Acid-soluble NANO material and preparation method therefor and use thereof, and fracturing fluid

Abstract

An acid-soluble nano material and a preparation method therefor and a use thereof, and a fracturing fluid, relating to petrochemical technology. The hydrodynamic particle size D10 of molecular aggregates of the acid-soluble nano material in water is 2-10 μm, D50 is 8-31 μm, and D90 is 20-90 μm. The preparation method for the acid-soluble nano material comprises: carrying out hydroxylation treatment on an unsaturated fatty monoacid, and carrying out a contact reaction between the hydroxylated unsaturated fatty monoacid and a nano carbonate raw material; and carrying out amination treatment on a product of the contact reaction, wherein the nano carbonate raw material contains a nano calcium carbonate raw material and / or a nano magnesium carbonate raw material. The acid-soluble nano material has the dissolution performance meeting fracturing construction requirements, can realize multi-size plugging in a compact reservoir and improve the plugging rate of a pore throat, and can enter the pore throat for adsorption and space occupation to reduce the retention amount of the fracturing fluid, thereby reducing damage to the reservoir.

Description

Acid-soluble nanomaterial, preparation method and application thereof, and fracturing fluid

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202410154420.9, filed on February 2, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to petrochemical technology, in particular to an acid-soluble nanomaterial, a preparation method and application thereof, and a fracturing fluid containing the acid-soluble nanomaterial as a plugging agent. Background Art

[0004] In the development of low-permeability oil and gas reservoirs, fracturing is a primary production-increasing measure. Its purpose is to create a crack within the low-permeability reservoir, increasing the drainage area and boosting oil and gas production. Temporary fracturing uses plugging agents to form a filter cake in front of the high-permeability layer or increase the flow resistance of the high-permeability layer, thereby diverting the working fluid into the low-permeability layer.

[0005] Calcium carbonate, an acid-soluble material, has been used in plugging agent product development. After performing its plugging action, it can be acid-dissolved to promote flowback of the working fluid. However, since calcium carbonate particles can only form bridges and seal at pore throats or microfractures, the plugging effect is poor. Furthermore, the acid dissolution rate after temporary plugging as a plugging agent is too rapid, resulting in unstable working fluid system operation, poor flowback effectiveness, and the potential for formation damage.

[0006] Existing technologies often modify calcium carbonate particles before using them as plugging agents. Although this can improve the plugging effect, there are still some difficult-to-overcome problems in their application. For example, calcium carbonate particles or existing modified calcium carbonate still have low adsorption capacity and low plugging rate for pore throats of multiple sizes when plugging reservoir pores and throats.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems existing in the prior art and provide an acid-soluble nanomaterial, a preparation method and application thereof, and a fracturing fluid. The acid-soluble nanomaterial not only has solubility properties that meet the requirements of fracturing construction, but also can achieve multi-size plugging in tight reservoirs, improve the plugging rate of pore throats, and can enter the pore throats to adsorb and occupy space, thereby reducing the retention of fracturing fluid and reducing damage to the reservoir.

[0009] In order to achieve the above object, the present invention provides an acid-soluble nanomaterial in the first aspect, wherein the molecular aggregate hydrodynamic particle size D of the acid-soluble nanomaterial in water is 10 2-10μm, D 50 8-31μm, D 9020-90μm.

[0010] The second aspect of the present invention provides a method for preparing an acid-soluble nanomaterial, which comprises: subjecting an unsaturated fatty monocarboxylic acid to a hydroxylation treatment and then subjecting the unsaturated fatty monocarboxylic acid to a contact reaction with a nanocarbonate raw material; and subjecting the product of the contact reaction to an amination treatment; wherein the nanocarbonate raw material contains a nano-calcium carbonate raw material and / or a nano-magnesium carbonate raw material.

[0011] The third aspect of the present invention provides the use of the acid-soluble nanomaterial as described above or the acid-soluble nanomaterial prepared according to the method as described above in oil production working fluid, preferably as a plugging agent for fracturing fluid.

[0012] A fourth aspect of the present invention provides a fracturing fluid containing the acid-soluble nanomaterial as described above or the acid-soluble nanomaterial prepared according to the method as described above.

[0013] Through the above technical solution, the beneficial effects of the present invention are as follows: the acid-soluble nanomaterial provided by the present invention has a specific molecular aggregate hydrodynamic particle size in water, which can achieve multi-size plugging in tight reservoirs, improve the plugging rate of pore throats, and can enter the pore throats to adsorb and occupy space, reducing the retention of fracturing fluid and reducing the damage of thickeners in the fracturing fluid to the reservoir. Furthermore, the acid dissolution rate of the acid-soluble nanomaterial can meet the construction process requirements of tight reservoirs, reduce damage to the formation after the plugging operation, and effectively dissolve the acid-soluble nanomaterial through the acidification process, promote the return of the working fluid, reduce the filtration loss of the fracturing fluid system, and solve the formation damage problem easily caused by general inorganic material plugging agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG1 is an infrared spectrum of the acid-soluble nanomaterial obtained in Example 1;

[0015] FIG2 is a scanning electron microscope morphology image and EDS spectrum image of the acid-soluble nanomaterial obtained in Example 1;

[0016] FIG3 is a scanning electron microscope morphology image and EDS spectrum image of unmodified nano calcium carbonate particles;

[0017] FIG4 is an optical microscope observation diagram of the aqueous solution of the acid-soluble nanomaterial obtained in Example 1;

[0018] FIG5 is an optical microscope observation diagram of unmodified nano calcium carbonate particles;

[0019] FIG6 is an optical microscope observation diagram of an aqueous solution of unmodified nano-calcium carbonate particles. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] The first aspect of the present invention provides an acid-soluble nanomaterial, wherein the hydrodynamic particle size D of the molecular aggregate of the acid-soluble nanomaterial in water is 10 2-10 μm, specifically 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, or any value between the above two values; D 50 8-31 μm, specifically 8 μm, 15 μm, 20 μm, 25 μm, 31 μm, or any value between the above two values; D 90 It is 20-90 μm, specifically 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or any value between the above two values.

[0022] The inventors of the present invention unexpectedly discovered during the research and development process that acid-soluble nanomaterials have a specific molecular aggregate hydrodynamic particle size D in water. 10 、D 50 、D 90 It has good rock adsorption properties, can achieve multi-size plugging in tight reservoirs, improve the plugging rate of pore throats, and can enter the pore throats to adsorb and occupy space to reduce the retention of fracturing fluid and reduce damage to the reservoir; after reservoir construction, the acidification process is used to effectively dissolve the acid-soluble nanomaterial, promote the return of the working fluid, reduce the filtration loss of the fracturing fluid system, and solve the formation damage problem that is easily caused by general inorganic material plugging agents.

[0023] In the present invention, the hydrodynamic particle size of the molecular aggregates of acid-soluble nanomaterials in water refers to the apparent particle size of the molecular aggregates formed by the acid-soluble nanomaterials in water. The test method is as follows: the acid-soluble nanomaterials are measured by wet method using a Fritsch 22 laser particle size analyzer. The test software MaScontrol is opened and the cleaning and calibration program is clicked to complete the cleaning and calibration of the instrument before the measurement is performed. The test sample is prepared and added to the funnel in small amounts and multiple times using a medicine spoon. The sample is dispersed using clean water and ultrasound. After the addition of the sample is completed, the instrument automatically performs three sets of parallel data tests. If the error does not exceed 5%, the test dynamic particle size distribution report is output. After the test is completed, the instrument is cleaned and dried, and then turned off. 10 、D 20 、D 50 、D70 and D 90 They respectively represent the particle sizes corresponding to when the cumulative particle size distribution number of the sample reaches 10%, 20%, 50%, 70% and 90% (manually accumulate the percentages of all particle sizes before or after this particle size); its physical meaning is that the number of particles with a size smaller than this particle size accounts for 10%, 20%, 50%, 70% and 90% of the total number of particles.

[0024] According to the present invention, the acid-soluble nanomaterial preferably has an acid solubility of 50-80%, more preferably 65-80%, in a 15% by weight hydrochloric acid solution at 90°C for 1 hour; and an acid solubility of 90% or more after 2 hours at 90°C. In this manner, the acid-soluble nanomaterial not only ensures the return of working fluid after oil extraction operations, but also achieves an acid dissolution rate that better meets the time requirements of the post-fracturing construction process. The acid dissolution time can meet the construction process requirements for tight reservoirs, reducing damage to the formation after plugging operations.

[0025] In the present invention, the specific detection process of the acid solubility rate is as follows: 2 g of acid-soluble nanomaterial is placed in an oven and dried to constant weight, recorded as m1, added to 250 mL of 15 wt% hydrochloric acid solution, stirred evenly, covered and kept at 90 ° C for 1 hour or 2 hours, stopped heating, taken out and filtered, dried to constant weight and weighed, recorded as m2, and then the acid solubility rate S is calculated according to formula (I):

[0026] S=(m1-m2) / m1×100% formula (I),

[0027] Where: S is the acid solubility (%); m1 is the sample mass (g); m2 is the residue mass (g).

[0028] According to the present invention, preferably, the hydrodynamic particle size D of the molecular aggregate of the acid-soluble nanomaterial in water is 20 4-22μm, D 70 The inventors have found that under this preferred embodiment, the fluid loss can be effectively reduced during the fracturing process, and multi-scale plugging of reservoirs of different sizes can be achieved during fracturing. It has a high degree of compatibility with the pore throats of tight sandstone reservoirs and can meet the fracturing transformation technology requirements of more low-permeability tight gas reservoirs.

[0029] In the present invention, the acid-soluble nanomaterial can be any nanoscale acid-soluble material capable of forming the above-mentioned specific molecular aggregate hydrodynamic particle size in water, such as a modified nano-calcium carbonate material, a modified nano-magnesium carbonate material, etc. Preferably, the acid-soluble nanomaterial comprises carbonate particles and a modifier attached to the surface of the carbonate particles, wherein the carbonate particles comprise calcium carbonate particles and / or magnesium carbonate particles, and the modifier comprises a derivative formed by replacing at least one hydroxyl group of a polyhydroxy fatty acid with an amino-containing substituent.

[0030] The present invention modifies the nano calcium carbonate raw material and / or nano magnesium carbonate raw material so that the nano calcium carbonate raw material has a specific molecular aggregate hydrodynamic particle size D in water. 10 、D 50 、D 90 The obtained modified nano-calcium carbonate material and / or modified nano-magnesium carbonate material not only has an acid dissolution time that meets the construction process requirements of tight reservoirs and reduces damage to the formation after the plugging operation, but also utilizes the acidification process to effectively dissolve the modified nano-calcium carbonate material and / or modified nano-magnesium carbonate material, promotes the return of the working fluid, and reduces the filtration loss of the fracturing fluid system. In addition, it has good rock adsorption properties, can achieve multi-size plugging in tight reservoirs, improve the plugging rate of pore throats, and can enter the pore throats to absorb and occupy space to reduce the retention of fracturing fluid and reduce damage to the reservoir. Further preferably, the carbonate particles are calcium carbonate particles.

[0031] Among them, the carboxyl group contained in the modifier can form a stable chemical bond with calcium carbonate and / or magnesium carbonate to attach to the surface of calcium carbonate particles and / or magnesium carbonate particles. The modifier makes the acid-soluble nanomaterial belong to an organic / inorganic nanocomposite material. Combined with the bridging effect of inorganic nanoparticles and the deformation performance of organic particles, it forms a specific molecular aggregate hydrodynamic particle size in water, has good dispersion performance and pore throat plugging performance, and can be used as an excellent plugging agent when applied to the oil production working fluid system to achieve multi-size plugging in tight reservoirs, improve the plugging rate of pore throats, and can enter the pore throats to absorb and occupy space, making the plugging of the formation more successful and effectively improving The plugging rate during temporary plugging and fracturing in oil production is improved, and the retention volume of fracturing fluid is reduced. The surface modifier of the calcium carbonate particles and / or magnesium carbonate particles of the acid-soluble nanomaterial can be hydrolyzed and removed under the combined action of high temperature and acidic conditions, exposing the internally coated calcium carbonate particles and / or magnesium carbonate particles. The calcium carbonate particles and / or magnesium carbonate particles are then decomposed by acid, so that the material has excellent acid solubility and forms a suitable acid dissolution rate. After the temporary plugging and fracturing construction is completed, the acidification process can be used to effectively dissolve the acid-soluble nanomaterial, promote the return of the working fluid, and reduce the filtration loss during the fracturing process. The acidolysis rate and acidolysis time can meet the time requirements of the post-fracturing construction process of the tight reservoir.

[0032] According to the present invention, preferably, the acid-soluble nanomaterial has a retention reduction rate of 4.5% or more, preferably 25% or more, for a fracturing fluid composed of 99.7wt% solvent + 0.1wt% thickener + 0.1wt% drainage agent + 0.1wt% clay stabilizer and a retention amount of 12.5 mg / g, so as to further reduce the adsorption damage of the working fluid system to the reservoir.

[0033] In order to verify the adsorption and space-occupying effect of the acid-soluble nanomaterial provided by the present invention on sandstone, thereby preventing acrylamide homopolymer in the fracturing fluid system from entering the sandstone pores, by testing its effect on the retention of the acrylamide homopolymer fracturing fluid system in the reservoir, it was found that the acid-soluble nanomaterial provided by the present invention can be adsorbed in the tiny pore throats of the sandstone, preventing the adsorption of the polyacrylamide system, allowing more polyacrylamide to flow out and reducing the retention amount, thereby indicating that the acid-soluble nanomaterial can effectively improve the pore throat blocking rate of the fracturing fluid.

[0034] The specific detection process for the effect of the acrylamide homopolymer system on the retention of the reservoir is as follows: first, the sandstone sample is made into 0.21-0.30 mm (70-50 mesh) sandstone particles and loaded into a sand filling tube. The core of the sand filling tube with a diameter of 2.5 cm and a length of 15 cm is dried and weighed; a solution (1000 mg / L anionic polyacrylamide solution) is prepared, and the acid-soluble nanomaterial provided by the present invention is added to each of the solutions at a displacement rate of 1 mL / min for 5 hours. The solution concentration in the outflow sample is measured by the starch-chromium iodide method, and the retention of the polyacrylamide in the formation is calculated using the material balance method according to formula (II);

[0035] Q = (ρ0V0-ρ1V1) / W Formula (II), retention of polyacrylamide in the core, mg / g;

[0036] ρ0-concentration of injected polyacrylamide solution, mg / L; V0-volume of injected polyacrylamide, mL; ρ1-concentration of the sample flowing out of the core outlet, mg / L; V1-volume of the sample flowing out of the core outlet, mL; W-dry mass of the core, g.

[0037] The retention reduction rate refers to the ratio of the change in retention before and after the addition of the acid-soluble nanomaterial provided by the present invention (the amount of the acid-soluble nanomaterial added is preferably 0.5-2% by weight) to the initial retention of the fracturing fluid, and the calculation formula is shown in Formula (III);

[0038] In formula (III):

[0039] ΔQ——reduction rate of fracturing fluid retention, %;

[0040] Q0——Retention amount of the fracturing fluid without the acid-soluble nanomaterial provided by the present invention, mg / g;

[0041] Q1——Retention amount of fracturing fluid after adding the acid-soluble nanomaterial provided by the present invention, mg / g.

[0042] In the present invention, the solvent for the fracturing fluid can be water, the thickener can be any substance that can serve as a thickener in fracturing fluid, the drainage aid can be any substance that can serve as a drainage aid in fracturing fluid, and the clay stabilizer can be any substance that can serve as a clay stabilizer in fracturing fluid. Exemplarily, the thickener is an acrylamide homopolymer and / or a copolymer of acrylamide and another monomer, wherein the other monomer is selected from at least one of acryloyloxyethyltrimethylammonium chloride, sodium acrylate, and acrylic acid. More preferably, the copolymer of acrylamide and another monomer is at least one of an acrylamide-acryloyloxyethyltrimethylammonium chloride copolymer, an acrylamide-sodium acrylate-acrylic acid copolymer, and an acrylamide-acryloyloxyethyltrimethylammonium chloride-sodium acrylate-acrylic acid copolymer. Furthermore, preferably, the molecular weight of the acrylamide homopolymer is greater than 18 million, and the molecular weight of the copolymer of acrylamide and another monomer is greater than 18 million. The drainage aid is polyoxyethylene amine ether and / or polyoxyethylene fatty alcohol ether, preferably oleylamine polyoxyethylene ether and / or rosin amine polyoxyethylene ether, and preferably at least one of polyoxyethylene lauryl alcohol ether, polyoxyethylene tetradecyl alcohol ether, polyoxyethylene cetyl alcohol ether, and polyoxyethylene octadecyl alcohol ether. The clay stabilizer is dimethylamine quaternary ammonium salt and / or polyquaternium salt, preferably polyquaternium-126.

[0043] In the present invention, a fracturing fluid comprising a solvent, a thickener, a drainage aid, and a clay stabilizer with a retention rate of 12.5 mg / g can be formulated as follows: 99.7 wt% water + 0.1 wt% acrylamide homopolymer with a relative molecular weight of 18 million + 0.1 wt% drainage aid + 0.1 wt% dimethylamine quaternary ammonium salt. Fracturing fluids meeting these requirements can be, for example, the SPR series of fracturing fluids produced by Dongying Shipurui Petroleum Engineering Technology Co., Ltd., for example, a mixture of acrylamide homopolymer (thickener SPR-08), oleylamine polyoxyethylene ether (drainage aid SPR-201), and dimethylamine quaternary ammonium salt (clay stabilizer SPR-103) in the aforementioned proportions.

[0044] According to the present invention, preferably, the structural formula of the modifier is as shown in formula (I) and the carbon chain length is greater than 20.

[0045] Among them, R I 、R II Each is independently hydrogen or C1-C3 alkyl, specifically hydrogen, methyl, ethyl, n-propyl, isopropyl; R IIIis hydrogen or C1-C20 alkyl (including linear alkyl, branched alkyl, cycloalkyl), for example, hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, etc.; m is an integer of 0-20; R IV and R V One of them is an amino-containing substituent and the other is hydrogen, or both are amino-containing substituents; the amino-containing substituent can be an amino group, an imino group, a nitro group, an alkyl group having an amino group, an aromatic group having an amino group, etc.

[0046] In the present invention, the morphology of the acid-soluble nanomaterial can be detected by the following steps: After drying the acid-soluble nanomaterial under infrared light, a small amount is placed on conductive tape on a copper support and gently pressed with lint-free paper to firmly adhere the sample particles, while removing any powder sample adhering to the sides of the copper support. The sample is then loaded into an apparatus, evacuated, and conductively tested, and the morphology and elemental analysis of the sample powder is performed using a Quanta 250 scanning electron microscope. As shown in Figure 1, the acid-soluble nanomaterial (modified nano-calcium carbonate material) provided by the present invention clearly exhibits modified units attached to the particle surface compared to the calcium carbonate shown in Figure 2.

[0047] According to the present invention, preferably, the carbon chain content of the modifier is 5-15% by weight, based on the total amount of the acid-soluble nanomaterial; further preferably, the amino group content is 0.05-0.6% by weight. The inventors have found that under this preferred embodiment, the fluid loss during the fracturing process and the retention of the fracturing fluid in the pore throat can be further reduced.

[0048] In the present invention, the carbon and amino content can be determined by combining H NMR spectroscopy, C NMR spectroscopy and infrared detection, or by combining infrared detection with scanning electron microscopy.

[0049] The second aspect of the present invention provides a method for preparing an acid-soluble nanomaterial, which comprises: subjecting an unsaturated fatty monocarboxylic acid to a hydroxylation treatment and then subjecting the unsaturated fatty monocarboxylic acid to a contact reaction with a nanocarbonate raw material; and subjecting the product of the contact reaction to an amination treatment; wherein the nanocarbonate raw material contains a nano-calcium carbonate raw material and / or a nano-magnesium carbonate raw material.

[0050] The preparation method of the acid-soluble nanomaterial provided by the present invention not only has a specific molecular aggregate hydrodynamic particle size in water, forming good dispersion performance and rock adsorption performance, but also significantly improves the multi-size plugging rate during construction, can enter the pore throat to absorb and occupy space, and reduce the retention of fracturing fluid. In addition, the acid dissolution rate can meet the construction process requirements of tight reservoirs, reducing damage to the formation after the plugging operation.

[0051] In the present invention, the particle size of the nano calcium carbonate raw material and the nano magnesium carbonate raw material is nanometer scale, preferably 30-150 nm, and can be commercially obtained.

[0052] In the present invention, preferably, the structural formula of the unsaturated fatty monocarboxylic acid is as shown in formula (II) and the carbon chain length is greater than 20.

[0053] Among them, R I 、R II are each independently hydrogen or C1-C3 alkyl, R III is hydrogen or a C1-C20 alkyl group, and m is an integer from 0 to 20. For example, the unsaturated fatty monoacid may be docos-13-enoic acid, hexacos-7-enoic acid, pentacos-9-enoic acid, tetracos-20-enoic acid, octacos-10-enoic acid, etc., preferably hexacos-7-enoic acid and / or docos-13-enoic acid, and more preferably docos-13-enoic acid. The inventors have discovered that this preferred embodiment further enhances the rock adsorption of the acid-soluble nanomaterial and improves the plugging rate.

[0054] According to the present invention, preferably, the hydroxylation process comprises: mixing the unsaturated fatty monobasic acid with a hydroxylating agent in the presence of a C1-C5 organic acid. The C1-C5 organic acid may be formic acid, acetic acid, propionic acid, butyric acid, or valeric acid, preferably formic acid.

[0055] According to the present invention, preferably, the hydroxylation agent is a peroxide, more preferably hydrogen peroxide. The inventors have found that under this preferred embodiment, it is beneficial to promote the addition reaction of formic acid and monounsaturated fatty acids and improve the reaction efficiency.

[0056] According to the present invention, preferably, the mixing reaction process includes: mixing the unsaturated fatty monobasic acid with a C1-C5 organic acid, dropwise adding the hydroxylation reagent at 30-35°C, and then heating to 65-70°C for 4-6 hours. The inventors have discovered that this preferred embodiment improves the efficiency of polyhydroxy fatty acid synthesis.

[0057] According to the present invention, the weight ratio of the unsaturated fatty acid, C1-C5 organic acid and hydroxylating agent is 1-2:1-2:1. The inventors have found that under this preferred embodiment, the conversion rate of the addition reaction between the hydroxylating agent and the monounsaturated fatty acid is improved.

[0058] In the present invention, the reaction solution obtained by the mixed reaction can be separated into layers to remove the water layer, the oil layer can be washed with hot water until neutral, a small amount of acetone can be added to dissolve the oil layer, and the water and solvent can be removed by rotary evaporation to obtain the first product (polyhydroxy fatty acid).

[0059] According to the present invention, preferably, the weight ratio of the hydroxylated unsaturated fatty monoacid to the nano-carbonate raw material is 1:4-8.

[0060] According to the present invention, preferably, the contact reaction conditions include: a temperature of 30-70°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C, or any value therebetween; and a reaction time of 0.5-1.5 hours, specifically 0.5 hours, 0.7 hours, 0.9 hours, 1.1 hours, 1.3 hours, 1.5 hours, or any value therebetween. The inventors have found that this preferred embodiment facilitates the modification of calcium carbonate and / or magnesium carbonate by polyhydroxy fatty acids, thereby improving reaction efficiency.

[0061] In the present invention, the contact reaction is carried out in the presence of a solvent. For example, the nano-calcium carbonate raw material and / or the nano-magnesium carbonate raw material can be dispersed in anhydrous ethanol, and then the nano-calcium carbonate raw material and the first product are shaken and stirred in an ultrasonic stirrer to carry out a contact reaction, and the product of the contact reaction (the second product) is obtained by filtering and drying.

[0062] According to the present invention, preferably, the amination treatment process comprises: reacting the product of the contact reaction with an aromatic sulfonyl halide in a first stage to obtain a third product, and then reacting the product with a diamine in a second stage in the presence of a catalyst.

[0063] According to the present invention, the aromatic sulfonyl halide can be benzenesulfonyl chloride, benzenesulfonyl fluoride, benzenesulfonyl bromide, or benzenesulfonyl iodide. Preferably, the aromatic sulfonyl halide is benzenesulfonyl chloride, more preferably at least one of p-toluenesulfonyl chloride, p-ethylbenzenesulfonyl chloride, m-toluenesulfonyl chloride, and m-ethylbenzenesulfonyl chloride; further preferably, p-toluenesulfonyl chloride. The diamine is selected from at least one of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl, and 4,4'-diaminodiphenyl sulfone; further preferably, p-phenylenediamine. The inventors have discovered that this preferred embodiment facilitates surface modification of the contact reaction product, improving the blocking effect.

[0064] According to the present invention, preferably, the weight ratio of the aromatic sulfonyl halide to the product of the contact reaction is 1:0.8-1.2.

[0065] According to the present invention, preferably, the first stage reaction process includes: adding the product of the contact reaction to the solution containing the aromatic sulfonyl halide in multiple portions. The inventors have found that under this preferred embodiment, the reaction efficiency of the aromatic sulfonyl halide and the product of the contact reaction is improved.

[0066] Further preferably, the solvent of the solution containing the aromatic sulfonyl halide is a strong base solution with a concentration of 20-30% by weight or pyridine, and the strong base is preferably sodium hydroxide and / or potassium hydroxide; the solvent of the solution containing the aromatic sulfonyl halide is further preferably pyridine.

[0067] According to the present invention, preferably, the conditions for the first stage reaction include: a temperature of -5 to 5°C, specifically -5°C, -3°C, -1°C, 0°C, 1°C, 3°C, 5°C, or any value therebetween; and a reaction time of 4 to 7 hours, specifically 4 hours, 5 hours, 6 hours, 7 hours, or any value therebetween. The inventors have found that under this preferred embodiment, the reaction efficiency is improved.

[0068] Illustratively, the process of the first stage reaction is: dissolving the aromatic sulfonyl halide in pyridine, stirring in an ice bath, adding the product of the contact reaction in small amounts and multiple times, and reacting for a total of 4-7 hours.

[0069] According to the present invention, preferably, the weight ratio of the product of the first stage reaction to the diamine is 2.4-3: 1. The inventors have found that under this preferred embodiment, it is beneficial to introduce amino groups on the surface of the third product, thereby increasing the yield of acid-soluble nanomaterials.

[0070] According to the present invention, preferably, the second stage reaction uses a concentrated strong alkali solution as a reaction solvent, and the strong alkali is preferably sodium hydroxide and / or potassium hydroxide with a concentration of 20-30% by weight.

[0071] According to the present invention, preferably, the catalyst is a phase transfer catalyst, more preferably tetrabutylammonium bromide and / or benzyltriethylammonium chloride. The inventors have found that under this preferred embodiment, it is beneficial to improve the conversion rate of amino groups introduced into the surface of the product of the first stage reaction.

[0072] According to the present invention, preferably, the second-stage reaction conditions include: using a strong alkaline solution with a concentration of 20-30% by weight as the reaction solvent, a temperature of 95-105°C, and a reaction time of 7-12 hours. The inventors have found that under this preferred embodiment, the yield of the acid-soluble nanomaterial with attached structural unit a is improved.

[0073] The third aspect of the present invention provides the use of the acid-soluble nanomaterial as described above or the acid-soluble nanomaterial prepared according to the method as described above in oil production working fluid.

[0074] In the present invention, the oil production working fluid can be a fracturing fluid, a drilling fluid, a completion fluid, or any other working fluid; preferably, the above-mentioned acid-soluble nanomaterial is used as a plugging agent for the fracturing fluid. During on-site construction, it plays the role of a plugging agent, has good dispersibility and rock adsorption, has high plugging strength and good stability, can enter the pore throat and absorb and occupy space to reduce the retention of the fracturing fluid; after the construction is completed, the acid-soluble nanomaterial, based on its own acid solubility, can be acidified and dissolved, effectively reducing the residue content of the working fluid, reducing damage to the reservoir matrix, and can effectively reduce the filtration loss of the working fluid, promote the rapid return of the fracturing fluid to the reservoir, and improve the return efficiency of the working fluid.

[0075] A fourth aspect of the present invention provides a fracturing fluid containing the acid-soluble nanomaterial as described above.

[0076] According to the present invention, preferably, the content of the acid-soluble nanomaterial is 0.5-2% by weight based on the total amount of the fracturing fluid. The inventors have found that under this preferred embodiment, it is beneficial to better improve the sealing strength and stability, reduce the filtration loss of the fracturing fluid, and reduce the damage of the fluid to the formation.

[0077] According to the present invention, the fracturing fluid preferably further comprises, based on the total amount of the fracturing fluid, 0.1-1% by weight of a thickener, 0.1-1% by weight of a drainage aid, and 0.1-1% by weight of a clay stabilizer, with the remainder being a solvent (e.g., water). The fracturing fluid provided by the present invention, by adding the acid-soluble nanomaterial provided above to an existing conventional fracturing fluid system, can significantly improve the plugging rate compared to the initial fracturing fluid system and enhance the flowback efficiency of the working fluid after construction.

[0078] According to the present invention, preferably, the thickener is an acrylamide homopolymer and / or a copolymer of acrylamide and another monomer, wherein the other monomer is selected from at least one of acryloyloxyethyltrimethylammonium chloride, sodium acrylate, and acrylic acid. Further preferably, the copolymer of acrylamide and another monomer is at least one of an acrylamide-acryloyloxyethyltrimethylammonium chloride copolymer, an acrylamide-sodium acrylate-acrylic acid copolymer, and an acrylamide-acryloyloxyethyltrimethylammonium chloride-sodium acrylate-acrylic acid copolymer. Further preferably, the molecular weight of the acrylamide homopolymer is greater than 18 million, and the molecular weight of the copolymer of acrylamide and another monomer is greater than 18 million.

[0079] According to the present invention, preferably, the drainage aid is polyoxyethylene amine ether and / or polyoxyethylene fatty alcohol ether. Further preferably, the polyoxyethylene amine ether is oleylamine polyoxyethylene ether and / or rosin amine polyoxyethylene ether; and the polyoxyethylene fatty alcohol ether is at least one of polyoxyethylene lauryl alcohol ether, polyoxyethylene tetradecyl alcohol ether, polyoxyethylene cetyl alcohol ether, and polyoxyethylene stearyl alcohol ether.

[0080] According to the present invention, preferably, the clay stabilizer is dimethylamine quaternary ammonium salt and / or polyquaternium salt, and the polyquaternium salt is preferably polyquaternium-126.

[0081] The present invention will be described in detail below through examples.

[0082] In the following examples, the nano-calcium carbonate raw material was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., product model XFI11-2, with a particle size of 50-100 nm; the nano-magnesium carbonate raw material was purchased from Ningbo Luofei Nanotechnology Co., Ltd., CAS No. 546-93-0, with a particle size of 50-80 nm; erucic acid (docosa-13-enoic acid) was purchased from Shanghai Aladdin Technology Co., Ltd., CAS No. 112-86-7; hexacos-7-enoic acid was purchased from Shanghai Aladdin Technology Co., Ltd., CAS No. 66274-43-9; unless otherwise specified, the remaining raw materials and reagents are conventional commercially available products.

[0083] In the following examples, the specific detection process of the acid solubility rate is as follows: 2 g of acid-soluble nanomaterial is placed in an oven and dried to constant weight, recorded as m1, added to 250 mL of 15 wt% hydrochloric acid solution, stirred evenly, covered and kept at 90 ° C for 1 h or 2 h, stopped heating, taken out and filtered, dried to constant weight and weighed, recorded as m2, and then the acid solubility rate S is calculated according to formula (I):

[0084] S=(m1-m2) / m1×100% formula (I),

[0085] Where: S is the acid solubility (%); m1 is the sample mass (g); m2 is the residue mass (g).

[0086] In order to verify whether the acid-soluble nanomaterials block the pore throats, the filtration loss of the fracturing fluid added with acid-soluble nanomaterials was measured using a high-temperature and high-pressure filtration tester. The specific filtration loss test was carried out using a slab processed from a core of a tight sandstone reservoir. The pore diameter of the sample was between 0.01 and 20 μm. The detection process referred to the industry standard "SY / T 5107-2016 Performance Evaluation Method of Water-Based Fracturing Fluid".

[0087] In order to verify the adsorption and occupying effect of the acid-soluble nanomaterials provided by the present invention on sandstone, thereby preventing acrylamide homopolymers in the fracturing fluid system from entering the sandstone pores, the retention of the fracturing fluid after adding the acid-soluble nanomaterials and the retention reduction rate before and after addition were measured. The specific process is: first, the sandstone sample is made into 0.21-0.3mm (70-50 mesh) sandstone particles and loaded into the sand-filling tube, and the sand-filling tube core with a diameter of 2.5cm and a length of 15cm is dried and weighed; a solution (1000mg / L anionic polyacrylamide solution) is prepared, and the acid-soluble nanomaterials are added respectively and displaced at 1mL / min for 5h, and the starch-chromium iodide method is used to determine the solution concentration in the outflow sample, and the material balance method is used to calculate the retention of polyacrylamide in the formation according to formula (II);

[0088] Q = (ρ0V0-ρ1V1) / W Formula (II), retention of polyacrylamide in the core, mg / g;

[0089] ρ0-concentration of injected polyacrylamide solution, mg / L; V0-volume of injected polyacrylamide, mL; ρ1-concentration of the sample flowing out of the core outlet, mg / L; V1-volume of the sample flowing out of the core outlet, mL; W-dry mass of the core, g.

[0090] The retention reduction rate refers to the ratio of the change in retention before and after the addition of the acid-soluble nanomaterial provided by the present invention (the addition amount of the acid-soluble nanomaterial is preferably 0.5-2 weight %) to the initial retention of the fracturing fluid, and is calculated as shown in formula (III);

[0091] In formula (III):

[0092] ΔQ——reduction rate of fracturing fluid retention, %;

[0093] Q0——Retention amount of the fracturing fluid without the acid-soluble nanomaterial provided by the present invention, mg / g;

[0094] Q1——Retention amount of fracturing fluid after adding the acid-soluble nanomaterial provided by the present invention, mg / g.

[0095] The hydrodynamic particle size test method for molecular aggregates of acid-soluble nanomaterials in water is as follows: the acid-soluble nanomaterials are used to determine the particle size of modified calcium carbonate dispersed in water using a Fritsch 22 laser particle size analyzer using a wet method, and the liquid medium (using water) dispersion and measurement method in the reference standard GB / T19077-2016 "Particle Size Analysis Laser Diffraction Method" is used for wet testing at room temperature 20-25°C and normal pressure. The specific process is: open the test software MaScontrol and click the cleaning and calibration program to complete the cleaning and calibration of the instrument, and then perform the measurement; prepare the test sample, add the sample to the funnel in small amounts and multiple times with a medicine spoon, and disperse the sample with clean water and ultrasound. After the addition is completed, the instrument automatically performs three sets of parallel data tests. If the error does not exceed 5%, the test dynamic particle size distribution report is output. After the test is completed, the instrument is cleaned and dried, and then turned off. Among them, the frequency of the laser particle size analyzer is 50-60HZ, and the pump speed is 40L / min.

[0096] Example 1

[0097] 1) 16 g of erucic acid and 14 g of formic acid were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 32° C. with stirring. 10 g of hydrogen peroxide was then added dropwise at a uniform rate. The system temperature was adjusted to 68° C., the reaction temperature, and the reaction was stopped after 5 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid); 90 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added to the mixture. The mixture was stirred and shaken in an ultrasonic stirrer at 65° C. for 1 h. The mixture was filtered and dried to obtain the second product (polyhydroxy erucic acid-grafted nano-calcium carbonate);

[0098] 2) 10 g of p-toluenesulfonyl chloride was dissolved in 20 mL of pyridine and stirred in an ice bath. A total of 10 g of the second product was added in small amounts (about 0.5 g each time) for a total reaction time of 6 h to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 28 g of the third product was mixed with 10 g of p-phenylenediamine in a 25 wt% sodium hydroxide solution in the presence of a phase transfer catalyst, tetrabutylammonium bromide, and magnetic stirring was performed. The mixture was heated to 100° C. and refluxed for 10 h. The modified nano-calcium carbonate material was obtained as an acid-soluble nanomaterial after drying, filtration, and rotary evaporation.

[0099] Example 2

[0100] 1) 20 g of erucic acid and 18 g of formic acid were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 35° C. with stirring. 10 g of hydrogen peroxide was then added dropwise at a uniform rate. The system temperature was adjusted to 70° C. and the reaction was stopped after 4 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid); 100 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added. The mixture was stirred and reacted in an ultrasonic stirrer at 70° C. for 0.5 h. The mixture was filtered and dried to obtain the second product (polyhydroxy erucic acid-grafted nano-calcium carbonate);

[0101] 2) 10 g of p-toluenesulfonyl chloride was dissolved in a 20 wt% sodium hydroxide solution, stirred in an ice bath, and a total of 9 g of the second product was added in small amounts (about 0.4 g each time) for a total reaction of 7 h to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 24 g of the third product was mixed with 10 g of p-phenylenediamine in a 20 wt% sodium hydroxide solution in the presence of a phase transfer catalyst, tetrabutylammonium bromide, and magnetic stirring. The mixture was heated to 95° C. and refluxed for 12 h. The modified nano-calcium carbonate material was obtained by drying, filtering, and rotary evaporation as an acid-soluble nanomaterial.

[0102] Example 3

[0103] 1) 12 g of erucic acid and 10 g of formic acid were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 30° C. with stirring. 10 g of hydrogen peroxide was then added dropwise at a uniform rate. The system temperature was adjusted to 65° C. and the reaction was stopped after 6 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid); 80 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added. The mixture was stirred and shaken in an ultrasonic stirrer at 30° C. for 1.5 h. The reaction was filtered and dried to obtain the second product (polyhydroxy erucic acid-grafted nano-calcium carbonate);

[0104] 2) 10 g of p-ethylbenzenesulfonyl chloride was dissolved in a 30 wt % sodium hydroxide solution, stirred in an ice bath, and a total of 12 g of the second product was added in small amounts (about 0.6 g each time) for a total reaction of 4 h to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 30 g of the third product was mixed with 10 g of p-phenylenediamine in a 30 wt % sodium hydroxide solution in the presence of a phase transfer catalyst, benzyltriethylammonium chloride, and stirred with a magnetic stirrer. The mixture was heated to 105° C. and refluxed for 7 h. The modified nano-calcium carbonate material was obtained by drying, filtering, and rotary evaporation as an acid-soluble nanomaterial.

[0105] Example 4

[0106] The acid-soluble nanomaterial was prepared according to the method of Example 1, except that the erucic acid in step 1) was replaced by hexacos-7-enoic acid.

[0107] Example 5

[0108] The acid-soluble nanomaterial was prepared according to the method of Example 1, except that the p-phenylenediamine in step 2) was replaced by 1,4-butanediamine.

[0109] Example 6

[0110] Acid-soluble nanomaterials were prepared according to the method of Example 1, except that step 1) was replaced by:

[0111] 1) 16 g of erucic acid, 14 g of formic acid, and 10 g of hydrogen peroxide were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 68° C. with stirring. The reaction was stopped after 5 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid). 90 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added to the mixture. The mixture was stirred and shaken in an ultrasonic stirrer at room temperature (25° C.) for 1 h. The mixture was filtered and dried to obtain the second product (polyhydroxy erucic acid-grafted nano-calcium carbonate).

[0112] Example 7

[0113] Acid-soluble nanomaterials were prepared according to the method of Example 1, except that step 2) was replaced by:

[0114] 2) 10 g of p-toluenesulfonyl chloride was dissolved in a 25 wt% sodium hydroxide solution, stirred in an ice bath, and then mixed with 10 g of the second product and reacted for 6 h to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 28 g of the third product was mixed with 10 g of p-phenylenediamine in a 25 wt% sodium hydroxide solution in the presence of a phase transfer catalyst, tetrabutylammonium bromide, and stirred with a magnetic stirrer. The mixture was heated to 100° C. and refluxed for 10 h. The modified nano-calcium carbonate material was obtained by drying, filtering, and rotary evaporation as an acid-soluble nanomaterial.

[0115] Example 8

[0116] Acid-soluble nanomaterials were prepared according to the method of Example 1, except that step 1) was replaced by:

[0117] 1) 16 g of erucic acid and 14 g of formic acid were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 32° C. with stirring. 10 g of hydrogen peroxide was then added dropwise at a uniform rate. The system temperature was adjusted to 55° C. and the reaction was stopped after 5 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid). 90 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added thereto. The mixture was stirred and shaken in an ultrasonic stirrer at room temperature (25° C.) for 1 h. The mixture was filtered and dried to obtain the second product (polyhydroxy erucic acid-grafted nano-calcium carbonate).

[0118] Example 9

[0119] Acid-soluble nanomaterials were prepared according to the method of Example 1, except that step 2) was replaced by:

[0120] 2) 10 g of p-toluenesulfonyl chloride was dissolved in a 25 wt% sodium hydroxide solution, stirred at room temperature (25° C.), and a total of 10 g of the second product was added in small amounts multiple times (about 0.5 g each time), and the reaction was carried out for 6 hours to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 28 g of the third product and 10 g of p-phenylenediamine were mixed in a 25 wt% sodium hydroxide solution in the presence of a phase transfer catalyst, tetrabutylammonium bromide, and magnetic stirring were performed. The mixture was heated to 100° C. and refluxed for 10 hours. The modified nano-calcium carbonate material was obtained as an acid-soluble nanomaterial after drying, filtration, and rotary evaporation.

[0121] Example 10

[0122] Acid-soluble nanomaterials were prepared according to the method of Example 1, except that step 2) was replaced by:

[0123] 2) 10 g of p-toluenesulfonyl chloride was dissolved in a 25 wt% sodium hydroxide solution, stirred in an ice bath, and a total of 10 g of the second product was added in small amounts multiple times (about 0.5 g each time), and the reaction was carried out for 6 hours to obtain a third product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 28 g of the third product was mixed with 10 g of p-phenylenediamine in a 25 wt% sodium hydroxide solution, stirred with a magnetic stirrer, heated to 100° C. and refluxed, reacted for 10 hours, and dried, filtered, and rotary evaporated to obtain a modified nano-calcium carbonate material as an acid-soluble nanomaterial.

[0124] Example 11

[0125] The acid-soluble nanomaterial was prepared according to the method of Example 1, except that the nano-calcium carbonate raw material in step 1) was replaced by a nano-magnesium carbonate raw material.

[0126] Example 12

[0127] The acid-soluble nanomaterial was prepared according to the method of Example 4, except that the nano-calcium carbonate raw material in step 1) was replaced by a nano-magnesium carbonate raw material.

[0128] Example 13

[0129] The acid-soluble nanomaterial was prepared according to the method of Example 5, except that the nano-calcium carbonate raw material in step 1) was replaced by a nano-magnesium carbonate raw material.

[0130] Comparative Example 1

[0131] 16 g of erucic acid and 14 g of formic acid were placed in a four-necked reaction flask equipped with an electric stirrer, a thermometer, a dropping funnel, and a condenser. The reaction flask was placed in a constant temperature water bath and heated to 32° C. with stirring. 10 g of hydrogen peroxide was then added dropwise at a uniform rate. The system temperature was adjusted to a reaction temperature of 68° C. The reaction was stopped after 5 h to obtain reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and the water and solvent were removed by rotary evaporation to obtain the first product (white solid, polyhydroxy erucic acid). 90 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and the first product was added. The mixture was stirred and shaken in an ultrasonic stirrer at 65° C. for 1 h. The second product (polyhydroxy erucic acid-grafted nano-calcium carbonate) was filtered and dried to obtain the second product as an acid-soluble nanomaterial.

[0132] Comparative Example 2

[0133] 90 g of nano-calcium carbonate raw material (powder) was dispersed in 200 mL of anhydrous ethanol, and 16 g of erucic acid was added. The mixture was stirred and reacted at 65° C. in an ultrasonic stirrer for 1 h. The second product (erucic acid-grafted nano-calcium carbonate) was obtained by filtration and drying as an acid-soluble nanomaterial.

[0134] Comparative Example 3

[0135] 16 g of erucic acid, 10 g of hydrogen peroxide, 90 g of nano calcium carbonate raw material (powder), 10 g of p-toluenesulfonyl chloride and 10 g of p-phenylenediamine were physically mixed (forming a suspension with calcium carbonate floating on the surface of other liquid solutions), dried, filtered and rotary evaporated to obtain a modified nano calcium carbonate material as an acid-soluble nano material.

[0136] Comparative Example 4

[0137] 90 g of nano-calcium carbonate raw material (powder) is dispersed in 200 mL of anhydrous ethanol, 10 g of p-toluenesulfonyl chloride is dissolved in 20 mL of pyridine, and the mixture is stirred in an ice bath. A total of 10 g of an ethanol solution of calcium carbonate is added in small amounts multiple times (about 0.5 g each time) and the mixture is reacted for 6 hours to obtain a first product. In the presence of a phase transfer catalyst, tetrabutylammonium bromide, 28 g of the first product and 10 g of p-phenylenediamine are mixed in a 25 wt% sodium hydroxide solution, the mixture is stirred with a magnetic stirrer, the temperature is raised to 100° C., refluxed, and reacted for 10 hours. The modified nano-calcium carbonate material is obtained as an acid-soluble nano-material after drying, filtration, and rotary evaporation.

[0138] Comparative Example 5

[0139] 1) 16 g of octadecanoic acid and 14 g of formic acid were placed in a four-necked reaction flask with an electric stirrer, a thermometer, a dropping funnel, and a condenser, and the reaction flask was placed in a thermostatic water bath. After the temperature was raised to 32° C. under stirring, 10 g of hydrogen peroxide was uniformly added dropwise, the system temperature was adjusted to a reaction temperature of 68° C., and the reaction was stopped after 5 h to obtain a reaction solution I. The reaction solution was transferred to a separatory funnel, the water layer was separated, the oil layer was washed with hot water until neutral, a small amount of acetone was added to dissolve the oil layer, and water and solvent were removed by rotary evaporation to obtain a first product; 90 g of nano calcium carbonate raw material (powder) was dispersed with 200 mL of anhydrous ethanol, and the first product was added thereto. The mixture was stirred and shaken in an ultrasonic stirrer at 65° C. for 1 h, filtered, and dried to obtain the first product (stearic acid-grafted nano calcium carbonate);

[0140] 2) 10 g of p-toluenesulfonyl chloride was dissolved in 20 mL of pyridine and stirred in an ice bath. A total of 10 g of the first product was added in small amounts (about 0.5 g each time) for a total of 6 hours to obtain a second product (alkyl p-toluenesulfonate grafted nano-calcium carbonate); 28 g of the second product was mixed with 10 g of p-phenylenediamine in a 25 wt% sodium hydroxide solution in the presence of a phase transfer catalyst, tetrabutylammonium bromide, and stirred with a magnetic stirrer. The mixture was heated to 100° C. and refluxed for 10 hours. The modified nano-calcium carbonate material was obtained by drying, filtering, and rotary evaporation as an acid-soluble nanomaterial.

[0141] Test Example 1

[0142] The fine powder of the modified nano-calcium carbonate material prepared in Example 1 was pressed into a KBr pellet and analyzed by a Shimadzu IRPrestige-21 Fourier transform infrared spectrometer. The infrared spectrum is shown in Figure 1. Figure 1 shows that the absorption peak of NH in -NH2 of phenylenediamine is at 3420 cm -1 The -CH=CH- bending vibration peaks of the benzene ring are at 1583, 1492, and 1400 cm -1 , indicating that the modified nano-calcium carbonate material contains aniline structure; in addition, 1700cm -1 and 2923cm -1 The stretching vibration peaks of C=O and methylene CH2 in polyhydroxy erucic acid appeared, and the absorption peak of -OH in polyhydroxy erucic acid partially overlapped with the peak of NH; at the same time, the characteristic absorption peaks of CaCO3 mainly appeared at 1700, 1460, 875, and 715 cm -1 It is proved that the modified nano calcium carbonate material finally prepared in Example 1 contains calcium carbonate particles and is grafted with a modifier having a fatty acid carbon chain and an amino group.

[0143] The fine powder of the modified nano-calcium carbonate material prepared in Example 1 was dried by irradiation with an infrared lamp. A small amount was then placed on a conductive tape on a copper tray and lightly pressed with lint-free paper to firmly adhere the sample particles. The powder sample adhering to the side of the copper tray was removed. The sample was then loaded into an apparatus, evacuated, and conductive. The morphology and elemental analysis of the sample powder were performed using a Quanta 250 scanning electron microscope. The morphology and EDS spectrum of the modified calcium carbonate provided by the present invention are shown in FIG2 . Compared with the morphology and EDS spectrum of the calcium carbonate particles shown in FIG3 , a modifier is clearly attached to the particle surface. The EDS spectrum indicates the presence of element N in the modified nano-calcium carbonate. The amino group content can be inferred from the element N content.

[0144] The carbon chain content and amino group content in the acid-soluble nanomaterials prepared in Examples 1 to 13 and Comparative Examples 1 to 5 were determined by combining infrared detection and scanning electron microscopy. The results are shown in Table 2.

[0145] FIG4 shows an optical microscope observation of the aqueous solution of the modified nano-calcium carbonate material obtained in Example 1. The particles of the modified calcium carbonate are formed by the aggregation of many tiny microcrystals and are evenly distributed.

[0146] The optical microscope observation images of the unmodified nano-calcium carbonate particles and their aqueous solutions are shown in Figures 5 and 6. The nano-calcium carbonate particles are uniform in size in the dry powder state; after adding water, they are agglomerated, but the size is inconsistent and the distribution is uneven.

[0147] The hydrodynamic particle size D of the molecular aggregates of the acid-soluble nanomaterials prepared in test examples 1 to 13 and comparative examples 1 to 5 in water is 10 、D20 、D 50 、D 70 and D 90 , with nano calcium carbonate raw material as control, the results are shown in Table 1. The acid solubility of the acid-soluble nanomaterials prepared in Examples 1 to 13 and Comparative Examples 1 to 5 was tested, with calcium carbonate raw material and magnesium carbonate raw material as reference, and the results are shown in Table 2.

[0148] Table 1

[0149] Table 2

[0150] Test Example 2

[0151] Step 1) 0.1 g of polyacrylamide with a weight average molecular weight of 18 million (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is thickener SPR-08) is added to 99.7 g of clean water. The addition speed is controlled during the addition process to prevent the formation of fish eyes, and the speed is adjusted at all times to ensure a vortex state until it is fully dissolved to form a uniform solution; then 0.1 g of oleylamine polyoxyethylene ether (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is drainage agent SPR-201) and 0.1 g of dimethylamine quaternary ammonium salt (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is clay stabilizer SPR-103) are added and stirred evenly.

[0152] Step 2) While maintaining the stirring state, 0.5 g of the acid-soluble nanomaterials prepared in Examples 1 to 13 were added to the solution obtained in Step 1) respectively, and the mixture was stirred to obtain the fracturing fluid.

[0153] Test Example 3

[0154] Step 1) 0.1 g of polyacrylamide with a weight average molecular weight of 18 million (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is thickener SPR-08) is added to 99.7 g of clean water. The addition speed is controlled during the addition process to prevent the formation of fish eyes, and the speed is adjusted at all times to ensure a vortex state until it is fully dissolved to form a uniform solution; then 0.1 g of oleylamine polyoxyethylene ether (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is drainage agent SPR-201) and 0.1 g of dimethylamine quaternary ammonium salt (purchased from Dongying Shipurui Petroleum Engineering Technology Co., Ltd., product model is clay stabilizer SPR-103) are added and stirred evenly.

[0155] Step 2) While maintaining the stirring state, add 2 g of the acid-soluble nanomaterial prepared in Example 1 to the solution obtained in step 1) and stir to obtain the fracturing fluid.

[0156] Test Example 4

[0157] The fracturing fluid was prepared according to the method of Test Example 3, except that the amount of the acid-soluble nanomaterial prepared in Example 1 in step 2) was replaced with 1.5 g.

[0158] Comparative test example 1

[0159] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example 1 was replaced with 0.5 g of the acid-soluble nanomaterial prepared in Comparative Example 1 in step 2).

[0160] Comparative test example 2

[0161] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example 2 was replaced with 0.5 g of the acid-soluble nanomaterial prepared in Comparative Example 2 in step 2).

[0162] Comparative test example 3

[0163] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example 2) was replaced by 0.5 g of the acid-soluble nanomaterial prepared in Comparative Example 3.

[0164] Since the physical mixing in Comparative Example 3 was followed by filtration, drying, and rotary evaporation, only calcium carbonate powder with some erucic acid was obtained, which was still floating when dissolved in solvent water. Therefore, no fracturing fluid system could be obtained, and the filtration loss and retention of the fracturing fluid could not be effectively detected.

[0165] Comparative test example 4

[0166] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example 2) was replaced by 0.5 g of the acid-soluble nanomaterial prepared in Comparative Example 4.

[0167] Comparative test example 5

[0168] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example 2) was replaced by 0.5 g of the acid-soluble nanomaterial prepared in Comparative Example 5.

[0169] Comparative Test Example 6

[0170] The fracturing fluid was prepared according to the method of Test Example 2, except that 0.5 g of the acid-soluble nanomaterial prepared in Example was not added in step 2).

[0171] The fracturing fluid prepared in Comparative Test Example 6 is used as the original fracturing fluid.

[0172] The filtration loss, retention volume, and retention volume reduction rate of each fracturing fluid corresponding to the acid-soluble nanomaterials prepared in Test Examples 2-4 and Comparative Test Examples 1-6 were measured. The results are shown in Table 3.

[0173] Table 3

[0174] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An acid-soluble nanomaterial, characterized in that: The hydrodynamic diameter D of the molecular aggregates of the acid-soluble nanomaterial in water is 10 2-10μm, D 50 8-31μm, D 90 20-90μm.

2. The acid-soluble nanomaterial according to claim 1, wherein The acid-soluble nano material has an acid solubility of 50-80% in a hydrochloric acid solution with a concentration of 15% by weight and dissolved at 90° C. for 1 hour, and an acid solubility of more than 90% when dissolved at 90° C. for 2 hours.

3. The acid-soluble nanomaterial according to claim 1 or 2, wherein The hydrodynamic diameter D of the molecular aggregates of the acid-soluble nanomaterial in water is 20 4-22μm, D 70 12-70μm.

4. The acid-soluble nanomaterial according to any one of claims 1 to 3, wherein The acid-soluble nanomaterial contains carbonate particles and a modifier attached to the surface of the carbonate particles. The carbonate particles contain calcium carbonate particles and / or magnesium carbonate particles. The modifier contains a derivative formed by replacing at least one hydroxyl group in a polyhydroxy fatty acid with an amino-containing substituent.

5. The acid-soluble nanomaterial according to claim 4, wherein The acid-soluble nanomaterial reduces the retention of a fracturing fluid composed of 99.7 wt% solvent + 0.1 wt% thickener + 0.1 wt% drainage aid + 0.1 wt% clay stabilizer and having a retention of 12.5 mg / g by more than 4.5%, preferably more than 25%.

6. The acid-soluble nanomaterial according to claim 4 or 5, wherein The structural formula of the modifier is shown in formula (I) and the carbon chain length is greater than 20. Among them, R I 、R II are each independently hydrogen or C1-C3 alkyl, R III is hydrogen or C1-C20 alkyl, m is an integer of 0-20; R IV and R V One of them is an amino-containing substituent and the other is a hydroxyl group, or both are amino-containing substituents; Preferably, based on the total amount of the acid-soluble nanomaterial, the carbon chain content in the modifier is 5-15% by weight, and the amino group content is 0.05-0.6% by weight.

7. A method for preparing an acid-soluble nanomaterial, characterized in that: The method comprises: subjecting unsaturated fatty monocarboxylic acid to hydroxylation treatment and then subjecting it to contact reaction with a nano-carbonate raw material; subjecting the product of the contact reaction to amination treatment; wherein the nano-carbonate raw material contains a nano-calcium carbonate raw material and / or a nano-magnesium carbonate raw material.

8. The preparation method according to claim 7, characterized in that The structural formula of the unsaturated fatty monocarboxylic acid is shown in formula (II) and the carbon chain length is greater than 20. Among them, R I 、R II are each independently hydrogen or C1-C3 alkyl, R III is hydrogen or C1-C20 alkyl, and m is an integer from 0 to 20; The hydroxylation treatment process includes: mixing the unsaturated fatty monobasic acid with a hydroxylation agent in the presence of a C1-C5 organic acid; Preferably, the hydroxylation agent is a peroxide, more preferably hydrogen peroxide; The weight ratio of the unsaturated fatty monocarboxylic acid, the C1-C5 organic acid and the hydroxylation agent is 1-2:1-2:

1.

9. The preparation method according to claim 8, characterized in that The mixing reaction comprises: mixing the unsaturated fatty monoacid and the C1-C5 organic acid, adding the hydroxylation reagent dropwise at a temperature of 30-35° C., and then heating to 65-70° C. to react for 4-6 hours.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The weight ratio of the hydroxylated unsaturated fatty monocarboxylic acid to the nanocarbonate raw material is 1:4-8; Preferably, the contact reaction conditions include: temperature of 30-70° C. and time of 0.5-1.5 h.

11. The preparation method according to any one of claims 7 to 10, characterized in that: The amination treatment process includes: reacting the product of the contact reaction with an aromatic sulfonyl halide in a first stage, and then reacting the product with a diamine in the presence of a catalyst in a second stage; Preferably, the aromatic sulfonyl halide is benzenesulfonyl chloride, more preferably at least one of p-toluenesulfonyl chloride, p-ethylbenzenesulfonyl chloride, m-toluenesulfonyl chloride and m-ethylbenzenesulfonyl chloride; The diamine is selected from at least one of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 2,2'-bis(trifluoromethyl)diaminobiphenyl and 4,4'-diaminodiphenyl sulfone; The catalyst is a phase transfer catalyst, more preferably tetrabutylammonium bromide and / or benzyltriethylammonium chloride; Preferably, the weight ratio of the aromatic sulfonyl halide to the product of the contact reaction is 1:0.8-1.2, and the weight ratio of the product of the first stage reaction to the diamine is 2.4-3:

1.

12. The preparation method according to claim 11, characterized in that The first stage reaction process includes: adding the product of the contact reaction to the solution containing the aromatic sulfonyl halide in multiple times to react; The conditions of the first stage reaction include: temperature of -5 to 5°C, time of 4-7h; Preferably, the conditions for the second stage reaction include: using a strong alkaline solution with a concentration of 20-30 wt% as the reaction solvent, a temperature of 95-105° C., and a reaction time of 7-12 h.

13. Use of the acid-soluble nanomaterial according to any one of claims 1 to 6 or the acid-soluble nanomaterial prepared according to the method according to any one of claims 7 to 12 in oil production working fluid, preferably as a plugging agent in fracturing fluid.

14. A fracturing fluid containing the acid-soluble nanomaterial according to any one of claims 1 to 6 or the acid-soluble nanomaterial prepared according to the method according to any one of claims 7 to 12.

15. The fracturing fluid according to claim 14, wherein Based on the total amount of the fracturing fluid, the content of the acid-soluble nanomaterial is 0.5-2% by weight.

16. The fracturing fluid according to claim 14 or 15, wherein: The fracturing fluid also contains, based on the total amount of the fracturing fluid, 0.1-1 weight percent of a thickener, 0.1-1 weight percent of a drainage aid, and 0.1-1 weight percent of a clay stabilizer; Preferably, the thickener is an acrylamide homopolymer and / or a copolymer of acrylamide and other monomers, wherein the other monomers are selected from at least one of acryloyloxyethyltrimethylammonium chloride, sodium acrylate, and acrylic acid; further preferably, the copolymer of acrylamide and other monomers is at least one of acrylamide-acryloyloxyethyltrimethylammonium chloride copolymer, acrylamide-sodium acrylate-acrylic acid copolymer, and acrylamide-acryloyloxyethyltrimethylammonium chloride-sodium acrylate-acrylic acid copolymer; Preferably, the drainage aid is polyoxyethylene amine ether and / or polyoxyethylene fatty alcohol ether; Preferably, the polyoxyethylene amine ether is oleylamine polyoxyethylene ether and / or rosin amine polyoxyethylene ether; the polyoxyethylene fatty alcohol ether is at least one of polyoxyethylene lauryl alcohol ether, polyoxyethylene tetradecyl alcohol ether, polyoxyethylene cetyl alcohol ether and polyoxyethylene stearyl alcohol ether; Preferably, the clay stabilizer is dimethylamine quaternary ammonium salt and / or polyquaternium salt.

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