A dynamic sealing system and method for gas drainage boreholes

Abstract

The present application discloses a dynamic sealing system and method for extraction boreholes, which belongs to the field of coal mine gas extraction. A grouting subsystem and an extraction subsystem are set in an extraction borehole. The grouting subsystem is provided with a grouting branch pipe, a first solenoid valve, a pressure relief valve, low-pressure and high-pressure one-way valves, and a bag; the extraction subsystem is provided with an extraction pipe, a concentration sensor, a pressure gauge, and a second solenoid valve; the low-pressure slurry is injected into the bag through two low-pressure one-way valves to achieve two blockages, and after pressurization, the sealing cavity is filled with slurry through the high-pressure one-way valve to achieve one injection; all grouting subsystems are connected to the grouting mechanism through the grouting main pipe. The first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, and the second solenoid valve of the present application can be intelligently linked to control the injection amount of slurry in the sealing cavity, so as to achieve long-term dynamic and stable sealing when the extraction borehole fails multiple times; and the pulse grouting pump in the grouting mechanism realizes intermittent pulse grouting by receiving pulse signals, which can effectively improve the sealing quality and stability.

Description

Technical Field

[0001] This application relates to the technical field of coal mine gas drainage, and particularly to a dynamic sealing system and method for drainage boreholes. Background Art

[0002] As China's coal resources gradually move towards the deep mining stage, the occurrence characteristics of "three highs and one low" in coal seams become more and more obvious. Due to the low strength of the coal and rock mass around the high-gas and low-permeability soft coal seams, there are often micro-cracks around the borehole sealing section. These micro-cracks will become gas leakage channels, resulting in significant losses when the drainage negative pressure is transmitted to the coal seam, making it difficult to effectively extract gas, which will directly affect the drainage efficiency. In addition, the existence of micro-cracks will change the physical structure of the coal seam, reduce the coal seam permeability, and increase the flow resistance of gas in the coal seam, thus increasing the drainage difficulty. Due to the existence of micro-cracks, gas is prone to leak into the surrounding environment during the drainage process, resulting in a decrease in the concentration of the extracted gas. Low-concentration gas not only reduces the drainage efficiency but also increases the cost and difficulty of subsequent treatment.

[0003] Furthermore, during the deep mining process, factors such as mining disturbance, roadway excavation, periodic roof weighting, and blasting vibration will all interfere with the boreholes in which gas drainage is being carried out in the coal seam. This interference will cause the strength of the coal body around the gas drainage boreholes to be further reduced, the compressive capacity to be weakened, and it is extremely prone to plastic deformation under pressure, resulting in a large number of conductive micro-cracks in the coal and rock mass around the borehole. Subsequently, new micro-cracks will further evolve in the borehole and the surrounding conductive micro-cracks, thereby causing the loosening of the sealing section and directly affecting the sealing performance and drainage efficiency of the borehole. Even if ideal drainage effects can be achieved in the initial stage of gas drainage, with the continuous intensification of these disturbance effects, the sealing performance of the borehole and the subsequent drainage results will also be gradually adversely affected.

[0004] At present, the traditional grouting process and method can only play a certain role in plugging the borehole and the micro-cracks around the borehole, but cannot play a role in plugging the new cracks derived from the subsequent factors. At the same time, the traditional solid sealing materials cannot deform with the stress of the borehole and are extremely prone to cause the failure of borehole sealing.

[0005] The existing secondary plugging system and method for boreholes to improve gas drainage effect propose secondary plugging and sealing. However, due to the complex and changeable geological conditions of the coal seam, this method can only plug the failed boreholes once and cannot achieve long-term dynamic and stable plugging when the subsequent drainage boreholes fail multiple times. After judging the sealed failed boreholes, it is necessary to manually control the liquid separation regulator to connect the pump liquid pipeline with the liquid injection pipe in the failed boreholes, and the degree of intelligence is low. Summary of the Invention

[0006] The embodiments of the present application provide a dynamic sealing system and method for gas drainage boreholes, which can solve the problems that the existing methods cannot achieve long-term dynamic stable plugging when subsequent gas drainage boreholes fail multiple times and have low intelligence level.

[0007] To achieve the above object, the technical solution of the embodiments of the present invention is as follows:

[0008] In a first aspect, the embodiments of the present invention provide a dynamic sealing system for gas drainage boreholes, including a control mechanism, a grouting mechanism, a main grouting pipe, a grouting subsystem and a gas drainage subsystem;

[0009] The grouting subsystem includes a grouting branch pipe, a first solenoid valve, a pressure relief valve, a low-pressure check valve, a high-pressure check valve and a bladder;

[0010] The first solenoid valve, the pressure relief valve, the low-pressure check valve, the high-pressure check valve and the low-pressure check valve are sequentially arranged on the grouting branch pipe;

[0011] One bladder is arranged at each position of the two low-pressure check valves on the grouting branch pipe, and the low-pressure check valve communicates with the grouting branch pipe and the bladder;

[0012] One grouting branch pipe is arranged in one gas drainage borehole, so that the two bladders arranged on the grouting branch pipe are arranged in the gas drainage borehole, and a sealing cavity is formed between the two bladders after being filled with slurry. The sealing cavity is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole, and the high-pressure check valve is located in the sealing cavity and communicates with the grouting branch pipe and the sealing cavity;

[0013] One end of all the grouting branch pipes is communicated with one end of the main grouting pipe;

[0014] The other end of the main grouting pipe is communicated with the grouting mechanism;

[0015] The gas drainage subsystem includes a gas drainage branch pipe, a concentration sensor, a pressure gauge and a second solenoid valve;

[0016] The concentration sensor, the pressure gauge and the second solenoid valve are arranged on the gas drainage branch pipe;

[0017] One end of one gas drainage branch pipe extends into one gas drainage borehole, and the other ends of all the gas drainage branch pipes are communicated with one end of the main gas drainage pipe;

[0018] The first solenoid valve, the pressure relief valve, the low-pressure check valve, the high-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve and the grouting mechanism are all electrically connected to the control mechanism.

[0019] In combination with the first aspect, in a possible implementation manner, the slurry uses a low-viscosity sealing slurry.

[0020] In combination with the first aspect, in a possible implementation manner, the control mechanism includes a monitoring sub-station, a programmable logic controller, and a ground monitoring platform;

[0021] The first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism are all electrically connected to the monitoring sub-station;

[0022] The monitoring sub-station and the programmable logic controller are electrically connected;

[0023] The programmable logic controller is electrically connected to the ground monitoring platform.

[0024] In combination with the first aspect, in a possible implementation manner, the dynamic sealing system for gas drainage boreholes further includes an explosion-proof power supply;

[0025] The monitoring sub-station is electrically connected to the explosion-proof power supply;

[0026] The explosion-proof power supply is electrically connected to the programmable logic controller.

[0027] In a second aspect, an embodiment of the present invention provides a dynamic sealing method for gas drainage boreholes. Based on the above-mentioned dynamic sealing system for gas drainage boreholes, it includes:

[0028] A first solenoid valve, a pressure relief valve, a low-pressure check valve, a high-pressure check valve, and a low-pressure check valve are sequentially arranged on the grouting branch pipe; a bladder is respectively arranged at the positions of the two low-pressure check valves on the grouting branch pipe, and the low-pressure check valve communicates with the grouting branch pipe and the bladder;

[0029] One grouting branch pipe is arranged in one gas drainage borehole, so that the two bladders arranged on the grouting branch pipe are arranged in the gas drainage borehole, and a sealing cavity is formed between the two bladders after being filled with slurry. The sealing cavity is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole, and the high-pressure check valve is located in the sealing cavity and communicates with the grouting branch pipe and the sealing cavity;

[0030] One end of all the grouting branch pipes is communicated with one end of the grouting main pipe; the other end of the grouting main pipe is communicated with the grouting mechanism;

[0031] A concentration sensor, a pressure gauge, and a second solenoid valve are arranged on the gas drainage branch pipe; one end of one gas drainage branch pipe extends into one gas drainage borehole, and the other ends of all the gas drainage branch pipes are communicated with one end of the gas drainage main pipe;

[0032] Electrically connect the first solenoid valve, the pressure relief valve, the low-pressure check valve, the high-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the control mechanism;

[0033] The control mechanism controls the grouting mechanism, the first solenoid valve, and the two low-pressure check valves to open, and injects slurry into the bladder provided at the positions of the two low-pressure check valves on each grouting branch pipe through the grouting main pipe and the grouting branch pipe until a sealed cavity is formed between the two bladders after the slurry is filled. Then, the control mechanism controls the high-pressure check valve to open, so that the sealed cavity is filled with slurry. After that, the control mechanism controls the first solenoid valve to close and the second solenoid valve to open, and starts the gas drainage operation;

[0034] After that, perform the dynamic sealing step multiple times. The dynamic sealing step includes: the concentration sensor monitors the gas drainage concentration value of the drainage branch pipe and transmits the gas drainage concentration value to the control mechanism; when the gas drainage concentration value is less than the preset concentration value, the control mechanism controls the second solenoid valve to close for a first preset time; if the control mechanism monitors that the pressure of the pressure gauge within the first preset time is less than the preset pressure value, the control mechanism controls the first solenoid valve to open and controls the grouting mechanism to grout intermittently until the control mechanism monitors that the grouting pressure reaches the upper limit pressure of the pressure relief valve, the control mechanism controls the first solenoid valve to close and the second solenoid valve to open, and continues the gas drainage operation.

[0035] In combination with the second aspect, in a possible implementation manner, the slurry uses a low-viscosity sealing slurry.

[0036] In combination with the second aspect, in a possible implementation manner, the electrically connecting the first solenoid valve, the pressure relief valve, the low-pressure check valve, the high-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the control mechanism includes:

[0037] Electrically connect the first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the monitoring sub-station;

[0038] Electrically connect the monitoring sub-station and the programmable logic controller;

[0039] Electrically connect the programmable logic controller to the ground monitoring platform.

[0040] In combination with the second aspect, in a possible implementation manner, the dynamic sealing method for the drainage borehole further includes: electrically connecting the monitoring sub-station to the explosion-proof power supply;

[0041] The explosion-proof power supply is electrically connected to the editable logic controller.

[0042] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0043] The dynamic sealing system for the extraction borehole provided by the embodiment of the present invention forms a sealing cavity between two bags, and the sealing cavity is filled with slurry. The dynamic sealing effect of the extraction borehole is judged by the linkage control between the concentration sensor and the pressure gauge, and the monitoring data is transmitted to the control mechanism, and the control mechanism controls the operation of the grouting mechanism according to the monitoring data. The first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, and the second solenoid valve can be intelligently linked to control the injection amount of the slurry in the sealing cavity to achieve dynamic sealing of the extraction borehole. When the dynamic sealing of the extraction borehole fails, the extraction borehole can be quickly sealed without a limit on the number of times, and long-term dynamic and stable sealing can be achieved when the extraction borehole fails multiple times. In addition, the first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, and the second solenoid valve in the embodiment of the present application are intelligently linked and controlled by the control mechanism, and the degree of intelligence is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A schematic structural diagram of a dynamic sealing system for a drainage borehole provided in an embodiment of the present application;

[0046] Figure 2 A partial schematic diagram of the dynamic sealing system for extraction drilling provided in the embodiment of the present application Figure 1 ;

[0047] Figure 3 A partial schematic diagram of the dynamic sealing system for extraction drilling provided in the embodiment of the present application Figure 2 ;

[0048] Figure 4 A partial schematic diagram of the dynamic sealing system for extraction drilling provided in the embodiment of the present application Figure 3 ;

[0049] Figure 5 A partial schematic diagram of the dynamic sealing system for extraction drilling provided in the embodiment of the present application Figure 4 .

[0050] Icons: 1 - Grouting branch pipe; 2 - Grouting main pipe; 3 - First solenoid valve; 4 - Pressure relief valve; 5 - Low-pressure check valve; 6 - High-pressure check valve; 7 - Bladder bag; 8 - Concentration sensor; 9 - Pressure gauge; 10 - Second solenoid valve; 20 - Grouting mechanism; 201 - Grouting cylinder; 202 - Pulse grouting pump; 30 - Control mechanism; 301 - Monitoring sub-station; 302 - Programmable logic controller; 303 - Ground monitoring platform; 40 - Explosion-proof power supply; 50 - Drainage branch pipe; 60 - Drainage main pipe; 70 - Automatic water drainer; 80 - Gas drainage pump; A - Sealed cavity; B - Coal seam; C - Drainage borehole. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. The terms "first", "second", and "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance. In addition, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0053] Please refer to Figure 1 As shown, the embodiments of the present invention provide a dynamic sealing system for drainage boreholes, including a control mechanism 30, a grouting mechanism 20, a grouting main pipe 2, a grouting subsystem, and a drainage subsystem;

[0054] The grouting subsystem includes a grouting branch pipe 1, a first solenoid valve 3, a pressure relief valve 4, a low-pressure check valve 5, a high-pressure check valve 6, and a bladder bag 7.

[0055] As Figures 1 to 5As shown, a first solenoid valve 3, a pressure relief valve 4, a low-pressure check valve 5, a high-pressure check valve 6, and a low-pressure check valve 5 are sequentially arranged on the grouting branch pipe 1.

[0056] At the positions of the two low-pressure check valves 5 on the grouting branch pipe 1, a bladder 7 is respectively arranged, and the low-pressure check valve 5 communicates with the grouting branch pipe 1 and the bladder 7.

[0057] As Figures 2 to 5 shown, a grouting branch pipe 1 is arranged in a gas drainage borehole C, so that the two bladders 7 arranged on the grouting branch pipe 1 are arranged in the gas drainage borehole C, and a sealed cavity A is formed between the two bladders 7 after being filled with slurry. As Figure 2 shown, the sealed cavity A is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole C, and the high-pressure check valve 6 is located in the sealed cavity A and communicates with the grouting branch pipe 1 and the sealed cavity A.

[0058] As Figure 1 shown, one end of all the grouting branch pipes 1 is communicated with one end of the grouting main pipe 2. The other end of the grouting main pipe 2 is communicated with the grouting mechanism 20. That is, all the grouting subsystems are communicated with the grouting mechanism 20 through the grouting main pipe 2.

[0059] The gas drainage subsystem includes a gas drainage branch pipe 50, a concentration sensor 8, a pressure gauge 9, and a second solenoid valve 10. The concentration sensor 8, the pressure gauge 9, and the second solenoid valve 10 are arranged on the gas drainage branch pipe 50.

[0060] One end of a gas drainage branch pipe 50 extends into a gas drainage borehole C, and the other ends of all the gas drainage branch pipes 50 are communicated with one end of the gas drainage main pipe 60. The other end of the gas drainage main pipe 60 is communicated with an automatic water drainer 70, and the automatic water drainer 70 is communicated with a gas drainage pump 80. That is, one set of grouting subsystem and gas drainage subsystem is arranged in a gas drainage borehole C.

[0061] The first solenoid valve 3, the pressure relief valve 4, the low-pressure check valve 5, the high-pressure check valve 6, the concentration sensor 8, the pressure gauge 9, the second solenoid valve 10, and the grouting mechanism 20 are all electrically connected to the control mechanism 30. The pressure gauge 9 can be an intelligent digital display pressure gauge.

[0062] The grouting mechanism 20 includes a grouting cylinder 201 and a pulse grouting pump 202. The grouting cylinder 201 is communicated with the pulse grouting pump 202, and the pulse grouting pump 202 is communicated with the other end of the grouting main pipe 2. The grouting cylinder 201 and the pulse grouting pump 202 are both electrically connected to the control mechanism 30.

[0063] In the gas drainage borehole dynamic sealing system provided by the embodiments of the present invention, during actual operation, first, a first solenoid valve 3, a pressure relief valve 4, a low-pressure check valve 5, a high-pressure check valve 6, and a low-pressure check valve 5 are sequentially arranged on the grouting branch pipe 1. At the positions of the two low-pressure check valves 5 on the grouting branch pipe 1, a bladder 7 is respectively arranged, and the low-pressure check valve 5 communicates with the grouting branch pipe 1 and the bladder 7. Then, a grouting branch pipe 1 is arranged in a gas drainage borehole C, and the two bladders 7 arranged on the grouting branch pipe 1 are arranged in the gas drainage borehole C, so that a sealing cavity A is formed between the two bladders 7 after being filled with slurry. The sealing cavity A is located between the elastic zone and the original stress zone in the stress concentration zone of the gas drainage borehole C. The high-pressure check valve 6 is located in the sealing cavity A and communicates with the grouting branch pipe 1 and the sealing cavity A. The low-pressure check valve 5 and the high-pressure check valve 6 are check valves, which can prevent the slurry from flowing back.

[0064] Then, one end of all the grouting branch pipes 1 is connected to one end of the grouting main pipe 2. The other end of the grouting main pipe 2 is connected to the grouting mechanism 20.

[0065] After that, a concentration sensor 8, a pressure gauge 9, and a second solenoid valve 10 are arranged on the gas drainage branch pipe 50. One end of a gas drainage branch pipe 50 extends into a gas drainage borehole C, and the other ends of all the gas drainage branch pipes 50 are connected to one end of the gas drainage main pipe 60.

[0066] Finally, the first solenoid valve 3, the pressure relief valve 4, the low-pressure check valve 5, the high-pressure check valve 6, the concentration sensor 8, the pressure gauge 9, the second solenoid valve 10, and the grouting mechanism 20 are all electrically connected to the control mechanism 30, completing the installation of the gas drainage borehole dynamic sealing system.

[0067] When performing the "two-block one-injection" operation, the control mechanism 30 controls the grouting mechanism 20, the first solenoid valve 3, and the two low-pressure check valves 5 to open, and injects low-pressure slurry into the bladders 7 arranged at the positions of the two low-pressure check valves 5 on each grouting branch pipe 1 through the grouting main pipe 2 and the grouting branch pipe 1 until a sealing cavity A is formed between the two bladders 7 after being filled with slurry. The low-pressure slurry is injected into the bladders 7 through the two low-pressure check valves 5 to achieve the two blocks. Then, the control mechanism 30 controls the high-pressure check valve 6 to open, so that the sealing cavity A is filled with slurry, thereby forming a hole-sealing section, that is, after pressurization, the sealing cavity A is filled with slurry through the high-pressure check valve 6 to achieve one injection. The hole-sealing section of the gas drainage borehole C is arranged between the elastic zone and the original stress zone in the stress concentration zone by using the "two-block one-injection" hole-sealing method. The two bladders 7 realize the sealing of the sealing cavity A, and the two bladders 7 and the hole-sealing section jointly realize the sealing of the gas drainage borehole C. Then, the control mechanism 30 controls the first solenoid valve 3 to close, and the second solenoid valve 10 to open, starting the gas drainage operation.

[0068] In practice, in the gas drainage drill field, affected by mining activities, when the sealing cavity A of the gas drainage borehole C is filled with slurry and micro-cracks occur around the grouting section, resulting in air leakage when the sealing of the gas drainage borehole C fails, the gas drainage concentration will decrease accordingly.

[0069] At this time, the dynamic sealing steps are executed multiple times. The dynamic sealing steps include: the concentration sensor 8 monitors the gas drainage concentration value of the gas drainage branch pipe 50 and transmits the gas drainage concentration value to the control mechanism 30. When the gas drainage concentration value is less than the preset concentration value (for example, the preset concentration value can be 50% of the normal gas drainage concentration value, and the specific value of the preset concentration value can be set according to the gas drainage parameters of each coal mine working face. When the gas drainage concentration value is less than the preset concentration value, the sealing effect of the gas drainage borehole C deteriorates at this time), the control mechanism 30 controls the second solenoid valve 10 to close for the first preset time (for example, the first preset time can be 30 minutes). If the control mechanism 30 monitors that the pressure of the pressure gauge 9 within the first preset time is less than the preset pressure value (that is, the pressure value shown by the pressure gauge 9 remains unchanged or increases slowly, which proves that the sealing of the gas drainage borehole C fails; if the pressure of the pressure gauge 9 continues to rise, it proves that the sealing of the gas drainage borehole C is intact), the control mechanism 30 controls the first solenoid valve 3 to open and controls the grouting mechanism 20 to perform intermittent grouting (the control mechanism 30 transmits a pulse signal to the grouting mechanism 20, thereby realizing intermittent pulse grouting of the grouting mechanism 20. Compared with the ordinary equal-pressure grouting process, intermittent pulse grouting forms more seepage channels and forms a relatively stable "network skeleton" composed of multiple seepage channels around the grouting section, which can effectively improve the sealing quality and stability. In addition, intermittent pulse grouting enables the grouting slurry to be more effectively injected into the sealing cavity A under the intermittent action of the grouting pressure, and then intermittently pressed into the micro-cracks, as Figure 4 and Figure 5 shown, so that the micro-cracks can be better blocked. Thus, pulse grouting and pulse dynamic grouting can improve the borehole sealing performance while reducing the grouting volume, and then improve the gas drainage efficiency), until the control mechanism 30 monitors that the grouting pressure reaches the upper limit pressure of the pressure relief valve 4 (setting the pressure relief valve 4 can prevent the grouting mechanism 20 from continuously grouting, resulting in excessive pressure in the grouting branch pipe 1 or the enclosed space, which may damage the dynamic sealing system of the gas drainage borehole or cause damage to the surrounding wall surface of the grouting section formed by the sealing cavity A, thereby ensuring the plugging effect of dynamic sealing, effectively ensuring the subsequent dynamic sealing quality, and improving the reliability and durability of the sealing), the control mechanism 30 controls the first solenoid valve 3 to close and the second solenoid valve 10 to open (the first solenoid valve 3 and the second solenoid valve 10 have interlocking control. When the first solenoid valve 3 is open, the second solenoid valve 10 is closed; when the first solenoid valve 3 is closed, the second solenoid valve 10 is open), and continue the gas drainage operation to achieve efficient gas drainage from coal seam B.

[0070] The dynamic sealing system for gas drainage boreholes provided by the embodiments of the present invention forms a sealed cavity A between two bladder bags 7, fills the sealed cavity A with slurry, judges the sealing effect of the gas drainage borehole C through the interlocking control between the concentration sensor 8 and the pressure gauge 9, and transmits the monitoring data to the control mechanism 30. The control mechanism 30 controls the operation of the grouting mechanism 20 according to the monitoring data. The first solenoid valve 3, the pressure relief valve 4, the concentration sensor 8, the pressure gauge 9 and the second solenoid valve 10 can intelligently interlock to control the injection volume of the slurry in the sealed cavity A, realizing the dynamic plugging of the gas drainage borehole C. When the seal of the gas drainage borehole C fails, the gas drainage borehole C can be quickly plugged without limit on the number of times, and long-term dynamic stable sealing can be achieved when the gas drainage borehole C fails multiple times. In addition, the first solenoid valve 3, the pressure relief valve 4, the concentration sensor 8, the pressure gauge 9 and the second solenoid valve 10 in the embodiments of the present application are intelligently interlocked through the control mechanism 30, with a high degree of intelligence.

[0071] The embodiments of the present application solve the problems of partial failure of the gas drainage borehole C in the drill field under the current disturbance, high sealing cost, serious air leakage, low drainage purity, etc. The intelligent interlocking control between components can accurately and efficiently locate the sealing failure borehole and perform targeted sealing on the failure borehole caused by mining movement. Compared with the traditional process of increasing the grouting length of the sealing section to improve the borehole sealing performance, it is more targeted and goal-oriented. And it can also realize the dynamic sealing when the subsequent boreholes fail multiple times, making the sealing process more accurate and reliable, with long-term stability and reliable durability.

[0072] At the same time, the characteristics of intermittent grouting can improve the sealing quality and stability, and then improve the drainage effect, with good economic benefits. It provides strong technical support for promoting the green development of the coal industry and helping to achieve the national "dual carbon goals", and is of great significance for promoting the optimization and upgrading of the energy structure.

[0073] Furthermore, the slurry uses a low-viscosity sealing slurry, so as to better realize the dynamic sealing of the gas drainage borehole C. A preparation method for a kind of slurry provided by the embodiments of the present application is as follows: using sodium-based bentonite with good expansibility as the base material, adding sodium carboxymethylcellulose as the binder, and supplementing fatty acid methyl ester sulfonate (MES) and polyacrylamide (PAM) as the surfactant and water retention agent respectively. The mixing ratio of MES and PAM is: the dosage of MES is 4%, the dosage of PAM is 0.8%, and the water-to-material ratio is 10:1. The measured viscosity of the prepared low-viscosity sealing slurry is 77 mPa·s.

[0074] Optionally, as Figure 1As shown in the figure, the control mechanism 30 includes a monitoring sub-station 301, a programmable logic controller 302, and a ground monitoring platform 303. The first solenoid valve 3, the pressure relief valve 4, the concentration sensor 8, the pressure gauge 9, the second solenoid valve 10, and the grouting mechanism 20 are all electrically connected to the monitoring sub-station 301. The monitoring sub-station 301 is electrically connected to the programmable logic controller 302. The programmable logic controller 302 is electrically connected to the ground monitoring platform 303.

[0075] The monitoring data is transmitted to the programmable logic controller 302 through the monitoring sub-station 301, and then transmitted to the intelligent control center in the ground monitoring platform 303. The intelligent control center gives corresponding control instructions and conducts operations. The intelligent control center is a conventional computer control system, which is an existing device and program, and will not be elaborated here.

[0076] Further, when the grouting mechanism 20 includes a grouting cylinder 201 and a pulse grouting pump 202, the grouting cylinder 201 and the pulse grouting pump 202 are electrically connected to the monitoring sub-station 301. The programmable logic controller 302 transmits a pulse signal to the monitoring sub-station 301, and the monitoring sub-station 301 transmits the pulse signal to the pulse grouting pump 202, so as to realize the intermittent pulse grouting of the pulse grouting pump 202 into the sealing cavity A and realize dynamic pulse sealing.

[0077] The pulse grouting can realize intermittent pulse grouting, which is achieved by the reciprocating movement of the piston in the power structure of the pulse grouting pump 202. The reciprocating movement of the piston forms a pulse pressure in the grouting branch pipe 1. This pulse pressure is non-constant and has a non-constant change rate. It changes the action mode of the constant pressure, so that the grouting slurry can be more effectively injected into the sealing cavity A under the action of pressure, and then be pressed into the micro-cracks, such as Figure 4 and Figure 5 As shown, after the micro-cracks in the coal seam B are better blocked and a relatively stable network skeleton is formed, the gas drainage operation of the coal seam B is carried out. The pulse grouting pump 202 in the grouting mechanism 20 realizes intermittent pulse grouting by receiving the pulse signal of the programmable logic controller 302, which can effectively improve the hole sealing quality and stability.

[0078] Further, as Figure 1 shown, the dynamic sealing system for the drainage borehole also includes an explosion-proof power supply 40. The monitoring sub-station 301 is electrically connected to the explosion-proof power supply 40. The explosion-proof power supply 40 is electrically connected to the programmable logic controller 302. Thus, the explosion-proof power supply 40 can supply power to all structures connected to the monitoring sub-station 301 and the programmable logic controller.

[0079] Another embodiment of the present invention provides a method for sealing the drainage borehole C, based on the above-mentioned dynamic sealing system for the drainage borehole, including:

[0080] Construct the drainage boreholes C in sequence according to the layout plan in the coal seam B in the drill site.

[0081] A first solenoid valve 3, a pressure relief valve 4, a low-pressure check valve 5, a high-pressure check valve 6 and a low-pressure check valve 5 are successively arranged on the grouting branch pipe 1. A bladder 7 is respectively arranged at the positions of the two low-pressure check valves 5 on the grouting branch pipe 1, and the low-pressure check valve 5 communicates with the grouting branch pipe 1 and the bladder 7.

[0082] A grouting branch pipe 1 is arranged in a gas drainage borehole C, so that the two bladders 7 arranged on the grouting branch pipe 1 are arranged in the gas drainage borehole C, and a sealed cavity A is formed between the two bladders 7 after being filled with slurry. The sealed cavity A is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole C. The high-pressure check valve 6 is located in the sealed cavity A and communicates with the grouting branch pipe 1 and the sealed cavity A.

[0083] One end of all the grouting branch pipes 1 is communicated with one end of the grouting main pipe 2. The other end of the grouting main pipe 2 is communicated with the grouting mechanism 20.

[0084] A concentration sensor 8, a pressure gauge 9 and a second solenoid valve 10 are arranged on the gas drainage branch pipe 50. One end of a gas drainage branch pipe 50 extends into a gas drainage borehole C, and the other ends of all the gas drainage branch pipes 50 are communicated with one end of the gas drainage main pipe 60.

[0085] The first solenoid valve 3, the pressure relief valve 4, the low-pressure check valve 5, the high-pressure check valve 6, the concentration sensor 8, the pressure gauge 9, the second solenoid valve 10 and the grouting mechanism 20 are all electrically connected to the control mechanism 30, and the installation of the dynamic sealing system for the gas drainage borehole is completed.

[0086] When carrying out the "two-block one-injection" operation, the control mechanism 30 controls the grouting mechanism 20, the first solenoid valve 3 and the two low-pressure check valves 5 to open, and injects slurry into the bladder 7 arranged at the positions of the two low-pressure check valves 5 on each grouting branch pipe 1 through the grouting main pipe 2 and the grouting branch pipe 1 until a sealed cavity A is formed between the two bladders 7 after being filled with slurry. Then the control mechanism 30 controls the high-pressure check valve 6 to open, so that the sealed cavity A is filled with slurry, thereby forming a sealing section. That is, the sealing sections of the gas drainage borehole C are arranged between the elastic zone and the original stress zone in the stress concentration area by using the "two-block one-injection" sealing method. The two bladders 7 realize the plugging of the sealed cavity A, and the two bladders 7 and the sealing section jointly realize the plugging of the gas drainage borehole C. Then the control mechanism 30 controls the first solenoid valve 3 to close and the second solenoid valve 10 to open, and starts the gas drainage operation.

[0087] In practice, in the gas drainage drill field, affected by the mining action, when the sealing section formed by filling the sealed cavity A of the gas drainage borehole C with slurry generates micro-cracks and causes the sealing of the gas drainage borehole C to fail, air leakage will occur, which will further lead to a decrease in the drainage concentration.

[0088] After performing the dynamic sealing step multiple times, the dynamic sealing step includes: the concentration sensor 8 monitors the gas extraction concentration value of the extraction branch pipe 50 and transmits the gas extraction concentration value to the control mechanism 30. When the gas extraction concentration value is less than the preset concentration value (for example, the preset concentration value can be 50% of the normal extraction concentration value, and the specific value of the preset concentration value can be set according to the extraction parameter differences of each coal mine working face. When the gas extraction concentration value is less than the preset concentration value, at this time, the sealing effect of the extraction borehole C becomes worse), the control mechanism 30 controls the second solenoid valve 10 to close for the first preset time (for example, the first preset time can be 30 minutes). If the control mechanism 30 monitors that the pressure of the pressure gauge 9 within the first preset time is less than the preset pressure value (that is, the pressure value displayed by the pressure gauge 9 remains unchanged or increases slowly, which proves that the sealing of the extraction borehole C fails. If the pressure of the pressure gauge 9 continues to rise, it proves that the sealing of the extraction borehole C is intact), the control mechanism 30 controls the first solenoid valve 3 to open and controls the grouting mechanism 20 to perform intermittent grouting (the control mechanism 30 transmits a pulse signal to the grouting mechanism 20, thereby realizing intermittent pulse grouting of the grouting mechanism 20. Compared with the ordinary equal-pressure grouting process, intermittent pulse grouting forms more seepage channels and forms a relatively stable "network skeleton" composed of multiple seepage channels around the sealing section, which can effectively improve the sealing quality and stability. In addition, intermittent pulse grouting enables the grouting slurry to be more effectively injected into the sealing cavity A under the intermittent action of the grouting pressure, and then is intermittently pressed into the microcracks, such as Figure 4 and Figure 5 shown, so that the microcracks are better blocked. Thus, pulse grouting and pulse dynamic grouting can improve the borehole sealing performance while reducing the grouting volume, and then improve the gas extraction efficiency), until the control mechanism 30 monitors that the grouting pressure reaches the upper limit pressure of the pressure relief valve 4 (setting the pressure relief valve 4 can prevent the grouting mechanism 20 from continuously grouting and causing excessive pressure in the grouting branch pipe 1 or the enclosed space, thereby damaging the dynamic sealing system of the extraction borehole, or damaging the surrounding wall surface of the sealing section formed by the sealing cavity A, thus ensuring the plugging effect of the dynamic sealing, effectively ensuring the subsequent dynamic sealing quality, and improving the reliability and durability of the sealing). The control mechanism 30 controls the first solenoid valve 3 to close and the second solenoid valve 10 to open (the first solenoid valve 3 and the second solenoid valve 10 have interlocking control. When the first solenoid valve 3 is open, the second solenoid valve 10 is closed. When the first solenoid valve 3 is closed, the second solenoid valve 10 is open), and continue the gas extraction operation to achieve efficient gas extraction from coal seam B.

[0089] The C-sealing method for gas drainage boreholes provided by the embodiments of the present invention forms a sealed cavity A between two bladder bags 7, fills the sealed cavity A with slurry, judges the sealing effect of the gas drainage borehole C through the interlocking control between a concentration sensor 8 and a pressure gauge 9, and transmits the monitoring data to a control mechanism 30. The control mechanism 30 controls the operation of a grouting mechanism 20 according to the monitoring data. An intelligent interlocking control can be achieved among a first electromagnetic valve 3, a pressure relief valve 4, the concentration sensor 8, the pressure gauge 9, and a second electromagnetic valve 10 to control the injection volume of the slurry in the sealed cavity A, realizing the dynamic plugging of the gas drainage borehole C. When the seal of the gas drainage borehole C fails, the borehole C can be quickly plugged without any limit on the number of times, and long-term dynamic stable sealing can be achieved when the gas drainage borehole C fails multiple times. In addition, in the embodiments of the present application, an intelligent interlocking control is performed among the first electromagnetic valve 3, the pressure relief valve 4, the concentration sensor 8, the pressure gauge 9, and the second electromagnetic valve 10 through the control mechanism 30, with a high degree of intelligence.

[0090] Among them, a low-viscosity sealing slurry is used as the slurry, thereby further facilitating the subsequent dynamic sealing of the gas drainage borehole C.

[0091] Further, the first electromagnetic valve 3, the pressure relief valve 4, a low-pressure check valve 5, a high-pressure check valve 6, the concentration sensor 8, the pressure gauge 9, the second electromagnetic valve 10, and the grouting mechanism 20 are all electrically connected to the control mechanism 30, including:

[0092] The first electromagnetic valve 3, the pressure relief valve 4, the concentration sensor 8, the pressure gauge 9, the second electromagnetic valve 10, and the grouting mechanism 20 are all electrically connected to a monitoring sub-station 301.

[0093] The monitoring sub-station 301 is electrically connected to a programmable logic controller 302.

[0094] The programmable logic controller 302 is electrically connected to a ground monitoring platform 303.

[0095] Optionally, the C-sealing method for the gas drainage borehole C further includes: electrically connecting the monitoring sub-station 301 to an explosion-proof power supply 40. Electrically connecting the explosion-proof power supply 40 to the programmable logic controller 302.

[0096] The various embodiments in this specification are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

[0097] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A dynamic sealing method for gas drainage boreholes, characterized in that The dynamic sealing system for gas drainage boreholes includes a control mechanism, a grouting mechanism, a main grouting pipe, a grouting subsystem, and a gas drainage subsystem; The grouting subsystem includes a grouting branch pipe, a first solenoid valve, a pressure relief valve, a first low-pressure check valve, a high-pressure check valve, a second low-pressure check valve, and a bladder; The first solenoid valve, the pressure relief valve, the first low-pressure check valve, the high-pressure check valve, and the second low-pressure check valve are sequentially arranged on the grouting branch pipe; One bladder is respectively arranged at the positions of the first low-pressure check valve and the second low-pressure check valve on the grouting branch pipe, and the first low-pressure check valve and the second low-pressure check valve connect the grouting branch pipe and the bladder at the corresponding position; One grouting branch pipe is arranged in one gas drainage borehole, so that the two bladders arranged on the grouting branch pipe are arranged in the gas drainage borehole, and a sealing cavity is formed between the two bladders after being filled with slurry. The sealing cavity is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole, and the high-pressure check valve is located in the sealing cavity and connects the grouting branch pipe and the sealing cavity; One end of all the grouting branch pipes is connected to one end of the main grouting pipe; The other end of the main grouting pipe is connected to the grouting mechanism; The gas drainage subsystem includes a gas drainage branch pipe, a concentration sensor, a pressure gauge, and a second solenoid valve; The concentration sensor, the pressure gauge, and the second solenoid valve are arranged on the gas drainage branch pipe; One end of one gas drainage branch pipe extends into one gas drainage borehole, and the other ends of all the gas drainage branch pipes are connected to one end of the main gas drainage pipe; The first solenoid valve, the pressure relief valve, the first low-pressure check valve, the high-pressure check valve, the second low-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism are all electrically connected to the control mechanism; The method for dynamically sealing gas drainage boreholes includes: Sequentially arranging a first solenoid valve, a pressure relief valve, a first low-pressure check valve, a high-pressure check valve, and a second low-pressure check valve on the grouting branch pipe; arranging one bladder at the positions of the first low-pressure check valve and the second low-pressure check valve on the grouting branch pipe respectively, and the first low-pressure check valve and the second low-pressure check valve connect the grouting branch pipe and the bladder at the corresponding position; Arranging one grouting branch pipe in one gas drainage borehole, so that the two bladders arranged on the grouting branch pipe are arranged in the gas drainage borehole, and a sealing cavity is formed between the two bladders after being filled with slurry. The sealing cavity is located between the elastic zone and the original stress zone in the stress concentration area of the gas drainage borehole, and the high-pressure check valve is located in the sealing cavity and connects the grouting branch pipe and the sealing cavity; Connecting one end of all the grouting branch pipes to one end of the main grouting pipe; connecting the other end of the main grouting pipe to the grouting mechanism; Arranging a concentration sensor, a pressure gauge, and a second solenoid valve on the gas drainage branch pipe; extending one end of one gas drainage branch pipe into one gas drainage borehole, and connecting the other ends of all the gas drainage branch pipes to one end of the main gas drainage pipe; Electrically connect the first solenoid valve, the pressure relief valve, the first low-pressure check valve, the high-pressure check valve, the second low-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the control mechanism; The control mechanism controls the grouting mechanism, the first solenoid valve, the first low-pressure check valve, and the second low-pressure check valve to open, and injects slurry into the bladder bags located at the positions of the first low-pressure check valve and the second low-pressure check valve on each grouting branch pipe through the grouting main pipe and the grouting branch pipes until a sealed cavity is formed between the two bladder bags after being filled with slurry. Then, the control mechanism controls the high-pressure check valve to open, so that the sealed cavity is filled with slurry. After that, the control mechanism controls the first solenoid valve to close and the second solenoid valve to open, and starts the gas drainage operation; Then, perform the dynamic sealing step multiple times. The dynamic sealing step includes: the concentration sensor monitors the gas drainage concentration value of the drainage branch pipe and transmits the gas drainage concentration value to the control mechanism; when the gas drainage concentration value is less than the preset concentration value, the control mechanism controls the second solenoid valve to close for a first preset time; if the control mechanism monitors that the pressure of the pressure gauge is less than the preset pressure value within the first preset time, the control mechanism controls the first solenoid valve to open and controls the grouting mechanism to grout intermittently until the control mechanism monitors that the grouting pressure reaches the upper limit pressure of the pressure relief valve, the control mechanism controls the first solenoid valve to close and the second solenoid valve to open, and continues the gas drainage operation.

2. The dynamic sealing method for drainage boreholes according to claim 1, wherein The slurry uses a low-viscosity sealing slurry.

3. The dynamic sealing method for drainage boreholes according to claim 1, wherein The control mechanism includes a monitoring sub-station, a programmable logic controller, and a ground monitoring platform; The first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism are all electrically connected to the monitoring sub-station; The monitoring sub-station is electrically connected to the programmable logic controller; The programmable logic controller is electrically connected to the ground monitoring platform.

4. The dynamic sealing method for drainage boreholes according to claim 3, characterized in that, The dynamic sealing system for the drainage borehole further includes an explosion-proof power supply; The monitoring sub-station is electrically connected to the explosion-proof power supply; The explosion-proof power supply is electrically connected to the programmable logic controller.

5. The dynamic sealing method for drainage boreholes according to claim 1, characterized in that The electrically connecting the first solenoid valve, the pressure relief valve, the first low-pressure check valve, the high-pressure check valve, the second low-pressure check valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the control mechanism includes: Electrically connect the first solenoid valve, the pressure relief valve, the concentration sensor, the pressure gauge, the second solenoid valve, and the grouting mechanism to the monitoring sub-station; Electrically connect the monitoring sub-station and the programmable logic controller; Electrically connect the programmable logic controller to the ground monitoring platform.

6. The dynamic sealing method for drainage boreholes according to claim 5, characterized in that, It further includes: Electrically connect the monitoring sub-station to the explosion-proof power supply; Electrically connect the explosion-proof power supply to the programmable logic controller.

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