Filtrate reducer as well as preparation method and application thereof

Abstract

The invention relates to a filtrate reducer as well as a preparation method and application thereof. The filtrate reducer is obtained by polymerizing the following monomers: a sulfonic acrylamide compound, N-vinyl pyrrolidone, an alkenyl aromatic compound containing an anionic group, a siloxane acrylamide compound, a perfluoroalkyl acrylate compound and vinylnaphthalene. According to the filtrate reducer provided by the invention, through compounding of various active components, the prepared micromolecular heterochain polymer has excellent filtrate reduction performance, high temperature resistance and salt resistance, and meets the drilling requirements of high-temperature and high-salt formations of deep wells.

Description

Technical Field

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

[0002] In recent years, domestic energy demand has increased rapidly, and the exploration of oil and 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 for drilling fluid, filtrate reducer plays a key role in reducing the intrusion of drilling fluid filtrate into the formation. However, the current filtrate reducer is difficult to meet the requirements of deep well drilling for high temperature and complex salt resistance. 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. Add acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, styrene and dimethyldiallylammonium chloride into a reactor, then add deionized water and stir to completely dissolve, add an alkali solution after dissolution to adjust its pH value; then introduce an inert gas to replace the atmosphere, then heat and heat to react, add an initiator and stir to react, add a precipitant after the reaction, cool to room temperature, filter and dry to obtain a solid reactant; grind the solid reactant into powder, place the powder in white oil and stir to heat, then add a sulfonating agent to carry out a sulfonation reaction; after the reaction, add a precipitant to precipitate and precipitate the product, the product is filtered, washed, dried and ground in sequence to obtain a high temperature resistant polymer water-based drilling fluid fluid loss reducer, which has a high temperature resistance of 230°C, but a salt resistance of only 4%, and the salt resistance performance needs to be improved.

[0004] CN111303356A discloses a non-sulfonated temperature-resistant fluid loss reducer, which first dissolves nano-silicon dioxide modified by an organic silane coupling agent in water, stirs at room temperature to fully disperse the modified nano-SiO2, and obtains an inorganic modified nano-SiO2 suspension; then acrylic acid and dimethyldiallyl ammonium chloride are mixed with the inorganic modified nano-SiO2 suspension, which can effectively reduce water loss and has good filtration reduction performance at room temperature and 180°C-200°C, but its temperature resistance needs to be further improved. CN116082570A discloses a nano-composite fluid loss reducer, which can resist temperatures up to 240°C in fresh water, but its salt and calcium resistance needs to be further improved. CN114716607A and CN106366243A disclose betaine copolymer fluid loss reducers, 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+ ) Excellent performance fluid loss reducer to meet the application requirements of ultra-deep well drilling. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a fluid loss reducer and a preparation method and application thereof. Through the compounding of multiple active components, the prepared small molecule heterochain polymer has excellent fluid loss reduction performance and high temperature resistance 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 well 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 reducer, wherein the raw materials for preparing the fluid loss reducer include the following components: sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds and vinyl naphthalene.

[0009] The sulfonic acid acrylamide compounds in the raw materials for preparing the fluid loss reducer provided by the present invention have a certain surface active effect and can promote the reaction. The sulfonic acid acrylamide compounds cooperate with N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups and siloxane acrylamide compounds to improve the reaction activity of vinyl naphthalene monomers and perfluoroalkyl acrylate compounds that are not easy to react, and 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 slightly affected when the fluid loss reducer is added into a deep high-density drilling fluid system, thereby solving the problem that viscosity increase occurs when a high molecular weight polymer is added into the drilling fluid system, the amount of the fluid loss reducer added is limited, and a good fluid loss reduction effect is difficult to achieve.

[0010] At the same time, the anionic groups such as sulfonic acid groups in sulfonic 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 filtrate reducer has good salt resistance (Na + , Ca 2+ ) properties. By using aromatic alkenyl aromatic compounds containing anionic groups and vinyl naphthalene that can be dispersed in the reaction system through the solubilization effect to increase the steric hindrance, and using siloxane acrylamide compounds to increase the negative charge of clay particles, the multi-components synergistically improve the filtration loss reduction effect of the obtained polymer. In addition, the raw materials for preparing the filtration loss reducer provided by the present invention include perfluoroalkyl acrylate compounds, which increase the high temperature stability, so that the obtained filtration loss reducer has excellent temperature resistance.

[0011] Preferably, the weight average molecular weight of the fluid loss reducer is 30000-50000 g / mol, for example, 32000 g / mol, 35000 g / mol, 38000 g / mol, 40000 g / mol, 42000 g / mol, 45000 g / mol or 48000 g / mol.

[0012] Preferably, the raw materials for preparing the fluid loss reducer include the following components, measured in parts by weight: 15-25 parts of sulfonic acrylamide compounds (for example, 16 parts, 18 parts, 20 parts, 22 parts or 24 parts, etc.), 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, etc.), 4-6 parts of vinyl aromatic compounds containing anionic groups (for example, 4.2 parts, 5.5 parts, 6 parts or 6.5 parts, etc.), and 15-20 parts of sulfonic acrylamide compounds (for example, 16 parts, 18 parts, 20 parts, 22 parts or 24 parts, etc.). 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-acrylamide-2-methyl-1-propane sulfonic acid, 2-acrylamide-1-propane sulfonic acid or 2-acrylamide-1-ethane sulfonic 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 alkenyl aromatic compound containing anionic groups 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 comprises 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 reducer as described in the first aspect, the preparation method comprising the following steps:

[0021] The sulfonic acid acrylamide compound, N-vinyl pyrrolidone, anionic group-containing alkenyl aromatic compound, siloxane acrylamide compound, perfluoroalkyl acrylate compound 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 of the total mass of the monomers, the mass 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, etc.

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

[0024] Preferably, the initiator includes an azo amidine initiator, for example, the azo amidine 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 for preparation 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, the reaction is followed by washing, filtering, drying and crushing 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, wherein the drilling fluid comprises the fluid loss reducer as described in the first aspect.

[0037] Preferably, the drilling fluid also includes bentonite and a solvent.

[0038] Preferably, the drilling fluid comprises the following components, in parts by weight: 1-5 parts of the filtrate reducer as described in the first aspect (for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts), 1-5 parts of bentonite (for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts), 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 and synergistically improves 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 needs of deep well high temperature and high salt formations. DETAILED DESCRIPTION

[0044] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help 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 reducer A1, comprising the following raw materials in parts by weight: 21 parts of 2-acrylamido-2-methyl-1-propane sulfonic acid, 5 parts of N-vinyl pyrrolidone, 5 parts of sodium p-styrene sulfonate, 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-triethoxymethylsiloxy)propyl acrylamide, perfluoroalkylethyl acrylate, and 1-vinylnaphthalene were added into water, stirred for 20 minutes until fully dispersed, heated to 55° C., added with azoamidine initiator V50, and subjected to free radical polymerization for 4 hours to obtain a viscous crude polymer; the crude polymer was washed with acetone twice, 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 reducer A1 is 36572 g / mol.

[0051] Example 2

[0052] A fluid loss reducer 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 reducer 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 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 reducer A3 is 33675 g / mol.

[0057] Example 4

[0058] A fluid loss reducer A4, which differs from Example 1 only in that N-(3-triethoxysilyl)propyl acrylamide is 6 parts, and other components and preparation methods 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 reducer A4 is 43244 g / mol.

[0060] Example 5

[0061] A fluid loss reducer 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 filtrate reducer 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 4 parts, and other components and preparation methods 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 reducer 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 8 parts, and other components and preparation methods 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 reducer 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 1 part, and other components and preparation methods 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 reducer 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 the filtrate reducer A according to 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-propane sulfonic acid is replaced by an equal amount of acrylamide, and other components and preparation methods 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 reducer A2 is 61456 g / mol.

[0081] Comparative Example 2

[0082] A fluid loss reducer D2, which differs from Example 1 only in that N-vinyl pyrrolidone is replaced by an equal amount of maleic anhydride, and other components and preparation methods 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 reducer A2 is 56702 g / mol.

[0084] Application Example 1

[0085] A drilling fluid F1, the drilling fluid 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, and then 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, the drilling fluid 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, and then stirred for another 20 minutes, 3 parts of A1 were added, and then 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, measured by weight, comprises 4 parts of sodium-based bentonite, 96 parts of 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, 3.45MPa), 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 achieve molecular weight control, so that it has excellent fluid loss reduction effect, and synergistically improves the high temperature resistance and salt resistance of the fluid loss reducer, with a temperature resistance of 220°C, a NaCl resistance of 30%, a CaCl2 resistance of 5%, an API fluid loss of ≤9.8mL, and a high temperature and high pressure fluid loss of FL HTHP ≤41.8mL can meet the drilling needs of deep wells, high temperature and high salt 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, resistance to NaCl of 30% means the ability to resist NaCl that is 30% of the mass of the base slurry.

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

[0104] By comparing application examples 2, 5, 13 and 16, it can be seen that appropriately increasing the proportion of perfluoroalkyl ethyl acrylate in the polymer can further reduce the filtration loss, because the fluorine atoms in the perfluoroalkyl ethyl acrylate increase the negative charge of the clay particles, and the perfluoro side chains of the polymer are oriented outward, forming a "shielding protection" for the main chain and internal molecules, and the addition further enhances the polymer's resistance to temperature and salt. On the contrary, when the proportion of perfluoroalkyl ethyl acrylate in the polymer is reduced, the number of fluorine atoms in the polymer is reduced, resulting in insufficient resistance to temperature and salt. In addition, if the proportion of perfluoroalkyl ethyl acrylate is too large, the reaction activity is too low, it is difficult to polymerize smoothly, and the polymer filtration reducer cannot be obtained. Therefore, the proportion of perfluoroalkyl acrylate compounds needs to be controlled within the scope of the present invention, and a filtration reducer with a more excellent application effect can be obtained.

[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 the filtration loss. More aromatic benzene rings provide hydrophobic properties and rigidity for the polymer, thereby improving the thermal stability of the polymer. When the proportion of vinyl naphthalene in the polymer is reduced, the polymer's filtration loss reduction performance will decrease, because the benzene ring content in the polymer is reduced and the polymer's ability to resist high temperatures is weakened. However, when the proportion of vinyl naphthalene monomer is further increased, due to the steric effect of the benzene ring of the vinyl naphthalene monomer, the excessive number will hinder the polymerization between the monomers, and the polymerization result is that the reaction product has a low molecular weight, a low viscosity, or even cannot be polymerized, and the filtration loss reduction performance is poor; if the proportion of vinyl naphthalene in the monomer is too much, 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 filtration 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 filtration loss reduction performance is excellent.

[0106] By 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 the fluid loss, because the addition of more siloxane groups enhances the adsorption between the polymer and the clay, increases the adsorption of small molecule heterochain polymer fluid loss reducer on the clay surface at high temperature, maintains the colloidal stability of clay under high temperature and high salt, and thus achieves the purpose of reducing the drilling fluid loss. On the contrary, reducing the proportion of N-(3-triethoxysilyl)propyl acrylamide monomer in the polymer will also lead to a decrease in the performance of the fluid loss reducer, because the adsorption of the polymer on the surface of the clay particles is reduced, and the fluid loss reduction effect is reduced.

[0107] It can be seen from the test results of comparative application example 4 that when 2-acrylamido-2-methyl-1-propane sulfonic 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] It can be seen from the test results of comparative application example 5 that when N-vinyl pyrrolidone is replaced by maleic anhydride, the thermal decomposition temperature of the synthesized polymer fluid loss reducer is low. During high-temperature drilling, thermal decomposition easily occurs to generate small molecular substances, thereby losing its original fluid loss reduction function. In other words, the present invention obtains a fluid loss reducer with better fluid loss reduction effect and heat and salt resistance by using a combination of specific monomers.

[0109] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope 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 shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A fluid loss reducer, 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.

2. The fluid loss reducer according to claim 1, characterized in that: The weight average molecular weight of the fluid loss reducer is 30000-50000 g / mol; Preferably, the monomer comprises 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.

3. The fluid loss reducer according to claim 1 or 2, characterized in that: The sulfonic acid acrylamide compound includes any one of 2-acrylamide-2-methyl-1-propane sulfonic acid, 2-acrylamide-1-propane sulfonic acid or 2-acrylamide-1-ethane sulfonic acid or a combination of at least two thereof; Preferably, the siloxane acrylamide compound includes N-(3-triethoxysilyl)propyl acrylamide.

4. The fluid loss reducer according to any one of claims 1 to 3, characterized in that: The alkenyl aromatic compound containing anionic groups 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; Preferably, the alkenyl group in the alkenyl aromatic compound containing anionic groups includes any one of vinyl, propenyl or allyl, or a combination of at least two of them; Preferably, the anionic group-containing alkenyl aromatic compound comprises sodium p-styrene sulfonate.

5. The fluid loss reducer according to any one of claims 1 to 4, characterized in that: The perfluoroalkyl acrylate compound includes any one or a combination of at least two of perfluoroalkyl ethyl acrylate, perfluoroalkyl methacrylate or perfluoroalkyl propyl acrylate; Preferably, the vinyl naphthalene includes 1-vinyl naphthalene and / or 2-vinyl naphthalene.

6. A method for preparing the fluid loss reducer according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: The sulfonic acid acrylamide compound, N-vinyl pyrrolidone, anionic group-containing alkenyl aromatic compound, siloxane acrylamide compound, perfluoroalkyl acrylate compound and vinyl naphthalene are reacted in the presence of an initiator and an optional solvent to obtain the fluid loss reducer.

7. The preparation method according to claim 6, characterized in that: Based on 100 parts of the total mass of the monomer, the mass of the initiator is 0.01-1 part; Preferably, the initiator comprises a water-soluble initiator; Preferably, the initiator comprises an azoamidine initiator; Preferably, based on 100 parts by mass of the monomer, the mass of the solvent is 50-400 parts; Preferably, the solvent comprises water.

8. The preparation method according to claim 6 or 7, characterized in that: The preparation method comprises the following steps: Evenly dispersing sulfonic acid acrylamide compounds, N-vinyl pyrrolidone, alkenyl aromatic compounds containing anionic groups, siloxane acrylamide compounds, perfluoroalkyl acrylate compounds, vinyl naphthalene and solvent, heating to reaction temperature, adding initiator to react, and obtaining the fluid loss reducer; Preferably, the reaction temperature is 50-60°C; Preferably, the reaction time is 4-6h; Preferably, the reaction is followed by washing, filtering, drying and crushing to obtain the fluid loss reducer; Preferably, the washing solvent comprises acetone; Preferably, the drying temperature is 90-100°C; Preferably, the drying time is 24-48 hours.

9. A drilling fluid, characterized in that: The drilling fluid comprises the fluid loss reducer according to any one of claims 1 to 5; Preferably, the drilling fluid further comprises bentonite and a solvent; Preferably, 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 5, 1-5 parts of bentonite, and 100 parts of a solvent; Preferably, the bentonite comprises sodium bentonite; Preferably, the solvent comprises water.

10. Use of the fluid loss reducer according to any one of claims 1 to 5 or the drilling fluid according to claim 9 in deep well drilling.

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