A pulping agent and its application

Abstract

The present invention provides a slurrying agent and its application, which relates to the technical field of working fluid for tunnel engineering. The slurrying agent provided by the present invention comprises the following components in parts by weight: 30-40 parts of bentonite, 9-12 parts of dispersant, 0.1-0.3 parts of thickener, 0.5-1 parts of salt-resistant agent, and 1-2 parts of chelating agent. 2+ Mg 2+ Mud stability is critical, and chelating agents and salt-reducing agents, combined with divalent cations, enhance the suspension stability of clay particles in high-salinity seawater or groundwater. The slurrying agent provided by this invention can be used to prepare mud with good suspension stability and moderate viscosity in high-salinity marine environments and groundwater containing divalent cations, making it suitable for use in diverse formation environments.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering working fluids, and in particular to a slurrying agent and application thereof. Background Art

[0002] In recent years, with the development of coastal areas into underground spaces, cross-sea tunnel projects have been increasing. The slurry shield method has been gradually adopted in tunnel construction in areas with complex hydrogeological conditions, especially in the construction of cross-river and cross-sea tunnels, due to its safety, high efficiency, and superior pressure control mode. The core of the slurry shield method is to prepare suitable mud to form a layer of slightly permeable mud film on the excavation surface stratum, so that the mud water pressure can effectively balance the water / soil pressure of the stratum to maintain the stability of the excavation surface. Mud water, also known as slurry, is generally a suspended dispersion composed of natural clay such as bentonite, admixtures and water. For submarine tunnels, due to the micro-permeability of the mud film during shield excavation, seawater will inevitably seep into the mud water compartment. Due to the high salt concentration of seawater, especially the Ca contained in it 2+ Mg 2+ Divalent cations such as ions can severely weaken the suspension stability of clay particles in the mud, causing stratification and flocculation, which can degrade mud performance. Therefore, when using slurry shield construction in marine environments, overcoming the adverse effects of seawater intrusion or groundwater on the mud and mud film properties is crucial for maintaining excavation face stability, ensuring construction safety, and advancing project progress.

[0003] Due to the high salinity of seawater, current slurrying agents used in marine slurry shield construction primarily incorporate various inorganic or organic dispersants (such as sodium hexametaphosphate, sodium silicate, and polycarboxylates / polyacrylates), supplemented by thickeners (such as bio-colloids such as guar gum and xanthan gum, polyacrylamide, carboxymethyl cellulose, and white carbon black). The working principle of these slurrying agent components is that dispersants enhance the electrostatic / steric repulsion between clay particles, while thickeners increase the liquid viscosity to prevent flocculation and sedimentation due to electrostatic forces / gravity. However, even a slight increase in the concentration of divalent cations in seawater significantly reduces the surface zeta potential of clay particles and forms bridges between anionic polymers, promoting flocculation. Furthermore, divalent cations can cause polymers such as sodium carboxymethyl cellulose and xanthan gum to agglomerate, affecting the effectiveness of thickeners. In particular, when a shield tunnel passes through a marine composite stratum, it will experience a stratigraphic change from soft soil layer to hard rock section to soft soil layer. If the amount of thickener is simply increased to ensure mud stability, construction will become difficult in some stratum environments due to a sharp increase in mud viscosity.

[0004] Therefore, there is an urgent need in this field to develop a special slurrying agent that can produce mud with good suspension stability and moderate viscosity in a high-salt environment, especially in groundwater in a marine environment with a high concentration of divalent cations. Summary of the Invention

[0005] The purpose of the present invention is to provide a slurrying agent and its application, which can effectively improve the suspension stability of groundwater prepared slurry in marine environment, and is particularly suitable for groundwater or seawater containing high concentrations of Ca 2+ Mg 2+ The risk of seawater infiltration during slurry shield construction can be effectively reduced.

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

[0007] The invention provides a pulping agent, which comprises the following components in parts by weight: 30-40 parts of bentonite, 9-12 parts of dispersant, 0.1-0.3 parts of thickener, 0.5-1 parts of salt-resistant agent and 1-2 parts of chelating agent.

[0008] Preferably, the density of the bentonite is 2.3-2.5 g / cm 3 , loss on ignition ≤18%.

[0009] Preferably, the dispersant comprises an inorganic dispersant and / or sodium silicate.

[0010] Preferably, the thickener comprises sodium carboxymethylcellulose and / or xanthan gum.

[0011] Preferably, the anti-salt agent is an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution.

[0012] Preferably, the preparation method of the acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution comprises:

[0013] Acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, water, NaOH solution and initiator are mixed to carry out free radical polymerization reaction to obtain acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution.

[0014] Preferably, the chelating agent comprises EDTA and / or EDTA disodium.

[0015] The present invention provides the application of the slurrying agent described in the above technical solution in a slurry shield construction method in a marine environment.

[0016] Preferably, the application method comprises:

[0017] The chelating agent and groundwater from a marine environment are mixed to obtain solution A;

[0018] Mixing the solution A and a thickener to obtain a solution B;

[0019] The solution B is mixed with an anti-salt agent, a dispersant and bentonite to obtain slurry.

[0020] Preferably, the salt concentration of the groundwater in the marine environment is 0.9-1.5 wt%; the concentration of divalent cations in the groundwater in the marine environment is 5-30 mmol / L.

[0021] The present invention provides a slurrying agent, which comprises the following components in parts by weight: 30-40 parts of bentonite, 9-12 parts of dispersant, 0.1-0.3 parts of thickener, 0.5-1 parts of salt-resistance agent, and 1-2 parts of chelating agent. 2+ Mg 2+ Mud stability is critical, and chelating agents and salt-reducing agents, combined with divalent cations, enhance the suspension stability of clay particles in high-salinity seawater or groundwater. The slurrying agent provided by this invention can be used to prepare mud with good suspension stability and moderate viscosity in high-salinity marine environments and groundwater containing divalent cations, making it suitable for use in diverse formation environments. DETAILED DESCRIPTION

[0022] The invention provides a pulping agent, which comprises the following components in parts by weight: 30-40 parts of bentonite, 9-12 parts of dispersant, 0.1-0.3 parts of thickener, 0.5-1 parts of salt-resistant agent and 1-2 parts of chelating agent.

[0023] In parts by weight, the slurrying agent provided by the present invention comprises 30 to 40 parts of bentonite, preferably 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts or 40 parts. In the present invention, the density of the bentonite is preferably 2.3 to 2.5 g / cm 3 , the loss on ignition is preferably ≤18%. In the present invention, the bentonite is preferably sodium bentonite.

[0024] Based on the weight of the bentonite, the slurrying agent provided by the present invention includes 9 to 12 parts of a dispersant, and is preferably 9 parts, 10 parts, 11 parts or 12 parts. In the present invention, the dispersant is preferably an inorganic dispersant, and more preferably includes anhydrous sodium carbonate and / or sodium silicate. In the present invention, the purity of the anhydrous sodium carbonate is preferably not less than 99%. In the present invention, the sodium silicate is preferably sodium metasilicate pentahydrate or sodium metasilicate nonahydrate; the purity of the sodium silicate is preferably not less than 99%. In the present invention, the dispersant can effectively prevent the clay particles from stacking on each other to form a "house of cards" structure and produce flocculation and stratification by increasing the pH value of the mud and adsorbing on the edges of the clay particles.

[0025] Based on the weight of the bentonite, the slurrying agent provided by the present invention includes 0.1 to 0.3 parts of a thickener, specifically preferably 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts or 0.3 parts. In the present invention, the thickener preferably includes sodium carboxymethyl cellulose (CMC-Na) and / or xanthan gum. In the present invention, the Brookfield viscosity of a 1wt% aqueous solution of the sodium carboxymethyl cellulose is preferably 1000 to 3000 mPa·s. In the present invention, the Brookfield viscosity of a 1wt% aqueous solution of the xanthan gum is preferably 800 to 1200 mPa·s. In the present invention, the sodium carboxymethyl cellulose in the thickener can increase the characteristic particle size of the clay particles in the mud and enhance the density of the mud film formed; xanthan gum has relatively good salt resistance, and the salt concentration has little effect on the liquid phase viscosity, but the presence of divalent cations will still cause sodium carboxymethyl cellulose or xanthan gum to coagulate.

[0026] Based on the weight of the bentonite, the slurrying agent provided by the present invention includes 0.5 to 1 part of a salt-resistant agent, and specifically preferably 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 1 part. In the present invention, the salt-resistant agent is preferably an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution.

[0027] In the present invention, the method for preparing the acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution preferably comprises:

[0028] Acrylic acid (AA), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), water, a NaOH solution, and an initiator are mixed and subjected to a free radical polymerization reaction to obtain an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution. In the present invention, the purity of the acrylic acid is preferably not less than 99%. In the present invention, the purity of the 2-acrylamido-2-methylpropanesulfonic acid is preferably not less than 98%. In the present invention, the initiator is preferably sodium persulfate or potassium persulfate.

[0029] In the present invention, the mass ratio of the acrylic acid to 2-acrylamido-2-methylpropanesulfonic acid is preferably 30 to 40:100, more preferably 31:100. In the present invention, the mass ratio of the 2-acrylamido-2-methylpropanesulfonic acid to water is preferably 1:2. In the present invention, the concentration of the sodium hydroxide solution is preferably 50wt%. In the present invention, the mass ratio of the initiator to 2-acrylamido-2-methylpropanesulfonic acid is preferably 2 to 3:100, more preferably 2.7:100.

[0030] In the present invention, the mixing of acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, water, NaOH solution, and initiator preferably comprises: dissolving 2-acrylamido-2-methylpropanesulfonic acid in water, adding NaOH solution dropwise until the pH of the solution reaches 10, adding acrylic acid and stirring, and then adding the initiator in a 55°C water bath. In the present invention, the stirring speed is preferably 200 rpm, and the stirring time is preferably 15 minutes.

[0031] In the present invention, the temperature of the free radical polymerization reaction is preferably 70-90°C, more preferably 80°C; the time of the free radical polymerization reaction is preferably 2-4 hours, more preferably 3 hours. In the present invention, the free radical polymerization reaction is preferably carried out under stirring conditions; the stirring speed is preferably 200 r / min.

[0032] In the present invention, after the free radical polymerization reaction, the resulting system is preferably cooled to room temperature and then dialyzed for 24 hours using an ultrafiltration membrane with a molecular weight cutoff of 15,000 to obtain an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution. In the present invention, the acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution preferably has a solids content of 30-40%, more preferably 33%.

[0033] The pulping agent provided by the present invention includes 1 to 2 parts of a chelating agent, preferably 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2 parts, based on the weight of the bentonite. In the present invention, the chelating agent preferably includes ethylenediaminetetraacetic acid (EDTA) and / or disodium ethylenediaminetetraacetate (EDTA-Na2). In the present invention, the purity of the EDTA is preferably not less than 99%; the purity of the disodium ethylenediaminetetraacetate is preferably not less than 99%.

[0034] The present invention combines the salt-repellent and the chelating agent with the Ca in the groundwater of the marine environment. 2+ Mg 2+ , ensuring the effectiveness of thickeners and dispersants, thereby improving the suspension stability of clay particles in groundwater in the marine environment.

[0035] The present invention provides the application of the slurrying agent described in the above technical solution in a slurry shield construction method in a marine environment.

[0036] In the present invention, the method of application preferably includes:

[0037] The chelating agent and groundwater from a marine environment are mixed to obtain solution A;

[0038] Mixing the solution A and a thickener to obtain a solution B;

[0039] The solution B is mixed with an anti-salt agent, a dispersant and bentonite to obtain slurry.

[0040] In the present invention, because thickeners such as sodium carboxymethyl cellulose and xanthan gum have strong hydrophilicity, direct preparation of mud from powders easily forms agglomerates. Therefore, in application, the present invention pre-treats groundwater in a marine environment with a chelating agent, dissolves the thickening agent in a solution containing the chelating agent, and then adds a salt-resistant agent, a dispersant, and bentonite to produce the mud. The present invention adds the resulting mud to a mud pool, and adjusts the specific gravity, viscosity, and water extraction of the mixed mud by adjusting the amount of mud and water added to meet construction requirements under different geological environments.

[0041] The present invention preferably mixes a chelating agent with groundwater from a marine environment to obtain solution A. In the present invention, the salt concentration of the groundwater from the marine environment is preferably 0.9-1.5 wt%; the concentration of divalent cations in the groundwater from the marine environment is preferably 5-30 mmol / L. In a specific embodiment of the present invention, the chemical composition of the groundwater from the marine environment comprises, by weight percentage, 4-5% sodium, 0.1-0.2% potassium, 0.2-0.3% magnesium, 0.5-1.0% calcium, 7-8% chloride, 0.6-0.8% sulfate, and the remainder water. In the present invention, the mass ratio of the chelating agent to the groundwater from the marine environment is preferably 1:20-100, more preferably 1:20-80. In the present invention, the mixing is preferably carried out under stirring; the stirring rate is preferably 800-1000 r / min; and the stirring time is preferably 1-2 minutes. In the present invention, the stirring is preferably carried out using a powerful overhead stirrer.

[0042] After obtaining solution A, the present invention preferably mixes solution A with a thickener to obtain solution B. In the present invention, the mixing is preferably performed under stirring; the stirring rate is preferably 300 to 4000 r / min, more preferably 1000 to 1800 r / min; and the stirring time is preferably 10 to 15 minutes. In the present invention, the stirring is preferably performed using a powerful overhead stirrer.

[0043] After obtaining Solution B, the present invention preferably mixes Solution B with a salt-reducing agent, a dispersant, and bentonite to produce a slurry. In the present invention, the mixing is preferably performed under stirring; the stirring rate is preferably 800 to 1000 rpm; and the stirring time is preferably 3 to 5 minutes. In the present invention, the stirring is preferably performed using a powerful overhead stirrer.

[0044] The present invention adopts a stirring process to enhance the dissolution of thickeners to prepare mud, which can give full play to the effectiveness of thickeners and save the amount of thickeners used. The mud prepared by the present invention is a concentrated mud that can be used after being added to the mud pool and simply stirred, which is convenient for construction.

[0045] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] The bentonite used in the embodiment of the present invention is sodium bentonite with a loss on ignition of ≤18%.

[0047] The anhydrous sodium carbonate used in the embodiments of the present invention is analytically pure with a purity of ≥99.5%.

[0048] The sodium metasilicate pentahydrate used in the embodiments of the present invention has a purity of ≥95%.

[0049] The sodium carboxymethyl cellulose used in the examples of the present invention is USP grade, and the viscosity of a 1 wt % aqueous solution is 1000-3000 mPa·s.

[0050] The xanthan gum used in the examples of the present invention is USP grade, and the viscosity of a 1 wt % aqueous solution is 800-1200 mPa·s.

[0051] The acrylic acid used in the embodiments of the present invention is liquid, contains a trace amount of hydroquinone monomethyl ether polymerization inhibitor, and is not purified when used.

[0052] The 2-acrylamido-2-methylpropanesulfonic acid used in the examples of the present invention is a powder with a purity of 98%.

[0053] The EDTA used in the examples of the present invention is analytically pure with a purity of ≥99.5%.

[0054] The disodium edetate dihydrate used in the embodiments of the present invention has a purity of ≥99%.

[0055] The marine environment groundwater used in the embodiments of the present invention has the following chemical components by weight: sodium 4-5%, potassium 0.1-0.2%, magnesium 0.2-0.3%, calcium 0.5-1.0%, chloride 7-8%, sulfate 0.6-0.8%, and the balance water.

[0056] Example 1

[0057] In parts by weight, the components of the slurrying agent of this embodiment are: 30 parts of bentonite, 9 parts of dispersant, 0.25 parts of thickener, 0.8 parts of salt-resistant agent, and 1.5 parts of chelating agent.

[0058] The dispersant is anhydrous sodium carbonate, the thickener is xanthan gum, the salt-resistant agent is acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution, and the chelating agent is disodium ethylenediaminetetraacetic acid dihydrate.

[0059] The acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is prepared from the raw materials in parts by weight according to the following method:

[0060] 100 parts of 2-acrylamido-2-methylpropanesulfonic acid were dissolved in 200 parts of deionized water, and a NaOH solution prepared from 10 parts of granular NaOH and 10 parts of deionized water was added dropwise to adjust the solution pH to 10. 31 parts of acrylic acid were added to the solution, and the mixture was stirred at 200 r / min for 15 minutes. 2.7 parts of sodium persulfate were added to the solution in a 55°C water bath. The water bath temperature was raised to 80°C, and the mixture was stirred at 200 r / min for 3 hours. After cooling to room temperature, the copolymer solution was dialyzed for 24 hours through an ultrafiltration membrane with a molecular weight cutoff of 15,000 to obtain an acrylic acid / 2-acrylamido-2-methylpropanesulfonic acid copolymer solution with a solid content of 33%.

[0061] Application Example 1

[0062] The slurrying agent of Example 1 is used in a slurry shield in a marine environment, and the steps are as follows:

[0063] (1) mixing the chelating agent with groundwater from a marine environment at a mass ratio of 1:80, and stirring at 800 rpm for 2 minutes using a powerful overhead stirrer to obtain a solution A;

[0064] (2) adding the thickener to solution A and stirring at 1800 rpm for 15 min using a powerful overhead stirrer to obtain solution B;

[0065] (3) The anti-salt agent, dispersant and bentonite were added to solution B and stirred at 1000 r / min for 5 min using a powerful overhead stirrer to obtain a slurry.

[0066] 380 parts by weight of groundwater from a marine environment were weighed and mixed with the mud. The mixture was stirred at 400 rpm for 1 minute using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0067] Example 2

[0068] In parts by weight, the components of the slurrying agent of this embodiment are: 30 parts of bentonite, 9 parts of dispersant, 0.1 parts of thickener, 0.8 parts of salt-resistant agent, and 1.5 parts of chelating agent.

[0069] The dispersant is anhydrous sodium carbonate, the thickener is xanthan gum, the salt-resistant agent is acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution, and the chelating agent is disodium ethylenediaminetetraacetic acid dihydrate.

[0070] The preparation method of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is the same as that in Example 1.

[0071] Application Example 2

[0072] The slurrying agent of Example 2 is used in a mud-water shield in a marine environment, and the steps are the same as those of Application Example 1 to obtain slurry.

[0073] 500 parts by weight of groundwater from a marine environment were weighed and mixed with the mud. The mixture was stirred at 400 rpm for 5 minutes using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0074] Example 3

[0075] In parts by weight, the components of the slurrying agent of this embodiment are: 30 parts of bentonite, 9 parts of dispersant, 0.1 parts of thickener, 1.0 parts of salt-resistant agent, and 1.5 parts of chelating agent.

[0076] The dispersant is sodium metasilicate, the thickener is xanthan gum, the salt-resistant agent is acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution, and the chelating agent is disodium ethylenediaminetetraacetic acid dihydrate.

[0077] The preparation method of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is the same as that in Example 1.

[0078] Application Example 3

[0079] The slurrying agent of Example 3 is used in a mud-water shield in a marine environment, and the steps are the same as those of Application Example 1 to obtain slurry.

[0080] 380 parts by weight of groundwater from a marine environment were weighed and mixed with the mud. The mixture was stirred at 400 rpm for 1 minute using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0081] Example 4

[0082] In parts by weight, the components of the slurrying agent of this embodiment are: 30 parts of bentonite, 9 parts of dispersant, 0.1 parts of thickener, 0.5 parts of salt-resistant agent, and 1.5 parts of chelating agent.

[0083] The dispersant is sodium metasilicate, the thickener is sodium carboxymethyl cellulose, the anti-salt agent is acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution, and the chelating agent is ethylenediaminetetraacetic acid.

[0084] The preparation method of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is the same as that in Example 1.

[0085] Application Example 4

[0086] The slurrying agent of Example 4 is used in a mud-water shield in a marine environment, and the steps are the same as those of Application Example 1 to obtain slurry.

[0087] 380 parts by weight of groundwater from a marine environment were weighed and mixed with the mud. The mixture was stirred at 400 rpm for 1 minute using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0088] Example 5

[0089] In parts by weight, the components of the slurrying agent of this embodiment are: 30 parts of bentonite, 9 parts of dispersant, 0.1 parts of thickener, 0.6 parts of salt-resistant agent, and 1 part of chelating agent.

[0090] The dispersant is anhydrous sodium carbonate, the thickener is xanthan gum, the salt-resistant agent is acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution, and the chelating agent is ethylenediaminetetraacetic acid.

[0091] The preparation method of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is the same as that in Example 1.

[0092] Application Example 5

[0093] The slurrying agent of Example 5 is used in a mud-water shield in a marine environment, and the steps are the same as those of Application Example 1 to obtain slurry.

[0094] 380 parts by weight of groundwater from a marine environment were weighed and mixed with the mud. The mixture was stirred at 400 rpm for 1 minute using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0095] Comparative Example 1

[0096] A commercially available seawater-specific slurrying agent, model HS-1, was used as a control sample. 30 parts by weight of the special slurrying agent were weighed and mixed with 500 parts of marine environmental groundwater. The mixture was stirred at 400 rpm for 5 minutes using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0097] Comparative Example 2

[0098] A commercially available seawater-specific slurrying agent, model HS-3, was used as a control sample. 30 parts by weight of the special slurrying agent were weighed and mixed with 500 parts of marine environmental groundwater. The mixture was stirred at 400 rpm for 5 minutes using a powerful overhead stirrer. The mud properties were tested at room temperature. The results are shown in Table 1.

[0099] Table 1 Mud properties of application examples 1 to 5 and comparative examples 1 to 2

[0100]

[0101] As shown in Table 1, the addition of chelating agents and anti-salt agents in Application Examples 1-5 improved the colloid fraction of the mud, i.e., the mud's stability under gravity. Even at a pressure of 0.25 MPa, the muds in Application Examples 2-5 maintained good stability, with water extraction rates of less than 10% in two hours (based on the 240 mL test mud volume in the application examples).

[0102] Compared with Application Example 1, the 2-hour colloid rate of the mud in Application Example 2 is lower, indicating that the reduction in the amount of thickener used and the reduced efficiency caused by incomplete dissolution have an adverse effect on the stability of the mud.

[0103] Compared with Application Example 2, the 2-hour colloid rate of the mud in Application Example 3 is improved, indicating that the replacement of the dispersant from sodium carbonate to sodium metasilicate and the increase in the amount of anti-salt agent have a positive effect on the stability of the mud.

[0104] Compared with Application Example 1 and Application Example 2, the 2-hour colloid rate of the mud in Application Example 4 and Application Example 5 is further reduced, indicating that the reduction in the amount of anti-salt agent and chelating agent has an adverse effect on the stability of the mud.

[0105] Compared with Application Examples 1 to 5, the 2-hour colloid rate of the mud in Comparative Examples 1 and 2 is very low, indicating that the underground cement slurry prepared with commercially available slurrying agents has poor stability and is not suitable for situations where the concentration of divalent cations in groundwater in marine environments is high.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Application of a slurrying agent in a slurry shield method in a marine environment, characterized in that: The slurrying agent is composed of the following components in parts by weight: 30-40 parts of bentonite, 9-12 parts of dispersant, 0.1-0.3 parts of thickener, 0.5-1 parts of salt-resistant agent, and 1-2 parts of chelating agent; The dispersant includes anhydrous sodium carbonate and / or sodium silicate, and the dispersant can increase the pH value of the mud and be adsorbed on the edges of clay particles; The chelating agent is ethylenediaminetetraacetic acid and / or disodium ethylenediaminetetraacetic acid; the anti-salt agent is an acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution; the molecular weight of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer is greater than 15,000; and the solid content of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution is 30-40%; The method of application includes: The chelating agent and groundwater from a marine environment are mixed to obtain a solution A; Mixing the solution A and a thickener to obtain a solution B; Mixing the solution B with a salt-repellent agent, a dispersant, and bentonite to obtain a slurry; The chemical composition of the groundwater in the marine environment includes, by weight percentage, 0.2-0.3% magnesium and 0.5-1.0% calcium.

2. The use according to claim 1, characterized in that The density of the bentonite is 2.3-2.5 g / cm 3 , loss on ignition ≤18%.

3. The use according to claim 1, characterized in that The dispersant is an inorganic dispersant.

4. The use according to claim 1, characterized in that The thickener includes sodium carboxymethyl cellulose and / or xanthan gum.

5. The use according to claim 1, characterized in that The preparation method of the acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution comprises: Acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, water, NaOH solution and initiator are mixed to carry out free radical polymerization reaction to obtain acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer solution.

6. The use according to claim 1, characterized in that The salt concentration of the groundwater in the marine environment is 0.9-1.5 wt %; the concentration of divalent cations in the groundwater in the marine environment is 5-30 mmol / L.

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