Cement paste retarder, its preparation method and application

Abstract

The application provides a cement slurry retarder and a preparation method and application thereof, and the preparation method comprises the following steps: adding an initiator to a raw material solution, and then heating to 60-70 DEG C to initiate a polymerization reaction to obtain the retarder; wherein the raw material solution comprises styrene sulfonate, an organic phosphorus scale inhibitor, (methyl) acrylic acid hydroxyl ester, an unsaturated dibasic acid, 2-acrylamide-2-methylpropane sulfonic acid and deionized water, and the pH value of the raw material solution is 6-7. The retarder can reduce the viscosity of cement slurry components for well cementing of oil and gas wells, delay the thickening speed of the cement slurry, prolong the pumpable time, and not settle under high temperature conditions, and the well cementing effect is good.

Description

Technical Field

[0001] This invention relates to a cement slurry retarder, its preparation method, and its application, belonging to the field of oilfield chemistry. Background Technology

[0002] Cementing is a crucial operation in the drilling process. During cementing, casing is first run into the well, and then cement slurry is injected into the annular space between the wellbore and the casing. The cement slurry serves two main purposes: firstly, it provides support and protection for the casing; secondly, after hardening in the downhole annulus, it forms an impermeable cement sheath, preventing fluid migration between different formations. Currently, oil and gas exploration and development is gradually shifting towards the exploration of deep and ultra-deep oil and gas resources. Typically, downhole temperature and pressure are positively correlated with well depth; therefore, cementing deep and ultra-deep wells requires a high-temperature resistant cement slurry system.

[0003] In cement slurry systems, retarders play a crucial role. Retarders reduce viscosity, slow down the thickening rate of cement slurry within the annulus, extend pumpable time, and facilitate more uniform distribution of the cement slurry between the wellbore and casing, forming a high-strength, impermeable cement annulus, effectively acting as a sealing layer. Chinese patent document CN115368506A discloses a high-temperature resistant zwitterionic copolymer retarder and its preparation method. The retarder is composed of anionic functional monomers, cationic functional monomers, heat-resistant monomers, and salt-resistant monomers. Experiments have shown that this retarder can reduce cement slurry viscosity and slow down the thickening rate of cement slurry within the annulus below 150℃. However, in special extraction environments, including heavy oil thermal recovery, multiple high-temperature, high-pressure steam injection operations are required at temperatures above 150℃ throughout the extraction lifespan. Current retarders are clearly unsuitable for such harsh high-temperature, high-pressure environments.

[0004] Therefore, it is necessary to conduct further research on cement slurry retarders that can withstand higher temperatures in order to solve the problem of performance degradation of existing retarders under high temperature conditions, and on this basis, to develop cement slurry systems suitable for high-temperature cementing. Summary of the Invention

[0005] This invention provides a method for preparing a cement slurry retarder. The retarder obtained by this method not only helps to improve the high-temperature stability of cement slurry, but also extends the thickening time of cement slurry, thus facilitating the efficient extraction of high-temperature deep and ultra-deep oil and gas.

[0006] The present invention also provides a cement slurry retarder, which is prepared according to the above method. Therefore, its high temperature stability and ultra-long thickening time help to cope with high temperature oil and gas wells with more demanding mining conditions.

[0007] The present invention also provides a cement slurry comprising the above-mentioned retarder, thus having the characteristics of high temperature resistance and long thickening time.

[0008] This invention provides a method for preparing a cement slurry retarder, comprising the following steps:

[0009] After adding an initiator to the raw material liquid, the temperature is raised to 60-70℃ to initiate the polymerization reaction, thereby obtaining the retarder;

[0010] The raw material solution includes styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and deionized water, and the pH value of the raw material solution is 6-7.

[0011] In the preparation method described above, the mass ratio of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid is (6-7):(6-7):(3-5):(1-3):(1-3);

[0012] In the preparation method described above, the total mass of the styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 22%-25% of the total mass of the raw material liquid.

[0013] In the preparation method described above, the organophosphorus scale inhibitor is one or more of allylphosphonic acid, hydroxyethylidene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediaminetetramethylidene phosphonic acid, and their salts.

[0014] In the preparation method described above, the (meth)acrylate hydroxy ester is 2-hydroxyethyl acrylate or (meth)acrylate 2-hydroxyethyl ester; and / or, the unsaturated dicarboxylic acid is one or more of itaconic acid and butenedioic acid;

[0015] In the preparation method described above, the mass of the initiator is 3%-4% of the total mass of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0016] In the preparation method described above, the polymerization reaction takes 4-5 hours;

[0017] The retarder described above is prepared according to any of the preparation methods described above;

[0018] The retarder described above has a particle size of less than 0.3 mm;

[0019] The present invention also provides a cement slurry retarder, prepared according to the method described in any of the preceding claims. The present invention also provides a cement slurry comprising the cement slurry retarder described in any of the preceding claims.

[0020] The method for preparing the cement slurry retarder provided by this invention, by selecting suitable raw materials and carrying out a polymerization reaction under appropriate conditions, can obtain a retarder with good high-temperature stability and a long thickening time. Specifically, it can remain stable without settling at 200°C, and further at 220°C, and can maintain a low viscosity without thickening for at least 240 minutes. Therefore, the retarder prepared by this invention can still achieve high extraction efficiency even in more demanding oil and gas extraction environments, such as deep or ultra-deep well gas production environments or heavy oil extraction environments. Attached Figure Description

[0021] Figure 1 The thickening curve of the cement slurry containing the cement slurry retarder of Example 1 is shown. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The first aspect of this invention provides a method for preparing a cement slurry retarder, comprising the following steps:

[0024] After adding an initiator to the raw material liquid, the temperature is raised to 60-70℃ to initiate the polymerization reaction, thereby obtaining the retarder;

[0025] The raw material solution includes styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and deionized water, and the pH value of the raw material solution is 6-7.

[0026] A feedstock solution needs to be prepared before the polymerization reaction occurs. This invention does not limit the order in which the feedstocks are added. Exemplarily, non-aqueous feedstocks such as styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxyl ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid can be added to deionized water in any order. Alternatively, at least two non-aqueous feedstocks can be mixed and then added to deionized water together with or sequentially with other non-aqueous feedstocks. During the mixing process, it is sufficient to ensure that the non-aqueous feedstocks are uniformly dispersed in the deionized water.

[0027] After mixing the non-aqueous raw materials and deionized water, a suitable pH adjuster can be selected to adjust the pH of the mixture to 6-7 based on the current pH value of the mixture. Specifically, different proportions of the raw materials may result in different pH values ​​in the mixture. Therefore, when the pH of the mixture is acidic, an alkaline pH adjuster can be selected to adjust the pH to 6-7. Alkaline pH adjusters can be, for example, at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, or other alkaline substances. Preferably, a 2-4 mol / L sodium carbonate aqueous solution is used to adjust the pH of the mixture; more preferably, a 3 mol / L sodium carbonate aqueous solution is used. When the pH of the mixture is alkaline, an acidic pH adjuster can be selected to adjust the pH to 6-7. Acidic pH adjusters can be, for example, at least one of dilute sulfuric acid, dilute hydrochloric acid, or other alkaline substances. Preferably, a dilute sulfuric acid solution with a concentration of 2-4 mol / L is used to adjust the pH value of the mixture; more preferably, a dilute sulfuric acid solution with a concentration of 3 mol / L is used to adjust the pH value of the mixture.

[0028] It is understood that post-processing of the reaction system is generally required after the reaction to separate the target product with higher purity. In this invention, post-processing includes purification and drying of the reaction system. For example, the drying temperature is 105℃±2℃, and the time is 24h±1h.

[0029] The retarder prepared according to the above-described technical solution of the present invention exhibits good stability under high-temperature conditions. When added as an additive to cement slurry, the cement slurry not only does not settle at 220°C, but also maintains a low viscosity and does not thicken within 240 minutes. Cement slurry with the above-described retarder can still achieve high efficiency in harsh mining environments. As mentioned above, in the preparation of the retarder, the present invention does not impose excessive limitations on the mass ratio of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxyl ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid in the raw material liquid. In one specific embodiment, when the mass ratio of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid is (6-7):(6-7):(3-5):(1-3):(1-3), preferably, when the mass ratio of the above five compounds is 6.5:6:4:2:2, the high-temperature stability of the retarder and its characteristic of extending the thickening time of cement slurry are more prominent.

[0030] Furthermore, the reaction efficiency of the polymerization reaction can be further improved by controlling the mass ratio of the aforementioned non-aqueous raw materials to deionized water. Specifically, when the total mass of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxyl ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 22%-25% of the total mass of the raw material liquid, it is not only beneficial to control the polymerization rate, but the appropriate reaction system volume also facilitates related post-processing operations.

[0031] This invention does not impose excessive limitations on the various non-aqueous raw materials in the feed liquid. For example, styrene sulfonate is selected from at least one of lithium styrene sulfonate, sodium styrene sulfonate, potassium styrene sulfonate, and ammonium styrene sulfonate; organophosphorus scale inhibitor is selected from at least one of allylphosphonic acid, hydroxyethylidene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediaminetetramethylidenephosphonic acid, and salts formed from the aforementioned four acids; hydroxy(meth)acrylate is selected from at least one of 2-hydroxyethyl acrylate and (meth)acrylate-2-hydroxyethyl ester; and unsaturated dicarboxylic acid is selected from at least one of itaconic acid and butenedioic acid. When the aforementioned five types of compounds are mixtures of multiple specific compounds, this invention does not impose excessive limitations on the proportions between the various specific compounds.

[0032] It is understood that an initiator needs to be added to the above-mentioned feedstock liquid system to initiate the polymerization reaction. This invention does not limit the specific type of initiator; for example, it can be at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0033] When adding an initiator, in order to ensure the efficient progress of the polymerization reaction, and to avoid the effect of excessive initiator addition on the performance of the retarder, the mass of the initiator can be controlled to be 3-4% of the total mass of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid, more preferably 3.5%.

[0034] Furthermore, to ensure the efficient conduction of the polymerization reaction, the reaction can be carried out in an inert atmosphere. The inert gas is selected from at least one of helium, argon, and nitrogen.

[0035] Furthermore, the high-temperature resistance of the retarder and the ability to extend the thickening time of the cement slurry can be further improved by controlling the polymerization reaction time. Generally, controlling the polymerization reaction time to 4-5 hours can basically ensure a suitable degree of polymerization for the retarder, thereby giving it superior performance. In actual preparation, a polymerization inhibitor is usually added to the reaction system to stop the reaction.

[0036] A second aspect of the present invention provides a cement slurry retarder, which is prepared according to the method described in the first aspect above.

[0037] As mentioned earlier, when this retarder is added to the cement slurry, the cement slurry can remain stable at 200°C or even 220°C without settling, and can maintain a low viscosity state without thickening for 240 minutes.

[0038] Furthermore, to facilitate the dispersion of the retarder in the cement paste, it can be ground until it can pass through a sieve with a pore size of 0.3 mm, i.e., the particle size of the retarder particles is controlled to be less than 0.3 mm. This is because only when the dry retarder is pulverized to a particle size of less than 0.3 mm can the retarder be uniformly mixed into the cement paste, which is beneficial to achieving the technical effect of the retarder enhancing the high-temperature stability of the cement paste and extending the thickening time.

[0039] A third aspect of the present invention provides a cement slurry comprising the cement slurry retarder described in the second aspect above.

[0040] This invention does not limit the composition of the cement slurry to other components, which can be common cement slurries in the art. For example, it includes Grade G cement, quartz sand, water loss reducing agent, retarder, and water.

[0041] In practical applications, the retarder content in cement paste is 0.1%-5% by mass. The percentage of retarder added should increase accordingly with increasing temperature.

[0042] Example 1

[0043] The preparation method of the retarder in this embodiment includes the following steps:

[0044] 1) Sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid and deionized water are mixed and stirred evenly. Then the pH of the mixture is adjusted to 6 with 3 mol / L sodium carbonate aqueous solution to obtain the raw material solution.

[0045] The total mass of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 23% of the total mass of the raw material liquid, and the mass ratio of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid is 6.5:6:4:2:2.

[0046] 2) Under a nitrogen atmosphere, potassium persulfate is slowly added to the raw material solution at 60°C to carry out the reaction; wherein, the mass of potassium persulfate is 3.5% of the total mass of sodium styrene sulfonate, 3-dimethylaminoallylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0047] 3) After the reaction proceeded for 5 hours, hydroquinone was added, and the slightly viscous liquid product was cooled to room temperature. The liquid product was purified, dried, and then pulverized to a particle size of less than 0.3 mm to obtain a powdered polymer retarder.

[0048] Example 2

[0049] The preparation method of the retarder in this embodiment includes the following steps:

[0050] 1) Sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid and deionized water are mixed and stirred evenly. Then the pH of the mixture is adjusted to 6 with 2 mol / L sodium carbonate aqueous solution to obtain the raw material solution.

[0051] The total mass of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 23% of the total mass of the raw material liquid, and the mass ratio of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid is 6:6:3:1:1.

[0052] 2) Under a nitrogen atmosphere, potassium persulfate is slowly added to the raw material solution at 55°C to carry out the reaction; wherein the mass of potassium persulfate is 3% of the total mass of sodium styrene sulfonate, 3-dimethylaminoallylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0053] 3) After the reaction proceeded for 4 hours, hydroquinone was added, and the slightly viscous liquid product was cooled to room temperature. The liquid product was purified, dried, and then pulverized to a particle size of less than 0.3 mm to obtain a powdered polymer retarder.

[0054] Example 3

[0055] The preparation method of the retarder in this embodiment includes the following steps:

[0056] 1) Sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid and deionized water are mixed and stirred evenly. Then the pH of the mixture is adjusted to 6 with 4 mol / L sodium carbonate aqueous solution to obtain the raw material solution.

[0057] The total mass of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 23% of the total mass of the raw material liquid, and the mass ratio of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid is 7:7:5:3:3.

[0058] 2) Under a nitrogen atmosphere, potassium persulfate is slowly added to the raw material solution at 65°C to carry out the reaction; wherein, the mass of potassium persulfate is 4% of the total mass of sodium styrene sulfonate, 3-dimethylaminoallylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0059] 3) After the reaction proceeded for 6 hours, hydroquinone was added, and the slightly viscous liquid product was cooled to room temperature. The liquid product was purified, dried, and then pulverized to a particle size of less than 0.3 mm to obtain a powdered polymer retarder.

[0060] Example 4

[0061] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 1) of this embodiment, the mass ratio of sodium styrene sulfonate, allylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid is 3:9:1:5:2.

[0062] Example 5

[0063] The preparation method of the retarder in this embodiment includes the following steps:

[0064] 1) Sodium styrene sulfonate, hydroxyethylidene diphosphonic acid, 2-hydroxyethyl acrylate, itaconic acid, 2-acrylamide-2-methylpropanesulfonic acid and deionized water are mixed and stirred evenly. Then the pH of the mixture is adjusted to 6 with 3 mol / L sodium carbonate aqueous solution to obtain the raw material solution.

[0065] The total mass of sodium styrene sulfonate, hydroxyethylidene diphosphonic acid, 2-hydroxyethyl acrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 23% of the total mass of the raw material liquid, and the mass ratio of sodium styrene sulfonate, hydroxyethylidene diphosphonic acid, 2-hydroxyethyl acrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid is (4:6:1:3:5).

[0066] 2) Under a nitrogen atmosphere, potassium persulfate is slowly added to the raw material solution at 60°C to carry out the reaction; wherein, the mass of potassium persulfate is 3.5% of the total mass of sodium styrene sulfonate, hydroxyethylidene diphosphonic acid, 2-hydroxyethyl acrylate, butenedioic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0067] 3) After the reaction has proceeded for 5 hours, hydroquinone is added, and the slightly viscous liquid product is cooled to room temperature. It is then purified, dried, and pulverized to a particle size of less than 0.3 mm to obtain a powdered polymer retarder.

[0068] Example 6

[0069] The preparation method of the retarder in this embodiment includes the following steps:

[0070] 1) Sodium styrene sulfonate, aminotrimethylphosphonic acid, 2-hydroxyethyl methacrylate, butenedioic acid, 2-acrylamide-2-methylpropanesulfonic acid and deionized water were mixed and stirred evenly. Then the pH of the mixture was adjusted to 6 with 3 mol / L sodium carbonate aqueous solution to obtain the raw material solution.

[0071] The total mass of sodium styrene sulfonate, aminotrimethylphosphonic acid, 2-hydroxyethyl methacrylate, butenedioic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 23% of the total mass of the raw material liquid, and the mass ratio of sodium styrene sulfonate, aminotrimethylphosphonic acid, 2-hydroxyethyl methacrylate, butenedioic acid, and 2-acrylamide-2-methylpropanesulfonic acid is (5:7:2:3:2).

[0072] 2) Under a nitrogen atmosphere, potassium persulfate is slowly added to the raw material solution at 60°C to carry out the reaction; wherein, the mass of potassium persulfate is 3.5% of the total mass of sodium styrene sulfonate, aminotrimethylphosphonic acid, 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0073] 3) After the reaction proceeded for 5 hours, hydroquinone was added, and the slightly viscous liquid product was cooled to room temperature. The liquid product was purified, dried, and then pulverized to a particle size of less than 0.3 mm to obtain a powdered polymer retarder.

[0074] Example 7

[0075] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 1) of this embodiment, the total mass of the five raw materials accounts for 10% of the total mass of the raw material liquid.

[0076] Example 8

[0077] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 1) of this embodiment, the total mass of the five raw materials accounts for 50% of the total mass of the raw material liquid.

[0078] Comparative Example 1

[0079] 1) Weigh 798 parts by weight of deionized water and divide it into 600 parts by weight of deionized water A and 198 parts by weight of deionized water B.

[0080] 2) Weigh out 75.8 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, 55.2 parts by weight of sodium p-styrenesulfonate, 55.2 parts by weight of methylene succinic acid, and 13.8 parts by weight of methacryloyloxyethyltrimethylammonium chloride for later use;

[0081] 3) Stir deionized water A continuously, and add the four functional monomers weighed in step 2 into deionized water A in the order of methylene succinic acid, methacryloyloxyethyltrimethylammonium chloride, sodium p-styrene sulfonate, and 2-acrylamide-2-methylpropanesulfonic acid. After they are completely dissolved, label it as solution A.

[0082] 4) Pour solution A into the reaction vessel, turn on the stirring device at the set speed of 200 rpm, add a certain amount of NaOH to adjust the pH of solution A until it is 6, and after adjustment, set the temperature of the reaction vessel to 60℃.

[0083] 5) Heat to 60℃ and keep the temperature constant. Then, introduce nitrogen into the reactor for 10 minutes. After the nitrogen is introduced, plug the reactor opening with a stopper to isolate it from the air.

[0084] 6) Weigh 2 parts by mass of potassium persulfate and add it to the deionized water B mentioned in step 1. Stir well to form solution B for later use.

[0085] 7) Open the lid of the reaction vessel and add solution B described in step 6 dropwise into solution A in the reaction vessel;

[0086] 8) After solution B is added, stopper the reaction vessel and wait for the solution in the reaction vessel to react for 5 hours before taking it out. The resulting pale yellow viscous solution is the product of this invention.

[0087] Comparative Example 2

[0088] The preparation method of this embodiment is basically the same as that of Example 1, except that in step 1) of this embodiment, the raw materials are 2-hydroxyethyl methacrylate, itaconic acid, and 2-acrylamide-2-methylpropanesulfonic acid, and the mass ratio of the three is 2:1:1.

[0089] Experimental Example 1

[0090] The retarders synthesized in Examples 1-8 and Comparative Examples 1 and 2 were added to the cement paste formula (by weight, 105 parts of G-grade cement, 30 parts of quartz sand, 2 parts of water loss reducer, 1.5 parts of retarder, and 50 parts of water) and tested under thickening conditions of 220°C and 90 MPa. The thickening time is shown in Table 1. Figure 1 The thickening curve of the cement slurry containing the cement slurry retarder of Example 1 is shown.

[0091] Table 1

[0092]

[0093] Conclusion: Based on Figure 1As shown in Table 1, the cement slurry with the retarder prepared according to the method of Example 1 maintained a viscosity below 30 Bc for 264 minutes at 220°C. Comparing this to the thickening time of the cement slurry with the retarder prepared according to Comparative Example 1, it can be seen that the cement slurry with the retarder described in this invention can extend its thickening time at high temperatures. Combined with experimental data from other examples and comparative examples, it can be seen that this invention, by selecting suitable raw materials and carrying out polymerization reactions under appropriate conditions, yields a cement slurry retarder with good high-temperature stability and a long thickening time. The cement slurry with this retarder remains stable and does not settle at 220°C, and can provide a thickening time of at least 240 minutes.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cement slurry retarder, characterized in that, Includes the following steps: After adding an initiator to the raw material liquid, the temperature is raised to 60-70℃ to initiate the polymerization reaction, and the reaction time is 4-5 hours to obtain the retarder; The raw material solution includes styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and deionized water, and the pH value of the raw material solution is 6-7. The mass ratio of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid is 6.5∶6∶4∶2∶2; The total mass of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid accounts for 22%-25% of the total mass of the feed liquid. The organophosphorus scale inhibitor is one or more of allylphosphonic acid, hydroxyethylidene diphosphonic acid, aminotrimethylphosphonic acid, ethylenediaminetetramethylidene phosphonic acid, and their salts. The (meth)acrylate hydroxy ester is 2-hydroxyethyl acrylate or (meth)acrylate-2-hydroxyethyl ester; the unsaturated dicarboxylic acid is one or more of itaconic acid and butenedioic acid; The initiator is 3.5% of the total mass of styrene sulfonate, organophosphorus scale inhibitor, (meth)acrylate hydroxy ester, unsaturated dicarboxylic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

2. A cement slurry retarder, characterized in that, Prepared according to the method of claim 1.

3. The cement slurry retarder according to claim 2, characterized in that, The particle size of the retarder powder is no greater than 0.3 mm.

4. A cement grout, characterized in that, It includes the cement slurry retarder as described in claim 2 or 3.

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