A fluid loss reducer and its preparation method and application

Abstract

The present invention relates to a fluid loss control agent, its preparation method, and its application. The fluid loss control agent is obtained by polymerizing the following monomers: a sulfonic acid acrylamide compound, N-vinyl pyrrolidone, an anionic alkenyl aromatic compound, a siloxane acrylamide compound, a perfluoroalkyl acrylate compound, and vinyl naphthalene. The fluid loss control agent provided by the present invention, through the compounding of multiple active components, produces a small molecule heterochain polymer with excellent fluid loss reduction performance and high-temperature and salt tolerance, meeting the drilling requirements of deep wells with high-temperature and high-salt formations.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling, and in particular to a fluid loss reducer, a preparation method thereof and an application thereof. Background Art

[0002] In recent years, domestic energy demand has increased rapidly, and the exploration of oil and natural gas reserves has also increased. Complex terrains such as deep and ultra-deep formations, overpressure formations, salt layers, clay layers, and leakage layers have brought great challenges to the performance of drilling fluids, especially in high temperature and high salt (such as high Na + , Ca 2+ ) conditions, the drilling fluid loss is out of control, seriously affecting safe drilling. As one of the core treatment agents of drilling fluid, fluid loss reducer plays a key role in reducing the invasion of drilling fluid filtrate into the formation. However, the current fluid loss reducer is difficult to meet the requirements of deep well drilling for fluid loss reducer resistance to high temperature and complex salt. Therefore, there is an urgent need for high temperature and salt resistance (Na + , Ca 2+ ) drilling fluid loss reducer.

[0003] CN115850578A discloses a polymer fluid loss reducer, a method for preparing a high-temperature resistant polymer water-based drilling fluid fluid loss reducer. Acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, styrene, and dimethyldiallylammonium chloride are added to a reactor, followed by adding deionized water and stirring to completely dissolve. After dissolution, an alkaline solution is added to adjust the pH value. An inert gas is then introduced to replace the atmosphere, followed by heating and reacting. An initiator is added and stirred to react. After the reaction, a precipitant is added, cooled to room temperature, filtered, and dried to obtain a solid reactant. The solid reactant is ground into powder, the powder is placed in white oil and stirred to heat, and then a sulfonating agent is added to carry out a sulfonation reaction. After the reaction, a precipitant is added to precipitate and precipitate a product. The product is filtered, washed, dried, and ground to obtain a high-temperature resistant polymer water-based drilling fluid fluid loss reducer. The high-temperature resistant polymer fluid loss reducer reaches 230°C, but the salt resistance is only 4%, indicating that the salt resistance performance needs to be improved.

[0004] CN111303356A discloses a non-sulfonated temperature-resistant filtration-loss agent, which first dissolves nano-silica modified with an organic silane coupling agent in water, stirs at room temperature to fully disperse the modified nano-SiO2, and prepares an inorganic modified nano-SiO2 suspension; then takes acrylic acid and dimethyldiallyl ammonium chloride and mixes them with the inorganic modified nano-SiO2 suspension, which can effectively reduce water loss and has good filtration reduction performance at room temperature and 180℃-200℃, but its temperature resistance needs to be further improved. CN116082570A discloses a nano-composite filtration-loss agent, which can resist temperatures up to 240℃ in fresh water, but its salt and calcium resistance needs to be further improved. CN114716607A and CN106366243A disclose betaine copolymer filtration-loss agents, which can enhance the salt resistance of polymers, but their calcium resistance is poor. 2+ Both performance and high temperature and high pressure filtration performance need to be further improved.

[0005] Therefore, this area is in urgent need of developing a temperature and salt resistance (Na + , Ca 2+ ) High-performance fluid loss reducer to meet the application needs of ultra-deep well drilling. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a fluid loss reducer, a preparation method thereof, and an application thereof. By compounding multiple active components, the prepared small molecule heterochain polymer has excellent fluid loss reduction performance and high temperature and salt resistance. It can still achieve good fluid loss reduction effect under high temperature and high salt conditions, meeting the drilling needs of deep wells, high temperature, and high salt formations.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a fluid loss control agent, wherein the raw materials for preparing the fluid loss control agent include the following components: a sulfonic acid acrylamide compound, N-vinyl pyrrolidone, an anionic group-containing alkenyl aromatic compound, a siloxane acrylamide compound, a perfluoroalkyl acrylate compound and vinyl naphthalene.

[0009] The sulfonic acid acrylamide compound in the raw material for preparing the fluid loss reducer provided by the present invention has a certain surface active effect and can promote the reaction. The sulfonic acid acrylamide compound synergistically combines with N-vinyl pyrrolidone, anionic group-containing alkenyl aromatic compounds, and siloxane acrylamide compounds to improve the reactivity of vinyl naphthalene monomers and perfluoroalkyl acrylate compounds that are not easily reactive. The molecular weight of the fluid loss reducer is controlled within a relatively small range, so that the rheological properties of the fluid loss reducer are minimally affected when the fluid loss reducer is added to a deep high-density drilling fluid system. This solves the problem that viscosity increase occurs when a high-molecular-weight polymer is added to the drilling fluid system, which limits the amount of the fluid loss reducer added and makes it difficult to achieve a good fluid loss reduction effect.

[0010] At the same time, the anionic groups such as sulfonic acid groups in sulfonic acid acrylamide compounds and alkenyl aromatic compounds containing anionic groups can be adsorbed on the surface of clay particles to form a hydration film. This hydration film increases the mechanical resistance and electrostatic repulsion between particles, so that the clay particles maintain a multi-level dispersion state, thereby effectively preventing the reduction of filtration loss caused by the aggregation of particles to form large particles; on the other hand, the anionic groups with strong hydration ability can enhance the salt resistance of the polymer, so that the filtration reducer has good salt resistance (Na + , Ca 2+ ) properties. By using aromatic alkenyl aromatic compounds containing anionic groups and vinyl naphthalene, which can be dispersed in the reaction system through a solubilizing effect, to increase steric hindrance, and using siloxane acrylamide compounds to increase the negative charge of clay particles, these multiple components synergistically improve the fluid loss reduction effect of the resulting polymer. Furthermore, the raw materials for preparing the fluid loss control agent provided by the present invention include perfluoroalkyl acrylate compounds, which enhance high-temperature stability and provide the resulting fluid loss control agent with excellent heat resistance.

[0011] Preferably, the weight average molecular weight of the fluid loss agent is 30,000-50,000 g / mol, for example, 32,000 g / mol, 35,000 g / mol, 38,000 g / mol, 40,000 g / mol, 42,000 g / mol, 45,000 g / mol or 48,000 g / mol.

[0012] Preferably, the raw materials for preparing the fluid loss agent include the following components, calculated in parts by weight: 15-25 parts of sulfonic acid acrylamide compounds (for example, 16 parts, 18 parts, 20 parts, 22 parts or 24 parts), 3-7 parts of N-vinyl pyrrolidone (for example, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts or 6.5 parts), 4-6 parts of vinyl aromatic compounds containing anionic groups (for example, 4.2 parts, 5.5 parts, 6.5 parts or 6.5 parts), and 15-20 parts of sulfonic acid acrylamide compounds (for example, 16 parts, 18 parts, 20 parts, 22 parts or 24 parts). 4.5 parts, 4.8 parts, 5 parts, 5.2 parts, 5.5 parts or 5.8 parts, etc.), 3-9 parts of siloxane acrylamide compounds (for example, 3.5 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts, etc.), 2-7 parts of perfluoroalkyl acrylate compounds (for example, 2.5 parts, 3 parts, 4 parts, 5 parts or 6 parts, etc.), and 1.5-4 parts of vinyl naphthalene (for example, 1.8 parts, 2 parts, 2.5 parts, 3 parts or 3.5 parts, etc.).

[0013] Preferably, the sulfonic acid acrylamide compound includes any one of 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-acrylamido-1-propanesulfonic acid or 2-acrylamido-1-ethanesulfonic acid, or a combination of at least two thereof.

[0014] Preferably, the siloxane acrylamide compound includes N-(3-triethoxysilyl)propyl acrylamide.

[0015] Preferably, the anionic group-containing alkenyl aromatic compound includes any one of alkenyl aromatic sulfonates, alkenyl aromatic sulfates, alkenyl aromatic phosphates or alkenyl aromatic carboxylates, or a combination of at least two thereof.

[0016] Preferably, the alkenyl group in the anionic group-containing alkenyl aromatic compound includes any one of vinyl, propenyl or allyl, or a combination of at least two of them.

[0017] Preferably, the anionic group-containing alkenyl aromatic compound includes sodium p-styrene sulfonate.

[0018] Preferably, the perfluoroalkyl acrylate compound includes any one of perfluoroalkyl ethyl acrylate, perfluoroalkyl methacrylate or perfluoroalkyl propyl acrylate, or a combination of at least two thereof.

[0019] Preferably, the vinyl naphthalene includes 1-vinyl naphthalene and / or 2-vinyl naphthalene.

[0020] In a second aspect, the present invention provides a method for preparing the fluid loss additive according to the first aspect, the preparation method comprising the following steps:

[0021] Sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, anionic group-containing alkenyl aromatic compounds, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds and vinyl naphthalene are reacted in the presence of an initiator and an optional solvent to obtain the fluid loss reducer.

[0022] Preferably, based on 100 parts by weight of the total monomers, the weight of the initiator is 0.01-1 part, for example, 0.05 part, 0.1 part, 0.2 part, 0.3 part, 0.5 part or 0.8 part.

[0023] Preferably, the initiator comprises a water-soluble initiator.

[0024] Preferably, the initiator includes an azoamidine initiator, for example, the azoamidine initiator V50.

[0025] Preferably, based on 100 parts by mass of the monomer, the mass of the solvent is 50-400 parts, for example, 60 parts, 80 parts, 100 parts, 150 parts, 200 parts, 250 parts, 300 parts or 350 parts.

[0026] Preferably, the solvent comprises water.

[0027] Preferably, the raw materials in the preparation method include the following components in parts by weight: 15-25 parts of sulfonic acid acrylamide compounds, 3-7 parts of N-vinyl pyrrolidone, 4-6 parts of vinyl aromatic compounds containing anionic groups, 3-9 parts of siloxane acrylamide compounds, 2-7 parts of perfluoroalkyl acrylate compounds, 1.5-4 parts of vinyl naphthalene, 0.1-0.2 parts of initiator, and 70-110 parts of solvent.

[0028] Preferably, the preparation method comprises the following steps:

[0029] Sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds, vinyl naphthalene and solvent are uniformly dispersed, the temperature is raised to the reaction temperature, and an initiator is added to react to obtain the fluid loss reducer.

[0030] Preferably, the reaction temperature is 50-60°C, for example, 51°C, 53°C, 55°C, 57°C or 59°C.

[0031] Preferably, the reaction time is 4-6 h, for example, 4.2 h, 4.5 h, 4.8 h, 5 h, 5.2 h, 5.5 h or 5.8 h.

[0032] Preferably, after the reaction, washing, filtering, drying and crushing are performed to obtain the fluid loss reducer.

[0033] Preferably, the washing solvent comprises acetone.

[0034] Preferably, the drying temperature is 90-100°C, for example, 91°C, 93°C, 95°C, 97°C or 99°C.

[0035] Preferably, the drying time is 24-48 hours, for example, 28 hours, 32 hours, 36 hours, 40 hours or 44 hours.

[0036] In a third aspect, the present invention provides a drilling fluid, which includes the fluid loss reducer as described in the first aspect.

[0037] Preferably, the drilling fluid further comprises bentonite and a solvent.

[0038] Preferably, the drilling fluid comprises the following components, in parts by weight: 1-5 parts (for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts) of the fluid loss reducer as described in the first aspect, 1-5 parts (for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts) of bentonite, and 100 parts of solvent.

[0039] Preferably, the bentonite comprises sodium bentonite.

[0040] Preferably, the solvent comprises water.

[0041] In a fourth aspect, the present invention provides a use of the fluid loss reducer as described in the first aspect or the drilling fluid as described in the third aspect in deep well drilling.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] The fluid loss reducer provided by the present invention is compounded with specific types of monomers to achieve molecular weight control, so that it has excellent fluid loss reduction effect while synergistically improving the high temperature resistance and salt resistance of the fluid loss reducer. The temperature resistance reaches 220°C, the NaCl resistance reaches 30%, and the CaCl2 resistance reaches 5%. It maintains excellent fluid loss reduction performance under high temperature and high salt conditions and can meet the drilling requirements of deep wells, high temperature and high salt formations. DETAILED DESCRIPTION

[0044] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Unless otherwise specified, the materials used in the following examples can be obtained from commercial sources.

[0046] Example 1

[0047] A fluid loss control agent A1, comprising the following raw materials in parts by weight: 21 parts of 2-acrylamido-2-methyl-1-propanesulfonic acid, 5 parts of N-vinyl pyrrolidone, 5 parts of sodium p-styrenesulfonate, 4 parts of N-(3-triethoxysilyl)propyl acrylamide, 3 parts of perfluoroalkylethyl acrylate, 2 parts of 1-vinylnaphthalene, 0.15 parts of azoamidine initiator V50, and 100 parts of deionized water;

[0048] The fluid loss reducer is prepared by the following method:

[0049] 2-Acrylamido-2-methyl-1-propanesulfonic acid, N-vinyl pyrrolidone, sodium p-styrenesulfonate, N-(3-triethoxysilyl)propyl acrylamide, perfluoroalkylethyl acrylate, and 1-vinylnaphthalene were added to water and stirred for 20 minutes until fully dispersed. After heating to 55° C., azoamidine initiator V50 was added and free radical polymerization was carried out for 4 hours to obtain a viscous crude polymer. The crude polymer was washed twice with acetone, dried at 100° C. for 24 hours, and crushed to obtain a white powder, which is the fluid loss reducer A1.

[0050] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A1 is 36572 g / mol.

[0051] Example 2

[0052] A fluid loss additive A2, which differs from Example 1 only in that the perfluoroalkyl ethyl acrylate is 5 parts, and the other components and preparation method are the same as those of Example 1;

[0053] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A2 is 39841 g / mol.

[0054] Example 3

[0055] A fluid loss reducer A3, which differs from Example 1 only in that 1-vinylnaphthalene is used in an amount of 3 parts, and the other components and preparation method are the same as those of Example 1;

[0056] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A3 is 33675 g / mol.

[0057] Example 4

[0058] A fluid loss additive A4, which differs from Example 1 only in that N-(3-triethoxysilyl)propyl acrylamide is used in an amount of 6 parts, and the other components and preparation method are the same as those of Example 1;

[0059] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A4 is 43244 g / mol.

[0060] Example 5

[0061] A fluid loss additive A5, which differs from Example 1 only in that the perfluoroalkyl ethyl acrylate is 7 parts, and the other components and preparation method are the same as those of Example 1;

[0062] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of fluid loss additive A5 is 40807 g / mol.

[0063] Example 6

[0064] A fluid loss reducer A6, which differs from Example 1 only in that 1-vinylnaphthalene is used in an amount of 4 parts, and the other components and preparation method are the same as those of Example 1;

[0065] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A6 is 31218 g / mol.

[0066] Example 7

[0067] A fluid loss reducer A7, which differs from Example 1 only in that N-(3-triethoxysilyl)propyl acrylamide is used in an amount of 8 parts, and the other components and preparation method are the same as those of Example 1;

[0068] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A7 is 47342 g / mol.

[0069] Example 8

[0070] A fluid loss reducer A8, which differs from Example 1 only in that the perfluoroalkyl ethyl acrylate is 1 part, and the other components and preparation method are the same as those of Example 1;

[0071] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss reducer A8 is 37931 g / mol.

[0072] Example 9

[0073] A fluid loss reducer A9, which differs from Example 1 only in that 1-vinylnaphthalene is used as 1 part, and the other components and preparation method are the same as those of Example 1;

[0074] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A9 is 38109 g / mol.

[0075] Example 10

[0076] A fluid loss reducer A 10 The only difference between it and Example 1 is that N-(3-triethoxysilyl)propyl acrylamide is 2 parts, and the other components and preparation method are the same as those in Example 1;

[0077] Test Fluid Loss Reducer A in accordance with the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014 10 The weight average molecular weight is 34640 g / mol.

[0078] Comparative Example 1

[0079] A fluid loss reducer D1, which differs from Example 1 only in that 2-acrylamido-2-methyl-1-propanesulfonic acid is replaced with an equal amount of acrylamide, and the other components and preparation method are the same as those of Example 1;

[0080] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A2 is 61456 g / mol.

[0081] Comparative Example 2

[0082] A fluid loss additive D2, which differs from Example 1 only in that N-vinyl pyrrolidone is replaced with an equal amount of maleic anhydride, and the other components and preparation method are the same as those of Example 1;

[0083] According to the National Metrology Verification Regulations of the People's Republic of China JJG 342-2014, the weight average molecular weight of the fluid loss additive A2 is 56702 g / mol.

[0084] Application Example 1

[0085] A drilling fluid F1, comprising the following raw materials in parts by weight: 13 parts of fluid loss reducer A, 4 parts of sodium bentonite (Shandong Huawei Bentonite Co., Ltd., sodium bentonite for drilling fluid), and 96 parts of water;

[0086] The drilling fluid is prepared by the following method:

[0087] 4 parts by weight of sodium bentonite were added to 96 parts of water, stirred at 11000 r / min for 20 minutes, and then allowed to stand and cure at room temperature for 24 hours. The mixture was stirred for another 20 minutes, and 3 parts of A1 were added to obtain the drilling fluid.

[0088] Application Example 2

[0089] A drilling fluid F2, comprising the following raw materials in parts by weight: 13 parts of fluid loss reducer A, 4 parts of sodium bentonite (Shandong Huawei Bentonite Co., Ltd., sodium bentonite for drilling fluid), 96 parts of water, and 30 parts of sodium chloride;

[0090] The drilling fluid is prepared by the following method:

[0091] 4 parts by weight of sodium bentonite were added to 96 parts of water, stirred at 11000 r / min for 20 minutes, and then allowed to stand at room temperature for 24 hours. The mixture was stirred for another 20 minutes, and 3 parts of A1 and 30 parts of sodium chloride were added to obtain the drilling fluid.

[0092] Application Example 3-18, Comparative Application Example 1-6

[0093] A drilling fluid comprises, in parts by weight, 4 parts sodium bentonite, 96 parts water, a fluid loss reducer, and sodium chloride or calcium chloride as shown in Table 1; when sodium chloride or calcium chloride is present, the preparation method is the same as that of Application Example 2; when sodium chloride or calcium chloride is absent, the preparation method is the same as that of Application Example 1.

[0094] Table 1

[0095]

[0096]

[0097] Take 400mL of the above drilling fluid and stir it at 8000rpm for 20min, then put it into a stainless steel aging tank and roll it at a constant temperature of 220℃ for 16 hours. After aging, cool it to room temperature and take it out, and stir it at 8000rpm for 20min. According to the petroleum and natural gas industry standard GB / T 29170-2012 "Petroleum and Natural Gas Industry-Drilling Fluid Laboratory Test", the apparent viscosity (AV, mPa.s), plastic viscosity (PV, mPa.s), dynamic shear force (YP, Pa), API filtration loss FL of the above drilling fluid were measured. API , high temperature and high pressure filtration loss FL HTHP (180°C, 3.45 MPa), the results are summarized in Table 2.

[0098] Table 2

[0099]

[0100]

[0101] The test results show that the fluid loss reducer provided by the present invention adopts a specific type of monomer to compound and realize molecular weight control, so that it has excellent fluid loss reduction effect, while synergistically improving the high temperature resistance and salt resistance of the fluid loss reducer, with a temperature resistance of 220°C, a NaCl resistance of 30%, and a CaCl2 resistance of 5%. The API fluid loss is ≤9.8mL, and the high temperature and high pressure fluid loss is FL HTHP ≤41.8mL can meet the drilling needs of deep wells, high temperature and high salinity formations.

[0102] In this field, salt resistance is calculated based on the mass of the base slurry (including bentonite and solvent) as 100%, that is, NaCl resistance of 30% means that it can resist NaCl that is 30% of the mass of the base slurry.

[0103] By comparing Application Examples 1-3 with the Comparative Application Examples, it can be seen that after adding the fluid loss reducer provided by the present invention, the API fluid loss of the freshwater base slurry can be reduced from 41.0 mL to 5.0 mL, and the high-temperature and high-pressure fluid loss can be reduced from 103.0 mL to 25.4 mL; when containing sodium chloride, the API fluid loss is reduced from 264.0 mL after high-temperature aging of the drilling fluid obtained in Comparative Application Example 2 to 5.8 mL, and the high-temperature and high-pressure fluid loss is reduced from the total fluid loss to 36.8 mL; when containing calcium chloride, the API fluid loss and high-temperature and high-pressure fluid loss are reduced from the total fluid loss of the drilling fluid obtained in Comparative Application Example 3 to 9.8 mL and 41.8 mL, respectively, confirming that the fluid loss reducer provided by the present invention maintains excellent fluid loss reduction effect under high temperature and high salinity conditions. In addition, by comparing Comparative Application Example 6 with Application Example 2, it can be seen that the fluid loss reducer provided by the present invention is significantly better than the commercial fluid loss reducer. Compared with DSP-1, the API fluid loss and high-temperature and high-pressure fluid loss are reduced by 43.14% and 42.86%, respectively.

[0104] Comparing Application Examples 2, 5, 13, and 16, it can be seen that appropriately increasing the proportion of perfluoroalkylethyl acrylate in the polymer can further reduce fluid loss. This is because the fluorine atoms in the perfluoroalkylethyl acrylate increase the negative charge of the clay particles. At the same time, the perfluoro side chains of the polymer are oriented outward, forming a "shielding protection" for the main chain and internal molecules. The addition further enhances the polymer's temperature and salt resistance. Conversely, when the proportion of perfluoroalkylethyl acrylate in the polymer is reduced, the number of fluorine atoms in the polymer decreases, resulting in insufficient temperature and salt resistance. In addition, if the proportion of perfluoroalkylethyl acrylate is too high, the reaction activity is too low, making it difficult to successfully polymerize and thus unable to obtain a polymer fluid loss control agent. Therefore, the proportion of perfluoroalkyl acrylate compounds needs to be controlled within the range of the present invention to obtain a fluid loss control agent with even better application effects.

[0105] By comparing Application Examples 2, 8, 14, and 17, it can be seen that appropriately increasing the proportion of vinyl naphthalene in the monomer can also reduce fluid loss. More aromatic benzene rings provide hydrophobic properties and rigidity to the polymer, thereby improving the thermal stability of the polymer. Reducing the proportion of vinyl naphthalene in the polymer will lead to a decrease in the polymer's fluid loss reduction performance because the benzene ring content in the polymer decreases and the polymer's high temperature resistance weakens. However, when the proportion of vinyl naphthalene monomer is further increased, due to the steric effect of the benzene rings in the vinyl naphthalene monomer, an excessive number will hinder the polymerization between the monomers. The polymerization result is a reaction product with low molecular weight and low viscosity, or even inability to polymerize, and poor fluid loss reduction performance. If the proportion of vinyl naphthalene in the monomer is too high, the proportion of other groups such as sulfonic acid groups is reduced, which will also weaken the polymer's adsorption, temperature resistance, and salt resistance, resulting in an increase in fluid loss. Therefore, the proportion of vinyl naphthalene needs to be controlled within the scope of the present invention. At this time, the polymerization effect of vinyl naphthalene monomer and other monomers is good, and the fluid loss reduction performance is excellent.

[0106] Comparing Application Examples 2, 11, 15, and 18, it can be seen that appropriately increasing the proportion of N-(3-triethoxysilyl)propyl acrylamide monomer in the polymer can further reduce fluid loss. This is because the addition of more siloxane groups enhances the adsorption between the polymer and the clay, increasing the amount of small-molecule heterochain polymer fluid loss additive adsorbed on the clay surface at high temperatures, maintaining the colloidal stability of the clay under high temperature and high salinity conditions, thereby achieving the goal of reducing drilling fluid loss. Conversely, reducing the proportion of N-(3-triethoxysilyl)propyl acrylamide monomer in the polymer can also lead to a decrease in fluid loss additive performance due to reduced polymer adsorption on the clay particle surface, reducing the fluid loss reduction effect.

[0107] From the test results of Comparative Application Example 4, it can be seen that when 2-acrylamido-2-methyl-1-propanesulfonic acid is replaced by acrylamide, the fluid loss reduction performance is significantly reduced. This is because sulfonic acid acrylamide compounds have stronger hydrolysis stability, and polymers containing this monomer are more stable at high temperatures. At the same time, the sulfonic acid group contained in it increases the adsorption capacity of the polymer, and their fluid loss reduction performance is better.

[0108] The test results of Comparative Application Example 5 show that when maleic anhydride is substituted for N-vinyl pyrrolidone, the resulting polymeric fluid loss control agent exhibits a low thermal decomposition temperature. During high-temperature drilling, it readily decomposes, generating small molecules that lose their original fluid loss control function. This indicates that the present invention, through the use of a specific monomer combination, produces a fluid loss control agent with superior fluid loss reduction performance and temperature and salt tolerance.

[0109] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A fluid loss additive, characterized in that: The fluid loss reducer is obtained by polymerizing the following monomers: sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds and vinyl naphthalene; The anionic group-containing alkenyl aromatic compound includes alkenyl aromatic sulfonates.

2. The fluid loss reducer according to claim 1, wherein The weight average molecular weight of the fluid loss additive is 30,000-50,000 g / mol.

3. The fluid loss reducer according to claim 1, characterized in that The monomers include the following components in parts by weight: 15-25 parts of sulfonic acid acrylamide compounds, 3-7 parts of N-vinyl pyrrolidone, 4-6 parts of vinyl aromatic compounds containing anionic groups, 3-9 parts of siloxane acrylamide compounds, 2-7 parts of perfluoroalkyl acrylate compounds, and 1.5-4 parts of vinyl naphthalene.

4. The fluid loss reducer according to claim 1, characterized in that The sulfonic acid acrylamide compound includes any one of 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-acrylamido-1-propanesulfonic acid or 2-acrylamido-1-ethanesulfonic acid, or a combination of at least two thereof.

5. The fluid loss reducer according to claim 1, characterized in that The siloxane acrylamide compound includes N-(3-triethoxysilyl)propyl acrylamide.

6. The fluid loss reducer according to claim 1, characterized in that The alkenyl group in the alkenyl aromatic compound containing an anionic group includes any one of vinyl, propenyl or allyl, or a combination of at least two of them.

7. The fluid loss reducer according to claim 1, characterized in that The anionic group-containing alkenyl aromatic compound includes sodium p-styrene sulfonate.

8. The fluid loss reducer according to claim 1, characterized in that The perfluoroalkyl acrylate compound includes any one of perfluoroalkyl ethyl acrylate, perfluoroalkyl methacrylate or perfluoroalkyl propyl acrylate, or a combination of at least two thereof.

9. The fluid loss reducer according to claim 1, characterized in that The vinyl naphthalene includes 1-vinyl naphthalene and / or 2-vinyl naphthalene.

10. A method for preparing the fluid loss additive according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: Sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, anionic group-containing alkenyl aromatic compounds, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds and vinyl naphthalene are reacted in the presence of an initiator and an optional solvent to obtain the fluid loss reducer.

11. The preparation method according to claim 10, characterized in that: Based on 100 parts of the total mass of the monomers, the mass of the initiator is 0.01-1 part.

12. The preparation method according to claim 10, characterized in that The initiator includes a water-soluble initiator.

13. The preparation method according to claim 10, characterized in that The initiator includes an azoamidine initiator.

14. The preparation method according to claim 10, characterized in that Based on 100 parts by mass of the monomer, the mass of the solvent is 50-400 parts by mass.

15. The preparation method according to claim 10, characterized in that The solvent includes water.

16. The preparation method according to claim 10, characterized in that The preparation method comprises the following steps: Sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds, vinyl naphthalene and solvent are uniformly dispersed, the temperature is raised to the reaction temperature, and an initiator is added to react to obtain the fluid loss reducer.

17. The preparation method according to claim 16, characterized in that The reaction temperature is 50-60°C.

18. The preparation method according to claim 16, characterized in that The reaction time is 4-6 hours.

19. The preparation method according to claim 16, characterized in that After the reaction, washing, filtering, drying and crushing are performed to obtain the fluid loss reducer.

20. The preparation method according to claim 19, characterized in that The washing solvent includes acetone.

21. The preparation method according to claim 19, characterized in that The drying temperature is 90-100°C.

22. The preparation method according to claim 19, characterized in that The drying time is 24-48 hours.

23. A drilling fluid, characterized in that: The drilling fluid comprises the fluid loss reducer according to any one of claims 1 to 9.

24. The drilling fluid according to claim 23, wherein The drilling fluid also includes bentonite and a solvent.

25. The drilling fluid according to claim 24, wherein The drilling fluid comprises the following components in parts by weight: 1-5 parts of the fluid loss reducer according to any one of claims 1 to 9, 1-5 parts of bentonite, and 100 parts of a solvent.

26. The drilling fluid according to claim 24, wherein The bentonite includes sodium bentonite.

27. The drilling fluid according to claim 24, wherein The solvent includes water.

28. Use of the fluid loss reducer according to any one of claims 1 to 9 or the drilling fluid according to any one of claims 23 to 27 in deep well drilling.

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