A bottom-hole pressurization device and system for improving the permeability of horizontal coalbed methane wells.

Abstract

This invention discloses a bottom-hole pressurization device and system for improving the permeability of horizontal coalbed methane wells. The device includes a drive unit, a locking mechanism, an opening and closing mechanism, a mounting cylinder, and a housing. The housing can be connected to both an oil pipe and a screen pipe. The locking mechanism includes a gear, a rack, and a locking element. The gear is connected to the drive unit and meshes with the rack. The locking element is connected to the end of the rack. The drive unit can drive the gear to rotate, causing the rack and locking element to reciprocate. The opening and closing mechanism includes a telescopic rod, multiple sets of ribs, and a sealing layer covering the ribs. The telescopic rod is connected to the locking element. A perforated mesh frame is provided inside the housing. The two ends of the ribs are connected to the telescopic rod and the center of the mesh frame, respectively. The locking element can drive the telescopic rod to extend and retract. When the telescopic rod is extended, the ribs open the sealing layer to seal the mesh frame. This device can generate high-pressure liquid with fluctuating pressure. The high-pressure liquid periodically impacts the well wall, achieving wellbore unblocking and improving the permeability of the near-well coal seam.

Description

Technical Field

[0001] This invention relates to the field of oil and gas production equipment, and in particular to a bottom-hole pressurization device and system for enhancing the permeability of horizontal coalbed methane wells. Background Technology

[0002] In recent years, with the increasing development of unconventional energy sources worldwide, coalbed methane has attracted global attention. Coalbed methane resources are abundant and widely distributed, but its development has been relatively slow due to the difficulty of extraction. Factors restricting coalbed methane extraction include low coal seam permeability, blockage of bottom-hole fracture channels, and coal dust accumulation.

[0003] Currently, horizontal well development technology for coalbed methane has become the mainstream in China. After a period of production, some horizontal wells become low-production wells. The main reasons for the low production of horizontal wells are the accumulation of coal powder in the casing and the blockage of cracks around the casing. Summary of the Invention

[0004] To enrich the product range of bottom-hole booster devices for coalbed methane horizontal wells, increase the selection space for bottom-hole booster methods for coalbed methane horizontal wells, and increase coal seam permeability, this invention provides a bottom-hole booster device and system for enhancing the permeability of coalbed methane horizontal wells.

[0005] In a first aspect, embodiments of the present invention provide a bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells, comprising a drive device, a locking mechanism, an opening and closing mechanism, an installation cylinder, and a housing;

[0006] The driving device and the locking mechanism are disposed inside the mounting cylinder; the mounting cylinder and the opening and closing mechanism are disposed inside the housing; the housing can be connected to the oil pipe and the screen pipe respectively;

[0007] The locking mechanism includes a gear, a rack, and a locking member; the gear is connected to the driving device and meshes with the rack, the locking member is connected to the end of the rack, and the driving device can drive the gear to rotate so as to drive the rack and the locking member to reciprocate.

[0008] The mounting cylinder is provided with a card interface, and the card connector can be snapped into the card interface;

[0009] The opening and closing mechanism includes a telescopic rod, multiple sets of umbrella ribs, and a sealing layer covering the multiple sets of umbrella ribs; the telescopic rod is connected to the snap-fit ​​component; a hollow mesh frame is provided inside the housing, and the two ends of the umbrella ribs are respectively connected to the telescopic rod and the center of the mesh frame;

[0010] The snap-fit ​​component can drive the telescopic rod to extend and retract. When the telescopic rod is extended, the umbrella ribs open the sealing layer to seal the mesh frame.

[0011] In one or more alternative embodiments, the bottom-hole booster device further includes an impeller structure;

[0012] The impeller structure includes a fixed shaft and an impeller sleeved on the fixed shaft, and the impeller can rotate relative to the fixed shaft under the action of fluid impact force;

[0013] The fixing shaft is fixed to the side of the mesh frame away from the umbrella ribs.

[0014] In one or more alternative embodiments, the inlet end of the housing is provided with an oil pipe connection portion, which is used to connect an oil pipe;

[0015] The outlet end of the shell is provided with a screen tube connection part, which is used to connect the screen tube.

[0016] In one or more alternative embodiments, when the screen tube connection is connected to the screen tube, the impeller structure is located inside the screen tube.

[0017] In one or more alternative embodiments, the bottom-hole pressurization device further includes a pressure sensor and a controller;

[0018] The pressure sensor is located at one end of the mounting cylinder near the oil pipe and is used to monitor the fluid pressure flowing into the housing;

[0019] The controller is connected to the pressure sensor and the drive device respectively; the controller can acquire the pressure monitoring results of the pressure sensor and control the drive device to operate according to the pressure monitoring results.

[0020] In one or more alternative embodiments, a diaphragm is provided at one end of the mounting cylinder near the oil pipe, and the pressure sensor is in close contact with the diaphragm.

[0021] In one or more alternative embodiments, the pressure sensor is a contact-type pressure sensor.

[0022] In one or more alternative embodiments, the umbrella ribs include a hinged first link and a second link.

[0023] In one or more alternative embodiments, the bottom-hole booster device further includes a support structure;

[0024] The support structure can be installed between the screen tube and the guide shoe;

[0025] The support structure includes a short tube, two pins, and a first support rod, an elastic element, and a second support rod connected in sequence.

[0026] The short tube can be longitudinally fixed to the shoe guide. The first support rod, the elastic element and the second support rod are disposed inside the short tube. The two pins are radially inserted into the short tube and lock the elastic element in a compressed state.

[0027] The two pins can release the locking of the elastic element under the action of fluid impact force, so that the first support rod and the second support rod extend out of the short pipe and abut against the inner wall of the well barrel.

[0028] Secondly, embodiments of the present invention provide a bottom-hole pressurization system for improving the permeability of horizontal coalbed methane wells, comprising the bottom-hole pressurization device for improving the permeability of horizontal coalbed methane wells as described in the first aspect, tubing, and screen pipe.

[0029] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0030] The bottom-hole pressurization device for improving the permeability of horizontal coalbed methane wells provided in this embodiment of the invention uses a drive device to open or close the locking mechanism, causing intermittent pressure surges within the bottom-hole tubing. This generates high-pressure liquid with fluctuating pressure, which periodically impacts the well wall, effectively cleaning coal dust, clearing the wellbore, causing fatigue damage to the coal seam, opening coal seam fractures, and improving the permeability of the near-well coal seam. By connecting the umbrella ribs to the grid frame and telescopic rods respectively, an umbrella-shaped opening and closing structure is formed. When the umbrella ribs are not open, they occupy less space, avoiding obstruction of liquid passage. By setting a sealing layer on the surface of the umbrella ribs, the shell is sealed when the umbrella ribs are open, thereby achieving pressure buildup within the tubing and significantly increasing the pressure and impact force of the liquid within the tubing.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram of the bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells provided in an embodiment of the present invention;

[0035] Figure 2This is a schematic diagram of the bottom-hole pressurization system for enhancing the permeability of horizontal coalbed methane wells provided in an embodiment of the present invention.

[0036] In the picture:

[0037] 1. Drive unit;

[0038] 2. Locking mechanism; 21. Gear; 22. Rack; 23. Snap-fit ​​component;

[0039] 3. Opening and closing mechanism; 31. Telescopic rod; 32. Umbrella ribs; 321. First connecting rod; 322. Second connecting rod; 33. Sealing layer;

[0040] 4. Mounting cylinder; 41. Card interface;

[0041] 5. Shell; 51. Frame; 52. Oil pipe connection; 53. Screen pipe connection;

[0042] 6. Impeller structure; 61. Fixed shaft; 62. Impeller;

[0043] 7. Pressure sensor;

[0044] 8. Diaphragm;

[0045] 9. Supporting structure; 91. Short pipe;

[0046] 10. Tubing; 101. Vertical tubing; 102. Horizontal tubing; 103. Steering tubing; 11. Screen pipe; 12. Water storage tank; 13. Fracturing truck; 131. Injection pipe; 14. Generator; 15. Derrick; 16. Hoist; 17. Suspension device; 18. Flange; 19. Guide shoe;

[0047] 100. Bottom-of-well pressurization device. Detailed Implementation

[0048] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0049] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," and "rear," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying 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, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] The inventors discovered that when coal dust accumulation and crack blockage around the casing cause a decrease in the production of horizontal wells, conventional hydraulic flushing cannot improve permeability due to its low pressure, and there are problems such as incomplete flushing of coal dust inside the casing.

[0052] Based on this, the present invention provides a bottom-hole pressurization device and system for improving the permeability of horizontal coalbed methane wells, which will be described in detail below through specific embodiments.

[0053] Example 1

[0054] This invention provides a bottom-hole booster device 100 (hereinafter referred to as bottom-hole booster device 100) for improving the permeability of horizontal coalbed methane wells, referring to... Figure 1 and Figure 2 As shown, it includes a drive device 1, a locking mechanism 2, an opening and closing mechanism 3, a mounting cylinder 4, and a housing 5;

[0055] The drive unit 1 and the locking mechanism 2 are located inside the mounting cylinder 4; the mounting cylinder 4 and the opening and closing mechanism 3 are located inside the housing 5; the housing 5 can be connected to the oil pipe 10 and the screen pipe 11 respectively.

[0056] The locking mechanism 2 includes a gear 21, a rack 22, and a locking member 23; the gear 21 is connected to the drive device 1 and meshes with the rack 22, and the locking member 23 is connected to the end of the rack 22. The drive device 1 can drive the gear 21 to rotate, so as to drive the rack 22 and the locking member 23 to reciprocate.

[0057] The mounting cylinder 4 is provided with a card interface 41, and the card connector 23 can be inserted into the card interface 41;

[0058] The opening and closing mechanism 3 includes a telescopic rod 31, multiple sets of umbrella ribs 32 and a sealing layer 33 covering the multiple sets of umbrella ribs 32; the telescopic rod 31 is connected to a snap-fit ​​23; a hollow mesh frame 51 is provided inside the housing 5, and the two ends of the umbrella ribs 32 are respectively connected to the center of the telescopic rod 31 and the center of the mesh frame 51.

[0059] The snap-fit ​​23 can drive the telescopic rod 31 to extend and retract. When the telescopic rod 31 is extended, the umbrella rib 32 opens the sealing layer 33 to seal the grid frame 51.

[0060] In this embodiment of the invention, the bottom-hole pressurization device 100 can be installed in the bottom-hole tubing of a horizontal coalbed methane well, and its housing 5 can be connected to the tubing 10 and the screen pipe 11 respectively. Specifically, the inlet end of the housing 5 is provided with a tubing 10 connection part 52, which is used to connect the tubing 10; the outlet end of the housing 5 is provided with a screen pipe 11 connection part 53, which is used to connect the screen pipe 11. The high-pressure liquid injected from the surface fracturing truck 13 enters the bottom-hole pressurization device 100 through the tubing 10 for further pressurization, then flows into the screen pipe 11 and impacts the coal seam around the screen pipe 11, thereby achieving the effect of increasing the permeability of the coal seam near the well.

[0061] In this embodiment of the invention, the driving device 1 can be an electric motor, equipped with a rotating shaft (not shown in the figure), which can rotate clockwise and counterclockwise. A gear 21 is connected to the rotating shaft, and the gear 21 and rack 22 together form a gear 21 rack 22 mechanism. Through the gear 21 rack 22 mechanism, the torque output by the driving device 1 can be converted into the linear reciprocating motion of the rack 22 to drive the snap-fit ​​member 23 to move. A power source (not shown in the figure) is also provided inside the mounting cylinder 4. This power source is connected to the driving device 1 and can supply power to the driving device 1. Specifically, the power source can be a battery with a capacity of about 20,000 mAh.

[0062] In this embodiment of the invention, the opening and closing mechanism 3 can open and close in an umbrella shape under the pushing and pulling action of the telescopic rod 31, thereby sealing or unsealing the mesh frame 51, realizing intermittent pressure release in the bottom hole tubing, further increasing the pressure of the high-pressure liquid, strengthening the impact on the near-well coal seam, reducing coal dust accumulation, and improving the permeability of the near-well coal seam. The number of umbrella ribs 32 can be reasonably set according to factors such as the inner diameter of the shell 5 and the flow rate and velocity of the high-pressure liquid, as long as it has sufficient supporting force and ensures that the high-pressure liquid can pass smoothly through the shell 5. Here, no specific limitation is made.

[0063] In one specific embodiment, reference is made to Figure 1As shown, the bottom-hole pressurization device 100 also includes an impeller structure 6. The impeller structure 6 may include a fixed shaft 61 and an impeller 62 sleeved on the fixed shaft 61. The fixed shaft 61 is fixed to the side of the mesh frame 51 away from the umbrella rib 32 and is located at the center of the mesh frame 51. When the high-pressure liquid is released after being pressurized in the housing 5, the impeller 62 can rotate rapidly relative to the fixed shaft 61 under the impact force of the high-pressure liquid. Furthermore, when the screen pipe 11 connection part 53 is connected to the screen pipe 11, the impeller structure 6 is located inside the screen pipe 11. The high-speed rotation of the impeller 62 can increase the radial impact force of the high-pressure liquid on the screen pipe 11, thereby enhancing the permeability of the near-well coal seam and the wellbore unblocking effect.

[0064] In one specific embodiment, reference is made to Figure 1 As shown, the bottom-hole booster device 100 also includes a pressure sensor 7. The pressure sensor 7 is located at one end of the mounting cylinder 4 near the tubing 10 and is used to monitor the pressure of the high-pressure fluid flowing into the housing 5. Specifically, a diaphragm 8 is provided at one end of the mounting cylinder 4 near the tubing 10. The pressure sensor 7 is installed inside the mounting cylinder 4, tightly attached to the diaphragm 8. This pressure sensor 7 is a contact-type pressure sensor. When the high-pressure fluid flows into the housing 5, it impacts the diaphragm 8, causing the pressure sensor 7 to detect the pressure on the diaphragm 8, thus obtaining the pressure of the high-pressure fluid. By providing a diaphragm 8 at the end opening of the mounting cylinder 4, direct impact of the high-pressure fluid on the pressure sensor 7 and other components inside the mounting cylinder 4 can be prevented, avoiding damage to the pressure sensor 7 and other components, and extending the service life of the bottom-hole booster device 100.

[0065] In one specific embodiment, the bottom-hole pressurization device 100 further includes a controller (not shown in the figure), which is connected to the pressure sensor 7 and the drive device 1 respectively; the controller can acquire the pressure monitoring results of the pressure sensor 7 and control the drive device 1 to operate according to the pressure monitoring results. For example, the minimum pressure threshold of the high-pressure liquid is set to 20 MPa and the maximum pressure threshold is set to 50 MPa. When the pressure sensor 7 detects that the pressure of the high-pressure liquid is lower than 20 MPa, the controller controls the drive device 1 to drive the gear 21 to rotate counterclockwise, so that the rack 22 extends to push the telescopic rod 31 to extend and open the umbrella rib 32, thereby opening the opening and closing mechanism 3 to block the mesh frame 51 (the outlet end of the shell 5), so that the high-pressure liquid in the oil pipe 10 and the shell 5 is pressurized. When the pressure sensor 7 detects that the pressure of the high-pressure liquid reaches 50 MPa, the controller controls the drive device 1 to drive the gear 21 to rotate clockwise, so that the rack 22 retracts to pull the telescopic rod to retract and close the umbrella rib 32, thereby closing the opening and closing mechanism 3, releasing the blockage of the outlet end of the shell 5. The pressurized high-pressure liquid can then impact the near-well coal seam, greatly improving the wellbore dredging efficiency and the near-well coal seam permeability.

[0066] In one specific embodiment, reference is made to Figure 1As shown, the umbrella rib 32 includes a hinged first link 321 and a second link 322. The end of the first link 321 is hinged to the telescopic rod 31, and the end of the second link 322 is hinged to the center of the mesh frame 51. The lengths of the first link 321 and the second link 322 can be reasonably set according to the inner diameter of the shell 5, and are not specifically limited here. The hinge method between the first link 321 and the second link 322, as well as between the first link 321 and the second link 322 and the outside, can be referred to the detailed description in the prior art, and will not be repeated here.

[0067] In one specific embodiment, the diameter of the housing 5 can be larger than the outer diameter of the oil pipe 10 and the screen pipe 11 to avoid the arrangement of the internal components of the housing 5 from obstructing the flow of high-pressure liquid. Its specific diameter can be reasonably set according to actual needs, and is not specifically limited here.

[0068] In one specific embodiment, reference is made to Figure 1 As shown, the bottom-hole pressurization device 100 also includes a support structure 9 that can be disposed between the screen pipe 11 and the guide shoe 19. The support structure 9 includes a short pipe 91, two pins (not shown in the figure), and a first support rod (not shown in the figure), an elastic element (not shown in the figure), and a second support rod (not shown in the figure) connected in sequence. The short pipe 91 can be longitudinally fixed to the guide shoe 19. The first support rod, the elastic element, and the second support rod are disposed inside the short pipe 91, and two radial through holes (not shown in the figure) are respectively opened in the middle part of the short pipe 91. The two pins are radially inserted into the two radial through holes of the short pipe 91, locking the elastic element in a compressed state. When the high-pressure liquid flows out from the shell 5, the two pins can be pushed out of the short pipe 91 by the impact force of the high-pressure liquid, thereby releasing the locking of the elastic element. This allows the first support rod and the second support rod to extend out of the short pipe 91 and abut against the inner wall of the wellbore under the elastic force of the elastic element, thereby preventing the end of the tubing from swinging significantly in the wellbore under the impact force of the high-pressure fluid and preventing damage to the tubing and coal seam.

[0069] In this embodiment of the invention, the specific process of further pressurizing high-pressure liquid at the bottom of a coalbed methane horizontal well using the bottom-hole pressurization device 100 may include:

[0070] High-pressure liquid is injected into the oil pipe 10 through the fracturing truck 13 on the ground;

[0071] High-pressure liquid flows through the tubing 10 and the housing 5 of the bottom-hole booster device 100, and impacts the coal seam near the well in the screen pipe 11 section. The high-pressure liquid passing through the housing 5 also impacts the diaphragm 8, causing the pressure sensor 7 to monitor the pressure of the high-pressure liquid.

[0072] When the monitored high-pressure liquid pressure is less than the minimum pressure threshold, the control drive device 1 drives the drive gear 21 to rotate counterclockwise, causing the rack 22 to extend in the direction of the screen tube 11, thereby pushing the snap-fit ​​23 to move, so that the telescopic rod 31 extends to open the opening and closing mechanism 3. When the snap-fit ​​23 snaps into the snap-fit ​​interface 41, the opening and closing mechanism 3 is fully opened, completely blocking the outlet of the housing 5. At this point, the high-pressure liquid begins to pressurize.

[0073] When the monitored high-pressure liquid pressure reaches the maximum pressure threshold, it indicates that the pressure buildup is complete. The control drive device 1 rotates clockwise, driving the rack 22 to retract towards the oil pipe 10, thereby pushing the locking member 23 to move. This causes the telescopic rod 31 to retract the opening and closing mechanism 3. When the locking member 23 disengages from the locking interface 41 and returns to the origin, the opening and closing mechanism 3 is fully retracted, and the outlet end of the housing 5 is completely unblocked, achieving pressure release. The high-pressure liquid after further pressurization flows out of the housing 5 and impacts the impeller 62. The high-speed rotation of the impeller 62 causes the pressurized high-pressure liquid to impact the screen pipe 11 and the coal seam near the well.

[0074] When the high-pressure liquid impacts the screen pipe 11 after further pressurization, the pin of the support structure 9 disengages from the short pipe 91, and the first support rod and the second support rod pop out and abut against the inner wall of the well barrel to prevent the tubing string from swinging significantly.

[0075] When the high-pressure liquid pressure drops below the minimum pressure threshold again, the gear 21 is driven to rotate counterclockwise again, and the cycle is repeated to achieve intermittent pressure build-up and release, thereby clearing the well shaft and increasing the permeability of the coal seam near the well.

[0076] The bottom-hole pressurization device 100 for improving the permeability of horizontal coalbed methane wells provided in this embodiment of the invention drives the locking mechanism 2 to open or close the opening and closing mechanism 3 through the driving device 1, so that intermittent pressure excitation is formed in the bottom-hole tubing, generating high-pressure liquid with fluctuating pressure. The high-pressure liquid periodically impacts the well wall, effectively cleaning coal dust, clearing the wellbore, causing fatigue failure of the coal seam, opening coal seam fractures, and improving the permeability of the near-well coal seam. By connecting the umbrella ribs 32 to the grid frame 51 and the telescopic rod 31 respectively, an umbrella-shaped opening and closing structure is formed. When the umbrella ribs 32 are not opened, they occupy less space and avoid obstructing the passage of liquid. By setting a sealing layer 33 on the surface of the umbrella ribs 32, the shell 5 is sealed when the umbrella ribs 32 are opened, thereby achieving pressure build-up in the tubing and greatly increasing the pressure and impact force of the liquid in the tubing.

[0077] Example 2

[0078] Based on the same inventive concept, embodiments of the present invention also provide a bottom-hole pressurization system for enhancing the permeability of horizontal coalbed methane wells (hereinafter referred to as the bottom-hole pressurization system), referring to... Figure 2As shown, it includes the bottom-hole booster device 100, tubing 10, and screen pipe 11 for improving the permeability of horizontal coalbed methane wells as described in Embodiment 1; the bottom-hole booster device 100 is connected to the tubing 10 and the screen pipe 11 respectively.

[0079] In this embodiment of the invention, reference is made to Figure 2 As shown, the bottom-hole pressurization system also includes a water storage tank 12 and a fracturing truck 13 installed at the wellhead. The water storage tank 12 is connected to the fracturing truck 13, and the injection pipe 131 of the fracturing truck 13 is connected to the oil pipe 10 inside the wellbore. The fracturing truck 13 can pressurize the liquid to obtain high-pressure liquid and inject the high-pressure liquid into the oil pipe 10.

[0080] In this embodiment of the invention, reference is made to Figure 2 As shown, the bottom-hole pressurization system also includes a generator 14, a derrick 15, and a hoist 16 located at the wellhead. The derrick 15 is positioned directly above the wellhead, the hoist 16 is mounted on the derrick 15, and the generator 14 is located on the ground and connected to the hoist 16. The hoist 16 is capable of lifting the tubing string inside the wellbore.

[0081] In this embodiment of the invention, reference is made to Figure 2 As shown, the bottomhole pressurization system also includes a hanger 17, a flange 18, and a guide shoe 19; the tubing 10 includes a vertical tubing 101 installed in the vertical section, a horizontal tubing 102 installed in the horizontal section, and a steering tubing 103 installed in the directional section; the hanger 17 is installed between the vertical tubing 101 and the steering tubing 103 for connecting the two; the flange 18 is installed between the steering tubing 103 and the horizontal tubing 102 for connecting the two. The guide shoe 19 is installed at the end of the integral tubing string and has a guiding function when the tubing string is lowered into the wellbore.

[0082] In this embodiment of the invention, the specific process of using the bottom-hole pressurization system to enhance the permeability of a horizontal coalbed methane well may include:

[0083] The bottom-hole booster device 100 described in Embodiment 1 is fixedly connected to the screen pipe 11 and the oil pipe 10 respectively;

[0084] Determine the lengths of the horizontal and vertical well sections respectively, and send the bottom-hole booster device 100 to the target horizontal well section at the bottom of the well through the tubing 10;

[0085] The fracturing truck 13 on the ground is started to pressurize the liquid in the water storage tank 12 to obtain high-pressure liquid;

[0086] High-pressure liquid is injected into the oil pipe 10, and intermittent pressure is released through the bottom-hole pressurization device 100, thereby intermittently flushing the coal dust blocking the bottom of the well;

[0087] After a target well section is flushed, the tubing 10 is dragged or extended a preset distance by the hoist 16 to continue flushing the next target well section. Furthermore, any target well section can be flushed multiple times. When the return fluid gradually becomes clear, the flushing of the target well section is stopped. This process is repeated until the entire horizontal well section is flushed.

[0088] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A bottom-hole pressurization device for enhancing permeability in horizontal coalbed methane wells, characterized in that, Includes a drive unit, locking mechanism, opening and closing mechanism, mounting cylinder, and housing; The driving device and the locking mechanism are disposed inside the mounting cylinder; the mounting cylinder and the opening and closing mechanism are disposed inside the housing; the housing can be connected to the oil pipe and the screen pipe respectively; The locking mechanism includes a gear, a rack, and a locking member; the gear is connected to the driving device and meshes with the rack, the locking member is connected to the end of the rack, and the driving device can drive the gear to rotate so as to drive the rack and the locking member to reciprocate. The mounting cylinder is provided with a card interface, and the card connector can be snapped into the card interface; The opening and closing mechanism includes a telescopic rod, multiple sets of umbrella ribs, and a sealing layer covering the multiple sets of umbrella ribs; The telescopic rod is connected to the snap-fit ​​component; a hollowed-out mesh frame is provided inside the housing, and the two ends of the umbrella rib are respectively connected to the telescopic rod and the center of the mesh frame; The snap-fit ​​component can drive the telescopic rod to extend and retract. When the telescopic rod is extended, the umbrella ribs open the sealing layer to seal the mesh frame.

2. The bottom-hole pressurization device for enhancing permeability in horizontal coalbed methane wells according to claim 1, characterized in that, The bottom-hole booster device also includes an impeller structure; The impeller structure includes a fixed shaft and an impeller sleeved on the fixed shaft, and the impeller can rotate relative to the fixed shaft under the action of fluid impact force; The fixing shaft is fixed to the side of the mesh frame away from the umbrella ribs.

3. The bottom-hole pressurization device for enhancing permeability in horizontal coalbed methane wells according to claim 2, characterized in that, The inlet end of the housing is provided with an oil pipe connection part, which is used to connect an oil pipe. The outlet end of the shell is provided with a screen tube connection part, which is used to connect the screen tube.

4. The bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells according to claim 3, characterized in that, When the screen tube connection is connected to the screen tube, the impeller structure is located inside the screen tube.

5. The bottom-hole pressurization device for enhancing permeability in horizontal coalbed methane wells according to claim 1, characterized in that, The bottom-hole pressurization device also includes a pressure sensor and a controller; The pressure sensor is located at one end of the mounting cylinder near the oil pipe and is used to monitor the fluid pressure flowing into the housing; The controller is connected to the pressure sensor and the drive device respectively; The controller can acquire the pressure monitoring results of the pressure sensor and control the drive device to operate based on the pressure monitoring results.

6. The bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells according to claim 5, characterized in that, A diaphragm is provided at one end of the mounting cylinder near the oil pipe, and the pressure sensor is in close contact with the diaphragm.

7. The bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells according to claim 5, characterized in that, The pressure sensor is a contact-type pressure sensor.

8. The bottom-hole pressurization device for enhancing permeability in horizontal coalbed methane wells according to claim 1, characterized in that, The umbrella ribs include a hinged first link and a second link.

9. The bottom-hole pressurization device for enhancing the permeability of horizontal coalbed methane wells according to claim 1, characterized in that, The bottom-hole pressurization device also includes a support structure; The support structure can be installed between the screen tube and the guide shoe; The support structure includes a short tube, two pins, and a first support rod, an elastic element, and a second support rod connected in sequence. The short tube can be longitudinally fixed to the shoe guide. The first support rod, the elastic element and the second support rod are disposed inside the short tube. The two pins are radially inserted into the short tube and lock the elastic element in a compressed state. The two pins can release the locking of the elastic element under the action of fluid impact force, so that the first support rod and the second support rod extend out of the short pipe and abut against the inner wall of the well barrel.

10. A bottom-hole pressurization system for enhancing permeability in horizontal coalbed methane wells, characterized in that, Includes the bottom-hole booster device, tubing, and screen pipe for enhancing the permeability of horizontal coalbed methane wells as described in any one of claims 1-9.

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