Plugging-type fluid loss additive, preparation thereof, oil-based drilling fluid, and oilfield drilling method

Abstract

This invention provides a plugging-type filtration loss reducer, its preparation, an oil-based drilling fluid, and an oilfield drilling method. The plugging-type filtration loss reducer is prepared 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 acrylate, styrene, and vinylimidazole. The plugging-type filtration loss reducer provided by this invention features low dosage, significant filtration loss reduction effect, outstanding temperature resistance, and minimal impact on the rheological properties of oil-based drilling fluids.

Description

Technical Field

[0001] This invention relates to a plugging-type filtration reduction agent 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 by sealing formation micropores, participating in mud cake formation, enhancing mud cake quality, reducing mud cake permeability, and decreasing drilling fluid filtration loss. Currently, conventional filtration reducers for oil-based drilling fluids are generally natural asphalt or oxidized asphalt with different softening points, including small amounts of sulfonated asphalt and modified humic acid filtration reducers. In practice, these conventional oil-based drilling fluid filtration reducers commonly suffer from excessive dosage, which negatively impacts the rheological properties of the drilling fluid.

[0003] Among them, modified humic acid-based filtration loss reducers are obtained by lipophilic modification of humic acid raw materials. Organically modified humic acid and lignite-based filtration loss reducers often have problems such as poor compatibility with oil-based drilling fluids and a rapid decrease in filtration loss reduction effect.

[0004] For asphalt-based fluid loss reducers, these agents 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 fluid loss reduction effects. Conversely, when the formation temperature is much lower than the asphalt softening point, the asphalt-based fluid loss reducer often exists in the drilling fluid as a large solid phase, significantly reducing its fluid loss reduction effect and increasing the solid content in the drilling fluid, leading to excessively high viscosity. Furthermore, the resins and asphaltenes contained in asphalt-based fluid loss reducers dissolve in the oil phase, increasing the liquid phase viscosity and thus thickening the oil-based drilling fluid. In addition, the fluorescence properties of asphalt-based fluid loss reducers can affect the accuracy of geological logging. Moreover, asphalt easily causes environmental pollution; therefore, reducing the use of these fluid loss reducers has become a significant challenge for oilfields.

[0005] Therefore, providing a novel, highly efficient plugging agent for reducing filtration loss, its preparation, oil-based drilling fluid, and oilfield drilling methods have become urgent technical problems to be solved in this field. Summary of the Invention

[0006] To address the problems of high dosage, increased solid phase, and impact on rheological properties associated with the most widely used and extensively applied asphalt-based oil-based drilling fluid filtration reducers, as well as the problems of poor compatibility and rapid failure of filtration reduction effects associated with humic acid-based filtration reducers, one objective of this invention is to provide a plugging-type filtration reducer.

[0007] Another object of the present invention is to provide a method for preparing the above-described blocking filtration reduction agent.

[0008] Another object of the present invention is to provide an oil-based drilling fluid comprising the above-described plugging filtration reducer.

[0009] Another object of the present invention is to provide an oilfield drilling method that utilizes the oil-based drilling fluid described above.

[0010] To achieve the above objectives, on the one hand, the present invention provides a blocking-type filtration loss reducing agent, wherein the blocking-type 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 acrylate, styrene and vinylimidazole.

[0011] As a specific embodiment of the blocking-type filtration loss reducing agent described above in this invention, the blocking-type filtration loss reducing agent is prepared by a method including the following steps:

[0012] S1: Add 40.0-60.0 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.

[0013] 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.

[0014] 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.

[0015] S4: Add 60-100 parts by weight of surfactant and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3 and allow the vinylimidazole to dissolve completely. Then add 0.20-0.25 parts by weight of molecular weight regulator. React the resulting solution under anaerobic conditions at a constant temperature of 70-75°C for 30-40 minutes. After the reaction is complete, add 8.6-65.0 parts by weight of acrylate and 10.4-20.8 parts by weight of styrene to the resulting solution to form a microemulsion. Then add 1.5-4.97 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2°C to react for 1-3 hours. After the reaction is complete, the blocking filtration loss reducer is obtained.

[0016] As a specific embodiment of the plugging-type filtration loss reducing agent described above in this invention, the preparation method further includes:

[0017] 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.

[0018] 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 blocking filtration reduction agent.

[0019] As a specific embodiment of the blocking-type 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.

[0020] Preferably, the alkenyl-containing silane coupling agent includes one or a combination of several of vinyltriethoxysilane (A-151), vinyltrimethoxysilane (A-171), vinyltri(2-methoxyethoxy)silane (A-172), and vinylmethyldimethoxysilane (A-2171).

[0021] The alkenyl-containing silane coupling agents used in this invention are commercially available conventional products, such as those purchased from Compton International Chemicals, Inc.

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

[0023] The lithium magnesium silicate used in this invention is also a commercially available product, such as that available from Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0024] As a specific embodiment of the blocking-type filtration reduction 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;

[0025]

[0026] In Formula I, R2 includes methyl, ethyl, n-propyl, isopropyl, or butyl, and X - Including tetrafluoroborate, chloride, or bromide ions;

[0027] Preferably, the vinylimidazole comprises one or a combination of several of 1-vinyl-3-ethylimidazole tetrafluoroborate, 1-vinyl-3-ethylimidazole bromide, 1-vinylimidazole and 1-vinyl-3-butylimidazole chloride, and more preferably, the vinylimidazole is 1-vinylimidazole.

[0028] The vinylimidazole used in this invention is also a commercially available conventional product, such as the corresponding product available from Shanghai Chengjie Chemical Co., Ltd.

[0029] As a specific embodiment of the blocking-type filtration loss reducing agent described above in this invention, the acrylate includes one of methyl acrylate, ethyl acrylate, methyl 2-methacrylate, ethyl 2-methacrylate, octadecyl acrylate, etc.

[0030] In one specific embodiment of the plugging-type filtration loss reducing agent described above in this invention, the molar ratio between lithium magnesium silicate and the silane coupling agent containing an alkenyl group is 1:1 to 1:1.5, preferably 1:1 or 1:1.5, wherein the molecular weight of lithium magnesium silicate is 361 g / mol.

[0031] In one specific embodiment of the blocking-type filtration loss reducing agent described above in this invention, the molar ratio between the alkenyl-containing silane coupling agent, acrylate, styrene and vinylimidazole is 2-3:2-4:2-4:1-2, preferably 2:3:3:2 or 3:3:3:1.

[0032] As a specific embodiment of the blocking-type filtration loss reducing agent described above in this invention, the surfactant includes 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).

[0033] The surfactants used in this invention are all commercially available conventional products.

[0034] As a specific embodiment of the blocking-type 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.

[0035] As a specific embodiment of the plugging-type filtration loss reducing agent described above in this invention, the oil-soluble initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, or azobiscyclohexylformitrile.

[0036] The oil-soluble initiators used in this invention are all commercially available conventional products.

[0037] As a specific embodiment of the blocking-type filtration reduction agent described above in this invention, the molecular weight regulator includes one or two of tert-dodecyl mercaptan, diisopropyl disulfide xanthate, etc.

[0038] The molecular weight regulators used in this invention are all commercially available conventional products.

[0039] The plugging-type filtration 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. As a specific embodiment of the plugging-type filtration reducer described above, the molecular weight of the plugging-type filtration reducer is 10,000-30,000.

[0040] As a specific embodiment of the blocking-type filtration loss reducing agent described above in this invention, the average particle size of the blocking-type filtration loss reducing agent is 50-150 nm, preferably 92 nm.

[0041] On the other hand, the present invention also provides a method for preparing the above-mentioned blocking-type filtration loss reducing agent, wherein the preparation method includes:

[0042] 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 acrylate, styrene, and vinylimidazole. After the reaction is completed, the blocking filtration reduction agent is obtained.

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

[0044] S1: Add 40.0-60.0 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.

[0045] 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.

[0046] 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.

[0047] S4: Add 60-100 parts by weight of surfactant and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3 and allow the vinylimidazole to dissolve completely. Then add 0.20-0.25 parts by weight of molecular weight regulator. React the resulting solution under anaerobic conditions at a constant temperature of 70-75°C for 30-40 minutes. After the reaction is complete, add 8.6-65.0 parts by weight of acrylate and 10.4-20.8 parts by weight of styrene to the resulting solution to form a microemulsion. Then add 1.5-4.97 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2°C to react for 1-3 hours. After the reaction is complete, the blocking filtration loss reducer is obtained.

[0048] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes:

[0049] 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.

[0050] 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 blocking filtration reduction agent.

[0051] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes:

[0052] 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.

[0053] In one specific embodiment of the preparation method described above, in step S1, 40.0-60.0 parts by weight of lithium magnesium silicate are added to 1000 parts by weight of deionized water, and the mixture is 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.

[0054] 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:

[0055]

[0056] In Formula II, R1 varies depending on the vinylsilane coupling agent, for example, it may be methyl or ethyl.

[0057] 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.

[0058] In a specific embodiment of the preparation method described above, in S4, acrylate and styrene are hydrophobic monomers (oil-soluble monomers). According to the principle of like dissolves like, acrylate is readily soluble in substances containing esters, while styrene containing a benzene ring is readily soluble in oil-soluble substances containing an aromatic ring. By introducing these two monomers, the dispersion performance of the synthesized plugging filtration reducer product in oil can be enhanced. Simultaneously, a certain proportion of vinylimidazole monomer is introduced, mainly considering the hydrophilicity of the imidazole group and its adsorption effect in nano- and micro-cracks, thereby regulating the product's distribution at the oil-water interface and enhancing its plugging effect on nano-scale micro-cracks during use.

[0059] In a specific embodiment of the preparation method described above, in S4, vinylimidazole is a hydrophilic monomer. Its imidazole structure enhances the adsorption capacity of the synthesized polymer, making it easier to embed into the clay (organic clay) layers and adsorb onto the surface of clay or barite. Furthermore, the five-membered ring structure in this vinylimidazole monomer further improves the temperature and salt resistance of the synthesized plugging filtration reducer product, thereby reducing the filtration loss of oil-based drilling fluids and improving plugging capability.

[0060] In this invention, the reaction process of alkenyl-containing silane-modified magnesium lithium silicate (taking vinylsilane-modified magnesium lithium silicate as an example) with acrylate, styrene, and vinylimidazolium (taking vinylimidazolium having the structure shown in Formula I above as an example) is shown in Formula III below:

[0061]

[0062] In Equation III, the molar ratio of x, y, z and n is 2-3:2-4:2-4:1-2.

[0063] 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.

[0064] 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, thereby reducing the negative impact of the surfactants used in the synthesis reaction on the oil-based drilling fluid when the plugging filtration reducer is subsequently added.

[0065] In another aspect, the present invention also provides an oil-based drilling fluid, wherein the oil-based drilling fluid comprises the above-described plugging filtration reducer.

[0066] As a specific embodiment of the oil-based drilling fluid described above in this invention, the amount of the plugging-type filtration reducer added is 1-3%, where 1-3% is a mass-volume ratio. For example, if 1g of the plugging-type filtration reducer is added to 100mL of drilling fluid or base slurry, the amount of the plugging-type filtration reducer added is 1%.

[0067] 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.

[0068] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0069] This invention synthesizes a plugging-type filtration reducer for oil-based drilling fluids through organic-inorganic composite modification. In preparing the 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, oil-soluble monomers, namely styrene, acrylate, and a hydrophilic monomer, namely vinylimidazole, are polymerized with alkenyl-containing active lithium magnesium silicate through microemulsion polymerization, ultimately forming an organic-inorganic polymer composite, namely the organic-inorganic nanocomposite filtration reducer. This invention, through hydrophobic modification, endows hydrophilic lithium magnesium silicate with a certain degree of hydrophobicity, solving the problem of lipophilic dispersion of lithium magnesium silicate. Simultaneously, the filtration reducer obtained by this invention is an inorganic-organic polymer composite, in which the inorganic part performs a plugging function while the organic polymer chains act as a "bridging" agent, further enhancing the product's plugging and filtration reduction effects.

[0070] This invention synthesizes the 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.

[0071] This invention effectively controls the polymer chain length by selecting appropriate initiators and molecular weight regulators and controlling their dosage, resulting in polymer chains with good filtration loss reduction and self-dispersibility, effectively preventing the aggregation of plugging filtration loss reduction agent particles; furthermore, the synthesized product, while possessing excellent plugging and filtration loss reduction performance, does not affect the rheological properties of the drilling fluid.

[0072] This invention optimizes the ratio of hydrophilic and hydrophobic monomers to hydrophilic lithium magnesium silicate, thereby producing a product with a certain degree of amphiphilicity. This amphiphilic product is also a good "solid particle emulsifier" that can play an auxiliary emulsification role in oil-based drilling fluids, thereby further improving the emulsification stability of oil-based drilling fluids, increasing demulsification voltage, and reducing filtration loss.

[0073] In summary, the plugging filtration reducer provided by this invention has the characteristics of low addition amount, significant filtration reduction effect, outstanding temperature resistance, and minimal impact on the rheological properties of oil-based drilling fluids. Detailed Implementation

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] Example 1

[0081] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0082] 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.

[0083] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0084] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0085] S4: Add 80.0g of surfactant composition (48.0g of SDBS and 32.0g of OP-10) and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to fully dissolve the 1-vinylimidazole. Then add 0.25g of molecular weight regulator tert-dodecyl mercaptan. After purging with nitrogen for 30min, heat to 70℃ and maintain this temperature for 30min. Then add the remaining lipophilic monomer mixture (12.9g of methyl acrylate and 15.6g of styrene) and 1.5g of initiator azobisisobutyronitrile (AIBN) dropwise to the system, and complete the dropwise addition of the lipophilic monomer mixture and initiator within 2h. After the dropwise addition is complete, raise the temperature of the system to 75℃ and react for 1h.

[0086] 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.

[0087] 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 a blocking filtration reducer with a molecular weight of 18000 and an average particle size of 92nm.

[0088] Example 2

[0089] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0090] 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.

[0091] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0092] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0093] S4: 100.0 g of the surfactant composition (60.0 g of SDBS and 40.0 g of OP-10), 9.4 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.25 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (48.6 g of octadecyl acrylate and 15.6 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0094] 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.

[0095] 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 a blocking filtration reducer with a molecular weight of 17000 and an average particle size of 90nm.

[0096] Example 3

[0097] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0098] 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.

[0099] S2: Under stirring, add 19.0g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 4.6g of ethanol and stir at 3000±100rpm for 1h to allow vinyltriethoxysilane to fully react with magnesium lithium silicate to form a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0100] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate formed 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.

[0101] S4: 80.0 g of the surfactant composition (48.0 g of SDBS and 32.0 g of OP-10), 9.4 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.25 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (12.9 g of methyl acrylate and 15.6 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile (AIBN) were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0102] 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.

[0103] 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 a blocking filtration reducer with a molecular weight of 18000 and an average particle size of 92nm.

[0104] Example 4

[0105] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0106] 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.

[0107] S2: Under stirring, add 19.0g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 4.6g of ethanol and stir at 3000±100rpm for 1h to allow vinyltriethoxysilane to fully react with magnesium lithium silicate to form a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0108] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate formed 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.

[0109] S4: 80.0 g of the surfactant composition (48.0 g of SDBS and 32.0 g of OP-10), 9.4 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.20 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (12.9 g of methyl acrylate and 15.6 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0110] 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.

[0111] 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 a blocking filtration reducer with a molecular weight of 25,000 and an average particle size of 100 nm.

[0112] Example 5

[0113] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0114] 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.

[0115] S2: Under stirring, add 19.0g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 4.6g of ethanol and stir at 3000±100rpm for 1h to allow vinyltriethoxysilane to fully react with magnesium lithium silicate to form a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0116] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate formed 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.

[0117] S4: 80.0 g of the surfactant composition (48.0 g of SDBS and 32.0 g of OP-10), 3.18 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.25 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (32.4 g of octadecyl acrylate and 10.4 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0118] 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.

[0119] 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 a blocking filtration reducer with a molecular weight of 20,000 and an average particle size of 95 nm.

[0120] Example 6

[0121] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0122] 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.

[0123] S2: Under stirring, add 22.2g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0124] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0125] S4: 80.0 g of the surfactant composition (48.0 g of SDBS and 32.0 g of OP-10), 4.7 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.25 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (48.6 g of octadecyl acrylate and 15.6 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0126] 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.

[0127] 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 a blocking filtration reducer with a molecular weight of 20,000 and an average particle size of 90 nm.

[0128] Comparative Example 1

[0129] This comparative example provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0130] 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.

[0131] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0132] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0133] S4: Add 80.0 g of surfactant composition (48.0 g of SDBS and 32.0 g of OP-10) and 0.25 g of molecular weight regulator tert-dodecyl mercaptan sequentially to a glass reactor. After purging with nitrogen for 30 min, heat to 70 °C and maintain this temperature for 30 min. Then, add the remaining lipophilic monomer mixture (12.9 g of methyl acrylate and 15.6 g of styrene) and 1.5 g of initiator azobisisobutyronitrile (AIBN) dropwise to the system, ensuring the dropwise addition of the lipophilic monomer mixture and initiator is completed within 2 h. After the dropwise addition is complete, raise the temperature of the system to 75 °C and react for 1 h.

[0134] 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.

[0135] 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 a blocking filtration reducer with a molecular weight of 19000 and an average particle size of 96nm.

[0136] Comparative Example 2

[0137] This comparative example provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0138] 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.

[0139] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0140] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0141] S4: Add 80.0g of surfactant composition (48.0g of SDBS and 32.0g of OP-10) and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to fully dissolve the 1-vinylimidazole. Purge with nitrogen for 30 min, heat to 70°C, maintain this temperature, and react at 70°C for 30 min. Then, add the remaining lipophilic monomer mixture (12.9g of methyl acrylate and 15.6g of styrene) and 1.5g of initiator azobisisobutyronitrile (AIBN) dropwise to the system, ensuring that the lipophilic monomer mixture and initiator are added dropwise over 2 h. After the addition is complete, heat the system to 75°C and react for 1 h.

[0142] 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.

[0143] 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 a blocking filtration reducer with a molecular weight of 40,000 and an average particle size of 180 nm.

[0144] Comparative Example 3

[0145] This comparative example provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0146] 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.

[0147] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0148] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0149] S4: Add 80.0g of surfactant composition (48.0g of SDBS and 32.0g of OP-10) and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to fully dissolve the 1-vinylimidazole. Then add 0.25g of molecular weight regulator tert-dodecyl mercaptan. After purging with nitrogen for 30min, heat to 70℃ and maintain this temperature for 30min. Then add the remaining lipophilic monomer mixture (25.8g of methyl acrylate and 7.8g of styrene) and 1.5g of initiator azobisisobutyronitrile (AIBN) dropwise to the system, and complete the dropwise addition of the lipophilic monomer mixture and initiator within 2h. After the dropwise addition is complete, raise the temperature of the system to 75℃ and react for 1h.

[0150] 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.

[0151] 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 a blocking filtration reducer with a molecular weight of 20,000 and an average particle size of 94 nm.

[0152] Comparative Example 4

[0153] This comparative example provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0154] 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.

[0155] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0156] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0157] S4: Add 80.0g of surfactant composition (48.0g of SDBS and 32.0g of OP-10) and 9.4g of 1-vinylimidazole sequentially to a glass reactor. Add a certain amount of deionized water and stir to fully dissolve the 1-vinylimidazole. Then add 0.25g of molecular weight regulator tert-dodecyl mercaptan. After purging with nitrogen for 30min, heat to 70℃ and maintain this temperature for 30min. Then add the remaining lipophilic monomer mixture (12.9g of methyl acrylate and 15.6g of styrene) and 1.5g of initiator ammonium persulfate dropwise to the system, and complete the dropwise addition of the lipophilic monomer mixture and initiator within 2h. After the dropwise addition is complete, raise the temperature of the system to 75℃ and react for 1h.

[0158] 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.

[0159] 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 a blocking filtration reducer with a molecular weight of 6000 and an average particle size of 66nm.

[0160] Comparative Example 5

[0161] This comparative example provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0162] 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.

[0163] S2: Under stirring, add 14.8g of vinyltrimethoxysilane (A-171, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 3.2g of methanol and stir at 3000±100rpm for 1h to allow vinyltrimethoxysilane to fully react with magnesium lithium silicate to form a vinyltrimethoxysilane-modified magnesium lithium silicate aqueous solution; dry the formed solution at 105℃ and then let it cool naturally to room temperature.

[0164] S3: Add the vinyltrimethoxysilane-modified magnesium lithium silicate formed 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.

[0165] S4: Add 80.0g of surfactant composition (48.0g of SDBS and 32.0g of OP-10) and 7.1g of acrylamide sequentially to a glass reactor. Add a certain amount of deionized water and stir to fully dissolve the acrylamide. Then add 0.25g of molecular weight regulator tert-dodecyl mercaptan. After purging with nitrogen for 30min, heat to 70℃ and maintain this temperature for 30min. Then add the remaining lipophilic monomer mixture (12.9g of methyl acrylate and 15.6g of styrene) and 1.5g of initiator azobisisobutyronitrile (AIBN) dropwise to the system, and complete the dropwise addition of the lipophilic monomer mixture and initiator within 2h. After the dropwise addition is complete, heat the system to 75℃ and react for 1h.

[0166] 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.

[0167] 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 a blocking filtration reducer with a molecular weight of 20,000 and an average particle size of 90 nm.

[0168] Comparative Example 6

[0169] This embodiment provides a blocking-type filtration loss reducing agent, which is prepared by a method including the following specific steps:

[0170] 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.

[0171] S2: Under stirring, add 19.0g of vinyltriethoxysilane (A-151, purchased from Compton International Chemical Company, USA) to the magnesium lithium silicate solution prepared in S1, then add acetic acid to adjust the pH of the solution to 4-6, then add 4.6g of ethanol and stir at 3000±100rpm for 1h to allow vinyltriethoxysilane to fully react with magnesium lithium silicate to form a vinyltriethoxysilane-modified magnesium lithium silicate aqueous solution; then dry the formed solution at 105℃ and allow it to cool naturally to room temperature after drying.

[0172] S3: Add the vinyltriethoxysilane-modified magnesium lithium silicate formed 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.

[0173] S4: 80.0 g of the surfactant composition (48.0 g of SDBS and 32.0 g of OP-10), 9.4 g of 1-vinylimidazole, and a certain amount of deionized water were added sequentially and stirred to fully dissolve the 1-vinylimidazole. Then, 0.40 g of the molecular weight regulator tert-dodecyl mercaptan was added. After purging with nitrogen for 30 min, the mixture was heated to 70 °C and maintained at this temperature for 30 min. Subsequently, the remaining lipophilic monomer mixture (12.9 g of methyl acrylate and 15.6 g of styrene) and 1.5 g of the initiator azobisisobutyronitrile were added dropwise over 2 h. After the addition was complete, the system was heated to 75 °C and reacted for 1 h.

[0174] 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.

[0175] 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 a blocking filtration reducer with a molecular weight of 8000 and an average particle size of 81nm.

[0176] Test Example 1

[0177] This test example tests the filtration loss reduction performance and temperature resistance of the blocking filtration loss reducing agents provided in Examples 1-6 and Comparative Examples 1-6, respectively. The tests include the following steps:

[0178] 1) Sample slurry preparation:

[0179] 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.

[0180] Among them, No. 3 white oil was taken from the Changning block in Sichuan Province.

[0181] The oil-based drilling fluid emulsifier-modified rosin salt (CQ-NT) was obtained from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0182] 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.

[0183] 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.

[0184] The calcium chloride used was of analytical grade;

[0185] YX-40, an oil-based drilling fluid plugging agent, was sourced from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0186] The oil-based drilling fluid plugging agent YX-120 was sourced from the Sichuan Qingyuan Drilling and Production Engineering Technology Research Institute.

[0187] The barite was obtained from the Sichuan-Chongqing Drilling and Production Engineering Technology Research Institute.

[0188] 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 Tables 1 and 2 below, and stir at high speed for 10 min to obtain the sample slurry.

[0189] The filter loss reducing agents are the plugging filter loss reducing agents provided in Examples 1-6 and Comparative Examples 1-6, and the 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.

[0190] 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%.

[0191] 2) Test methods and experimental results:

[0192] The sample slurries prepared above were placed in roller furnaces and rolled for 16 hours at (180±2)℃ and (200±2)℃ respectively. After cooling, the tanks were opened, and the water and oil separation of the sample slurries in the aging tanks 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 slurry 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 apparent viscosity (AV), plastic viscosity (PV), dynamic shear force (YP), ES value, and HTHP filtration loss value of the sample slurry at (50±1)℃ and 180℃ and 200℃ were determined according to the provisions of GB / T 16783.2-2012. The test results are shown in Table 1 and Table 2 below.

[0193] Table 1. Comparison of performance of different filtration reducers after aging at 180℃ in white oil-based drilling fluid.

[0194]

[0195]

[0196]

[0197] Table 2. Comparison of performance of different filtration reducers after aging at 200℃ in white oil-based drilling fluid.

[0198]

[0199]

[0200] Note: The asphalt in Tables 1 and 2 is commercially available ordinary oxidized asphalt.

[0201] The percentages in Tables 1 and 2 are mass-volume ratios, calculated based on the total volume of the base slurry. For example, if 18g of asphalt is added to 300mL of base slurry, the amount of asphalt added is 6%.

[0202] As can be seen from Table 1 above, the plugging-type filtration reducer provided in the embodiments of the present invention has a temperature resistance of up to 180℃ in oil-based drilling fluids. Furthermore, this plugging-type filtration reducer product has minimal impact on the rheological properties of oil-based drilling fluids, outstanding filtration reduction effect, good compatibility with filtration 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 to a certain extent.

[0203] Comparing the experimental data in Tables 1 and 2, it can be seen that the plugging-type filtration reducer provided in this embodiment of the invention has a temperature resistance of up to 180℃ in oil-based drilling fluids. However, its filtration loss increases significantly at 200℃, requiring further improvement to enhance its temperature resistance. Nevertheless, at 200℃, compared to filtration reducers for oil-based drilling fluids such as humic acids and conventional polymers, the plugging-type filtration reducer provided in this embodiment of the invention has virtually no impact on the rheological properties of oil-based drilling fluids, and its filtration loss reduction capability is comparable to that of asphalt. The reason for the significant increase in filtration loss at 200℃ in the plugging-type filtration reducer product provided in this embodiment of the invention may be that the acrylate monomer used in the synthesis of the plugging-type filtration reducer is not temperature-resistant and will degrade at high temperatures.

[0204] Comparing the data from Examples 1 and 2 shown in Tables 1 and 2, and combining them with Examples 1 and 2, it can be seen that both octadecyl acrylate and methyl acrylate contribute to the filtration loss reduction capacity of the filtration loss control product. However, the filtration loss control product prepared using octadecyl acrylate as a hydrophobic monomer exhibits a stronger filtration loss reduction capacity. This may be because octadecyl acrylate has a longer hydrophobic chain, resulting in better dispersibility in oil. Meanwhile, comparing the data from Examples 1 and 3 shown in Tables 1 and 2, and combining them with Examples 1 and 3, it can be seen that the filtration loss reduction effect of the blocking filtration loss control product is good regardless of whether vinylmethoxysilane or vinylethoxysilane is used, with very little difference. This indicates that the type of silane coupling agent containing alkenyl groups has little impact on the performance of the prepared blocking filtration loss control product.

[0205] Comparing the data from Example 1 and Comparative Example 1 shown in Tables 1 and 2, and combining them with the data from Example 1 and Comparative Example 1, it can be seen that if hydrophilic monomers are not used when preparing the plugging-type filtration loss reducer, the filtration loss reduction effect of the resulting filtration loss reducer product is reduced, and the product's effect on improving the emulsion stability of oil-based drilling fluid is significantly reduced. Analysis suggests that if all monomers used in the preparation of the plugging-type filtration loss reducer are hydrophobic, the hydrophilicity of the resulting filtration loss reducer product is significantly reduced. In oil-based drilling fluid, it is more dispersed in the oil phase, while the amount adsorbed at the emulsion interface is reduced, thus its stabilizing effect on the emulsion as a solid particle is reduced. Conversely, the presence of an appropriate amount of the hydrophilic monomer "vinylimidazole" allows the filtration loss reducer product to not only adsorb at the oil-water interface, but the imidazole groups can also adsorb on the clay interlayer or the surface of nanofissures, thereby stabilizing the emulsion and strengthening the plugging effect.

[0206] Comparing the data from Examples 4, 5, Comparative Examples 2, and 6 shown in Tables 1 and 2, and combining these data with those from Examples 4, 5, 2, and 6, it can be seen that the amount of molecular weight regulator directly affects the filtration loss reduction effect of the resulting filtration loss reduction agent product. Specifically, a lower amount of molecular weight regulator results in longer polymer chains in the obtained filtration loss reduction agent product, making the thickening effect of the filtration loss reduction agent product more obvious. However, the dispersibility will be affected to some extent, which is not conducive to the filtration loss reduction effect of the filtration loss reduction agent product. Conversely, if the amount of molecular weight regulator is too high, excessive chain transfer will occur, resulting in polymer chains in the filtration loss reduction agent product that are too short. In some cases, the silane-modified magnesium silicate may not form effective polymerization with other monomers, thus reducing the filtration loss reduction effect of the product.

[0207] In addition, compared with the filtration loss reducing agent product obtained in Example 1, Comparative Example 2 did not use a molecular weight regulator, and the HTHP filtration loss value of the filtration loss reducing agent product provided therein was significantly increased, and the filtration loss reduction performance was significantly reduced.

[0208] Comparing the data from Example 1 and Comparative Example 3 shown in Tables 1 and 2, and combining the data from Example 1 and Comparative Example 3, 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 blocking ability of the resulting filtration loss reducing agent product. Analysis suggests that the increased proportion of acrylate and the decreased proportion of styrene reduced the rigidity of the filtration loss reducing agent product, thus adversely affecting its temperature resistance under high-temperature conditions, and consequently impacting its performance after high-temperature aging.

[0209] Comparing the data from Example 1 and Comparative Example 4 shown in Tables 1 and 2, and combining them with the data from Example 1 and Comparative Example 4, it can be seen that when a hydrophilic initiator is used to prepare a blocking-type filtration loss reducer, the filtration loss reduction and blocking effect of the resulting filtration loss reducer product is reduced, and its stabilizing effect on the emulsion is also decreased. Analysis suggests that because this invention uses emulsion polymerization, the external phase is aqueous. Although the amount of 1-vinylimidazole added is small, its reactivity is high. Dispersed in the aqueous phase, due to the barrier effect of the emulsion film, when the reaction temperature is reached, the initiator first initiates the 1-vinylimidazole reaction. After the reaction is complete, the oil-soluble monomer (hydrophobic monomer), which is the internal phase of the emulsion, only partially reacts or does not react at all. This results in an insufficient reaction during the preparation of the filtration loss reducer product, leading to a decrease in the performance of the filtration loss reducer product.

[0210] Comparing the data from Example 1 and Comparative Example 5 shown in Tables 1 and 2, and combining the data from Example 1 and Comparative Example 5, it can be seen that compared to Example 1, which used 1-vinylimidazole as a hydrophilic monomer to prepare the filtration loss reducing agent, and Comparative Example 5, which used conventional acrylamide monomer as a hydrophilic monomer to prepare the filtration loss reducing agent, the filtration loss reducing agent product prepared in Example 1 has a lower HTHP filtration loss value and significantly better blocking and filtration loss reducing performance. Analysis suggests that this is mainly due to: 1) The five-membered ring structure of 1-vinylimidazole makes the resulting filtration loss reducing agent product more resistant to temperature and salt, and more stable at high temperatures; 2) The imidazole structure contains two nitrogen atoms, which have a certain positive charge, making it easier for the filtration loss reducing agent product with the imidazole structure to embed in the clay interlayer and more easily adsorb onto the solid surface of barite and rock fragments, thus making the filtration loss reducing agent product more adsorbent, resulting in a lower HTHP filtration loss value and significantly better blocking and filtration loss reducing performance.

[0211] The experimental results above show that the monomer components used in the preparation of the plugging-type filtration loss reducing agent 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 reducing agent prepared will have inferior filtration loss reducing performance and other properties compared with the corresponding filtration loss reducing agent provided by the present invention.

[0212] Compared with the prior art, the beneficial technical effects that the plugging-type filtration loss reducing agent provided in the embodiments of the present invention can achieve include:

[0213] This invention relates to an organic-inorganic composite modification to synthesize a plugging-type oil-based drilling fluid filtration reducer. In preparing the filtration reducer, a monomer with silane coupling properties, i.e., an alkenyl-containing silane coupling agent, is first reacted with lithium magnesium silicate to modify nano-sized lithium magnesium silicate particles into polymerizable nanoparticles. Then, oil-soluble monomers, i.e., styrene, acrylate, and a hydrophilic monomer, i.e., vinylimidazole, are polymerized with alkenyl-containing active lithium magnesium silicate through microemulsion polymerization, ultimately forming an organic-inorganic polymer composite, i.e., an organic-inorganic nanocomposite filtration reducer.

[0214] The embodiments of the present invention improve the hydrophobicity of magnesium lithium silicate by modifying it to have a certain degree of hydrophobicity, thereby solving the problem of lipophilic dispersion of magnesium lithium silicate.

[0215] Meanwhile, the filtration loss reducing agent obtained in the embodiments of the present invention is an inorganic-organic polymer composite, wherein the inorganic part plays a blocking role while the organic polymer chain can play a certain "bridging" role, further enhancing the blocking and filtration loss reducing effects of the product.

[0216] The present invention synthesizes the filtration loss reducer through microemulsion polymerization, which effectively controls the particle size of the product, 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.

[0217] By selecting appropriate initiators and molecular weight regulators and controlling their dosage, the polymer chain length of the product is effectively controlled, resulting in a polymer chain with good filtration loss reduction and self-dispersibility, effectively preventing the agglomeration of plugging filtration loss reduction agent particles. Furthermore, the synthesized product, while possessing excellent plugging and filtration loss reduction performance, does not affect the rheological properties of the drilling fluid.

[0218] The embodiments of the present invention optimize the hydrophilic monomers and hydrophobic monomers and adjust their ratio with hydrophilic magnesium lithium silicate to make the synthesized product have a certain degree of amphiphilicity. The amphiphilic product is also a good "solid particle emulsifier" that can play an auxiliary emulsification role in oil-based drilling fluids, thereby further improving the emulsification stability of oil-based drilling fluids, increasing the demulsification voltage, and reducing filtration loss.

[0219] In summary, the plugging filtration reducer provided in this embodiment of the invention has the characteristics of low addition amount, significant filtration reduction effect, outstanding temperature resistance, and minimal impact on the rheological properties of oil-based drilling fluids.

[0220] 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 plugging-type filtration loss reducing agent, characterized in that, The blocking-type 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 copolymerizing the alkenyl-containing silane-modified lithium magnesium silicate with acrylate, styrene and vinylimidazole. The blocking-type filtration loss reducing agent is prepared by a method including the following steps: S1: Add 40.0-60.0 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 them evenly. Then heat the system temperature to 40-50℃ by water bath heating. S4: Add 60-100 parts by weight of surfactant and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3 and allow the vinylimidazole to dissolve completely. Then add 0.20-0.25 parts by weight of molecular weight regulator. React the resulting solution under anaerobic conditions at a constant temperature of 70-75°C for 30-40 minutes. After the reaction is complete, add 8.6-65.0 parts by weight of acrylate and 10.4-20.8 parts by weight of styrene to the resulting solution to form a microemulsion. Then add 1.5-4.97 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2°C to react for 1-3 hours. After the reaction is complete, the blocking filtration reduction agent is obtained. The molecular weight regulator includes one or both of tert-dodecyl mercaptan and diisopropyl disulfide xanthate. The oil-soluble initiator includes any one of azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, or azobiscyclohexylformitrile.

2. The plugging-type filtration loss reducing agent according to claim 1, 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 blocking filtration reduction agent.

3. The plugging-type filtration loss reducer according to claim 1, characterized in that, The alkenyl-containing silane coupling agent includes silane coupling agents containing vinyl, propenyl, or allyl groups.

4. The plugging-type filtration loss reducer according to claim 3, 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.

5. The plugging-type filtration loss reducing agent according to any one of claims 1-4, 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.

6. The plugging-type filtration reduction agent according to any one of claims 1-4, 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.

7. The plugging-type filtration loss reducing agent according to claim 6, 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.

8. The plugging-type filtration loss reducing agent according to claim 7, characterized in that, The vinylimidazole is 1-vinylimidazole.

9. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The acrylates include one of methyl acrylate, ethyl acrylate, methyl 2-methacrylate, ethyl 2-methacrylate, and octadecyl acrylate.

10. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The molar ratio between lithium magnesium silicate and the alkenyl-containing silane coupling agent is 1:1 to 1:1.5, wherein the molecular weight of lithium magnesium silicate is 361 g / mol.

11. The plugging-type filtration loss reducing agent according to claim 10, characterized in that, The molar ratio between lithium magnesium silicate and the alkenyl-containing silane coupling agent is 1:1 or 1:1.

5.

12. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The molar ratio between the alkenyl-containing silane coupling agent, acrylate, styrene and vinylimidazole is 2-3:2-4:2-4:1-2.

13. The plugging-type filtration loss reducer according to claim 12, characterized in that, The molar ratio between the alkenyl-containing silane coupling agent, acrylate, styrene, and vinylimidazole is 2:3:3:2 or 3:3:3:

1.

14. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The surfactant comprises any combination of two of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, octylphenol polyoxyethylene ether, and cashew phenol polyoxyethylene ether.

15. The plugging-type filtration loss reducer according to claim 14, 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.

16. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The molecular weight of the blocking-type filtration reduction agent is 10,000-30,000.

17. The plugging-type filtration loss reducing agent according to any one of claims 1-4, characterized in that, The average particle size of the blocking filtration reduction agent is 50-150 nm.

18. The plugging-type filtration loss reducing agent according to claim 17, characterized in that, The average particle size of the plugging-type filtration reduction agent is 92 nm.

19. A method for preparing the blocking-type filtration loss reducing agent according to any one of claims 1-18, 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 acrylate, styrene and vinylimidazole. After the reaction is completed, the blocking filtration loss reducer is obtained. The preparation method specifically includes: S1: Add 40.0-60.0 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 them evenly. Then heat the system temperature to 40-50℃ by water bath heating. S4: Add 60-100 parts by weight of surfactant and 4.7-22.2 parts by weight of vinylimidazole to the solution obtained in S3 and allow the vinylimidazole to dissolve completely. Then add 0.20-0.25 parts by weight of molecular weight regulator. React the resulting solution under anaerobic conditions at a constant temperature of 70-75°C for 30-40 minutes. After the reaction is complete, add 8.6-65.0 parts by weight of acrylate and 10.4-20.8 parts by weight of styrene to the resulting solution to form a microemulsion. Then add 1.5-4.97 parts by weight of oil-soluble initiator to the microemulsion and heat to 75±2°C to react for 1-3 hours. After the reaction is complete, the blocking filtration loss reducer is obtained.

20. The preparation method according to claim 19, 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 blocking filtration reduction agent.

21. The preparation method according to claim 19 or 20, 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%.

22. An oil-based drilling fluid, characterized in that, The oil-based drilling fluid contains a plugging filtration reducer as described in any one of claims 1-18.

23. The oil-based drilling fluid according to claim 22, characterized in that, The amount of the blocking-type filtration reduction agent added is 1-3%.

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

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