Pigging Device and Method for Deep-Water Long-Distance Pipeline

Abstract

The present invention relates to a pigging device and method for deep-water long-distance pipelines. The method includes: using the internal fluid of the pipeline to push the pigging device to move, and at the same time using an ultrasonic component to emit ultrasonic waves towards the inner wall of the pipeline; detecting the pressures at the front end and the rear end of the pigging device and calculating the pressure difference between the front end and the rear end; when the pressure difference between the front end and the rear end increases, increasing the ultrasonic frequency, and when the pressure difference between the front end and the rear end decreases, decreasing the ultrasonic frequency. The device includes a housing, a scraping member is arranged on the outer wall of the housing, a first pressure detection member and an ultrasonic component are arranged at the front end of the housing, a second pressure detection member is arranged at the rear end of the housing, and a power supply, a central control system and an ultrasonic controller are arranged inside the housing. The pigging device of the present invention has a simple structure and strong endurance, and the device and method can clean the pipeline sufficiently.

Description

Technical Field

[0001] The present invention belongs to the field of pigging equipment, and in particular, to a pigging device and method for deep - water long - distance pipelines. Background Art

[0002] The crude oil and natural gas produced in our country are characterized by high wax content and high pour point. With the increase of the in - service time of natural gas pipelines, a large amount of wax deposits and hydrates will accumulate in the pipelines, increasing the resistance during natural gas transportation and the energy consumption of the system. In some areas with severe wax deposition, even pipe - freezing accidents may occur.

[0003] In order to remove the deposits on the inner wall of the transportation pipeline, a pigging device needs to be used for cleaning. Traditional pigging tools move inside the pipeline to remove substances such as congealed oil, wax deposits, mechanical impurities, corrosion products such as iron sulfide, and accumulated water in oil and gas pipelines, so as to restore or improve the pipeline transportation efficiency.

[0004] Traditional pigging tools are mostly used in onshore oil and gas pipelines, and there are receiving and sending cylinders at certain intervals for taking them out. Therefore, traditional onshore pigging tools are convenient to use, but at the same time, they are relatively easy to be damaged in high - pressure or long - distance pipelines. At the same time, onshore pipelines mostly use scraping, brushing and other methods to clean the pipeline, which is easy to damage the pipeline. For deep - water long - distance submarine pipelines, with long distances and high pressures, the required pigging device needs to be able to be used for a long time and is not easily damaged, and is suitable for submarine high - pressure environments. Most onshore pigging tools are not suitable for submarine oil and gas migration pipelines or long - distance transportation.

[0005] CN106269730A discloses a self - powered ultrasonic descaling pigging tool, which introduces an ultrasonic generating device to replace the hard blades or steel brushes in other previous pipeline pigging tools, reducing the mechanical damage to the inner wall of the pipeline. An electromagnetic induction power generation device is set to convert part of the mechanical energy into electrical energy, so that the effect of long - distance pigging and descaling can be achieved without carrying a large - sized storage battery. This pigging tool has a relatively strong endurance, but it needs to set up a power generation mechanism, resulting in a large weight, complex structure and high cost of the whole pigging tool. In addition, transmission media such as oil and gas need to pass through the inside of the pigging tool, which is easy to contaminate the internal components.

[0006] CN114618841A discloses a pigging equipment for oil pipelines, which detects the position of agglomerates through a camera, and then moves the ultrasonic vibrator to a suitable position to remove the agglomerates. The structure of this equipment is also relatively complex, and there is no light inside the pipeline, so it must rely on a lighting lamp for illumination to enable the camera to take clear pictures, resulting in high energy consumption. In addition, there may be multiple agglomerates at the same axial position in the pipeline, which are difficult to be completely removed.

[0007] CN112238110A discloses a pipeline cleaning and dredging device that can move freely inside the pipeline, with a complex structure.

[0008] It can be seen that the structures of existing pigging devices are relatively complex and the equipment costs are high. For the pigging devices of deep-water long pipelines, energy conservation and enhanced endurance are very important. The endurance of the existing technologies is relatively poor, and during the pigging process of the existing technologies, the frequency of ultrasonic waves always remains the same, which is not energy-efficient during operation and reduces the endurance of the equipment. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a pigging device and method for deep-water long-distance pipelines, the device has a simple structure and strong endurance, and the device and method can fully clean the pipeline.

[0010] To solve the above problems, the technical solution adopted by the present invention is: a pigging method for deep-water long-distance pipelines,

[0011] using the fluid inside the pipeline to push the pigging device to move, and at the same time using an ultrasonic component to emit ultrasonic waves towards the inner wall of the pipeline;

[0012] detecting the pressures at the front end and the rear end of the pigging device, and calculating the pressure difference between the front end and the rear end;

[0013] When the pressure difference between the front end and the rear end increases, increasing the ultrasonic frequency, and when the pressure difference between the front end and the rear end decreases, decreasing the ultrasonic frequency.

[0014] Detecting the moving speed of the pigging device, when the pressure difference between the front end and the rear end increases rapidly and the change amount of the moving speed of the pigging device is less than the set value, the frequency of the ultrasonic waves remains unchanged.

[0015] A pigging device is provided with cup leather on it, and the cup leather is in sealed contact with the inner wall of the pipeline. When the pigging device moves, the cup leather scrapes off the impurities on the inner wall of the pipeline.

[0016] The frequency change range of the ultrasonic waves is 20KHz to 40KHz.

[0017] A pigging device for deep-water long-distance pipelines, including a housing, a scraping member is arranged on the outer wall of the housing, a first pressure detection member and an ultrasonic component are arranged at the front end of the housing, a second pressure detection member is arranged at the rear end of the housing, a power supply, a central control system and an ultrasonic controller are arranged inside the housing, the power supply, the first pressure detection member, the second pressure detection member and the ultrasonic controller are all connected to the central control system, and the ultrasonic component is connected to the ultrasonic controller.

[0018] Further, the scraping member is cup leather.

[0019] Further, a speed measuring element is arranged on the housing, and the speed measuring element is connected to the central control system.

[0020] Further, the ultrasonic component includes a plurality of uniformly distributed ultrasonic transmitters.

[0021] Further, the first pressure detection member and the second pressure detection member are connected to a differential pressure calculation member, and the differential pressure calculation member is connected to the central control system.

[0022] Further, the front end face of the housing is a spherical surface protruding outward.

[0023] The beneficial effects of the present invention are as follows: 1. Using the fluid inside the pipeline as the power to drive the pigging device to move, there is no need to set up an additional power mechanism, which can simplify the structure of the pigging device and does not consume electric energy, which is beneficial to improving the endurance. During the process of the fluid inside the pipeline driving the pigging device to move, if the impurities on the pipe wall increase, the resistance to the pigging device increases, the speed of the pigging device decreases, and then the thrust of the fluid behind the pigging device will increase, that is, the pressure received by the back of the pigging device increases, and the pressure difference between the front and rear ends of the pigging device by the fluid increases; conversely, if the impurities on the pipe wall decrease, the resistance to the pigging device decreases, the pressure received by the back of the pigging device decreases, and the pressure difference between the front and rear ends of the pigging device by the fluid decreases. According to this law, the present invention detects the change of the pressure difference between the front and rear of the pigging device, judges the amount of impurities according to the change of the pressure difference, and then adjusts the frequency of the ultrasonic wave according to the amount of impurities to ensure that the impurities are fully removed, while avoiding unnecessary power consumption of the ultrasonic component, thereby improving the endurance. In addition, compared with the ultrasonic component with a fixed frequency, the service life of the ultrasonic component of the present invention is greatly improved.

[0024] 2. The pigging device for the deep-water long-distance pipeline of the present invention has a very simple mechanical hardware structure, only including a housing, a scraping member and an ultrasonic component, with low weight and cost, reducing production costs, and being convenient to carry and transport. Description of the Drawings

[0025] Figure 1 is an overall schematic diagram of the pigging device for the deep-water long-distance pipeline of the present invention;

[0026] Figure 2 is a front schematic diagram of the pigging device for the deep-water long-distance pipeline of the present invention;

[0027] Reference Numerals: 1 - ultrasonic transmitter; 2 - housing; 3 - leather cup; 4 - differential pressure calculation member; 5 - second pressure detection member; 6 - power supply; 7 - central control system; 8 - speed measurement element; 9 - ultrasonic controller; 10 - first pressure detection member. Detailed Embodiments

[0028] The present invention will be further described below with reference to the drawings and embodiments.

[0029] The pigging device for deep-water long-distance pipelines of the present invention is as follows Figure 1 and Figure 2 shown, which includes a housing 2. A scraping member is provided on the outer wall of the housing 2. A first pressure detection member 10 and an ultrasonic component are provided at the front end of the housing 2. A second pressure detection member 5 is provided at the rear end of the housing 2. A power supply 6, a central control system 7 and an ultrasonic controller 9 are provided inside the housing 2. The power supply 6, the first pressure detection member 10, the second pressure detection member 5 and the ultrasonic controller 9 are all connected to the central control system 7, and the ultrasonic component is connected to the ultrasonic controller 9.

[0030] The housing 2 is cylindrical, and the front end face of the housing 2 is a spherical surface protruding outward to reduce the moving resistance. The housing 2 is made of pressure-resistant material. The scraping member is used to directly contact the inner wall of the pipeline tightly, so as to scrape the impurities on the inner wall of the pipeline. In order to ensure the sealing between the scraping member and the inner wall of the pipeline and avoid scratching the inner wall of the pipeline, the scraping member is preferably a leather cup 3. There are multiple leather cups 3, which are fixedly sleeved on the outer wall of the housing 2.

[0031] The ultrasonic component can emit ultrasonic waves towards the inner wall of the pipeline, and the ultrasonic controller 9 is used to control the emission frequency of the ultrasonic component. By supplying different voltages to the ultrasonic controller 9, the ultrasonic component can emit ultrasonic waves of different frequencies. In order to ensure that the range of ultrasonic waves covers the entire inner wall of the pipeline, as Figure 2 shown, the ultrasonic component includes multiple uniformly distributed ultrasonic transmitters 1. The ultrasonic transmitters 1 are uniformly distributed in a circumferential shape. The specific number can be 4, 5 or 6, etc. The emission direction of each ultrasonic transmitter 1 is inclined outward.

[0032] The power supply 6 is used to supply power to each electrical component, and a common storage battery can be used. The first pressure detection member 10 and the second pressure detection member 5 are respectively used to detect the fluid pressure received at the front end and the rear end of the housing 2 in real time, and pressure sensors can be used; the first pressure detection member 10 and the second pressure detection member 5 are connected to a differential pressure calculation member 4, and the differential pressure calculation member 4 is connected to the central control system 7. The differential pressure calculation member 4 is used to calculate the difference between the detection results of the second pressure detection member 5 and the first pressure detection member 10, that is, the pressure difference, and transmit the pressure difference to the central control system 7. The central control system 7 is used to adjust the magnitude of the voltage provided to the ultrasonic controller 9, and further adjust the frequency of the ultrasonic waves emitted by the ultrasonic transmitter 1.

[0033] The pigging method for deep-water long-distance pipelines of the present invention is as follows

[0034] The internal fluid of the pipeline is utilized to push the pigging device to move, and meanwhile, an ultrasonic component is used to emit ultrasonic waves towards the inner wall of the pipeline. The pigging device for the entire deep-water long-distance pipeline is launched into the submarine pipeline through a pig launcher. The pipeline can be a pipeline for transporting oil, gas, or a mixture of oil and gas. The edge of the leather cup 3 is in close contact with the pipeline, and the internal fluid of the pipeline is used to push the entire pigging device forward. During the advancement of the pigging device, the leather cup 3 can directly scrape off the impurities generated by the unfixed wax.

[0035] The pressures at the front end and the rear end of the pigging device are detected, and the pressure difference between the front end and the rear end is calculated. Specifically, the first pressure detection component 10 detects the pressure received at the front end of the housing 2, the second pressure detection component 5 detects the pressure received at the rear end of the housing 2, and the pressure difference calculation component 4 calculates the pressure difference between the rear end and the front end of the housing 2.

[0036] According to Bernoulli's principle In the formula, are respectively the pressure, density, and velocity of the fluid, is a constant that remains unchanged. During the process of the internal fluid of the pipeline pushing the pigging device to move, if a large area of wax appears on the pipe wall, the resistance to the pigging device increases, the speed of the pigging device decreases, then the thrust of the rear fluid on the pigging device will increase, that is, the pressure received at the rear of the pigging device increases, and the pressure difference between the front and rear ends of the pigging device by the fluid increases; conversely, if the impurities on the pipe wall decrease, the resistance to the pigging device decreases, the pressure received at the rear of the pigging device decreases, and the pressure difference between the front and rear ends of the pigging device by the fluid decreases.

[0037] When the pressure difference between the front end and the rear end increases, the ultrasonic frequency is increased; when the pressure difference between the front end and the rear end decreases, the ultrasonic frequency is decreased.

[0038] According to the relationship between ultrasonic energy and frequency is Planck's constant, is the ultrasonic energy, is the frequency. When the energy is greater than the power output of the power supply is: Among them, P is the output frequency, β is the phase shift angle, U is the output voltage, R is the impedance. The acoustic wave transmitter 1 adjusts the phase shift angle according to the pressure difference, thereby changing the output frequency.

[0039] By detecting the change in the pressure difference before and after the pigging device, judging the amount of impurities according to the change in the pressure difference, and then adjusting the frequency of the ultrasonic wave according to the amount of impurities, it is ensured that the impurities are removed sufficiently, and at the same time, the unnecessary power consumption of the ultrasonic component is avoided, thereby improving the endurance. The scraped impurities are pushed out of the pipeline by the fluid or the pigging device.

[0040] Generally speaking, when the ultrasonic intensity increases, the cavitation intensity increases. However, when the ultrasonic wave reaches a certain value, the cavitation tends to be saturated. At this time, increasing the ultrasonic intensity will generate a large number of useless bubbles, thereby increasing the scattering attenuation and reducing the cavitation intensity. Therefore, the frequency change range of the ultrasonic wave is set to 20KHz to 40KHz.

[0041] A speed measuring element 8 is arranged on the housing 2, and the speed measuring element 8 is connected to the central control system 7. The speed measuring element 8 is used to detect the moving speed of the pigging device. There are inevitably narrow positions such as valves and interfaces on the pipeline. When the pigging device passes through these narrow positions, a throttling effect is generated, and the pressure of the fluid suddenly decreases. At this time, the pressure difference between the rear end and the front end of the pigging device suddenly increases. This situation is not caused by an increase in impurities on the inner wall of the pipeline, and there is no need to increase the frequency of the ultrasonic wave. Therefore, the present invention uses the speed measuring element 8 to detect the moving speed of the pigging device. When the pressure difference between the front end and the rear end increases rapidly and the change amount of the moving speed of the pigging device is less than the set value, it indicates that the pigging equipment is passing through a narrow position such as a valve, and the fluid generates a throttling effect, and the impurities on the pipe wall do not increase. Therefore, the frequency of the ultrasonic wave is controlled to be unchanged to avoid the cavitation effect, thereby prolonging the service life of the ultrasonic transmitter 1.

[0042] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Pigging method for deep - water long - distance pipelines, characterized in that: The pigging device is pushed to move by the internal fluid of the pipeline, and at the same time, an ultrasonic component emits ultrasonic waves towards the inner wall of the pipeline; The pressures at the front end and the rear end of the pigging device are detected, and the pressure difference between the front end and the rear end is calculated; When the pressure difference between the front end and the rear end increases, the ultrasonic frequency is increased, and when the pressure difference between the front end and the rear end decreases, the ultrasonic frequency is decreased; The moving speed of the pigging device is detected. When the pressure difference between the front end and the rear end increases rapidly and the change amount of the moving speed of the pigging device is less than the set value, the frequency of the ultrasonic wave remains unchanged.

2. The pigging method for deep-water long-distance pipelines according to claim 1, characterized in that: A pigskin cup (3) is arranged on the pigging device. The pigskin cup (3) is in sealed contact with the inner wall of the pipeline. When the pigging device moves, the pigskin cup (3) scrapes off the impurities on the inner wall of the pipeline.

3. The pigging method for deep-water long-distance pipelines according to claim 1, characterized in that: The frequency change range of the ultrasonic wave is 20KHz - 40KHz.

4. A pigging device for a deep-water long-distance pipeline for the pigging method of the deep-water long-distance pipeline described in claim 1, 2 or 3, characterized in that: It includes a housing (2). A scraping member is arranged on the outer wall of the housing (2). A first pressure detection member (10) and an ultrasonic component are arranged at the front end of the housing (2). A second pressure detection member (5) is arranged at the rear end of the housing (2). A power supply (6), a central control system (7) and an ultrasonic controller (9) are arranged inside the housing (2). The power supply (6), the first pressure detection member (10), the second pressure detection member (5) and the ultrasonic controller (9) are all connected to the central control system (7), and the ultrasonic component is connected to the ultrasonic controller (9).

5. The pigging device for deep-water long-distance pipelines according to claim 4, characterized in that: The scraping member is a pigskin cup (3).

6. The pigging device for deep-water long-distance pipelines according to claim 4, characterized in that: A speed - measuring element (8) is arranged on the housing (2), and the speed - measuring element (8) is connected to the central control system (7).

7. The pigging device for deep-water long-distance pipelines according to claim 4, characterized in that: The ultrasonic component includes a plurality of uniformly distributed ultrasonic transmitters (1).

8. The pigging device for deep-water long-distance pipelines according to claim 4, characterized in that: The first pressure detection member (10) and the second pressure detection member (5) are connected to a pressure - difference calculation member (4), and the pressure - difference calculation member (4) is connected to the central control system (7).

9. The pigging device for deep-water long-distance pipelines according to claim 4, characterized in that: The front end face of the housing (2) is a spherical face protruding outwards.

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