Oil and gas field small-caliber gathering and transportation pipeline mouth pre-repairing method

Abstract

The invention provides an oil and gas field small-caliber gathering and transportation pipeline pre-joint-coating method which comprises the steps that the inner wall surface of a pipe end is treated, polishing machining is conducted within the preset distance range in the gathering and transportation pipeline end, and the inner wall of the pipe end is exposed out of a metal body; preheating metal ceramic powder: filling the exposed position of the inner wall of the pipe end with metal ceramic mixture powder, and preheating at a preset temperature; prefabricating a metal ceramic layer, uniformly burning metal ceramic mixture powder on the inner wall of the pipe end of the gathering and transportation pipeline, cooling, and removing a corundum layer and a transition layer, so that a corrosion-resistant alloy layer is flush with the inner wall of the steel pipe; and gathering and transportation pipeline anti-corrosion and welding treatment: carrying out anti-corrosion treatment on other positions of the inner wall of the pipeline, and then carrying out on-site welding. The method solves the technical problem of inner joint coating of the small-caliber gathering and transportation pipeline of the oil and gas field, realizes continuity of an anti-corrosion layer in the pipeline, and does not need inner joint coating after welding; the electrochemical corrosion risk caused by mechanical combination of the lining layer and the steel pipe can be avoided; and the defects of low surfacing efficiency and high cost can be overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion of small-diameter gathering and transportation pipelines in oil and gas fields, and specifically, to a method for pre-compensating joints of small-diameter gathering and transportation pipelines in oil and gas fields. Background Art

[0002] The oilfield surface gathering and transportation pipelines (with a diameter below DN200) have a small diameter, a high salinity and strong corrosivity of the transported medium, and are difficult to anti-corrode. Especially for the joint parts of small-diameter pipelines, due to the lack of suitable joint compensation technology, they become the weak links in pipeline anti-corrosion. According to relevant data statistics, 90% of the total corrosion perforations of gathering and transportation pipelines come from the corrosion of the inner wall, and 70% of them occur at joint parts such as joint compensation and elbows. Some pipelines are corroded and perforated after operating for 1 to 2 years, resulting in problems such as running, leaking, and dripping, which seriously affect the safe operation of oilfield stations. For large-diameter pipelines, generally, a joint compensation vehicle is used for joint compensation construction after pipeline welding. For small-diameter pipelines, due to their small diameter, the joint compensation vehicle cannot be applied, and on-site extrusion coating is generally used for internal anti-corrosion and joint compensation, but the anti-corrosion quality is difficult to guarantee.

[0003] Chinese Patent Application No. 2011202508763 provides a technology for internal anti-corrosion joint compensation with a corrosion-resistant alloy lined at the pipe end. The "lining" layer in this technology is mechanically combined with the steel pipe, and there is a risk of electrochemical corrosion; Chinese Patent Application No. 201210514544.0 discloses a pre-joint compensation technology for surfacing a stainless steel layer on the inner wall of the pipe end, which has defects such as low efficiency and high cost of surfacing the stainless steel layer; Chinese Patent Application No. 20150348243.9 discloses a method for internal joint compensation of anti-corrosion surfacing of submarine pipelines. This technology realizes internal joint compensation by surfacing a corrosion-resistant alloy with a certain width and thickness on the inner wall of the pipe end, and has defects such as low efficiency and high cost of surfacing the stainless steel layer; Chinese Patent Application No. 201210573393.6 discloses a metal-ceramic lined pipeline and its preparation method. This technology prepares a metal-ceramic lining layer on the inner wall of the pipeline. The inner wall of the pipeline is composed of a metal-ceramic layer composed of corundum and metallic titanium and an alloy layer composed of chromium-nickel-iron from the inside to the outside in the radial direction, and has defects such as difficult welding of the metal-ceramic layer and low accuracy of weld non-destructive testing. Summary of the Invention

[0004] In view of this, the present invention proposes a method for pre-compensating joints of small-diameter gathering and transportation pipelines in oil and gas fields, aiming to solve the existing problems.

[0005] A method for pre-compensating joints of small-diameter gathering and transportation pipelines in oil and gas fields proposed by the present invention includes the following steps: Step 1: Surface treatment of the inner wall of the pipe end. Grinding and processing are carried out within a preset distance range inside the pipe end of the gathering and transportation pipeline to expose the metal body on the inner wall of the pipe end. Step 2: Preheating of the metal-ceramic powder. The metal-ceramic mixture powder is filled at the exposed position on the inner wall of the pipe end and preheated at a preset temperature. Step 3: Prefabrication of the cermet layer. Uniformly flame-clad the cermet mixture powder on the inner wall of the pipe end of the gathering and transportation pipeline. After cooling, remove the corundum layer and the transition layer to make the corrosion-resistant alloy layer flush with the inner wall of the steel pipe. Step 4: Anti-corrosion and welding treatment of the gathering and transportation pipeline. Conduct anti-corrosion treatment on other positions of the inner wall of the pipeline, and then perform on-site welding.

[0006] Further, in the above Step 1, the range of the grinding process on the inner wall of the pipe end of the gathering and transportation pipeline is within 8 - 10 cm of the inner wall of the pipe end.

[0007] Further, in the above Step 1, the depth of the exposed metal body on the inner wall of the pipe end is 0.5 - 1.5 mm.

[0008] Further, in the above Step 2, the cermet powder mixture includes Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al.

[0009] Further, the above Step 3 includes the following sub-steps: i) Place the gathering and transportation pipeline on a centrifuge, start the centrifuge, and rotate the steel pipe. ii) Ignite the cermet powder. The powder reacts at high temperature and is uniformly clad on the inner wall of the pipe end of the pipeline as the pipeline rotates. iii) After the cladding is completed, cool it. After cooling, conduct mechanical processing on the inner wall of the pipe end of the pipeline to remove the corundum layer and the transition layer on the surface of the cermet, making the corrosion-resistant alloy layer flush with the inner wall of the steel pipe.

[0010] Specifically, by centrifugally self-propagating the cermet on the inner wall of the pipeline and then removing the corundum layer and the transition layer through mechanical processing, it avoids the defects that in some cases, the inner wall of the steel pipe is the corundum layer and the alloy layer, resulting in difficulties in welding and low accuracy of non-destructive testing of the weld.

[0011] Further, the particle size of the cermet powder is 100 - 300 mesh, and the total mass of the powder is adapted to the pipe diameter size and the required thickness of the cermet layer.

[0012] Further, in the cermet powder mixture, the mass ratios of Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al are 15 - 17%, 5 - 8%, 0.3 - 0.5%, 45 - 50%, 25 - 29% respectively.

[0013] Specifically, a corrosion-resistant layer prepared from the cermet powder mixture has good corrosion prevention performance, not only having good corrosion resistance to crude oil and oilfield sewage, but also having good corrosion resistance to acid and salt corrosives.

[0014] Further, in the second step, the preheating temperature is 100 - 110 °C, and the preheating time is 1.0 - 1.5 hours.

[0015] Further, the rotation speed of the gathering and transportation pipeline is 1500 - 1700 r / min.

[0016] Further, in the fourth step, the welding of the gathering and transportation pipeline is carried out with reference to the provisions of GB / T13148.

[0017] A pre-patching method for small-diameter gathering and transportation pipelines in oil and gas fields provided by the present invention has the following beneficial technical effects: It solves the technical problem of internal patching for small-diameter gathering and transportation pipelines in oil and gas fields. First, a corrosion-resistant alloy layer with a certain width and thickness is cladded on the inner wall of the pipe end of the small-diameter pipeline, and then after internal anti-corrosion of the pipeline and on-site welding, the anti-corrosion function of the internal patching area at the pipe end is replaced by the corrosion-resistant alloy layer, realizing the continuity of the internal anti-corrosion layer of the pipeline, and no internal patching is required after welding; it can avoid the risk of electrochemical corrosion existing in the mechanical bonding between the "inner lining" layer and the steel pipe; it can solve the defects of low surfacing efficiency and high cost in surfacing a stainless steel layer on the inner wall of the pipeline; by centrifugally self-propagating the cermet on the inner wall of the pipeline and then mechanically processing to remove the corundum layer and the transition layer, it avoids the defects that in some cases, the inner wall of the steel pipe is the corundum layer and the alloy layer, resulting in difficult welding and low accuracy of weld non-destructive testing; it provides a new idea and a new choice for internal patching of small-diameter gathering and transportation pipelines in oil and gas fields. Description of the Drawings

[0018] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 It is a schematic diagram of the steps of the pre-patching method for small-diameter gathering and transportation pipelines in oil and gas fields provided by the embodiment of the present invention; Figure 2 It is a schematic diagram of the structure after the inner wall of the pipe end of the gathering and transportation pipeline provided by the embodiment of the present invention is polished; Figure 3 It is a schematic diagram of the structure of the cermet layer on the inner wall of the pipe end of the gathering and transportation pipeline provided by the embodiment of the present invention; Figure 4 It is a schematic diagram of the structure after the corundum layer and the transition layer of the cermet layer on the inner wall of the pipe end of the gathering and transportation pipeline provided by the embodiment of the present invention are mechanically cut; Figure 5 Schematic diagram of the structure of the inner wall of the pipe end of the gathering and transportation pipeline after anti-corrosion treatment provided by the embodiment of the present invention; Figure 6 Schematic diagram of the structure after on-site welding at the joint of the gathering and transportation pipeline provided by the embodiment of the present invention; In the figure, 1 is the inner wall of the gathering and transportation pipeline, 2 is the prefabricated groove at the pipe end, 3 is the cermet layer, 31 is the corrosion-resistant alloy layer, 32 is the cermet transition layer, 33 is the cermet corundum layer, 4 is the anti-corrosion layer, 5 is the weld, 51 is the stainless steel weld, and 52 is the carbon steel weld. Detailed implementation manners

[0019] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

[0020] See Figure 1 As shown, it is a method for pre-compensating the joint of a small-diameter gathering and transportation pipeline in an oil and gas field provided by the embodiment of the present invention, including the following steps: Step 1, surface treatment of the inner wall of the pipe end. Grinding is carried out within a preset distance range on the inner wall of the pipe end of the gathering and transportation pipeline to expose the metal body of the pipe end inner wall, and a prefabricated groove 2 is formed on the inner wall 1 of the pipe end of the gathering and transportation pipeline. Its structural form refers to Figure 2 As shown; Step 2, preheating of the cermet powder. At the exposed position of the inner wall of the pipe end, that is, at the position of the formed prefabricated groove 2, a mixture of cermet powder is filled and preheated at a preset temperature; Step 3, prefabrication of the cermet layer. The cermet powder is evenly cladded on the inner wall of the pipe end of the gathering and transportation pipeline. The formed cermet layer refers to Figure 3 As shown. The cermet layer includes a corrosion-resistant alloy layer 31, a cermet transition layer 32, and a cermet corundum layer 33. After cooling, the corundum layer 33 and the transition layer 32 are removed to make the corrosion-resistant alloy layer 31 flush with the inner wall 1 of the steel pipe. The flush effect refers to Figure 4 As shown; The formed cermet layer can avoid the risk of electrochemical corrosion existing in the "lining" layer and the steel pipe due to mechanical bonding; Step 4, anti-corrosion and welding treatment of the gathering and transportation pipeline. Anti-corrosion treatment is carried out on other positions of the inner wall of the pipeline. After the anti-corrosion treatment, refer to Figure 5 As shown, the inner wall of the pipe end of the gathering and transportation pipeline remains with the corrosion-resistant alloy layer 31, and the other inner walls of the pipe remain with the anti-corrosion layer 4, and then on-site welding is carried out. The welding effect refers toFigure 6 As shown in the figure, butt welding is carried out at the bevel of the pipe end on site to form a weld 5, and the weld 5 is composed of a stainless steel weld 51 and a carbon steel weld 52; this method can solve the defects of low surfacing efficiency and high cost in surfacing a stainless steel layer on the inner wall of the pipeline.

[0021] A specific embodiment of a pre-patching method for small-diameter gathering and transportation pipelines in oil and gas fields is as follows Embodiment 1 (1) Surface treatment of the inner wall of the pipe end of the gathering and transportation pipeline: The inner wall of the pipe end with a specification of 114mm * 6 and a length of 10m is machined mechanically within a range of 10cm, ensuring a depth of 1mm, and there are no attachments such as dust and oil on the processed inner wall of the pipe end.

[0022] (2) Preheating of the cermet powder: 1) Fill the inner wall part of the steel pipe with cermet powder, and the cermet powder is composed of Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al. The Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al powder is 150 mesh, and each component accounts for 16.9%, 6.17%, 0.38%, 49.18%, and 27.3% respectively, and the powder quality is 650g; 2) Preheat the cermet powder at 105 °C for 1 hour.

[0023] (3) Prefabrication of the cermet layer: 1) Place the steel pipe on the centrifuge and start the centrifuge, with the centrifuge speed of 1600r / min; 2) Ignite the cermet powder, and the powder reacts at high temperature and is evenly clad on the inner wall of the pipe end of the steel pipe as the steel pipe rotates. The cermet layer is composed of a corundum layer, a transition layer, and a corrosion-resistant alloy layer. Among them, the thickness of the corundum layer is 3.0mm, the thickness of the transition layer is 0.5mm, and the thickness of the alloy layer is 1.0mm. By centrifugal self-propagating prefabrication of cermet on the inner wall of the pipeline and then machining to remove the corundum layer and the transition layer, it is avoided that the inner wall of the steel pipe is the corundum layer and the alloy layer in some cases; 3) After the cladding is completed, it is cooled, and after cooling, the inner wall of the pipe end of the steel pipe is machined to remove the corundum layer and the transition layer on the surface of the cermet, ensuring that the corrosion-resistant alloy layer of the cermet is flush with the inner wall of the steel pipe, and the thickness of the corrosion-resistant alloy layer is 1.0mm.

[0024] (4) The internal and external anti-corrosion steps of the gathering and transportation pipeline are determined according to the design requirements.

[0025] (5) The on-site welding steps and requirements of the pipeline shall be carried out in accordance with the provisions of GB / T 13148.

[0026] Example 2 (1) Inner wall surface treatment of the pipe end of the gathering and transportation pipeline: The inner wall of the pipe end with a specification of 89mm * 6 and a length of 10m is machined mechanically within a range of 10cm, ensuring a depth of 1.2mm. After treatment, there are no attachments such as dust and oil stains on the inner wall of the pipe end.

[0027] (2) Preheating of the cermet powder: 1) Fill the inner wall part of the steel pipe with cermet powder. The cermet powder consists of Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al. The Fe 2 O 3 , NiO, CrO 3 , TiO 2 , Al powder is 150 mesh, and each component accounts for 15.5%, 6%, 0.4%, 47%, and 26% respectively. The powder quality is 500g; 2) Preheat the cermet powder at 107°C for 1.5 hours.

[0028] (3) Prefabrication of the cermet layer: 1) Place the steel pipe on the centrifuge and start the centrifuge. The rotation speed of the centrifuge is 1500r / min; 2) Ignite the cermet powder. The powder reacts at high temperature and is evenly cladded on the inner wall of the pipe end of the steel pipe as the steel pipe rotates. The cermet layer consists of a corundum layer, a transition layer, and a corrosion-resistant alloy layer. Among them, the thickness of the corundum layer is 3.0mm, the thickness of the transition layer is 0.5mm, and the thickness of the corrosion-resistant alloy layer is 1.0mm; 3) After the cladding is completed, cool it. After cooling, machine the inner wall of the pipe end of the steel pipe to remove the corundum layer and the transition layer on the surface of the cermet, ensuring that the corrosion-resistant alloy layer of the cermet is flush with the inner wall of the steel pipe, and the thickness of the corrosion-resistant alloy layer is 1.0mm.

[0029] (4) The internal and external anti-corrosion steps of the gathering and transportation pipeline are determined according to the design requirements.

[0030] (5) The on-site welding steps and requirements of the pipeline shall be carried out in accordance with the provisions of GB / T 13148.

[0031] Performance tests were carried out on the pre-patching of the small-diameter pipelines prepared in the above Example 1 and Example 2, and the results are shown in Table 1.

[0032] Table 1 Referring to the test results in Table 1, it can be seen that the pre-compensated joints of small-diameter pipelines obtained by implementing the above embodiments of the pre-compensated joint method for small-diameter gathering and transportation pipelines in oil and gas fields have good corrosion resistance. They not only have good corrosion resistance to crude oil and oilfield sewage, but also have good corrosion resistance to corrosive substances such as acids and salts. It can be seen that the joint compensation method disclosed in this embodiment not only solves the technical problem of in-pipe joint compensation in the existing operation method for small-diameter gathering and transportation pipelines, but also does not require in-pipe joint compensation after welding.

[0033] In summary, the pre-compensated joint method for small-diameter gathering and transportation pipelines in oil and gas fields provided by the embodiments of the present invention solves the technical problem of in-pipe joint compensation in small-diameter gathering and transportation pipelines in oil and gas fields. First, a corrosion-resistant alloy layer with a certain width and thickness is cladded on the inner wall of the pipe end of the small-diameter pipeline. Then, after in-pipe anti-corrosion and on-site welding, the anti-corrosion function of the in-pipe joint compensation area is replaced by the corrosion-resistant alloy layer, realizing the continuity of the in-pipe anti-corrosion layer and eliminating the need for in-pipe joint compensation after welding. In this embodiment, the metallurgical fusion between the inner wall of the pipeline and the corrosion-resistant alloy layer is achieved through centrifugal self-propagating high-temperature synthesis, avoiding the risk of electrochemical corrosion existing in the "lining" layer and the steel pipe being mechanically combined as described in the patent with Chinese Patent Application No. 201120250876.3. In this embodiment, by centrifugally self-propagating and cladding a corrosion-resistant alloy layer on the inner wall of the pipeline, the defects of low surfacing efficiency and high cost in surfacing a stainless steel layer on the inner wall of the pipeline as described in the patents with Chinese Patent Application Nos. 201210514544.0 and 20150348243.9 are avoided. In this embodiment, after centrifugally self-propagating and prefabricating cermet on the inner wall of the pipeline, the corundum layer and the transition layer are removed by mechanical processing, avoiding the defects of difficult welding and low accuracy of weld non-destructive testing caused by the corundum layer and the alloy layer on the inner wall of the steel pipe as described in the patent with Chinese Patent Application No. 201210573393.6. The joint compensation method of this embodiment also provides a new idea and a new option for in-pipe joint compensation of small-diameter gathering and transportation pipelines in oil and gas fields.

[0034] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0035] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field, characterized in that: The following operations are included: Step 1: Surface treatment of the inner wall of the pipe end: grinding within the preset distance range of the pipe end of the gathering and transportation pipeline Processing to expose the metal body from the inner wall of the pipe end; Step 2: Preheat the metal ceramic powder and fill the metal ceramic mixture at the exposed position on the inner wall of the pipe end. The material powder is preheated at a preset temperature; Step 3: Prefabricate the metal-ceramic layer and evenly coat the metal-ceramic mixture powder on the gathering and transportation pipeline. The inner wall of the end, after cooling, remove the corundum layer and transition layer, so that the corrosion-resistant alloy layer is flush with the inner wall of the steel pipe; Step 4: Anti-corrosion and welding treatment of the gathering and transportation pipelines, and anti-corrosion treatment of other locations on the inner wall of the pipelines. Then weld on site.

2. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: In the step 1, the grinding range of the inner wall of the pipe end of the gathering and transportation pipeline is within 8-10 cm of the inner wall of the pipe end.

3. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: In the step 1, the depth of the exposed metal body on the inner wall of the pipe end is 0.5-1.5 mm.

4. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: In the step 2, the metal ceramic powder mixture includes Fe2O3, NiO, CrO3, TiO2, and Al.

5. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: The step three comprises the following sub-steps: 1) Place the gathering and transportation pipeline on the centrifuge, start the centrifuge, and rotate the steel pipe; 2) Ignite the metal ceramic powder, the powder reacts at high temperature, and the uniform cladding is achieved as the pipeline rotates On the inner wall of the pipeline end; 3) After the cladding is completed, the inner wall of the pipeline end is cooled and mechanically processed to remove Remove the corundum layer and transition layer on the surface of the metal ceramic, so that the corrosion-resistant alloy layer is flush with the inner wall of the steel pipe.

6. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: The particle size of the metal ceramic powder is 100-300 meshes, and the total mass of the powder is compatible with the pipe diameter and the required thickness of the metal ceramic layer.

7. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 4, characterized in that: The corresponding mass proportions of Fe2O3, NiO, CrO3, TiO2 and Al in the metal ceramic powder mixture are 15~17%, 5~8%, 0.3~0.5%, 45~50% and 25~29% respectively.

8. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 1, characterized in that: In the step 2, the preheating temperature is 100-110° C., and the preheating time is 1.0-1.5 hours.

9. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to claim 5, characterized in that: The rotation speed of the gathering and transportation pipeline is 1500~1700 r / min.

10. The method for pre-patching a small-diameter gathering and transportation pipeline in an oil and gas field according to any one of claims 1 to 9, characterized in that: In the step 4, the gathering and transportation pipeline welding is performed in accordance with the provisions of GB / T13148.

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