Acrylamide multicomponent copolymers, processes for their preparation and use

Abstract

The application discloses an acrylamide multi-copolymer, a preparation method and application thereof. The acrylamide multi-copolymer comprises structural units A, B, C, D and E; wherein the structural unit A has a structure shown in formula (1), the structural unit B has a structure shown in formula (2), the structural unit C has a structure shown in formula (3), the structural unit D has a structure shown in formula (4), and the structural unit E has a structure shown in formula (5); wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 and R 12 are independently hydrogen or C1-C10 linear or branched alkyl; Y is C1-C10 linear or branched alkylene; X is halogen; M1 is hydrogen or alkali metal; and M2 is hydrogen or alkali metal. The acrylamide multi-copolymer has excellent temperature resistance, and can keep adhesion without aging under high-temperature formation conditions.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to acrylamide multi-component copolymers, their preparation methods, and applications. Background Technology

[0002] With the development of oil and gas resources in high-temperature deep wells and complex wells, the requirements for the high-temperature resistance of drilling fluids are constantly increasing. Viscosifiers, as one of the core processing agents in reservoir protection drilling fluids, have always been a research hotspot for drilling fluid engineers, playing a crucial role in regulating the rheological properties of drilling fluids. Besides their viscosity-increasing function, drilling fluid viscosifiers often also function as shale inhibitors (coating agents), filtration loss reducers, and flow pattern modifiers.

[0003] Historically, thickeners can be categorized into four main types: natural plant gum thickeners, inorganic thickeners, organic thickeners, and synthetic polymer thickeners. Commonly used thickeners for reservoir protection drilling fluids mainly include synthetic polymers, represented by acrylamide polymers, and biopolymers, represented by xanthan gum. However, both have insurmountable problems when used in high-temperature formations. Xanthan gum is easily degraded at high temperatures, exhibits relatively poor stability, and is prone to degradation, thus clogging the oil layer. Furthermore, it has high operating costs. Polyacrylamide polymers, on the other hand, have amide groups that are easily hydrolyzed, especially under acidic and alkaline conditions, where the hydrolysis rate is very fast. The hydrolysis rate increases with increasing temperature. When the degree of hydrolysis of the amide groups exceeds a certain level, it causes a loss of viscosity in the polymer solution.

[0004] CN105038733A discloses a high-temperature resistant polymer thickener for drilling fluids and its preparation method. This thickener is obtained by copolymerization of alkenyl sulfonic acid, alkenyl amide, and alkenylbenzene, and has a weight-average molecular weight of 1200,000-1500,000. However, while this drilling fluid thickener has a good thickening effect, it is not effective at high temperatures and has poor rheological properties.

[0005] CN110760295A discloses a high-temperature viscosity enhancer for oil well cement slurry and its preparation method, which can meet the viscosity enhancement requirements of fluids in oil well cementing and can be used in combination with other oil well additives under conditions of 50-160℃. However, when the temperature exceeds 160℃, its viscosity decreases significantly or it loses its viscosity.

[0006] Therefore, it is necessary to develop a new type of high-temperature resistant thickener for drilling fluids to further improve the performance of polymers and make them better suited to the needs of complex formations. Summary of the Invention

[0007] The purpose of this invention is to overcome the problem that the viscosity of existing thickeners decreases or is lost in high-temperature environments, and to provide an acrylamide multi-component copolymer, its preparation method and application. This acrylamide multi-component copolymer has excellent temperature resistance. Under high-temperature formation conditions, it can maintain the viscosity and flow pattern of drilling fluid while also reducing filtration loss. It can be used as a high-temperature resistant thickener for water-based drilling fluids. When used in combination with other drilling fluid additives at 50-180℃, its temperature resistance reaches 180℃.

[0008] To achieve the above objectives, a first aspect of the present invention provides an acrylamide multi-component copolymer, the acrylamide multi-component copolymer comprising: structural unit A, structural unit B, structural unit C, structural unit D, and structural unit E; wherein structural unit A has the structure shown in formula (1), structural unit B has the structure shown in formula (2), structural unit C has the structure shown in formula (3), structural unit D has the structure shown in formula (4), and structural unit E has the structure shown in formula (5).

[0009]

[0010]

[0011] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group;

[0012] Y is a C1-C10 straight-chain or branched alkylene group;

[0013] X is a halogen;

[0014] M1 is hydrogen or an alkali metal;

[0015] M2 is hydrogen or an alkali metal.

[0016] A second aspect of the present invention provides a method for preparing an acrylamide multi-component copolymer, the method comprising: under polymerization reaction conditions, in the presence of an initiator, causing monomers of formula (I), formula (II), formula (III), formula (IV) and formula (V) to undergo a polymerization reaction in a solvent;

[0017]

[0018]

[0019] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group;

[0020] Y is a C1-C10 straight-chain or branched alkylene group;

[0021] X is a halogen;

[0022] M1 is hydrogen or an alkali metal;

[0023] M2 is hydrogen or an alkali metal.

[0024] The third aspect of the present invention provides the application of the aforementioned acrylamide multi-component copolymer or the acrylamide multi-component copolymer prepared by the aforementioned preparation method in water-based drilling fluids.

[0025] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0026] The acrylamide multi-element copolymer of this invention exhibits excellent temperature resistance and can be used as a temperature-resistant thickener for water-based drilling fluids, satisfying the thickening effect of fluids in oil well cementing. It can be used in combination with other drilling fluid additives under conditions of 50-180℃, with a temperature resistance reaching 180℃. Under high-temperature formation conditions, it can maintain the viscosity and flow pattern of the drilling fluid, maintain adhesion without aging, and simultaneously reduce filtration loss.

[0027] The acrylamide multi-element copolymer of the present invention has low cost and simple manufacturing process, and has great economic and promotional value. 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] The first aspect of the present invention provides an acrylamide multi-component copolymer, the acrylamide multi-component copolymer comprising: structural unit A, structural unit B, structural unit C, structural unit D and structural unit E; wherein structural unit A has the structure shown in formula (1), structural unit B has the structure shown in formula (2), structural unit C has the structure shown in formula (3), structural unit D has the structure shown in formula (4), and structural unit E has the structure shown in formula (5).

[0030]

[0031] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group;

[0032] Y is a C1-C10 straight-chain or branched alkylene group;

[0033] X is a halogen;

[0034] M1 is hydrogen or an alkali metal;

[0035] M2 is hydrogen or an alkali metal.

[0036] In this invention, examples of the C1-C10 straight-chain or branched alkyl groups can be, for example, any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, n-heptyl, isoheptyl, 2-methylhexyl, 2-ethylhexyl, 1-methylheptyl, 2-methylheptyl, n-octyl, isooctyl, n-nonyl, isononyl, and 3,5,5-trimethylhexyl.

[0037] In this invention, examples of the C1-C10 straight-chain or branched alkylene groups may be, for example, any one of methylene, 1,2-ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, n-hexylene, isohexylene, n-heptylene, isoheptylene, 2-methylhexylene, 2-ethylhexylene, 1-methylheptylene, 2-methylheptylene, n-octylene, isooctylene, and n-nonylene.

[0038] In some implementations, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each of the components is independently hydrogen or a straight-chain or branched alkyl group of C1-C6, preferably hydrogen or a straight-chain or branched alkyl group of C1-C4; more preferably hydrogen, methyl or ethyl.

[0039] In some preferred embodiments, R1, R2, R3, R4, R5, R6, R9, R 10 R 11 and R 12 Each is independently hydrogen.

[0040] In some preferred embodiments, R7 and R8 are each independently methyl.

[0041] In some embodiments, Y is a C1-C6 straight-chain or branched alkylene group, more preferably a C1-C3 straight-chain or branched alkylene group, and even more preferably methylene or 1,2-ethylene.

[0042] In some embodiments, X is chlorine, bromine, or iodine, more preferably chlorine.

[0043] In some embodiments, M1 is hydrogen or sodium, more preferably hydrogen.

[0044] In some embodiments, M2 is hydrogen or sodium, more preferably hydrogen.

[0045] In some preferred embodiments, the structural unit shown in formula (1) can be a structural unit from acrylamide, the structural unit shown in formula (2) can be a structural unit from acrylic acid, the structural unit shown in formula (3) can be a structural unit from 2-acrylamido-2-methylpropanesulfonic acid, the structural unit shown in formula (4) can be a structural unit from diallyl dimethylammonium chloride, and the structural unit shown in formula (5) can be a structural unit from sodium p-styrenesulfonate.

[0046] In this invention, the polymer is a random copolymer, and the structural units are randomly distributed on the main chain.

[0047] In some implementations, the molar ratio of structural unit A, structural unit B, structural unit C, structural unit D, and structural unit E is 60-96:1-10:1-10:1-10:1-10, for example 60:10:10:10:10, 65:9:9:9:8, 70:9:8:7:6, 75:8:7:5:5, 80:5:5:5:5, 85:5:4:4:2, 88:3:3:3:3, 90:4:3:2:1, 92:2:2:2:2, 94:2:2:1:1.

[0048] In this invention, unless otherwise specified, the molar ratio of each structural unit is calculated by the amount of material fed.

[0049] In some embodiments, the acrylamide multi-component copolymer is a random copolymer.

[0050] In some embodiments, the viscosity-average molecular weight of the acrylamide copolymer is 1 million to 10 million, preferably 5 million to 9 million.

[0051] In this invention, the viscosity-average molecular weight is calculated according to the method in GB12005.10-92.

[0052] In some embodiments, under the condition of hot rolling at 180°C for 16 hours, the apparent viscosity of the acrylamide multi-element copolymer is 27-38 mPa·s, preferably 38 mPa·s; and the plastic viscosity is 15-26 mPa·s, preferably 26 mPa·s.

[0053] In this invention, both apparent viscosity and plastic viscosity are determined according to the method in GB / T 16783.1.

[0054] A second aspect of the present invention provides a method for preparing an acrylamide multi-component copolymer, the method comprising: under polymerization reaction conditions, in the presence of an initiator, causing monomers of formula (I), formula (II), formula (III), formula (IV) and formula (V) to undergo a polymerization reaction in a solvent;

[0055]

[0056] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group;

[0057] Y is a C1-C10 straight-chain or branched alkylene group;

[0058] X is a halogen;

[0059] M1 is hydrogen or an alkali metal;

[0060] M2 is hydrogen or an alkali metal.

[0061] In some implementations, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each of the components is independently hydrogen or a straight-chain or branched alkyl group of C1-C6, preferably hydrogen or a straight-chain or branched alkyl group of C1-C4; more preferably hydrogen, methyl or ethyl.

[0062] In some preferred embodiments, R1, R2, R3, R4, R5, R6, R9, R 10 R 11 and R 12 Each is independently hydrogen.

[0063] In some preferred embodiments, R7 and R8 are each independently methyl;

[0064] In some embodiments, Y is a C1-C6 straight-chain or branched alkylene group, more preferably a C1-C3 straight-chain or branched alkylene group, and even more preferably methylene or 1,2-ethylene.

[0065] In some embodiments, X is chlorine, bromine, or iodine, more preferably chlorine;

[0066] In some embodiments, M1 is hydrogen or sodium, more preferably hydrogen;

[0067] In some embodiments, M2 is hydrogen or sodium, more preferably hydrogen.

[0068] Examples of C1-C10 straight-chain or branched alkyl groups and examples of C1-C10 straight-chain or branched alkylene groups described in the second aspect of the present invention are described in the first aspect of the present invention above, and will not be repeated here.

[0069] In some preferred embodiments, the monomer shown in formula (I) is acrylamide, the monomer shown in formula (II) is acrylic acid, the monomer shown in formula (III) is 2-acrylamido-2-methylpropanesulfonic acid, the monomer shown in formula (IV) is diallyl dimethylammonium chloride, and the monomer shown in formula (V) is sodium p-styrenesulfonate.

[0070] This invention improves the rigidity of the polymer backbone by introducing diallyl dimethyl ammonium chloride to form a cyclic structure. At the same time, it further improves the temperature resistance of the polymer by introducing sodium p-styrene sulfonate.

[0071] In some embodiments, the polymerization reaction conditions include: under a nitrogen atmosphere, a reaction temperature of 30-60°C, preferably 40-50°C; and a reaction time of 4-8 hours, preferably 5-7 hours.

[0072] In some embodiments, the molar ratio of the monomer shown in formula (I), the monomer shown in formula (II), the monomer shown in formula (III), and the monomer shown in formula (IV) is 60-96:1-10:1-10:1-10:1-10, for example 60:10:10:10:10, 65:9:9:9:8, 70:9:8:7:6, 75:8:7:5:5, 80:5:5:5:5, 85:5:4:4:2, 88:3:3:3:3, 90:4:3:2:1, 92:2:2:2:2, 94:2:2:1:1.

[0073] In some embodiments, the initiator is a mixture of ammonium persulfate and sodium sulfite in a weight ratio of 1-3:1, preferably 2:1.

[0074] In some embodiments, the amount of the initiator is 0.01-0.1% of the total weight of the monomers shown in formula (I), (II), (III), and (IV), preferably 0.05%.

[0075] In some embodiments, the solvent is water.

[0076] In some embodiments, the amount of solvent used is 2 to 5 times the total weight of the monomers shown in formula (I), formula (II), formula (III), and formula (IV).

[0077] In some embodiments, the solvent further contains diethylene glycol butyl ether, wherein the amount of diethylene glycol butyl ether is 10-30% of the weight of the solvent, preferably 20%.

[0078] In this embodiment, diethylene glycol butyl ether is used as a dispersant to increase the solubility of the monomer shown in (IV).

[0079] The acrylamide multi-element copolymer of the present invention has low cost and simple manufacturing process, and has great economic and promotional value.

[0080] The third aspect of the present invention provides the application of the aforementioned acrylamide multi-component copolymer or the acrylamide multi-component copolymer prepared by the aforementioned preparation method in water-based drilling fluids.

[0081] In some embodiments, the acrylamide copolymer is used as a thickener for water-based drilling fluids.

[0082] In some embodiments, the acrylamide copolymer can be used in combination with other oil well additives at temperatures ranging from 50 to 180°C.

[0083] The acrylamide multi-element copolymer of this invention exhibits excellent temperature resistance and can be used as a temperature-resistant thickener for water-based drilling fluids, satisfying the thickening effect of fluids in oil well cementing. It can be used in combination with other drilling fluid additives under conditions of 50-180℃, with a temperature resistance reaching 180℃. Under high-temperature formation conditions, it can maintain the viscosity and flow pattern of the drilling fluid, maintain adhesion without aging, and simultaneously reduce filtration loss.

[0084] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0085] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0086] Example 1

[0087] (1) Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 80:5:5:5:5 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is twice the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 20% of the weight of water;

[0088] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0089] (3) Heat the monomer reaction solution obtained in step (2) to 40°C, add ammonium persulfate and sodium sulfite in a weight ratio of 2:1, and add 0.05% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 6 hours.

[0090] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is twice the weight of water.

[0091] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0092] (6) The gel polymer was dried in an oven at 65°C for 24 hours and then pulverized to obtain an acrylamide multi-element copolymer.

[0093] The acrylamide multi-component copolymer obtained in step 6) was analyzed using a TENSOR 27 infrared spectrometer (Bruker, Germany). The infrared spectrum of the acrylamide multi-component copolymer showed that at 1403 cm⁻¹... -1 and 1573cm -1 A stretching vibration peak of the COO-conjugate system exists nearby, and it is located at 614 cm⁻¹. -1 and 1051cm -1 The characteristic vibration peak of S=O exists nearby.

[0094] The viscosity-average molecular weight of the acrylamide copolymer was found to be 8.5 million.

[0095] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0096] Example 2

[0097] (1) Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 80:5:5:10:10 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is 2.5 times the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 25% of the weight of water;

[0098] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0099] (3) Heat the monomer reaction solution obtained in step (2) to 50°C, add ammonium persulfate and sodium sulfite in a weight ratio of 1:1, and add 0.08% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 7 hours.

[0100] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is 3 times the weight of water.

[0101] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0102] (6) The gel polymer was dried in an oven at 75°C for 24 hours and then pulverized to obtain an acrylamide multi-component copolymer.

[0103] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0104] Example 3

[0105] (1) Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 60:10:10:10:10 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is 2.5 times the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 30% of the weight of water;

[0106] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0107] (3) Heat the monomer reaction solution obtained in step (2) to 40°C, add ammonium persulfate and sodium sulfite in a weight ratio of 3:1, and add 0.03% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 8 hours.

[0108] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is 3 times the weight of water.

[0109] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0110] (6) The gel polymer was dried in an oven at 60°C for 24 hours and then pulverized to obtain an acrylamide multi-element copolymer.

[0111] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0112] Example 4

[0113] (1) Acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 75:7:6:6:6 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is 2.5 times the total weight of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 25% of the weight of water;

[0114] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0115] (3) Heat the monomer reaction solution obtained in step (2) to 50°C, add ammonium persulfate and sodium sulfite in a weight ratio of 1:1, and add 0.08% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 7 hours.

[0116] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is 3 times the weight of water.

[0117] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0118] (6) The gel polymer was dried in an oven at 75°C for 24 hours and then pulverized to obtain an acrylamide multi-component copolymer.

[0119] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0120] Example 5

[0121] (1) Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 85:5:5:5:5 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is twice the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 20% of the weight of water;

[0122] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0123] (3) Heat the monomer reaction solution obtained in step (2) to 40°C, add ammonium persulfate and sodium sulfite in a weight ratio of 2:1, and add 0.05% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 5 hours.

[0124] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is twice the weight of water.

[0125] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0126] (6) The gel polymer was dried in an oven at 65°C for 24 hours and then pulverized to obtain an acrylamide multi-element copolymer.

[0127] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0128] Example 6

[0129] (1) Acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate in a molar ratio of 90:4:3:2:1 are dissolved in water, and diethylene glycol butyl ether is added and dissolved completely to obtain a monomer reaction solution; wherein, the amount of water added is 2.5 times the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrene sulfonate, and the amount of diethylene glycol butyl ether added is 20% of the weight of water;

[0130] (2) After adding the monomer reaction solution obtained in step (1) to the reactor, nitrogen gas is purged into the reactor for 15 minutes.

[0131] (3) Heat the monomer reaction solution obtained in step (2) to 40°C, add ammonium persulfate and sodium sulfite in a weight ratio of 2:1, and add 0.05% of the total weight of acrylic acid, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, diallyl dimethylammonium chloride and sodium p-styrenesulfonate. React for 8 hours.

[0132] (4) After the reaction is complete, pour the reaction solution into methanol for sedimentation and washing. The amount of methanol added is 3 times the weight of water.

[0133] (5) After sedimentation, the methanol solution is poured out to obtain a colloidal polymer;

[0134] (6) The gel polymer was dried in an oven at 65°C for 24 hours and then pulverized to obtain an acrylamide multi-element copolymer.

[0135] The acrylamide copolymer obtained in step 6) was dissolved in water to form an aqueous solution with a mass concentration of 1%. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0136] Comparative Example 1

[0137] The anti-temperature thickener for water-based drilling fluid was prepared according to the method of Example 1, except that in step (1), acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and sodium p-styrenesulfonate in a molar ratio of 80:5:5:5 were dissolved in water, and the remaining steps were the same.

[0138] The obtained acrylamide multi-polymer was dissolved in water to form a 1% aqueous solution. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0139] Comparative Example 2

[0140] The anti-temperature thickener for water-based drilling fluid was prepared according to the method of Example 1, except that in step (1), acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and diallyl dimethylammonium chloride in a molar ratio of 80:5:5:5 were dissolved in water, and the other steps were the same.

[0141] The obtained acrylamide multi-polymer was dissolved in water to form a 1% aqueous solution. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0142] Comparative Example 3

[0143] The anti-temperature thickener for water-based drilling fluid was prepared according to the method of Example 1, except that in step (1), acrylamide, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid in a molar ratio of 80:5:5 were dissolved in water, and the other steps were the same.

[0144] The obtained acrylamide multi-polymer was dissolved in water to form a 1% aqueous solution. The aqueous solution was placed in an aging tank and aged at 180°C for 16 hours. Then it was cooled to room temperature, and the viscosity parameters of the aqueous solution were tested using a six-speed rotational viscometer. The results are shown in Table 1.

[0145] Table 1 Viscosity parameters

[0146]

[0147] As shown in Table 1, the high-temperature resistant thickener prepared by the method of the present invention can withstand temperatures up to 180°C. After aging at 180°C for 16 hours, its 1% aqueous solution still has an apparent viscosity greater than 15 mPa·s and a plastic viscosity greater than 10 mPa·s. In contrast, the thickener in the comparative example has an apparent viscosity of no more than 4.5 mPa·s and a plastic viscosity of no more than 3.5 mPa·s after aging at 180°C for 16 hours.

[0148] It is evident that the acrylamide multi-component copolymer of the present invention, when used as a temperature-resistant thickener in water-based drilling fluids, can significantly improve the thickening effect of the drilling fluid.

[0149] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining the 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. An acrylamide multi-polymer used as a thickener in water-based drilling fluids, characterized in that, The acrylamide multi-component copolymer comprises: structural unit A, structural unit B, structural unit C, structural unit D and structural unit E; wherein, structural unit A has the structure shown in formula (1), structural unit B has the structure shown in formula (2), structural unit C has the structure shown in formula (3), structural unit D has the structure shown in formula (4), and structural unit E has the structure shown in formula (5); the molar ratio of structural unit A, structural unit B, structural unit C, structural unit D and structural unit E is 60-96:1-10:1-10:1-10:1-10; The viscosity-average molecular weight of the acrylamide multi-polymer is 1 million to 10 million. The acrylamide copolymer was dissolved in water to form a 1% (w / w) aqueous solution. After aging at 180°C for 16 hours, the solution was cooled to room temperature. The apparent viscosity of the aqueous solution was 18-40 mPa. s; the plastic viscosity of the aqueous solution is 12-26 mPa. s; Equation (1), Equation (2), Equation (3), Equation (4), Equation (5), Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group; Y is a C1-C10 straight-chain or branched alkylene group; X is a halogen; M1 is hydrogen or an alkali metal; M2 is hydrogen or an alkali metal.

2. The acrylamide multi-component copolymer according to claim 1, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C6 straight-chain or branched alkyl group.

3. The acrylamide multi-component copolymer according to claim 2, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C4 straight-chain or branched alkyl group; And / or, Y is a C1-C6 straight-chain or branched alkylene group; And / or, X is chlorine, bromine, or iodine; And / or, M1 is hydrogen or sodium; And / or, M2 is hydrogen or sodium.

4. The acrylamide multi-component copolymer according to claim 3, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each can be independently hydrogen, methyl, or ethyl; And / or, Y is a C1-C3 straight-chain or branched alkylene group; And / or, X is chlorine; And / or, M1 is hydrogen; And / or, M2 is hydrogen.

5. The acrylamide multi-component copolymer according to claim 4, wherein, R1, R2, R3, R4, R5, R6, R9, R 10 R 11 and R 12 Each is independently hydrogen; R7 and R8 are independently methyl groups; And / or, Y is methylene or 1,2-ethylene.

6. The acrylamide multi-component copolymer according to any one of claims 1-5, wherein, The viscosity-average molecular weight of the acrylamide multi-polymer is 5 million to 9 million.

7. A method for preparing an acrylamide multi-component copolymer for use as a thickener in water-based drilling fluids, characterized in that, The preparation method includes: under polymerization reaction conditions, in the presence of an initiator, causing the monomers shown in formula (I), (II), (III), (IV), and (V) to undergo a polymerization reaction in a solvent; the molar ratio of the monomers shown in formula (I), (II), (III), (IV), and (V) is 60-96:1-10:1-10:1-10:1-10:1-10; The initiator is a mixture of ammonium persulfate and sodium sulfite, with a weight ratio of 1-3:1; the amount of the initiator is 0.01-0.1% of the total weight of the monomers shown in formula (I), (II), (III), (IV), and (V). The solvent is water; the amount of the solvent used is 2-5 times the total weight of the monomers shown in formula (I), formula (II), formula (III), formula (IV) and formula (V); The solvent also contains diethylene glycol butyl ether, wherein the amount of diethylene glycol butyl ether is 10-30% of the weight of the solvent; Equation (1), Equation (2), Equation (3), Equation (4), Equation (5), Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C10 straight-chain or branched alkyl group; Y is a C1-C10 straight-chain or branched alkylene group; X is a halogen; M1 is hydrogen or an alkali metal; M2 is hydrogen or an alkali metal.

8. The preparation method according to claim 7, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C6 straight-chain or branched alkyl group.

9. The preparation method according to claim 8, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently hydrogen or a C1-C4 straight-chain or branched alkyl group; And / or, Y is a C1-C6 straight-chain or branched alkylene group; And / or, X is chlorine, bromine, or iodine; And / or, M1 is hydrogen or sodium; And / or, M2 is hydrogen or sodium.

10. The preparation method according to claim 9, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each can be independently hydrogen, methyl, or ethyl; And / or, Y is a C1-C3 straight-chain or branched alkylene group; And / or, X is chlorine; And / or, M1 is hydrogen; And / or, M2 is hydrogen.

11. The preparation method according to claim 10, wherein, R1, R2, R3, R4, R5, R6, R9, R 10 R 11 and R 12 Each is independently hydrogen; R7 and R8 are independently methyl groups; And / or, Y is methylene or 1,2-ethylene.

12. The preparation method according to any one of claims 7-11, wherein, The polymerization reaction conditions include: under a nitrogen atmosphere, a reaction temperature of 30-60℃, and a reaction time of 4-8h.

13. The preparation method according to claim 12, wherein, The polymerization reaction conditions include: under a nitrogen atmosphere, a reaction temperature of 40-50℃, and a reaction time of 5-7h.

14. The application of the acrylamide multi-component copolymer according to any one of claims 1-6 or the acrylamide multi-component copolymer prepared by the preparation method according to any one of claims 7-13 in water-based drilling fluids.

15. The application according to claim 14, wherein, The acrylamide multi-polymer is used as a thickener for water-based drilling fluids.

16. The application according to claim 15, wherein, The acrylamide multi-polymer can be used in combination with other oil well additives at temperatures ranging from 50 to 180°C.

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