Anti-ultra-high temperature fluid loss additive, preparation thereof, oil-based drilling fluid and oil field drilling method

Abstract

The application provides an anti-ultra-high-temperature fluid loss additive, a preparation method of the anti-ultra-high-temperature fluid loss additive, an oil-based drilling fluid and an oilfield drilling method. The anti-ultra-high-temperature fluid loss additive is prepared by the following steps: first, reacting magnesium lithium silicate with a silane coupling agent containing an alkenyl group to generate magnesium lithium silicate modified by the silane containing the alkenyl group; and then, performing a copolymerization reaction on the magnesium lithium silicate modified by the silane containing the alkenyl group, isoprene, 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphonium salt, styrene and vinyl imidazole. The anti-ultra-high-temperature fluid loss additive provided by the application has the characteristics of small addition amount, obvious fluid loss reduction effect, anti-ultra-high-temperature, small influence on the rheological property of the oil-based drilling fluid and the like.

Description

Technical Field

[0001] This invention relates to a high-temperature resistant filtration loss reducer and its preparation, oil-based drilling fluid, and oilfield drilling methods, belonging to the field of oilfield drilling fluid technology. Background Technology

[0002] Oil-based drilling fluids are widely used in oilfield drilling processes due to their advantages such as good inhibition, resistance to salt corrosion, and good lubrication. Filtration reducers in oil-based drilling fluids function to seal micro- and nano-pores, reducing fluid loss. Currently, conventional filtration reducers for oil-based drilling fluids are generally natural or oxidized asphalt with different softening points, including small amounts of sulfonated asphalt and modified humic acid-based filtration reducers. In practice, these conventional filtration reducers commonly suffer from problems such as excessive dosage, affecting the rheological properties of the drilling fluid and leading to uncontrolled fluid loss under high and ultra-high temperature conditions.

[0003] Asphalt-based filtration reducers typically only function near their softening point. When the formation temperature is much higher than the asphalt softening point, the asphalt softens, dissolves, and decomposes into molecular-level small particles, losing its sealing and filtration reduction effects. Conversely, when the formation temperature is much lower than the asphalt softening point, asphalt-based filtration reducers often exist in the drilling fluid as large solid particles. This not only significantly reduces their filtration reduction effect but also increases the solid content in the drilling fluid, leading to excessively high drilling fluid viscosity.

[0004] In recent years, with the continuous deepening of exploration and development, the temperature of operating wells has been rising steadily, with many wells reaching temperatures above 205℃ and some even reaching 260℃. Under ultra-high temperature (205-260℃) or extremely high temperature (≥260℃) conditions, modified humic acid-based filtration loss reducers and conventional polymer-based filtration loss reducers have become ineffective. To control filtration loss, large quantities of asphalt-based filtration loss reducers are often added during field drilling operations, frequently exceeding 8% (where the addition is by mass-volume ratio, e.g., to a 100m³ well). 3 Adding 1 ton of treatment agent to the drilling fluid or base mud (at which point the treatment agent dosage is 1%), or even exceeding 10%, still makes it difficult to control the filtration loss. Because asphalt contains oil-soluble gums and asphaltenes, the addition of large amounts of filtration loss reducers leads to excessively high liquid phase viscosity in oil-based drilling fluids, making filtration loss difficult to control and often causing uncontrolled rheological properties. Furthermore, the fluorescence properties of asphalt-based filtration loss reducers can also affect the accuracy of geological logging.

[0005] Furthermore, asphalt easily causes environmental pollution, so how to reduce the use of such filtration loss reducers and improve the temperature resistance of the products has become an important problem for oil fields.

[0006] Therefore, providing a novel high-temperature resistant filtration loss reducer and its preparation, as well as oil-based drilling fluids and oilfield drilling methods, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0007] To address the problems of excessive addition, excessive solid phase, insufficient temperature resistance, easy failure under ultra-high temperature conditions, insufficient filtration reduction effect at low temperatures, and impact on drilling fluid rheology of the most widely used asphalt-based oil-based drilling fluid filtration reducers, one objective of this invention is to provide an ultra-high temperature resistant filtration reducer.

[0008] Another object of the present invention is to provide a method for preparing the above-described ultra-high temperature resistant filtration loss reducing agent.

[0009] Another object of the present invention is to provide an oil-based drilling fluid comprising the above-described ultra-high temperature filtration loss reducer.

[0010] Another object of the present invention is to provide an oilfield drilling method that utilizes the oil-based drilling fluid described above.

[0011] To achieve the above objectives, on the one hand, the present invention provides a high-temperature resistant filtration loss reducer, wherein the high-temperature resistant filtration loss reducer is obtained by first reacting lithium magnesium silicate with an alkenyl-containing silane coupling agent to generate alkenyl-containing silane-modified lithium magnesium silicate, and then subjecting the alkenyl-containing silane-modified lithium magnesium silicate to a copolymerization reaction with isoprene, 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt, styrene and vinylimidazole, and obtaining the high-temperature resistant filtration loss reducer after the reaction is completed.

[0012] As a specific embodiment of the ultra-high temperature resistant filtration loss reducing agent described above in this invention, the ultra-high temperature resistant filtration loss reducing agent is prepared by a method including the following steps:

[0013] S1: Add 19.5-58.6 parts by weight (preferably 39.1 parts by weight) of lithium magnesium silicate to 1000 parts by weight of deionized water to obtain a lithium magnesium silicate dispersion, and then allow the lithium magnesium silicate dispersion to stand and hydrate.

[0014] S2: Under stirring conditions, add 14.8-28.0 parts by weight of an alkenyl-containing silane coupling agent to the solution obtained in S1, then adjust the pH of the system to 4-6, and allow the alkenyl-containing silane coupling agent to fully react with lithium magnesium silicate to obtain an alkenyl-containing silane-modified lithium magnesium silicate aqueous solution, and then dry the aqueous solution and allow it to cool naturally.

[0015] S3: Add the alkenyl-containing silane-modified magnesium lithium silicate obtained in S2 to 500 parts by weight of deionized water and mix them evenly. Then heat the system temperature to 40-50℃ by water bath heating.

[0016] S4: Add 60-80 parts by weight of surfactant, 22.1-44.2 parts by weight of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3, and ensure that the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole are fully dissolved; then react the resulting solution under anaerobic conditions at a constant temperature of 70-75℃ for 30-40 min; after the reaction is completed, add 13.6-20.4 parts by weight of isoprene and 5.2-15.6 parts by weight of styrene to the resulting solution to form a microemulsion; then add 0.5-1.5 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2℃ for 1-3 h. After the reaction is completed, the ultra-high temperature filtration loss reducing agent is obtained.

[0017] As a specific embodiment of the ultra-high temperature resistant filtration loss reducing agent described above in this invention, the preparation method further includes:

[0018] S5: The polymer emulsion obtained in S4 is dried, and the dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is then stirred and allowed to stand to allow the solid phase to fully precipitate.

[0019] S6: After discarding the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, and then dry the turbid liquid until constant weight to obtain the ultra-high temperature filtration loss reducing agent.

[0020] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the alkenyl-containing silane coupling agent includes silane coupling agents containing vinyl, propenyl, or allyl groups.

[0021] Preferably, the alkenyl-containing silane coupling agent includes one or a combination of several of vinyltriethoxysilane (A-151), vinyltrimethoxysilane (A-171), vinyltris(2-methoxyethoxy)silane (A-172), and vinylmethyldimethoxysilane (A-2171). The alkenyl-containing silane coupling agent used in this invention is a commercially available, conventional product, such as a corresponding product purchased from Compton International Chemicals, Inc., USA.

[0022] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the magnesium lithium silicate has a nanosheet structure with a particle size of 30-70 nm and a thickness of 5-15 nm.

[0023] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the vinylimidazole includes one or a combination of 1-vinylimidazole and vinylimidazole having the structure shown in Formula I below;

[0024]

[0025] In Formula I, R2 includes methyl, ethyl, n-propyl, isopropyl, or butyl, etc., X - Including tetrafluoroborate, chloride ions, or bromide ions;

[0026] Preferably, the vinylimidazole comprises one or a combination of several of 1-vinyl-3-ethylimidazolium tetrafluoroborate, 1-vinyl-3-ethylimidazolium bromide, 1-vinylimidazole and 1-vinyl-3-butylimidazolium chloride.

[0027] In a preferred embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the vinylimidazole is 1-vinylimidazole.

[0028] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the molar ratio between lithium magnesium silicate and alkenyl-containing silane coupling agent is 1:1, wherein the molecular weight of lithium magnesium silicate is 361 g / mol.

[0029] In one specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the molar ratio between the alkenyl-containing silane coupling agent, isoprene, styrene, 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole is 2:5:2:1:2.

[0030] The magnesium lithium silicate, styrene, isoprene, vinylimidazole, and 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt used in this invention are all commercially available conventional products. For example, the magnesium lithium silicate was purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., the vinylimidazole can be the corresponding product purchased from Shanghai Chengjie Chemical Co., Ltd., and the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt was purchased from Southwest Petroleum University, with a relative molecular mass of 442 g / mol.

[0031] In one specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the surfactant comprises any combination of two of the following: sodium dodecylbenzenesulfonate (SDBS), sodium dodecyl sulfate (AS), octylphenol polyoxyethylene ether (OP-10), and cashew phenol polyoxyethylene ether (BGF-10). All surfactants used in this invention are commercially available conventional products.

[0032] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the surfactant includes sodium dodecylbenzenesulfonate and octylphenol polyoxyethylene ether in a mass ratio of 3:2, or sodium dodecyl sulfate and octylphenol polyoxyethylene ether in a mass ratio of 7:3, or sodium dodecylbenzenesulfonate and cashew phenol polyoxyethylene ether in a mass ratio of 4:1.

[0033] As a specific embodiment of the ultra-high temperature filtration loss reducing agent described above in this invention, the oil-soluble initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, or azobiscyclohexylformitrile.

[0034] The ultra-high temperature resistant filtration loss reducer provided by this invention needs to have a suitable molecular weight. If its molecular weight is too small, it cannot form multi-point adsorption; if its molecular weight is too large, it can easily lead to drilling fluid conditioning. Considering that the product needs to have high temperature resistance to prevent excessive degradation at high temperatures, it is also necessary to prevent the product from having an excessive impact on the viscosity of the drilling fluid. As a specific embodiment of the ultra-high temperature resistant filtration loss reducer described above, the molecular weight of the ultra-high temperature resistant filtration loss reducer is 10,000-50,000.

[0035] As a specific embodiment of the ultra-high temperature resistant filtration loss reducing agent described above in this invention, the average particle size of the ultra-high temperature resistant filtration loss reducing agent is 50-150 nm, preferably 70-100 nm.

[0036] On the other hand, the present invention also provides a method for preparing the above-mentioned ultra-high temperature resistant filtration loss reducing agent, wherein the preparation method includes:

[0037] First, lithium magnesium silicate is reacted with an alkenyl-containing silane coupling agent to generate alkenyl-containing silane-modified lithium magnesium silicate. Then, the alkenyl-containing silane-modified lithium magnesium silicate is copolymerized with isoprene, 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt, styrene, and vinylimidazole. After the reaction is completed, the ultra-high temperature filtration loss reducing agent is obtained.

[0038] As a specific embodiment of the preparation method described above in this invention, the preparation method specifically includes:

[0039] S1: Add 19.5-58.6 parts by weight of lithium magnesium silicate to 1000 parts by weight of deionized water to obtain a lithium magnesium silicate dispersion, and then allow the lithium magnesium silicate dispersion to stand and hydrate.

[0040] S2: Under stirring conditions, add 14.8-28.0 parts by weight of an alkenyl-containing silane coupling agent to the solution obtained in S1, then adjust the pH of the system to 4-6, and allow the alkenyl-containing silane coupling agent to fully react with lithium magnesium silicate to obtain an alkenyl-containing silane-modified lithium magnesium silicate aqueous solution, and then dry the aqueous solution and allow it to cool naturally.

[0041] S3: Add the alkenyl-containing silane-modified magnesium lithium silicate obtained in S2 to 500 parts by weight of deionized water and mix them evenly. Then heat the system temperature to 40-50℃ by water bath heating.

[0042] S4: Add 60-80 parts by weight of surfactant, 22.1-44.2 parts by weight of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3, and ensure that the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole are fully dissolved; then react the resulting solution under anaerobic conditions at a constant temperature of 70-75℃ for 30-40 min; after the reaction is completed, add 13.6-20.4 parts by weight of isoprene and 5.2-15.6 parts by weight of styrene to the resulting solution to form a microemulsion; then add 0.5-1.5 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2℃ for 1-3 h. After the reaction is completed, the ultra-high temperature filtration loss reducing agent is obtained.

[0043] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes:

[0044] S5: The polymer emulsion obtained in S4 is dried, and the dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is then stirred and allowed to stand to allow the solid phase to fully precipitate.

[0045] S6: After discarding the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, and then dry the turbid liquid until constant weight to obtain the ultra-high temperature filtration loss reducing agent.

[0046] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes:

[0047] In S2, after adjusting the pH of the system to 4-6, an alcohol solvent produced during the hydrolysis of the alkenyl-containing silane coupling agent is added to the system to ensure that the alkenyl-containing silane coupling agent reacts fully with lithium magnesium silicate. The amount of alcohol solvent added is 3-30%, where 3-30% is a mass-volume ratio. For example, if 1000 parts by weight of deionized water is used in S1, then the mass of alcohol solvent added in S2 is 3-30g.

[0048] In one specific embodiment of the preparation method described above, in step S1, 19.5-58.6 parts by weight of lithium magnesium silicate are added to 1000 parts by weight of deionized water, and then stirred at a high speed of 12000±1000 rpm for 20-30 minutes to form a lithium magnesium silicate dispersion. The purpose of the high-speed stirring in step S1 is to fully disperse the lithium magnesium silicate into nano-sized particles. Furthermore, the lithium magnesium silicate needs to be fully hydrated to disperse into nano-sized flake-like particles, exposing the hydroxyl groups on its surface.

[0049] As a specific embodiment of the preparation method described above in this invention, in S2, the alkenyl-containing silane coupling agent needs to be hydrolyzed before it can undergo a coupling reaction with the hydroxyl groups on the surface of lithium magnesium silicate. Taking a vinyl silane coupling agent as an example, the reaction process is shown in Formula II below:

[0050]

[0051] In Formula II, R1 varies depending on the vinylsilane coupling agent, for example, it may be methyl or ethyl.

[0052] For alkenyl-containing silane coupling agents (such as A151) whose own functional groups have a relatively weak effect on the pH of aqueous solutions, the pH of the aqueous solution can be adjusted by adding substances such as acetic acid or ammonia to the system. This makes the alkenyl-containing silane coupling agent easier to hydrolyze. Adding acetic acid to adjust the pH of the aqueous solution to a weakly acidic level (4-6) before hydrolyzing A151 significantly increases the hydrolysis rate. Furthermore, the hydrolysis of alkenyl-containing silane coupling agents produces a certain amount of alcohol solvents such as methanol and ethanol, which are miscible with water. This is determined by the R1 group in the silane structure. If these alcohol solvents are added to the aqueous solution obtained from S1 beforehand, the alkenyl-containing silane coupling agent will be more fully dispersed in the aqueous solution, thus making the hydrolysate more stable. If a small amount of ethanol is added to the aqueous solution obtained from S1 beforehand, the oil droplets of A151 will mix with the aqueous solution more quickly and are less prone to condensation and precipitation. In addition, thorough stirring is required during the hydrolysis of alkenyl-containing silane coupling agents to ensure that the alkenyl-containing silane coupling agents come into more complete contact with water, thereby reducing the condensation reaction that occurs between alkenyl-containing silane coupling agents due to contact. Once the alkenyl-containing silane coupling agents have condensed, they are difficult to hydrolyze.

[0053] As a specific embodiment of the preparation method described above in this invention, in S4, isoprene and styrene are hydrophobic monomers (oil-soluble monomers). According to the principle of similar compatibility, isoprene is easily soluble in oil-soluble substances containing hydrocarbons, while styrene containing benzene rings is easily soluble in oil-soluble substances containing aromatic rings. By introducing the above two monomers, the dispersion performance of the synthesized product in oil can be enhanced.

[0054] Furthermore, to prevent high-temperature degradation, this invention uses isoprene containing C=C unsaturated double bonds for polymerization, resulting in a polymer with C=C single bonds. Since the bond energy of C=C is very high, it is less prone to high-temperature degradation, thus improving the temperature resistance of the resulting polymer. Simultaneously, after polymerization, isoprene forms double bonds in the polymer's side chains, further ensuring the hydrophobicity of the product.

[0055] This invention also introduces two hydrophilic monomers: 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole. These are polymerizable ionic liquid monomers. Besides their inherent good temperature resistance, both 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and styrene monomer possess benzene ring structures. Their combined use increases the rigidity of the polymer molecular chain, thereby improving the product's temperature resistance. Furthermore, the five-membered ring structure of vinylimidazole also provides a certain degree of rigidity, further enhancing the product's temperature resistance. Simultaneously, the presence of the tetrabutyl quaternary phosphine salt group enhances the dipole moment of the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt monomer, giving the monomer a certain degree of polarity, thus improving the adsorption capacity of the polymer product. The introduction of the imidazole structure further enhances the adsorption effect of the resulting polymer product.

[0056] In this invention, the reaction process of alkenyl-containing silane-modified magnesium lithium silicate (taking vinylsilane-modified magnesium lithium silicate as an example) with isoprene, styrene, 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole (taking vinylimidazole having the structure shown in Formula I above as an example) is shown in Formula III below:

[0057]

[0058] In Formula III, the molar ratio of x, y, z, m and n is 1-3:1-3:1-3:4-6:1-1.5, preferably 2:2:2:5:1.

[0059] As a specific embodiment of the preparation method described above in this invention, in S5 and S6, the drying can be carried out in a spray dryer. Spray drying is one of the commonly used drying methods for emulsion products and turbid liquid products. The temperature and time of spray drying can be reasonably adjusted according to the actual needs of on-site operations, as long as the drying purpose can be achieved.

[0060] In S5, the dried product is then added to an aqueous solution containing ethanol to adjust it into a turbid liquid. This is to facilitate the precipitation of the polymer complex. Simultaneously, allowing the turbid liquid to settle allows water-soluble surfactants to enter the upper aqueous phase and be washed away. This reduces the negative impact of the surfactants used in the synthesis reaction on the oil-based drilling fluid when it is subsequently added to the oil-based drilling fluid as a high-temperature resistant filtration reducer.

[0061] In another aspect, the present invention also provides an oil-based drilling fluid, wherein the oil-based drilling fluid contains the above-mentioned ultra-high temperature resistant filtration loss reducer.

[0062] As a specific embodiment of the oil-based drilling fluid described above in this invention, the amount of the ultra-high temperature resistant filtration loss reducer added is 1-3%, where 1-3% is a mass-volume ratio. For example, if 1g of ultra-high temperature resistant filtration loss reducer is added to 100mL of drilling fluid or base slurry, the amount of ultra-high temperature resistant filtration loss reducer added is 1%.

[0063] In another aspect, the present invention also provides an oilfield drilling method, wherein the oilfield drilling method is implemented using the oil-based drilling fluid described above.

[0064] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0065] This invention synthesizes a high-temperature resistant, plugging-type filtration reducer for oil-based drilling fluids through organic-inorganic composite modification. In preparing this high-temperature resistant filtration reducer, firstly, a monomer with silane coupling effect, namely an alkenyl-containing silane coupling agent, is reacted with lithium magnesium silicate to modify nano-sized lithium magnesium silicate particles into polymerizable nanoparticles. Then, through microemulsion polymerization, oil-soluble monomers, namely styrene and isoprene, and hydrophilic monomers, namely 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole, are polymerized with alkenyl-containing active lithium magnesium silicate, ultimately forming an organic-inorganic polymer composite, namely the organic-inorganic nanocomposite filtration reducer. This invention solves the problem of lipophilic dispersion of lithium magnesium silicate by hydrophobic modification, giving hydrophilic lithium magnesium silicate a certain degree of hydrophobicity. Meanwhile, the ultra-high temperature resistant filtration loss reducer obtained by this invention is an inorganic-organic polymer composite. While the inorganic part plays a blocking role, the organic polymer chain can play a certain "bridging" role, further enhancing the blocking and filtration loss reduction effects of the product.

[0066] This invention synthesizes the ultra-high temperature filtration loss reducer through microemulsion polymerization, effectively controlling the particle size of the product and ensuring that the synthesized composite particles remain at the nanoscale. This solves the problems of agglomeration and difficulty in controlling particle size that easily occur in the conventional modification process of inorganic-organic nanocomposites.

[0067] This invention effectively controls the polymer chain length by controlling the amount of initiator added, resulting in a polymer chain with good filtration loss reduction and self-dispersibility. Furthermore, the synthesized product has excellent plugging and filtration loss reduction properties without affecting the rheological properties of the drilling fluid.

[0068] This invention significantly improves the temperature resistance of the product by using monomers containing rigid and temperature-resistant groups and adjusting the ratio of each monomer, achieving a temperature resistance of up to 260°C.

[0069] This invention optimizes the ratio of hydrophilic and hydrophobic monomers to hydrophilic lithium magnesium silicate, thereby producing a product with amphiphilic properties that can assist in emulsification in oil-based drilling fluids. This further improves the emulsification stability of oil-based drilling fluids, increases demulsification voltage, and reduces filtration loss.

[0070] This invention utilizes two monomers, 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole, to not only greatly enhance the product's temperature resistance but also improve its adsorption capacity on particles such as clay and barite, thereby significantly improving the product's temperature resistance and filtration loss reduction capabilities.

[0071] In summary, the ultra-high temperature resistant filtration loss reducer provided by this invention not only requires a small amount to achieve a significant filtration loss reduction effect, but also has the characteristics of being resistant to ultra-high temperatures and having minimal impact on the rheological properties of oil-based drilling fluids. Detailed Implementation

[0072] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0073] The "range" disclosed in this invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this way are composable, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is also expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if the listed minimum range values ​​are 1 and 2, and the listed maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0074] In this invention, unless otherwise specified, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this invention, and "0-5" is simply a shortened representation of these numerical combinations.

[0075] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in this invention can be combined with each other to form new technical solutions.

[0076] In this invention, unless otherwise specified, all technical features and preferred features mentioned in this invention can be combined with each other to form new technical solutions.

[0077] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the appendices and embodiments. The embodiments described below are some, but not all, embodiments of this invention, and are only used to illustrate the invention, and should not be considered as limiting the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0078] Example 1

[0079] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0080] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0081] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0082] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0083] S4: Add 80g of the surfactant composition (64.0g of SDBS and 16.0g of BGF-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Then add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Then add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0084] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0085] S6: Discard the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0086] Example 2

[0087] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0088] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0089] S2: Under stirring conditions, 19.0 g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) was first added to the lithium magnesium silicate dispersion prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 4.6 g of ethanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow vinyltriethoxysilane to react fully with lithium magnesium silicate, thereby obtaining a vinyltriethoxysilane-modified lithium magnesium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0090] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0091] S4: 80g of a surfactant composition (48.0g of SDBS and 32.0g of OP-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole were added sequentially to a glass reactor. A certain amount of deionized water was then added and stirred to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, the system was heated to 70℃ and kept at a constant temperature for 30min. After the reaction was completed, the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) was added dropwise to the system, and stirring was continued for 30min to form a microemulsion. Then, 1.0g of azobisisobutyronitrile initiator was added to the microemulsion, and the system was heated to 75℃ and reacted for 1h.

[0092] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0093] S6: Discard the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0094] Example 3

[0095] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0096] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0097] S2: Under stirring conditions, 19.0 g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate dispersion prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 4.6 g of ethanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltriethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0098] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0099] S4: 80g of a surfactant composition (48.0g of SDBS and 32.0g of OP-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole were added sequentially to a glass reactor. A certain amount of deionized water was then added and stirred to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, the system was heated to 70℃ and kept at a constant temperature for 30min. After the reaction was completed, the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) was added dropwise to the system, and stirring was continued for 30min to form a microemulsion. 0.5g of azobisisobutyronitrile initiator was then added to the microemulsion, and the system was heated to 75℃ and reacted for 1h.

[0100] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0101] S6: Discard the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 50,000 and an average particle size of 140 nm.

[0102] Example 4

[0103] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0104] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0105] S2: Under stirring conditions, 19.0 g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate dispersion prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 4.6 g of ethanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltriethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0106] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0107] S4: 80g of a surfactant composition (48.0g of SDBS and 32.0g of OP-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole were added sequentially to a glass reactor. A certain amount of deionized water was then added and stirred to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, the system was heated to 70℃ and kept at a constant temperature for 30min. After the reaction was completed, the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) was added dropwise to the system, and stirring was continued for 30min to form a microemulsion. Then, 1.5g of azobisisobutyronitrile initiator was added to the microemulsion, and the system was heated to 75℃ and reacted for 1h.

[0108] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0109] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 10,000 and an average particle size of 60 nm.

[0110] Example 5

[0111] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0112] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0113] S2: Under stirring conditions, 22.2 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. The solution was then stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, resulting in a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105°C and then naturally cooled to room temperature.

[0114] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0115] S4: Add 80g of surfactant composition (48.0g of SDBS and 32.0g of OP-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0116] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0117] S6: Discard the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0118] Comparative Example 1

[0119] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0120] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0121] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0122] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0123] S4: Add 80g of surfactant composition (including 64.0g of SDBS and 16.0g of BGF-10) to a glass reactor, purge with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (including 17.0g of isoprene and 10.4g of styrene) dropwise to the system, continue stirring for 30min to form a microemulsion, then add 1.0g of azobisisobutyronitrile initiator to the microemulsion, and heat the system to 75℃ for 1h.

[0124] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0125] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0126] Comparative Example 2

[0127] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0128] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0129] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0130] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0131] S4: Add 40g of surfactant composition (32.0g of SDBS and 8.0g of BGF-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form an emulsion. Add 1.0g of azobisisobutyronitrile initiator to the emulsion and heat the system to 75℃ for 1h.

[0132] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0133] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 40,000 and an average particle size of 220 nm.

[0134] Comparative Example 3

[0135] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0136] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0137] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0138] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0139] S4: Add 80g of surfactant composition (64.0g of SDBS and 16.0g of BGF-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (6.8g of isoprene and 26g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0140] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0141] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer for drying, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 12000 and an average particle size of 80nm.

[0142] Comparative Example 4

[0143] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0144] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0145] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0146] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0147] S4: 80g of a surfactant composition (64.0g of SDBS and 16.0g of BGF-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole were added sequentially to a glass reactor. A certain amount of deionized water was then added and stirred to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole. After purging with nitrogen for 30min, the system was heated to 70℃ and kept at a constant temperature for 30min. After the reaction was completed, the remaining lipophilic monomer mixture (12.9g of methyl acrylate and 10.4g of styrene) was added dropwise to the system. Stirring was continued for 30min to form a microemulsion. Then, 1.0g of azobisisobutyronitrile initiator was added to the microemulsion, and the system was heated to 75℃ and reacted for 1h.

[0148] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0149] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 20,000 and an average particle size of 105 nm.

[0150] Comparative Example 5

[0151] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0152] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0153] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0154] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0155] S4: Add 80g of surfactant composition (64.0g of SDBS and 16.0g of BGF-10), 10.3g of sodium styrene sulfonate and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0156] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0157] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0158] Comparative Example 6

[0159] This comparative example provides a filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0160] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0161] S2: Under stirring conditions, 14.8 g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) was first added to the magnesium lithium silicate solution prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 3.2 g of methanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow the vinyltrimethoxysilane to react fully with the magnesium lithium silicate, thereby obtaining a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0162] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0163] S4: Add 80g of surfactant composition (64.0g of SDBS and 16.0g of BGF-10) and 22.1g of 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt to a glass reactor in sequence. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0164] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0165] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain the filtration loss reducer with a molecular weight of 20,000 and an average particle size of 100 nm.

[0166] Comparative Example 7

[0167] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0168] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0169] S2: Under stirring conditions, 19.0 g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) was first added to the lithium magnesium silicate dispersion prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 4.6 g of ethanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow vinyltriethoxysilane to react fully with lithium magnesium silicate, thereby obtaining a vinyltriethoxysilane-modified lithium magnesium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0170] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0171] S4: 80g of a surfactant composition (48.0g of SDBS and 32.0g of OP-10), 22.1g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 9.4g of 1-vinylimidazole were added sequentially to a glass reactor. A certain amount of deionized water was then added and stirred to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, the system was heated to 70℃ and kept at a constant temperature for 30min. After the reaction was completed, the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) was added dropwise to the system, and stirring was continued for 30min to form a microemulsion. 0.1g of azobisisobutyronitrile initiator was then added to the microemulsion, and the system was heated to 75℃ and reacted for 1h.

[0172] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0173] S6: Discard the supernatant obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 120,000 and an average particle size of 280 nm.

[0174] Comparative Example 8

[0175] This embodiment provides a high-temperature resistant filtration loss reducer, which is prepared by a method including the following specific steps:

[0176] S1: Add 36.1g of lithium magnesium silicate (purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd., which has a nanosheet structure with a particle size of 30-70nm and a thickness of 5-15nm) to 1000mL of deionized water, stir at a high speed of 12000±1000rpm for 30min, and after forming a lithium magnesium silicate dispersion, let it stand for 1h to hydrate.

[0177] S2: Under stirring conditions, 19.0 g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) was first added to the lithium magnesium silicate dispersion prepared in S1. Then, acetic acid was added to adjust the pH of the solution to 4-6. After that, 4.6 g of ethanol was added and the mixture was stirred at 3000±100 rpm for 1 h to allow vinyltriethoxysilane to react fully with lithium magnesium silicate, thereby obtaining a vinyltriethoxysilane-modified lithium magnesium silicate aqueous solution. The aqueous solution was dried at 105 °C and then naturally cooled to room temperature.

[0178] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate obtained in S2 to 500 mL of deionized water, stir at high speed for 30 min, then transfer to a 2 L glass reactor, turn on the water bath heating device, and adjust the temperature to 45 °C.

[0179] S4: Add 80g of surfactant composition (48.0g of SDBS and 32.0g of OP-10), 44.2g of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 18.8g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to dissolve and mix the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and 1-vinylimidazole evenly. After purging with nitrogen for 30min, heat the system to 70℃ and maintain the temperature for 30min. After the reaction is complete, add the remaining lipophilic monomer mixture (17.0g of isoprene and 10.4g of styrene) dropwise to the system and continue stirring for 30min to form a microemulsion. Add 1.0g of azobisisobutyronitrile initiator to the microemulsion and heat the system to 75℃ for 1h.

[0180] S5: The polymer emulsion obtained in S4 is placed in a spray dryer for drying. The dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is stirred at low speed for 1 hour and allowed to stand for 2 hours until the solid phase is fully precipitated.

[0181] S6: Discard the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, place the turbid liquid in a spray dryer to dry, and after drying to constant weight, obtain an ultra-high temperature resistant filtration loss reducer with a molecular weight of 20,000 and an average particle size of 106 nm.

[0182] Test Example 1

[0183] This test example tests the filtration loss reduction performance and temperature resistance of the ultra-high temperature resistant filtration loss reducing agents provided in Examples 1-5 and Comparative Examples 1-8, respectively. The tests include the following specific steps:

[0184] 1) Sample slurry preparation:

[0185] Preparation of the base slurry: Take 240 mL of No. 3 white oil, add 21.0 g of oil-based drilling fluid emulsifier modified rosin acid salt (CQ-NT) and 9.0 g of oil-based drilling fluid co-emulsifier low molecular weight polyamide (CQ-GC), stir at 11000 r / min for 20 min, then add oil-based drilling fluid viscosity stabilizer modified silicate (CQNZC-Ⅱ) and stir at high speed for 10 min. Under high-speed stirring conditions, slowly add 60 mL of 25.0% calcium chloride brine, stir at high speed for 20 min after the addition is complete, then add 12.0 g of calcium oxide and stir at high speed for 30 min. Then add 3.0 g of oil-based drilling fluid plugging agent YX-40 and 3.0 g of oil-based drilling fluid plugging agent YX-120, stir at high speed for 10 min after the addition is complete, then add 388 g of barite and stir at high speed for 30 min to obtain the base slurry.

[0186] Among them, No. 3 white oil was taken from the Changning block in Sichuan Province.

[0187] The oil-based drilling fluid emulsifier-modified rosin salt (CQ-NT) was obtained from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0188] The low molecular weight polyamide (CQ-GC) used as an emulsifier for oil-based drilling fluids was obtained from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0189] The oil-based drilling fluid viscosity enhancer and stabilizer modified silicate (CQNZC-Ⅱ) was obtained from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0190] The calcium chloride used was of analytical grade;

[0191] YX-40, an oil-based drilling fluid plugging agent, was sourced from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0192] The oil-based drilling fluid plugging agent YX-120 was sourced from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0193] The barite was obtained from the Sichuan-Chongqing Drilling and Production Engineering Technology Research Institute.

[0194] Preparation of sample slurry: Add the target mass of filtration loss reducer to 300 mL of base slurry according to the design ratio shown in Table 1 below, and stir at high speed for 10 min to obtain the sample slurry.

[0195] The filter loss reducing agents are the ultra-high temperature resistant filter loss reducing agents provided in Examples 1-5, the filter loss reducing agents provided in Comparative Examples 1-8, and commercially available filter loss reducing agents. The commercially available filter loss reducing agents include commercially available filter loss reducing agent No. 1, commercially available filter loss reducing agent No. 2, commercially available filter loss reducing agent No. 3, and commercially available ordinary oxidized asphalt.

[0196] Among them, commercially available filtration loss reducer No. 1 is an asphalt-based filtration loss reducer produced by a manufacturer in Chengdu; commercially available filtration loss reducer No. 2 is a humic acid-modified filtration loss reducer produced by a manufacturer in Hubei; commercially available filtration loss reducer No. 3 is a polymer-based filtration loss reducer produced by a manufacturer in Shandong; and the parameters of commercially available ordinary oxidized asphalt are as follows: asphalt softening point is 180-220℃, toluene insoluble content is 25-35% by weight, quinoline insoluble content is 10-12% by weight, coking value is 30-50%, and volatile matter is 45%-55%.

[0197] 2) Test methods and experimental results:

[0198] The sample slurries prepared above were placed in a roller furnace and rolled for 16 hours at (260±2)℃. After cooling, the tank was opened, and the water and oil separation of the sample slurry in the aging tank were observed. The upper layer of precipitate was poured out, and the volume of the precipitate was measured with a graduated cylinder. The upper layer of precipitate and the lower layer of mud were poured back into the high-speed stirring cup and stirred at high speed for 20 minutes. Then it was poured into a constant temperature cup, and the AV, PV, YP, and ES values ​​of the sample slurry at (50±1)℃ and the HTHP filtration loss value at 220℃ were determined according to the provisions of GB / T16783.2-2012. The test results are shown in Table 1 below.

[0199] Table 1. Comparison of performance of different filtration reducers after aging at 260℃ in white oil-based drilling fluid.

[0200]

[0201]

[0202] Note: The asphalt in Table 1 is commercially available ordinary oxidized asphalt.

[0203] The percentages in Table 1 are mass-volume ratios, calculated based on the total volume of the base slurry. For example, if 24g of asphalt is added to 300mL of base slurry, the amount of asphalt added is 8%.

[0204] As can be seen from Table 1 above, the ultra-high temperature resistant filtration loss reducer provided in the embodiments of the present invention has a temperature resistance of up to 260℃ in oil-based drilling fluids. Furthermore, this ultra-high temperature resistant filtration loss reducer product has minimal impact on the rheological properties of oil-based drilling fluids, outstanding filtration loss reduction effect, good compatibility with filtration loss reducers for oil-based drilling fluids such as asphalt, humic acid, and conventional polymers, strong synergistic effect, and can also significantly improve the demulsification voltage of oil-based drilling fluids.

[0205] Comparing the data of Examples 1 and 2 shown in Table 1, and combining Examples 1 and 2, it can be seen that for alkenyl-containing silane coupling agents, whether vinylmethoxysilane or vinylethoxysilane is used, the filtration loss reduction effect of the prepared ultra-high temperature resistant filtration loss reduction agent is good and the difference is very small. This indicates that the type of alkenyl-containing silane coupling agent has little impact on the performance of the prepared ultra-high temperature resistant filtration loss reduction agent product.

[0206] Comparing the data from Examples 2-4 and Comparative Example 7 in Table 1, it can be seen that the amount of initiator added significantly affects the filtration loss reduction effect of the ultra-high temperature filtration loss reducing agent product. A smaller initiator dosage results in longer polymer chains in the product, leading to a more pronounced thickening effect. Within a certain range, the increased molecular weight helps reduce filtration loss. Conversely, a larger initiator dosage results in more active sites, leading to shorter polymer chains and a reduced thickening effect. At the current dosage, compared to the ultra-high temperature filtration loss reducing agent provided in Example 3, the filtration loss of the ultra-high temperature filtration loss reducing agents provided in Examples 2 and 4 is slightly higher, but the increase is not significant. Comparing Examples 2-4 and Comparative Example 7 shows that when the amount of initiator used is significantly reduced, the molecular weight of the product increases, and the particle size becomes larger. The result is a significant thickening effect in the filtration loss reducing agent product, but the filtration loss actually increases. This is likely due to the larger particle size leading to an unreasonable particle size distribution in the system.

[0207] Comparing the data from Example 1 and Comparative Example 1 in Table 1, and combining them, it can be seen that the filtration loss of the filtration loss reducer prepared without using hydrophilic monomers is increased, and the product's effect on improving the emulsion stability of oil-based drilling fluids is significantly reduced. Analysis suggests that, compared to Example 1, the filtration loss reducer prepared using only hydrophobic monomers in Comparative Example 1 has significantly reduced hydrophilicity. In this case, the filtration loss reducer is more dispersed in the oil phase in the oil-based drilling fluid, resulting in reduced adsorption at the emulsion interface, thus decreasing its stabilizing effect on the emulsion as a solid particle. Conversely, the presence of appropriate amounts of hydrophilic monomers, namely 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt and 1-vinylimidazole, allows the product to adsorb at the oil-water interface, enhancing its stabilizing effect on the emulsion. Furthermore, the styrene monomer used has a benzene ring, increasing the rigidity of the resulting polymer chain, thereby improving the product's temperature resistance.

[0208] Comparing the data from Example 1 and Comparative Example 2 shown in Table 1, and combining them with the data from Example 1 and Comparative Example 2, it can be seen that when the amount of emulsifier added is insufficient, the filtration loss of the resulting filtration loss reducer increases significantly. Furthermore, during the actual reaction, the semi-transparent or transparent microemulsion did not appear. This may be because insufficient emulsifier prevents the formation of a microemulsion system, resulting only in a regular emulsion system. The droplet size in a regular emulsion system is larger than that in a microemulsion, leading to a correspondingly larger particle size in the resulting product. This negates the nano-blocking effect, and the polymer chains also become longer, affecting the product's viscosity.

[0209] Comparing the data from Example 1 and Comparative Example 3 shown in Table 1, and combining the data from both examples, it can be seen that compared to Example 1, the significant change in the proportion of lipophilic monomers used in Comparative Example 3 resulted in a decrease in the filtration loss reduction and plugging ability of the product. Analysis suggests that while the decrease in isoprene and the significant increase in styrene in Comparative Example 3 improved the product's rigidity and temperature resistance, the excessive addition of benzene-containing styrene increased steric hindrance in the reaction system, hindering the polymerization reaction. Consequently, fewer monomers actually participated in the reaction to form polymer chains than theoretically required, resulting in a smaller molecular weight and a weaker filtration loss reduction effect at high temperatures.

[0210] Comparing the data from Example 1 and Comparative Example 4 shown in Table 1, and combining the data from Example 1 and Comparative Example 4, it can be seen that in Comparative Example 4, replacing the isoprene monomer used in Example 1 with the acrylate monomer resulted in a greater filtration loss and a weaker filtration loss reduction effect. Analysis suggests that the main reason is the insufficient temperature resistance of the acrylate, which decomposes at a high temperature of 260°C.

[0211] Comparing the data from Example 1 and Comparative Example 5 shown in Table 1, and combining the data from both examples, it can be seen that in Comparative Example 5, replacing the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt monomer used in Example 1 with sodium styrene sulfonate resulted in an increase in the filtration loss of the product. The analysis suggests that this may be because the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt monomer used in Example 1 contains a quaternary phosphine salt structure, which enhances the polarity and adsorption capacity of the resulting product, thus improving its adsorption capacity on clay and barite, and consequently contributing to a reduction in filtration loss.

[0212] Comparing the data of Example 1 and Comparative Example 6 shown in Table 1, and combining the data of Example 1 and Comparative Example 6, it can be seen that, compared to Example 1, the filtration loss of the product obtained in Comparative Example 6, which did not use the 1-vinylimidazol monomer, was higher. The reason for this is that in Example 1, the filtration loss reducer was prepared using the 1-vinylimidazol monomer. The introduction of the 1-vinylimidazol structure increased the rigidity of the product and improved its adsorption capacity. However, in Comparative Example 6, without the 1-vinylimidazol monomer, the high-temperature adsorption capacity of the obtained product was reduced, thus increasing the filtration loss.

[0213] Comparing the data of Example 2 and Comparative Example 8 shown in Table 1, and combining them with the data of Example 2 and Comparative Example 8, it can be seen that when the monomer ratio exceeds a certain range, the molecular weight of the product does not change significantly, and the particle size does not change significantly. However, the filtration loss of the filtration loss reduction agent product increases. It is believed that this is due to the unreasonable ratio between the lipophilic monomer and the hydrophilic monomer used in the preparation of the filtration loss reduction agent in Comparative Example 8, which leads to a change in the hydrophilic and lipophilic properties of the product. Specifically, it causes the product to have increased hydrophilicity and decreased lipophilicity.

[0214] The experimental results above show that the monomer components used in the preparation of the ultra-high temperature resistant filtration loss reducer of the present invention have a synergistic effect. If a certain monomer component is missing or is replaced with another monomer component commonly used in this field, the filtration loss reduction performance, high temperature resistance and other properties of the prepared filtration loss reducer are inferior to the corresponding performance of the filtration loss reducer provided by the present invention.

[0215] In summary, the ultra-high temperature resistant filtration loss reducer provided by this invention not only requires a small amount to achieve a significant filtration loss reduction effect, but also has the characteristics of being resistant to ultra-high temperatures and having minimal impact on the rheological properties of oil-based drilling fluids.

[0216] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A high-temperature resistant filtration loss reducer, characterized in that, The ultra-high temperature filtration loss reducing agent is obtained by first reacting lithium magnesium silicate with an alkenyl-containing silane coupling agent to generate alkenyl-containing silane-modified lithium magnesium silicate, and then copolymerizing the alkenyl-containing silane-modified lithium magnesium silicate with isoprene, 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt, styrene and vinylimidazole.

2. The ultra-high temperature resistant filtration loss reducer according to claim 1, characterized in that, The ultra-high temperature resistant filtration loss reducer is prepared by a method including the following steps: S1: Add 19.5-58.6 parts by weight of lithium magnesium silicate to 1000 parts by weight of deionized water to obtain a lithium magnesium silicate dispersion, and then allow the lithium magnesium silicate dispersion to stand and hydrate. S2: Under stirring conditions, add 14.8-28.0 parts by weight of an alkenyl-containing silane coupling agent to the solution obtained in S1, then adjust the pH of the system to 4-6, and allow the alkenyl-containing silane coupling agent to fully react with lithium magnesium silicate to obtain an alkenyl-containing silane-modified lithium magnesium silicate aqueous solution, and then dry the aqueous solution and allow it to cool naturally. S3: Add the alkenyl-containing silane-modified magnesium lithium silicate obtained in S2 to 500 parts by weight of deionized water and mix thoroughly. Then, heat the system to 40-50°C using a water bath. o C; S4: Add 60-80 parts by weight of surfactant, 22.1-44.2 parts by weight of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3, and ensure that the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole are fully dissolved; then allow the resulting solution to stand in an anaerobic environment at 70-75°C. o The reaction was carried out at a constant temperature of C for 30-40 min. After the reaction was completed, 13.6-20.4 parts by weight of isoprene and 5.2-15.6 parts by weight of styrene were added to the resulting solution to form a microemulsion. Then, 0.5-1.5 parts by weight of an oil-soluble initiator were added to the microemulsion, and the temperature was raised to 75±2℃. o The reaction proceeds for 1-3 hours, and the ultra-high temperature resistant filtration loss reducer is obtained after the reaction is completed.

3. The ultra-high temperature resistant filtration loss reducer according to claim 2, characterized in that, The preparation method further includes: S5: The polymer emulsion obtained in S4 is dried, and the dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is then stirred and allowed to stand to allow the solid phase to fully precipitate. S6: After discarding the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, and then dry the turbid liquid until constant weight to obtain the ultra-high temperature filtration loss reducing agent.

4. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The alkenyl-containing silane coupling agent includes silane coupling agents containing vinyl, propenyl, or allyl groups.

5. The ultra-high temperature resistant filtration loss reducer according to claim 4, characterized in that, The alkenyl-containing silane coupling agent includes one or a combination of several of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinylmethyldimethoxysilane.

6. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The lithium magnesium silicate has a nanosheet structure with a particle size of 30-70 nm and a thickness of 5-15 nm.

7. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The vinylimidazole includes one or a combination of 1-vinylimidazole and vinylimidazole having the structure shown in Formula I below; Formula I In Formula I, R2 includes methyl, ethyl, n-propyl, isopropyl, or butyl, and X - This includes tetrafluoroborate, chloride, or bromide ions.

8. The ultra-high temperature resistant filtration loss reducer according to claim 7, characterized in that, The vinylimidazole includes one or a combination of several of 1-vinyl-3-ethylimidazolium tetrafluoroborate, 1-vinyl-3-ethylimidazolium bromide, 1-vinylimidazole and 1-vinyl-3-butylimidazolium chloride.

9. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The molar ratio between lithium magnesium silicate and the alkenyl-containing silane coupling agent is 1:1, wherein the molecular weight of lithium magnesium silicate is 361 g / mol.

10. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The molar ratio of the alkenyl-containing silane coupling agent, isoprene, styrene, 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole is 2:5:2:1:

2.

11. The ultra-high temperature resistant filtration loss reducer according to claim 2 or 3, characterized in that, The surfactant comprises any combination of two of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, octylphenol polyoxyethylene ether, and cashew phenol polyoxyethylene ether.

12. The ultra-high temperature resistant filtration loss reducer according to claim 11, characterized in that, The surfactant comprises sodium dodecylbenzenesulfonate and octylphenol polyoxyethylene ether in a mass ratio of 3:2, or sodium dodecyl sulfate and octylphenol polyoxyethylene ether in a mass ratio of 7:3, or sodium dodecylbenzenesulfonate and cashew phenol polyoxyethylene ether in a mass ratio of 4:

1.

13. The ultra-high temperature resistant filtration loss reducing agent according to claim 2 or 3, characterized in that, The oil-soluble initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, or azobiscyclohexylformitrile.

14. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The molecular weight of the ultra-high temperature resistant filtration loss reducer is 10,000-50,000.

15. The ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-3, characterized in that, The average particle size of the ultra-high temperature resistant filtration loss reducer is 50-150 nm.

16. The ultra-high temperature resistant filtration loss reducer according to claim 15, characterized in that, The average particle size of the ultra-high temperature resistant filtration loss reducer is 70-100 nm.

17. The method for preparing the ultra-high temperature resistant filtration loss reducing agent according to any one of claims 1-16, characterized in that, The preparation method includes: First, lithium magnesium silicate is reacted with an alkenyl-containing silane coupling agent to generate alkenyl-containing silane-modified lithium magnesium silicate. Then, the alkenyl-containing silane-modified lithium magnesium silicate is copolymerized with isoprene, 4-vinylbenzenesulfonic acid-tetrabutylphosphine salt, styrene, and vinylimidazole. After the reaction is completed, the ultra-high temperature filtration loss reducing agent is obtained.

18. The preparation method according to claim 17, characterized in that, The preparation method specifically includes: S1: Add 19.5-58.6 parts by weight of lithium magnesium silicate to 1000 parts by weight of deionized water to obtain a lithium magnesium silicate dispersion, and then allow the lithium magnesium silicate dispersion to stand and hydrate. S2: Under stirring conditions, add 14.8-28.0 parts by weight of an alkenyl-containing silane coupling agent to the solution obtained in S1, then adjust the pH of the system to 4-6, and allow the alkenyl-containing silane coupling agent to fully react with lithium magnesium silicate to obtain an alkenyl-containing silane-modified lithium magnesium silicate aqueous solution, and then dry the aqueous solution and allow it to cool naturally. S3: Add the alkenyl-containing silane-modified magnesium lithium silicate obtained in S2 to 500 parts by weight of deionized water and mix thoroughly. Then, heat the system to 40-50°C using a water bath. o C; S4: Add 60-80 parts by weight of surfactant, 22.1-44.2 parts by weight of 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt, and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3, and ensure that the 4-vinylbenzenesulfonic acid-tetrabutyl quaternary phosphine salt and vinylimidazole are fully dissolved; then allow the resulting solution to stand in an anaerobic environment at 70-75°C. o The reaction was carried out at a constant temperature of C for 30-40 min. After the reaction was completed, 13.6-20.4 parts by weight of isoprene and 5.2-15.6 parts by weight of styrene were added to the resulting solution to form a microemulsion. Then, 0.5-1.5 parts by weight of an oil-soluble initiator were added to the microemulsion, and the temperature was raised to 75±2℃. o The reaction proceeds for 1-3 hours, and the ultra-high temperature resistant filtration loss reducer is obtained after the reaction is completed.

19. The preparation method according to claim 18, characterized in that, The preparation method further includes: S5: The polymer emulsion obtained in S4 is dried, and the dried product is added to an aqueous solution containing ethanol to adjust it into a turbid liquid. The turbid liquid is then stirred and allowed to stand to allow the solid phase to fully precipitate. S6: After discarding the supernatant in the system obtained in S5, add deionized water to adjust the precipitate to a turbid liquid, and then dry the turbid liquid until constant weight to obtain the ultra-high temperature filtration loss reducing agent.

20. The preparation method according to claim 18 or 19, characterized in that, The preparation method further includes: In S2, after adjusting the pH of the system to 4-6, an alcohol solvent produced during the hydrolysis of the alkenyl-containing silane coupling agent is added to the system to ensure that the alkenyl-containing silane coupling agent reacts fully with lithium magnesium silicate; wherein, the amount of alcohol solvent added is 3-30%.

21. An oil-based drilling fluid, characterized in that, The oil-based drilling fluid contains the ultra-high temperature resistant filtration loss reducer as described in any one of claims 1-16.

22. The oil-based drilling fluid according to claim 21, characterized in that, The amount of the ultra-high temperature resistant filtration loss reducer added is 1-3%.

23. An oilfield drilling method, characterized in that, The oilfield drilling method is implemented using the oil-based drilling fluid described in claim 21 or 22.

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