Environment-friendly viscosity reducer and application thereof

Abstract

The invention discloses an environment-friendly viscosity reducer and application thereof, and belongs to the technical field of viscosity reducer processing. The environment-friendly viscosity reducer is used for solving the technical problem that the viscosity reduction effect of a viscosity reducer on water-based drilling fluid needs to be further improved in the prior art, and comprises the following components in parts by weight: 60-70 parts of ferrous gluconate, 20-30 parts of supported sulfonated montmorillonite and 15-18 parts of mPEG modified nanoparticles. Charge regulation of ferrous gluconate, electrostatic-hydrophobic synergistically dispersed sulfonated montmorillonite and mPEG modified nanoparticles with steric hindrance-lubrication effect are used for synergistically matching, the viscosity parameter of the water-based drilling fluid is remarkably reduced, the dynamic shearing force of the water-based drilling fluid is reduced at the same time, and the water-based drilling fluid is small in environmental pollution and has environmental protection performance.

Description

Technical Field

[0001] The present invention relates to the technical field of viscosity reducer processing, and particularly relates to an environmentally friendly viscosity reducer and its application. Background Technique

[0002] Drilling fluid is the general term for various circulating fluids that meet the needs of drilling work with its various functions during the drilling process. Drilling fluid is the blood of drilling, also known as borehole flushing fluid. During the circulation of drilling fluid, due to reasons such as calcium invasion and salt invasion, the double electric layer of clay ions is compressed, and the solid particles in the drilling fluid come into contact with each other at the end-face or end-end, causing the drilling fluid to flocculate, resulting in an increase in viscosity and shear force, and generating adverse effects including increased flow resistance, increased pump pressure, reduced bottom-hole cleaning effect, bit balling, difficulty in tripping, and fluctuations in drilling fluid performance, bringing risks to drilling operations. Therefore, when the viscosity of the drilling fluid increases, it is necessary to add a viscosity reducer to reduce the viscosity of the drilling fluid.

[0003] In the prior art, a patent for invention with the publication number of CN117736382B discloses a polymer viscosity reducer for water-based drilling fluid and its preparation method, which relates to the technical field of oil drilling engineering and oilfield chemistry. The polymer viscosity reducer for water-based drilling fluid provided by the present invention includes the following preparation raw materials in parts by mass: 100 - 150 parts of water, 30 - 50 parts of acrylic acid, 10 - 20 parts of maleic anhydride, 40 - 60 parts of allyl polyethylene glycol, 3 - 6 parts of initiator, 1 - 3 parts of pH regulator, 10 - 20 parts of diamine, and 5 - 10 parts of saturated organic acid.

[0004] However, the existing viscosity reducer is a kind of high molecular polymer, and its large-scale use causes relatively large pollution to the environment. Moreover, it only reduces the viscosity of water-based drilling fluid through electrostatic action and improving hydrophilicity. During the actual drilling process, the high-valent metal ions in the drilling fluid are prone to form flocs by bridging clay particles in the drilling fluid, resulting in an increase in the viscosity and shear force of the drilling fluid, and the viscosity reduction effect of the existing viscosity reducer on water-based drilling fluid needs to be further improved.

[0005] In view of this technical defect, a solution is proposed now. Summary of the Invention

[0006] The purpose of the present invention is to provide an environmentally friendly viscosity reducer and its application, aiming to solve the technical problem that the viscosity reduction effect of the viscosity reducer on water-based drilling fluid in the prior art needs to be further improved.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] An environmentally friendly viscosity reducer, comprising the following components in parts by weight: 60 - 70 parts of ferrous gluconate, 20 - 30 parts of supported sulfonated montmorillonite, and 15 - 18 parts of mPEG-modified nanoparticles.

[0009] Further, the supported sulfonated montmorillonite is obtained by the following steps:

[0010] A1. Mix diatomite and acid water, react at room temperature for 10 - 12 h, and perform post-treatment to obtain activated diatomite;

[0011] A2. Mix sodium lignosulfonate, purified water, and sodium hydroxide, stir at room temperature until the system becomes clear, add activated diatomite to the reaction system, ultrasonically disperse for 30 - 50 min, add dilute acid to the reaction system to adjust the system pH to 3 - 4, continue stirring for 20 - 30 min, add a modification solution to the reaction system, keep the temperature for reaction for 5 - 6 h, and perform post-treatment to obtain supported sulfonated diatomite.

[0012] The synthesis reaction mechanism of the supported sulfonated diatomite is as follows:

[0013] During the reaction process, acid water can react with metal oxides in diatomite to form water-soluble salts, removing metal impurities in diatomite, expanding the pore size of diatomite, increasing its specific surface area and adsorption capacity. Under alkaline conditions, sodium lignosulfonate dissolves into anionic form and exists freely in the solution. Through ultrasonic dispersion, it promotes the uniform dispersion of sodium lignosulfonate and activated diatomite. By adjusting the system pH to acidic, sodium lignosulfonate precipitates out and is adsorbed on diatomite through electrostatic interaction. As a modifier, octyltrimethoxysilane, under acidic conditions, the siloxane bond on its molecule hydrolyzes to form silanol and condenses with the surface hydroxyl groups of diatomite to form a covalent bond, grafting the octyl chain onto the surface of diatomite, enhancing the hydrophobicity and fixing the sulfonic acid group, thereby preparing the supported sulfonated diatomite.

[0014] Further, in step A1, the dosage ratio of the diatomite to the acid water is 1 g: 15 - 20 mL, the acid water is a 3 - 5 mol / L hydrochloric acid solution, and the post-treatment includes: after the reaction is completed, perform suction filtration, wash the filter cake with purified water until it is neutral and then drain it, transfer the filter cake to a drying oven at a temperature of 60 - 70 °C, and vacuum dry it to constant weight to obtain activated diatomite.

[0015] Further, in step A2, the dosage ratio of the sodium lignosulfonate, purified water, sodium hydroxide, activated diatomite, and the modification solution is 2 g: 30 mL: 0.5 g: 7 g: 10 mL, the modification solution is composed of octyltrimethoxysilane and absolute ethanol in a ratio of 1 g: 10 mL, the dilute acid is 0.3 - 0.5 mol / L hydrochloric acid, and the post-treatment includes: after the reaction is completed, perform suction filtration, wash the filter cake with a 50 wt% ethanol aqueous solution until it is neutral and then drain it, transfer the filter cake to a drying oven at a temperature of 60 - 70 °C, and vacuum dry it to constant weight to obtain supported sulfonated diatomite.

[0016] Further, the preparation method of the mPEG-modified nanoparticles is as follows: An anhydride-modified nanoparticle, methoxypolyethylene glycol, acetone, and a catalyst are stirred and mixed, the temperature of the reaction system is raised to the reflux temperature of the system, and the reaction is carried out under insulation for 10 - 12 h. After post-treatment, mPEG-modified nanoparticles are obtained.

[0017] The synthesis reaction mechanism of the mPEG-modified nanoparticles is as follows:

[0018] During the reaction process, under the action of the catalyst, the anhydride group on the anhydride-modified nanoparticle is protonated, and a ring-opening reaction occurs to generate an acyloxy intermediate. The hydroxyl group on the methoxypolyethylene glycol molecule attacks the activated anhydride group as a nucleophile to form an ester bond, and mPEG modification is formed on the anhydride-modified nanoparticle, thereby preparing the mPEG-modified nanoparticles.

[0019] Further, the dosage ratio of the anhydride-modified nanoparticle, methoxypolyethylene glycol, acetone, and the catalyst is 5 g: 3 g: 50 mL: 0.1 g. The catalyst is p-toluenesulfonic acid. The post-treatment includes: After the reaction is completed, the temperature of the reaction system is lowered to room temperature, and suction filtration is carried out. The filter cake is washed three times with absolute ethanol and 50 vol% ethanol aqueous solution in sequence and then dried by suction. The filter cake is transferred to an oven at 65 - 75 °C and vacuum dried to a constant weight to obtain the mPEG-modified nanoparticles.

[0020] Further, the preparation method of the anhydride-modified nanoparticle is as follows: Under the protection of an inert gas, an olefin-modified nanoparticle and toluene are mixed and stirred, the temperature of the reaction system is raised to 70 - 80 °C, a modification solution is added dropwise to the reaction system, and the reaction is carried out under insulation for 4 - 5 h. After post-treatment, the anhydride-modified nanoparticle is obtained.

[0021] The synthesis reaction mechanism of the anhydride-modified nanoparticle is as follows:

[0022] During the reaction process, under the action of a radical initiator, a radical addition reaction occurs between the unsaturated double bonds on maleic anhydride, acrylic acid, and the olefin-modified nanoparticle, and dilute acid and anhydride modification are formed on the nanoparticle, thereby preparing the anhydride-modified nanoparticle.

[0023] Further, the dosage ratio of the olefin-modified nanoparticle, toluene, and the modification solution is 7 g: 50 mL: 4 mL. The modification solution consists of maleic anhydride, acrylic acid, toluene, and an initiator in a ratio of 2 g: 3 g: 5 mL: 0.2 g. The initiator is benzoyl peroxide. The post-treatment includes: After the reaction is completed, the temperature of the reaction solution is lowered to room temperature, and suction filtration is carried out. The filter cake is washed 3 times with toluene and then dried by suction. The filter cake is transferred to an oven at 60 - 70 °C and vacuum dried to a constant weight to obtain the anhydride-modified nanoparticle.

[0024] Further, the preparation method of the olefin-modified nanoparticles is as follows: Mix ammonia water and an ethanol solution, raise the temperature of the reaction system to 55 - 60°C, dropwise add a siloxane solution to the reaction system, keep the temperature for reaction for 4 - 6 h, and perform post-treatment to obtain the olefin-modified nanoparticles.

[0025] The synthesis reaction mechanism of the olefin-modified nanoparticles is as follows:

[0026] During the reaction process, the siloxane solution is dropped into the ethanol emulsion dispersion system. In an alkaline environment, the siloxane bonds in tetraethyl orthosilicate and 5-hexenyltriethoxysilane molecules undergo hydrolysis and condensation reactions to bond with siloxane-silicon bonds, forming microparticles in the emulsion, and obtaining nano-silica particles modified with olefin double bonds.

[0027] Further, the dosage ratio of the ammonia water, ethanol solution, and siloxane solution is 1 g:20 mL:3 g. The ethanol solution consists of absolute ethanol, deionized water, and an emulsifier in a ratio of 5 mL:5 mL:0.2 g. The emulsifier is octadecylamine polyoxyethylene ether. The siloxane solution consists of tetraethyl orthosilicate and 5-hexenyltriethoxysilane in a ratio of 3 g:1 g. The post-treatment includes: after the reaction is completed, lower the temperature of the reaction system to room temperature, perform suction filtration, wash the filter cake with absolute ethanol 3 times and then drain it, transfer the filter cake to a drying oven at 50 - 60°C, and perform vacuum drying until constant weight to obtain the olefin-modified nanoparticles.

[0028] The application of an environmentally friendly viscosity reducer is to use the environmentally friendly viscosity reducer as a viscosity reducer in water-based drilling fluids.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention uses ferrous gluconate, supported sulfonated montmorillonite, and mPEG-modified nanoparticles to form an environmentally friendly viscosity reducer. By synergistically combining the charge regulation of ferrous gluconate, the electrostatic-hydrophobic synergistic dispersion of sulfonated montmorillonite, and the steric hindrance-lubrication effect of mPEG-modified nanoparticles, it significantly reduces the viscosity parameter of the water-based drilling fluid and simultaneously reduces its dynamic shear force. The supported sulfonated montmorillonite has short-chain structures of surface-modified octyl chains and sulfonic acid groups, which are easy to be biodegradable by microorganisms and have no risk of bioaccumulation. The mPEG-modified nanoparticles are connected by ester bonds of methoxypolyethylene glycol, and can be hydrolyzed into low-molecular-weight methoxypolyethylene glycol and carboxylic acid in the environment, meeting the OECD 301B biodegradation standard. The iron element in ferrous gluconate is an essential trace element for the environment and has no ecological toxicity. Therefore, the components do not contain heavy metals such as chromium and lead, or persistent organic pollutants such as halogens and polycyclic aromatic hydrocarbons, and have little environmental pollution and are very environmentally friendly.

[0031] 2. In the environmentally friendly viscosity reducer of the present invention, ferrous gluconate generates gluconic acid and ferrous ions under aqueous conditions. The glucose groups can adsorb on the edge of clay particles, preventing the end-face, face-face, or end-end contact of clay particles, and bringing more negative charges and hydration layers to the clay particles, increasing the double-layer repulsive force and the thickness of the hydration film at the end face of the clay particles, thereby disassembling and weakening the network structure formed by the end-face and end-end connections between clay particles, reducing the viscosity and dynamic shear force. After loading sodium lignosulfonate on diatomite and introducing octyl chain modification, a supported sulfonated diatomite is prepared. The sulfonic acid groups on the surface of the supported sulfonated diatomite ionize into -SO3 - in the water-based drilling fluid, endowing the particle surface with strong negative charges, significantly enhancing the electrostatic repulsion between like charges, destroying the aggregation structure of clay particles, and reducing the internal frictional resistance of the system. The octyl chain forms a physical barrier on the surface of diatomite particles, preventing direct contact between particles and reducing the aggregation dominated by van der Waals attraction. Moreover, -SO3 - adsorbs on the positively charged region at the edge of clay particles, neutralizes local positive charges, reduces the edge-face attraction, promotes the parallel arrangement of lamellae rather than cross-linking. The hydrophobicity of the octyl chain interferes with the hydrogen bond network between clay particles and water molecules, reducing the hydrogen bond cross-linking density between lamellae, making the network structure looser, and further reducing the apparent viscosity, plastic viscosity, and dynamic shear force of the drilling fluid.

[0032] 3. In the environmentally friendly viscosity reducer of the present invention, the hydrophilic chain of mPEG on the mPEG-modified nanoparticles contains a large number of ether oxygen groups, which can form strong hydrogen bonds with water molecules, forming a dense hydration layer on the surface of the nanoparticles, reducing the direct contact friction between the nanoparticles and clay particles. Moreover, the extension of the mPEG chain occupies space, weakening the van der Waals force and hydrogen bond interaction between lamellae, hindering the aggregation of clay particles, and reducing the flow resistance caused by the stacking of lamellae. The residual carboxylic acid groups on the surface of the anhydride-modified nanoparticles are partially ionized into -COO - in the alkaline drilling fluid, enhancing the negative charge on the particle surface, generating electrostatic repulsion with clay particles, further dispersing the system, and reducing the viscosity and dynamic shear force. The Fe in the ferrous gluconate molecule 2+ chelates the high-valent metal ions in the drilling fluid, eliminates the bridging effect of metal ions on clay particles, reduces flocculation. The sulfonic acid groups on the surface of the supported sulfonated montmorillonite enhance the electrostatic repulsion, superimposing with the negative charges of mPEG nanoparticles to form a stronger like-charge barrier, inhibiting clay aggregation. Moreover, the long chain of mPEG provides a physical barrier, and the sulfonic acid group provides a charge barrier. The dual effects prevent particles from approaching, optimizing the dispersion mechanism of the viscosity reducer for the drilling fluid, and reducing the viscosity and shear force of the drilling fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Figure 1 This is a schematic diagram of the states of clay ions in the drilling fluid, such as dispersion, flocculation, and aggregation, of the present invention. Specific Embodiments

[0035] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0036] In this application, the water-based drilling fluid is the water-based drilling fluid prepared in Example 4 of the invention patent with the publication number CN111793477A;

[0037] In this application, the CAS number of ferrous gluconate is 12389-15-0;

[0038] In this application, octadecylamine polyoxyethylene ether is selected from Taizhou Jiayin Chemical Co., Ltd., the product name is octadecylamine polyoxyethylene ether AC1815, and the CAS number is 26635-92-7;

[0039] In this application, polyethylene glycol monomethyl ether is selected from Jiangsu Haian Petrochemical Factory, the model is MPEG-400, and the CAS number is 9004-74-4.

[0040] Example 1

[0041] This example provides a preparation method of a supported sulfonated montmorillonite for an environmentally friendly viscosity reducer, including the following steps:

[0042] A1. Preparation of activated diatomaceous earth

[0043] Weigh: 100 g of diatomaceous earth and 1500 mL of 3 mol / L hydrochloric acid solution are added to a 3 L reaction flask and stirred. Stir at room temperature for 10 h, filter by suction. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to an oven at 60 °C, and the vacuum is pumped to a negative pressure of 0.1 MPa, and vacuum dried to constant weight to obtain activated diatomaceous earth.

[0044] A2. Preparation of supported sulfonated montmorillonite

[0045] Mix octyltrimethoxysilane and absolute ethanol evenly at a ratio of 1 g:10 mL to obtain a modified solution for standby.

[0046] Weigh: 20 g of sodium lignosulfonate, 300 mL of purified water and 5 g of sodium hydroxide, add them to a 1 L reaction flask and stir. Stir at room temperature until the system becomes clear. Add 70 g of activated diatomite to the reaction flask, and disperse it ultrasonically for 30 min. Fix the reaction flask on an iron stand with mechanical stirring. Add 0.3 mol / L hydrochloric acid to the reaction flask to adjust the pH of the system to 3, and continue stirring for 20 min. Add 100 mL of the modified solution to the reaction flask, keep the temperature for reaction for 5 h, filter by suction. Wash the filter cake with 50 wt% ethanol aqueous solution until neutral and then dry by suction. Transfer the filter cake to a drying oven at 60 °C, evacuate to a negative pressure of 0.1 MPa, and dry under vacuum until constant weight to obtain supported sulfonated diatomite.

[0047] Example 2

[0048] This example provides a preparation method of supported sulfonated montmorillonite for an environmentally friendly viscosity reducer, including the following steps:

[0049] A1. Preparation of activated diatomite

[0050] Weigh: 100 g of diatomite and 1800 mL of 4 mol / L hydrochloric acid solution, add them to a 3 L reaction flask and stir. Stir at room temperature for 11 h, filter by suction. Wash the filter cake with purified water until neutral and then dry by suction. Transfer the filter cake to a drying oven at 65 °C, evacuate to a negative pressure of 0.1 MPa, and dry under vacuum until constant weight to obtain activated diatomite.

[0051] A2. Preparation of supported sulfonated montmorillonite

[0052] Mix octyltrimethoxysilane and absolute ethanol evenly at a ratio of 1 g:10 mL to obtain a modified solution for standby.

[0053] Weigh: 20 g of sodium lignosulfonate, 300 mL of purified water and 5 g of sodium hydroxide, add them to a 1 L reaction flask and stir. Stir at room temperature until the system becomes clear. Add 70 g of activated diatomite to the reaction flask, and disperse it ultrasonically for 40 min. Fix the reaction flask on an iron stand with mechanical stirring. Add 0.4 mol / L hydrochloric acid to the reaction flask to adjust the pH of the system to 3.5, and continue stirring for 25 min. Add 100 mL of the modified solution to the reaction flask, keep the temperature for reaction for 5.5 h, filter by suction. Wash the filter cake with 50 wt% ethanol aqueous solution until neutral and then dry by suction. Transfer the filter cake to a drying oven at 65 °C, evacuate to a negative pressure of 0.1 MPa, and dry under vacuum until constant weight to obtain supported sulfonated diatomite.

[0054] Example 3

[0055] This embodiment provides a preparation method of supported sulfonated montmorillonite for an environmentally friendly viscosity reducer, including the following steps:

[0056] A1. Prepare activated diatomite

[0057] Weigh: 100 g of diatomite and 2000 mL of 5 mol / L hydrochloric acid solution are added to a 3 L reaction flask and stirred. Stir for 12 h at room temperature, then filter by suction. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 70 °C, evacuated to a negative pressure of 0.1 MPa, and vacuum dried to constant weight to obtain activated diatomite.

[0058] A2. Prepare supported sulfonated montmorillonite

[0059] Mix octyltrimethoxysilane and absolute ethanol evenly at a ratio of 1 g:10 mL to obtain a modified solution for standby;

[0060] Weigh: 20 g of sodium lignosulfonate, 300 mL of purified water and 5 g of sodium hydroxide are added to a 1 L reaction flask and stirred. Stir at room temperature until the system is clear. Add 70 g of activated diatomite to the reaction flask, and disperse ultrasonically for 50 min. Fix the reaction flask on an iron stand with mechanical stirring. Add 0.5 mol / L hydrochloric acid to the reaction flask to adjust the pH of the system to 4, and continue stirring for 30 min. Add 100 mL of the modified solution to the reaction flask, keep the temperature for reaction for 6 h, then filter by suction. The filter cake is washed with 50 wt% ethanol aqueous solution until neutral and then dried by suction. The filter cake is transferred to a drying oven at 70 °C, evacuated to a negative pressure of 0.1 MPa, and vacuum dried to constant weight to obtain supported sulfonated diatomite.

[0061] Example 4

[0062] This embodiment provides a preparation method of mPEG-modified nanoparticles for an environmentally friendly viscosity reducer, including the following steps:

[0063] B1. Prepare olefin-modified nanoparticles

[0064] Mix tetraethyl orthosilicate and 5-hexenyltriethoxysilane evenly at a ratio of 3 g:1 g to obtain a siloxane solution for standby;

[0065] Mix absolute ethanol, deionized water and polyoxyethylene octadecylamine evenly at a ratio of 5 mL:5 mL:0.2 g to obtain an ethanol solution for standby;

[0066] Weigh: Add 25 g of ammonia water and 500 mL of ethanol solution into a 1 L reaction flask and stir. Raise the temperature of the reaction flask to 55 °C. Dropwise add 75 g of siloxane solution into the reaction flask, keep the temperature for reaction for 4 h, lower the temperature of the reaction flask to room temperature, perform suction filtration. Wash the filter cake with anhydrous ethanol three times and then drain it. Transfer the filter cake to a drying oven at 50 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain olefin-modified nanoparticles.

[0067] B2. Preparation of anhydride-modified nanoparticles

[0068] Mix maleic anhydride, acrylic acid, toluene and benzoyl peroxide evenly in a ratio of 2 g: 3 g: 5 mL: 0.2 g to obtain a modification solution for standby.

[0069] Weigh: Add 70 g of olefin-modified nanoparticles and 500 mL of toluene into a 1 L reaction flask protected by argon and stir. Raise the temperature of the reaction flask to 70 °C. Dropwise add 40 mL of the modification solution into the reaction flask, keep the temperature for reaction for 4 h, lower the temperature of the reaction flask to room temperature, perform suction filtration. Wash the filter cake with toluene three times and then drain it. Transfer the filter cake to a drying oven at 60 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain anhydride-modified nanoparticles.

[0070] B3. Preparation of mPEG-modified nanoparticles

[0071] Weigh: Add 50 g of anhydride-modified nanoparticles, 30 g of methoxypolyethylene glycol, 500 mL of acetone and 1 g of p-toluenesulfonic acid into a reaction flask and stir. Raise the temperature of the reaction flask to the reflux temperature of the system, keep the temperature for reaction for 10 h, lower the temperature of the reaction flask to room temperature, perform suction filtration. Wash the filter cake successively with anhydrous ethanol and 50 vol% ethanol aqueous solution three times and then drain it. Transfer the filter cake to a drying oven at 65 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain mPEG-modified nanoparticles.

[0072] Example 5

[0073] This example provides a preparation method of mPEG-modified nanoparticles for an environmentally friendly viscosity reducer, including the following steps:

[0074] B1. Preparation of olefin-modified nanoparticles

[0075] Mix tetraethyl orthosilicate and 5-hexenyltriethoxysilane evenly in a ratio of 3 g: 1 g to obtain a siloxane solution for standby.

[0076] Mix anhydrous ethanol, deionized water and polyoxyethylene ether of octadecylamine evenly in a ratio of 5 mL: 5 mL: 0.2 g to obtain an ethanol solution for standby.

[0077] Weigh: Add 25 g of ammonia water and 500 mL of ethanol solution to a 1 L reaction flask and stir. Raise the temperature of the reaction flask to 57 °C. Dropwise add 75 g of siloxane solution to the reaction flask, keep the temperature for reaction for 5 h, lower the temperature of the reaction flask to room temperature, filter by suction. Wash the filter cake with anhydrous ethanol three times and then drain it. Transfer the filter cake to a drying oven at 55 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain olefin-modified nanoparticles.

[0078] B2. Preparation of anhydride-modified nanoparticles

[0079] Mix maleic anhydride, acrylic acid, toluene and benzoyl peroxide evenly in a ratio of 2 g: 3 g: 5 mL: 0.2 g to obtain a modification solution for standby.

[0080] Weigh: Add 70 g of olefin-modified nanoparticles and 500 mL of toluene to a 1 L reaction flask protected by argon and stir. Raise the temperature of the reaction flask to 75 °C. Dropwise add 40 mL of the modification solution to the reaction flask, keep the temperature for reaction for 4.5 h, lower the temperature of the reaction flask to room temperature, filter by suction. Wash the filter cake with toluene three times and then drain it. Transfer the filter cake to a drying oven at 65 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain anhydride-modified nanoparticles.

[0081] B3. Preparation of mPEG-modified nanoparticles

[0082] Weigh: Add 50 g of anhydride-modified nanoparticles, 30 g of methoxypolyethylene glycol, 500 mL of acetone and 1 g of p-toluenesulfonic acid to a reaction flask and stir. Raise the temperature of the reaction flask to the reflux temperature of the system, keep the temperature for reaction for 11 h, lower the temperature of the reaction flask to room temperature, filter by suction. Wash the filter cake with anhydrous ethanol and 50 vol% ethanol aqueous solution three times each and then drain it. Transfer the filter cake to a drying oven at 70 °C, evacuate to a negative pressure of 0.1 MPa, and vacuum dry to constant weight to obtain mPEG-modified nanoparticles.

[0083] Example 6

[0084] This example provides a method for preparing mPEG-modified nanoparticles for an environmentally friendly viscosity reducer, including the following steps:

[0085] B1. Preparation of olefin-modified nanoparticles

[0086] Mix tetraethyl orthosilicate and 5-hexenyltriethoxysilane evenly in a ratio of 3 g: 1 g to obtain a siloxane solution for standby.

[0087] Mix anhydrous ethanol, deionized water and polyoxyethylene ether of octadecylamine evenly in a ratio of 5 mL: 5 mL: 0.2 g to obtain an ethanol solution for standby.

[0088] Weigh: Add 25 g of ammonia water and 500 mL of ethanol solution into a 1 L reaction flask and stir. Raise the temperature of the reaction flask to 60 °C. Dropwise add 75 g of siloxane solution into the reaction flask, keep the temperature for reaction for 6 h, lower the temperature of the reaction flask to room temperature, perform suction filtration, wash the filter cake with anhydrous ethanol 3 times and then drain it. Transfer the filter cake to a drying oven at 60 °C, evacuate to a negative pressure of 0.1 MPa, and perform vacuum drying until constant weight to obtain olefin-modified nanoparticles.

[0089] B2. Preparation of anhydride-modified nanoparticles

[0090] Mix maleic anhydride, acrylic acid, toluene and benzoyl peroxide evenly in a ratio of 2 g: 3 g: 5 mL: 0.2 g to obtain a modifier solution for standby.

[0091] Weigh: Add 70 g of olefin-modified nanoparticles and 500 mL of toluene into a 1 L reaction flask protected by argon and stir. Raise the temperature of the reaction flask to 80 °C. Dropwise add 40 mL of the modifier solution into the reaction flask, keep the temperature for reaction for 5 h, lower the temperature of the reaction flask to room temperature, perform suction filtration, wash the filter cake with toluene 3 times and then drain it. Transfer the filter cake to a drying oven at 70 °C, evacuate to a negative pressure of 0.1 MPa, and perform vacuum drying until constant weight to obtain anhydride-modified nanoparticles.

[0092] B3. Preparation of mPEG-modified nanoparticles

[0093] Weigh: Add 50 g of anhydride-modified nanoparticles, 30 g of methoxypolyethylene glycol, 500 mL of acetone and 1 g of p-toluenesulfonic acid into a reaction flask and stir. Raise the temperature of the reaction flask to the reflux temperature of the system, keep the temperature for reaction for 12 h, lower the temperature of the reaction flask to room temperature, perform suction filtration, wash the filter cake successively with anhydrous ethanol and 50 vol% ethanol aqueous solution three times and then drain it. Transfer the filter cake to a drying oven at 75 °C, evacuate to a negative pressure of 0.1 MPa, and perform vacuum drying until constant weight to obtain mPEG-modified nanoparticles.

[0094] Example 7

[0095] This example provides a preparation method and application of an environmentally friendly viscosity reducer.

[0096] The preparation method of the environmentally friendly viscosity reducer is: Weigh by weight: 60 parts of ferrous gluconate, 20 parts of the supported sulfonated montmorillonite prepared in Example 1 and 15 parts of the mPEG-modified nanoparticles prepared in Example 4, and mix them evenly to obtain the environmentally friendly viscosity reducer.

[0097] Application of the environmentally friendly viscosity reducer: Add the environmentally friendly viscosity reducer to the water-based drilling fluid at an addition amount of 1 wt%.

[0098] Example 8

[0099] This example provides a preparation method and application of an environmentally friendly viscosity reducer.

[0100] The preparation method of the environmentally friendly viscosity reducer is as follows: Weigh by weight: 65 parts of ferrous gluconate, 25 parts of the supported sulfonated montmorillonite prepared in Example 2, and 16 parts of the mPEG-modified nanoparticles prepared in Example 5, and mix them evenly to obtain the environmentally friendly viscosity reducer;

[0101] Application of the environmentally friendly viscosity reducer: Add the environmentally friendly viscosity reducer to the water-based drilling fluid at an addition amount of 1 wt%.

[0102] Example 9

[0103] This example provides a preparation method and application of an environmentally friendly viscosity reducer

[0104] The preparation method of the environmentally friendly viscosity reducer is as follows: Weigh by weight: 70 parts of ferrous gluconate, 30 parts of the supported sulfonated montmorillonite prepared in Example 3, and 18 parts of the mPEG-modified nanoparticles prepared in Example 6, and mix them evenly to obtain the environmentally friendly viscosity reducer;

[0105] Application of the environmentally friendly viscosity reducer: Add the environmentally friendly viscosity reducer to the water-based drilling fluid at an addition amount of 1 wt%.

[0106] Comparative Example 1

[0107] This comparative example is a blank control example, and the difference from Example 9 is that the environmentally friendly viscosity reducer is not added to the water-based drilling fluid.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 9 is that ferrous gluconate is not added.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 9 is that when preparing the supported sulfonated montmorillonite, the modification liquid is not added in step A2.

[0112] Comparative Example 4

[0113] The difference between this comparative example and Example 9 is that when preparing the mPEG-modified nanoparticles, step B3 is cancelled, and the anhydride-modified nanoparticles in step B2 are used to replace the mPEG-modified nanoparticles in equal amounts.

[0114] Performance test:

[0115] Add the environmentally friendly viscosity reducers prepared in Examples 7-9 and Comparative Examples 1-4 to the water-based drilling fluid at an addition amount of 1 wt%, and measure the apparent viscosity, plastic viscosity, and dynamic shear force of the samples. The specific test results are shown in Table 1 below;

[0116] The viscosity reducers prepared in Examples 7-9 and Comparative Examples 1-4 were mixed with the base slurry at a ratio of 1 g:9 mL to prepare a drilling base slurry, and the apparent viscosity, plastic viscosity, and dynamic shear force of the test samples were measured.

[0117] Table 1 - Data Sheet for Performance Detection of Drilling Fluid Samples

[0118]

[0119]

[0120] Table 2 - Data Sheet for Performance Detection of Drilling Base Slurry Samples

[0121]

[0122] Data Analysis:

[0123] Through comparative analysis of the data in Table 1 above, when the environmentally friendly viscosity reducer prepared in the present invention was added to the water-based drilling fluid at an addition amount of 1 wt%, the apparent viscosity of the drilling fluid decreased to 23.1 mPa·s, a decrease of 23.76% compared to Comparative Example 1 of the blank group; the plastic viscosity decreased to 17.3 mPa·s, a decrease of 15.61% compared to Comparative Example 1 of the blank group; the dynamic shear force decreased to 6.47 Pa, a decrease of 36.69% compared to Comparative Example 1 of the blank group. All the performance test data were better than those of the comparative examples.

[0124] Through comparative analysis of the data in Table 2 above, when the viscosity reducer prepared in the present invention was mixed with the base slurry at a ratio of 1 g:9 mL to reduce the viscosity of the base slurry, the apparent viscosity of the base slurry decreased to 12.3 mPa·s, a decrease of 32.79% compared to Comparative Example 1 of the blank group; the plastic viscosity decreased to 7.1 mPa·s, a decrease of 32.38% compared to Comparative Example 1 of the blank group; the dynamic shear force decreased to 5.10 Pa, a decrease of 39.43% compared to Comparative Example 1 of the blank group. All the performance test data were better than those of the comparative examples.

[0125] It shows that the present invention utilizes the charge regulation of ferrous gluconate, the sulfonated montmorillonite with electrostatic-hydrophobic synergistic dispersion, and the mPEG-modified nanoparticles with steric hindrance-lubrication effect to cooperate synergistically, significantly reducing the viscosity parameters of the water-based drilling fluid and its dynamic shear force, and having little environmental pollution and environmental protection performance.

[0126] The above content is only an example and explanation of the structure of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

[0127] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0128] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An environmentally friendly viscosity reducer, characterized in that: The invention comprises the following components by weight: 60-70 parts of ferrous gluconate, 20-30 parts of supported sulfonated montmorillonite and 15-18 parts of mPEG modified nanoparticles.

2. An environmentally friendly viscosity reducer according to claim 1, characterized in that: The supported sulfonated montmorillonite is obtained by processing the following steps: A1, diatomaceous earth and acid water are mixed, reacted at room temperature for 10-12 hours, and post-treated to obtain activated diatomaceous earth; A2. Sodium lignin sulfonate, purified water and sodium hydroxide are mixed, stirred at room temperature until the system is dissolved, activated diatomaceous earth is added to the reaction system, ultrasonic dispersion is performed for 30-50 minutes, dilute acid is added to the reaction system, pH of the system is adjusted to 3-4, stirring is continued for 20-30 minutes, and modified liquid is added to the reaction system. The reaction is kept warm for 5-6 hours, and post-processed to obtain supported sulfonated diatomaceous earth.

3. An environmentally friendly viscosity reducer according to claim 2, characterized in that: In step A1, the dosage ratio of the diatomite and the acid water is 1g:15-20mL, and the acid water is a 3-5mol / L hydrochloric acid solution; in step A2, the dosage ratio of the sodium lignin sulfonate, purified water, sodium hydroxide, activated diatomite and the modifying liquid is 2g:30mL:0.5g:7g:10mL, the modifying liquid is composed of octyltrimethoxysilane and anhydrous ethanol at 1g:10mL, and the dilute acid is 0.3-0.5mol / L hydrochloric acid.

4. An environmentally friendly viscosity reducer according to claim 1, characterized in that: The preparation method of the mPEG modified nanoparticles is as follows: anhydride modified nanoparticles, polyethylene glycol monomethyl ether, acetone and a catalyst are stirred and mixed, the temperature of the reaction system is increased to system reflux, the reaction is kept warm for 10-12 hours, and post-processed to obtain the mPEG modified nanoparticles.

5. An environmentally friendly viscosity reducer according to claim 4, characterized in that: The dosage ratio of the anhydride-modified nanoparticles, polyethylene glycol monomethyl ether, acetone and catalyst is 5g:3g:50mL:0.1g, and the catalyst is p-toluenesulfonic acid.

6. An environmentally friendly viscosity reducer according to claim 4, characterized in that: The preparation method of the anhydride-modified nanoparticles is as follows: under the protection of inert gas, olefin-modified nanoparticles and toluene are mixed and stirred, the temperature of the reaction system is increased to 70-80° C., the modification solution is added dropwise to the reaction system, the reaction is kept warm for 4-5 hours, and post-processed to obtain the anhydride-modified nanoparticles.

7. An environmentally friendly viscosity reducing agent according to claim 6, characterized in that: The usage ratio of the olefin-modified nanoparticles, toluene and the modification solution is 7g:50mL:4mL. The modification solution is composed of maleic anhydride, acrylic acid, toluene and initiator in a ratio of 2g:3g:5mL:0.2g. The initiator is benzoyl peroxide.

8. The environmentally friendly viscosity reducing agent according to claim 6, characterized in that: The preparation method of the olefin-modified nanoparticles is as follows: mixing ammonia water and ethanol solution, raising the temperature of the reaction system to 55-60° C., dropping a siloxane solution into the reaction system, keeping the temperature for 4-6 hours, and post-treating to obtain the olefin-modified nanoparticles.

9. An environmentally friendly viscosity reducing agent according to claim 8, characterized in that: The dosage ratio of the ammonia water, ethanol solution and siloxane solution is 1g:20mL:3g, the ethanol solution is composed of anhydrous ethanol, deionized water and emulsifier in the ratio of 5mL:5mL:0.2g, the emulsifier is octadecylamine polyoxyethylene ether, and the siloxane solution is composed of tetraethyl orthosilicate and 5-hexenyltriethoxysilane in the ratio of 3g:1g.

10. An application of an environmentally friendly viscosity reducer, characterized in that: The environmentally friendly viscosity reducer according to any one of claims 1 to 9 is applied to water-based drilling fluid as a viscosity reducer.

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