CN112412421B - Method for strengthening pumping promotion by heat injection and hydraulic punching in layer-crossing drilling - Google Patents

Abstract

The method of layer-crossing drilling and heat injection combined with hydraulic punching to strengthen pumping promotion includes the following steps: constructing layer-crossing drilling in the floor rock roadway, the end points of each drilling hole are arranged in a grid array, and two adjacent drilling holes are respectively Named the heat injection hole and the extraction hole; set the extraction pipe for the borehole, and send the special hole sealer into the second extraction pipe to seal the hole; inject high temperature and high pressure nitrogen into the heat injection hole through the special sealer , the adjacent drainage hole has been in normal gas drainage to ensure that the gas escaping from the coal body after heating is pumped away in time; the drainage pipe in the heat injection hole is connected to the drainage system to carry out gas drainage work, further strengthening the gas Draw effect. To sum up, the present invention has a scientific principle, ingenious design, tight hole sealing, safety and reliability, combined with hydraulic punching, the effect of heat injection to enhance pumping is greatly enhanced, and can be widely used in Shimen unraveling coal, crossing faults, and mining working faces It has a broad application prospect for the works such as enhancing penetration and promoting drainage, strengthening gas drainage and so on.

Description

Intensified pumping promotion method through layer drilling combined with heat injection and hydraulic punching

technical field

The invention belongs to the technical field of coal mine safety production, and in particular relates to a method for intensifying and promoting pumping by drilling through layers and injecting heat in cooperation with hydraulic punching.

Background technique

Most coal seams in my country have the characteristics of "three lows and one high" (low permeability, low saturation, low reservoir pressure, and high degree of metamorphism). The low permeability of the coal seam makes it difficult to extract gas, resulting in the imbalance of "pumping-excavation-mining" in the mine, forming a major safety hazard, and laying hidden dangers for the occurrence of coal mine gas accidents. Therefore, scholars at home and abroad have researched and proposed technical measures for enhancing coal seam permeability and pumping, such as hydraulic slotting, protective layer mining, deep hole blasting, and CO ₂ phase change fracturing. However, due to various reasons, from the perspective of technology and economy, the anti-reflection effects of various technical measures currently commonly used still need to be further improved.

The coal gas desorption rate is closely related to the coal temperature. Relevant research results show that when the coal body temperature increases by 1 °C, the gas desorption capacity of the coal body increases by about 8%. Therefore, the method of heating the coal body can be used to strengthen the gas desorption of the coal body and improve the gas extraction effect. However, the existing coal heating technologies mostly use non-contact heating methods such as infrared and microwave. Although these methods can quickly heat the coal, they have the disadvantages of fast attenuation, high energy consumption, easy damage, and equipment that cannot be reused. It has been popularized and applied on a large scale; some scholars have also proposed to inject superheated water or water vapor into the coal seam to heat the coal body. Although the coal body can be effectively heated, after the water vapor and hot water enter the coal body, " "Water lock effect" inhibits the desorption of coal gas, but reduces the effect of gas drainage. In addition, if the high-temperature medium injected into the coal body is oxidizing, it may cause the coal body to ignite in the borehole, thus bringing about new safety problems. Therefore, it is urgent to find new heat injection methods, heat injection media and heat injection channels when adopting heat injection to enhance gas extraction technology measures, in order to strengthen the heat drive effect, improve the gas drainage effect, and effectively alleviate the "pumping-excavation-extraction" of the mine. "Balance issues and avoid drilling fires.

Nitrogen has good chemical stability and is a common inert gas. It does not burn itself or support combustion. It is very easy to prepare and the cost is very low. If nitrogen is heated and injected into the coal body through drilling, the temperature of the coal body can be effectively increased, the thermal driving effect on the coal body can be enhanced, and the effect of gas extraction can be enhanced; the higher partial pressure of nitrogen gas can reduce the formation of gas in the coal body. The replacement and displacement effects further enhance the gas drainage effect; and the inert characteristics of nitrogen can prevent drilling fires and prevent fires, gas explosions, coal dust explosions and other accidents. Therefore, it is economically feasible to use high-temperature nitrogen as a medium for coal seam drilling to enhance pumping by heat injection.

For the method of heating the injected coal medium in the downhole, methods such as heating cables and resistance wires are generally used. However, this method directly exposes heating cables and resistance wires to the air or coal body. In the atmosphere with high gas concentration and coal dust concentration in coal mines, there is a danger of inducing gas explosion and coal dust explosion, which is likely to cause serious accidents.

For low-permeability coal seams, especially outburst coal seams, the coal body is soft, the air permeability is poor, and drainage is difficult. The hydraulic punching technology of layer-penetrating drilling has been widely used due to its high safety in rock roadway construction, long extraction time, and good pressure relief effect. However, due to the huge amount of hydraulic punching engineering, serious injection holes, and frequent gas out-of-limit issues, the popularization and application of this technology has been limited to a certain extent; The effect is not ideal, and there are blank strips of drainage. It is necessary to continue to implement hydraulic punching measures to eliminate these blank strips of drainage, which further increases the amount of punching and drilling engineering, and increases the risk of problems such as injection holes and gas exceeding the limit. . Therefore, it is urgent to find a new technical measure to effectively solve the above-mentioned problems under the premise of ensuring the effect of coal seam gas drainage and not increasing the engineering amount.

Based on the above technologies, it can be seen that injecting high-temperature nitrogen gas into the coal body through interlayer drilling can heat the coal body and strengthen gas desorption. At the same time, high temperature can also pyrolyze the coal body, increasing the gas permeability of the coal body, which is beneficial to gas drainage. ; Moreover, because the injected high-temperature nitrogen can form a high-pressure area around the borehole, with a high partial pressure of the gas, it can displace and displace the coal gas to the area affected by the remote hydraulic punching borehole (low-pressure area) , Under the action of strong pressure difference, the effect of gas drainage can be strengthened, and then the amount of hydraulic punching can be greatly reduced, and problems such as spray holes and gas exceeding the limit can be reduced. The technical measure of cross-bed drilling and heat injection combined with hydraulic punching can effectively improve the effect of coal seam gas drainage, and is of great benefit to solving the problem of "extraction-excavation-extraction" imbalance in mines. It is a relatively advanced measure for coal seam gas drainage enhancement .

In the process of heat injection to enhance drainage and gas drainage, hole sealing work is a very important basic work; the quality of hole sealing directly affects the degree of coal cracking and the effect of gas drainage , which directly affects the economic benefits of the technology. The quality of the hole sealing is mainly controlled by the performance of the hole sealing device and the sealing process method; however, the existing hole sealing device and the hole sealing method are all designed for normal temperature conditions. Under the pumping action, it is easy to cause problems such as cracking of the sealing material, gas leakage in the borehole, and poor gas drainage effect. It is difficult to take into account the requirements of high-temperature medium injection and gas drainage at room temperature. If the drainage borehole under normal temperature conditions and the high-temperature medium injection borehole are constructed and sealed separately, it will increase the amount of drilling engineering, increase the drainage engineering cost and the cost of sealing the hole, no matter from the technical level or the economic level. All can't meet the requirement of coal mine field work. Therefore, there is an urgent need for a method of cross-layer drilling and heat injection combined with hydraulic punching to enhance drainage, which can simultaneously meet the requirements of high-temperature medium injection, normal-temperature gas drainage, reuse, and safety and reliability.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention provides a method of through-layer drilling and heat injection combined with hydraulic punching to enhance pumping, which solves the problem of low heating efficiency and unsafeness of the heat injection medium, and that conventional hole sealers cannot be applied to high temperatures conditions, poor sealing effect, poor drainage effect caused by pure hydraulic punching, etc., to achieve the purpose of strengthening the sealing effect under high temperature and normal temperature conditions, improving the degree of coal heat injection to enhance drainage, and improving the effect of coal seam gas drainage. Purpose.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solution: the method of drilling through layers and injecting heat to cooperate with hydraulic punching to strengthen and promote pumping includes the following steps,

(1) Manipulate the mechanical drilling rig in the floor rock roadway to drill through the coal body. The end points of each drill hole are arranged in a grid array, and the distance between the end points of two adjacent drilling holes is 6- 9m, any two adjacent boreholes are named heat injection hole and extraction hole respectively;

(2) Carry out hydraulic punching for the extraction hole. After the hydraulic punching construction is completed, the conventional "two plugging and one injection" process is used to seal the hole. The length of the sealing section of the hole is not less than 5m; , connect the first extraction pipe in the extraction hole to the underground extraction system of the coal mine for gas extraction;

(3) Send the special hole sealing device into the predetermined depth in the second extraction pipe in the heat injection hole, and seal the second extraction pipe;

(4) Inject high-temperature, high-pressure nitrogen into the heat injection hole through a special hole sealer;

(5) High-temperature, high-pressure nitrogen injects heat into the coal body at high pressure, and the pressure of the nitrogen gas is not less than 2MPa; under the action of high pressure, the nitrogen gas migrates to the distance of the heat injection hole, and the coal body is continuously heated during the migration process to promote the coal gas. Desorb and pyrolyze the coal body to increase the pores of the coal body, improve the gas permeability of the coal body, and strengthen the gas extraction; at the same time, the adjacent drainage holes are always in normal gas extraction to ensure that the gas released from the coal body after heating is pumped away in time. Prevent gas from hurting people;

(6) After injecting high-temperature and high-pressure nitrogen into the heat injection hole to heat the coal body for 4 hours, stop the heat injection of the coal body to strengthen the drainage and promote the work, and take out the special hole sealer from the second extraction pipe, and continue to reuse the dedicated hole sealer next time. Sealer;

(7) Connect the second extraction pipe in the heat injection hole to the extraction system for gas extraction to further enhance the effect of gas extraction.

The special sealing device includes nitrogen cylinder, heat injection pump, grouting pump, nitrogen heating device, first bladder, second bladder, gas injection tube and sealing tube. The nitrogen cylinder is set upside down on the bracket, and the gas injection tube and sealing tube Both are parallel to the second extraction tube, the first bladder and the second bladder are fixed on the gas injection tube with the center line, the second bladder is located inside the first bladder, and the outlet end of the sealing tube passes through the first The pouch extends to the inside of the second pouch, the sealing tube is provided with a through-hole communicating with the inside of the first pouch, the inside of the second extraction pipe forms a closed cavity between the first pouch and the second pouch, the second pouch A one-way valve is provided on the second pouch, the inlet of the one-way valve communicates with the closed cavity, the outlet of the one-way valve is located inside the second pouch, and the sealing tube is provided between the first pouch and the second pouch There is a blasting valve; the joints of the gas injection pipe, the sealing pipe, the one-way valve and the second bladder are all sealed, and the joints of the gas injection pipe, the sealing tube and the first bladder are all sealed;

The grouting pump is connected to the outer end of the sealing pipe through the grouting hose, the nitrogen cylinder is connected to the outer end of the gas injection pipe through the gas injection hose, and the heat injection pump and the nitrogen heating device are arranged on the gas injection hose.

The outer end of the gas injection pipe is provided with a gas injection valve, the outer end of the sealing pipe is provided with a sealing valve, and the bottle mouth of the nitrogen cylinder is provided with a switch valve.

The nitrogen heating device includes a heating box with a rectangular parallelepiped structure. The two opposite sides of the heating box are respectively provided with an air inlet and an air outlet connected to the gas injection hose. The heating box is equipped with a three-dimensional mesh cage structure. The left box wall and the right box wall are respectively provided with fixing rings for fixing the three-dimensional cage-like structure. The three-dimensional cage structure is fixedly connected by several heat-conducting tubes arranged vertically and horizontally. The heat-conducting tubes are equipped with electric heating wires and insulating heat-conducting Oil, the upper and lower terminals of the three-dimensional mesh cage structure are respectively provided in the heating box, and the upper and lower ends of all electric heating wires are connected with wires, and the upper and lower wires are respectively connected to the upper and lower terminals. The post is connected, and the upper terminal post and the lower terminal post are respectively connected with power supply lines passing through the heating box wall.

The wall of the heating box is a three-layer structure, the outermost layer and the innermost layer are welded by steel plates, and the middle interlayer is filled with glass fiber insulation material (with good thermal insulation performance, to ensure that the heat exchange efficiency).

The specific process of step (3) is to fix the first bladder and the second bladder on the gas injection tube, and the distance between the first bladder and the second bladder is not less than 4m; Hose and grouting pump, open the sealing valve, and the grouting pump pumps clean water through the grouting hose and the sealing tube to inject water into the first bladder and the second bladder. The water injection pressure is not less than 2MPa, so that the first bladder and the outer edge of the second bladder fully contact with the inner wall of the second extraction pipe to achieve the purpose of sealing the second extraction pipe; continue to increase the water injection pressure of the grouting pump, so that the sealing pipe is between the first bladder and the second The blasting valve between the bladders is opened, and clean water flows into the closed cavity formed between the first bladder and the second bladder inside the second extraction pipe; the opening pressure of the one-way valve on the second bladder is 2MPa , when the pressure in the closed cavity is greater than 2MPa, the one-way valve on the second bladder opens to the inside of the heat injection hole, and the air in the closed cavity is discharged, so that clean water continues to flow into the closed cavity until the closed cavity is filled with water, and then closed Grouting pump and sealing valve.

The specific process of step (4) is to open the gas injection valve on the gas injection pipe and the switch valve on the nitrogen cylinder; firstly, the electric heating wire is energized to raise the temperature, and the electric heating wire heats the insulating heat-conducting oil in the heat-conducting pipe, and the insulating heat-conducting oil heats up. The heat energy is radiated outward through the heat pipe. After 3-5 minutes, the heat injection pump is started, and the nitrogen in the nitrogen bottle enters the heating box first. When the nitrogen passes through the heating box, the heat emitted by the heat pipe heats the nitrogen, and the temperature of the nitrogen After being heated to 80°C, the gas injection hose enters the gas injection pipe, and then the gas injection pipe enters the heat injection hole; under the action of high temperature and high pressure nitrogen heating, the inside of the first bladder, the second bladder and the two The water body between the pockets expands when heated, and under the action of its own expansion force, the inner wall of the second extraction pipe is tightly sealed.

The specific process of taking out the special hole sealer in step (6) is to turn off the heat injection pump, on-off valve and gas injection valve in sequence, and open the hole sealing valve after 1 hour. The water in the gap will flow out automatically, and the special hole sealing device can be taken out.

Adopt above-mentioned technical scheme, the present invention has following technical effect:

1) Use high-temperature and high-pressure nitrogen to heat the coal body, which can strengthen gas desorption, replace and displace coal gas, and can greatly improve the gas drainage effect, achieve enhanced permeability and enhanced gas drainage, and effectively Solve the problem of "extraction-excavation-extraction" imbalance in mines;

2) Utilizing the thermal expansion of water, the water body expands naturally under the action of high-temperature nitrogen heating, resulting in huge thermal stress, which can be used to tightly seal the borehole, improve the sealing effect, and have no pollution to the coal body and groundwater; the use of water As a sealing material, it is cheap and economical;

3) High-temperature nitrogen is used as the heating medium, which can effectively heat the coal body and prevent the coal body from igniting in the borehole; while ensuring safety, it can effectively solve the "water lock effect" to ensure the gas drainage effect, and can solve infrared, Heating measures such as microwaves have disadvantages such as fast attenuation speed, high energy consumption, easy damage, and inability to be reused;

4) The electric heating wire (resistance wire) is used for heating in the heating box, and the electric heating wire is placed in a sealed structure (heat pipe) filled with insulating heat transfer oil, so as to ensure the heating effect of nitrogen and ensure that no electric sparks will be generated As a result, accidents such as gas explosions and coal dust explosions may occur;

5) Place the heat injection pump on the front side of the heating box to ensure that the heat injection pump is in a low temperature state, which effectively prolongs the life of the heat injection pump and can provide a stable high-pressure gas source;

6) Hydraulic punching is carried out on the drainage hole, and the hydraulic punching makes the coal body in the area around the drainage hole creep and relieve pressure, and the low pressure formed around the drainage hole is formed under the action of the negative pressure of the drainage system on the drainage hole. High-temperature nitrogen is injected into the heat injection hole, and the high-pressure zone formed around the heat injection hole forms a strong partial pressure difference of nitrogen gas between the heat injection hole and the extraction hole, which is conducive to strengthening the replacement and displacement effect of coal gas , improve the effect of gas drainage, and greatly reduce the amount of hydraulic punching engineering, realize the balance of "pumping-excavation-extraction" in the mine, and ensure mine safety;

7) The extraction pipe is made of PVE pipe, and the gas injection pipe is made of polytetrafluoroethylene. This pipe has the characteristics of low temperature resistance, corrosion resistance, antistatic, flame retardant, hydrophobicity, and non-stickiness. It can be applied to this hole sealer, and Guaranteed air tightness.

8) The special hole sealing device in the present invention adopts the design of double bladders combined with one-way valve and blasting valve, which can release the water in the bladder and between the two bladders smoothly; The inner wall of the pipe is smooth and less deformed; the above measures ensure that the hole sealing device of the present invention can be reused and reduce material costs;

9. After the heat injection process is completed, the heat injection hole can continue to be used as a gas drainage hole to achieve the purpose of "one hole for two purposes".

To sum up, the present invention has a scientific principle, ingenious design, tight hole sealing, safety and reliability, combined with hydraulic punching, the effect of heat injection to enhance pumping is greatly enhanced, and can be widely used in Shimen unraveling coal, crossing faults, and mining working faces It has a broad application prospect for the works such as enhancing penetration and promoting drainage, strengthening gas drainage and so on.

Description of drawings

Fig. 1 is the structural representation of special-purpose hole sealing device when working among the present invention;

Fig. 2 is the enlarged structure schematic diagram of special hole sealing device in the present invention;

Fig. 3 is a schematic diagram of the internal structure of the nitrogen heating device in Fig. 1;

Fig. 4 is a schematic plan view of the drilling arrangement in the present invention;

Fig. 5 is a schematic cross-sectional view of the drilling arrangement in the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention.

As shown in Fig. 1-Fig. 5, the method of the present invention for intensifying and pumping promotion through layer drilling and heat injection combined with hydraulic punching includes the following steps:

(1) Manipulate the mechanical drilling rig in the floor rock roadway 1 to drill through layers to the coal body 2 (the mechanical drilling rig first drills the rock layer 32, and then drills into the coal body 2), and the end points of each drilling hole are grid-like Arranged in an array, the distance between the end points of two adjacent boreholes is 6-9m, and any two adjacent boreholes are named heat injection hole 3 and extraction hole 4 respectively;

(2) Carry out hydraulic punching for the extraction hole 4. After the hydraulic punching construction is completed, the hole is sealed by the conventional "two plugging and one injection" process. The length of the hole sealing section of the hole is not less than 5m; the sealing material is solidified Finally, connect the first extraction pipe 5 in the extraction hole 4 to the underground extraction system (extraction pipeline) of the coal mine for gas extraction;

(3) Send the special hole sealing device 30 into the predetermined depth in the second extraction pipe 6 in the heat injection hole 3, and seal the second extraction pipe 6;

(4) Inject high-temperature and high-pressure nitrogen into the heat injection hole 3 through the special hole sealer 30;

(5) High-temperature, high-pressure nitrogen is injected into the coal body 2 under high pressure, and the pressure of the nitrogen gas is not less than 2MPa; under the action of high pressure, the nitrogen gas migrates to the distance of the heat injection hole 3, and continuously promotes the gas desorption of the coal body 2 during the migration process , and pyrolyze the coal body 2, increase the pores of the coal body 2, increase the gas permeability of the coal body 2, and strengthen the gas extraction; meanwhile, the adjacent drainage hole 4 has been in normal gas extraction to ensure that the gas escaped from the coal body 2 after heating is Take it away in time to prevent the gas from hurting people;

(6) After injecting high-temperature and high-pressure nitrogen gas into the heat injection hole 3 to heat the coal body 2 for 4 hours, stop the heat injection of the coal body 2 to enhance the pumping, take out the special hole sealer 30 from the second extraction pipe 6, and put it down. Continue to reuse the special sealer 30 again;

(7) The second drainage pipe 6 in the heat injection hole 3 is connected to the drainage system to carry out gas drainage work to further enhance the effect of gas drainage.

The special sealing device 30 includes a nitrogen cylinder 7, a heat injection pump 8, a grouting pump 9, a nitrogen heating device 10, a first bladder 11, a second bladder 12, a gas injection tube 13 and a sealing tube 14, and the nitrogen cylinder 7 is set upside down On the support 15, the gas injection pipe 13 and the sealing pipe 14 are all parallel to the second extraction pipe 6, and the first pouch 11 and the second pouch 12 are fixed on the gas injection pipe 13 with the center line, and the second pouch 12 is located inside the first pouch 11, the outlet end of the sealing tube 14 extends through the first pouch 11 to the inside of the second pouch 12, and the sealing tube 14 is provided with a through hole communicating with the inside of the first pouch 11 , the inside of the second extraction pipe 6 forms a closed cavity 16 between the first bag 11 and the second bag 12, the second bag 12 is provided with a one-way valve 17, and the inlet of the one-way valve 17 is connected to the closed cavity 16 Connected, the outlet of the one-way valve 17 is positioned at the inboard of the second bladder 12, and the blasting valve 18 is provided between the first bladder 11 and the second bladder 12 on the sealing tube 14; the gas injection pipe 13, the sealing tube 14 1. The joints of the one-way valve 17 and the second bladder 12 are all sealed, and the joints of the gas injection pipe 13, the sealing tube 14 and the first bladder 11 are all sealed;

The grouting pump 9 is connected to the outer end of the sealing pipe 14 through the grouting hose 19, the nitrogen cylinder 7 is connected to the outer end of the gas injection pipe 13 through the gas injection hose 20, and the heat injection pump 8 and the nitrogen heating device 10 are both provided. On the insufflation hose 20.

The outer end of the gas injection pipe 13 is provided with a gas injection valve 21 , the outer end of the sealing pipe 14 is provided with a sealing valve 22 , and the mouth of the nitrogen cylinder 7 is provided with an on-off valve 23 .

The nitrogen heating device 10 comprises a heating box 29 in a rectangular parallelepiped structure, two opposite sides of the heating box 29 are respectively provided with an air inlet and an air outlet connected to the gas injection hose 20, and a three-dimensional mesh cage is arranged in the heating box 29 structure, the left and right sides of the heating box 29 are respectively provided with fixing rings 50 for fixing the three-dimensional cage-like structure, and the three-dimensional cage structure is fixedly connected by several heat-conducting pipes 24 arranged vertically and horizontally, and the heat-conducting pipes 24 is provided with an electric heating wire 25 and an insulating heat-conducting oil 26, and an upper terminal 27 and a lower terminal 28 are respectively provided above and below the three-dimensional mesh cage structure in the heating box 29, and the upper and lower ends of all the electric heating wires 25 are connected Lead 31 is arranged, and the lead 31 of top and bottom is connected with upper terminal 27 and lower terminal 28 respectively, and upper terminal 27 and lower terminal 28 are respectively connected with the power supply line that passes heating box 29 case walls.

The box wall of the heating box 29 has a three-layer structure, the outermost layer and the innermost layer are respectively welded by steel plates, and the middle interlayer is filled with glass fiber insulation material 30 .

The specific process of step (3) is to fix the first pouch 11 and the second pouch 12 on the gas injection tube 13, the distance between the first pouch 11 and the second pouch 12 is not less than 4m; The orifice pipe 14 connects the grouting hose 19 and the grouting pump 9, opens the sealing valve 22, and the grouting pump 9 draws clean water through the grouting hose 19 and the sealing pipe 14 to the first bladder 11 and the second bladder 12 Carry out water injection, the water injection pressure is not less than 2MPa, make the outer edge of the first bag 11 and the second bag 12 fully contact with the inner wall of the second extraction pipe 6, to achieve the purpose of sealing the second extraction pipe 6; continue to increase the grouting The water injection pressure of the pump 9 makes the blast valve 18 between the first bladder 11 and the second bladder 12 on the sealing pipe 14 open, and clear water flows into the second extraction pipe 6 inside the first bladder 11 and the second bladder. In the closed cavity 16 formed between the two bladders 12; the opening pressure of the check valve 17 on the second bladder 12 is 2MPa, when the pressure in the sealed cavity 16 was greater than 2MPa, the check valve on the second bladder 12 17 is opened to the inside of the heat injection hole 3, and the air in the closed cavity 16 is discharged, so that clear water continues to flow in the closed cavity 16 until the closed cavity 16 is filled with water (according to the first capsule bag 11, the second capsule bag 12 and the closed cavity 16 combined with the water injection speed of the grouting pump 9, the time required to fill the water can be calculated, in order to ensure that the closed cavity 16 is filled with water, the calculated time can be extended by 1-2 minutes), and then close the injection Slurry pump 9 and sealing valve 22.

The specific process of step (4) is to open the gas injection valve 21 on the gas injection pipe 13 and the switch valve 23 on the nitrogen cylinder 7; The oil 26 is heated, and the insulating and heat-conducting oil 26 heats up and radiates heat energy through the heat-conducting pipe 24. After 3-5 minutes, the heat injection pump 8 is started, and the nitrogen in the nitrogen bottle 7 first enters the heating box 29, and the nitrogen gas passes through the heating box 29. During the process, the heat emitted by the heat pipe 24 heats the nitrogen gas, and the nitrogen gas is heated to 80°C and enters the gas injection pipe 13 from the gas injection hose 20, and then enters the heat injection hole 3 from the gas injection pipe 13; 1. Under the action of high-pressure nitrogen heating, the water inside the first bladder 11, the second bladder 12 and the water between the two bladders are heated and expanded, and under the action of their own expansion force, the inner wall of the second extraction pipe 6 is tightly sealed .

The specific process of taking out the special hole sealer 30 in step (6) is to turn off the heat injection pump 8, the switch valve 23 and the gas injection valve 21 in sequence, and open the hole sealing valve 22 after 1 hour, the first bladder 11, the second bladder 12 and the water between the two pouches flow out automatically, and the special hole sealer 30 can be taken out.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (6)

1. The method for strengthening pumping promotion by combining heat injection of cross-layer drilling and hydraulic punching is characterized by comprising the following steps of: comprises the following steps of (a) preparing a solution,

(1) Operating a mechanical drilling machine to construct cross-layer drill holes to the coal body in a bottom plate rock roadway, wherein all drilling hole end points are arranged in a grid-shaped array, the distance between every two adjacent drilling hole end points is 6-9m, and any two adjacent drilling holes are named as a heat injection hole and an extraction hole respectively;

(2) Performing hydraulic punching on the extraction hole, and sealing the hole by adopting a conventional two-plugging and one-injecting process after the hydraulic punching construction is finished, wherein the length of the sealed hole section of the hole is not less than 5m; after the hole sealing material is solidified, connecting a first extraction pipe in an extraction hole with an underground extraction system of a coal mine to extract gas;

(3) Conveying the special hole packer into a second extraction pipe in the heat injection hole to a preset depth, and sealing the second extraction pipe;

(4) Injecting high-temperature and high-pressure nitrogen into the hot hole through a special hole packer;

(5) High-temperature and high-pressure nitrogen is used for carrying out high-pressure heat injection on the coal body, and the pressure of the nitrogen is not less than 2MPa; the nitrogen is transported to the far position of the heat injection hole under the action of high pressure, the coal body is continuously heated in the transportation process, the gas desorption of the coal body is promoted, the coal body is pyrolyzed, the pores of the coal body are increased, the gas permeability of the coal body is improved, and the gas extraction is strengthened; meanwhile, the adjacent extraction holes are used for normally extracting gas all the time, so that the escaped gas of the heated coal body is ensured to be timely extracted, and the gas is prevented from hurting people;

(6) After injecting high-temperature and high-pressure nitrogen into the heat injection hole to heat the coal body for 4 hours, stopping the heat injection strengthening pumping promotion work of the coal body, taking out the special hole packer from the second pumping pipe, and continuously reusing the special hole packer next time;

(7) Connecting the second extraction pipe in the heat injection hole with an extraction system to perform gas extraction work so as to further enhance the gas extraction effect;

the special hole packer comprises a nitrogen bottle, a heat injection pump, a grouting pump, a nitrogen heating device, a first bag, a second bag, a gas injection pipe and a hole sealing pipe, wherein the nitrogen bottle is arranged on a support in an inverted mode, the gas injection pipe and the hole sealing pipe are parallel to a second extraction pipe, the first bag and the second bag are fixedly arranged on the gas injection pipe along the same central line, the second bag is positioned on the inner side of the first bag, the outlet end of the hole sealing pipe penetrates through the first bag to extend into the second bag, a through hole communicated with the interior of the first bag is formed in the hole sealing pipe, a closed cavity is formed between the first bag and the second bag in the second extraction pipe, a one-way valve is arranged on the second bag, the inlet of the one-way valve is communicated with the closed cavity, the outlet of the one-way valve is positioned on the inner side of the second bag, and an explosion valve is arranged between the first bag and the second bag on the hole sealing pipe; the joints of the gas injection pipe, the hole sealing pipe and the check valve and the second bag are all connected in a sealing way, and the joints of the gas injection pipe and the hole sealing pipe and the first bag are all connected in a sealing way;

the grouting pump is connected with the outer end of the hole sealing pipe through a grouting hose, the nitrogen bottle is connected with the outer end of the gas injection pipe through a gas injection hose, and the heat injection pump and the nitrogen heating device are both arranged on the gas injection hose;

the nitrogen heating device comprises a heating box with a cuboid structure, an air inlet and an air outlet which are connected with a gas injection hose are respectively arranged on two opposite side surfaces of the heating box, a three-dimensional net cage structure is arranged in the heating box, the left side box wall and the right side box wall of the heating box are respectively provided with a fixing ring for fixing the three-dimensional cage structure, the three-dimensional net cage structure is formed by fixedly connecting a plurality of heat pipes which are arranged in a criss-cross mode, electric heating wires and insulating heat conduction oil are arranged in the heat pipes, an upper wiring column and a lower wiring column are respectively arranged above and below the three-dimensional net cage structure in the heating box, the upper end and the lower end of each electric heating wire are respectively connected with the upper wiring column and the lower wiring column, and the upper wiring column and the lower wiring column are respectively connected with power supply wires which penetrate through the box walls of the heating box.

2. The method for enhancing pumping by heat injection and hydraulic punching in cooperation with cross-layer drilling according to claim 1, is characterized in that: the outer end part of the gas injection pipe is provided with a gas injection valve, the outer end part of the hole sealing pipe is provided with a hole sealing valve, and the bottle mouth of the nitrogen cylinder is provided with a switch valve.

3. The method for enhancing pumping by heat injection and hydraulic punching in cooperation with cross-layer drilling according to claim 2, is characterized in that: the wall of the heating box is of a three-layer structure, the outermost layer and the innermost layer are respectively formed by welding steel plates, and the middle interlayer is filled with glass fiber heat-insulating materials.

4. The method for enhancing pumping by heat injection of cross-layer drilling and hydraulic punching in cooperation with the cross-layer drilling as claimed in claim 3, is characterized in that: the specific process of the step (3) is that the first bag and the second bag are fixed on an air injection pipe, and the distance between the first bag and the second bag is not less than 4m; connecting the hole sealing pipe with a grouting hose and a grouting pump, opening a hole sealing valve, pumping clear water by the grouting pump to inject water into the first bag and the second bag through the grouting hose and the hole sealing pipe, wherein the water injection pressure is not less than 2MPa, so that the outer edges of the first bag and the second bag are fully contacted with the inner wall of the second extraction pipe, and the purpose of sealing the second extraction pipe is achieved; continuously increasing the water injection pressure of the grouting pump, opening a blast valve between a first bag and a second bag on the hole sealing pipe, and allowing clean water to flow into a closed cavity formed between the first bag and the second bag in the second extraction pipe; the opening pressure of the one-way valve on the second bag is 2MPa, when the pressure in the closed cavity is greater than 2MPa, the one-way valve on the second bag is opened towards the inner side of the heat injection hole, air in the closed cavity is discharged, clean water continuously flows into the closed cavity until the closed cavity is filled with water, and then the grouting pump and the hole sealing valve are closed.

5. The method for enhancing pumping by heat injection and hydraulic punching in cooperation with cross-layer drilling according to claim 4, wherein the method comprises the following steps: the specific process of the step (4) is that an air injection valve on an air injection pipe and a switch valve on a nitrogen cylinder are opened; firstly, electrifying an electric heating wire to heat, heating the insulated heat conducting oil in the heat conducting pipe by the electric heating wire, radiating heat energy outwards through the heat conducting pipe after the insulated heat conducting oil is heated, starting the heat injection pump after 3-5 minutes, firstly, enabling nitrogen in the nitrogen bottle to enter a heating box, heating the nitrogen by the heat emitted by the heat conducting pipe in the process that the nitrogen passes through the heating box, heating the temperature of the nitrogen to 80 ℃, then, enabling the nitrogen to enter a gas injection pipe through a gas injection hose, and then, enabling the nitrogen to enter a heat injection hole through a gas injection pipe; under the heating action of high-temperature and high-pressure nitrogen, the water bodies in the first bag, the second bag and between the two bags are heated and expanded, and the inner wall of the second extraction pipe is tightly sealed under the action of self expansion force.

6. The method for enhancing pumping by heat injection of cross-layer drilling and hydraulic punching in cooperation with the cross-layer drilling as claimed in claim 5, wherein the method comprises the following steps: and (5) closing the heat injection pump, the switch valve and the air injection valve in sequence, opening the hole sealing valve after 1h, automatically flowing out the first bag, the second bag and the water body between the two bags, and taking out the special hole sealing device.

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