Temperature-resistant and salt-resistant retarder as well as preparation method and application thereof

Abstract

The invention provides a temperature-resistant and salt-resistant retarder and a preparation method and application thereof, the temperature-resistant and salt-resistant retarder is formed by copolymerization of a prepolymer 1 and a prepolymer 2, the prepolymer 1 is obtained by reaction of an acrylamide monomer containing a sulfonic acid group and binary acid with the carbon atom number of 7-9, and the prepolymer 2 is obtained by reaction of an acrylamide monomer containing a sulfonic acid group and binary acid with the carbon atom number of 7-9. The prepolymer 1 is obtained by reacting a sulfonic acid group-containing water-based styrene-acrylic emulsion with a heterocyclic ring-containing styrene-acrylic emulsion, the prepolymer 2 is obtained by reacting a sulfonic acid group-containing water-based styrene-acrylic emulsion with a heterocyclic ring-containing styrene-acrylic emulsion, the mass ratio of the prepolymer 1 to the prepolymer 2 is (0.85-1): (0.98-1.22), and the mass ratio of the sulfonic acid group-containing acrylamide monomer to the binary acid with the carbon atom number of 7-9 is (0.86-1.02): (1.90-2.2). The mass ratio of the sulfonic acid group-containing water-based styrene-acrylic emulsion to the heterocyclic ring-containing styrene-acrylic emulsion is (1.0-1.5): (6.0-7.3), and the temperature-resistant and salt-resistant retarder has excellent high temperature resistance and salt water resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas well cementing, and in particular relates to a temperature-resistant and salt-resistant retarder and a preparation method and application thereof. Background Art

[0002] As oil exploration and development continues to develop towards deep and ultra-deep wells, the complex environment of high temperature and high salt at the bottom of the well has posed severe challenges to the cement slurry system, which is mainly manifested in the following aspects: 1) The cement slurry system has poor coagulation performance under high temperature environment; 2) The cement slurry loses a lot of water in saturated salt water, resulting in increased system density and decreased construction performance. These complex situations have brought new challenges to cementing technology, and also put forward higher performance requirements for cement slurry and its admixtures.

[0003] Retarders are one of the main additives of cement slurry. They can control the thickening time of cement slurry and ensure that the cement slurry is pumpable within the specified time, thereby ensuring the safe progress of cementing construction. Retarders are divided into traditional retarders and polymer retarders. Traditional retarders include lignin sulfonates and their derivatives, organic phosphates, and inorganic salts, which have the problems of poor high-temperature stability and high sensitivity to dosage. Polymer retarders are formed by polymerization of monomers containing multiple functional groups, and have the characteristics of designable structure, so that the retarder has good high-temperature setting properties.

[0004] CN116041601A discloses a polymer cement slurry retarder, the preparation method of which includes adding an initiator to a raw material liquid, heating to 60-70°C to initiate a polymerization reaction to obtain the retarder, the raw material liquid includes styrene sulfonate, organic phosphorus scale inhibitor, (methyl) acrylic acid hydroxy ester, unsaturated dibasic acid, 2-acrylamide-2-methylpropane sulfonic acid and water, and the cement slurry added with the retarder maintains a low viscosity state without thickening within 240 minutes at 220°C. CN117659311A discloses a cement slurry retarder, the preparation method of which includes using 2-acrylamide-2-methylpropane sulfonic acid, acrylic acid and diallyldimethylammonium chloride as monomers, using diallyldimethylammonium chloride modified montmorillonite as an active filler, and synthesizing by solution polymerization in-situ intercalation method, the cement slurry added with the retarder can reach a thickening time of 322-547 minutes at 240°C. The above patent application has achieved certain results in high temperature resistant retarders. However, there are few reports on cement slurry retarders that are both resistant to high temperature and resistant to salt water.

[0005] Therefore, how to develop a temperature-resistant and salt-resistant retarder is a technical problem to be solved urgently in this field. Summary of the invention

[0006] The invention provides a heat-resistant and salt-resistant retarder, which has excellent high temperature resistance and salt water resistance capabilities.

[0007] The present invention also provides a method for preparing the above-mentioned heat-resistant and salt-resistant retarder. The preparation method has simple process, simple and convenient operation and is convenient for industrial production.

[0008] The present invention also provides a cement slurry, wherein the cement slurry comprises the above-mentioned temperature-resistant and salt-resistant retarder, and the cement slurry has excellent high-temperature stability and salt water resistance.

[0009] In a first aspect, the present invention provides a heat-resistant and salt-resistant retarder, wherein the heat-resistant and salt-resistant retarder is copolymerized by prepolymer 1 and prepolymer 2;

[0010] The prepolymer 1 is obtained by reacting acrylamide monomer containing a sulfonic acid group and a dibasic acid having 7 to 9 carbon atoms;

[0011] The prepolymer 2 is obtained by reacting an aqueous styrene-acrylic emulsion containing a sulfonic acid group and a styrene-acrylic emulsion containing a heterocycle;

[0012] The mass ratio of the prepolymer 1 to the prepolymer 2 is (0.85-1): (0.98-1.22);

[0013] The mass ratio of the acrylamide monomer containing sulfonic acid group to the dibasic acid having 7 to 9 carbon atoms is (0.86-1.02): (1.9-2.2);

[0014] The mass ratio of the aqueous styrene-acrylic emulsion containing sulfonic acid groups to the styrene-acrylic emulsion containing heterocycles is (1-1.5):(6-7.3).

[0015] The heat-resistant and salt-resistant retarder as described above, wherein the weight average molecular weight of the heat-resistant and salt-resistant retarder is 450,000-500,000.

[0016] The heat-resistant and salt-resistant retarder as described above, wherein the sulfonic acid group-containing acrylamide monomer comprises at least one of 2-acrylamide-2-phenylethanesulfonic acid, 2-acrylamide dodecylsulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid; and / or,

[0017] The dibasic acid having 7 to 9 carbon atoms includes at least one of 1,7-pimelic acid, suberic acid, and azelaic acid; and / or,

[0018] The aqueous styrene acrylic emulsion containing sulfonic acid groups includes at least one of silicone styrene acrylic emulsion and elastic styrene acrylic emulsion; and / or,

[0019] The heterocyclic-containing styrene-acrylic emulsion includes at least one of a condensed-ring styrene-acrylic emulsion and a cross-linked modified styrene-acrylic emulsion.

[0020] In a second aspect, the present invention provides a method for preparing the above-mentioned heat-resistant and salt-resistant retarder, comprising the following steps:

[0021] (1) mixing an aqueous solution of acrylamide monomer containing a sulfonic acid group and an aqueous solution of a dibasic acid having 7 to 9 carbon atoms, adding alkali to adjust the pH value to 6.5 to 7.5, raising the temperature to 60 to 80° C., and reacting to obtain a prepolymer 1;

[0022] (2) mixing an aqueous styrene-acrylic emulsion containing a sulfonic acid group and a styrene-acrylic emulsion containing a heterocyclic ring, heating the mixture to 60-80° C., and reacting the mixture to obtain a prepolymer 2;

[0023] (3) Prepolymer 1, prepolymer 2 and an initiator are mixed, the temperature is raised to 60-70° C., a polymerization reaction is carried out, an inhibitor is added, and the temperature is cooled to 15-30° C. to obtain the heat-resistant and salt-resistant retarder.

[0024] In the preparation method as described above, the mass percentage concentrations of the aqueous solution of acrylamide monomer containing sulfonic acid groups, the aqueous solution of dibasic acid having 7-9 carbon atoms, the aqueous styrene-acrylic emulsion containing sulfonic acid groups and the styrene-acrylic emulsion containing heterocycles in step (1) and step (2) are all 25%-30%.

[0025] The preparation method as described above, wherein the base in step (1) comprises at least one of sodium hydroxide, potassium hydroxide and sodium carbonate; and / or,

[0026] The reaction time in step (1) is 30-40 min; and / or,

[0027] The reaction time in step (2) is 60-80 min; and / or,

[0028] The polymerization reaction time in step (3) is 0.5-1.5h.

[0029] In the preparation method as described above, the initiator comprises ammonium persulfate, and the inhibitor comprises at least one of resorcinol, p-benzoquinone, methylhydroquinone, and copper sulfate.

[0030] In the preparation method as described above, the mass of the initiator is 1%-2.5% of the total mass of prepolymer 1 and prepolymer 2, and the mass of the inhibitor is 0.9%-1.3% of the total mass of prepolymer 1 and prepolymer 2.

[0031] The preparation method as described above, wherein the polymerization reaction in step (3) is carried out under an inert gas; and / or,

[0032] The inert gas in step (3) includes at least one of helium, argon and nitrogen; and / or,

[0033] The cooling in step (3) further includes purification and drying.

[0034] In a third aspect, the present invention provides a cement slurry comprising the above-mentioned temperature-resistant and salt-resistant retarder.

[0035] The implementation of the present invention has at least the following beneficial effects:

[0036] The present invention adopts raw materials of specific types and contents to prepare a heat-resistant and salt-resistant retarder with a weight-average molecular weight of 450,000-500,000. The heat-resistant and salt-resistant retarder has good high temperature resistance and salt water resistance. The cement slurry added with the heat-resistant and salt-resistant retarder has excellent high temperature stability and salt water resistance, and will not increase water loss in a salt water environment. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The first aspect of the present invention provides a heat-resistant and salt-resistant retarder, which is copolymerized by prepolymer 1 and prepolymer 2;

[0039] Prepolymer 1 is obtained by reacting acrylamide monomer containing sulfonic acid group and dibasic acid having 7-9 carbon atoms;

[0040] Prepolymer 2 is obtained by reacting a sulfonic acid group-containing aqueous styrene-acrylic emulsion with a heterocyclic styrene-acrylic emulsion;

[0041] The mass ratio of prepolymer 1 to prepolymer 2 is (0.85-1):(0.98-1.22);

[0042] The mass ratio of the acrylamide monomer containing a sulfonic acid group to the dibasic acid having 7 to 9 carbon atoms is (0.86-1.02):(1.9-2.2);

[0043] The mass ratio of the aqueous styrene acrylic emulsion containing sulfonic acid groups to the styrene acrylic emulsion containing heterocyclic rings is (1-1.5):(6-7.3).

[0044] The present invention uses the above-mentioned specific type and proportion of polymer monomers to prepare a heat-resistant and salt-resistant retarder with excellent high temperature resistance and salt water resistance.

[0045] In the present invention, the weight average molecular weight of the heat-resistant and salt-resistant retarder is 450,000-500,000, which can enable the heat-resistant and salt-resistant retarder to form a spatial network structure at high temperature.

[0046] In some embodiments, the sulfonic acid group-containing acrylamide monomer includes at least one of 2-acrylamido-2-phenylethanesulfonic acid, 2-acrylamidododecylsulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid; and / or,

[0047] The dibasic acid having 7 to 9 carbon atoms includes at least one of 1,7-pimelic acid, suberic acid, and azelaic acid.

[0048] The invention introduces sulfonic acid group, amide group and carboxyl group with strong adsorption capacity into the heat-resistant and salt-resistant retarder through acrylamide containing sulfonic acid group and dibasic acid with 7-9 carbon atoms, which is helpful to adsorb cement particles and reduce the hydration rate of cement.

[0049] Further, the aqueous styrene-acrylic emulsion containing sulfonic acid groups includes at least one of silicone styrene-acrylic emulsion and elastic styrene-acrylic emulsion; and / or,

[0050] The heterocyclic-containing styrene-acrylic emulsion includes at least one of a condensed-ring styrene-acrylic emulsion and a cross-linked modified styrene-acrylic emulsion.

[0051] The invention introduces high temperature resistant benzene ring and heterocycle into the heat and salt resistant retarder by using aqueous styrene acrylic emulsion containing sulfonic acid group and styrene acrylic emulsion containing heterocycle, so that the retarder is not easy to agglomerate at high temperature, which is beneficial to improve the high temperature resistance and salt water resistance of the retarder.

[0052] In a second aspect, the present invention provides a method for preparing the above-mentioned heat-resistant and salt-resistant retarder, the preparation method comprising the following steps:

[0053] (1) mixing an aqueous solution of acrylamide monomer containing a sulfonic acid group and an aqueous solution of a dibasic acid having 7 to 9 carbon atoms, adding alkali to adjust the pH value to 6.5 to 7.5, raising the temperature to 60 to 80° C., and reacting to obtain a prepolymer 1;

[0054] (2) mixing an aqueous styrene-acrylic emulsion containing a sulfonic acid group and a styrene-acrylic emulsion containing a heterocyclic ring, heating the mixture to 60-80° C., and reacting the mixture to obtain a prepolymer 2;

[0055] (3) Prepolymer 1, prepolymer 2 and an initiator are mixed, the temperature is raised to 60-70° C., a polymerization reaction is carried out, an inhibitor is added, and the temperature is cooled to 15-30° C. to obtain the heat-resistant and salt-resistant retarder.

[0056] In step 1) of the present invention, a base is added to adjust the pH value of the mixed system to 6.5-7.5 to avoid incomplete polymerization of the polymerization monomers under acidic conditions.

[0057] In some embodiments, the mass percentage concentrations of the aqueous solution of acrylamide monomer containing sulfonic acid groups, the aqueous solution of dibasic acid having 7-9 carbon atoms, the aqueous styrene-acrylic emulsion containing sulfonic acid groups, and the heterocyclic styrene-acrylic emulsion in step (1) and step (2) are all 25%-30%.

[0058] Preparing a polymerization monomer solution with a specific mass percentage concentration before the polymerization reaction can further control the reaction efficiency of the polymerization reaction and make the polymerization reaction proceed smoothly. Specifically, the acrylamide monomer containing sulfonic acid groups can be added to water to prepare an aqueous solution of acrylamide monomer containing sulfonic acid groups with a mass percentage concentration of 25%-30%; dibasic acids with carbon atoms of 7-9 are added to water respectively to prepare an aqueous solution of dibasic acids with carbon atoms of 7-9 with a mass percentage concentration of 25%-30%; an aqueous styrene-acrylic emulsion containing sulfonic acid groups is added to water to prepare an aqueous styrene-acrylic emulsion containing sulfonic acid groups with a mass percentage concentration of 25%-30%; and a styrene-acrylic emulsion containing heterocyclic rings is added to water to prepare a styrene-acrylic emulsion containing heterocyclic rings with a mass percentage concentration of 25%-30%.

[0059] In some embodiments, the base includes at least one of sodium hydroxide, potassium hydroxide, and sodium carbonate, so that the polymerization monomers can undergo polymerization reaction more fully.

[0060] Furthermore, the reaction time in step (1) is 30-40 min; and / or, the reaction time in step (2) is 60-80 min; and / or, the polymerization reaction time in step (3) is 0.5-1.5 h, so as to ensure that the polymerization monomers fully undergo polymerization reaction while saving energy.

[0061] In the present invention, the initiator ammonium persulfate is added to the polymerization monomer. Ammonium persulfate has the advantages of fast initiation speed, fast dissolution, fast dispersion and low price, so that the polymerization monomer can efficiently undergo polymerization reaction.

[0062] Furthermore, the polymerization inhibitor includes at least one of resorcinol, p-benzoquinone, methylhydroquinone and copper sulfate, which terminates the polymerization reaction.

[0063] In some embodiments, the mass of the initiator is 1%-2.5% of the total mass of the prepolymer 1 and the prepolymer 2, which can improve the efficiency of the polymerization reaction while saving the initiator.

[0064] Furthermore, the mass of the polymerization inhibitor is 0.9%-1.3% of the total mass of the prepolymer 1 and the prepolymer 2, and the polymerization reaction is terminated in time while saving the polymerization inhibitor.

[0065] In the present invention, the polymerization reaction in step (3) is carried out under an inert gas, and the inert gas includes at least one of helium, argon and nitrogen, which can further improve the polymerization reaction efficiency.

[0066] Furthermore, after cooling in step (3), the reaction system is purified and dried in sequence to separate and obtain a heat-resistant and salt-resistant retarder with higher purity.

[0067] In a third aspect, the present invention provides a cement slurry comprising the temperature-resistant and salt-resistant retarder of the first aspect.

[0068] The present invention does not limit other components and contents of the cement slurry, and may be cement slurry commonly used in the art, for example, including cement, quartz sand, a fluid loss reducer, a defoamer, a retarder and water.

[0069] The cement slurry has excellent high temperature stability and salt water resistance and will not increase water loss in a salt water environment.

[0070] The present invention is described in detail below by specific embodiments:

[0071] Example 1

[0072] The preparation method of the heat-resistant and salt-resistant retarder provided in this embodiment comprises the following steps:

[0073] (1) mixing an aqueous solution of 2-acrylamido-2-phenylethanesulfonic acid and an aqueous solution of azelaic acid, adding sodium hydroxide to adjust the pH value to 7, raising the temperature to 70° C., and reacting for 30 minutes to obtain a prepolymer 1;

[0074] (2) mixing a silicone styrene acrylic emulsion (model 707, Henan Tianchou Chemical Products Co., Ltd.) and a polycyclic styrene acrylic emulsion (model BJ806, Beijing Jiahui Tongda Chemical Products Co., Ltd.), heating to 65° C., and reacting for 60 min to obtain prepolymer 2;

[0075] (3) Under nitrogen protection, prepolymer 1, prepolymer 2 and ammonium persulfate are mixed, the temperature is raised to 70° C., the polymerization reaction is carried out for 1 hour, resorcinol is added, the mixture is cooled to 15° C., and the heat-resistant and salt-resistant retarder is obtained after purification and drying.

[0076] Among them, the mass ratio of prepolymer 1 to prepolymer 2 is 1:1.22, the mass ratio of 2-acrylamido-2-phenylethanesulfonic acid to azelaic acid is 1:2.2, and the mass ratio of silicone styrene acrylic emulsion to condensed ring styrene acrylic emulsion is 1:7.3;

[0077] The mass percentage concentration of 2-acrylamido-2-phenylethanesulfonic acid aqueous solution, azelaic acid aqueous solution, silicone styrene acrylic emulsion and condensed ring styrene acrylic emulsion is 25%;

[0078] The mass of ammonium persulfate is 1% of the total mass of prepolymer 1 and prepolymer 2, and the mass of resorcinol is 0.9% of the total mass of prepolymer 1 and prepolymer 2.

[0079] Example 2

[0080] The preparation method of the heat-resistant and salt-resistant retarder provided in this embodiment comprises the following steps:

[0081] (1) Mixing an aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid and an aqueous solution of suberic acid, adding potassium hydroxide to adjust the pH value to 6.5, raising the temperature to 75° C., and reacting for 40 minutes to obtain a prepolymer 1;

[0082] (2) mixing elastic styrene-acrylic emulsion (model 707H, Henan Tianchou Chemical Products Co., Ltd.) and cross-linked modified styrene-acrylic emulsion (BJ-806H, Beijing Jiahui Tongda Chemical Products Co., Ltd.), heating to 65° C., and reacting for 80 min to obtain prepolymer 2;

[0083] (3) Under nitrogen protection, prepolymer 1, prepolymer 2 and ammonium persulfate were mixed, the temperature was raised to 65° C., the polymerization reaction was carried out for 1.5 hours, p-benzoquinone was added, the mixture was cooled to 15° C., and the heat-resistant and salt-resistant retarder was obtained after purification and drying.

[0084] The mass ratio of prepolymer 1 to prepolymer 2 is 1:1, the mass ratio of 2-acrylamido-2-methylpropanesulfonic acid to suberic acid is 1:2, and the mass ratio of elastic styrene acrylic emulsion to cross-linked modified styrene acrylic emulsion is 1:6;

[0085] The mass percentage concentration of 2-acrylamido-2-methylpropanesulfonic acid aqueous solution, suberic acid aqueous solution, elastic styrene acrylic emulsion and cross-linked modified styrene acrylic emulsion is 26%;

[0086] The mass of ammonium persulfate is 1.5% of the total mass of prepolymer 1 and prepolymer 2, and the mass of p-benzoquinone is 1.1% of the total mass of prepolymer 1 and prepolymer 2.

[0087] Example 3

[0088] The preparation method of the heat-resistant and salt-resistant retarder provided in this embodiment comprises the following steps:

[0089] (1) Mixing an aqueous solution of 2-acrylamidododecylsulfonic acid and an aqueous solution of azelaic acid, adding sodium carbonate to adjust the pH value to 7.5, heating to 80° C., and reacting for 35 minutes to obtain a prepolymer 1;

[0090] (2) mixing the elastic styrene acrylic emulsion and the condensed ring styrene acrylic emulsion, heating to 65° C., and reacting for 75 min to obtain prepolymer 2;

[0091] (3) Under nitrogen protection, prepolymer 1, prepolymer 2 and ammonium persulfate are mixed, the temperature is raised to 70° C., the polymerization reaction is carried out for 1 hour, resorcinol is added, the mixture is cooled to 15° C., and the heat-resistant and salt-resistant retarder is obtained after purification and drying.

[0092] Among them, the mass ratio of prepolymer 1 to prepolymer 2 is 0.9:1.22, the mass ratio of 2-acrylamide-2-phenylethanesulfonic acid to azelaic acid is 1:1.9, and the mass ratio of elastic styrene acrylic emulsion to condensed ring styrene acrylic emulsion is 1:6;

[0093] The mass percentage concentration of 2-acrylamidododecylsulfonic acid aqueous solution, azelaic acid aqueous solution, elastic styrene acrylic emulsion and condensed ring styrene acrylic emulsion is 27%;

[0094] The mass of ammonium persulfate is 2% of the total mass of prepolymer 1 and prepolymer 2, and the mass of resorcinol is 1.3% of the total mass of prepolymer 1 and prepolymer 2.

[0095] Application Examples 1-3

[0096] The heat-resistant and salt-resistant retarders prepared in Examples 1-3 were respectively added to the cement slurry formula, which included the following components in parts by weight: 100 parts of cement (Dalian Cement), 40 parts of quartz sand (Chaoyang Minghua), 8 parts of fluid loss additive (DS-1, Liaoning Hengao), 0.5 parts of defoaming agent (Panjin Hongbo), 5 parts of heat-resistant and salt-resistant retarder, and 46 parts of water.

[0097] Application Example 4

[0098] This application example provides a cement slurry, which reduces the content of the heat-resistant and salt-resistant retarder to 4 parts compared with application example 1, while other conditions remain unchanged.

[0099] Application Example 5

[0100] This application example provides a cement slurry. Compared with application example 4, the fluid loss reducer DS-1 is replaced by DRG (Panjin Hongbo Petroleum Technology Service Co., Ltd.) in equal amount, and other conditions remain unchanged.

[0101] Application Example 6

[0102] This application example provides a cement slurry. Compared with application example 4, the fluid loss reducer DS-1 is replaced by D181 (Schlumberger) in equal amounts, and other conditions remain unchanged.

[0103] Application Example 7

[0104] This application example provides a cement slurry. Compared with application example 4, the fluid loss reducer DS-1 is replaced by GWF-200L (Great Wall Drilling and Cementing Company) in equal amount, and other conditions remain unchanged.

[0105] Application Example 8

[0106] This application example provides a cement slurry. Compared with application example 4, the content of the heat-resistant and salt-resistant retarder is increased to 6 parts, while other conditions remain unchanged.

[0107] Performance Testing

[0108] (1) Thickening time test: The cement slurries prepared in Application Examples 1-3 of the same mass were weighed and subjected to thickening tests at 220° C. according to the requirements of GB / T10238. The results are shown in Table 1.

[0109] (2) Retarder dosage sensitivity test: The thickening time of the cement slurries of Examples 4-8 was tested. The results are shown in Table 2.

[0110] (3) Salt water resistance test: Weigh the same mass of cement slurry prepared in Application Examples 1-3, replace the water in the cement slurry with 18 wt % sodium salt water, and perform a thickening time test at 220° C. in accordance with the requirements of GB / T10238. The results are shown in Table 3.

[0111] Table 1

[0112]

[0113] From the analysis of Table 1, it can be seen that the cement slurries prepared by using Examples 1-3 have a longer thickening time.

[0114] Table 2

[0115]

[0116] As can be seen from Table 2, the cement slurry prepared by using the fluid loss reducer GWF-200L in Example 7 and the heat-resistant and salt-resistant retarder in Example 1 has a longer thickening time, a right-angle thickening trend, and an ideal sensitivity reaction.

[0117] Table 3

[0118]

[0119] From the analysis of Table 3, it can be seen that when the NaCl content in the slurry prepared in Examples 1-3 is 18 wt%, the cement slurry still has a relatively long thickening time, indicating that the cement slurry has a strong ability to resist salt water.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 heat-resistant and salt-resistant retarder, characterized in that: The heat-resistant and salt-resistant retarder is copolymerized by prepolymer 1 and prepolymer 2; The prepolymer 1 is obtained by reacting acrylamide monomer containing a sulfonic acid group and a dibasic acid having 7 to 9 carbon atoms; The prepolymer 2 is obtained by reacting an aqueous styrene-acrylic emulsion containing a sulfonic acid group and a styrene-acrylic emulsion containing a heterocycle; The mass ratio of the prepolymer 1 to the prepolymer 2 is (0.85-1): (0.98-1.22); The mass ratio of the acrylamide monomer containing sulfonic acid group to the dibasic acid having 7 to 9 carbon atoms is (0.86-1.02): (1.90-2.2); The mass ratio of the aqueous styrene-acrylic emulsion containing sulfonic acid groups to the styrene-acrylic emulsion containing heterocycles is (1.0-1.5):(6.0-7.3).

2. The heat-resistant and salt-resistant retarder according to claim 1, characterized in that: The weight average molecular weight of the heat-resistant and salt-resistant retarder is 450,000-500,000.

3. The heat-resistant and salt-resistant retarder according to claim 1 or 2, characterized in that: The sulfonic acid group-containing acrylamide monomer includes at least one of 2-acrylamide-2-phenylethanesulfonic acid, 2-acrylamide dodecylsulfonic acid, and 2-acrylamide-2-methylpropanesulfonic acid; and / or, The dibasic acid having 7 to 9 carbon atoms includes at least one of 1,7-pimelic acid, suberic acid, and azelaic acid; and / or, The aqueous styrene acrylic emulsion containing sulfonic acid groups includes at least one of silicone styrene acrylic emulsion and elastic styrene acrylic emulsion; and / or, The heterocyclic-containing styrene-acrylic emulsion includes at least one of a condensed-ring styrene-acrylic emulsion and a cross-linked modified styrene-acrylic emulsion.

4. A method for preparing the heat-resistant and salt-resistant retarder according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) mixing an aqueous solution of acrylamide monomer containing a sulfonic acid group and an aqueous solution of a dibasic acid having 7 to 9 carbon atoms, adding alkali to adjust the pH value to 6.5 to 7.5, raising the temperature to 60 to 80° C., and reacting to obtain a prepolymer 1; (2) mixing an aqueous styrene-acrylic emulsion containing a sulfonic acid group and a styrene-acrylic emulsion containing a heterocyclic ring, heating the mixture to 60-80° C., and reacting the mixture to obtain a prepolymer 2; (3) Prepolymer 1, prepolymer 2 and an initiator are mixed, the temperature is raised to 60-70° C., a polymerization reaction is carried out, an inhibitor is added, and the temperature is cooled to 15-30° C. to obtain the heat-resistant and salt-resistant retarder.

5. The preparation method according to claim 4, characterized in that: The mass percentage concentrations of the sulfonic acid group-containing acrylamide monomer aqueous solution, the carbon atom number 7-9 dibasic acid aqueous solution, the sulfonic acid group-containing aqueous styrene-acrylic emulsion and the heterocyclic styrene-acrylic emulsion in step (1) and step (2) are all 25%-30%.

6. The preparation method according to claim 4 or 5, characterized in that: The base in step (1) comprises at least one of sodium hydroxide, potassium hydroxide and sodium carbonate; and / or, The reaction time in step (1) is 30-40 min; and / or, The reaction time in step (2) is 60-80 min; and / or, The polymerization reaction time in step (3) is 0.5-1.5h.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The initiator comprises ammonium persulfate; and / or, The polymerization inhibitor includes at least one of resorcinol, p-benzoquinone, methylhydroquinone and copper sulfate.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The mass of the initiator is 1%-2.5% of the total mass of prepolymer 1 and prepolymer 2; and / or, The mass of the polymerization inhibitor is 0.9%-1.3% of the total mass of the prepolymer 1 and the prepolymer 2.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The polymerization reaction in step (3) is carried out under an inert gas; and / or, The inert gas in step (3) includes at least one of helium, argon and nitrogen; and / or, The cooling in step (3) further includes purification and drying.

10. A cement slurry, characterized in that: The cement slurry comprises the temperature-resistant and salt-resistant retarder according to any one of claims 1 to 3.

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