High-calcium-resistant plugging filtrate reducer for drilling fluid as well as preparation method and application of high-calcium-resistant plugging filtrate reducer

Abstract

The invention provides a high-calcium-resistant plugging filtrate reducer for drilling fluid as well as a preparation method and application of the high-calcium-resistant plugging filtrate reducer, and relates to the field of drilling fluid. The high-calcium-resistant plugging filtrate reducer for the drilling fluid is prepared from the following raw materials in parts by weight: 60 to 80 parts of AMPS-phosphate ester / AM copolymer, 3 to 5 parts of silane modified nano SiO2, 10 to 30 parts of styrene, 3 to 5 parts of emulsifier, 1 to 3 parts of cross-linking agent and 0.05 to 0.15 part of initiator. The invention also provides a preparation method of the anti-high-calcium blocking filtrate reducer for the drilling fluid and application of the anti-high-calcium blocking filtrate reducer in water-based drilling fluid. The high-calcium-resistant plugging filtrate reducer for the drilling fluid provided by the invention can improve the salt resistance and calcium resistance of a drilling fluid system, effectively plug micropores of a mud cake, improve the quality of the mud cake and adjust the flow pattern of the drilling fluid, and is long in acting time, good in compatibility and suitable for a water-based system under various high-calcium conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of drilling fluids, in particular to an anti-high-calcium plugging fluid loss additive for drilling fluids, a preparation method and application thereof. BACKGROUND

[0002] During the construction process of underground drilling and drilling fluid circulation, drilling fluid frequently contacts with concrete, calcium ions continuously invade the drilling fluid, and the working performance of the drilling fluid will gradually deteriorate, and a large amount of waste slurry will be produced after the construction is completed. Therefore, it is required to continuously improve the calcium resistance of the drilling fluid. Therefore, considering the frequency of encountering complex strata during drilling, it is urgent to develop an anti-high-calcium plugging fluid loss additive that can resist high calcium and reduce fluid loss and adjust the flow pattern.

[0003] The anti-salt and high-temperature fluid loss additives in the prior art mainly include the following types: first, drilling fluid polymer fluid loss additives, which have good salt resistance and can resist temperatures above 150 DEG C, but have certain viscosity increasing effect, poor resistance to divalent ions, and the polymer products are easily degraded at high temperature for a long time, and the effect maintenance time is short; second, synthetic polymer fluid loss additives, which have good salt resistance and can resist temperatures up to 160 DEG C, can resist low concentration of divalent salt, but have poor effect on resisting high concentration of divalent salt, and have poor plugging property, cannot plug microcracks, and the cost of synthetic monomer is high; third, natural polyphenol polymer fluid loss additives, which have salt resistance and calcium resistance, can resist temperatures up to 180 DEG C, have good fluid loss effect, but have large viscosity increasing range, and the effect maintenance time is short at high temperature; fourth, lignite resin fluid loss additives, which have salt resistance and calcium resistance, have good viscosity reducing effect, can resist temperatures up to 150 DEG C, but the calcium resistance effect depends on the sulfonation degree (Ca 2+ >5000 mg / L), and has poor environmental performance.

[0004] In summary, the current anti-high-calcium plugging fluid loss additive for drilling fluid has single function, cannot simultaneously meet the effects of resisting high temperature, salt, high calcium, fluid loss reduction and viscosity reduction, the product effect maintenance time is short, and it is difficult to be widely applied. SUMMARY

[0005] Therefore, the purpose of the present application is to provide an anti-high-calcium plugging fluid loss additive which has good plugging and fluid loss reduction effect under high temperature and high calcium conditions, can effectively plug the micro-pore of the mud cake, improve the quality of the mud cake and adjust the flow pattern of the drilling fluid.

[0006] To achieve the above purpose, the present application provides the following technical solutions: In a first aspect, the present application provides a high-calcium resistant plugging fluid loss additive for drilling fluid, which is prepared from raw materials including the following components in parts by weight: 60-80 parts of AMPS-phosphonate / AM copolymer, 3-5 parts of emulsifier, 1-3 parts of crosslinking agent, 0.05-0.15 parts of initiator, 10-30 parts of styrene, and 2-5 parts of silane-modified nano-SiO2. The preparation method of the AMPS-phosphonate / AM copolymer comprises: 2-acrylamido-2-methylpropane sulfonic acid and 2-(hydroxyethyl) dimethyl phosphate undergo esterification reaction in a non-polar solvent at a molar ratio of 1-3:1 to obtain AMPS-phosphonate; and the AMPS-phosphonate and acrylamide undergo copolymerization reaction at a molar ratio of 2:1 to obtain the AMPS-phosphonate / AM copolymer.

[0007] Further, the high-calcium resistant plugging fluid loss additive for drilling fluid is prepared from raw materials including the following components in parts by weight: 63 parts of AMPS-phosphonate / AM copolymer, 3.6 parts of emulsifier, 1.8 parts of crosslinking agent, 0.09 parts of initiator, 18 parts of styrene, and 3.6 parts of silane-modified nano-SiO2.

[0008] Further, the conditions of the esterification reaction are as follows: 2-acrylamido-2-methylpropane sulfonic acid and 2-(hydroxyethyl) dimethyl phosphate are dispersed in a non-polar solvent, and the reaction is carried out in a closed container at 110°C for 5 hours, and the solvent is recovered by distillation.

[0009] Further, the non-polar solvent is toluene.

[0010] Further, the conditions of the copolymerization reaction are as follows: the AMPS-phosphonate and acrylamide are dissolved in distilled water, the total mass of the AMPS-phosphonate and acrylamide added in 100 mL of distilled water is 30 g, and the copolymerization reaction is carried out at 50-60°C for 3-5 hours.

[0011] Further, the emulsifier is Tween 80.

[0012] Further, the crosslinking agent is N,N'-methylenebisacrylamide.

[0013] Further, the initiator includes ammonium persulfate and sodium bisulfite at a mass ratio of 1:1.

[0014] Further, the preparation raw materials further include: 200-220 parts of distilled water, preferably 210 parts.

[0015] Further, the preparation method of the silane modified nano-SiO2 comprises the following steps: dispersing nano-SiO2 in an ethanol solution with a volume concentration of 20-25%, adding 6-8% silane coupling agent by mass to the dispersion, and reacting at 60-70°C for 20-24 hours; the reaction product is centrifuged and washed at 3000-4000 rpm for 3-5 minutes, and the operation is repeated 2-3 times to obtain the silane modified nano-SiO2.

[0016] Further, the nano-SiO2 is selected from nano-SiO2 prepared by a gas phase method; the silane coupling agent is silane coupling agent KH-570; 18 g of nano-SiO2 is added to 100 mL of ethanol solution; the volume concentration of the ethanol solution is 90%; the mass of the silane coupling agent is 3% of the dispersion; the reaction temperature is 70°C, and the reaction time is 24 hours; the centrifugal washing condition is centrifugal washing at 3000 rpm for 5 minutes, and the operation is repeated 3 times.

[0017] In the second aspect, the application provides a preparation method of the high-calcium-resistant plugging and fluid loss additive for drilling fluid, which comprises the following steps: uniformly mixing AMPS-phosphonate / AM copolymer, silane modified nano-SiO2, styrene, emulsifier and crosslinking agent with water, adjusting the pH value to 7.0-8.0, adding an initiator, and performing graft polymerization reaction at 55-65°C for 5-8 hours to obtain the high-calcium-resistant plugging and fluid loss additive for drilling fluid.

[0018] Further, the pH value is 7.0-7.5; the graft polymerization reaction temperature is 60±2°C; and the graft polymerization reaction time is 6 hours.

[0019] In the third aspect, the application provides application of the high-calcium-resistant plugging and fluid loss additive for drilling fluid or the high-calcium-resistant plugging and fluid loss additive for drilling fluid obtained by the preparation method in water-based drilling fluid.

[0020] In the fourth aspect, the application provides a water-based drilling fluid, which is composed of bentonite slurry and a treating agent; the water content of the bentonite slurry is 97-98%; and the treating agent comprises, in an amount of 100 mL of bentonite slurry, 2-3 g of temperature-resistant fluid loss additive, 2-3 g of the high-calcium-resistant plugging and fluid loss additive for drilling fluid, 1-2 g of film-forming plugging agent, 0.5-1 g of high-temperature-resistant polymer fluid loss additive, 0.2-0.5 g of coating agent, 1-2 g of rigid particle plugging agent, 1-2 g of ultra-fine calcium carbonate, 1-2 g of biomimetic plugging agent, 1-1.5 g of lubricant, 0.1-0.2 g of viscosity enhancer and 20-30 g of weighting agent.

[0021] Further, the bentonite slurry has a water content of 98%; and the treating agent includes, in terms of the amount of 100 mL of the bentonite slurry, 3 g of temperature-resistant fluid loss additive, 2-3 g of the high-calcium-resistant plugging fluid loss additive for drilling fluid, 2 g of film-forming plugging agent, 1 g of high-temperature-resistant polymer fluid loss additive, 0.5 g of coating agent, 2 g of rigid particle plugging agent, 2 g of superfine calcium carbonate, 2 g of biomimetic plugging agent, 1.5 g of lubricant, 0.2 g of viscosity enhancer, and 30 g of weighting agent.

[0022] The application provides the high-calcium-resistant plugging fluid loss additive for drilling fluid, and the preparation raw material includes: AMPS-phosphonate / AM copolymer, silane modified nano SiO2, styrene, emulsifier, crosslinking agent, and initiator. (1) AMPS-phosphonate / AM copolymer The AMPS-phosphonate is prepared by esterification reaction of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 2-(hydroxyethyl) dimethyl phosphate in a non-polar solvent.

[0023] The AMPS provides a sulfonic acid group (-SO3H), the 2-(hydroxyethyl) dimethyl phosphate provides a hydroxyl group (-OH), the sulfonic acid group and the hydroxyl group are esterified to generate a sulfonate group, and the 2-(hydroxyethyl) dimethyl phosphate also provides a phosphate group, so that the AMPS-phosphonate has both the sulfonate group and the phosphate group.

[0024] The non-polar solvent: dissolves the AMPS and disperses the 2-(hydroxyethyl) dimethyl phosphate, controls the reaction rate, and avoids local overheating to cause a side reaction. Preferably, toluene, which has a boiling point of 110 ℃, matches the reaction temperature and removes water through reflux.

[0025] The specific reaction formula is as follows:

[0026] The product structural formula is shown as formula (I):

[0027] The AMPS-phosphonate provides a phosphate group and a sulfonate group as a functional monomer, wherein: The phosphate group has strong chelation ability (100 times of carboxyl), and can chelate Ca 2+ forms a five-membered ring chelate with a stable constant logK=8.2, the five-membered ring chelate is adsorbed on the crystal surface to distort the CaCO3 lattice (lattice distortion effect), blocks the deposition of calcium salt, and improves the calcium limit resistance; The sulfonate group has strong ionization (ionization constant pKa≈-2), and can form a strong ion pair with Ca 2+The environment keeps negative charge, prevents clay particles from gathering by electrostatic repulsion, inhibits calcium flocculation, and maintains stable rheological property.

[0028] Acrylamide (AM) provides amide group (-CONH2) as functional monomer, enhances polymer chain flexibility and adsorption, and reduces the risk of intermolecular crosslinking; the amide group adsorbs clay particles through hydrogen bond to stabilize the filter cake structure.

[0029] (2) Silane-modified nano-SiO2: provides a nano-SiO2 core to form a core-shell structure with AMPS-phosphonate / AM copolymer, which not only maintains the 20 nm particle size plugging capacity but also avoids particle agglomeration and viscosity increase; self-adaptive plugging is achieved: when the temperature rises, the polymer shrinks, and the nano-particles are released to penetrate into micro-cracks.

[0030] (3) Styrene: provides rigid benzene ring units to inhibit high-temperature thermal motion of polymer chains, and the decomposition temperature is >220℃ (the decomposition temperature of traditional drilling fluid carboxymethyl cellulose sodium salt PAC-LV is ≤150℃).

[0031] (4) Emulsifier (such as Tween 80): increases the solubility of reactants.

[0032] (5) Crosslinking agent (such as N,N'-methylene bisacrylamide): the molecular structure contains double bonds, which can promote the formation of a three-dimensional crosslinked network and delay chain rupture.

[0033] (6) Initiator: redox system (such as ammonium persulfate-sodium bisulfite), which initiates free radical polymerization at low temperature and controls the molecular weight distribution; the initiation efficiency is >90% at 60℃, avoiding decomposition of sulfonic acid groups at high temperature.

[0034] The present application realizes dual functionalization of the AMPS-phosphonate molecular structure and physical-chemical synergistic plugging (chemical plugging of polymer chains and physical plugging of modified nano-SiO2 particles), avoids loss of control of drilling fluid filtration in micro-crack formations, and solves the technical problem of wellbore instability.

[0035] The technical scheme of the present application has the following advantages: 1. The anti-high-calcium plugging and filtration-reducing agent for drilling fluid provided by the present application can improve the salt and calcium resistance of the drilling fluid system, effectively plug the micro-pores of the mud cake, improve the quality of the mud cake, and adjust the flow pattern of the drilling fluid.

[0036] 2. The anti-high-calcium plugging and filtration-reducing agent for drilling fluid provided by the present application has outstanding calcium resistance in the drilling fluid system, long action time, and good compatibility, and is suitable for various water-based systems under high-calcium conditions.

[0037] 3. The drilling fluid anti-high calcium plugging fluid loss reducer provided by the application can prolong the service life of the drilling fluid, increase the circulation period, improve the downhole circulation quality, reduce the drilling time caused by the drilling fluid filtration control problem, greatly reduce the frequency of calcium pollution treatment on the well, reduce the well collapse accident rate, and thus reduce the drilling cost.

[0038] 4. The water-based drilling fluid provided by the application still has good flow performance and rheological performance after being aged at 150 DEG C for 64 h under the addition of 35% calcium chloride, and has good filtration wall building performance. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is a process route map for preparing the drilling fluid anti-high calcium plugging fluid loss reducer in Example 1 of the application. DETAILED DESCRIPTION

[0040] The following examples are provided for better further understanding of the application and are not limited to the best mode, do not constitute limitations on the content and protection scope of the application, and any person under the enlightenment of the application or the combination of the application with other prior art features falls within the protection scope of the application.

[0041] The specifications, models and sources of the raw materials required in the preparation of the water-based drilling fluid are shown in Table 1. Table 1 Preparation raw materials

[0042] If the specific experimental steps or conditions are not specified in the examples, the operation or conditions can be performed according to the conventional experimental steps described in the literature in the art. The raw materials or instruments used are conventional products that can be obtained by purchase, including but not limited to the raw materials or instruments used in the examples of the application.

[0043] Example 1 The example provides a drilling fluid anti-high calcium plugging fluid loss reducer, and the preparation process route is as shown in Figure 1 The specific preparation steps are as follows: (1) Preparation of AMPS-phosphonate: 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 2-(hydroxyethyl) dimethyl phosphate are dispersed in toluene at a molar ratio of 3:1, and reacted in a sealed container at 110 DEG C for 5 h. The solvent is recovered by distillation to obtain AMPS-phosphonate; (2) Preparation of AMPS-phosphonate / AM copolymer: AMPS-phosphonate and acrylamide are dissolved in distilled water at a molar ratio of 2:1, the total mass of AMPS-phosphonate and acrylamide in 100 mL of distilled water is 30 g, and copolymerization is carried out at 55℃ for 4 h to obtain AMPS-phosphonate / AM copolymer; (3) Preparation of silane-modified nano-SiO2: 18 g of nano-SiO2 prepared by a vapor phase method is dispersed in 100 mL of an ethanol solution with a volume concentration of 20%, and after ultrasonic treatment for 1 h, 6% of silane coupling agent KH-570 by mass is added to the dispersion, and reflux reaction is carried out at 70℃ for 24 h; the reaction product is centrifuged at 3000 rpm for 5 min, and the operation is repeated 3 times to obtain silane-modified nano-SiO2; (4) Preparation of fluid loss additive: 70 parts of distilled water is added to a reaction kettle, and 21 parts of AMPS-phosphonate / AM copolymer, 1.2 parts of silane-modified nano-SiO2, 6 parts of styrene, 1.2 parts of Tween 80, and 0.6 parts of crosslinking agent are added; sodium hydroxide is used to adjust the pH value to 7.0-7.5, and the temperature is raised to 60±2℃; 0.03 parts of initiator is added, and graft polymerization is carried out under the above-mentioned pH and temperature conditions for 6 h to obtain the product, which is the anti-high-calcium plugging fluid loss additive of the present application, and the molecular weight thereof is about 600,000.

[0044] Example 2 The present example provides a water-based drilling fluid, which is obtained by mixing bentonite slurry (water content 98%) and treatment agent; the components and amounts of the treatment agent are as follows: 3 g of temperature-resistant fluid loss additive, 3 g of drilling fluid anti-high-calcium plugging fluid loss additive (prepared in Example 1), 2 g of film-forming plugging agent, 1 g of high-temperature-resistant polymer fluid loss additive, 0.5 g of coating agent, 2 g of rigid particle plugging agent, 2 g of ultra-fine calcium carbonate, 2 g of biomimetic plugging agent, 1.5 g of lubricant, 0.2 g of viscosity enhancer, and 30 g of weighting agent, based on the amount of 100 mL of bentonite slurry.

[0045] Example 3 The present example provides a water-based drilling fluid, which is obtained by mixing bentonite slurry (water content 98%) and treatment agent; the components and amounts of the treatment agent are as follows: 3 g of temperature-resistant fluid loss additive, 2 g of drilling fluid anti-high-calcium plugging fluid loss additive (prepared in Example 1), 2 g of film-forming plugging agent, 1 g of high-temperature-resistant polymer fluid loss additive, 0.5 g of coating agent, 2 g of rigid particle plugging agent, 2 g of ultra-fine calcium carbonate, 2 g of biomimetic plugging agent, 1.5 g of lubricant, 0.2 g of viscosity enhancer, and 30 g of weighting agent, based on the amount of 100 mL of bentonite slurry.

[0046] Comparative Example 1 The comparative example provides a fluid loss additive, the preparation method refers to example 1, and the only difference is that the AMPS-phosphonate is replaced by equal molar amount of AMPS to prepare AMPS / AM copolymer, and the AMPS-phosphonate / AM copolymer is replaced by equal amount of AMPS / AM copolymer.

[0047] Comparative example 2 The comparative example provides a fluid loss additive, the preparation method refers to example 1, and the only difference is that the AMPS-phosphonate is replaced by equal molar amount of AMPS to prepare AMPS / AM copolymer, and the AMPS-phosphonate / AM copolymer is replaced by equal amount of AMPS / AM copolymer and a mixture of vinyl phosphoric acid (mass ratio 2:1).

[0048] Comparative example 3 The comparative example provides a fluid loss additive, the preparation method refers to example 1, and the only difference is that the styrene is omitted.

[0049] Experimental example 1 single agent performance detection The present experimental example aims to detect the single agent performance of the high calcium resistant plugging fluid loss additive for drilling fluid prepared in example 1 and comparative examples 1-3, and the detection is carried out according to the operation specification and calculation of Oil and Natural Gas Industry Drilling Fluid Field Test Part 1: Water-based Drilling Fluid (standard number: GB / T 16783.1-2014). The detection items, index requirements and detection results are shown in table 2. Among them: system 1 is 3% calcium chloride brine slurry (3 g of calcium chloride is added in 100 g of distilled water to prepare); system 2 is 30% sodium chloride brine slurry (30 g of sodium chloride is added in 100 g of distilled water to prepare).

[0050] Table 2 single agent detection results

[0051] As shown in table 2, the high calcium resistant plugging fluid loss additive for drilling fluid prepared in example 1 has outstanding salt resistance and calcium resistance effect (single agent detection calcium resistance 3%, about 10800 mg / L, while the calcium resistance of conventional products is about 4000 mg / L), and good temperature resistance. Compared with example 1, the calcium resistance of the product of comparative example 1 is poor because AMPS is not phosphonated, and the salt resistance effect changes little; the calcium resistance of the product of comparative example 2 is poor because AMPS is not phosphonated and vinyl phosphoric acid is added (compared with comparative example 1 without vinyl phosphoric acid, the product has certain improvement effect), and the salt resistance effect changes little; the temperature resistance and calcium resistance of the product of comparative example 3 are poor because styrene is not added, and the salt resistance effect changes little. It is proved that AMPS-phosphonate as a polymer monomer significantly improves the calcium resistance of the product, and the addition of styrene can effectively improve the temperature resistance and calcium resistance of the product.

[0052] Experimental Example 2: Drilling fluid performance test The present experimental example aims to test the calcium resistance of the water-based drilling fluid prepared in Example 2 and Example 3. The calcium chloride is added to the water-based drilling fluid (35 g of calcium chloride is added to 100 mL of bentonite slurry), and the operation and calculation are performed according to the operation specification of Oil and Natural Gas Industry Drilling Fluid Field Test Part 1: Water-based Drilling Fluid (Standard No.: GB / T 16783.1-2014).

[0053] Table 3: Drilling fluid performance test results

[0054] As shown in Table 3, under the addition of 35% calcium chloride, the water-based drilling fluid system still has good flow performance and rheological performance, and also has good filtration and wall building performance.

[0055] Obviously, the above examples are only examples for the purpose of clarity, and are not limitations on the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A drilling fluid anti-high-calcium plugging and filtration loss reducing agent, characterized in that, It is prepared from raw materials comprising the following parts by weight: 60-80 parts of AMPS-phosphate ester / AM copolymer, 3-5 parts of silane-modified nano-SiO2, 10-30 parts of styrene, 3-5 parts of emulsifier, 1-3 parts of crosslinking agent, and 0.05-0.15 parts of initiator. The preparation method of the AMPS-phosphate ester / AM copolymer includes: esterification reaction of 2-acrylamido-2-methylpropanesulfonic acid and 2-(hydroxyethyl) dimethyl phosphate in a nonpolar solvent at a molar ratio of 1 to 3:1 to obtain AMPS-phosphate ester; and copolymerization reaction of AMPS-phosphate ester with acrylamide at a molar ratio of 2:1 to obtain AMPS-phosphate ester / AM copolymer.

2. The drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 1, characterized in that, It is prepared from the following raw materials in parts by weight: 63 parts of AMPS-phosphate ester / AM copolymer, 3.6 parts of silane-modified nano-SiO2, 18 parts of styrene, 3.6 parts of emulsifier, 1.8 parts of crosslinking agent and 0.09 parts of initiator.

3. The drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 1, characterized in that, The conditions for the esterification reaction were as follows: 2-acrylamido-2-methylpropanesulfonic acid and 2-(hydroxyethyl) dimethyl phosphate were dispersed in a nonpolar solvent and reacted in a closed container at 110 °C for 5 h, and the solvent was recovered by distillation. The copolymerization reaction conditions are as follows: AMPS-phosphate ester and acrylamide are dissolved in distilled water, and the total mass of AMPS-phosphate ester and acrylamide is 30 g added to every 100 mL of distilled water. The copolymerization reaction is carried out at 50~60 ℃ for 3~5 h.

4. The drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 1, characterized in that, The emulsifier is Tween 80; The crosslinking agent is N,N'-methylenebisacrylamide; The initiator comprises ammonium persulfate and sodium bisulfite in a mass ratio of 1:1; The raw materials for its preparation also include: 200-220 parts of distilled water.

5. The drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 1, characterized in that, The method for preparing silane-modified nano-SiO2 includes: dispersing nano-SiO2 in an ethanol solution with a volume concentration of 20%~25% and dispersing it evenly; adding 6%~8% by mass of a silane coupling agent to the dispersion; reacting at 60~70 °C for 20~24 h; centrifuging and washing the reaction product at 3000~4000 rpm for 3~5 min; repeating the process 2~3 times to obtain silane-modified nano-SiO2.

6. The drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 5, characterized in that, The nano-SiO2 is selected from gas-phase nano-SiO2; the silane coupling agent is silane coupling agent KH-570; 18 g of nano-SiO2 is added to every 100 mL of ethanol solution; the volume concentration of the ethanol solution is 20%; the mass of the silane coupling agent is 6% of the dispersion; the reaction temperature is 70 ℃, the reaction time is 24 h; the centrifugation and washing conditions are centrifugation and washing at 3000 rpm for 5 min, repeated 3 times.

7. The method for preparing the drilling fluid anti-high calcium plugging and filtration loss reducing agent according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing AMPS-phosphate ester / AM copolymer, silane-modified nano-SiO2, styrene, emulsifier and crosslinking agent with water until homogeneous, adjusting the pH to 7.0~8.0, adding an initiator, and carrying out a graft polymerization reaction at 55~65 ℃ for 5~8 h to obtain the drilling fluid anti-high calcium plugging and filtration loss reducing agent.

8. The preparation method of the drilling fluid anti-high calcium plugging and filtration loss reducing agent according to claim 7, characterized in that, The pH value was 7.0~7.5; the graft polymerization temperature was 60±2 ℃; and the graft polymerization time was 6 h.

9. The application of the drilling fluid anti-high calcium plugging and filtration loss reducing agent according to any one of claims 1 to 6 or the drilling fluid anti-high calcium plugging and filtration loss reducing agent obtained by the preparation method according to claim 7 or 8 in water-based drilling fluids.

10. A water-based drilling fluid, characterized in that, Composed of bentonite slurry and treatment agent, wherein the water content of the bentonite slurry is 97%~98%; based on the dosage of 100 mL of bentonite slurry, the treatment agent includes: 2~3 g of anti-temperature filtration loss agent, 2~3 g of drilling fluid anti-high calcium plugging filtration loss agent, 1~2 g of film-forming plugging agent, 0.5~1 g of anti-high temperature polymer filtration loss agent, 0.2~0.5 g of coating agent, 1~2 g of rigid particle plugging agent, 1~2 g of ultrafine calcium carbonate, 1~2 g of biomimetic plugging agent, 1~1.5 g of lubricant, 0.1~0.2 g of shearing agent, and 20~30 g of weighting agent.

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