Through porous foaming material for soft coal seam, injection system and injection method

Abstract

The invention discloses a through porous foaming material for a soft coal seam, an injection system and an injection method.The porous foaming material comprises a component A and a component B, and the mass ratio of the component A to the component B is 1: 1. The continuous injection system comprises a slurry pumping device, a continuous hose is connected to the slurry pumping device, and a slurry outlet head 3 is arranged at the front end of the continuous hose; the porous foam material provided by the invention has the characteristics of high compressive strength, strong permeability and the like, the permeability of a formed through pore network is far higher than that of a coal reservoir, the porous foam material has better compressive strength, forms powerful support for drilling holes, and ensures that a gas extraction channel is unblocked; after being injected into the hole by means of the continuous hose, the porous foaming material can effectively and continuously react in the hole and fill the whole drill hole, a gas extraction channel is greatly improved, the problems that the foaming material is discontinuous and the gas extraction channel is not smooth are solved, the utilization rate of the drill hole is higher, and finally the gas extraction effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of underground coal mine gas drainage, relates to a porous foam material, and specifically designs a through-hole porous foam material for soft coal seams, an injection system and an injection method. Background Art

[0002] Drilling is an important technical method for underground gas control in coal mines. During drilling in soft coal seams, the drilling rate is low and the depth is shallow due to factors such as the poor stability of the soft coal seams themselves, high gas content, and high pressure, which seriously restricts the efficiency of gas extraction. For this reason, in the existing technology, coal mines often use the technology of lowering the screen pipe without lifting the drill to extract gas. The technology of lowering the screen pipe without lifting the drill means that after the drilling is completed, the drill tool is not temporarily lifted. After removing the water feeder, the gas extraction screen pipe is sent to the bottom of the borehole through the through hole in the drill pipe and the front open and close drill bit. The drill is then lifted, and the gas extraction screen pipe is left at the bottom of the hole. This technology solves the problem that after drilling in soft coal seams is completed, the screen pipe is difficult to lower to the bottom of the hole due to the collapse of the borehole. However, the following problems exist in the promotion and application of this process technology: ① The screen pipe supporting the process is composed of a single series of screen pipes, and the connection and lowering process of the screen pipes are all completed manually, which is labor-intensive and has low construction efficiency; ② During gas extraction, the gas extraction screen pipe supporting the process is prone to sieve blockage, affecting the gas extraction effect; ③ This process is only suitable for conventional shallow boreholes, and is not suitable for directional long boreholes with complex designs and deeper boreholes, which has certain limitations; ④ The diameter of the screen pipe is only about 30% of the borehole diameter and cannot support the stability of the hole wall. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a through-hole porous foam material, injection system and injection method for soft coal seams, so as to solve the technical problems of high labor intensity, poor extraction effect and poor process applicability in the existing technology of gas extraction in soft coal seams, so as to increase the gas extraction effect of soft coal seams and ensure safe production in coal mines.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A through-hole foam material for soft coal seams, comprising a component A and a component B, wherein the mass ratio of the component A to the component B is 1:(1-3);

[0006] The component A comprises the following raw material components by mass percentage: 85-90% alcohol, 0.5-1.0% foaming agent, 3-5% pore connecting agent, 0.5-1% surfactant and 5-10% flame retardant, and the mass percentage of each component totals 100%;

[0007] The B component is selected from one or both of polymethylene polyphenyl isocyanate and toluene diisocyanate.

[0008] The present invention also has the following technical features:

[0009] Specifically, the alcohol is selected from any one or any two of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran.

[0010] Furthermore, the foaming agent is selected from any one of hydrofluoroolefins, cyclopentane, liquid carbon dioxide and water.

[0011] Furthermore, the pore connecting agent includes solid paraffin with a melting point of 25 to 70°C.

[0012] Furthermore, the surfactant is selected from one or more of 1,4-butanediol, glycerol, ethylene glycol and silicone oil.

[0013] Furthermore, the flame retardant is selected from one or more of ammonium polyphosphate, pentaerythritol and phosphorus-containing polyols.

[0014] The present invention also protects a continuous injection system of porous foaming materials for soft coal seams, comprising a slurry pumping device, a continuous hose connected to the slurry pumping device, and a slurry outlet head provided at the front end of the continuous hose;

[0015] The slurry discharge head includes a guide head and an outer tube body connected from front to back; an inner cavity is provided in the outer tube body, a stirring shaft is provided in the inner cavity along the axial direction of the outer tube body, and a plurality of stirring blades are provided on the stirring shaft at equal intervals;

[0016] A pulp outlet communicating with the inner cavity is provided on the front end surface of the guide head.

[0017] Furthermore, the continuous hose comprises a coating layer, a skeleton layer, a toughness material layer and an inner lining layer sequentially arranged from the outside to the inside, and at least one slurry conveying channel is arranged in the inner lining layer along the axial direction;

[0018] The coating layer is formed by interweaving multiple layers of fibers, and the fibers are selected from one or more of glass fibers, basalt fibers and quartz fibers; the coating layer is coated with a wear-resistant coating, the wear-resistant coating has a thickness of 1`2 mm, and the wear-resistant coating material is selected from one or more of diamond powder, silicon carbide powder and ceramic powder; the tough material layer is a steel-zinc alloy layer.

[0019] The present invention also provides a method for continuously injecting a porous foaming material into a soft coal seam, comprising the following steps:

[0020] Step 1: Drill the hole to the designed depth;

[0021] Step 2: Lower the continuous hose with the slurry outlet connected to the front end into the borehole. When the difference between the length of the continuous hose lowered and the total length of the drill bit in the hole reaches 0.5m, stop lowering the continuous hose.

[0022] Step 3: Take out the drilling tool from the borehole;

[0023] Step 4: Connect the slurry pumping device, set the pumping pressure according to the hole depth, and inject the porous foam material into the bottom of the hole; during the injection process, pull back the continuous hose according to the set continuous hose pull-back speed;

[0024] Step 5: Complete the drilling and sealing operations and implement gas extraction.

[0025] Preferably, in step 4, when 0 m < hole depth ≤ 100 m, 1 MPa < pumping pressure ≤ 3 MPa, the continuous hose pull-back speed is 3 m / min;

[0026] When 100m<hole depth≤200m, 3Mpa<pump pressure≤5Mpa, the continuous hose pull-back speed is 5m / min;

[0027] When 200m<hole depth≤300m, 5Mpa<pump pressure≤8Mpa, the pull-back speed of the continuous hose is 6m / min;

[0028] When 300m<hole depth≤400m, 8Mpa<pump pressure≤11Mpa, the continuous hose pull-back speed is 9m / min;

[0029] When 400m<hole depth≤500m, 11Mpa<pump pressure≤15Mpa, the continuous hose pull-back speed is 10m / min.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] (1) The porous foam material provided by the present invention has the characteristics of high compressive strength and strong permeability. The through pore network formed is much higher than the permeability of the coal reservoir, has good compressive strength, forms a strong support for the borehole, and ensures the smooth flow of the gas extraction channel; after the porous foam material is injected into the hole with the help of a continuous hose, it can effectively and continuously react in the hole, filling the entire borehole, greatly improving the gas extraction channel, solving the problem of discontinuous foam material and blocked gas extraction channel, making the borehole utilization rate higher, and ultimately improving the gas extraction effect.

[0032] (2) The method of the present invention eliminates the construction steps of manually connecting the gas extraction screen pipes one by one and lowering them into the hole in sequence, thereby reducing labor intensity and improving construction efficiency; the continuous hose used is suitable for ultra-long directional drilling, which solves the problem of lowering the screen pipe in the entire hole section caused by the deep drilling hole and complex trajectory bending in the existing technology, and broadens the application scope of gas extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0034] Figure 2 is a cross-sectional view of the continuous hose of the present invention;

[0035] Figure 3 It is a cross-sectional view of the pulping head of the present invention;

[0036] Figure 4 Schematic diagram of the stirring blade structure.

[0037] The meaning of each number in the figure is:

[0038] 1-slurry pumping device, 2-continuous hose, 3-slurry outlet, 4-component A barrel, 5-component B barrel, 6-continuous hose storage mechanism; 21-coating layer, 22-skeleton layer, 23-tough material layer, 24-lining layer, 25-slurry conveying channel; 31-guide head, 32-outer tube body, 33-stirring shaft, 34-stirring blade, 35-slurry mixing groove; 311-slurry outlet. DETAILED DESCRIPTION

[0039] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0040] It should be noted that, unless otherwise specified, all components and raw materials in the present invention are those known in the prior art.

[0041] The technical concept of this application is: using an injection system to deliver a porous foam material obtained by mixing two-component materials with the characteristics of high compressive strength and strong permeability to the bottom of the borehole, and adopting an operation method of pulling back a continuous hose and grouting and foaming. After the foaming of the entire hole section is completed, the borehole is sealed and the joints are closed for gas extraction, replacing the traditional operation method of lowering the screen pipe during gas extraction, effectively avoiding the blockage of the screen hole affecting the gas extraction effect.

[0042] The terms "upper", "lower", "front", "back", "top", "bottom", etc. used in the present invention to indicate directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. "Inside" and "outside" refer to the inside and outside of the contour of the corresponding component, and the above terms cannot be understood as limiting the present invention.

[0043] In the present invention, unless otherwise specified, terms such as "mounted," "connected," "connect," and "fixed" should be interpreted broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] Example 1

[0045] Following the above technical solution, this embodiment provides a porous foam material for soft coal seams, comprising components A and B, with a mass ratio of 1:1. The foam material foams within a drilled hole, forming a porous columnar material that matches the borehole diameter. While supporting the hole wall, the porous columnar material's interpenetrating pores provide channels for gas extraction. The foaming reaction time of components A and B is 2 to 10 minutes.

[0046] The component A comprises the following raw material components by mass percentage: 85% alcohol, 1% foaming agent, 3% pore connecting agent, 1% surfactant and 10% flame retardant;

[0047] The B component is selected from one or both of polymethylene polyphenyl isocyanate and toluene diisocyanate;

[0048] Among them, the NCO mass fraction of polymethylene polyphenyl isocyanate is 30.0% to 32.0%, the viscosity (25°C) is between 50 and 400 mPa·s, the melting point of toluene diisocyanate is 20-22°C, the boiling point is 251.0°C, and the density is 1.225 g / cm 3 .

[0049] As a preferred solution of this embodiment, the alcohol is polyethylene glycol.

[0050] As a preferred solution of this embodiment, the foaming agent is water.

[0051] As a preferred solution of this embodiment, the pore connecting agent includes solid paraffin with a melting point of 25 to 70°C.

[0052] As a preferred solution of this embodiment, the surfactant is silicone oil.

[0053] As a preferred solution of this embodiment, the flame retardant is ammonium polyphosphate.

[0054] As a preferred solution of this embodiment, component B is polymethylene polyphenyl isocyanate.

[0055] The porous foam material is prepared by the following method: 85% alcohol, 1% foaming agent, 3% pore connecting agent, 1% surfactant and 10% flame retardant are mixed and stirred uniformly to obtain component A; component B is mixed with component A in a mass ratio of 2:1 to obtain the porous foam material.

[0056] The porous foam material produced in this example maintains a fluid, slurry-like appearance with good dynamic viscosity, allowing for long-term stable storage for over 180 days at room temperature and pressure, meeting the immediate grouting requirements of engineering sites. By adjusting the ratio of polyol to isocyanate and adding functional components, a porous columnar structure with adjustable physical and chemical properties is formed. After curing, the material achieves compressive strengths of 1-5 MPa, permeability of 0.5-3D, and volume expansion of 2-5 times, meeting the requirements of coal seam projects with varying burial depths, temperatures, and ground stresses.

[0057] During the foaming and expansion stage, the porous foam material achieves efficient filling of the pore walls and cracks through its high viscosity properties. Its interface bonding strength is high, and it can effectively form a composite structure of "external bonding-internal conduction".

[0058] According to existing methods of testing, the porous foam material prepared in this embodiment has a compressive strength of 3.5 MPa, a permeability of 1.67D, and an interface bonding strength of 1.5 MPa.

[0059] Example 2

[0060] like Figures 1 to 4 As shown, this embodiment provides a continuous injection system of a through-hole foaming material for soft coal seams, including a slurry pumping device 1, to which a continuous hose 2 is connected, and a slurry outlet head 3 is provided at the front end of the continuous hose 2; the slurry pumping device 1 is connected to a component A barrel for storing component A and a component A barrel for storing component B through a feed pipe, and the continuous hose 2 can be stored in a continuous hose storage mechanism 6.

[0061] The slurry discharge head 3 includes a guide head 31 and an outer tube 32 connected from front to back; an inner cavity is provided in the outer tube 32, and a stirring shaft 33 is provided in the inner cavity along the axial direction of the outer tube 32, and a plurality of stirring blades 34 are provided on the stirring shaft 33 at equal intervals;

[0062] In this embodiment, the stirring blades 34 adopt a symmetrical double-helix cross-layout structure, that is, the double-helix blades are symmetrically distributed on both sides of the stirring shaft 33, and one end of the stirring blade 34 is connected to the stirring shaft 33, and the other end is connected to the inner wall of the outer tube body 32, thereby forming two slurry passages in the outer tube body 32. The lead of the stirring blade 34 is 50-~65mm, and the wall thickness is 1~2mm. A mixing groove 35 is opened on the stirring blade 34. The mixing groove 35 can mix the two slurries. The mixing groove 35 can be a plurality of regular circular holes or an irregularly shaped groove.

[0063] A slurry outlet 311 communicating with the inner cavity is formed on the front end surface of the guide head 31 .

[0064] As a preferred solution of this embodiment, the continuous hose 2 includes a covering layer 21, a skeleton layer 22, a toughness material layer 23 and an inner lining layer 24 arranged in sequence from the outside to the inside, and at least one slurry conveying channel 25 is arranged axially in the inner lining layer 24; in this embodiment, two slurry conveying channels 25 are arranged.

[0065] The covering layer 21 is interwoven with multiple layers of fibers, and the fibers are selected from one or more of glass fibers, basalt fibers and quartz fibers; the covering layer 21 is coated with a wear-resistant coating, and the thickness of the wear-resistant coating is 1 to 2 mm; the wear-resistant coating material is selected from one or more of diamond powder, silicon carbide powder and ceramic powder; the toughness material layer 23 is a steel-zinc alloy layer, which is used to improve the flexibility of the continuous hose 2; the main body of the skeleton layer is a rigid hollow structure, which provides a certain strength for the continuous hose 2 and facilitates the continuous hose 2 to be delivered into the hole.

[0066] When using this device: the continuous hose 2 is sent to the bottom of the drill hole with the help of the existing continuous hose running device, the slurry pumping device 1 is turned on, and the prepared porous foaming material enters the continuous hose 2, and then reaches the slurry outlet 3 at the end of the hose through the continuous hose 2 for mixing and foaming reaction. Then, the continuous hose 2 is pulled back with the help of the continuous hose running device to realize the operation process of injecting foaming material while pulling it back, realizing the backward continuous foaming operation in the bottom drill hole. The operation is stopped when the continuous hose 2 is pulled back to the hole mouth. If the prepared slurry is consumed during the construction process, the slurry pumping operation and the continuous hose 2 pulling back operation should be stopped at any time, and the operation can be repeated after the porous foaming material is replenished.

[0067] Example 3

[0068] This embodiment provides a method for continuously injecting a porous foam material into a soft coal seam, comprising the following steps:

[0069] Step 1: Drill the hole to the designed depth;

[0070] Step 2: Lower the continuous hose with the slurry outlet connected to the front end into the borehole. When the difference between the length of the continuous hose lowered and the total length of the drill tool in the hole reaches 0.5 m, that is, when the length of the continuous hose lowered exceeds the total length of the drill tool in the hole by 0.5 m, stop lowering the continuous hose.

[0071] Step 3: Take out the drilling tool from the borehole;

[0072] Step 4: Connect the slurry pumping device, set the pumping pressure according to the hole depth, and inject the porous foaming material into the bottom of the hole; during the injection process, pull back the continuous hose according to the set continuous hose pull-back speed to achieve grouting and foaming while pulling back the continuous hose;

[0073] Specifically, when 0m<hole depth≤100m, 1Mpa<pump pressure≤3Mpa, the continuous hose pull-back speed is 3m / min;

[0074] When 100m<hole depth≤200m, 3Mpa<pump pressure≤5Mpa, the continuous hose pull-back speed is 5m / min;

[0075] When 200m<hole depth≤300m, 5Mpa<pump pressure≤8Mpa, the pull-back speed of the continuous hose is 6m / min;

[0076] When 300m<hole depth≤400m, 8Mpa<pump pressure≤11Mpa, the continuous hose pull-back speed is 9m / min;

[0077] When 400m<hole depth≤500m, 11Mpa<pump pressure≤15Mpa, the continuous hose pull-back speed is 10m / min.

[0078] Step 5: Complete the drilling and sealing operations and implement gas extraction.

[0079] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0080] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0081] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A porous foam material for soft coal seams, characterized in that: Comprising component A and component B, wherein the mass ratio of component A to component B is 1:(1-3); The component A comprises the following raw material components by mass percentage: 85-90% alcohol, 0.5-1.0% foaming agent, 3-5% pore connecting agent, 0.5-1% surfactant and 5-10% flame retardant, and the mass percentage of each component totals 100%; The B component is selected from one or both of polymethylene polyphenyl isocyanate and toluene diisocyanate.

2. The through-hole foam material for soft coal seams according to claim 1, characterized in that: The alcohol is selected from any one or any two of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran.

3. The through-hole foam material for soft coal seams according to claim 1, characterized in that: The foaming agent is selected from any one of hydrofluoroolefins, cyclopentane, liquid carbon dioxide and water.

4. The through-hole porous foam material for soft coal seams according to claim 1, characterized in that: The pore connecting agent includes solid paraffin with a melting point of 25 to 70°C.

5. The through-hole porous foam material for soft coal seams according to claim 1, characterized in that: The surfactant is selected from one or more of 1,4-butanediol, glycerol, ethylene glycol and silicone oil.

6. The through-hole porous foam material for soft coal seams according to claim 1, characterized in that: The flame retardant is selected from one or more of ammonium polyphosphate, pentaerythritol and phosphorus-containing polyols.

7. A continuous injection system of porous foaming material for soft coal seams, characterized in that: It comprises a slurry pumping device (1), the slurry pumping device (1) is connected to a continuous hose (2), and a slurry outlet head (3) is provided at the front end of the continuous hose (2); The slurry discharge head (3) comprises a guide head (31) and an outer tube (32) connected from front to back; an inner cavity is provided in the outer tube (32) and is axially penetrated; a stirring shaft (33) is provided in the inner cavity along the axial direction of the outer tube (32); and a plurality of stirring blades (34) are provided on the stirring shaft (33) at equal intervals; A pulp outlet (311) communicating with the inner cavity is provided on the front end surface of the guide head (31).

8. The continuous injection system of porous foam material for soft coal seams according to claim 7, characterized in that: The continuous hose (2) comprises a coating layer (21), a skeleton layer (22), a toughness material layer (23) and an inner lining layer (24) arranged in sequence from the outside to the inside, and at least one slurry conveying channel (25) is arranged in the inner lining layer (24) along the axial direction; The coating layer (21) is formed by interweaving multiple layers of fibers, wherein the fibers are selected from one or more of glass fibers, basalt fibers and quartz fibers; the coating layer (21) is coated with a wear-resistant coating, and the thickness of the wear-resistant coating is 1 to 2 mm; the wear-resistant coating material is selected from one or more of diamond powder, silicon carbide powder and ceramic powder; and the toughness material layer (23) is a steel-zinc alloy layer.

9. A method for continuously injecting porous foaming material into soft coal seams, characterized in that: The following steps are involved: Step 1: Drill the hole to the designed depth; Step 2: Lower the continuous hose with the slurry outlet connected to the front end into the borehole. When the difference between the length of the continuous hose lowered and the total length of the drill bit in the hole reaches 0.5m, stop lowering the continuous hose. Step 3: Take out the drilling tool from the borehole; Step 4: Connect the slurry pumping device, set the pumping pressure according to the hole depth, and inject the porous foam material into the bottom of the hole; during the injection process, pull back the continuous hose according to the set continuous hose pull-back speed; Step 5: Complete the drilling and sealing operations and implement gas extraction.

10. The method for continuous injection of porous foaming material for soft coal seams according to claim 9, characterized in that: In step 4, when 0 m < hole depth ≤ 100 m, 1 MPa < pumping pressure ≤ 3 MPa, the continuous hose pull-back speed is 3 m / min; When 100m<hole depth≤200m, 3Mpa<pump pressure≤5Mpa, the continuous hose pull-back speed is 5m / min; When 200m<hole depth≤300m, 5Mpa<pump pressure≤8Mpa, the pull-back speed of the continuous hose is 6m / min; When 300m<hole depth≤400m, 8Mpa<pump pressure≤11Mpa, the continuous hose pull-back speed is 9m / min; When 400m<hole depth≤500m, 11Mpa<pump pressure≤15Mpa, the continuous hose pull-back speed is 10m / min.

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