity oil injects foam near the wall surface and flows to the test section, it finally flows into the separation tank for separation; the gas storage tank, the foam liquid tank and the oil tank are all connected with a pressure transmitter, a temperature transmitter and a flowmeter; the pressure transmitter A, the temperature transmitter A, the pressure transmitter B, the temperature transmitter B, the pressure transmitter C, the temperature transmitter C, the vortex flowmeter, the turbine flowmeter, the gear flowmeter, the differential pressure transmitter and the high-speed camera are all connected to a computer terminal and a data acquisition system.

2. An evaluation method of a high-viscosity oil pipeline near-wall foam lubrication drag reduction performance evaluation device as described in claim 1, characterized in that: During use, first turn on the compressor and ball valve A to fill the gas storage tank with air to the working pressure, then turn on ball valve B and pressure regulator A, and the compressed air is monitored for pressure, temperature and flow through the pressure transmitter A, temperature transmitter A and vortex flowmeter; at the same time, turn on filter A, and the foam liquid in the foam liquid tank is filtered and then passes through the water pump; at the same time, turn on ball valve E and pressure regulator D, and the prepared foam base liquid flows through the pressure transmitter B, temperature transmitter B and turbine flowmeter and mixes with the compressed air in the foam generator, and the prepared foam is stored in the foam tank; for the generation of the foam layer, the prepared foam enters the foam layer generator from circular hole A and generates a foam layer in the annular space; at the same time, turn on ball valve I and ball valve K, and the oil phase is injected into the center of the pipeline through the inner pipe of the foam layer generator; the oil phase and the foam layer are mixed and flow into the test section; at this time, turn on the high-speed camera and the differential pressure transmitter, start shooting the flow pattern diagram, and the differential pressure transmitter measures the pressure drop at both ends of the test section; finally, the data acquisition system collects flow, pressure drop and other flow parameters to complete the evaluation of the lubrication and drag reduction performance of the high-viscosity oil pipeline near the wall surface.

3. The evaluation method according to claim 2, characterized in that: After injecting foam between the high-viscosity oil and the pipe wall, the fluidity of the high-viscosity oil is significantly improved, and the lubrication and drag reduction performance near the wall surface of the high-viscosity oil pipeline is realized; when measuring the pipe flow characteristics of the high-viscosity oil under the action of foam, the high-speed camera constantly shoots and records the flow pattern characteristics in the test section, and the differential pressure transmitter obtains the pressure drop at both ends of the test section.

4. The evaluation method according to claim 2, wherein: Adjust the pressure of the pressure regulator E and the opening of the ball valve H to control the amount of foam flowing out of the foam tank; different amounts of foam enter the foam layer generator to generate foam rings with different thicknesses, thereby realizing the monitoring of the flow pattern and pressure drop of the high-viscosity oil under different foam layer thicknesses.

5. The evaluation method according to claim 2, wherein: Adjust the pressure of the pressure regulator F and the opening degree of the ball valve K to control the flow rate of the highly viscous oil flowing out of the oil tank. The highly viscous oil then flows through the foam layer generator and is mixed with the foam to realize the monitoring of the flow pattern characteristics and pressure drop law of the highly viscous oil-foam flow at different flow rates.

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