Horizontal well jet flow axial slotting pressure relief coal and coal bed gas co-mining method

Abstract

The invention relates to a horizontal well jet flow axial slotting pressure relief coal and coal bed gas co-mining method. The method comprises the steps of horizontal well building, axial continuous hydraulic slotting, coal bed drainage pressure relief and coal and coal bed gas co-mining. The axial continuous hydraulic slotting comprises the steps that a casing pipe is put into a horizontal well; a plurality of slots are formed in the sleeve, and a directional structure is arranged in the sleeve; the water jet tool pipe column is tripped into the casing pipe, and the lateral nozzle is kept to move directionally along the directional structure; when the lateral nozzle is aligned with the foremost slot, high-pressure water sprayed by the lateral nozzle penetrates through the foremost slot to impact the coal seam, and high-pressure water sprayed by the axial nozzle pushes the oil pipe to retreat; when coal seam slotting at each slot is completed, water injection is stopped, and the oil pipe is pulled backwards; when the lateral nozzle is aligned with the next slot, the high-pressure water sprayed out of the lateral nozzle penetrates through the next slot to impact the coal seam, and the high-pressure water sprayed out of the axial nozzle still pushes the oil pipe to retreat; and the steps are repeated till coal seam slotting at the last seam groove is completed.

Description

Technical Field

[0001] The invention relates to the field of coalbed methane mining, and in particular to a method for co-mining coal and coalbed methane by jetting axial slots to relieve pressure on a horizontal well. Background Art

[0002] In recent years, with the increasing awareness of the importance of developing coalbed methane resources and strengthening the management of coal mine gas disasters and their mutual relationship, people's concept has evolved from "first gas extraction, then coal mining" to the concept of "coordinated development of coal and coalbed methane resources", and a lot of research work has been carried out for different geological conditions, which has important guiding significance for the coordinated development of coal and coalbed methane in coal mining areas. The coalbed methane content in my country's mines is generally high, the permeability is low, the geological structure of coalfields is diverse, and the extraction is difficult. With the increase of mining depth, the occurrence pressure and ground stress increase, and the extraction difficulty increases further. Coal and coalbed methane are typical symbiotic minerals of the same origin and body. Coal mining and coalbed methane development both promote and restrict each other. Coal mines have always extracted coalbed methane for the purpose of safety, and a large amount of coalbed methane resources have been directly discharged. The coordinated development of coal and coalbed methane has improved the recovery rate and utilization rate of resources.

[0003] In view of my country's coal mining conditions, three coordinated development models under typical geological conditions were initially proposed, namely, the Jincheng model under high-permeability medium-hard coal seams, the Lianghuai model under low-permeability protruding soft coal seams, and the Songzao model under complex geological conditions.

[0004] The coordinated development of coal and coalbed methane is to coordinate the development and utilization plan of coal and coalbed methane resources in the target area, comprehensively consider and coordinate in terms of development time connection, spatial layout, mining and extraction deployment, etc., make full use of wells, tunnels and drilling projects, choose a reasonable development method, give full play to the mutually beneficial effects of gas and coal mining, maximize the development of coalbed methane, and carry out coal mining under the premise of safety, so as to realize the safe and efficient development of coal and coalbed methane resources and achieve the most ideal comprehensive benefits.

[0005] However, due to the fact that my country has many coal-bearing strata and coal-bed methane reservoir types, and coal-bed methane is stored in a very complex geological environment, the technical means of development are quite different. Therefore, it is extremely critical and important to explore and study methods suitable for the co-exploitation of coal resources and coal-bed methane under various conditions. Summary of the invention

[0006] The present invention provides a method for co-mining coal and coalbed methane by jet axial slitting to relieve coal pressure in a horizontal well. The method adopts a ground development mode and performs continuous axial slitting based on hydraulic slitting technology. After the slitting is completed, coalbed methane is extracted and coal is mined, thereby achieving a higher degree of coalbed pressure relief and mining efficiency.

[0007] The technical solution of the present invention is: A method for co-mining coal and coal-bed methane by jet axial slotting and pressure relief in a horizontal well, comprising: horizontal well construction, axial continuous hydraulic slotting, coal-bed drainage and pressure relief, and co-mining coal and coal-bed methane; When constructing a horizontal well, a horizontal well is formed by drilling in the coal seam along the direction of minimum principal stress; The steps of axial continuous hydraulic cutting include: The casing is lowered into the horizontal well; a plurality of slots are arranged on the casing along the axial direction thereof, and a directional structure is arranged inside the casing along the axial direction thereof; Lowering a water jet tool string into the casing, and keeping the lateral nozzle of the water jet tool string moving in a directional manner along the directional structure; the water jet tool string comprises an oil pipe for conveying high-pressure water, a water jet ejector arranged at the end of the oil pipe, a directional eccentric and a centralizer assembled on the oil pipe, and the water jet ejector comprises a lateral nozzle and an axial nozzle; When the lateral nozzle moves along the directional structure to align with the first slot on the casing, the high-pressure water sprayed by the lateral nozzle passes through the first slot to impact the coal seam, and the high-pressure water sprayed by the axial nozzle pushes the oil pipe to retreat in the horizontal direction; After each coal seam cutting at a slot is completed, water injection is stopped and the oil pipe is pulled backwards for a preset distance; when the lateral nozzle moves backwards along the directional structure to align with the next slot on the casing, the high-pressure water sprayed from the lateral nozzle passes through the next slot to impact the coal seam, and the high-pressure water sprayed from the axial nozzle still pushes the oil pipe backwards in the horizontal direction; this cycle is repeated until the coal seam cutting at the last slot is completed.

[0008] Furthermore, the orientation structure comprises: a continuous slide rail disposed in the sleeve along the axial direction thereof; When the coal seam is cut, the nozzle of the lateral nozzle is embedded in the continuous slide rail, and the nozzle of the lateral nozzle is arranged opposite to the corresponding slot.

[0009] Furthermore, the orientation structure comprises: a plurality of slide grooves and a plurality of slide rails arranged in the sleeve along the axial direction thereof; The slide rails are arranged at positions opposite to the slots of each slot, the slide grooves are arranged on the remaining axial tube wall of the sleeve except the slots, and the ends of the slide rails are arranged as trumpet-shaped introduction ports, which are opposite to the ends of the adjacent slide rails.

[0010] Furthermore, the rear end of the slide rail is provided with an anti-accidental opening device for blocking the lateral nozzle; When the backward pulling force of the lateral nozzle exceeds the maximum supporting force provided by the anti-accidental opening device, the anti-accidental opening device releases the limit on the lateral nozzle.

[0011] Furthermore, the slide rail comprises a first slide plate and a second slide plate opposite to each other, the first slide plate and the second slide plate each comprising: a connecting plate and a supporting plate rotatably connected by a rotating member, the connecting plate being connected to the sleeve; the nozzle of the lateral nozzle is embedded between the two supporting plates; When the weight of the coal seam fragments accumulated on the support plate exceeds the maximum supporting force provided by the rotating member, the support plate rotates relative to the connecting plate to make the coal seam fragments slide into the annulus between the oil pipe and the casing.

[0012] Furthermore, the surface of the slide rail is treated with a polyurethane coating.

[0013] The beneficial effects of the present invention are: Since many slits are opened on the casing in advance, the high-pressure water sprayed from the lateral nozzle does not need to be sprayed on the casing underground, which can reduce the pressure when the high-pressure water impacts the coal seam, reduce the difficulty of cutting with the lateral nozzle, and improve the cutting efficiency.

[0014] When the casing is lowered into the horizontal well, the angle of the casing in the well is uncontrollable. This uncontrollability will cause the side nozzles on the water jet tool string to be unable to aim at the slot after the water jet tool string is lowered into the casing, thereby causing the slitting operation to be unable to proceed. In the embodiment of the present application, relying on the directional structure set in the casing, the side nozzles of the water jet tool string are assembled with the directional structure before the water jet tool string is lowered into the casing, and the directional structure is used to limit the angle of the side nozzle of the water jet tool string, so that the side nozzle of the water jet tool string always remains in a state relative to the slot, ensuring the accurate execution of the slitting operation. In addition, the directional structure is used to limit the angle of the side nozzle of the water jet tool string, and when the water jet tool string retreats, the side nozzle will not deflect due to the deflection of the water jet tool string. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of horizontal well construction in an embodiment of the present application; Figure 2 This is a schematic diagram of performing axial continuous hydraulic slitting in an embodiment of the present application; Figure 3 for Figure 2 A partial enlarged view of Figure 4 for Figure 3 AA section view; Figure 5 This is a schematic diagram of the process of the method in the embodiment of the present application; Figure 6 A schematic diagram of a slide rail in an embodiment of the present application; Figure 7 This is a schematic diagram of the installation of the anti-accidental opening device in the slide rail in the embodiment of the present application; Figure 8 It is a schematic diagram of a rotating member in an embodiment of the present application. DETAILED DESCRIPTION

[0016] The exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims. The flowcharts shown in the accompanying drawings are merely exemplary and do not necessarily include all contents and operations / steps, nor do they necessarily have to be performed in the order described. For example, some operations / steps may be further decomposed, while some operations / steps may be combined or partially combined, so the actual order of execution may change according to actual conditions.

[0017] Reference Figure 1-Figure 5 The embodiment of the present application provides a method for co-mining coal and coalbed methane by jet axial slitting to relieve pressure in a horizontal well, including: horizontal well construction, axial continuous hydraulic slitting, coalbed drainage and pressure relief, and co-mining of coal and coalbed methane.

[0018] like Figure 1 When constructing a horizontal well, a drilling device is used to perform directional drilling along the direction of the minimum principal stress, thereby drilling a horizontal well in the coal seam 2. The drilling device includes a derrick 11, a drilling string connected to the derrick 11, a wellhead device 13 and a ground device 14. The drilling string includes a drill pipe 111, a centralizer 112 disposed between a vertical well and a horizontal well, and a drill bit 113 disposed at the end of the drill pipe 111.

[0019] Refer to the attached Figure 2-Figure 4 When performing axial continuous hydraulic cutting, follow the steps below: The casing 3 is lowered into the horizontal well; a plurality of slots 31 are provided on the casing 3 along its axial direction, and a directional structure is provided inside the casing 3 along its axial direction; The water jet tool string is lowered into the casing 3, and the lateral nozzle of the water jet tool string is kept moving in a directional manner along the directional structure; the water jet tool string includes an oil pipe 41 for conveying high-pressure water, a water jet ejector arranged at the end of the oil pipe 41, a directional eccentric 42 and a centralizer 43 assembled on the oil pipe 41, and the water jet ejector includes a lateral nozzle 44 and an axial nozzle 45; When the lateral nozzle 44 moves along the directional structure to align with the first slot on the casing 3, the high-pressure water sprayed by the lateral nozzle 44 passes through the first slot to impact the coal seam 2, and the high-pressure water sprayed by the axial nozzle 45 pushes the oil pipe 41 to retreat in the horizontal direction; After each coal seam cutting at a slot is completed, water injection is stopped and the oil pipe 41 is pulled backwards for a preset distance; when the lateral nozzle 44 moves backwards along the directional structure to align with the next slot on the casing 3, the high-pressure water sprayed by the lateral nozzle 44 passes through the next slot to impact the coal seam 2, and the high-pressure water sprayed by the axial nozzle 45 still pushes the water jet tool string to retreat in the horizontal direction; this cycle is repeated until the coal seam cutting at the last slot is completed.

[0020] When drilling a horizontal well, the horizontal well is drilled along the direction of the minimum principal stress, which is where the mechanical properties of the rock are weak. Drilling along this direction makes it easier to form extended cracks in the coal seam 2, increase the permeability of the coal seam, improve the conductivity of coalbed methane, make it easier to desorb coalbed methane, and improve the recovery rate; after drilling along the direction of the minimum principal stress, the fracture network formed by the slit can better communicate with the natural cracks in the coal seam, forming a more effective seepage channel. Compared with other directions, the flow resistance of the fluid in these cracks is smaller, which is conducive to the desorption of coalbed methane from the coal matrix and rapid flow to the wellbore. It is also conducive to the discharge of water in the coal body, reducing the water lock effect, and thus improving the coal mining efficiency; the minimum principal stress is the smallest of the three principal stresses, and the stress perpendicular to the slit direction is relatively small, and the force acting on the slit surface to close it is weak. The non-closure of the fracture can also increase the permeability of the coal body, allowing more coal body to exchange gas with the outside world, which is conducive to the mining of combustible gas in the coal, thereby increasing the output of coal.

[0021] Combination Figure 5 After drilling is completed, a casing 3 of a certain size is lowered, and when the target layer (below 1500m) is reached, the lowering of the casing 3 is stopped. Cement slurry 5 is injected into the casing 3 to fix the casing 3 on the well wall to prevent the well wall from collapsing and control the wellhead pressure.

[0022] Among them, the casing 3 used in the embodiment of the present application is pre-set with multiple slots 31 of specific length on the casing by axial continuous hydraulic slotting technology. The gaps between the multiple slots 31 are set between 0.5m-1m, for example, set to values ​​such as 0.5m, 0.7m, and 1m; and, in the radial direction of the casing 3, these slots 31 form a slot network on the casing.

[0023] In the above method of the present application, since many slits 31 are pre-opened on the casing 3, the high-pressure water sprayed from the lateral nozzle 44 does not need to be sprayed on the casing 3 underground, which can reduce the pressure when the high-pressure water impacts the coal seam 2, reduce the difficulty of cutting by the lateral nozzle 44, and improve the cutting efficiency.

[0024] When the casing 3 is lowered into the horizontal well, the angle of the casing 3 in the well is uncontrollable. This uncontrollability will cause the side nozzle 44 on the water jet tool string to be unable to face the slit 31 after the water jet tool string is lowered into the casing 3, thereby causing the slitting operation to be unable to proceed. In the embodiment of the present application, relying on the directional structure set in the casing 3, before the water jet tool string is lowered into the casing 3, the side nozzle 44 of the water jet tool string is assembled with the directional structure, and the directional structure is used to limit the angle of the side nozzle 44 of the water jet tool string, so that the side nozzle 44 of the water jet tool string always remains in a state relative to the slit 31, ensuring the accurate performance of the slitting operation. In addition, the directional structure is used to limit the angle of the side nozzle 44 of the water jet tool string, and when the water jet tool string retreats, the side nozzle 44 will not deflect due to the deflection of the water jet tool string.

[0025] Reference Figure 5 After the casing 3 is fixed, the tubing head 6 and the self-sealing well sealer are installed at the wellhead, the tubing 41 is lowered and the self-sealing well sealer is assembled. During the lowering of the tubing 41, it is necessary to ensure that the thread is tightened in the positive direction to meet the torque requirements. The lowering speed of the tubing 41 should be controlled at ≤0.03m / s, and when the tubing 41 reaches the slot 31, the speed should be further reduced to ≤0.02m / s. After the tubing 41 reaches the horizontal section of the casing 3, the straightener 42 and the directional eccentric 43 are used to ensure that the tubing 41 can move in the horizontal direction. When the lateral nozzle 44 reaches the farthest end between the directional structure and the casing, the movement of the tubing is stopped. When the directional eccentric 43 and the straightener 42 are used to inject high-pressure water jets, they play a role in preventing the tubing 41 from deflecting and shocking through the action of gravity and torque, while stabilizing the drilling direction, preventing changes in the well inclination, and reducing the resistance of the tubing 41 when dragging.

[0026] Combination Figure 5After the drilling and pipe installation of the multi-branch horizontal well is completed, the axial continuous hydraulic slotting technology provides high-pressure water through the work vehicle 7 and injects it into the oil pipe 41 through the continuous pipe 8. The high-pressure water is ejected through the axial nozzle 45 to generate reverse thrust to ensure that the oil pipe 41 continues to maintain a horizontal direction. The high-pressure water jet ejected from the lateral nozzle 44 impacts the coal seam 2 through the slot 31 to form a spindle-shaped cavity. After the first slot is formed, the oil pipe 41 retreats. When the second slot is formed, the coal body between the maximum width horizontal line position and the pipe wall of the casing 3 is broken and collapsed by itself due to gravity and the impact of high-pressure water. The coal body between the maximum width horizontal line and the highest horizontal line of the cavity is impacted and crushed to make the shape of the entire cavity more regular.

[0027] Reference Figure 6 In the embodiment of the present application, the orientation structure includes: a continuous slide rail 32 arranged in the casing 3 along its axial direction; when the coal seam is cut, the nozzle of the lateral nozzle 44 is embedded in the continuous slide rail 32, and the nozzle of the lateral nozzle 44 is arranged opposite to the corresponding slot 31. The setting method of the continuous slide rail can ensure the continuous orientation of the lateral nozzle 44 without the need for other structural design in the casing.

[0028] In another embodiment of the present application, the directional structure includes: a plurality of slide grooves and a plurality of slide rails 32 arranged in the sleeve 3 along its axial direction; the slide rails 32 are arranged at positions opposite to the notches of each slot 31, and the slide grooves are arranged on the remaining axial tube walls of the sleeve 3 except for each slot 31, and the ends of the slide rails 32 are arranged as trumpet-shaped introduction ports, and the introduction ports are opposite to the ends of adjacent slide rails 32. The arrangement of multiple slide rails 32 can reduce the installation cost. When the lateral nozzle 44 enters the slide rail 32 along the slide groove, the trumpet-shaped introduction port can provide an adjustment position to buffer the entry into the slide rail 32.

[0029] In this embodiment, the surface of the slide rail 33 is treated with a polyurethane coating.

[0030] Combination Figure 6 For the above continuous slide rail 32 and segmented slide rail 32, both include a relative first slide plate and a second slide plate, and the first slide plate and the second slide plate both include: a connecting plate and a support plate rotatably connected by a rotating member 321, and the connecting plate is connected to the casing 3; the nozzle of the lateral nozzle 44 is embedded between the two support plates; when the gravity of the coal seam fragments accumulated on the support plate exceeds the maximum support force provided by the rotating member 33, the support plate rotates relative to the connecting plate, so that the coal seam fragments slide into the annulus 33 between the oil pipe 41 and the casing 3.

[0031] In this embodiment, the rotating member 321 can be configured similarly to Figure 8The roller structure in the connecting plate and the supporting plate realizes the rotation of the supporting plate by meshing with the roller structure; of course, the rotating member 321 can also be set to a structure similar to a torsion spring.

[0032] Reference Figure 7 The tail end of the slide rail 32 is provided with an anti-accidental opening device 322 for blocking the side nozzle 44; when the backward pulling force of the side nozzle 44 exceeds the maximum supporting force provided by the anti-accidental opening device 322, the anti-accidental opening device 322 releases the limit on the side nozzle 44.

[0033] Combination Figure 5 After cutting, coal seam fragments and coal seam gas are discharged along the annulus 33 of the casing 3 and the oil pipe 41 along with the discharge liquid, and at the same time reach the separation device 9 for processing. The coal body is fractured to a certain extent, the coal seam voids are increased, and the coal seam gas permeability is improved.

[0034] Combination Figure 5 After all branch wells have completed water jet cavity building for coal and coalbed methane mining, the water jet tool string is replaced with a production string, and the fluid in the cavity and the main horizontal well is pumped to the ground by the production string under the action of pressure difference. While the water is extracted into the water storage pit, the coalbed methane is extracted to the gas gathering and transmission device under the action of pressure difference; the production string includes an oil pipe, a drainage pump arranged at the end of the oil pipe, and a pressure gauge connected to the oil pipe and arranged on the ground; as water in the coal seam flows from the coal seam into the cavity, it is discharged under the action of the drainage pump, so that the formation pressure is reduced. When the formation pressure drops below the critical desorption pressure, the coalbed methane begins to desorb and accumulate in the cavity. Under the action of pressure, the coalbed methane is extracted along the annulus between the production string and the casing to the gas gathering and transmission device for gas collection and storage.

[0035] The method for co-mining coal and coalbed methane by jet axial slit pressure relief in horizontal wells proposed in this embodiment can increase the coal seam pressure relief area, improve coalbed methane overflow and coalbed methane mining efficiency to a certain extent, reduce gas pressure during coal mining, reduce mining risks, and improve resource utilization.

[0036] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0037] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0038] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, relational terms such as "first" and "second" are used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements does not include those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0039] The technical solution provided by the present invention is described in detail above. The principle and implementation mode of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the present invention, and the content of this specification should not be understood as limiting the present invention. At the same time, for those skilled in the art, according to the present invention, there will be different forms of changes in the specific implementation mode and application scope. It is not necessary and impossible to list all the implementation modes here, and the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in a horizontal well, characterized in that: include: Horizontal well construction, axial continuous hydraulic slotting, coal seam drainage and pressure relief, and coal and coal seam methane co-production; When constructing a horizontal well, a horizontal well is formed by drilling in the coal seam along the direction of minimum principal stress; The steps of axial continuous hydraulic cutting include: The casing is lowered into the horizontal well; a plurality of slots are arranged on the casing along the axial direction thereof, and a directional structure is arranged inside the casing along the axial direction thereof; Lowering a water jet tool string into the casing, and keeping the lateral nozzle of the water jet tool string moving in a directional manner along the directional structure; the water jet tool string comprises an oil pipe for conveying high-pressure water, a water jet ejector arranged at the end of the oil pipe, a directional eccentric and a centralizer assembled on the oil pipe, and the water jet ejector comprises a lateral nozzle and an axial nozzle; When the lateral nozzle moves along the directional structure to align with the first slot on the casing, the high-pressure water sprayed by the lateral nozzle passes through the first slot to impact the coal seam, and the high-pressure water sprayed by the axial nozzle pushes the oil pipe to retreat in the horizontal direction; After each coal seam cutting at a slot is completed, water injection is stopped and the oil pipe is pulled backwards for a preset distance; when the lateral nozzle moves backwards along the directional structure to align with the next slot on the casing, the high-pressure water sprayed from the lateral nozzle passes through the next slot to impact the coal seam, and the high-pressure water sprayed from the axial nozzle still pushes the oil pipe backwards in the horizontal direction; this cycle is repeated until the coal seam cutting at the last slot is completed.

2. The method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in horizontal wells according to claim 1 is characterized in that: The orientation structure comprises: a continuous slide rail arranged in the sleeve along the axial direction thereof; When the coal seam is cut, the nozzle of the lateral nozzle is embedded in the continuous slide rail, and the nozzle of the lateral nozzle is arranged opposite to the corresponding slot.

3. The method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in horizontal wells according to claim 1 is characterized in that: The orientation structure comprises: a plurality of slide grooves and a plurality of slide rails arranged in the sleeve along the axial direction thereof; The slide rails are arranged at positions opposite to the slots of each slot, the slide grooves are arranged on the remaining axial tube wall of the sleeve except the slots, and the ends of the slide rails are arranged as trumpet-shaped introduction ports, which are opposite to the ends of the adjacent slide rails.

4. The method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in horizontal wells according to claim 3 is characterized in that: The rear end of the slide rail is provided with an anti-accidental opening device for blocking the lateral nozzle; When the backward pulling force of the lateral nozzle exceeds the maximum supporting force provided by the anti-accidental opening device, the anti-accidental opening device releases the limit on the lateral nozzle.

5. The method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in horizontal wells according to claim 2 or 3, characterized in that: The slide rail comprises a first slide plate and a second slide plate opposite to each other, wherein the first slide plate and the second slide plate each comprise: a connecting plate and a supporting plate rotatably connected by a rotating member, wherein the connecting plate is connected to the sleeve; and the nozzle of the lateral nozzle is embedded between the two supporting plates; When the weight of the coal seam fragments accumulated on the support plate exceeds the maximum supporting force provided by the rotating member, the support plate rotates relative to the connecting plate to make the coal seam fragments slide into the annulus between the oil pipe and the casing.

6. The method for co-mining coal and coalbed methane by jet axial slotting to relieve pressure in horizontal wells according to claim 2 or 3, characterized in that: The surface of the slide rail is treated with polyurethane coating.

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