A method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline

Abstract

This invention belongs to the field of oilfield oil and gas gathering and transportation technology, and discloses a method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline. The method includes: preheating oil and water samples and the equipment; adding different proportions of oil and water samples to a mixer according to different water contents; shearing the crude oil; cooling while stirring; maintaining a constant temperature; weighing the mass of oil residue adhering to the inner wall of the mixing tank; obtaining the critical wall adhesion temperature corresponding to the sudden change in wall adhesion mass; if the crude oil water content is before the inversion point, this wall adhesion temperature is used as the gathering and transportation temperature for on-site testing; if the pressure along the pipeline exceeds the pipeline's pressure-bearing capacity during the gathering and transportation process, the gathering and transportation temperature needs to be increased until the pressure along the pipeline is below the pipeline's pressure-bearing capacity, and this temperature is the gathering and transportation temperature; if the crude oil water content is after the inversion point, the gathering and transportation temperature is set above the wall adhesion temperature. This invention can more conveniently and accurately determine the gathering and transportation temperature at different stages of oilfield development, ensuring the safe and economical operation of oilfield gathering and transportation pipelines.

Description

Technical Field

[0001] This invention belongs to the field of oilfield oil and gas gathering and transportation technology, specifically relating to a method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline. Background Technology

[0002] The crude oil produced in my country's oilfields is mainly high-viscosity crude oil that is easy to solidify. In the early stages of oilfield development, the water cut is low, and the flow pattern of the produced fluid is mainly "oil-in-water". Crude oil with low water cut has a high viscosity. As oil wells are gradually developed, the water cut gradually increases, and the oil-water mixture undergoes phase reversal. When the water cut exceeds the reversal point, the flow pattern of the water-bearing crude oil changes, gradually shifting from a predominantly "oil-in-water" flow pattern to a predominantly "water-in-oil" flow pattern. Because water has a higher viscosity and pour point than crude oil, the viscosity of the produced fluid is lower than when the water cut is low, and the fluidity is also improved. In the later stages of oilfield development, entering the high water cut stage, the viscosity of the produced fluid decreases significantly, and the fluidity increases significantly.

[0003] In summary, the flow regime and flow properties of fluids within gathering and transportation pipelines vary significantly at different stages of oilfield development, and the methods for determining the gathering and transportation temperature also differ. It is crucial to ensure that the gathering and transportation temperature remains above a certain point. Below this point, crude oil adheres to the pipeline's inner wall, reducing the effective flow area, increasing pipeline resistance, and leading to a rapid increase in pressure along the pipeline. In severe cases, this can even cause pipe blockage, threatening the safe operation of the gathering and transportation pipeline. Therefore, determining the gathering and transportation temperature throughout the entire lifecycle of the pipeline is a key technology in oilfield gathering and transportation processes to ensure normal oilfield production. However, a universally applicable method suitable for the widespread adoption of gathering and transportation systems is lacking, and the determination method needs further improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline, which can more conveniently and accurately determine the gathering and transportation temperature at different stages of oilfield development, and ensure the safe and economical operation of oilfield gathering and transportation pipelines.

[0005] The technical solution adopted in this invention is a method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline, which includes the following steps: S1. Preheating of oil and water samples and equipment; S2. Add different proportions of oil and water samples to the mixer according to different moisture contents; S3. Turn on the agitator to shear crude oil with different water contents; S4. Adjust the stirring speed and cool down while stirring; S5. After reaching the set temperature, maintain constant temperature. S6. Discharge the oil-water mixture and weigh the mass of the oil stains adhering to the inner wall of the mixing tank. S7. Repeat S2-S6 until the wall adhesion quality changes abruptly. The set temperature at the time of the change is the critical wall adhesion temperature. S8. If the water content of crude oil is before the reversal point, an on-site cooling test needs to be carried out. The wall adhesion temperature is used as the gathering and transportation temperature for on-site testing. If the pressure along the pipeline exceeds the pipeline's pressure-bearing capacity during the gathering and transportation process, the gathering and transportation temperature needs to be increased until the pressure along the pipeline is below the pipeline's pressure-bearing capacity. The temperature at this point is the gathering and transportation temperature. S9. If the water content of crude oil is after the reversal point, the critical wall adhesion temperature shall be used as the gathering and transportation temperature boundary, and the gathering and transportation temperature shall be set above the wall adhesion temperature.

[0006] Furthermore, before S1, the process includes: the experimental oil sample and water sample are respectively made from dehydrated crude oil and corresponding well produced water. After dehydration, the experimental oil sample needs to be pretreated to eliminate the influence of thermal history and shear history on the crude oil. Then, it is sealed in a glass bottle and placed in the dark to obtain the dehydrated crude oil.

[0007] Further, S1 specifically includes the following steps: turning on the heating water bath, setting the temperature to 5°C above the emulsion's freezing point, placing the oil sample and water sample into the water bath for heating, and simultaneously setting the temperature of the stirring tank to 5°C above the emulsion's freezing point.

[0008] Furthermore, S2 specifically includes the following steps: confirming that the drain valve at the bottom of the mixing tank is closed, and when the temperature-controlled water bath of the mixing tank reaches the set temperature, pouring the water sample and oil sample into the mixing tank in the order of water first and then oil according to the water content ratio of the oil well.

[0009] Furthermore, the stirring speed in S3 is set to 1000 r / min.

[0010] Furthermore, the specific steps for adjusting the stirring speed and cooling while stirring as described in S4 are as follows: the stirring speed is adjusted to 200 r / min, the temperature of the temperature-controlled water bath is set to a certain temperature below the freezing point, and the temperature is cooled while stirring at a cooling rate of 0.5℃ / min.

[0011] Furthermore, the constant temperature time in S5 is 10 minutes.

[0012] Furthermore, the specific steps for weighing the oil stains adhering to the inner wall of the mixing tank as described in S6 are as follows: under the condition that the mixing tank is kept in a shear state, the oil-water mixture in the mixing tank is discharged from the lower drain valve, the volume of free water is measured, the height of the solidified oil adhering to the inner wall of the mixing tank is measured, the solidified oil on the tank wall is scraped off with a scraper, and the mass of the solidified oil on the tank wall is weighed.

[0013] Furthermore, the specific steps of S7 are as follows: determine whether the wall adhesion quality suddenly increases. If the wall adhesion quality does not change abruptly, repeat the operations of S2 to S6 to test the wall adhesion quality of the emulsion at different temperatures until the wall adhesion quality changes abruptly.

[0014] Furthermore, the on-site cooling experiment described in S8 reduces the pipeline transport temperature by adjusting the temperature of the heating furnace, and gradually reduces the temperature of the heating furnace in a step-down manner.

[0015] The beneficial effects of this invention are as follows: This invention is the first to realize a method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline. The entire life cycle of the gathering and transportation pipeline in this invention can be divided into two stages: the low water content stage before the oil reversal point and the medium-high water content stage after the oil reversal point. This covers different stages of the oilfield gathering and transportation process and has universal applicability for the promotion of gathering and transportation systems.

[0016] This invention enables more convenient and accurate determination of the gathering and transportation temperature at different stages of oilfield development, ensuring the safe and economical operation of oilfield gathering and transportation pipelines. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method for determining the gathering and transportation temperature throughout the entire life cycle of the gathering and transportation pipeline according to the present invention.

[0018] Figure 2 This is a flowchart illustrating a method for determining the gathering and transportation temperature throughout the entire lifecycle of a gathering and transportation pipeline, as provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the stirring simulation system.

[0020] Figure 4 This is a schematic diagram illustrating how the quality of crude oil emulsion adhering to the wall changes with temperature during the testing of the present invention.

[0021] In the diagram: 1. Temperature-controlled water bath; 2. Stirring motor; 3. Magnetic sealing cover; 4. Stirring paddle; 5. Stirring tank; 6. Drain valve; 7. Bottom support; 8. Digital display control box; 9. Control box switch button; 10. Motor speed adjustment knob; 11. Digital display of motor speed; 12. Digital display of sample temperature; 13. Temperature sensor. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] Example 1 like Figure 1 As shown, the method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline according to the present invention includes the following steps: S1. Preheating of oil and water samples and equipment; S2. Add different proportions of oil and water samples to the mixer according to different moisture contents.

[0024] S3. Turn on the agitator to shear crude oil with different water contents.

[0025] S4. Adjust the stirring speed and cool down while stirring.

[0026] S5. After reaching the set temperature, maintain constant temperature.

[0027] S6. Discharge the oil-water mixture and weigh the amount of oil residue adhering to the inner wall of the mixing tank.

[0028] S7. Repeat S2-S6 until the wall adhesion quality changes abruptly. The set temperature at the time of the change is the critical wall adhesion temperature.

[0029] S8. If the water content of crude oil is before the reversal point, an on-site cooling test needs to be carried out. The wall adhesion temperature is used as the gathering and transportation temperature for on-site testing. If the pressure along the pipeline exceeds the pipeline's pressure-bearing capacity during the gathering and transportation process, the gathering and transportation temperature needs to be increased until the pressure along the pipeline is below the pipeline's pressure-bearing capacity. The temperature at this point is the gathering and transportation temperature.

[0030] S9. If the water content of crude oil is after the reversal point, the overall water content will increase, and the flow state and flow properties of the fluid in the gathering and transportation pipeline will be significantly improved. The pressure along the pipeline will not exceed the pipeline's pressure-bearing capacity. The critical wall-adhering temperature will be used as the gathering and transportation temperature boundary. If the gathering and transportation temperature is set above the wall-adhering temperature, the gathering and transportation pipeline can operate safely.

[0031] Example 2 like Figure 2 As shown, the following steps are included before step S1: The experimental oil and water samples were dehydrated crude oil and corresponding produced water from oil wells, respectively. To avoid significant changes in oil sample properties over time, the dehydrated oil samples underwent pretreatment to eliminate the "memory" effect of thermal and shear history on the crude oil. Thermal and shear history alter the rheological properties and pour point of waxy crude oil by affecting the morphology and structure of wax crystals. These factors significantly influence the determination of the gathering and transportation temperature throughout the entire lifecycle of the pipeline. Therefore, pretreatment of the dehydrated crude oil is essential to eliminate the influence of thermal and shear history and improve the accuracy of the method determined by this patent. The dehydrated crude oil was obtained by sealing it in glass bottles and storing it in the dark.

[0032] The specific steps for preheating the oil sample, water sample, and apparatus mentioned in step S1 are as follows: turn on the heating water bath, set the temperature to 5°C above the emulsion freezing point, put the oil sample and water sample into the water bath and heat for 30 minutes, and at the same time set the temperature of the stirring tank to 5°C above the emulsion freezing point.

[0033] The specific steps for adding the sample into the device described in step S2 are as follows: confirm that the drain valve at the bottom of the stirring simulation tank is closed, and when the temperature-controlled water bath of the stirring tank reaches the set temperature, pour the water sample and oil sample into the stirring tank in the order of water first and then oil according to the water content ratio of the oil well, with a total volume of 200ml.

[0034] The specific steps for turning on the agitator and shearing crude oil at different water contents as described in step S3 are as follows: turn on the agitator, the agitator blade is a four-bladed blade with a diameter of 5cm, the agitator speed is set to 1000r / min, and the crude oil at different water contents is agitated and sheared for 10min.

[0035] The specific steps for adjusting the stirring speed and cooling while stirring in step S4 are as follows: adjust the stirring speed to 200 r / min, set the temperature of the temperature-controlled water bath to a certain temperature below the freezing point, and cool while stirring at a cooling rate of 0.5℃ / min.

[0036] In one specific embodiment of this application, in step S5, the preferred heat preservation time is 10 minutes.

[0037] The specific steps for weighing the oil stains adhering to the inner wall of the mixing tank in step S6 are as follows: under the condition that the mixing tank is kept in a shear state, the oil-water mixture in the mixing tank is discharged from the lower drain valve, the volume of free water is measured, the height of the solidified oil adhering to the inner wall of the mixing tank is measured, the solidified oil on the tank wall is scraped off with a scraper, and the mass of the solidified oil on the tank wall is weighed.

[0038] The specific steps for determining whether the wall-adhesion quality has undergone a sudden change, as described in step S7, are as follows: Determine if the wall-adhesion quality suddenly increases. If no sudden change occurs, repeat steps S2-S6 to test the wall-adhesion quality of the emulsion at different temperatures until a sudden change occurs. The temperature at which the wall-adhesion quality suddenly increases is the critical wall-adhesion temperature. The wall-adhesion temperature must be 1°C higher than the critical wall-adhesion temperature.

[0039] The antiphase point mentioned in steps S8 and S9 refers to the condensation (maximum) water content of the oil-water mixture when its apparent viscosity is at its maximum.

[0040] Example 3 like Figure 3 As shown, this embodiment provides a stirring simulation system, including a temperature-controlled water bath 1, a stirrer, and a control device. The temperature-controlled water bath 1 is located on one side of the stirrer. The stirrer includes a stirring motor 2, a magnetic sealing cover 3, a stirring paddle 4, a stirring tank 5, a drain valve 6, and a bottom support 7. The control device includes a digital display control box 8, a control box switch button 9, a motor speed adjustment knob 10, a motor speed digital display 11, a sample temperature digital display 12, and a temperature sensor 13.

[0041] The stirring motor 2 is located on top of the magnetic sealing cover 3, which is located on top of the mixing tank 5. The upper end of the stirring paddle 4 is connected to the output shaft of the stirring motor 2, and the lower end of the stirring paddle 4 extends into the mixing tank 5. The inner cavity of the mixing tank 5 has a size of Φ70×105mm. The drain valve 6 is located at the bottom of the mixing tank 5, and a bottom support 7 is also provided at the bottom of the mixing tank 5.

[0042] Temperature sensor 13 is located at the bottom inside the mixing tank 5. The stirring motor 2 and temperature sensor 13 are electrically connected to the controller in the digital display control box 8. The digital display control box 8 is equipped with a control box switch button 9, a motor speed adjustment knob 10, a motor speed digital display 11, and a sample temperature digital display 12. The speed of the stirring motor 2 can be controlled by controlling the motor speed adjustment knob 10. The motor speed digital display 11 is used to display the speed of the stirring motor 2, and the sample temperature digital display 12 is used to display the temperature of the sample in the mixing tank 5.

[0043] Example 4 like Figure 2 As shown, this embodiment provides examples for determining the wall adhesion temperature of crude oil with different water contents, the crude oil gathering and transportation temperature before the reversal point, and the crude oil gathering and transportation temperature after the reversal point.

[0044] 1) Examples of determining the wall adhesion temperature of crude oil with different water contents a) The experimental oil samples were pretreated after dehydration to eliminate the "memory" effect of crude oil on thermal and shear history. A batch of sealed ground glass bottles containing oil samples were placed in a water bath, heated to 80°C, and kept at that temperature for 2 hours to allow the crude oil in the bottles to reach a homogeneous state through the thermal motion of molecules. Then, the samples were allowed to cool naturally to room temperature and stored in a place with minimal temperature fluctuations for more than 48 hours. The oil samples were then considered to be base oil samples with the same compositional state.

[0045] Table 1 shows the basic parameters of the two oil samples selected in this embodiment. The overall water content of crude oil #1 is 36% before its reversal point, and the overall water content of crude oil #2 is 78% after its reversal point.

[0046]

[0047] b) Turn on the heating water bath and set the temperature to 5°C above the emulsion's freezing point. Place the oil and water samples in the water bath and heat for 30 minutes. At the same time, set the temperature of the stirring tank to 5°C above the emulsion's freezing point. Specifically, the water bath and stirring tank temperatures for crude oil #1 are set to 24°C, and the water bath and stirring tank temperatures for crude oil #2 are set to 27°C.

[0048] c) Confirm that the drain valve at the bottom of the mixing simulation tank is closed. When the temperature-controlled water bath of the mixing tank reaches the set temperature, pour the water sample and oil sample into the mixing tank in the order of water first and oil second, according to the water content of the oil well. The total volume of oil and water is 200ml.

[0049] d) Turn on the agitator. The agitator is a four-bladed blade with a diameter of 5cm. Set the speed to 1000r / min. Agitate and shear the crude oil at different water contents for 10min.

[0050] e) Adjust the stirring speed to 200 r / min, and set the temperature of the temperature-controlled water bath of the stirring tank to 1℃ below the pour point. The temperature of the temperature-controlled water bath of the stirring tank for crude oil No. 1 is set to 18℃, and the temperature of the temperature-controlled water bath of the stirring tank for crude oil No. 2 is set to 21℃. Cool down while stirring at a cooling rate of 0.5℃ / min.

[0051] f) After reaching the set temperature, maintain the temperature for 10 minutes. Under the condition of keeping the mixing tank in a shear state, release the oil-water mixture in the mixing tank from the lower outlet, measure the volume of free water, measure the height of the solidified oil adhering to the tank wall, scrape the solidified oil off the tank wall with a scraper, and weigh it. At a test temperature of 18℃, the mass of crude oil #1 adhering to the wall was 1.63g, and at a test temperature of 21℃, the mass of crude oil #2 adhering to the wall was 0.80g.

[0052] g) Repeat steps c-f to test the wall adhesion quality of the emulsion at different temperatures until a sudden increase in wall adhesion quality occurs. The temperature at which the wall adhesion quality suddenly increases is the critical wall adhesion temperature. The wall adhesion quality of crude oil #1 and crude oil #2 at different temperatures is shown in Tables 2 and 3.

[0053]

[0054] As shown in Tables 2 and 3, the wall adhesion mass of crude oil #1 increases sharply at 15℃, with a wall adhesion temperature of 16℃. Similarly, the wall adhesion mass of crude oil #2 increases sharply at 18℃, with a wall adhesion temperature of 19℃. The wall adhesion mass of crude oil #1 emulsion changes with temperature as follows: Figure 4 As shown.

[0055] 2) Example of determining crude oil gathering and transportation temperature before the reversal point The water content of crude oil #1 is 36%. This adhesion temperature was used as the gathering and transportation temperature for on-site testing. Thermometers and pressure gauges were installed at both ends of the inter-station oil gathering pipeline to monitor changes in parameters such as the flow state of the produced fluid, inlet and outlet temperatures, and other parameters. Specific operating parameters for the oil gathering pipeline are shown in Table 4.

[0056]

[0057] The field test reduced the pipeline transport temperature by adjusting the temperature of the heating furnace. The heating furnace temperature was gradually reduced in a step-down manner. After each reduction in the heating furnace temperature, sufficient time should be maintained to allow the soil temperature field to reach a new equilibrium, and at the same time, the hydraulic and thermal system in the oil collection pipeline should reach a new stability. The temperature at which the inlet temperature drops to the point where the inter-station pressure drop increases significantly is observed.

[0058] The field test lasted for 10 days. The changes in the operating parameters of the No. 1 crude oil gathering pipeline were obtained by adjusting the inlet temperature. Detailed operating parameters are shown in Table 5.

[0059]

[0060] As can be seen from the table, when the inlet temperature is between 18 and 24°C, the pressure parameters do not fluctuate significantly, and the pipeline can always operate safely. However, when the inlet temperature drops to 17°C, the pressure drop along the pipeline increases significantly to 0.3 MPa, requiring an increase in the gathering and transportation temperature until the pressure drop returns to stability. Therefore, the gathering and transportation temperature of No. 1 crude oil should be above 18°C.

[0061] 3) Example of determining crude oil gathering and transportation temperature after the phase reversal point The water content of No. 2 crude oil is 78%. After its reversal point, due to the increase in overall water content, the flow state and flow properties of the fluid in the gathering and transportation pipeline are significantly improved. The pressure along the pipeline will not exceed the pipeline's pressure bearing capacity. Therefore, the gathering and transportation temperature of No. 2 crude oil is set above the wall adhesion temperature, and the gathering and transportation pipeline can operate safely.

[0062] Components and structures not described in detail in the embodiments are well-known components, common structures or common means in the industry, and will not be described in detail here.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the gathering and transportation temperature throughout the entire life cycle of a gathering and transportation pipeline, characterized in that, Includes the following steps: S1. Preheating of oil and water samples and equipment; S2. Add different proportions of oil and water samples to the mixer according to different moisture contents; S3. Turn on the agitator to shear crude oil with different water contents; S4. Adjust the stirring speed and cool down while stirring; S5. After reaching the set temperature, maintain constant temperature. S6. Discharge the oil-water mixture and weigh the mass of the oil stains adhering to the inner wall of the mixing tank. S7. Repeat S2-S6 until the wall adhesion quality changes abruptly. The set temperature at the time of the change is the critical wall adhesion temperature. S8. If the water content of crude oil is before the reversal point, an on-site cooling test needs to be carried out. The wall adhesion temperature is used as the gathering and transportation temperature for on-site testing. If the pressure along the pipeline exceeds the pipeline's pressure-bearing capacity during the gathering and transportation process, the gathering and transportation temperature needs to be increased until the pressure along the pipeline is below the pipeline's pressure-bearing capacity. The temperature at this point is the gathering and transportation temperature. S9. If the water content of crude oil is after the reversal point, the critical wall adhesion temperature shall be used as the gathering and transportation temperature boundary, and the gathering and transportation temperature shall be set above the wall adhesion temperature.

2. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, Before S1, the process also includes: the experimental oil sample and water sample are respectively made from dehydrated crude oil and corresponding well produced water. After the experimental oil sample is dehydrated, it needs to be pretreated to eliminate the influence of thermal history and shear history on the crude oil. Then, it is sealed in a glass bottle and placed in the dark to obtain the dehydrated crude oil.

3. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, S1 specifically includes the following steps: turn on the heating water bath, set the temperature to 5°C above the emulsion's freezing point, put the oil sample and water sample into the water bath for heating, and at the same time set the temperature of the stirring tank to 5°C above the emulsion's freezing point.

4. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, S2 specifically includes the following steps: confirm that the drain valve at the bottom of the mixing tank is closed, and when the temperature-controlled water bath of the mixing tank reaches the set temperature, pour the water sample and oil sample into the mixing tank in the order of water first and oil second, according to the water content ratio of the oil well.

5. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, The stirring speed in S3 is set to 1000 r / min.

6. The gathering pipeline full life cycle gathering temperature determination method of claim 5, wherein, The specific steps for adjusting the stirring speed and cooling while stirring, as described in S4, are as follows: adjust the stirring speed to 200 r / min, set the temperature of the temperature-controlled water bath to a certain temperature below the freezing point, and cool while stirring at a cooling rate of 0.5℃ / min.

7. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, The constant temperature time in S5 is 10 minutes.

8. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, The specific steps for weighing the oil stains adhering to the inner wall of the mixing tank as described in S6 are as follows: under the condition that the mixing tank is kept in a shear state, the oil-water mixture in the mixing tank is discharged from the lower drain valve, the volume of free water is measured, the height of the solidified oil adhering to the inner wall of the mixing tank is measured, the solidified oil on the tank wall is scraped off with a scraper, and the mass of the solidified oil on the tank wall is weighed.

9. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, The specific steps in S7 are as follows: determine whether the wall adhesion quality suddenly increases. If the wall adhesion quality does not change abruptly, repeat the S2~S6 operations to test the wall adhesion quality of the emulsion at different temperatures until the wall adhesion quality changes abruptly.

10. The gathering pipeline full life cycle gathering temperature determination method of claim 1, wherein, The on-site cooling experiment described in S8 reduces the pipeline transport temperature by adjusting the temperature of the heating furnace, and gradually reduces the temperature of the heating furnace in a step-down manner.

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