Anionic poly-surfactant as well as preparation method and application thereof

Abstract

The invention provides an anionic poly-surfactant as well as a preparation method and application thereof, the structural formula of the anionic poly-surfactant comprises the following structural units: # imgabs0 #, in which R1 is uncharged, preferably an uncharged group containing an amide group; r2 is negatively charged, and preferably is a negatively charged group containing organic acid anions; r3 is a lipophilic or amphiphilic long chain, preferably a C12-C50 long chain containing a heteroatom, and the heteroatom is more preferably a nitrogen atom or an oxygen atom; the anionic poly-surfactant is a random copolymer, n, m and o are respectively the total number of corresponding structural units in the anionic poly-surfactant, and the ratio of n: m: o is 1: (0.01-0.2): (0.001-0.02); the anionic poly-surfactant prepared by the method provided by the invention improves the controllability of hydrophilicity / lipophilicity of the poly-surfactant while solving the chromatographic separation problem of polymer-surfactant binary flooding, and improves the effectiveness of regulating the mobility ratio of the poly-surfactant.

Description

Technical Field

[0001] The invention relates to the technical field of oil field production, and more particularly to an anionic surface-polymerizing agent and a preparation method and application thereof. Background Art

[0002] Today's crude oil production is increasingly developing towards demanding reservoirs with high bipolarity (high exploitation degree and high permeability). The remaining oil underground is difficult to drive, and efficiency can only be improved by increasing the swept volume of the displacement fluid and reducing the capillary force of the displacement fluid. The main chemical agents for enhanced oil recovery at home and abroad are polymers and surfactants. Polymers can increase the viscosity of the displacement fluid and thus increase the swept volume, and surfactants can reduce the interfacial tension between the displacement fluid and crude oil and thus reduce the capillary force. The simultaneous use of the two is the so-called polymer-surface binary drive, which can increase viscosity and reduce interfacial tension at the same time. However, due to the large difference in molecular weight between the polymer and the surfactant, the gap can reach 4 to 5 orders of magnitude, and chromatographic separation problems will inevitably occur underground, affecting the efficiency of use.

[0003] Based on this problem, some practitioners have proposed the design of polymer surfactants, which can play a role in viscosity increase and tension reduction as a chemical agent to avoid chromatographic separation. However, some problems were also found during use. Since the viscosity increase ability of polymer surfactants and their interfacial tension are a contradiction, it is difficult to take both into account in the development of polymer surfactants. As a result, when the interfacial activity of polymer surfactants is improved, the viscosity increase effect of polymer surfactants will decrease. If the polymer synthesis process is referred to, the polymer surfactant is post-hydrolyzed to increase the ionization degree of the polymer surfactant, thereby increasing the hydration degree of the polymer surfactant to enhance its viscosity increase ability, but this will increase the hydrophilicity of the polymer surfactant and reduce the lipophilicity, thereby causing the loss of the oil-water interfacial activity of the polymer surfactant. The balance control of the hydrophilicity / lipophilicity of the polymer surfactant is more difficult. In addition, when the polymer surfactant contacts crude oil, the viscosity of the polymer surfactant solution will be further significantly lost, affecting the effect of regulating the mobility ratio of the oil displacement fluid.

[0004] In summary, there is a certain gap between the performance of the existing technology and the usage requirements. Therefore, it is necessary to propose a macromolecular polymer surfactant with better performance to ensure its water solubility and viscosity increasing properties while avoiding flocculation. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides an anionic surface-polymerizing agent and a preparation method and application thereof.

[0006] The present invention controls the hydrophilicity of an anionic polymer surfactant by controlling its anionic degree, and at the same time introduces an interfacial active monomer to achieve the interfacial activity of the anionic polymer surfactant. It solves the problems that the hydrophilicity / lipophilicity of general polymer surfactants is difficult to regulate, resulting in poor water solubility, poor thickening effect, or viscosity loss when encountering crude oil, and the mobility ratio cannot be effectively regulated. An anionic polymer surfactant with good water solubility can be obtained, which improves the controllability of the hydrophilicity / lipophilicity of the polymer surfactant while solving the chromatographic separation problem of polymer-surfactant binary flooding, and improves the effectiveness of the polymer surfactant in regulating the mobility ratio.

[0007] Different from the traditional anionic structure of polyacrylamide introduced by post-hydrolysis, the present invention directly introduces an anionic monomer in the synthesis of the polymer surfactant, adopts one-step synthesis, does not require post-hydrolysis, improves production efficiency and reduces energy consumption at the same time.

[0008] One of the purposes of the present invention is to provide an anionic polymer surfactant, the structural formula of which includes the following structural units:

[0009]

[0010]

[0011] Among them, the structural unit of formula (Ⅰ) is a non-ionic structural unit, the structural unit of formula (Ⅱ) is an anionic structural unit, and the structural unit of formula (Ⅲ) is an interfacial active structural unit; R 1 is uncharged, preferably an uncharged group containing an amide group; R 2 is negatively charged, preferably a negatively charged group containing an organic acid anion; R 3 is a lipophilic or amphiphilic long chain, preferably a lipophilic or amphiphilic C12-C50 long chain containing a heteroatom, and the heteroatom is more preferably a nitrogen atom or an oxygen atom;

[0012] The anionic polymer surfactant is a random copolymer. In the structural formula of the anionic polymer surfactant, n, m, and o are the total number of unit numbers of the corresponding structural units in the anionic polymer surfactant, and n:m:o is 1:(0.01-0.2):(0.001-0.02), preferably 1:(0.02-0.15):(0.002-0.016).

[0013] In a preferred embodiment of the present invention,

[0014] The non-ionic structural unit is obtained from a non-ionic monomer in aqueous solution polymerization; preferably, the non-ionic monomer is at least one of acrylamide, methacrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide;

[0015] The anionic structural unit is obtained from an anionic monomer in aqueous solution polymerization; preferably, the anionic monomer is at least one of sodium acrylate, sodium methacrylate, 2-acrylamido-2-methylpropanesulfonic acid sodium salt, sodium styrenesulfonate, sodium vinylsulfonate, and sodium allylsulfonate.

[0016] In a preferred embodiment of the present invention,

[0017] The surfactant structural unit is obtained from a surfactant monomer in aqueous solution polymerization; preferably, the surfactant monomer is at least one of the compounds with the following structural formula:

[0018] i is an integer between 12 and 24;

[0019] p is an integer between 2 and 4; X - is a halogen negative ion, preferably Cl - 、Br - 、I - one of;

[0020] q is an integer between 12 and 24; Y - is a halogen negative ion, preferably Cl - 、Br - 、I - one of;

[0021] r and s are each independently selected from integers between 5 and 10;

[0022] j is an integer between 5 and 10, and k is an integer between 12 and 24.

[0023] In a preferred embodiment of the present invention,

[0024] The anionic degree of the anionic poly-surfactant is 2.5×10 -4 ~1.6×10 -3 mol / g, preferably 3×10 -4 ~1.2×10 -3 mol / g.

[0025] The anionic degree refers to the number of moles of anions contained in each gram of the dry powder of the anionic poly-surfactant.

[0026] The second object of the present invention is to provide a preparation method of an anionic poly-surfactant, including:

[0027] In the presence of an initiator, the anionic polymer surfactant is obtained by aqueous solution polymerization of polymerizable monomers; the polymerizable monomers include the nonionic monomer, the anionic monomer and the surfactant monomer; the method of the present invention is one-step polymerization;

[0028] Preferably, based on the total weight of the polymerizable monomers and water being 100 parts by weight, it includes 50 - 60 parts by weight of water and 40 - 50 parts by weight of polymerizable monomers; the water is more preferably deionized water;

[0029] Further preferably, in the polymerizable monomers, the molar ratio of the nonionic monomer, the anionic monomer and the surfactant monomer is 1:(0.01 - 0.2):(0.001 - 0.02), and most preferably 1:(0.02 - 0.15):(0.002 - 0.016).

[0030] In a preferred embodiment of the present invention,

[0031] The total mass of the initiator is 0.03 - 0.5 wt% of the total mass of the polymerizable monomers, preferably 0.04 - 0.1 wt%;

[0032] Further preferably, the initiator comprises initiator I, initiator II and initiator III;

[0033] Even more preferably, the mass ratio of initiator I, initiator II and initiator III is 1:(0.5 - 2):(0.5 - 5), and most preferably 1:(0.5 - 1):(0.5 - 3).

[0034] In a preferred embodiment of the present invention,

[0035] The initiator I is an oxidizing initiator, preferably one of hydrogen peroxide, sodium persulfate, ammonium persulfate, potassium persulfate, sodium peroxide, potassium peroxide;

[0036] The initiator II is a reducing initiator, preferably one of sodium thiosulfate, sodium sulfite, sodium bisulfite, potassium sulfite, potassium bisulfite;

[0037] The initiator III is a water-soluble azo initiator, preferably one of 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) dihydrochloride, 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid).

[0038] In a preferred embodiment of the present invention,

[0039] The preparation method includes the following steps:

[0040] (1) Dissolve the nonionic monomer, the anionic monomer and the surfactant monomer in water, and adjust the pH value to obtain a polymerizable monomer solution;

[0041] (2) Dissolve initiator I, initiator II, and initiator III in water respectively to obtain an initiator I solution, an initiator II solution, and an initiator III solution;

[0042] (3) Under the protection of a protective gas, first add the initiator II solution and the initiator III solution obtained in step (2) to the polymerizable monomer solution obtained in step (1), and then add the initiator I solution;

[0043] (4) Remove the protective gas, seal the reaction, obtain a hydrogel of an anionic poly-surfactant, and obtain the anionic poly-surfactant after post-treatment.

[0044] In a preferred embodiment of the present invention,

[0045] Step (1),

[0046] Adjust the pH value of the polymerizable monomer solution to 7.5 - 8.5 with an alkali solution, and the alkali solution is preferably an aqueous sodium hydroxide solution;

[0047] The mass concentration of the polymerizable monomer solution is 30 - 60%, preferably 40 - 50%;

[0048] Step (2),

[0049] Dissolve initiator I, initiator II, and initiator III in deionized water respectively to obtain an initiator I solution, an initiator II solution, and an initiator III solution, and the mass concentrations are independently 0.1 - 2%, preferably 0.5 - 1%;

[0050] Step (3),

[0051] Before adding the initiator solution, cool the polymerizable monomer solution to below 5°C, transfer it into an adiabatic reactor, and introduce a protective gas; the reaction process is carried out in the adiabatic reactor without heat exchange with the outside, insert a thermocouple into the reactor containing the polymerizable monomer solution, and record the reaction process temperature;

[0052] The protective gas is one of nitrogen and inert gases;

[0053] Under the condition of introducing the protective gas, after adding the initiator II solution and the initiator III solution, then add the initiator I solution dropwise; preferably, the time for dropping the initiator I solution is 60 - 180 s;

[0054] Step (4),

[0055] Keep introducing the protective gas for 20 - 40 min after dropping the initiator I solution and before sealing the reactor;

[0056] The time of the closed reaction is 4 to 12 hours, preferably 6 to 8 hours; the thermocouple continuously records the reaction process temperature. After the reaction temperature rises to the highest point, the reaction is continued for a certain period of time and then the reactor is opened to terminate the reaction. The time for maintaining the reaction is 1 to 2 hours, preferably 1 to 1.5 hours;

[0057] The post-treatment includes granulation, drying, and pulverization; preferably drying in a vacuum oven, and the drying time is 60 to 120 min.

[0058] The third object of the present invention is to provide an application of an anionic polymer surfactant in oil production, preferably in enhanced oil recovery operations.

[0059] In a preferred embodiment of the present invention,

[0060] The anionic polymer surfactant is dissolved in injection water matching the target formation to obtain a solution with a mass concentration of the anionic polymer surfactant of 0.1 to 0.5%; preferably,

[0061] The filtration factor of the 0.1 wt% aqueous solution of the anionic polymer surfactant is less than 1.5;

[0062] At 90 °C, the viscosity of the 0.25 wt% aqueous solution of the anionic polymer surfactant is 10 to 35 mPa·s;

[0063] At 90 °C, the viscosity of the 0.5 wt% aqueous solution of the anionic polymer surfactant is 25 to 70 mPa·s;

[0064] After contacting with crude oil, the viscosity of its solution can still remain more than 50% of the original viscosity;

[0065] The interfacial tension with crude oil reaches below 5×10 -2 mN / m within 3 hours, and the final interfacial tension with crude oil is less than 2×10 -2 mN / m;

[0066] The anionic polymer surfactant solution is used in enhanced oil recovery operations and can improve the crude oil recovery rate.

[0067] Compared with the prior art, the beneficial effects of the present invention:

[0068] The polymer surfactant in the prior art has problems such as poor water solubility and viscosity increasing effect caused by difficult regulation of hydrophilicity / lipophilicity, or viscosity loss after encountering crude oil and inability to effectively regulate the mobility ratio; the present invention controls the hydrophilicity of the anionic polymer surfactant by controlling the anionicity, and at the same time introduces an interfacial active monomer to achieve the interfacial activity of the anionic polymer surfactant, preparing an anionic polymer surfactant with good water solubility, solving the chromatographic separation problem of polymer surfactant binary flooding while improving the controllability of the hydrophilicity / lipophilicity of the polymer surfactant and the effectiveness of the polymer surfactant in regulating the mobility ratio.

[0069] The anionic polymer surfactant prepared by the present invention can adapt to different salinities and temperatures, and can provide good viscosity and interfacial tension within a wide range of salinities and temperatures. After contacting with crude oil, the viscosity is well maintained and the mobility ratio is strongly controlled.

[0070] In the synthesis of the polymer surfactant of the present invention, an anionic monomer is directly introduced, and one-step synthesis is adopted without post-hydrolysis, which improves the production efficiency and reduces the energy consumption at the same time. Specific embodiments

[0071] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0072] The raw materials used in the embodiments are all conventional commercially available raw materials.

[0073] Testing methods:

[0074] Anionic degree: For anionic polymer surfactants, it is calculated according to the monomer feed in the synthesis; for post-hydrolyzed polymer surfactants, it is calculated according to (the anionic content converted from the hydrolysis degree + the anionic monomer fed).

[0075] Filtration factor: The filtration factor test is carried out according to the filtration ratio test method in Standard Q / SH1020 1572-2017, item 7.5.

[0076] Viscosity: The testing instrument is a Brookfield LV2T rotational viscometer or a similar type of viscometer; the constant temperature water bath is set to the formation temperature, the 0# rotor is connected to the viscometer, about 16 mL of the solution to be tested is poured into the sample cup, after constant temperature for 4 min, the rotation speed is set to 6 rpm, and after rotating for 4 min, the viscosity value is recorded. After the viscosity value is stable, the viscosity data within 30 s is recorded and its average value is taken as the viscosity test result.

[0077] Interfacial tension: The rotation method is used for testing. The testing instrument is a KRUSSS DT rotational drop interfacial tension meter or a similar type of interfacial tension meter; the high-density phase is the polymer surfactant solution; the low-density phase is the target formation crude oil; the testing temperature is the target formation temperature; the testing rotation speed is 6000 rpm.

[0078] Example 1

[0079] Weigh 100 g of deionized water in a 500 mL beaker, add 80 g (1.125 mol) of acrylamide, 15 g (0.0727 mol) of sodium styrene sulfonate and 5 g (0.0173 mol) of CH 2=CH-CH 2 -N + (CH 3 ) 2 -C 12 H 25 Cl - , stir evenly, adjust the pH value to 8.1 with an aqueous sodium hydroxide solution to obtain a polymer monomer solution.

[0080] Weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of potassium persulfate to obtain initiator I solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of sodium bisulfite to obtain initiator II solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of azobisisobutyramidine hydrochloride to obtain initiator III solution.

[0081] Cool the monomer solution to 5 °C and then add it to a 0.5 L adiabatic reaction kettle. Insert a thermocouple into the reaction kettle containing the polymer monomer solution, record the reaction temperature. After purging with nitrogen for 30 min, while maintaining the nitrogen flow, add 1 g of initiator II solution and 1 g of initiator III solution. Then, dropwise add 2 g of initiator I solution within 120 s. Continue to purge with nitrogen for 30 min, then remove the nitrogen, seal the reaction kettle. After the reaction temperature rises to the highest point, continue the reaction for about 1 hour. The total sealed reaction time is 8 hours to obtain a polymer gel.

[0082] Granulate the gel and place it in a vacuum oven at 120 °C for drying for 1.5 hours, then pulverize to obtain polymer dry powder.

[0083] Example 2

[0084] Weigh 300 g of deionized water in a 1000 mL beaker, add 125 g (1.469 mol) of methacrylamide, 25 g (0.2523 mol) of N,N-dimethylacrylamide, 25 g (0.3516 mol) of acrylamide, 15 g (0.1388 mol) of sodium methacrylate, 10 g (0.0139 mol) of CH 2 =CH-(CH 2 CH 2 O) 10 -C 18 H 37 , stir evenly, adjust the pH value to 8.3 with an aqueous sodium hydroxide solution to obtain a polymer monomer solution.

[0085] Weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of potassium persulfate to obtain initiator I solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of sodium bisulfite to obtain initiator II solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of azobisisobutyramidine hydrochloride to obtain initiator III solution.

[0086] Cool the monomer solution to 5 °C and then add it to a 2 L adiabatic reaction kettle. Insert a thermocouple into the reaction kettle containing the polymerized monomer solution, record the temperature during the reaction process. After purging with nitrogen for 30 min, while maintaining nitrogen flow, add 4 g of initiator II solution and 12 g of initiator III solution. Then, gradually add 4 g of initiator I solution dropwise within 180 s. After purging with nitrogen for another half an hour, remove the nitrogen, seal the reaction kettle. After the reaction temperature rises to the highest point, continue the reaction for about 1 hour. The total sealed reaction time is 8 hours to obtain a polymer gel.

[0087] Granulate the gel and place it in a vacuum oven at 120 °C for drying for 1.5 hours and then crush it to obtain polymer dry powder.

[0088] Example 3

[0089] Weigh 100 g of deionized water in a 500 mL beaker, add 78 g (1.097 mol) of acrylamide, 18 g (0.1249 mol) of sodium allylsulfonate and 4 g (0.0179 mol) of CH 2 =CH-CONH-C 12 H 25 , stir evenly, adjust the pH value to 8.0 with aqueous sodium hydroxide solution to obtain a polymerized monomer solution.

[0090] Weigh 99.5 g of deionized water in a 100 mL beaker, add 0.5 g of potassium persulfate to obtain initiator I solution; weigh 99.5 g of deionized water in a 100 mL beaker, add 0.5 g of sodium bisulfite to obtain initiator II solution; weigh 99.5 g of deionized water in a 100 mL beaker, add 0.5 g of azobisisobutyramidine hydrochloride to obtain initiator III solution.

[0091] Cool the monomer solution to 5 °C and then add it to a 0.5 L adiabatic reaction kettle. Insert a thermocouple into the reaction kettle containing the polymerized monomer solution, record the temperature during the reaction process. After purging with nitrogen for 30 min, while maintaining nitrogen flow, add 3 g of initiator II solution and 4 g of initiator III solution. Then, gradually add 4 g of initiator I solution dropwise within 120 s. Continue purging with nitrogen for another half an hour and then remove the nitrogen, seal the reaction kettle. After the reaction temperature rises to the highest point, continue the reaction for about 1 hour. The total sealed reaction time is 6 hours to obtain a polymer gel.

[0092] The gel was granulated and then placed in a vacuum oven at 120 °C for drying for 1.5 hours and then pulverized to obtain a polymer dry powder.

[0093] Example 4

[0094] In a 1000 mL beaker, 300 g of deionized water was weighed, and 230 g (2.703 mol) of methacrylamide, 17.5 g (0.0764 mol) of 2-acrylamido-2-methylpropanesulfonic acid sodium salt, and 2.5 g (0.0079 mol) of CH 2 =CH-CH 2 -N + (CH 3 ) 2 -(C 6 H 4 ) 2 -HBr - were added, stirred evenly, and the pH value was adjusted to 7.9 with an aqueous sodium hydroxide solution to obtain a polymer monomer solution.

[0095] In a 100 mL beaker, 49.5 g of deionized water was weighed, and 0.5 g of potassium persulfate was added to obtain Initiator I solution; in a 100 mL beaker, 49.5 g of deionized water was weighed, and 0.5 g of sodium bisulfite was added to obtain Initiator II solution; in a 100 mL beaker, 49.5 g of deionized water was weighed, and 0.5 g of azodiisobutyramidine hydrochloride was added to obtain Initiator III solution.

[0096] The monomer solution was cooled to 5 °C and then added to a 2 L adiabatic reaction autoclave. A thermocouple was inserted into the autoclave containing the polymer monomer solution to record the reaction process temperature. After purging with nitrogen for 30 min, while maintaining the nitrogen flow, 4 g of Initiator II solution and 12 g of Initiator III solution were added. Then, 4 g of Initiator I solution was added dropwise within 180 s. After purging with nitrogen for another half an hour, the nitrogen was removed, and the reaction autoclave was sealed. After the reaction temperature rose to the highest point, the reaction was continued for about 1 hour. The total sealed reaction time was 8 hours to obtain a polymer gel.

[0097] The gel was granulated and then placed in a vacuum oven at 120 °C for drying for 1.5 hours and then pulverized to obtain a polymer dry powder.

[0098] Comparative Example 1

[0099] The difference from Example 1 is: the polymer monomer solution is different;

[0100] The monomer solution of Comparative Example 1 was prepared by adding 95 g (1.336 mol) of acrylamide and 5 g (0.0173 mol) of CH 2 =CH-CH 2 -N + (CH3 ) 2 -C 12 H 25 Cl - , stir evenly, and adjust the pH value to 8.2 with an aqueous sodium hydroxide solution to obtain;

[0101] Except for the above differences, other conditions in Comparative Example 1 are the same as those in Example 1 to obtain a polymer dry powder.

[0102] Comparative Example 2

[0103] Weigh 100 g of deionized water in a 500 mL beaker, add 90 g (1.266 mol) of acrylamide, 5 g (0.0218 mol) of 2-acrylamido-2-methylpropanesulfonic acid sodium salt and 5 g (0.0173 mol) of CH 2 =CH-CH 2 -N + -(CH 3 ) 2 -C 12 H 25 Cl - , stir evenly, and adjust the pH value to 8.2 with an aqueous sodium hydroxide solution to obtain a polymer monomer solution.

[0104] Weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of potassium persulfate to obtain Initiator I solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of sodium bisulfite to obtain Initiator II solution; weigh 49.5 g of deionized water in a 100 mL beaker, add 0.5 g of azodiisobutyramidine hydrochloride to obtain Initiator III solution.

[0105] Cool the monomer solution to 5 °C and then add it to a 0.5 L adiabatic reactor. Insert a thermocouple into the reactor containing the polymer monomer solution, record the reaction temperature, after introducing nitrogen for 30 min, while maintaining the nitrogen flow, add 1 g of Initiator II solution and 1 g of Initiator III solution, then dropwise add 2 g of Initiator I solution within 120 s, continue to introduce nitrogen for half an hour and then remove the nitrogen, seal the reactor, continue the reaction for about 1 hour after the reaction temperature rises to the highest point, and the total sealed reaction time is 8 hours to obtain a polymer gel.

[0106] After gel granulation, place the gel in a 500 mL beaker, add 8 g of a 1% NaOH solution, mix the NaOH solution and the gel particles evenly, and place them in a water bath at 85 °C for post-hydrolysis reaction for 1.5 hr.

[0107] The post-hydrolysis reaction can improve the anionicity of the product, and 1 mol of NaOH can generate 1 mol of carboxylate groups on the polymer.

[0108] The product after post-hydrolysis was dried in a vacuum oven at 120 °C for 1.5 hours and then pulverized to obtain polymer dry powder.

[0109] Performance test:

[0110] Prepare a formulated water containing CaCl 2 11100 mg / L, MgCl 2 3958 mg / L, and NaCl 64942 mg / L (total salinity 80000 mg / L, total calcium and magnesium content 5000 mg / L).

[0111] Weigh 198 g of the formulated water in a 600 mL tall-form beaker, place it on a mechanical stirrer, start stirring at 500 rpm, and slowly add 2 g of the anionic poly-surfactant dry powder in Examples 1-4 and the poly-surfactant dry powder in Comparative Examples 1-2 respectively. Then increase the stirring rate to 700 rpm and stir for 2 hours to obtain a 1% poly-surfactant mother liquor, and let it stand for 24 hours.

[0112] Dilute part of the mother liquor with the formulated water to a concentration of 0.1% to obtain a poly-surfactant test solution, and measure its filtration factor at room temperature; dilute part of the mother liquor with the formulated water to a concentration of 0.25% to obtain a poly-surfactant test solution, and measure its viscosity and interfacial tension at 90 °C. When the viscosity of the test solution is 10-35 mPa·s and the interfacial tension < 2×10 -2 mN / m, mix the poly-surfactant test solution and crude oil at a weight ratio of 95:5, stir on a magnetic stirrer at a speed of 300 rpm for 15 min, then let it stand for more than 2 hours. After the oil-water separation, take the lower aqueous solution to measure the viscosity after contacting the crude oil; for samples with a viscosity lower than 35 mPa·s at 0.25%, dilute part of the mother liquor with the formulated water to a concentration of 0.5% to obtain a poly-surfactant test solution, and measure its viscosity and interfacial tension at 90 °C. The test results are shown in Table 1.

[0113] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-2

[0114]

[0115] As can be seen from Table 1, compared with Example 1, in Comparative Example 1, the anionic monomer sodium styrene sulfonate was replaced with the non-ionic monomer acrylamide in equal mass, and its anionicity was 0; if such a large amount of the corresponding anionic monomer was directly added during the reaction, the polymerization reaction would have problems. In Comparative Example 2, a method of pre-polymerization and then hydrolysis was adopted, and through post-hydrolysis, the anionicity was increased to reach 2.2×10 -3 mol / g, which is much higher than that of Examples 1-4 ((3.1-11)×10 -4 mol / g).

[0116] Compared with Comparative Examples 1-2, the filtration factors of Examples 1-4 are less than 1.5, the viscosities (0.25%, 0.5%) are higher, the viscosity of the anionic polymer surfactant solution at 0.25 wt% at 90 °C is 10-35 mPa·s, and the viscosity of the anionic polymer surfactant solution at 0.5 wt% is 25-70 mPa·s. The lowest interfacial tension (0.25 wt%, 0.5 wt%) is lower, and the interfacial tension with crude oil reaches 5×10 -2 mN / m or less within 3 hours, and the final interfacial tension is less than 2×10 -2 mN / m. After contacting with crude oil, the viscosity of its solution can still remain more than 50% of the original viscosity, which proves that too high or too low anionic degree of the anionic polymer surfactant will significantly affect its performance. The anionic polymer surfactant solutions of Examples 1-4 with the anionic degree controlled within a certain range are used in enhanced oil recovery operations, which can improve the oil recovery rate.

[0117] The anionic degree of the anionic polymer surfactants prepared in Examples 1-4 is (3.1-11)×10 -4 mol / g. The hydrophilicity of the anionic polymer surfactant is controlled by the anionic degree, and at the same time, interfacial active monomers are introduced to achieve the interfacial activity of the anionic polymer surfactant, and an anionic polymer surfactant with good water solubility is prepared. While solving the chromatographic separation problem of polymer surfactant binary flooding, the controllability of the hydrophilicity / lipophilicity of the polymer surfactant is improved, the effectiveness of the polymer surfactant in regulating the mobility ratio is improved, and the problems in the prior art that the polymer surfactant has poor water solubility and viscosity increasing effect due to difficult regulation of hydrophilicity / lipophilicity, or the viscosity loss after encountering crude oil and inability to effectively regulate the mobility ratio are solved.

[0118] The anionic polymer surfactants prepared in Examples 1-4 can adapt to different salinities and temperatures, and can provide good viscosities and interfacial tensions within a wide range of salinities and temperatures. The viscosity remains good after contacting with crude oil, and the mobility ratio control is strong.

Claims

1. An anionic polymer surfactant, the structural formula of which includes the following structural units: Wherein, The structural unit of formula (I) is a non-ionic structural unit, the structural unit of formula (II) is an anionic structural unit, and the structural unit of formula (III) is a surfactant structural unit; R 1 is uncharged, preferably an uncharged group containing an amide group; R 2 is negatively charged, preferably a negatively charged group containing an organic acid anion; R 3 is a lipophilic or amphiphilic long chain, preferably a lipophilic or amphiphilic C12-C50 long chain containing a heteroatom, and the heteroatom is more preferably a nitrogen atom or an oxygen atom; The anionic polymer surfactant is a random copolymer. In the structural formula of the anionic polymer surfactant, n, m, and o are respectively the total number of units of the corresponding structural units in the anionic polymer surfactant, and n:m:o is 1:(0.01 - 0.2):(0.001 - 0.02), preferably 1:(0.02 - 0.15):(0.002 - 0.016).

2. The anionic polymer surfactant according to claim 1, Characterized in that: The non-ionic structural unit is obtained from non-ionic monomers in aqueous solution polymerization; preferably, the non-ionic monomer is at least one of acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide; and / or, The anionic structural unit is obtained from anionic monomers in aqueous solution polymerization; preferably, the anionic monomer is at least one of sodium acrylate, sodium methacrylate, 2-acrylamido-2-methylpropanesulfonic acid sodium salt, sodium styrenesulfonate, sodium vinylsulfonate, sodium allylsulfonate.

3. The anionic polymer surfactant according to claim 1, Characterized in that: The interfacial activity structural unit is obtained from interfacial activity monomers in aqueous solution polymerization; preferably, the interfacial activity monomer is at least one of the compounds with the following structural formula: i is an integer between 12 and 24; p is an integer between 2 and 4; X - is a halogen anion, preferably Cl - , Br - , I - ; and one of them q is an integer between 12 and 24; Y - is a halogen anion, preferably Cl - , Br - , I - ; and one of them r and s are each independently selected from integers between 5 and 10; j is an integer between 5 and 10, and k is an integer between 12 and 24.

4. The anionic polymer surfactant according to any one of claims 1 - 3, Characterized in that: The anionic degree of the anionic polymer surfactant is 2.5×10 -4 ~1.6×10 -3 mol / g, preferably 3×10 -4 ~1.2×10 -3 mol / g.

5. A preparation method of the anionic polymer surfactant according to any one of claims 1 - 4, Comprising: In the presence of an initiator, the anionic polymer surfactant is obtained by aqueous solution polymerization of polymerization monomers; the polymerization monomers include the non-ionic monomers, the anionic monomers and the interfacial activity monomers; preferably, Based on the total weight of the polymerization monomers and water being 100 parts by weight, it includes 50 - 60 parts by weight of water and 40 - 50 parts by weight of polymerization monomers; the water is more preferably deionized water; Further preferably, in the polymerization monomers, the molar ratio of the non-ionic monomer, the anionic monomer and the interfacial activity monomer is 1:(0.01 - 0.2):(0.001 - 0.02), and most preferably 1:(0.02 - 0.15):(0.002 - 0.016).

6. The preparation method of the anionic polymer surfactant according to claim 5, Characterized in that: The total mass of the initiator is 0.03 - 0.5 wt% of the total mass of the polymerization monomers, preferably 0.04 - 0.1 wt%; Further preferably, the initiator includes initiator I, initiator II and initiator III; Even more preferably, the mass ratio of initiator I, initiator II and initiator III is 1:(0.5 - 2):(0.5 - 5), and most preferably 1:(0.5 - 1):(0.5 - 3).

7. The preparation method of the anionic polymer surfactant according to claim 6, Characterized in that: The initiator I is an oxidative initiator, preferably one of hydrogen peroxide, sodium persulfate, ammonium persulfate, potassium persulfate, sodium peroxide, potassium peroxide; and / or, The initiator II is a reducing initiator, preferably one of sodium thiosulfate, sodium sulfite, sodium bisulfite, potassium sulfite, and potassium bisulfite; and / or, The initiator III is a water-soluble azo initiator, preferably one of azodiisobutyramidine hydrochloride, azodiisobutyramidine hydrochloride, azodiisopropylimidazoline hydrochloride, and azodicyanovaleric acid.

8. The preparation method of the anionic poly-surfactant according to any one of claims 5 to 7, characterized in that the method comprises the following steps: (1) Dissolve the non-ionic monomer, anionic monomer, and interfacial active monomer in water, and adjust the pH value to obtain a polymerization monomer solution; (2) Dissolve the initiator I, initiator II, and initiator III in water respectively to obtain an initiator I solution, an initiator II solution, and an initiator III solution; (3) Under the protection of a protective gas, first add the initiator II solution and initiator III solution obtained in step (2) to the polymerization monomer solution obtained in step (1), and then add the initiator I solution; (4) Remove the protective gas, seal the reaction to obtain a hydrogel of the anionic poly-surfactant, and obtain the anionic poly-surfactant after post-treatment.

9. The preparation method of the anionic poly-surfactant according to claim 8, characterized in that the method comprises the following steps: Step (1), Adjust the pH value of the polymerization monomer solution to 7.5 - 8.5 with an alkali solution, and the alkali solution is preferably an aqueous sodium hydroxide solution; and / or, The mass concentration of the polymerization monomer solution is 30 - 60%, preferably 40 - 50%; and / or, Step (2), Dissolve the initiator I, initiator II, and initiator III in deionized water respectively to obtain an initiator I solution, an initiator II solution, and an initiator III solution, and the mass concentrations are independently 0.1 - 2%, preferably 0.5 - 1%; and / or, Step (3), Cool the polymerization monomer solution to below 5°C before adding the initiator solution, transfer it to an adiabatic reactor, and introduce a protective gas; preferably, the time for introducing the protective gas is 15 - 45 min; and / or, The protective gas is one of nitrogen and inert gas; and / or, Under the condition of introducing the protective gas, after adding the initiator II solution and initiator III solution, add the initiator I solution dropwise; preferably, the time for dropping the initiator I solution is 60 - 180 s; and / or, Step (4), Keep introducing the protective gas for 20 - 40 min after dropping the initiator I solution and before sealing the reactor; and / or, The time for the sealed reaction is 4 - 12 hours, preferably 6 - 8 hours; and / or, The post-treatment includes granulation, drying, and pulverization; preferably, drying is carried out in a vacuum oven, and the drying time is 60 - 120 min.

10. The application of the anionic poly-surfactant according to any one of claims 1 to 4 or the anionic poly-surfactant obtained by the preparation method according to any one of claims 5 to 9 in oil recovery, preferably in enhanced oil recovery operations.

11. The application according to claim 10, characterized in that: Dissolve the anionic polymer surfactant in the injection water matching the target formation to obtain a solution with a mass concentration of the anionic polymer surfactant of 0.1-0.5%; preferably, the filtration factor of the 0.1 wt% aqueous solution of the anionic polymer surfactant is less than 1.5; and / or, at 90 °C, the viscosity of the 0.25 wt% aqueous solution of the anionic polymer surfactant is 10-35 mPa·s; and / or, at 90 °C, the viscosity of the 0.5 wt% aqueous solution of the anionic polymer surfactant is 25-70 mPa·s; and / or, after contacting with crude oil, the viscosity of its solution can still remain more than 50% of the original viscosity; and / or, The interfacial tension with crude oil reaches below 5×10 -2 mN / m within 3 hours, and finally the interfacial tension with crude oil is less than 2×10 -2 mN / m.

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