A composite tubing for oil and gas well production and a method for processing the same

Abstract

The application provides a composite oil pipe for oil and gas well exploitation, which comprises a main pipe section, a male pin joint and a box joint arranged at two ends of the main pipe section respectively, an inner wrapping layer formed on an inner wall surface of the main pipe section, and an outer wrapping layer formed on an outer wall surface of the main pipe section, wherein the inner wrapping layer comprises a first inner composite layer, a second inner composite layer and a wear-resistant composite layer arranged on the inner wall of the main pipe section in sequence, the first composite layer is in contact with the inner wall surface of the main pipe section, and the outer wrapping layer comprises a first outer composite layer and a second outer composite layer arranged in sequence from inside to outside. The application further provides a processing method of the composite oil pipe for oil and gas well exploitation.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a composite tubing for oil and gas well extraction. This invention also relates to a method for processing the composite tubing for oil and gas well extraction. Background Technology

[0002] In existing oil and gas well development and actual oilfield production, the flow transmission method generally uses polished tubing strings. This involves connecting multiple metal tubing strings with threads to form a polished rod. The ordinary tubing used is typically steel, which has poor insulation and is prone to surface corrosion and flaking during long-term downhole operation. In severe cases, this can cause downhole blockage, especially in heavy oil extraction where high-temperature fluids need to be injected downhole to aid in production. Therefore, ordinary tubing cannot operate long-term in this environment; it is easily clogged and prone to wear during installation, further threatening its service life.

[0003] In existing technologies, specialized hollow-walled insulated tubing is used for heating operations in certain well conditions. For example, Chinese patent document CN201811608884.3, entitled "A Small-Diameter Seamless High-Pressure Stainless Steel Tubing," discloses a small-diameter seamless high-pressure stainless steel tubing, including a tubing body and connectors. The connectors are located at both ends of the tubing body. The tubing body comprises, from the inside out, an inner layer, a middle layer, an outer layer, and a protective layer, all coaxially arranged. However, this type of tubing has a high manufacturing cost, and due to its hollow-wall design, its structural dimensions are large, resulting in a smaller flow channel area and a limited range of applications. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a composite tubing for oil and gas well development. This composite tubing is adaptable to heavy oil well conditions, enhances corrosion and wax resistance, and has good heat insulation properties, thereby significantly extending the service life of the composite tubing.

[0005] The present invention also proposes a method for processing composite tubing for oil and gas well extraction.

[0006] Therefore, according to a first aspect of the present invention, a composite tubing for oil and gas well production is provided, comprising: a main pipe section, wherein male and female threaded joints are respectively provided at both ends of the main pipe section; an inner sheathing layer formed on the inner wall surface of the main pipe section; and an outer sheathing layer formed on the outer wall surface of the main pipe section; wherein the inner sheathing layer comprises a first inner composite layer, a second inner composite layer and a wear-resistant composite layer sequentially disposed on the inner wall of the main pipe section, the first composite layer being in contact with the inner wall surface of the main pipe section, and the outer sheathing layer comprises a first outer composite layer and a second outer composite layer sequentially disposed from the inside out.

[0007] In one embodiment, the first inner composite layer and the first outer composite layer are both made of PE material, and the second inner composite layer and the second outer composite layer are both made of POK material.

[0008] In one embodiment, the thickness of the inner wrapping layer is 5-6 mm, wherein the thickness of the first inner composite layer is 1.2-1.5 mm, and the thickness of the composite wear-resistant layer is 1.0-2.0 mm.

[0009] In one embodiment, the thickness of the first outer composite layer is 3-4 mm, and the thickness of the second outer composite layer is 2-3 mm.

[0010] In one embodiment, the composite wear-resistant layer comprises a stainless steel mesh coated with a wear-resistant material, the wear-resistant material comprising one or more of chromium carbide, tungsten carbide, manganese oxide, and molybdenum disulfide.

[0011] According to a second aspect of the present invention, a method for processing a composite tubing for oil and gas well production as described above is provided, comprising the following steps:

[0012] Select a metal oil pipe and grind it. Then, process the male threaded connector and the female threaded connector at both ends of the metal oil pipe respectively.

[0013] The inner and outer walls of the metal oil pipe are processed respectively, so that the inner and outer walls of the metal oil pipe form an internal friction surface and an external friction surface respectively;

[0014] The inner wrapping layer is formed on the inner wall surface of the metal oil pipe;

[0015] The outer coating layer is formed on the outer wall surface of the metal oil pipe.

[0016] In one embodiment, the friction surface is a mesh-like or corrugated surface.

[0017] In one embodiment, during the processing of the inner coating layer, the first inner composite layer and the second inner composite layer are first extruded and attached to the internal friction surface, and then the composite wear-resistant layer is bonded to the inner wall surface of the second inner composite layer.

[0018] One end of the second inner composite layer is flanged to cover the first end face of the main pipe section, and the other end extends axially to a range of 1-2 cm on the female buckle.

[0019] In one embodiment, the bonding of the composite wear-resistant layer includes the following sub-steps:

[0020] Provide a metal mesh and fabricate the metal mesh into a mesh structure that can interfere with the inner diameter of the second inner composite layer;

[0021] The metal mesh is sintered into a thin film structure and pressed into a crescent shape before being inserted into the metal oil pipe;

[0022] A metal gauge is inserted into one end of the metal oil pipe to stretch the metal mesh and press it against the inner wall of the metal oil pipe, thereby forming the wear-resistant composite layer.

[0023] In one embodiment, during the processing of the outer wrapping layer, the first outer composite layer and the second outer composite layer are simultaneously extruded and attached to the outer friction surface. One end of the second outer composite layer is flanged to cover the second end face of the main pipe section, and the other end extends axially to the stepped end face of the male coupling and is flanged to cover the stepped end face.

[0024] Compared with the prior art, the advantages of this application are:

[0025] The composite tubing for oil and gas well production according to the present invention is adaptable to heavy oil well conditions. By providing inner and outer wrapping layers on the inner and outer walls of the main pipe section, the composite tubing meets downhole insulation requirements, significantly enhancing its corrosion and wax resistance, thermal insulation performance, and wear resistance, thereby greatly extending its service life. The inner and outer wrapping layers effectively cover the inner and outer surfaces of the main pipe section, enabling the composite tubing to meet downhole performance requirements. Furthermore, this composite tubing has a simple structure, is easy to manufacture, and has low production costs. Attached Figure Description

[0026] The present invention will now be described with reference to the accompanying drawings.

[0027] Figure 1 The structure of the composite tubing for oil and gas well production according to the present invention is schematically shown.

[0028] Figure 2 schematically shown Figure 1The structure of the inner sheath of the composite tubing.

[0029] Figure 3 schematically shown Figure 1 The structure of the outer sheath of the composite oil pipe.

[0030] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0031] The invention will now be described with reference to the accompanying drawings.

[0032] Figure 1 The structure of a composite tubing 100 for oil and gas well production according to the present invention is schematically shown. Figure 1 As shown, the composite tubing 100 includes a main pipe section 1, with a male threaded connector 2 and a female threaded connector 3 at both ends of the main pipe section 1. The two ends of the main pipe section 1 are connected to the upper tubing string and the lower tubing string (not shown) respectively through the male threaded connector 2 and the female threaded connector 3, thereby forming a complete set of downhole tubing.

[0033] In one embodiment, the male connector 2 is configured as an external threaded connector, and the female connector 3 is configured as an internal threaded connector.

[0034] According to the present invention, an inner wrapping layer 4 is provided on the inner wall surface of the main pipe section 1, extending to the axial inner end of the female threaded connector 3. Simultaneously, an outer wrapping layer 5 is provided on the outer wall surface of the main pipe section 1, extending to the axial inner end of the male threaded connector 2. This structure of the composite oil pipe 100 significantly improves its corrosion resistance and thermal insulation performance, and greatly extends its service life.

[0035] According to the present invention, the inner cladding layer 4 is formed on the inner wall surface of the main pipe section 1. For example... Figure 2 As shown, the inner cladding layer 4 includes a first inner composite layer 41, a second inner composite layer 42, and a wear-resistant composite layer 43 sequentially disposed on the inner wall of the main pipe section 1. The first composite layer 41 is in contact with the inner wall surface of the main pipe section 1. In one embodiment, the first inner composite layer 41 is made of PE material, and the second inner composite layer is made of POK material.

[0036] The thickness of the inner wrapping layer 4 is set to be in the range of 5-6 mm. The thickness of the first inner composite layer 41 is set to be in the range of 1.2-1.5 mm, and the thickness of the composite wear-resistant layer 43 is set to be in the range of 1.0-2.0 mm.

[0037] According to the present invention, the composite wear-resistant layer 43 comprises a stainless steel mesh coated with a wear-resistant material. The wear-resistant material includes one or more of chromium carbide, tungsten carbide, manganese oxide, and molybdenum disulfide.

[0038] During the processing of the inner coating layer 4, the main influencing factor on its thickness is the thickness of the composite wear-resistant layer 43. Different metal compositions of the composite wear-resistant layer 43 result in different thicknesses, which in turn affect the thicknesses of the first inner composite layer 41 and the second inner composite layer 42. The stainless steel mesh of the composite wear-resistant layer 43 serves as a reference mesh, and other wear-resistant materials are coated onto the stainless steel mesh to form the composite wear-resistant layer 43.

[0039] The composite wear-resistant layer 43 will be described below with reference to a specific embodiment.

[0040] In one embodiment, when the thickness of the composite wear-resistant layer 43 is set to 1 mm, the composition of the composite wear-resistant layer 43 includes chromium carbide and tungsten carbide, and the chromium carbide and tungsten carbide are mixed evenly in a ratio of 1:2.2, and then attached to the stainless steel mesh to form a composite wear-resistant layer.

[0041] In one embodiment, when the thickness of the composite wear-resistant layer 43 is set to 1.4 mm, the composition of the composite wear-resistant layer 43 includes chromium carbide and tungsten carbide, and the chromium carbide and tungsten carbide are mixed evenly in a ratio of 1.3:2, and then attached to the stainless steel mesh to form a composite wear-resistant layer.

[0042] In one embodiment, when the thickness of the composite wear-resistant layer 43 is set to 2 mm, the composition of the composite wear-resistant layer 43 includes chromium carbide and tungsten carbide, and the chromium carbide and tungsten carbide are mixed evenly in a ratio of 0.8:1, and then attached to the stainless steel mesh to form a composite wear-resistant layer.

[0043] According to the present invention, the outer wrapping layer 5 is formed on the outer wall surface of the main pipe section 1. For example... Figure 3 As shown, the outer wrapping layer 5 includes a first outer composite layer 51 and a second outer composite layer 52 arranged sequentially from the inside to the outside. In one embodiment, the first outer composite layer 51 is made of PE material, and the second outer composite layer 52 is made of POK material.

[0044] The thickness of the first outer composite layer 51 is 3-4 mm, and the thickness of the second outer composite layer 52 is 2-3 mm.

[0045] According to the present invention, a method for processing composite tubing for oil and gas well production is also proposed. The processing method of the composite tubing is described in detail below.

[0046] First, select a metal oil pipe and grind it. Then, process male thread connector 2 and female thread connector 3 at both ends of the metal oil pipe.

[0047] In this embodiment, a metal pipe matching the tubing size is selected and cut to the required tubing length to form the metal tubing to be processed. In one embodiment, the tubing length is 7.32m. Then, the metal tubing is ground to ensure flat cross-sections at both ends, and male threaded connectors 2 and female threaded connectors 3 are machined at both ends of the metal tubing. Preferably, male threaded sections and female threaded sections are machined at both ends of the metal tubing.

[0048] Subsequently, the inner and outer walls of the metal oil pipe are processed separately to form an inner friction surface and an outer friction surface, respectively. Preferably, the friction surface can be a mesh-like or corrugated surface.

[0049] Subsequently, an inner wrapping layer 4 is formed on the inner wall of the metal oil pipe.

[0050] During the processing of the inner coating layer 4, the first inner composite layer 41 and the second inner composite layer 42 are first extruded and formed simultaneously, and then attached to the inner friction surface of the metal oil pipe. Then, the composite wear-resistant layer 43 is bonded to the inner wall surface of the second inner composite layer 42. Thus, the inner coating layer 4 is formed.

[0051] To ensure the corrosion resistance of the inner wall of the composite oil pipe 100, one end of the second inner composite layer 42 can be flanged to cover the first end face of the main pipe section 1. Figure 1 The upper end of the second inner composite layer 42 extends axially to a range of 1-2 cm on the female connector 3. The second inner composite layer 42 has good wear resistance and impact resistance.

[0052] Of course, it is understandable that the first inner composite layer 41, the second inner composite layer 42, and the wear-resistant composite layer 43 in the inner wrapping layer 4 can all be configured with one end flanged to cover the first end face of the main pipe section 1. Figure 1 The upper end of the male connector is extended axially to a range of 1-2 cm on the female connector 3.

[0053] According to the present invention, in the process of bonding the composite wear-resistant layer 43, firstly, a metal mesh is provided and fabricated into a mesh structure capable of forming an interference fit with the second inner composite layer 42. The metal mesh can be, for example, stainless steel mesh. Then, a wear-resistant material is coated onto the metal mesh. Next, the metal mesh is sintered into a thin film structure, the total length of which is slightly greater than the length of the inner side of the main pipe section 1 of the composite oil pipe 100 excluding the length of the female threaded connector 3. Then, the metal mesh is pressed into a crescent shape and inserted into the metal oil pipe. After the metal mesh is inserted into place, the entire thin film structure is inserted into the metal oil pipe, with a small amount protruding from the male threaded connector end and a small amount protruding from the bottom of the female threaded connector end. Then, a metal gauge is inserted from one end of the metal oil pipe, and the recessed portion inside the metal mesh is flattened by the metal gauge. The metal mesh is then pressed against the inner wall of the metal oil pipe by its own elasticity and the clamping force of the interference fit, thus fixing the metal mesh. In this way, the wear-resistant composite layer 43 is formed.

[0054] In this embodiment, after the metal gauge presses the composite wear-resistant layer 43 tightly, the excess at both ends of the composite wear-resistant layer 43 is bent outward so that it can cover the end face of the male connector 2 and the bottom end face of the female connector 3.

[0055] Subsequently, an inner coating layer 5 is formed on the outer wall of the metal oil pipe. During the processing of the outer coating layer 5, the first outer composite layer 51 and the second outer composite layer 42 are simultaneously extruded and attached to the outer friction surface.

[0056] To ensure the corrosion resistance of the outer wall of the composite tubing 100, one end of the second outer composite layer 52 is flanged to cover the second end face of the main pipe section 1. Figure 1 The lower end of the second outer composite layer 52 extends to the stepped end face 21 of the male threaded connector 2, and is flanged to cover the stepped end face 21 of the male threaded connector 2. Thus, the processing of the composite oil pipe 100 is completed.

[0057] The composite tubing 100 for oil and gas well production according to the present invention is adaptable to heavy oil well conditions. By providing an inner wrapping layer 4 and an outer wrapping layer 5 on the inner and outer walls of the main pipe section 1 respectively, the composite tubing 100 meets the downhole insulation requirements, significantly enhancing its corrosion and wax resistance, heat insulation performance, and wear resistance, thereby greatly extending its service life. According to the processing method of the present invention, the inner wrapping layer 4 and the outer wrapping layer 5 effectively cover the inner and outer surfaces of the main pipe section 1, enabling the composite tubing 100 to meet downhole performance requirements. Furthermore, the composite tubing 100 has a simple structure, is easy to manufacture, and has low production costs.

[0058] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0059] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite tubing for oil and gas well production, comprising: The main pipe section (1) is provided with a male fastener (2) and a female fastener (3) at both ends. An inner cladding layer (4) formed on the inner wall surface of the main pipe section; and An outer wrapping layer (5) is formed on the outer wall surface of the main pipe section; The inner wrapping layer includes a first inner composite layer (41), a second inner composite layer (42) and a composite wear-resistant layer (43) sequentially disposed on the inner wall of the main pipe section. The first inner composite layer is in contact with the inner wall surface of the main pipe section. The outer wrapping layer includes a first outer composite layer (51) and a second outer composite layer (52) sequentially disposed from the inside to the outside. The composite wear-resistant layer includes a metal mesh and a wear-resistant material coated on the metal mesh. The metal mesh is interference-fitted with the second inner composite layer. Both ends of the composite wear-resistant layer are bent outward to cover the end face of the male connector and the bottom end face of the female connector. The first inner composite layer and the first outer composite layer are both made of PE material, and the second inner composite layer and the second outer composite layer are both made of POK material.

2. The composite oil pipe according to claim 1, characterized in that, The thickness of the inner wrapping layer is 5-6 mm. The thickness of the first inner composite layer is 1.2-1.5 mm, and the thickness of the composite wear-resistant layer is 1.0-2.0 mm.

3. The composite tubing according to claim 1 or 2, characterized in that, The thickness of the first outer composite layer is 3-4 mm, and the thickness of the second outer composite layer is 2-3 mm.

4. The composite tubing according to claim 1 or 2, characterized in that, The composite wear-resistant layer includes a stainless steel mesh coated with a wear-resistant material, which includes one or more of chromium carbide, tungsten carbide, manganese oxide, and molybdenum disulfide.

5. A method for processing a composite tubing for oil and gas well production according to any one of claims 1 to 4, comprising the following steps: Select a metal oil pipe and grind it. Then, process the male threaded connector and the female threaded connector at both ends of the metal oil pipe respectively. The inner and outer walls of the metal oil pipe are processed respectively, so that the inner and outer walls of the metal oil pipe form an internal friction surface and an external friction surface respectively; The inner wrapping layer is formed on the inner wall surface of the metal oil pipe; The outer coating layer is formed on the outer wall surface of the metal oil pipe.

6. The processing method according to claim 5, characterized in that, The friction surface is a grid-like or corrugated surface.

7. The processing method according to claim 5, characterized in that, In the process of processing the inner coating layer, the first inner composite layer and the second inner composite layer are first extruded and formed simultaneously and attached to the inner friction surface. Then, the composite wear-resistant layer is bonded to the inner wall surface of the second inner composite layer. One end of the second inner composite layer is flanged to cover the first end face of the main pipe section, and the other end extends axially to a range of 1-2 cm on the female buckle.

8. The processing method according to claim 7, characterized in that, The bonding of the composite wear-resistant layer includes the following sub-steps: Provide a metal mesh and fabricate the metal mesh into a mesh structure that can interfere with the inner diameter of the second inner composite layer; The metal mesh is sintered into a thin film structure and pressed into a crescent shape before being inserted into the metal oil pipe; A metal gauge is inserted into one end of the metal oil pipe to stretch the metal mesh and press it against the inner wall of the metal oil pipe, thereby forming the composite wear-resistant layer.

9. The processing method according to claim 5, characterized in that, In the step of processing the outer coating layer, the first outer composite layer and the second outer composite layer are simultaneously extruded and attached to the outer friction surface. One end of the second outer composite layer is flanged to cover the second end face of the main pipe section, and the other end extends axially to the stepped end face (21) of the male connector and is flanged to cover the stepped end face.

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