Sleeve structure and manufacturing method thereof

Abstract

The invention belongs to the technical field of oil well pipes, and discloses a casing pipe structure and a manufacturing method thereof.The casing pipe structure comprises a steel screen pipe, an aluminum alloy pipe, water swelling rubber and a steel coupling; the outer diameter of the aluminum alloy pipe is smaller than the inner diameter of the steel screen pipe, the inner diameter of the aluminum alloy pipe is larger than the outer diameter of the continuous pipe, the aluminum alloy pipe is located in the steel screen pipe, the steel screen pipe and the aluminum alloy pipe are coaxial, multiple pieces of water swelling rubber are arranged between the steel screen pipe and the aluminum alloy pipe, and the adjacent steel screen pipes are in threaded connection through steel couplings. The flammability of the aluminum alloy pipe under the low-temperature condition and the high bearing capacity characteristic of the steel screen pipe under the high-temperature condition are utilized, and in addition, the water swelling rubber wound on the inclined clamping groove is combined with the swelling deformation mode to form tight and reliable sealing; and the safety and reliability of the underground coal gasification channel are ensured while the requirements of the underground coal gasification process are met.

Description

Technical Field

[0001] The invention belongs to the technical field of oil well pipes, and in particular relates to a casing structure and a manufacturing method thereof. Background Art

[0002] Underground coal gasification refers to the chemical gasification technology that creates appropriate process conditions for deep coal in situ, conducts controlled combustion, and produces combustible gases such as hydrogen, carbon monoxide and methane through coal pyrolysis and a series of chemical reactions between coal, oxygen and water vapor. The underground coal gasification process requires that the outer casing of the horizontal section continuous pipe can form an oxygen channel after burning or melting at a temperature of 500℃ to 800℃, so that the oxygen coming out of the continuous pipe can directly enter the coal seam to promote continuous combustion. Since the casing and the internal continuous pipe annulus are water flow channels with a certain pressure, the casing needs to withstand a certain sealed internal pressure. In addition, the casing must withstand the extrusion force of the external coal seam to prevent the casing from deforming and jamming the continuous pipe. Common metal pipes and non-metallic pipes are difficult to meet the requirements of underground coal gasification technology. Combustible aluminum alloy pipes or magnesium alloy pipes have a greater safety risk in use due to their limited strength.

[0003] Therefore, it is necessary to provide a casing that meets the requirements of underground coal gasification technology, which can form an oxygen channel after burning or melting at a temperature of 500°C to 800°C, and at the same time the casing can withstand a certain sealing internal pressure and external extrusion force. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a casing that meets the requirements of underground coal gasification process, which can form an oxygen channel after burning or melting at a temperature of 500°C to 800°C, and the casing can withstand a certain sealing internal pressure and external extrusion force.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A casing structure, comprising a steel screen pipe, an aluminum alloy pipe, water-swellable rubber and a steel coupling;

[0007] The outer diameter of the aluminum alloy pipe is smaller than the inner diameter of the steel screen pipe, and the inner diameter of the aluminum alloy pipe is larger than the outer diameter of the continuous pipe. The aluminum alloy pipe is located inside the steel screen pipe, and the steel screen pipe is coaxial with the aluminum alloy pipe. A plurality of water-swellable rubbers are arranged between the steel screen pipe and the aluminum alloy pipe, and adjacent steel screen pipes are connected by steel coupling threads.

[0008] Optionally, the pipe wall of the steel screen pipe is provided with a plurality of holes, and the holes include round holes, square holes or slit elliptical holes.

[0009] Optionally, outer walls at both ends of the steel screen pipe are processed with external threads, and inner walls at both ends of the steel coupling are correspondingly processed with internal threads.

[0010] Optionally, both ends of the steel coupling are provided with anti-expansion shoulders and torque shoulders.

[0011] Optionally, the inner diameter of the steel screen pipe is 14 mm to 18 mm larger than the outer diameter of the aluminum alloy pipe.

[0012] Optionally, the outer diameter of the water-swellable rubber is 6 mm to 10 mm larger than the outer diameter of the aluminum alloy tube.

[0013] Optionally, a groove is provided at the connection between the aluminum alloy tube and the water-swellable rubber, and the water-swellable rubber is formed by wrapping a rubber sheet around the groove and bonding it.

[0014] Optionally, the bottom surface of the slot is inclined at an angle less than 8° with the central axis of the aluminum alloy tube, and the bottom surface of the slot is transitionally rounded to the two side surfaces.

[0015] In another aspect, the present invention discloses a method for manufacturing a sleeve structure, comprising:

[0016] Connect the steel screen pipe and the steel coupling through external threads and internal threads;

[0017] A groove is processed on the outer wall of the aluminum alloy tube, and water-swellable rubber is wound and bonded in the groove;

[0018] Install the aluminum alloy pipe bonded with water-swellable rubber into the steel screen pipe and align it;

[0019] The aluminum alloy pipe is expanded so that the outer surface of the aluminum alloy pipe and the water-swellable rubber are closely fitted to the inner surface of the steel screen pipe and form an interference fit, so that the inner surface of the aluminum alloy pipe is flush with the inner surface of the steel coupling, and the two ends of the aluminum alloy pipe are fitted with the anti-expansion shoulders of the steel coupling to obtain a casing structure.

[0020] Technical effects and advantages of the present invention:

[0021] The present invention designs a casing structure, which is composed of a steel screen pipe, an aluminum alloy pipe, water-swelling rubber and a steel coupling. The water-swelling rubber wrapped around the aluminum alloy pipe is combined with expansion deformation to form a tight and reliable seal. When the casing is at a temperature of 500°C to 800°C, the aluminum alloy pipe and the water-swelling rubber burn or melt, and the remaining steel screen pipe forms an oxygen channel. At this temperature, the steel screen pipe can withstand a certain sealing internal pressure and external extrusion force, thereby meeting the requirements of the underground coal gasification process.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of the casing structure of the present invention;

[0024] Figure 2 is a structural schematic diagram of a card slot;

[0025] Figure 3 The present invention is a flow chart of the method for manufacturing the sleeve structure.

[0026] Figure numerals: 1. steel screen pipe; 2. aluminum alloy pipe; 3. water-swellable rubber; 4. steel coupling; 5. eyelet; 6. external thread; 7. slot; 8. anti-expansion shoulder; 9. torque shoulder; 10. internal thread. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, the present invention provides a casing structure, comprising:

[0029] Steel screen pipe 1, aluminum alloy pipe 2, water-swellable rubber 3 and steel coupling 4;

[0030] The outer diameter of the aluminum alloy pipe 2 is smaller than the inner diameter of the steel screen pipe 1, and the inner diameter of the aluminum alloy pipe 2 is larger than the outer diameter of the continuous pipe. The aluminum alloy pipe 2 is located inside the steel screen pipe 1, and the steel screen pipe 1 is coaxial with the aluminum alloy pipe 2. A plurality of water-swellable rubbers 3 are arranged between the steel screen pipe 1 and the aluminum alloy pipe 2, and adjacent steel screen pipes 1 are threadedly connected by steel couplings 4.

[0031] In some embodiments of the present invention, a plurality of holes 5 are provided on the wall of the steel screen pipe 1, and the holes 5 include round holes, square holes or slit elliptical holes. After the aluminum alloy pipe 2 burns out, the oxygen in the casing can enter the coal outside the casing through the holes 5 to promote the continuous combustion of the coal.

[0032] In some embodiments of the present invention, the outer walls of both ends of the steel screen pipe 1 are processed with external threads 6, and the inner walls of both ends of the steel coupling 4 are correspondingly processed with internal threads 10, so as to facilitate the connection of multiple steel screen pipes 1 with each other.

[0033] In some embodiments of the present invention, anti-expansion shoulders 8 and torque shoulders 9 are provided at both ends of the steel coupling 4. After the pipe end of the aluminum alloy pipe 2 expands, it contacts the anti-expansion shoulders 8. The anti-expansion shoulders 8 can form a tight seal between the pipe end of the aluminum alloy pipe 2 and the steel coupling 4. After the steel coupling 4 and the steel screen pipe 1 are threadedly connected and buckled, the end face of the steel screen pipe 1 is pushed against the torque shoulder 9 to form a tight seal.

[0034] In some embodiments of the present invention, the inner diameter of the steel screen pipe 1 is 14 mm to 18 mm larger than the outer diameter of the aluminum alloy pipe 2 , so that the aluminum alloy pipe 2 can easily penetrate into the steel screen pipe 1 , and the outer surface of the aluminum alloy pipe 2 can fit the inner surface of the steel screen pipe 1 after expansion.

[0035] In some embodiments of the present invention, the outer diameter of the water-swellable rubber 3 is 6 mm to 10 mm larger than the outer diameter of the aluminum alloy tube 2 , so that the aluminum alloy tube 2 forms a certain contact pressure with the steel screen tube 1 after expansion.

[0036] In some embodiments of the present invention, Figure 2 As shown, a groove 7 is provided at the connection between the aluminum alloy tube 2 and the water-swellable rubber 3, and the water-swellable rubber 3 is formed by wrapping and bonding a rubber sheet around the groove 7, thereby preventing the water-swellable rubber 3 from sliding on the surface of the aluminum alloy tube 2 and affecting the sealing effect.

[0037] In some embodiments of the present invention, the bottom surface of the slot 7 is inclined at an angle less than 8° to the central axis of the aluminum alloy tube 2, and the bottom surface and the two side surfaces of the slot 7 are excessively rounded, thereby reducing stress concentration and preventing cracks from occurring in this portion of the aluminum alloy tube 2.

[0038] On the other hand, Figure 3 As shown, the present invention provides a method for manufacturing a casing structure, comprising:

[0039] Connect the steel screen pipe 1 and the steel coupling 4 through the external thread 6 and the internal thread 10;

[0040] A groove 7 is processed on the outer wall of the aluminum alloy tube 2, and a water-swellable rubber 3 is wound and bonded in the groove 7;

[0041] The aluminum alloy tube 2 bonded with the water-swellable rubber 3 is installed into the steel screen tube 1 and aligned;

[0042] The aluminum alloy tube 2 is expanded so that the outer surface of the aluminum alloy tube 2 and the water-swellable rubber 3 are tightly fitted to the inner surface of the steel screen tube 1 and form an interference fit, so that the inner surface of the aluminum alloy tube 2 is flush with the inner surface of the steel coupling 4, and the two ends of the aluminum alloy tube 2 are fitted with the anti-expansion shoulders 8 of the steel coupling 4 to obtain a casing structure.

[0043] In order to better illustrate the present invention, the following examples are provided.

[0044] Example

[0045] Two slits are processed on the stainless steel casing to divide the casing evenly into three parts to obtain the steel screen pipe 1, and then the steel screen pipe 1 and the steel coupling 4 are connected by buckling through the external thread 6 and the internal thread 10, and then the groove 7 is processed on the outer surface of the aluminum alloy pipe 2, and the water-swelling rubber 3 is wound and bonded in the groove 7, and then the aluminum alloy pipe 2 is installed in the steel screen pipe 1 and aligned, and then the aluminum alloy pipe 2 is expanded to make its outer surface and the water-swelling rubber 3 fit tightly to the inner surface of the steel screen pipe 1 and form an interference fit. After the expansion, the inner surface of the aluminum alloy pipe 2 is flush with the inner surface of the steel coupling 4, and the end is in contact with the anti-expansion shoulder 8. Finally, the inner surface of the casing is polished and smooth to obtain the casing structure.

[0046] During the use of the casing structure, an annulus is formed between the inner surface of the aluminum alloy tube 2 and the outer surface of the continuous tube as a water flow channel. The aluminum alloy tube 2 meets the sealing internal pressure condition of the water flow channel. When the casing structure is at a temperature of 500°C to 800°C, the aluminum alloy tube 2 and the water-swellable rubber 3 burn or melt and disappear, and the remaining steel screen tube 1 serves as an oxygen channel. The oxygen in the steel screen tube 1 enters the coal through the holes 5 to promote continuous combustion of the coal, and the outer surface of the steel screen tube 1 is subjected to the squeezing force of the external coal seam.

[0047] The casing structure of the present invention makes full use of the flammability of the aluminum alloy pipe 2 under low temperature conditions and the high load-bearing capacity of the steel screen pipe 1 under high temperature. In addition, the water-swellable rubber 3 wrapped around the inclined groove 7 is combined with the expansion deformation mode to form a tight and reliable seal, which meets the requirements of the underground coal gasification process while ensuring the safety and reliability of the underground coal gasification channel.

[0048] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A sleeve structure, characterized in that: The casing structure comprises a steel screen pipe (1), an aluminum alloy pipe (2), water-swellable rubber (3) and a steel coupling (4); The outer diameter of the aluminum alloy pipe (2) is smaller than the inner diameter of the steel screen pipe (1), and the inner diameter of the aluminum alloy pipe (2) is larger than the outer diameter of the continuous pipe. The aluminum alloy pipe (2) is located inside the steel screen pipe (1), and the steel screen pipe (1) is coaxial with the aluminum alloy pipe (2). A plurality of water-swellable rubbers (3) are arranged between the steel screen pipe (1) and the aluminum alloy pipe (2), and adjacent steel screen pipes (1) are threadedly connected via the steel coupling (4).

2. A sleeve structure according to claim 1, characterized in that: The pipe wall of the steel screen pipe (1) is provided with a plurality of holes (5), wherein the holes (5) include round holes, square holes or slotted elliptical holes.

3. A sleeve structure according to claim 2, characterized in that: The outer walls at both ends of the steel screen pipe (1) are processed with external threads (6), and the inner walls at both ends of the steel coupling (4) are correspondingly processed with internal threads (10).

4. A sleeve structure according to any one of claims 1 to 3, characterized in that: Anti-expansion shoulders (8) and torque shoulders (9) are provided at both ends of the steel coupling (4).

5. A sleeve structure according to claim 1, characterized in that: The inner diameter of the steel screen tube (1) is 14 mm to 18 mm larger than the outer diameter of the aluminum alloy tube (2).

6. A sleeve structure according to claim 5, characterized in that: The outer diameter of the water-swellable rubber (3) is 6 mm to 10 mm larger than the outer diameter of the aluminum alloy tube (2).

7. A sleeve structure according to claim 1, characterized in that: A clamping groove (7) is provided at the connection between the aluminum alloy tube (2) and the water-swellable rubber (3), and the water-swellable rubber (3) is formed by wrapping a rubber sheet around the clamping groove (7) and bonding it.

8. A sleeve structure according to claim 7, characterized in that: The bottom surface of the clamping groove (7) and the central axis of the aluminum alloy tube (2) form an inclination angle of less than 8°, and the bottom surface of the clamping groove (7) and the two side surfaces have rounded transitions.

9. A method for manufacturing a sleeve structure, characterized in that: include: Connecting the steel screen pipe (1) and the steel coupling (4) via an external thread (6) and an internal thread (10); A groove (7) is machined on the outer wall of the aluminum alloy tube (2), and a water-swellable rubber (3) is wound and bonded in the groove (7); The aluminum alloy tube (2) bonded with the water-swellable rubber (3) is installed into the steel screen tube (1) and aligned; The aluminum alloy tube (2) is expanded so that the outer surface of the aluminum alloy tube (2) and the water-swellable rubber (3) are tightly fitted to the inner surface of the steel screen tube (1) and form an interference fit, so that the inner surface of the aluminum alloy tube (2) is flush with the inner surface of the steel coupling (4), and the two ends of the aluminum alloy tube (2) are fitted with the anti-expansion shoulders (8) of the steel coupling (4) to obtain a casing structure.

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