CN117736708A - An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt and its preparation method and application - Google Patents

Abstract

The invention provides 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid and a preparation method and application thereof. The 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid comprises the following raw materials in parts by weight: 100 parts of water, 1-4 parts of composite soil cutting agent, 0.2-0.6 part of sodium hydroxide, 3-6 parts of high temperature resistant and salt resistant zwitterionic polymer, 2-4 parts of high temperature resistant and salt resistant anionic polymer, 3-5 parts of alcohol amine inhibitor, 6-10 parts of organic-inorganic hybrid microsphere plugging agent, 2-4 parts of strong adsorption collapse prevention plugging agent, 3-4 parts of composite grease lubricant and 0.5-1 part of system stabilizer. The water-based drilling fluid can keep good rheological property, fluid loss and plugging anti-collapse performance under the conditions of more than 220 ℃ saturated sodium chloride and 3% calcium chloride. The drilling fluid system does not contain sulfonated materials, the used treating agent has strong high-temperature and high-salt resistance, does not decompose under the conditions of high temperature and high salt, and has good environmental protection performance.

Description

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt and its preparation method and application

Technical field

The invention relates to a 220°C saturated salt-resistant, environmentally friendly water-based drilling fluid and its preparation method and application, and belongs to the technical field of drilling fluids.

Background technique

The deepest reservoirs in my country (Tarimu, Sichuan, Bohai Bay, etc.) are more than 9,000m deep, and the bottom hole temperature is 180 to 260°C. Ultra-deep wells have the characteristics of high temperature and pressure, complex geological conditions (mostly salt-gypsum layers exist), and multiple sets of pressure layers in the same open-hole section. At this stage, the temperature resistance of the drilling fluid system is generally lower than 220°C, and the salt content will increase significantly. Reduce the performance of drilling fluid. During the drilling process, drilling fluid failure often leads to major safety accidents such as well collapse, stuck pipe, well leakage, blowout, etc., resulting in high drilling costs and easy to cause reservoir damage, which has a major impact on deep oil and gas development. . The research and development of an ultra-high-temperature and high-salt drilling fluid technology can increase the drilling speed, reduce the occurrence of downhole complications, maintain the smooth progress of my country's deep and ultra-deep oil and gas exploration and development strategic tasks, and lay a technical foundation for future deep-earth drilling projects, which is of important economic importance. and social significance.

Oil-based drilling fluids have good performance in terms of high-temperature stability, filter loss reduction, and lubricity. However, the difficulty in obtaining raw materials, high economic costs, and serious environmental pollution are the fundamental flaws of oil-based drilling fluids. Treatment agents such as sulfonated lignite and sulfonated phenolic resin in common high-temperature and high-salt water-based drilling fluid systems such as trisulfonate systems and polysulfonate systems are themselves toxic and have poor biodegradability. After high-temperature aging, the treatment agents decompose and release Toxic and odorous gases seriously pollute the environment and are difficult to use in areas with strict environmental protection requirements. How to improve the temperature and salt resistance of drilling fluids while maintaining environmental protection is an issue that cannot be ignored.

Chinese patent document CN104559968A discloses a high-temperature resistant water-based drilling fluid and its preparation method. The system is composed of base slurry and high softening point asphalt liquid, and can only withstand a temperature of 150°C. Chinese patent document CN108641683A discloses a high-temperature resistant, high-salinity, high-density water-based drilling fluid and its application. However, the high-temperature and high-pressure filter loss of this system under saturated salt conditions at 220°C is 21.6 mL, and the drilling fluid performance needs to be improved; Moreover, a large amount of sulfonated materials are added to the system, which results in poor environmental performance. Chinese patent document CN114891489A discloses a non-sulfonated high-temperature resistant water-based drilling fluid. The drilling fluid system does not contain sulfonated materials, is safe and environmentally friendly, and can withstand temperatures above 200°C, but does not show salt resistance. None of the above drilling fluids can meet the requirements of temperature resistance, salt resistance and environmental protection at the same time, and it is difficult to provide support for deep oil and gas drilling.

Contents of the invention

In view of the shortcomings of the existing technology, especially the problems that the current deep formation water-based drilling fluid has weak temperature resistance, high salinity resistance and poor environmental performance, the present invention provides an environmentally friendly water-based water-based drilling fluid resistant to 220°C saturated salt. Drilling fluid and its preparation methods and applications. The water-based drilling fluid of the present invention can maintain good rheology, filter loss, sealing and anti-collapse properties under the conditions of 220°C and above, saturated sodium chloride, and 3% calcium chloride. The drilling fluid system does not contain sulfonated materials, and the treatment agent used has strong resistance to high temperature and high salt, does not decompose under high temperature and high salt conditions, and has good environmental performance.

The present invention is achieved through the following technical solutions:

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, including the following raw material components by weight: 100 parts of water, 1-4 parts of composite soil cutting agent, 0.2-0.6 parts of sodium hydroxide, and high-temperature and salt-resistant amphoteric ions 3-6 parts of polymer, 2-4 parts of high temperature and salt resistant anionic polymer, 3-5 parts of alcoholamine inhibitor, 6-10 parts of organic-inorganic hybrid microsphere blocking agent, strong adsorption and anti-collapse blocking agent 2-4 parts, 3-4 parts of compound grease lubricant, 0.5-1 part of system stabilizer.

According to the preferred embodiment of the present invention, the composite soil cutting agent is obtained by mixing bentonite, attapulgite, diatomaceous earth, volcanic stone powder and sepiolite. Preferably, the mass ratio of bentonite, attapulgite, diatomite, volcanic stone powder and sepiolite is 1-3:1:0.1-1:0.1-1:0.1-1, preferably 2:1:0.5:0.5 :0.5.

According to the preferred embodiment of the present invention, the high-temperature-resistant and salt-resistant zwitterionic polymer is prepared by including the following parts by weight of raw materials: 15-25 parts by weight of N,N-dimethylacrylamide, 2-acrylamido-2-methyl 5-15 parts of propanesulfonic acid, 120-140 parts of water, 10-20 parts of methacryloyloxyethyltrimethylammonium chloride, TPEG-2400 (methallyl polyoxyethylene ether-2400) 10- 20 parts, 5-10 parts of 1-vinylimidazole, 0.1-1 part of N,N,N',N'-tetramethylethylenediamine, 0.1-0.5 part of ammonium persulfate, 0.01-0.1 part of sodium bisulfite .

Preferably, the high-temperature-resistant and salt-resistant zwitterionic polymer includes the following parts by weight of raw materials: 20 parts of N,N-dimethylacrylamide, 10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 130 parts of water, 15 parts of methacryloyloxyethyltrimethylammonium chloride, 15 parts of TPEG-2400, 8 parts of 1-vinylimidazole, N,N,N',N'-tetramethylethylenediamine 0.5 parts, ammonium persulfate 0.25 parts, sodium bisulfite 0.05 parts.

Preferably, the preparation method of the high-temperature-resistant and salt-resistant zwitterionic polymer includes the steps:

Fully disperse N,N-dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid in water, use 40-60wt% NaOH aqueous solution to adjust the pH to 7-8; add methacryloxyethyl Trimethylammonium chloride, TPEG-2400, 1-vinylimidazole and N,N,N',N'-tetramethylethylenediamine, fully dispersed; add ammonium persulfate and sodium bisulfite mixed initiator , undergo a stirring reaction, and then wash, dry, and pulverize to obtain a high-temperature-resistant and salt-resistant zwitterionic polymer.

Preferably, the stirring reaction temperature is 60-70°C, the stirring reaction time is 3-8 hours, and the stirring reaction is carried out under the protection of nitrogen or argon.

According to the preferred method of the present invention, the preparation method of the high-temperature-resistant and salt-resistant anionic polymer includes the steps:

(1) Dissolve sodium formaldehyde sulfoxylate in deionized water, add a dimethylamine aqueous solution with a concentration of 30-50wt%, react with stirring, centrifuge to remove the precipitate, and dry to obtain sodium (dimethylamine) methanesulfonate;

(2) Dissolve sodium (dimethylamine) methanesulfonate in an aqueous ethanol solution to obtain a sodium (dimethylamine) methanesulfonate solution; dissolve 4-chloromethylstyrene in absolute ethanol to obtain 4-chloromethylstyrene. Methyl styrene solution; add sodium (dimethylamine) methanesulfonate solution dropwise to the 4-chloromethylstyrene solution, react with stirring, filter, wash, dry and pulverize to obtain betaine monomer;

(3) Fully disperse N,N-dimethylacrylamide, betaine monomer, and 2-acrylamido-2-methylpropanesulfonic acid in deionized water, add initiator potassium persulfate, and perform free radical polymerization reaction, and then washed, dried, and pulverized to obtain a high-temperature-resistant and salt-resistant anionic polymer.

Preferably, in step (1), the mass ratio of sodium formaldehyde sulfoxylate, deionized water and dimethylamine aqueous solution is 1:3-5:1-3, preferably 1:4:2.

Preferably, in step (1), the stirring reaction temperature is 25-35°C, and the stirring reaction time is 70-75h.

Preferably, in step (2), the mass ratio of ethanol to water in the ethanol aqueous solution is 1:1.

Preferably, in step (2), the mass ratio of sodium (dimethylamine) methanesulfonate, ethanol aqueous solution, 4-chloromethylstyrene, and absolute ethanol is 6-8:90-110:3-8: 30-50, preferably 7:100:5:40.

Preferably, in step (2), the dropping time is 5-10 min; the stirring reaction temperature is 40-50°C, and the stirring reaction time is 20-30 h.

According to the present invention, in step (2), the preparation route of the betaine monomer is as follows:

Preferably, in step (3), the mass ratio of N,N-dimethylacrylamide, betaine monomer, 2-acrylamido-2-methylpropanesulfonic acid, deionized water and potassium persulfate is 18 -25:6-10:6-10:90-110:0.1-0.3, preferably 21:8:8:100:0.15.

Preferably, in step (3), the free radical polymerization reaction temperature is 50-70°C, and the free radical polymerization reaction time is 4-8 hours.

According to the preferred embodiment of the present invention, the alcoholamine inhibitor is obtained by mixing polyetheramine D230, polyetheramine D400, polyethylene glycol 400, triethanolamine and pentaethylenehexamine.

Preferably, the mass ratio of polyetheramine D230, polyetheramine D400, polyethylene glycol 400, triethanolamine and pentaethylenehexamine is 1-3:1:1:0.1-0.5:0.1-0.3, preferably 2:1 :1:0.3:0.2.

According to the preferred embodiment of the present invention, the organic-inorganic hybrid microsphere blocking agent is prepared by including the following parts by weight of raw materials:

5-15 parts of sodium p-styrenesulfonate, 1-10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 100 parts of water, 0.1-0.5 parts of sodium dodecylbenzene sulfonate, KH-570 modified 1-3 parts of flexible nanosilica, 15-25 parts of styrene, 0.1-0.3 parts of initiator potassium persulfate, and 0.01-0.05 parts of cross-linking agent N,N′-methylenebisacrylamide.

Preferably, the organic-inorganic hybrid microsphere blocking agent is prepared by including the following parts by weight of raw materials:

10 parts of sodium p-styrenesulfonate, 5 parts of 2-acrylamido-2-methylpropanesulfonic acid, 100 parts of water, 0.3 parts of sodium dodecylbenzene sulfonate, KH-570 modified nanosilica 2 parts, 20 parts of styrene, 0.2 parts of initiator potassium persulfate, and 0.02 parts of cross-linking agent N,N′-methylenebisacrylamide.

According to the present invention, KH-570 modified nanosilica can be commercially available or prepared according to existing methods.

Preferably, the preparation method of the organic-inorganic hybrid microsphere blocking agent includes the steps:

1) Fully disperse sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid, sodium dodecylbenzenesulfonate, and KH-570 modified nanosilica in water to obtain solution a ;

2) Under stirring conditions, add styrene dropwise into solution a, stir at room temperature for 20-40 minutes to form an emulsion; under stirring conditions, add initiator potassium persulfate and cross-linking agent N,N'-methylene bis Acrylamide, through stirring reaction, can obtain organic-inorganic hybrid microsphere blocking agent.

Further preferably, in step 2), before using styrene, there is also a step of washing away the MEHQ polymerization inhibitor using a NaOH aqueous solution with a mass concentration of 40-60%.

Further preferably, in step 2), the stirring reaction temperature is 65-75°C, the stirring reaction time is 5-8 hours, and the stirring reaction is carried out under the protection of nitrogen or argon.

According to the preferred embodiment of the present invention, the strong adsorption anti-collapse blocking agent is prepared by including the following raw materials in parts by weight: 5-15 parts of methacrylic acid, 100-140 parts of water, 1-10 parts of N-vinylpyrrolidone, methane 10-30 parts of methyl acrylate, 1-10 parts of lauryl methacrylate, 1-5 parts of divinylbenzene, and 0.05-0.5 parts of initiator potassium persulfate.

Preferably, the strong adsorption anti-collapse blocking agent is prepared by including the following raw materials by weight: 10 parts of methacrylic acid, 120 parts of water, 5 parts of N-vinylpyrrolidone, 20 parts of methyl methacrylate, methyl 5 parts of lauryl acrylate, 3 parts of divinylbenzene, 0.1 part of initiator potassium persulfate.

Preferably, the preparation method of the strong adsorption anti-collapse blocking agent includes the steps:

1) Fully disperse methacrylic acid and N-vinylpyrrolidone in water to obtain mixed solution 1;

2) Thoroughly mix methyl methacrylate, lauryl methacrylate and divinylbenzene, and use a NaOH aqueous solution with a mass concentration of 40-60% to wash away the polymerization inhibitor MEHQ to obtain mixed solution 2;

3) Under stirring conditions, add mixed liquid 2 dropwise to mixed liquid 1, add initiator potassium persulfate, and obtain a strong adsorption anti-collapse blocking agent after stirring and reaction.

Further preferably, in step 3), the stirring reaction temperature is 60-70°C, the stirring reaction time is 4-6 hours, and the stirring reaction is carried out under the protection of nitrogen or argon.

According to the preferred embodiment of the present invention, the composite grease lubricant is obtained by mixing glycerin oleate materials, castor oil and SP-60. Preferably, the mass ratio of glyceryl oleate materials, castor oil and SP-60 is 1:1:0.1-1, preferably 1:1:0.5.

Preferably, the glyceryl oleate material is selected from one or a combination of two or more of glycerol monooleate, glyceryl dioleate or glyceryl trioleate.

According to the preferred embodiment of the present invention, the system stabilizer is obtained by mixing Span-80, Tween-80 and OP-10. Preferably, the mass ratio of Span-80, Tween-80 and OP-10 is 1-3:1:1, preferably 2:1:1.

The preparation method of the above-mentioned 220°C saturated salt-resistant environmentally friendly water-based drilling fluid includes the steps:

Fully disperse the composite soil cutting agent and sodium hydroxide in the water, and then add the high-temperature-resistant and salt-resistant zwitterionic polymer, the high-temperature resistant and salt-resistant anionic polymer, the alcoholamine inhibitor, and the organic-inorganic hybrid microsphere blocking agent in sequence. , strong adsorption anti-collapse plugging agent, compound grease lubricant and system stabilizer, fully dispersed and evenly obtained to obtain an environmentally friendly water-based drilling fluid resistant to 220°C saturated salt.

According to the preferred method of the present invention, the preparation method of the 220°C saturated salt-resistant environmentally friendly water-based drilling fluid includes the following steps:

Add water to the high-speed mixing cup, add compound soil cutting agent and sodium hydroxide under low-speed stirring, stir at low speed for 24-48 hours; add high-temperature and salt-resistant zwitterionic polymer, stir at high speed for 20 minutes; add high-temperature and salt-resistant anionic polymer material, stir at high speed for 20 minutes; add alcohol amine inhibitor, stir at high speed for 20 minutes; add organic-inorganic hybrid microsphere blocking agent, stir at high speed for 20 minutes; add strong adsorption anti-collapse blocking agent, stir at high speed for 20 minutes; add complex grease lubricant , stir at high speed for 20 minutes; add system stabilizer, stir at high speed for 20 minutes, and obtain an environmentally friendly water-based drilling fluid that is resistant to 220°C saturated salt.

Preferably, the low-speed stirring speed is 1000-3000r/min, and the high-speed stirring speed is 8000-10000r/min.

The application of the above-mentioned environmentally friendly water-based drilling fluid resistant to 220°C saturated salt is used in deep or ultra-deep drilling processes to balance formation pressure, seal formation fractures, lubricate drill bits, carry cuttings, inhibit clay mineral expansion, and stabilize Well wall and other functions.

The technical features and beneficial effects of the present invention are as follows:

(1) The 220°C saturated salt-resistant and environmentally friendly water-based drilling fluid of the present invention consists of a composite soil-lifting agent, a high-temperature and salt-resistant zwitterionic polymer, a high-temperature and salt-resistant anionic polymer, an alcoholamine inhibitor, and an organic-inorganic hybrid. It is composed of core treatment agents such as chemical microsphere sealing agent, strong adsorption anti-collapse sealing agent, and compound grease lubricant. Composite soil cutting agent, high temperature and salt resistant zwitterionic polymer and high temperature and salt resistant anionic polymer can synergize and play a good role in reducing fluid loss and maintaining good rheological properties of drilling fluid under ultra-high temperature and high salt conditions. . Organic-inorganic hybrid microsphere plugging agent and strong adsorption anti-collapse plugging agent further fill formation cracks and pores, reduce filtration loss, prevent filtrate from invading the formation, and maintain well wall stability. Alcoholamine inhibitors enhance the ability of drilling fluids to inhibit the expansion of clay minerals, and compound grease lubricants increase drill bit speed and prevent drill sticking. Under the synergistic effect of various treatment agents, the drilling fluid can still maintain good rheology and filter loss properties under high temperature and high salinity conditions, and can effectively seal formation fractures, inhibit the expansion of clay minerals, maintain the stability of the well wall, and prevent the well wall from being damaged. Drilling accidents such as collapse, necking, and stuck drilling occur.

(2) The composite soil cutting agent of the present invention is made of bentonite, attapulgite, diatomaceous earth, volcanic stone powder and sepiolite in a specific proportion. On the basis of soil and sepiolite, high temperature resistant volcanic stone powder and salt-insensitive diatomaceous earth are added to further enhance the temperature and salt resistance of the cutting agent. The specific material ratio allows the composite soil to maintain good hydration and expansion under high temperature and high salt conditions, effectively absorb polymers in the drilling fluid, and maintain good rheological properties of the drilling fluid.

(3) The high-temperature-resistant and salt-resistant zwitterionic polymer in the drilling fluid system of the present invention is based on N,N-dimethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and methacryloyloxyethane. A branched zwitterionic copolymer made of trimethylammonium chloride, TPEG-2400, 1-vinylimidazole, and N,N,N',N'-tetramethylethylenediamine as synthetic monomers. The cationic groups in the molecular chain can electrostatically adsorb negatively charged clay particles, and combined with the hydration effect of the anionic groups, strengthen the hydration layer around the clay, thereby weakening the agglomeration between clay particles and improving the hydration rate of the clay particles. The proportion of clay particles enhances the compactness of the mud cake, thereby reducing filtration loss. There are many adsorption sites on it, and it can rotate in three-dimensional space and connect with multiple clay particles or polymer chains in different directions to form a strong three-dimensional grid structure that is resistant to temperature and salt inside the drilling fluid, improving the drilling fluid. The cutting force enhances its rock-carrying ability. The three-dimensional grid keeps the drilling fluid clay well dispersed, and the drilling fluid still has good rheological properties and filter loss properties after long-term high-temperature aging. Only the specific raw material composition of the present invention can prepare the high-temperature-resistant and salt-resistant zwitterionic polymer with the above-mentioned excellent properties of the present invention. The deletion or substitution of any monomer and the change of the ratio will reduce its performance.

(4) The high-temperature and high-salt-resistant anionic polymer of the present invention is prepared by free radical polymerization of N,N-dimethylacrylamide, 2-acrylamido-2-methylpropanesulfonic acid and betaine monomers. Anionic polymer. A specific amount and a specific type of betaine monomer are added to the high-temperature-resistant and high-salt anionic polymer of the present invention, which has both quaternary ammonium cationic groups and sulfonate groups, allowing the polymer to be tightly adsorbed at high temperatures. On the clay surface, it maintains the colloidal stability of clay under high temperature and high salt conditions, effectively fills the water loss channels inside the mud cake, and reduces filtration loss. The betaine monomer with a specific structure and dosage of the present invention, combined with other raw materials, can work together to prepare the high-temperature and high-salt-resistant anionic polymer with excellent performance of the present invention; the deletion or substitution of any monomer and the change of the proportion will cause Its performance is reduced.

(5) The organic-inorganic hybrid microsphere sealing agent in the drilling fluid of the present invention has a flexible polymer soft shell on the outside, which has high elasticity and toughness and can adapt to the size and shape of fractures in the formation to achieve efficient and dense filling. . The sulfonic acid group in the polymer soft shell molecular chain has strong hydration characteristics, and the benzene ring improves the high temperature and salt resistance of the molecule. The core is temperature and salt resistant rigid nano-silica, which serves as a supporting skeleton to facilitate sealing. The strength of the agent increases. Under the action of pressure difference, the plugging agent can not only reduce the filtration loss of drilling fluid, but also fill and deposit around the well wall. It cooperates with the rigid plugging agent to form a strong pressure-bearing plugging layer, thereby preventing pressure transmission. and filtrate intrusion. The blocking agent with the above-mentioned excellent performance of the present invention is prepared from the raw materials of a specific composition. The deletion or replacement of any raw materials and the change of the proportion will reduce its performance.

(6) The main chain of the strong adsorption anti-collapse plugging agent molecule in the drilling fluid of the present invention is a long carbon chain composed of high bond energy C-C covalent bonds, which is not easy to break under high temperature conditions and not easy to twist under high salt conditions; and the interchain It has large steric hindrance and can form a hydrophobic association structure in water, which improves the temperature and salt resistance of the blocking agent. The molecular chain of the plugging agent contains a large number of hydrophilic and strong adsorption groups such as amide groups, which is beneficial to the dispersion of the plugging agent in the drilling fluid and its adsorption in the formation. Polymer microspheres (organic-inorganic hybrid microsphere plugging agent, strong adsorption anti-collapse plugging agent) can be well dispersed in the drilling fluid, can enter the leakage channel, automatically fill, and form a seal with anti-erosion and anti-breakage capabilities. The anti-collapse sealing layer enhances the sealing performance of drilling fluid under high temperature and high salt conditions and maintains the stability of the well wall. The blocking agent with the above-mentioned excellent performance of the present invention is prepared from the raw materials of a specific composition. The deletion or replacement of any raw materials and the change of the proportion will reduce its performance.

(7) The drilling fluid of the present invention is added with an environmentally friendly composite grease lubricant that is resistant to high temperatures and insensitive to salinity, and a system stabilizer is added to enhance the stability of the drilling fluid in a high temperature and high salinity environment, making the drilling fluid It can still maintain good performance under high temperature and high salinity. Only the composite grease lubricant and system stabilizer composed of specific raw materials of the present invention can achieve the excellent effects of the present invention. The lack or replacement of any raw materials and the change of the ratio will reduce its performance.

(8) The polymer in the drilling fluid of the present invention has a unique molecular structure and can form a strong three-dimensional grid structure that is resistant to temperature and salt inside the drilling fluid. The clay in the drilling fluid can remain well dispersed and can drill wells after long-term high-temperature aging. The fluid still has good rheological properties and filter loss properties; the drilling fluid of the present invention can achieve adaptive plugging of the formation, form an anti-collapse plugging layer with anti-scouring and anti-breakage capabilities, reduce filtrate intrusion, and further reduce filtration. Loss of volume; the microemulsion structure is formed in the drilling fluid of the present invention, which enhances the suspension of solid particles, maintains the stability of the drilling fluid, and enables the drilling fluid to increase to a higher density.

(9) The water-based drilling fluid of the present invention can maintain good rheology, filter loss, sealing and anti-collapse properties under the conditions of 220°C and above, saturated sodium chloride, and 3% calcium chloride. Each component of the invention works together to achieve synergistic effects, can meet the needs of safe and efficient drilling of deep oil and gas formations, and is simple in configuration, safe and environmentally friendly, and easy to maintain. The drilling fluid system of the present invention can be used in various drilling and mining operations and can exert good effects. Moreover, the drilling fluid system does not contain sulfonated materials, and the treatment agent used has strong resistance to high temperature and salt, does not decompose under high temperature and high salt conditions, has good environmental performance, and can be promoted and used in areas with strict environmental protection requirements. The drilling fluid of the present invention maintains the smooth progress of the strategic tasks of deep and ultra-deep oil and gas exploration and development in my country and lays a technical foundation for future deep-earth drilling projects, which has important economic and social significance.

Detailed ways

The specific embodiments of the present invention will be further described below. The present invention can be better understood according to the following examples. However, those skilled in the art can easily understand that the specific material proportions, process conditions and results described in the examples are only for illustrating the present invention, and should not and will not limit the invention as described in detail in the claims. . At the same time, in the following examples and comparative examples, unless otherwise specified, the materials used are all commercially available, and the methods used are conventional methods in this field.

The "parts" mentioned in the following preparation examples and examples are all parts by weight unless otherwise specified.

Preparation Example 1

The preparation method of the high temperature and salt resistant zwitterionic polymer is as follows:

1) Add 20 parts of N,N-dimethylacrylamide and 10 parts of 2-acrylamido-2-methylpropanesulfonic acid to 130 parts of water, stir under magnetic stirring at 300 rpm until fully dispersed, and adjust with 50wt% NaOH aqueous solution pH to 7.5;

2) Add 15 parts of methacryloyloxyethyltrimethylammonium chloride and 15 parts of TPEG-2400 in sequence, stir under magnetic stirring at 300 rpm until fully dispersed, and transfer the liquid to a three-necked flask;

3) Raise the temperature to 65°C, add 8 parts of 1-vinylimidazole and 0.5 parts of N,N,N',N'-tetramethylethylenediamine, and stir thoroughly with magnetic stirring at 300 rpm until dispersed;

4) After flowing nitrogen for 20 minutes, add 0.25 parts of ammonium persulfate and 0.05 parts of sodium bisulfite mixed initiators to initiate the reaction, and maintain a constant temperature reaction of 65°C for 5 hours under magnetic stirring at 300 rpm;

3) After the reaction, wash the reaction product three times with acetone, dry it in a 90°C oven for 10 hours and then pulverize it. The obtained light yellow powder is a high-temperature and salt-resistant zwitterionic polymer.

Preparation Example 2

The preparation method of the high-temperature-resistant and salt-resistant anionic polymer is as follows:

1) Dissolve 5 parts of sodium formaldehyde sulfoxylate in 20 parts of deionized water, add 10 parts of dimethylamine aqueous solution (concentration: 40wt%), stir and react at 30°C for 72 hours, centrifuge to remove the supernatant after the reaction is completed, Take out the light yellow precipitate and dry it under vacuum at 45°C for 12 hours to obtain sodium (dimethylamine) methanesulfonate.

2) Dissolve 7 parts of sodium (dimethylamine) methanesulfonate in 100 parts of aqueous ethanol solution (the mass ratio of ethanol to water in the aqueous ethanol solution is 1:1) to obtain solution 1. Dissolve 5 parts of 4-chloromethylstyrene in 40 parts of absolute ethanol to obtain solution 2; add 1 drop of solution into solution 2, the dropping time is 8mim, after the dropwise addition is completed, stir magnetically at 45°C and 300rpm The reaction was carried out for 24 hours. After the reaction, it was filtered. The solid obtained was washed three times with acetonitrile, vacuum dried at 60°C for 12 hours, and crushed to obtain betaine monomer.

3) Add 21 parts of N,N-dimethylacrylamide, 8 parts of betaine monomer, and 8 parts of 2-acrylamide-2-methylpropanesulfonic acid to 100 parts of deionized water, and stir for 5 minutes until sufficient Disperse, heat to 60°C, add 0.15 parts of initiator potassium persulfate, and perform free radical polymerization for 6 hours to obtain a viscous crude polymer;

4) Wash the crude polymer with acetone twice, dry it at 100°C for 24 hours, and crush it to obtain white powder, which is the high-temperature and salt-resistant anionic polymer.

Preparation Example 3

The preparation method of organic-inorganic hybrid microsphere blocking agent is as follows:

1) Weigh 10 parts of sodium p-styrenesulfonate and 5 parts of 2-acrylamido-2-methylpropanesulfonic acid, add 100 parts of water, stir at 300 rpm until fully dispersed, then add 0.3 parts of dodecyl Sodium benzenesulfonate, stir until fully dispersed,

2) Add 2 parts of KH-570 modified nano-silica to the liquid obtained in step 1), stir and disperse at 300 rpm, and then disperse with ultrasonic for 30 minutes. The ultrasonic temperature is controlled below 40°C to obtain solution a;

3) Weigh 20 parts of styrene, use a NaOH aqueous solution with a mass concentration of 50% to wash away the MEHQ polymerization inhibitor, and obtain solution b; under high-speed stirring above 500 rpm, add solution b dropwise to solution a, and keep stirring at room temperature for 30 minutes. form an emulsion;

4) Transfer the emulsion obtained in 3) to a three-necked flask, keep stirring, and deoxygenate with nitrogen for 30 minutes; raise the temperature to 70°C, add 0.2 parts of the initiator potassium persulfate and 0.02 parts of the cross-linking agent N,N'-methylene Base bisacrylamide, stir and react with nitrogen for 7 hours; after the reaction is completed, keep stirring, stop heating, and wait until the temperature drops to 20-30°C to obtain the organic-inorganic hybrid microsphere blocking agent.

Preparation Example 4

The preparation method of strong adsorption anti-collapse sealing agent is as follows:

1) Weigh 10 parts of methacrylic acid, add 120 parts of water, stir until fully dispersed, then add 5 parts of N-vinylpyrrolidone, stir at 300rpm until fully dispersed; keep stirring, use nitrogen to deoxygenate for 30 minutes, and mix Liquid 1;

2) Weigh 20 parts of methyl methacrylate, 5 parts of lauryl methacrylate and 3 parts of divinylbenzene, stir until fully mixed, and then use a 50% NaOH aqueous solution to wash away the polymerization inhibitor MEHQ to obtain Mixture 2;

4) Under stirring conditions, add mixed solution 2 dropwise to mixed solution 1, keep stirring at 500 rpm and heat to 65°C, add 0.1 part of the initiator potassium persulfate, and stir and react with nitrogen for 5 hours;

5) After the reaction is completed, keep stirring, stop heating, and lower the temperature to 30-40°C to obtain a strong adsorption anti-collapse blocking agent.

Preparation Comparative Example 1

The preparation method of the high temperature and salt resistant zwitterionic polymer is the same as Preparation Example 1, except that TPEG-2400 is not added; other steps and conditions are the same as Preparation Example 1.

Preparation Comparative Example 2

The preparation method of the high temperature and salt resistant zwitterionic polymer is the same as Preparation Example 1, except that TPEG-2400 is replaced by HPEG-2400; other steps and conditions are the same as Preparation Example 1.

Preparation Comparative Example 3

The preparation method of the high-temperature-resistant and salt-resistant anionic polymer is the same as Preparation Example 2, except that the betaine monomer is replaced by methacryloylethyl sulfobetaine; other steps and conditions are the same as Preparation Example 2.

Preparation Comparative Example 4

The preparation method of the high-temperature-resistant and salt-resistant anionic polymer is the same as Preparation Example 2, except that in step (2), 4-chloromethylstyrene is replaced by 2-chloromethylstyrene; other steps and conditions are the same as Preparation Example 2. 2.

Preparation Comparative Example 5

The preparation method of the organic-inorganic hybrid microsphere blocking agent is the same as that of Preparation Example 3, except that in step 1), 2-acrylamido-2-methylpropanesulfonic acid is not added; other steps and conditions are the same as those of preparation Example 3.

Preparation Comparative Example 6

The preparation method of the organic-inorganic hybrid microsphere blocking agent is the same as Preparation Example 3, except that in step 1), 2-acrylamido-2-methylpropanesulfonic acid is replaced by acrylamide; other steps and conditions Same as Preparation Example 3.

Example 1

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, including the following parts by weight of raw materials: 100 parts of water, 2 parts of composite soil cutting agent, 0.4 parts of sodium hydroxide, and high temperature and salt resistant zwitterionic polymer obtained in Preparation Example 1 4 parts of the material, 2 parts of the high-temperature-resistant and salt-resistant anionic polymer obtained in Preparation Example 2, 3 parts of the alcoholamine inhibitor, 8 parts of the organic-inorganic hybrid microsphere blocking agent obtained in Preparation Example 3, and the strong 2 parts of adsorption anti-collapse blocking agent, 3 parts of compound grease lubricant, and 0.5 parts of system stabilizer.

The composite soil cutting agent is obtained by mixing bentonite, attapulgite, diatomite, volcanic stone powder and sepiolite in a mass ratio of 2:1:0.5:0.5:0.5. The alcoholamine inhibitor is obtained by mixing polyetheramine D230, polyetheramine D400, polyethylene glycol 400, triethanolamine and pentaethylenehexamine in a mass ratio of 2:1:1:0.3:0.2. The composite grease lubricant is obtained by mixing glycerol monooleate, castor oil and SP-60 in a mass ratio of 1:1:0.5. The system stabilizer is obtained by mixing Span-80, Tween-80 and OP-10 in a mass ratio of 2:1:1.

The preparation method of the above-mentioned 220°C saturated salt-resistant environmentally friendly water-based drilling fluid includes the steps:

According to the above proportion, add water to the high-speed mixing cup, add the composite soil cutting agent and sodium hydroxide under low-speed stirring, stir for 24 hours at low speed; add high-temperature and salt-resistant zwitterionic polymer, stir at high speed for 20 minutes; add anti-high temperature and anti-salt amphoteric polymer. Salt anionic polymer, stir at high speed for 20 minutes; add alcohol amine inhibitor, stir at high speed for 20 minutes; add organic-inorganic hybrid microsphere blocking agent, stir at high speed for 20 minutes; add strong adsorption anti-collapse blocking agent, stir at high speed for 20 minutes; add composite Grease lubricant, stir at high speed for 20 minutes; add system stabilizer, stir at high speed for 20 minutes, and prepare environmentally friendly water-based drilling fluid F1 that is resistant to 220°C saturated salt.

The low-speed stirring speed is 2000r/min, and the high-speed stirring speed is 10000r/min.

Example 2

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, including the following parts by weight of raw materials: 100 parts of water, 4 parts of composite soil cutting agent, 0.6 parts of sodium hydroxide, and high temperature and salt resistant zwitterionic polymer obtained in Preparation Example 1 6 parts of the material, 4 parts of the high-temperature-resistant and salt-resistant anionic polymer obtained in Preparation Example 2, 5 parts of the alcoholamine inhibitor, 10 parts of the organic-inorganic hybrid microsphere blocking agent obtained in Preparation Example 3, and the strong 4 parts of adsorption anti-collapse blocking agent, 4 parts of compound grease lubricant, and 1 part of system stabilizer.

Other raw material types and drilling fluid preparation methods are the same as in Example 1. An environmentally friendly water-based drilling fluid F2 that is resistant to 220°C saturated salt was prepared.

Example 3

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, including the following parts by weight of raw materials: 100 parts of water, 1 part of composite soil cutting agent, 0.2 parts of sodium hydroxide, and high temperature and salt resistant zwitterionic polymer obtained in Preparation Example 1 3 parts of the high-temperature and salt-resistant anionic polymer obtained in Preparation Example 2, 4 parts of alcoholamine inhibitors, 6 parts of the organic-inorganic hybrid microsphere blocking agent obtained in Preparation Example 3, 3 parts of adsorption anti-collapse blocking agent, 4 parts of compound grease lubricant, and 0.8 parts of system stabilizer.

Other raw material types and drilling fluid preparation methods are the same as in Example 1. An environmentally friendly water-based drilling fluid F3 that is resistant to 220°C saturated salt was prepared.

Example 4

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, as described in Example 1, except that the composite soil cutting agent is composed of bentonite, attapulgite, diatomaceous earth, volcanic stone powder and sepiolite. The mass ratio is 1:1:0.5:1:1, and the other raw material compositions are the same as in Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1 to prepare water-based drilling fluid F4.

Example 5

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, as described in Example 1, except that the composite grease lubricant is composed of glycerol monooleate, castor oil and SP-60 in a mass ratio of 1:1 :1 obtained by mixing; other raw material compositions are the same as in Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1, and the water-based drilling fluid F5 is prepared.

Example 6

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, as described in Example 1, except that the glyceryl monooleate in the composite grease lubricant is replaced by glyceryl dioleate; other raw material compositions are the same as in the implementation example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1 to prepare water-based drilling fluid F6.

Example 7

An environmentally friendly water-based drilling fluid resistant to 220°C saturated salt, as described in Example 1, except that the system stabilizer is composed of Span-80, Tween-80 and OP-10 in a mass ratio of 1:1:1 Obtained by mixing; other raw material compositions are the same as in Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1, and water-based drilling fluid F7 is prepared.

Comparative example 1

A water-based drilling fluid is as described in Example 1, except that no high-temperature and salt-resistant zwitterionic polymer is added; other raw material compositions are the same as in Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1, except that the step of adding a high-temperature-resistant and salt-resistant zwitterionic polymer is omitted; a water-based drilling fluid DF1 is obtained.

Comparative example 2

A water-based drilling fluid is as described in Example 1, except that no high-temperature and salt-resistant anionic polymer is added; the composition of other raw materials is the same as in Example 1.

The preparation method of the above-mentioned water-based drilling fluid is as described in Example 1, except that the step of adding high-temperature-resistant and salt-resistant anionic polymer is omitted; a water-based drilling fluid DF2 is obtained.

Comparative example 3

A water-based drilling fluid is as described in Example 1, except that no organic-inorganic hybrid microsphere plugging agent is added; other raw material compositions are the same as in Example 1.

The preparation method of the above-mentioned water-based drilling fluid is as described in Example 1, except that the step of adding organic-inorganic hybrid microsphere plugging agent is omitted; a water-based drilling fluid DF3 is obtained.

Comparative example 4

A water-based drilling fluid, as described in Example 1, except that the adsorption of the anti-collapse plugging agent is not enhanced; and the other raw material compositions are the same as those in Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1, except that the step of adding a strong adsorption anti-collapse plugging agent is omitted; a water-based drilling fluid DF4 is obtained.

Comparative example 5

A water-based drilling fluid is as described in Example 1, except that compound grease lubricant and system stabilizer are not added; other raw material compositions are the same as in Example 1.

The preparation method of the above-mentioned water-based drilling fluid is as described in Example 1, except that the steps of adding compound grease lubricant and system stabilizer are omitted; water-based drilling fluid DF5 is obtained.

Comparative example 6

A water-based drilling fluid, as described in Example 1, except that the high-temperature-resistant and salt-resistant zwitterionic polymer and the high-temperature and salt-resistant anionic polymer are replaced with 6 parts of the sulfonate copolymer fluid loss agent DSP- 1; Other raw material compositions are the same as in Example 1.

The preparation method of the above-mentioned water-based drilling fluid includes the steps:

Add water to the high-speed mixing cup, add the compound soil cutting agent and sodium hydroxide under low-speed stirring, stir at low speed for 24 hours; add sulfonate copolymer fluid loss agent DSP-1, stir at high speed for 20 minutes; add alcohol amine inhibitor , stir at high speed for 20 minutes; add organic-inorganic hybrid microsphere blocking agent, stir at high speed for 20 minutes; add strong adsorption anti-collapse blocking agent, stir at high speed for 20 minutes; add compound grease lubricant, stir at high speed for 20 minutes; add system stabilizer, stir at high speed Stir for 20 minutes to prepare water-based drilling fluid DF6.

The low-speed stirring speed is 2000r/min, and the high-speed stirring speed is 10000r/min.

Comparative example 7

A water-based drilling fluid, as described in Example 1, except that the high temperature and salt resistant zwitterionic polymer obtained in Preparation Example 1 is replaced with the high temperature and salt resistant zwitterionic polymer obtained in Preparation Comparative Example 1; others The raw material composition is the same as in Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF7.

Comparative example 8

A water-based drilling fluid, as described in Example 1, except that the high temperature and salt resistant zwitterionic polymer obtained in Preparation Example 1 is replaced with the high temperature and salt resistant zwitterionic polymer obtained in Preparation Comparative Example 2; others The raw material composition is the same as in Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF8.

Comparative example 9

A water-based drilling fluid, as described in Example 1, except that the high-temperature-resistant and salt-resistant anionic polymer obtained in Preparation Example 2 is replaced with the high-temperature and salt-resistant anionic polymer obtained in Preparation Comparative Example 3; other raw material compositions Same as Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF9.

Comparative example 10

A water-based drilling fluid, as described in Example 1, except that the high-temperature-resistant and salt-resistant anionic polymer obtained in Preparation Example 2 is replaced with the high-temperature and salt-resistant anionic polymer obtained in Preparation Comparative Example 4; other raw material compositions Same as Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF10.

Comparative example 11

A water-based drilling fluid, as described in Example 1, except that the organic-inorganic hybrid microsphere sealing agent obtained in Preparation Example 3 is replaced with the organic-inorganic hybrid microsphere sealing agent obtained in Preparation Comparative Example 5. Blocking agent; other raw material compositions are the same as in Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF11.

Comparative example 12

A water-based drilling fluid, as described in Example 1, except that the organic-inorganic hybrid microsphere sealing agent obtained in Preparation Example 3 is replaced with the organic-inorganic hybrid microsphere sealing agent obtained in Preparation Comparative Example 6. Blocking agent; other raw material compositions are the same as in Example 1.

The preparation method of water-based drilling fluid is the same as in Example 1 to prepare water-based drilling fluid DF12.

Comparative example 13

A kind of water-based drilling fluid, as described in Example 1, the difference is that the composite soil cutting agent is obtained by mixing bentonite, attapulgite, and diatomite in a mass ratio of 3:1:0.5; the other raw materials have the same composition Example 1.

The preparation method of the above water-based drilling fluid is as described in Example 1, and the water-based drilling fluid DF13 is prepared.

Test example 1

Take 400mL of the above-mentioned drilling fluids F1-F3 and DF1-DF6 respectively, use barite to weight it to 1.6g/cm ³ , add 36wt% NaCl and 3wt% CaCl ₂ , stir at 5000r/min for 20min, put it into an aging tank, and put it in the Put it into the roller furnace, roll it at constant temperature for 16 hours at 220°C, take it out and cool it to room temperature, stir it at 5000rpm for 20 minutes, and then follow the oil and natural gas industry standard GB/T 16783.1-2014 "Field test of drilling fluids in the oil and natural gas industry" Part 1: Water-based drilling fluid》Measurement of the apparent viscosity (AV, mPa.s), plastic viscosity (PV, mPa.s), dynamic shear force (YP, Pa), API fluid loss FL _{API of the} above drilling fluid , high temperature and high pressure filtration loss FL _HTHP (220℃), the results are shown in Table 1.

Table 1 Drilling fluid performance test

Drilling fluid AV,mPa.s PV,mPa.s YP,Pa _FLAPI ,mL FL _HTHP220℃ , mL Fl 42 34.5 7.5 0.8 9.2 F2 48.5 38 10.5 0.4 8.4 F3 38.5 32.5 6 1.2 11.4 F4 41 34 7 1.0 10.2 F5 43 35 8 1.0 10.8 F6 41.5 34 7.5 0.8 10.0 F7 42 34 8 1.2 10.8 DFl 36 31 5 3.2 38.6 DF2 37 32.5 4.5 2.6 29.8 DF3 42 35 7 1.6 22.1 DF4 42.5 35 7.5 1.4 15.8 DF5 40 33 7 1.4 16.4 DF6 56 45 11 3.6 48.6 DF7 38 32 6 3.2 28.6 DF8 37 31.5 5.5 2.8 26.4 DF9 36 29.5 6.5 3.0 32.8 DF10 41.5 32 9.5 2.6 29.4 DF11 42 35 7 1.6 20.6 DF12 43 35.5 7.5 1.8 21.8 DF13 38 34 4 3.4 30.4

It can be seen from the data in Table 1 that the 220°C saturated salt-resistant environmentally friendly water-based drilling fluid of the present invention has good rheology, low API filter loss and HTHP filter loss, and can effectively control the filtrate entering the formation; the present invention The high-temperature and salt-resistant zwitterionic polymers and high-temperature and salt-resistant anionic polymers used in drilling fluids have better performance than DSP-1. The addition of organic-inorganic hybrid microsphere plugging agents and strong adsorption anti-collapse plugging agents can significantly improve To reduce HTHP filter loss, each treatment agent can work synergistically to jointly improve drilling fluid performance. The system stabilizer can improve the stability of drilling fluid under high temperature and high salinity, and assist the core treatment agent to maintain the performance of drilling fluid.

Test example 2

Drilling fluids F1-F3 and DF1-DF6 were tested for sand bed plugging and core plugging performance.

Take 400mL of drilling fluid F1-F3 and DF1-DF6 respectively, use barite to weight it to 1.6g/cm ³ , add 36wt% NaCl and 3wt% CaCl ₂ , stir at 5000rpm for 20min, put it into the aging tank, and put the roller In the furnace, after rolling at constant temperature for 16 hours at 220°C, take it out and cool it to room temperature, then stir at 5000 rpm for 20 minutes to obtain the drilling fluid to be tested.

The instrument used in the sand bed filter loss experiment is a visual medium-pressure sand bed plugging instrument. The particle size of the sand used is 80-100 mesh. The specific steps are as follows:

Put 350mL of sand into the sand filter tube and fill it evenly; add 200mL of drilling fluid to be measured on the top of the sand, close the gland tightly, and seal the gland port with a sealing ring; place a measuring cylinder of a certain size under the sand filter tube to measure the fluid loss First, open the main gas valve of the nitrogen bottle to provide a gas source. When the value of the pressure gauge connected to the upper end of the gland increases to 100 psi and stabilizes, open the valve between the pressure gauge and the gland to ventilate. After the stopwatch counts for 30 minutes, record the graduated cylinder. The filtration loss (filtration loss is the sand bed penetration depth or filtration loss volume), the results are shown in Table 2.

Test the core plugging rate as follows:

On the core flow tester, the drilling fluid contamination holder was used to measure the initial forward standard salt water permeability K ₁ of the rock sample. Then remove the core contamination holder and connect it to the drilling fluid high temperature and high pressure dynamic comprehensive tester. Use the above drilling fluid to block the rock sample forward. The drilling fluid temperature is 80°C, the pressure difference is 3.5MPa, and the confining pressure is 5MPa. The shear rate is 150s ^-1 . After the damage time is 30 minutes, the core contamination holder is removed, connected to the core flow tester, and the forward standard salt water permeability K ₂ of the core is measured. The core blocking rate is:

The test results are shown in Table 2.

Table 2 Drilling fluid plugging performance test

As can be seen from Table 2, the 220°C saturated salt-resistant environmentally friendly water-based drilling fluid of the present invention has good plugging performance. The sand bed intrusion depth is as low as 0.5cm, and the core plugging rate reaches 98.6%.

Test example 3

The environmental performance evaluation of drilling fluids F1-F7 was carried out in accordance with SY/T6788-2020 "Environmental Protection Technical Evaluation Requirements for Water-Soluble Oilfield Chemicals", and the biotoxicity EC50 of the luminescent bacteria method was tested. The test results are shown in Table 3.

Table 3 Biotoxicity EC50 using luminescent bacteria method

Drilling fluid EC50/mg/L Fl 69000 F2 64000 F3 75000 F4 71000 F5 70000 F6 69000 F7 68000

It can be seen from Table 3 that the environmentally friendly water-based drilling fluid resistant to 220° C. saturated salt of the present invention has good biocompatibility and meets environmental protection requirements.

In summary, the 220°C saturated salt-resistant and environmentally friendly water-based drilling fluid of the present invention can show good performance under high-temperature and high-salt conditions, meeting the needs of drilling deep oil and gas formations.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that each of the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner without conflict. In order to avoid unnecessary repetition, the present invention combines various possible combinations. The combination method will not be further explained.

In addition, any combination of various embodiments of the present invention can also be carried out. As long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (10)

1. The 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid is characterized by comprising the following raw materials in parts by weight: 100 parts of water, 1-4 parts of composite soil cutting agent, 0.2-0.6 part of sodium hydroxide, 3-6 parts of high temperature resistant and salt resistant zwitterionic polymer, 2-4 parts of high temperature resistant and salt resistant anionic polymer, 3-5 parts of alcohol amine inhibitor, 6-10 parts of organic-inorganic hybrid microsphere plugging agent, 2-4 parts of strong adsorption collapse prevention plugging agent, 3-4 parts of composite grease lubricant and 0.5-1 part of system stabilizer.

2. The 220 ℃ saturated salt resistant environmental protection water-based drilling fluid of claim 1, comprising one or more of the following conditions:

i. the composite soil cutting agent is prepared by mixing bentonite, attapulgite, diatomite, volcanic rock powder and sepiolite; preferably, the mass ratio of bentonite, attapulgite, diatomite, volcanic rock powder and sepiolite is 1-3:1:0.1-1:0.1-1:0.1-1, preferably 2:1:0.5:0.5:0.5;

ii. The alcohol amine inhibitor is prepared by mixing polyether amine D230, polyether amine D400, polyethylene glycol 400, triethanolamine and pentaethylenehexamine; preferably, the mass ratio of polyetheramine D230, polyetheramine D400, polyethylene glycol 400, triethanolamine and pentaethylenehexamine is 1-3:1:1:0.1-0.5:0.1 to 0.3, preferably 2:1:1:0.3:0.2;

the compound grease lubricant is prepared by mixing glycerol oleate materials, castor oil and SP-60; preferably, the mass ratio of the glycerol oleate material to the castor oil to the SP-60 is 1:1:0.1-1, preferably 1:1:0.5;

preferably, the glycerol oleate material is selected from one or more than two of glycerol monooleate, glycerol dioleate or glycerol trioleate;

iv, the system stabilizer is obtained by mixing Span-80, tween-80 and OP-10; preferably, the mass ratio of Span-80, tween-80 and OP-10 is 1-3:1:1, preferably 2:1:1.

3. the 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid according to claim 1, wherein the high temperature resistant and salt resistant zwitterionic polymer is prepared from the following raw materials in parts by weight: 15-25 parts of N, N-dimethylacrylamide, 5-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 120-140 parts of water, 10-20 parts of methacryloyloxyethyl trimethyl ammonium chloride, 10-20 parts of TPEG-2400 (methallyl polyoxyethylene ether-2400), 5-10 parts of 1-vinylimidazole, 0.1-1 part of N, N, N ', N' -tetramethyl ethylenediamine, 0.1-0.5 part of ammonium persulfate and 0.01-0.1 part of sodium bisulfite;

preferably, the preparation method of the high-temperature-resistant and salt-resistant zwitterionic polymer comprises the following steps:

fully dispersing N, N-dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid in water, and adjusting the pH to 7-8 by using 40-60wt% NaOH aqueous solution; adding methacryloyloxyethyl trimethyl ammonium chloride, TPEG-2400, 1-vinylimidazole and N, N, N ', N' -tetramethyl ethylenediamine, and fully dispersing; adding ammonium persulfate and sodium bisulphite mixed initiator, stirring for reaction, washing, drying and crushing to obtain the high-temperature-resistant salt-resistant amphoteric ion polymer.

4. The 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid according to claim 1, wherein the preparation method of the high temperature resistant salt resistant anionic polymer comprises the following steps:

(1) Dissolving sodium formaldehyde sulfoxylate in deionized water, adding 30-50wt% dimethylamine aqueous solution, stirring for reaction, centrifuging to obtain precipitate, and drying to obtain (dimethylamine) sodium methylsulfonate;

(2) Dissolving sodium (dimethylamine) methylsulfonate in an ethanol water solution to obtain a sodium (dimethylamine) methylsulfonate solution; dissolving 4-chloromethyl styrene in absolute ethyl alcohol to obtain 4-chloromethyl styrene solution; dropwise adding a (dimethylamine) sodium methylsulfonate solution into a 4-chloromethyl styrene solution, stirring for reaction, filtering, washing, drying and crushing to obtain betaine monomers;

(3) Fully dispersing N, N-dimethylacrylamide, betaine monomer and 2-acrylamide-2-methylpropanesulfonic acid in deionized water, adding initiator potassium persulfate, performing free radical polymerization reaction, and then washing, drying and crushing to obtain the high-temperature-resistant salt-resistant anionic polymer.

5. The 220 ℃ saturated brine resistant environmental protection type water-based drilling fluid according to claim 4, comprising one or more of the following conditions:

i. In the step (1), the mass ratio of the sodium formaldehyde sulfoxylate to the deionized water to the dimethylamine aqueous solution is 1:3-5:1-3, preferably 1:4:2;

ii. In the step (1), the stirring reaction temperature is 25-35 ℃, and the stirring reaction time is 70-75h;

iii, in the step (2), the mass ratio of ethanol to water in the ethanol aqueous solution is 1:1;

iv, in the step (2), the mass ratio of the (dimethylamine) sodium methylsulfonate to the ethanol aqueous solution to the 4-chloromethylstyrene to the absolute ethanol is 6-8:90-110:3-8:30-50, preferably 7:100:5:40;

v, in the step (2), the dripping time is 5-10min; stirring and reacting at 40-50 deg.c for 20-30 hr;

vi, in the step (3), the mass ratio of N, N-dimethylacrylamide to betaine monomer to 2-acrylamido-2-methylpropanesulfonic acid to deionized water to neutralized potassium persulfate is 18-25:6-10:6-10:90-110:0.1-0.3, preferably 21:8:8:100:0.15;

vii, in the step (3), the free radical polymerization reaction temperature is 50-70 ℃ and the free radical polymerization reaction time is 4-8 hours.

6. The 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid according to claim 1, wherein the organic-inorganic hybrid microsphere plugging agent is prepared from the following raw materials in parts by weight:

5-15 parts of sodium p-styrenesulfonate, 1-10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 100 parts of water, 0.1-0.5 part of sodium dodecyl benzene sulfonate, 1-3 parts of KH-570 modified nano-silica, 15-25 parts of styrene, 0.1-0.3 part of initiator potassium persulfate and 0.01-0.05 part of cross-linking agent N, N' -methylene bisacrylamide;

preferably, the preparation method of the organic-inorganic hybrid microsphere plugging agent comprises the following steps:

1) Fully dispersing sodium p-styrenesulfonate, 2-acrylamide-2-methylpropanesulfonic acid, sodium dodecyl benzene sulfonate and KH-570 modified nano-silica into water to obtain a solution a;

2) Adding styrene dropwise into the solution a under stirring, and stirring at room temperature for 20-40 minutes to form emulsion; under the stirring condition, adding initiator potassium persulfate and cross-linking agent N, N' -methylene bisacrylamide, and stirring for reaction to obtain the organic-inorganic hybrid microsphere plugging agent.

7. The 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid as claimed in claim 1, wherein the strong adsorption collapse prevention plugging agent is prepared from the following raw materials in parts by weight: 5-15 parts of methacrylic acid, 100-140 parts of water, 1-10 parts of N-vinyl pyrrolidone, 10-30 parts of methyl methacrylate, 1-10 parts of lauryl methacrylate, 1-5 parts of divinylbenzene and 0.05-0.5 part of initiator potassium persulfate;

Preferably, the preparation method of the strong adsorption anti-collapse plugging agent comprises the following steps:

1) Fully dispersing methacrylic acid and N-vinyl pyrrolidone in water to obtain a mixed solution 1;

2) Thoroughly mixing methyl methacrylate, lauryl methacrylate and divinylbenzene, washing away polymerization inhibitor MEHQ by using an aqueous solution of NaOH with the mass concentration of 40-60% to obtain a mixed solution 2;

3) Under the stirring condition, dropwise adding the mixed solution 2 into the mixed solution 1, adding an initiator potassium persulfate, and stirring for reaction to obtain the strong-adsorption anti-collapse plugging agent.

8. The method for preparing 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid according to any one of claims 1 to 7, comprising the following steps:

fully dispersing the composite soil cutting agent and sodium hydroxide in water, and then sequentially adding the high-temperature-resistant salt-resistant zwitterionic polymer, the high-temperature-resistant salt-resistant anionic polymer, the alcohol amine inhibitor, the organic-inorganic hybrid microsphere plugging agent, the strong-adsorption collapse-preventing plugging agent, the composite grease lubricant and the system stabilizer, and fully and uniformly dispersing to obtain the 220 ℃ saturated salt-resistant environment-friendly water-based drilling fluid.

9. The method for preparing 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid according to claim 8, which is characterized by comprising the following steps:

Adding water into a high-speed stirring cup, adding a composite soil cutting agent and sodium hydroxide under low-speed stirring, and stirring for 24-48h under low-speed stirring; adding the high-temperature-resistant and salt-resistant zwitterionic polymer, and stirring at a high speed for 20min; adding the high-temperature-resistant and salt-resistant anionic polymer, and stirring at a high speed for 20min; adding alcohol amine inhibitor, and stirring at high speed for 20min; adding an organic-inorganic hybrid microsphere plugging agent, and stirring at a high speed for 20min; adding a strong adsorption collapse prevention plugging agent, and stirring at a high speed for 20min; adding a composite grease lubricant, and stirring at a high speed for 20min; adding a system stabilizer, and stirring at a high speed for 20min to obtain 220 ℃ saturated salt resistant environment-friendly water-based drilling fluid;

preferably, the rotating speed of the low-speed stirring is 1000-3000r/min, and the rotating speed of the high-speed stirring is 8000-10000r/min.

10. The use of an environmentally friendly water-based drilling fluid resistant to 220 ℃ saturated salts according to any one of claims 1-7 in deep or ultra-deep drilling processes.