Flexible pressure-maintaining and recoverable intelligent hole sealing construction method for downhole extraction borehole

Abstract

The application discloses a flexible pressure-maintaining and recyclable intelligent hole sealing construction method for downhole extraction drilling, which comprises the following steps: arranging a PLC controller, a slurry storage and stirring container, a grouting pipe pump assembly and a back slurry pipe pump assembly in a downhole roadway, and arranging a double-flexible-tire capsule hole sealer in an extraction drilling hole; the slurry storage and stirring container is used for preparing slurry for hole sealing; the double-flexible-tire capsule hole sealer is used for grouting and hole sealing; a gas extraction pipeline is connected to the double-flexible-tire capsule hole sealer for gas extraction operation of the extraction drilling hole; a downhole slurry storage and conveying system is used for dynamic pressure maintenance of the double-flexible-tire capsule hole sealer, and alarm and treatment are performed on pressure loss of the double-flexible-tire capsule and the middle section; and the double-flexible-tire capsule hole sealer and the slurry are recycled. The application realizes intelligent grouting and hole sealing, achieves accurate and free control of hole sealing pressure, automatic pressure maintenance of the drilling hole, automatic recycling of the hole sealing material after the extraction is completed, recycling and reuse of the hole sealer, and has the advantages of simple operation, high automation, low labor intensity of workers, cost saving and the like.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas extraction technology, specifically relating to a flexible, pressure-maintaining, recyclable, and intelligent sealing method for underground gas extraction boreholes. Background Technology

[0002] Traditional gas extraction and sealing processes typically involve inserting a sealing device after drilling the borehole. Workers add sealing material and water to a slurry tank in a specific ratio and mix thoroughly to form a slurry. The slurry is then injected into the sealing device using a grouting pump. Once the slurry solidifies, the extraction pipe is connected to the extraction pipeline for gas extraction. This sealing process suffers from high costs associated with transporting sealing materials, high labor intensity, complex operation, low success rate, and significant dependence on worker skill levels. If the borehole deforms due to mining activity after the slurry solidifies in the sealing device, gas leakage can easily occur, affecting the gas extraction concentration. Furthermore, the sealing device and sealing material cannot be recycled and reused, resulting in high costs. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a flexible, recyclable, and intelligent sealing method for downhole extraction boreholes that allows for direct preparation of sealing slurry downhole, is easy to operate, maintains constant pressure, and prevents air leakage.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a flexible pressure-maintaining and recyclable intelligent sealing method for downhole extraction boreholes, comprising the following steps:

[0005] (1) A PLC controller, a slurry mixing container, a grouting pipe pump assembly and a return slurry pipe pump assembly are arranged in the underground roadway. A double flexible bladder sealer is installed in the extraction borehole. The lower part of the grouting mixing container is connected to the inlet of the grouting pipe pump assembly. The outlet of the grouting mixing container is connected to the inlet of the double flexible bladder sealer. The outlet of the double flexible bladder sealer is connected to the inlet of the return slurry pipe pump assembly. The outlet of the return slurry pipe pump assembly is connected to the top of the slurry mixing container. When arranging and connecting the various pipelines, valves, pump stations, flow sensors, pressure sensors and solenoid valves installed on the pipelines are also connected.

[0006] (2) Preparation of sealing slurry in a slurry storage and mixing container;

[0007] (3) Grouting and sealing operations are performed into the double flexible bladder sealer;

[0008] (4) Connect the gas extraction pipeline to the extraction borehole for gas extraction operation;

[0009] (5) During the gas extraction operation, the underground slurry storage and transportation system dynamically maintains the pressure of the double flexible bladder sealing device, and alarms and handles the pressure loss of the double flexible bladder and intermediate section.

[0010] (6) After the gas extraction is completed, the double flexible bladder sealer and slurry are recovered.

[0011] The slurry storage and mixing container includes a slurry storage tank. A solid raw material injection port is provided at the top of the slurry storage tank, and a screw feeder is connected to the solid raw material injection port. A water supply pipe is connected to the upper side of the slurry storage tank, and a water supply solenoid valve and a water supply flow meter are provided on the water supply pipe. A stirring motor is provided at the top of the slurry storage tank, and a stirrer is connected to the main shaft of the stirring motor inside the slurry storage tank. A density sensor and a viscosity sensor are provided in the lower middle part of the inner wall of the slurry storage tank, and a liquid level sensor is provided in the upper and lower parts of the inner wall of the slurry storage tank.

[0012] The dual flexible bladder sealing device is installed inside the extraction borehole. The dual flexible bladder sealing device includes a first flexible bladder, a second flexible bladder, an intrabladder grouting recovery pipe, and an interbladder grouting recovery pipe. An extraction pipe is inserted into the central hole of the first and second flexible bladders. The first flexible bladder is located below the second flexible bladder. The intrabladder grouting recovery pipe passes through the first and second flexible bladders from bottom to top. The upper end of the intrabladder grouting recovery pipe is sealed. The intrabladder grouting recovery pipe has a first flexible bladder grouting recovery hole located in the first flexible bladder and a second flexible bladder grouting recovery hole located in the second flexible bladder. The upper end of the interbladder grouting recovery pipe passes through the first flexible bladder from bottom to top and extends between the first and second flexible bladders.

[0013] The lower end of the grouting recovery pipe in the fetal sac is connected to a first tee pipe. The lower part of the grouting recovery pipe in the fetal sac is equipped with a first pressure sensor and a first flow sensor. The second port of the first tee pipe is equipped with a first solenoid valve, and the third port of the first tee pipe is equipped with a second solenoid valve. The lower end of the second grouting pipe is connected to a second tee pipe. The lower part of the second grouting pipe is equipped with a second pressure sensor and a second flow sensor. The second port of the second tee pipe is equipped with a third solenoid valve, and the third port of the second tee pipe is equipped with a fourth solenoid valve.

[0014] The grouting pipe pump assembly includes a grouting and pressure-maintaining main pipe. The inlet end of the grouting and pressure-maintaining main pipe is connected to the lower part of the grout storage tank. Along the grout flow direction, the grouting and pressure-maintaining main pipe is equipped with a fifth solenoid valve, a downhole grouting pump, a third flow sensor, a sixth solenoid valve, and a third pressure sensor in sequence.

[0015] The slurry return pipe pump assembly includes an intelligent pressure-maintaining slurry return main pipe, the outlet end of which is connected to the top of the slurry storage tank. Along the slurry flow direction, the intelligent pressure-maintaining slurry return main pipe is equipped with a fourth pressure sensor, a seventh solenoid valve, a fourth flow sensor, and a downhole slurry return pump.

[0016] The second port of the first tee pipe is connected to the grouting and pressure-maintaining main pipe through the first grouting hose, and the third port of the first tee pipe is connected to the intelligent pressure-maintaining and grouting return main pipe through the first grout return hose. The second port of the second tee pipe is connected to the grouting and pressure-maintaining main pipe through the second grouting hose, and the third port of the second tee pipe is connected to the intelligent pressure-maintaining and grouting return main pipe through the second grout return hose.

[0017] The specific process of step (2) is as follows: According to the predetermined pulping volume, the PLC controller sends an instruction to the water pump connected to the water supply pipe inlet, and at the same time instructs the stirring motor and screw feeder to start and the water supply solenoid valve to open, injecting a certain amount of water into the slurry storage tank. According to the information of the water supply flow meter, it is judged that the predetermined water volume has been reached and the water injection is stopped. The screw feeder quantitatively transports the solid material into the slurry storage tank. The stirring motor drives the agitator to start stirring, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The sealing material has good fluidity and a certain viscosity. The density sensor and viscosity sensor are used to measure the viscosity and density information of the slurry in real time and transmit it to the PLC controller. After the slurry is qualified, the stirring motor stops working.

[0018] The specific process of step (3) is as follows: The PLC controller instructs the fifth and sixth solenoid valves to open, the downhole grouting pump starts, and the grout is transported to the sealing location through the grouting pressure maintaining main pipe. The PLC controller sends a pressure signal value through the third pressure sensor to control the fifth and sixth solenoid valves on the grouting pressure maintaining main pipe to realize the pipeline opening and closing and the start and stop of the downhole grouting pump, so that a certain grouting pressure is always maintained in the grouting pressure maintaining main pipe; the double flexible bladder sealing device is inserted into the predetermined sealing depth of the borehole, and the sealing command is issued through the PLC controller. At this time, the first three-way valve... The first solenoid valve on the pipe opens, and the grouting recovery pipe inside the sac begins to inject grout into the two first and second flexible sacs. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and the grouting stops. Then, the third solenoid valve on the second three-way pipe opens, and the grout begins to be injected into the middle section between the first and second flexible sacs through the grouting recovery pipe between the sacs until the second pressure sensor detects that the preset grouting pressure value has been reached. The PLC controller then issues a command to close the third solenoid valve to stop the grouting, and the extraction borehole is sealed.

[0019] The specific process of dynamically maintaining pressure for the dual flexible bladder sealing device in step (5) is as follows: When the cross-section of the extraction borehole deforms and increases, causing the pressure in the first flexible bladder and / or the second flexible bladder to decrease and be less than the predetermined constant pressure, the first pressure sensor transmits the pressure monitoring data to the PLC controller. The PLC controller instructs the first solenoid valve to open, and the grouting recovery pipe inside the bladder begins to inject grout into the two first flexible bladders and the second flexible bladder. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and stops grouting. Similarly, when the pressure drops in the middle section between the first flexible bladder and the second flexible bladder due to the appearance of cracks around the extraction borehole, the third solenoid valve connected to the grouting recovery pipe between the bladders opens, and the grout begins to be injected into the middle section between the first flexible bladder and the second flexible bladder through the grouting recovery pipe between the bladders until the second pressure sensor detects that the preset grouting pressure value has been reached. The downhole PLC controller then issues a command to close the third solenoid valve and stop grouting.

[0020] When the borehole deforms and its effective diameter decreases due to mining activities, the pressure on the double flexible sluice and the intermediate section increases. When the pressure exceeds the set value, the first and second pressure sensors send pressure change information to the PLC controller. The PLC controller first sends an opening command to the fourth and seventh solenoid valves. The slurry in the intermediate section of the borehole will first enter the second slurry return hose through the grout recovery pipe between the sluices and the third interface (slurry return port) of the second tee pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank in the roadway. When the value monitored by the second pressure sensor reaches the set value, the fourth and seventh solenoid valves close. Then, the PLC controller first sends an opening command to the second and seventh solenoid valves. The slurry in the first and second flexible sluices will first enter the first slurry return hose through the grout recovery pipe inside the sluice and the third interface (slurry return port) of the first tee pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank in the roadway. When the value monitored by the first pressure sensor reaches the set value, the second and seventh solenoid valves close.

[0021] The specific process for alarming and handling the loss of pressure in the dual flexible sac and intermediate segment in step (5) is as follows:

[0022] A) Alarm and Handling of Pressure Loss in Dual Flexible Bubble: When a flexible bubbling ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor, and the grout injection cannot maintain the pressure of the flexible bubbling, or when a pressure loss occurs shortly after the pressure rises, the system will stop injecting grout into the flexible bubbling to prevent a large amount of grout from flowing into the borehole or tunnel, and will issue an audible and visual alarm to indicate that the flexible bubbling in the borehole has lost pressure and ruptured. At this time, the flexible bubbling in the borehole can be recovered first, the damaged flexible bubbling can be replaced, and then the borehole can be sealed to ensure that the borehole can continue to pump normally.

[0023] B) Alarm and Handling of Pressure Loss in the Middle Section: When a large number of through-type fractures appear in the middle section of the borehole due to mining, resulting in severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor, and the injection of slurry cannot maintain pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into the borehole or roadway, and will issue an audible and visual alarm to indicate that the middle section of the borehole is under pressure. At this time, the gas concentration in a single borehole can be measured first. If the gas concentration in a single borehole does not decrease significantly, no action is taken. If the concentration in the borehole has decreased significantly compared to before, the double flexible bladder sealer of the borehole can be retrieved, and the sealing position of the sealer or the density and viscosity of the sealing slurry in the middle section can be adjusted before resealing. If it is still difficult to maintain pressure, it proves that there are serious and large fractures around the borehole that are difficult to seal. The borehole can be closed to prevent the overall gas concentration of the extraction pipeline from decreasing due to gas leakage in the borehole.

[0024] The specific process of recovering the double flexible sluice bag sealing device and slurry in step (6) is as follows: The PLC controller first sends an opening command to the fourth and seventh solenoid valves. The slurry in the middle section of the borehole will first enter the second slurry return hose through the slurry recovery pipe between the sluice bags and the third interface (slurry return port) of the second three-way pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and then flow into the main slurry return pipe through the third three-way pipe. Under the action of the downhole slurry return pump, it finally flows into the slurry storage tank. When the value monitored by the second pressure sensor reaches the set value, the fourth and seventh solenoid valves are closed. Then, the PLC controller first sends an opening command to the second and seventh solenoid valves. The slurry in the first and second flexible sluice bags will first enter the first slurry return hose through the slurry recovery pipe in the sluice bag and the third interface (slurry return port) of the first three-way pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank under the action of the downhole slurry return pump. When the value monitored by the first pressure sensor reaches the set value, the second and seventh solenoid valves are closed.

[0025] By adopting the above technical solution, the present invention has the following technical effects:

[0026] 1. The control system in this invention is a PLC controller. The PLC controller is mainly responsible for controlling the stirring motor, downhole grouting pump, downhole return grouting pump and solenoid valve to perform corresponding actions according to the requirements of grouting, grouting storage and delivery and the information fed back by the flow sensor, density sensor, viscosity sensor and liquid level sensor. It also displays the relevant information on the display screen of the PLC controller and can adjust key data such as grouting volume, grouting volume and grouting volume as needed. It can also communicate and display key data information of downhole grouting storage and sealing device in real time.

[0027] 2. During pulping, the PLC controller controls the opening and closing of the water supply solenoid valve on the water supply pipe and the water injection volume measured by the water supply flow meter based on the pulping volume and concentration. It also controls the opening and closing of the screw feeder to measure the feed amount of solid raw materials. A silo is arranged in the tunnel, with the screw feeder located at the lower port of the silo. Density and viscosity sensors are installed at corresponding positions in the pulp storage tank to measure the viscosity and density information of the pulp in real time and transmit it to the PLC controller.

[0028] 3. When recovering slurry, recover the slurry in the middle section first, and then recover the slurry inside the first and second flexible bladders. This sequential order avoids the situation where the pressure in the flexible bladder decreases and the pressure in the middle section increases, causing slurry leakage. It also ensures that the flexible bladder will not rupture due to increased pressure caused by borehole deformation.

[0029] 4. The flexible sealing and dynamic pressure-holding sealing of the borehole ensures that the entire borehole is always in a stable pressure-holding extraction state. This eliminates the air leakage caused by the increase in borehole volume after the traditional sealing material solidifies, and the failure of the extraction borehole caused by the compression and breakage of the extraction tube due to the decrease in borehole volume. This ensures the safety and efficiency of extraction.

[0030] In summary, this invention directly prepares slurry downhole and delivers it to a dual flexible bladder sealing device. It utilizes a control system to achieve highly intelligent grouting and sealing, enabling precise and free control of sealing pressure, automatic pressure maintenance throughout the drilling and sealing process, automatic recovery of sealing material after extraction, and recyclable sealing device. It has advantages such as small footprint, simple operation, high degree of automation, low labor intensity for workers, and cost savings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the connection structure between the slurry storage and mixing container, the grouting pipe pump assembly, and the slurry return pipe pump assembly in this invention;

[0032] Figure 2 This is a schematic diagram of the structure of the dual flexible bladder sealing device in this invention;

[0033] Figure 3 yes Figure 2 Axial cross-sectional view of the two flexible sacs in the middle;

[0034] Figure 4 This is a schematic diagram of the arrangement of the dual flexible bladder sealing device along the length of the roadway in the cross-layer borehole of the present invention.

[0035] Figure 5 This is a schematic diagram of the arrangement of the dual flexible bladder sealing device in the cross-layer borehole along the width direction of the roadway in this invention;

[0036] Figure 6 This is a schematic diagram of the arrangement of the dual flexible bladder sealing device in the in-seam borehole along the length of the roadway in this invention. Detailed Implementation

[0037] like Figures 1-6 As shown, the downhole extraction borehole flexible pressure-maintaining and recyclable intelligent sealing construction method of the present invention includes the following steps:

[0038] (1) A PLC controller, a slurry mixing container, a grouting pipe pump assembly and a return slurry pipe pump assembly are arranged in the underground roadway. A double flexible bladder sealer 5 is installed in the extraction borehole. The lower part of the grouting mixing container is connected to the inlet of the grouting pipe pump assembly. The outlet of the grouting mixing container is connected to the inlet of the double flexible bladder sealer. The outlet of the double flexible bladder sealer is connected to the inlet of the return slurry pipe pump assembly. The outlet of the return slurry pipe pump assembly is connected to the top of the slurry mixing container. When arranging and connecting the various pipelines, valves, pump stations, flow sensors, pressure sensors and solenoid valves installed on the pipelines are also connected.

[0039] (2) Preparation of sealing slurry in a slurry storage and mixing container;

[0040] (3) Grouting and sealing operation is performed into the double flexible bladder sealing device 5;

[0041] (4) Connect the gas extraction pipeline to the extraction borehole for gas extraction operation;

[0042] (5) During the gas extraction operation, the underground slurry storage and transportation system dynamically maintains the pressure of the double flexible bladder sealing device 5, and alarms and handles the pressure loss of the flexible bladder and intermediate section.

[0043] (6) After the gas extraction is completed, the double flexible bladder sealer 5 and the slurry are recovered.

[0044] The slurry storage and mixing container includes a slurry storage tank 6. The top of the slurry storage tank 6 is provided with a solid raw material injection port 7. A water supply pipe 8 is connected to the upper side of the slurry storage tank 6. A water supply solenoid valve 9 and a water supply flow meter 10 are provided on the water supply pipe 8. A stirring motor 11 is provided at the top of the slurry storage tank 6. The main shaft of the stirring motor 11 is driven to connect to a stirrer 12 located inside the slurry storage tank 6. A density sensor 13 and a viscosity sensor 14 are provided in the lower middle part of the inner wall of the slurry storage tank 6. A liquid level sensor 15 is provided in the upper and lower parts of the inner wall of the slurry storage tank 6, respectively.

[0045] The dual flexible bladder sealing device 5 is installed inside the extraction borehole 29 (the extraction borehole 29 includes cross-layer boreholes and in-layer boreholes); the dual flexible bladder sealing device 5 includes a first flexible bladder 30, a second flexible bladder 31, an intra-bladder grouting recovery pipe 32, and an inter-bladder grouting recovery pipe 33. An extraction pipe 34 is inserted into the central hole of the first flexible bladder 30 and the second flexible bladder 31. The first flexible bladder 30 is located below the second flexible bladder 31, and the intra-bladder grouting recovery pipe 32 extends from below. The first flexible fetal sac 30 and the second flexible fetal sac 31 are passed through sequentially. The upper end of the grouting recovery pipe 32 inside the fetal sac is sealed. The grouting recovery pipe 32 inside the fetal sac is provided with a first flexible fetal sac grouting recovery hole 35 located inside the first flexible fetal sac 30 and a second flexible fetal sac grouting recovery hole 36 located inside the second flexible fetal sac 31. The upper end of the grouting recovery pipe 33 between the fetal sacs passes through the first flexible fetal sac 30 from bottom to top and then extends between the first flexible fetal sac 30 and the second flexible fetal sac 31.

[0046] The lower port of the intrasac grout recovery pipe 32 is connected to a first three-way pipe 64. The lower part of the intrasac grout recovery pipe 32 is provided with a first pressure sensor 37 and a first flow sensor 38. The second port of the first three-way pipe 64 is provided with a first solenoid valve 41, and the third port of the first three-way pipe 64 is provided with a second solenoid valve 42. The lower port of the intersac grout recovery pipe 33 is connected to a second three-way pipe 43. The lower part of the intersac grout recovery pipe 33 is provided with a second pressure sensor 44 and a second flow sensor 45. The second port of the second three-way pipe 43 is provided with a third solenoid valve 48, and the third port of the second three-way pipe 43 is provided with a fourth solenoid valve 49.

[0047] The grouting pipe pump assembly includes a grouting and pressure-maintaining main pipe 3. The inlet end of the grouting and pressure-maintaining main pipe 3 is connected to the lower side of the grout storage tank 6. The grouting and pressure-maintaining main pipe 3 is equipped with a fifth solenoid valve 16, a downhole grouting pump 17, a third flow sensor 18, a sixth solenoid valve 19, and a third pressure sensor 20 in sequence along the grout flow direction.

[0048] The slurry return pipe pump assembly includes an intelligent pressure-maintaining slurry return main pipe 4. The outlet end of the intelligent pressure-maintaining slurry return main pipe 4 is connected to the top of the slurry storage tank 6. Along the slurry flow direction, the intelligent pressure-maintaining slurry return main pipe 4 is equipped with a fourth pressure sensor 21, a seventh solenoid valve 22, a fourth flow sensor 23, and a downhole slurry return pump 24.

[0049] The second port of the first three-way pipe 64 is connected to the grouting and pressure-maintaining main pipe 3 via the first grouting hose 39. The third port of the first three-way pipe 64 is connected to the intelligent pressure-maintaining and grouting return main pipe 4 via the first grouting return hose 40. The second port of the second three-way pipe 43 is connected to the grouting and pressure-maintaining main pipe 3 via the second grouting hose 46. The third port of the second three-way pipe 43 is connected to the intelligent pressure-maintaining and grouting return main pipe 4 via the second grouting return hose 47.

[0050] The specific process of step (2) is as follows: According to the predetermined pulping amount, the PLC controller sends an instruction to the water pump connected to the inlet of the water supply pipe 8, and at the same time instructs the stirring motor 11 and the screw feeder to start and the water supply solenoid valve 9 to open, injecting a certain amount of water into the slurry storage tank 6. According to the information of the water supply flow meter 10, it is judged that the predetermined water volume has been reached and the water injection is stopped. The screw feeder quantitatively delivers the solid material into the slurry storage tank 6. The stirring motor 11 drives the stirrer 12 to start stirring, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The sealing material has good fluidity and a certain viscosity. The density sensor 13 and the viscosity sensor 14 are used to measure the viscosity and density information of the slurry in real time and transmit it to the PLC controller. After the slurry is qualified, the stirring motor 11 stops working.

[0051] The specific process of step (3) is as follows: the PLC controller instructs the fifth solenoid valve 16 and the sixth solenoid valve 19 to open, the downhole grouting pump 17 to start, and the grout is transported to the sealing location through the grouting pressure maintaining main pipe 3. The PLC controller sends a pressure signal value through the third pressure sensor 20 to control the fifth solenoid valve 16 and the sixth solenoid valve 19 on the grouting pressure maintaining main pipe 3 to realize the opening and closing of the pipeline and the start and stop of the downhole grouting pump 17, so that a certain grouting pressure is always maintained in the grouting pressure maintaining main pipe 3. The dual flexible bladder sealing device 5 is inserted into the borehole to the predetermined sealing depth. The PLC controller issues a sealing command, at which point the first solenoid valve 41 on the first three-way pipe 64 opens, and the grouting recovery pipe 32 inside the bladder begins to inject grout into the two first flexible bladders 30 and the second flexible bladder 31. When the first pressure sensor 37 detects that the set pressure value has been reached, the first solenoid valve 41 closes and the grouting stops. Then, the third solenoid valve 48 on the second three-way pipe 43 opens, and the grout begins to be injected into the middle section between the first flexible bladder 30 and the second flexible bladder 31 through the grouting recovery pipe 33 between the bladders, until the second pressure sensor 44 detects that the preset grouting pressure value has been reached. The PLC controller issues a command to close the third solenoid valve 48 to stop the grouting, and the sealing of the extraction borehole 29 is completed.

[0052] The specific process of dynamically maintaining pressure on the dual flexible bladder sealing device in step (5) is as follows: When the extraction borehole 29 deforms and the cross section increases, causing the pressure in the first flexible bladder 30 and / or the second flexible bladder 31 to decrease and be less than the predetermined constant pressure, the first pressure sensor 37 transmits the pressure monitoring data to the PLC controller. The PLC controller instructs the first solenoid valve 41 to open, and the grouting recovery pipe 32 inside the bladder starts to inject grout into the two first flexible bladders 30 and the second flexible bladder 31. When the first pressure sensor 37 detects that the set pressure value has been reached, the first solenoid valve 41 closes and stops grouting. Similarly, when the pressure drops in the middle section between the first flexible bladder 30 and the second flexible bladder 31 due to the continuous seepage of slurry into the fractures around the extraction borehole 29, the third solenoid valve 48 connected to the slurry recovery pipe 33 between the bladders opens, and the slurry begins to be replenished into the middle section between the first flexible bladder 30 and the second flexible bladder 31 through the slurry recovery pipe 33 until the second pressure sensor 44 detects that the preset slurry pressure value has been reached. The downhole PLC controller then issues a command to close the third solenoid valve 48 to stop the slurry replenishment.

[0053] When the effective diameter of the borehole 29 deforms due to mining, the pressure on the flexible sluice and intermediate section increases. When the pressure exceeds the set value, the first pressure sensor 37 and the second pressure sensor send pressure change information to the PLC controller. The PLC controller first sends an opening command to the fourth solenoid valve 49 and the seventh solenoid valve 22. The slurry in the intermediate section of the borehole will first enter the second slurry return hose 47 through the slurry recovery pipe 33 between the sluice and the third interface (slurry return port) of the second three-way pipe 43, flow into the intelligent pressure-maintaining slurry return main pipe 4, and finally flow into the slurry storage tank 6 of the roadway 28. When the value monitored by the second pressure sensor 44 reaches the set value, the fourth solenoid valve 49 and the seventh solenoid valve 22 close. Then, the PLC controller first sends an opening command to the second solenoid valve 42 and the seventh solenoid valve 22. The slurry in the first flexible sac 30 and the second flexible sac 31 will first enter the first return slurry hose 40 through the slurry recovery pipe 32 in the sac and the third interface (return slurry port) of the first three-way pipe 64, flow into the intelligent pressure-maintaining return slurry main pipe 4, and finally flow into the slurry storage tank 6 of the roadway 28. When the value monitored by the first pressure sensor 37 reaches the set value, the second solenoid valve 42 and the seventh solenoid valve 22 will close.

[0054] First, the slurry in the middle section is recovered, and then the slurry inside the first flexible bladder 30 and the second flexible bladder 31 is recovered. This sequential order avoids the situation where the pressure in the flexible bladder decreases and the pressure in the middle section increases, causing slurry leakage. It also ensures that the flexible bladder will not rupture due to increased pressure caused by borehole deformation.

[0055] The specific process for alarming and handling the loss of pressure in the dual flexible sac and intermediate segment in step (5) is as follows:

[0056] A) Alarm and handling of pressure loss in dual flexible bladders: When the flexible bladder ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor 37, and the grout injection cannot maintain the pressure of the flexible bladder, or when the pressure rises and then drops shortly, the system will stop injecting grout into the flexible bladder to prevent a large amount of grout from flowing into the borehole or tunnel 28, and will issue an audible and visual alarm to indicate that the flexible bladder in the borehole has lost pressure and ruptured. At this time, the flexible bladder in the borehole can be recovered first, and the damaged flexible bladder can be replaced before the borehole is sealed to ensure that the borehole can continue to be pumped normally.

[0057] B) Alarm and Handling of Pressure Loss in the Middle Section: When a large number of through-type fractures appear in the middle section of the borehole due to mining activities, resulting in severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor 44, and slurry injection fails to maintain pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into the borehole or roadway 28, and issue an audible and visual alarm to indicate pressure loss in the middle section. At this time, the gas concentration in a single borehole can be measured first. If the gas concentration in a single borehole does not decrease significantly, no action is needed. If the gas concentration in the borehole has decreased significantly compared to before, the borehole sealer can be retrieved, and the sealing position of the sealer or the density and viscosity of the sealing slurry in the middle section can be adjusted before resealing. If it is still difficult to maintain pressure, it proves that there are serious and large fractures around the borehole that are difficult to seal, and the borehole can be closed to prevent gas leakage from the borehole from causing an overall decrease in the gas concentration of the extraction pipeline.

[0058] The specific process of recovering the double flexible sac sealing device and slurry in step (6) is as follows: The PLC controller first sends an opening command to the fourth solenoid valve 49 and the seventh solenoid valve 22. The slurry in the middle section of the borehole will first enter the second slurry return hose 47 through the slurry recovery pipe 33 between the sacs and the third interface (slurry return port) of the second three-way pipe 43, flow into the intelligent pressure-maintaining slurry return main pipe 4, and then flow into the main slurry return pipe through the third three-way pipe. Under the action of the downhole slurry return pump 24, it finally flows into the slurry storage tank 6. When the value monitored by the second pressure sensor 44 reaches the set value, the fourth solenoid valve 49 and the seventh solenoid valve 22 are closed. Then, the PLC controller first sends an opening command to the second solenoid valve 42 and the seventh solenoid valve 22. The slurry in the first flexible sac 30 and the second flexible sac 31 will first enter the first slurry return hose 40 through the slurry recovery pipe 32 in the sac and the third interface (slurry return port) of the first three-way pipe 64, and flow into the intelligent pressure-maintaining slurry return main pipe 4. Under the action of the downhole slurry return pump 24, it finally flows into the slurry storage tank 6. When the value monitored by the first pressure sensor 37 reaches the set value, the second solenoid valve 42 and the seventh solenoid valve 22 are closed.

[0059] This embodiment does not impose any limitation on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A flexible, pressure-maintaining, recyclable, and intelligent sealing method for downhole extraction boreholes, characterized by: Includes the following steps: (1) A PLC controller, a slurry mixing container, a grouting pipe pump assembly and a return slurry pipe pump assembly are arranged in the underground roadway. A double flexible bladder sealer is installed in the extraction borehole. The lower part of the grouting mixing container is connected to the inlet of the grouting pipe pump assembly. The outlet of the grouting pipe pump assembly is connected to the inlet of the double flexible bladder sealer. The outlet of the double flexible bladder sealer is connected to the inlet of the return slurry pipe pump assembly. The outlet of the return slurry pipe pump assembly is connected to the top of the slurry mixing container. When arranging and connecting the various pipelines, valves, pump stations, flow sensors, pressure sensors and solenoid valves installed on the pipelines are also connected. (2) Prepare sealing slurry using a slurry storage and mixing container; (3) Grouting and sealing operations are performed into the double flexible bladder sealer; (4) Connect the gas extraction pipeline to the extraction borehole for gas extraction operation; (5) During the gas extraction operation, the underground slurry storage and transportation system dynamically maintains the pressure of the double flexible bladder sealing device, and alarms and handles the pressure loss of the double flexible bladder and intermediate section. (6) After the gas extraction is completed, the double flexible bladder sealer and slurry are recovered; The dual flexible bladder sealing device is installed inside the extraction borehole. The dual flexible bladder sealing device includes a first flexible bladder, a second flexible bladder, an intrabladder grouting recovery pipe, and an interbladder grouting recovery pipe. An extraction pipe is inserted into the central hole of the first and second flexible bladders. The first flexible bladder is located below the second flexible bladder. The intrabladder grouting recovery pipe passes through the first and second flexible bladders from bottom to top. The upper end of the intrabladder grouting recovery pipe is sealed. The intrabladder grouting recovery pipe has a first flexible bladder grouting recovery hole located in the first flexible bladder and a second flexible bladder grouting recovery hole located in the second flexible bladder. The upper end of the interbladder grouting recovery pipe passes through the first flexible bladder from bottom to top and extends between the first and second flexible bladders. The lower end of the intrasac grout recovery pipe is connected to a first tee pipe. The lower part of the intrasac grout recovery pipe is equipped with a first pressure sensor and a first flow sensor. The second port of the first tee pipe is equipped with a first solenoid valve, and the third port of the first tee pipe is equipped with a second solenoid valve. The lower end of the intersac grout recovery pipe is connected to a second tee pipe. The lower part of the intersac grout recovery pipe is equipped with a second pressure sensor and a second flow sensor. The second port of the second tee pipe is equipped with a third solenoid valve, and the third port of the second tee pipe is equipped with a fourth solenoid valve.

2. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 1, characterized in that: The slurry storage and mixing container includes a slurry storage tank. A solid raw material injection port is provided at the top of the slurry storage tank, and a screw feeder is connected to the solid raw material injection port. A water supply pipe is connected to the upper side of the slurry storage tank, and a water supply solenoid valve and a water supply flow meter are provided on the water supply pipe. A stirring motor is provided at the top of the slurry storage tank, and a stirrer is connected to the main shaft of the stirring motor inside the slurry storage tank. A density sensor and a viscosity sensor are provided in the lower middle part of the inner wall of the slurry storage tank, and a liquid level sensor is provided in the upper and lower parts of the inner wall of the slurry storage tank.

3. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 2, characterized in that: The grouting pipe pump assembly includes a grouting and pressure-maintaining main pipe. The inlet end of the grouting and pressure-maintaining main pipe is connected to the lower part of the grout storage tank. Along the grout flow direction, the grouting and pressure-maintaining main pipe is equipped with a fifth solenoid valve, a downhole grouting pump, a third flow sensor, a sixth solenoid valve, and a third pressure sensor in sequence.

4. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 3, characterized in that: The slurry return pipe pump assembly includes an intelligent pressure-maintaining slurry return main pipe, the outlet end of which is connected to the top of the slurry storage tank. Along the slurry flow direction, the intelligent pressure-maintaining slurry return main pipe is equipped with a fourth pressure sensor, a seventh solenoid valve, a fourth flow sensor, and a downhole slurry return pump. The second port of the first tee pipe is connected to the grouting and pressure-maintaining main pipe through the first grouting hose, and the third port of the first tee pipe is connected to the intelligent pressure-maintaining and grouting return main pipe through the first grout return hose. The second port of the second tee pipe is connected to the grouting and pressure-maintaining main pipe through the second grouting hose, and the third port of the second tee pipe is connected to the intelligent pressure-maintaining and grouting return main pipe through the second grout return hose.

5. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 4, characterized in that: The specific process of step (2) is as follows: According to the predetermined pulping volume, the PLC controller sends an instruction to the water pump connected to the water supply pipe inlet, and at the same time instructs the stirring motor and screw feeder to start and the water supply solenoid valve to open, injecting a certain amount of water into the slurry storage tank. According to the information of the water supply flow meter, the predetermined water volume is determined and the water injection is stopped. The screw feeder quantitatively transports the solid material into the slurry storage tank. The stirring motor drives the agitator to start stirring, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The density sensor and viscosity sensor are used to measure the viscosity and density information of the slurry in real time and transmit it to the PLC controller. After the slurry is qualified, the stirring motor stops working.

6. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 5, characterized in that: The specific process of step (3) is as follows: The PLC controller instructs the fifth and sixth solenoid valves to open, the downhole grouting pump starts, and the grout is transported to the sealing location through the grouting pressure maintaining main pipe. The PLC controller sends a pressure signal value through the third pressure sensor to control the fifth and sixth solenoid valves on the grouting pressure maintaining main pipe to realize the pipeline opening and closing and the start and stop of the downhole grouting pump, so that a certain grouting pressure is always maintained in the grouting pressure maintaining main pipe; the double flexible bladder sealing device is inserted into the predetermined sealing depth of the borehole, and the sealing command is issued through the PLC controller. At this time, the first three-way valve... The first solenoid valve on the pipe opens, and the grouting recovery pipe inside the sac begins to inject grout into the two first and second flexible sacs. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and the grouting stops. Then, the third solenoid valve on the second three-way pipe opens, and the grout begins to be injected into the middle section between the first and second flexible sacs through the grouting recovery pipe between the sacs until the second pressure sensor detects that the preset grouting pressure value has been reached. The PLC controller then issues a command to close the third solenoid valve to stop the grouting, and the extraction borehole is sealed.

7. The method for flexible pressure-maintaining and recyclable intelligent sealing of downhole extraction boreholes according to claim 6, characterized in that: The specific process of dynamically maintaining pressure for the dual flexible bladder sealing device in step (5) is as follows: When the cross-section of the extraction borehole deforms and increases, causing the pressure in the first flexible bladder and / or the second flexible bladder to decrease and be less than the predetermined constant pressure, the first pressure sensor transmits the pressure monitoring data to the PLC controller. The PLC controller instructs the first solenoid valve to open, and the grouting recovery pipe inside the bladder begins to inject grout into the two first flexible bladders and the second flexible bladder. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and stops grouting. Similarly, when the pressure drops in the middle section between the first flexible bladder and the second flexible bladder due to the appearance of cracks around the extraction borehole, the third solenoid valve connected to the grouting recovery pipe between the bladders opens, and the grout begins to be injected into the middle section between the first flexible bladder and the second flexible bladder through the grouting recovery pipe between the bladders until the second pressure sensor detects that the preset grouting pressure value has been reached. The downhole PLC controller then issues a command to close the third solenoid valve and stop grouting. When the borehole deforms and its effective diameter decreases due to mining activities, the pressure on the double flexible sluice and the intermediate section increases. When the pressure exceeds the set value, the first and second pressure sensors send pressure change information to the PLC controller. The PLC controller first sends an opening command to the fourth and seventh solenoid valves. The slurry in the intermediate section of the borehole will first enter the second slurry return hose through the grout recovery pipe between the sluices and the third interface of the second tee pipe, then flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank in the roadway. When the value monitored by the second pressure sensor reaches the set value, the fourth and seventh solenoid valves close. Then, the PLC controller first sends an opening command to the second and seventh solenoid valves. The slurry in the first and second flexible sluices will first enter the first slurry return hose through the grout recovery pipe inside the sluice and the third interface of the first tee pipe, then flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank in the roadway. When the value monitored by the first pressure sensor reaches the set value, the second and seventh solenoid valves close.

8. The method for constructing a flexible, pressure-maintaining, recyclable, and intelligent well-sealing borehole for downhole extraction drilling according to claim 7, characterized in that: The specific process for alarming and handling the loss of pressure in the dual flexible sac and intermediate segment in step (5) is as follows: A) Alarm and Handling of Pressure Loss in Dual Flexible Bubble: When a flexible bubbling ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor, and grout injection fails to maintain the bubbling pressure, or when pressure rises and then briefly drops, the system will stop injecting grout into the flexible bubbling to prevent a large amount of grout from flowing into the borehole or tunnel. An audible and visual alarm will be issued to indicate that the flexible bubbling in the borehole has ruptured due to pressure loss. In this case, the flexible bubbling in the borehole should be recovered first, and the ruptured flexible bubbling should be replaced before sealing the borehole to ensure that the borehole can continue to be pumped normally. B) Alarm and Handling of Pressure Loss in the Middle Section: When a large number of through-type fractures appear in the middle section of the borehole due to mining, resulting in severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor, and the injection of slurry cannot maintain pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into the borehole or roadway, and issue an audible and visual alarm to indicate that the middle section of the borehole is under pressure. At this time, the gas concentration in the single borehole is measured first. If the gas concentration in the single borehole does not decrease significantly, no action is taken. If the gas concentration in the borehole decreases significantly compared to before, the borehole sealer is retrieved, and the sealing position of the sealer or the density and viscosity of the sealing slurry in the middle section is adjusted before resealing. If it is still difficult to maintain pressure, it proves that there are serious and large fractures around the borehole that are difficult to seal. The borehole is then closed to prevent the overall gas concentration in the extraction pipeline from decreasing due to gas leakage in the borehole.

9. The method for constructing a flexible, pressure-maintaining, recyclable, and intelligent sealing borehole in downhole extraction drilling according to claim 8, characterized in that: The specific process of recovering the double flexible sluice bag sealing device and slurry in step (6) is as follows: The PLC controller first sends an opening command to the fourth and seventh solenoid valves. The slurry in the middle section of the borehole will first enter the second slurry return hose through the slurry recovery pipe between the sluice bags and the third interface of the second three-way pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and then flow into the main slurry return pipe through the third three-way pipe. Under the action of the downhole slurry return pump, it finally flows into the slurry storage tank. When the value monitored by the second pressure sensor reaches the set value, the fourth and seventh solenoid valves are closed. Then, the PLC controller first sends an opening command to the second and seventh solenoid valves. The slurry in the first and second flexible sluice bags will first enter the first slurry return hose through the slurry recovery pipe in the sluice bag and the third interface of the first three-way pipe, flow into the intelligent pressure-maintaining slurry return main pipe, and finally flow into the slurry storage tank under the action of the downhole slurry return pump. When the value monitored by the first pressure sensor reaches the set value, the second and seventh solenoid valves are closed.

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