Natural gas gathering pipeline free pig

Abstract

The purpose of this invention is to provide a non-recoverable pigging ball for natural gas gathering and transmission pipelines, comprising a hollow spherical body with small holes on its shell. The diameter of the holes is 3mm to 10mm, the shell thickness is 1cm to 3cm, and the interference fit between the outer diameter of the shell and the inner diameter of the pipeline to be cleaned is 3% to 5.5%. The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin. The tensile strength of the spherical body material ranges from 30MPa to 55MPa, the elongation at break is 50% to 75%, the pressure difference for the shell to break upon encountering resistance is 0.21MPa to 2.45MPa, the dissolution rate of the shell is 0.15mm / h to 1mm / h for outer diameter reduction, and the complete dissolution time is 108h to 120h. This invention solves the problems of easy jamming, ball loss, and difficulty in positioning during the cleaning of small-diameter gathering and transmission pipelines in gas fields that exist in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of pipeline cleaning technology, specifically relating to a natural gas gathering and transmission pipeline that does not require the collection of a cleaning ball. Background Technology

[0002] During gas field development, underground natural gas needs to be transported through pipelines. Since raw natural gas often contains produced water, foaming agents, and mechanical impurities, these can affect pipeline capacity, efficiency, metering accuracy, clog instruments, and exacerbate pipeline corrosion during gathering and transportation. For smaller-diameter gathering and transportation pipelines in gas fields, conventional cleaning techniques are prone to blockage, loss of cleaning balls, and difficulty in locating them; currently, there is no mature cleaning technology. Therefore, cleaning is rarely performed on small-diameter gathering and transportation pipelines in gas fields. During winter operation, the accumulated liquid inside the pipes can easily form hydrates, causing freezing blockages and leading to transportation shutdowns, affecting peak winter gas supply, and in severe cases, causing safety accidents.

[0003] As gas fields are developed on a large scale, more and more natural gas wells are entering the middle and late stages of their life cycle, and the produced water will gradually increase. As a result, the problems of liquid accumulation and freezing blockage in small-diameter gathering and transportation pipelines will become more and more prominent. Therefore, it is urgent to remove the liquid accumulation in small-diameter gathering and transportation pipelines.

[0004] Currently, there are few reports on pipeline cleaning technology for small-diameter gathering and transportation pipelines in gas fields, both domestically and internationally. While related soluble ball cleaning technologies can be found in domestic patent applications, they are all still in the initial design and laboratory research stages, with no mature products yet. Academic papers involve introductions to principles and small-scale trials, but no products have yet been applied on a large scale in gas fields.

[0005] In response to the current situation of gas field supply during winter, there is an urgent need to explore a pipeline cleaning method that is suitable for small-diameter gathering and transmission pipelines in gas fields, can remove accumulated liquid in the pipelines, and avoids blockage. This pipeline cleaning method is characterized by ease of operation, strong practicality, safety and environmental protection. Summary of the Invention

[0006] The purpose of this invention is to provide a method for cleaning pigs in natural gas gathering and transmission pipelines without the need for pig collection, which solves the problems of easy blockage, pig loss, and difficulty in positioning during the cleaning of small-diameter gathering and transmission pipelines in gas fields in the prior art.

[0007] The technical solution adopted in this invention is a natural gas gathering and transmission pipeline cleaning-free pig, which includes a spherical body, the spherical body being hollow, and small holes being opened on the shell of the spherical body.

[0008] The invention is further characterized in that,

[0009] The diameter of the small hole is 3mm to 10mm.

[0010] The thickness of the spherical shell is 1cm to 3cm.

[0011] The interference fit between the outer diameter of the spherical shell and the inner diameter of the pipe to be cleaned is 3% to 5.5%.

[0012] The interference fit between the outer diameter of the spherical shell and the inner diameter of the pipe to be cleaned is calculated as follows:

[0013] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0014] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0015] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles. The wear-resistant particles are evenly distributed in the modified resin, and the addition ratio is not less than 5% of the volume of the modified resin.

[0016] The tensile strength of the spherical bulk material ranges from 30 MPa to 55 MPa, and the Akron wear is no greater than 0.5 cm. 3 / 1.61km; elongation at break 50%–75%.

[0017] The pressure differential that causes the spherical shell to break upon encountering resistance is 0.21 MPa to 2.45 MPa.

[0018] The dissolution rate of the spherical shell is 0.15 mm / h to 1 mm / h in outer diameter reduction, and the complete dissolution time is 108 h to 120 h.

[0019] The beneficial effects of this invention are that it eliminates the need for pigging at the natural gas gathering and transmission pipeline. Only 1-2 people are required to launch the pig at the launching end. No positioning or tracking is needed along the route. If the pig encounters a blockage, it breaks and dissolves spontaneously. The dissolved substances have no impact on the gathering and transmission system, and there is no need to retrieve the pig at the receiving end. The cleaned-up liquid and dissolved substances are then processed downstream. This method saves manpower and operations at the receiving end, avoiding the complicated process and safety hazards associated with pig retrieval. The removal of accumulated liquid also eliminates the risk of hydrate freezing and blockage in winter, playing a positive supporting role in the safe transportation of the gathering and transmission system and ensuring supply during winter. It is highly practical. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the natural gas gathering and transmission pipeline that eliminates the need for pigging.

[0021] In the diagram, 1. small hole, 2. spherical shell. Detailed Implementation

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

[0023] This invention eliminates the need for pigging in natural gas gathering and transmission pipelines; the structure is as follows: Figure 1As shown, it includes a spherical body. The spherical design is similar to that of a rubber pigging ball, enhancing the seal with the pipeline and reducing wear during the pigging process. The hollow spherical body allows for breakage upon encountering resistance, resulting in fragmentation and rapid dissolution of the pigging ball. The breakage pressure differential is within a given range, and small holes 1 are opened on the spherical shell 2 of the spherical body.

[0024] The diameter of small hole 1 is 3mm to 10mm. The 3mm to 10mm diameter balances the internal and external pressure, preventing excessive air pressure from impacting the cleaning ball during the ball's launch and causing it to rupture.

[0025] The thickness of the spherical shell 2 is 1cm to 3cm. This thickness is designed based on a comprehensive consideration of factors such as pipeline specifications, elevation along the pipeline, working pressure, conveying medium, conveying gas volume, and given dissolution time.

[0026] The interference fit between the outer diameter of the spherical shell 2 and the inner diameter of the pipe to be cleaned is 3% to 5.5%. The interference fit design allows the spherical shell to fit tightly against the pipe wall, preventing air and liquid leakage, and better removing accumulated liquid or impurities.

[0027] The interference fit between the outer diameter of spherical shell 2 and the inner diameter of the pipe to be cleaned is calculated as follows:

[0028] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0029] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell 2; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0030] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin and added at a ratio of not less than 5% of the volume of the modified resin. After dissolving, the material is well-compatible with the produced water and has no impact on the gathering and transportation system, thus ensuring safety and environmental friendliness. Simultaneously, the material possesses certain tensile strength, wear resistance, elasticity, and the ability to withstand pipeline deformation.

[0031] The tensile strength of the spherical bulk material ranges from 30 MPa to 55 MPa, and the Akron wear is no greater than 0.5 cm. 3 / 1.61km; elongation at break 50%–75%.

[0032] The pressure differential that causes the spherical shell 2 to break upon encountering resistance is 0.21 MPa to 2.45 MPa.

[0033] The dissolution rate of the spherical shell 2 is 0.15 mm / h to 1 mm / h in terms of outer diameter reduction, and the complete dissolution time is 108 h to 120 h.

[0034] In this invention, the pigging ball is spherical in shape, which allows it to fit tightly against the inner wall of the pipeline, enhancing the sealing and cleaning capabilities while reducing uneven wear during the cleaning process. The pigging ball can pass through pipelines with a deformation of up to 30%.

[0035] The working principle and usage process of this invention are as follows: During use, the pipeline cleaning pig of this invention, which eliminates the need for retrieving the natural gas gathering and transmission pipeline, is placed in the pipeline launching cylinder. The pressure difference between the natural gas at one end of the pipeline and the two ends of the cleaning pig causes the cleaning pig to move forward. The interference fit of the cleaning pig ensures a tight fit with the inner wall of the pipeline, thereby pushing the accumulated liquid and impurities in the pipeline forward until they enter downstream processing. The cleaning pig then automatically enters the pipeline receiving cylinder. The operation requires no tracking or positioning, and no pig retrieval is needed. After dissolving, the cleaning pig automatically enters downstream processing. If blockage occurs en route, the cleaning pig will break and dissolve if the pressure difference before and after it is within the designed threshold range, allowing it to enter downstream processing without affecting the gathering and transmission system equipment.

[0036] Example 1

[0037] This invention eliminates the need for pigging in natural gas gathering and transmission pipelines; the structure is as follows: Figure 1 As shown, it includes a spherical body. The spherical design is similar to that of a rubber pigging ball, enhancing the seal with the pipeline and reducing wear during the pigging process. The hollow spherical body allows for breakage upon encountering resistance, resulting in fragmentation and rapid dissolution of the pigging ball. The breakage pressure differential is within a given range, and small holes 1 are opened on the spherical shell 2 of the spherical body.

[0038] The diameter of small hole 1 is 3mm. The 3mm diameter balances the internal and external pressure, preventing excessive air pressure from impacting the cleaning ball during the serve and causing it to break.

[0039] The thickness of the spherical shell 2 is 1cm. This thickness is designed based on a comprehensive consideration of factors such as pipeline specifications, elevation along the pipeline, working pressure, conveying medium, conveying gas volume, and given dissolution time.

[0040] The interference fit between the outer diameter of the spherical shell 2 and the inner diameter of the pipe to be cleaned is 3%. The interference fit design allows the spherical shell to fit tightly against the pipe wall, preventing air and liquid leakage, and better removing accumulated liquid or impurities.

[0041] The interference fit between the outer diameter of spherical shell 2 and the inner diameter of the pipe to be cleaned is calculated as follows:

[0042] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0043] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell 2; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0044] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin and added at a ratio of not less than 5% of the volume of the modified resin. After dissolving, the material is well-compatible with the produced water and has no impact on the gathering and transportation system, thus ensuring safety and environmental friendliness. Simultaneously, the material possesses certain tensile strength, wear resistance, elasticity, and the ability to withstand pipeline deformation.

[0045] The tensile strength of the spherical bulk material is in the range of 305 MPa, and the Akron abrasion is no greater than 0.5 cm. 3 / 1.61km; Elongation at break 50%.

[0046] The pressure difference that caused the spherical shell 2 to break upon encountering resistance was 0.21 MPa.

[0047] The dissolution rate of spherical shell 2 was 0.15 mm / h for outer diameter reduction, and the complete dissolution time was 108 h.

[0048] In this embodiment, the parameters of the pigging ball are generally too small during operation, and the pigging ball may break before reaching the end point, resulting in a slightly poorer pigging effect and requiring 2 to 3 attempts.

[0049] Example 2

[0050] This invention eliminates the need for pigging in natural gas gathering and transmission pipelines; the structure is as follows: Figure 1 As shown, it includes a spherical body. The spherical design is similar to that of a rubber pigging ball, enhancing the seal with the pipeline and reducing wear during the pigging process. The hollow spherical body allows for breakage upon encountering resistance, resulting in fragmentation and rapid dissolution of the pigging ball. The breakage pressure differential is within a given range, and small holes 1 are opened on the spherical shell 2 of the spherical body.

[0051] The diameter of small hole 1 is 10mm. The 10mm diameter balances the internal and external pressure, preventing excessive air pressure from impacting the cleaning ball during the serve and causing it to break.

[0052] The thickness of the spherical shell 2 is 3cm. This thickness is designed based on a comprehensive consideration of factors such as pipeline specifications, elevation along the pipeline, working pressure, conveying medium, conveying gas volume, and given dissolution time.

[0053] The interference fit between the outer diameter of the spherical shell 2 and the inner diameter of the pipe to be cleaned is 5.5%. The interference fit design allows the spherical shell to fit tightly against the pipe wall, preventing air and liquid leakage, and better removing accumulated liquid or impurities.

[0054] The interference fit between the outer diameter of spherical shell 2 and the inner diameter of the pipe to be cleaned is calculated as follows:

[0055] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0056] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell 2; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0057] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin and added at a ratio of not less than 5% of the volume of the modified resin. After dissolving, the material is well-compatible with the produced water and has no impact on the gathering and transportation system, thus ensuring safety and environmental friendliness. Simultaneously, the material possesses certain tensile strength, wear resistance, elasticity, and the ability to withstand pipeline deformation.

[0058] The tensile strength of the spherical bulk material is in the range of 55 MPa, and the Akron abrasion is no greater than 0.5 cm. 3 / 1.61km; Elongation at break 75%.

[0059] The pressure differential that caused the spherical shell 2 to break upon encountering resistance was 2.45 MPa.

[0060] The dissolution rate of spherical shell 2 is 1 mm / h for outer diameter reduction, and the complete dissolution time is 120 h.

[0061] In this embodiment, the parameters of the pigging ball are generally large during operation, the pigging ball reaches the end point intact, the pigging effect is good, and only one pigging ball is needed.

[0062] Example 3

[0063] This invention eliminates the need for pigging in natural gas gathering and transmission pipelines; the structure is as follows: Figure 1 As shown, it includes a spherical body. The spherical design is similar to that of a rubber pigging ball, enhancing the seal with the pipeline and reducing wear during the pigging process. The hollow spherical body allows for breakage upon encountering resistance, resulting in fragmentation and rapid dissolution of the pigging ball. The breakage pressure differential is within a given range, and small holes 1 are opened on the spherical shell 2 of the spherical body.

[0064] The diameter of small hole 1 is 7mm. The 7mm diameter balances the internal and external pressure, preventing excessive air pressure from impacting the cleaning ball during the serve and causing it to rupture.

[0065] The thickness of the spherical shell 2 is 2cm. This thickness is designed based on a comprehensive consideration of factors such as pipeline specifications, elevation along the pipeline, working pressure, conveying medium, conveying gas volume, and given dissolution time.

[0066] The interference fit between the outer diameter of the spherical shell 2 and the inner diameter of the pipe to be cleaned is 4%. The interference fit design allows the spherical shell to fit tightly against the pipe wall, preventing air and liquid leakage, and better removing accumulated liquid or impurities.

[0067] The interference fit between the outer diameter of spherical shell 2 and the inner diameter of the pipe to be cleaned is calculated as follows:

[0068] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0069] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell 2; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0070] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin and added at a ratio of not less than 5% of the volume of the modified resin. After dissolving, the material is well-compatible with the produced water and has no impact on the gathering and transportation system, thus ensuring safety and environmental friendliness. Simultaneously, the material possesses certain tensile strength, wear resistance, elasticity, and the ability to withstand pipeline deformation.

[0071] The tensile strength of the spherical bulk material is in the range of 40 MPa, and the Akron abrasion is no greater than 0.5 cm. 3 / 1.61km; Elongation at break 60%.

[0072] The pressure differential when the spherical shell 2 breaks due to obstruction is 1.5 MPa.

[0073] The dissolution rate of spherical shell 2 is 0.5 mm / h for outer diameter reduction, and the complete dissolution time is 110 h.

[0074] In this embodiment, the parameters of the pigging ball are moderate during operation, the pigging ball is basically intact when it reaches the end point, the pigging effect is obvious, and only one ball is needed.

[0075] Example 4

[0076] This invention eliminates the need for pigging in natural gas gathering and transmission pipelines; the structure is as follows: Figure 1 As shown, it includes a spherical body. The spherical design is similar to that of a rubber pigging ball, enhancing the seal with the pipeline and reducing wear during the pigging process. The hollow spherical body allows for breakage upon encountering resistance, resulting in fragmentation and rapid dissolution of the pigging ball. The breakage pressure differential is within a given range, and small holes 1 are opened on the spherical shell 2 of the spherical body.

[0077] The diameter of small hole 1 is 6mm. The 6mm diameter balances the internal and external pressure, preventing excessive air pressure from impacting the cleaning ball during the serve and causing it to rupture.

[0078] The thickness of the spherical shell 2 is 3cm. This thickness is designed based on a comprehensive consideration of factors such as pipeline specifications, elevation along the pipeline, working pressure, conveying medium, conveying gas volume, and given dissolution time.

[0079] The interference fit between the outer diameter of the spherical shell 2 and the inner diameter of the pipe to be cleaned is 5.5%. The interference fit design allows the spherical shell to fit tightly against the pipe wall, preventing air and liquid leakage, and better removing accumulated liquid or impurities.

[0080] The interference fit between the outer diameter of spherical shell 2 and the inner diameter of the pipe to be cleaned is calculated as follows:

[0081] X=[D1-(D2-2×δ)]×100% / (D2-2×δ)

[0082] In the formula, X is the interference fit of the pig; D1 is the outer diameter of the pig shell 2; D2 is the inner diameter of the pipe to be cleaned; and δ is the wall thickness of the pipe to be cleaned.

[0083] The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles, with the wear-resistant particles evenly distributed in the modified resin and added at a ratio of not less than 5% of the volume of the modified resin. After dissolving, the material is well-compatible with the produced water and has no impact on the gathering and transportation system, thus ensuring safety and environmental friendliness. Simultaneously, the material possesses certain tensile strength, wear resistance, elasticity, and the ability to withstand pipeline deformation.

[0084] The tensile strength of the spherical bulk material is in the range of 30 MPa, and the Akron wear is no greater than 0.5 cm. 3 / 1.61km; Elongation at break 50%.

[0085] The pressure difference that caused the spherical shell 2 to break upon encountering resistance was 0.21 MPa.

[0086] The dissolution rate of spherical shell 2 is 1 mm / h for outer diameter reduction, and the complete dissolution time is 120 h.

[0087] In this embodiment, the key parameters (except for interference fit and shell thickness, which are taken as larger values) during the operation of the pigging ball are moderate. The pigging ball is basically intact when it reaches the end point, and the pigging effect is good. One pigging ball is sufficient, and two pigging balls can be used for pipelines with more accumulated liquid.

[0088] This invention avoids the pigging ball getting stuck during the pigging process, eliminates the need for tracking and positioning, and eliminates the need for ball retrieval; it cleans up accumulated liquid and impurities in the pipeline; improves pipeline transportation efficiency; reduces pipeline pressure differential; avoids freezing blockage by hydrates in winter, eliminating safety hazards; reduces manpower for pigging operations, simplifies the pigging operation process, has strong cleaning ability, simple structure, is safe and environmentally friendly, and is highly practical.

Claims

1. A natural gas gathering and transmission pipeline that eliminates the need for pigging, characterized in that... It includes a spherical body, which is hollow. The spherical shell (2) of the spherical body has a small hole (1) with a diameter of 3mm to 10mm. The thickness of the spherical shell (2) is 1cm to 3cm. The interference fit between the outer diameter of the spherical shell (2) and the inner diameter of the pipe to be cleaned is 3% to 5.5%. The interference fit between the outer diameter of the spherical shell (2) and the inner diameter of the pipe to be cleaned is calculated as follows: In the formula, X is the interference fit of the pigging ball; D1 is the outer diameter of the pigging ball shell (2); D2 is the inner diameter of the pipe to be cleaned; δ is the wall thickness of the pipe to be cleaned. The spherical body is made of a mixture of water-soluble modified resin and wear-resistant particles. The wear-resistant particles are evenly distributed in the modified resin, and the addition ratio is not less than 5% of the volume of the modified resin. The tensile strength of the spherical body material is in the range of 30MPa to 55MPa, and the Akron abrasion is not greater than 0.5cm. 3 / 1.61km; Elongation at break 50%~75%, the pressure difference of the shell (2) when encountering resistance is 0.21MPa~2.45MPa, the dissolution rate of the shell (2) is 0.15mm / h~1mm / h for outer diameter reduction, and the complete dissolution time is 108h~120h.

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