Pressure injection fluid expansion solidification hole protection anti-sloughing and pumping protection method

Abstract

The invention relates to a pressure injection fluid expansion curing hole-protecting anti-sloughing pumping-keeping method, which comprises the following steps of: injecting a hole-protecting foaming fluid material into a drill hole in a manner of withdrawing a rod while performing pressure injection, and after the hole-protecting foaming fluid material is completely cured, realizing the anti-sloughing effect of the drill hole; the preparation process of the hole-protecting foaming fluid material comprises the following steps: mixing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylenediamine, polysorbate and solid filler according to a certain proportion, and then stirring at normal temperature for 5-10 minutes; according to the method, the construction process is simpler and more convenient, 48 hours can be saved at most compared with traditional cement paste material hole sealing, consumed time is less, efficiency is high, and flexibility is higher; and meanwhile, the problems that the sieve tube is difficult to lower and the hole protection effect is poor in the hole protection of the traditional PVC perforated sieve tube are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine gas disaster prevention and gas resource development, and particularly relates to a method for protecting holes, preventing collapse and ensuring extraction by pressure-injected fluid expansion and solidification. Background Art

[0002] Coal is the main energy structure in my country. In order to ensure the supply of coal production, various disasters need to be prevented and controlled during underground coal mining. Gas disasters are one of the disasters commonly encountered in coal mines. Low-permeability soft coal is widely distributed in my country. In order to prevent abnormal gas outburst and gas outburst disasters, coal body drilling pre-gas extraction is a widely used basic measure for gas disaster control. During the advancement of underground coal mining working faces, the coal body is in a long-term environment of ground stress and mining stress disturbance. Gas pre-extraction drilling holes often collapse and block under the action of stress, resulting in small gas flow and low concentration in the drilling holes, which greatly reduces the coal body gas pre-extraction effect and even affects the safety of underground coal mining.

[0003] In response to the phenomenon of coal gas pre-extraction drilling holes collapsing, the engineering generally uses screen pipes made of PVC pipes to prevent collapse and ensure extraction. During the pre-extraction drilling process, the screen pipe is lowered through the hollow space of the drill rod until the hole protection depth. For the shallow hole protection needs of pre-extraction drilling, there is also a method of manually pushing down the screen pipe to prevent the collapse of the drilling hole and ensure extraction. However, the screen pipe made of PVC pipes has a limited diameter, small screen holes and a small number, which changes the original open extraction of the entire drilling section to the extraction of a limited number of small holes, reducing the drilling gas extraction efficiency; the screen pipe made of PVC pipes is easily collapsed by wet coal powder after wet drilling, which reduces the hole protection and extraction effect of the PVC perforated screen pipe; for the need to protect the entire section of a long borehole, the PVC perforated screen pipe has the problem of difficulty in lowering the screen pipe over a long distance, and the diameter, depth or angle of the borehole generally has deviations, which further increases the difficulty of lowering the screen pipe to protect the hole. In addition, the PVC perforated screen pipe protection technology requires the purchase of a large number of PVC pipes, and workers are required to perform additional processing and drilling, which consumes a lot of time, labor and costs.

[0004] In summary, it can be seen that in order to solve the problem of coal gas pre-extraction drilling hole collapse, a new method for preventing gas extraction drilling hole collapse is urgently needed. To this end, the present invention proposes a method for preventing gas extraction drilling hole collapse by injecting fluid expansion and solidification, which can improve the drilling hole formation rate of coal seam gas extraction, simplify the drilling hole protection and extraction process, and ensure the gas extraction flow and concentration of coal body drilling holes. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for pressurized fluid expansion and solidification to prevent hole collapse and ensure extraction. A grouting pump can be used to inject a foaming fluid material into the gas pre-extraction borehole to expand and protect the borehole, thereby achieving the dual effects of preventing hole collapse and extracting flow in the coal gas extraction borehole, and solving the problems of difficult lowering of the screen pipe and poor hole protection effect in traditional PVC perforated screen pipe hole protection.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for protecting a hole from collapse and pumping by pressure-injecting fluid for expansion and solidification, comprising the following steps:

[0008] Step 1: According to the length of the coal gas pre-extraction borehole, the mechanical properties of the coal, the borehole stress environment, and the drill rod withdrawal speed, the borehole protection foaming fluid material is prepared and injected into the borehole by a grouting pump;

[0009] The preparation process of the pore-protecting foaming fluid material includes: mixing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylene diamine, polysorbate and solid filler in a certain proportion, and then stirring at room temperature for 5-10 minutes;

[0010] Step 2: After the gas pre-extraction drilling is completed, during the retreat of the drill pipe, the hole-protecting foaming fluid material is injected through the hollow drill pipe, and the hole-protecting foaming fluid material is continuously injected from the deep part of the borehole to the shallow part to fill the borehole;

[0011] Step 3: When the hole-protecting foaming fluid material is completely solidified, the anti-collapse effect of the borehole is achieved. At the same time, the hole-protecting foaming fluid material forms a large number of pores during the foaming process, ensuring the stability and effectiveness of the borehole gas extraction flow.

[0012] Furthermore, the pore-protecting foaming fluid material includes the following raw materials in parts by weight: 25-35 parts of water, 350-550 parts of polyether polyol, 250-350 parts of polyisocyanate, 8-12 parts of triethylene diamine, 8-12 parts of polyoxyethylene alkyl ether, 0.8-1.2 parts of fatty acid alcohol amide, 8-12 parts of tetramethylethylenediamine, 0.8-1.2 parts of polysorbate, and 12-18 parts of solid filler.

[0013] Furthermore, the particle size of the solid filler is 0.9-1.1 mm, and the solid filler is one or more of coal powder and gangue powder.

[0014] Furthermore, the pore-protecting foaming fluid material includes the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0015] Furthermore, by adjusting the ratio of fatty acid alcohol amide, the porosity of the pore-protecting foaming fluid material after solidification is adjusted, and the foaming multiple of the pore-protecting foaming fluid material can be adjusted in the range of 2-20 times.

[0016] Furthermore, by adjusting the polyether polyol and polyisocyanate components, the foaming time of the pore-protecting foaming fluid material can be adjusted to a range of 0.5-5 hours.

[0017] Furthermore, by adjusting the proportion of tetramethylethylenediamine, the curing time of the hole-protecting foaming fluid material can be adjusted in the range of 0.5-7 hours, which can meet the hole-protecting curing time requirements of drilling holes of different depths.

[0018] Furthermore, in step 1, a preliminary experiment of foaming and curing of the pore-protecting foaming fluid material is carried out before formal preparation to measure the foaming time and curing time of the pore-protecting foaming fluid material and the foaming multiple, porosity and compressive strength of the cured material to determine the proportion of basic components and the foaming support effect achieved.

[0019] Furthermore, the pre-experimental steps of foaming and curing the pore-protecting foaming fluid material include:

[0020] (1) preparing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylenediamine, polysorbate and solid filler in a ratio of 30:450:300:10:10:1:10:1:15, respectively, pouring into a blender for uniform stirring, and then pouring into a foaming machine for foaming and curing, and measuring the curing time, foaming multiple, compressive strength and porosity thereof;

[0021] (2) According to the drilling depth, hole protection position and drill rod withdrawal speed, the time required for the hole protection foaming fluid material to foam and solidify is analyzed, the reasonable raw material ratio and flow rate of the hole protection foaming fluid material are adjusted, and the raw material composition of the hole protection foaming fluid material under the current working conditions is determined, so that the hole protection foaming fluid material after solidification can reach a compressive strength of more than 9 MPa.

[0022] The beneficial effects of the present invention are:

[0023] The hole-protecting foaming fluid material of the present invention is injected through the hollow space of the drill pipe, which greatly improves the efficiency of drilling hole collapse prevention; the foaming multiple (porosity) of the hole-protecting foaming fluid material is adjustable to meet the different drilling hole extraction volume requirements; the solidification time of the hole-protecting foaming fluid material is adjustable to meet the construction requirements of different hole protection depths of the drilling hole; the solidification hardness of the hole-protecting foaming fluid material is adjustable to meet the support strength requirements of different ground stress environments of gas pre-extraction drilling holes. Compared with the traditional PVC screen pipe collapse prevention technology, the method of injecting fluid expansion and solidification to protect the hole against collapse and extraction proposed by the present invention is simpler in construction technology, and can save up to 48 hours of time compared with the traditional cement slurry material sealing, with high efficiency and greater flexibility; at the same time, it solves the problems of difficult lowering of the screen pipe and poor hole protection effect in the traditional PVC perforated screen pipe hole protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0025] Figure 1 This is a physical photograph of the pore-protecting foaming fluid material after solidification in Example 1 of the present invention.

[0026] Figure 2 for Figure 1 A partial enlarged view of .

[0027] Figure 3 for Figure 1 Local scanning electron microscope image.

[0028] Figure 4 This is a diagram showing the changes in compression stroke under different pressures after the pore-protecting foaming fluid material of Example 1 of the present invention is solidified. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0030] A method for protecting a hole from collapse and pumping by pressure-injecting fluid for expansion and solidification, comprising the following steps:

[0031] Step 1: According to the length of the coal gas pre-extraction borehole, the mechanical properties of the coal, the borehole stress environment, and the drill rod withdrawal speed, the borehole protection foaming fluid material is prepared and injected into the borehole by a grouting pump;

[0032] The preparation process of the pore-protecting foaming fluid material includes: mixing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylene diamine, polysorbate and solid filler in a certain proportion, and then stirring at room temperature for 5-10 minutes;

[0033] Step 2: After the gas pre-extraction drilling is completed, during the withdrawal of the drill pipe, the hole-protecting foaming fluid material is injected through the hollow drill pipe, and the hole-protecting foaming fluid material is continuously injected from the deep part of the borehole to the shallow part, and the grouting flow rate is adjusted according to the withdrawal speed to fill the borehole; it should be noted that the hole-protecting foaming fluid material filled here is only filled into the borehole at low pressure, and has no fracturing effect on the borehole wall;

[0034] Step 3: When the hole-protecting foaming fluid material is completely solidified, Figures 1 to 3 As shown, the solidified hole-protecting foaming fluid material is a porous solid with uniform pore structure and good air permeability. It can form a supporting effect with sufficient strength and can achieve the effect of preventing the borehole from collapsing. At the same time, the hole-protecting foaming fluid material forms a large number of pores during the foaming process, which ensures the stability and effectiveness of the borehole gas extraction flow rate and achieves the purpose of preventing the collapse and ensuring the extraction of coal gas pre-extraction drilling holes.

[0035] The hole-protecting foaming fluid material of the present invention is injected through the hollow space inside the drill pipe, and the injection operation is performed during the retreat of the drill pipe. Compared with the traditional PVC perforated screen pipe hole protection method, it is simpler and has stronger operability;

[0036] The hole protection, anti-collapse and extraction foaming fluid material has the property of being pressurized and can be pressurized into the gas pre-extraction borehole by a grouting pump to expand and protect the borehole. The hole protection, anti-collapse and extraction foaming fluid material contains solid filler particles which can ensure the compressive strength and compressibility of the solidified material. Under the action of stress, it can shift inside to produce crack channels, further improving the porosity and connectivity, and achieving the dual effects of hole protection, anti-collapse and extraction flow rate for coal gas extraction boreholes.

[0037] Furthermore, the pore-protecting foaming fluid material includes the following raw materials in parts by weight: 25-35 parts of water, 350-550 parts of polyether polyol, 250-350 parts of polyisocyanate, 8-12 parts of triethylene diamine, 8-12 parts of polyoxyethylene alkyl ether, 0.8-1.2 parts of fatty acid alcohol amide, 8-12 parts of tetramethylethylenediamine, 0.8-1.2 parts of polysorbate, and 12-18 parts of solid filler; wherein the particle size of the solid filler is 0.9-1.1 mm, and the solid filler is a combination of one or two of coal powder and gangue powder.

[0038] The functions of the components in the raw materials of the pore-protecting foaming fluid material are as follows:

[0039] Polyether polyol and polyisocyanate: They are the main raw materials for synthesizing the pore-protecting foaming fluid material and the basis for the formation of the pore-protecting foaming fluid material. The physical properties of the carrier of the pore-protecting foaming fluid material can be adjusted by the ratio of the two.

[0040] Triethylenediamine: As a catalyst, it is mainly used to accelerate the curing process and hardness of the pore-protecting foaming fluid material; the strength of the final product can be adjusted by changing its dosage;

[0041] Polyoxyethylene alkyl ether: a surfactant, mainly used to control the uniformity and stability of foam and help form a uniform foam structure; the foaming multiple can be adjusted by changing its dosage;

[0042] Fatty acid alcohol amide: a nonionic surfactant that acts as an emulsifier, thickener and foam stabilizer to help form and stabilize foam; has a synergistic effect with polyoxyethylene alkyl ether;

[0043] Tetramethylethylenediamine: As a foaming catalyst, it promotes the reaction between isocyanate and polyol, accelerates the formation of the pore-protecting foaming fluid material, and mainly adjusts the curing time of the pore-protecting foaming fluid material;

[0044] Polysorbate: A surfactant that acts as an emulsifier or dispersant, helping to disperse other ingredients and ensure the homogeneity of the mixture;

[0045] Solid filler: Solid filler provides the anti-compression property of the framework for the hole-protecting foaming fluid material, and has the function of resisting the deformation and damage of the coal body under stress and buffering the pressure. The solid fillers in the hole-protecting foaming fluid material after solidification shift with each other under the action of stress, generating new fracture channels, further increasing the permeability of the material and ensuring the gas pre-extraction drilling flow rate of the coal body;

[0046] Water: acts as a reaction medium and reacts with isocyanate to produce carbon dioxide gas, promoting foam formation;

[0047] The characteristics of this material are: (1) while supporting the drilling, it forms sufficient porosity to ensure extraction; (2) the support material has a certain compressive strength and compressibility, which alleviates the support failure caused by rigid damage.

[0048] Furthermore, in step 1, before the actual injection, it is generally necessary to carry out a preliminary experiment on the foaming and curing of the hole-protecting foaming fluid material indoors to measure the curing time of the hole-protecting foaming fluid material and the foaming multiple, porosity and compressive strength of the cured material, and determine the reasonable raw material composition and proportion to achieve the expected foaming and curing effect; according to the borehole diameter, borehole depth and the amount of gas to be extracted, the foaming hole-protecting material with different curing times is deployed.

[0049] Specifically, the pre-experimental steps of foaming and curing the pore-protecting foaming fluid material include:

[0050] (1) Debug the mixing grouting pump and other equipment, check the operating status and performance of the equipment, and ensure the normal operation of the equipment;

[0051] Prepare water, polyether polyol, polyisocyanate, triethylenediamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylenediamine, polysorbate and solid filler in a weight ratio of 30:450:300:10:10:1:10:1:15, pour them into a blender for uniform stirring, then pour them into a foaming machine for foaming and curing, and measure the curing time, foaming multiple, compressive strength and porosity respectively;

[0052] (2) According to the drilling depth, hole protection position and drill rod withdrawal speed, the time required for the hole protection foaming fluid material to foam and solidify is analyzed, the reasonable raw material ratio and flow rate of the hole protection foaming fluid material are adjusted, and the raw material composition of the hole protection foaming fluid material under the current working conditions is determined, so that the solidified hole protection foaming fluid material can reach a compressive strength of more than 9MP, resist the mine pressure, and avoid hole collapse.

[0053] Among them, water, polyether polyol, polyisocyanate, triethylenediamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylenediamine, polysorbate and solid filler are adjusted according to the ratio range of (25-35):(350-550):(250-350):(8-12):(8-12):(0.8-1.2):(8-12):(0.8-1.2):(12-18).

[0054] Furthermore, by adjusting the proportion of fatty acid alcohol amide, the porosity of the pore-protecting foaming fluid material after curing is adjusted, and the foaming multiple of the pore-protecting foaming fluid material can be adjusted in the range of 2-20 times; by adjusting the polyether polyol and polyisocyanate components, the foaming time of the pore-protecting foaming fluid material can be adjusted in the range of 0.5-5 hours; by adjusting the proportion of tetramethylethylenediamine, the curing time of the pore-protecting foaming fluid material can be adjusted in the range of 0.5-7 hours, which can meet the curing time requirements of the pore protection at different drilling depths.

[0055] Furthermore, step 2 includes the following steps:

[0056] (1) After the drill pipe construction is completed, increase the water pressure in the drill pipe, open the drill bit at the bottom of the hole, and wash the hole to remove dust;

[0057] (2) Pour the raw materials of the hole-protecting foaming fluid material with a determined raw material ratio into the stirring grouting pump and stir them evenly. The grouting pump is connected to the grouting hose, and the grouting hose is connected to the hollow drill pipe. Start injecting the hole-protecting foaming fluid material, and measure the flow rate, flow velocity, and time;

[0058] (3) Remove the drill rods one by one, turn off the grouting pump when removing the drill holes, disconnect the grouting hose from the drill rod, reconnect the grouting hose to the drill rod after the drill rod is removed, and turn on the grouting pump to inject the hole protection foaming fluid material;

[0059] (4) Repeat steps (2) and (3) until the hole guard position reaches the planned depth, terminate the grouting hole guard, disconnect the grouting hose from the drill pipe, and clean the grouting hose and grouting pump;

[0060] (5) Seal and continue to extract gas from the gas pre-extraction holes.

[0061] The following is a detailed description with reference to the embodiments. The water used in each embodiment is tap water, the solid filler is coal powder with a particle size of about 1 mm, and the coal powder used here is produced during the drilling process of the coal mine; other raw materials are all of chemically pure or above grade.

[0062] Example 1

[0063] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0064] The ratio in Example 1 is taken as the basic ratio, and the subsequent Examples 2 to 7 are adjusted on this basis.

[0065] Example 2

[0066] Compared with Example 1, the triethylenediamine component is changed in Example 2 in order to compare the change in strength of the pore-protecting foaming fluid material after curing.

[0067] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 8 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0068] Example 3

[0069] Compared with Example 2, the triethylenediamine component is changed in Example 3 in order to compare the change in strength of the pore-protecting foaming fluid material after curing.

[0070] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 12 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0071] Example 4

[0072] Compared with Example 1, Example 4 changes the proportions of polyoxyethylene alkyl ether and fatty acid alcohol amide in order to compare the changes in foaming multiples.

[0073] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 8 parts of polyoxyethylene alkyl ether, 0.8 parts of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0074] Example 5

[0075] Compared with Example 4, Example 5 changes the proportions of polyoxyethylene alkyl ether and fatty acid alcohol amide in order to compare the changes in foaming multiples.

[0076] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 12 parts of polyoxyethylene alkyl ether, 1.2 parts of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0077] Example 6

[0078] Compared with Example 1, Example 6 changes the amount of tetramethylethylenediamine in order to compare the change in curing time.

[0079] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 8 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0080] Example 7

[0081] Compared with Example 6, Example 7 changes the amount of tetramethylethylenediamine in order to compare the change in curing time.

[0082] The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 12 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

[0083] Comparative Example 1

[0084] No solid filler is added to the raw materials of Comparative Example 1, and the amounts and proportions of other raw materials are the same as those of the embodiment.

[0085] Comparative Example 2

[0086] Traditional cement slurry materials use cement as the main material. Here, silicate cement is taken as an example. Its composition is tetracalcium aluminoferrate, dicalcium silicate, tricalcium silicate, and tricalcium aluminate. The water-cement ratio is 1 as an example.

[0087] The pore-protecting foaming fluid materials of the above embodiments and comparative examples were subjected to pressure injection experiments and tests in the room through an indoor simulated drilling device. The main structure of the indoor simulated drilling device includes a simulated drilling, a stirring grouting pump, and a drill rod; the simulated drilling is made of a transparent plastic tube with a diameter of 10 cm and a length of 2 m; after the pore-protecting foaming fluid material is solidified, the transparent plastic tube is cut open and the solidified pore-protecting foaming fluid material is taken out for compressive strength testing. The foaming multiple is determined by measuring the volume before and after foaming, which is completed in the laboratory using a measuring cup or a measuring cylinder.

[0088] The test results are shown in Table 1 and Figure 1-Figure 4 :

[0089] Table 1 Test results of embodiments and comparative examples

[0090] Test items Compressive strength(Mpa) Foaming multiple Curing time (h) Example 1 12.35 11.5 3.4 Example 2 9.2 11.8 3.9 Example 3 15.68 10.7 3.1 Example 4 12.42 2.6 6.7 Example 5 12.64 20.1 2.7 Example 6 12.28 12.5 5.8 Example 7 12.16 10.9 0.55 Comparative Example 1 4.58 13.6 4.2 Comparative Example 2 10.9 1.0 24.6

[0091] Figures 1 to 3 This is the appearance of the pore-protecting foamed fluid material of Example 1 after solidification. It can be seen that it is cylindrical as a whole, with many openings on the surface and inside. These openings are interconnected to serve as gas extraction channels.

[0092] Figure 4 This is a test comparison chart of the pore-protecting foamed fluid material of Example 1 and the traditional cement slurry pore-protecting material of Comparative Example 2. The vertical axis in the figure is the pressure applied to the material after solidification, and the horizontal axis is the length compression stroke of the material; the compression stroke is measured by a rock mechanics test (similar to the test of concrete cylindrical specimens).

[0093] By comparing the test results of Example 1 with those of Comparative Example 1, it can be seen that the solid filler in the pore-protecting foaming fluid material significantly enhances the compressive strength of the pore-protecting foaming fluid material on the basis of the strength of the foaming material, and the compressive strength increases by about 2 times after adding the solid filler.

[0094] By comparing the test results of Example 1 and Comparative Example 2, it can be seen that the pore-protecting foaming fluid material has a significant advantage in foaming expansion, which is the main performance for forming an extraction channel to ensure the extraction effect; and has better compressive strength performance, while significantly shortening the curing time and significantly improving the construction efficiency.

[0095] Comparing Example 1, Example 2 and Example 3, as the content of triethylenediamine increases, the compressive strength increases successively, indicating that adjusting the content of triethylenediamine has the effect of regulating the strength of the final product.

[0096] Comparing Example 1, Example 4 and Example 5, the change in the amount of polyoxyethylene alkyl ether and fatty acid alcohol amide has a significant effect on the foaming multiple; as the amount of polyoxyethylene alkyl ether and fatty acid alcohol amide increases, the foaming multiple increases.

[0097] Comparing Example 1, Example 6 and Example 7, as the amount of tetramethylethylenediamine increases, the curing time of the pore-protecting foaming fluid material decreases, indicating that adjusting the amount can effectively adjust the curing time of the pore-protecting foaming fluid material.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A method for preventing hole collapse and pumping by pressure-injected fluid expansion and solidification, characterized in that: The following steps are involved: Step 1: According to the length of the coal gas pre-extraction borehole, the mechanical properties of the coal, the borehole stress environment, and the drill rod withdrawal speed, the borehole protection foaming fluid material is prepared and injected into the borehole by a grouting pump; The preparation process of the pore-protecting foaming fluid material includes: mixing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylene diamine, polysorbate and solid filler in a certain proportion, and then stirring at room temperature for 5-10 minutes; Step 2: After the gas pre-extraction drilling is completed, during the retreat of the drill pipe, the hole-protecting foaming fluid material is injected through the hollow drill pipe, and the hole-protecting foaming fluid material is continuously injected from the deep part of the borehole to the shallow part to fill the borehole; Step 3: When the hole-protecting foaming fluid material is completely solidified, the anti-collapse effect of the borehole is achieved. At the same time, the hole-protecting foaming fluid material forms a large number of pores during the foaming process, ensuring the stability and effectiveness of the borehole gas extraction flow.

2. The method for protecting holes from collapse and pumping by expanding and solidifying injected fluid according to claim 1, characterized in that: The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 25-35 parts of water, 350-550 parts of polyether polyol, 250-350 parts of polyisocyanate, 8-12 parts of triethylene diamine, 8-12 parts of polyoxyethylene alkyl ether, 0.8-1.2 parts of fatty acid alcohol amide, 8-12 parts of tetramethylethylenediamine, 0.8-1.2 parts of polysorbate, and 12-18 parts of solid filler.

3. The method for protecting holes from collapse and pumping by expanding and solidifying injected fluid according to claim 2, characterized in that: The particle size of the solid filler is 0.9-1.1 mm, and the solid filler is one or more of coal powder and gangue powder.

4. The method for preventing hole collapse and pumping by pressure injection fluid expansion and solidification according to claim 2 is characterized in that: The pore-protecting foaming fluid material comprises the following raw materials in parts by weight: 30 parts of water, 450 parts of polyether polyol, 300 parts of polyisocyanate, 10 parts of triethylene diamine, 10 parts of polyoxyethylene alkyl ether, 1 part of fatty acid alcohol amide, 10 parts of tetramethylethylenediamine, 1 part of polysorbate, and 15 parts of solid filler.

5. The method for protecting holes from collapse and pumping by expanding and solidifying injected fluid according to claim 2, characterized in that: By adjusting the ratio of fatty acid alcohol amide, the porosity of the pore-protecting foaming fluid material after solidification is adjusted, and the foaming multiple of the pore-protecting foaming fluid material can be adjusted in the range of 2-20 times.

6. The method for protecting holes from collapse and pumping by expanding and solidifying injected fluid according to claim 2, characterized in that: By adjusting the polyether polyol and polyisocyanate components, the foaming time of the pore-protecting foaming fluid material can be adjusted to a range of 0.5-5 hours.

7. The method for protecting holes from collapse and pumping by pressure-injected fluid expansion and solidification according to claim 2, characterized in that: By adjusting the proportion of tetramethylethylenediamine, the curing time of the hole-protecting foaming fluid material can be adjusted in the range of 0.5-7 hours, which can meet the hole-protecting curing time requirements of drilling holes of different depths.

8. The method for protecting holes from collapse and pumping by expanding and solidifying injected fluid according to claim 1, characterized in that: In step 1, a preliminary experiment of foaming and curing of the pore-protecting foaming fluid material is carried out before formal preparation to measure the foaming time and curing time of the pore-protecting foaming fluid material and the foaming multiple, porosity and compressive strength of the cured material to determine the proportion of basic components and the foaming support effect achieved.

9. The method for protecting holes from collapse and pumping by pressure-injected fluid expansion and solidification according to claim 1, characterized in that: The pre-experimental steps for foaming and curing of the hole-protecting foaming fluid material include: (1) preparing water, polyether polyol, polyisocyanate, triethylene diamine, polyoxyethylene alkyl ether, fatty acid alcohol amide, tetramethylethylenediamine, polysorbate and solid filler in a ratio of 30:450:300:10:10:1:10:1:15, respectively, pouring into a blender for uniform stirring, and then pouring into a foaming machine for foaming and curing, and measuring the curing time, foaming multiple, compressive strength and porosity thereof; (2) According to the drilling depth, hole protection position and drill rod withdrawal speed, the time required for the hole protection foaming fluid material to foam and solidify is analyzed, the reasonable raw material ratio and flow rate of the hole protection foaming fluid material are adjusted, and the raw material composition of the hole protection foaming fluid material under the current working conditions is determined, so that the hole protection foaming fluid material after solidification can reach a compressive strength of more than 9 MPa.

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