High-pressure sealing drill pipe for gas extraction in cross-seam drilling of outburst coal seams

Abstract

This invention discloses a high-pressure sealed gas extraction drill pipe for cross-layer drilling in outburst-prone coal seams, comprising an outer drill pipe, an inner extraction pipe installed in the cavity of the outer drill pipe, and an anti-backflow component. The anti-backflow component is installed on the inner extraction pipe. The annular gap between the inner wall of the outer drill pipe and the inner extraction pipe serves as a high-pressure water ring supply channel. The central hole of the inner extraction pipe serves as a gas extraction channel for gas extraction. The specially shaped sealing ring of this invention achieves a seal between the inner extraction pipes of the two drill pipes, maximizing the diameter of the gas extraction steel pipe. This provides borehole support for rapid gas extraction and rapid elimination of the gas power source in the blowout, and also provides borehole support for lowering the protective screen before drilling. The specially structured annular anti-backflow component of this invention solves the backflow problem of the annular supply channel.

Description

Technical Field

[0001] This invention relates to the field of drilling technology for gas extraction in outburst-prone coal seams, and particularly to a high-pressure sealed drilling rod for gas extraction during drilling in cross-seam boreholes in outburst-prone coal seams. Background Technology

[0002] In the construction of inclined cross-layer boreholes in the bottom rock roadway of outburst-prone coal seams, gas drainage is implemented in the areas to be excavated or mined within the outburst-prone coal seam to achieve gas drainage and gas outburst mitigation. This is the main technical means for gas drainage and control in outburst-prone coal seams. Currently, the drill rods used for cross-layer drilling in soft outburst-prone coal seams in China mainly include grooved drill rods, ribbed drill rods, and prismatic grooved drill rods. These drill rods have sealing rings installed at the threaded connection, and the central hole of the drill rod serves as the flow channel. A one-way valve is installed in the central hole of the drill rod to prevent water leakage. A high-low conversion device and a jet nozzle are installed between the drill rod and the drill bit at the front end. Under low pressure, the flow is supplied to the drill bit, and under high pressure, the flow is supplied to the nozzle. High-pressure water jet cutting and cavity creation are carried out on the coal body of the coal section. During the cutting and cavity creation process, a large amount of water slag and gas are generated. These water slag and gas are discharged outside the hole through the annular gap between the drill rod surface and the borehole wall. For inclined boreholes in outburst-prone coal seams, coal slag can be discharged using its own weight and the spiral grooves, spiral ribs, and protrusions on the drill rod surface. Since methane gas is lighter than air, it can only be discharged through pressure difference, leading to excessive methane levels in the perforation. Excessive methane levels in perforations have become one of the main safety hazards in outburst-prone mines. On the other hand, because the drill rods used have a single-wall structure, after the installation of high-low pressure switching devices, the drill rods lose the function of lowering the protective screen pipe during drill retraction.

[0003] Therefore, the current high-pressure water jet cutting and cavity creation method for drilling through layers has two problems: one is the problem of excessive gas in the nozzle, and the other is the difficulty in lowering the protective screen during drill retraction. In order to solve the problems of excessive gas in the high-pressure water jet cutting and hole-making permeability enhancement process of cross-layer drilling and the problem of lowering the screen pipe, the applicant once submitted "Cross-layer drilling extraction drill tool and blowout prevention hole gas extraction method during drilling" (application number 202210251353.3). The "extraction drill rod" involved has two defects: (1) Using the original inner wall of the outer tube as the coaxial positioning reference can maximize the cross-sectional area of ​​the threaded flow channel and the diameter of the gas extraction steel pipe, and enhance the extraction and blowout prevention effect of the drill rod. However, due to the unevenness of the pipe wall thickness, it is difficult to control the coaxiality of the outer tube and the inner tube. As a result, the high pressure resistance of the seal between the inner tubes is poor, and the life of the sealing ring is also shortened; (2) No backflow prevention technology solution is given for the flow channel of the drill rod ring. During cross-layer inclined drilling, the water stored in the drill rod for tens of meters leaks down, wasting water power and affecting the working environment.

[0004] Therefore, in response to these two defects, this patent focuses on solving the sealing problem between gas extraction steel pipes and the backflow prevention problem of the circular flow channel, based on the premise of circular flow supply, high pressure resistance, backflow prevention, and maximizing the diameter of gas extraction steel pipes. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a high-pressure sealed drilling rod for gas extraction during drilling in a coal seam.

[0006] The technical solution adopted to achieve the above objectives is:

[0007] The high-pressure sealed gas extraction drill pipe for cross-burden drilling in coal seams includes an outer drill pipe and an inner extraction pipe installed in the cavity of the outer drill pipe. It is characterized by further including an anti-backflow component, which is installed on the inner extraction pipe. The annular gap between the inner wall of the outer drill pipe and the inner extraction pipe is a high-pressure water ring supply channel, and the central hole of the inner extraction pipe is a gas extraction channel for extracting gas.

[0008] Furthermore, one end of the external drill rod is machined with a male thread, a male end positioning hole, and a male end retaining ring groove, and the other end of the external drill rod is machined with a female thread, a female end positioning hole, and a female end retaining ring groove. A first sealing ring is installed on the male thread end of the external drill rod, and the male thread and the female thread are matched with each other.

[0009] Furthermore, the outer surface of the outer drill rod is provided with a spiral groove, a spiral rib, or a prismatic groove.

[0010] Furthermore, the extraction inner tube is composed of a gas extraction steel pipe, a female end positioning ring, a male end positioning ring, a special-shaped sealing ring, and a second sealing ring. One end of the gas extraction steel pipe with the second sealing ring is fixedly inserted into the inner hole of the female end positioning ring, and the other end of the gas extraction steel pipe passes through the inner hole of the male end positioning ring. The special-shaped sealing ring is fastened to the outer end of the female end positioning ring.

[0011] The outer circle of the male end positioning ring is located inside the male end positioning hole, and the male end positioning ring is fixed between the gas drainage steel pipe and the inner cavity of the outer drill pipe by setting a first spring retaining ring in the male end retaining ring groove. The outer circle of the female end positioning ring is located inside the female end positioning hole, and the female end positioning ring is limited and fixed in the cavity of the outer drill pipe by setting a second spring retaining ring in the female end retaining ring groove.

[0012] Furthermore, the gas drainage steel pipe is fixedly connected to the mother end positioning ring by applying adhesive.

[0013] Furthermore, the anti-backflow component consists of a shaped sliding seal ring, a sliding support, a compression spring, a fixed support, and a third spring retaining ring. The shaped sliding seal ring is fastened to the sliding support, the compression spring is located between the sliding support and the fixed support, and is limited and fixed to the gas drainage steel pipe by the third spring retaining ring. The compression spring pushes the shaped sliding seal ring on the sliding support to fit tightly against the inner ring end face of the female end positioning hole and the female end positioning ring, thereby realizing the anti-backflow function of the ring supply channel.

[0014] Furthermore, the female end positioning ring has an installation groove on its outer end, and the irregular-shaped sealing ring is fastened in the installation groove.

[0015] Furthermore, the sliding support and the irregular sliding sealing ring exist in two states. When high-pressure water is supplied, the sliding support slides inward under the action of high-pressure water and compresses the compression spring, opening the supply channel. When preventing backflow, the sliding support slides outward under the action of the compression spring, and the irregular sliding sealing ring is in contact with the inner wall of the outer drill rod for sealing, while also in contact with the inner ring end face of the female end positioning ring for sealing.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. This invention addresses the use of drilling pipes for high-pressure ring-fed and low-pressure gas extraction. The invention designs a specially shaped sealing ring to achieve a reliable seal between the inner extraction pipes of the two drill pipes, maximizing the diameter of the gas extraction steel pipe. This provides borehole support for rapid gas extraction and elimination of the gas source in the blowout, and also provides borehole support for lowering the protective screen before drilling.

[0018] 2. This invention addresses the problem of water leakage from the drill rod during the process of adding drill rods in inclined drilling. This invention designs a specially structured annular hole anti-backflow component, which solves the backflow problem of the annular supply channel. The anti-backflow component is designed with a specially shaped sliding sealing ring, and only one irregular sliding sealing ring is needed to seal the backflow path of the annular supply channel.

[0019] 3. The overall structure of the gas extraction drill pipe of the present invention features complete detachability and easy replacement of seals: after removing the female end spring retaining ring, the extraction inner tube and the anti-backflow component can be pulled out together; the sealing ring, irregular sealing ring and irregular sliding sealing ring on the gas extraction drill pipe can all be replaced. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall design of the drilling pipe for gas extraction during drilling according to the present invention;

[0021] Figure 2 This is a structural diagram of the external drill pipe of the gas extraction drill pipe of the present invention.

[0022] Figure 3 This is an assembly diagram of the extraction inner tube of the drilling pipe for gas extraction during drilling according to the present invention.

[0023] Figure 4 This is a structural diagram of the male and female support rings at both ends of the drilling pipe for gas extraction during drilling according to the present invention;

[0024] Figure 5 This is an assembly diagram of the anti-backflow component of the gas extraction drill pipe during drilling according to the present invention;

[0025] Figure 6 This is an assembly diagram of the extraction inner tube and the anti-backflow component of the present invention;

[0026] Figure 7 This is a diagram showing the threaded connection of the drilling pipe for gas extraction during drilling, and its working position.

[0027] Figure 8 This is a schematic diagram of the irregular-shaped sealing ring in this invention;

[0028] Figure 9 This is a schematic diagram of the irregular sliding sealing ring in this invention. Figure 1 ;

[0029] Figure 10 This is a schematic diagram of the irregular sliding sealing ring in this invention. Figure 2 .

[0030] Among them, 1-external drill pipe, 11-male thread, 12-female thread, 13-male end positioning hole, 14-female end positioning hole, 15-female end retaining ring groove, 16-male end retaining ring groove, 17-spiral groove, 18-first sealing ring, 2-extraction inner tube, 21-gas drainage steel pipe, 22-female end positioning ring, 23-male end positioning ring, 24-irregular sealing ring, 25-second sealing ring, 3-anti-backflow component, 31-irregular sliding sealing ring, 32-sliding support, 33-compression spring, 34-fixed support, 35-third spring retaining ring, 36-third sealing ring, 37-fourth sealing ring, 4-high pressure water flow channel, 5-gas gas flow channel.

[0031] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0033] like Figure 1-10As shown in the figure, this embodiment discloses a high-pressure sealed gas extraction drill pipe for cross-layer drilling in outburst coal seams, comprising an outer drill pipe 1, a gas extraction steel pipe 21, and an anti-backflow component 3. The gas extraction steel pipe 21 is inserted into the cavity of the outer drill pipe 1, and the anti-backflow component 3 is sleeved on the gas extraction steel pipe 21. The annular gap between the outer drill pipe 1 and the gas extraction steel pipe 21 is a high-pressure water flow channel 4, which provides high-pressure fluid for hydraulic cutting or cavity creation in cross-layer drilling. The central hole of the gas extraction steel pipe 21 is a gas gas flow channel 5, through which the gas generated by hydraulic cutting or cavity creation is extracted to the outside of the hole.

[0034] like Figure 1-4 As shown, one end of the outer drill rod 1 is machined with a male thread 11, a male end positioning hole 13, and a male end retaining ring groove 16. The other end of the outer drill rod 1 is machined with a female thread 12, a female end positioning hole 14, and a female end retaining ring groove 15. The male thread 11 and the female thread 12 are matched with each other. Before machining the male thread 11 and the female thread 12, the two ends of the rod body can be upsetting or friction welded. If friction weld is used, the two weld beads in the inner hole need to be machined off. The outer surface of the outer drill rod 1 located at the male thread 11 end is equipped with a first sealing ring 18. The outer surface of the outer drill rod 1 is provided with a spiral groove 17. The outer surface shape of the outer drill rod can also be a spiral rib or a prismatic groove, that is, the outer surface shape of the outer drill rod 1 can be the same as the outer surface shape of the existing drill rod.

[0035] like Figure 1-4 As shown, the inner extraction pipe 2 consists of a gas extraction steel pipe 21, a female end positioning ring 22, a male end positioning ring 23, a special-shaped sealing ring 24, and a second sealing ring 25. One end of the gas extraction steel pipe 21 with the second sealing ring 25 is fixedly inserted into the inner hole of the female end positioning ring 22, and the other end of the gas extraction steel pipe 21 passes through the inner hole of the male end positioning ring 23. The special-shaped sealing ring 24 is fastened to the outer end of the female end positioning ring 22. The outer circle of the male end positioning ring 23 is located in the male end positioning hole 13, and the male end positioning ring 23 is limited and fixed to the gas extraction steel pipe 21 by setting a first spring retaining ring in the male end retaining ring groove 16. The outer circle of the female end positioning ring 22 is located in the female end positioning hole 14, and the female end positioning ring 22 is limited and fixed in the cavity of the outer drill pipe 1 by setting a second spring retaining ring in the female end retaining ring groove 15.

[0036] like Figure 1-4As shown, the male end positioning ring 23 is fitted onto the gas drainage steel pipe 21 and located within the male end positioning hole 13. A first spring retaining ring is provided in the male end retaining ring groove 16, located outside the male end positioning ring 23. Under the action of the first spring retaining ring, the male end positioning ring 23 is limited and fixed onto the gas drainage steel pipe 21. The fitting of the male end positioning ring 23 onto the gas drainage steel pipe 21 is a movable fitting, allowing for easy installation and removal. A limiting step is provided on the gas drainage steel pipe 21, so that the male end positioning ring 23 can no longer move after sliding a certain distance inward on the gas drainage steel pipe 21, and is limited and fixed onto the gas drainage steel pipe 21 under the action of the first spring retaining ring. Figure 4 (b) is a schematic diagram of the male end positioning ring 23.

[0037] like Figure 1-4 As shown, a second sealing ring 25 is provided on one end of the gas extraction steel pipe 21 connected to the female end positioning ring 22. The female end positioning ring 22 is located in the female end positioning hole 14. A second spring retaining ring is provided in the female end retaining ring groove 15. The second spring retaining ring is located on the outside of the female end positioning ring 22. The female end positioning ring 22 is limited and fixed in the outer drill rod 1 under the action of the second spring retaining ring. After applying glue to the end of the gas extraction steel pipe 21 with the second sealing ring 25, it is inserted into the inner hole of the female end positioning ring 22. When applying glue, the second sealing ring 25 should not be contaminated. The purpose of applying glue is to permanently fix the gas extraction steel pipe 21 and the female end positioning ring 22 together. An installation groove is opened on the outer end of the female end positioning ring 22, and the irregular sealing ring 24 is fastened in the installation groove.

[0038] like Figure 5-6 As shown, the anti-backflow assembly 3 includes a fixed support 34, a sliding support 32, a compression spring 33 connecting the fixed support 34 and the sliding support 32, and a shaped sliding sealing ring 31 located on the sliding support 32. Both the fixed support 34 and the sliding support 32 are sleeved on one end of the gas drainage steel pipe 21 where the female end positioning ring 22 is located. The gas drainage steel pipe 21 is provided with a third spring retaining ring 35, and the fixed support 34 is fixedly limited to the gas drainage steel pipe 21 by the third spring retaining ring 35. The shaped sliding sealing ring 31 is fixedly fastened to the sliding support 32. The shaped sliding sealing ring 31 can be made of, for example, a... Figure 5 (a) and as Figure 5 The shape and structure of (b), specifically the structure as follows: Figure 9-10 As shown, a third sealing ring 36 and a fourth sealing ring 37 can also be installed on the sliding support 32 to replace the irregular sliding sealing ring 31, such as... Figure 5 As shown in (c).

[0039] like Figure 6The diagram shows the assembly of the gas extraction inner tube 2 and the anti-backflow component 3 of the present invention. The anti-backflow component 2 includes a shaped sliding sealing ring 31, a sliding support 32, a compression spring 33, a fixed support 34, and a third spring retaining ring 35, which are sequentially fitted onto the gas extraction steel pipe 21 and fixed by the third spring retaining ring 35. The fitting of the male end positioning ring 23 to the gas extraction steel pipe 21 is a movable fitting, and the male end positioning ring 23 can be easily removed. When installing the anti-backflow component 3, the male end positioning ring 23 is removed. After the anti-backflow component 3 is installed, the male end positioning ring 23 is installed again. The extraction inner tube 2 with the anti-backflow component 3 installed is inserted into the inner cavity of the outer drill rod 1 from the female end of the outer drill rod 1, so that the male end positioning ring 23 is inserted into the male end positioning hole 13 and fixed by the first spring retaining ring, and the female end positioning ring 22 is inserted into the female end positioning hole 14 and fixed by the second spring retaining ring. After assembly, as shown... Figure 1 As shown.

[0040] like Figure 7 The diagram shows the threaded connection of the drilling pipe for gas extraction during drilling, and its position. The sealing between the outer drilling pipes 1 relies on the first sealing ring 18, and the sealing between the inner extraction pipes 2 relies on the shaped sealing ring 24. The shaped sliding sealing ring 31 is used to prevent backflow in the annular supply channel 4. Figure 7 (a) is the backflow prevention condition. Figure 7 (b) is the high-pressure water supply condition. When high-pressure water is supplied, the sliding support 32 slides inward under the action of high-pressure water and compresses the compression spring 33. When preventing backflow, the sliding support 32 slides outward under the action of the compression spring, and the irregular sliding sealing ring 31 is sealed against the inner wall of the outer drill rod 1, and at the same time, it is sealed against the inner ring end face of the female end positioning ring 22.

[0041] In the description of this invention, it should be understood that the terms "center", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0042] If the terms "first" or "second" are used in this document to define components, those skilled in the art should know that the use of "first" or "second" is merely for the convenience of describing the invention and simplifying the description, and unless otherwise stated, the above terms have no special meaning.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure sealed gas extraction drill pipe for cross-seam boreholes in outburst-prone coal seams, comprising an outer drill pipe (1) and an inner extraction pipe (2) installed within the cavity of the outer drill pipe (1), characterized in that, It also includes an anti-backflow component (3), which is installed on the inner extraction tube (2). The annular gap between the inner wall of the outer drill rod (1) and the inner extraction tube (2) is a high-pressure water ring supply channel (4), and the central hole of the inner extraction tube (2) is a gas extraction channel (5) for extracting gas. One end of the external drill rod (1) is machined with a male thread (11), a male end positioning hole (13), and a male end retaining ring groove (16). The other end of the external drill rod (1) is machined with a female thread (12), a female end positioning hole (14), and a female end retaining ring groove (15). A first sealing ring (18) is installed on the male thread end of the external drill rod (1). The male thread (11) and the female thread (12) are matched with each other. The extraction inner tube (2) is composed of a gas extraction steel pipe (21), a female end positioning ring (22), a male end positioning ring (23), a special-shaped sealing ring (24), and a second sealing ring (25). One end of the gas extraction steel pipe (21) with the second sealing ring (25) is fixedly inserted into the inner hole of the female end positioning ring (22), and the other end of the gas extraction steel pipe (21) is inserted into the inner hole of the male end positioning ring (23). The special-shaped sealing ring (24) is fastened to the outer end of the female end positioning ring (22). The outer circle of the male end positioning ring (23) is located inside the male end positioning hole (13), and the male end positioning ring (23) is fixed to the gas drainage steel pipe (21) by setting a first spring retaining ring in the male end retaining ring groove (16). The outer circle of the female end positioning ring (22) is located inside the female end positioning hole (14), and the female end positioning ring (22) is fixed to the cavity of the outer drill rod (1) by setting a second spring retaining ring in the female end retaining ring groove (15). The anti-backflow assembly (3) consists of a shaped sliding seal ring (31), a sliding support (32), a compression spring (33), a fixed support (34), and a third spring retaining ring (35). The shaped sliding seal ring (31) is fastened to the sliding support (32). The compression spring (33) is located between the sliding support (32) and the fixed support (34), and is fixed to the gas drainage steel pipe (21) by the third spring retaining ring (35). The compression spring (33) pushes the shaped sliding seal ring (31) on the sliding support (32) to fit tightly against the female end positioning hole (14).

2. The high-pressure sealed drilling rod for gas extraction in cross-seam boreholes of outburst-prone coal seams according to claim 1, characterized in that, The outer surface of the external drill rod (1) is provided with a spiral groove, a spiral rib, or a prismatic groove.

3. The high-pressure sealed drilling rod for gas extraction in cross-seam boreholes of outburst-prone coal seams according to claim 1, characterized in that, The gas drainage steel pipe (21) and the female end positioning ring (22) are fixedly connected by applying adhesive.

4. The high-pressure sealed drilling rod for gas extraction in cross-seam boreholes of outburst-prone coal seams according to claim 1, characterized in that, The female end positioning ring (22) has an installation groove on its outer end, and the irregular sealing ring (24) is fastened in the installation groove.

5. The high-pressure sealed drilling rod for gas extraction in cross-seam boreholes of outburst-prone coal seams according to claim 1, characterized in that, The sliding support (32) and the irregular sliding sealing ring (31) exist in two states. When high-pressure water is supplied, the sliding support (32) slides inward under the action of high-pressure water and compresses the compression spring (33). When preventing backflow, the sliding support (32) slides outward under the action of the compression spring (33), and the irregular sliding sealing ring (31) is sealed against the inner wall of the outer drill rod (1) and sealed against the inner ring end face of the female end positioning ring (22).

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