Anti-frost-heaving buried oil and gas transmission pipeline in cold region

Abstract

The utility model discloses a frost heaving resistant cold region buried oil and gas transmission pipeline which comprises a plurality of pipeline bodies which are sequentially connected end to end, each pipeline body is of a double-layer cavity structure formed by an inner-layer pipe and an outer-layer pipe in a sleeved mode, and a cavity between the outer-layer pipe and the inner-layer pipe is filled with a foam concrete layer. The inner wall of the inner-layer pipe is covered with a first anti-corrosion layer, and the outer wall of the inner-layer pipe is covered with an uneven sand grain layer. The inner wall of the outer-layer pipe is covered with an uneven sand grain layer, and the outer wall of the outer-layer pipe is covered with a second anti-corrosion layer. And the foam concrete layer is in close contact with the sand grain layers of the inner-layer pipe and the outer-layer pipe. According to the scheme, frost heaving and corrosion of the buried oil and gas conveying pipeline can be effectively prevented, and the service life of the buried oil and gas conveying pipeline in the cold region is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of oil and gas transmission pipelines, in particular to a cold-region buried oil and gas transmission pipeline which is resistant to frost heave. Background Art

[0002] The China-Russia crude oil pipeline is one of the four major strategic energy channels in my country. It has made important contributions to ensuring national energy security, optimizing the oil supply and transportation pattern, deepening China-Russia strategic cooperation, and promoting economic and social development. The most serious problems and threats faced during the construction and operation of the China-Russia crude oil pipeline are permafrost and permafrost engineering diseases, namely, the instability of the pipe foundation and the degradation of the permafrost environment caused by the melting of permafrost. At the same time, the pipeline is prone to corrosion because the oil products transported contain sulfur and acidic substances, plus bacteria that metabolize sulfate on the surface of the pipeline and water accumulation around the pipe. In the cold environment, the safe and stable operation of buried oil and gas pipelines faces severe challenges. Changes in permafrost and corrosion factors in the soil may cause freeze-thaw deformation and corrosion damage to the pipeline. Utility Model Content

[0003] In view of the above-mentioned deficiencies in the prior art, the utility model provides a cold-region buried oil and gas transmission pipeline resistant to frost heave, which solves the problem in the prior art that cold-region pipelines are easily deformed by frost heave and damaged by corrosion.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] Provided is a cold-region buried oil and gas transmission pipeline that is resistant to frost heave, which comprises a plurality of pipeline bodies connected end to end in sequence, the pipeline body being a double-layer cavity structure formed by overlapping an inner layer pipe and an outer layer pipe, the cavity between the outer layer pipe and the inner layer pipe being filled with a foam concrete layer; the inner wall of the inner layer pipe being covered with a first anti-corrosion layer, and the outer wall being covered with an uneven sand layer; the inner wall of the outer layer pipe being covered with an uneven sand layer, and the outer wall being covered with a second anti-corrosion layer; the foam concrete layer is in close contact with the sand layers of both the inner layer pipe and the outer layer pipe.

[0006] The beneficial effects of the utility model are as follows: the double-layer pipe design itself increases the strength and rigidity of the pipe, and the outer pipe can protect the inner pipe from the influence of the external environment. Foamed concrete is a relatively excellent anti-deformation material and thermal insulation material. The foamed concrete layer filled in the pipe can not only enhance the anti-deformation ability of the pipe, but also effectively reduce the heat transfer inside and outside the pipe, improve the thermal insulation effect of the pipe, and reduce the direct influence of the external low temperature environment on the pipe, thereby improving the anti-freezing and deformation ability of the pipe.

[0007] The setting of the sand layer can effectively improve the roughness of the pipeline surface and provide a good adhesion foundation for the foam concrete layer. The rough surface increases the contact area and mechanical anchoring force, adhesion and durability between the foam concrete layer and the pipeline. The first anti-corrosion layer can prevent corrosion inside the pipe, and the second anti-corrosion layer can prevent corrosion outside the pipe.

[0008] Furthermore, the first anti-corrosion layer is a dense film structure, which is uniformly adsorbed on the inner wall of the inner layer pipe. The first anti-corrosion layer slows down the occurrence speed of the corrosion reaction and prolongs the service life of the pipeline.

[0009] Furthermore, the surface roughness of the inner wall of the inner layer pipe is less than 0.1 mm. The smooth surface helps the first anti-corrosion layer to be evenly distributed on the surface and form a dense protective film, thereby improving the overall anti-corrosion effect.

[0010] Furthermore, the thickness of the foamed concrete layer is 10 to 60 mm. The use of a suitable filling thickness can find a balance between structural stability and economy, and has the advantages of high strength and good economy.

[0011] Furthermore, the two end faces of the pipe body are fixedly connected with end panels, and a circular hole is opened in the center of the end panel for the inner layer pipe to extend into; the end panel, the outer layer pipe and the inner layer pipe together enclose a closed cavity, and the foam concrete layer is filled in the closed cavity. The end panels are provided to block the two ends of the pipe body, protect the internal filling layer, and prevent the foam concrete layer from being directly exposed to the external environment.

[0012] Furthermore, the end panel is a circular plate, the diameter of the circular hole of the end panel is equal to the sum of the outer diameter of the inner tube and the thickness of the sand layer of the inner tube, and the diameter of the end panel is equal to the sum of the diameter of the circular hole of the end panel and the thickness of the foam concrete layer. The end panel can be self-supported in the cavity between the inner tube and the outer tube, and can play a role of limiting support for the inner tube, ensuring that the inner tube and the outer tube are coaxially arranged, thereby ensuring that the radial force of the pipeline body is uniform.

[0013] Furthermore, adjacent pipe bodies are sealed and connected by a connecting piece, which includes a metal bellows, both ends of which are fixedly connected with annular hoops, the free end of which is provided with an internal thread, and both ends of the outer pipe are provided with external threads, the annular hoop is sleeved on the outer wall of the outer pipe and is threadably connected to the outer pipe.

[0014] Metal corrugated hose has good elasticity and can play a role in buffering and absorbing bending deformation, and can reduce the impact of frost heave and thaw settlement on buried oil and gas pipelines.

[0015] Furthermore, the inner wall of the metal bellows is evenly covered with the first anti-corrosion layer, and the outer wall is evenly covered with the second anti-corrosion layer, thereby improving the anti-corrosion capability of the metal bellows. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view of an underground oil and gas pipeline in a cold region that is resistant to frost heave;

[0017] Figure 2 It is a schematic diagram of the connection between the pipeline body and the connector;

[0018] Figure 3 A cross-sectional view of the end panel.

[0019] Among them, 1. pipeline body; 11. inner layer pipe; 12. outer layer pipe; 2. foam concrete layer; 31. first anti-corrosion layer; 32. second anti-corrosion layer; 4. sand layer; 5. connector; 52. metal bellows; 53. annular hoop; 6. end panel. DETAILED DESCRIPTION

[0020] The specific implementation methods of the utility model are described below to facilitate technical personnel in this technical field to understand the utility model, but it should be clear that the utility model is not limited to the scope of the specific implementation methods. For ordinary technical personnel in this technical field, as long as various changes are within the spirit and scope of the utility model defined and determined by the attached claims, these changes are obvious, and all utility model creations using the concept of the utility model are protected.

[0021] like Figure 1 As shown, the frost-heaving resistant cold-region buried oil and gas transmission pipeline of this scheme includes a plurality of sections of pipeline bodies 1 connected end to end in sequence. The pipeline body 1 is a double-layer cavity structure formed by overlapping an inner layer pipe 11 and an outer layer pipe 12. The cavity between the outer layer pipe 12 and the inner layer pipe 11 is filled with a foam concrete layer 2.

[0022] The double-layer pipe design itself increases the strength and rigidity of the pipe, and the outer pipe 12 can protect the inner pipe 11 from the influence of the external environment, so that the pipe's ability to resist the pressure and deformation of the external environment is enhanced. The foamed concrete layer 2 has high compressive strength and good ductility. When deformation or stress occurs, it can absorb part of the energy and reduce the deformation and damage of the pipe. After filling the cavity between the double-layer pipes, this strengthening effect is more obvious.

[0023] The characteristics of foam concrete are: it contains a large number of closed pores inside, which greatly reduce the thermal conductivity of the material, making foam concrete a relatively excellent thermal insulation material. Therefore, the foam concrete layer 2 filled in the pipeline can not only enhance the pipeline's anti-deformation ability, but also effectively reduce the heat transfer inside and outside the pipeline, improve the thermal insulation effect of the pipeline, reduce the heat exchange between the medium in the pipe and the soil around the pipe, weaken the influence of frost heave and thaw settlement on the pipeline body 1, thereby improving the pipeline body 1's anti-frost heave and thaw settlement differential deformation ability and anti-destruction ability.

[0024] The inner wall of the inner layer pipe 11 is covered with a first anti-corrosion layer 31, and the outer wall is covered with an uneven sand layer 4; the inner wall of the outer layer pipe 12 is covered with an uneven sand layer 4, and the outer wall is covered with a second anti-corrosion layer 32; the foam concrete layer 2 is in close contact with the sand layer 4 of the inner layer pipe 11 and the outer layer pipe 12. The first anti-corrosion layer 31 can prevent corrosion inside the pipe, reduce friction resistance, and increase the transmission capacity. The outer layer pipe 12 and the second anti-corrosion layer 32 isolate the inner layer pipe 11 from various corrosive media, and can protect the inner layer pipe 11.

[0025] The sand layer 4 can be attached to the pipe wall by sandblasting. The setting of the sand layer 4 can effectively increase the roughness of the outer surface of the inner pipe 11, providing a good attachment basis for the foamed concrete layer 2. The rough surface increases the contact area and mechanical anchoring force, adhesion and durability between the foamed concrete layer 2 and the pipe. In addition, the setting of the sand layer 4 can assist in removing impurities such as dirt, grease, rust, etc. on the outer surface of the inner pipe 11 and the inner surface of the outer pipe 12, which helps to improve the anti-corrosion effect of the layer and extend the service life of the pipe.

[0026] Preferably, the outer tube 12 is a galvanized steel tube, and the second anti-corrosion layer 32 is a sprayed epoxy powder, specifically, it is a continuous fused epoxy powder anti-corrosion insulation layer formed after melting and solidification, and the second anti-corrosion layer 32 is hard and thin, has strong bonding with the steel tube, good mechanical properties, and excellent corrosion resistance. If the second anti-corrosion layer 32 on the outer surface of the galvanized steel tube layer is damaged, the exposed metal zinc contacts the soil and is easily combined with carbonates and other substances in the soil to form insoluble zinc carbonate, thereby forming a new dense protective layer to prevent the continued occurrence of corrosion.

[0027] The first anti-corrosion layer 31 is a dense film structure, which is uniformly adsorbed on the inner wall of the inner tube 11. The first anti-corrosion layer 31 is preferably an organic corrosion inhibitor, which can form a protective film on the inner wall of the inner tube 11 to protect the pipeline. The corrosion inhibitor protective film will increase the activation energy required for the chemical reaction, thereby slowing down the occurrence of the corrosion reaction and extending the service life of the pipeline.

[0028] The surface roughness of the inner wall of the inner tube 11 is less than 0.1 mm. The inner wall of the inner tube 11 is preferably ground and polished to ensure that it is as smooth as possible, which helps the corrosion inhibitor to be evenly distributed on the surface after coating and form a dense protective film, while obtaining a more uniform coating thickness and improving the overall anti-corrosion effect.

[0029] The thickness of the foamed concrete layer 2 is preferably 10 to 60 mm. The use of a suitable filling thickness can find a balance between structural stability and economy, and has the advantages of both high strength and good economy.

[0030] The two end faces of the pipeline body 1 are fixedly connected with the end panels 6, and the center of the end panels 6 is provided with a circular hole for the inner layer tube 11 to extend into; the end panels 6, the outer layer tube 12 and the inner layer tube 11 together enclose a closed cavity, and the foam concrete layer 2 is filled in the closed cavity. The end panels 6 are provided to block the two ends of the pipeline body 1, protect the internal filling layer, and prevent the foam concrete layer 2 from being directly exposed to the external environment.

[0031] refer to Figure 2 The end panel 6 is a circular plate, the diameter of the circular hole of the end panel 6 is equal to the sum of the outer diameter of the inner layer tube 11 and the thickness of the sand layer 4 of the inner layer tube 11, and the diameter of the end panel 6 is equal to the sum of the diameter of the circular hole of the end panel 6 and the thickness of the foam concrete layer 2. The end panel 6 can be self-supported in the cavity between the inner layer tube 11 and the outer layer tube 12, and can play a role of limiting support for the inner layer tube 11, ensuring that the inner layer tube 11 and the outer layer tube 12 are coaxially arranged, thereby ensuring that the radial force of the pipeline body 1 is uniform.

[0032] Adjacent pipe bodies 1 are sealed and connected by a connector 5, which includes a metal bellows 52, an annular hoop 53 is fixedly connected to both ends of the metal bellows 52, an internal thread is provided at the free end of the annular hoop 53, and both ends of the outer tube 12 are provided with external threads, and the annular hoop 53 is sleeved on the outer wall of the outer tube 12 and is threadedly connected to the outer tube 12. The inner wall of the metal bellows is evenly covered with a first anti-corrosion layer 31, and the outer wall is evenly covered with a second anti-corrosion layer 32, so as to enhance the anti-corrosion ability of the metal bellows.

[0033] The metal corrugated hose has good elasticity, can play a role in buffering and absorbing bending deformation, and can reduce the impact of frost heave and thaw settlement on buried oil and gas pipelines. By setting the connector 5, a detachable connection between the pipeline bodies 1 can be achieved, which is convenient for maintenance or replacement of a certain section of the pipeline body 1. The threaded connection node needs to be sealed, for example, an annular groove can be opened on the inner wall of the annular hoop 53, and a sealing gasket can be installed in the annular groove, or thread sealant can be used.

[0034] The manufacturing steps of the pipeline body 1 of the utility model are:

[0035] S1. Prepare a stainless steel seamless steel pipe as the inner layer pipe 11, use polishing paste and cloth wheel to roughly polish its inner wall to make the polished area smooth and shiny, and then use a clean cloth wheel to polish and remove dust and other traces so that the corrosion inhibitor can form a uniform protective film on the inner surface;

[0036] S2. The inner surface of the inner tube 11 is uniformly coated with an organic corrosion inhibitor as a first anti-corrosion layer 31, and the outer surface of the inner tube 11 is sandblasted with a sandblasting machine to form a sand layer 4;

[0037] S3 prepares a galvanized steel pipe as the outer tube 12, and uses a sandblasting machine to sandblast the inner surface of the galvanized steel pipe layer to form a sand layer 4;

[0038] S4. The outer tube 12 is sleeved outside the inner tube 11, and the end panel 6 is fixedly connected at one end and the two pipes are placed vertically so that the inner tube 11 and the outer tube 12 remain coaxial;

[0039] S5. Pouring foamed concrete between the inner tube 11 and the outer tube 12 to form a foamed concrete layer 2, and curing it;

[0040] S6. Use electrostatic spraying equipment to evenly spray the fused epoxy powder on the outer surface of the outer tube 12 to form a uniform second anti-corrosion layer 32, and perform curing treatment on the sprayed components. Through melting and cross-linking, the epoxy powder forms a solid anti-corrosion insulation layer to improve its adhesion and corrosion resistance.

[0041] In summary, this solution can effectively prevent frost heave and corrosion of buried oil and gas pipelines, and increase the service life of buried oil and gas pipelines in cold regions.

Claims

1. A cold-region buried oil and gas pipeline resistant to frost heave, characterized by: The invention comprises a pipeline body (1) which is connected end to end in sequence. The pipeline body (1) is a double-layer cavity structure formed by overlapping an inner layer tube (11) and an outer layer tube (12). The cavity between the outer layer tube (12) and the inner layer tube (11) is filled with a foam concrete layer (2); the inner wall of the inner layer tube (11) is covered with a first anti-corrosion layer (31), and the outer wall is covered with an uneven sand layer (4); the inner wall of the outer layer tube (12) is covered with an uneven sand layer (4), and the outer wall is covered with a second anti-corrosion layer (32); the foam concrete layer (2) is in close contact with the sand layers (4) of the inner layer tube (11) and the outer layer tube (12).

2. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 1 is characterized in that: The first anti-corrosion layer (31) is a dense membrane structure, which is uniformly adsorbed on the inner wall of the inner layer tube (11).

3. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 2 is characterized in that: The surface roughness of the inner wall of the inner layer tube (11) is less than 0.1 mm.

4. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 1 is characterized in that: The thickness of the foamed concrete layer (2) is 10 to 60 mm.

5. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 1 is characterized in that: The two end faces of the pipe body (1) are fixedly connected with end panels (6), and a circular hole for the inner layer pipe (11) to extend into is provided at the center of the end panel (6); the end panel (6), the outer layer pipe (12) and the inner layer pipe (11) together enclose a closed cavity, and the foam concrete layer (2) is filled in the closed cavity.

6. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 5 is characterized in that: The end panel (6) is a circular plate, the diameter of the circular hole is equal to the sum of the outer diameter of the inner tube (11) and the thickness of the sand layer (4) of the inner tube (11), and the diameter of the end panel (6) is equal to the sum of the diameter of the circular hole and the thickness of the foam concrete layer (2).

7. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 1 is characterized in that: Adjacent pipe bodies (1) are sealedly connected via a connector (5), the connector (5) comprising a metal bellows (52), both ends of the metal bellows (52) being fixedly connected with an annular hoop (53), the free end of the annular hoop (53) being provided with an internal thread, both ends of the outer layer pipe (12) being provided with an external thread, the annular hoop (53) being sleeved on the outer wall of the outer layer pipe (12) and being threadedly connected with the outer layer pipe (12).

8. The cold-region buried oil and gas pipeline resistant to frost heave according to claim 7 is characterized in that: The inner wall of the metal bellows is evenly covered with a first anti-corrosion layer (31), and the outer wall is evenly covered with a second anti-corrosion layer (32).

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