Coal seam CO2 phase-change perforation fracturing anti-reflection gas extraction equipment and coal seam CO2 phase-change perforation fracturing anti-reflection gas extraction method

Abstract

The invention discloses coal seam CO2 phase change perforation fracturing anti-reflection gas extraction equipment and method, and relates to the technical field of coal mine gas prevention and control. The device comprises a device body, a coal clearing mechanism is arranged at the top of the device body and used for clearing and scraping coal rock fragments on the inner wall of the hole, and meanwhile a collecting mechanism is arranged below the coal clearing mechanism and used for collecting the cleared coal rock fragments. The coal cleaning mechanism comprises a movable pipe rotationally mounted in the equipment body; through the coal cleaning mechanism, a threaded rod can be driven to drive a movable ring to move, so that a rotating rod, a connecting pipe and a conical rod enter a hole, then a movable pipe is driven to rotate, the rotating rod, the connecting pipe and a cleaning scraper are driven to rotate through a limiting groove and a limiting plate, coal rock fragments on the inner wall of the hole are scraped, and the conical rod can push the coal rock fragments in the hole during resetting; and the coal rock fragments on the inner wall of the hole are effectively cleaned, abrasion or damage caused by contact of the air bag and the coal rock fragments in subsequent operation is avoided, the blasting effect of the subsequent fracturing pipe is guaranteed, and therefore gas is better extracted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine gas prevention and control, in particular to a coal seam CO2 phase change perforation fracturing and gas extraction equipment and method. BACKGROUND

[0002] The carbon dioxide gas expansion fracturing technology is a kind of non-explosive fracturing technology based on physical phase change energy release, and the core logic is to use the rapid phase change expansion characteristics of liquid carbon dioxide to produce controllable pressure acting on the coal and rock medium, so as to realize the coal body fracture and permeability improvement. The specific process is as follows: liquid carbon dioxide is injected into a special fracturing pipe through a high-pressure filling device, and the fracturing pipe is provided with an activator (such as an electric heating rod or a chemical activator); after starting the activator at the operation site, the liquid carbon dioxide rapidly absorbs heat and completes the "liquid-gas" phase change in milliseconds, and the volume expands sharply (the expansion ratio can reach 600-800 times), so that the pressure in the fracturing pipe instantaneously rises to 30-80 MPa; when the pressure exceeds the compressive strength and tensile strength threshold of the coal and rock, a crack network is generated in the coal and rock, and finally the coal body fracturing and gas channel dredging are realized.

[0003] Based on the search of the patent number and the deficiencies in the prior art, it is found that: Before the fracturing pipe is operated, the staff needs to fill the stemming or insert the air bag between the fracturing pipe and the drill hole, and the inner wall of the drill hole is easy to leave a large amount of coal and rock fragments after drilling. When the air bag expands, it is easy to produce severe friction with the surface of the air bag, causing the air bag to wear and damage, destroying the sealing performance, and further leading to pressure loss of control during the fracturing pipe operation, affecting the coal body fracturing effect and gas extraction efficiency, and also affecting the subsequent air bag recycling, increasing the construction cost. SUMMARY

[0004] In order to solve the problem that the coal and rock fragments are easy to produce severe friction with the surface of the air bag when the air bag expands, the purpose of the present application is to provide a coal seam CO2 phase change perforation fracturing and gas extraction equipment and method.

[0005] To solve the above technical problems, the present application adopts the following technical scheme: a coal seam CO2 phase change perforation fracturing and gas extraction equipment, comprising an equipment body, a coal cleaning mechanism is arranged at the top of the equipment body for cleaning and scraping off the coal and rock fragments on the inner wall of the hole, and a collecting mechanism is arranged below the coal cleaning mechanism for collecting the coal and rock fragments removed; The coal cleaning mechanism comprises a movable pipe rotatably installed in the equipment body, a rotating rod movably arranged in the movable pipe, a plurality of limiting plates annularly arranged and fixedly installed on the outer side of the rotating rod, the plurality of limiting plates being movably clamped in the corresponding limiting slots respectively, an activity ring movably arranged in the rotating rod, a connecting pipe fixedly installed on one side of the rotating rod, a plurality of cleaning scrapers annularly arranged and fixedly installed on the outer side of the connecting pipe, a tapered rod fixedly installed on the end of the connecting pipe away from the rotating rod, and a threaded rod rotatably arranged in the equipment body, the activity ring being threadedly sleeved on the outer side of the threaded rod.

[0006] Preferably, the collecting mechanism comprises a feeding box fixedly connected with the equipment body, the inside of the feeding box being in an inclined state, a through slot being formed on the side of the equipment body close to the feeding box, an empty slot being formed on the bottom of the equipment body, a collecting box being slidably installed in the empty slot, a feeding slot being formed on one side of the top end of the collecting box, and trapezoidal blocks being fixedly installed in the collecting box in an inclined state.

[0007] Preferably, the inner wall of the empty slot is fixedly installed with symmetrically distributed guide rails, the bottom of the collecting box is formed with symmetrically distributed clamping slots, and the two guide rails respectively penetrate through the corresponding clamping slots.

[0008] Preferably, the equipment body is fixedly installed with support plates on both sides, and the movable pipe is rotatably installed on the corresponding support plates at both ends.

[0009] Preferably, the outer side of one of the support plates is rotatably installed with a rotating shaft, the outer side of the rotating shaft is fixedly installed with a pinion, the outer side of the pinion is meshingly connected with a gear, and the movable pipe is fixedly connected with the gear.

[0010] Preferably, the outer side of one of the support plates is fixedly installed with a stabilizing box, the threaded rod is rotatably installed on the top of the stabilizing box, and the pinion and the gear are both located in the stabilizing box.

[0011] Preferably, one end of the threaded rod is coaxially fixedly installed with a first motor, and one end of the rotating shaft is coaxially fixedly installed with a second motor.

[0012] The application also discloses a method for implementing the coal seam CO2 phase change perforation fracturing and gas extraction equipment. Step one, move the device to the target drilling hole, align the tapered rod with the drilling hole, push the activity ring by driving the threaded rod, drive the cleaning assembly into the drilling hole until the connecting pipe is completely inserted, then rotate the movable pipe to make the cleaning scraper rotate, scrape off the coal rock fragments on the hole wall, push out the fragments in the hole when the tapered rod is reset by driving the threaded rod in reverse, and complete the cleaning. Step two, send the activated tube into the cleaned borehole, connect the high-pressure filling device to the tube, inject a certain amount of liquid CO2, then close the filling valve, remove the pipeline and check the activator line, and remove the filling device; Step three, personnel evacuate to the safety zone and set up a warning, activate the activator remotely, liquid CO2 absorbs heat and gasifies into gas in milliseconds, the volume expands 600-800 times, the pressure in the tube reaches 30-80 MPa, and finally the pressure breaks through the coal rock strength threshold to form a fracture network to dredge the gas channel.

[0013] Advantages Compared with the prior art, the advantages of the present application are: 1. The coal cleaning mechanism can drive the threaded rod to move the movable ring, so that the rotating rod, the connecting pipe and the conical rod enter the hole, then drive the movable pipe to rotate, and drive the rotating rod, the connecting pipe and the cleaning scraper to rotate through the limiting groove and the limiting plate, so that the coal rock fragments in the hole wall are scraped off, and when the conical rod pushes the coal rock fragments in the hole, the coal rock fragments in the hole wall are effectively cleaned, avoiding the contact between the air bag and the coal rock fragments in subsequent operation, which causes wear or damage, and ensuring the blasting effect of the subsequent fracturing tube, so that the gas can be better extracted; 2. The collection mechanism can effectively collect the coal rock fragments removed, avoid the scattering of the coal rock fragments affecting the working environment, and improve the cleanliness of the operation; 3. The trapezoidal blocks in the collection tank of the collection mechanism are distributed in an inclined state, which can convey the coal rock fragments entering the collection tank to the middle, avoid the accumulation of coal rock fragments at the feed slot to hinder the entry of subsequent coal rock fragments, ensure the continuous and smooth collection process of coal rock fragments, and improve the collection efficiency.

[0014] 4. After the application of the carbon dioxide gas expansion fracturing technology, the permeability of the coal reservoir is increased by 12.3-15.7 times, the original permeability of the coal seam is only 0.42mD, the three-dimensional fracture network formed after fracturing greatly improves the permeability; at the same time, the single-hole gas flow after fracturing is increased by 0.08-0.21m³ / min; under the conventional application of the carbon dioxide gas expansion fracturing technology, the fracturing influence radius is 2.2-4.7 meters, the effective extraction radius after fracturing of low-permeability coal seams is 7.8-12.7 meters, which can be adjusted by the fracturing tube parameters and drilling arrangement; and the number of cracks in the coal body after fracturing increases significantly, the spatial distribution is more uniform, and the fractal dimension of the cracks increases by 43%-62%. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the overall structure diagram of the present application.

[0016] Figure 2 This is a schematic diagram of the internal structure of the stabilization chamber of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure of part of the coal cleaning mechanism of the present invention.

[0018] Figure 4 This is a schematic diagram of the internal structure of the rotating rod of the present invention.

[0019] Figure 5 This is a schematic diagram of the structure of part of the collection mechanism of the present invention.

[0020] Figure 6 This is a schematic diagram of the internal structure of the collection box of the present invention.

[0021] In the diagram: 101. Equipment body; 1. Coal cleaning mechanism; 2. Collection mechanism; 11. Movable pipe; 12. Limiting groove; 13. Rotating rod; 14. Limiting plate; 15. Movable ring; 16. Connecting pipe; 17. Cleaning scraper; 18. Tapered rod; 19. Threaded rod; 21. Feed box; 22. Through groove; 23. Empty groove; 24. Collection box; 25. Feed chute; 26. Trapezoidal block; 31. Guide rail; 32. Slot; 41. Support plate; 51. Rotating shaft; 52. Small gear; 53. Large gear; 61. Stabilizing box; 71. First motor; 72. Second motor. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example: Figures 1-6 As shown, this invention discloses a coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction device, and provides the following two embodiments: Example 1: Includes a device body 101. The top of the device body 101 is provided with a coal cleaning mechanism 1, which is used to clean and scrape coal and rock fragments on the inner wall of the hole. At the same time, a collection mechanism 2 is provided below the coal cleaning mechanism 1, which is used to collect the removed coal and rock fragments. The coal cleaning mechanism 1 comprises a movable pipe 11 rotatably installed inside the equipment body 101, the inside of the movable pipe 11 is provided with annularly distributed limiting grooves 12, the inside of the movable pipe 11 movably provided with a rotating rod 13, the outside of the rotating rod 13 is fixedly installed with annularly distributed limiting plates 14, a plurality of limiting plates 14 are movably clamped in the corresponding limiting grooves 12 respectively, the inside of the rotating rod 13 movably provided with a movable ring 15, one side of the rotating rod 13 is fixedly installed with a connecting pipe 16, the outside of the connecting pipe 16 is fixedly installed with annularly distributed cleaning scrapers 17, one end of the connecting pipe 16 away from the rotating rod 13 is fixedly installed with a tapered rod 18, the inside of the equipment body 101 is rotatably provided with a threaded rod 19, and the movable ring 15 is threadedly sleeved on the outside of the threaded rod 19.

[0024] The difference between the second embodiment and the first embodiment is that the collecting mechanism 2 comprises a feeding box 21 fixedly connected with the equipment body 101, the inside of the feeding box 21 is in an inclined state, a through slot 22 is formed in the side of the equipment body 101 close to the feeding box 21, an empty slot 23 is formed in the bottom of the equipment body 101, a collecting box 24 is slidably installed in the inside of the empty slot 23, a feeding slot 25 is formed in one side of the top of the collecting box 24, and trapezoidal blocks 26 in an inclined state are fixedly installed in the inside of the collecting box 24.

[0025] The inside wall lower surface of the empty slot 23 is fixedly installed with symmetrically distributed guide rails 31, the bottom of the collecting box 24 is provided with symmetrically distributed clamping grooves 32, and the two guide rails 31 respectively penetrate through the corresponding clamping grooves 32. Through the setting of the guide rails 31 and the clamping grooves 32, the stability of the collecting box 24 when moving is improved.

[0026] Both sides of the equipment body 101 are fixedly installed with support plates 41, and both ends of the movable pipe 11 are rotatably installed on the corresponding support plates 41. Through the setting of the support plates 41, the movable pipe 11 can be supported, and the stability and carrying capacity thereof are improved.

[0027] The outside of one of the support plates 41 is rotatably installed with a rotating shaft 51, the outside of the rotating shaft 51 is fixedly installed with a pinion 52, the outside of the pinion 52 is meshingly connected with a gear 53, the movable pipe 11 is fixedly connected with the gear 53, the rotating shaft 51 is driven to rotate, the rotating shaft 51 drives the gear 53 to rotate through the pinion 52, and the rotation of the movable pipe 11 is realized.

[0028] The outside of one of the support plates 41 is fixedly installed with a stabilizing box 61, the threaded rod 19 is rotatably installed on the top of the stabilizing box 61, and the pinion 52 and the gear 53 are located in the inside of the stabilizing box 61. Through the setting of the stabilizing box 61, the threaded rod 19 can be supported to rotate smoothly, the pinion 52 and the gear 53 can be prevented from being exposed to the outside and affected by dust, and the service life thereof is improved.

[0029] One end of the threaded rod 19 is coaxially fixedly installed with a first motor 71, and one end of the rotating shaft 51 is coaxially fixedly installed with a second motor 72, and by arranging the first motor 71 and the second motor 72, power can be provided for the threaded rod 19 and the rotating shaft 51, so that they can rotate smoothly.

[0030] The application also discloses a coal seam CO2 phase change perforation fracturing and gas extraction method. Step one, move the device to the target drilling hole, align the conical rod with the drilling hole, push the movable ring by driving the threaded rod, drive the cleaning assembly into the drilling hole until the connecting pipe is fully inserted, then rotate the movable pipe to rotate the cleaning scraper, and scrape off the coal rock fragments on the hole wall, then drive the threaded rod in the opposite direction, and push out the hole fragments when the conical rod is reset, and the cleaning is completed. Step two, send the fracturing pipe with the activator into the cleaned drilling hole, connect the high-pressure filling device to the fracturing pipe, inject a certain amount of liquid CO2, then close the filling valve, remove the pipeline and check the activator line, and move away the filling device. Step three, personnel evacuate to the safety zone and set up a warning, start the activator remotely, liquid CO2 absorbs heat and gasifies into gas in milliseconds, expands 600-800 times in volume, the pressure in the pipe reaches 30-80 MPa, and finally the pressure breaks through the coal rock strength threshold, forming a fracture network to dredge the gas channel.

[0031] Meanwhile, the contents not described in detail in the specification are all prior art known to those skilled in the art.

[0032] Working principle: first, move the device body 101 to the vicinity of the hole to be cleaned, align the conical rod 18 with the hole, then drive the threaded rod 19 to rotate by starting the first motor 71, and drive the movable ring 15 to move towards the hole, the movable ring 15 drives the rotating rod 13, the connecting pipe 16 and the conical rod 18 to move, and the limiting plate 14 moves in the limiting groove 12, until the connecting pipe 16 completely enters the hole, at this time, the rotating shaft 51 is driven to rotate by starting the second motor 72, the rotating shaft 51 drives the large gear 53 to rotate through the pinion 52, and the large gear 53 drives the movable pipe 11 to rotate, so that the limiting groove 12 drives the rotating rod 13 to rotate through the limiting plate 14, the rotating rod 13 drives the connecting pipe 16 and the cleaning scraper 17 to rotate, so that the cleaning scraper 17 scrapes off the coal rock fragments on the inner wall of the hole, and falls from the inner wall to the inside of the hole, the connecting pipe 16 and the conical rod 18 are reset by driving the threaded rod 19 in the opposite direction, and the coal rock fragments in the hole are pushed out by the conical rod 18 at the same time, thereby completing the whole coal rock fragment cleaning process. When the conical rod 18 pushes the coal rock pieces out from the hole, the coal rock pieces fall into the feeding box 21, enter the through slot 22 and the feeding groove 25 through the inclined surface inside the feeding box 21, and are collected into the collecting box 24, and the trapezoidal block 26 inside the collecting box 24 can convey the coal rock pieces to the middle of the collecting box 24, so that the coal rock pieces are prevented from being accumulated at the feeding groove 25 to affect the entry of subsequent coal rock pieces.

[0034] It is to be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0035] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and alterations can be made therein without departing from the spirit and scope of the application, which is defined by the following claims and their equivalents.

Claims

1. A coal seam CO2 phase change perforation fracturing gas extraction device, comprising a device body (101), characterized in that: The top of the equipment body (101) is provided with a coal cleaning mechanism (1) for cleaning and scraping coal and rock fragments on the inner wall of the hole. At the same time, a collection mechanism (2) is provided below the coal cleaning mechanism (1) for collecting the removed coal and rock fragments. The coal cleaning mechanism (1) includes a movable tube (11) rotatably installed inside the equipment body (101). The movable tube (11) has annularly distributed limiting grooves (12) inside. A rotating rod (13) is movably installed inside the movable tube (11). Annularly distributed limiting plates (14) are fixedly installed on the outside of the rotating rod (13). Multiple limiting plates (14) are movably locked in the corresponding limiting grooves (12). A movable ring (15) is movably installed inside the rotating rod (13). A connecting pipe (16) is fixedly installed on one side of the rotating rod (13). Annularly distributed cleaning scrapers (17) are fixedly installed on the outside of the connecting pipe (16). A tapered rod (18) is fixedly installed at the end of the connecting pipe (16) away from the rotating rod (13). A threaded rod (19) is rotatably installed inside the equipment body (101). The movable ring (15) is threadedly sleeved on the outside of the threaded rod (19).

2. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 1, characterized in that, The collecting mechanism (2) includes a feeding box (21) fixedly connected to the equipment body (101). The inside of the feeding box (21) is inclined. A through groove (22) is provided on the side of the equipment body (101) near the feeding box (21). A hollow groove (23) is provided at the bottom of the equipment body (101). A collecting box (24) is slidably installed inside the hollow groove (23). A feeding groove (25) is provided on the top side of the collecting box (24). Trapezoidal blocks (26) are fixedly installed inside the collecting box (24) in an inclined state.

3. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 2, characterized in that, The inner wall of the empty slot (23) is fixedly installed with symmetrically distributed guide rails (31), and the bottom of the collection box (24) is provided with symmetrically distributed slots (32), with the two guide rails (31) passing through the corresponding slots (32).

4. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 1, characterized in that, Both sides of the device body (101) are fixedly installed with support plates (41), and the two ends of the movable tube (11) are respectively rotatably installed on the corresponding support plates (41).

5. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 4, characterized in that, A rotating shaft (51) is rotatably mounted on the outer side of one of the support plates (41), a small gear (52) is fixedly mounted on the outer side of the rotating shaft (51), a large gear (53) is meshed on the outer side of the small gear (52), and the movable tube (11) and the large gear (53) are fixedly connected.

6. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 5, characterized in that, A stabilizing box (61) is fixedly installed on the outside of one of the support plates (41), the threaded rod (19) is rotatably installed on the top of the stabilizing box (61), and the pinion (52) and gear (53) are both located inside the stabilizing box (61).

7. The coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 6, characterized in that, One end of the threaded rod (19) is coaxially fixedly mounted with a first motor (71), and one end of the rotating shaft (51) is coaxially fixedly mounted with a second motor (72).

8. A method for coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction, implemented based on the coal seam CO2 phase change perforation fracturing and permeability enhancement gas extraction equipment as described in claim 1, characterized in that, Includes the following steps: Step 1: Move the equipment to the target borehole, align the tapered rod (18) with the borehole, and push the movable ring (15) through the drive threaded rod (19) to drive the coal cleaning mechanism (1) into the borehole until the connecting pipe (16) is fully inserted. Then rotate the movable pipe (11) to make the cleaning scraper (17) rotate and scrape off the coal and rock fragments on the borehole wall. When the tapered rod (18) is reset by reversing the drive threaded rod (19), the coal block in the borehole is pushed out, and the cleaning is completed. Step 2: Insert the fracturing tube with the activator into the cleaned borehole, connect the high-pressure filling equipment to the fracturing tube, inject a fixed amount of liquid CO2, then close the filling valve, disconnect the pipeline and check the activator circuit, and remove the filling equipment. Step 3: Personnel are evacuated to a safe area and a warning is set up. The activator is activated remotely. Liquid CO2 absorbs heat and vaporizes into gas within milliseconds, expanding in volume by 600-800 times. The pressure inside the pipe reaches 30-80 MPa. Finally, the pressure exceeds the strength threshold of the coal and rock, forming a fracture network to clear the gas passage.

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