High-Temperature Retarder for Oil Well Cement, its Preparation Method and Application

Abstract

This invention discloses a high-temperature resistant retarder for oil well cement, its preparation method, and its application. The retarder comprises a sulfonic acid-carboxylic acid polymer with cationic clusters on its molecular chain, formed by the clustering of unsaturated carboxylic acid monomers, 2-methyl-2-acrylamidopropanesulfonic acid, and ammonium salt cationic monomers; wherein the mass ratio of ammonium salt cationic monomers, unsaturated carboxylic acid monomers, and 2-methyl-2-acrylamidopropanesulfonic acid is 17:(19-30):(52-64). The retarder of this invention uses a clustered distribution method to distribute the ammonium salt cationic monomers within the molecular structure of the sulfonic acid-carboxylic acid polymer with cationic clusters on its molecular chain, and then combines it with a strong chelating agent containing Ca... 2+ The retarder prepared by this invention is ethylenediaminetetramethylenephosphonate sodium. The retarder prepared by this invention has a temperature resistance of 240℃, and when the retarder dosage is 2%–4%, the thickening time of the cement slurry at 240℃ is between 343 and 600 minutes. After curing the cement slurry system for 24 hours, the compressive strength of the cement stone reaches over 26.2 MPa, which can meet the requirements of ultra-high temperature cementing.

Description

TECHNICAL FIELD

[0001] The present application relates to a retarding agent for high-temperature oil well cement and a preparation method and application thereof. BACKGROUND

[0002] With the progress of drilling technology and the continuous deepening of oil field exploration and development, high-temperature deep wells and ultra-deep wells with bottom hole temperature exceeding 200℃ are gradually increasing. The complex well conditions of deep wells and ultra-deep wells bring new challenges to cementing technology, and at the same time, higher performance requirements are put forward for cementing fluid, i.e. cement slurry and its additives. Cementing is the process of lowering casing into the wellbore, pumping cementing fluid, usually cement slurry, into the annulus between the casing and the well wall through the casing, and then waiting for the cementing fluid to set until it solidifies. Cementing mainly plays the role of protecting and supporting the casing and sealing the oil and gas layer, and is the basic guarantee for safe and efficient development of oil and gas. In order to ensure the safety of cementing construction, a retarding agent is usually added to the cement slurry. The commonly used high-temperature retarding agent is usually a synthetic high molecular polymer, which can make the thickening time of the cement slurry 1-2 hours longer than the pumping construction time.

[0003] Yan S, Wu Y, Yang S, Yang K, Wang Y, Tang B. Synthesis and performance evaluation of high-temperature retarding agent AMCT [J]. Fine Chemicals, 2017, 34(05): 562-568. A high-temperature retarding agent (AMCT) was synthesized using sodium methacryl sulfonate (MAS), hydrophilic long-chain olefin monomer (CL), acrylic acid (AA) and allyl trimethyl ammonium chloride (TMAAC) as raw materials. The maximum applicable temperature can only reach 200℃.

[0004] Patent CN109824822B uses carboxylic acid monomer, ammonium salt cationic monomer and sulfonate monomer to prepare high-temperature retarding agent, and the applicable temperature range is only 50-180℃.

[0005] Patent CN109824823B uses carboxylic acid monomer, ammonium salt cationic monomer, sulfonate monomer and N,N-dimethyl acrylamide to prepare high-temperature retarding agent, and the maximum applicable temperature can only reach 220℃.

[0006] Patent CN111662409B obtains a high-temperature oil well cement retarding agent by aqueous solution polymerization of 2-acrylamido-2-methylpropanesulfonic acid, unsaturated carboxylic acid monomer, steric hindrance functional monomer and cationic functional monomer. The maximum applicable temperature can only reach 150℃, the "bulging" and "core" phenomena of cement slurry in the temperature range of 120-150℃ can be inhibited, the strength development of cement stone is not affected, and the comprehensive performance of cement slurry is good.

[0007] Feng Dejie, Yang Qizhen, Cao Chengzhang. Synthesis and performance of oil well cement retarder for large temperature difference [J]. Synthetic Chemistry, 2023, 31(02): 93-100, A new oil well cement retarder for large temperature difference was synthesized by using 2-methyl-2-propenamide propyl sulfonic acid (AMPS), acrylic acid (AA), methyl methacryloyl ethyl trimethyl ammonium chloride (DMC) and long-chain quaternary ammonium salt (DBrC) as monomers. It can only meet the requirements of large temperature difference cementing construction of 60-150℃.

[0008] Wu Yanhua. Synthesis and retarding mechanism of high-temperature resistant zwitterionic oil well cement retarder, Synthetic Chemistry, 2023, 31(2), 101-108, A high-temperature resistant zwitterionic polymer oil well cement retarder HFB-2 was synthesized by aqueous solution polymerization using acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), maleic anhydride (MAH) and dimethyl diallyl ammonium chloride (DMDAAC) as polymerization monomers. The highest temperature it can be used is only 220℃.

[0009] Yu Yongjin, Xue Yukong, Xia Xiujian, Wang Chengwen, Liu Huiting, Meng Renzhou, Chen Zehua, Liu Benuo. Development and evaluation of a 240℃ ultra-high temperature cementing retarder [J]. Natural Gas Industry, 2023, 43(03): 107-112, A new four-component ultra-high temperature zwitterionic retarder (HTRP) was prepared using strong adsorption cationic monomer (CP-22) and high-temperature resistant monomers such as unsaturated carboxylic acid. The cement slurry thickening time at 240℃ ultra-high temperature cycle is 401min. However, the inventors believe that in this scheme, the cationic monomer is directly polymerized with other monomers, and the cation is dispersedly distributed in the molecular chain, and the adsorption performance is not as expected.

[0010] In patent CN109503781B, the aqueous solution of itaconic acid and 2-acrylamide-2-methylpropanesulfonic acid is mixed with inorganic non-metallic materials and silane coupling agent, and the reaction is carried out in the presence of initiator to obtain an inorganic-organic polymer oil well cement retarder. The highest temperature it can be used is only 230℃.

[0011] Peng Zhigang, Zhang Bojian, Feng Qi, Huang Rengu, Zhang Jian, Liu Gaofeng. Preparation and performance of polymer intercalated montmorillonite composite high temperature retarder [J]. Journal of Silicate, 2018, 46(08): 1087-1094, A organic-inorganic composite high temperature retarder (HTR-5) was synthesized by using 2-acrylamide-2-methylpropanesulfonic acid (AMPS), acrylic acid (AA), and diallyl dimethyl ammonium chloride (DMDAAC) as monomers, and montmorillonite as active polymer filler by solution polymerization in situ intercalation method. The temperature range it can be used is only 150-180℃.

[0012] In summary, the commonly used anti-high-temperature retarder is a synthetic high-molecular polymer, but the anti-temperature capacity of the polymer molecular chain is limited. SUMMARY

[0013] To solve at least one of the above technical problems, increase the selection space of the retarder for oil well cement to be applicable to more application scenarios, the application provides a retarder for high-temperature resistant oil well cement with good temperature resistance and a preparation method thereof.

[0014] As an aspect of the application, a retarder for high-temperature resistant oil well cement is provided, which comprises a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain, which is polymerized from an unsaturated carboxylic acid monomer, 2-methyl-2-acrylamidopropyl sulfonic acid and an ammonium salt cationic monomer in a cluster form; the mass ratio of the ammonium salt cationic monomer, the unsaturated carboxylic acid monomer and the 2-methyl-2-acrylamidopropyl sulfonic acid is 17:(19-30):(52-64).

[0015] In a specific embodiment, the retarder further comprises ethylenediamine tetramethylene phosphonic acid sodium.

[0016] Further, the mass of the ethylenediamine tetramethylene phosphonic acid sodium accounts for 15-30% of the mass of the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

[0017] In a specific embodiment, the unsaturated carboxylic acid monomer is selected from one of itaconic acid, maleic acid, fumaric acid and acrylic acid.

[0018] In a specific embodiment, the ammonium salt cationic monomer is selected from methacryloyloxyethyl trimethyl ammonium chloride or acryloyloxyethyl trimethyl ammonium chloride.

[0019] As another aspect of the application, a preparation method of the above-mentioned retarder for high-temperature resistant oil well cement is provided, which uses cluster distribution to distribute the ammonium salt cationic monomer in the molecular structure of the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

[0020] Specifically, the method comprises the following steps:

[0021] S1, preparation of solution A

[0022] Water is added to dissolve the ammonium salt cationic monomer, and a part of the initiator is added dropwise under stirring, and then the solution is heated to obtain solution A;

[0023] S2, preparation of solution B

[0024] Under heating and stirring, water is added to dissolve the unsaturated carboxylic acid monomer and 2-methyl-2-acrylamidopropyl sulfonic acid, and the pH value of the solution is adjusted to obtain solution B;

[0025] S3, preparation of polymer

[0026] S3, preparation of polymer

[0027] S4, preparation of retarder

[0028] S4, preparation of retarder

[0029] The water solution of initiator in S1 or S3 refers to dissolving initiator in water accounting for 60% of the mass of the ammonium salt cationic monomer.

[0030] In specific embodiments, the reaction temperature in S1 is 60-65℃, and the reaction time is 0.5-1h.

[0031] In specific embodiments, the pH value of solution B in S2 is 2-4.

[0032] In specific embodiments, the temperature in S3 is raised to 60-70℃ before being added to solution A prepared in S1.

[0033] In specific embodiments, the reflux reaction time in S3 is 6-8h.

[0034] In specific embodiments, the mass of initiator is 1.5%-3% of the mass of the ammonium salt cationic monomer.

[0035] Further, the initiator is selected from ammonium persulfate or potassium persulfate.

[0036] As a further aspect of the present application, it relates to a cement slurry for well cementation, wherein the above-mentioned retarder for high-temperature oil well cement is used in the cementing fluid.

[0037] As a further aspect of the present application, it relates to a process for well cementation of oil and gas wells, wherein the above-mentioned cement slurry for well cementation is used.

[0038] The present application improves the adsorption capacity of molecular chains on the surface of cement particles, develops a super-high-temperature retarder, forms cation clusters on the molecular chains of the generated polymer, and changes the dispersion distribution of cations in the molecular chains to clustered distribution, thereby increasing the adsorption capacity of molecular chains on the surface of cement particles. 2+ The present application also compounding sodium ethylenediaminetetramethylene phosphonate with strong Ca

[0039] The retarder prepared by the application can resist 240 DEG C, when the retarder is added in an amount of 2% to 4%, the thickening time of the cement slurry at 240 DEG C is between 343 min and 600 min, and the compressive strength of the cement stone after the cement slurry system is cured for 24 h is more than 26.2 MPa, which can meet the requirements of super-high-temperature well cementation.

[0040] Other features and advantages of the present application will be set forth in the following specification, and in part will be apparent from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims. DETAILED DESCRIPTION

[0041] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with specific embodiments. The materials mainly involved in the embodiments of the application are shown in Table 1 below, and other materials not shown are all conventional commercially available products.

[0042] Table 1: Material source explanation

[0043]

[0044] In addition, the 191230 high-low temperature double-cylinder pressurization thickening instrument used in the embodiments of the application is from Liaoning Besrue Petroleum Equipment Manufacturing Co., Ltd., and the 4265 type ultrasonic cement stone strength analyzer is from the United States Quedel Instrument Company.

[0045] The inventors continuously optimize the composition and preparation method of the retarder through a large number of experimental researches, and give Examples 1 to 8.

[0046] Example 1

[0047] The retarder of the embodiment is prepared by the following steps:

[0048] S1, preparation of solution A

[0049] 17g of methacryloyloxyethyl trimethyl ammonium chloride (DMC, ammonium salt cationic monomer) is dissolved in 30g of deionized water, 50wt% of an aqueous solution of ammonium persulfate is added dropwise under the condition that the stirring speed is 200r / min, after the dropwise addition is completed, the temperature is raised to 65 DEG C, and the reaction is carried out for 0.5h to obtain solution A;

[0050] S2, preparation of solution B

[0051] 29g of itaconic acid (IA) and 54g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) are dissolved in 136g of deionized water, after stirring at 45 DEG C for 15 min, the pH of the solution is adjusted to 3 using a saturated sodium hydroxide solution to obtain solution B;

[0052] S3, preparation of polymer

[0053] After solution B prepared in S2 was stirred at 45°C for 30 min, the temperature was raised to 65°C, and solution B was added into solution A prepared in S2. The remaining 50wt% ammonium persulfate aqueous solution was added dropwise under stirring at 200r / min, and the reaction was refluxed for 8h to prepare a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

[0054] S4, preparation of retarder

[0055] After the polymer in S3 was cooled to room temperature, 15% of the mass of the polymer of ethylenediamine tetramethylene phosphonic acid sodium was added and stirred uniformly to prepare a retarder.

[0056] The aqueous solution of the initiator in S1 and / or S3 refers to 0.51g of ammonium persulfate (initiator) dissolved in 10.2g of deionized water.

[0057] The viscosity of the retarder prepared in this example is 480mPa·s, and the relative molecular weight is 19820.

[0058] Example 2

[0059] The retarder of this example was prepared by the following steps:

[0060] S1, preparation of solution A

[0061] 17g of acryloyloxyethyl trimethyl ammonium chloride (DAC, ammonium salt cationic monomer) was dissolved in 30g of deionized water, and 50wt% potassium persulfate aqueous solution was added dropwise under stirring at 200r / min. After the dropwise addition was completed, the temperature was raised to 60°C, and the reaction was carried out for 1h to obtain solution A.

[0062] S2, preparation of solution B

[0063] 19g of maleic acid (MA) and 64g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) were dissolved in 136g of deionized water. After stirring at 45°C for 15min, the pH of the solution was adjusted to 2.4 using saturated sodium hydroxide solution to obtain solution B.

[0064] S3, preparation of polymer

[0065] After the solution B prepared in S2 is stirred at 45°C for 30 min, the temperature is raised to 60°C, and the solution B is added to the solution A prepared in S2, and the remaining 50wt% aqueous solution of potassium persulfate is added dropwise under stirring at 200r / min, and the reaction is refluxed for 6.5h to prepare the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain;

[0066] S4, preparation of the retarder

[0067] After the polymer in S3 is cooled to room temperature, 20% of the mass of the polymer of ethylenediamine tetramethylene phosphonic acid sodium is added, and stirred uniformly to prepare the retarder;

[0068] The aqueous solution of the initiator in S1 and / or S3 refers to 0.31g of potassium persulfate (initiator) dissolved in 10.2g of deionized water.

[0069] The viscosity of the retarder prepared in this example is 600mPa·s, and the relative molecular weight is 30215.

[0070] Example 3

[0071] The retarder of this example is prepared by the following steps:

[0072] S1, preparation of solution A

[0073] 17g of methacryloyloxyethyl trimethyl ammonium chloride (DMC, ammonium salt cationic monomer) is dissolved in 30g of deionized water, and 50wt% aqueous solution of ammonium persulfate is added dropwise under stirring at 200r / min, after the dropwise addition is completed, the temperature is raised to 65°C, and the reaction is carried out for 0.6h to obtain solution A;

[0074] S2, preparation of solution B

[0075] 20g of fumaric acid (FA) and 60g of 2-methyl-2-acrylamidopropyl sulfonic acid (AMPS) are dissolved in 136g of deionized water, after stirring at 45°C for 15min, the pH of the solution is adjusted to 4 using saturated sodium hydroxide solution to obtain solution B;

[0076] S3, preparation of the polymer

[0077] After the solution B prepared in S2 is stirred at 45°C for 30 min, the temperature is raised to 70°C, and the solution B is added to the solution A prepared in S2, and the remaining 50wt% aqueous solution of potassium persulfate is added dropwise under stirring at 200r / min, and the reaction is refluxed for 7.5h to prepare the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain;

[0078] S4, preparation of the retarder

[0079] After the polymer in S3 is cooled to room temperature, 30% of the mass of the polymer of ethylenediamine tetramethylene phosphonic acid sodium is added, stirred uniformly, and a retarder is prepared;

[0080] The aqueous solution of potassium persulfate in S1 and / or S3 refers to 0.34 g of ammonium persulfate (initiator) dissolved in 10.2 g of deionized water.

[0081] The viscosity of the retarder prepared in this example is 422 mPa·s, and the relative molecular weight is 12589.

[0082] Example 4

[0083] The retarder of this example is prepared by the following steps:

[0084] Preparation of solution A in S1

[0085] 17 g of acryloyloxyethyl trimethyl ammonium chloride (DAC, cationic monomer of ammonium salt) is dissolved in 30 g of deionized water, 50 wt% of the aqueous solution of potassium persulfate is added dropwise under the condition that the stirring speed is 200 r / min, after the dropwise addition is completed, the temperature is raised to 62℃, and the reaction is carried out for 0.8 h to obtain solution A;

[0086] Preparation of solution B in S2

[0087] 30 g of acrylic acid (AA) and 64 g of 2-methyl-2-acrylamido propane sulfonic acid (AMPS) are dissolved in 136 g of deionized water, after stirring at 45℃ for 15 min, the pH of the solution is adjusted to 2.5 using saturated sodium hydroxide solution to obtain solution B;

[0088] Preparation of the polymer in S3

[0089] After solution B prepared in S2 is stirred at 45℃ for 30 min, the temperature is raised to 63℃, and it is added to solution A prepared in S2, 50 wt% of the remaining aqueous solution of potassium persulfate is added dropwise under the condition that the stirring speed is 200 r / min, and the reaction is carried out for 6 h under reflux to prepare a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain;

[0090] Preparation of the retarder in S4

[0091] After the polymer in S3 is cooled to room temperature, 30% of the mass of the polymer of ethylenediamine tetramethylene phosphonic acid sodium is added, stirred uniformly, and a retarder is prepared;

[0092] The aqueous solution of potassium persulfate in S1 and / or S3 refers to 0.34 g of ammonium persulfate (initiator) dissolved in 10.2 g of deionized water.

[0093] The viscosity of the retarder prepared in this embodiment is 570 mPa·s, and the relative molecular weight is 27153.

[0094] Example 5

[0095] The retarder of this embodiment is prepared by the following steps:

[0096] S1, preparation of solution A

[0097] 17 g of methacryloyloxyethyl trimethyl ammonium chloride (DMC, cationic monomer of ammonium salt) is dissolved in 30 g of deionized water, and 50 wt% of ammonium persulfate aqueous solution is added dropwise under the condition that the stirring speed is 200 r / min. After the dropwise addition is completed, the temperature is raised to 63°C, and the reaction is carried out for 1 h to obtain solution A.

[0098] S2, preparation of solution B

[0099] 25 g of itaconic acid (IA) and 52 g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) are dissolved in 136 g of deionized water. After stirring at 45°C for 15 min, the pH of the solution is adjusted to 3.8 using saturated sodium hydroxide solution to obtain solution B.

[0100] S3, preparation of polymer

[0101] After solution B prepared in S2 is stirred at 45°C for 30 min, the temperature is raised to 66°C, and it is added to solution A prepared in S2. Under the condition that the stirring speed is 200 r / min, the remaining 50 wt% of ammonium persulfate aqueous solution is added dropwise, and the reaction is carried out under reflux for 7 h to prepare a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

[0102] S4, preparation of retarder

[0103] After the polymer in S3 is cooled to room temperature, 18% of the mass of the polymer of ethylenediamine tetramethylene phosphonic acid sodium is added and stirred uniformly to prepare the retarder.

[0104] The aqueous solution of the initiator in S1 and / or S3 refers to the preparation of 0.48 g of ammonium persulfate (initiator) dissolved in 10.2 g of deionized water.

[0105] The viscosity of the retarder prepared in this embodiment is 750 mPa·s, and the relative molecular weight is 43256.

[0106] Example 6

[0107] The retarder of this embodiment is prepared by the following steps:

[0108] S1, preparation of solution A

[0109] 17g of acryloyloxyethyltrimethylammonium chloride (DAC, an ammonium salt cationic monomer) was dissolved in 30g of deionized water. Under the condition of stirring at 200r / min, 50wt% potassium persulfate aqueous solution was added dropwise. After the addition was completed, the temperature was raised to 61℃ and the reaction was carried out for 0.5h to obtain solution A.

[0110] S2, Preparation of Solution B

[0111] 19g of maleic acid (MA) and 52g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) were dissolved in 136g of deionized water. After stirring at 45°C for 15min, the pH of the solution was adjusted to 2.2 using saturated sodium hydroxide solution to obtain solution B.

[0112] S3, Polymer Formulation

[0113] The solution B obtained in S2 was stirred at 45°C for 30 min, and then the temperature was raised to 68°C. It was added to the solution A obtained in S2. The remaining 50 wt% potassium persulfate aqueous solution was added dropwise under the condition of stirring speed of 200 r / min. The mixture was refluxed for 6 h to obtain a sulfonic acid-carboxylic acid polymer with cation clusters on the molecular chain.

[0114] S4. Preparation of retarder

[0115] After the polymer in S3 has cooled to room temperature, sodium ethylenediaminetetramethylenephosphonate (EDTA) is added at 28% of the polymer mass and stirred until homogeneous to obtain a retarder.

[0116] The potassium persulfate aqueous solution mentioned in S1 and / or S3 refers to the solution prepared by dissolving 0.29g of potassium persulfate (initiator) in 10.2g of deionized water.

[0117] The retarder prepared in this embodiment has a viscosity of 534 mPa·s and a relative molecular weight of 23565.

[0118] Example 7

[0119] The retarder in this embodiment is prepared through the following steps:

[0120] S1, Preparation of solution A

[0121] 17g of methacryloyloxyethyltrimethylammonium chloride (DMC, an ammonium salt cationic monomer) was dissolved in 30g of deionized water. Under the condition of stirring at 200r / min, 50wt% aqueous solution of ammonium persulfate was added dropwise. After the addition was completed, the temperature was raised to 64℃ and the reaction was carried out for 0.9h to obtain solution A.

[0122] S2, Preparation of Solution B

[0123] 24g of fumaric acid (FA) and 60g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) were dissolved in 136g of deionized water. After stirring at 45°C for 15min, the pH of the solution was adjusted to 3.5 using saturated sodium hydroxide solution to obtain solution B.

[0124] S3, Polymer Formulation

[0125] Solution B obtained in S2 was stirred at 45°C for 30 min, then the temperature was raised to 62°C and added to solution A obtained in S2. Under the condition of stirring at 200 r / min, the remaining 50 wt% aqueous solution of ammonium persulfate was added dropwise, and the reaction was refluxed for 7.5 h to obtain a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

[0126] S4. Preparation of retarder

[0127] After the polymer in S3 has cooled to room temperature, add sodium ethylenediaminetetramethylenephosphonate (EDTA) at 26% of the polymer mass, stir well, and the retarder is obtained.

[0128] The aqueous solution of the initiator mentioned in S1 and / or S3 refers to the solution prepared by dissolving 0.26g of ammonium persulfate (initiator) in 10.2g of deionized water.

[0129] The retarder prepared in this embodiment has a viscosity of 492 mPa·s and a relative molecular weight of 20156.

[0130] Example 8

[0131] The retarder in this embodiment is prepared through the following steps:

[0132] S1, Preparation of solution A

[0133] 17g of acryloyloxyethyltrimethylammonium chloride (DAC, an ammonium salt cationic monomer) was dissolved in 30g of deionized water. Under the condition of stirring at 200r / min, 50wt% potassium persulfate aqueous solution was added dropwise. After the addition was completed, the temperature was raised to 60℃ and the reaction was carried out for 0.7h to obtain solution A.

[0134] S2, Preparation of Solution B

[0135] Dissolve 30g of acrylic acid (AA) and 52g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) in 136g of deionized water. Stir at 45°C for 15min, then adjust the pH of the solution to 2 using saturated sodium hydroxide solution to obtain solution B.

[0136] S3, Polymer Formulation

[0137] Solution B obtained in S2 was stirred at 45°C for 30 min, then the temperature was raised to 62°C and added to solution A obtained in S2. Under the condition of stirring at 200 r / min, the remaining 50 wt% potassium persulfate aqueous solution was added dropwise, and the reaction was refluxed for 6.5 h to obtain a sulfonic acid-carboxylic acid polymer with cation clusters on the molecular chain.

[0138] S4. Preparation of retarder

[0139] After the polymer in S3 has cooled to room temperature, add sodium ethylenediaminetetramethylenephosphonate (EDTA) at 26% of the polymer mass, stir well, and the retarder is obtained.

[0140] The potassium persulfate aqueous solution mentioned in S1 and / or S3 refers to the solution prepared by dissolving 0.41g of potassium persulfate (initiator) in 10.2g of deionized water.

[0141] The retarder prepared in this embodiment has a viscosity of 450 mPa·s and a relative molecular weight of 15421.

[0142] The following are comparative examples 1 to 5, made by the inventors through a series of changes to the experimental conditions during their experimental investigations.

[0143] Comparative Example 1

[0144] The retarder in this comparative example was prepared by the following steps:

[0145] Dissolve 0.51 g of ammonium persulfate (initiator) in 10.2 g of deionized water to obtain an aqueous solution of ammonium persulfate;

[0146] 17g of methacryloyloxyethyltrimethylammonium chloride (DMC, an ammonium salt cationic monomer), 29g of itaconic acid (IA) and 54g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) were dissolved in 136g of deionized water. After stirring at 45°C for 30min, the pH of the solution was adjusted to 3 using saturated sodium hydroxide solution to obtain solution A.

[0147] The temperature of the prepared solution A was raised to 65℃, and then all of the aqueous solution of ammonium persulfate was added dropwise under the condition of stirring speed of 200 r / min. The mixture was refluxed for 8 hours to obtain the polymer.

[0148] After the polymer is cooled to room temperature, sodium ethylenediaminetetramethylenephosphonate (EDTA) is added to the polymer at a mass of 15%, and the mixture is stirred until homogeneous to obtain a retarder.

[0149] The retarder prepared in this comparative example has a viscosity of 468 mPa·s and a relative molecular weight of 19685.

[0150] Comparative Example 2

[0151] The retarder in this comparative example was prepared by the following steps:

[0152] Dissolve 0.31 g of potassium persulfate (initiator) in 10.2 g of deionized water to obtain an aqueous solution of potassium persulfate;

[0153] 17g of acryloyloxyethyltrimethylammonium chloride (DAC, an ammonium salt cationic monomer), 19g of maleic acid (MA) and 64g of 2-methyl-2-acrylamidopropanesulfonic acid (AMPS) were dissolved in 136g of deionized water. After stirring at 45°C for 30min, the pH of the solution was adjusted to 2.4 using saturated sodium hydroxide solution to obtain solution A.

[0154] The temperature of the prepared solution A was raised to 60℃, and then all the potassium persulfate aqueous solution was added dropwise under the condition of stirring speed of 200 r / min. The mixture was refluxed for 6.5 h to obtain the polymer.

[0155] After the polymer is cooled to room temperature, sodium ethylenediaminetetramethylenephosphonate (EDTA) is added to the polymer at a mass of 20% and stirred until homogeneous to obtain a retarder.

[0156] The retarder prepared in this comparative example has a viscosity of 591 mPa·s and a relative molecular weight of 30001.

[0157] Comparative Example 3

[0158] The difference from Example 3 is that "17g of dimethyl diallyl ammonium chloride (DMDAAC)" is used instead of "17g of methacryloyloxyethyl trimethyl ammonium chloride (DMC)" in S1.

[0159] The retarder prepared in this comparative example has a viscosity of 353 mPa·s and a relative molecular weight of 10125.

[0160] Comparative Example 4

[0161] The difference from Example 4 is that “64g sodium styrene sulfonate (SSS)” is used instead of “64g 2-methyl-2-acrylamidopropanesulfonic acid (AMPS)” in Example 2.

[0162] The retarder prepared in this comparative example has a viscosity of 732 mPa·s and a relative molecular weight of 39524.

[0163] Comparative Example 5

[0164] The difference from Example 5 is that S4 is omitted.

[0165] The retarder prepared in this comparative example has a viscosity of 615 mPa·s and a relative molecular weight of 30256.

[0166] To clearly illustrate the differences between Comparative Examples 1-5 and Examples 1-8, the inventors provide a brief explanation below:

[0167] Comparative Examples 1-2: Ammonium cationic monomers did not form cationic clusters in the molecular structure of the retarder; Comparative Examples 3-4: Monomers of the same class were replaced; Comparative Example 5: No compounding with organophosphonates was performed.

[0168] The inventors prepared cement slurry according to "GB / T 19139-2012 Test Method for Cement in Oil Wells" using the retarders prepared in Examples 1-8 and Comparative Examples 1-5. The specific steps of the cement slurry formulation are as follows: Grade G oil well cement + 50% (cement mass) quartz sand (200 mesh) + x% (cement mass) retarder + y% water, with a liquid-to-solid ratio of 0.44.

[0169] The thickening time of the prepared cement slurry was tested according to ANSI / API Recommended Practice 10B-5.

[0170] Simultaneously, the inventors also tested the highest temperature the retarder could withstand before its failure. For example, the retarding effect of the retarder was tested at 150℃. If the thickening curve was normal and no abnormal phenomena such as bulging, core formation, or over-retardation occurred, the test temperature was increased to 160℃ and the test continued in this manner until the retarder failed. The last test temperature before the retarder failed was recorded as the test temperature (i.e., the highest temperature), and the compressive strength of the cement paste was tested at this test temperature. The above test results are recorded in Table 2 below.

[0171] Table 2: Performance Test Results of Retarder

[0172]

[0173] As can be seen from the data in Table 2, the retarders prepared according to Examples 1-8 of this invention all achieve a temperature resistance of 240℃, which is superior to the retarders prepared in the comparative examples. Therefore, the inventors, through data analysis, believe that the improved temperature resistance is mainly due to the transformation of the cationic monomers in the polymer molecular structure from a traditional dispersed distribution to a clustered distribution.

[0174] The experimental data recorded in Table 2 show that when cement slurry is prepared using the retarders prepared in Examples 1-8, the initial consistency of the cement slurry is below 25 Bc, and the compressive strength of the cement stone after 24 hours is >26.2 MPa, meeting the actual cementing requirements. Therefore, after a series of analyses, the inventors believe that when preparing the retarder using the method of this invention, the thickening time of the cement slurry can be changed by adjusting the raw material ratio and reaction conditions.

[0175] Compared to Examples 1-2, the performance of the retarders in Comparative Examples 1-2 was generally inferior. It is inferred that this may be because, during the preparation of the retarder materials in Comparative Examples 1-2, the ammonium cationic monomers did not form cationic clusters in the retarder molecular structure. However, cations existing in cluster form have a more stable structure and are less susceptible to damage from high temperatures. Therefore, the retarders prepared in Examples 1-2 have stronger high-temperature resistance and higher compressive strength.

[0176] Based on Comparative Example 3 and Example 3 and their test results: In Comparative Example 3, the use of dimethyl diallyl ammonium chloride with two double bonds in its molecular structure led to its tendency to self-polymerize and form a cyclic structure during preparation. This prevented the formation of copolymerizable cationic clusters, which could not effectively connect to the polymer molecular chain, thus hindering the improvement of the polymer's temperature resistance. Therefore, the inventors believe that when preparing retarder, methacryloyloxyethyltrimethylammonium chloride or acryloyloxyethyltrimethylammonium chloride are more recommended as the ammonium salt cationic monomers.

[0177] Based on the performance test data in Table 2, we can also find that Comparative Example 4 has the lowest compressive strength. Therefore, the inventors believe that the possible reason is that Comparative Example 4 used sodium styrene sulfonate with rigid groups when preparing the retarder, but this substance is not conducive to the stability of the cement paste system and the development of early strength of cement stone.

[0178] Example 5, compared to Comparative Example 5, incorporates an organophosphonate. This organophosphonate possesses C-P-O bond electronic ligands, which can bind with Ca in cement. 2+ Al 3+ They form a strong chelate structure that is not easily destroyed at high temperatures, which can synergistically enhance the application temperature range and hydration inhibition ability of the retarder with the polymer.

[0179] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All modifications or applications made in accordance with the above embodiments are within the scope of protection of this technical solution.

[0180] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A retarder for high temperature oil well cement, characterized by, The retarder comprises a sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain, which is polymerized from unsaturated carboxylic acid monomers, 2-methyl-2-propenoyl amido propane sulfonic acid and ammonium salt cationic monomers in a clustered form; the mass ratio of the ammonium salt cationic monomers, the unsaturated carboxylic acid monomers and the 2-methyl-2-propenoyl amido propane sulfonic acid is 17: (19-30): (52-64); the ammonium salt cationic monomers are selected from methacryloyloxyethyl trimethyl ammonium chloride or acryloyloxyethyl trimethyl ammonium chloride; The retarder further comprises sodium ethylenediaminetetramethylene phosphonate.

2. The set retarding agent for high temperature oil well cement according to claim 1, characterized by, The mass of the sodium ethylenediaminetetramethylene phosphonate accounts for 15-30% of the mass of the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain.

3. The set retarding agent for high temperature oil well cements of claim 1, wherein, The unsaturated carboxylic acid monomers are selected from one of itaconic acid, maleic acid, fumaric acid and acrylic acid.

4. A method for preparing the retarder for high temperature oil well cement according to any one of claims 1 to 3, characterized by, The method uses a clustered distribution to distribute the ammonium salt cationic monomers in the molecular structure of the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain; the method comprises the following steps: S1, preparation of solution A Water is added to dissolve the ammonium salt cationic monomers, and a part of the aqueous solution of initiator is added dropwise under stirring, after the dropwise addition is completed, the reaction is carried out by increasing the temperature, and solution A is obtained; S2, preparation of solution B Under the condition of heating and stirring, water is added to dissolve the unsaturated carboxylic acid monomers and 2-methyl-2-propenoyl amido propane sulfonic acid, and the pH value of the solution is adjusted, and solution B is obtained; S3, preparation of polymer Solution B prepared in S2 is stirred at a constant temperature, and then added into solution A prepared in S1 after the temperature is increased, the remaining aqueous solution of initiator is continuously added dropwise under stirring, and the reflux reaction is carried out, and the sulfonic acid-carboxylic acid polymer with cationic clusters on the molecular chain is prepared; S4, preparation of retarder After the polymer prepared in S3 is cooled to room temperature, sodium ethylenediaminetetramethylene phosphonate is added, and stirred uniformly, and the retarder is prepared; The aqueous solution of initiator in S1 or S3 refers to the preparation of the initiator dissolved in water accounting for 60% of the mass of the ammonium salt cationic monomers.

5. The method of preparing a set retarding agent for high temperature oil well cements according to claim 4, characterized in that, In S1, the reaction temperature is 60-65°C, and the reaction time is 0.5-1h.

6. The method of preparing a set retarding agent for high temperature oil well cements according to claim 4, characterized in that, In S2, the pH value of solution B is 2-4.

7. The method of preparing a set retarding agent for high temperature oil well cements according to claim 4, characterized in that, In S3, the temperature is increased to 60-70°C before being added into solution A prepared in S1.

8. The method of preparing a set retarding agent for high temperature oil well cements according to claim 4, characterized in that, In S3, the reflux reaction time is 6-8h.

9. The method of preparing a set retarding agent for high temperature oil well cements according to claim 4, characterized in that, The mass of the initiator is 1.5%-3% of the mass of the ammonium salt cationic monomers.

10. The method of preparing a set retarding agent for high temperature oil well cements according to claim 9, characterized in that, The initiator is selected from ammonium persulfate or potassium persulfate.

11. A cement slurry, characterized in that, The cementing slurry uses the retarder for high-temperature oil well cement or the retarder for high-temperature oil well cement prepared by the method of any one of claims 4-10.

12. An oil and gas well cementing process, characterized by, The oil and gas well cementing process uses the cementing slurry of claim 11.

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