High temperature viscosity increasing multifunctional additive for oil well cement and its preparation method and application

Abstract

The present invention belongs to the technical field of oilfield chemistry, and specifically relates to a high-temperature tackifying multifunctional additive for oil well cement, and a preparation method and application thereof. The high-temperature tackifying multifunctional additive for oil well cement of the present invention is formed by copolymerization of the following monomers: 2-10 parts by weight of anionic monomer, 0.5-5 parts by weight of rigid monomer, 0.2-3.8 parts by weight of carboxylic acid monomer, 0.5-4.5 parts by weight of cationic monomer, 0.5-10 parts by weight of ether monomer, and 0.2-5.5 parts by weight of cross-linking monomer. The high-temperature tackifying multifunctional additive for oil well cement of the present invention has low viscosity, good fluidity, good compatibility, multiple functions, is beneficial to offshore cementing construction operations, and improves operating efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a high-temperature viscosity-increasing multifunctional additive for oil well cement, a preparation method and application thereof. Background Art

[0002] During cementing operations, the influence of temperature on the stability of cement slurry is extremely obvious. At present, high molecular polymer type admixtures are often used in cement slurries under high temperature conditions, such as polymer filtration reducers and high temperature retarders synthesized with AMPS as the basic monomer. Such admixtures have good high temperature resistance and can meet the basic performance of cement slurry under high temperature conditions. However, temperature has an inevitable influence on high molecular polymers. As the temperature rises, the viscosity of the polymer decreases, and the suspension capacity of solid phase particles decreases, which causes the viscosity of cement slurry to decrease under high temperature conditions, resulting in sedimentation instability, increasing the density difference between the upper and lower cement slurry columns, and deteriorating the strength and bonding properties of the top cement stone, which directly affects the cementing quality.

[0003] A large number of researchers have reported on oil well cement stabilizers that can be used under high temperature conditions. According to literature or patents, the materials used to improve the high temperature stability of cement slurry are mainly the following:

[0004] (1) Ultrafine materials, such as nano-silicon and ultrafine cement, can increase the viscosity of cement slurry to a certain extent by reducing free water, reducing the distance between solid phase particles and increasing van der Waals force. However, such materials can easily cause the viscosity of cement slurry to be high at low temperatures and to drop sharply at high temperatures.

[0005] (2) Clay materials, such as bentonite, also have a certain suspension effect under high temperature conditions, but they also have unfavorable factors such as high viscosity at low temperatures and affecting the strength development of cement paste;

[0006] (3) Adding natural or synthetic high molecular weight polymers is currently the most common way to improve the stability of cement slurry. Commonly used polymers include glue, AMPS polymers, latex, etc., which can effectively increase the liquid phase viscosity. However, there is a natural limitation that the polymer viscosity decreases at high temperature.

[0007] (4) Thermal thickening polymers. In recent years, literature and patents have reported on this type of polymer, which can increase the viscosity of the polymer or cement slurry as the temperature rises, thereby improving the stability of the cement slurry at high temperatures. However, this type of material has the problem of difficult control of the thickening effect and a low temperature limit, and is rarely used in practice. Summary of the invention

[0008] The purpose of the present invention is to provide a high-temperature viscosity-increasing multifunctional additive for oil well cement and a preparation method and application thereof in view of the defects of the prior art.

[0009] Specifically, the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention is prepared by copolymerizing the following monomers: 2-10 parts by weight of anionic monomers, 0.5-5 parts by weight of rigid monomers, 0.2-3.8 parts by weight of carboxylic acid monomers, 0.5-4.5 parts by weight of cationic monomers, 0.5-10 parts by weight of ether monomers, and 0.2-5.5 parts by weight of crosslinking monomers.

[0010] The above-mentioned high-temperature thickening multifunctional additive for oil well cement is prepared by copolymerizing the following monomers: 4-8 parts by weight of anionic monomer, 0.5-2 parts by weight of rigid monomer, 0.5-1 parts by weight of carboxylic acid monomer, 0.5-2.5 parts by weight of cationic monomer, 0.5-5 parts by weight of ether monomer and 0.2-2 parts by weight of cross-linking monomer.

[0011] In the above-mentioned high-temperature viscosity-increasing multifunctional additive for oil well cement, the anionic monomer includes one or more of 2-acrylamide-2-methylpropanesulfonic acid and 3-allyloxy-2-hydroxy-1-propanesulfonic acid.

[0012] In the above-mentioned high-temperature viscosity-increasing multifunctional additive for oil well cement, the rigid monomer includes one or more of sodium styrene sulfonate, N,N-dimethylacrylamide, and N-hydroxymethylacrylamide.

[0013] In the above-mentioned high-temperature viscosity-increasing multifunctional additive for oil well cement, the carboxylic acid monomer includes one or more of acrylic acid, maleic anhydride and itaconic acid.

[0014] In the above-mentioned high-temperature viscosity-increasing multifunctional additive for oil well cement, the cationic monomer includes one or more of methacryloyloxyethyl trimethyl ammonium chloride, methacryloyl propyl trimethyl ammonium chloride, and dimethyl diallyl ammonium chloride.

[0015] The above-mentioned high-temperature tackifying multifunctional additive for oil well cement, the ether monomer includes one or more of allyl polyoxyethylene ether-1200, allyl polyoxyethylene ether-2400, allyl polyoxyethylene ether-3600, methyl allyl polyoxyethylene ether-1200, methyl allyl polyoxyethylene ether-2400, methyl allyl polyoxyethylene ether-3600, isopentanol polyoxyethylene ether-1200, isopentanol polyoxyethylene ether-2400, and isopentanol polyoxyethylene ether-3600.

[0016] The high-temperature tackifying multifunctional additive for oil well cement, wherein the crosslinking monomers include one or more of polyethylene glycol diacrylate-200, polyethylene glycol diacrylate-400, polyethylene glycol diacrylate-600, trimethylolpropane triacrylate, and ethylene glycol diallyl ether.

[0017] On the other hand, the present invention provides a method for preparing the above-mentioned high-temperature viscosity-increasing multifunctional additive for oil well cement, comprising:

[0018] (1) Add deionized water, anionic monomer, alkali, rigid monomer, carboxylic acid monomer, cationic monomer, ether monomer, crosslinking monomer, and molecular weight regulator into a container in sequence and stir to mix;

[0019] (2) introducing nitrogen and heating, adding initiator to initiate polymerization reaction, and raising the temperature after the reaction temperature stabilizes;

[0020] (3) Cool down to stop the reaction, add auxiliary agent and stir evenly to obtain high temperature thickening multifunctional auxiliary agent for oil well cement.

[0021] In the preparation method of the high-temperature viscosity-increasing multifunctional additive for oil well cement, the molecular weight regulator comprises one or more of tert-dodecyl mercaptan, sodium vinyl sulfonate, sodium methacrylic sulfonate and sodium formate.

[0022] In the preparation method of the high-temperature viscosity-increasing multifunctional additive for oil well cement, the initiator includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0023] The preparation method of the high-temperature viscosity-increasing multifunctional auxiliary agent for oil well cement, the auxiliary agent includes one or more of ethylene glycol, polyethylene glycol-200, polyethylene glycol-400, polyethylene glycol diacrylate-200, polyethylene glycol diacrylate-400.

[0024] In the above-mentioned method for preparing a high-temperature viscosity-increasing multifunctional additive for oil well cement, in step (2), the heating temperature is 40-65°C, and the temperature after heating is 70-85°C.

[0025] In another aspect, the present invention further provides the use of the above-mentioned high-temperature tackifying multifunctional additive for oil well cement or the high-temperature tackifying multifunctional additive for oil well cement prepared by the above-mentioned preparation method in preparing cement slurry.

[0026] The technical solution of the present invention has the following beneficial effects:

[0027] (1) The high-temperature viscosity-enhancing multifunctional additive for oil well cement of the present invention effectively improves the comprehensive performance of high-temperature cement slurry, which is beneficial to the subsequent development of high-temperature and ultra-high-temperature wells;

[0028] (2) The high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention has low viscosity, good fluidity, good compatibility, and multiple functions, which is beneficial to offshore cementing operations and improves operation efficiency;

[0029] (3) The high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention has high-temperature thermal viscosity-increasing properties and can effectively improve the viscosity and suspension stability of cement slurry at high temperatures (90-210°C);

[0030] (4) The high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention has the function of reducing water loss of cement slurry. It can be used alone as a fluid loss reducer for oil well cement below 90°C, and can synergize with a fluid loss reducer or other auxiliary fluid loss reducing materials at 90-210°C to effectively reduce high-temperature water loss.

[0031] (5) The high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention has a dispersing effect in cement slurry at room temperature, which is beneficial to improving the fluidity of cement slurry and increasing the mixing efficiency of cement slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0033] Figure 1 The shutdown test curve of cement slurry formula 4 (150℃);

[0034] Figure 2 The shutdown test curve of cement slurry formula 2 (150℃);

[0035] Figure 3 The shutdown test curve of cement slurry formula 2 (180℃);

[0036] Figure 4 The shutdown test curve of cement slurry formula 3 (210℃). DETAILED DESCRIPTION

[0037] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0038] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0039] In recent years, there are more and more high-temperature and ultra-high-temperature wells. The performance of existing high-temperature cement slurry cannot fully meet the requirements of high-temperature well cementing, especially the poor high-temperature suspension stability of cement slurry. At present, high-temperature cement slurry usually uses polymers to increase the viscosity of cement slurry and improve the high-temperature suspension stability. Conventional polymers have the characteristics of increasing viscosity at low temperatures and becoming thinner at high temperatures, which seriously affects the use of cement slurry at high temperatures. At the same time, the damage of high temperature to the water loss performance of cement slurry, as well as the high viscosity of cement slurry at room temperature and poor mixing ability, have seriously affected the subsequent development of high-temperature wells.

[0040] In order to solve the problem of poor stability of high-temperature cement slurry, more and more high-temperature suspension stabilizers and high-temperature polymers have been developed. In recent years, polymers with thermal viscosity-increasing properties have also appeared to improve the stability of cement slurry at high temperatures. Although these products have certain functions of improving suspension stability and improving the characteristics of reducing high-temperature viscosity, they also have some defects, such as poor temperature resistance, side effects that affect the fluidity and strength of cement slurry, and difficult to control high-temperature viscosity-increasing effects. They are rarely used in practice or the application effect is not obvious.

[0041] To this end, the present invention provides a high-temperature viscosity-increasing multifunctional additive for oil well cement, which is prepared by copolymerizing the following monomers: anionic monomers, rigid monomers, carboxylic acid monomers, cationic monomers, ether monomers, and crosslinking monomers.

[0042] The high-temperature thickening multifunctional additive for oil well cement of the present invention forms a polymer main chain with anionic monomers, rigid monomers and carboxylic acid monomers, has heat resistance, salt resistance and strong adsorption, can effectively adsorb cement particles and reduce cement slurry filtration loss; cationic monomers can improve the polymer's resistance to polyvalent cations such as calcium and magnesium, prevent the polymer from complexing with the polyvalent cations, and improve the fluidity of cement slurry; ether monomers provide long side chains, provide steric hindrance and electrostatic repulsion, can improve the fluidity of cement slurry and prevent cement particles from agglomerating, and have hydrophobic association, can improve the intermolecular force at high temperature, and can improve the thermal dilution effect of the polymer after being cross-linked and forming a specific structure, and improve the high-temperature sedimentation stability; cross-linking monomers have a multi-double bond structure, can change the chain molecular structure into a network molecular structure, improve the molecular stability of the polymer at high temperature, and have an ester group and a polyhydroxy group, and form a strong adsorption structure of polyhydroxy and carboxyl groups after being hydrolyzed at high temperature, improve the high-temperature thermal dilution effect, and improve the high-temperature sedimentation stability.

[0043] The various monomers involved in the high temperature viscosity increasing multifunctional additive for oil well cement of the present invention are introduced in detail below:

[0044] Anionic monomer

[0045] The anionic monomer contains a long-chain hydrophilic group and as a polymer backbone has temperature and salt resistance properties.

[0046] Preferably, the anionic monomer used in the present invention includes one or more of 2-acrylamido-2-methylpropanesulfonic acid and 3-allyloxy-2-hydroxy-1-propanesulfonic acid.

[0047] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the anionic monomer is 2-10 parts by weight.

[0048] Practice has shown that when the ratio of anionic monomers is too small, the polymerization efficiency is low and it is not conducive to the fluidity of cement slurry; when the ratio of anionic monomers is too large, the filtration loss performance of polymer on cement slurry is weakened.

[0049] In some preferred embodiments, the proportion of the anionic monomer is 4-8 parts by weight.

[0050] Rigid monomer

[0051] Rigid monomers can increase the rigidity of long-chain polymer molecules and improve their high-temperature resistance.

[0052] Preferably, the rigid monomer used in the present invention includes one or more of sodium styrene sulfonate, N,N-dimethylacrylamide, and N-hydroxymethylacrylamide.

[0053] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the rigid monomer is 0.5-5 parts by weight.

[0054] Practice has shown that when the ratio of rigid monomer is too small, the filtration loss control performance is weakened; when the ratio of rigid monomer is too large, the fluidity and high-temperature sedimentation stability of cement slurry are reduced.

[0055] In some preferred embodiments, the ratio of the rigid monomer is 0.5-2 parts by weight.

[0056] Carboxylic acid monomers

[0057] Carboxylic acid monomers contain carboxyl groups, which increase the adsorption of polymers to cement particles through van der Waals forces and intermolecular hydrogen bonds, thereby improving the ability of polymers to control water loss.

[0058] Preferably, the carboxylic acid monomers used in the present invention include one or more of acrylic acid, maleic anhydride and itaconic acid.

[0059] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the carboxylic acid monomer is 0.2-3.8 parts by weight.

[0060] Practice has shown that when the ratio of carboxylic acid monomers is too small, the fluid loss control performance is weakened and the fluidity of cement slurry is poor; when the ratio of carboxylic acid monomers is too large, the fluid loss control performance is also reduced and the polymerization efficiency is reduced.

[0061] In some preferred embodiments, the proportion of the carboxylic acid monomer is 0.5-1 part by weight.

[0062] Cationic monomer

[0063] Cationic monomers can improve the polymer's resistance to metal ions, preventing the metal ions from complexing with polymer molecules and affecting the fluidity of cement slurry.

[0064] Preferably, the cationic monomer used in the present invention includes one or more of methacryloyloxyethyltrimethylammonium chloride, methacryloylpropyltrimethylammonium chloride, and dimethyldiallylammonium chloride.

[0065] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the cationic monomer is 0.5-4.5 parts by weight.

[0066] Practice has shown that when the ratio of cationic monomers is too small, the mixing ability and fluidity of cement slurry will be reduced; when the ratio of cationic monomers is too large, the filtration loss control performance will be reduced.

[0067] In some preferred embodiments, the proportion of the cationic monomer is 0.5-2.5 parts by weight.

[0068] Ether monomers

[0069] Ether monomers have long side chain structures, which can form a steric hindrance effect, improve the fluidity of cement slurry and prevent cement particles from agglomerating. At the same time, due to their hydrophobic association, they can improve the intermolecular forces at high temperatures. After cross-linking and forming a specific structure, they can improve the thermal dilution effect of the polymer and enhance the stability of the slurry.

[0070] Preferably, the ether monomers used in the present invention include one or more of allyl polyoxyethylene ether-1200, allyl polyoxyethylene ether-2400, allyl polyoxyethylene ether-3600, methyl allyl polyoxyethylene ether-1200, methyl allyl polyoxyethylene ether-2400, methyl allyl polyoxyethylene ether-3600, isopentanol polyoxyethylene ether-1200, isopentanol polyoxyethylene ether-2400, and isopentanol polyoxyethylene ether-3600.

[0071] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the ether monomer is 0.5-10 parts by weight.

[0072] Practice has shown that when the ratio of ether monomers is too small, the thermal viscosity increasing effect is weakened and the high-temperature sedimentation stability is reduced; when the ratio of ether monomers is too large, the filtration loss control performance is reduced and the polymerization efficiency is reduced.

[0073] In some preferred embodiments, the proportion of the ether monomer is 0.5-5 parts by weight.

[0074] Crosslinking monomers

[0075] Crosslinking monomers can make polymer molecules form a certain structure, improve heat resistance, and enhance the stability of cement slurry. Crosslinking monomers have multiple double bond structures, which can change the chain molecular structure into a network molecular structure, improve the molecular stability of polymers at high temperatures, and have ester groups and polyhydroxyl groups. After hydrolysis at high temperatures, they form a strong adsorption structure of polyhydroxyl and carboxyl groups, improve the high-temperature thermal dilution effect, and improve the high-temperature sedimentation stability.

[0076] Preferably, the cross-linking monomers used in the present invention include one or more of polyethylene glycol diacrylate-200, polyethylene glycol diacrylate-400, polyethylene glycol diacrylate-600, trimethylolpropane triacrylate, and ethylene glycol diallyl ether.

[0077] In the high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention, the proportion of the cross-linking monomer is 0.2-5.5 parts by weight.

[0078] Practice has shown that when the ratio of cross-linking monomers is too small, the thermal viscosity-increasing effect is weakened and the high-temperature sedimentation stability is reduced; when the ratio of cross-linking monomers is too large, the fluidity of the cement slurry is reduced and the filtration loss control effect is reduced.

[0079] In some preferred embodiments, the proportion of cross-linking monomers is 0.2-2 parts by weight.

[0080] The high-temperature viscosity-increasing multifunctional additive for oil well cement of the present invention can not only effectively improve the suspension stability of cement slurry under high temperature and ultra-high temperature conditions and improve the phenomenon of reduced high-temperature viscosity of polymers, but also has multiple functions. It has a certain dispersibility function that can improve the fluidity of high-temperature cement slurry and improve the mixing efficiency of cement slurry; it has the function of reducing the filtration loss of cement slurry at high temperature, which can effectively reduce the damage of high temperature to the filtration loss capacity of cement slurry and reduce the dosage of polymer filtration loss reducer.

[0081] On the other hand, the present invention also provides a method for preparing the high-temperature viscosity-increasing multifunctional additive for oil well cement, comprising:

[0082] (1) Add deionized water, anionic monomer, alkali, rigid monomer, carboxylic acid monomer, cationic monomer, ether monomer, crosslinking monomer, and molecular weight regulator into a container in sequence and stir to mix;

[0083] (2) introducing nitrogen and heating, adding initiator to initiate polymerization reaction, and raising the temperature after the reaction temperature stabilizes;

[0084] (3) After the reaction is completed, the temperature is lowered, and auxiliary agents are added and stirred evenly to obtain a high-temperature thickening multifunctional auxiliary agent for oil well cement.

[0085] Among them, the chemical substances and proportions contained in the anionic monomers, rigid monomers, carboxylic acid monomers, cationic monomers, ether monomers, and crosslinking monomers are the same as those in the high-temperature thickening multifunctional additive for oil well cement provided in the first aspect of the present invention, and the present invention will not repeat them here.

[0086] Wherein, the molecular weight regulator is used to control the molecular weight of the polymer to prevent the reaction from being too fast or the molecular weight from being too high. Preferably, the molecular weight regulator includes one or more of tert-dodecyl mercaptan, sodium vinyl sulfonate, sodium methacrylic sulfonate, and sodium formate.

[0087] More preferably, the molecular weight regulator is contained in an amount of 0.01-0.5 parts by weight.

[0088] Wherein, the initiator is used to initiate the polymerization reaction. Preferably, the initiator includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0089] More preferably, the ratio of the initiator is 0.1-0.5 parts by weight.

[0090] The auxiliary agent can form a combined effect with the main polymer agent to improve the high temperature viscosity increasing property of the polymer and improve the high temperature stability of the cement slurry. Preferably, the auxiliary agent includes one or more of ethylene glycol, polyethylene glycol-200, polyethylene glycol-400, polyethylene glycol diacrylate-200, and polyethylene glycol diacrylate-400.

[0091] More preferably, the proportion of the auxiliary agent is 15-35 parts by weight.

[0092] In another aspect, the present invention also provides the use of the high-temperature viscosity-increasing multifunctional additive for oil well cement in preparing cement slurry.

[0093] The high temperature viscosity increasing multifunctional additive for oil well cement of the present invention can be used to prepare a cement having a density of 1.90 g / cm 3 , cement slurry with water-cement ratio of 0.44.

[0094] Among them, when the bottom hole circulation temperature is within 90°C, the multifunctional additive of the present invention can be used alone as a fluid loss reducer, such as cement slurry formula 1: 100% Shandong "G" grade cement + 4% multifunctional additive + 0.5% retarder + 0.25% defoamer + 40% fresh water; when the high temperature condition is above 90°C, the multifunctional additive of the present invention needs to be used in combination with a fluid loss reducer, such as cement slurry formula 2: 100% Shandong "G" grade cement + 35% silica powder + 6% fluid loss reducer + 1.5% multifunctional additive + 3% retarder + 0.25% defoamer + 46.5% fresh water; cement slurry formula 3: 100% Shandong "G" grade cement + 35% silica powder + 7% fluid loss reducer + 2% multifunctional additive + 4% retarder + 0.25% defoamer + 46.5% fresh water.

[0095] Example

[0096] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions. The raw materials used in the following examples are all conventionally purchased.

[0097] Example 1

[0098] (1) Weigh a certain weight of reactants: 200 g of deionized water, 38.54 g of 2-acrylamido-2-methylpropanesulfonic acid, 11.32 g of sodium hydroxide, 7.25 g of N,N-dimethylacrylamide, 3.23 g of acrylic acid, 6.65 g of methacryloylpropyltrimethylammonium chloride, 13.40 g of allyl polyoxyethylene ether-2400, 4.68 g of polyethylene glycol diacrylate-400, and 0.40 g of sodium formate, add them into a reaction container in sequence, stir and mix them evenly, and control the stirring speed at 120 r / min;

[0099] (2) Place the reaction vessel in a water bath, heat to 55°C, and introduce nitrogen for 10 min to displace the oxygen in the vessel.

[0100] (3) Prepare 6.40 g of 10% sodium persulfate solution, add dropwise to initiate polymerization reaction, and after the reaction temperature stabilizes, raise the temperature to 82 °C and maintain the reaction for 4 h;

[0101] (4) Cooling down to stop the reaction, adding 36.8 g of ethylene glycol and stirring evenly, and obtaining a high-temperature thickening multifunctional additive I for oil well cement.

[0102] Example 2

[0103] (1) Weigh a certain weight of reactants: 212 g of deionized water, 45.60 g of 2-acrylamido-2-methylpropanesulfonic acid, 9.82 g of calcium hydroxide, 10.35 g of N,N-dimethylacrylamide, 5.10 g of maleic anhydride, 2.74 g of dimethyldiallylammonium chloride, 8.46 g of methyl allyl polyoxyethylene ether-3600, 2.58 g of polyethylene glycol diacrylate-600, and 0.68 g of sodium methyl propene sulfonate, add them into a reaction container in sequence, stir and mix evenly, and control the stirring speed at 120 r / min;

[0104] (2) Place the reaction vessel in a water bath, heat to 60°C, and introduce nitrogen for 10 min to displace the oxygen in the vessel.

[0105] (3) Prepare 4.50 g of 10% ammonium persulfate solution and add it dropwise to initiate the polymerization reaction. After the reaction temperature stabilizes, raise the temperature to 78°C and maintain the reaction for 4 hours;

[0106] (4) Cool down to stop the reaction, add 40.50 g of polyethylene glycol-400 and stir evenly to obtain high-temperature thickening multifunctional additive II for oil well cement.

[0107] Example 3

[0108] (1) Weigh a certain weight of reactants: deionized water 186 g, 3-allyloxy-2-hydroxy-1-propanesulfonic acid 51.88 g, sodium hydroxide 13.34 g, N-hydroxymethyl acrylamide 6.41 g, itaconic acid 3.22 g, dimethyl diallyl ammonium chloride 2.74 g, isopentanol polyoxyethylene ether-2400 7.15 g, trimethylolpropane triacrylate 0.89 g, sodium vinyl sulfonate 0.46 g, add them into a reaction container in sequence, stir and mix evenly, and control the stirring speed at 120 r / min;

[0109] (2) Place the reaction vessel in a water bath, heat to 53°C, and introduce nitrogen for 10 min to displace the oxygen in the vessel.

[0110] (3) Prepare 6.15 g of 10% potassium persulfate solution and add dropwise to initiate polymerization. After the reaction temperature stabilizes, raise the temperature to 85 °C and maintain the reaction for 4 h.

[0111] (4) Cooling down to stop the reaction, adding 32.26 g of polyethylene glycol diacrylate-200 and stirring evenly, thereby obtaining a high-temperature thickening multifunctional additive III for oil well cement.

[0112] Example 4

[0113] Prepare cement slurry according to formula 1-4, as follows:

[0114] Formula 1: 100% Shandong "G" grade cement + 4% multifunctional additive + 0.5% retarder (C-R21L) + 0.25% defoamer (C-DF60L) + 40% fresh water;

[0115] Formula 2: 100% Shandong "G" grade cement + 35% silica fume + 6% fluid loss reducer (C-FL80L) + 1.5% multifunctional additive + 3% retarder (C-R40L) + 0.25% defoamer (C-DF60L) + 46.5% fresh water;

[0116] Formula 3: 100% Shandong "G" grade cement + 35% silica fume + 7% fluid loss reducer (C-FL80L) + 2% multifunctional additive + 4% retarder (C-R40L) + 0.25% defoamer (C-DF60L) + 46.5% fresh water;

[0117] Formula 4: 100% Shandong "G" grade cement + 35% silica fume + 7.5% fluid loss reducer (C-FL80L) + 3% retarder (C-R40L) + 0.25% defoamer (C-DF60L) + 46.5% fresh water;

[0118] Formula 5: 100% Shandong "G" grade cement + 4% fluid loss reducer (C-FL80L) + 0.5% retarder (C-R21L) + 0.25% defoamer (C-DF60L) + 40% fresh water;

[0119] Formula 6: 100% Shandong "G" grade cement + 35% silica fume + 6% fluid loss reducer (C-FL80L) + 3% retarder (C-R40L) + 0.25% defoamer (C-DF60L) + 47% fresh water;

[0120] Formula 7: 100% Shandong "G" grade cement + 35% silica fume + 7% fluid loss reducer (C-FL80L) + 4% retarder (C-R40L) + 0.25% defoamer (C-DF60L) + 48.5% fresh water.

[0121] Performance Testing

[0122] Cement slurry was prepared using multifunctional additive I according to formula 2, and cement slurry was prepared according to cement slurry formula 4, and the performances of the two were compared. The comparison results are shown in Table 1.

[0123] Table 1 Performance comparison of cement slurry prepared with high temperature viscosity-enhancing multifunctional additive and blank control formula

[0124]

[0125] Formula 2 and Formula 4 are based on the principle that the 150℃ API water loss performance of cement slurry is basically the same. The amount of water loss reducer in Formula 2 with the addition of multifunctional additives is lower than that in Formula 4. At the same time, the water loss performance of the two formulas is consistent.

[0126] From the results in Table 1 above, it can be seen that the high-temperature viscosity-increasing multifunctional additive is beneficial to the fluidity of cement slurry, improves the mixing efficiency of cement slurry, and has a certain ability to control water loss. After the cement slurry is cured at 150°C, the rheological parameters of the cement slurry with the addition of the high-temperature viscosity-increasing multifunctional additive are significantly higher than those of the control group experiment, and the results of the shutdown experiment are better, indicating that the high-temperature viscosity-increasing multifunctional additive has the characteristics of high-temperature viscosity-increasing, which is beneficial to improve the stability of cement slurry at high temperatures.

[0127] Cement slurry was prepared according to the formula shown in Table 2-3, and the performance was evaluated. Among them, the static filtration, rheological properties, thickening time, compressive strength, mixing time and other tests were measured in accordance with the provisions of GB / T 19139-2012 "Test Methods for Oil Well Cement". The shutdown test is a high-temperature and high-pressure thickening test in accordance with the standard. After the temperature rises to the experimental temperature (90 / 150 / 180 / 210℃), it continues to run for 30 minutes, and the thickener motor is turned off for 30 minutes and then turned on again to observe the change in consistency in the thickening curve. If the consistency rises by more than 60bc, it fails. The test results are shown in Table 2-3.

[0128] Table 2 Performance evaluation of cement slurry prepared with high temperature viscosity-enhancing multifunctional additives

[0129]

[0130] Table 3 Performance evaluation of cement slurry prepared without adding high temperature viscosity increasing multifunctional additives

[0131]

[0132] In Table 2-3, Experiment No. 1 is the experimental data of high-temperature thickening multifunctional additive as a fluid loss reducer at 90°C. It can be seen that at this temperature, the water loss of cement slurry can be effectively controlled, and at the same time, it has no adverse effect on the rheology, thickening time and compressive strength of cement slurry; Experiment No. 7 is the control experiment of Experiment No. 1, and the experimental data of using the fluid loss reducer C-FL80L alone. It can be seen from the data in the table that when the addition amount is the same and other admixtures in the cement slurry are consistent, the water loss performance, thickening and strength performance are similar. The rheological properties are different due to the different viscosities of the two polymers. The rheological parameters of the cement slurry using the fluid loss reducer alone are relatively High; Experiment No. 8, 9, 10 are blank control experiments of Experiment No. 4, 5, 6, respectively. The performance of cement slurry without adding multifunctional additives. It can be seen from the data in the table that the water loss in the blank experiment increased significantly, indicating that the multifunctional additive helps to reduce the water loss of cement slurry; at the same time, the rheological data at 90℃ decreased slightly, indicating that the addition of multifunctional additives slightly increased the viscosity of cement slurry at 90℃; the thickening time and compressive strength did not change much, indicating that the multifunctional additive had no significant effect on the thickening and strength properties; the blank experiment thickening shutdown experiment failed, indicating that the multifunctional additive effectively improved the suspension stability of cement slurry. Under high temperature conditions (150 / 180 / 210℃), the success of the thickening shutdown experiment showed that after high temperature curing, the cement slurry had good stability and no sedimentation after standing for 30 minutes, and had no adverse effect on the rheology, thickening time and compressive strength of the cement slurry.

[0133] Formula 4 in Example 4 is a cement slurry formula without adding multifunctional additives. The 150°C thickening shutdown test shows Figure 1 The results of the thickening shutdown experiment of experiment number 4-6 in Table 2 are shown in Figure 2-4 .

[0134] Figure 1 This is the thickening curve of cement slurry formula 4 in the shutdown experiment at 150°C. After 30 minutes of shutdown, the consistency rises to 100bc, indicating that the cement slurry has obvious sedimentation at this temperature and the sedimentation stability is poor. Figure 2 This is the shutdown test curve of cement slurry formula 2 at 150℃. Figure 3 This is the shutdown test curve of cement slurry formula 2 at 180℃. Figure 4 This is the shutdown test curve of cement slurry formula 3 at 210℃. Figure 2-4 The results show that the cement slurry containing high-temperature viscosity-increasing multifunctional additives did not show a significant increase in consistency after being shut down for 30 minutes, indicating that the cement slurry did not show significant sedimentation at this temperature and the sedimentation stabilizer was good.

[0135] The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only used to describe the present invention and should not be understood as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to these embodiments should be deemed to be included in the scope of the claims of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined in the claims.

Claims

1. A high temperature viscosity increasing multifunctional additive for oil well cement, characterized in that: It is formed by copolymerizing the following monomers: 2-10 parts by weight of anionic monomer, 0.5-5 parts by weight of rigid monomer, 0.2-3.8 parts by weight of carboxylic acid monomer, 0.5-4.5 parts by weight of cationic monomer, 0.5-10 parts by weight of ether monomer, and 0.2-5.5 parts by weight of cross-linking monomer; The anionic monomers include one or more of 2-acrylamido-2-methylpropanesulfonic acid and 3-allyloxy-2-hydroxy-1-propanesulfonic acid; the rigid monomers include one or more of sodium styrene sulfonate, N,N-dimethylacrylamide and N-hydroxymethylacrylamide; the carboxylic acid monomers include one or more of acrylic acid, maleic anhydride and itaconic acid; the cationic monomers include one or more of methacryloyloxyethyl trimethylammonium chloride, methacryloyl propyl trimethylammonium chloride and dimethyl diallyl ammonium chloride; the ether monomers include allyl polyoxyethylene ether-1200, olefin ... One or more of propyl polyoxyethylene ether-2400, allyl polyoxyethylene ether-3600, methyl allyl polyoxyethylene ether-1200, methyl allyl polyoxyethylene ether-2400, methyl allyl polyoxyethylene ether-3600, isopentanol polyoxyethylene ether-1200, isopentanol polyoxyethylene ether-2400, and isopentanol polyoxyethylene ether-3600; the cross-linking monomers include one or more of polyethylene glycol diacrylate-200, polyethylene glycol diacrylate-400, polyethylene glycol diacrylate-600, trimethylolpropane triacrylate, and ethylene glycol diallyl ether.

2. The high temperature viscosity increasing multifunctional additive for oil well cement according to claim 1, characterized in that: It is prepared by copolymerizing the following monomers: 4-8 parts by weight of anionic monomers, 0.5-2 parts by weight of rigid monomers, 0.5-1 parts by weight of carboxylic acid monomers, 0.5-2.5 parts by weight of cationic monomers, 0.5-5 parts by weight of ether monomers, and 0.2-2 parts by weight of cross-linking monomers.

3. The method for preparing the high temperature viscosity increasing multifunctional additive for oil well cement according to any one of claims 1 to 2, characterized in that: include: (1) Add deionized water, anionic monomer, alkali, rigid monomer, carboxylic acid monomer, cationic monomer, ether monomer, crosslinking monomer, and molecular weight regulator into a container in sequence and stir to mix; (2) introducing nitrogen and heating, adding initiator to initiate polymerization reaction, and raising the temperature after the reaction temperature stabilizes; (3) Cool down to stop the reaction, add auxiliary agent and stir evenly to obtain high temperature thickening multifunctional auxiliary agent for oil well cement.

4. The method for preparing the high temperature viscosity increasing multifunctional additive for oil well cement according to claim 3, characterized in that: The molecular weight regulator includes one or more of tert-dodecyl mercaptan, sodium vinyl sulfonate, sodium methacrylic sulfonate, and sodium formate.

5. The method for preparing the high temperature viscosity increasing multifunctional additive for oil well cement according to claim 3, characterized in that: The initiator includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

6. The method for preparing the high temperature viscosity increasing multifunctional additive for oil well cement according to claim 3, characterized in that: The auxiliary agent includes one or more of ethylene glycol, polyethylene glycol-200, polyethylene glycol-400, polyethylene glycol diacrylate-200, and polyethylene glycol diacrylate-400.

7. The method for preparing the high temperature viscosity increasing multifunctional additive for oil well cement according to claim 3, characterized in that: In step (2), the heating temperature is 40-65°C, and the temperature after heating is 70-85°C.

8. Use of the high-temperature viscosity-increasing multifunctional additive for oil well cement according to any one of claims 1 to 2 or the high-temperature viscosity-increasing multifunctional additive for oil well cement prepared by the preparation method according to any one of claims 3 to 7 in preparing cement slurry.

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