Oil-based suspensions, methods of making and using the same

Abstract

The present application relates to the technical field of suspending agent, and discloses an oil-based suspending emulsion, a preparation method and application thereof, the oil-based suspensing emulsion comprises: active component, nano calcium carbonate dispersion and dispersion aid, wherein the nano calcium carbonate dispersion comprises liquid phase medium and monodisperse nano calcium carbonate dispersed in the liquid phase medium, the monodisperse nano calcium carbonate comprises calcium carbonate particles and surfactant wrapped on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.The oil-based suspending emulsion of the present application directly suspends active component particles by using nano calcium carbonate dispersion, has high stability, and can be stored for a long time without stratification and sedimentation.

Description

Technical Field

[0001] This invention relates to the field of suspension technology, specifically to an oil-based suspension emulsion, its preparation method, and its application. Background Technology

[0002] Oil-based suspension emulsions are a rapidly developing formulation type in recent years, widely used in fracturing fluids and oil displacement agents in oil extraction, pesticide suspensions, and oil-based coatings. The main components of oil-based suspension emulsions include dispersion media, thickeners, activators, active components, and surfactants. The composition of suspension emulsions is complex, requiring careful matching of each component phase. Furthermore, to ensure the stability of the suspension emulsion, the good supporting effect of the thickener is crucial. Commonly used thickeners such as xanthan gum, hydroxymethyl cellulose, and magnesium aluminum silicate cannot spread in oil-based dispersion media to form a three-dimensional network structure, thus their effects are often unsatisfactory. Organobentonite thickeners require organic modification of the bentonite before adding an activator to the dispersion media for full activation, which is costly and requires an additional activation step. Moreover, organobentonite increases the residue content of fracturing fluids, and formation residues can also have a certain impact. Fumed silica is prone to agglomeration, leading to system aggregation and sedimentation, resulting in poor long-term suspension stability and affecting product quality. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned problems in the prior art and to provide an oil-based suspension emulsion, its preparation method, and its application.

[0004] To achieve the above objectives, the first aspect of the present invention provides an oil-based suspension emulsion comprising: an active component, a nano-calcium carbonate dispersion, and a dispersing aid, wherein the nano-calcium carbonate dispersion comprises a liquid phase medium and monodisperse nano-calcium carbonate dispersed in the liquid phase medium, the monodisperse nano-calcium carbonate comprising calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.

[0005] A second aspect of the present invention provides a method for preparing an oil-based suspension emulsion, the method comprising: mixing an active component, a nano-calcium carbonate dispersion, and a dispersing agent, wherein the nano-calcium carbonate dispersion comprises a liquid phase medium and monodisperse nano-calcium carbonate dispersed in the liquid phase medium, the monodisperse nano-calcium carbonate comprising calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.

[0006] The third aspect of this invention provides the application of the above-described oil-based suspension emulsion in oilfield fracturing fluids, oil displacement agents, pesticide suspensions, and coatings.

[0007] Through the above technical solution, the present invention achieves the following beneficial effects:

[0008] (1) The oil-based suspension emulsion of the present invention uses nano-calcium carbonate dispersion to directly suspend active component particles, which has high stability and can be stored for a long time without stratification and sedimentation.

[0009] (2) The oil-based suspension emulsion of the present invention can be used in fracturing fluids and oil displacement agents in oilfield development, pesticide suspensions, and coatings. The oil-based suspension emulsion of the present invention can be used as a thickener and drag reducer in fracturing fluids and as an oil displacement agent, meeting the requirements of rapid dissolution and online mixing. The monodisperse nanoparticles have a good wedge pressure effect, improving oil displacement efficiency. The oil-based suspension emulsion of the present invention can be used in pesticide dispersible oil suspension formulations, improving the stability, flowability, and thermal storage stability of pesticide suspensions. The oil-based suspension emulsion of the present invention, when applied in coatings, prevents hard sedimentation of pigments and fillers and prevents stratification.

[0010] (3) The oil-based suspension emulsion of the present invention has simple composition and high solid content of active components. The preparation method of the oil-based suspension emulsion of the present invention is simple, which simplifies the preparation process of oil-based suspension emulsion and effectively reduces costs. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] The first aspect of the present invention provides an oil-based suspension emulsion comprising: an active component, a nano-calcium carbonate dispersion, and a dispersing aid, wherein the nano-calcium carbonate dispersion comprises a liquid phase medium and monodisperse nano-calcium carbonate dispersed in the liquid phase medium, the monodisperse nano-calcium carbonate comprising calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.

[0013] According to the present invention, preferably, the content of the surfactant is 5-50 wt% (for example, it can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, and any two of the above) based on the total weight of calcium carbonate particles and surfactant, more preferably 15-35 wt%.

[0014] According to the present invention, preferably, the content of calcium carbonate in the nano-calcium carbonate dispersion is 1-60 wt%, based on the total weight of the nano-calcium carbonate dispersion (for example, it can be 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, and any two of the above).

[0015] According to the present invention, preferably, the surfactant is an organic acid, more preferably an aliphatic organic carboxylic acid, an aromatic organic carboxylic acid, an aliphatic organic sulfonic acid, or an aromatic organic sulfonic acid; more preferably, the surfactant includes at least one of butyric acid, succinic acid, valeric acid, glutaric acid, hexanoic acid, adipic acid, heptanoic acid, pimelic acid, octanoic acid, octanoic acid, nonanoic acid, azelaic acid, decanoic acid, sebacic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, linoleic acid, eicosenoic acid, benzoic acid, sorbic acid, ferulic acid, alginic acid, mandelic acid, salicylic acid, dodecyl sulfonic acid, dodecylbenzene sulfonic acid, hexadecylbenzene sulfonic acid, and dinonylnaphthalene sulfonic acid. In the embodiments of the present invention, dodecylbenzene sulfonic acid is used as an example for illustrative purposes, but the present invention is not limited thereto.

[0016] According to the present invention, preferably, the liquid medium includes benzene, toluene, xylene, chlorobenzene, petroleum ether (e.g., petroleum ether (30-60°C), petroleum ether (60-90°C), petroleum ether (90-120°C)), pentane, isopentane, cyclopentane, n-hexane, isohexane, cyclohexane, n-heptane, cycloheptane, cyclopentane, naphtha, diesel, kerosene, gasoline, white oil, peanut oil, castor oil, hydrogenated castor oil, polyoxyethylene castor oil (e.g., polyoxyethylene (35) castor oil), polyoxyethylene hydrogenated castor oil (e.g., polyoxyethylene (40) hydrogenated castor oil, polyoxyethylene (60) hydrogenated castor oil), fish oil, coconut oil, olive oil, palm oil, corn oil, soybean oil, sunflower seed oil, juniper berry oil, stigma oil, dill oil, and perilla. Leaf oil, cinnamon oil, linseed oil, avocado oil, bay leaf oil, glyceryl behenate, peppermint oil, camphor oil, eucalyptus oil, clove basil oil, clove stem and leaf oil, methyl oleate, methylated vegetable oil, epoxidized vegetable oil, paraffin wax, ceresin wax, beeswax, petrolatum, vitex oil, toad oil, burn oil, patchouli oil, rhododendron oil, star anise oil, turpentine oil, tea oil, turmeric oil, turmeric oil, tung oil, linseed oil, heavy oil, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, benzyl alcohol, 1,2-butanediol, 1,3-butanediol, glycerol, neopentyl glycol, pentaerythritol, dipentaerythritol, trimethylolpropane, tetrahydrofuran, dichloromethane, chloroform, tetrachloromethane, ethyl acetate, butyl acetate, acetone. In the embodiments of the present invention, white oil, methyl oleate, and ethyl acetate are used as examples of liquid phase media for illustrative purposes, but the present invention is not limited thereto.

[0017] According to the present invention, preferably, the active component includes at least one selected from anionic polyacrylamide, cationic polyacrylamide, nonionic polyacrylamide, amphoteric polyacrylamide, hydrophobically associating polyacrylamide, acrylamide copolymer, polyacrylamide derivative, guar gum and its derivatives, cellulose and its derivatives, imidacloprid, pymetrozine, nicosulfuron, mesotrione, nicosulfuron, atrazine, nicosulfuron-methyl, penoxsulam, triazole sulfonamide, flupyradifurone, bifenthrin, dinotefuran, bromuconazole, titanium dioxide, talc, and pigments. More preferably, the active component includes at least one selected from 2-acrylamido-2-methylpropanesulfonic acid copolymer with acrylamide, nicosulfuron, titanium dioxide, and talc. In the embodiments of the present invention, the active components are exemplarily described using 2-acrylamido-2-methylpropanesulfonic acid copolymer with acrylamide, nicosulfuron, titanium dioxide, and talc as examples, but the present invention is not limited thereto.

[0018] The present invention does not impose any particular limitation on the specific selection of the 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer, as long as it can provide the active components required for the oil-based suspension emulsion. The 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer can be a commonly used 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer in oil-based suspension emulsions. For example, the viscosity-average molecular weight of the 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer is 10-20 million g / mol, and the content of acrylamide monomer providing structural units in the copolymer is 50-90% by weight.

[0019] In this invention, the particle size of the active component is not particularly limited, and those skilled in the art can select it within a wide range. For example, the particle size of the active component is concentrated below 250 μm, and the proportion of active components with a particle size greater than 250 μm to the total weight of the active component is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the active component is concentrated between 90 and 250 μm, and the proportion of active components with a particle size greater than 250 μm and less than 90 μm to the total weight of the active component is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the active component is concentrated between 125 and 180 μm, and the proportion of active components with a particle size greater than 180 μm and less than 125 μm to the total weight of the active component is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the active component is concentrated between 90-125 μm, and the proportion of active components with a particle size greater than 125 μm and less than 90 μm accounts for less than 20% by weight of the total weight of the active component, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the active component is concentrated between 180-250 μm, and the proportion of active components with a particle size greater than 250 μm and less than 180 μm accounts for less than 20% by weight of the total weight of the active component, preferably less than 10% by weight, and more preferably less than 5% by weight.

[0020] According to the present invention, preferably, the dispersing agent comprises: fatty alcohol polyoxyethylene ether, isomeric tridecyl alcohol polyoxyethylene ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, octylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, sodium fatty alcohol polyoxyethylene ether sulfate, potassium monoalkyl phosphate, alkyl sulfonate, oleic acid diethanolamide, coconut oil diethanolamide, lignin sulfonate, phosphate, polycarboxylate, polyoxyethylene-polyoxypropylene block copolymer, alkyl sulfate, alkyl sulfonate, alkyl naphthalene sulfonate, fatty alcohol polyoxyethylene ether phosphate, castor oil polyoxyethylene ether, oleic acid polyoxyethylene ether and sorbitan polyoxyethylene ether, sodium oleate, decahydrate, and tridecyl alcohol polyoxyethylene ether. The dispersing agent comprises at least one of the following: octadecylamine acetate, aminopropylamine dioleate, polyethylene glycol-type polyol, polyethyleneimine derivative, lecithin, betaine derivative, alkyl sulfate or sulfonate, alkyl aryl sulfonate, polyoxyethylene modified alkyl sulfate or sulfonate, fatty acid amide derivative sulfate or sulfonate, alkylphenol polyoxyethylene ether, alkyl succinate, sorbitol alkylate, and poly(meth)acrylic acid derivative; more preferably, the dispersing agent comprises at least one of isooctyl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyoxyethylene-polyoxypropylene block copolymer, and polycarboxylic acid amine salt.

[0021] According to the present invention, preferably, the oil-based suspension emulsion further includes a stabilizer; more preferably, the stabilizer includes at least one selected from silica gel, molecular sieve, calcium chloride, and carboxymethyl cellulose.

[0022] In this invention, the particle size of the stabilizer is not particularly limited, and those skilled in the art can select it within a wide range. For example, the particle size of the stabilizer is concentrated below 250 μm, and the proportion of stabilizer particles larger than 250 μm in the total weight of the stabilizer is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the stabilizer is concentrated below 150 μm, and the proportion of stabilizer particles larger than 150 μm in the total weight of the stabilizer is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight. Alternatively, the particle size of the stabilizer is concentrated below 120 μm, and the proportion of stabilizer particles larger than 120 μm in the total weight of the stabilizer is less than 20% by weight, preferably less than 10% by weight, and more preferably less than 5% by weight.

[0023] According to the present invention, preferably, based on the total weight of the oil-based suspension emulsion, the content of the active component is 25-70% by weight, the content of the nano-calcium carbonate dispersion is 10-65% by weight, the content of the dispersing aid is 5-20% by weight, and the content of the stabilizer is 1-10% by weight. In the present invention, the content of each component of the oil-based suspension emulsion is calculated based on the amount of feed.

[0024] In this invention, based on the total weight of the oil-based suspension emulsion, the content of the active component can be 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, and any two of the above ranges.

[0025] In this invention, based on the total weight of the oil-based suspension emulsion, the content of the nano-calcium carbonate dispersion can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, or any two of the above.

[0026] In this invention, based on the total weight of the oil-based suspension emulsion, the content of the dispersing agent can be 5% by weight, 10% by weight, 15% by weight, 20% by weight, or any combination of the above.

[0027] In this invention, based on the total weight of the oil-based suspension emulsion, the content of the stabilizer can be 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, 10 wt%, or any two of the above.

[0028] According to the present invention, preferably, the oil-based suspension emulsion does not stratify or deposit after standing at 30-50°C for more than 70 days.

[0029] According to the present invention, preferably, the dissolution time of the oil-based suspension emulsion in brine is less than 10 minutes. The dissolution time is tested by mixing 1 g of the oil-based suspension emulsion with 200 g of brine with a concentration of 20000 mg / L to obtain a mixture, and then testing the viscosity of the mixture at 30°C to obtain a viscosity-time curve. The time at which the viscosity no longer changes is recorded as the dissolution time. More preferably, the dissolution time of the oil-based suspension emulsion in brine is 1-8 minutes.

[0030] This invention also provides a method for preparing monodisperse nano-calcium carbonate, the method comprising:

[0031] (1) In the presence of an organic solvent, a calcium source is subjected to an acid-base neutralization reaction with a surfactant; wherein the calcium source is an alkaline calcium source;

[0032] (2) Mix water with the product obtained from the acid-base neutralization reaction in step (1);

[0033] (3) The mixture obtained in step (2) is subjected to a first carbonization reaction with carbon source a;

[0034] (4) The product obtained from the first carbonization reaction is reacted with carbon source b to carry out a second carbonization reaction;

[0035] Wherein, carbon source a is different from carbon source b.

[0036] According to the present invention, preferably, the organic solvent includes a low-polarity solvent and / or a water-soluble organic solvent.

[0037] According to the present invention, preferably, the low-polarity solvent includes at least one of benzene, toluene, chlorobenzene, petroleum ether, petroleum ether, petroleum ether, pentane, isopentane, cyclopentane, n-hexane, isohexane, cyclohexane, n-heptane, cycloheptane, cyclopentane, naphtha, diesel, kerosene, gasoline, white oil, peanut oil, castor oil, hydrogenated castor oil, fish oil, coconut oil, olive oil, corn oil, soybean oil, sunflower seed oil, juniper berry oil, stigmata oil, dill oil, perilla leaf oil, cinnamon oil, flaxseed oil, avocado oil, bay leaf oil, behenicol, peppermint oil, camphor oil, eucalyptus oil, clove basil oil, clove stem and leaf oil, paraffin wax, ceresin wax, beeswax, vitex oil, toad oil, burn oil, patchouli oil, rhododendron oil, star anise oil, turpentine oil, tea oil, turmeric oil, and heavy oil.

[0038] According to the present invention, preferably, the water-soluble organic solvent includes at least one of a monohydric alcohol (e.g., methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, benzyl alcohol), a dihydric alcohol (e.g., at least one of 1,2-butanediol, 1,3-butanediol, neopentanediol), a trihydric alcohol (e.g., glycerol), a tetrahydric alcohol (e.g., pentaerythritol and / or dipentaerythritol), trimethylolpropane, tetrahydrofuran, dichloromethane, chloroform, and tetrachloromethane.

[0039] According to the present invention, preferably, the calcium source includes an inorganic alkaline calcium source and / or an organic alkaline calcium source; more preferably, it is at least one of the following: seashell, limestone, marble, gypsum, apatite, calcium oxide, calcium hydroxide, calcium formate, calcium acetate (e.g., calcium acetate monohydrate), calcium propionate, calcium pyruvate, calcium stearate, calcium alginate, calcium citrate, DL-calcium tartrate (e.g., DL-calcium tartrate tetrahydrate), L-calcium ascorbate (e.g., L-calcium ascorbate dihydrate), calcium acetylacetone, calcium methacrylate, calcium lactate (e.g., calcium lactate hydrate), calcium neodecanoate, calcium palmitate, calcium gluconate, and calcium malate.

[0040] In this invention, the calcium source can be either a calcium source with water of crystallization or a calcium source without water of crystallization.

[0041] In this invention, in step (1), the calcium source and the surfactant undergo an acid-base neutralization reaction to generate organic calcium, which exists in the organic phase of the reaction system in the form of micelles.

[0042] Preferably, the calcium source includes a substance with water-absorbing properties, such as calcium oxide or gypsum. When the calcium source includes a substance with water-absorbing properties, it can promote the acid-base neutralization reaction.

[0043] According to the present invention, preferably, based on the total weight of the organic solvent, surfactant, and calcium source, the concentration of the calcium source is 0.1-30 wt%, preferably 0.5-30 wt%, the concentration of the surfactant is 0.1-60 wt%, preferably 0.5-50 wt%, and the concentration of the water-soluble organic solvent is 10-80 wt%, preferably 10-75 wt%.

[0044] In this invention, the total weight of the organic solvent, surfactant, and calcium source is used as a basis, and the concentration of the calcium source can be 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or any two of the above.

[0045] In this invention, the total weight of the organic solvent, surfactant, and calcium source is used as a basis. The concentration of the surfactant can be 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 40wt%, 50wt%, 60wt%, or any two of the above.

[0046] In this invention, based on the total weight of the organic solvent, surfactant, and calcium source, the concentration of the water-soluble organic solvent can be 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, or any two of the above.

[0047] According to the present invention, preferably, the conditions for the acid-base neutralization reaction include: a temperature of 20-100℃, preferably 25-95℃, and a time of 5min-15h, preferably 5min-12h.

[0048] According to the present invention, preferably, in step (2), the volume ratio of water to the product obtained by the acid-base neutralization reaction in step (1) is 0.0002-5:1, more preferably 0.001-3:1, and even more preferably 0.001-0.08:1.

[0049] According to the present invention, preferably, in step (2), the mixing conditions include: a temperature of 20-100℃, preferably 25-95℃; and a time of 5min-15h, preferably 5min-12h.

[0050] In this invention, the mixing order in step (2) is not limited. The mixing method between water and the product obtained from the acid-base neutralization reaction in step (1) can be: adding water to the product obtained from the acid-base neutralization reaction in step (1) at a certain flow rate; or adding the product obtained from the acid-base neutralization reaction in step (1) to water at a certain flow rate. When water is added to the product obtained from the acid-base neutralization reaction in step (1) at a certain flow rate, the flow rate of water relative to each mole of calcium source can be 0.1-12000 mL / min. When the product obtained from the acid-base neutralization reaction in step (1) is added to water at a certain flow rate, the flow rate of the product obtained from the acid-base neutralization reaction in step (1) can be 0.1-12000 mL / min.

[0051] According to the present invention, preferably, carbon source a and carbon source b are each independently selected from at least one of water-soluble carbonates, water-soluble bicarbonates, basic magnesium carbonate, magnesium hydroxide carbonate, carbon dioxide, and compressed air; preferably, carbon source a and carbon source b are each independently selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, tetramethylammonium bicarbonate, trimethylammonium bicarbonate, triethylammonium bicarbonate, basic magnesium carbonate, magnesium hydroxide carbonate, carbon dioxide, and compressed air. Carbon source a and carbon source b may also be independently selected from hydrates of the above-mentioned solid carbon sources, such as potassium carbonate 1,5-hydrate.

[0052] In this invention, carbon source a and carbon source b provide carbonate ions for the carbonation process, enabling calcium ions to form calcium carbonate. In the embodiments of this invention, carbon source a is exemplarily illustrated using potassium carbonate and potassium bicarbonate as examples, and carbon source b is exemplarily illustrated using carbon dioxide as an example, but the invention is not limited thereto. Preferably, carbon source a is a solid carbon source, and carbon source b is a gaseous carbon source. Carbon source a can be selected from one or two of the aforementioned solid carbon sources. When carbon source a is two solid carbon sources, the ratio of the two solid carbon sources is not particularly limited and can be selected within a wide range, as long as the molar ratio of carbon source a to calcium source is satisfied. For example, when carbon source a is potassium carbonate and potassium bicarbonate, the weight ratio of potassium carbonate to potassium bicarbonate is not particularly limited and can be selected within a wide range; the weight ratio of potassium carbonate to potassium bicarbonate can be 0.01-1:1.

[0053] In this invention, carbon source a in step (3) can be added to the mixture obtained in step (2) in solid form or introduced into the mixture obtained in step (2) in gas form. The method of adding carbon source a can be reasonably selected according to the form of the carbon source. Similarly, carbon source b in step (4) can be added to the product of the first carbonization reaction in solid form or introduced into the product of the first carbonization reaction in gas form.

[0054] According to the present invention, preferably, when the carbon source a is a solid, the molar ratio of the carbon source a to the calcium source is 0.001-0.3:1, more preferably 0.01-0.2:1. When the amount of carbon source a is limited to the above range, the uniformity of the particle size morphology of nano-calcium carbonate can be further improved.

[0055] According to the present invention, preferably, when the carbon source a is a gas, the flow rate of the carbon source a is 1-2000 mL / min relative to each mole of calcium source, and the aeration time is 0.01-6 h.

[0056] According to the present invention, preferably, when the carbon source b is a solid, the molar ratio of the carbon source b to the calcium source is 0.002-0.7:1.

[0057] According to the present invention, preferably, when the carbon source b is a gas, the flow rate of the carbon source b is 2-5000 mL / min relative to each mole of calcium source, and the aeration time is 0.01-6 h. When the amount of carbon source b is limited to the above range in the present invention, the uniformity of the particle size morphology of nano-calcium carbonate can be further improved.

[0058] In this invention, when the carbon source is gas, the ventilation method can be one or more of the following: normal pressure circulating ventilation, normal pressure non-circulating ventilation, and pressure-holding continuous ventilation; wherein the pressure of the pressure-holding continuous ventilation is 20 kPa-4 MPa.

[0059] According to the present invention, preferably, the conditions for the first carbonization reaction and the second carbonization reaction each independently include: a temperature of 20-210°C, preferably 25-180°C, and a time of 0.01-12h, preferably 0.01-10h.

[0060] According to the present invention, preferably, during the first carbonization reaction and the second carbonization reaction, the reaction system is kept at a certain stirring rate to ensure that the carbon source and the reaction liquid are fully mixed. The stirring rate can be 200-1500 r / min.

[0061] According to the present invention, preferably, the method further includes: (5) performing solid-liquid separation on the product obtained from the second carbonization reaction to obtain a liquid phase containing nano-calcium carbonate, and then removing the solvent from the liquid phase containing nano-calcium carbonate.

[0062] In this invention, the solid-liquid separation method described in step (5) is not particularly limited and can be a solid-liquid separation method commonly used in the art, such as: letting the liquid stand and then pouring it out, centrifugation, filtration (vacuum filtration or pressure filtration, ultrafiltration, nanofiltration) at least one of the following.

[0063] According to the present invention, preferably, step (5) further includes: washing the solid obtained by solid-liquid separation, then mixing the washing liquid with the liquid phase containing nano-calcium carbonate, and then removing the solvent.

[0064] In this invention, the method of solid washing in step (5) is not particularly limited and can be any washing method commonly used in the art, such as soaking, rinsing, filtration (vacuum filtration or pressure filtration, ultrafiltration, nanofiltration), dialysis, centrifugation, or at least one of these. The number of washing cycles can be 1-10. The solvent used for washing can be selected from one or more of the following substances: water, methanol, ethanol, acetone, n-pentane, isopentane, cyclopentane, cyclopentane, n-hexane, isohexane, cyclohexane, n-heptane, cycloheptane, n-octane, isooctane, 3-methyloctane, petroleum ether (30-60℃), petroleum ether (60-90℃), petroleum ether (90-120℃), tetrahydrofuran, benzofuran, benzene, toluene, phenylacetic acid ester, chlorobenzene, dichloromethane, trichloromethane, tetrachloromethane.

[0065] The solid produced in step (5) may be due to a side reaction that occurred during the second carbonization reaction, which generated calcium carbonate coated on the outer layer of the carbon source, and the particles were relatively large.

[0066] The solvent removal method in step (5) is selected from one or more of the following methods: freeze drying, vacuum drying, atmospheric pressure evaporation, rotary vacuum evaporation, forced air drying, infrared irradiation, and spray drying. The number of drying cycles can be 1-10. Under normal circumstances, all solvents in the liquid phase can be removed to obtain nano-calcium carbonate solid; alternatively, some solvents in the liquid phase can be removed (partial solvents usually refer to solvents with a boiling point below 120℃ under atmospheric pressure) to directly obtain monodisperse nano-calcium carbonate dispersion.

[0067] The present invention also provides a method for preparing a monodisperse nano-calcium carbonate dispersion, the method comprising: mixing the above-described monodisperse nano-calcium carbonate with a liquid medium.

[0068] A second aspect of the present invention provides a method for preparing an oil-based suspension emulsion, the method comprising: mixing an active component, a nano-calcium carbonate dispersion, and a dispersing agent, wherein the nano-calcium carbonate dispersion comprises a liquid phase medium and monodisperse nano-calcium carbonate dispersed in the liquid phase medium, the monodisperse nano-calcium carbonate comprising calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.

[0069] According to the method for preparing oil-based suspension emulsions of the present invention, the types, compositions and amounts of the active components, nano-calcium carbonate dispersion, dispersing aids, liquid media, and surfactants are as described in the first aspect, and will not be repeated here.

[0070] According to the method for preparing an oil-based suspension emulsion of the present invention, the method further includes adding a stabilizer during the preparation of the oil-based suspension emulsion, wherein the type and amount of the stabilizer are as described in the first aspect and will not be repeated here.

[0071] According to the method for preparing oil-based suspension emulsions of the present invention, the mixing conditions and order are not particularly limited and can be the mixing conditions and order commonly used in the art.

[0072] The third aspect of this invention provides the application of the above-described oil-based suspension emulsion in oilfield fracturing fluids, oil displacement agents, pesticide suspensions, and coatings.

[0073] The present invention will be described in detail below through embodiments. In the following embodiments,

[0074] The method for calculating the average particle size of nano-calcium carbonate is as follows: 100 calcium carbonate particles are randomly selected from the electron microscope image, and the particle size of the 100 calcium carbonate particles is counted. Then, the average particle size of the 100 calcium carbonate particles is calculated.

[0075] The content of each component in the nano-calcium carbonate dispersion was obtained by thermogravimetric analysis.

[0076] Preparation Example 1-1

[0077] This preparation example illustrates the preparation method of nano-calcium carbonate dispersion (NanoCa-1-1).

[0078] (1) A water-soluble organic solvent (53.4g tetrahydrofuran) and a low-polarity solvent (75.1g cyclopentane) were mixed, and then a calcium source (15.6g calcium oxide) and a surfactant (3g dodecylbenzenesulfonic acid) were added to carry out an acid-base neutralization reaction. The reaction temperature was 35℃ and the reaction time was 4h.

[0079] (2) Water is added dropwise to the product of the acid-base neutralization reaction in step (1). The flow rate of water is 36 mL / min relative to each mole of calcium source. The temperature of the dropwise addition is 95°C. After the dropwise addition is completed, the mixing time at this temperature is 9 h, and the stirring rate is 300 r / min. The volume ratio of water to the product of the acid-base neutralization reaction in step (1) is 0.0625:1.

[0080] (3) Add carbon source a (potassium carbonate and potassium bicarbonate in a weight ratio of 0.1:1) to the product obtained in step (2) to carry out the first carbonization reaction; the conditions for the first carbonization reaction include: temperature of 95℃, time of 2h, and stirring rate of 300r / min; wherein the molar ratio of carbon source a to calcium source is 0.1:1.

[0081] (4) Carbon source b (carbon dioxide gas) is introduced into the product of the first carbonization reaction to carry out the second carbonization reaction; relative to each mole of calcium source, the carbon dioxide gas flow rate is 36 mL / min, the gas introduction method is continuous gas introduction under pressure, the pressure is 500 kPa, and the gas introduction time is 3 h; the conditions for the second carbonization reaction include: the reaction temperature is 95 °C, the reaction time is 10 min, and the stirring rate is 300 r / min.

[0082] (5) The reaction solution obtained from the second carbonization reaction was centrifuged to separate liquid I; the separated solid was then washed three times with water, three times with ethanol, and three times with cyclopentane by centrifugation. Liquid I and the cyclopentane washing liquid contained carbonates.

[0083] (6) After mixing liquid I and the liquid washed with cyclopentane, the solvent with a boiling point below 120°C under normal pressure (water, cyclopentane, tetrahydrofuran and a small amount of residual ethanol in this preparation example) is removed by rotary evaporation and dried once to obtain transparent monodisperse nano calcium carbonate solid.

[0084] (7) The monodisperse nano calcium carbonate solid obtained in step (6) is mixed with 49g of white oil to obtain a monodisperse nano calcium carbonate white oil phase dispersion.

[0085] Transmission electron microscopy (TEM) analysis revealed that the monodisperse nano-calcium carbonate white oil phase dispersion exhibited an average particle size of 4 nm, uniform particle size distribution, and good monodispersity.

[0086] Thermogravimetric analysis (TGA) of the monodisperse nano-calcium carbonate white oil phase dispersion revealed that the weight loss at 30-350℃ (62 wt%) was due to the solvent white oil, the weight loss at 320-500℃ (15.3 wt%) was due to the surfactant dodecylbenzenesulfonic acid, and the weight loss at 520-850℃ (12.2 wt%) was due to carbon dioxide in the calcium carbonate, leaving 15.6 wt% calcium oxide. The calcium carbonate content was calculated based on the carbon dioxide content: the formula is carbon dioxide mass fraction × M. 碳酸钙 / M 二氧化碳 =23.2wt% × 100 / 44 = 35wt%; the calculated calcium carbonate content in the monodisperse nano-calcium carbonate dispersion is 35wt%.

[0087] Preparation Examples 1-2

[0088] The preparation method was carried out according to Example 1-1, except that "49g white oil" was replaced with "155g white oil". The resulting nano-calcium carbonate dispersion is denoted as NanoCa-1-2.

[0089] Thermogravimetric analysis showed that, based on the total weight of the nano-calcium carbonate dispersion, the calcium carbonate content was 15 wt%.

[0090] Preparation Examples 1-3

[0091] The preparation method was carried out according to Example 1-1, except that "49g white oil" was replaced with "39g white oil". The resulting nano-calcium carbonate dispersion is denoted as NanoCa-1-3.

[0092] Thermogravimetric analysis showed that, based on the total weight of the nano-calcium carbonate dispersion, the calcium carbonate content was 40 wt%.

[0093] Preparation Examples 1-4

[0094] This preparation example illustrates the preparation method of nano-calcium carbonate dispersion (NanoCa-1-4).

[0095] (1) A water-soluble organic solvent (53.4g tetrahydrofuran) and a low-polarity solvent (75.1g cyclopentane) were mixed, and then a calcium source (15.6g calcium oxide) and a surfactant (5g dodecylbenzenesulfonic acid) were added to carry out an acid-base neutralization reaction. The reaction temperature was 35℃ and the reaction time was 4h.

[0096] (2) Add water droplets to the product of the acid-base neutralization reaction in step (1). The flow rate of water is 30 mL / min relative to each mole of calcium source. The temperature of the droplets is 95°C. After the droplets are added, the mixing time at this temperature is 9 h and the stirring rate is 300 r / min. The volume ratio of water to the product of the acid-base neutralization reaction in step (1) is 0.0521:1.

[0097] (3) Add carbon source a (potassium carbonate and potassium bicarbonate in a weight ratio of 0.1:1) to the product obtained in step (2) to carry out the first carbonization reaction; the conditions for the first carbonization reaction include: temperature of 95℃, time of 2h, and stirring rate of 300r / min; wherein the molar ratio of carbon source a to calcium source is 0.04:1.

[0098] (4) Carbon source b (carbon dioxide gas) is introduced into the product of the first carbonization reaction to carry out the second carbonization reaction; relative to each mole of calcium source, the carbon dioxide gas flow rate is 36 mL / min, the gas introduction method is continuous gas introduction under pressure, the pressure is 400 kPa, and the gas introduction time is 3 h; the conditions for the second carbonization reaction include: the reaction temperature is 95 °C, the reaction time is 10 min, and the stirring rate is 300 r / min.

[0099] (5) The reaction solution obtained from the second carbonization reaction was centrifuged to separate liquid I; the separated solid was then washed three times with water, three times with ethanol, and three times with cyclopentane by centrifugation. Liquid I and the cyclopentane washing liquid contained carbonates.

[0100] (6) After mixing liquid I and the liquid washed with cyclopentane, the solvent with a boiling point below 120°C under normal pressure (water, cyclopentane, tetrahydrofuran and a small amount of residual ethanol in this preparation example) is removed by rotary evaporation and dried once to obtain transparent monodisperse nano calcium carbonate solid.

[0101] (7) The monodisperse nano calcium carbonate solid obtained in step (6) is mixed with 155g of white oil to obtain a monodisperse nano calcium carbonate white oil phase dispersion.

[0102] Electron microscopy revealed that the average particle size of the nano-calcium carbonate particles was 2.4 nm.

[0103] Thermogravimetric analysis revealed that, based on the total weight of calcium carbonate particles and surfactant, the surfactant content was 15.2 wt%; and based on the total weight of the nano-calcium carbonate dispersion, the calcium carbonate content was 15 wt%.

[0104] Comparative Preparation Example 1-1

[0105] The procedure was carried out according to Preparation Example 1-1, except that "dodecylbenzenesulfonic acid" was replaced with "equal molar amounts of γ-methacryloyloxypropyltrimethoxysilane". The resulting nano-calcium carbonate dispersion is denoted as NanoCa-D1-1. NanoCa-D1-1 is a suspension, indicating that the method of Preparation Example 1 cannot achieve monodispersity of solid particles in a liquid medium. Furthermore, the composition of the solid particles in the suspension was tested, and no calcium carbonate was found, indicating that the method of Preparation Example 1-1 cannot produce calcium carbonate.

[0106] Comparative preparation examples 1-2

[0107] The preparation method of Example 1-1 was followed, except that "calcium oxide" was replaced with "an equimolar amount of calcium chloride". The resulting nano-calcium carbonate dispersion was denoted as NanoCa-D1-2. NanoCa-D1-2 was a suspension, indicating that the method of Comparative Preparation Example 1-2 could not achieve monodispersity of calcium carbonate in a liquid medium.

[0108] Comparative preparation examples 1-3

[0109] The method of Preparation Example 1-1 was followed, except that the second carbonization process in step 4) was not included; and the molar ratio of carbon source a to calcium source in step 3) was 1:1. The resulting nano-calcium carbonate dispersion was denoted as NanoCa-D1-3. In contrast, after the reaction solution obtained from the carbonization reaction in Preparation Example 1-3 was allowed to stand, almost all the solid precipitated to the bottom, and the upper liquid contained almost no solid. This indicates that the solid prepared by the method in Preparation Example 1-3 cannot be dispersed in a liquid solvent.

[0110] Comparative preparation examples 1-4

[0111] The preparation method was carried out according to Example 1-1, except that the first carbonization process in step 3) was not included. The resulting nano-calcium carbonate dispersion was designated NanoCa-D1-4. Electron microscopy revealed that the average particle size of the nano-calcium carbonate particles was 13 nm, and the prepared nano-calcium carbonate particles had uneven morphology, with some large particles forming.

[0112] Comparative preparation examples 1-5

[0113] The preparation method was carried out according to Example 1-1, except that the first carbonation reaction in step 3) was not included. Carbon source a and carbon source b were simultaneously added to the product obtained in step 2), and then a carbonation reaction was carried out under the second carbonation conditions. The resulting nano-calcium carbonate dispersion was designated NanoCa-D1-5. Electron microscopy showed that the average particle size of the nano-calcium carbonate particles was 14 nm, and the prepared calcium carbonate particles had uneven morphology, with some strip-shaped particles formed.

[0114] Comparative preparation examples 1-6

[0115] The preparation method was followed as in Example 1-1, except that "dodecylbenzenesulfonic acid" was replaced with an equimolar amount of "ammonium dodecylbenzenesulfonate". The resulting nano-calcium carbonate dispersion was designated NanoCa-D1-6. Compared to the reaction solution obtained from the second carbonation reaction in Example 1-6, the supernatant after standing contained almost no solids, indicating that the solids prepared by the method in Example 1-6 could not be dispersed in a liquid solvent. Furthermore, XRD analysis of the centrifuged solids showed that the main component of the calcium slag was Ca(OH)2, with no calcium carbonate present. Therefore, replacing the organic acid surfactant with an organic acid salt ultimately fails to yield a nano-calcium carbonate dispersion, or even calcium carbonate at all.

[0116] Example 1-1

[0117] Add 30g of nano-calcium carbonate dispersion (NanoCa-1-1) to a reactor equipped with mechanical stirring. After stirring evenly, add 15g of isooctanol polyoxyethylene ether and 5g of silica gel (based on the total weight of stabilizers, the content of stabilizers with particle size greater than 150μm is less than 5% by weight, and the remainder is stabilizers with particle size range less than 150μm); add 50g of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer (viscosity average molecular weight of 15 million, the content of acrylamide monomer providing structural units in the copolymer is 85% by weight, based on the total weight of active components, the content of active components with particle size greater than 180μm and particle size less than 125μm is less than 10% by weight, and the remainder is active components with particle size range between 125-180μm), and continue stirring to obtain an oil-based suspension emulsion.

[0118] Examples 1-2

[0119] Add 45g of nano-calcium carbonate dispersion (NanoCa-1-2) to a reactor equipped with mechanical stirring. After stirring evenly, add 10g of octylphenol polyoxyethylene ether and 5g of silica gel (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 150μm is less than 10% by weight, and the remainder is stabilizers with a particle size range of less than 150μm). Add 40g of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer (viscosity average molecular weight of 15 million, the content of acrylamide monomer providing structural units in the copolymer is 85% by weight, based on the total weight of active components, the content of active components with a particle size greater than 180μm and a particle size less than 125μm is less than 10% by weight, and the remainder is active components with a particle size range of 125-180μm). Continue stirring to obtain an oil-based suspension emulsion.

[0120] Examples 1-3

[0121] Add 15g of nano-calcium carbonate dispersion (NanoCa-1-3) to a reactor equipped with mechanical stirring. After stirring evenly, continue to add 20g of isooctanol polyoxyethylene ether and 5g of silica gel (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 150μm is less than 5% by weight, and the remainder is stabilizers with a particle size range of less than 150μm); add 60g of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer (viscosity average molecular weight of 15 million, the content of acrylamide monomer providing structural units in the copolymer is 85% by weight, based on the total weight of active components, the content of active components with a particle size greater than 125μm and a particle size less than 96μm is less than 10% by weight, and the remainder is active components with a particle size range of 96-125μm), and continue stirring to obtain an oil-based suspension emulsion.

[0122] Examples 1-4

[0123] Add 62g of nano-calcium carbonate dispersion (NanoCa-1-3) to a reactor equipped with mechanical stirring. After stirring evenly, add 5g of isomeric tridecyl alcohol polyoxyethylene ether and 3g of silica gel (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 150μm is less than 5% by weight, and the remainder is stabilizers with a particle size range of less than 150μm). Add 30g of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer (viscosity average molecular weight of 15 million, the content of acrylamide monomer providing structural units in the copolymer is 85% by weight, based on the total weight of active components, the content of active components with a particle size greater than 250μm and a particle size less than 180μm is less than 10% by weight, and the remainder is active components with a particle size range of 180-250μm). Continue stirring to obtain an oil-based suspension emulsion.

[0124] Examples 1-5

[0125] 10g of nano-calcium carbonate dispersion (NanoCa-1-1) was added to a reactor equipped with mechanical stirring. After stirring evenly, 20g of nonylphenol polyoxyethylene ether and 5g of silica gel were added to the reactor (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 120μm was less than 5% by weight, and the remainder was stabilizers with a particle size range of less than 120μm). 65g of 2-acrylamido-2-methylpropanesulfonic acid and acrylamide copolymer (viscosity-average molecular weight of 15 million, the content of acrylamide monomer providing structural units in the copolymer was 85% by weight, based on the total weight of active components, the content of active components with a particle size greater than 125μm and a particle size less than 96μm was less than 5% by weight, and the remainder was active components with a particle size range of 96-125μm) were added and stirred continuously to obtain an oil-based suspension emulsion.

[0126] Examples 1-6

[0127] The procedure was carried out according to Example 1-1, except that the “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-1-4)”.

[0128] Comparative Example 1-1

[0129] The procedure was carried out according to Examples 1-3, except that “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-D1-1)”.

[0130] Comparative Examples 1-2

[0131] The procedure was carried out according to Examples 1-3, except that the “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-D1-2)”.

[0132] Comparative Examples 1-3

[0133] The procedure was carried out according to Examples 1-3, except that the “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-D1-4)”.

[0134] Comparative Examples 1-4

[0135] The procedure was carried out according to Examples 1-3, except that the “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-D1-5)”.

[0136] Comparative Examples 1-5

[0137] The procedure was carried out according to Examples 1-3, except that “nano-calcium carbonate dispersion (NanoCa-1-1)” was replaced with “an equal weight of white oil”.

[0138] Comparative Examples 1-6

[0139] The method was followed according to Examples 1-3, except that "nano-calcium carbonate dispersion (NanoCa-1-1)" was replaced with "an equal weight of silica dispersion". The silica dispersion was prepared by mixing silica (manufacturer: Evonik Degussa, grade: R972) with white oil to prepare a silica dispersion with a silica content of 40% by weight.

[0140] Test Example 1

[0141] The long-term stability, viscosity, dissolution time, drag reduction rate, and viscosity of the aqueous solution of the oil-based suspension emulsions prepared in the above examples and comparative examples were tested. The test results are shown in Table 1.

[0142] (1) Stability test method for oil-based suspension emulsions: The oil-based suspension emulsion samples were placed at a constant temperature of 30°C, the appearance of the samples was observed, and the time when stratification and sedimentation began to appear was recorded.

[0143] (2) The method for testing the dissolution time of oil-based suspension emulsions is as follows:

[0144] 1) Preparation of saline solution: Add approximately 500 mL of deionized water to a 1000 mL beaker. While stirring at 400 rpm, add 20.0 g of NaCl. Once the added salt has completely dissolved and formed a homogeneous liquid, transfer it to a 1000 mL volumetric flask. Rinse the beaker three times with deionized water, transferring all the rinsing solution into the volumetric flask. Add deionized water to bring the volume to 1000 mL, which is the 20000 mg / L saline solution. The saline solution should be prepared and used immediately.

[0145] 2) Dissolution time determination: Add 200g of the salt solution prepared in step 1) to a beaker. At a rotation speed of 400-500 rpm, add 1g of sample to obtain a 0.5% concentration solution. Test the viscosity of the solution at fixed intervals, such as 1 minute, until the viscosity no longer changes. Obtain the viscosity-time curve. The time corresponding to the point where the viscosity curve becomes stable is the dissolution time. A Brookfield viscometer was used to test the viscosity of the solution at 30℃ and a shear rate of 6 rpm / min.

[0146] (3) Viscosity test method for oil-based suspension emulsion: using a Brookfield viscometer, temperature 30℃, shear rate: 6rpm / min.

[0147] (4) Viscosity determination of oil-based suspension emulsion aqueous solution: Stirred at 500 r / min, add 0.1 g of suspension emulsion sample to 100 g deionized water to obtain solution, and test the viscosity after adding the sample for 2 min. The viscosity of the solution was tested using a Brookfield viscometer at 30℃ and shear rate of 6 rpm / min.

[0148] (5) Test method for drag reduction of oil-based suspension emulsion: The drag reduction rate shall be measured in accordance with the method specified in SY / T 5107-2016 Performance Evaluation Method of Water-based Fracturing Fluid.

[0149] Table 1

[0150]

[0151] As shown in Table 1, the oil-based suspension emulsion prepared by the method not only exhibits high stability but also rapid dissolution and a high drag reduction rate. The oil-based suspension emulsion of this invention can be used as a drag-reducing agent, improving its stability, dissolution rate, and drag reduction rate.

[0152] Preparation Example 2-1

[0153] Nano-calcium carbonate dispersions were prepared according to the method of Preparation Example 1-1, except that "white oil" was replaced with "an equal weight of methyl oleate". The resulting nano-calcium carbonate dispersion is denoted as NanoCa-2-1.

[0154] Comparative Preparation Example 2-1

[0155] The preparation method was carried out according to Example 2-1, except that the first carbonization process in step 3) was not included. The resulting nano-calcium carbonate dispersion is denoted as NanoCa-D2-1.

[0156] Example 2-1

[0157] Add 35g of nano-calcium carbonate dispersion (NanoCa-2-1) to a reactor equipped with mechanical stirring. After stirring evenly, add 10g of polyoxyethylene-polyoxypropylene block copolymer (BASF Pluronic PE), 10g of isooctanol polyoxyethylene ether, and 5g of anhydrous calcium chloride (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 120μm is less than 5% by weight, and the balance is stabilizers with a particle size range of less than 120μm); add 40g of nicotinamide atrazine (based on the total weight of active components, the content of active components with a particle size greater than 125μm and a particle size less than 96μm is less than 5% by weight, and the balance is active components with a particle size range of 96-125μm), and continue stirring to obtain an oil-based suspension emulsion.

[0158] Comparative Example 2-1

[0159] The procedure was carried out according to Example 2-1, except that “nano-calcium carbonate dispersion (NanoCa-2-1)” was replaced with “equal weight of NanoCa-D2-1”.

[0160] Comparative Example 2-2

[0161] The procedure was carried out according to Example 2-1, except that “nano-calcium carbonate dispersion (NanoCa-2-1)” was replaced with “an equal weight of methyl oleate”.

[0162] Comparative Examples 2-3

[0163] The procedure was carried out according to Example 2-1, except that "nano-calcium carbonate dispersion (NanoCa-2-1)" was replaced with "an equal weight of silica dispersion". The silica dispersion was prepared by mixing silica (manufacturer: Evonik Degussa, grade: R972) with methyl oleate to prepare a silica dispersion with a silica content of 35% by weight.

[0164] Test Example 2

[0165] The long-term stability, viscosity, thermal storage stability, pourability and flowability of the oil-based suspension emulsions prepared in the above examples and comparative examples were tested, and the test results are shown in Table 3.

[0166] The test methods for the long-term stability and viscosity of the oil-based suspension emulsion are the same as those in Test Example 1.

[0167] (1) The method for testing thermal storage stability is as follows: Take 50 mL of the oil-based suspension emulsion sample to be tested and place it in a high-airtightness sealed container. Place it in an oven at (54±2)℃ for 14 days. After taking it out, take 5 mL of the suspension sample and centrifuge it at 3000 r / min for 30 min. Observe and record the oil separation and precipitation. Calculate the oil separation rate according to the ratio of the oil separation volume to the total volume.

[0168] (2) The test method for pourability is as follows: it is determined according to the method of GB / T 31737-2015; while testing the pourability, the fluidity of the oil-based suspension emulsion is observed during the pouring process, and the fluidity is rated. The fluidity evaluation includes four levels: excellent, good, average, and poor.

[0169] Table 2

[0170]

[0171]

[0172] As shown in Table 2, the oil-based suspension emulsion prepared by the method exhibits not only high stability but also excellent flowability and minimal residue after pouring; it also demonstrates a low oil separation rate during heat storage, indicating good heat storage stability. The oil-based suspension emulsion of this invention can be used as a pesticide suspension agent, improving the stability, flowability, and heat storage stability of pesticide suspensions.

[0173] Preparation Example 3-1

[0174] Nano-calcium carbonate dispersions were prepared according to the method of Preparation Example 1-1, except that "white oil" was replaced with "an equal weight of ethyl acetate". The resulting nano-calcium carbonate dispersion is denoted as NanoCa-3-1.

[0175] Thermogravimetric analysis showed that, based on the total weight of the nano-calcium carbonate dispersion, the calcium carbonate content in the nano-calcium carbonate dispersion was 35 wt%.

[0176] Comparative Preparation Example 3-1

[0177] The preparation method was carried out according to Example 3-1, except that the first carbonization process in step 3) was not included. The resulting nano-calcium carbonate dispersion is denoted as NanoCa-D3-1.

[0178] Example 3-1

[0179] Add 50g of nano-calcium carbonate dispersion (NanoCa-3-1) to a reactor equipped with mechanical stirring. After stirring evenly, add 10g of polycarboxylate (polycarboxylate amine salt, manufactured by Dow Chemical, brand name TRITON@CF-10), 5g of isooctanol polyoxyethylene ether, and 5g of anhydrous calcium chloride (based on the total weight of stabilizers, the content of stabilizers with a particle size greater than 120μm is less than 5% by weight, and the balance is stabilizers with a particle size range of less than 120μm); add 10g of titanium dioxide and 20g of talc powder and continue stirring to obtain an oil-based suspension emulsion.

[0180] Comparative Example 3-1

[0181] The procedure was carried out according to Example 3-1, except that “nano-calcium carbonate dispersion (NanoCa-3-1)” was replaced with an equal weight of “nano-calcium carbonate dispersion (NanoCa-D3-1)”.

[0182] Comparative Example 3-2

[0183] The procedure was carried out according to Example 3-1, except that “nano-calcium carbonate dispersion (NanoCa-3-1)” was replaced with “an equal weight of ethyl acetate”.

[0184] Comparative Example 3-3

[0185] The procedure was carried out according to Example 3-1, except that "nano-calcium carbonate dispersion (NanoCa-3-1)" was replaced with "an equal weight of silica dispersion". The silica dispersion was prepared by mixing silica (manufacturer: Evonik Degussa, grade: R972) with ethyl acetate to prepare a silica dispersion with a silica content of 35% by weight.

[0186] Test Example 3

[0187] The long-term stability and viscosity of the oil-based suspension emulsions of the above examples and comparative examples were tested. Coatings were prepared using the oil-based suspension emulsions of the above examples and preparation examples, and then the storage sedimentation degree of the coatings was tested. The test results are shown in Table 3.

[0188] The test methods for the long-term stability and viscosity of the oil-based suspension emulsion are the same as those in Test Example 1.

[0189] The coating preparation process is as follows: 49 parts by weight of suspension emulsion sample, 50 parts by weight of film-forming substance (polyacrylic resin), 0.5 parts by weight of leveling agent (polyether modified organosilicon), and 0.5 parts by weight of defoamer (polysiloxane) are mixed evenly to obtain the coating.

[0190] The test method for the degree of storage sedimentation is as follows: determined according to GB / T 6753.3-1986.

[0191] Table 3

[0192]

[0193]

[0194] A storage sedimentation degree of 10 indicates complete suspension; a storage sedimentation degree of 8 indicates a small amount of sedimentation; and a storage sedimentation degree of 6 indicates significant sedimentation.

[0195] As shown in Table 3, the oil-based suspension emulsion of the present invention exhibits high stability. Coatings prepared using the oil-based suspension emulsion of the present invention also demonstrate good stability and can be stored for extended periods without settling.

[0196] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An oil-based suspension emulsion, characterized in that, The oil-based suspension emulsion comprises: an active component, a nano-calcium carbonate dispersion, and a dispersing agent, wherein the nano-calcium carbonate dispersion comprises a liquid medium and monodisperse nano-calcium carbonate dispersed in the liquid medium, the monodisperse nano-calcium carbonate comprising calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles, and the average particle size of the calcium carbonate particles is 1-5 nm.

2. The oil-based suspension emulsion according to claim 1, wherein, Based on the total weight of calcium carbonate particles and surfactant, the surfactant content is 5-50 wt%, preferably 15-35 wt%. And / or, based on the total weight of the nano-calcium carbonate dispersion, the calcium carbonate content in the nano-calcium carbonate dispersion is 1-60 wt%.

3. The oil-based suspension emulsion according to claim 1, wherein, The surfactant is an organic acid, preferably an aliphatic organic carboxylic acid, an aromatic organic carboxylic acid, an aliphatic organic sulfonic acid, or an aromatic organic sulfonic acid; more preferably, the surfactant includes at least one of butyric acid, succinic acid, valeric acid, glutaric acid, hexanoic acid, adipic acid, heptanoic acid, pimelic acid, octanoic acid, octanoic acid, nonanoic acid, azelaic acid, decanoic acid, sebacic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, linoleic acid, eicosenoic acid, benzoic acid, sorbic acid, ferulic acid, alginic acid, mandelic acid, salicylic acid, dodecyl sulfonic acid, dodecylbenzene sulfonic acid, hexadecylbenzene sulfonic acid, and dinonylnaphthalene sulfonic acid.

4. The oil-based suspension emulsion according to claim 1, wherein, The liquid medium includes benzene, toluene, xylene, chlorobenzene, petroleum ether, pentane, isopentane, cyclopentane, n-hexane, isohexane, cyclohexane, n-heptane, cycloheptane, cyclopentane, naphtha, diesel, kerosene, gasoline, white oil, peanut oil, castor oil, hydrogenated castor oil, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, fish oil, coconut oil, olive oil, palm oil, corn oil, soybean oil, sunflower seed oil, juniper berry oil, stigmacandra glabra oil, dill oil, perilla leaf oil, cinnamon oil, flaxseed oil, avocado oil, bay leaf oil, behenicol, peppermint oil, camphor oil, eucalyptus oil, clove basil oil, and clove stems. Leaf oil, methyl oleate, methylated vegetable oil, epoxidized vegetable oil, paraffin wax, ceresin wax, beeswax, petrolatum, vitex oil, toad oil, burn oil, patchouli oil, rhododendron oil, star anise oil, turpentine oil, tea oil, turmeric oil, turmeric oil, tung oil, linseed oil, heavy oil, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, benzyl alcohol, 1,2-butanediol, 1,3-butanediol, glycerol, neopentyl glycol, pentaerythritol, dipentaerythritol, trimethylolpropane, tetrahydrofuran, dichloromethane, chloroform, tetrachloromethane, ethyl acetate, butyl acetate, acetone.

5. The oil-based suspension emulsion according to claim 1, wherein, The active component includes at least one of anionic polyacrylamide, cationic polyacrylamide, nonionic polyacrylamide, amphoteric polyacrylamide, hydrophobically associating polyacrylamide, acrylamide copolymer, polyacrylamide derivative, guar gum and its derivatives, cellulose and its derivatives, imidacloprid, pymetrozine, nicosulfuron, mesotrione, nicosulfuron, atrazine, nicosulfuron-methyl, penoxsulam, triazole sulfonamide, flupyradifurone, bifenthrin, dinotefuran, bromuconazole, titanium dioxide, talc, and pigments; preferably, the active component includes at least one of 2-acrylamido-2-methylpropanesulfonic acid copolymer with acrylamide, nicosulfuron, titanium dioxide, and talc.

6. The oil-based suspension emulsion according to claim 1, wherein, The dispersing agents include: fatty alcohol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, octylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, sodium fatty alcohol polyoxyethylene ether sulfate, potassium monoalkyl phosphate, alkyl sulfonate, oleic acid diethanolamide, coconut oil diethanolamide, lignin sulfonate, phosphate, polycarboxylate, polyoxyethylene-polyoxypropylene block copolymer, alkyl sulfate, alkyl sulfonate, alkyl naphthalene sulfonate, fatty alcohol polyoxyethylene ether phosphate, castor oil polyoxyethylene ether, oleic acid polyoxyethylene ether and sorbitan polyoxyethylene ether, sodium oleate, and octadeceneamine. The dispersant comprises at least one of the following: acetate, aminopropylamine dioleate, polyethylene glycol-type polyol, polyethyleneimine derivative, lecithin, betaine derivative, alkyl sulfate or sulfonate, alkyl aryl sulfonate, polyoxyethylene modified alkyl sulfate or sulfonate, fatty acid amide derivative sulfate or sulfonate, alkylphenol polyoxyethylene ether, alkyl succinate, sorbitol alkylate, and poly(meth)acrylic acid derivative; preferably, the dispersant comprises at least one of the following: isooctyl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, isotridecyl alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, polyoxyethylene-polyoxypropylene block copolymer, and polycarboxylic acid amine salt.

7. The oil-based suspension emulsion according to claim 1, wherein, The oil-based suspension emulsion further includes a stabilizer, preferably, the stabilizer includes at least one of silica gel, molecular sieve, calcium chloride and carboxymethyl cellulose.

8. The oil-based suspension emulsion according to claim 7, wherein, Based on the total weight of the oil-based suspension emulsion, the content of active ingredients is 25-70% by weight, the content of nano-calcium carbonate dispersion is 10-65% by weight, the content of dispersing aid is 5-20% by weight, and the content of stabilizer is 1-10% by weight.

9. The oil-based suspension emulsion according to claim 1, wherein, The oil-based suspension emulsion showed no stratification or sedimentation after standing at 30-50℃ for more than 70 days. And / or, the dissolution time of the oil-based suspension emulsion in brine is less than 10 min. The method for testing the dissolution time is as follows: 1 g of oil-based suspension emulsion is mixed with 200 g of brine with a concentration of 20000 mg / L to obtain a mixture. Then, the viscosity of the mixture is tested at 30 °C to obtain a viscosity-time curve. The time when the viscosity no longer changes is recorded as the dissolution time.

10. A method for preparing an oil-based suspension emulsion, characterized in that, The method includes: mixing an active component, a nano-calcium carbonate dispersion, and a dispersing agent, wherein the nano-calcium carbonate dispersion comprises a liquid medium and monodisperse nano-calcium carbonate dispersed in the liquid medium, and the monodisperse nano-calcium carbonate comprises calcium carbonate particles and a surfactant coated on the surface of the calcium carbonate particles. The 1240905 I97306BHY The average particle size of calcium carbonate particles is 1-5 nm.

11. The application of the oil-based suspension emulsion according to any one of claims 1-9 in oilfield fracturing fluids, oil displacement agents, pesticide suspensions, and coatings.

Images