Plug cone type fusible tube and machining method

Abstract

The invention belongs to the technical field of coal bed gasification drilling and completion, and discloses a plug cone type fusible tube and a machining method.The plug cone type fusible tube comprises a supporting tube and a combustible plug cone, and a plurality of mounting holes are formed in the supporting tube; the combustible plug cones are inserted into the mounting holes in a one-to-one correspondence mode and fixedly connected with the supporting pipe, and the combustible plug cones are made of fusible alloy or fusible nonmetal. According to the plug cone type fusible tube, a coal seam can be effectively ignited after the combustible plug cone is combusted at high temperature, meanwhile, the supporting tube can prevent the coal seam from collapsing, it is guaranteed that an igniter safely withdraws, it is guaranteed that a gas channel is smooth after combustion, and the manufacturing cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of coal bed gasification drilling and completion, and in particular to a plug cone type fusible pipe and a processing method thereof. Background Art

[0002] Underground coal gasification technology (UCG) is a new clean energy technology that produces coal gas and other gases by burning coal in a controlled manner underground without mining. This technology has the advantages of ensuring safety, reducing manpower, reducing pollution, and increasing mining rates, and has become a hot topic in coal research at home and abroad. Underground coal seam gasification involves ignition and continuous combustion of coal seams. In China, ignition is ignited by injecting combustibles. After a gasification cycle is completed, the gas injection point needs to be withdrawn to form a new gasification cycle, which is the controlled retreat injection process (CRIP). The combustion of this process is uncontrollable, and the coal seam may collapse, making it impossible for the gas injection and ignition devices to be withdrawn smoothly through the casing.

[0003] Related technologies propose a completion fusible composite casing for underground coal gasification development, which puts a combustible pipe and a support pipe together. The combustible pipe is made of a combustible alloy material, and a plurality of holes are opened on the support pipe to ensure that the flames generated by the igniter and the combustible pipe can smoothly pass through the support pipe and reach the coal seam, thereby achieving ignition smoothly. The support pipe still has sufficient strength and anti-extrusion performance to resist coal seam collapse.

[0004] The above-mentioned fusible composite casing uses a large amount of combustible alloy materials to manufacture the combustible tube, and the manufacturing cost is high. The inner hole of the same specification is small, which is not conducive to the retreat of the igniter. At the same time, the annulus between the igniter pipe string and the fusible composite casing is small, which is not conducive to the injection of related gases such as oxygen and nitrogen. Summary of the invention

[0005] One of the purposes of the present invention is to provide a plug-cone fusible tube, which can reduce the amount of combustible materials used and reduce manufacturing costs, while facilitating the safe and reliable retreat of the igniter and being more conducive to the injection of related gases such as oxygen and nitrogen.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A plug-cone type fusible tube comprises a support tube and a flammable plug cone. The support tube is provided with a plurality of mounting holes. The flammable plug cones are inserted into the mounting holes one by one and fixedly connected to the support tube. The flammable plug cones are made of fusible alloy or fusible non-metal.

[0008] Preferably, the inner and outer end surfaces of the combustible plug cone are flush with the inner and outer walls of the support tube respectively.

[0009] Preferably, it also includes a joint, which includes a main body and a second connecting part, two sections of the second connecting part are respectively arranged at the axial ends of the main body and have the same inner diameter as the inner diameter of the main body, the support tube includes a support part and a first connecting part, the mounting hole is opened on the support part, the inner diameter of the support part is the same as the inner diameter of the main body, the first connecting part is arranged at one axial end of the support part, and the second connecting part is inserted into the first connecting part and screwed to the first connecting part.

[0010] Preferably, the mounting hole is a threaded hole.

[0011] Preferably, the flammable plug cone is threaded, injection-molded or bonded to the support tube.

[0012] Another object of the present invention is to provide a method for processing a plug cone type fusible tube, which is used to process the above-mentioned flammable plug cone type fusible tube, and mainly comprises the following steps:

[0013] Processing mounting holes on the tubular blank;

[0014] Processing of a flammable plug cone is performed, and the flammable plug cone is assembled into the mounting hole.

[0015] Another object of the present invention is to provide a processing method for a plug-cone type fusible tube which is different from the above processing method, and mainly comprises the following steps:

[0016] Processing mounting holes on the tubular blank;

[0017] A liner is sleeved inside the tubular blank, and an outer tube with injection holes is sleeved outside. The injection holes correspond to the mounting holes one by one, and fusible non-metal casting is injected into the mounting holes through the injection holes to form a combustible plug cone.

[0018] Preferably, the liner tube, the tubular blank and the outer tube are positioned using positioning pieces before casting and forming the combustible plug cone.

[0019] Preferably, after the combustible plug cone is fixedly connected to the tubular blank, the inner and outer portions of the combustible plug cone that protrude from the inner and outer walls of the tubular blank are removed.

[0020] Preferably, after the flammable plug cone is fixedly connected to the tubular blank, the tubular blank is pressure tested to ensure that the pressure resistance of the finally formed plug cone type fusible tube meets the requirements.

[0021] Beneficial effects of the present invention: In the present invention, the support tube in the plug-cone type fusible tube can prevent the coal seam from collapsing and ensure that the gas channel for coal gas discharge is connected, and the combustible plug cone is inserted into the mounting hole on the support tube. The combustible plug cone melts quickly at high temperature, and the coal seams inside and outside the tube are connected. The flame generated by the combustible plug cone can quickly reach the coal seam to ensure smooth ignition. Compared with making low-temperature fusible metal or low-temperature fusible non-metal into a tubular structure coaxial with the support tube, less material is used, the manufacturing cost is reduced, and it is conducive to the injection of related gases such as oxygen and nitrogen, thereby improving the ignition effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 2 is a schematic diagram of the structure of a plug-cone type fusible tube in an embodiment of the present invention;

[0023] Figure 2 Schematic diagram of one distribution mode of mounting holes on a support tube in an embodiment of the present invention;

[0024] Figure 3 is a schematic diagram of another distribution mode of the mounting holes on the support tube in an embodiment of the present invention;

[0025] Figure 4 This is a process flow chart of the plug-cone type fusible tube processing in an embodiment of the present invention;

[0026] Figure 5 It is a structural schematic diagram of the processing process of the plug-cone type fusible tube in one embodiment of the present invention;

[0027] Figure 6 It is a structural schematic diagram of the processing process of a plug-cone type fusible tube in another embodiment of the present invention;

[0028] Figure 7 yes Figure 6 The enlarged schematic diagram at A in the middle;

[0029] Figure 8 Schematic diagram of the working state of the plug-cone fusible tube in the embodiment of the present invention.

[0030] In the figure:

[0031] 1. Support tube; 11. Support part; 111. Mounting hole; 12. First connecting part; 2. Combustible plug cone; 3. Joint; 31. Main body; 32. Second connecting part; 4. Liner; 41. Air vent; 5. Outer tube; 51. Injection hole; 6. Positioning piece; 7. Injection port; 8. Igniter; 9. Well section. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0033] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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 mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0035] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0036] Embodiment 1:

[0037] Figure 1-Figure 3 What is shown is the plug-cone type fusible tube proposed in this embodiment, which includes a support tube 1 and a combustible plug cone 2, wherein the support tube 1 is made of a high-temperature resistant and high-strength steel tube, and a plurality of mounting holes 111 are opened through the surface of the support tube 1, and the combustible plug cone 2 is made of a low-temperature fusible metal or a low-temperature fusible non-metallic material including but not limited to magnesium alloy, aluminum alloy, high-strength plastic, etc., and the fusible alloy has strong corrosion resistance in the presence of water, oxygen, methane and other media and at a temperature below 150°C, and begins to melt above 500°C, and a plurality of combustible plug cones 2 are inserted into the mounting holes 111 one by one and fixedly connected to the support tube 1.

[0038] The support tube 1 used in the above-mentioned plug cone type fusible tube is resistant to high temperature and has high strength. When the combustible plug cone 2 ignites the coal seam, it can prevent the coal seam from collapsing, ensuring that the gas channel for coal gas discharge is unobstructed, and the combustible plug cone 2 is inserted in the mounting hole 111 on the support tube 1. The combustible plug cone 2 melts quickly at high temperature, and the coal seams inside and outside the tube are connected. The flame generated by the combustible plug cone 2 can quickly reach the coal seam, ensuring the smooth ignition. Compared with making low-temperature fusible metal or low-temperature fusible non-metal into a tubular structure coaxial with the support tube 1, the combustible plug cone 2 is inserted in the mounting hole 111 and uses less material, thereby reducing the manufacturing cost.

[0039] The combustible plug cone 2 is ignited by the igniter 8, and the igniter 8 is used in conjunction with the injection tube (continuous oil pipe) inserted into the support tube 1. The injection tube can inject an oxidant into the support tube 1. After the combustible plug cone 2 is ignited, the igniter 8 and the injection tube need to be withdrawn. In order to avoid interference, the support tube 1 is configured to be a hollow cylinder, and the first end face of the combustible plug cone 2 inserted into the support tube 1 is flush with the inner wall of the support tube 1; and in order to allow the support tube 1 to be smoothly inserted into the well, the second end face of the combustible plug cone 2 facing the outside of the support tube 1 remains flush with the inner wall of the support tube 1.

[0040] In this embodiment, the flammable plug cone 2 is connected to the support tube 1 by means including but not limited to screw connection, bonding, etc. In order to improve the stability of the connection between the flammable plug cone 2 and the support tube 1, an internal thread is provided in the mounting hole 111, and the flammable plug cone 2 can be connected to the support tube 1 by screw connection or injection molding.

[0041] Optionally, the plurality of mounting holes 111 are distributed in an array or spiral on the support tube 1, or in any other form, which is not specifically limited in this embodiment. The mounting holes 111 themselves can be set to regular or irregular shapes such as round, square, oval, etc., and the shape of the combustible plug cone 2 matches the mounting holes 111.

[0042] For example, the mounting hole 111 is set as a circular step hole, and the combustible plug cone 2 includes a large diameter section and a small diameter section, wherein the small diameter section faces the inside of the support tube 1 for contacting the igniter 8, and the large diameter section faces the outside of the support tube 1 for contacting the coal seam. While ensuring that the contact area between the combustible plug cone 2 and the coal seam remains unchanged, the combustible plug cone 2 with a variable diameter setting can further reduce the amount of material used to manufacture the combustible plug cone 2.

[0043] In order to achieve effective connection with other pipe sections, a joint 3 is further provided at at least one end of the plug-cone fusible pipe, and the joint 3 is connected to the support pipe 1 through an airtight thread. It can be understood that other pipe sections include but are not limited to another section of the plug-cone fusible pipe. The connection of multiple sections of the plug-cone fusible pipe can meet the construction requirements of the long well section 9 of underground coal gasification. Optionally, the support pipe 1 includes a support portion 11 and a first connecting portion 12, and the mounting hole 111 is provided in the support portion 11. The first connecting portion 12 is provided with two sections, which are respectively connected to the two axial ends of the support portion 11. The inner wall of the first connecting portion 12 is set to a truncated cone shape, which gradually narrows from one axial end to the other end to the same inner diameter as the support portion 11, and the inner wall of the first connecting portion 12 is provided with an internal thread; the joint 3 includes a main body portion 31 and a second connecting portion 32, wherein the inner and outer diameters of the main body portion 31 are the same as the inner and outer diameters of the support portion 11. Similarly, the second connection part 32 is also provided with two sections, which are respectively connected to the axial ends of the main body part 31. The outer wall of the second connection part 32 is set to a truncated cone shape, gradually expanding from one axial end surface to the other end. The outer wall of the second connection part 32 is provided with an external thread matching the internal thread of the first connection part 12. The second connection part 32 can be inserted into the first connection part 12 to realize the threaded connection between the support tube 1 and the joint 3, and the inner diameter of the overall structure formed by the plug-in support tube 1 and the joint 3 is unified, which can ensure the safe and effective withdrawal of the igniter 8.

[0044] Embodiment 2

[0045] Figure 4-Figure 5 The present invention shows a processing method of a plug cone type fusible tube proposed in this embodiment, which is used to process the above plug cone type fusible tube. The processing method mainly includes the following steps:

[0046] S1. According to the size of the well section 9, a high-temperature and high-strength steel pipe of suitable specifications is selected as a tubular blank, and a plurality of holes are processed on the tubular blank, namely, mounting holes 111. The shape and distribution of the mounting holes 111 are not specifically limited, and can be circular holes, square holes distributed in an array, or circular holes, square holes distributed in a spiral, etc.

[0047] S2, select materials, process the combustible plug cone 2, and assemble the combustible plug cone 2 into the mounting hole 111. If the mounting hole 111 is a non-circular hole, the combustible plug cone 2 and the tubular blank can be bonded together. If the mounting hole 111 is a circular hole, the combustible plug cone 2 and the tubular blank can be screwed together. Of course, they can also be bonded together, and there is no specific limitation here. The material used to process the combustible plug cone 2 is selected from low-temperature fusible metal or low-temperature fusible non-metallic material.

[0048] S3, after the combustible plug cone 2 is assembled to the mounting hole 111, the first pressure test is carried out. This pressure test is an external pressure test. During the test, the two ends of the entire tubular blank are sealed and placed in a sealed container. Water, oil, gas and other media are poured into the sealed container to observe the pressure resistance. If the pressure resistance does not meet the requirements, return to S2 and select different materials to re-process the combustible plug cone 2; if the pressure resistance meets the requirements, continue to process the surface of the combustible plug cone 2, remove the parts of the combustible plug cone 2 that protrude from the inner and outer walls of the tubular blank, so that the end faces of the combustible plug cone 2 at both ends are flush with the inner and outer walls of the tubular blank, and then proceed to the next step.

[0049] S4, process the internal thread at the end of the tubular blank, the support tube 1 is formed, and then the second pressure test is carried out. This pressure test is an internal and external pressure test. During the test, the external pressure test and the internal pressure test are carried out respectively. The external pressure test is the same as the first pressure test. The internal pressure test is to seal both ends of the entire support tube 1 and pass water, oil, gas and other media into the support tube 1 to observe the pressure resistance. If the pressure resistance does not meet the requirements, return to S2, select different materials to re-process the combustible plug cone 2, and if the pressure resistance meets the requirements, proceed to the next step.

[0050] S5, processing the joint 3, connecting the joint 3 to the support pipe 1, realizing the assembly, and completing the processing.

[0051] S6, conduct indoor combustion simulation test, if qualified, then batch production; if unqualified, then repeat step S1, and adjust the size and distribution density of the mesh in step S2.

[0052] Embodiment 3

[0053] Figure 4 , Figure 6 and Figure 7 Another method for processing a plug-cone type fusible tube proposed in this embodiment is shown, which is also used to process the plug-cone type fusible tube in the first embodiment. The processing method specifically includes the following steps:

[0054] S1. According to the size of the well, a high-temperature and high-strength tubular blank of suitable specifications is selected as the tubular blank, and a plurality of holes are processed on the tubular blank as mounting holes 111. The shape and distribution of the mounting holes 111 are not specifically limited, and can be circular holes, square holes distributed in an array, or circular holes, square holes distributed in a spiral, etc.

[0055] Optionally, the mounting hole 111 is configured as a threaded hole to improve the connection stability with the flammable plug cone 2 .

[0056] S2. Put a liner 4 on the inner side of the tubular blank, and put an outer tube 5 with an injection hole 51 on the outer side, and make the injection hole 51 on the outer tube 5 correspond to the mounting hole 111 one by one. The outer tube 5 can be made of an aluminum alloy tube, and the outer diameter of the liner 4 is consistent with the inner diameter of the tubular blank, and the inner diameter of the outer tube 5 is consistent with the outer diameter of the tubular blank. Inject non-metallic material into the mounting hole 111 through the injection hole 51 to cast and form the combustible plug cone 2. In order to ensure that the combustible plug cone 2 can be completely filled in the mounting hole 111, a plurality of air holes 41 are opened on the liner 4, and the plurality of air holes 41 correspond to the mounting hole 111 one by one, and the size of the air holes 41 is smaller than the mounting hole 111. As for the injection hole 51, it is set as a conical hole to facilitate the insertion of the injection port 7 of the external injection molding device into the injection hole 51.

[0057] Optionally, in order to prevent displacement between the liner 4, the tubular blank and the outer tube 5 during the casting process, a positioning member 6 is provided between the liner 4, the tubular blank and the outer tube 5. In this embodiment, the positioning member 6 is a pin, and a positioning hole is provided on the liner 4, the tubular blank and the outer tube 5, and the positioning hole is located at one end of the tubular blank. After the combustible plug cone 2 is formed, the pin is removed, and the portion of the tubular blank with the positioning hole is cut off, and the liner 4 and the outer tube 5 can be reused.

[0058] S3, conduct the first pressure test, which is an external pressure test. During the test, the two ends of the entire tubular blank are sealed and placed in a sealed container. Water, oil, gas and other media are poured into the sealed container to observe the pressure resistance. If the pressure resistance does not meet the requirements, return to S2 and select different materials to re-process the combustible plug cone 2; if the pressure resistance meets the requirements, continue to process the surface of the combustible plug cone 2, cut off the parts of the combustible plug cone 2 that protrude from the inner and outer walls of the tubular blank, so that the end faces of the combustible plug cone 2 are flush with the inner and outer walls of the tubular blank, and then proceed to the next step.

[0059] S4, process the internal thread at the end of the tubular blank, form the support tube 2, and then conduct the second pressure test, which is an internal and external pressure test. During the test, the external pressure test and the internal pressure test are carried out respectively. The external pressure test is the same as the first pressure test operation method. The internal pressure test is to seal the two ends of the entire support tube 2 and pass water, oil, gas and other media into the support tube 2 to observe the pressure resistance. If the pressure resistance does not meet the requirements, return to S2, select different materials to re-process the combustible plug cone 2, and if the pressure resistance meets the requirements, proceed to the next step.

[0060] S5, processing the joint 3, connecting the joint 3 to the support pipe 2, realizing the assembly, and completing the processing.

[0061] S6, conduct indoor combustion simulation test, if qualified, batch production will be carried out; if not qualified, repeat step S2 to adjust the material used for the combustible plug cone 2.

[0062] The main difference between Example 3 and Example 2 is that the flammable plug cone 2 in Example 2 is manufactured separately and then connected to the steel pipe as a tubular blank, while the flammable plug cone 2 in Example 3 is directly connected to the steel pipe as a tubular blank by injection molding.

[0063] The plug-cone fusible tubes prepared in Example 2 and Example 3 can effectively ignite the coal seam and realize a controllable backward injection process.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Plug cone type fusible tube, characterized in that: include: A support tube (1), wherein a plurality of mounting holes (111) are formed on the support tube (1); The combustible plug cones (2) are inserted into the mounting holes (111) in a one-to-one correspondence and are fixedly connected to the support tube (1). The combustible plug cones (2) are made of fusible alloy or fusible non-metal.

2. The plug-cone type fusible tube according to claim 1, characterized in that: The inner and outer end surfaces of the combustible plug cone (2) are respectively flush with the inner and outer walls of the support tube (1).

3. The plug-cone type fusible tube according to claim 2, characterized in that: The invention also comprises a joint (3), wherein the joint (3) comprises a main body (31) and a second connecting part (32), wherein two sections of the second connecting part (32) are respectively arranged at two axial ends of the main body (31) and have an inner diameter which is the same as the inner diameter of the main body (31); the support tube (1) comprises a support part (11) and a first connecting part (12); the mounting hole (111) is provided on the support part (11), the inner diameter of the support part (11) is the same as the inner diameter of the main body (31); the first connecting part (12) is arranged at one axial end of the support part (11), and the second connecting part (32) is inserted into the first connecting part (12) and is threadedly connected to the first connecting part (12).

4. The plug-cone type fusible tube according to claim 1, characterized in that: The mounting hole (111) is a threaded hole.

5. The plug-cone type fusible tube according to claim 1, characterized in that: The flammable plug cone (2) is threaded, injection-molded or bonded to the support tube (1).

6. A method for processing a plug-cone type fusible tube, used for processing the plug-cone type fusible tube as claimed in claim 1, mainly comprising the following steps: Processing a mounting hole (111) on the tubular blank; The flammable plug cone (2) is processed and the flammable plug cone (2) is assembled into the mounting hole (111).

7. A method for processing a plug-cone type fusible tube, used for processing the plug-cone type fusible tube as claimed in claim 1, characterized in that: The main steps include: Processing a mounting hole (111) on the tubular blank; A liner tube (4) is sleeved on the inner side of the tubular blank, and an outer tube (5) with an injection hole (51) is sleeved on the outer side. The injection hole (51) corresponds to the mounting hole (111) one by one, and a fusible non-metal casting-molded combustible plug cone (2) is injected into the mounting hole (111) through the injection hole (51).

8. The method for processing a plug-cone type fusible tube according to claim 7, characterized in that: The liner tube (4), the tubular blank and the outer tube (5) are positioned using a positioning piece (6) before casting and forming the combustible plug cone (2).

9. The method for processing a plug-cone type fusible tube according to any one of claims 6 to 8, characterized in that: After the combustible plug cone (2) is fixedly connected to the tubular blank, the parts of the combustible plug cone (2) protruding from the inner wall and the outer wall of the tubular blank are removed.

10. The method for processing a plug-cone type fusible tube according to any one of claims 6 to 8, characterized in that: After the flammable plug cone (2) is fixedly connected to the tubular blank, the tubular blank is pressure tested to ensure that the pressure resistance of the plug cone type fusible tube finally formed meets the requirements.

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