A grouting hole sealing material and a preparation method thereof

Abstract

The application provides a grouting hole sealing material and a preparation method thereof, relates to the technical fields of mine safety and high polymer composite materials, and is prepared from the following raw materials in parts by weight: a framework component 30-50 parts, a reinforcing and reinforcing component 15-30 parts, a state adjusting component 2-10 parts, a state stabilizing component 8-20 parts, and an anti-corrosion and antibacterial component 0.2-2 parts. The water content of each raw material component of the grouting hole sealing material is less than 1%, the particle size D90 is less than or equal to 120 microns and can pass through a 100-mesh screen, and the raw materials of the grouting hole sealing material do not contain cement, polyurethane prepolymer and isocyanate curing agent. The grouting hole sealing material and the gas extraction drilling sealing method provided by the application do not contain cement, polyurethane prepolymer and isocyanate curing agent, realize the controllable gelation and long-term self-adaptive sealing, and further improve the sealing and extraction stability.

Description

Technical Field

[0001] This invention belongs to the field of mine safety and polymer composite materials technology, specifically relating to a grouting and sealing material and its grouting and sealing method, and more particularly to a grouting and sealing material and its grouting and sealing method for sealing gas extraction boreholes. Background Technology

[0002] Gas drainage is a crucial step in coal mine gas control and coalbed methane development. The quality of borehole sealing directly determines the drainage concentration, flow rate, and duration. Primary fractures typically exist in the coal and rock mass surrounding the borehole, and secondary fractures can be generated under mining stress, ground stress, and negative pressure during drainage, forming leakage channels. Among traditional sealing materials, cement-based materials are low-cost, but suffer from large curing shrinkage, significant brittleness, insufficient early strength and adhesion, and are prone to cracking under disturbance, making them difficult to seal micro-fractures. Polyurethane materials, while fast-reacting and foaming, have limited strength and toughness due to difficulty in controlling the foaming ratio and curing time, and often contain isocyanates, making them sensitive to humid environments and posing high construction and environmental risks. Ordinary inorganic / organic composite slurries also suffer from high water content, coarse particle size, poor suspension stability and antibacterial properties, and difficulty in balancing gel time and sealing strength. With the development of deep mining and long-cycle extraction, the sealing section is often in a humid, pressurized and dynamically disturbed environment, and secondary fractures will continue to expand. The sealing material is required to be able to penetrate into micro fractures with low viscosity, form a high viscoelastic gel, absorb water and expand under humid conditions, and self-repair through creep. At the same time, it should have low shrinkage, anti-corrosion and antibacterial properties, and long-term stability.

[0003] Therefore, there is a need for a grouting sealing material and method that is free of cement, polyurethane prepolymer and isocyanate curing agent, can form a high-viscosity gel in the range of low to high water-to-material ratio, has low shrinkage, high toughness, self-healing ability, and is suitable for sealing gas extraction boreholes. Summary of the Invention

[0004] The purpose of this application is to provide a grouting sealing material and its preparation method, to solve the problems of existing cement-based, polyurethane-based, and ordinary composite sealing materials, such as shrinkage cracking, high brittleness, uncontrollable curing or foaming, poor moisture adaptability, isocyanate content, insufficient injectability in microcracks, and poor antibacterial stability. In particular, after secondary cracks are generated in gas drainage boreholes under disturbance, the sealing body is difficult to self-fill and maintain pressure for a long time, resulting in gas leakage and a decrease in extraction concentration. This application aims to solve the problems of low viscosity injectability, controllable gelation, high viscoelasticity and low shrinkage, wet self-healing and corrosion resistance stability in a system without cement, polyurethane prepolymer, or isocyanate curing agent through multi-component compounding.

[0005] In view of the above problems, this application provides a grouting sealing material and its preparation method.

[0006] The present invention provides a grouting and sealing material, which, by weight, is made of the following raw materials: 30-50 parts of skeleton component, 15-30 parts of reinforcing component, 2-10 parts of state conditioning component, 8-20 parts of state stabilizing component, and 0.2-2 parts of anti-corrosion and antibacterial component. The raw materials of the grouting and sealing material do not contain cement, polyurethane prepolymer, or isocyanate curing agents. The skeleton component is a mixture of modified hydroxypropyl methylcellulose and nanocellulose in a mass ratio of 5:1 to 10:1, and the viscosity of a 3% aqueous solution at 25°C is 200,000 to 250,000 mPa·s. The nanocellulose is pre-dispersed with sodium carboxymethyl cellulose, and the mass ratio of sodium carboxymethyl cellulose to nanocellulose is 1:10 to 1:3. The reinforcing components are modified silica, superabsorbent resin, calcium lactate, magnesium oxide and silane coupling agent compounded in a mass ratio of (5~8):(3~6):(2~4):(1~3):(0.5~1.5). The modified silica is fumed silica modified with silane coupling agent KH550, and the superabsorbent resin is sodium polyacrylate with a water absorption ratio of 30~300 g / g in 0.9 wt% NaCl aqueous solution. The state-conditioning component is a compound of citric acid, sodium citrate, borax and sodium dodecylbenzenesulfonate in a mass ratio of (0.5~1.5):(1~3):(1~4):(0.5~2), and the state-conditioning component makes the pH of the slurry after the material is mixed with water in a mass ratio of 1:25~1:35 7.5~9.5. The stable components are modified magnesium lithium silicate, polyvinyl alcohol powder, modified organic bentonite, sodium alginate and organosilicon defoamer compounded in a mass ratio of (3~8):(2~6):(2~6):(1~4):(0.2~1), and the modified organic bentonite is quaternary ammonium salt modified bentonite. The antiseptic and antibacterial component is a mixture of potassium sorbate and natamycin in a mass ratio of 1:1 to 3:1.

[0007] Another aspect of the present invention provides a grouting and sealing method for the above-mentioned grouting and sealing material, used for sealing gas extraction boreholes, comprising: (1) Dry each raw material separately until the moisture content is less than 1%, crush it through a 100-300 mesh sieve, and mix them to obtain a whole powder; (2) Mix the whole powder with water at a mass ratio of 1:28 to 1:35 and stir for 3 to 10 minutes to obtain the first slurry. Mix the whole powder with water at a mass ratio of 1:20 to 1:27 and stir for 3 to 10 minutes to obtain the second slurry. The first and second slurries are heated at 25°C and a shear rate of 10 s. -1The initial viscosity of the first slurry is less than 50 mPa·s, and the viscosity of the second slurry is higher than that of the first slurry. (3) Install plugs at both ends of the sealing section and inject the first grout using a two-plug-one-injection process with a grouting pressure of 0.5~2MPa, so that the first grout can penetrate into the 1~500μm fissures around the borehole. (4) Inject the second grout through the grouting pipe at a grouting pressure of 0.1~0.3MPa to drive the first grout into the crack and maintain pressure and fill the hole in the sealing section; (5) Allow the slurry in the sealing section to react under pressure for 5 to 120 minutes to form the sealing body of the gel; (6) During the extraction process, when the extraction concentration drops by more than 20% from the initial concentration, or the absolute extraction concentration is less than 30%, secondary grouting is carried out through the grouting pipe. The grouting pressure is 0.1~0.3MPa, and the water-to-material ratio of the secondary grouting is 20:1~27:1.

[0008] Preferably, before step (3), the method further includes observing the width of the cracks around the sealing section and the effective sealing length, specifically including: When the width is less than 0.5 mm and the length of the sealing section is 8 m, the water-to-material ratio of the first grout is 32:1 to 35:1, and the grouting pressure is 0.6 to 0.8 MPa. When the width is 0.5~2.0 mm and the length of the sealing section is 8~12 m, the water-to-material ratio of the first grout is 30:1~33:1 and the grouting pressure is 0.8~1.2 MPa; When the width is greater than 2.0 mm and the length of the sealing section is greater than 12 m, the water-to-material ratio of the first grout is 28:1 to 30:1, and the grouting pressure is 1.2 to 1.5 MPa. The grouting pressure in steps (4) and (6) is 0.1~0.3MPa; During the grouting process, when the pressure rise rate is >0.5MPa / min, the grouting pressure is reduced to 50%~80% of the original pressure, and the reduction rate is 0.1~0.3 MPa / min.

[0009] Preferably, the grouting and sealing material is the grouting and sealing material described in the aforementioned aspect. In steps (5) and (6), the relative humidity of the sealing section is controlled to be ≥60%, so that the total mass of calcium carbonate and calcium silicate in the repair products generated in the secondary crack is ≥60%. When the width of the secondary crack is ≤1.5 mm, the crack cross-sectional area reduction rate is ≥90% within 8 days. The total mass is quantified by XRDRietveld precision repair.

[0010] Preferably, a three-bag sealing device is used, comprising two primary grouting bags at both ends of the sealing section and a secondary grouting bag in the middle. The grouting pipe is connected to the primary grouting bags, the first end of the grouting pipe is connected to the secondary grouting bags, and the second end is connected to the grout storage tank. The grout storage tank is connected to the downhole ventilation pipe, and a pressure of 0.2~0.6MPa is applied to the grout in the grout storage tank through a pressure reducing valve and a pressure stabilizing tank, with a pressure fluctuation of ±0.05MPa. The bursting pressure of the bladder is 1.2 to 2 times the grouting pressure in step (3), and not less than 0.6 MPa; The volume of the pressure stabilizing tank is 10% to 30% of the volume of the slurry storage tank; One or more technical solutions provided in this application have at least the following technical effects or advantages: 1. An organic-inorganic synergistic network is constructed using modified HPMC and nanocellulose, which is free of cement, polyurethane prepolymer and isocyanate curing agents, making it environmentally friendly and safe; 2. The pH of the slurry is controlled at 7.5~9.5 by adjusting the state components to ensure that borax and polyvinyl alcohol form borate crosslinks, and the gelation time can be adjusted within 5~120 min; 3. The gel was kept at 25°C for 1 second. -1 With a viscosity greater than 200,000 mPa·s, a 28-day volume shrinkage rate ≤0.5%, and a fracture strain ≥10%, it combines high viscosity with low shrinkage and high toughness. 4. The superabsorbent resin has a water absorption swelling ratio of ≥30 g / g in 0.9 wt% NaCl aqueous solution after 7 days. It can absorb water and swell when secondary cracks are generated and cooperate with the creep of cellulose network to achieve adaptive filling. 5. The use of a three-bag sealing device and pressure control enables two-stop and one-injection, grouting and pressure maintenance, and secondary grouting, thereby improving the sealing effect of gas extraction boreholes. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of the three-bag sealing device of the present invention.

[0013] Explanation of reference numerals in the attached figures: 1. Extraction pipe, 2. Primary grouting bag, 3. Secondary grouting bag, 4. Grouting pipe, 5. Grouting supply pipe, 6. Grouting tank, 7. Pressure reducing valve, 8. Pressure stabilizing tank, 9. Downhole ventilation pipe. Detailed Implementation

[0014] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims. Furthermore, it should be emphasized that the following performance data are exemplary data obtained according to conventional testing methods in the art, and those skilled in the art can make adjustments within the scope of the claims.

[0015] This application provides a grouting sealing material and its preparation method, solving the problems of traditional cement-based, polyurethane-based, and ordinary composite sealing materials in the prior art, such as shrinkage cracking, high brittleness, uncontrollable curing or foaming, poor moisture adaptability, isocyanate content, insufficient injectability in microcracks, and poor antibacterial stability. In particular, after secondary cracks are generated in gas drainage boreholes under disturbance, the sealing body is difficult to self-fill and maintain pressure for a long time, resulting in gas leakage and a decrease in extraction concentration. This application aims to solve the problems of low viscosity injectability, controllable gelation, high viscoelasticity and low shrinkage, wet self-healing and corrosion resistance stability in a system without cement, polyurethane prepolymer, or isocyanate curing agent through multi-component compounding. Therefore, this application aims to provide a grouting and sealing material and a gas extraction borehole sealing method that does not contain cement, polyurethane prepolymer, or isocyanate curing agents. This material achieves low water content, fine particle size, and easy dispersion of the powder; low initial viscosity of the grout, allowing penetration into 1–500 μm cracks; controllable gelation time; and high viscoelasticity, low shrinkage, and antibacterial and anti-corrosion properties in the sealing body. Furthermore, it restores the seal by replenishing and secondary grouting when the extraction concentration decreases, adaptively repairing secondary cracks and ensuring long-term high efficiency in gas extraction. Through the synergistic effect of the skeleton, reinforcement, state adjustment, state stabilization, and anti-corrosion and antibacterial components, the material achieves a water content of less than 1%, a fine particle size that can pass through a 100-mesh sieve, a grout pH of 7.5–9.5, and forms a gel within 5–120 minutes after mixing with water. The gel is then subjected to a 1-second reaction at 25°C. -1 With a viscosity greater than 200,000 mPa·s, a 28-day volume shrinkage rate ≤0.5%, and a fracture strain ≥10%, the superabsorbent resin has a water absorption rate ≥30 g / g in 0.9 wt% sodium chloride for 7 days and expands when it absorbs water at a relative humidity ≥60%. It synergistically fills secondary cracks with creep of the cellulose network. Combined with two-plug-one-injection, grouting and secondary grouting, it can reduce the cross-sectional area of ​​cracks by ≥90% and maintain the gas extraction seal.

[0016] This invention provides a grouting and sealing material and a grouting and sealing method thereof. The grouting and sealing material, by weight, is made from the following raw materials: 30-50 parts of a skeleton component, 15-30 parts of a reinforcing component, 2-10 parts of a state-regulating component, 8-20 parts of a state-stabilizing component, and 0.2-2 parts of an anti-corrosion and antibacterial component. The raw materials do not contain cement, polyurethane prepolymer, or isocyanate curing agents.

[0017] The following details the material composition and mechanism of action, performance testing methods, material examples, method examples, comparative examples, and performance results.

[0018] I. Material composition and mechanism of action 1. Skeletal components The skeleton component is a mixture of modified hydroxypropyl methylcellulose (modified HPMC) and nanocellulose in a mass ratio of 2:1 to 4:1.

[0019] The modified HPMC has a degree of substitution of 1.0 to 2.0, and its 3% aqueous solution has a viscosity of 200,000 to 250,000 mPa·s at 25°C. This viscosity range is an important parameter of this invention. If the viscosity is too high, for example, 300,000 mPa·s, the apparent viscosity of the slurry is too high at a water-to-material ratio of 20:1 to 35:1, making stirring and grouting difficult; if the viscosity is too low, the gel network strength is insufficient. This invention has determined through extensive experiments that when the viscosity of the 3% aqueous solution at 25°C is 200,000 to 250,000 mPa·s, the slurry at different water-to-material ratios at 25°C and a shear rate of 10 s⁻¹ is suitable for grouting. -1 The apparent viscosity of all samples was less than 50 mPa·s. For example, when the viscosity of the modified HPMC 3% aqueous solution was 210000, 220000, 230000, and 240000 mPa·s, the apparent viscosity of the slurry at water-to-material ratios of 20:1, 25:1, 30:1, and 35:1 was shown in Table 1.

[0020] Table 1. Apparent viscosity of slurry at different HPMC viscosities and water-to-material ratios (25℃, 10 s⁻¹) -1 )

[0021] As shown in Table 1, the apparent viscosity of all combinations is less than 50 mPa·s.

[0022] The nanocellulose particles have a diameter of 10–100 nm and are pre-dispersed with sodium carboxymethyl cellulose (CMC) at a mass ratio of 1:10 to 1:3. Nanocellulose has a large specific surface area and is prone to agglomeration; without pre-dispersion, the gel is uneven, and its mechanical and self-healing properties decrease. The pre-dispersion method is dry powder premixing. The dispersion degree of the pre-dispersed nanocellulose can be characterized by a laser particle size analyzer and SEM. For example, the average particle size of the undispersed nanocellulose agglomerates is >5 μm, while the average particle size after pre-dispersion is <200 nm, and no sedimentation occurs after 24 h. CMC pre-dispersion has no significant adverse effect on the slurry pH, gel time, or gel strength; data are shown in Table 2.

[0023] Table 2 Effect of CMC predispersion on slurry properties

[0024] 2. Reinforcing and strengthening components The reinforcing components are modified silica, superabsorbent resin, calcium lactate, magnesium oxide and silane coupling agent in a mass ratio of (5~8):(3~6):(2~4):(1~3):(0.5~1.5).

[0025] The modified silica is fumed silica modified with silane coupling agent KH550, with a specific surface area of ​​100~300 m². 2 / g, particle size 10~50 nm. After hydrolysis, KH550 condenses with hydroxyl groups on the surface of silica, improving its compatibility with organic networks.

[0026] The superabsorbent polymer (SAP) is sodium polyacrylate (SPA). It has a water absorption ratio of 100–1000 g / g in deionized water and 30–300 g / g in a 0.9 wt% NaCl aqueous solution, with a particle size of 50–200 mesh. The 0.9 wt% NaCl aqueous solution simulates well water quality. The testing method is the tea bag method: 1.0 g of SAP is weighed, placed in a non-woven bag, and immersed in deionized water or a 0.9 wt% NaCl aqueous solution. After 7 days, it is removed, drained until no water droplets remain, weighed, and the water absorption ratio is calculated. For example, one type of SPA has a water absorption ratio of 500 g / g in deionized water and 120 g / g in a 0.9 wt% NaCl aqueous solution; another type of SPA has a water absorption ratio of 800 g / g in deionized water and 200 g / g in a 0.9 wt% NaCl aqueous solution. If SAP absorbs less than 30 g / g of water in 0.9 wt% NaCl, its self-healing expansion is insufficient.

[0027] Calcium lactate provides Ca 2+ Magnesium oxide provides Mg 2+ It also adjusts the alkalinity, and the silane coupling agent is at least one of KH550, KH560, and KH570 to enhance the inorganic-organic interface bonding.

[0028] 3. State-regulating components The state-conditioning components are citric acid, sodium citrate, borax and sodium dodecylbenzenesulfonate compounded in a mass ratio of (0.5~1.5):(1~3):(1~4):(0.5~2), and the state-conditioning components make the pH of the slurry after the material is mixed with water in a mass ratio of 1:25~1:35 7.5~9.5.

[0029] Citric acid / sodium citrate forms a buffer system to control the pH of the slurry. Borax forms borate ester bonds with polyvinyl alcohol under alkaline conditions. The characteristic absorption peak of the borate ester bonds (approximately 1350 cm⁻¹) can be observed by Fourier transform infrared spectroscopy (FTIR). -1 and 670cm -1When the pH is below 7.5, borax cross-linking is insufficient, resulting in a gel time >180 min and a gel viscosity <100,000 mPa·s; when the pH is between 7.5 and 9.5, the gel time is 5–120 min and the gel viscosity >200,000 mPa·s; when the pH is above 9.5, the preservative and antibacterial components may be unstable. For example, with 0.8 parts citric acid, 2.0 parts sodium citrate, 2.5 parts borax, and 0.5 parts sodium dodecylbenzenesulfonate, the slurry pH is 8.3, the gel time is 45 min, and the gel viscosity is 225,000 mPa·s.

[0030] 4. Stable components The stable components are modified lithium magnesium silicate, polyvinyl alcohol powder, modified organobentonite, sodium alginate and organosilicon defoamer in a mass ratio of (3~8):(2~6):(2~6):(1~4):(0.2~1).

[0031] The modified organo-bentonite is a quaternary ammonium salt modified bentonite with an interlayer spacing of 1.5–2.5 nm. The modification method is as follows: sodium-based montmorillonite is dispersed in water, a quaternary ammonium salt (such as dioctadecyl dimethyl ammonium chloride) is added, and the mixture is stirred at 60–80 °C for 2–4 h. After filtration, washing, and drying, organo-bentonite is obtained. The interlayer spacing is determined by XRD; a (001) diffraction peak appears at 2θ in the 3–7° range. The interlayer spacing is calculated according to the Bragg equation. For example, the interlayer spacing of unmodified montmorillonite is 1.2 nm, while that of modified bentonite is 1.8 nm, 2.0 nm, and 2.3 nm. The organo-bentonite with an interlayer spacing of 1.5–2.5 nm disperses well in water-based slurries, improving the slurry's water retention and stability.

[0032] 5. Antiseptic and antibacterial components The antiseptic and antibacterial components are potassium sorbate and natamycin in a mass ratio of 1:1 to 3:1, which inhibits the growth of microorganisms in the well.

[0033] 6. Particle size, moisture content, and absence of components Each raw material has a moisture content of less than 1%, a particle size distribution (D90) ≤ 120 μm, and can pass through a 100-mesh sieve. The pulverizing and sieving process is as follows: each raw material is dried to a moisture content of <1%, pulverized using a pulverizer, and passed through a 100-300 mesh sieve. The portion passing through the 100-mesh sieve is then collected. The particle size distribution is determined using a laser particle size analyzer; for example, D10 = 15 μm, D50 = 45 μm, and D90 = 110 μm.

[0034] The raw materials do not contain cement, polyurethane prepolymer, or isocyanate curing agents. Testing method: Take a small amount of powder or gel and test it using FTIR. If it is within 2270 cm⁻¹... -1If there are no absorption peaks of NCO groups nearby, then it does not contain isocyanates; if there are no exothermic peaks of polyurethane curing at 100~150℃ using DSC detection, then it does not contain polyurethane prepolymer; if there are no diffraction peaks attributable to cement clinker minerals using XRD detection, then it does not contain cement.

[0035] II. Performance Testing Methods Gel time: The slurry is placed in a constant temperature water bath at 25℃ and measured using the inverted cup method. The slurry is considered gelled when it no longer flows.

[0036] Viscosity: measured using a rotational rheometer at 25°C and a shear rate of 1 s. -1 or 10 s -1 Record the apparent viscosity.

[0037] 28-day volume shrinkage rate: The gel was prepared into cylindrical samples and cured for 28 days at 25°C and 60% relative humidity. The volume change was measured by the water displacement method.

[0038] Fracture strain: The gel was made into a cylindrical specimen and subjected to triaxial compression test under a confining pressure of 0~5MPa and a loading rate of 0.5 mm / min. The stress-strain curve was recorded and the fracture strain was calculated.

[0039] SAP water absorption ratio: tea bag method, deionized water or 0.9 wt% NaCl aqueous solution, 7 days.

[0040] Self-healing: Secondary cracks are pre-fabricated in the sealing body, relative humidity is controlled, and the cross-sectional area reduction rate of the cracks is calculated by CT or microscopic observation after 8 days.

[0041] XRD Rietveld refinement: Take the refined product, grind to <10μm, Cu target, 2θ 10~80°, step size 0.02°, use Rietveld refinement to quantify the mass fraction of CaCO3 and CaSiO3.

[0042] III. Material Examples To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0043] Example 1

[0044] By weight: 40 parts of skeleton component, including 30 parts of modified HPMC (degree of substitution 1.4, viscosity of 230,000 mPa·s at 25℃ for 3% aqueous solution), and 10 parts of nanocellulose (particle size 50 nm, pre-dispersed with CMC, CMC:nanocellulose = 1:5); 22 parts of reinforcing component, including 8 parts of KH550 modified fumed silica (specific surface area 200 m²).2 / g, particle size 20 nm), 5 parts sodium polyacrylate (deionized water absorption rate 500 g / g, 0.9% NaCl water absorption rate 120 g / g, particle size 100 mesh), 4 parts calcium lactate, 3 parts magnesium oxide, 1.5 parts KH550; 6 parts state conditioning components, including 1 part citric acid, 2 parts sodium citrate, 2.5 parts borax, 0.5 parts sodium dodecylbenzenesulfonate; 15 parts state stabilizing components, including 5 parts modified lithium magnesium silicate, 4 parts polyvinyl alcohol powder, 4 parts quaternary ammonium salt modified bentonite (interlayer spacing 2.0 nm), 2 parts sodium alginate, 0.5 parts organosilicon defoamer; 0.5 parts antiseptic and antibacterial components, including 0.3 parts potassium sorbate, 0.2 parts natamycin.

[0045] Preparation: Dry all raw materials to a moisture content of <1%, pulverize and pass through a 100-mesh sieve, and mix. Mix with water at a ratio of 30:1, resulting in a slurry pH of 8.5. Gelation time: 45 min. Gelation temperature: 25℃, 1 s. -1 With a viscosity of 225,000 mPa·s, a 28-day shrinkage of 0.2%, a fracture strain of 12%, and an expansion of 45 g / g of SAP in 0.9% NaCl over 7 days, the SAP exhibits a shrinkage of 0.2%.

[0046] Example 2

[0047] The skeleton component consists of 35 parts, including 25 parts of modified HPMC (degree of substitution 1.2, viscosity 15000 mPa·s) and 10 parts of nanocellulose (particle size 30 nm, CMC:nanocellulose = 1:8); the reinforcing component consists of 20 parts, including 7 parts of modified silica, 5 parts of sodium polyacrylate (0.9% NaCl water absorption ratio 80 g / g), 3 parts of calcium lactate, 3 parts of magnesium oxide, and 1 part of KH560; the state-regulating component consists of 5 parts, including 0.8 parts of citric acid, 1.8 parts of sodium citrate, 2 parts of borax, and 0.4 parts of sodium dodecylbenzenesulfonate; the state-stabilizing component consists of 12 parts, including 4 parts of modified lithium magnesium silicate, 3 parts of polyvinyl alcohol powder, 3 parts of modified bentonite (interlayer spacing 1.8 nm), 1.5 parts of sodium alginate, and 0.5 parts of defoamer; and the antiseptic and antibacterial component consists of 0.4 parts.

[0048] The slurry pH was 8.2, the gel time was 30 min, the gel viscosity was 236667 mPa·s, the shrinkage was 0.3% after 28 days, the fracture strain was 15%, and the expansion after 7 days with SAP 0.9% NaCl was 60 g / g.

[0049] Example 3

[0050] Based on Example 1, the reinforcing components further include 1.5 parts sodium gluconate and 1.5 parts potassium aluminum sulfate, in a mass ratio of 1:1. Sodium gluconate has a positive effect on Fe... 3+ The chelation constant is high, and it has a high affinity for Ca. 2+The chelation constant is low (log K approximately 1.5), which does not significantly affect the Ca provided by calcium lactate. 2+ Potassium aluminum sulfate forms microcrystals within the gel, and its characteristic peaks can be detected by XRD. The slurry pH was 8.3, the gelation time was 50 min, the gel viscosity was 300,000 mPa·s, the shrinkage after 28 days was 0.25%, the fracture strain was 13%, and the expansion after 7 days in SAP 0.9% NaCl was 48 g / g. The remediation product contained 42% CaCO3, 23% CaSiO3, and a total of 65%.

[0051] Example 4

[0052] The skeleton component consists of 30 parts, including 20 parts of modified HPMC (degree of substitution 1.0, viscosity 5000 mPa·s) and 10 parts of nanocellulose (particle size 10 nm, CMC:nanocellulose = 1:10); the reinforcing component consists of 15 parts, including 5 parts of modified silica (specific surface area 100 m²). 2 / g, particle size 10 nm), 3 parts sodium polyacrylate (deionized water absorption rate 100 g / g, 0.9% NaCl water absorption rate 30 g / g, particle size 50 mesh), 2 parts calcium lactate, 1 part magnesium oxide, 0.5 parts KH550; 2 parts state conditioning components, 0.5 parts citric acid, 1 part sodium citrate, 1 part borax, 0.5 parts sodium dodecylbenzenesulfonate; 8 parts state stabilizing components, 3 parts modified lithium magnesium silicate, 2 parts polyvinyl alcohol powder, 2 parts modified bentonite (interlayer spacing 1.5 nm), 1 part sodium alginate, 0.2 parts defoamer; 0.2 parts antiseptic and antibacterial components, 0.1 parts potassium sorbate, 0.1 parts natamycin.

[0053] The slurry pH was 7.8, the gel time was 120 min, the gel viscosity was 210000 mPa·s, the shrinkage was 0.5% after 28 days, the fracture strain was 10%, and the expansion after 7 days with SAP 0.9% NaCl was 30 g / g.

[0054] Example 5

[0055] The skeleton component consists of 50 parts, including 40 parts of modified HPMC (degree of substitution 2.0, viscosity 50000 mPa·s) and 10 parts of nanocellulose (particle size 100 nm, CMC:nanocellulose = 1:3); the reinforcing component consists of 30 parts, including 8 parts of modified silica (specific surface area 300 m²). 2 / g, particle size 50 nm), 6 parts sodium polyacrylate (deionized water absorption rate 1000 g / g, 0.9% NaCl water absorption rate 300 g / g, particle size 200 mesh), 4 parts calcium lactate, 3 parts magnesium oxide, 1.5 parts KH570; 10 parts state conditioning components, 1.5 parts citric acid, 3 parts sodium citrate, 4 parts borax, 2 parts sodium dodecylbenzenesulfonate; 20 parts state stabilizing components, 8 parts modified lithium magnesium silicate, 6 parts polyvinyl alcohol powder, 6 parts modified bentonite (interlayer spacing 2.5 nm), 4 parts sodium alginate, 1 part defoamer; 2 parts antiseptic and antibacterial components, 1.5 parts potassium sorbate, 0.5 parts natamycin.

[0056] The slurry pH was 9.2, the gel time was 5 min, the gel viscosity was 250,000 mPa·s, the shrinkage was 0.1% after 28 days, the fracture strain was 18%, and the expansion after 7 days with SAP 0.9% NaCl was 280 g / g.

[0057] IV. Method Examples Example 6

[0058] The material used in Example 1 was employed. Step (1) Each raw material was dried until its moisture content was less than 1%, pulverized through a 100-300 mesh sieve, and mixed to obtain a complete powder. Step (2) The complete powder was mixed with water at a mass ratio of 1:32, stirred for 5 minutes to obtain the first slurry, and then heated at 25°C for 10 seconds. -1 The initial viscosity was 20 mPa·s. The powder was mixed with water at a mass ratio of 1:24 and stirred for 5 min to obtain the second slurry with an initial viscosity of 35 mPa·s. The viscosity of the second slurry was higher than that of the first slurry. Step (3) Plugs were set at both ends of the sealing section, and the first slurry was injected using a two-plug-one-injection process with an injection pressure of 2.5 MPa to allow the first slurry to penetrate into the 1~500 μm fissures around the borehole. Step (4) The second slurry was injected through the slurry injection pipe with an injection pressure of 0.4 MPa to allow the first slurry to continue to drive into the fissures and fill the sealing section under pressure. Step (5) The slurry in the sealing section was allowed to react under pressure for 50 min to form a gel sealing body. The mixture was then heated at 25℃ for 1 s. -1 Viscosity 225000 mPa·s. Step (6) During the extraction process, when the extraction concentration drops by more than 20% from the initial concentration, or the absolute extraction concentration is less than 30%, secondary grouting is carried out through the grouting pipe. The grouting pressure is 0.4 MPa and the water-to-material ratio for secondary grouting is 24:1.

[0059] Example 7

[0060] The width of the cracks around the sealing section was observed to be less than 0.5 mm. The water-to-material ratio of the first grout was 34:1, and the grouting pressure was 3 MPa. The penetration depth reached 320 μm. The replenishment grouting pressure was 0.4 MPa. When the pressure rise rate during grouting exceeded 0.5 MPa / min, the grouting pressure was reduced to 70% of the original pressure at a rate of 0.2 MPa / min. The extraction concentration retention rate after sealing was 95%.

[0061] Example 8

[0062] The fracture width was 1.2 mm. The water-to-material ratio of the first grout was 32:1, and the grouting pressure was 2 MPa. The penetration depth reached 450 μm. The replenishment pressure was 0.5 MPa. The pressure rise rate was controlled in the same way as in Example 7. The concentration retention rate after sealing was 93%.

[0063] Example 9

[0064] The fracture width was 3.0 mm. The water-to-material ratio of the first grout was 29:1, and the grouting pressure was 1.2 MPa. The subsequent grouting pressure was 0.6 MPa. The grout did not leak in the wide fracture and maintained pressure to ensure complete filling. The concentration retention rate after sealing was 90%.

[0065] Example 10

[0066] The material from Example 3 was used. The relative humidity of the sealing section was 70%. The secondary crack width was 1.2 mm. After 8 days, the crack cross-sectional area decreased by 93%. XRD Rietveld refinement: the repair product contained 45% CaCO3, 22% CaSiO3, and 67% total CaCO3. Sodium gluconate was used to treat CaCO3. 2+ The chelation is weak and does not affect CaCO3 mineralization.

[0067] Example 11

[0068] Relative humidity 65%. Secondary crack width 1.0 mm. Crack cross-sectional area reduction rate 90% after 8 days. Repair products consist of 40% CaCO3, 21% CaSiO3, and 61% total.

[0069] Example 12

[0070] use Figure 1 The device consists of two primary grouting bags 2 and an intermediate secondary grouting bag 3 fitted onto the extraction pipe 1. The grouting pipe 4 connects to the primary bags, the grouting supply pipe 5 connects to the secondary bags, and the other end of the grouting supply pipe connects to the grout storage tank 6. The grout storage tank is connected to the downhole ventilation pipe 9, and a pressure of 0.4 MPa is applied through the pressure reducing valve 7 and the pressure stabilizing tank 8, with a pressure fluctuation of ±0.03 MPa. The volume of the pressure stabilizing tank is 20% of that of the grout storage tank. In step (3), the grouting pressure is 0.7 MPa, and the bag bursting pressure is 0.93 MPa (1.33 times), not lower than 0.6 MPa. The bags do not burst during grouting, and the secondary bags burst as needed during grouting. The bag material is rubber.

[0071] V. Comparative Examples Comparative Example 1 (Undispersed nanocellulose) Compared to Example 1, the nanocellulose was not pre-dispersed with CMC. As a result, the nanocellulose agglomerated, the gel was uneven, the fracture strain was 6%, the 28-day shrinkage was 0.9%, and the self-healing crack cross-sectional area reduction rate was 60% after 8 days.

[0072] Comparative Example 2 (HPMC viscosity too high) Compared to Example 1, the viscosity of the modified HPMC 3% aqueous solution is 100,000 mPa·s. The initial viscosity of the slurry is >200 mPa·s, making grouting difficult.

[0073] Comparative Example 3 (pH too low) Compared to Example 1, the state-conditioning component resulted in a slurry pH of 5.5. Insufficient borax crosslinking led to a gel time >180 min, gel viscosity <100,000 mPa·s, fracture strain of 8%, and a 65% reduction in cross-sectional area of ​​the self-healing crack after 8 days.

[0074] Comparative Example 4 (Cement-based Sealing Material) Cement-based sealing material. 28-day shrinkage of 1.5%, brittle fracture, no self-healing, and rapid decrease in pump concentration.

[0075] Comparative Example 5 (grouting pressure below 0.3 MPa) Compared to Example 6, the slurry replenishment pressure was 0.2 MPa. The slurry replenishment displacement effect was insufficient, the sealing section was not densely filled, and the extraction concentration retention rate was only 75%.

[0076] VI. Performance Results Table 3 Summary of the performance of material examples

[0077] Table 4 Sealing effect of method examples

[0078] Table 5 Self-healing and mineralization results

[0079] As can be seen from the above embodiments, comparative examples, and Tables 3, 4, and 5, the grouting and sealing material of the present invention, under conditions without cement, polyurethane prepolymer, or isocyanate curing agents, achieves controllable gelation time, high viscosity, low shrinkage, high toughness, and self-healing ability through the synergistic effect of modified HPMC, CMC pre-dispersed nanocellulose, modified silica, sodium polyacrylate, and state-regulating and state-stabilizing components. The method, through stepwise injection of the first and second grouts, grout replenishment and pressure maintenance, secondary grout replenishment, and CO2 mineralization, significantly improves the sealing effect of gas drainage boreholes.

[0080] The applicant declares that the present invention is illustrated through the above embodiments to describe the detailed products and methods of the present invention, but the present invention is not limited to the detailed products and methods described above, that is, it does not mean that the present invention must rely on the detailed products and methods described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the products of the present invention, additions to auxiliary structures, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A grouting and sealing material, characterized in that, By weight, it is made from the following raw materials: 30-50 parts of skeleton component, 15-30 parts of reinforcing component, 2-10 parts of state conditioning component, 8-20 parts of state stabilizing component, and 0.2-2 parts of antiseptic and antibacterial component. The raw materials of the grouting and sealing material do not contain cement, polyurethane prepolymer, or isocyanate curing agents. The skeleton component is a mixture of modified hydroxypropyl methylcellulose and nanocellulose in a mass ratio of 5:1 to 10:1, and the viscosity of a 3% aqueous solution at 25°C is 200,000 to 250,000 mPa·s. The nanocellulose is pre-dispersed with sodium carboxymethyl cellulose, and the mass ratio of sodium carboxymethyl cellulose to nanocellulose is 1:10 to 1:

3. The reinforcing components are modified silica, superabsorbent resin, calcium lactate, magnesium oxide and silane coupling agent compounded in a mass ratio of (5~8):(3~6):(2~4):(1~3):(0.5~1.5). The modified silica is fumed silica modified with silane coupling agent KH550, and the superabsorbent resin is sodium polyacrylate with a water absorption ratio of 30~300 g / g in 0.9 wt% NaCl aqueous solution. The state-conditioning component is a compound of citric acid, sodium citrate, borax and sodium dodecylbenzenesulfonate in a mass ratio of (0.5~1.5):(1~3):(1~4):(0.5~2), and the state-conditioning component makes the pH of the slurry after the material is mixed with water in a mass ratio of 1:25~1:35 7.5~9.

5. The stable components are modified magnesium lithium silicate, polyvinyl alcohol powder, modified organic bentonite, sodium alginate and organosilicon defoamer compounded in a mass ratio of (3~8):(2~6):(2~6):(1~4):(0.2~1), and the modified organic bentonite is quaternary ammonium salt modified bentonite. The antiseptic and antibacterial component is a mixture of potassium sorbate and natamycin in a mass ratio of 1:1 to 3:

1.

2. The grouting and sealing material according to claim 1, characterized in that, The moisture content of each raw material component of the grouting and sealing material is less than 1%, the particle size D90 is ≤120μm and can pass through a 100-mesh sieve.

3. The grouting and sealing material according to claim 1, characterized in that, The degree of substitution of the modified hydroxypropyl methylcellulose is 1.0~2.0, the particle size of the nanocellulose is 10~100 nm, and the specific surface area of ​​the modified silica is 100~300 m². 2 / g, with a particle size of 10~50 nm, the superabsorbent resin has a particle size of 50~200 mesh, and a water absorption ratio of 100~1000 g / g in deionized water, the silane coupling agent is at least one of KH550, KH560, and KH570, and the interlayer spacing of the modified organobentonite is 1.5~2.5 nm.

4. The grouting and sealing material according to claim 1, characterized in that, The grouting and sealing material is mixed with water at a mass ratio of 1:25 to 1:35, and a gel is formed within 5 to 120 minutes. When secondary cracks occur, the superabsorbent resin absorbs water and expands under the condition of relative humidity ≥60% in the sealing section, and works in conjunction with the creep of the cellulose network to adaptively fill the secondary cracks. The gel is subjected to a shear rate of 1 s at 25°C. -1 The viscosity is greater than 200,000 mPa·s, the volume shrinkage rate after 28 days is ≤0.5%, and the fracture strain of the gel is ≥10% under a confining pressure of 0~5 MPa and a loading rate of 0.5 mm / min. The superabsorbent resin exhibits a water absorption swelling ratio of ≥30 g / g after 7 days in a 0.9 wt% sodium chloride aqueous solution.

5. The grouting and sealing material according to claim 1, characterized in that, The reinforcing component further includes a metal complexing agent and a crystallizing agent, wherein the mass ratio of the metal complexing agent to the crystallizing agent is 1:0.5 to 1:2, wherein the metal complexing agent is sodium gluconate and the crystallizing agent is potassium aluminum sulfate.

6. A grouting sealing method for sealing gas extraction boreholes, characterized in that, include: (1) Dry each raw material separately until the moisture content is less than 1%, crush it through a 100-300 mesh sieve, and mix them to obtain a whole powder; (2) Mix the whole powder with water at a mass ratio of 1:28 to 1:35 and stir for 3 to 10 minutes to obtain the first slurry. Mix the whole powder with water at a mass ratio of 1:20 to 1:27 and stir for 3 to 10 minutes to obtain the second slurry. The first and second slurries are heated at 25°C and a shear rate of 10 s. -1 The initial viscosity of the first slurry is less than 50 mPa·s, and the viscosity of the second slurry is higher than that of the first slurry. (3) Install plugs at both ends of the sealing section and inject the first grout using a two-plug-one-injection process with a grouting pressure of 0.5~2MPa, so that the first grout can penetrate into the 1~500μm fissures around the borehole. (4) Inject the second grout through the grouting pipe at a grouting pressure of 0.1~0.3MPa to drive the first grout into the crack and maintain pressure and fill the hole in the sealing section; (5) Allow the slurry in the sealing section to react under pressure for 5 to 120 minutes to form a sealing body with gel as described in claim 2; (6) During the extraction process, when the extraction concentration drops by more than 20% from the initial concentration, or the absolute extraction concentration is less than 30%, secondary grouting is carried out through the grouting pipe. The grouting pressure is 0.1~0.3MPa, and the water-to-material ratio of the secondary grouting is 20:1~27:

1.

7. The grouting and sealing method according to claim 6, characterized in that, Step (3) also includes observing the width of the cracks around the sealing section and the effective sealing length, specifically including: When the width is less than 0.5 mm and the length of the sealing section is 8 m, the water-to-material ratio of the first grout is 32:1 to 35:1, and the grouting pressure is 0.6 to 0.8 MPa. When the width is 0.5~2.0 mm and the length of the sealing section is 8~12 m, the water-to-material ratio of the first grout is 30:1~33:1 and the grouting pressure is 0.8~1.2 MPa; When the width is greater than 2.0 mm and the length of the sealing section is greater than 12 m, the water-to-material ratio of the first grout is 28:1 to 30:1, and the grouting pressure is 1.2 to 1.5 MPa. The grouting pressure in steps (4) and (6) is 0.1~0.3MPa; During the grouting process, when the pressure rise rate is >0.5MPa / min, the grouting pressure is reduced to 50%~80% of the original pressure, and the reduction rate is 0.1~0.3 MPa / min.

8. The grouting and sealing method according to claim 6, characterized in that, The grouting and sealing material is the grouting and sealing material as described in claim 3. In steps (5) and (6), the relative humidity of the sealing section is controlled to be ≥60%, so that the total mass of calcium carbonate and calcium silicate in the repair products generated in the secondary crack is ≥60%. When the width of the secondary crack is ≤1.5 mm, the crack cross-sectional area reduction rate is ≥90% within 8 days. The total mass is quantified by XRD Rietveld precision finishing.

9. The grouting and sealing method according to claim 6, characterized in that, A three-bag sealing device with a through-hole design is adopted, including two primary grouting bags at both ends of the sealing section and a secondary grouting bag in the middle. The grouting pipe is connected to the primary grouting bag, the first end of the grouting pipe is connected to the secondary grouting bag, and the second end is connected to the grout storage tank. The grout storage tank is connected to the downhole ventilation pipe. A pressure of 0.2~0.6MPa is applied to the grout in the grout storage tank through a pressure reducing valve and a pressure stabilizing tank, with a pressure fluctuation of ±0.05MPa. The bursting pressure of the bladder is 1.2 to 2 times the grouting pressure in step (3), and not less than 0.6 MPa; The volume of the pressure stabilizing tank is 10% to 30% of the volume of the slurry storage tank.

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