Temperature-resistant and salt-resistant wall-fixing agent for water-based drilling fluid for myriameter deep well as well as preparation method and application of wall-fixing agent

Abstract

The invention provides a temperature-resistant and salt-resistant wall-fixing agent for a water-based drilling fluid for a myriameter deep well as well as a preparation method and application of the wall-fixing agent, and belongs to the technical field of drilling. The preparation method of the wall fixing agent comprises the following steps: adding acrylic acid into deionized water, adjusting the pH value of a system to 7.0, then sequentially adding N-hydroxymethyl acrylamide, N-[2-(3, 4-dihydroxyphenyl) ethyl]-2-acrylamide, an emulsifier, octadecyl vinyl ether and a complexing agent into the system, and shearing to obtain a monomer solution; adding an initiator into the monomer solution, and reacting; and after the reaction is completed, washing, drying and crushing to obtain the wall fixing agent. The wall fixing agent can resist the temperature of 200 DEG C, can resist the salt to be saturated, has strong adsorbability and high cohesion, and can effectively adsorb, block and bond micropores and micro cracks of rocks, so that the rocks are solidified, the well wall stability is effectively enhanced, drilling fluid leakage is prevented, and a technical guarantee is provided for safe and efficient drilling of deep wells.

Description

Technical Field

[0001] The present invention relates to a temperature-resistant and salt-tolerant wellbore stabilizing agent for ten-thousand-meter deep water-based drilling fluid, its preparation method and application, belonging to the field of drilling technology. Background Technique

[0002] Drilling fluid is the "blood" of the drilling engineering, which has the functions of lubricating the drill bit, cleaning the bottom of the well, balancing the formation pressure and maintaining the stability of the wellbore. Safe and efficient drilling requires the support of high-performance drilling fluid. Deep and ultra-deep formations coexist with complex and harsh conditions of high temperature, high pressure and high salt. Especially when drilling through high-permeability sandstone, conglomerate, natural fractured carbonate rock formations and weakly cemented hard and brittle shale formations, the water-based drilling fluid is extremely easy to invade into the interior of the formation along the rock pores and cracks, causing formation hydration, resulting in wellbore instability, and bringing downhole complex accidents such as well collapse, stuck pipe and hole shrinkage.

[0003] At present, chemical cementing wellbore stabilizing agents have become the key treatment agents for stabilizing the wellbore. Chinese Patent Document CN117986520A discloses an environmentally friendly lignin-based strong cementing wellbore stabilizing agent, which is prepared from 4,4'-diphenylmethane diisocyanate and lignin. The wellbore stabilizing agent contains hydrophilic and hydrophobic groups such as hydroxyl groups and benzene rings, which can effectively repel the water molecules between the wellbore stabilizing agent and the rock, and form a three-dimensional network structure through hydrogen bonds, van der Waals forces and hydrophobic interactions, improving the cementing strength between the wellbore stabilizing agent and the rock. However, due to the ether bonds in lignin that are easy to hydrolyze, the temperature resistance of this wellbore stabilizing agent is only 150°C. Chinese Patent Document CN116589632A discloses a high-temperature-resistant and low-viscosity hyperbranched wellbore stabilizing agent prepared from dipentaerythritol hexaacrylate, polyethylene glycol diacrylate, glycine, 3-aminopropanesulfonic acid and tannic acid. The hydrophobic skeleton formed by the ester bonds and benzene rings in the wellbore stabilizing agent will quickly aggregate and form aggregates, excluding the water molecules between the wellbore stabilizing agent and the rock particles, reducing the destructive effect of free water molecules on the rock cementing force, and effectively bonding the rock. Due to the easy hydrolysis of the ester group at high temperature, the temperature resistance of this wellbore stabilizing agent is only 180°C.

[0004] Chinese patent document CN115093837A discloses a wall fixing agent, which is compounded by redispersible latex powder, rubber, thermosetting resin, epoxy resin, chloroprene latex, and nano-silica, and its temperature resistance is only 120°C. Chinese patent document CN115057967A discloses a microgel chemical wall fixing agent, which is prepared by inverse emulsion polymerization of cellulose, polyacrylamide, xanthan gum macromolecules and vinyl monomers such as acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and acrylate. The temperature resistance of cellulose, polyacrylamide, xanthan gum, and acrylate is poor, and the temperature resistance of the wall fixing agent is only 180°C. Chinese patent document CN116063991A discloses an adhesion cementing wall fixing agent for shale formations, which is composed of an adhesion wall protection agent, a cementing wall fixing agent, and a promoter. The adhesion cementing wall fixing agent is a polymer of styrene, butyl acrylate, 2-acrylamido-2-methylpropanesulfonic acid, a cationic structuring agent, and a crosslinking agent. The cementing wall fixing agent is at least one of alginate, modified alginate, propylene glycol alginate, acrylic acid, polyacrylic acid, and methacrylic acid. The promoter is at least one of calcium chloride, magnesium chloride, calcium sulfate, and magnesium sulfate. The main component of the cementing wall fixing agent is alginate, which is a polysaccharide compound and will decompose violently above 100°C. Therefore, the temperature resistance of the adhesion cementing wall fixing agent is only 120°C. Chinese patent document CN111748330A discloses an aqueous drilling fluid wall fixing agent, which is prepared by free radical polymerization of acrylamide, an adhesive, dimethyldiallylammonium chloride, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid. The adhesive is at least one of vinyl alcohol, vinyl ester, polyvinyl alcohol, vinyl alcohol, vinyl acetate, and diethyl acetate. This wall fixing agent can effectively increase viscosity, increase gel strength, and reduce filtration loss, but its temperature resistance is only 150°C.

[0005] Although the above-mentioned wall fixing agents can all achieve the effect of cementing, their temperature resistance is insufficient and cannot meet the drilling requirements under high temperature conditions of 200°C. Therefore, it is urgent to develop a cementing wall fixing agent with a temperature resistance of up to 200°C to support the smooth drilling of deep wells and ultra-deep wells. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, especially the technical problem that the existing wall fixing agents have insufficient temperature resistance and cannot effectively maintain the stability of the wellbore in high-temperature (200°C) formations, the present invention provides a temperature-resistant and salt-tolerant wall fixing agent for water-based drilling fluid in ten-thousand-meter deep wells, its preparation method and application, especially provides a temperature-resistant, salt-tolerant, strongly adsorptive and highly cohesive cementing wall fixing agent for water-based drilling fluid in ten-thousand-meter deep wells, its preparation method and application.

[0007] The technical solution of the present invention is as follows: A preparation method of a temperature-resistant and salt-tolerant wall fixing agent for water-based drilling fluid in ten-thousand-meter deep wells, including the following steps: (1) Add acrylic acid to deionized water, adjust the pH of the system to 7.0, and then sequentially add N-methylolacrylamide, N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, emulsifier, octadecyl vinyl ether, and complexing agent to the system, and perform shearing to make the monomers disperse evenly to obtain a monomer solution; (2) Add an initiator to the monomer solution and carry out the reaction; after the reaction is completed, wash, dry, and pulverize to obtain a temperature-resistant and salt-tolerant wall stabilizer for 10,000-meter deep well water-based drilling fluid.

[0008] Preferably according to the present invention, in step (1), the mass ratio of the deionized water to acrylic acid is 60-120:5-10.

[0009] Preferably according to the present invention, in step (1), use sodium hydroxide or potassium hydroxide to adjust the pH of the system to 7.

[0010] Preferably according to the present invention, in step (1), the mass ratio of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, N-methylolacrylamide, acrylic acid, and octadecyl vinyl ether is 5-10:10-20:5-10:1-5.

[0011] Preferably according to the present invention, in step (1), the emulsifier is any one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, Tween 80, and Span 80; the mass ratio of the emulsifier to octadecyl vinyl ether is 0.01-0.03:1-5.

[0012] Preferably according to the present invention, in step (1), the complexing agent is ferric chloride hexahydrate, zinc chloride, magnesium chloride, or calcium chloride; the mass ratio of the complexing agent to N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide is 0.3-0.8:5-10.

[0013] Preferably according to the present invention, in step (1), the shearing rate is 1500-2500 rpm and the shearing time is 10-30 min.

[0014] Preferably according to the present invention, N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide in step (1) is prepared by the following method: Add 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride to methanol and stir until the solid dissolves to obtain solution 1; add acryloyl chloride to tetrahydrofuran and stir to dissolve to obtain solution 2; add triethylamine to methanol and stir evenly to obtain solution 3; add solution 2 and solution 3 dropwise into solution 1, and after the dropping is completed, carry out the reaction to obtain N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide.

[0015] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the mass ratio of methanol to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride in Solution 1 is 70 - 130:8 - 15.

[0016] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the mass ratio of acryloyl chloride to tetrahydrofuran in Solution 2 is 4.5 - 6.5:4.2 - 5.5.

[0017] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the mass ratio of triethylamine to methanol in Solution 3 is 13 - 18:20 - 35.

[0018] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the mass ratio of acryloyl chloride to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride is 4 - 6:10 - 15; the mass ratio of triethylamine to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride is 1 - 2:1.

[0019] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, Solution 2 and Solution 3 are simultaneously added dropwise to Solution 1 at 0 - 5°C, and the dropping time is 15 - 20 min.

[0020] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the reaction temperature is 20 - 30°C, the reaction time is 5 - 7 h; the reaction is carried out under a nitrogen atmosphere.

[0021] Preferably, in the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, after the reaction is completed, a post-treatment step is further included, specifically as follows: the obtained reaction solution is removed of the solvent, ethyl acetate is added, the organic phase is washed with a mixed solution containing HCl and NaCl, dried over anhydrous sodium sulfate, filtered, and the solvent is removed. The obtained product is vacuum dried at 100 - 110°C to constant weight to obtain N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide; the mass ratio of HCl to NaCl in the mixed solution is 7 - 9:10 - 12, and the concentration of HCl in the mixed solution is 0.5 - 1.5 mol / L.

[0022] Preferably according to the present invention, the initiator in step (2) is a composition of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride, wherein the mass ratio of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride is 5-8:2-4:8-12, and the mass ratio of the initiator to N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is 0.15-0.25:5-10.

[0023] Preferably according to the present invention, the temperature of the reaction in step (2) is 70-80 °C, and the reaction time is 5-7 h; the washing is carried out by washing with methanol 2-3 times, and the drying is carried out at 70-80 °C until constant weight.

[0024] The present invention also provides a temperature-resistant and salt-tolerant wellbore stabilizing agent for 10,000-meter deep water-based drilling fluids, which is prepared by the above preparation method.

[0025] According to the present invention, the above temperature-resistant and salt-tolerant wellbore stabilizing agent for 10,000-meter deep water-based drilling fluids is used in water-based drilling fluids to stabilize the wellbore and prevent leakage; the mass concentration of the temperature-resistant and salt-tolerant wellbore stabilizing agent for 10,000-meter deep water-based drilling fluids in the water-based drilling fluid is 1-3 wt%.

[0026] The technical features and beneficial effects of the present invention are as follows: 1. The temperature-resistant and salt-tolerant wellbore stabilizing agent of the present invention is a strongly adsorbed and highly cohesive wellbore stabilizing agent, which is prepared by free radical copolymerization of an acrylamide special monomer modified with catechol groups, N-methylolacrylamide, acrylic acid, and octadecyl vinyl ether, and contains strongly polar hydroxyl groups, amide groups, catechol groups, and strongly hydrophobic long alkyl chains. The hydroxyl groups, carboxyl groups, and catechol groups can strongly adhere to the rock surface through adsorption actions such as hydrogen bonds, π-π interactions, coordination bonds, and covalent bonds. The strongly hydrophobic long alkyl chains can repel the water molecules between the wellbore stabilizing agent and the rock surface, enhancing the adhesion force between the wellbore stabilizing agent and the rock. At the same time, the catechol groups, carboxyl groups, and hydroxyl groups of the wellbore stabilizing agent can form stable coordination complexes with complexing agents, appropriately crosslinking the molecular chains of the wellbore stabilizing agent, endowing the cementing wellbore stabilizing agent with strong internal cohesion, and thus effectively exerting an excellent cementing wellbore stabilizing effect in the water environment.

[0027] 2. Under the synergistic action of the hydroxyl groups, carboxyl groups, catechol groups, and long alkyl chains of the wellbore stabilizing agent of the present invention, the temperature resistance reaches 200 °C and the salt tolerance reaches saturation. Under high temperature and high salt conditions, it can adsorb, block, and cement the micro-pores and micro-fractures inside the rock, playing a role in consolidating the rock, maintaining the stability of the wellbore, and preventing the leakage of drilling fluids, ensuring the safe and efficient drilling of deep formations.

[0028] 3. The wellbore stabilizing agent of the present invention is simple to prepare, environmentally friendly, and low in price, and is suitable for drilling projects in deep wells, ultra-deep wells, and environmentally sensitive areas. Description of the Drawings

[0029] Figure 1 It is the infrared spectrum of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide prepared in Preparation Example 1.

[0030] Figure 2 It is the 1H NMR spectrum of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide prepared in Preparation Example 1.

[0031] Figure 3 It is the infrared spectrum of the temperature-resistant and salt-tolerant wall-building agent for 10,000-meter deep water-based drilling fluid prepared in Example 1. Detailed Description of the Invention

[0032] The present invention will be described in detail below by way of examples, but this does not limit the present invention. In the following preparation examples, examples and comparative examples, unless otherwise specified, the materials used can be obtained commercially, and the methods used are conventional methods in the art.

[0033] Preparation Example 1 Preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide: Add 12.5 g of 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride and 75.0 g of methanol to a clean beaker, stir until the solid dissolves to obtain Solution 1, and cool it to 0 °C in an ice bath environment; dissolve 5.80 g of acryloyl chloride in 5.5 g of tetrahydrofuran, stir evenly to obtain Solution 2; dissolve 15.8 g of triethylamine in 25.0 g of methanol, stir evenly to obtain Solution 3; at 0 °C, simultaneously add Solution 2 and Solution 3 dropwise into Solution 1, and the dropping time is 20 min; after the dropping is completed, keep the reaction mixture reacting continuously at 25 °C, a stirring rate of 400 rpm, and a nitrogen atmosphere for 6 h. After the reaction is completed, rotary evaporate the solvent from the obtained reaction solution at 70 °C, add 100 mL of ethyl acetate to the obtained crude product, and wash it 2 times with a mixed solution containing HCl and NaCl (the mass ratio of HCl and NaCl in the mixed solution is 3:4, and the concentration of HCl in the mixed solution is 1 mol / L); dry the washed organic layer with anhydrous sodium sulfate, filter, and rotary evaporate to remove the solvent; then vacuum dry the obtained product at 105 °C to constant weight, and the obtained white solid powder is N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide.

[0034] The infrared spectrum of the N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide obtained in this preparation example is as Figure 1 shown, and it can be known from Figure 1 that the characteristic peak at 3449 cm -1 comes from the stretching vibration of the phenolic hydroxyl group; the characteristic peak at 3279 cm -1The characteristic peak at [location] comes from the stretching vibration of the N-H bond in the amide group; at 1669 cm -1 The characteristic peak at [location] comes from the stretching vibration of C=O in the amide group; 1620 cm -1 The characteristic peak at [location] comes from the stretching vibration of the carbon-carbon double bond; 1595, 1512, 1469 cm -1 The characteristic peak at [location] comes from the skeletal vibration of the benzene ring; at 1277 and 1256 cm -1 The characteristic peak at [location] comes from the stretching vibration of C-N in the amide and the bending vibration of the phenolic hydroxyl group; at 1095 cm -1 The characteristic peak at [location] comes from the stretching vibration of the C-O bond in the phenolic hydroxyl group; at 918 cm -1 The characteristic peak at [location] comes from the out-of-plane deformation vibration of the carbon-carbon double bond; at 744 cm -1 The characteristic peak at [location] comes from the bending vibration of the C-H bond in the benzene ring. The results of infrared spectroscopy analysis show that the synthesized product contains characteristic functional groups such as hydroxyl, amide, carbonyl, and carbon-carbon double bonds, indicating the successful synthesis of N-(2-[3,4-dihydroxyphenyl]ethyl)acrylamide.

[0035] The nuclear magnetic resonance hydrogen spectrum of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide obtained in this preparation example is as Figure 2 shown. From Figure 2 it can be seen that the characteristic peak at 2.71 ppm comes from the chemical shift of the hydrogen atom on the methylene group connected to the benzene ring; the characteristic peak at 3.73 ppm comes from the chemical shift of the hydrogen atom on the methylene group in -NH-CH2-; the characteristic peaks at 5.78 ppm and 6.22 ppm come from the chemical shift of the hydrogen atom on the carbon-carbon double bond; the characteristic peaks at 6.82 ppm and 6.92 ppm come from the chemical shift of the hydrogen atom on the benzene ring. From the results of nuclear magnetic resonance hydrogen spectrum and infrared spectroscopy analysis, the synthesized product contains characteristic functional groups such as carbon-carbon double bond, hydroxyl, amide, and benzene ring, indicating the successful synthesis of N-(2-[3,4-dihydroxyphenyl]ethyl)acrylamide (since the phenolic hydroxyl group will undergo ion exchange with the solvent D2O, the characteristic peak of the phenolic hydroxyl group does not appear in the nuclear magnetic resonance hydrogen spectrum).

[0036] Preparation Example 2 Preparation of N-(2-phenylethyl)acrylamide: Dissolve 10.0 g of phenethylamine thoroughly in 70.0 g of methanol to obtain Solution 1, and place it in an ice bath environment to cool to 0 °C; dissolve 6.8 g of acryloyl chloride in 6.0 g of tetrahydrofuran, stir evenly to obtain Solution 2; dissolve 17.2 g of triethylamine in 30.0 g of methanol, stir evenly to obtain Solution 3; at 0 °C, simultaneously add Solution 2 and Solution 3 dropwise into Solution 1, and the dropping time is 20 min; after the dropping is completed, keep the reaction mixture reacting continuously at 25 °C, a stirring rate of 400 rpm, and a nitrogen atmosphere for 6 h. After the reaction is completed, rotary evaporate the solvent from the obtained reaction solution at 70 °C, transfer the obtained crude product to 100 mL of ethyl acetate, and wash it 2 times with a mixed solution of HCl and NaCl (the mass ratio of HCl to NaCl in the mixed solution is 3:4, and the concentration of HCl in the mixed solution is 1 mol / L); dry the washed organic layer with anhydrous sodium sulfate, filter, and rotary evaporate the solvent; then vacuum dry the obtained product at 105 °C to constant weight, and the obtained white solid powder is N-(phenethyl)acrylamide.

[0037] Example 1 A preparation method of a temperature-resistant and salt-tolerant wall stabilizer for a water-based drilling fluid at a depth of 10,000 meters includes the following steps: Add 5 g of acrylic acid and 60 g of deionized water to a clean beaker, add sodium hydroxide particles to adjust the pH of the system to 7.0; then sequentially add 10 g of N-hydroxymethylacrylamide, 5 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 2 g of octadecyl vinyl ether, and 0.3 g of ferric chloride hexahydrate to the system, and shear at a stirring rate of 2000 rpm for 20 min to make the monomers disperse evenly to obtain a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of an initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm, and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product 2 times with methanol, dry it to constant weight at 75 °C, and pulverize it to obtain a temperature-resistant and salt-tolerant wall stabilizer A1 for a water-based drilling fluid at a depth of 10,000 meters.

[0038] The infrared spectrum of the temperature-resistant and salt-tolerant wall stabilizer for the water-based drilling fluid obtained in this example is as Figure 3 shown, and it can be seen from Figure 3 that the characteristic peak at 3450 cm -1 comes from the stretching vibration of the phenolic hydroxyl group; the characteristic peak at 3327 cm -1 comes from the stretching vibration of the N-H bond in the amide group; the characteristic peak at 2935 cm -1 comes from the asymmetric stretching vibration of -CH2 in the long alkyl chain; the characteristic peak at 2860 cm-1 The characteristic peak at [location] comes from the symmetric stretching vibration of -CH3; at 1670 cm -1 The characteristic peak at [location] comes from the stretching vibration of C=O (from amide and carboxyl); at 1595, 1512, 1469 cm -1 The characteristic peak at [location] comes from the skeletal vibration of the benzene ring; at 1277, 1256 cm -1 The characteristic peak at [location] comes from the stretching vibration of C-N in amide and the bending vibration of phenolic hydroxyl; at 1035 cm -1 The characteristic peak at [location] comes from both the stretching vibration of the C–O bond in hydroxyl and the stretching vibration of C-O-C in ether bond; at 744 cm -1 The characteristic peak at [location] comes from the bending vibration of the C-H bond in the benzene ring. At 647 cm -1 The characteristic peak at [location] comes from the stretching vibration of the Fe-O bond. The infrared spectroscopy results show that the wall stabilizer contains the characteristic peaks of four monomer raw materials, indicating the successful polymerization of the wall stabilizer.

[0039] Example 2 A preparation method of a temperature-resistant and salt-tolerant wall stabilizer for a ten-thousand-meter deep water-based drilling fluid, comprising the following steps: Add 10 g of acrylic acid and 60 g of deionized water to a clean beaker, add sodium hydroxide pellets to adjust the pH of the system to 7.0; then sequentially add 10 g of N-methylolacrylamide, 5 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 2 g of octadecyl vinyl ether and 0.3 g of ferric chloride hexahydrate to the system, shear at a stirring rate of 2000 rpm for 20 min to disperse the monomers evenly to obtain a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product with methanol twice, dry it to constant weight at 75 °C, and pulverize it to obtain a temperature-resistant and salt-tolerant wall stabilizer A2 for a ten-thousand-meter deep water-based drilling fluid.

[0040] Example 3 A preparation method of a temperature-resistant and salt-tolerant wall stabilizer for a ten-thousand-meter deep water-based drilling fluid, comprising the following steps: Add 10 g of acrylic acid and 60 g of deionized water into a clean beaker, and add sodium hydroxide pellets to adjust the pH of the system to 7.0; then sequentially add 20 g of N-methylolacrylamide, 5 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 2 g of octadecyl vinyl ether and 0.3 g of ferric chloride hexahydrate into the system, and shear at a stirring rate of 2000 rpm for 20 min to disperse the monomers uniformly to obtain a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm, and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product twice with methanol, dry it to constant weight at 75 °C, and pulverize it to obtain the high-temperature and salt-resistant wall stabilizer A3 for 10,000-meter deep well water-based drilling fluid.

[0041] Example 4 A preparation method of a high-temperature and salt-resistant wall stabilizer for 10,000-meter deep well water-based drilling fluid, comprising the following steps: Add 10 g of acrylic acid and 60 g of deionized water into a clean beaker, and add sodium hydroxide pellets to adjust the pH of the system to 7.0; then sequentially add 20 g of N-methylolacrylamide, 10 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 2 g of octadecyl vinyl ether and 0.3 g of ferric chloride hexahydrate into the system, and shear at a stirring rate of 2000 rpm for 20 min to disperse the monomers uniformly to obtain a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm, and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product twice with methanol, dry it to constant weight at 75 °C, and pulverize it to obtain the high-temperature and salt-resistant wall stabilizer A4 for 10,000-meter deep well water-based drilling fluid.

[0042] Example 5 A preparation method of a high-temperature and salt-resistant wall stabilizer for 10,000-meter deep well water-based drilling fluid, comprising the following steps: Add 10 g of acrylic acid and 60 g of deionized water into a clean beaker, and add sodium hydroxide particles to adjust the pH of the system to 7.0; then add 20 g of N-methylolacrylamide, 10 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 5 g of octadecyl vinyl ether and 0.3 g of ferric chloride hexahydrate into the system in sequence, and shear at a stirring rate of 2000 rpm for 20 min to make the monomers disperse evenly, obtaining a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product twice with methanol, dry it to constant weight at 75 °C, and pulverize it to obtain the high-temperature and salt-resistant wall stabilizer A5 for 10,000-meter deep water-based drilling fluid.

[0043] Example 6 A preparation method of a high-temperature and salt-resistant wall stabilizer for 10,000-meter deep water-based drilling fluid includes the following steps: Add 10 g of acrylic acid and 60 g of deionized water into a clean beaker, and add sodium hydroxide particles to adjust the pH of the system to 7.0; then add 20 g of N-methylolacrylamide, 10 g of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-acrylamide, 0.02 g of sodium dodecyl sulfate, 5 g of octadecyl vinyl ether and 0.6 g of ferric chloride hexahydrate into the system in sequence, and shear at a stirring rate of 2000 rpm for 20 min to make the monomers disperse evenly, obtaining a monomer solution. Transfer the monomer solution to a three-necked flask, add 0.20 g of initiator (the initiator is a mixture of ammonium persulfate, sodium bisulfite, 2,2'-azobis(2-methylpropionamidine) dihydrochloride in a mass ratio of 2:1:2), and continuously react at 75 °C, a stirring rate of 200 rpm and a nitrogen atmosphere for 6 h to obtain a pale yellow viscous reaction product; wash the reaction product twice with methanol, dry it to constant weight at 75 °C, and pulverize it to obtain the high-temperature and salt-resistant wall stabilizer A6 for 10,000-meter deep water-based drilling fluid.

[0044] Comparative Example 1 A preparation method of a wall stabilizer for water-based drilling fluid is as described in Example 1, the difference is that: acrylic acid is replaced with acrylamide of the same mass, obtaining the wall stabilizer D1 for water-based drilling fluid.

[0045] Comparative Example 2 A preparation method of a wall stabilizer for water-based drilling fluid is as described in Example 1, the difference is that: N-methylolacrylamide is replaced with N,N-dimethylacrylamide of the same mass, obtaining the wall stabilizer D2 for water-based drilling fluid.

[0046] Comparative Example 3 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: octadecyl vinyl ether is replaced with ethyl vinyl ether of the same mass to obtain a wall stabilizing agent D3 for water-based drilling fluid.

[0047] Comparative Example 4 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is replaced with N-(2-phenylethyl)acrylamide of the same mass to obtain a wall stabilizing agent D4 for water-based drilling fluid.

[0048] Comparative Example 5 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: acrylic acid is not added to prepare the wall stabilizing agent to obtain a wall stabilizing agent D5 for water-based drilling fluid.

[0049] Comparative Example 6 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: N-methylolacrylamide is not added to obtain a wall stabilizing agent D6 for water-based drilling fluid.

[0050] Comparative Example 7 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is not added to obtain a wall stabilizing agent D7 for water-based drilling fluid.

[0051] Comparative Example 8 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: octadecyl vinyl ether is not added to obtain a wall stabilizing agent D8 for water-based drilling fluid.

[0052] Comparative Example 9 The preparation method of a wall stabilizing agent for water-based drilling fluid is as described in Example 1, except that: the complexing agent is not added to obtain a wall stabilizing agent D9 for water-based drilling fluid.

[0053] Application Test Example 1: Evaluation of the Rheological Filtration Performance of Drilling Fluid Preparation of bentonite base slurry: At room temperature, 400 g of bentonite and 14.0 g of Na2CO3 are added to 10000 mL of deionized water, stirred at a rate of 3000 rpm for 2 h, and then left to stand and cure for 24 h to obtain bentonite base slurry.

[0054] Preparation of saturated salt bentonite base slurry: At room temperature, 144 g of NaCl is added to 400 mL of bentonite base slurry and stirred at a rate of 3000 rpm for 20 min to obtain saturated salt bentonite base slurry.

[0055] 8 g of the wall stabilizers A1 - A6 in the examples and D1 - D9 in the comparative examples were respectively added to 400 g of saturated salt bentonite base mud, and stirred at 6000 rpm for 20 min to obtain drilling fluids F1 - F6, DF1 - DF9.

[0056] The drilling fluids were filled into a stainless - steel aging tank and kept rolling at a constant temperature of 200 °C for 16 hours. After aging, they were cooled to room temperature and taken out, and stirred at 10000 rpm for 20 min. According to the petroleum and natural gas industry standard GB / T 29170 - 2012 "Petroleum and natural gas industry - Laboratory testing of drilling fluids", the apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), yield point (YP, Pa), and API fluid loss FL of the drilling fluids before and after high - temperature aging were measured. API , and the results are shown in Tables 1 - 2.

[0057] Table 1 Performance test of drilling fluids with wall stabilizers in examples

[0058] Table 2 Performance test of drilling fluids with wall stabilizers in comparative examples

[0059] It can be seen from the experimental results that when the addition amount of the wall stabilizer of the present invention in the saturated salt base mud is 2%, the apparent viscosity, plastic viscosity, and shear force of the saturated salt base mud before and after aging at 200 °C are all increased to a certain extent, and the fluid loss is greatly reduced. This shows that the strong - adsorption and high - cohesion cementing wall stabilizer of the present invention has good viscosity - increasing and shear - enhancing effects in the saturated salt base mud, and can effectively reduce the fluid loss. The wall stabilizer of the present invention contains strongly - adsorbing hydroxyl, amino, and carboxyl groups, enabling the wall stabilizer to tightly adsorb on the clay surface. The hydrophobic groups form an associative structure and jointly construct the internal network structure of the drilling fluid with the clay, maintaining the stability of the internal network structure of the drilling fluid under high - temperature and high - salt conditions. At the same time, the strong - adsorption and high - cohesion cementing wall stabilizer can participate in the formation of the mud cake, cement the internal water - loss pores and cracks in the mud cake, thereby effectively reducing the fluid loss. It can be seen from the comparative examples that the wall stabilizers lacking key monomers such as acrylic acid, N - hydroxymethylacrylamide, N-(2 - [3,4 - dihydroxyphenyl]ethyl)acrylamide, octadecyl vinyl ether and complexing agents, or the wall stabilizers prepared by reducing the dosage of key monomers, fail to achieve effective viscosity - increasing, shear - enhancing and fluid - loss - reducing effects.

[0060] Application test example 2: Evaluation of the plugging performance of drilling fluids Sand - bed plugging experiment: The drilling fluids F1 - F6 of the examples and DF1 - DF9 of comparative examples 1 - 9 were prepared according to the method in Application test example 1, aged at 200 °C for 16 h, cooled to room temperature and taken out. 300 cm was filled into the clean and transparent glass filling tube of the FA.BX type medium - pressure sand - bed plugging instrument. 3Quartz sand with a mesh size of 80, after paving and tamping, add 150 cm 3 The aged drilling fluid, measure the depth of the drilling fluid invading the sand bed at room temperature and 0.69 ± 0.03 MPa for 30 min.

[0061] Microfiltration membrane plugging experiment: Add the wellbore wall stabilizers A1 - A6 of the examples and the wellbore wall stabilizers D1 - D9 of Comparative Examples 1 - 9 into 400 mL of deionized water, and then add 144 g of NaCl to prepare saturated salt solutions FL1 - FL6 and DFL1 - DFL9 containing the wellbore wall stabilizers. Load FL1 - FL6 and DFL1 - DFL9 into a stainless - steel aging tank and age at 200 °C for 16 h. After cooling to room temperature, take out and measure the API filtration loss of FL1 - FL6 and DFL1 - DFL9 at 25 °C and 100 psi. The filter paper uses a polytetrafluoroethylene microfiltration membrane with a pore size of 1 μm, and the results are shown in Table 3.

[0062] Table 3 Drilling fluid plugging performance test

[0063] It can be seen from the experimental results that when the wellbore wall stabilizer of the present invention is not added, the drilling fluid filtrate completely penetrates the sand bed. After adding the wellbore wall stabilizer of the present invention, the invasion depth of the drilling fluid into the sand bed is reduced, and the microfiltration membrane plugging experiment also shows the same result. It shows that the wellbore wall stabilizer of the present invention has excellent plugging effect and can effectively prevent the filtration loss of the drilling fluid to the high - permeability layer. If the key monomer or key material is lacking in the wellbore wall stabilizer of the present invention, the plugging effect will become worse.

[0064] Application Test Example 3: Drilling fluid wellbore wall performance test Compressive strength test: Immerse shale columns (25 cm × 30 cm) in drilling fluids F1 - F6 and DF1 - DF9 (prepared according to the method in Application Test Example 1) respectively, and let them stand and age at 200 °C for 16 h. After the aging time ends, cool to room temperature, vacuum - dry the taken - out shale columns at 90 °C for 12 h, and measure their compressive strength. The experimental results are shown in Table 4.

[0065] Point - load strength test: Immerse shale slices (25 mm × 3 mm) in the drilling fluids F1 - F6 of the examples and the drilling fluids DF1 - DF9 of the comparative examples (prepared according to the method in Application Test Example 1) respectively, and let them stand and age at 200 °C for 16 h. After the aging time ends, cool to room temperature, vacuum - dry the shale slices at 90 °C for 12 h, and use the nano - indentation module of a multi - functional surface tester to measure the point - load strength of the shale slices. Use a 60 °C triangular pyramid diamond indenter, with a load increase rate of 100 N / min and a maximum load of 200 N. The experimental results are shown in Table 4.

[0066] Lap shear strength test: For the drilling fluids F1 - F6 of the examples and the drilling fluids DF1 - DF9 of the comparative examples (prepared according to the method in Application Test Example 1), in accordance with "Determination Method for Tensile Shear Strength of Adhesives" (GB7124 - 2008) and "Determination Method for Chemical Reagent Resistance Performance of Adhesives" (GB / T13353 - 92), the above - mentioned drilling fluids were evenly spread on the single lap surface of an artificial lap specimen (shale piece). The lap specimen was pressed at 10 ± 0.5 MPa for 2 h, then placed in a vacuum dryer at 90 °C for 12 h. A tensile force was applied parallel to the lap surface and in the main axis direction of the specimen to test the lap shear strength of the specimen. The experimental results are shown in Table 4.

[0067] Table 4. Test on the Wall - stabilizing Performance of Drilling Fluids

[0068] It can be seen from the experimental results that the wall - stabilizing agents of the present invention are all beneficial to improving the strength of the core and have excellent wall - stabilizing performance. The wall - stabilizing agents of the present invention contain strong adsorption groups such as hydroxyl, amino, and carboxyl groups, and have strong adhesion to the rock surface. When the wall - stabilizing agent adsorbs on the rock surface and inside the pore - fissures, on the one hand, the wall - stabilizing agent can block the pore - fissures of the rock, consolidate the core through strong cohesive force, and maintain the rock strength; on the other hand, the hydrophobic groups of the wall - stabilizing agent can form a hydrophobic layer on the rock surface, producing an isolation effect on water molecules and maintaining the bonding force between the wall - stabilizing agent and the rock. During the drilling process, the wall - stabilizing agents of the present invention can adsorb and block the micro - pore - fissures inside the rock, and then cement the rock, maintain the compressive strength of the rock, prevent the drilling fluid from invading the formation inside, and effectively prevent the collapse of the wellbore.

[0069] In summary, the strong - adsorption and high - cohesion cementing wall - stabilizing agent of the present invention has a temperature resistance of up to 200 °C and a salt resistance of up to saturation. It has good viscosity - increasing, gel - strength - increasing, and filtration - loss reducing effects under high - temperature and high - salt conditions. It can effectively adsorb, block, and cement the micro - pores and micro - cracks inside the rock, maintain the stability of the wellbore, prevent the loss of drilling fluid, and provide strong technical support for the safe and efficient drilling of deep wells.

[0070] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above - mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0071] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above - mentioned specific embodiments can be combined in any suitable way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0072] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should equally be regarded as the content disclosed by the present invention.

Claims

1. A preparation method of a temperature-resistant and salt-tolerant wall stabilizing agent for a water-based drilling fluid in ten-thousand-meter deep well, which is characterized in that, It includes the following steps: (1) Add acrylic acid into deionized water, adjust the pH of the system to 7.0, and then successively add N-methylolacrylamide, N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, an emulsifier, octadecyl vinyl ether, and a complexing agent into the system, and perform shearing to make the monomers disperse evenly to obtain a monomer solution; the mass ratio of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, N-methylolacrylamide, acrylic acid, and octadecyl vinyl ether is 5-10:10-20:5-10:1-5; the emulsifier is any one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, Tween 80, and Span 80; the mass ratio of the emulsifier to octadecyl vinyl ether is 0.01-0.03:1-5; the complexing agent is ferric chloride hexahydrate, zinc chloride, magnesium chloride, or calcium chloride; the mass ratio of the complexing agent to N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is 0.3-0.8:5-10; (2) Add an initiator into the monomer solution and carry out a reaction; after the reaction is completed, wash, dry, and pulverize to obtain a temperature-resistant and salt-tolerant wall stabilizer for a 10,000-meter deep water-based drilling fluid; the initiator is a composition of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride, wherein the mass ratio of ammonium persulfate, sodium bisulfite, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride is 5-8:2-4:8-12, and the mass ratio of the initiator to N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is 0.15-0.25:5-10.

2. The preparation method of the high-temperature and salt-resistant wall stabilizing agent for the ten-thousand-meter deep well water-based drilling fluid according to claim 1, wherein, In step (1), the mass ratio of the deionized water to acrylic acid is 60-120:5-10; use sodium hydroxide or potassium hydroxide to adjust the pH of the system to 7.

3. The preparation method of the temperature-resistant and salt-tolerant wall stabilizing agent for the 10,000-meter deep water-based drilling fluid according to claim 1, characterized in that In step (1), the shearing rate is 1500-2500 rpm, and the shearing time is 10-30 min.

4. The preparation method of the high-temperature and salt-resistant wall stabilizing agent for the 10,000-meter deep well water-based drilling fluid according to claim 1, wherein, In step (1), N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide is prepared according to the following method: Add 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride into methanol, stir until the solid dissolves to obtain solution 1; add acryloyl chloride into tetrahydrofuran, stir and dissolve to obtain solution 2; add triethylamine into methanol, stir evenly to obtain solution 3; dropwise add solution 2 and solution 3 into solution 1, and after the dropping is completed, carry out a reaction to obtain N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide.

5. The preparation method of the high-temperature and salt-resistant wall stabilizing agent for the ten-thousand-meter deep well water-based drilling fluid according to claim 4, characterized in that, In the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, the mass ratio of methanol to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride in Solution 1 is 70-130:8-15; the mass ratio of acryloyl chloride to tetrahydrofuran in Solution 2 is 4.5-6.5:4.2-5.5; the mass ratio of triethylamine to methanol in Solution 3 is 13-18:20-35; the mass ratio of acryloyl chloride to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride is 4-6:10-15; the mass ratio of triethylamine to 2-(3,4-dihydroxyphenyl)ethylamine hydrochloride is 1-2:

1.

6. The preparation method of the temperature-resistant and salt-tolerant wall stabilizing agent for the ten-thousand-meter deep well water-based drilling fluid according to claim 4, characterized in that, In the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, Solution 2 and Solution 3 are simultaneously added dropwise to Solution 1 at 0-5°C, and the dropping time is 15-20 min; the reaction temperature is 20-30°C, and the reaction time is 5-7 h; the reaction is carried out under a nitrogen atmosphere.

7. The preparation method of the temperature-resistant and salt-tolerant wall stabilizing agent for the 10,000-meter deep well water-based drilling fluid according to claim 4, characterized in that, In the preparation of N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide, after the reaction is completed, a post-treatment step is also included, which is specifically as follows: the obtained reaction solution is removed of the solvent, ethyl acetate is added, the organic phase is washed with a mixed solution containing HCl and NaCl, dried over anhydrous sodium sulfate, filtered, and the solvent is removed, and the obtained product is vacuum dried at 100-110°C to constant weight to obtain N-[2-(3,4-dihydroxyphenyl)ethyl]-2-propenamide; the mass ratio of HCl to NaCl in the mixed solution is 7-9:10-12, and the concentration of HCl in the mixed solution is 0.5-1.5 mol / L.

8. The preparation method of the high-temperature and salt-resistant wall stabilizing agent for the 10,000-meter deep well water-based drilling fluid according to claim 1, characterized in that, In step (2), the reaction temperature is 70-80°C, and the reaction time is 5-7 h; the washing is carried out 2-3 times with methanol, and the drying is carried out to constant weight at 70-80°C.

9. An anti-temperature and salt-resistant wall stabilizing agent for water-based drilling fluid in 10,000-meter deep well, characterized in that, Prepared by using the preparation method described in any one of claims 1-8.

10. Use of the high-temperature and salt-resistant wall stabilizing agent for ten-thousand-meter deep water-based drilling fluid according to claim 9 in a water-based drilling fluid for stabilizing the wellbore and preventing leakage, characterized in that, The mass concentration of the temperature-resistant and salt-tolerant wall stabilizer for 10,000-meter deep water-based drilling fluid in the water-based drilling fluid is 1-3 wt%.

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