Polymer having interpenetrating network structure, and preparation method therefor and use thereof

Abstract

Provided in the present invention are a polymer having an interpenetrating network structure, and a preparation method therefor and the use thereof. The method comprises: polymerizing a polymer framework and a first monomer, wherein the polymer framework is of a network shape and comprises a structural unit derived from a non-ionic monomer, a structural unit derived from an anionic monomer, and a structural unit derived from a phenolic resin; and the first monomer has a structure as represented by formula (A). Formula (A), wherein R0 is a C4-C12 alkyl. The polymer of the present invention does not excessively spread at high temperatures or excessively shrink under high-salt conditions, has good temperature resistance and salt resistance, and exhibits good dispersion stability in high-temperature water / brine. When applied to a drilling fluid and / or a completion fluid, the polymer has good fluid-loss-reducing, lubrication-optimizing and suspension-enhancing effects.

Description

Polymers with interpenetrating network structures, their preparation methods and applications

[0001] Cross-reference of related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411938394.5, filed on December 26, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of oil and gas field drilling technology, specifically to a polymer with an interpenetrating network structure, its preparation method, and its application in drilling fluids and / or completion fluids. Background Technology

[0004] Unconventional oil and gas resources, represented by shale oil and gas, tight oil and gas, and coalbed methane, have proven reserves of 67.1 billion tons of oil equivalent, accounting for 34% of my country's total oil and gas resources. Furthermore, with the steady progress of new energy construction projects such as deep geothermal energy, compressed air energy storage, and the conversion of depleted oil and gas reservoirs into gas storage facilities, my country has entered a new stage of development that emphasizes "conventional + unconventional + new energy." Developing and utilizing new geological resources effectively has become an inevitable choice to support the national energy strategy. Drilling fluids and completion fluids are the circulating media that directly contact the wellbore during drilling operations, and are crucial technologies for ensuring a well can be drilled successfully, efficiently, and quickly. Polymer-based treatment agents are the core technology of drilling and completion fluids, playing a vital role in reducing filtration loss, optimizing lubrication, and enhancing suspension. However, in the drilling and development of new geological resources, unknown and abnormal formations are often encountered, posing multiple challenges to polymer materials used in drilling and completion fluids, including temperature and salinity issues. In response to the demands of new energy development, there is an urgent need to optimize and innovate polymer materials for drilling fluids and completion fluids.

[0005] Conventional drilling and completion fluid polymers are primarily multi-component copolymers based on acrylamide and acrylic acid. By introducing cationic, anionic, or other monomers during synthesis, the polymer acquires its main functions in drilling and completion fluids. Furthermore, the hydrophobic and electrostatic interactions between chemical groups within the polymer enhance its temperature and salt resistance. However, conventional polymer molecules have a one-dimensional linear structure, which suffers from poor rigidity and strength. Due to this structural weakness, polymer molecules are prone to decomposition under high formation temperatures and to shrink and fail in high-salt drilling fluids or when exposed to highly saline formation water. Therefore, improving the performance of polymers for drilling and completion fluids requires not only selecting temperature- and salt-resistant reactive monomers but also optimizing the polymer molecular structure. In recent years, by adjusting the synthesis method and increasing the molecular weight, novel polymers for drilling and completion fluids with comb-like, star-shaped, branched, and hyperbranched molecular structures have emerged. The novel molecular structure, based on the original one-dimensional linear molecular morphology, increases the molecular volume of the side chains to form a three-dimensional network structure, thereby improving the rigidity and strength of the molecular chains. This effectively protects the weaker chemical bonds such as ester bonds, amide bonds, and ether bonds that are easily hydrolyzed, thus enhancing the temperature and salt resistance properties of polymers used in drilling and completion fluids. For example, conventional linear drilling fluid polymer flow modifiers have a temperature resistance of only 120℃, while those optimized to a comb-shaped molecular structure can withstand temperatures up to 180℃. However, although the performance of the polymer systems for drilling and completion fluids developed using the above-mentioned optimized molecular structure method has improved, there is still a gap compared to the high-temperature conditions (often exceeding 200℃) and near-saturated saline conditions encountered in new geological resource drilling. Therefore, it is particularly important to further innovate and optimize the molecular structure of polymers for drilling and completion fluids to break through the current limits of polymer temperature and salt resistance.

[0006] Further optimization of the polymer molecular structure for drilling and completion fluids hinges on effectively controlling the thermal motion of molecular chains in solvents under high-temperature and high-salt conditions to maintain relative stability. However, high temperatures in aqueous environments cause molecular chains to primarily expand outwards, while high salinity causes them to primarily contract inwards. These two completely opposite effects cause irreversible damage to the polymer molecular structure, thus determining the performance limits of polymer systems with single molecular structures. Furthermore, drilling and completion operations often involve mechanical agitation, high-speed shearing of the drill bit's water jets, and multiple cycles of drilling fluid circulation, resulting in significant temperature differences between the surface and the wellbore. These factors place even higher demands on the stability of the polymer molecular structure used in drilling and completion fluids. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems of excessive spreading of polymers at high temperatures and excessive shrinkage under high salinity, and the urgent need to improve the temperature and salt resistance of polymers. This invention provides a polymer with an interpenetrating network structure, its preparation method, and its application in drilling fluids and / or completion fluids. This polymer does not overspread at high temperatures or shrink excessively under high salinity, exhibits excellent temperature and salt resistance, and has good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0008] To achieve the objectives of this invention, a first aspect of this invention provides a method for preparing a polymer having an interpenetrating network structure, the method comprising: polymerizing a polymer backbone with a first monomer; wherein the polymer backbone is a network; the polymer backbone includes structural units derived from a nonionic monomer, structural units derived from an anionic monomer, and structural units derived from a phenolic resin; the first monomer has the structure shown in formula (A);

[0009] Wherein, R0 is a C4-C12 alkyl group.

[0010] A second aspect of the present invention provides a polymer prepared by the method of the present invention.

[0011] A third aspect of the present invention provides the use of the polymer described herein in drilling fluids and / or completion fluids.

[0012] The polymer with an interpenetrating network structure of the present invention does not spread excessively at high temperatures or shrink excessively under high salinity, exhibiting excellent temperature and salt resistance and good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer has excellent effects in reducing filtration loss, optimizing lubrication, and enhancing suspension. Attached Figure Description

[0013] Figure 1 is a schematic diagram of the preparation process of the polymer of the present invention;

[0014] Figure 2 is a scanning electron microscope image of the skeleton prepared in Example 1 of the present invention;

[0015] Figure 3 is a scanning electron microscope image of the skeleton prepared in Example 2 of the present invention;

[0016] Figure 4 is a scanning electron microscope image of the skeleton prepared in Example 3 of the present invention;

[0017] Figure 5 is a scanning electron microscope image of the skeleton prepared in Example 4 of the present invention;

[0018] Figure 6 is a scanning electron microscope image of the polymer of Example 1 of the present invention;

[0019] Figure 7 is a scanning electron microscope image (region 1, region 2) of the polymer of Example 1 of the present invention;

[0020] Figure 8 is the Raman spectrum of region 1 in the polymer of Example 1 of the present invention;

[0021] Figure 9 shows the Raman spectrum of region 2 in the polymer of Example 1 of the present invention;

[0022] Figure 10 shows the hydration kinetics particle size distribution of the polymer in Example 1 in deionized water at room temperature;

[0023] Figure 11 shows the hydration kinetics particle size distribution of the polymer in Example 1 in deionized water at 200°C.

[0024] Figure 12 shows the hydration kinetics particle size distribution of the polymer in Example 1 in salt water at 200°C.

[0025] Figure 13 shows the TSI stability index of the polymer and commercially available drilling fluid polymer treatment agent in high-temperature water / salt water in Example 1.

[0026] Figure 14 is a scanning electron microscope image of the polymer of Comparative Example 1 of the present invention;

[0027] Figure 15 shows the dispersion of the polymer of Comparative Example 1 of the present invention in water. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] To overcome the problems of excessive polymer spreading at high temperatures and excessive shrinkage under high salinity in existing technologies, and the urgent need to improve the temperature and salt resistance of polymers, it is necessary to introduce a second or more structures based on a polymer molecular structure to form a complex morphology of multiple interpenetrating and interlocking molecular chains. This leverages the performance advantages of different molecular chains under conditions such as temperature and salinity to synergistically improve the thermal stability of the polymer in solvents. However, current research reports on polymer systems with multiple interpenetrating molecular structures suitable for drilling and completion fluids are lacking, making it difficult to provide effective reference and guidance.

[0030] This invention provides a method for preparing a polymer with an interpenetrating network structure. The method includes: polymerizing a polymer backbone with a first monomer; wherein the polymer backbone is a network; the polymer backbone includes structural units derived from a nonionic monomer, structural units derived from an anionic monomer, and structural units derived from a phenolic resin; the first monomer has the structure shown in formula (A):

[0031] Wherein, R0 is a C4-C12 alkyl group.

[0032] It should be noted that, in this invention, C4-C12 alkyl groups refer to alkyl groups with a total number of carbon atoms of 4-12. For example, they can be alkyl groups with a total number of carbon atoms of 4, 5, 6, 7, 8, 9, 10, 11, or 12, such as n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl (lauryl), etc. A similar interpretation applies to "C6-C12 alkyl groups".

[0033] Figure 1 shows a schematic diagram of the preparation process of the polymer with an interpenetrating network structure of the present invention. The polymer backbone with a network structure is polymerized with monomers to obtain a polymer with an interpenetrating network structure.

[0034] In this invention, the aforementioned preparation methods can all achieve the objectives of this invention. A wide range of other monomers can be selected for use. The following is an illustrative description, but it does not limit the scope of this invention. According to one embodiment of this invention, the preparation process of the polymer further includes the presence of a second monomer, which has the structure shown in formula (B):

[0035] Wherein, R is a C6-C12 alkyl group. The polymer prepared using the aforementioned technical solution does not exhibit excessive spreading at high temperatures or excessive shrinkage under high salinity, demonstrating excellent temperature and salt resistance. It also exhibits good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0036] In this invention, as long as the purpose of this invention can be achieved, there are no special requirements for the polymerization conditions during the preparation of the polymer. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the polymerization temperature is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, or any two of the above values.

[0037] In this invention, during the preparation of the polymer, the polymerization time is generally adjusted according to the polymerization temperature, etc., and the polymerization time can be selected from a wide range. For example, the polymerization time is 5-8 hours, such as 5 hours, 6 hours, 7 hours, 8 hours, or any two of the above values.

[0038] In this invention, the polymerization process is usually carried out under alkaline conditions. The range of alkaline conditions that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the pH of the polymerization is 10-12, for example, it can be 10, 10.5, 11, 11.5, 12, or any two of the above values.

[0039] In this invention, the polymerization process can be carried out in an inert gas during the preparation of the polymer. The range of inert gases that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. For example, the inert gas is nitrogen.

[0040] In this invention, the polymerization process can be carried out dynamically during the preparation of the polymer. The rotation speed is generally adjusted according to the polymerization temperature, time, etc., and the range of selectable rotation speed is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the rotation speed is 600-800 rpm, for example, it can be 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, or any combination of two of the above values.

[0041] Those skilled in the art will know that in the process of preparing polymers, after polymerization, organic solvents such as anhydrous ethanol are generally used to filter and wash out the product, mainly to remove the reaction solvents, etc., and then the polymer is obtained after drying and pulverizing. This operation is a conventional prior art, and will not be described in detail in this invention.

[0042] In this invention, during the preparation of the polymer, any second monomer having the structure shown in the aforementioned formula (B) can achieve the purpose of this invention. The range of options for the second monomer is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the second monomer is selected from one or more of 3,4,5-tris(n-hexanemethoxy)styrene, 3,4,5-tris(n-octanemethoxy)styrene and 3,4,5-tris(dodecanemethoxy)styrene.

[0043] Those skilled in the art will understand that, in the structure shown in formula (B), when R is a C6 alkyl group, the second monomer is 3,4,5-tris(n-hexanemethoxy)styrene; when R is a C8 alkyl group, the second monomer is 3,4,5-tris(n-octanemethoxy)styrene; and when R is a C12 alkyl group, the second monomer is 3,4,5-tris(dodecanemethoxy)styrene. The polymer prepared using the aforementioned technical solution exhibits excellent temperature and salt resistance, without excessive spreading at high temperatures or excessive shrinkage under high salt conditions. It also demonstrates good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0044] In this invention, during the preparation of the polymer, any first monomer having the structure shown in the aforementioned formula (A) can achieve the purpose of this invention. The range of options for the first monomer is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the first monomer is selected from one or more of butyl methacrylate, hexyl methacrylate, and lauryl methacrylate.

[0045] Those skilled in the art will understand that in the structure shown in formula (A), when R is a C4 alkyl group, the first monomer is butyl methacrylate; when R is a C6 alkyl group, the first monomer is hexyl methacrylate; and when R is a C12 alkyl group, the first monomer is lauryl methacrylate. The polymer prepared using the aforementioned technical solution exhibits excellent temperature and salt resistance, without excessive spreading at high temperatures or excessive shrinkage under high salt conditions. It also demonstrates good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0046] In this invention, the aforementioned preparation methods can all achieve the objectives of this invention. The mass ratio of the polymer backbone to the total amount of added monomers has a wide selectable range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the mass ratio of the polymer backbone to the total amount of added monomers is 1:0.5-2, for example, it can be 1:0.5, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, or any two of the above values. It is understood that the total amount of monomers includes the mass of the first monomer and the mass of the second monomer. The polymer prepared using the aforementioned technical solution will not over-spread at high temperatures or over-shrink under high salinity, exhibiting excellent temperature and salt resistance, and good dispersion stability in high-temperature water / salt water. When this polymer is applied to drilling fluids and / or completion fluids, it has excellent effects in reducing filtration loss, optimizing lubrication, and enhancing suspension.

[0047] In this invention, in order to achieve the purpose of this invention, commonly used materials known to those skilled in the art can be used in the preparation process of the polymer. For example, the polymerization can be carried out in the presence of raw materials such as solubilizer, initiator 1 and crosslinking agent 1. In the preparation process of the polymer, the range of types of raw materials such as solubilizer, initiator 1 and crosslinking agent 1 is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the solubilizer is selected from one or more of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0048] In the preparation of the polymer, according to a preferred embodiment of the present invention, the crosslinking agent 1 is selected from one or more of ethylene glycol dimethacrylate and divinylbenzene. The polymer prepared using the aforementioned technical solution exhibits excellent temperature and salt resistance, without excessive spreading at high temperatures or excessive shrinkage under high salinity, and demonstrates good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0049] In the preparation of polymers, commonly used initiators can be used in this invention. In this invention, the advantages of the invention are illustrated by the example of initiator 1 being selected from one or more of azobisisobutyronitrile and dimethyl azobisisobutyrate, but this does not limit the scope of the invention.

[0050] In this invention, the aforementioned preparation methods can all achieve the objectives of this invention. The range of selectable amounts of the solubilizer and crosslinking agent 1 is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, during the polymer preparation process, the mass ratio of the sum of the polymer backbone and the total amount of monomers to the solubilizer is 1:0.01-0.05, for example, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, or any two of the above values. The mass ratio of the sum of the polymer backbone and the total amount of monomers to the solubilizer refers to the ratio of the mass of the polymer backbone and the total mass of monomers to the mass of the solubilizer.

[0051] According to a preferred embodiment of the present invention, during the preparation of the polymer, the mass ratio of the total amount of the polymer backbone and monomers to the crosslinking agent 1 is 1:0.05-0.2, for example, it can be 1:0.05, 1:0.08, 1:0.1, 1:0.15, 1:0.18, 1:0.2, or any two of the above values. The polymer prepared using the aforementioned technical solution does not exhibit excessive spreading at high temperatures or excessive shrinkage under high salinity, demonstrating excellent temperature and salt resistance, and good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer exhibits excellent effects in reducing filtration loss, optimizing lubrication, and enhancing suspension.

[0052] As is well known to those skilled in the art, the polymerization process is generally carried out in the presence of a solvent. There are no special requirements for the choice of solvent. Those skilled in the art can make conventional selections based on the raw materials and polymerization conditions of the polymerization reaction. For example, in this invention, the solvent can be water, etc.

[0053] In this invention, there are no special requirements for the amount of solvent used in the preparation of the polymer. Those skilled in the art can make conventional selections based on the raw materials and polymerization conditions of the polymerization reaction. For example, the amount of solute can be adjusted. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, in the preparation of the polymer, the mass ratio of the polymer backbone, total monomer, solubilizer and crosslinking agent 1 to the solvent is 1:2-5, for example, it can be 1:2, 1:3, 1:4, 1:5, or any two of the above values.

[0054] In this invention, there are no special requirements for the amount of initiator 1 used in the polymer preparation process. For example, it can be adjusted according to the amount of solvent used. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, in the polymer preparation process, the mass ratio of solvent to initiator 1 is 1:0.001-0.005, for example, it can be 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, or any two of the above values.

[0055] In this invention, the number-average molecular weight of the polymer backbone used in the preparation process can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the number-average molecular weight of the polymer backbone is 0.5 million to 50,000 g / mol, for example, it can be 0.5 million g / mol, 10,000 g / mol, 20,000 g / mol, 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, or any two of the above values.

[0056] Polymer skeletons with the aforementioned technical features can all be used in this invention. The range of optional amounts and types of the nonionic monomer, the anionic monomer, and the phenolic resin is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the mass ratio of the nonionic monomer to the anionic monomer is 1:0.2-1, for example, it can be 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, or any two of the above values.

[0057] According to a preferred embodiment of the present invention, the mass ratio of the total mass of the nonionic monomer and the anionic monomer to the mass of the phenolic resin is 1:0.2-0.5, for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, or any two of the above values.

[0058] According to a preferred embodiment of the present invention, the nonionic monomer is selected from one or more of acrylamide, N-hydroxymethylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, vinylpyrrolidone, and vinylcaprolactam.

[0059] According to a preferred embodiment of the present invention, the anionic monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid and sodium styrenesulfonate.

[0060] According to a preferred embodiment of the present invention, the phenolic resin is a water-soluble phenolic resin, and the phenolic resin contains structural units shown in formula (C) and optionally structural units shown in formula (D):

[0061] In this invention, phenolic resins having the aforementioned structure can be used to form the polymer backbone required by this invention. The number-average molecular weight of the phenolic resin can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the number-average molecular weight of the phenolic resin is 500-1200 g / mol.

[0062] In this invention, any phenolic resin possessing the aforementioned technical features can be used to form the polymer skeleton required by this invention. There are no special requirements for the preparation method of the phenolic resin. One embodiment is illustrated, but this does not limit the scope of the invention. According to a preferred embodiment of the invention, the preparation method of the phenolic resin includes: reacting raw materials containing phenol and formaldehyde under alkaline conditions at 40-90°C for 2-6 hours. For example, the reaction temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or any combination of two of the above values; the reaction time can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or any combination of two of the above values. The molar ratio of phenol to formaldehyde is 1:1.5-3, for example, 1:1.5, 1:2, 1:2.5, 1:3, or any combination of two of the above values. The polymer prepared using the aforementioned technical solution will not spread excessively at high temperatures or shrink excessively under high salinity, exhibiting excellent temperature and salt resistance. It also demonstrates good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0063] Specifically, for example, the steps for preparing phenolic resin include: first, weighing phenol and stirring it at 40-60℃ to remove oxygen, then adding sodium hydroxide solution dropwise and mixing well, then adding the required amount of formaldehyde solution (the molar ratio of phenol to formaldehyde is 1:1.5-3) dropwise at a temperature of 40-90℃ and mixing well, and reacting under nitrogen conditions for 2-6 hours.

[0064] In this invention, any polymer skeleton possessing the aforementioned technical features can achieve the objective of this invention during the polymer preparation process. There are no special requirements for the preparation method of the polymer skeleton; the following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the preparation method of the polymer skeleton includes: copolymerizing a nonionic monomer, an anionic monomer, and a phenolic resin to obtain a first polymer; then forming a first polymer dispersion from the first polymer and performing freeze-drying. The freeze-drying step can be a conventional step in the art, such as pre-freezing in liquid nitrogen followed by freeze-drying.

[0065] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the range of types of nonionic monomers, anionic monomers, and phenolic resins that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the nonionic monomer used is selected from one or more of acrylamide, N-hydroxymethylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, vinylpyrrolidone, and vinylcaprolactam.

[0066] According to a preferred embodiment of the present invention, the anionic monomer used is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid and sodium styrene sulfonate.

[0067] According to a preferred embodiment of the present invention, the phenolic resin used is a water-soluble phenolic resin, wherein the phenolic resin contains structural units shown in formula (C) and optionally structural units shown in formula (D):

[0068] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resins to obtain the first polymer, any phenolic resin having the aforementioned structure can achieve the purpose of this invention. The number-average molecular weight of the phenolic resin can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the number-average molecular weight of the phenolic resin is 500-1200 g / mol.

[0069] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, any phenolic resin with the aforementioned technical characteristics can be used in this invention. There are no special requirements for the preparation method of the phenolic resin. One embodiment is illustrated, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the preparation method of the phenolic resin includes: reacting raw materials containing phenol and formaldehyde at 40-90°C for 2-6 hours in the presence of an alkaline environment, wherein the molar ratio of phenol to formaldehyde is 1:1.5-3.

[0070] Specifically, for example, the steps for preparing phenolic resin include: first, weighing phenol and stirring it at 40-60℃ to remove oxygen, then adding sodium hydroxide solution dropwise and mixing well, then adding the required amount of formaldehyde solution (the molar ratio of phenol to formaldehyde is 1:1.5-3) dropwise at a temperature of 40-90℃ and mixing well, and reacting under nitrogen conditions for 2-6 hours.

[0071] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the range of selectable amounts of the nonionic monomers, anionic monomers, and phenolic resins is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the mass ratio of the nonionic monomer to the anionic monomer is 1:0.2-1, for example, it can be 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, or any two of the above values.

[0072] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, according to a preferred embodiment of the invention, the mass ratio of the total mass of the nonionic monomers and the anionic monomers to the mass of the phenolic resin is 1:0.2-0.5, for example, it can be 1:0.2, 1:0.3, 1:0.4, 1:0.5, or any two of the above values.

[0073] Those skilled in the art will understand that in the process of copolymerizing nonionic monomers, anionic monomers and phenolic resins to obtain the first polymer, commonly used materials known to those skilled in the art can be used. For example, the copolymerization can be carried out in the presence of raw materials such as initiator 2 and crosslinking agent 2. There are no special requirements for the type and amount of raw materials such as initiator 2 and crosslinking agent 2. The following is an illustrative description, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the crosslinking agent 2 is selected from one or more of N,N-methylenebisacrylamide, ethylene glycol diacrylate and polyethyleneimine.

[0074] In the process of copolymerizing nonionic monomers, anionic monomers and phenolic resins to obtain the first polymer, according to a preferred embodiment of the present invention, the initiator 2 is selected from one or more of potassium persulfate and ammonium persulfate.

[0075] In the process of copolymerizing nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, according to a preferred embodiment of the present invention, the mass ratio of the total mass of the nonionic monomers, the anionic monomers, and the phenolic resin to the mass ratio of the crosslinking agent 2 is 1:0.001-0.02, for example, it can be 1:0.001, 1:0.005, 1:0.01, 1:0.015, 1:0.02, or any two of the above values.

[0076] Those skilled in the art will know that the copolymerization of nonionic monomers, anionic monomers and phenolic resin to obtain the first polymer is generally carried out in the presence of a solvent. There are no special requirements for the choice of solvent. Those skilled in the art can make conventional selections based on the raw materials and conditions of copolymerization. For example, in this invention, the solvent can be water, etc.

[0077] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, there are no special requirements for the amount of solvent used. Those skilled in the art can make conventional selections based on the raw materials and copolymerization conditions of the copolymerization reaction. For example, the amount of solute can be adjusted. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the mass ratio of the total mass of the nonionic monomer, the anionic monomer, the phenolic resin, and the crosslinking agent 2 to the mass of the solvent is 1:5-10, such as 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or any two of the above values.

[0078] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, there are no special requirements for the amount of initiator 2. For example, it can be adjusted according to the amount of solvent. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the mass ratio of solvent to initiator 2 is 1:0.0005-0.001, for example, it can be 1:0.0005, 1:0.0007, 1:0.0009, 1:0.001, or any two of the above values.

[0079] In this invention, there are no special requirements for the copolymerization conditions during the copolymerization process of nonionic monomers, anionic monomers and phenolic resins to obtain the first polymer. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the copolymerization temperature is 60-70°C.

[0080] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the copolymerization time is generally adjusted according to the copolymerization temperature, etc., and the range of selectable copolymerization time is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. For example, the copolymerization time is 2-3 hours.

[0081] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the copolymerization is usually carried out under alkaline conditions. The range of alkaline conditions that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pH of the copolymerization is 9-11.

[0082] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the copolymerization can be carried out in an inert gas. The range of inert gases that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. For example, the inert gas is nitrogen.

[0083] In this invention, during the copolymerization of nonionic monomers, anionic monomers, and phenolic resin to obtain the first polymer, the copolymerization can be carried out dynamically. The rotation speed is generally adjusted according to the copolymerization temperature, time, etc., and the range of selectable rotation speed is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the rotation speed is 400-600 rpm.

[0084] Those skilled in the art will know that in the process of copolymerizing nonionic monomers, anionic monomers and phenolic resin to obtain the first polymer, the product is generally filtered and washed with an organic solvent such as anhydrous ethanol after copolymerization, mainly to remove the reaction solvent, etc., and then dried and pulverized to obtain the first polymer. This operation is conventional prior art and will not be described in detail in this invention.

[0085] In this invention, during the freeze-drying process after the first polymer forms a first polymer dispersion,

[0086] There are no special requirements for the freeze-drying conditions. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the freeze-drying conditions include: the solvent of the first polymer dispersion includes alcohol and water, wherein the alcohol is selected from one or more of tert-butanol, ethanol, methanol, and propanol, and the mass ratio of alcohol to water is 1:1-5, for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, or any two of the above values.

[0087] According to a preferred embodiment of the present invention, the freeze-drying conditions include: in the first polymer dispersion, the mass ratio of solvent to the first polymer is 1:0.01-0.05, for example, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, or any two of the above values.

[0088] According to a preferred embodiment of the present invention, the freeze-drying conditions include: pre-freezing in liquid nitrogen for 0.5-2.5 hours.

[0089] According to a preferred embodiment of the present invention, the freeze-drying conditions include a freeze-drying temperature of -60 to -80°C.

[0090] According to a preferred embodiment of the present invention, the freeze-drying conditions include a freeze-drying pressure of 0.5-1.5 Pa.

[0091] In this invention, as long as the first polymer dispersion can be freeze-dried, there are no special requirements for the freeze-drying time. It is generally selected based on the freeze-drying temperature and pressure, for example, the freeze-drying time is 36-60 hours.

[0092] According to a preferred embodiment of the present invention, the freeze-drying conditions include: the solvent of the first polymer dispersion includes tert-butanol, ethanol and water, and the mass ratio of tert-butanol, ethanol and water is 1:1-2 (for example, it can be 1, 1.2, 1.4, 1.6, 1.8, 2, or any two of the above values):7-8 (for example, it can be 7, 7.2, 7.4, 7.6, 7.8, 8, or any two of the above values).

[0093] According to a preferred embodiment of the present invention, the freeze-drying conditions include: in the first polymer dispersion, the mass ratio of solvent to the first polymer is 1:0.01-0.02, for example, 1:0.01, 1:0.015, 1:0.02, or any two of the above values. The polymer prepared using the aforementioned technical solution exhibits excellent temperature and salt resistance, without excessive spreading at high temperatures or excessive shrinkage under high salinity, and good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer effectively reduces filtration loss, optimizes lubrication, and enhances suspension.

[0094] This invention provides polymers prepared by the method described herein.

[0095] In this invention, the polymers prepared by the aforementioned methods can all achieve the purpose of this invention. There are no special requirements for the physicochemical properties of the polymers. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the polymer has an approximately spherical morphology, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface and no obvious filamentous or porous structure.

[0096] According to one embodiment of the present invention, the number average molecular weight of the polymer is 30,000-200,000 g / mol, for example, it can be 30,000 g / mol, 50,000 g / mol, 80,000 g / mol, 100,000 g / mol, 120,000 g / mol, 150,000 g / mol, 180,000 g / mol, 200,000 g / mol, or any two of the above values.

[0097] According to a preferred embodiment of the present invention, the average particle size of the polymer in the dry state is 200-300 μm, for example, it can be 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, or any combination of two of the above values.

[0098] According to a preferred embodiment of the present invention, the hydration kinetic particle size distribution of the polymer in water at 10-40°C ranges from 100-400 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, or any combination of the above values, and the average particle size is 200-300 μm, for example, 200 μm, 230 μm, 260 μm, 290 μm, 300 μm, or any combination of the above values.

[0099] According to a preferred embodiment of the present invention, the hydration kinetic particle size distribution of the polymer in water at 150-250°C ranges from 100-500 μm, for example, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, or any combination of the above values, and the average particle size is 200-300 μm, for example, 200 μm, 230 μm, 260 μm, 290 μm, 300 μm, or any combination of the above values.

[0100] According to a preferred embodiment of the present invention, the hydration kinetic particle size distribution of the polymer in brine at 150-250°C and 200,000-400,000 mg / L is 100-400 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, or any combination of the above values; the average particle size is 200-300 μm, for example, 200 μm, 230 μm, 260 μm, 290 μm, 300 μm, or any combination of the above values. The polymer possessing the aforementioned physicochemical properties does not excessively spread at high temperatures or excessively shrink under high salinity, exhibiting excellent temperature and salt resistance, and good dispersion stability in high-temperature water / salt water. When applied to drilling fluids and / or completion fluids, this polymer provides excellent effects in reducing filtration loss, optimizing lubrication, and enhancing suspension.

[0101] This invention provides the application of the polymer described herein in drilling fluids and / or completion fluids.

[0102] The polymer described in this invention is particularly suitable for use in water-based drilling fluids.

[0103] The present invention will be described in detail below through embodiments.

[0104] In the following examples and comparative examples:

[0105] Scanning electron microscope (SEM) images of the polymer and skeleton were obtained using a FEI Quanta 200F SEM. Before measurement, the sample surface was coated with gold.

[0106] The average particle size of the polymer in its dry state was measured using a scanning electron microscope.

[0107] The number-average molecular weights of the polymer, backbone, and phenolic resin were determined using an integrated gel permeation chromatograph, specifically with tetrahydrofuran as the eluent and a flow rate of 1.0 mL / min.

[0108] The scanning electron microscopy-Raman spectroscopy (SEM-Raman spectroscopy) characterization method for polymers involves examining their microstructure in the SEM field of view, selecting the region to be analyzed, performing Raman scanning on the corresponding region, and outputting the Raman spectrum of the corresponding region.

[0109] The hydration kinetics particle size distribution of the polymer was obtained using a dynamic light scattering (DLS) instrument. Specifically, a Hosic (Germany) ALV / DLS / SLS-5022F DLS instrument was used, with the sample cell type selected as "Glass" and water selected as the solvent. A 0.05% (w / w) sample solution was injected into the sample cell, and the correlation function of the scattering data was analyzed using the CONTIN method to obtain the particle size distribution information of the sample.

[0110] The method for testing the dispersion stability of the polymer is as follows: The TSI stability index of the sample is determined using a Formulaction TurbiScan Lab Expert stability analyzer (France) to characterize the dispersion stability of the sample. 5g of polymer is mixed with 500mL of deionized water, and 5g of polymer gel is mixed with 500mL of water containing a mineralization of 100,000 mg / L (including Ca2+). 2+ Mg 2+ The concentration of divalent ions was 16000 mg / L, and the concentration was 200000 mg / L (including Ca). 2+ Mg 2+ The concentration of divalent ions was 33,000 mg / L, and the concentration was 300,000 mg / L (including Ca). 2+ Mg 2+ The content of divalent ions was 50000 mg / L. The polymer gel-deionized water and polymer gel-salt were mixed and injected into the high temperature and high pressure sample cell, respectively. The temperature was set at 200℃ and the test time lasted for 12000 minutes.

[0111] The rheological properties, filtration loss reduction properties, and lubrication properties of the polymer were tested and evaluated according to the methods in the national standard GB / T 29170-2012, with the experimental temperature set at 200℃ and hot rolling for 16 hours. The mass of polymer added was calculated as a percentage of the water volume. The preparation method for the water-based drilling fluid was as follows: based on a water volume of 100 mL, 2.0 g of bentonite, 10.0 g of potassium chloride, 20.0 g of sodium chloride, 30.0 g of type I organic salt, and 76.7 g of barite were added to form the water-based drilling fluid.

[0112] The synthesis conditions for the water-soluble phenolic resin were as follows: a molar ratio of phenol to formaldehyde of 1:2, a reaction temperature of 75℃, and a reaction time of 4 hours. The specific steps were as follows: Phenol was pre-melted in water at 50℃ in a sealed container. Deionized water was prepared, and a 20% sodium hydroxide solution was prepared. First, the required mass of phenol was weighed into a 250mL four-necked flask according to the desired ratio. The flask was stirred and deoxygenated at 50℃ for 20 minutes. Then, the sodium hydroxide solution was added dropwise to the four-necked flask, and the mixture was stirred for another 20 minutes. The temperature was then set to 75℃. After the temperature stabilized, the required mass of formaldehyde solution was weighed at a molar ratio of phenol to formaldehyde of 1:2 and added dropwise to the four-necked flask at a uniform rate using a constant-pressure dropping funnel. Nitrogen gas was maintained throughout the reaction, and the reaction was allowed to proceed for 4 hours to obtain the phenolic resin. The number-average molecular weight of the obtained phenolic resin was 816 g / mol.

[0113] Preparation Example 1

[0114] 8.0 g acrylamide, 2.0 g vinylpyrrolidone, 5 g 2-acrylamido-2-methylpropanesulfonic acid, 5 g water-soluble phenolic resin, 0.1 g N,N-methylenebisacrylamide, and 0.15 g polyethyleneimine were sequentially dispersed in 200 mL of deionized water. The mixture was stirred in an ice-water bath at 5-10 °C at a stirring speed of 100 rpm. After uniform dispersion, the solution was added to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer. Nitrogen gas was purged for 30 min, the pH was maintained at 10, and the temperature was maintained at 65 °C. Then, 0.15 g potassium persulfate was added, and the stirring speed was set to 500 rpm. The reaction was allowed to proceed for 3 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized to obtain the polymer.

[0115] The 15g polymer obtained above was dispersed in a 1000g mixed solution of tert-butanol / ethanol / deionized water, wherein the mass of tert-butanol in the mixed solution was 100g, the mass of ethanol was 200g, and the mass of deionized water was 700g. After being evenly dispersed, the polymer was frozen in liquid nitrogen for 60min and then freeze-dried at -80℃ and 1Pa for 48h. After being restored to room temperature and normal pressure, the polymer skeleton was obtained.

[0116] The scanning electron microscope image of the obtained skeleton is shown in Figure 2. As can be seen from the figure, it has an intertwined and interwoven filamentous structure with pores between the filaments. The pores are widely distributed, and the filaments and pores form a network. The number average molecular weight of the obtained skeleton is measured to be 12,300-24,800 g / mol.

[0117] Preparation Example 2

[0118] 5.0g acrylamide, 1.0g N-hydroxymethylacrylamide, 1.0g N-ethylacrylamide, 1.0g N-isopropylacrylamide, 1.0g vinylpyrrolidone, 1.0g vinylcaprolactam, 1g 2-acrylamido-2-methylpropanesulfonic acid, 1g sodium styrene sulfonate, 2.4g water-soluble phenolic resin, 0.05g N,N-methylenebisacrylamide, and 0.002g polyethyleneimine were sequentially dispersed in 73mL of deionized water. The mixture was stirred in an ice-water bath at a temperature controlled at 5-10℃ and a stirring speed of 100rpm. After the mixture is evenly dispersed, it is added to a three-necked glass bottle equipped with a stirrer, a nitrogen purging tube and a thermometer. Nitrogen gas is purged for 30 minutes, the pH is controlled at 9 and the temperature is controlled at 65℃. Then, 0.025g of potassium persulfate and 0.015g of ammonium persulfate are added. The stirring speed is set to 400rpm and the reaction is carried out for 2 hours. After cooling to room temperature, the product is filtered and washed with anhydrous ethanol. After drying and pulverizing, the polymer is obtained.

[0119] The 10g polymer obtained above was dispersed in a 1000g mixed solution of tert-butanol / ethanol / deionized water, wherein the mass of tert-butanol in the mixed solution was 100g, the mass of ethanol was 100g, and the mass of deionized water was 800g. After being evenly dispersed, the polymer was placed in liquid nitrogen and frozen for 60min, and then freeze-dried at -80℃ and 1Pa for 48h. After drying, the polymer skeleton was obtained by restoring it to room temperature and normal pressure.

[0120] The scanning electron microscope image of the obtained skeleton is shown in Figure 3. As can be seen from the figure, it has an intertwined and interwoven filamentous structure with pores between the filaments. The pores are widely distributed, and the filaments and pores form a network. The number average molecular weight of the obtained skeleton is measured to be 0.81 million to 1.35 million g / mol.

[0121] Preparation Example 3

[0122] 8.0 g acrylamide, 2.0 g vinylpyrrolidone, 5 g 2-acrylamido-2-methylpropanesulfonic acid, 5 g sodium styrene sulfonate, 10 g water-soluble phenolic resin, 0.2 g N,N-methylenebisacrylamide, and 0.1 g polyethyleneimine were sequentially dispersed in 300 mL of deionized water. The mixture was stirred in an ice-water bath at 5-10 °C at a stirring speed of 100 rpm. After uniform dispersion, the solution was added to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer. Nitrogen gas was purged for 30 min, the pH was maintained at 11, and the temperature was maintained at 65 °C. Then, 0.3 g potassium persulfate was added, and the stirring speed was set to 600 rpm. The reaction was allowed to proceed for 3 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized to obtain the polymer.

[0123] The 20g polymer obtained above was dispersed in a 1000g mixed solution of tert-butanol / ethanol / deionized water, wherein the mass of tert-butanol in the mixed solution was 100g, the mass of ethanol was 100g, and the mass of deionized water was 800g. After being evenly dispersed, the polymer was frozen in liquid nitrogen for 60min and then freeze-dried at -80℃ and 1Pa for 48h. After being restored to room temperature and normal pressure, the polymer skeleton was obtained.

[0124] The scanning electron microscope image of the obtained skeleton is shown in Figure 4. As can be seen from the figure, it has an intertwined and interwoven filamentous structure with pores between the filaments. The pores are widely distributed, and the filaments and pores form a network. The number average molecular weight of the obtained skeleton is measured to be 21,200-38,800 g / mol.

[0125] Preparation Example 4

[0126] 8.0 g acrylamide, 2.0 g vinylpyrrolidone, 5 g 2-acrylamido-2-methylpropanesulfonic acid, 5 g water-soluble phenolic resin, 0.1 g N,N-methylenebisacrylamide, and 0.15 g polyethyleneimine were sequentially dispersed in 200 mL of deionized water. The mixture was stirred in an ice-water bath at 5-10 °C at a stirring speed of 100 rpm. After uniform dispersion, the solution was added to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer. Nitrogen gas was purged for 30 min, the pH was maintained at 10, and the temperature was maintained at 65 °C. Then, 0.15 g potassium persulfate was added, and the stirring speed was set to 500 rpm. The reaction was allowed to proceed for 3 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized to obtain the polymer.

[0127] The 15g polymer obtained above was dispersed in a 1000g mixed solution of tert-butanol / ethanol / deionized water, wherein the mass of tert-butanol in the mixed solution was 100g, the mass of ethanol was 200g, and the mass of deionized water was 700g. After being dispersed evenly, the polymer was placed in a -80℃ freezer for 60min and then freeze-dried: the temperature was set at -80℃ and the pressure was set at 1Pa. After drying for 48h, the polymer skeleton was obtained by restoring it to room temperature and normal pressure.

[0128] The scanning electron microscope image of the obtained skeleton is shown in Figure 5. As can be seen from the figure, it is a dense blocky structure, without intertwined filamentous structures or porous structures, and does not form a network. The number-average molecular weight of the obtained skeleton is measured to be 12,000-25,100 g / mol.

[0129] Preparation Example 5

[0130] 8.0 g acrylamide, 2.0 g vinylpyrrolidone, 5 g 2-acrylamido-2-methylpropanesulfonic acid, 1.5 g water-soluble phenolic resin, 0.1 g N,N-methylenebisacrylamide, and 0.15 g polyethyleneimine were sequentially dispersed in 200 mL of deionized water. The mixture was stirred in an ice-water bath at 5-10 °C at a stirring speed of 100 rpm. After uniform dispersion, the solution was added to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer. Nitrogen gas was purged for 30 min, the pH was maintained at 10, and the temperature was maintained at 65 °C. Then, 0.15 g potassium persulfate was added, and the stirring speed was set to 500 rpm. The reaction was allowed to proceed for 3 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized to obtain the polymer.

[0131] The 15g polymer obtained above was dispersed in a 1000g mixed solution of tert-butanol / ethanol / deionized water, wherein the mass of tert-butanol in the mixed solution was 100g, the mass of ethanol was 200g, and the mass of deionized water was 700g. After being evenly dispersed, the polymer was frozen in liquid nitrogen for 60min and then freeze-dried at -80℃ and 1Pa for 48h. After being restored to room temperature and normal pressure, the polymer skeleton was obtained.

[0132] The scanning electron microscope image of the obtained skeleton is similar to that of Preparation Example 1, showing an intertwined and interwoven filamentous structure with widely distributed pores, forming a network. The number-average molecular weight of the obtained skeleton was measured to be 0.96 million to 2.13 million g / mol.

[0133] Example 1

[0134] The polymer backbone from Preparation Example 1 was used as a raw material.

[0135] Disperse 10.0g of polymer backbone and 0.8g of sodium dodecyl sulfate in 80mL of deionized water, maintaining the temperature at 20-25℃ and stirring at 50rpm. After uniform dispersion, add the mixture to a three-necked glass flask equipped with a stirrer, nitrogen purging tube, and thermometer, and increase the stirring speed to 100rpm. 2.0 g butyl methacrylate, 2.0 g hexyl methacrylate, 3.0 g lauryl methacrylate, 1.0 g 3,4,5-tris(n-hexanemethoxy)styrene, 1.0 g 3,4,5-tris(n-octanemethoxy)styrene, 1.0 g 3,4,5-tris(dodecanemethoxy)styrene, 1.0 g ethylene glycol dimethacrylate, and 1.0 g divinylbenzene were sequentially added to a three-necked glass flask. Nitrogen gas was bubbled through the flask for 30 min, the pH was controlled at 11, and the temperature was controlled at 50 °C. Then, 0.20 g azobisisobutyronitrile and 0.10 g dimethyl azobisisobutyrate were added. The stirring speed was set to 700 rpm, and the reaction was carried out for 6 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized.

[0136] The scanning electron microscope image of the obtained polymer is shown in Figure 6. As can be seen from the figure, its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains. The surface is rough and dense, with no obvious filamentous or porous structures. The average particle size of the obtained polymer in its dry state is approximately 256.3 μm, and the number-average molecular weight is 72,800–111,200 g / mol.

[0137] The structure and composition of the prepared polymer were characterized by scanning electron microscopy-Raman spectroscopy, as shown in Figure 7. Regions 1 and 2, two intertwined parts, were selected in the scanning electron microscope field of view. Figures 8 and 9 show the Raman spectra of regions 1 and 2, respectively. The figures show that the Raman spectrum of region 1 is in the range of 3163-3583 cm⁻¹. -1 The presence of strong peaks within the range indicates the presence of numerous polar groups in the polymer of region 1, suggesting that the polymer in region 1 is primarily a network polymer skeleton; the Raman spectrum of region 2 is between 3163 and 3583 cm⁻¹. -1 The absence of obvious absorption peaks within the range indicates that the polymer in region 2 is essentially devoid of polar groups, instead consisting mainly of long hydrocarbon chains and nonpolar groups. This suggests that the polymer in region 2 is primarily another type of polymer. This further confirms that the obtained polymer is in the form of multiple interwoven and entangled molecular chains.

[0138] Hydration kinetics and particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature:

[0139] (1) The hydration kinetic particle size distribution of the obtained polymer in room temperature and deionized water is shown in Figure 10. As can be seen from the figure, the hydration kinetic particle size distribution range in room temperature and deionized water is 170.2 to 310.9 μm, and the average particle size is 227.3 μm, indicating that it can be effectively dispersed in room temperature and deionized water.

[0140] (2) The hydration kinetic particle size distribution of the obtained polymer in deionized water at 200℃ is shown in Figure 11. As can be seen from the figure, in deionized water at 200℃, its hydration kinetic particle size distribution range is 123.1~398.6μm, and the average particle size is 232.9μm, indicating that it can be effectively dispersed in deionized water at 200℃.

[0141] (3) The obtained polymer was tested at 200℃ with a mineralization of 300,000 mg / L (including Ca). 2+ Mg 2+ Figure 12 shows the hydration kinetics particle size distribution in brine with a divalent ion content of 50,000 mg / L. As can be seen from the figure, at 200℃ and a mineralization of 300,000 mg / L (including Ca²⁺ and Mg²⁺), the hydration kinetics particle size distribution is optimal. 2+ Mg 2+ In a solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution ranged from 160.8 to 281.3 μm, with an average particle size of 213.6 μm, indicating that it can be absorbed at 200℃ and a mineralization of 300,000 mg / L (including Ca). 2+ Mg 2+ The content of divalent ions (e.g., 50000 mg / L) is effectively dispersed in saline solution;

[0142] Therefore, the dispersion state of the obtained polymer in high temperature and high salt is similar to that in room temperature and deionized water. Its tendency to spread outward when heated and shrink inward when exposed to salt is not obvious, and it has significant advantages in temperature and salt resistance.

[0143] By comparing the TSI stability index of the polymer obtained in this invention with that of commercially available drilling fluid polymer treatment agents SO-1 (Shandong Deshunyuan Company) and Redu200 (Beijing Peikang Company) in high-temperature water / salt water, the dispersion stability of the obtained polymer in high-temperature and high-salt environments was further evaluated. The results are shown in Figure 13. As can be seen from the figure: First, in deionized water at 200℃, the TSI value of the polymer of this invention remained stable for more than 10,000 minutes, with the curve remaining horizontal. The TSI value was 2.12 at 10,800 minutes, indicating that the polymer maintained good dispersion stability in deionized water at 200℃. Second, at 200℃ and 100,000 mg / L (including Ca2+), the dispersion stability of the polymer was significantly improved. 2+ Mg 2+ The concentration of divalent ions was 16000 mg / L, and the concentration was 200000 mg / L (including Ca). 2+ Mg 2+ The concentration of divalent ions was 33,000 mg / L, and the concentration was 300,000 mg / L (including Ca). 2+ Mg 2+ In a saline solution containing 50,000 mg / L of divalent ions, the TSI stability index of the polymer obtained in this invention slowly increased over time. This indicates that in high-temperature and high-salt environments, the stability of the polymer obtained in this invention is slightly lower than that in deionized water at 200°C. Simultaneously, the TSI value of the polymer obtained in this invention also increases with increasing mineralization. Specifically, at 10800 min, the polymer obtained in this invention showed a higher TSI value at 200°C and 100,000 mg / L of divalent ions (including Ca²⁺). 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 3.64 at 200℃ and 200000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) is 8.51, and it remains stable at 200℃ and 300,000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in the brine (containing 50,000 mg / L of divalent ions) was 13.82; this indicates that the mineralization degree had an adverse effect on the dispersion stability of the polymer obtained in this invention, especially Ca. 2+ / Mg 2+The presence of divalent ions can cause excessive shrinkage of the polymer, leading to loss of dispersibility and sedimentation; third, comparative analysis revealed that the polymer obtained in this invention exhibits better performance at concentrations of 300,000 mg / L (including Ca). 2+ Mg 2+ The dispersion stability of the polymer obtained in this invention in brine (containing 50,000 mg / L of divalent ions) is significantly better than that of commercially available drilling fluid polymer treatment agents SO-1 (Shandong Deshunyuan Company) and Redu200 (Beijing Peikang Company); this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0144] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the obtained polymer are shown in Table 1.

[0145] Example 2

[0146] The polymer backbone of Preparation Example 2 was used as the raw material;

[0147] Disperse 10.0g of the network polymer backbone and 0.15g of sodium dodecyl sulfate in 32mL of deionized water, maintaining the temperature at 20-25℃ and stirring at 50rpm. After uniform dispersion, add the mixture to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer, and increase the stirring speed to 100rpm. 1.0 g butyl methacrylate, 1.0 g hexyl methacrylate, 1.5 g lauryl methacrylate, 0.5 g 3,4,5-tris(n-hexanemethoxy)styrene, 0.5 g 3,4,5-tris(n-octanemethoxy)styrene, 0.5 g 3,4,5-tris(dodecanemethoxy)styrene, 0.5 g ethylene glycol dimethacrylate, and 0.26 g divinylbenzene were sequentially added to a three-necked glass flask. Nitrogen gas was purged for 30 min, the pH was controlled at 10, and the temperature was controlled at 40℃. Then, 0.04 g azobisisobutyronitrile was added, the stirring speed was set to 600 rpm, and the reaction was carried out for 5 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized.

[0148] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 281.5 μm, and the number-average molecular weight was 52,100-93,100 g / mol.

[0149] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0150] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0151] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 159.6 to 331.2 μm, with an average particle size of 242.3 μm, indicating that it can be effectively dispersed in room temperature and deionized water.

[0152] (2) At 200℃ in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 110.8 to 421.5 μm, with an average particle size of 256.4 μm, indicating that it can be effectively dispersed in deionized water at 200℃.

[0153] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+ In a saline solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 149.7 to 361.2 μm, with an average particle size of 249.6 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca²⁺ and Mg²⁺). 2+ Mg 2+ The content of divalent ions (e.g., 50000 mg / L) is effectively dispersed in saline solution;

[0154] Therefore, the dispersion state of the obtained polymer in high temperature and high salt is similar to that in room temperature and deionized water. Its tendency to spread outward when heated and shrink inward when exposed to salt is not obvious, and it has significant advantages in temperature and salt resistance.

[0155] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0156] The obtained polymer had a TSI value of 2.06 in deionized water at 200°C and 100,000 mg / L (containing Ca) at 200°C and 10800 min. 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 3.71. At 200℃ and 200000 mg / L (including Ca2+), the TSI stability index is [missing value]. 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) is 8.43, and it remains stable at 200℃ and 300,000 mg / L (including Ca). 2+ Mg 2+The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 14.21; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0157] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the obtained polymer are shown in Table 2.

[0158] Example 3

[0159] The polymer backbone of Preparation Example 3 was used as a raw material;

[0160] 10.0 g of the network polymer backbone and 1.5 g of sodium dodecyl sulfate were dispersed in 180 mL of deionized water. The temperature was controlled at 20-25 °C, and the stirring speed was maintained at 50 rpm. After uniform dispersion, the mixed solution was added to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer, and the stirring speed was increased to 100 rpm. 4.0 g of butyl methacrylate, 10.0 g of lauryl methacrylate, 3.0 g of 3,4,5-tris(n-hexanemethoxy)styrene, 3.0 g of 3,4,5-tris(n-octanemethoxy)styrene, 3.0 g of ethylene glycol dimethacrylate, and 3.0 g of divinylbenzene were added sequentially to the three-necked glass flask. Nitrogen gas was purged for 30 min, the pH was controlled at 12, and the temperature was controlled at 60 °C. Then, 0.9 g of dimethyl azobisisobutyrate was added, the stirring speed was set to 800 rpm, and the reaction was carried out for 8 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized.

[0161] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 267.2 μm, and the number-average molecular weight was 110,300-152,100 g / mol.

[0162] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0163] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0164] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 144.7 to 317.6 μm, with an average particle size of 227.6 μm, indicating that it can be effectively dispersed in room temperature and deionized water.

[0165] (2) At 200℃ in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 126.8 to 431.5 μm, with an average particle size of 266.3 μm, indicating that it can be effectively dispersed in deionized water at 200℃.

[0166] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+ In a saline solution containing 50,000 mg / L of divalent ions, the hydration kinetics particle size distribution of the obtained polymer ranged from 155.6 to 377.9 μm, with an average particle size of 247.8 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca²⁺ and Mg²⁺). 2+ Mg 2+ The content of divalent ions (e.g., 50000 mg / L) is effectively dispersed in saline solution;

[0167] Therefore, the dispersion state of the obtained polymer in high temperature and high salt is similar to that in room temperature and deionized water. Its tendency to spread outward when heated and shrink inward when exposed to salt is not obvious, and it has significant advantages in temperature and salt resistance.

[0168] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0169] The obtained polymer had a TSI value of 2.11 at 200°C and 100,000 mg / L (containing Ca) at 10800 min and 200°C. 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 3.64 at 200℃ and 200000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) is 8.57, and it remains stable at 200℃ and 300,000 mg / L (including Ca2+). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 13.83; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0170] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the obtained polymer are shown in Table 3.

[0171] Example 4

[0172] The method is the same as in Example 1, except that the amount of sodium dodecyl sulfate used is 1.2g, while the other raw materials and methods are the same.

[0173] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 238.2 μm, and the number-average molecular weight was 68,900-122,100 g / mol.

[0174] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0175] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0176] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranges from 101.2 to 252.3 μm, with an average particle size of 177.6 μm, indicating that it can be effectively dispersed in room temperature and deionized water; compared with Example 1, its dispersion degree is increased.

[0177] (2) At 200°C in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 53.2 to 265.6 μm, with an average particle size of 159.8 μm, indicating that it could be effectively dispersed at 200°C in deionized water; compared with Example 1, its dispersion degree increased.

[0178] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+ In a saline solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 79.3 to 175.1 μm, with an average particle size of 125.3 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca2+). 2+ Mg 2+ The divalent ions (containing 50,000 mg / L of divalent ions) were effectively dispersed in saline solution; compared to Example 1, a slight shrinkage phenomenon occurred.

[0179] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0180] The obtained polymer had a TSI value of 3.12 at 200°C and 100,000 mg / L (containing Ca) at 10800 min and 200°C.2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 4.36. At 200℃ and 200000 mg / L (including Ca2+), the TSI stability index is [missing value]. 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) is 9.25 at 200℃ and 300,000 mg / L (including Ca2+). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 15.96; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0181] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the prepared polymer are shown in Table 4.

[0182] Example 5

[0183] The method is the same as in Example 1, except that the amount of sodium dodecyl sulfate used is 0.1g, while the other raw materials and methods are the same.

[0184] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 241.5 μm, and the number-average molecular weight was 41,100-64,900 g / mol.

[0185] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0186] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0187] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 70.2 to 241.1 μm, with an average particle size of 156.6 μm, indicating that it could be effectively dispersed in room temperature and deionized water; compared with Example 1, its dispersion degree increased.

[0188] (2) At 200°C in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 37.3 to 290.2 μm, with an average particle size of 163.7 μm, indicating that it could be effectively dispersed in deionized water at 200°C; compared with Example 1, its dispersion degree increased.

[0189] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+ In a brine solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 66.2 to 175.1 μm, with an average particle size of 121.6 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca²⁺ and Mg²⁺). 2+ Mg 2+ The divalent ions (containing 50,000 mg / L of divalent ions) were effectively dispersed in saline solution; compared to Example 1, a slight shrinkage phenomenon occurred.

[0190] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0191] The obtained polymer had a TSI value of 3.36 in deionized water at 200°C and 100,000 mg / L (containing Ca) at 200°C and 10800 min. 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 4.58. At 200℃ and 200000 mg / L (including Ca2+), the TSI stability index is [missing value]. 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) is 9.63 at 200℃ and 300,000 mg / L (including Ca2+). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 15.71; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0192] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the prepared polymer are shown in Table 5.

[0193] Example 6

[0194] The method is the same as in Example 1, except that the mass of ethylene glycol dimethacrylate is 0.4 g and the mass of divinylbenzene is 0.4 g, while the other raw materials and methods are the same.

[0195] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 252.3 μm, and the number-average molecular weight was 49,100-73,100 g / mol.

[0196] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0197] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0198] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranges from 126.1 to 281.6 μm, with an average particle size of 203.5 μm, indicating that it can be effectively dispersed in room temperature and deionized water; compared with Example 1, its dispersion degree is increased.

[0199] (2) At 200°C in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 70.3 to 320.1 μm, with an average particle size of 196.4 μm, indicating that it could be effectively dispersed in deionized water at 200°C; compared with Example 1, its dispersion degree increased.

[0200] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+ In a brine solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 95.4 to 240.9 μm, with an average particle size of 167.8 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca2+). 2+ Mg 2+ The divalent ions (containing 50,000 mg / L of divalent ions) were effectively dispersed in saline solution; compared to Example 1, a slight shrinkage phenomenon occurred.

[0201] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0202] The obtained polymer had a TSI value of 3.42 at 200°C and 100,000 mg / L (containing Ca) at 10800 min and 200°C. 2+ Mg 2+The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 4.36. At 200℃ and 200000 mg / L (including Ca2+), the TSI stability index is [missing value]. 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) was 10.08 at 200℃ and 300,000 mg / L (including Ca2+). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 15.56; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0203] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the prepared polymer are shown in Table 6.

[0204] Example 7

[0205] The method is the same as in Example 1, except that the amount of polymer backbone is 15g, the amount of butyl methacrylate is 1g, the mass of hexyl methacrylate is 1g, the mass of lauryl methacrylate is 1.5g, the mass of 3,4,5-tris(n-hexanemethoxy)styrene is 0.5g, the mass of 3,4,5-tris(n-octanemethoxy)styrene is 0.5g, and the mass of 3,4,5-tris(dodecanemethoxy)styrene is 0.5g. All other raw materials and methods are the same.

[0206] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 241.6 μm, and the number-average molecular weight was 44,100-65,900 g / mol.

[0207] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0208] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0209] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranges from 110.2 to 285.0 μm, with an average particle size of 197.5 μm, indicating that it can be effectively dispersed in room temperature and deionized water; compared with Example 1, its dispersion degree is increased.

[0210] (2) At 200°C and in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 25.6 to 318.2 μm, with an average particle size of 171.8 μm, indicating that it could be effectively dispersed in deionized water at 200°C; compared with Example 1, its dispersion degree increased.

[0211] (3) At 300,000 mg / L (wherein, including Ca...) 2+ Mg 2+ In a saline solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 93.2 to 243.8 μm, with an average particle size of 168.8 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca2+). 2+ Mg 2+ The divalent ions (containing 50,000 mg / L of divalent ions) were effectively dispersed in saline solution; compared to Example 1, a slight shrinkage phenomenon occurred.

[0212] The TSI stability index of the obtained polymer in high-temperature water / salt water shows a similar trend to that in Example 1, wherein:

[0213] The obtained polymer had a TSI value of 3.56 in deionized water at 200°C and 100,000 mg / L (containing Ca) at 200°C and 10800 min. 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 4.63 at 200℃ and 200000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) was 10.84 at 200℃ and 300,000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) was 16.11; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0214] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the prepared polymer are shown in Table 7.

[0215] Example 8

[0216] The polymer backbone of Preparation Example 5 was used as the raw material;

[0217] Disperse 10.0g of the network polymer backbone and 0.15g of sodium dodecyl sulfate in 32mL of deionized water, maintaining the temperature at 20-25℃ and stirring at 50rpm. After uniform dispersion, add the mixture to a three-necked glass flask equipped with a stirrer, a nitrogen purging tube, and a thermometer, and increase the stirring speed to 100rpm. 1.0 g butyl methacrylate, 1.0 g hexyl methacrylate, 1.5 g lauryl methacrylate, 0.5 g 3,4,5-tris(n-hexanemethoxy)styrene, 0.5 g 3,4,5-tris(n-octanemethoxy)styrene, 0.5 g 3,4,5-tris(dodecanemethoxy)styrene, 0.5 g ethylene glycol dimethacrylate, and 0.26 g divinylbenzene were sequentially added to a three-necked glass flask. Nitrogen gas was purged for 30 min, the pH was controlled at 10, and the temperature was controlled at 40℃. Then, 0.04 g azobisisobutyronitrile was added, the stirring speed was set to 600 rpm, and the reaction was carried out for 5 h. After cooling to room temperature, the product was filtered and washed with anhydrous ethanol, dried, and pulverized.

[0218] The scanning electron microscope image of the obtained polymer is similar to that in Example 1. Its morphology is approximately spherical, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface. Testing showed that the average particle size of the obtained polymer in its dry state was approximately 249.5 μm, and the number-average molecular weight was 66,500-102,100 g / mol.

[0219] The scanning electron microscopy-Raman spectroscopy characterization results of the obtained polymer were similar to those in Example 1, which once again proved that the obtained polymer was a morphology of multiple molecular chains intertwined and entangled.

[0220] The hydration kinetics particle size distribution of the obtained polymer in water / salt solutions at room temperature / high temperature is similar to that in Example 1, wherein:

[0221] (1) In room temperature and deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 93.6 to 238.4 μm, with an average particle size of 166.3 μm, indicating that it could be effectively dispersed in room temperature and deionized water; compared with Example 1, its dispersion degree increased.

[0222] (2) At 200°C in deionized water, the hydration kinetic particle size distribution of the obtained polymer ranged from 40.3 to 274.5 μm, with an average particle size of 157.8 μm, indicating that it could be effectively dispersed in deionized water at 200°C; compared with Example 1, its dispersion degree increased.

[0223] (3) At 200℃, with a mineralization of 300,000 mg / L (including Ca... 2+ Mg 2+In a saline solution containing 50,000 mg / L of divalent ions, the hydration kinetic particle size distribution of the obtained polymer ranged from 70.2 to 158.3 μm, with an average particle size of 114.3 μm. This indicates that it can be synthesized at 200℃ and a salinity of 300,000 mg / L (including Ca2+). 2+ Mg 2+ The sample was effectively dispersed in saline solution with a divalent ion content of 50,000 mg / L; compared with Example 1, it exhibited slight shrinkage.

[0224] Therefore, the dispersion state of the obtained polymer in high temperature and high salt is similar to that in room temperature and deionized water. Its tendency to spread outward when heated and shrink inward when exposed to salt is not obvious, and it has significant advantages in temperature and salt resistance.

[0225] The TSI stability index of the obtained polymer in high-temperature water / salt water showed a similar trend to that in Example 1, wherein: the obtained polymer had a TSI value of 4.20 in deionized water at 200°C after 10800 min; and a TSI value of 100000 mg / L (containing Ca) at 200°C after 10800 min. 2+ Mg 2+ The TSI stability index in the brine (containing 16000 mg / L of divalent ions) is 5.33 at 200℃ and 200000 mg / L (including Ca). 2+ Mg 2+ The TSI stability index in the brine (containing 33,000 mg / L of divalent ions) was 12.67 at 200℃ and 300,000 mg / L (including Ca2+). 2+ Mg 2+ The TSI stability index in brine (containing 50,000 mg / L of divalent ions) is 18.06; this indicates that the polymer obtained in this invention has good dispersion stability in high-temperature water / salt water and has outstanding performance advantages in temperature and salt resistance.

[0226] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the obtained polymer are shown in Table 8.

[0227] Comparative Example 1

[0228] Same as Example 1, except that the polymer backbone of Preparation Example 4 was used as the raw material, and all other raw materials and conditions were the same.

[0229] The scanning electron microscope image of the obtained polymer is shown in Figure 14. As can be seen from the figure, it has a dense, blocky structure and does not exhibit the morphology of multiple interwoven or entangled molecular chains. The number-average molecular weight of the obtained polymer is measured to be 73,100-112,100 g / mol.

[0230] The resulting polymer could not be dispersed in deionized water and floated on the surface of the water, as shown in Figure 15. It is speculated that this is because the polymer skeleton of Preparation Example 4 does not have a network structure. During polymerization, the monomer cannot enter the interior of the polymer skeleton and can only undergo polymerization on the surface of the polymer skeleton to form a coating structure. Furthermore, due to the hydrophobicity of the monomer, the resulting polymer could not be dispersed in water and floated on the surface of the water.

[0231] The results of performance tests on the rheological properties, filtration loss reduction properties, and lubrication properties of the obtained polymer are shown in Table 9.

[0232] Table 1

[0233] Table 2

[0234] Table 3

[0235] Table 4

[0236] Table 5

[0237] Table 6

[0238] Table 7

[0239] Table 8

[0240] Table 9

[0241] As can be seen from the table, the polymer of the present invention has the characteristics of low plastic viscosity (PV), high dynamic shear force (YP), and suitable initial and final shear under high temperature and high salt conditions, exhibiting outstanding rheological and thixotropic properties. It can provide good support for the dynamic carrying of rock cuttings and static suspension of solid phases in the system, while also having excellent effects in reducing filtration loss and optimizing lubrication.

[0242] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a polymer with an interpenetrating network structure, characterized in that, The method includes: The polymer backbone is polymerized with a first monomer; wherein the polymer backbone is a network; the polymer backbone includes structural units derived from nonionic monomers, structural units derived from anionic monomers, and structural units derived from phenolic resins; the first monomer has the structure shown in formula (A): Wherein, R0 is a C4-C12 alkyl group.

2. The method according to claim 1, characterized in that, The method also includes being carried out in the presence of a second monomer having the structure shown in formula (B): Wherein, R is a C6-C12 alkyl group.

3. The method according to claim 1 or 2, characterized in that, The second monomer is selected from one or more of 3,4,5-tris(n-hexanemethoxy)styrene, 3,4,5-tris(n-octanemethoxy)styrene and 3,4,5-tris(dodecanemethoxy)styrene.

4. The method according to any one of claims 1-3, characterized in that, The polymerization temperature is 40-60℃; and / or The polymerization time is 5-8 hours; and / or The polymerization occurs at a pH of 10-12; and / or Polymerization is carried out in an inert gas; and / or The polymerization is carried out dynamically at a speed of 600-800 rpm.

5. The method according to any one of claims 1-4, characterized in that, The first monomer is selected from one or more of butyl methacrylate, hexyl methacrylate, and lauryl methacrylate; and / or The mass ratio of the polymer backbone to the total amount of added monomers is 1:0.5-2; and / or The polymerization is carried out in the presence of a solubilizer, initiator 1, and crosslinking agent 1; Preferably, the solubilizer is selected from one or more of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate; Preferably, the crosslinking agent 1 is selected from one or more of ethylene glycol dimethacrylate and divinylbenzene; Preferably, the initiator 1 is selected from one or more of azobisisobutyronitrile and dimethyl azobisisobutyrate.

6. The method according to claim 5, characterized in that, The mass ratio of the total polymer backbone, total monomers, and solubilizer is 1:0.01-0.05; and / or The mass ratio of the total amount of polymer backbone and monomers to crosslinking agent 1 is 1:0.05-0.

2.

7. The method according to any one of claims 1-6, characterized in that, The number-average molecular weight of the polymer backbone is 0.5-50,000 g / mol; and / or The mass ratio of the nonionic monomer to the anionic monomer is 1:0.2-1; and / or The total mass ratio of the nonionic monomer and the anionic monomer to the phenolic resin is 11:0.2-0.5; and / or The nonionic monomer is selected from one or more of acrylamide, N-hydroxymethylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, vinylpyrrolidone, and vinylcaprolactam; and / or The anionic monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid and sodium styrene sulfonate; and / or The phenolic resin is a water-soluble phenolic resin, and the phenolic resin contains structural units shown in formula (C) and optionally structural units shown in formula (D):

8. The method according to any one of claims 1-7, characterized in that, The number average molecular weight of the phenolic resin is 500-1200 g / mol; and / or The method for preparing the phenolic resin includes: reacting raw materials containing phenol and formaldehyde under alkaline conditions at 40-90℃ for 2-6 hours, wherein the molar ratio of phenol to formaldehyde is 1:1.5-3.

9. The method according to any one of claims 1-8, characterized in that, The method for preparing the polymer skeleton includes: copolymerizing a nonionic monomer, anionic monomer and phenolic resin to obtain a first polymer, and then freeze-drying the first polymer to form a first polymer dispersion.

10. The method according to claim 9, characterized in that, The nonionic monomer is selected from acrylamide, N-hydroxymethylacrylamide, N-ethylacrylamide, N-isopropylacrylamide, vinylpyrrolidone, vinylcaprolactam; and / or The anionic monomer is selected from one or more of 2-acrylamido-2-methylpropanesulfonic acid and sodium styrene sulfonate; and / or The phenolic resin is a water-soluble phenolic resin, and the phenolic resin contains structural units shown in formula (C) and optionally structural units shown in formula (D):

11. The method according to claim 9 or 10, characterized in that, The mass ratio of the nonionic monomer to the anionic monomer is 1:0.2-1; and / or The total mass ratio of the nonionic monomer and the anionic monomer to the phenolic resin is 1:0.2-0.

5.

12. The method according to any one of claims 9-11, characterized in that, The copolymerization was carried out in the presence of initiator 2 and crosslinking agent 2; Preferably, the crosslinking agent 2 is selected from one or more of N,N-methylenebisacrylamide, ethylene glycol diacrylate, and polyethyleneimine; Preferably, the initiator 2 is selected from one or more of potassium persulfate and ammonium persulfate; and / or The total mass ratio of the nonionic monomer, the anionic monomer, and the phenolic resin to the crosslinking agent 2 is 1:0.001-0.02; and / or The copolymerization temperature is 60-70℃; and / or The co-polymerization time is 2-3 hours; and / or The copolymerization pH is 9-11; and / or Copolymerization is carried out in an inert gas; and / or The copolymerization was carried out dynamically at a speed of 400-600 rpm.

13. The method according to any one of claims 9-12, characterized in that, The solvent of the first polymer dispersion includes an alcohol and water, wherein the alcohol is selected from one or more of tert-butanol, ethanol, methanol, and propanol, and the mass ratio of alcohol to water is 1:1-5; and / or In the first polymer dispersion, the mass ratio of solvent to the first polymer is 1:0.01-0.05; and / or The freeze-drying step includes: pre-freezing in liquid nitrogen, followed by freeze-drying, preferably, pre-freezing in liquid nitrogen for 0.5-2.5 hours; Preferably, the freeze-drying temperature is -60 to -80°C; Preferably, the freeze-drying pressure is 0.5-1.5 Pa; Preferably, the freeze-drying time is 36-60 hours.

14. The method according to claim 13, characterized in that, The solvent for the first polymer dispersion includes tert-butanol, ethanol, and water, wherein the mass ratio of tert-butanol, ethanol, and water is 1:1-2:7-8; and / or In the first polymer dispersion, the mass ratio of solvent to the first polymer is 1:0.01-0.

02.

15. A polymer, characterized in that, The polymer is prepared according to the method described in any one of claims 1-14.

16. The polymer according to claim 15, characterized in that, The polymer has an approximately spherical morphology, consisting of multiple interwoven and entangled molecular chains, with a rough and dense surface, and no obvious filamentous or porous structures; and / or The polymer has a number-average molecular weight of 30,000-200,000 g / mol; and / or The polymer has an average particle size of 200-300 μm in the dry state; and / or The polymer exhibits a hydration kinetic particle size distribution range of 100-400 μm in water at 10-40℃, with an average particle size of 200-300 μm; and / or The polymer exhibits a hydration kinetic particle size distribution range of 100-500 μm in water at 150-250 °C, with an average particle size of 200-300 μm; and / or The polymer exhibits a hydration kinetic particle size distribution range of 100-400 μm in 150-250℃, 200000-400000 mg / L saline solution, with an average particle size of 200-300 μm.

17. The application of a polymer in drilling fluids and / or completion fluids, characterized in that, The polymer is the polymer described in claim 15 or 16.

18. The application according to claim 17, characterized in that, Application of the polymer in water-based drilling fluids.

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