CN115975133A - Suspension stabilizer for high-temperature high-density well cementing cement slurry, preparation method and application - Google Patents
Suspension stabilizer for high-temperature high-density well cementing cement slurry, preparation method and application Download PDFInfo
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Abstract
The invention belongs to the technical field of oil-gas well development, and discloses a suspension stabilizer suitable for high-temperature high-density cement slurry, and a preparation method and application thereof. The high-temperature suspension stabilizer comprises a structural unit A shown in a formula (I), a structural unit B shown in a formula (II), a structural unit C shown in a formula (III) and a result unit D shown in a formula (IV); wherein, the structural percentage of the structural units A, B, C and D is x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z and q is 1; n is 17, 19 or 21. The high-temperature high-density cement paste is stable in suspensionThe fixing agent ensures that higher viscosity is maintained under high temperature condition without increasing normal temperature viscosity by adjusting high temperature rheological property, and the temperature resistance reaches 210 ℃, thereby solving the difficult problem of high density cement paste sedimentation instability well cementation under high temperature condition.
Description
Technical Field
The invention relates to the technical field of oil and gas well development, in particular to a suspension stabilizer for high-temperature high-density cement slurry suitable for oil and gas well cementation, and a preparation method of the suspension stabilizer for the high-temperature high-density cement slurry suitable for oil and gas well cementation.
Background
Deep oil and gas resources in China have great potential, wherein 39% of residual oil resources and 57% of residual natural gas resources are distributed in deep strata on land, and the deep oil and gas resources become the main fields of exploration and development. However, due to the deep burial depth of deep oil and gas resources and the high temperature and pressure of the stratum, well cementation will face the outstanding problem of sedimentation instability of high-temperature and high-density cement slurry. The high temperature and high pressure are specially used in petroleum engineering under the conditions that the bottom temperature exceeds 150 deg.c and the pressure is greater than 69 MPa. Under the high-temperature environment, the weighting agent in the high-density cement slurry is easy to settle and destabilize due to high density and large addition amount, solid-phase particles of the weighting agent are settled and aggregated and even agglomerated to cause bridge plugging, a large amount of free liquid is separated out or an oil-gas-water channeling channel is formed, so that the well cementation construction risk is large, the well cementation quality qualification rate is low, and the production and safety of a high-temperature and high-pressure oil-gas well are even endangered. Therefore, the method is very important for ensuring good sedimentation stability of the high-temperature high-density cement paste.
Petroleum and natural gas are used as strategic resources, and have important influence on economic safety and stable development. The demand of petroleum and natural gas in China continuously increases, the contradiction between supply and demand of oil and gas resources is prominent, and the external dependence of crude oil and petroleum in 2019 is 70% higher than the internationally recognized 50% safety warning line. In the severe energy situation, new oil and gas resources are urgently needed. The potential of deep oil and gas resources in China is huge, and the evaluation result of the oil and gas resources in China in 2015 shows that the amount of petroleum geological resources in China is 1257 billion tons, the amount of natural gas geological resources is 90.3 trillion cubic meters, wherein 39% of residual petroleum resources and 57% of residual natural gas resources are distributed in deep strata on land. In recent years, a batch of ultra-deep pre-exploration wells, evaluation wells and the like are deployed in Xinjiang Tarim, sichuan basins and the like in China, the deepest record of Asia land drilling is created frequently, and the oil and gas important discoveries of Tarim depth, northward and the like are obtained first. The deep oil gas resource becomes the main field of exploration and development, the deep oil gas resource development is accelerated, and the method has great significance for improving the energy guarantee level of China, relieving the external dependence pressure of the energy of China and guaranteeing the national energy safety.
Ultra-deep well drilling often faces both high temperature and high pressure problems. The formation pressure is high, and the density of cement slurry required by well cementation is higher to ensure a stable stratum. However, conventional cement slurries have densities in the range of 1.78-1.97g/cm, subject to the optimum water usage of the cement 3 In order to increase the density of the cement paste, a large amount of weighting agent materials (barite powder, iron ore powder, ilmenite powder, reduced iron powder, manganese oxide powder and the like with the density of 4.5-7.0 g/cm and the like) are required to be added 3 ) (ii) a Meanwhile, in order to prevent the strength of the cement stone from declining at high temperature (the temperature is more than or equal to 110 ℃), more than or equal to 35 percent of silica powder needs to be added into the cement, the higher the temperature is, the larger the adding amount of the quartz sand is, and the density of the silica powder (2.6 g/cm) 3 ) Specific cement (about 3.15 g/cm) 3 ) And small, high-temperature silicon powder addition is not beneficial to increasing the density of cement paste. Where necessary, the relative amount of weighting material added to obtain a high density cement slurry at high temperatures must be higher, e.g., a high density cement slurry (2.45 g/cm) at a site 3 ) The basic solid composition is as follows: g-grade oil well cement, 35% of silicon powder, 110% of weighting agent and 10% of micro manganese, wherein the mass of the silicon powder and the admixture of the weighting agent is up to 155% of that of the cement. In a word, the high-temperature high-density cement slurry is a mixed system consisting of various solid and multi-density particles, and has the characteristics of large particle density difference and high solid content.
The viscous force of the cement slurry under high temperature is seriously weakened, the Brownian motion of particles is accelerated, the suspension capability of the cement slurry to solid-phase particles is poor, the slurry stability is poor, a large amount of solid-phase particles are gathered and settled, and the high-density cement slurry is easy to have serious high-temperature settlement instability and even serious layering. The settlement instability of high-density cement slurry is considered to cause settlement delamination of weighting agent particles, rheological change of the cement slurry and the like, so that the well cementation displacement efficiency is low, the cement slurry is bridged and blocked, and accidents such as pump holding, stratum pressure leakage and the like are easily induced. With the acceleration of deep oil and gas resource development in China, the effect and significance of stably controlling sedimentation of high-temperature and high-density cement slurry gradually exceed the cognitive category of traditional well cementation. In the deep drilling of China, when a plurality of pressure system stratums are encountered, stratum fracture pressure and pore pressure safety pressure windows are narrow, the requirements on density control and performance uniformity of entering cement slurry are high, sedimentation instability can cause the density difference of the upper section and the lower section of the slurry to be large, and the density of the slurry at the upper section is seriously deviated from the initial design requirement, so that the long-section low-density cement slurry formed by sedimentation at the upper part is difficult to stabilize a local high-pressure zone, and well cementation channeling is easily caused; secondly, deep oil and gas reservoirs in China are mainly fracture-cavity type high-pressure and ultrahigh-pressure gas reservoirs, the cement slurry entering a well is required to have better anti-channeling and anti-leakage performance, the contents of solid phase components and additives of the upper segment and the lower segment of the slurry are subjected to drastic changes due to sedimentation instability, the components and the performance of the slurry cannot be kept uniform, the control filtration, leakage prevention, gas channeling prevention performance, cement stone strength and other performances of the cement slurry in different intervals deviate from the design requirements, and the ultra-deep well cementing cannot be met, so that the cementing quality is poor.
The traditional polymer has obvious inherent defects of high-temperature viscosity reduction, and the instability out-of-control problem of high-temperature high-density cement paste cannot be solved, so that the ultra-deep well cementing risk is high, the cementing quality is poor, and even the high-temperature high-pressure oil and gas production and safety of the ultra-deep well are endangered.
Chinese patent document CN103694975A discloses a cement paste stabilizer, which comprises Wen Lunjiao, mineral oil, organic soil and a rheological regulator, wherein the content of Wen Lunjiao is 10-60 parts by weight, the content of organic soil is 1-0 part by weight, and the content of the rheological regulator is 2-12 parts by weight, relative to 100 parts by weight of the mineral oil; the rheology modifier comprises a nonionic surfactant with a hydrophilic-lipophilic balance value of less than 4 and a nonionic surfactant with a hydrophilic-lipophilic balance value of more than 14. The cement slurry stabilizer can effectively improve the sedimentation stability of slurry at the temperature of below 100 ℃, but can still not solve the sedimentation instability problem of high-temperature well cementation cement slurry at the high temperature of 200 ℃.
CN104263333A discloses a high-density cement slurry stabilizer, which consists of 20-30% of non-metal oxide, 65-75% of metal oxide and 3-5% of asphalt micro powder. The high-temperature stability of the high-density cement paste is improved mainly by a particle grading mode, but the suspending agent is inorganic particles, so that the problems of slurry thinning, poor stability and the like caused by the aggravation of self thermal motion of cement and aggravating materials in the high-density cement paste and the high-temperature thinning of polymer additives cannot be solved.
Published patent CN109485788A provides an oil well cement sedimentation stabilizer prepared from acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and a rigid hydrophobic monomer by free radical polymerization. The oil well cement sedimentation stabilizer improves the sedimentation stability of cement paste by utilizing the thermal tackifying effect of the oil well cement sedimentation stabilizer. However, the viscosity of the sedimentation stabilizer rapidly decreases after 155 ℃.
Published patent CN109321219A provides an oil well cement sedimentation stabilizer and a preparation method thereof, wherein the oil well cement sedimentation stabilizer is prepared from acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, N-dimethylacrylamide and a rigid hydrophobic monomer through free radical polymerization. The oil well cement sedimentation stabilizer actively adapts to downhole temperature change and the application environment of well cementation cement slurry by introducing rigid hydrophobic monomers into the conventional copolymer, thereby effectively preventing solid-phase substances and free liquid generated by the dilution of the well cementation cement slurry under the high temperature condition and improving the sedimentation stability of the well cementation cement slurry. However, the sedimentation stabilizer shows a large decrease in viscosity after 180 ℃.
Therefore, aiming at the problem of instability and incontrollability of deep ultra-deep well high-density cement slurry, the development of a new high-temperature stable material and the formation of a new slurry stability and rheological property regulation and control method are very urgent and important.
Disclosure of Invention
The invention aims to solve the problem of sedimentation instability of high-temperature and high-density cement slurry for well cementation of an oil and gas well, and provides a temperature response type high-temperature and high-density cement slurry suspension stabilizer suitable for well cementation of the oil and gas well, wherein the suspension stabilizer can adjust rheological property of the cement slurry within the range of normal temperature to 210 ℃, so that the sedimentation instability problem of the high-temperature and high-density well cementation cement slurry is effectively solved, the safety of well cementation construction is guaranteed, and the integral well cementation quality is improved.
In order to achieve the above object, a first aspect of the present invention provides a temperature-responsive high-temperature high-density cement slurry suspension stabilizer, wherein the suspension stabilizer for temperature-responsive high-temperature high-density cement slurry comprises a structural unit a represented by formula (I), a structural unit B represented by formula (II), a structural unit C represented by formula (III), and a resulting unit D represented by formula (iv);
wherein the structural percentages of structural unit a, structural unit B, and structural unit C are x, y, and z, and x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z, and q is 1;
wherein R is 1 、R 2 、R 3 、R 4 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl;
wherein n is 17, 19 or 21;
the invention provides a preparation method of the suspension stabilizer for the temperature response type high-temperature high-density cement slurry, which comprises the following steps of mixing a monomer A, a monomer B, a monomer C, a monomer D and deionized water in the presence of an initiator, and carrying out copolymerization reaction;
wherein the monomer A has a structure shown in a formula (V), the monomer B has a structure shown in a formula (VI), the monomer C has a structure shown in a formula (VII), and the monomer D has a structure shown in a formula (VIII);
wherein R is 5 、R 6 、R 7 And R 8 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl;
wherein n is 17, 19 or 21;
wherein, the monomers A, B, C and D are used in such amounts that the structural percentages of the structural unit A, the structural unit B, the structural unit C and the structural unit D contained in the suspension stabilizer for warm high-density cement slurry are x, y, z and q, x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z and q is 1.
Through the technical scheme, the invention introduces long-chain hydrophobic groups and modified nano SiO into the conventional high-temperature resistant polymer 2 The monomer enhances the thermal association effect, improves the temperature resistance, and solves the key technology that the cement slurry suspension stabilizer has poor temperature resistance under the conditions of high temperature and high density. The suspension stabilizer for the high-temperature high-density cement slurry has good thermal stability within the range of normal temperature to 210 ℃, can adjust the rheological property of the cement slurry, and effectively improves the sedimentation stability of the high-temperature high-density cement slurry at high temperature.
The invention also aims to provide a preparation method and application of the high-temperature high-density cement slurry suspension stabilizer for well cementation, wherein the method is reliable in principle and simple to operate. After the high-temperature high-density cement slurry suspension stabilizer prepared by the method is added into cement slurry, the sedimentation stability of the high-temperature high-density cement slurry can be effectively improved, the sedimentation instability problem of high-temperature high-density well cementation cement slurry is solved, the safety of well cementation construction is guaranteed, and the overall well cementation quality is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a rheological profile of a suspension stabilizer prepared in example 1 of the present invention at 25-90 deg.C;
FIG. 2 is a graph comparing the rheology curves of the suspension stabilizer prepared in example 1 of the present invention and those of comparative examples 1-3 at 25-90 deg.C;
FIG. 3 is a thermogravimetric plot of the suspension stabilizer prepared in example 1 of the present invention;
FIG. 4 is a high temperature rheology profile at 25-200 deg.C for the suspension stabilizer prepared in example 1 of the present invention.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In order to achieve the above object, a first aspect of the present invention provides a suspension stabilizer for temperature-responsive high-temperature and high-density cement slurry, wherein the suspension stabilizer for temperature-responsive high-temperature and high-density cement slurry comprises a structural unit a represented by formula (I), a structural unit B represented by formula (II), a structural unit C represented by formula (III), and a resulting unit D represented by formula (iv);
wherein the structural percentages of structural unit a, structural unit B and structural unit C are x, y and z, and x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31% and the sum of x, y, z and q is 1;
wherein n is 17, 19 or 21.
The method of claim 1, wherein the monomers A, B, C and D are used in a weight ratio of (34.55-86.27): (36.00-66.00): (16.67-33.33): 1;
according to the invention, preferably R 1 、R 2 、R 3 、R 4 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl; further, in the present invention, R 1 、R 2 、R 3 、R 4 When the structural unit is H, the structural unit A is a 2-acrylamido-2-methylpropanesulfonic acid group, the structural unit B is an N, N-dimethylacrylamide group, the structural unit C is a long-chain hydrophobic group, and the structural unit D is a silane coupling agent modified nano SiO 2 A group.
According to the invention, the weight average molecular weight of the suspension stabilizer for the high-temperature high-density cement slurry is 800-1400 ten thousand. In the invention, the high-temperature high-density cement slurry suspension stabilizer is limited to have the components and the weight average molecular weight of the components, so that the solid particle sedimentation caused by viscosity reduction and rheological property deterioration of the high-density cement slurry under a high-temperature condition can be effectively prevented, and the sedimentation stability of the high-temperature high-density cement slurry is effectively improved.
The invention provides a preparation method of a high-temperature high-density cement slurry suspension stabilizer, which is characterized by comprising the following steps of mixing a monomer A, a monomer B, a monomer C, a monomer D and deionized water in the presence of an initiator, and carrying out copolymerization reaction;
wherein the monomer A has a structure shown in a formula (V), the monomer B has a structure shown in a formula (VI), the monomer C has a structure shown in a formula (VII), and the monomer D has a structure shown in a formula (VIII);
wherein R is 5 、R 6 、R 7 And R 8 The same or different is H, methyl, ethyl, n-propyl, isopropyl or butyl;
wherein n is 17, 19 or 21;
wherein the monomers A, B, C and D are used in such amounts that the structural percentages of the structural units A, B, C and D in the suspension stabilizer for warm high-density cement slurry are x, y, z and q, x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z and q is 1.
The method of claim 1, wherein the monomers A, B, C and D are used in a weight ratio of (34.55-86.27): (36.00-66.00): (16.67-33.33): 1;
preferably, the total amount of the monomer A, the monomer B, the monomer C and the monomer D is 35 to 40 weight percent of the amount of the deionized water;
preferably, the pH of the mixed solution of the monomer A, the monomer B, the monomer C, the monomer D and the deionized water is 7-10.
Preferably, R 5 、R 6 、R 7 And R 8 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl; in the present invention, R represents 5 、R 6 、R 7 And R 8 When the structural unit is H, the structural unit A is 2-acrylamido-2-methylpropanesulfonic acid, the structural unit B is N, N-dimethylacrylamide, the structural unit C is a long-chain hydrophobic monomer, and the structural unit D is silane coupling agent modified nano SiO 2 A monomer.
According to the invention, 2-acrylamido-2-methylpropanesulfonic Acid (AMPS) is used as one of the reaction monomers, and has the advantages that the intramolecular steric hindrance of the 2-acrylamido-2-methylpropanesulfonic acid makes the thermal stability of the 2-acrylamido-2-methylpropanesulfonic acid good, the 2-acrylamido-2-methylpropanesulfonic acid is not easy to hydrolyze, and the molecule contains a sulfonate group (-SO) 3 -) to make it insensitive to external acid, alkali and salt ion interference, thereby further improving the temperature resistance and salt tolerance of the cement slurry suspension stabilizer and making it better applied to high temperature well cementation. In the present invention, 2-acrylamideThe 2-methyl propane sulfonic Acid (AMPS) is commercially available, for example, from the Guangdong Weng Jiang Chemicals, inc. in analytical purity.
According to the invention, N, N-Dimethylacrylamide (DMAA) is taken as one of the reaction monomers, which has the advantages of further improving the temperature resistance and salt resistance of the molecule and improving the water loss reduction performance. In the present invention, N-dimethylacrylamide is commercially available, for example, from Shandong Fengyuan chemical Co., ltd.
According to the invention, the long-chain hydrophobic monomer can be synthesized by itself through experimental means.
In the invention, a long-chain hydrophobic monomer is developed by increasing the length of an alkyl chain in the monomer, and the long-chain hydrophobic monomer is a rigid hydrophobic long-chain alkyl monomer and can endow the synthesized polymer with the characteristic of temperature response, so that the rigid hydrophobic long-chain alkyl quaternary ammonium salt-containing monomer is synthesized by using chloropropene and N, N-dimethyl long-chain alkyl tertiary amine (the number of long-chain alkyl is an even number of 16-20) as the long-chain hydrophobic monomer, and the specific synthesis method comprises the following steps:
(1) Adding fatty alcohol and a proper amount of catalyst into a reaction kettle, heating the reaction kettle, introducing monomethylamine into the reaction kettle for 75-85min at the temperature of 140 ℃ under the flow of 35-50 kg/h, and finally keeping the reaction temperature of the reaction kettle at 200-240 ℃ for 6-9h to synthesize N, N-dimethyl long-chain alkyl tertiary amine (the number of long-chain alkyl is an even number of 12-20);
(2) Quaternization of the tertiary amine is effected by reacting a quaternizing agent (C) 3 H 5 Cl) is introduced into a reaction vessel containing tertiary amine and a little alkali solution (Na) 2 CO 3 ) Alcohol solvent (isopropanol) in a closed container at 75-90 deg.c and 3.0X 9.8X 10 4 Pa to 3.5X 9.8X 10 4 Synthesized under the condition of Pa.
The reaction formula is as follows:
wherein, the hydrophobicity of the rigid hydrophobic monomer will be enhanced with the increase of the length of the long-chain alkyl chain (N value is increased), and the long-chain hydrophobic monomer is prepared by N, N-dimethyl long-chain alkyl tertiary amine with N being 16, 18 or 20.
In the present invention, chloropropene and N, N-dimethyl long-chain alkyl tertiary amine are both commercially available, for example, chloropropene is commercially available from Jinan Arsenegand chemical Co., ltd., chemically pure; n, N-dimethyl long-chain alkyl tertiary amines are available from Shanghai Aladdin Biotechnology Ltd, chemically pure. In the present invention, preferably, the chloropropene used is industrially pure and is subjected to a purification treatment by distillation before use.
According to the invention, the hydrophobic monomer is dissolved in deionized water in advance at a mass concentration of 10-30%.
Preferably, the hydrophobic monomer is a pale yellow wax with a density of 0.62-0.8g/cm 3 The mass content of the effective components is more than or equal to 70 percent.
According to the invention, the modified SiO 2 The monomer is self-modified by experimental means, and the invention utilizes silane coupling agent vinyl triethoxysilane to modify nano SiO 2 Grafting modification is carried out, namely, the grafting modification is carried out to improve the nano SiO 2 The second is to introduce unsaturated carbon-carbon double bonds which can participate in polymerization reaction on the surface of the modified nanoparticles, and the specific crosslinking method comprises the following steps:
(1) Mixing ethanol and nano SiO 2 The particles, distilled water and ammonia water are added into a round bottom flask in sequence, and nanometer SiO is added 2 The weight of the particles is 0.5-5 wt% of the total weight of the dispersion system, and ultrasonic dispersion is carried out for 30-60min to ensure that the nano SiO is 2 Uniformly dispersing the particles;
(2) Slowly dripping a proper amount of vinyl triethoxysilane into the round-bottom flask, controlling the temperature at 20-45 ℃ and reacting for 8-24h;
(3) After the reaction is completed, washing with absolute ethyl alcohol for 3-5 times, carrying out high-speed centrifugal separation, drying at constant temperature of 40-80 ℃ for 24-48h, crushing and grinding to obtain the vinyltriethoxysilane modified nano SiO 2 A monomer.
According to the invention, the modified SiO 2 GranulesNot only can improve the high-temperature resistance of the polymer, but also has abundant hydroxyl on the surface and is easy to form a hydrogen chain in the solution;
according to the present invention, preferably, the total amount of the monomer a, the monomer B, the monomer C and the monomer D is 30 to 40 wt% of the amount of the deionized water;
preferably, the pH of the mixed solution of the monomer A, the monomer B, the monomer C, the monomer D and the deionized water is 7-10. In the invention, the pH value of the reaction solution can be adjusted by using an alkali solution, wherein the alkali solution is a sodium hydroxide solution or a potassium hydroxide solution, and the mass concentration of the alkali solution is 10-30%.
According to the invention, the initiator adopts a redox initiation system, wherein the oxidant is at least one of persulfate, ammonium persulfate and potassium persulfate, the reducer is at least one of sodium bisulfite, ammonium hydroxide and triethylamine, and the molar ratio of the oxidant to the reducer is (2-4): (1-2), preferably 1: (0.3-1).
According to the invention, the initiator is used in an amount of 0.1 to 1% by weight based on the total amount of monomers A, B, C and D. In the present invention, the rate of addition of the initiator should be sufficiently slow to avoid a situation where the reactive monomers implode during the polymerization reaction.
According to the invention, a monomer A, a monomer B, a monomer C and a monomer D are all dissolved in deionized water, mixed liquor is formed after uniform stirring, the pH value is adjusted, then the mixed liquor with the adjusted pH value can be placed in a reaction device, wherein the reaction device comprises main components such as a ground three-neck flask with the capacity of 500mL, a precise reinforcement electric stirrer, a constant-pressure dropping funnel and the like, and the three-neck flask is sealed through a latex tube; discharging oxygen in the three-neck flask, placing the three-neck flask in a water bath tank at 40-70 ℃, preferably 40 ℃, stirring by using a precise power-increasing electric stirrer at the rotating speed of 100-400r/min, and when the temperature of the reaction solution rises to 40-70 ℃, preferably 40 ℃, dropwise adding the initiator to 2-acrylamide-2-methylpropanesulfonic acid, N-dimethylacrylamide, long-chain hydrophobic monomer and silane coupling agent modified nano SiO at the dropwise adding rate of 5-15mL/min 2 After mixing of monomers and said deionized waterAnd (3) in the mixed solution, stopping stirring when the viscosity of the reaction system is increased to be difficult to stir after 20min, standing for reacting for 6-10h, preferably 8h to obtain a light yellow low-elasticity gel polymer, and purifying and drying to obtain the high-temperature high-density cement slurry suspension stabilizer.
Wherein, the oxygen in the reaction vessel can be removed by filling nitrogen into the reaction vessel.
According to the invention, the method also comprises the step of purifying and drying the reaction product after the copolymerization reaction, wherein the absolute ethyl alcohol is adopted for purification for 2-3 times.
The drying may be performed by drying in a constant temperature drying oven, and the drying time is not particularly limited as long as it is performed, and may be, for example, 18 to 24 hours, and preferably 24 hours.
In the present invention, the formulation of the well cementation cement slurry is not specifically limited, and may be selected conventionally by those skilled in the art, for example, the mass parts of the components of the used well cementation cement slurry system are specifically as follows: weifang G-level cement, 38 percent of silica fume, 168 percent of ilmenite, 3 percent of high-temperature fluid loss additive, 0.15 to 1 percent of high-temperature high-density cement slurry suspension stabilizer, 1.5 percent of drag reducer, 0.25 percent of defoaming agent, 2.0 percent of high-temperature retarder and 68 percent of water, wherein the density of the cement slurry is 2.60G/cm 3 。
Through the technical scheme, the invention has the advantages that:
(1) A free radical aqueous solution polymerization mode is adopted, and a redox system is used as an initiator, so that the high-temperature high-density cement slurry suspension stabilizer with certain response capability along with temperature change is prepared. The used materials have wide and easily obtained sources, low cost, low requirements on preparation conditions, simple preparation method, high success rate of polymer synthesis and high conversion rate, and are very suitable for large-scale production and application.
(2) Introducing functional group monomer with special configuration and difficult degradation, such as sulfonic acid group and modified nano SiO 2 The temperature resistance of the obtained polymer is obviously improved, and the high temperature stability of the suspension stabilizer for high-temperature high-density cement slurry can be effectively improved.
(3) A quaternary ammonium salt monomer containing long carbon chain alkyl hydrophobic groups is used for modifying the suspension stabilizer of high-temperature high-density cement slurry, long hydrophobic group side chains are introduced on hydrophilic long chains, and the tackifying capability of the suspension stabilizer at high and low temperatures is adjusted by regulating the morphological distribution and adsorption state of the suspension stabilizer of the high-temperature high-density cement slurry in the cement slurry under the conditions of high and low temperatures. At a lower temperature, the long hydrophobic groups are easy to associate with each other, and the free energy of the system is reduced, so that the long carbon chain alkyl side chain groups shrink and curl due to the hydrophobic effect, are intertwined and agglomerated, the viscosity of a polymer solution is not greatly improved, as the temperature rises, the association structure formed by intertwining the long carbon chain alkyl side chains is gradually opened, the molecular chains of the polymer gradually extend in the water solution to form a more compact space network structure, and thus the viscosity of the high-temperature and high-density cement slurry is obviously improved, the normal pumping of the cement slurry at the low temperature is not influenced, and the sedimentation stability of the high-density cement slurry at the high temperature is ensured.
(4) The suspension stabilizer for the high-temperature high-density cement slurry has good operability, can be directly used in a dry mixing mode with cement, can also be directly used in a wet mixing mode by being added into water, and has good compatibility with other additives and strong adaptability.
The present invention will be described in detail below by way of examples.
Experimental methods used in the examples: a cement paste system prepared according to the oil well cement test method of the standard GB/T19139-2003, and refers to standard SY/T6544-2003 'oil well cement paste performance requirement', SY/T6466-2000 'oil well cement stone high temperature resistance performance evaluation method', SY/T5504.1-2013 'evaluation method of oil well cement admixture' test cement paste system and external performance.
The "parts" described in the examples and test examples are "parts by mass".
The starting materials used in the examples are all conventional commercial products.
The cement paste formula used in the test experiment of the embodiment is as follows: weifang G-level cement, 38 percent of silica fume, 168 percent of ilmenite, 3 percent of high-temperature fluid loss additive, 0.1 to 1 percent of suspension stabilizer for high-temperature high-density cement slurry, 1.5 percent of drag reducer, 0.25 percent of defoaming agent and 2.0 percent of high-temperature retarderThe agent is added with 68 percent of water, and the density of cement paste is 2.60g/cm 3 。
Example 1
This example illustrates the high temperature, high density cement slurry suspension stabilizer prepared by the method of the present invention.
The preparation steps are as follows:
(1) Respectively weighing 51.75 parts of 2-acrylamide-2-methylpropanesulfonic acid (monomer A), 39.6 parts of N, N-dimethylacrylamide (monomer B), 10 parts of long-side-chain hydrophobic monomer (monomer C) and 0.6 part of modified nano SiO 2 Dissolving a monomer (monomer D) by using deionized water, wherein the total mass concentration of the monomer in the solution is 37.63 percent, and adjusting the pH value to 8 by using a sodium hydroxide solution with the concentration of 5 mol/L;
wherein the long side chain hydrophobic monomer has a structure represented by formula (VII), and R 6 Is H, n is 17;
(2) The temperature of the water bath box is adjusted to 40 ℃, and the reaction device is installed. 2-acrylamide-2-methylpropanesulfonic acid, N-dimethylacrylamide, long side chain hydrophobic monomer and modified nano SiO 2 The mixed solution of the monomers is transferred into a three-neck flask, stirred by a magnetic stirrer, the rotating speed is kept at 300r/min, and nitrogen is introduced into the container to remove oxygen. Respectively weighing 2.5 parts of ammonium persulfate and 2 parts of sodium bisulfite to prepare a solution, wherein the mass concentration of an initiator in the solution is 1.8 percent, adding the initiator into a three-neck flask by using a constant-pressure dropping funnel when the temperature is raised to 40 ℃, and the adding amount of the initiator is 0.2 percent of the total mass of monomers;
(3) After the dropwise addition, maintaining the rotation speed unchanged, reacting for 8 hours at a set temperature, cooling the faint yellow low-elasticity gel to room temperature, and purifying for 3 times by using absolute ethyl alcohol to obtain the high-temperature high-density cement slurry suspension stabilizer marked as S1.
Wherein, the high-temperature high-density cement slurry suspension stabilizer S1 has the structure that:
[CM 1 HCH 2 ] x -[C 5 H 9 NO] y -[CH 2 CM 2 HCl - ] z -[C 2 H 4 Si 2 O 3 ] q (ii) a Wherein M is 1 is-CONHC (CH) 3 ) 2 CH 2 SO 3 H，M 2 Is- [ NCH 2 (CH 3 ) 2 (CH 2 ) n CH 3 ] + ；
Wherein x =50.76%, y =44.29%, z =3.95%, q =1.00% and
the weight average molecular weight of the suspension stabilizer S1 of the high-temperature high-density cement slurry is 1200 ten thousand.
Example 2
This example illustrates the high temperature, high density cement slurry suspension stabilizer prepared by the method of the present invention.
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: respectively weighing 25.88 parts of 2-acrylamide-2-methylpropanesulfonic acid (monomer A), 19.8 parts of N, N dimethylacrylamide (monomer B), 10 parts of long side chain hydrophobic monomer (monomer C) and 0.3 part of modified nano SiO 2 The monomer (monomer D) is dissolved by deionized water, the total mass concentration of the monomer in the solution is 31.11 percent, and the pH value is adjusted to 8 by sodium hydroxide solution with the concentration of 5 mol/L;
the suspension stabilizer of the high-temperature high-density cement paste prepared as a result is marked as S2.
The high-temperature high-density cement slurry suspension stabilizer S2 comprises the following structures:
[CM 1 HCH 2 ] x -[C 5 H 9 NO] y -[CH 2 CM 2 HCl - ] z -[C 2 H 4 Si 2 O 3 ] q (ii) a Wherein M is 1 is-CONHC (CH) 3 ) 2 CH 2 SO 3 H，M 2 Is- [ NCH 2 (CH 3 ) 2 (CH 2 ) n CH 3 ] + ；
Wherein x =36.04%, y =57.65%, z =5.60%, q =0.71%, and
the weight average molecular weight of the high-temperature high-density cement slurry suspension stabilizer S2 is 1080 ten thousand.
Example 3
This example illustrates the high temperature, high density cement slurry suspension stabilizer prepared by the method of the present invention.
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: respectively weighing 20.73 parts of 2-acrylamide-2-methylpropanesulfonic acid (monomer A), 24.78 parts of N, N-dimethylacrylamide (monomer B), 10 parts of long side chain hydrophobic monomer (monomer C) and 0.6 part of modified nano SiO according to weight ratio 2 Dissolving a monomer (monomer D) by using deionized water, wherein the total mass concentration of the monomer in the solution is 34.42 percent, and adjusting the pH value to 8 by using a sodium hydroxide solution with the concentration of 5 mol/L;
the suspension stabilizer of the high-temperature high-density cement paste prepared as a result is marked as S3.
The high-temperature high-density cement slurry suspension stabilizer S3 comprises the following structures:
[CM 1 HCH 2 ] x -[C 5 H 9 NO] y -[CH 2 CM 2 HCl - ] z -[C 2 H 4 Si 2 O 3 ] q (ii) a Wherein M is 1 is-CONHC (CH) 3 ) 2 CH 2 SO 3 H，M 2 Is- [ NCH 2 (CH 3 ) 2 (CH 2 ) n CH 3 ] + ；
Wherein x =26.72%, y =66.78%, z =5.18%, q =1.31% and
the weight average molecular weight of the suspension stabilizer S3 of the high-temperature high-density cement slurry is 820 ten thousand.
Example 4
This example illustrates the high temperature, high density cement slurry suspension stabilizer prepared by the method of the present invention.
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: the long side chain hydrophobic monomer has a structure represented by formula (VII), and R 7 Is H, n is 19;
and the high-temperature high-density cement slurry suspension stabilizer prepared by the result is marked as S4.
The high-temperature high-density cement slurry suspension stabilizer S4 comprises the following structures:
[CM 1 HCH 2 ] x -[C 5 H 9 NO] y -[CH 2 CM 2 HCl - ] z -[C 2 H 4 Si 2 O 3 ] q (ii) a Wherein M is 1 is-CONHC (CH) 3 ) 2 CH 2 SO 3 H，M 2 Is- [ NCH 2 (CH 3 ) 2 (CH 2 ) n CH 3 ] + ；
Wherein x =50.87%, y =44.38%, z =3.75%, q =1.00% and
the weight average molecular weight of the suspension stabilizer S4 of the high-temperature high-density cement slurry is 1348 ten thousand.
Example 5
This example is presented to illustrate a high temperature, high density cement slurry suspension stabilizer prepared using the method of the present invention.
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: the long side chain hydrophobic monomer has a structure represented by formula (VII), and R 7 Is H, n is 21;
and the high-temperature high-density cement slurry suspension stabilizer prepared by the result is marked as S5.
The high-temperature high-density cement slurry suspension stabilizer S5 comprises the following structures:
[CM 1 HCH 2 ] x -[C 5 H 9 NO] y -[CH 2 CM 2 HCl - ] z -[C 2 H 4 Si 2 O 3 ] q (ii) a Wherein M is 1 is-CONHC (CH) 3 ) 2 CH 2 SO 3 H，M 2 Is- [ NCH 2 (CH 3 ) 2 (CH 2 ) n CH 3 ] + ；
Wherein x =50.96%, y =44.47%, z =3.57%, q =1.00% and
the weight average molecular weight of the suspension stabilizer S5 of the high-temperature high-density cement slurry is 1354 ten thousand.
Comparative example 1
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: xanthan gum is used as a suspension stabilizer. The resulting oil well cement suspension stabilizer, designated DS1, was prepared.
Comparative example 2
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: hydroxyethyl cellulose is used as a suspension stabilizer. The resulting oil well cement suspension stabilizer, designated DS2, was prepared.
Comparative example 3
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: hydroxypropyl guar gum was used as a suspension stabilizer. The resulting oil well cement suspension stabilizer, designated DS3, was prepared.
Comparative example 4
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: 2-acrylamide-2-methylpropanesulfonic acid, N-dimethylacrylamide, long side chain hydrophobic monomer and modified nano SiO 2 The amount of the monomer used was such that the weight average molecular weight of the oil well cement suspension stabilizer prepared was 157 ten thousand.
Comparative example 5
A high temperature, high density cement slurry suspension stabilizer was prepared in the same manner as in example 1, except that: 2-acrylamide-2-methylpropanesulfonic acid, N-dimethylacrylamide, long side chain hydrophobic monomer and modified nano SiO 2 The monomer is used in such an amount that the weight average molecular weight of the prepared oil well cement suspension stabilizer is 283 ten thousand.
Test example 1
Suspension stabilizer solutions of the high-temperature high-density cement slurry described in example 1 were prepared at different concentrations (0.15 wt%, 0.3 wt% and 0.45 wt%), and the apparent viscosity and shear rate were measured at 170.3s -1 The temperature control mode is water bath temperature control, and the temperature rise is controlledThe results are shown in FIG. 1 at 5 ℃.
As can be seen from FIG. 1, the emulsion polymerization high-temperature stabilizer solution for high-temperature well cementation with the concentration of 0.15-0.45 wt% in example 1 has very small viscosity reduction in the temperature range of normal temperature-90 ℃, and has higher viscosity and rheology regulation capability. The experimental example only tests that the temperature is 90 ℃, and the rheological control capability of the emulsion polymerization high-temperature stabilizer for high-temperature well cementation is more than 90 ℃ from the trend of the change curve of the apparent viscosity of the emulsion polymerization high-temperature stabilizer for high-temperature well cementation with the concentration of 0.15-0.3% by weight along with the temperature.
Test example 2
The high-temperature high-density cement slurry suspension stabilizer of the embodiment 1 with the mass fraction of 0-0.6% is respectively added into a high-temperature high-density well cementation cement slurry system, and the used high-temperature fluid loss additive and high-temperature retarder are both provided by Zhongpetrochemical Shengli well cementation companies. According to the standard GB/T19139-2003 'oil well cement test method', and the performance of the cement paste system is tested by referring to the standard SY/T6544-2003 'oil well cement paste performance requirement', SY/T6466-2000 'oil well cement stone high temperature resistance performance evaluation method', and testing the initial consistency, thickening time, API water loss, free liquid amount, compressive strength and the difference between the upper density and the lower density of the cement paste, wherein the curing temperature is 210 ℃, and the curing time is 24 hours. The evaluation method of the density difference between the upper part and the lower part of the cement paste comprises the following steps: stirring high-temperature high-density cement slurry in a densifier at 210 ℃ for 20min, curing at 90 ℃ for 2.5h, testing the upper and lower densities to calculate the density difference, and when the upper and lower density difference is less than or equal to 0.03g/cm 3 When the amount is larger, the sedimentation stability is good. The results are shown in tables 1-2 for the effect of the addition of the suspension stabilizer to the cement slurry at high temperature and high density.
TABLE 1 influence of high-temp. high-density cement slurry suspension stabilizer dosage on cement slurry flow property
TABLE 2 influence of high-temp. high-density cement slurry suspension stabilizer dosage on cement slurry properties
According to the experimental results in the tables 1-2, the influence of the oil well cement suspension stabilizer on the initial consistency and thickening time of high-temperature well-cementing cement slurry is small, normal operation of well-cementing operation can be ensured, and meanwhile, the API water loss and free liquid volume of the high-temperature high-density well-cementing cement slurry are obviously reduced, which indicates that the high-temperature high-density cement slurry suspension stabilizer has certain water loss reduction capability. In addition, when the addition of the high-temperature high-density cement slurry suspension stabilizer is 0.30-0.60%, the compression strength of the set cement is improved, the difference of the upper and lower densities of the cement slurry is reduced, and the comprehensive performance of the cement slurry is improved.
Test example 3
A suspension stabilizer solution of example 1, a xanthan gum solution of comparative example 1, a hydroxyethylcellulose solution of comparative example 2 and a hydroxypropyl guar solution of comparative example 3 were prepared in respective mass fractions of 0.45% by weight, 0.45% by weight and the apparent viscosity and shear rate of 170.3s were measured in respective mass fractions of hydroxypropyl guar solution of comparative example 3 -1 The temperature control mode is water bath temperature control, the temperature rise is controlled to be 5 ℃, and the result is shown in figure 2.
As can be seen from FIG. 2, the emulsion polymerization high-temperature stabilizer solution for high-temperature well cementation has better rheology regulation capability, and the viscosity reduction rate is obviously lower than that of other three common tackifiers at the temperature of 20-90 ℃; hydroxyethyl cellulose solution, xanthan gum solution and hydroxypropyl guar gum solution exhibit high viscosity at normal temperature, but their viscosity decreases rapidly with increasing temperature. In conclusion, the hydroxyethyl cellulose, the xanthan gum and the hydroxypropyl guar gum can effectively improve the apparent viscosity of a liquid phase under the normal temperature condition, the viscosity is rapidly reduced under the high temperature condition, and the rheological property of the well cementation liquid cannot be effectively adjusted.
Test example 4
The oil well cement suspension stabilizer described in example 1 was pulverized and the change curve of mass loss was measured by using a thermogravimetric analyzer TG209F3 (German Steady instruments manufacturing Co., ltd.), and the result is shown in FIG. 3.
As can be seen from fig. 3, the thermogravimetric curve of the suspension stabilizer for high-temperature high-density cement slurry can be divided into 4 stages: the first stage is 25 ℃ to 292 ℃, the thermogravimetric curve changes in the first stage are very stable and slow, and the weight loss of the polymer is about 7.5 wt%, which is mainly caused by the weight loss of moisture due to evaporation by heating; the second stage is 292 ℃ to 318 ℃, the weight of the polymer is obviously reduced in the stage, and the weight loss is about 27.6 percent, which is mainly caused by that oxygen-containing groups such as amide, sulfonic acid and the like contained in the oil well cement suspension stabilizer begin to be thermally decomposed, so that the more obvious weight loss is caused; the third stage is 318 ℃ to 401 ℃, the weight loss in the stage is further increased, the loss is about 30.97 weight percent, and the main chain of the oil well cement suspension stabilizer begins to be broken, and the polymer molecules begin to be thoroughly decomposed; the fourth stage is above 401 ℃, and the weight of the oil well cement suspension stabilizer powder tends to be smooth, which indicates that the oil well cement suspension stabilizer powder is completely decomposed. Therefore, the oil well cement suspension stabilizer synthesized by the invention has excellent thermal stability, and can ensure the integrity of a molecular structure below 292 ℃.
Test example 5
The high-temperature high-density well cementation cement slurry is prepared according to a formula, and the used high-temperature fluid loss agent and high-temperature retarder are provided by China petrochemical Shengli well cementation companies. The initial consistencies and thickening times of cement slurries added with different additives at different curing temperatures are measured by respectively adding 0.45 mass percent of the high-temperature high-density cement slurry suspension stabilizer of example 1, 0.45 mass percent of xanthan gum of comparative example 1, 0.45 mass percent of hydroxyethyl cellulose of comparative example 2 and 0.45 mass percent of hydroxypropyl guar gum of comparative example 3 into a high-temperature well cementation cement slurry system. The results of the experiment are shown in table 3 below.
TABLE 3 initial consistency and thickening time at different curing temperatures for cement slurries with different additives
According to the experimental results in table 3, the suspension stabilizer for high-temperature high-density cement slurry of the invention does not improve the initial consistency of the cement slurry at normal temperature, but can play a role in thickening at high temperature, so that the initial consistency of the cement slurry is kept in a reasonable range; the hydroxyethyl cellulose, the xanthan gum and the hydroxypropyl guar gum can obviously improve the initial consistency of the cement paste at normal temperature, are not beneficial to pumping the cement paste, cannot effectively thicken at high temperature and are difficult to play a role in stabilizing the cement paste. In addition, the high-temperature high-density cement slurry suspension stabilizer and the hydroxyethyl cellulose can not change the thickening time of the cement slurry at different temperatures, and the xanthan gum and the hydroxypropyl guar gum can obviously prolong the thickening time of the cement slurry and influence the normal hydration reaction of the cement. Therefore, the suspension stabilizer for the high-temperature high-density cement slurry can realize the aims of no thickening at low temperature and high-temperature thickening, and effectively improve the sedimentation stability of the well cementation cement slurry.
Test example 6
0.45 percent of the suspension stabilizer of the high-temperature high-density cement slurry in the example 1 is prepared, and the rheological property under the high-temperature and high-pressure conditions is tested, and the shear rate is 430s -1 The experimental results are shown in fig. 4 below.
According to the experimental results of fig. 4, it can be known that the suspension stabilizer solution of the high-temperature high-density cement slurry of example 1 with the concentration of 0.45% has stable performance in the range from normal temperature to 210 ℃, and the rheological property of the solution can be improved to a certain extent.
Test example 7
0.45 percent of high-temperature high-density cement slurry suspension stabilizer of example 1, 0.45 percent of xanthan gum of comparative example 1, 0.45 percent of hydroxyethyl cellulose of comparative example 2 and 0.45 percent of hydroxypropyl guar gum of comparative example 3 are respectively added into a high-temperature well cementation cement slurry system, after the cement slurry is cured for 5 days at different temperatures, the compressive strength and the upper and lower density difference of the set cement are tested, and the experimental results are shown in the following table 4.
TABLE 4 influence of different additives on the compression strength and the difference in the upper and lower density of set cement
From the experimental results of table 4, it is understood that the compressive strength of the cement raw slurry gradually decreases and the difference in the upper and lower densities of the set cement increases as the curing temperature increases. The high-temperature high-density cement slurry suspension stabilizer and the hydroxyethyl cellulose can slightly improve the compressive strength of the set cement, and the xanthan gum and the hydroxypropyl guar gum can obviously reduce the compressive strength of the set cement. In addition, the suspension stabilizer for high-temperature high-density cement slurry can obviously reduce the upper and lower density difference of the cement stone under different high-temperature curing environments, and the hydroxyethyl cellulose, the xanthan gum and the hydroxypropyl guar gum can reduce the density difference of the cement stone at normal temperature to a certain extent, but the effect is obviously poorer than that of the suspension stabilizer for high-temperature high-density cement slurry.
In conclusion, from the using effect, the suspension stabilizer for the high-temperature high-density cement slurry has no adverse effect on the comprehensive performance of the cement slurry, can improve the high-temperature stability of the cement slurry, and ensures the well cementation quality. The high-temperature high-density cement slurry suspension stabilizer provided by the invention has a good application prospect in special well cementation operations such as high-temperature deep wells, highly deviated wells, horizontal wells and the like.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (6)
1. The high-temperature high-density cement slurry suspension stabilizer is characterized by comprising a structural unit A shown in a formula (I), a structural unit B shown in a formula (II), a structural unit C shown in a formula (III) and a result unit D shown in a formula (IV);
wherein the structural percentages of the structural units a, B, C and D are x, y, z and q, and x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z and q is 1;
wherein R is 1 、R 2 、R 3 、R 4 Same or different and is H or C 1 -C 4 One of substituted or unsubstituted alkyl groups of (a);
wherein n is 17, 19 or 21;
wherein, the monomers A, B, C and D are used in such amounts that the structural percentages of the structural unit A, the structural unit B, the structural unit C and the structural unit D contained in the suspension stabilizer for warm high-density cement slurry are x, y, z and q, x =26.72-50.96%, y =44.38-66.78%, z =3.57-5.60%, q =0.71-1.31%, and the sum of x, y, z and q is 1.
2. A high temperature high density cement slurry suspension stabilizer as claimed in claim 1, wherein R 1 、R 2 、R 3 And R 4 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl;
3. the high-temperature high-density cement slurry suspension stabilizer of claim 1, wherein the weight average molecular weight of the suspension stabilizer is 800-1400 ten thousand.
4. The method of claim 1, wherein the monomers A, B, C and D are used in a weight ratio of (34.55-86.27): (36.00-66.00): (16.67-33.33): 1;
wherein R is 5 、R 6 、R 7 And R 8 The same or different is one of H, methyl, ethyl, n-propyl, isopropyl or butyl;
wherein the total usage of the monomer A, the monomer B, the monomer C and the monomer D is 30-40 wt% of the usage of the deionized water;
wherein the pH value of the mixed solution of the monomer A, the monomer B, the monomer C, the monomer D and the deionized water is 7-10.
5. The preparation method of the suspension stabilizer for high-temperature high-density cement slurry according to claim 1, wherein the initiator adopts a redox initiation system, wherein the oxidant is at least one of persulfate, ammonium persulfate and potassium persulfate, the reductant is at least one of sodium bisulfite, ammonium hydroxide and triethylamine, and the molar ratio of the used amounts of the oxidant to the used amount of the reductant is (2-4): (1-2) in an amount of 0.1 to 1% by weight based on the total amount of the monomer A, the monomer B, the monomer C and the monomer D.
6. The preparation method of the high-temperature high-density cement slurry suspension stabilizer according to claim 1, wherein the copolymerization reaction conditions comprise: reacting for 6-12h under the condition of standing at the temperature of 30-60 ℃; and under the constant stirring of the stirring speed of 100-200r/min, the initiator is dripped into the mixed solution of the monomer A, the monomer B, the monomer C, the monomer D and the deionized water at the dripping speed of 0.5-1.5 mL/min.
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