Device and method for detecting gas tightness of coal mine gas extraction drilling hole

Abstract

The present application relates to the technical fields of coal mine gas extraction, and discloses a device and method for detecting the air tightness of a coal mine gas extraction borehole, comprising two sealing execution assemblies connected by a connecting rod, the bottom of the upper sealing execution assembly being provided with a detection module for detecting the air tightness between the two sealing execution assemblies, the sealing execution assembly comprising a mounting and connecting module, an expansion sealing module, two resistance-reducing guide modules and two fixing and limiting modules, the device and method for detecting the air tightness of a coal mine gas extraction borehole of the present application embodiment avoiding reliance on manual reading or simple instruments and improving the measurement accuracy and stability.

Description

Technical Field

[0001] This invention relates to the field of coal mine gas extraction technology, specifically to a device and method for detecting the airtightness of coal mine gas extraction boreholes. Background Technology

[0002] Coal mine gas drainage is a crucial safety production guarantee measure. Its efficiency and effectiveness largely depend on the structural integrity and sealing performance of the drainage borehole. Drainage boreholes, especially the sealed sections after grouting or cement sealing, as well as the sections with casing installed, need to have a high degree of airtightness to ensure that the drainage system can establish and maintain an effective negative pressure, thereby maximizing the extraction of gas from gas-bearing strata.

[0003] If the borehole is not airtight, that is, there are leaks of varying degrees, it will lead to a decrease in the negative pressure of the extraction, an increase in the ineffective extraction volume, and may even cause gas to escape back into the mine roadway, greatly increasing the risk of gas exceeding the limit and explosion. At present, the airtightness detection methods for coal mine extraction boreholes rely on manual reading or simple instruments, which are insufficient to capture minor leaks and are easily affected by external environmental interference (such as the operating status of the extraction system itself, air leakage in other areas, etc.). Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a device and method for detecting the airtightness of coal mine gas drainage boreholes, avoiding reliance on manual readings or simple instruments, and improving measurement accuracy and stability.

[0006] An embodiment of the present invention provides an airtightness testing device for coal mine gas drainage boreholes, comprising two sealing actuators connected by a connecting rod. A testing module for airtightness testing between the two actuators is disposed at the bottom of the upper sealing actuator. Each sealing actuator includes:

[0007] Mounting connection modules are used to mount equipment components;

[0008] An expansion sealing module is located in the middle of the mounting connection module and is used to fill the gap between the mounting connection module and the hole, and to seal and separate the hole.

[0009] Two drag-reducing guide modules are respectively set on the upper and lower sides of the mounting and connecting module to guide the mounting and connecting module when it moves in the hole and reduce the friction between the mounting and connecting module and the hole.

[0010] Two fixed limiting modules are respectively set between the drag-reducing guide module and the expansion sealing module, and are used to fix the connecting module installed in the hole.

[0011] The device and method for detecting the air tightness of coal mine gas drainage boreholes according to embodiments of the present invention avoids reliance on manual readings or simple instruments, thereby improving measurement accuracy and stability.

[0012] Furthermore, the installation connection module includes a frame, with mounting plates fixed to both the upper and lower sides of the frame by bolts, and guide frames fixed to the opposite sides of the two mounting plates by bolts. Two conical frames are bonded between the inner walls of both sides of the frame, and the two conical frames are arranged symmetrically.

[0013] Based on the aforementioned scheme, the expansion sealing module includes an airbag with one side bonded to a conical frame. A connecting air pipe is provided on the side of the airbag bonded to the conical frame. An external air pipe connected to an external air pump is provided through the frame. The external air pipe is connected to the connecting air pipe. A second electrically controlled valve is provided above the external air pipe connected to the connecting air pipe. The second electrically controlled valve is used to control the amount of gas in the airbag.

[0014] As a further embodiment of the present invention, the fixed limiting module includes multiple fixed frames fixed on the mounting plate and the top outer wall of the frame. Each fixed frame has two detachable rotating rods rotatably connected to one side, and the two rotating rods are arranged in parallel. The other end of the two rotating rods is rotatably connected to an arc-shaped clamp. The multiple arc-shaped clamps are combined to form a circle. The same number of servo motors as the fixed frames are fixed to the top outer wall of the mounting plate and the frame by bolts, and the output shaft of the servo motor is fixed to one of the two rotating rods arranged on the same fixed frame.

[0015] Furthermore, rubber pads are bonded to multiple sides of the various arc-shaped clamps, with the outer rubber pads used to increase friction with the holes.

[0016] Based on the aforementioned scheme, the two adjacent arc-shaped clamps are staggered in height.

[0017] As a further embodiment of the present invention, the drag-reducing guide module includes two electric push rods respectively fixed on opposite sides of two mounting plates. The movable end of the electric push rod passes through the mounting plate and is fixed to a connecting plate by bolts. The outer circumferential wall of the connecting plate is provided with multiple rotating grooves. A lever arm is rotatably connected in the rotating groove. The other end of the lever arm is rotatably connected to a support rod whose end is rotatably connected to the mounting plate. The other end of the support rod is provided with a roller.

[0018] Furthermore, the connecting rod includes multiple rods, with a threaded protrusion integrally formed on the top of the rod and a threaded hole at the bottom that mates with the threaded protrusion. The threaded protrusion between two adjacent rods is screwed into the threaded hole.

[0019] Based on the aforementioned scheme, the detection module includes a nozzle fixed below the lower guide frame inside the upper mounting and connecting module. A first electrically controlled valve is bolted above the nozzle through the guide frame. The upper part of the first electrically controlled valve is connected to an external inert gas pressurization system through a vent pipe. At least one pressure sensor is provided below the lower guide frame inside the upper mounting and connecting module and on one side of the connecting rod.

[0020] A method for testing the air tightness of coal mine gas drainage boreholes includes the following steps:

[0021] Step 1: Based on the testing requirements, identify the drilling area to be tested. Using the drag-reducing guide module in the two isolation actuators, a borehole with an inner diameter not less than the diameter of the isolation actuator can be passed through. And using the expansion sealing module and the fixed limiting module, a reliable physical isolation is formed at the upper and lower boundaries of the area to construct an independent test chamber.

[0022] Step 2: Inert gas is injected into the test chamber through an external pressurization system. Multiple preset pressure ranges are set, and the target test pressure is determined by the detection module.

[0023] Step 3: During the gas injection, maintenance, or decay process, the detection module records the real-time pressure and cumulative injection flow rate in the test chamber at high frequency and continuously, and calculates the leakage flow rate.

[0024] Step 4: Set multiple preset pressure ranges corresponding to multiple preset leakage flow ranges, and compare the actual pressure range and the corresponding actual leakage flow range with the preset pressure ranges corresponding to the multiple preset leakage flow ranges to determine the degree of borehole leakage.

[0025] The airtightness testing device and method have the following beneficial effects:

[0026] This invention completely eliminates the risk of reaction with flammable and explosive gases such as methane by using inert gas as the test medium, ensuring absolute safety in downhole operations.

[0027] This invention, through the structural design of an airbag combined with a conical frame, enables the airbag to be evenly stressed during expansion, further improving the reliability and stability of the seal, effectively preventing test gas from leaking from the seal edge, and ensuring the accuracy of test data.

[0028] This invention features a fixed limiting module, allowing the high-end arc-shaped clamping plate to be embedded in the gap between the low-end arc-shaped clamping plates, forming a complete circular fixing structure together with the low-end arc-shaped clamping plates. This creates a ring-supported clamping effect on the inner wall of the hole, further enhancing the stability of the frame within the hole.

[0029] This invention incorporates rollers that are evenly distributed along the circumference to form a stable support and guide structure, thereby converting the sliding friction between the equipment and the inner wall of the hole into rolling friction, significantly reducing movement resistance. Attached Figure Description

[0030] Figure 1 This is a three-dimensional structural schematic diagram of a device for detecting the air tightness of coal mine gas extraction boreholes proposed in this invention.

[0031] Figure 2 This is an enlarged structural schematic diagram of the sealing execution component of a coal mine gas drainage borehole airtightness detection device proposed in this invention;

[0032] Figure 3 This is an enlarged structural diagram of the installation and connection module for a coal mine gas drainage borehole air tightness testing device proposed in this invention.

[0033] Figure 4 This is a schematic cross-sectional view of the frame structure of a coal mine gas drainage borehole air tightness testing device proposed in this invention.

[0034] Figure 5 This invention proposes a device for detecting the air tightness of coal mine gas drainage boreholes. Figure 2 A schematic diagram of the enlarged frame structure;

[0035] Figure 6 This is an enlarged structural diagram of a fixed limiting module for a coal mine gas drainage borehole airtightness testing device proposed in this invention.

[0036] Figure 7 This is an enlarged schematic diagram of the arc-shaped clamping plate structure of the coal mine gas drainage borehole air tightness testing device proposed in this invention.

[0037] Figure 8 This is an enlarged structural diagram of a drag-reducing guide module for a coal mine gas drainage borehole airtightness testing device proposed in this invention.

[0038] Figure 9 This is a schematic diagram of the enlarged connecting rod structure of a coal mine gas drainage borehole airtightness testing device proposed in this invention.

[0039] Figure label:

[0040] The assembly includes a connecting module 1, a connecting rod 2, an expansion sealing module 3, a fixing and limiting module 4, a resistance-reducing guide module 5, a first electronically controlled valve 6, a nozzle 7, and a pressure sensor 8.

[0041] Frame 101, guide frame 102, mounting plate 103, tapered frame 104.

[0042] Rod body 201, threaded protrusion 202,

[0043] Airbag 301, external air tube 302, second electrically controlled valve 303, connecting air tube 304.

[0044] Servo motor 401, mounting bracket 402, rotating rod 403, arc-shaped clamp 404, rubber pad 405.

[0045] Electric actuator 501, connecting plate 502, lever arm 503, support rod 504, roller 505. Detailed Implementation

[0046] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0047] Please see Figures 1-9 As shown, a device for detecting the airtightness of coal mine gas drainage boreholes includes two sealing actuators connected by a connecting rod 2. A detection module for detecting the airtightness between the two sealing actuators is located at the bottom of the upper sealing actuator. The sealing actuator includes:

[0048] Mounting connection module 1 is used to mount equipment components;

[0049] The expansion sealing module 3 is located in the middle of the mounting connection module 1 and is used to fill the gap between the mounting connection module 1 and the hole and to seal and separate the hole.

[0050] Two drag-reducing guide modules 5 are respectively set on the upper and lower sides of the mounting and connecting module 1, which are used to guide the mounting and connecting module 1 when it moves in the hole and reduce the friction between the mounting and connecting module 1 and the hole.

[0051] Two fixed limiting modules 4 are respectively set between the resistance reduction guide module 5 and the expansion sealing module 3, and are used to fix the connecting module 1 installed in the hole;

[0052] Based on the above, the method for testing the air tightness of coal mine gas drainage boreholes is as follows:

[0053] Step 1: Based on the testing requirements, identify the drilling area to be tested (such as a sealing section of a specific length, a casing section, etc.); using the drag-reducing guide module 5 in the two sealing execution components, a drilling inner diameter not less than the diameter of the sealing execution component can be passed through, and using the expansion sealing module 3 and the fixed limiting module 4, a reliable physical isolation is formed at the upper and lower boundaries of the area to construct an independent test chamber;

[0054] Step 2: Inert gas (such as nitrogen) is injected into the test chamber through an external pressurization system. The target test pressure (ranging from 0.1 MPa to 2 MPa) is determined by the detection module, and subsequent operations are performed according to the selected test strategy (such as constant pressure maintenance or pulsed pressurization).

[0055] Step 3: During the gas injection, maintenance, or decay process, the detection module records the real-time pressure and cumulative injection flow rate in the test chamber at high frequency and continuously, and calculates the leakage flow rate (optional). At the same time, the gas concentration change outside the test chamber is monitored.

[0056] Step 4: Set multiple preset pressure ranges corresponding to multiple preset leakage flow ranges, and compare the actual pressure range and the corresponding actual leakage flow range with the preset pressure ranges corresponding to the multiple preset leakage flow ranges to determine the degree of borehole leakage.

[0057] For example, a preset pressure range corresponds to multiple preset leakage flow ranges, so as to determine the corresponding pressure range and the leakage flow range corresponding to the corresponding pressure range for different chamber pressures during the test, so as to determine the leakage degree of the borehole section under test.

[0058] Furthermore, different test pressures can be set according to different drilling conditions. For example, for undisturbed and relatively stable surrounding rock, a high pressure can be maintained in the test chamber for air tightness testing. For disturbed and fractured or relatively unstable surrounding rock, a lower pressure can be maintained in the test chamber for air tightness testing, to meet the gas extraction requirements under different conditions.

[0059] Furthermore, steps five and six may also be included. Step five: The data acquisition and processing unit uses the acquired P(t) and Q(t) data, substitutes them into a simplified model based on the Navier-Stokes equation or Darcy's law, and calculates the equivalent leakage cross-sectional area (ELA) or equivalent permeability (k) of the borehole section.

[0060] Step 6: Compare the calculated ELA / k value with the preset engineering qualification criteria (e.g., the upper limit of ELA value) to determine the leakage level of the borehole section; and send the raw data, calculation results, and judgment conclusions from the test process to the remote monitoring platform through the built-in communication module.

[0061] By introducing objective and accurate engineering parameters such as equivalent leakage cross-sectional area (ELA) or permeability (k), the problem of insufficient quantitative assessment in existing technologies has been completely solved. These parameters can directly reflect the size of the leakage channel and provide a more accurate quantitative basis for judging borehole quality and making repair decisions.

[0062] Meanwhile, the use of inert gases (such as nitrogen) as the testing medium completely eliminates the risk of reaction with flammable and explosive gases such as methane, ensuring absolute safety in downhole operations.

[0063] In order to install equipment components;

[0064] The mounting and connecting module 1 includes a frame 101. Mounting plates 103 are fixed to the upper and lower sides of the frame 101 by bolts. Guide frames 102 are fixed to the opposite sides of the two mounting plates 103 by bolts. Two conical frames 104 are bonded between the inner walls of the two sides of the frame 101. The two conical frames 104 are symmetrically arranged.

[0065] To ensure the test chamber is airtight;

[0066] The expansion sealing module 3 includes an airbag 301 bonded to a conical frame 104 on one side. A connecting air pipe 304 is provided on the side of the airbag 301 bonded to the conical frame 104. An external air pipe 302 connected to an external air pump is provided through the frame 101. The external air pipe 302 is connected to the connecting air pipe 304. A second electric control valve 303 is provided above the external air pipe 302 connected to the connecting air pipe 304. The second electric control valve 303 is used to control the amount of gas in the airbag 301.

[0067] Once the frame 101 is fixed, when a sealed cavity needs to be formed, an external air pump can be used to inflate the airbag 301 through the external air pipe 302. At this time, the second electric control valve 303 is opened, and the gas enters the airbag 301 through the external air pipe 302 and the connecting air pipe 304 in sequence. This causes the airbag 301 to gradually expand under the support of the conical frame 104 until it tightly fits the inner wall of the hole, thereby achieving a double seal for the hole and providing a stable testing environment for subsequent airtightness testing.

[0068] By adjusting the opening and closing degree of the second solenoid valve 303, the expansion pressure of the airbag 301 can be precisely controlled, avoiding damage to the airbag 301 due to excessive pressure or affecting the sealing effect due to insufficient pressure. At the same time, in conjunction with the structural design of the conical frame 104, the airbag 301 can be evenly stressed during the expansion process, further improving the reliability and stability of the seal, effectively preventing test gas from leaking from the sealing edge, and ensuring the accuracy of test data.

[0069] In order to fix the equipment in a specific position;

[0070] The fixed limiting module 4 includes multiple fixed frames 402 fixed on the top outer wall of the mounting plate 103 and the frame 101. Each fixed frame 402 has two detachable rotating rods 403 rotatably connected to one side, and the two rotating rods 403 are arranged in parallel. The other end of the two rotating rods 403 is rotatably connected to an arc-shaped clamping plate 404. The two adjacent arc-shaped clamping plates 404 are staggered in height. The multiple arc-shaped clamping plates 404 are combined to form a circle. The same number of servo motors 401 as the fixed frames 402 are fixed to the top outer wall of the mounting plate 103 and the frame 101 by bolts. The output shaft of the servo motor 401 is fixed to one of the two rotating rods 403 arranged on the same fixed frame 402.

[0071] When it is necessary to fix the frame 101, first start the servo motor 401 connected to the lower arc-shaped clamp 404. The output shaft of the servo motor 401 drives the rotating rod 403 fixed to it to rotate. Then, through the linkage of the two parallel rotating rods 403, the lower arc-shaped clamp 404 is pushed to move towards the inner wall of the hole until the lower arc-shaped clamp 404 is in close contact with the inner wall of the hole and forms a preliminary support.

[0072] Then, the servo motor 401 connected to the high-end arc-shaped clamp 404 is activated to repeat the above action, so that the high-end arc-shaped clamp 404 also moves towards the inner wall of the hole. Since the adjacent arc-shaped clamps 404 are staggered in height, the high-end arc-shaped clamp 404 can be inserted into the gap between the low-end arc-shaped clamps 404, and together with the low-end arc-shaped clamp 404, they form a complete circular fixing structure, thereby forming a ring-supported clamping on the inner wall of the hole, further enhancing the stability of the frame 101 in the hole.

[0073] During the fixing process, the extension distance of the arc-shaped clamping plate 404 can be precisely controlled by adjusting the rotation angle of the servo motor 401 to adapt to the drilling requirements of different inner diameters.

[0074] It should be noted that when the high and low arc-shaped clamping plates 404 cannot form a complete circular fixed structure, the servo motor 401 connected to the low arc-shaped clamping plate 404 can be started and stopped at any angle. After stopping, the electric telescopic rod can be used in conjunction with the pressing block to press the rotating rod 403 to fix the current angle (not shown in the figure) to ensure that the frame 101 will not slide in the hole. Those skilled in the art can set it according to actual needs.

[0075] To ensure a closer fit between the equipment and the hole;

[0076] Rubber pads 405 are bonded to multiple sides of the multiple arc-shaped clamps 404. The rubber pads 405 on the outer side are used to increase the friction with the holes.

[0077] When the high and low arc-shaped clamps 404 together form a complete circular fixing structure, they will compress the inner rubber pad 405, causing the rubber pad 405 to undergo elastic deformation and tightly adhere to the inner wall of the hole. Utilizing the high elasticity of the rubber material, it can effectively fill the tiny gap between the arc-shaped clamps 404 and the inner wall of the hole, further improving the tightness of the fixation.

[0078] Meanwhile, the surface of the rubber pad 405 can be designed with anti-slip texture to enhance the coefficient of friction with the inner wall of the hole and prevent the frame 101 from shifting due to vibration or pressure changes during the test.

[0079] In addition, the rubber material has good wear resistance and corrosion resistance, which can adapt to the complex environmental conditions downhole, extend the service life of the fixed limit module 4, and ensure that it can maintain a stable fixing effect during long-term use.

[0080] To make it easier for the equipment to move inside the holes;

[0081] The drag-reducing guide module 5 includes two electric push rods 501 that are respectively fixed on opposite sides of two mounting plates 103. The movable end of the electric push rod 501 passes through the mounting plate 103 and is fixed to a connecting plate 502 by bolts. The outer circumferential wall of the connecting plate 502 is provided with multiple rotating grooves. A lever arm 503 is rotatably connected in the rotating groove. The other end of the lever arm 503 is rotatably connected to a support rod 504, one end of which is rotatably connected to the mounting plate 103. A roller 505 is provided at the other end of the support rod 504.

[0082] When the equipment moves inside the hole, the electric push rod 501 is activated to extend, and the movable end pushes the connecting plate 502 to move away from the mounting plate 103. At this time, the lever arm 503 rotates in the rotating groove and drives the support rod 504 to unfold, so that the roller 505 contacts the inner wall of the hole.

[0083] Multiple rollers 505 are evenly distributed along the circumference to form a stable support and guide structure, which converts the sliding friction between the equipment and the inner wall of the hole into rolling friction, significantly reducing the moving resistance.

[0084] When encountering local changes in the inner diameter of the hole, the lever arm 503 and the support rod 504 can adaptively adjust the position of the roller 505 by rotating, ensuring that the equipment always moves along the central axis of the hole, avoiding jamming or displacement, and ensuring the smoothness and stability of the detection device in complex hole environments.

[0085] It should be noted that the opening angle of the roller 505 can be reduced depending on whether the equipment is blocked. For example, when the roller 505 is radially blocked, the equipment cannot continue to move downward. The electric push rod 501 can automatically shorten, driving the connecting plate 502 to move towards the mounting plate 103, so that the lever arm 503 and the support rod 504 are retracted, reducing the support range of the roller 505 to adapt to narrow areas, ensuring that the equipment can be flexibly adjusted in hole sections with different inner diameters, and improving the overall adaptability of movement.

[0086] The electric push rod 501, in conjunction with a magnetic switch, proximity switch, or photoelectric switch, enables precise control of the push rod's extension and retraction displacement. Those skilled in the art can configure it according to actual needs.

[0087] To adjust the length of the test chamber;

[0088] The connecting rod 2 includes multiple rods 201. The top of the rod 201 is integrally formed with a threaded protrusion 202, and the bottom is provided with a threaded hole that mates with the threaded protrusion 202. The threaded protrusion 202 between two adjacent rods 201 is screwed into the threaded hole.

[0089] By increasing or decreasing the number of rods 201, the distance between the two isolation actuators can be flexibly adjusted to adapt to the requirements of test chambers of different lengths;

[0090] In actual operation, each rod 201 is first connected to the threaded hole through the threaded protrusion 202 to form the connecting rod 2 of the required length, and then fixed to the installation and connection module 1 of the upper and lower sealing execution components respectively.

[0091] The threaded connection structure not only facilitates quick assembly and disassembly, but also ensures the structural strength of the connecting rod 2 when subjected to test pressure, preventing loosening or breakage of the connection due to cavity length adjustment, and providing a reliable length adjustment solution for constructing independent test cavities of different specifications.

[0092] In order to test the airtightness of the holes;

[0093] The detection module includes a nozzle 7 fixed below the lower guide frame 102 inside the upper mounting and connecting module 1. A first electric control valve 6 is bolted above the nozzle 7, passing through the guide frame 102. The upper part of the first electric control valve 6 is connected to an external inert gas storage tank through a vent pipe. At least one pressure sensor 8 is provided below the lower guide frame 102 inside the upper mounting and connecting module 1 and on one side of the connecting rod 2.

[0094] When testing is required, an external pressurization system is used to inject inert gas into the test chamber through the opening of the first solenoid valve 6 and the nozzle 7. At the same time, the pressure sensor 8 monitors the pressure change inside the chamber in real time. When the pressure reaches the target test pressure range (0.1MPa to 2MPa), the first solenoid valve 6 automatically closes to maintain pressure stability.

[0095] During the pressure maintenance phase, the pressure sensor 8 continuously collects pressure data P(t) and records the cumulative leakage flow Q(t) through the built-in flow sensor. The entire process requires no manual intervention and can achieve high-frequency, continuous data acquisition.

[0096] For monitoring external gas concentration, a gas sensor can be integrated outside the detection module to capture changes in gas concentration in the surrounding environment of the test chamber in real time, thereby further improving the safety of downhole operations (not shown in the figure).

[0097] After data collection is completed, the actual pressure range and the corresponding actual leakage flow range are compared with multiple preset leakage flow ranges corresponding to the preset pressure range to determine the degree of borehole leakage.

[0098] For example, a preset pressure range corresponds to multiple preset leakage flow ranges, so as to determine the corresponding pressure range and the leakage flow range corresponding to the corresponding pressure range for different chamber pressures during the test, so as to determine the leakage degree of the borehole section under test.

[0099] Furthermore, different test pressures can be set according to different drilling conditions. For example, for undisturbed and relatively stable surrounding rock, a high pressure can be maintained in the test chamber for airtightness testing. For disturbed and fractured or relatively unstable surrounding rock, a lower pressure can be maintained in the test chamber for airtightness testing, to meet the gas extraction requirements under different conditions.

[0100] Furthermore, after the data collection is completed, steps five and six can be performed.

[0101] Step 5: The data acquisition and processing unit uses the acquired P(t) and Q(t) data and substitutes them into a simplified model based on the Navier-Stokes equation or Darcy's law to calculate the equivalent leakage cross-sectional area (ELA) or equivalent permeability (k) of the borehole section.

[0102] Step 6: Compare the calculated ELA / k value with the preset engineering qualification criteria (e.g., the upper limit of ELA value) to determine the leakage level of the borehole section; and send the raw data, calculation results, and judgment conclusions from the test process to the remote monitoring platform through the built-in communication module.

[0103] By introducing objective and accurate engineering parameters such as equivalent leakage cross-sectional area (ELA) or permeability (k), the problem of insufficient quantitative assessment in existing technologies has been completely solved. These parameters can directly reflect the size of the leakage channel and provide a more accurate quantitative basis for judging borehole quality and making repair decisions.

[0104] Meanwhile, the use of inert gases (such as nitrogen) as the testing medium completely eliminates the risk of reaction with flammable and explosive gases such as methane, ensuring absolute safety in downhole operations.

[0105] The detection module transmits the raw pressure and flow data to the data processing unit, providing an accurate data source for the subsequent calculation of equivalent leakage cross-sectional area (ELA) or permeability (k), ensuring the objectivity and reliability of the detection results.

[0106] It should be noted that both the first solenoid valve 6 and the second solenoid valve 303 are electromagnetic control valves (such as the solenoid valve with model number 2W-160-15). They can achieve precise control of the injected gas flow rate according to the opening degree of the first solenoid valve 6. Their structure and principle can be learned by those skilled in the art through the technical manual.

[0107] The pressure sensor 8 can be a high-precision diffused silicon pressure sensor (such as the MPX5010 sensor), with a measurement accuracy of ±0.25%FS and a response time of less than 1ms, which can meet the requirements of high-frequency data acquisition.

[0108] The flow sensor can be a miniature mass flow sensor (such as the MF5700 series sensor), with a range of 0-500 sccm and an accuracy class of ±1.5%FS. It can monitor minute changes in gas leakage in real time and ensure the accuracy of Q(t) data.

[0109] In addition, the equipment integrates core control components such as a PLC controller and a 4G module. The PLC controller, as the central system of the equipment, is responsible for receiving real-time data from various sensors (such as pressure sensor 8, flow sensor, gas sensor, etc.) and controlling the coordinated action of actuators such as electric push rod 501, servo motor 401, electric push rod 501, first electric control valve 6, and second electric control valve 303 according to the preset program logic to realize the automated operation of the testing process. The 4G module undertakes the remote data transmission function, uploading the raw pressure P(t) and flow Q(t) data collected by the detection module, as well as the equivalent leakage cross-sectional area (ELA) or equivalent permeability (k) and leakage level judgment results calculated by the data processing unit to the mine safety monitoring center in real time. This facilitates the ground management personnel to remotely monitor, analyze, and make decisions on the sealing quality of underground boreholes, and also supports remote diagnosis and parameter adjustment of equipment operation status.

[0110] The method for detecting the air tightness of coal mine gas drainage boreholes according to embodiments of the present invention is applicable to the air tightness detection device for coal mine gas drainage boreholes described herein, characterized by comprising the following steps:

[0111] Step 1: Based on the testing requirements, identify the drilling area to be tested. Using the drag-reducing guide module 5 from the two isolation actuators, a borehole with an inner diameter not less than the diameter of the isolation actuator can pass through. The expansion sealing module 3 and the fixed limiting module 4 form a reliable physical isolation at the upper and lower boundaries of this area, constructing an independent test chamber.

[0112] Step 2: Inert gas is injected into the test chamber through an external pressurization system. Multiple preset pressure ranges are set, and the target test pressure is determined by the detection module.

[0113] Step 3: During the gas injection, maintenance, or decay process, the detection module records the real-time pressure and cumulative injection flow rate in the test chamber at high frequency and continuously, and calculates the leakage flow rate.

[0114] Step 4: Set multiple preset pressure ranges corresponding to multiple preset leakage flow ranges, and compare the actual pressure range and the corresponding actual leakage flow range with the preset pressure ranges corresponding to the multiple preset leakage flow ranges to determine the degree of borehole leakage.

[0115] For example, after the test and data collection are completed, it is confirmed that the actual pressure range falls into the corresponding preset pressure range. Then, the actual leakage is compared with multiple preset leakage flow ranges corresponding to the preset pressure range to determine the degree of borehole leakage, which is convenient for personnel to analyze and compare.

[0116] The method for detecting the airtightness of coal mine gas drainage boreholes according to embodiments of the present invention, by setting multiple preset pressure ranges, can more comprehensively evaluate the airtightness of the borehole under different pressure conditions, ensuring the comprehensiveness and accuracy of the test results. During gas injection, maintenance, or decay, high-frequency and continuous recording of real-time pressure, cumulative injection flow rate, and leakage flow rate within the test chamber can capture minute leakage changes, avoiding the accuracy degradation caused by manual operation and simple instruments, thus improving the sensitivity and accuracy of the detection. Comparing the actual pressure range with the preset pressure range determines the corresponding preset pressure range for the actual test pressure, and then comparing the corresponding leakage flow rate range allows for a more comprehensive evaluation of the borehole's airtightness under different pressure conditions, ensuring the comprehensiveness and accuracy of the test results. From the positioning of the sealing execution component to data acquisition and processing, the entire detection process is automated, minimizing manual intervention and improving detection efficiency and reliability. The use of inert gas (helium) and gas concentration monitoring ensures the safety of the detection process; quantitative evaluation and leakage level determination provide strong support for engineering decisions. These beneficial effects not only improve the reliability of airtightness testing of coal mine gas drainage boreholes, but also provide important guarantees for safe coal mine production.

[0117] Furthermore, when testing the airtightness of the sealing section of a newly constructed coal seam extraction borehole, during the gas injection, maintenance, or decay process, the detection module continuously and frequently records the real-time pressure and cumulative injection / leakage flow rate within the test chamber. The data acquisition and processing unit uses the acquired data and substitutes it into a simplified model based on the Navier-Stokes equation or Darcy's law to calculate the equivalent leakage cross-sectional area or equivalent permeability of the borehole section. The calculated equivalent leakage cross-sectional area / equivalent permeability value is compared with preset engineering qualification criteria to determine the leakage level of the borehole section. The raw data, calculation results, and judgment conclusions from the testing process are then sent to a remote monitoring platform via the built-in communication module.

[0118] Specifically, for example, (1) the device is lowered into the borehole, packers are deployed at the upper and lower ends of the sealing section (30 meters), and inflated to firmly seal the borehole wall, forming an independent test chamber.

[0119] (2) Nitrogen gas is injected into the cavity through the pressurization system of the device to precisely stabilize the pressure at 0.5MPa.

[0120] (3) Select constant pressure maintenance mode: keep the pressure between 0.5MPa±0.05MPa and continue to inject gas for 15 minutes; during this period, the flow meter records the cumulative injected gas volume as 12L.

[0121] (4) The data processing unit receives this data and, in combination with the cavity volume (calculated from the packer spacing and aperture) and gas properties, calls its internal quantization algorithm.

[0122] (5) The equivalent leakage cross-sectional area (ELA) of the sealing section is obtained.

[0123] (6) If the equivalent leakage cross-sectional area obtained is not greater than the pre-set qualified standard of the mine, the air tightness of the sealing section is deemed qualified.

[0124] (7) The test results are uploaded to the mine safety monitoring center in real time through the device's 4G module.

[0125] Used for locating leaks in long-running extraction borehole casing:

[0126] (1) In the borehole, packers are deployed about 10 meters above and below the suspected casing damage area to form a 20-meter-long test chamber.

[0127] (2) Pulse pressure decay mode: Nitrogen gas is injected into the cavity to instantly raise the pressure to 1.2 MPa.

[0128] (3) Immediately isolate the pressurization source and begin monitoring the pressure decay for 15 minutes.

[0129] (4 optional) Meanwhile, in the roadway near the borehole, the gas concentration sensor showed slight fluctuations, but did not reach the alarm threshold.

[0130] (5) The data processing unit receives the pressure decay data, combines the gas properties and cavity volume, calculates and obtains the equivalent leakage cross-sectional area (ELA) of the casing section.

[0131] (6) Based on the comparison between the equivalent leakage cross-sectional area (ELA) and the original data, determine whether the air tightness of the casing section is up to standard.

[0132] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0133] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0134] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0135] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0136] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0137] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A device for detecting the airtightness of coal mine gas drainage boreholes, characterized in that, It includes two sealing execution components connected by a connecting rod (2). A detection module for airtightness testing between the two sealing execution components is located at the bottom of the upper sealing execution component. The sealing execution component includes: The mounting connection module (1) is used to mount equipment components; An expansion sealing module (3) is set in the middle of the mounting connection module (1) to fill the gap between the mounting connection module (1) and the hole and to seal and separate the hole. Two drag-reducing guide modules (5) are respectively set on the upper and lower sides of the mounting connection module (1) to guide the mounting connection module (1) when it moves in the hole and reduce the friction between the mounting connection module (1) and the hole; Two fixed limiting modules (4) are respectively set between the resistance reduction guide module (5) and the expansion sealing module (3) for fixing the installation connection module (1) in the hole; the installation connection module (1) includes a frame (101), and mounting plates (103) are fixedly connected to both the upper and lower sides of the frame (101). Guide frames (102) are fixedly connected to the opposite sides of the two mounting plates (103). Two conical frames (104) are bonded between the inner walls of both sides of the frame (101). The two conical frames (104) are symmetrically arranged; the expansion sealing module (3) is fixedly connected to the expansion sealing module (4) in the hole. The module (3) includes an airbag (301) that is attached to a conical frame (104) on one side. A connecting air pipe (304) is provided on the side of the airbag (301) that is attached to the conical frame (104). An external air pipe (302) that is connected to an external air pump is provided through the frame (101). The external air pipe (302) is connected to the connecting air pipe (304). A second electric control valve (303) is provided above the external air pipe (302) that is connected to the connecting air pipe (304). The second electric control valve (303) is used to control the amount of gas in the airbag (301). The fixed limiting module (4) includes multiple fixed frames (402) fixed on the top outer wall of the mounting plate (103) and the frame (101). Each fixed frame (402) has two detachable rotating rods (403) rotatably connected to one side, and the two rotating rods (403) are arranged in parallel. The other end of the two rotating rods (403) is rotatably connected to an arc-shaped clamp (404). Multiple arc-shaped clamps (404) are combined to form a circle. The same number of servo motors (401) as the fixed frames (402) are fixedly connected to the top outer wall of the mounting plate (103) and the frame (101). The output shaft of the servo motor (401) is fixed to one of the two rotating rods (403) arranged on the same fixed frame (402). The drag-reducing guide module (5) includes two electric push rods (501) fixed on opposite sides of two mounting plates (103). The movable end of the electric push rod (501) passes through the mounting plate (103) and is fixedly connected to a connecting plate (502). The outer circumferential wall of the connecting plate (502) has multiple rotating grooves. A lever arm (503) is rotatably connected in the rotating groove. The other end of the lever arm (503) is rotatably connected to a support rod (504) whose end is rotatably connected to the mounting plate (103). The other end of the support rod (504) is connected to the other end of the support rod (504). The end is provided with a roller (505); the detection module includes a nozzle (7) fixed below the lower guide frame (102) inside the upper mounting and connecting module (1), a first electric control valve (6) is fixedly connected above the nozzle (7) through the guide frame (102), the upper part of the first electric control valve (6) is connected to an external inert gas pressurization system through a vent pipe, and at least one pressure sensor (8) is provided below the lower guide frame (102) inside the upper mounting and connecting module (1) and on one side of the connecting rod (2).

2. The device for detecting the airtightness of coal mine gas drainage boreholes according to claim 1, characterized in that, Rubber pads (405) are bonded to multiple sides of the multiple arc-shaped clamps (404), and the rubber pads (405) on the outer side are used to increase the friction with the holes.

3. The device for detecting the airtightness of coal mine gas drainage boreholes according to claim 1, characterized in that, The two adjacent arc-shaped clamps (404) are staggered in height.

4. The device for detecting the airtightness of coal mine gas drainage boreholes according to claim 1, characterized in that, The connecting rod (2) includes multiple rods (201). The top of the rod (201) is integrally formed with a threaded protrusion (202), and the bottom is provided with a threaded hole that matches the threaded protrusion (202). The threaded protrusion (202) between two adjacent rods (201) is screwed into the threaded hole.

5. A method for detecting the airtightness of coal mine gas drainage boreholes, applicable to the airtightness detection device for coal mine gas drainage boreholes as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Based on the testing requirements, identify the drilling area to be tested. Using the drag-reducing guide module (5) in the two sealing execution components, the borehole inner diameter, which is not less than the diameter of the sealing execution component, can be passed through. And using the expansion sealing module (3) and the fixed limiting module (4), a reliable physical isolation is formed at the upper and lower boundaries of the area to construct an independent test chamber. Step 2: Inert gas is injected into the test chamber through an external pressurization system. Multiple preset pressure ranges are set, and the target test pressure is determined by the detection module. Step 3: During the gas injection, maintenance, or decay process, the detection module records the real-time pressure and cumulative injection flow rate in the test chamber at high frequency and continuously, and calculates the leakage flow rate. Step 4: Set multiple preset pressure ranges corresponding to multiple preset leakage flow ranges, and compare the actual pressure range and the corresponding actual leakage flow range with the preset pressure ranges corresponding to the multiple preset leakage flow ranges to determine the degree of borehole leakage.

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