Seawater-resistant and salt-resistant emulsion fluid loss agent for well cementation as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oilfield chemistry, and relates to a well cementation fluid loss agent technology, in particular to a seawater-resistant salt-resistant emulsion fluid loss agent for well cementation as well as a preparation method and application of the seawater-resistant salt-resistant emulsion fluid loss agent. The anti-seawater salt-resistant emulsion fluid loss agent for well cementation provided by the invention is formed by copolymerization of sulfo group-containing alkenyl monomers, acylamino-containing alkenyl monomers, carboxyl-containing monomers, long side chain-containing functional monomers and cross-linking monomers. The seawater-resistant and salt-resistant emulsion fluid loss agent for well cementation is good in application universality, has three-resistance characteristics of ultrahigh temperature resistance, seawater resistance and salt resistance, can be applied to fresh water, seawater and saturated brine cement paste from a low-temperature section to an ultrahigh-temperature section (30-210 DEG C), and is excellent in fluid loss control performance.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, relates to cementing fluid loss reducing agent technology, and specifically relates to a seawater and salt-resistant emulsion fluid loss reducing agent for cementing, and a preparation method and application thereof. Background Art

[0002] In the process of cementing, in order to ensure the basic properties of cement slurry, it is often necessary to add oilfield chemical admixtures. Fluid loss reducer refers to an admixture that can control the loss of cement slurry into the formation. During cementing construction, cement slurry will "lose" under the action of pressure difference. If it is not controlled, on the one hand, the cement slurry will thicken and the fluidity will deteriorate, affecting the normal cementing construction; on the other hand, the filtrate will enter the formation and damage the reservoir. Therefore, it is necessary to add fluid loss reducer to the cement slurry.

[0003] Polymer fluid loss additives are a hot topic in fluid loss additive development. A large number of literature reports on the synthesis methods of fluid loss additives prepared by aqueous solution polymerization and their applications in cementing.

[0004] Chinese invention patent application number 200910076431.5 discloses a synthetic polymer oil well cement and a synthesis method thereof, which is prepared by copolymerizing three monomers, namely, sulfonic acid monomer, amide monomer and carboxyl monomer, using aqueous solution, and the mass ratio of the three monomers is (65-95):(1-30):(1-5).

[0005] Chinese invention patent application number 201110063542.X discloses a high temperature resistant dispersed oil well cement fluid loss reducer and a preparation method thereof, which is prepared by polymerization of a quaternary aqueous solution of AMPS, NNDMA, AM and MA, wherein the mass ratio of the four monomers is (50-65):(8-25):(10-15):(5-10).

[0006] Chinese invention patent application number 201310114159.1 discloses a calcium phosphate cement fluid loss reducer, which is prepared by aqueous solution polymerization of five monomers: unsaturated amide monomer, 2-acrylamido-2-methylpropane sulfonic acid, monounsaturated carboxylic acid, methylenebisacrylamide and allyl polyoxyethylene ether, and the mass ratio of the monomers is (20-50): (30-50): (1-10): (0.05-0.5): (1-20).

[0007] Chinese invention patent application number 20141067199.3 discloses a method for preparing a ternary polymer fluid loss reducer for oil well cement, which is prepared by polymerizing an aqueous solution of three monomers: 2-acrylamido-2-methylpropanesulfonic acid, acryloylmorpholine, and acrylic acid, and the mass ratio of the monomers is 139:(20.7-27.5):9.

[0008] Chinese invention patent application number 201510390561.1 discloses a fluid loss reducer suitable for shale gas cementing and a preparation method thereof, which is prepared by copolymerizing four monomers of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N,N-methylenebisacrylamide through aqueous solution, and the mass ratio of the monomers is (0.7-0.9):(39-41):(37-40):(0.1-0.2).

[0009] The Chinese invention patent with application number 201811584202.X discloses a multipolymer fluid loss additive and a preparation method thereof, which is prepared by copolymerizing four monomers, namely 2-acrylamido-2-methylpropanesulfonic acid, acrylic acid, acrylamide morpholine, and N-vinyl pyrrolidone, using an aqueous solution, and the mass ratio of the monomers is (20-40): (2-10): (1-10): (1-10).

[0010] The Chinese invention patent with application number 201910367578.3 discloses a fluid loss additive with anti-thickening and inverted properties, as well as a preparation method and use thereof. The fluid loss additive is prepared by copolymerizing four monomers, AMPS or AMPS salt, nitrogen-substituted acrylamide, quaternary ammonium salt cationic monomer, N-vinyl pyrrolidone or N-vinyl morpholine, using aqueous solution. The mass ratio of the monomers is (60-80): (10-15): (15-25): (5-10).

[0011] Chinese invention patent application number 202010624432.5 discloses an expansive fluid loss additive and a preparation method thereof, which is prepared by copolymerization of a quaternary aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, acrylic acid, and N-vinylpyrrolidone, and the mass ratio of the monomers is (20-40):(3-13):(1-5):(2-13).

[0012] The existing technologies represented by the above patents have made certain breakthroughs in the temperature resistance, functionality, and compatibility of cementing fluid loss reducers, but they are mainly aimed at the situation where the slurry water is fresh water. There are still some problems in the application of seawater and saturated salt water cement slurries. First, the polymer chains are prone to curling in an ionic environment, which affects their adsorption on cement particles, resulting in increased high-temperature and ultra-high-temperature water loss; second, the polymer chains adsorbed on the cement particles will cross-link with the calcium and magnesium ions in the seawater, resulting in bridging and bridging, which leads to thixotropy and thickening of the cement slurry. In addition, most of the existing fluid loss reducers are prepared by aqueous solution polymerization. Although aqueous solution polymerization is simple to operate, it also has certain disadvantages. First, the system has high viscosity in the later stage of the reaction, which makes it difficult to dissipate heat. In severe cases, it is easy to cause explosion and polymerization. The product has poor fluidity and cannot be added directly as a liquid. It is often necessary to use drying methods such as rollers and sprays to dry and crush it into solid powder for reuse, which consumes a lot of energy. Second, the monomer concentration of solution polymerization is often only 20-25% at most, and high-concentration polymer products cannot be prepared. Third, product quality is easily affected by ambient temperature and reaction heat. The larger the production kettle, the more unstable the product quality. Summary of the invention

[0013] The purpose of the present invention is to provide a seawater and salt-resistant emulsion fluid loss reducer for cementing and a preparation method and application thereof in view of the defects of the prior art.

[0014] Specifically, the seawater and salt-resistant emulsion fluid loss reducer for cementing provided by the present invention is copolymerized by sulfonic acid group-containing olefin monomers, amide group-containing olefin monomers, carboxyl group-containing monomers, long side chain functional monomers, and cross-linking monomers.

[0015] The above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing comprises, by weight, 70-80 parts of the sulfonic acid group-containing olefin monomer, 10-20 parts of the amide group-containing olefin monomer, 0-5 parts of the carboxyl group-containing monomer, 1-10 parts of the long side chain functional monomer, and 0-3 parts of the cross-linking monomer.

[0016] The above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing comprises, by weight, 73-78 parts of the sulfonic acid group-containing olefin monomer; 12-18 parts of the amide group-containing olefin monomer; 1-4.5 parts of the carboxyl group-containing monomer; 2-9 parts of the long side chain functional monomer; and 0.5-2.5 parts of the cross-linking monomer.

[0017] In the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing, the sulfonic acid group-containing vinyl monomer is one or more of styrene sulfonic acid, 2-acrylamido-2-methyl-1-propane sulfonic acid, 3-allyloxy-1-hydroxy-1-propane sulfonic acid sodium salt, and sodium methyl allyl sulfonate.

[0018] In the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing, the amide-containing olefin monomer is one or more of acrylamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylacrylamide, N-ethylacetamide, and N-benzylacrylamide.

[0019] In the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing, the carboxyl-containing monomer is one or more of itaconic acid, fumaric acid, maleic anhydride, acrylic acid, and methacrylic acid.

[0020] In the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing, the above-mentioned long side chain functional monomer is one or more of octadecyl methacrylate, dodecyl methacrylate, dodecyl dimethyl allyl ammonium chloride, didodecyl methyl allyl ammonium chloride, and hexadecyl dimethyl allyl ammonium chloride.

[0021] The cross-linking monomer of the seawater and salt-resistant emulsion fluid loss reducer for cementing is ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, divinylbenzene or N,N'-ethylbisacrylamide.

[0022] On the other hand, the present invention provides a method for preparing the above-mentioned seawater and salt-resistant emulsion fluid loss reducing agent for cementing, comprising:

[0023] (1) adding a sulfonic acid group-containing vinyl monomer, a carboxyl group-containing vinyl monomer, an amide group-containing vinyl monomer, and a long side chain functional monomer to deionized water containing an alkali according to a ratio to obtain an aqueous phase;

[0024] (2) adding a composite emulsifier to the solvent oil with stirring to obtain an oil phase;

[0025] (3) slowly adding the water phase to the oil phase while rapidly stirring and emulsifying to obtain a water-in-oil emulsion;

[0026] (4) adding a cross-linking monomer to the water-in-oil emulsion according to a ratio, introducing nitrogen to deoxygenate, adding an initiator and a reducing agent, reacting at 60° C.-70° C. for 3-5 hours, and after the reaction is completed, adding a reverse emulsifier, stirring rapidly, to obtain a seawater-resistant and salt-resistant emulsion fluid loss reducer for cementing.

[0027] In the preparation method of the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing, the alkali is sodium hydroxide, calcium hydroxide or potassium hydroxide; the solvent oil is one or more of No. 3 white oil, No. 5 white oil, paraffin oil, aviation kerosene, and cyclohexane.

[0028] In the preparation method of the seawater and salt-resistant emulsion fluid loss reducer for cementing, the composite emulsifier is one or more of the Span series, Tween series and AEO series; and the reverse emulsifier is Tween 60 or Tween 80.

[0029] In the preparation method of the above-mentioned seawater-resistant and salt-resistant emulsion fluid loss reducer for cementing, the initiator is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azobisisobutylamidine hydrochloride, and azobisisopropylimidazoline hydrochloride; the reducing agent is one or more of triethylenetetramine, tetraethylenepentamine, sodium bisulfite, sodium pyrosulfite, and sodium sulfite.

[0030] In the preparation method of the seawater and salt-resistant emulsion fluid loss reducing agent for well cementing, the added amount of the initiator and the reducing agent is 0.05%-0.1% of the total amount of various monomers.

[0031] In another aspect, the present invention also provides the use of the above-mentioned seawater and salt-resistant emulsion fluid loss reducer for cementing in the preparation of cement slurry.

[0032] In the above application, the cement slurry is freshwater cement slurry, seawater cement slurry or saturated salt water cement slurry.

[0033] In the above application, the temperature of the cement slurry is 30-210°C.

[0034] The technical solution of the present invention has the following beneficial effects:

[0035] (1) The seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention has low viscosity, which is 90% lower than the viscosity of the solution polymerization fluid loss reducer in the prior art, has good fluidity, and is suitable for LAS (liquid automatic addition) system;

[0036] (2) The solid content of the seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention can reach 35%, which is nearly doubled compared with the effective concentration of the prior art, and the cost and efficiency of production, transportation, storage and use are greatly improved;

[0037] (3) The seawater-resistant and salt-resistant emulsion fluid loss reducer for cementing of the present invention has good universal application, and has the "three-resistance characteristics" of "resistance to ultra-high temperature, seawater and salt", and can be used in fresh water, seawater and saturated salt water cement slurries from low temperature to ultra-high temperature (30-210°C), and has excellent water loss control performance;

[0038] (4) The preparation method of the anti-seawater and anti-salt emulsion fluid loss reducing agent for cementing of the present invention introduces a composite emulsifier and a multiple emulsification process, and then adds a reverse emulsifier for emulsification after the reaction. The appropriate emulsion system and sufficient emulsification time ensure that the emulsion is fully emulsified. The process is simple, easy to operate, and the product has good stability. It does not delaminate or demulsify when placed at room temperature for 40 months, and does not demulsify when placed in a 50°C oven for 3 months;

[0039] (5) The "parallel reactor" process is used in the preparation of the large sample of the anti-seawater and anti-salt emulsion fluid loss agent for cementing of the present invention. The water phase and the oil phase are separately prepared in a large-capacity (5-10 cubic meters) mixing kettle, connected by an emulsifying pump, mixed and stirred evenly, and finally pumped into a multi-connected small-capacity (0.5-1 cubic meter) reactor through an emulsifying pump. A large amount of ingredients are prepared at one time to improve efficiency; emulsification is carried out synchronously in the parallel reactor through the emulsifying pump, which is more efficient; initiators are added to each reactor simultaneously and reacted, and a small amount of initiator dissolves faster, and the reaction heat release is small and easy to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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.

[0041] Figure 1 This is the infrared spectrum of the seawater and salt-resistant emulsion fluid loss reducer for cementing, 3315cm -1 is the stretching vibration peak of -NH2, 2977cm -1 、2931cm -1 It is the characteristic absorption peak of -CH3 and -CH2, 1646cm -1 The position is the characteristic absorption peak of the amide group, 1456 cm -1 and 1366cm -1 It is the symmetrical bending vibration peak of -CH3, 1387cm -1 It is the absorption peak of -CH2 in long-chain monomer, 1177cm -1 and 1039cm -1 The positions are respectively the symmetric and asymmetric stretching vibration peaks of -SO3. The characteristic peaks of all monomers can be seen from the infrared spectrum, and the peaks are between 1600-1640cm -1 There is no characteristic peak of C=C double bond, indicating that the monomer polymerization is sufficient and complete.

[0042] Figure 2 This is the thermogravimetric curve of the anti-seawater and anti-salt emulsion fluid loss agent for cementing. Below 100°C, the mass loss of the fluid loss agent is mainly due to the volatilization of free water or bound water inside its molecules, resulting in a 3.63% thermal weight loss platform. Below 306°C, the various groups in the fluid loss agent are not decomposed, indicating that the prepared fluid loss agent has good thermal stability.

[0043] Figure 3 These are pictures of the seawater and salt-resistant emulsion fluid loss reducer for cementing placed at room temperature for 40 months and in a 50°C oven for 3 months. From the pictures, we can see that the sample is stable without stratification or demulsification.

[0044] Figure 4 This is a schematic diagram of the preparation process of large-scale samples of seawater and salt-resistant emulsion fluid loss reducers for cementing. DETAILED DESCRIPTION

[0045] 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.

[0046] The terms "the", "said", "one" and "an" used in the present invention do not indicate a limitation of quantity, but indicate the presence of at least one of the objects mentioned. The terms "preferred", "more preferred" and the like refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. In addition, the description of one or more embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0047] When a numerical range is disclosed in the present invention, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed in the present invention should be understood to include any and all subranges included therein.

[0048] Specifically, the present invention provides a seawater and salt-resistant emulsion fluid loss reducer for cementing, which is copolymerized by sulfonic acid group-containing olefin monomers, amide group-containing olefin monomers, carboxyl group-containing monomers, long side chain functional monomers, and cross-linking monomers.

[0049] In the anti-seawater and anti-salt emulsion fluid loss reducing agent for well cementing of the present invention, sulfonic acid group-containing olefin monomers and carboxyl group-containing monomers are adsorption monomers, which can be well adsorbed on the surface of cement particles, and when the filtrate flows through the gaps between particles, it does not flow away; amide group-containing olefin monomers, long side chain functional monomers, and cross-linking monomers are hydration monomers, which can swell in water by binding water, play a role in reducing the void ratio between particles and dragging the flow, thereby reducing filtration loss.

[0050] The following is a detailed introduction of various monomers in the seawater and salt resistant emulsion fluid loss reducer for well cementing of the present invention.

[0051] Sulfonic acid group-containing vinyl monomers

[0052] In the present invention, the sulfonic acid olefin monomer acts as a skeleton monomer, and has a large side group that can improve the rigidity and temperature resistance of the polymer chain. It is used in the synthesis of seawater and salt-resistant emulsion fluid loss reducers for cementing to ensure the strong adsorption function of the polymer and reduce the water loss.

[0053] The sulfonic acid group-containing vinyl monomer of the present invention is one or more of styrene sulfonic acid, 2-acrylamido-2-methyl-1-propane sulfonic acid, 3-allyloxy-1-hydroxy-1-propane sulfonic acid sodium salt, and sodium methyl allyl sulfonate.

[0054] Preferably, in the anti-seawater and anti-salt emulsion fluid loss reducer for cementing of the present invention, the content of the sulfonic acid olefin monomer is 70-80 parts. When the content of the sulfonic acid olefin monomer is less than 70 parts, the prepared fluid loss reducer has poor water loss performance; when the content of the sulfonic acid olefin monomer is greater than 80 parts, the viscosity of the prepared fluid loss reducer is too large, and the basic properties of the cement slurry such as flowability and thickening performance are poor.

[0055] Further preferably, in the seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention, the content of the sulfonic acid olefin monomer is 73-78 parts.

[0056] Amide-containing vinyl monomers

[0057] In the present invention, the amide-based olefin monomer has high polymerization activity and good water solubility, and can also improve the high temperature and salt resistance of the product. The aggregation structure of the cement slurry system is controlled by hydration and adsorption, and is used in cementing cement slurry to improve the suspension performance of the cement slurry by increasing the liquid phase viscosity of the cement slurry.

[0058] Wherein, the amide-containing vinyl monomer is one or more of acrylamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylacrylamide, N-ethylacetamide, and N-benzylacrylamide.

[0059] Preferably, in the anti-seawater and anti-salt emulsion fluid loss reducer for cementing of the present invention, the content of the amide-containing olefin monomer is 10-20 parts. When the content of the amide-containing olefin monomer is less than 10 parts, the prepared fluid loss reducer has poor water loss performance; when the content of the amide-containing olefin monomer is greater than 20 parts, the prepared fluid loss reducer has too high viscosity, which affects the water loss performance of the product and the fluidity of the cement slurry.

[0060] Further preferably, in the seawater and salt resistant emulsion fluid loss reducer for cementing of the present invention, the content of the amide-containing olefin monomer is 12-18 parts.

[0061] Carboxyl-containing monomers

[0062] In the present invention, the role of the carboxyl monomer is to be adsorbed on the surface of cement particles or hydration products, and to reduce the water loss of cement slurry through adsorption.

[0063] Wherein, the carboxyl group-containing monomer is one or more of itaconic acid, fumaric acid, maleic anhydride, acrylic acid, and methacrylic acid.

[0064] Preferably, in the anti-seawater and anti-salt emulsion fluid loss reducer for cementing of the present invention, the content of the carboxyl-containing monomer is 0-5 parts. When the content of the carboxyl-containing monomer is greater than 5 parts, the polymerization reaction is affected, and the molecular weight of the obtained fluid loss reducer is low, and the water loss control ability is poor.

[0065] Further preferably, in the seawater and salt resistant emulsion fluid loss reducer for cementing of the present invention, the content of the carboxyl group-containing monomer is 1-4.5 parts.

[0066] Contains long side chain functional monomers

[0067] In the present invention, the role of the long side chain functional monomer is to increase the steric hindrance effect of the polymer molecular chain movement. At the same time, the polymer is adsorbed on the surface of cement particles, and the electrostatic repulsion of the long side chain can increase the distance between particles and reduce the contact probability between particles.

[0068] The long side chain functional monomer is one or more of octadecyl methacrylate, dodecyl methacrylate, dodecyl dimethyl allyl ammonium chloride, didodecyl methyl allyl ammonium chloride, and hexadecyl dimethyl allyl ammonium chloride.

[0069] Preferably, in the anti-seawater and anti-salt emulsion fluid loss reducer for cementing of the present invention, the content of the long side chain functional monomer is 1-10 parts. When the content of the long side chain functional monomer is too small, the fluid loss reducer does not have sufficient steric hindrance effect, and will cross-link with calcium and magnesium ions in seawater, resulting in bridging and bridging, leading to cement slurry thixotropy, thickening and other phenomena; when the content of the long side chain functional monomer is too large, the prepared fluid loss reducer has a low molecular weight and a poor water loss control effect.

[0070] Further preferably, in the seawater and salt resistant emulsion fluid loss reducer for cementing of the present invention, the content of the long side chain functional monomer is 2-9 parts.

[0071] Cross-linking monomer

[0072] In the present invention, the addition of cross-linked monomers can, on the one hand, provide a certain body structure for the fluid loss additive and enhance its ultra-high temperature resistance; on the other hand, it can increase the sphericity of the emulsion droplets and increase the flowability of the cement slurry when used in the cement slurry.

[0073] The cross-linking monomer is ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, divinylbenzene or N,N′-ethylbisacrylamide.

[0074] Preferably, in the seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention, the content of the cross-linking monomer is 0-3 parts. When the content of the cross-linking monomer is too high, the molecular weight of the prepared fluid loss reducer is too high, and the cement slurry flowability is poor.

[0075] Further preferably, in the seawater and salt resistant emulsion fluid loss reducer for cementing of the present invention, the content of the cross-linking monomer is 0.5-2.5 parts.

[0076] On the other hand, the present invention also provides a method for preparing the anti-seawater and anti-salt emulsion fluid loss reducer for well cementing, comprising: (1) adding sulfonic acid group-containing olefin monomers, carboxyl group-containing olefin monomers, amide group-containing olefin monomers, and long side chain functional monomers to deionized water containing alkali according to a ratio to obtain an aqueous phase; (2) adding a composite emulsifier to solvent oil while stirring to obtain an oil phase; (3) slowly adding the aqueous phase to the oil phase while rapidly stirring and emulsifying to obtain an oil-in-water emulsion; (4) adding a cross-linking monomer to the oil-in-water emulsion according to a ratio, introducing nitrogen to deoxygenate, adding an initiator and a reducing agent, reacting at 60° C.-70° C. for 3-5 hours, and after the reaction is completed, adding an inverse emulsifier and rapidly stirring to obtain an anti-seawater and anti-salt emulsion fluid loss reducer for well cementing.

[0077] The invention introduces a composite emulsifier and a multiple emulsification process in the process of preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing, and then adds an inverting agent for emulsification after the reaction. A suitable emulsion system and sufficient emulsification time ensure that the emulsion is fully emulsified, and the process is simple, easy to operate, and has good product stability. The product does not delaminate or break when placed at room temperature for 40 months, and does not break when placed in a 50°C oven for 3 months.

[0078] In some preferred embodiments, the method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing of the present invention comprises:

[0079] (1) Water phase preparation

[0080] Add alkali to deionized water and start stirring. Add sulfonic acid group-containing olefin monomer, carboxyl group-containing olefin monomer, amide group-containing olefin monomer, and long side chain functional monomer according to the ratio to obtain an aqueous phase, and control the solution temperature not to exceed 40°C.

[0081] Preferably, the base is sodium hydroxide, calcium hydroxide or potassium hydroxide.

[0082] (2) Oil phase preparation

[0083] The composite emulsifier is added into the solvent oil with stirring to obtain an oil phase.

[0084] Preferably, the solvent oil is one or more of No. 3 white oil, No. 5 white oil, paraffin oil, aviation kerosene, and cyclohexane.

[0085] Preferably, the composite emulsifier is one or more of the Span series, Tween series and AEO series.

[0086] (3) Emulsification and polymerization

[0087] Slowly add the prepared water phase to the oil phase, and stir rapidly and emulsify for 15-30 minutes to obtain a water-in-oil emulsion. Transfer to a reaction flask, add a cross-linking monomer, introduce nitrogen to deoxygenate, add an initiator and a reducing agent, and react at 60℃-70℃ for 3-5 hours. After the reaction is completed, add an inverse emulsifier and stir rapidly for 15-30 minutes. You can get a water-in-oil emulsion fluid loss reducer.

[0088] Preferably, the reverse emulsifier is Tween 60 or Tween 80.

[0089] Preferably, the initiator is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azobisisobutylamidine hydrochloride, and azobisisopropylimidazoline hydrochloride.

[0090] Preferably, the reducing agent is one or more of triethylenetetramine, tetraethylenepentamine, sodium bisulfite, sodium pyrosulfite, and sodium sulfite.

[0091] Preferably, the added amount of the initiator and the reducing agent is 0.05%-0.1% of the total amount of each monomer.

[0092] The infrared spectrum of the seawater and salt-resistant emulsion fluid loss reducer for cementing prepared according to the method of the present invention is as follows: Figure 1 The characteristic peaks of all monomers can be seen from the infrared spectrum, and the peaks are between 1600-1640cm -1 There is no characteristic peak of C=C double bond at , indicating that the monomer polymerization is sufficient and complete. Figure 2 , Figure 2 It shows that the prepared fluid loss agent has good thermal stability. Figure 3 These are pictures of the seawater and salt-resistant emulsion fluid loss reducer for cementing placed at room temperature for 40 months and in a 50°C oven for 3 months. From the pictures, we can see that the sample is stable without stratification or demulsification.

[0093] Further, such as Figure 4 As shown, the present invention also provides a large-scale production process of seawater and salt-resistant emulsion fluid loss reducing agent for cementing.

[0094] (1) Preparation of aqueous phase: Add alkali to deionized water and start stirring. Add sulfonic acid group-containing olefin monomer, carboxyl group-containing olefin monomer, amide group-containing olefin monomer and long side chain functional monomer in sequence to obtain an aqueous phase. Control the solution temperature not to exceed 40°C.

[0095] (2) Oil phase preparation

[0096] Adding a composite emulsifier into the solvent oil with stirring to obtain an oil phase;

[0097] (3) Stirring and emulsification

[0098] Slowly add the prepared water phase to the oil phase and stir rapidly for 15-20 minutes to obtain a mixed solution. Use an emulsification pump to divert the mixed solution to each sub-reactor, continue emulsification for 30-50 minutes, and add the cross-linking monomer.

[0099] (4) Aggregation

[0100] Nitrogen is introduced to remove oxygen, and an initiator of a redox system is added, and the reaction is carried out at 60°C-70°C for 3-5 hours. After the reaction is completed, an inverse emulsifier is added and the mixture is rapidly stirred for 15-30 minutes. Then, a water-in-oil emulsion fluid loss reducer is obtained.

[0101] The present invention adopts the "coupling reactor" process in the preparation of the large sample of the anti-seawater and anti-salt emulsion fluid loss reducer for cementing, and the water phase and the oil phase are respectively in a large volume (5-10m 3 ) The ingredients in the mixing kettle are connected through an emulsification pump, mixed and stirred evenly, and finally pumped into a multi-connected small capacity (0.5-1m 3 ) reactor, a large amount of ingredients are added at one time to improve efficiency; in the coupled reactors, emulsification is carried out synchronously through emulsification pumps, which is more efficient; initiators are added to each reactor simultaneously and reacted, a small amount of initiator dissolves faster, the reaction heat release is small and easy to control.

[0102] It should be noted that the types of monomers used in the preparation method of the seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention, the ratio of various monomers, the beneficial effects, etc. are the same as those in the seawater and salt-resistant emulsion fluid loss reducer for cementing described above, and the present invention will not repeat them here.

[0103] In another aspect, the present invention also provides the use of the anti-seawater and anti-salt emulsion fluid loss reducer for cementing in the preparation of cement slurry.

[0104] Through practice, the seawater-resistant and salt-resistant emulsion fluid loss reducer for cementing of the present invention has good universal application, has the "three-resistance characteristics" of "resistance to ultra-high temperature, seawater and salt", can be used in fresh water, seawater and saturated salt water cement slurries from low temperature to ultra-high temperature (30-210°C), and has excellent water loss control performance.

[0105] Example

[0106] 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.

[0107] Embodiment 1:

[0108] A method for preparing a seawater and salt-resistant emulsion fluid loss reducing agent for cementing comprises the following steps:

[0109] (1) Preparation of aqueous phase: Weigh 12.5 g of sodium hydroxide, 55.6 g of AMPS, 14.8 g of N,N-dimethylacetamide, 1.5 g of itaconic acid, and 0.9 g of dimethylallyl hexadecyl ammonium chloride, and dissolve them in 50 g of deionized water to obtain an aqueous phase.

[0110] (2) Preparation of oil phase: Weigh 6.3 g of Span 80 and 0.63 g of fatty alcohol polyoxyethylene (10) ether, and dissolve them in 65 g of No. 3 white oil to obtain an oil phase.

[0111] (3) Emulsification and polymerization. The aqueous phase obtained in step (1) is slowly added to the oil phase, and stirred at 10000 r / min with a variable frequency high-speed stirrer for 20 min, and then emulsified with a high shear dispersing emulsifier homogenizer for 5 min to obtain an oil-in-water emulsion. Transfer to a three-necked flask, add 0.37 g of cross-linking monomer divinylbenzene, pass nitrogen for 20 min to deoxygenate, add 0.25 g of ammonium persulfate and 0.20 g of sodium bisulfite at 60°C, react for 4 h, add 3.5 g of reverse phase agent Tween 80, and stir at 10000 r / min with a variable frequency high-speed stirrer for 20 min to obtain an oil-in-water emulsion fluid loss reducer.

[0112] The prepared seawater and salt-resistant emulsion fluid loss reducer for cementing is a milky white liquid with a solid content of 35.2% and a Brookfield viscosity of 448 cP. It does not demulsify or stratify when placed at room temperature for 40 months and does not demulsify or stratify when placed in a 50°C oven for 3 months.

[0113] Embodiment 2:

[0114] A method for preparing a seawater and salt-resistant emulsion fluid loss reducing agent for cementing comprises the following steps:

[0115] (1) Preparation of aqueous phase: Weigh 8.1 g of sodium hydroxide, 58.8 g of AHPS, 12.6 g of N,N-dimethylformamide, 2 g of maleic anhydride, and 1.5 g of didodecyl methyl allyl ammonium chloride, and dissolve them in 64 g of deionized water to obtain an aqueous phase.

[0116] (2) Preparation of oil phase: Weigh 7.5 g of Span 60 and 0.75 g of fatty alcohol polyoxyethylene (7) ether, and dissolve them in 70 g of cyclohexane to obtain an oil phase.

[0117] (3) Emulsification and polymerization. The aqueous phase obtained in step (1) is slowly added to the oil phase, and stirred at 11000 r / min with a variable frequency high-speed stirrer for 20 min, and then emulsified with a high shear dispersing emulsifier homogenizer for 5 min to obtain an oil-in-water emulsion. Transfer to a three-necked flask, add 0.62 g of cross-linking monomer pentaerythritol triacrylate, pass nitrogen for 30 min to deoxygenate, add 0.20 g of sodium persulfate and 0.18 g of sodium pyrosulfite at 65°C, react for 6 h, add 3.9 g of reverse phase agent Tween 60, stir at 11000 r / min with a variable frequency high-speed stirrer for 20 min, and obtain an oil-in-water emulsion fluid loss reducer.

[0118] The prepared seawater and salt-resistant emulsion fluid loss reducer for cementing is a milky white liquid with a solid content of 35.8% and a Brookfield viscosity of 403 cP. It does not demulsify or stratify when placed at room temperature for 40 months and does not demulsify or stratify when placed in a 50°C oven for 3 months.

[0119] Embodiment 3:

[0120] A method for preparing a seawater and salt-resistant emulsion fluid loss reducing agent for cementing comprises the following steps:

[0121] (1) Preparation of aqueous phase: Weigh 20.8 g of calcium hydroxide, 115.6 g of AMPS, 20.8 g of N,N-dimethylacrylamide, 10.5 g of acrylic acid, and 1.5 g of dodecyldimethylallylammonium chloride, and dissolve them in 110 g of deionized water to obtain an aqueous phase.

[0122] (2) Preparation of oil phase: Weigh 12.6 g of Span 60 and 1.70 g of fatty alcohol polyoxyethylene (3) ether, and dissolve them in 120 g of liquid paraffin to obtain an oil phase.

[0123] (3) Emulsification and polymerization. The aqueous phase obtained in step (1) is slowly added to the oil phase, and stirred at 12000 r / min for 15 min with a variable frequency high-speed stirrer, and then emulsified for 5 min with a high shear dispersing emulsifier homogenizer to obtain an oil-in-water emulsion. Transfer to a three-necked flask, add 1.50 g of cross-linking monomer trimethylolpropane trimethacrylate, pass nitrogen for 15 min to deoxygenate, add 0.5 g of ammonium persulfate and 0.30 g of triethylenetetramine at 55°C, react for 5 h, add 8.4 g of reverse agent Tween 80, and stir at 12000 r / min for 15 min with a variable frequency high-speed stirrer to obtain an oil-in-water emulsion fluid loss reducer.

[0124] The prepared seawater and salt-resistant emulsion fluid loss reducer for cementing is a milky white liquid with a solid content of 35.1% and a Brookfield viscosity of 472 cP. It does not demulsify or stratify when placed at room temperature for 40 months and does not demulsify or stratify when placed in a 50°C oven for 3 months.

[0125] Embodiment 4:

[0126] A method for preparing a seawater and salt-resistant emulsion fluid loss reducing agent for cementing comprises the following steps:

[0127] (1) Preparation of aqueous phase: Weigh 10.3 g of sodium hydroxide, 62.9 g of sodium styrene sulfonate, 11.4 g of N-ethylacetamide, 2.2 g of maleic anhydride, and 3 g of hexadecyl dimethyl allyl ammonium chloride, and dissolve them in 75 g of deionized water to obtain an aqueous phase.

[0128] (2) Preparation of oil phase: Weigh 5.8 g of Span 80 and 1.70 g of fatty alcohol polyoxyethylene (9) ether, and dissolve them in 57 g of white oil to obtain an oil phase.

[0129] (3) Emulsification and polymerization. The aqueous phase obtained in step (1) is slowly added to the oil phase, and stirred at 12000r / min with a variable frequency high-speed stirrer for 20min, and then emulsified with a high shear dispersing emulsifier homogenizer for 5min to obtain an oil-in-water emulsion. Transfer to a three-necked flask, add 0.59g of cross-linking monomer ethylene glycol dimethacrylate, pass nitrogen for 15min to deoxygenate, add 1g of sodium persulfate and 0.5g of tetraethylene pentamine at 60°C, react for 4h, add 3.8g of reverse agent Tween 80, stir at 12000r / min with a variable frequency high-speed stirrer for 20min, and obtain an oil-in-water emulsion fluid loss reducer.

[0130] The prepared seawater and salt-resistant emulsion fluid loss reducer for cementing is a milky white liquid with a solid content of 35.5% and a Brookfield viscosity of 427 cP. It does not demulsify or stratify when placed at room temperature for 40 months and does not demulsify or stratify when placed in a 50°C oven for 3 months.

[0131] Embodiment 5:

[0132] A method for preparing a seawater and salt-resistant emulsion fluid loss reducing agent for cementing comprises the following steps:

[0133] (1) Preparation of aqueous phase: Weigh 10.3 g potassium hydroxide, 58.7 g sodium methyl allyl sulfonate, 12.7 g acrylamide, 2.2 g itaconic acid, and 2.5 g didodecyl methyl allyl ammonium chloride, and dissolve them in 60 g deionized water to obtain an aqueous phase.

[0134] (2) Preparation of oil phase: Weigh 6.4 g of Span 60 and 2.0 g of fatty alcohol polyoxyethylene (7) ether, and dissolve them in 57 g of white oil to obtain an oil phase.

[0135] (3) Emulsification and polymerization. The aqueous phase obtained in step (1) is slowly added to the oil phase, and stirred at 11000 r / min with a variable frequency high-speed stirrer for 20 min, and then emulsified with a high shear dispersing emulsifier homogenizer for 5 min to obtain an oil-in-water emulsion. Transfer to a three-necked flask, add 0.98 g of cross-linking monomer N, N′-ethylbisacrylamide, pass nitrogen for 15 min to deoxygenate, add 0.75 g of sodium persulfate and 0.35 g of tetraethylenepentamine at 60°C, react for 6 h, add 4.2 g of the reverse agent Tween 60, and stir at 12000 r / min with a variable frequency high-speed stirrer for 20 min to obtain an oil-in-water emulsion fluid loss reducer.

[0136] The prepared seawater and salt-resistant emulsion fluid loss reducer for cementing is a milky white liquid with a solid content of 35.3% and a Brookfield viscosity of 419 cP. It does not demulsify or stratify when placed at room temperature for 40 months and does not demulsify or stratify when placed in a 50°C oven for 3 months.

[0137] Comparative Example 1:

[0138] The commonly used fluid loss additive on the market has a solid content of 20% and a Brookfield viscosity of 9500cP.

[0139] Comparative Example 2:

[0140] Commonly used fluid loss additives on the market have a solid content of 13% and a Brookfield viscosity of 30,000 cP.

[0141] It can be seen from the Brookfield viscosity data that the seawater and salt-resistant emulsion fluid loss reducer for cementing of the present invention has good flowability and is convenient for on-site transportation, dosage and use. However, the fluid loss reducers of Comparative Examples 1 and 2 have low solid content and high viscosity, poor flowability and are not conducive to on-site pumping applications.

[0142] Application Experiment Example

[0143] The seawater and salt-resistant emulsion fluid loss reducer for cementing prepared in Example 3 above was prepared with a density of 1.90 g / cm 3 , fresh water, seawater and saturated brine cement slurries with a water-cement ratio of 0.44. Water loss, rheology, thickening, compressive strength, free liquid and other tests were all measured in accordance with the provisions of GBT 19139-2012 "Test Methods for Oil Well Cement".

[0144] Freshwater cement slurry formula:

[0145] Experimental Example 1-Experimental Example 4: G-grade Shandong cement + 2.5% fluid loss agent + 0.25% retarder C-R21L + 0.25% defoamer C-DF60L + 41.6% fresh water

[0146] Experimental Example 5: G-grade Shandong cement + 35% silica fume + 4% fluid loss reducer + 2% retarder C-R42L + 0.33% defoamer C-DF60L + 49.1% fresh water

[0147] Experimental Example 6: G-grade Shandong cement + 35% silica fume + 6% fluid loss reducer + 3% retarder C-R42L + 0.33% defoamer C-DF60L + 46.5% fresh water

[0148] Experimental Example 7: G-grade Shandong cement + 35% silica fume + 8% fluid loss reducer + 4% retarder C-R42L + 0.33% defoamer C-DF60L + 43.9% fresh water

[0149] Experimental Example 8: G-grade Shandong cement + 35% silica fume + 8% fluid loss agent + 8% fluid loss agent + 5% retarder C-R42L + 0.33% defoamer C-DF60L + 43.0% fresh water

[0150]

[0151]

[0152] As shown in Table 1, the prepared anti-seawater and anti-salt emulsion fluid loss agent for cementing has excellent water loss control performance when used in freshwater cement slurry, the cement slurry has good fluidity, no free liquid is generated, and the compressive strength of the cement stone meets the requirements of cementing construction. This shows that the prepared anti-seawater and anti-salt emulsion fluid loss agent for cementing has good performance in freshwater cement slurry from 30℃ to 210℃.

[0153] Seawater cement slurry formula:

[0154] Experimental Examples 9-12: G-grade Shandong cement + 2.5% fluid loss agent + 0.25% retarder C-R21L + 0.25% defoamer C-DF60L + 44.2% seawater

[0155] Experimental Example 13: G-grade Shandong cement + 35% silica fume + 4% fluid loss reducer + 2% retarder C-R42L + 0.33% defoamer C-DF60L + 52.3% seawater

[0156] Experimental Example 14: G-grade Shandong cement + 35% silica fume + 6% fluid loss reducer + 3% retarder C-R42L + 0.33% defoamer C-DF60L + 49.5% seawater

[0157] Experimental Example 15: G-grade Shandong cement + 35% silica fume + 8% fluid loss agent + 4% retarder C-R42L + 0.33% defoamer C-DF60L + 46.8% seawater

[0158] Experimental Example 16: G-grade Shandong cement + 35% silica fume + 8% fluid loss reducer + 5% retarder C-R42L + 0.33% defoamer C-DF60L + 45.8% seawater

[0159]

[0160] As shown in Table 2, the prepared anti-seawater and anti-salt emulsion fluid loss reducer for cementing still has excellent water loss control performance when used in seawater cement slurry. The water loss can be controlled within 40mL at 210℃. The cement slurry has good fluidity and no thickening thixotropy occurs. No free liquid is produced in the cement slurry, and the compressive strength of the cement stone meets the requirements of cementing construction. This shows that the prepared anti-seawater and anti-salt emulsion fluid loss reducer for cementing has good performance in seawater cement slurry from 30℃ to 210℃.

[0161] Water loss properties of saturated brine cement slurry

[0162] formula:

[0163] Experimental Example 17: G-grade Shandong cement + 3% fluid loss agent + 0.25% retarder C-R21L + 0.25% defoamer C-DF60L + 15.75% NaCl + 43.13% fresh water

[0164] Experimental Example 18: G-grade Shandong cement + 3% fluid loss agent + 0.25% retarder C-R21L + 0.25% defoamer C-DF60L + 15.8% NaCl + 43.13% fresh water

[0165] Experimental Example 19: G-grade Shandong cement + 35% silica fume + 5% fluid loss reducer + 2% retarder C-R42L + 0.33% defoamer C-DF60L + 18.4% NaCl + 50.7% fresh water

[0166] Experimental Example 20: G-grade Shandong cement + 35% silica fume + 6% fluid loss reducer + 3% retarder C-R42L + 0.33% defoamer C-DF60L + 17.8% NaCl + 48.9% fresh water

[0167]

[0168] It can be seen from Table 3 that the prepared fluid loss reducer also has a good water loss control effect in saturated brine, and the water loss can be controlled within 50 mL in 150°C saturated brine cement slurry.

[0169] The prepared fluid loss agent was compared with the fluid loss agent used in the market at 1.9 g / cm 3 Comparison of cement slurry properties.

[0170] freshwater:

[0171]

[0172] It can be seen from the above table that the use of fresh water to prepare cement slurry, compared with the fluid loss reducers currently used in the market, has better water loss control performance with less addition, and is more efficient in packaging, use and transportation.

[0173]

[0174] As can be seen from the table above, the use of seawater to prepare cement slurry has obvious water loss control performance and rheological properties when the amount of fluid loss reducer is less than that of the fluid loss reducer on the market. Comparative Examples 1 and 2 have large water loss and high rheological readings, poor slurry fluidity, and poor compatibility with seawater.

[0175] Saturated salt water comparison:

[0176]

[0177] As can be seen from the above table, the use of saturated brine to prepare cement slurry has obvious water loss control performance when compared with the water loss reducer on the market with less addition. The water loss of Comparative Example 1 and Comparative Example 2 is uncontrollable and has poor compatibility with brine. The present invention has been disclosed above in terms of 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 construed 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 shall be based on the scope defined in the claims.

Claims

1. A seawater and salt-resistant emulsion fluid loss reducer for cementing, characterized in that: It is copolymerized by sulfonic acid group-containing olefin monomers, amide group-containing olefin monomers, carboxyl group-containing monomers, long side chain functional monomers and cross-linking monomers.

2. The seawater and salt-resistant emulsion fluid loss reducer for cementing according to claim 1, characterized in that: In terms of weight, the sulfonic acid group-containing vinyl monomer is 70-80 parts; the amide group-containing vinyl monomer is 10-20 parts; the carboxyl group-containing monomer is 0-5 parts; the long side chain functional monomer is 1-10 parts; and the cross-linking monomer is 0-3 parts.

3. The seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: In terms of weight, the sulfonic acid group-containing vinyl monomer is 73-78 parts; the amide group-containing vinyl monomer is 12-18 parts; the carboxyl group-containing monomer is 1-4.5 parts; the long side chain functional monomer is 2-9 parts; and the cross-linking monomer is 0.5-2.5 parts.

4. The seawater and salt resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: The sulfonic acid group-containing vinyl monomer is one or more of styrene sulfonic acid, 2-acrylamido-2-methyl-1-propane sulfonic acid, 3-allyloxy-1-hydroxy-1-propane sulfonic acid sodium salt, and sodium methyl allyl sulfonate.

5. The seawater and salt resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: The amide-containing vinyl monomer is one or more of acrylamide, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylacrylamide, N-ethylacetamide, and N-benzylacrylamide.

6. The seawater and salt resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: The carboxyl group-containing monomer is one or more of itaconic acid, fumaric acid, maleic anhydride, acrylic acid, and methacrylic acid.

7. The seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: The long side chain functional monomer is one or more of octadecyl methacrylate, dodecyl methacrylate, dodecyl dimethyl allyl ammonium chloride, didodecyl methyl allyl ammonium chloride, and hexadecyl dimethyl allyl ammonium chloride.

8. The seawater and salt resistant emulsion fluid loss reducing agent for cementing according to claim 1, characterized in that: The cross-linking monomer is ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, divinylbenzene or N,N'-ethylbisacrylamide.

9. The method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to any one of claims 1 to 8, characterized in that: include: (1) adding a sulfonic acid group-containing vinyl monomer, a carboxyl group-containing vinyl monomer, an amide group-containing vinyl monomer, and a long side chain functional monomer to deionized water containing an alkali according to a ratio to obtain an aqueous phase; (2) adding a composite emulsifier to the solvent oil with stirring to obtain an oil phase; (3) slowly adding the water phase to the oil phase while rapidly stirring and emulsifying to obtain a water-in-oil emulsion; (4) adding a cross-linking monomer to the water-in-oil emulsion according to a ratio, introducing nitrogen to deoxygenate, adding an initiator and a reducing agent, reacting at 60° C.-70° C. for 3-5 hours, and after the reaction is completed, adding a reverse emulsifier, stirring rapidly, to obtain a seawater-resistant and salt-resistant emulsion fluid loss reducer for cementing.

10. The method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 9, characterized in that: The alkali is sodium hydroxide, calcium hydroxide or potassium hydroxide; the solvent oil is one or more of No. 3 white oil, No. 5 white oil, paraffin oil, aviation kerosene and cyclohexane.

11. The method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 9, characterized in that: The composite emulsifier is one or more of the Span series, Tween series and AEO series; the reverse emulsifier is Tween 60 or Tween 80.

12. The method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 9, characterized in that: The initiator is one or more of ammonium persulfate, sodium persulfate, potassium persulfate, azobisisobutylamidine hydrochloride, and azobisisopropylimidazoline hydrochloride; the reducing agent is one or more of triethylenetetramine, tetraethylenepentamine, sodium bisulfite, sodium pyrosulfite, and sodium sulfite.

13. The method for preparing the seawater and salt-resistant emulsion fluid loss reducing agent for cementing according to claim 9, wherein the added amount of the initiator and the reducing agent is 0.05%-0.1% of the total amount of various monomers.

14. Use of the seawater and salt-resistant emulsion fluid loss reducer for cementing according to any one of claims 1 to 8 in preparing cement slurry.

15. The use according to claim 14, characterized in that: The cement slurry is freshwater cement slurry, seawater cement slurry or saturated salt water cement slurry.

16. The use according to claim 14, characterized in that The temperature of the cement slurry is 30-210°C.

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