Gas extraction efficiency-increasing contrast experiment method combining spraying-cutting-pressing-extraction technology

Abstract

The invention discloses a gas extraction synergistic contrast experiment method combining a spraying-cutting-pressing-extraction technology, which comprises the following steps: S1, dividing a coal wall into two groups A and B of areas meeting operation requirements, uniformly spraying a plugging material I by adopting spraying equipment, and repeatedly spraying a plugging material II; s2, drilling holes by adopting a drilling machine and a matched drill bit, feeding slotting equipment into the holes by adopting a traction machine in the two groups of experimental areas, and performing hydraulic cutting along the holes by adopting an intermittent rotary drill retreating mode; s3, fracturing equipment is fed into the drill holes of the group A and the group B through a traction machine for hydraulic fracturing, hydraulic fracturing continues to be conducted in the drill holes of the experiment areas of the two groups along the slotted cutting positions, and therefore the cracks are expanded and extended; s4, the fracturing equipment is taken out, gas extraction equipment is arranged in the areas A and B for gas extraction operation, and then gas extraction concentration data are compared, and the method has the advantages that the internal permeability of the coal seam is increased, the gas extraction efficiency is high, the practical value is high, and the good application prospect is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas drainage, and particularly relates to a comparative experiment method for enhancing the efficiency of gas drainage by combining spraying - cutting - pressing - pumping technology. Background Art

[0002] Coal mine gas is an important factor seriously threatening the safe production of coal mines. The explosions and outbursts caused by gas have caused huge damage to personal and property safety. Gas drainage can not only reduce the occurrence of gas disasters, but also generate economic benefits to promote economic development.

[0003] In engineering practice, due to the small coal seam permeability and serious air leakage, the in - seam gas drainage efficiency in the mine is low, resulting in the gas drainage concentration dropping to an unusable value in a short time and being forced to be discharged into the atmosphere. This low - efficiency drainage situation not only pollutes the environment, but also cannot effectively reduce the gas content in the coal seam, causing potential safety hazards to coal mine production. At present, the market lacks both a method for synergistically enhancing the gas drainage efficiency in multiple ways and an experimental method for the specific selection of different gas drainage methods in coal roadways, resulting in the inability to maximize the benefits of gas drainage. Summary of the Invention

[0004] The present invention aims to provide a comparative experiment method for enhancing the efficiency of gas drainage by combining spraying - cutting - pressing - pumping technology, which has high gas drainage efficiency and reduces safety hazards, and solves the problems that the current coal seam permeability is small and the air leakage is serious, resulting in the gas drainage concentration dropping to an unusable value in a short time, and that the market currently lacks both a method for synergistically enhancing the gas drainage efficiency in multiple ways and an experimental method for the specific selection of different gas drainage methods in coal roadways, leading to the inability to maximize the benefits of gas drainage.

[0005] For this purpose, the technical solution adopted by the present invention is as follows: A comparative experiment method for enhancing the efficiency of gas drainage by combining spraying - cutting - pressing - pumping technology, comprising the following steps:

[0006] Step S1: Divide two groups of areas A and B that meet the operation requirements on the coal wall, and each group is provided with a control area and an experimental area. First, evenly spray a first sealing material on the coal wall of the experimental areas of groups A and B using a spraying device, and then evenly spray a second sealing material. During this period, use an air - drying device to blow the spraying area to accelerate the condensation of the sealing material.

[0007] Step S2: First, determine the number, angle, and depth of the drill holes according to the actual situation of the engineering site in areas A and B, and then use a drilling rig and a supporting drill bit to drill holes. In the experimental areas of both groups, use a tractor to send a slot - cutting device into the hole and perform hydraulic cutting along the hole in an intermittent rotary and retracting drilling mode.

[0008] Step S3: Use a tractor to send the fracturing equipment into the drill holes of both Group A and Group B for hydraulic fracturing, and continue hydraulic fracturing along the slit cutting area in the drill holes of the experimental areas of both groups to extend the fractures;

[0009] Step S4: Remove the fracturing equipment, install gas concentration monitors in the drill holes of both Group A and Group B areas, then place gas drainage equipment for gas drainage operations, and finally compare the gas drainage concentration data of the control areas and experimental areas of both Group A and Group B.

[0010] As an optimization of the above solution, in Step S1, the first plugging material includes polyurethane prepolymer, isocyanate, thickener, and propylene glycol solvent. Among them, according to the mass ratio, the polyurethane prepolymer: isocyanate is 3:1, and the weight of the thickener is 1 / 40 of the total weight of the mixture of polyurethane prepolymer and isocyanate; the second plugging material is composed of 30% fine sand, 30% quartz powder, and 40% sodium silicate by mass percentage.

[0011] The isocyanate in the first plugging material reacts with the hydroxyl group (-OH) in the polyurethane prepolymer to form a polyurethane structure. The reaction between the isocyanate and the polyurethane prepolymer can enhance the strength, hardness, and durability of the material. The role of the thickener is to increase the viscosity of the formulation, making the mixture have better rheology for easy coating and molding operations. Propylene glycol, as a solvent, mainly plays a role in dilution and dissolution, helping other components to be evenly dispersed. Moreover, the polyurethane prepolymer can also react with the sodium silicate in the second plugging material to form a cross-linked structure. This cross-linking significantly improves the strength and durability of the material. The three-dimensional structure formed by the cross-linked products tightly wraps the fine sand and quartz powder in the second plugging material sprayed later, forming a dense structure overall, which can effectively plug the coal wall and reduce the air leakage rate. At the same time, the presence of fine sand and quartz powder not only improves the plugging effect but also reduces costs.

[0012] The method of spraying the first plugging material and the second plugging material separately before and after is because the isocyanate and sodium silicate will coagulate relatively quickly after mixing. If they are sprayed together, it is easy to block the spraying equipment. Therefore, first spray the isocyanate on the roadway wall. Under the action of the thickener, it will not slide on the surface of the coal wall and can initially maintain a uniform wall-hanging state. At this time, spray the sodium silicate, which can quickly react and solidify into a plugging layer, and can also ensure the thickness uniformity of the plugging layer and the plugging effect.

[0013] The plugging material is sprayed out through the spraying equipment and adhered to the roadway coal wall, ensuring that the adhesive force is not less than 2.0 MPa. It can adhere to various materials such as coal blocks and concrete. After complete curing, it has extremely strong sealing performance, and the air permeability rate is as low as 0.001 L / (s·m 2 ), making the internal coal seam of the experimental area in a high-pressure state, thereby effectively increasing the gas drainage concentration and efficiency.

[0014] Further preferably, the spraying device includes a plugging material tank, a nozzle, and a connecting pipe. The connecting pipe connects the plugging material tank and the nozzle. The plugging material tank is used to uniformly mix plugging material one or plugging material two with water, which is simple and convenient to operate. Adding an appropriate amount of water can facilitate the flow of the plugging material.

[0015] Further preferably, in step S1, the dosage of the propylene glycol solvent in plugging material one is positively correlated with the spraying thickness, and the design is reasonable.

[0016] Further preferably, in step S2, the slitting device is installed at the front end of the drill bit of the drill rig. Only with a reasonable installation position can hydraulic slitting be carried out by the way of retracting the drill.

[0017] Further preferably, in step S3, the fracturing device is installed on the drill rig. The fracturing device includes a whipstock, a plug, a water pressure conversion valve, a throttle, and a check valve. The water in the water tank is injected under high pressure. Under the action of the high pressure, the plug expands, forming a closed area between the plugs. As the injection pressure of the high-pressure water flow continuously rises until it reaches the coal body fracture limit, a complex fracture network is generated in the coal body near the fracturing area, increasing the permeability of the coal body.

[0018] Further preferably, the drill rig, the water tank, and the water injection driving device are all connected in series through a connecting pipe, so that the water in the water tank is injected into the drill hole through the water injection driving device, providing power and a source for hydraulic cutting or hydraulic fracturing, and the structural design is reasonable.

[0019] Further preferably, in step S4, the gas drainage device includes a negative pressure fan, a motor, an air duct, a drainage pipe, and a plug. The motor provides rotational power for the negative pressure fan. The drainage pipe extends into the hole and the hole opening is blocked by the plug to form a closed drainage space. The air duct connects the drainage pipe and the negative pressure fan, so that the gas flows out through the air duct, and the structure is reasonable.

[0020] Advantages of the present invention:

[0021] (1) Compared with the current situation where the coal seam has a small permeability and serious air leakage, and the in-seam gas drainage efficiency in the mine is low, this solution adopts the combination of spraying plugging materials, hydraulic cutting, hydraulic fracturing, and gas drainage. By sequentially spraying plugging material one and plugging material two on the coal wall to form a closed coating, it can effectively avoid the air in the roadway from entering the coal seam during the gas drainage process due to coal wall air leakage, affecting the gas drainage efficiency and gas drainage concentration. Then, by internally slitting and creating fractures to assist hydraulic fracturing to expand a more complex fracture network, the internal permeability of the coal seam is increased, the gas drainage efficiency is improved, the occurrence of gas explosion accidents is avoided, it has high practical value, and has a good application prospect.

[0022] (2) Considering that the coal seam gas content in each area of the coal roadway is not consistent, in order to ensure the accuracy of experimental data, two areas, A and B, are designed, and a control area and an experimental area are set in each area. By comparing the gas drainage concentration data of the control areas and experimental areas in groups A and B, the improvement of the combined spraying-cutting-pressure-drainage technology on the gas drainage concentration can be accurately judged. The concept is novel and the design is reasonable.

[0023] (3) Since the coal seam gas concentration content and the coal seam fracture degree are not consistent in each coal roadway, for the different characteristics of the coal roadway, by first setting two groups of control areas and experimental areas, A and B, and comparing the gas drainage concentration data, the efficiency increase degree of the gas drainage using the spraying-cutting-pressure-drainage technology can be obtained compared with the simple gas drainage process. Moreover, since the plugging material also requires equipment and construction costs, it is necessary to simply calculate the cost of the additional process, so as to obtain which gas drainage method can maximize the gas drainage benefit in this coal roadway, and then continue to use this method for drainage in this coal roadway.

[0024] In summary, the present invention has the advantages of increased internal permeability of the coal seam, high gas drainage efficiency, high practical value, and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of steps S1 - S2 of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of the fracturing equipment.

[0027] Figure 3 It is a schematic diagram of the structure of the gas drainage equipment.

[0028] Figure 4 It is a curve graph comparing the methane concentrations of the control area and the experimental area in group A.

[0029] Figure 5 It is a curve graph comparing the methane concentrations of the control area and the experimental area in group B. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will be further described below through embodiments in conjunction with the drawings:

[0031] Combined with Figure 1 — Figure 5 As shown, a method for comparing the efficiency increase of gas drainage by the combined spraying-cutting-pressure-drainage technology is characterized by including the following steps:

[0032] Step S1: Divide two groups of areas A and B that meet the operation requirements on the coal wall. Each group is provided with a control area and an experimental area. Use the spraying device 1 to first evenly spray the first sealing material on the coal wall of the experimental areas in groups A and B, and then evenly spray the second sealing material. During this period, use the air drying device 8 to blow the sprayed area to accelerate the condensation of the sealing material.

[0033] In step S1, the first sealing material includes polyurethane prepolymer, isocyanate, thickener, and propylene glycol solvent. Among them, according to the mass ratio, the polyurethane prepolymer: isocyanate is 3:1, and the weight of the thickener is 1 / 40 of the weight of the mixture of polyurethane prepolymer and isocyanate.

[0034] The second sealing material is composed of 30% fine sand, 30% quartz powder, and 40% sodium silicate by mass percentage.

[0035] The spraying device 1 is composed of a sealing material tank 11, a nozzle 12, and a connecting pipe 13.

[0036] The connecting pipe 13 connects the sealing material tank 11 and the nozzle 12.

[0037] The sealing material tank 11 is used to uniformly mix the first sealing material or the second sealing material with water.

[0038] In step S1, the dosage of the propylene glycol solvent in the first sealing material is positively correlated with the spraying thickness.

[0039] Step S2: First, determine the number, angle, and depth of the drill holes according to the actual situation of the engineering site in areas A and B. Then use the drill 4 and the supporting drill bit 41 to drill holes. In the experimental areas of the two groups, use the tractor to send the slotting device 2 into the holes and perform hydraulic cutting along the holes in a discontinuous rotary back-drilling manner.

[0040] In step S2, the slotting device 2 is installed at the front end of the drill bit 41 of the drill 4.

[0041] Step S3: Use the tractor to send the fracturing device 3 into the drill holes in both groups A and B for hydraulic fracturing, and continue to perform hydraulic fracturing along the slotting cut in the drill holes in the experimental areas of the two groups to extend the cracks.

[0042] In step S3, the fracturing device 3 is installed on the drill 4. The fracturing device 3 includes an inclination guide, a plug 32, a water pressure conversion valve, a throttle 33, and a check valve 34.

[0043] The drill 4 is connected in series with the water tank 5 and the water injection driving device 6 through the connecting pipe 7, so that the water in the water tank 5 is injected into the drill holes through the water injection driving device 6 to provide power and a source for hydraulic cutting or hydraulic fracturing.

[0044] Step S4: Remove the fracturing equipment 3, install gas concentration monitors in the boreholes of areas A and B, then place the gas drainage equipment 9 for gas drainage operations, and finally compare the gas drainage concentration data of the two control areas A and B and the experimental area.

[0045] In step S4, the gas drainage equipment 9 consists of a negative pressure fan 91, a motor 92, an air duct 93, a drainage pipe 94, and a plug 95.

[0046] The motor 92 provides rotational power for the negative pressure fan 91.

[0047] The drainage pipe 94 extends into the hole and the hole opening is sealed by the plug 95 to form a closed drainage space.

[0048] The air duct 93 connects the drainage pipe 94 and the negative pressure fan 91, so that the gas flows out through the air duct 93.

[0049] According to Figure 4 、 Figure 5 The data shows that the gas drainage concentration of the experimental areas in both groups A and B using the gas drainage efficiency comparison experiment method of the combined spraying-cutting-pressure-drainage technology is higher than the ordinary gas drainage concentration in the control areas within the overall range. Thus, it is concluded that the two measures of externally spraying sealing materials and internally cutting slits to create fractures and expand the fracture space are indeed effective in improving the gas drainage concentration and effect.

[0050] Finally, based on the data comparison, a simple calculation is made of the gas drainage efficiency improvement degree and the cost of additional processes, so as to obtain which method, the ordinary gas drainage method or the combined spraying-cutting-pressure-drainage method, can maximize the gas drainage benefits in this coal roadway, and then the method can be continued to be used for drainage in this coal roadway.

Claims

1. A gas extraction efficiency comparison experimental method combining spraying-cutting-pressure-extraction technology, characterized in that: The following steps are involved: Step S1, dividing the coal wall into two groups A and B that meet the operation requirements, and each group is provided with a control area and an experimental area, using a spraying device (1) to first evenly spray the plugging material 1 on the coal wall of the experimental areas of the groups A and B, and then evenly spray the plugging material 2, during which time an air drying device (8) is used to blow the spraying area to accelerate the condensation of the plugging material; Step S2, first determine the number, angle and depth of the holes to be drilled in areas A and B according to the actual conditions of the project site, then use a drilling machine (4) and a matching drill bit (41) to drill holes, use a tractor to send the cutting device (2) into the hole in the experimental areas of the two groups, and use an intermittent rotary drill withdrawal method to perform hydraulic cutting along the hole; Step S3, using a tractor to send the fracturing equipment (3) into the boreholes of both groups A and B to perform hydraulic fracturing, and continue to perform hydraulic fracturing along the cut seams in the experimental area boreholes of the two groups, thereby expanding and extending the cracks; Step S4, take out the fracturing equipment (3), install gas concentration monitors in the boreholes of the two groups A and B areas, then place the gas extraction equipment (9) to perform gas extraction operations, and finally compare the gas extraction concentration data of the two groups A and B control areas and the experimental area.

2. The gas extraction efficiency comparison experimental method of the combined spray-cut-pressure-extraction technology according to claim 1 is characterized by: In step S1, the first plugging material includes a polyurethane prepolymer, an isocyanate, a thickener, and a propylene glycol solvent, wherein the mass ratio of the polyurethane prepolymer to the isocyanate is 3:1, and the weight of the thickener is 1 / 40 of the weight of the mixture of the polyurethane prepolymer and the isocyanate; the second plugging material is composed of 30% fine sand, 30% quartz powder, and 40% sodium silicate in mass percentage.

3. A gas extraction efficiency comparison experimental method of combined spraying-cutting-pressure-extraction technology according to claim 2, characterized in that: The spraying device (1) comprises a plugging material tank (11), a nozzle (12) and a connecting pipe (13); the connecting pipe (13) connects the plugging material tank (11) and the nozzle (12); two plugging material tanks (11) are provided, and a stirring structure is arranged inside the plugging material tank (11), which is used to mix plugging material 1 and plugging material 2 with water evenly.

4. The gas extraction efficiency comparison experimental method of the combined spray-cut-pressure-extraction technology according to claim 2 is characterized by: In the step S1, the amount of propylene glycol solvent in the plugging material 1 is positively correlated with the spraying thickness.

5. The gas extraction efficiency comparison experimental method of the combined spray-cut-pressure-extraction technology according to claim 1 is characterized by: In the step S2, the slotting device (2) is installed at the front end of the drill bit (41) of the drilling machine (4).

6. The gas extraction efficiency comparison experimental method of the combined spray-cut-pressure-extraction technology according to claim 1 is characterized by: In the step S3, the fracturing equipment (3) is installed on the drilling rig (4), and the fracturing equipment (3) comprises a guide, a plug (32), a water pressure conversion valve, a throttle (33), and a one-way valve (34).

7. A gas extraction efficiency comparison experimental method of combined spraying-cutting-pressure-extraction technology according to claim 5 or 6, characterized in that: The drilling machine (4), the water tank (5) and the water injection drive device (6) are all connected in series via a connecting pipe (7), so that the water in the water tank (5) is injected into the drill hole via the water injection drive device (6).

8. The gas extraction efficiency comparison experimental method of the combined spray-cut-pressure-extraction technology according to claim 1 is characterized by: In step S4, the gas extraction equipment (9) includes a negative pressure fan (91), a motor (92), an air duct (93), an extraction pipe (94), and a plug (95). The motor (92) provides rotational power for the negative pressure fan (91). The extraction pipe (94) extends into the hole and blocks the hole opening through the plug (95) to form a closed extraction space. The air duct (93) connects the extraction pipe (94) and the negative pressure fan (91), so that the gas flows out through the air duct (93).

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