A heavy oil viscosity-reducing displacement agent, a preparation method and application thereof

Abstract

The application discloses a thickened oil viscosity-reducing displacement agent, which is prepared by dissolving N,N dimethyl acrylamide, N-mono-substituted alkenyl amide and unsaturated alkyl polyoxyethylene ether in a solvent and then performing a free radical copolymerization reaction. The viscosity-reducing displacement agent has the effects of water phase viscosity increase and thickened oil emulsification viscosity reduction. The water phase viscosity increase can reduce the water / oil flow ratio, inhibit water channeling and expand the displacement fluid sweep area; the emulsification viscosity reduction can improve the mobility of thickened oil, reduce the displacement resistance, and realize the purpose of improving the heavy oil recovery ratio under the multiple effects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of heavy oil recovery, and particularly relates to a heavy oil viscosity-reducing displacement agent and a preparation method and application thereof. BACKGROUND

[0002] The global heavy oil reserves are very considerable, and the currently detected recoverable reserves of heavy oil account for more than 70% of the total crude oil reserves. In addition to Canada and Venezuela, China is also a country mainly exploiting heavy oil reservoirs. Due to the characteristics of high viscosity and high density of heavy oil, the flowability is very poor, and the difficulty and cost of exploitation and transportation of heavy oil are much higher than those of light oil. Reducing the viscosity of heavy oil and improving its flowability is an effective means to improve the recovery rate of heavy oil. Due to the rapid decrease of market oil price and the utilization rate of steam in steam exploitation of oil reservoirs, water flooding of heavy oil has become an important technical means for heavy oil recovery. Due to the high viscosity of heavy oil, the water flooding resistance is large, and once the water flow channel is formed by the displacement liquid breaking through the oil phase front, the subsequent displacement liquid directly flows to the oil well from the water flow channel with small resistance, and the remaining heavy oil will be difficult to be recovered. Therefore, in addition to the emulsification and viscosity reduction effect, the heavy oil displacement agent should also have the water phase viscosity increasing property, improve the water oil mobility ratio, and increase the displacement liquid sweep area.

[0003] CN107365574A proposes a viscosity-reducing displacement system for ordinary heavy oil reservoirs, which is composed of small molecule surfactants and polyacrylamide, and has the effects of reducing the water oil mobility ratio and reducing the oil water interfacial tension.

[0004] CN107365575A discloses a viscosity-reducing displacement agent composed of nonionic / anionic surfactants, ester compounds, wetting agents and water, which is used in combination with polyacrylamide, can improve the water oil mobility ratio, and increase the heavy oil recovery rate in Shengli oilfield by more than 17.6%.

[0005] The viscosity-reducing displacement agents disclosed in the above patents are all composed of small molecule surfactant systems and polymers to form a composite displacement system, so as to achieve the effects of emulsification, viscosity reduction and displacement liquid viscosity increase. In actual use, each composition will be separated by chromatography in the reservoir flow, resulting in a large amount of reagent and poor deep displacement effect.

[0006] CN107383273 A invents an active polymer for heavy oil recovery, which has the effects of increasing the viscosity of water phase and reducing the viscosity of heavy oil, and can increase the recovery rate by 10-20% when the concentration is 400-3000 mg / L.

[0007] CN110041462A invents an amphiphilic high molecular heavy oil viscosity reducer, which can reduce the viscosity of 1000-10000 mPa.s heavy oil by more than 98% at a concentration of 200 ppm.

[0008] CN108546315A adopts acrylamide, alkali metal salt of acrylic acid, dimethyl diallyl ammonium chloride, methacryloyloxyethyl dimethyl dodecyl ammonium bromide and two amphiphilic dendritic unsaturated monomers to prepare an amphiphilic polymer oil displacement agent, which has the functions of reducing viscosity and increasing viscosity of water phase.

[0009] Li Juan 1 et al. (Research and application of water-soluble amphiphilic polymer in oilfield development. Oilfield Chemistry 2011, 28(02), 229-235) uses N,N dimethyl acrylamide, acrylamide and N-vinyl pyrrolidone (NVP) monomers to synthesize a viscosity reducing system in an organic solvent. The organic solvent used in the synthesis is volatile and toxic, and further separation of the organic solvent is required after synthesis, which is complex.

[0010] In general, the viscosity-reducing displacement agent with viscosity reduction and mobility improvement functions is not mature, has a single type, a complex preparation process, high cost, and a small application range, and is often limited to single oil well application. New multifunctional viscosity-reducing displacement agents need to be further developed to expand the application range. SUMMARY

[0011] In view of the high difficulty in heavy oil exploitation, the small number of existing viscosity-reducing displacement agents, and the narrow application range, the present application provides a viscosity-reducing displacement agent. The viscosity-reducing displacement agent has hydrophilic and lipophilic properties, can reduce the oil-water interfacial tension, and promote emulsification and viscosity reduction of heavy oil. On the other hand, the viscosity-reducing displacement agent for heavy oil has a mobility improvement function, has a certain viscosity after being dissolved in water, increases the viscosity of the displacement fluid, improves the water-oil mobility ratio, and improves the sweep area of the displacement fluid, thereby improving the heavy oil recovery efficiency based on water flooding.

[0012] The present application also provides a preparation method of the viscosity-reducing displacement agent, which can be carried out at room temperature in an aqueous solution and is simple and easy to implement.

[0013] The present application provides a method for applying the viscosity-reducing displacement agent.

[0014] In order to achieve the above object, the present application provides a viscosity-reducing displacement agent for heavy oil, which contains a polymer having the following structure:

[0015]

[0016] wherein a, b and c are the mass percentages of each structural unit in the polymer, preferably a is 70% to 85%, preferably 75% to 80%, b is 0.5% to 5%, preferably 1% to 3%, and c is 12% to 28%, preferably 18% to 25%;

[0017] wherein R1 is H or C1-C3 alkyl, preferably H;

[0018] R2 is a C1-C8 alkyl, hydroxyalkyl, acyl, aryl, preferably a C1-C4 alkyl, hydroxyalkyl, acyl and phenyl or substituted phenyl, such as methyl, ethyl, propyl, hydroxymethyl, phenyl, hydroxyphenyl, benzyl, acetyl, propionyl, and the like;

[0019] R3 is H, methyl or ethyl;

[0020] R4 is a C8-C14 alkyl, preferably a C10-C12 linear alkyl;

[0021] X is -COONa or H;

[0022] n is an integer of 6-16, preferably an integer of 8-12.

[0023] The weight average molecular weight of the polymer can be 1.5 x 10 5 - 5 x 10 5 , preferably 2.5 x 10 5 - 4 x 10 5 , and the weight average molecular weight can be adjusted according to the actual application by those skilled in the art.

[0024] The application also provides a preparation method of a heavy oil viscosity reduction displacement agent, the method comprising:

[0025] The monomers N,N dimethyl acrylamide, N-mono-substituted alkenyl amide and unsaturated alkyl polyoxyethylene ether are added to water as a solvent, an initiator is added, and the reaction is stirred to obtain a polymerization product.

[0026] Specifically, the following steps can be taken:

[0027] A three-necked reaction bottle equipped with a reflux condenser and a stirrer is added with distilled water as a solvent, and the monomers N,N dimethyl acrylamide, N-mono-substituted alkenyl amide and unsaturated alkyl polyoxyethylene ether are added in a certain mass ratio. After being dissolved by stirring, the mixed solution is heated to a reaction temperature in an inert atmosphere, a certain amount of initiator is added, and the reaction is continuously stirred for 2-20 hours. After the reaction is completed, an excess of ethanol is added to the obtained product to obtain a precipitated product. The product is filtered and freeze-dried to obtain a polymerization product.

[0028] According to the method of the application, the monomer N-mono-substituted alkenyl amide has the following structure:

[0029]

[0030] R1 is H or a C1-C3 alkyl, preferably H;

[0031] Wherein, R2 is a C1 to C8 alkyl, hydroxyalkyl, acyl, or aryl group, preferably a C1 to C4 alkyl, hydroxyalkyl, acyl group, or phenyl or substituted phenyl group, such as methyl, ethyl, propyl, hydroxymethyl, phenyl, hydroxyphenyl, benzyl, acetyl, propionyl, etc.

[0032] Where X is -COONa or H.

[0033] Preferably, the N-monosubstituted alkenyl amide is N-acetylacrylamide, N-methylacrylamide, N-hydroxymethylacrylamide, N-phenylacrylamide, or N-propylacrylamide.

[0034] According to the method of the present invention, the molecular structure of the monomeric unsaturated alkyl polyoxyethylene ether is as shown in the following formula:

[0035]

[0036] Wherein, R3 is H, methyl, or ethyl;

[0037] Wherein, R4 is a C8 to C14 alkyl group, preferably a C10 to C12 straight-chain alkyl group;

[0038] Where n is an integer from 6 to 16, preferably an integer from 8 to 12;

[0039] According to the method of the present invention, the reactant monomer accounts for 5% to 30% of the total mass fraction of the solvent, preferably 10% to 20%.

[0040] Preferably, the mass ratio of the reactive monomers N,N-dimethylacrylamide, N-monosubstituted alkenylamide, and unsaturated alkyl polyoxyethylene ether is 70%–85%: 0.5%–5%: 12%–28%, more preferably 75%–80%: 1%–3%: 18%–25%.

[0041] According to the method of the present invention, the initiator is a mixture of persulfate and sulfite; preferably, the mass ratio of persulfate to sulfite is 1:4 to 5:1, more preferably 1:2 to 3:1. The persulfate is one or a combination of two or more of ammonium persulfate, potassium persulfate, and sodium persulfate, and the sulfite is one or a combination of two or more of sodium bisulfite, sodium sulfite, potassium bisulfite, potassium sulfite, ammonium sulfite, and ammonium bisulfite.

[0042] According to the method of the present invention, the initiator mass concentration is 0.1 to 1.0 wt% of the total monomer concentration, preferably 0.2 to 0.7 wt%.

[0043] According to the method of the present invention, the reaction temperature is 10-60°C, preferably 20-45°C; the reaction time is 2-20 hours, preferably 4-12 hours.

[0044] The application further provides a method for applying the heavy oil viscosity-reducing displacement agent, comprising: diluting the heavy oil viscosity-reducing displacement agent with water to a concentration of 0.01wt%-0.5wt% and injecting the heavy oil-containing formation at 10-90 DEG C.

[0045] The heavy oil has a viscosity in the range of 100-10000 mPa s.

[0046] The water used is field water of the target oil reservoir, and the salinity is less than or equal to 50000 mg / L.

[0047] Compared with the prior art, the application has the following advantages:

[0048] The viscosity-reducing displacement agent is an active polymer, and the molecular structure contains active hydrophilic groups such as sulfonic acid groups, amine groups, carbonyl groups and polyoxyethylene ether groups, and has good water solubility, so that the polymer-type viscosity-reducing displacement agent has high interfacial activity and water-phase viscosity-increasing performance. Compared with the traditional displacement system, the product of the application can not only quickly reduce the viscosity of heavy oil during use, but also increase the viscosity of the displacement liquid during use, can inhibit the fingering of the displacement liquid, increase the swept area of the displacement liquid in the oil reservoir, has the multiple effects of profile adjustment and improvement of the swept coefficient of the displacement liquid, and finally realizes the purpose of heavy oil viscosity reduction and yield increase. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 The micrograph (100 times) of the heavy oil viscosity-reducing displacement agent described in Example 4 after emulsification of Shengli heavy oil.

[0050] Figure 2 The micrograph (100 times) of the heavy oil viscosity-reducing displacement agent described in Example 4 after emulsification of Henan heavy oil.

[0051] Figure 3 The infrared spectrum of the viscosity-reducing displacement agent described in Example 4. DETAILED DESCRIPTION

[0052] In order to facilitate the understanding of the application, the application is illustrated by the following examples. It should be understood by those skilled in the art that the examples are only used to facilitate the understanding of the application and should not be regarded as a specific limitation on the application.

[0053] In the following examples, the instruments, reagents, materials and the like, if not specifically stated, are all conventional instruments, reagents, materials and the like in the prior art; they can be purchased through regular commercial channels;

[0054] In the examples, the experimental methods, detection methods and the like involved, if not specifically stated, are all conventional experimental methods, detection methods and the like.

[0055] Examples 1-5 illustrate the preparation of the displacement system provided in the present application.

[0056] Example 1

[0057] This example is used to illustrate the preparation method of the heavy oil viscosity-reducing displacement agent provided in the present application. It comprises the following steps:

[0058] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.10 g of N,N-dimethylacrylamide, 1.82 g of methallyl polyoxyethylene ether, and 0.08 g of acetylacrylamide were added as monomers. After stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system. The temperature was kept at 25°C in a constant-temperature water bath, and 0.016 g of potassium persulfate and 0.008 g of sodium bisulfite were added. The stirring was continued for 8 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product.

[0059] The molecular structure of the methallyl polyoxyethylene ether used in the preparation process is shown in the following formula:

[0060]

[0061] The structure of the monomer N-acetylacrylamide used in the preparation process is shown in the following formula:

[0062]

[0063] Example 2

[0064] This example is used to illustrate the preparation method of the heavy oil viscosity-reducing displacement agent provided in the present application. It comprises the following steps:

[0065] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.10 g of N,N-dimethylacrylamide, 1.82 g of methallyl polyoxyethylene ether, and 0.08 g of acetylacrylamide were added as monomers. After stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system. The temperature was kept at 25°C in a constant-temperature water bath, and 0.016 g of potassium persulfate and 0.008 g of sodium bisulfite were added. The stirring was continued for 8 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product.

[0066] The molecular structure of the methallyl polyoxyethylene ether used in the preparation process is shown in the following formula:

[0067]

[0068] The structure of the monomer N-acetylacrylamide used in the preparation process is shown in the following formula:

[0069]

[0070] Example 3

[0071] This example is used to illustrate the preparation method of the heavy oil viscosity reduction displacement agent provided by the present application. It comprises the following steps:

[0072] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.40 g of N,N-dimethyl acrylamide, 1.52 g of allyl polyoxyethylene ether, and 0.08 g of N-hydroxymethyl acrylamide were added as monomers. After stirring and dissolving, nitrogen was introduced into the mixed solution for 1 h to remove oxygen in the reaction system. The temperature was kept at 35°C in a constant temperature water bath, and 0.020 g of sodium persulfate and 0.010 g of sodium bisulfite were added. The stirring was continued for 4 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product.

[0073] The molecular structure of the allyl polyoxyethylene ether used in the preparation process is shown in the following formula:

[0074]

[0075] The monomer N-hydroxymethyl acrylamide used in the preparation process has the following structural formula:

[0076]

[0077] Example 4

[0078] This example is used to illustrate the preparation method of the heavy oil viscosity reduction displacement agent provided by the present application. It comprises the following steps:

[0079] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.40 g of N,N-dimethyl acrylamide, 1.52 g of allyl polyoxyethylene ether, and 0.08 g of N-hydroxymethyl acrylamide were added as monomers. After stirring and dissolving, nitrogen was introduced into the mixed solution for 1 h to remove oxygen in the reaction system. The temperature was kept at 35°C in a constant temperature water bath, and 0.020 g of sodium persulfate and 0.010 g of sodium bisulfite were added. The stirring was continued for 4 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product.

[0080] The molecular structure of the allyl polyoxyethylene ether used in the preparation process is shown in the following formula:

[0081]

[0082] The monomer N-phenylpropenamide used in the preparation process has the following formula:

[0083]

[0084] Example 5

[0085] This example is used to illustrate the preparation method of the heavy oil viscosity reduction displacement agent provided by the present application. It comprises the following steps:

[0086] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.2 g of N,N-dimethylacrylamide, 1.6 g of methyl allyl polyoxyethylene ether, and 0.2 g of N-propylacrylamide were added in a certain mass ratio. After stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system. In a constant temperature water bath maintained at 30°C, 0.024 g of potassium persulfate and 0.010 g of sodium bisulfite were added, and the stirring reaction was continued for 6 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product.

[0087] The molecular structure of the methyl allyl polyoxyethylene ether used in the preparation process is as follows:

[0088]

[0089] The monomer N-propylacrylamide used in the preparation process has the following formula:

[0090]

[0091] Comparative Example 1

[0092] In a three-necked reaction flask equipped with a reflux condenser and a stirrer, 42 g of distilled water was added as a solvent, and 6.2 g of N,N-dimethylacrylamide, 0.20 g of N-phenylacrylamide monomer were added in a certain mass ratio. After stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system. In a constant temperature water bath maintained at 30°C, 0.037 g of potassium persulfate and 0.018 g of potassium hydrogen sulfite were added, and the stirring reaction was continued for 8 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product. The product was filtered and freeze-dried to obtain a polymerization product D1.

[0093] Comparative Example 2

[0094] In a three-necked flask equipped with reflux condenser and stirrer, 42 g of distilled water was added as solvent, 6.2 g of N, N-dimethyl acrylamide and 1.6 g of methallyl polyoxyethylene ether monomer were added in a certain mass ratio, after stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system, 0.037 g of potassium persulfate and 0.018 g of potassium bisulfite were added in a constant temperature water bath at 30℃, and the stirring reaction was continued for 8 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product, and the product was filtered and freeze-dried to obtain a polymerization product D2.

[0095] The molecular structure of the methallyl polyoxyethylene ether used in the preparation process is as follows:

[0096]

[0097] Comparative Example 3

[0098] In a three-necked flask equipped with reflux condenser and stirrer, 42 g of distilled water was added as solvent, 6.2 g of N, N-dimethyl acrylamide and 1.6 g of methallyl polyoxyethylene ether monomer were added in a certain mass ratio, after stirring and dissolving, 1 h of nitrogen was introduced into the mixed solution to remove oxygen in the reaction system, 0.037 g of potassium persulfate and 0.018 g of potassium bisulfite were added in a constant temperature water bath at 30℃, and the stirring reaction was continued for 8 h. After the reaction was completed, excess ethanol was added to the obtained product to obtain a precipitated product, and the product was filtered and freeze-dried to obtain a polymerization product D2.

[0099] The molecular structure of the methallyl polyoxyethylene ether used in the preparation process is as follows:

[0100]

[0101] The monomer N-phenyl acrylamide used in the preparation process has the following formula:

[0102]

[0103] Comparative Example 4

[0104] A commercially available sodium dodecyl benzene sulfonate surfactant and polyacrylamide (molecular weight of 8 million to 20 million) were selected as comparative reagents (both reagents were purchased from Ino Kai Co., Ltd.), and the above surfactant and polyacrylamide were prepared into a surfactant-polymer aqueous solution D4 in a mass ratio of 1:1 with an appropriate amount of water.

[0105] Examples 6-8 are used to illustrate the performance test of the heavy oil viscosity reduction displacement agent provided in the present application.

[0106] The water used in Examples 6-8 is a certain oil field site mineralized water in Henan and a certain oil field mineralized water in Shengli oil field, respectively. The mineralization degree of the oil field site in Henan is 7609 mg / L, and the mineralization degree of the oil field site in Shengli is 23583 mg / L.

[0107] The oil used in Examples 6-8 is a certain block heavy oil sample in Henan oil field (50℃ surface degassing viscosity is 6320 mPa·s, and water content is 12.3%) and a certain block heavy oil sample in Shengli oil field (50℃ surface degassing viscosity is 1943 mPa·s, and water content is 3.5%).

[0108] Example 6

[0109] This example is used to illustrate the process of testing the viscosity reduction performance of the displacement system provided by the application.

[0110] (1) The certain heavy oil in Shengli and the certain heavy oil in Henan were respectively kept at 50℃ in a water bath for 30 min.

[0111] (2) In the viscosity reduction experiment, the products A1-A5 of Examples 1-5 and the products of Comparative Examples D1-D4 were diluted to a displacement system with a mass fraction of 0.1wt%, and the displacement system was mixed with the heavy oil sample at a mass ratio of 5:5, then slowly stirred at 50℃ for 10 min, and the viscosity of the emulsion was tested by HAKKE MARS III. The results are shown in Table 1.

[0112] Table 1 Viscosity reduction results of displacement system

[0113]

[0114]

[0115] Example 7

[0116] This example is used to illustrate the process of evaluating the viscosity increasing ability of the displacement system of the application to the water phase.

[0117] The products A1-A5 of Examples 1-5 and the products of Comparative Examples D1-D4 were diluted to a displacement system with a mass fraction of 0.1wt%, and the viscosity of the water solution at 50℃ was tested by HAKKE MARS III rheometer. The results are shown in Table 2.

[0118] Table 2 shows that the oil displacement system solution has the effect of increasing the viscosity of the water phase, can improve the water oil mobility ratio, adjust the profile, and improve the displacement liquid sweep area.

[0119] Table 2 Viscosity test results of solution

[0120]

[0121]

[0122] Example 8

[0123] This example is used to illustrate the process of displacement performance test of the displacement system in the present application.

[0124] (1) Dry the artificial core in the oven at 120°C to constant weight, and accurately measure the core size and gas permeability.

[0125] (2) After saturating the core with distilled water, measure the pore volume. Saturate the core with the dehydrated heavy oil of a certain block in Henan Oilfield, and record the saturated oil volume.

[0126] (3) Dilute the products A1-A5 of Examples 1-5 and the products of Comparative Examples D1-D4 to 0.1wt% of the displacement system.

[0127] (4) At 50°C, continuously inject the field water sample (salinity 7609mg / L) of a certain block in Henan Oilfield into the saturated oil core until the oil content in the effluent is <1%. Inject 0.5PV of the displacement fluid prepared from A1-A5 and Comparative Examples D1-D4, and then inject the field water for displacement until the oil content in the effluent is less than 1%, and calculate the recovery ratio of Henan heavy oil increased by the displacement fluid on the basis of water flooding.

[0128] (5) After saturating the core with distilled water, measure the pore volume. Saturate the core with the dehydrated heavy oil of a certain block in Shengli Oilfield, and record the saturated oil volume.

[0129] (6) At 50°C, continuously inject the field water sample (salinity 23583mg / L) of a certain block in Shengli Oilfield into the saturated oil core until the oil content in the effluent is <1%. Inject 0.5PV of the displacement fluid prepared from A1-A5 and Comparative Examples D1-D4, and then inject the field water for displacement until the oil content in the effluent is less than 1%, and calculate the recovery ratio of Shengli heavy oil increased by the displacement fluid on the basis of water flooding.

[0130] In the above process, the gas permeability of the core is measured by the permeability tester produced by Dongda Shiyi Company.

[0131] In the above process, the displacement test is evaluated by the simulation displacement evaluation device produced by Dongda Shiyi Company.

[0132] The results of the effect of increasing the recovery ratio of crude oil of the examples and comparative examples are shown in Table 3.

[0133] Table 3: Results of increasing the recovery ratio

[0134]

[0135] From table 3, the displacement system in the application can improve the recovery ratio of a certain heavy oil block in Henan oilfield by 15.9%~21.4% on the basis of water flooding, which is superior to the displacement effect of the comparative example.

[0136] The displacement system in the application can improve the recovery ratio of a certain heavy oil block in Shengli by 14.7%~18.7% on the basis of water flooding, which is superior to the displacement effect of the comparative example. Through viscosity reduction test, water phase viscosity increase and displacement test, the displacement system in the application has good viscosity reduction and water phase viscosity increase effect, can effectively improve the heavy oil recovery ratio of multiple oil wells, and can be used for heavy oil exploitation, especially after water flooding.

[0137] The applicant declares that the detailed process equipment and process flow of the application are illustrated by the above examples, but the application is not limited to the above detailed process equipment and process flow, that is, it does not mean that the application must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any improvement of the application, equivalent replacement of each raw material of the product of the application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the application.

[0138] Test example 9

[0139] The products obtained in the above preparation examples and preparation comparative examples were subjected to quantitative test, and the test results are shown in table 4.

[0140] Molecular weight test was carried out by gel permeation chromatography (GPC),

[0141] The mass ratio of structural units in the deaggregation polymer was calculated according to the material addition ratio.

[0142] Table 4

[0143]

[0144] Test example 10

[0145] The viscosity reducer A4 obtained in example 4 was subjected to infrared spectrum ((Germany Bruker MPA type) detection. The infrared spectrum characterization results are shown in Figure 3 The strong absorption peak of 3436 cm -1 in the infrared spectrum is the -NH absorption peak of amine group; the absorption peak near 2938 cm -1 is the methylene absorption peak, and the infrared absorption spectrum absorption peak at 1684 cm -1 is the carbonyl stretching absorption peak connected with N (amide). The strong absorption peak of 1457 cm -1 in the infrared spectrum is the benzene ring skeleton vibration, and the strong absorption peak of 685 cm -1 indicates that the branched benzene ring is a monosubstituted structure. The infrared absorption peak of 1129 cm -1The strong absorption peak at the absorption peak of C-O-C is 1008 cm -1 Further, the product has ethylene ether structure unit. 1037 cm -1 The strong absorption peak is C-N absorption peak. 784 cm -1 The absorption peak of 1720 cm-1 indicates that the synthetic sample contains And n>4. The above test results can prove that the interface modification viscosity reducer A4 prepared by the application has benzene ring, polyether and amide structure at the same time, indicating that the ternary copolymer product is successfully polymerized in the reaction.

Claims

1. A heavy oil viscosity-reducing displacement agent comprising a polymer having the following structure: wherein, a, b, c are the mass percentages of the respective structural units in the polymer, a is from 70% to 85%, b is from 1% to 3%, c is from 12% to 28%, R1is H or an alkyl group having from 1 to 3 carbon atoms, R2is an alkyl group having from 1 to 4 carbon atoms, a hydroxyalkyl group, an acyl group and a phenyl group or a substituted phenyl group, R3is H, methyl or ethyl, R4is an alkyl group having from 8 to 14 carbon atoms, X is -COONa or H, n is an integer from 6 to 16, the weight average molecular weight of the polymer is from 1.5 x 10 5 to 5 x 10 5 .

2. The viscosity-reducing displacing agent according to claim 1, wherein, a is 75% to 80%, and c is 18% to 25%.

3. The viscosity-reducing displacing agent according to claim 1, wherein, R4 is a linear alkyl group having 10 to 12 carbon atoms, and n is an integer of 8 to 12.

4. The viscosity-reducing displacing agent of claim 1, the polymer having a weight average molecular weight of 2 x 10 5 4 x 10 5 .

5. A process for the preparation of the heavy oil viscosity reducing displacement agent of any one of claims 1 to 4, said process comprising: The monomers N,N-dimethylacrylamide, N-mono-substituted alkenylamide, and unsaturated alkyl polyoxyethylene ether are added to water as a solvent, and an initiator is added, and the mixture is stirred and reacted at a temperature of 10 to 60°C to obtain the polymer.

6. The method of claim 5, wherein, The monomer N-mono-substituted alkenylamide has the following structure: wherein R1is H or C1-C3 alkyl, R2is C1-C4 alkyl, hydroxyalkyl, acyl, and phenyl or substituted phenyl, and X is -COONa or H.

7. The method of claim 6, wherein, R1 is H.

8. The method according to claim 5 or 6, wherein, The N-mono-substituted alkenylamide is selected from one or more of N-acetylpropenamide, N-methylacrylamide, N-hydroxymethylacrylamide, N-phenylacrylamide, and N-propylacrylamide.

9. The method of claim 5, wherein, The monomer unsaturated alkyl polyoxyethylene ether has the following structure: wherein R3is H, methyl or ethyl, R4is an alkyl group of C8to C14, and n is an integer from 6 to 16.

10. The method of claim 9, wherein, R4 is a linear alkyl group having 10 to 12 carbon atoms, and n is an integer of 8 to 12.

11. The method of claim 5, wherein, The total mass fraction of the monomers in the solvent is 5% to 30%.

12. The method of claim 5, wherein the total mass fraction of the monomers in the solvent is 10% to 20%.

13. The method of claim 5, wherein, The initiator is a mixture of persulfate and sulfite, and the mass ratio of persulfate to sulfite is 1:4 to 5:

1.

14. The method of claim 13, wherein the mass ratio of persulfate to sulfite is 1:2 to 3:

1.

15. The method of claim 13, wherein, The persulfate is one or a combination of two or more of ammonium persulfate, potassium persulfate, and sodium persulfate, and the sulfite is one or a combination of two or more of sodium bisulfite, sodium sulfite, potassium bisulfite, potassium sulfite, ammonium sulfite, and ammonium bisulfite.

16. The method of claim 5, wherein, The mass concentration of the initiator is 0.1 to 1.0 wt% of the total concentration of the monomers.

17. The method of claim 5, wherein the mass concentration of the initiator is 0.2 to 0.7 wt% of the total concentration of the monomers.

18. The method of claim 5, wherein, The reaction temperature is 20 to 45°C, and the reaction time is 2 to 20 hours.

19. The method of claim 5, wherein the reaction time is 4 to 12 hours.

20. A method of using a heavy oil viscosity-reducing displacement agent, comprising: The heavy oil viscosity-reducing displacement agent of any one of claims 1 to 4 is diluted with water to a concentration of 0.01 wt% to 0.5 wt%, and injected into a heavy oil-containing formation at a temperature of 10 to 90°C.

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