System and method for researching pipeline hydrate solid-phase blockage removal process

Abstract

The invention relates to the field of safety guarantee of deepwater oil and gas transportation and flow, and discloses a system and a method for researching a pipeline hydrate solid-phase blockage removal process. The system is characterized in that a first back pressure valve, a first inhibitor pump and a first inhibitor valve are mounted at the upper end of a first pressure-resistant pipeline, and a second liquid discharge valve is mounted at the lower end of the first pressure-resistant pipeline; temperature and pressure sensor groups are uniformly arranged on the first pressure-resistant pipeline, the second pressure-resistant pipeline and the third pressure-resistant pipeline; a terahertz wave generation device is arranged on the terahertz wave detection device; the outer side of the visible pipe section is sleeved with a square transparent water tank, and an image acquisition system is arranged outside the square transparent water tank; a second back pressure valve, a second inhibitor pump and a second inhibitor valve are mounted at the upper end of the third pressure-resistant pipeline; a vacuum pump, a water injection tank, a gas injection valve connected with the gas cylinder, a vacuum valve and a water injection valve are mounted at the upper end of the second pressure-resistant pipeline, a first drain valve and a first safety valve are mounted at the lower end of the second pressure-resistant pipeline, and sponge, a sieve plate and an electric telescopic rod are mounted inside the second pressure-resistant pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of deepwater oil and gas transportation flow safety assurance, and in particular to a system and method for studying the solid-phase blockage and unblocking process of pipeline hydrates, and is particularly suitable for simulating the blockage and unblocking process of submarine pipeline hydrates and evaluating the effects of different unblocking technologies. Background Art

[0002] With the continuous growth of global energy demand, the development and utilization of submarine oil and gas resources have received more and more attention. As an important channel connecting submarine oil and gas fields with land or offshore processing facilities, the safe and stable operation of submarine pipelines is crucial to energy supply. However, the hydrate blockage problem of submarine pipelines during operation has become a research hotspot and difficulty in the current marine engineering field.

[0003] Natural gas hydrate is an ice-like substance formed under low temperature and high pressure conditions, and its main components are methane and water. In submarine pipelines, due to the low temperature and high pressure environment, the conditions for hydrate formation are met, and natural gas and water may form hydrates, causing pipeline blockage. This blockage not only affects the normal transportation of oil and gas, but may also cause safety accidents and cause huge economic losses. In engineering applications, the unblocking technology for hydrate blockage is also constantly developing. At present, there are a variety of unblocking technologies for hydrate blockage problems, including chemical injection (such as injection of thermodynamic inhibitors such as methanol and ethylene glycol), heat treatment (including electric heating), pipeline pressure reduction and other methods. These methods can solve the hydrate blockage problem to a certain extent, but due to the complexity of the submarine environment and the difficulty in locating the blockage, the analysis of the unblocking process is relatively difficult. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a system and method for studying the process of solid-phase blockage and unblocking of pipeline hydrates, which can simulate the blockage and unblocking process of submarine pipeline hydrates and evaluate the effects of different unblocking technologies.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a system for studying the process of solid phase blockage and unblocking of pipeline hydrate, comprising: a first pressure-resistant pipeline, an ERT resistance imaging device, a terahertz wave detection device, a visible pipe section, a third pressure-resistant pipeline, a separation valve, and a second pressure-resistant pipeline, wherein the two components are connected in sequence by flanges to form a pressure-resistant experimental pipeline;

[0006] A first back pressure valve and a first inhibitor pump are installed in parallel at the upper end of the first pressure-resistant pipeline, and a first inhibitor valve is arranged between the first inhibitor pump and the first pressure-resistant pipeline; a second liquid discharge valve is installed at the lower end of the first pressure-resistant pipeline, and a temperature and pressure sensor group is evenly arranged on the pipeline between the first pressure-resistant pipeline and the third pressure-resistant pipeline;

[0007] The terahertz wave detection device is equipped with a terahertz wave generating device;

[0008] A square transparent water tank is provided outside the visible pipe section, and an image acquisition system is provided outside the square transparent water tank;

[0009] A second back pressure valve and a second inhibitor pump are installed in parallel at the upper end of the third pressure-resistant pipeline, and a second inhibitor valve is arranged between the second inhibitor pump and the third pressure-resistant pipeline; a second safety valve is installed at the lower end of the third pressure-resistant pipeline;

[0010] A vacuum pump, a water injection tank and an air injection valve are installed in parallel at the upper end of the second pressure-resistant pipe, a vacuum valve is arranged between the vacuum pump and the second pressure-resistant pipe, and a water injection valve is arranged between the water injection tank and the second pressure-resistant pipe; a first liquid discharge valve and a first safety valve are installed in parallel at the lower end of the second pressure-resistant pipe, and a sponge, a sieve plate and an electric telescopic rod are installed inside the second pressure-resistant pipe; the air injection valve is connected to the gas cylinder.

[0011] Furthermore, all safety valves and drain valves are connected to the waste liquid pool through a waste liquid recovery pipeline, and the waste liquid pool is connected to a waste gas valve and a waste gas bottle.

[0012] Further, the outer sides of the first pressure-resistant pipe, the third pressure-resistant pipe, and the second pressure-resistant pipe are respectively covered with a third water bath jacket, a second water bath jacket, and a first water bath jacket;

[0013] The third water bath jacket is connected to the square transparent water tank through the third jacket connecting pipe, and the third water bath jacket and the first water bath jacket are connected to the chiller through a cold water loop; the square transparent water tank is connected to the second water bath jacket through the second jacket connecting pipe, and the second water bath jacket is connected to the first water bath jacket through the first jacket connecting pipe.

[0014] Furthermore, the temperature and pressure sensor group, the ERT resistance imaging device and the terahertz wave detection device are all connected to the computer through a data acquisition system.

[0015] Furthermore, the pressure resistance of the pressure test pipeline is 0-8MPa, and the adjustable temperature range of the chiller 14 is -10°C-20°C.

[0016] Furthermore, the side of the separation valve where the inhibitor pump is installed is the detection pipe section, and the other side of the separation valve is the generation pipe section;

[0017] The sponge, sieve plate and electric telescopic rod form a scraper device to push the hydrates scattered in the tube into the detection tube section to form a hydrate solid phase section; the sieve plate is sealed with the tube wall by a rubber ring, tightly adhered to the sponge, and connected to the electric telescopic rod by threads. The sieve plate is densely covered with small holes to achieve material flow on both sides.

[0018] Furthermore, when the amount of hydrate generated in the pipe is greater than the set amount, the electric telescopic rod is turned on and extended, and the hydrate in the pipe section cannot pass through the sponge and continues to move forward with the sieve plate. The gas and water are separated through the sponge and the sieve plate into the pipe section behind the sieve plate, thereby achieving compression of the hydrate solids in the pipeline;

[0019] When the screen plate moves to the other side wall or contacts the incompressible hydrate solid, the electric telescopic rod contracts, and the gas and liquid behind the screen plate return to the generation pipe section to continue to participate in hydrate generation.

[0020] Furthermore, the water injection tank injects a fixed amount of liquid into the pipeline through a water injection valve, and the liquid is deionized water.

[0021] Furthermore, the gas cylinder injects a fixed amount of gas into the pipeline through the gas injection valve, and the gas is natural gas, methane gas, CO2 or H2.

[0022] A method for studying the process of solid-phase blockage and unblocking of pipeline hydrates is implemented based on the system for studying the process of solid-phase blockage and unblocking of pipeline hydrates, and comprises: using deionized water to fully clean the inside of the pipeline, then opening the vacuum valve and the vacuum pump, evacuating the pipe section of the second pressure-resistant pipeline to a vacuum state, and extracting the air inside the system; keeping the separation gate in an open state, the electric telescopic rod in the shortest position, adding deionized water to the water injection tank, opening the water injection valve, and quantitatively injecting deionized water into the pipeline by using the negative pressure in the pipeline; closing the water injection valve, opening the gas injection valve, injecting natural gas into the pipeline through a gas cylinder, and collecting the pressure in the pipeline through a temperature and pressure sensor group; turning on the chiller, adjusting the temperature to the experimental set temperature, keeping the pipeline temperature stable, and continuously replenishing gas into the pipeline through the gas injection valve to make the inside of the pipeline The pressure is maintained at the set experimental pressure to allow hydrates to form; the ERT resistance imaging device, the terahertz wave generating device, the terahertz wave detecting device and the image acquisition system are turned on; the ERT resistance imaging device is used to radially measure the gas-liquid-solid interface morphology during the hydrate decomposition process; the terahertz wave detecting device is used to observe the amount of decomposed water on the surface of the hydrate block in real time to determine the decomposition rate during the decomposition process of the hydrate block surface; the data is collected to a computer through a data acquisition system for subsequent analysis, and different operations are performed according to the different unblocking methods tested; after the experiment, the separation gate is opened, the set temperature of the chiller is adjusted, the pipeline temperature is increased to decompose the hydrate, the first drain valve and the second drain valve are opened, the liquid and gas in the pipeline are discharged into the waste liquid pool, the waste gas valve and the waste gas pump are opened, and the waste gas above the waste liquid pool is filled into the waste gas bottle for storage.

[0023] The present invention adopts the above technical solution, which has the following advantages:

[0024] The present invention can simulate the unblocking study of submarine pipelines after hydrate blockage, and for different hydrate unblocking technologies, such as chemical injection, heat treatment, pipeline depressurization, etc., combine temperature and pressure sensors, ERT resistance imaging devices 5, terahertz wave detection devices 6, etc. to realize the monitoring of the hydrate unblocking process and the evaluation of the unblocking method; compared with the problem that the traditional unblocking technology evaluation method is not accurate enough and it is difficult to evaluate the actual effects of different unblocking technologies, the present invention has the advantages of high measurement accuracy, wide application of hydrate types, visualization, and multiple types of unblocking technologies that can be evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the overall structure of a system for studying the process of removing solid-phase blockage of pipeline hydrates in an embodiment of the present invention;

[0026] Reference numerals:

[0027] 1. First back pressure valve; 2. First inhibitor pump; 3. First inhibitor valve; 4. First pressure-resistant pipeline; 5. ERT resistance imaging device; 6. Terahertz wave detection device; 7. Terahertz wave generating device; 8. Data acquisition system; 9. Image acquisition system; 10. Computer; 11. Second inhibitor pump; 12. Second inhibitor valve; 13. Second back pressure valve; 14. Chiller; 15. Separation valve; 16. Chiller loop; 17. Vacuum valve; 18. Vacuum pump; 19. Water injection valve; 20. Water injection tank; 21. Gas injection valve; 22. Sponge; 23. Sieve plate; 24. Electric telescopic rod; 25. Gas cylinder; 26. First liquid discharge valve; 27. Waste liquid pool; 28. Waste gas pump; 29. ​​Waste gas valve; 30. Waste gas bottle; 31. First safety valve; 32. Second pressure-resistant pipeline; 33. First water bath jacket; 34. Waste liquid recovery pipeline; 35. First jacket connecting pipe; 36. First flange; 37. Second flange; 38. Second safety valve; 39. Third pressure-resistant pipeline; 40. Second water bath jacket; 41. Third flange; 42. Second jacket connecting pipe; 43. Square transparent water tank; 44. Visible pipe section; 45. Third jacket connecting pipe; 46. Fourth flange; 47. Fifth flange; 48. Sixth flange; 49. Third water bath jacket; 50. Second drain valve; 51. Temperature and pressure sensor group. DETAILED DESCRIPTION

[0028] In order to solve the problem that most existing unblocking technologies lack accurate experimental data support and it is difficult to evaluate the actual effects of different unblocking technologies, the present invention provides a system and method for studying the unblocking process of pipeline hydrate solid phase blockage. The present invention aims to provide an effective experimental system and method by simulating the hydrate blockage and unblocking process of submarine pipelines, and provide a scientific basis for the research and development of hydrate unblocking technology. The present invention can use measuring devices such as ERT resistance imaging device 5 and terahertz wave detection device 6, can simulate the actual blockage situation and monitor the unblocking process in real time, and realize hydrate decomposition monitoring under different unblocking schemes (inhibitor, pressure reduction, temperature increase), including decomposition morphology, decomposition time, inhibitor unblocking effect, which is of great significance for optimizing unblocking schemes and improving unblocking efficiency.

[0029] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, 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 "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] Embodiment 1: In this embodiment of the present invention, a system for studying the process of removing the solid phase blockage of pipeline hydrate is provided. Figure 1 As shown, the system includes: a first pressure-resistant pipeline 4, an ERT resistance imaging device 5, a terahertz wave detection device 6, a visible pipe section 44, a third pressure-resistant pipeline 39, a separation valve 15 and a second pressure-resistant pipeline 32.

[0032] The first pressure-resistant pipeline 4, the ERT resistance imaging device 5, the terahertz wave detection device 6, the visible pipe section 44, the third pressure-resistant pipeline 39, the separation valve 15 and the second pressure-resistant pipeline 32 are connected in sequence through the first flange 36, the second flange 37, the third flange 41, the fourth flange 46, the fifth flange 47 and the sixth flange 48 to form a pressure-resistant test pipeline.

[0033] A first back-pressure valve 1 and a first inhibitor pump 2 are installed in parallel at the upper end of the first pressure-resistant pipe 4, and a first inhibitor valve 3 is arranged between the first inhibitor pump 2 and the first pressure-resistant pipe 4; a second drain valve 50 is installed at the lower end of the first pressure-resistant pipe 4, and a temperature and pressure sensor group 51 is evenly arranged on the pipe between the first pressure-resistant pipe 4 and the third pressure-resistant pipe 39.

[0034] The terahertz wave detection device 6 is provided with a terahertz wave generation device 7 .

[0035] A square transparent water tank 43 is sleeved on the outside of the visible tube section 44 , and an image acquisition system 9 is arranged outside the square transparent water tank 43 .

[0036] A second back pressure valve 13 and a second inhibitor pump 11 are installed in parallel at the upper end of the third pressure-resistant pipe 39 , and a second inhibitor valve 12 is provided between the second inhibitor pump 11 and the third pressure-resistant pipe 39 ; a second safety valve 38 is installed at the lower end of the third pressure-resistant pipe 39 .

[0037] A vacuum pump 18, a water injection tank 20 and a gas injection valve 21 are installed in parallel at the upper end of the second pressure-resistant pipe 32, a vacuum valve 17 is installed between the vacuum pump 18 and the second pressure-resistant pipe 32, and a water injection valve 19 is installed between the water injection tank 20 and the second pressure-resistant pipe 32; a first liquid discharge valve 26 and a first safety valve 31 are installed in parallel at the lower end of the second pressure-resistant pipe 32, and a sponge 22, a sieve plate 23 and an electric telescopic rod 24 are installed inside the second pressure-resistant pipe 32. The gas injection valve 21 is connected to the gas cylinder 25.

[0038] In the above embodiment, all safety valves and drain valves are connected to the waste liquid pool 27 via the waste liquid recovery pipeline 34 , and the waste liquid pool 27 is connected to the waste gas valve 29 and the waste gas bottle 30 .

[0039] In the above embodiment, the outer sides of the first pressure-resistant pipe 4 , the third pressure-resistant pipe 39 , and the second pressure-resistant pipe 32 are respectively covered with the third water bath jacket 49 , the second water bath jacket 40 , and the first water bath jacket 33 .

[0040] Among them, the third water bath jacket 49 is connected to the square transparent water tank 43 through the third jacket connecting pipe 45, and the third water bath jacket 49 and the first water bath jacket 33 are connected to the chiller 14 through the cold water loop 16; the square transparent water tank 43 is connected to the second water bath jacket 40 through the second jacket connecting pipe 42, and the second water bath jacket 40 is connected to the first water bath jacket 33 through the first jacket connecting pipe 35.

[0041] In the above embodiment, the temperature and pressure sensor group 51 , the ERT resistance imaging device 5 and the terahertz wave detection device 6 are all connected to the computer 10 via the data acquisition system 8 .

[0042] In the above embodiment, the pressure resistance of the pressure test pipeline is 0-8MPa, which meets the different pressure requirements of the actual submarine natural gas pipeline, and the flange connection is sealed with a rubber sealing ring. The adjustable temperature range of the chiller 14 is -10℃-20℃, and it is connected to the water bath jacket through the cold water loop 16 to achieve temperature control in the pipeline and meet the temperature conditions for hydrate formation.

[0043] In the above embodiment, the water injection tank 20 injects a fixed amount of liquid, preferably deionized water, into the pipeline through the water injection valve 19. If it is necessary to study the effects of different liquids on the formation and decomposition of hydrates, liquids such as mineral oil and asphalt can also be injected therein.

[0044] In the above embodiment, the gas cylinder 25 injects a fixed amount of gas into the pipeline through the gas injection valve 21, preferably natural gas or methane gas, and can also inject gases such as CO2 and H2 to study the formation and decomposition laws of other types of gas hydrates. The specific injection amount is determined according to the amount of injected water and the pressure environment required for the experiment, and is determined by the readings of the temperature and pressure sensor group 51 in the pipeline.

[0045] In the above embodiment, the separation valve 15 is used as the boundary in the pipeline, and the side where the inhibitor pump is installed is the detection pipe section, and the other side is the generation pipe section. Hydrates can be generated in both the detection pipe section and the generation pipe section, but the tests related to hydrate decomposition are all performed in the detection pipe section. The scraper device composed of the sponge 22, the sieve plate 23 and the electric telescopic rod 24 is used to push the hydrates generated in the pipe into the detection pipe section to form a hydrate solid phase section. The sieve plate 23 is sealed with the pipe wall by a rubber ring, tightly adhered to the sponge 22, and connected to the electric telescopic rod 24 by threads. The sieve plate 23 is densely covered with small holes to realize the flow of materials on both sides. When the amount of hydrate generated in the pipe is greater than the set amount, the electric telescopic rod 24 is turned on, the electric telescopic rod 24 is extended, and the hydrates in the pipe section cannot pass through the sponge 22. It continues to move forward with the sieve plate 23, and the gas and water are separated through the sponge 22 and the sieve plate 23 to the pipe section behind the sieve plate 23, so as to realize the compression of the hydrate solid in the pipeline. When the sieve plate 23 moves to the other side wall or contacts the incompressible hydrate solid, the electric telescopic rod 24 contracts, and the gas and liquid behind the sieve plate 23 return to the generation pipe section to continue to participate in hydrate generation. This process can be repeated many times until the hydrate solid fills or nearly fills the detection pipe section, and then the separation gate is closed to make the detection pipe section independent for subsequent liquid injection, heating and other operations.

[0046] In the above embodiments, the inhibitor pump can quantitatively inject the inhibitor into the pipeline through the inhibitor valve to explore the effect of hydrate inhibitors (such as methanol, ethylene glycol, imidazole, PVP, PVCap, etc.) on the hydrate deblocking process.

[0047] In the above embodiment, the ERT resistance imaging device 5 can radially measure the morphology of the hydrate decomposition process and observe the morphology of the gas-liquid-solid interface in the radial section of the pipeline.

[0048] In this embodiment, the visible pipe section 44 is preferably made of polymethyl methacrylate or other pressure-resistant materials, and can be used as an auxiliary observation method for the ERT resistance imaging device 5, and can also be used as a method for intuitively observing hydrate decomposition to facilitate the derivation of qualitative conclusions; in view of the optical distortion caused by the circular pipe during the image shooting process, a square transparent water tank 43 is provided on the outer sleeve of the pipe to avoid interface bending and achieve high-quality visual image observation.

[0049] In the above embodiment, the terahertz wave detection device 6 is equipped with a terahertz wave generating device 7. By utilizing the characteristic that terahertz waves are easily absorbed by water, terahertz waves are emitted to the hydrate blocks in the pipeline. Only the terahertz waves emitted to the hydrate surface are reflected, and the intensity of the terahertz waves reflected normally from the hydrate block surface is collected. The amount of decomposed water on the hydrate block surface is observed in real time, and the decomposition rate during the decomposition process of the hydrate block surface is determined.

[0050] In the above embodiment, the first drain valve 26 is used to discharge the liquid and gas in the pipeline after the experiment is completed (if there is solid, the temperature is increased to decompose it), and the second drain valve 50 is used to control the pressure in the pipe when the detection pipe section decomposes. The gas and liquid generated during the decomposition process are discharged through the valve so that the pressure in the pipe section reaches the required requirements of the experiment. The first safety valve 31 and the second safety valve 38 are both protection devices. If the pressure in the pipeline reaches the set pressure of the safety valve, the safety valve opens to discharge the gas and liquid in the pipeline to avoid damage to the equipment caused by excessive pressure in the pipeline. The drain valve and the safety valve are both connected to the waste liquid pool 27 through the waste liquid recovery pipeline 34. The gas above the waste liquid pool 27 is filled into the waste gas bottle 30 through the waste gas pump 28 and the waste gas valve 29 to realize the collection and recovery of waste gas and waste liquid.

[0051] Embodiment 2. In engineering applications, the technology for removing hydrate blockages is also constantly developing. At present, there are a variety of removal technologies for hydrate blockages, including chemical injection, heat treatment, pipeline depressurization and other methods. These methods can solve the hydrate blockage problem to a certain extent, but since most of the existing removal technologies lack accurate experimental data support, it is difficult to evaluate the actual effects of different removal technologies. Therefore, in this embodiment of the present invention, a method for studying the process of removing blockages caused by solid-phase hydrate blockages in pipelines is provided. The method is based on the system implementation for studying the process of removing blockages caused by solid-phase hydrate blockages in pipelines in the above-mentioned embodiments. Specifically, this embodiment describes the present invention by simulating the blockage of hydrates in submarine pipelines and their removal process to achieve hydrate decomposition monitoring under different removal schemes (inhibitors, pressure reduction, and temperature increase). The method includes the following steps:

[0052] 1) Use deionized water to thoroughly clean the inside of the pipeline, then open the vacuum valve 17 and the vacuum pump 18, evacuate the pipe section of the second pressure-resistant pipeline 32 to a vacuum state, extract the air inside the system, and eliminate the interference of impurities.

[0053] 2) Keep the separation gate open, the electric telescopic rod 24 in the shortest position, add deionized water to the water injection tank 20, open the water injection valve 19, and use the negative pressure in the pipeline to quantitatively inject deionized water into the pipeline. The specific amount of water injection is determined by the needs of the current group of experiments. Close the water injection valve 19, open the gas injection valve 21, inject natural gas into the pipeline through the gas cylinder 25, collect the pressure in the pipeline through the temperature and pressure sensor group 51, and inject gas until the pressure in the pipeline reaches the experimental set pressure.

[0054] 3) Turn on the chiller 14, adjust the temperature to the experimental set temperature, keep the pipeline temperature stable, and continue to add gas to the pipeline through the gas injection valve 21 to maintain the pressure in the pipeline at the experimental set pressure to generate hydrates. When the amount of hydrate generated in the pipe is large, open the telescopic rod, the electric telescopic rod 24 extends, the hydrate in the pipeline cannot pass through the sponge 22, and continues to move forward with the sieve plate 23. The gas and water are separated into the pipe section behind the sieve plate 23 through the sponge 22 and the sieve plate 23, and the hydrate solids in the pipeline are compressed. When the sieve plate 23 moves to the other side wall or contacts the incompressible hydrate solids, the telescopic rod contracts, and the gas and liquid behind the sieve plate 23 return to the generation pipe section to continue to participate in hydrate generation. This process can be repeated many times until the hydrate solids fill or nearly fill the detection pipe section, and then the separation gate is closed to make the detection pipe section independent.

[0055] 4) Turn on the ERT resistance imaging device 5, the terahertz wave generating device 7, the terahertz wave detecting device 6 and the image acquisition system 9, use the ERT resistance imaging device 5 to radially measure the gas-liquid-solid interface morphology during the hydrate decomposition process, use the terahertz wave detecting device 6 to observe the amount of decomposed water on the surface of the hydrate block in real time, judge the speed of the decomposition rate during the decomposition process of the hydrate block surface, and collect the data to the computer 10 through the data acquisition system 8 for subsequent analysis. Different operations are performed according to the different unblocking methods tested. If an inhibitor effect test is required, open the first inhibitor valve 3 and the second inhibitor valve 12, and inject hydrate inhibitors (such as methanol, ethylene glycol, imidazole, PVP, PVCap, etc.) into the pipeline through the first inhibitor pump 2 and the second inhibitor pump 11, collect the data required for the experiment, and observe the intuitive situation of hydrate decomposition in the pipeline through the visual pipe section 44 and collect image information; if a temperature increase effect test is required, adjust the set temperature of the chiller 14 to raise the temperature in the pipeline to the required temperature, collect data, and The pipe section 44 observes the intuitive situation of hydrate decomposition in the pipeline and collects image information; if a pressure reduction effect test is required, the exhaust pressure of the first back pressure valve 1 and the second back pressure valve 13 is set. When it is detected that the pressure in the pipe section is higher than the set pressure of the back pressure valve, gas will be discharged into the waste liquid pool 27 to maintain the air pressure in the pipe section at the set value. The temperature and pressure sensor group 51 is used to collect and determine whether the pressure in the pipeline reaches the required pressure, and the data required for the experiment are collected. At the same time, the visual situation of hydrate decomposition in the pipeline is observed through the visible pipe section 44 and image information is collected; only one of the two back pressure valves can be opened to conduct a single-side pressure reduction decomposition experiment.

[0056] 5) After the experiment, open the separation gate, adjust the set temperature of the chiller 14, increase the pipeline temperature to decompose the hydrate, open the first liquid discharge valve 26 and the second liquid discharge valve 50, discharge the liquid and gas in the pipeline into the waste liquid pool 27, open the waste gas valve 29 and the waste gas pump 28, and fill the waste gas above the waste liquid pool 27 into the waste gas bottle 30 for storage.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for studying the process of solid phase blockage and unblocking of pipeline hydrate, characterized in that: include: The first pressure-resistant pipeline, the ERT resistance imaging device, the terahertz wave detection device, the visible pipe section, the third pressure-resistant pipeline, the separation valve, and the second pressure-resistant pipeline are connected in sequence through flanges to form a pressure-resistant test pipeline; A first back pressure valve and a first inhibitor pump are installed in parallel at the upper end of the first pressure-resistant pipeline, and a first inhibitor valve is arranged between the first inhibitor pump and the first pressure-resistant pipeline; a second liquid discharge valve is installed at the lower end of the first pressure-resistant pipeline, and a temperature and pressure sensor group is evenly arranged on the pipeline between the first pressure-resistant pipeline and the third pressure-resistant pipeline; The terahertz wave detection device is equipped with a terahertz wave generating device; A square transparent water tank is provided outside the visible pipe section, and an image acquisition system is provided outside the square transparent water tank; A second back pressure valve and a second inhibitor pump are installed in parallel at the upper end of the third pressure-resistant pipeline, and a second inhibitor valve is arranged between the second inhibitor pump and the third pressure-resistant pipeline; a second safety valve is installed at the lower end of the third pressure-resistant pipeline; A vacuum pump, a water injection tank and an air injection valve are installed in parallel at the upper end of the second pressure-resistant pipe, a vacuum valve is arranged between the vacuum pump and the second pressure-resistant pipe, and a water injection valve is arranged between the water injection tank and the second pressure-resistant pipe; a first liquid discharge valve and a first safety valve are installed in parallel at the lower end of the second pressure-resistant pipe, and a sponge, a sieve plate and an electric telescopic rod are installed inside the second pressure-resistant pipe; the air injection valve is connected to the gas cylinder.

2. The system for studying the process of solid phase blockage and unblocking of pipeline hydrate according to claim 1, characterized in that: All safety valves and drain valves are connected to the waste liquid pool through the waste liquid recovery pipeline, and the waste liquid pool is connected to the waste gas valve and waste gas bottle.

3. The system for studying the process of removing blockage caused by solid phase hydrate in pipelines according to claim 1, characterized in that: The outer sides of the first pressure-resistant pipe, the third pressure-resistant pipe, and the second pressure-resistant pipe are respectively covered with a third water bath jacket, a second water bath jacket, and a first water bath jacket; The third water bath jacket is connected to the square transparent water tank through the third jacket connecting pipe, and the third water bath jacket and the first water bath jacket are connected to the chiller through a cold water loop; the square transparent water tank is connected to the second water bath jacket through the second jacket connecting pipe, and the second water bath jacket is connected to the first water bath jacket through the first jacket connecting pipe.

4. The system for studying the process of solid-phase blockage and unblocking of pipeline hydrate according to claim 1, characterized in that: The temperature and pressure sensor group, the ERT resistance imaging device and the terahertz wave detection device are all connected to the computer through the data acquisition system.

5. The system for studying the process of solid-phase blockage and unblocking of pipeline hydrate according to claim 1, characterized in that: The pressure resistance of the pressure test pipeline is 0-8MPa, and the adjustable temperature range of the chiller 14 is -10℃-20℃.

6. The system for studying the process of solid-phase blockage and unblocking of pipeline hydrate according to claim 1, characterized in that: The side of the separation valve where the inhibitor pump is installed is the detection pipe section, and the other side of the separation valve is the generation pipe section; The sponge, sieve plate and electric telescopic rod form a scraper device to push the hydrates scattered in the tube into the detection tube section to form a hydrate solid phase section; the sieve plate is sealed with the tube wall by a rubber ring, tightly adhered to the sponge, and connected to the electric telescopic rod by threads. The sieve plate is densely covered with small holes to achieve material flow on both sides.

7. The system for studying the process of removing blockage caused by solid phase hydrate in pipelines according to claim 6, characterized in that: When the amount of hydrate generated in the pipe is greater than the set amount, the electric telescopic rod is turned on and extended. The hydrate in the pipe section cannot pass through the sponge and continues to move forward with the sieve plate. The gas and water are separated through the sponge and the sieve plate into the pipe section behind the sieve plate, thus achieving compression of the hydrate solids in the pipeline. When the screen plate moves to the other side wall or contacts the incompressible hydrate solid, the electric telescopic rod contracts, and the gas and liquid behind the screen plate return to the generation pipe section to continue to participate in hydrate generation.

8. The system for studying the process of solid-phase blockage and unblocking of pipeline hydrate according to claim 1, characterized in that: The water injection tank injects a certain amount of liquid into the pipeline through the water injection valve, and the liquid is deionized water.

9. The system for studying the process of removing blockage caused by solid phase hydrate in pipelines according to claim 1, characterized in that: The gas cylinder injects a certain amount of gas into the pipeline through the gas injection valve. The gas is natural gas, methane, CO2 or H2.

10. A method for studying the process of solid-phase blockage and unblocking of pipeline hydrates, based on the system for studying the process of solid-phase blockage and unblocking of pipeline hydrates as claimed in any one of claims 1 to 9, characterized in that: include: Use deionized water to thoroughly clean the inside of the pipeline, then open the vacuum valve and vacuum pump, evacuate the pipe section of the second pressure-resistant pipeline to a vacuum state, and extract the air inside the system; Keep the separation gate open, the electric telescopic rod in the shortest position, add deionized water to the water injection tank, open the water injection valve, and use the negative pressure in the pipeline to quantitatively inject deionized water into the pipeline; close the water injection valve, open the gas injection valve, inject natural gas into the pipeline through the gas cylinder, and collect the pressure in the pipeline through the temperature and pressure sensor group; Turn on the chiller, adjust the temperature to the experimental set temperature, keep the pipeline temperature stable, and continuously add gas to the pipeline through the gas injection valve to maintain the pressure in the pipeline at the experimental set pressure to generate hydrates; Turn on the ERT resistance imaging device, the terahertz wave generating device, the terahertz wave detecting device and the image acquisition system, use the ERT resistance imaging device to radially measure the gas-liquid-solid interface morphology during the hydrate decomposition process, use the terahertz wave detecting device to observe the amount of decomposed water on the surface of the hydrate block in real time, judge the decomposition rate during the decomposition process of the hydrate block surface, collect the data to the computer through the data acquisition system for subsequent analysis, and perform different operations according to the different deblocking methods tested; After the experiment, open the separation gate, adjust the set temperature of the chiller, increase the pipeline temperature to decompose the hydrate, open the first drain valve and the second drain valve, discharge the liquid and gas in the pipeline into the waste liquid pool, open the waste gas valve and the waste gas pump, and fill the waste gas above the waste liquid pool into the waste gas bottle for storage.

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