Multifunctional polymer for improving recovery efficiency and preparation method thereof

Abstract

The invention discloses a multifunctional polymer for improving recovery efficiency and a preparation method thereof, and relates to the technical field of oil exploitation, the multifunctional polymer comprises a multifunctional salt-resistant polymer, the multifunctional salt-resistant polymer comprises the following components by weight: 240-280 parts of acrylamide; 15 parts to 30 parts of AMPS (2, 2, 4-trimethyl-1 6 parts to 15 parts of NNO; 10 to 40 parts of a functional monomer S; 6 to 9 parts of urea; 0.2 to 0.25 part of a 1 # initiator; 0.06 to 0.18 part of a 2 # initiator; 0.06 to 0.18 part of a 3 # initiator; and 720 to 760 parts of water. The multifunctional polymer for improving the recovery ratio and the preparation method thereof have the characteristics of bacteria resistance, salt resistance, good emulsifying activity and capability of being prepared by using oilfield produced sewage, and can keep good solubility under a sewage condition, so that the oil recovery ratio is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil exploitation, and particularly relates to a multifunctional polymer for enhancing oil recovery and a preparation method thereof. Background Art

[0002] At present, many oilfields have entered the tertiary oil recovery stage of high water cut reservoirs. Laboratory experiments and field tests on polymer flooding technology have shown that polymer flooding is an effective method for enhancing oil recovery. However, due to the limited fresh water resources, in order to reduce the production cost and protect the geological conditions of oilfield exploitation, the produced sewage is treated and then used for formulation and reinjection. However, sulfate reducing bacteria, iron bacteria, saprophytic bacteria, etc. mainly exist in the sewage. PAM can be decomposed as a carbon source for the above bacteria, reducing the viscosity and affecting the production efficiency. Developing a multifunctional polymer with antibacterial property, salt resistance and emulsifying property has great market prospects. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a multifunctional polymer for enhancing oil recovery and a preparation method thereof. The polymer has the characteristics of antibacterial property, salt resistance, good emulsifying activity and can be formulated with the produced sewage of the oilfield. Under sewage conditions, it can maintain good solubility and improve the oil recovery rate.

[0004] The technical solution adopted by the present invention is as follows: The components and parts by weight of the multifunctional salt-resistant polymer are: 240 parts - 280 parts of acrylamide; 15 parts - 30 parts of AMPS; 6 parts - 15 parts of NNO; 10 parts - 40 parts of functional monomer S; 6 parts - 9 parts of urea; 0.2 parts - 0.25 parts of initiator 1#; 0.06 parts - 0.18 parts of initiator 2#; 0.06 parts - 0.18 parts of initiator 3#; 720 parts - 760 parts of water.

[0005] Further, the initiator 1# is one or more of azobisisobutyronitrile, azobisisoheptonitrile or azobisisobutylamidine hydrochloride.

[0006] Further, the initiator 2# is one or more of ammonium persulfate, potassium persulfate or sodium persulfate.

[0007] Further, the initiator 3# is one or more of sodium bisulfite, sodium thiosulfate or triethanolamine.

[0008] Further, the functional monomer S is:

[0009]

[0010] Further, the preparation method of the functional monomer S includes the following steps:

[0011] Step 1: Add the solvent DMF into the reaction kettle, and then add dehydroabietylamine, whose molecular formula is:

[0012]

[0013] Add excessive isobutene, heat the reaction kettle to 90 °C, put potassium carbonate as the catalyst into the reaction kettle, after reacting for 4 h, rotary evaporate under reduced pressure at 35 °C to remove the solvent, and the reaction formula is:

[0014]

[0015] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid under the condition of a temperature of 0 - 5 °C, and the reaction formula is:

[0016]

[0017] Step 3: React the product obtained in Step 2 with:

[0018]

[0019] n = 10 - 16

[0020] Add EDC, and conduct the reaction in the reaction kettle. Add hydroquinone to prevent polymerization during the reaction, and the reaction formula is:

[0021]

[0022] Step 4: In a closed container, under the protection of nitrogen, add ammonium sulfide to the product obtained in Step 3 and stir to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction, and the reaction formula is:

[0023]

[0024] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of a pH of 9.5 - 10.5, and the reaction formula is:

[0025]

[0026] Step 6: At a temperature of 35 - 45 °C, rotary evaporate under low temperature and reduced pressure to remove the solvent from the product obtained in Step 5, and obtain the functional monomer S.

[0027] Furthermore, a preparation method of a multifunctional polymer for improving oil recovery includes the following steps:

[0028] (1), Mix the functional monomer S and NNO and set aside;

[0029] (2), Dissolve AMPS with ice water and neutralize it with sodium hydroxide;

[0030] (3) Add acrylamide and the monomers prepared in steps (1) and (2) to urea and water, stir and mix evenly, and then adjust the pH value with 10% sodium hydroxide solution to 6.9 - 7.1;

[0031] (4) After adjusting the temperature of the solution prepared in step (3) to 9°C - 11°C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 minutes to remove oxygen; after deoxygenation, add initiator 1# to the reaction kettle, add initiator 2# after 6 minutes, and add initiator 3# after another 6 minutes. Stop introducing nitrogen after the temperature of the system in the kettle starts to rise; when the reaction is completed and the temperature no longer rises, continue to cure for 3 hours to obtain a polymer colloid;

[0032] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75°C for 6 hours, then dry at 70°C for 14 hours, and then crush and screen to obtain particles with a particle size of 400μm - 800μm. These particles are the finished product of the multifunctional salt-resistant polymer.

[0033] The beneficial effects of the present invention: It provides a preparation method of a multifunctional polymer for improving oil recovery. This polymer has excellent antibacterial properties, salt resistance, and emulsifying activity, and can be prepared using the produced sewage in oil fields. Under sewage conditions, it can maintain good solubility, and in the formation, it can improve the oil washing efficiency through its emulsifying properties, and significantly improve the oil recovery rate. Specific embodiments

[0034] Example 1

[0035] A preparation method of a multifunctional polymer for improving oil recovery, comprising the following steps:

[0036] (1) Mix 10 parts of functional monomer S and 6 parts of NNO for later use;

[0037] (2) Dissolve 15 parts of AMPS in ice water and neutralize it with sodium hydroxide;

[0038] (3) Add 240 parts of acrylamide and the monomers prepared in steps (1) and (2) to 6 parts of urea and 760 parts of water, stir and mix evenly, and then adjust the pH value with 10% sodium hydroxide solution to 6.9 - 7.1;

[0039] The molecular formula of functional monomer S is:

[0040]

[0041] where n = 10;

[0042] The preparation method of functional monomer S includes the following steps:

[0043] Step 1: Add the solvent DMF into the reaction kettle, and then add dehydroabietylamine, whose molecular formula is:

[0044]

[0045] Add excessive isobutene, heat the reaction kettle to 90 °C, add potassium carbonate as a catalyst into the reaction kettle, and after reacting for 4 h, rotary evaporate the solvent under reduced pressure at 35 °C. The reaction formula is:

[0046]

[0047] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid under the condition of a temperature of 0 - 5 °C. The reaction formula is:

[0048]

[0049] Step 3: React the product obtained in Step 2 with:

[0050]

[0051] n = 10 - 16

[0052] Add EDC, and carry out the reaction in the reaction kettle. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0053]

[0054] Step 4: Add ammonium sulfide and stir in a closed container under nitrogen protection for the product obtained in Step 3 to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0055]

[0056] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of a pH of 9.5 - 10.5. The reaction formula is:

[0057]

[0058] Step 6: After rotary evaporating the solvent at a low temperature under reduced pressure for the product obtained in Step 5 at a temperature of 35 - 45 °C, obtain the functional monomer S.

[0059] (4) After adjusting the temperature of the solution prepared in step (3) to 9°C - 11°C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 minutes to remove oxygen. After deoxygenation, add 0.2 parts of azobisisobutyronitrile to the reaction kettle, add 0.06 parts of ammonium persulfate after 6 minutes, and then add 0.06 parts of sodium bisulfite after another 6 minutes. Stop introducing nitrogen after the temperature of the system in the kettle starts to rise. After the reaction is completed and the temperature no longer rises, continue to cure for 3 hours to obtain a polymer colloid;

[0060] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75°C for 6 hours, then dry at 70°C for 14 hours, and then crush and screen to obtain particles with a particle size of 400μm - 800μm. This particle is the finished product of the multifunctional salt-resistant polymer.

[0061] Example Two

[0062] A preparation method of a multifunctional polymer for improving oil recovery, comprising the following steps:

[0063] (1) Mix 10 parts of functional monomer S and 6 parts of NNO and set aside;

[0064] (2) Dissolve 30 parts of AMPS in ice water and neutralize with sodium hydroxide;

[0065] (3) Add 240 parts of acrylamide and the monomers prepared in steps (1) and (2) to 6 parts of urea and 760 parts of water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to a pH value of 6.9 - 7.1;

[0066] The molecular formula of functional monomer S is:

[0067]

[0068] where n = 12;

[0069] The preparation method of functional monomer S includes the following steps:

[0070] Step 1: Add the solvent DMF to the reaction kettle, and then add dehydroabietylamine, whose molecular formula is:

[0071]

[0072] Add excessive isobutene, heat the reaction kettle to 90°C, put potassium carbonate as a catalyst in the reaction kettle, and after reacting for 4 hours, rotary evaporate the solvent under reduced pressure at 35°C. The reaction formula is:

[0073]

[0074] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid at a temperature of 0 - 5°C. The reaction equation is:

[0075]

[0076] Step 3: React the product obtained in Step 2 with:

[0077]

[0078] n = 10 - 16

[0079] Add EDC and carry out the reaction in a reaction kettle. Add hydroquinone to prevent polymerization during the reaction. The reaction equation is:

[0080]

[0081] Step 4: Add ammonium sulfide to the product obtained in Step 3 in a sealed container under nitrogen protection and stir to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction. The reaction equation is:

[0082]

[0083] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three - necked flask under the condition of pH 9.5 - 10.5. The reaction equation is:

[0084]

[0085] Step 6: At a temperature of 35 - 45°C, remove the solvent by low - temperature vacuum rotary evaporation from the product obtained in Step 5 to obtain the functional monomer S.

[0086] (4) After adjusting the temperature of the solution prepared in step (3) to 9°C - 11°C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 min to remove oxygen. After deoxygenation, add 0.2 parts of azodiisobutyronitrile to the reaction kettle. After 6 min, add 0.06 parts of potassium persulfate, and after another 6 min, add 0.06 parts of sodium bisulfite. Stop introducing nitrogen when the temperature of the system in the kettle starts to rise. When the reaction is completed and the temperature no longer rises, continue to cure for 3 h to obtain a polymer colloid.

[0087] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75°C for 6 h, then dry at 70°C for 14 h, crush and screen to obtain particles with a particle size of 400 μm - 800 μm. This particle is the finished product of the multifunctional salt - resistant polymer.

[0088] Example 3

[0089] A preparation method of a multifunctional polymer for enhancing oil recovery, comprising the following steps:

[0090] (1) Mix 20 parts of functional monomer S and 6 parts of NNO and set aside.

[0091] (2) Dissolve 30 parts of AMPS in ice water and neutralize with sodium hydroxide.

[0092] (3) Add 240 parts of acrylamide and the monomers prepared in steps (1) and (2) to 6 parts of urea and 760 parts of water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to 6.9 - 7.1.

[0093] The molecular formula of functional monomer S is:

[0094]

[0095] where n = 16;

[0096] The preparation method of functional monomer S comprises the following steps:

[0097] Step 1: Add solvent DMF to the reaction kettle, and then add dehydroabietylamine, whose molecular formula is:

[0098]

[0099] Add excessive isobutene, heat the reaction kettle to 90 °C, put potassium carbonate as a catalyst into the reaction kettle, and after reacting for 4 h, rotary evaporate the solvent under reduced pressure at 35 °C. The reaction formula is:

[0100]

[0101] Step 2: React the product obtained in step 1 with a mixed acid of nitric acid and sulfuric acid under the condition of 0 - 5 °C. The reaction formula is:

[0102]

[0103] Step 3: React the product obtained in step 2 with:

[0104]

[0105] n = 10 - 16

[0106] Add EDC, carry out the reaction in the reaction kettle, and add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0107]

[0108] Step 4: Add ammonium sulfide to the product obtained in Step 3 in a sealed container under nitrogen protection and stir to reduce the nitro group to an amino group. Hydroquinone is added during the reaction to prevent polymerization. The reaction equation is as follows:

[0109]

[0110] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of pH 9.5 - 10.5. The reaction equation is as follows:

[0111]

[0112] Step 6: After removing the solvent by low-temperature vacuum rotary evaporation of the product obtained in Step 5 at a temperature of 35 - 45 °C, functional monomer S is obtained.

[0113] (4) After adjusting the temperature of the solution prepared in step (3) to 9 °C - 11 °C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 min to remove oxygen. After deoxygenation, add 0.2 parts of azobisisobutyronitrile to the reaction kettle. After 6 min, add 0.06 parts of ammonium persulfate, and after another 6 min, add 0.06 parts of sodium thiosulfate. Stop introducing nitrogen when the temperature of the system in the kettle starts to rise. After the reaction is completed and the temperature no longer rises, continue to cure for 3 h to obtain a polymer colloid.

[0114] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75 °C for 6 h, then dry at 70 °C for 14 h, crush and screen to obtain particles with a particle size of 400 μm - 800 μm. This particle is the finished product of the multifunctional salt-resistant polymer.

[0115] Example 4

[0116] A preparation method of a multifunctional polymer for enhancing oil recovery, comprising the following steps:

[0117] (1) Mix 40 parts of functional monomer S and 6 parts of NNO and set aside.

[0118] (2) Dissolve 30 parts of AMPS in ice water and neutralize with sodium hydroxide.

[0119] (3) Add 260 parts of acrylamide and the monomers prepared in steps (1) and (2) to 9 parts of urea and 740 parts of water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to pH 6.9 - 7.1.

[0120] The molecular formula of functional monomer S is:

[0121]

[0122] where n = 14;

[0123] The preparation method of the functional monomer S comprises the following steps:

[0124] Step 1: Add the solvent DMF into a reaction kettle, and then add dehydroabietylamine, whose molecular formula is:

[0125]

[0126] Add excessive isobutene, heat the reaction kettle to 90 °C, put potassium carbonate into the reaction kettle as a catalyst, and after reacting for 4 h, rotary evaporate the solvent under reduced pressure at 35 °C. The reaction formula is:

[0127]

[0128] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid under the condition of a temperature of 0 - 5 °C. The reaction formula is:

[0129]

[0130] Step 3: React the product obtained in Step 2 with:

[0131]

[0132] n = 10 - 16

[0133] Add EDC, and carry out the reaction in the reaction kettle. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0134]

[0135] Step 4: Put the product obtained in Step 3 into a closed container, add ammonium sulfide under the protection of nitrogen and stir to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0136]

[0137] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of a pH of 9.5 - 10.5. The reaction formula is:

[0138]

[0139] Step 6: After rotary evaporating the solvent at a low temperature under reduced pressure for the product obtained in Step 5 at a temperature of 35 - 45 °C, the functional monomer S is obtained;

[0140] (4) After adjusting the temperature of the solution prepared in step (3) to 9°C - 11°C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 minutes to remove oxygen. After deoxygenation, add 0.25 parts of azobisisobutyronitrile to the reaction kettle, add 0.18 parts of ammonium persulfate after 6 minutes, and then add 0.18 parts of sodium bisulfite after another 6 minutes. Stop introducing nitrogen after the temperature of the system in the kettle starts to rise. After the reaction is completed and the temperature no longer rises, continue to cure for 3 hours to obtain a polymer colloid;

[0141] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75°C for 6 hours, then dry at 70°C for 14 hours, crush and screen to obtain particles with a particle size of 400μm - 800μm, and this particle is the finished product of the multifunctional salt-resistant polymer.

[0142] Example Five

[0143] A preparation method of a multifunctional polymer for improving oil recovery, comprising the following steps:

[0144] (1) Mix 20 parts of functional monomer S and 15 parts of NNO and set aside;

[0145] (2) Dissolve 20 parts of AMPS in ice water and neutralize with sodium hydroxide;

[0146] (3) Add 260 parts of acrylamide and the monomers prepared in steps (1) and (2) to 9 parts of urea and 740 parts of water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to a pH value of 6.9 - 7.1;

[0147] The molecular formula of functional monomer S is:

[0148]

[0149] where n = 15;

[0150] The preparation method of functional monomer S includes the following steps:

[0151] Step 1: Add the solvent DMF to the reaction kettle, and then add dehydroabietylamine, and its molecular formula is:

[0152]

[0153] Add excessive isobutene, heat the reaction kettle to 90°C, put potassium carbonate as a catalyst in the reaction kettle, and after reacting for 4 hours, rotary evaporate the solvent under reduced pressure at 35°C. The reaction formula is:

[0154]

[0155] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid at a temperature of 0 - 5°C. The reaction equation is:

[0156]

[0157] Step 3: React the product obtained in Step 2 with:

[0158]

[0159] n = 10 - 16

[0160] Add EDC and carry out the reaction in a reaction kettle. Add hydroquinone to prevent polymerization during the reaction. The reaction equation is:

[0161]

[0162] Step 4: In a closed container, add ammonium sulfide under nitrogen protection to the product obtained in Step 3 and stir to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction. The reaction equation is:

[0163]

[0164] Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of pH 9.5 - 10.5. The reaction equation is:

[0165]

[0166] Step 6: At a temperature of 35 - 45°C, remove the solvent by low-temperature vacuum rotary evaporation from the product obtained in Step 5 to obtain the functional monomer S.

[0167] (4) After adjusting the temperature of the solution prepared in step (3) to 9°C - 11°C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 min to remove oxygen. After deoxygenation, add 0.2 parts of azobisisobutyronitrile to the reaction kettle. After 6 min, add 0.12 parts of ammonium persulfate, and after another 6 min, add 0.12 parts of sodium bisulfite. Stop introducing nitrogen when the system in the kettle starts to heat up. When the reaction is completed and no longer heats up, continue to cure for 3 h to obtain a polymer colloid.

[0168] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75°C for 6 h, then dry at 70°C for 14 h, crush and screen to obtain particles with a particle size of 400 μm - 800 μm. This particle is the finished product of the multifunctional salt-resistant polymer.

[0169] Example 6

[0170] A preparation method of a multifunctional polymer for enhanced oil recovery, comprising the following steps:

[0171] (1) Mix 40 parts of functional monomer S and 15 parts of NNO and set aside.

[0172] (2) Dissolve 30 parts of AMPS in ice water and neutralize with sodium hydroxide.

[0173] (3) Add 280 parts of acrylamide and the monomers prepared in steps (1) and (2) to 9 parts of urea and 720 parts of water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to 6.9 - 7.1.

[0174] The molecular formula of functional monomer S is:

[0175]

[0176] where n = 16;

[0177] The preparation method of functional monomer S includes the following steps:

[0178] Step 1: Add dehydroabietylamine to the reaction kettle, and its molecular formula is:

[0179]

[0180] Heat the reaction kettle to 85 - 100 °C, add potassium carbonate as a catalyst to the reaction kettle, and react in the solvent DMF. The reaction formula is:

[0181]

[0182] Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid at a temperature of 0 - 5 °C. The reaction formula is:

[0183]

[0184] Step 3: React the product obtained in Step 2 with:

[0185]

[0186] n = 16

[0187] , add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0188]

[0189] Step 4: Add ammonium sulfide to the product obtained in Step 3 under nitrogen protection to reduce the nitro group to an amino group, and add hydroquinone to prevent polymerization during the reaction. The reaction formula is:

[0190]

[0191] Step 5: React the product obtained in Step 4 with acryloyl chloride under the condition that the pH is 9.5 - 10.5, and the reaction formula is:

[0192]

[0193] Step 6: At a temperature of 35 - 45 °C, the product obtained in Step 5 is subjected to low-temperature rotary evaporation under reduced pressure to remove the solvent, and the functional monomer S is obtained.

[0194] (4) After adjusting the temperature of the solution prepared in step (3) to 9 °C - 11 °C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 min to remove oxygen; after deoxygenation, add 0.25 parts of 2,2'-azobis(2-methylpropionamidine) dihydrochloride to the reaction kettle, add 0.18 parts of sodium persulfate after 6 min, and then add 0.18 parts of triethanolamine after another 6 min. Stop introducing nitrogen after the temperature of the system in the kettle starts to rise; when the reaction is completed and the temperature no longer rises, continue to cure for 3 h to obtain a polymer colloid.

[0195] (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75 °C for 6 h, then dry at 70 °C for 14 h, and then crush and screen to obtain particles with a particle size of 400 μm - 800 μm. This particle is the finished product of the multifunctional salt-resistant polymer.

[0196] Next, the performance of a multifunctional polymer for enhancing oil recovery according to the present invention is evaluated:

[0197] 1. Evaluation of antibacterial performance

[0198] The antibacterial performances of the multifunctional salt-resistant polymers prepared in the above Examples 1, 2, 3, 4, 5, and 6 and the common polymer are compared.

[0199] The test method is based on Part 5 of GB / T 14643.5 - 2009: MPN method for the determination of sulfate-reducing bacteria.

[0200] The test water is the produced sewage from a certain oil production plant, and the test time is 7 days.

[0201] (Table 1) Antibacterial effects of different examples in sewage

[0202] MPN Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Ordinary polymer 0 days 1 cell / ml 1 cell / ml 1 cell / ml 1 cell / ml 1 cell / ml 1 cell / ml 1 cell / ml 7 days 2 cells / ml 2 cells / ml 2 cells / ml 1 cell / ml 1 cell / ml 1 cell / ml 25421 cells / ml

[0203] Since microorganisms are unstable, precise experiments cannot be achieved. However, it can be proven from the above data that Examples 1-6 can effectively inhibit the reproduction of sulfate-reducing bacteria under sewage conditions, while the number of sulfate-reducing bacteria in the ordinary polymer control increases significantly. This shows that compared with ordinary polymers, the multifunctional salt-resistant polymer in the present invention has good antibacterial properties.

[0204] 2. Salt Resistance Performance Evaluation

[0205] The salt resistance performance of the multifunctional salt-resistant polymers prepared in Examples 1, 2, 3, 4, 5, and 6 above was compared with that of ordinary polymers.

[0206] The polymer concentration was 1000 mg / L, the detection temperature was 45 °C, and the detection instrument was a Brookfield viscometer. The viscosities of the test samples under different concentrations of sodium chloride solution were measured as shown in the following table:

[0207] (Table 2) Viscosities of Aqueous Polymer Solutions under Different Concentrations of NaCl

[0208]

[0209] From the data in the above table, it can be seen that Examples 1-6 can maintain a relatively high viscosity under different concentrations of sodium chloride solution, while the viscosity of the ordinary polymer decreases significantly. This shows that the multifunctional salt-resistant polymer in the present invention has good salt resistance performance.

[0210] 3. Molecular Weight Evaluation

[0211] The molecular weights of Examples 1-6 were measured using an Ubbelohde viscometer, and the molecular weight distribution is shown in the following table:

[0212] (Table 3) Molecular Weight Distribution

[0213] Multifunctional salt-resistant polymer Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[Molecular weight (×10 4 )]]> 1265 1378 1586 1711 1921 2124

[0214] From the data in the above table, it can be seen that the molecular weight distribution range of the multifunctional salt-resistant polymers in Examples 1-6 is between 12.5 million and 21 million, with a wide distribution range, and it is convenient for production through formulation adjustment.

[0215] 4. Oil Displacement Performance Evaluation

[0216] Oil Displacement Scheme: Artificial core φ2.5×10 cm, water flooding until the water cut reaches 98%, then switching to polymer flooding, and subsequent water flooding until the water cut reaches 98%. The displacement rate is 0.1 ml / min, the injection volume of chemical flooding is 0.6 pv, and the experimental temperature is 45 °C.

[0217] The polymers used in polymer flooding were the polymers of Examples 1-6 and ordinary medium molecular weight polymers, with a concentration of 1000 mg / L. The prepared polymer solution was placed in an environment at 45 °C for 7 days before the experiment.

[0218] The experimental water used is the produced sewage from an oil production plant. The following table shows the results of the oil displacement experiment:

[0219] (Table 4) Results of the oil displacement experiment

[0220]

[0221] As can be seen from the above table, in the oil displacement experiments of Examples 1 - 6 after being placed for 7 days, the polymer flooding recovery rates are all around 20%, which is much higher than that of ordinary polymers. This shows that after 7 days of injection, the multifunctional salt - resistant polymer still has a high oil displacement recovery rate and will not cause the polymer to be decomposed and its viscosity reduced by bacteria due to too long injection time, resulting in a decrease in the polymer flooding recovery rate.

[0222] 5. Evaluation of interfacial tension performance

[0223] The interfacial tension was measured by a TX500 type rotating drop interfacial tensiometer. The capillary was placed in the interfacial tensiometer, the temperature was adjusted to 55°C, and the rotation speed was 5000 r / min. The diameter of the oil drop was recorded at regular intervals. Generally, dynamic equilibrium was reached in 2 h and the interfacial tension value no longer changed. Finally, the size of the interfacial tension was calculated by computer software. The interfacial tension is shown in Table 5:

[0224] (Table 5) Results of interfacial tension

[0225] Multifunctional salt-resistant polymer Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Interfacial tension mN / m 0.00203 0.00206 0.00197 0.00178 0.00156 0.00267

[0226] From the data in Table 5, it can be seen that the interfacial tensions of the multifunctional salt - resistant polymers in Examples 1 - 6 can all reach the order of magnitude of 10 -3 mN / m. A lower interfacial tension is more conducive to driving the remaining oil in the reservoir by water flooding, thereby improving the recovery rate.

[0227] 6. Evaluation of emulsifying ability

[0228] The emulsifying abilities of the multifunctional salt - resistant polymers prepared in Examples 1, 2, 3, 4, 5 and 6 were compared with those of ordinary polymers.

[0229] A 5000 mg / L mother liquor was prepared with the clear water of the produced water sample from an oil production plant, and a 1000 mg / L target solution was prepared with the produced sewage from this oil production plant. It was mixed with the dehydrated crude oil from this oil production plant at a ratio of 1:1 and filled into a 25 - ml colorimetric tube. After preheating at 45°C, it was shaken manually 300 times and then placed in a 45°C water bath for 1 hour, and then the water separation rate was observed and calculated.

[0230] (Table 6) Results of the emulsification experiment

[0231]

[0232]

[0233] As can be seen from the above table, after emulsification for 1 hour in Examples 1-6, the water separation rate is all below 5%. Compared with ordinary polymers, they have excellent emulsifying ability and can more easily drive out the remaining oil in rock pores, thereby improving the recovery rate.

Claims

1. A multifunctional polymer for enhancing oil recovery, characterized in that: The multifunctional polymer is a multifunctional salt-resistant polymer. The components and parts by weight of the multifunctional salt-resistant polymer are as follows: 240 to 280 parts of acrylamide; 15 to 30 parts of AMPS; 6 to 15 parts of NNO; 10 to 40 parts of functional monomer S; 6 to 9 parts of urea; 0.2 to 0.25 parts of Initiator 1; 0.06 to 0.18 parts of Initiator 2; 0.06 to 0.18 parts of Initiator 3; 720 to 760 parts of water.

2. The multifunctional polymer for enhancing oil recovery according to claim 1, wherein: The Initiator 1 is one or more of azobisisobutyronitrile, azobisisoheptonitrile or azobisisobutylamidine hydrochloride.

3. The multifunctional polymer for improving oil recovery according to claim 1, characterized in that: The Initiator 2 is one or more of ammonium persulfate, potassium persulfate or sodium persulfate.

4. A multifunctional polymer for improving oil recovery according to claim 1, characterized in that: The Initiator 3 is one or more of sodium bisulfite, sodium thiosulfate or triethanolamine.

5. A multifunctional polymer for enhancing oil recovery according to claim 1, characterized in that: The molecular formula of the functional monomer S is:

6. The multifunctional polymer for enhancing oil recovery according to claim 5, characterized in that: The preparation method of the functional monomer S includes the following steps: Step 1: Add the solvent DMF into the reaction kettle, and then add dehydroabietylamine, whose molecular formula is: Add excessive isobutene, heat the reaction kettle to 90 °C, put potassium carbonate as a catalyst into the reaction kettle, and after reacting for 4 h, rotary evaporate the solvent under reduced pressure at 35 °C. The reaction formula is: Step 2: React the product obtained in Step 1 with a mixed acid of nitric acid and sulfuric acid under the condition of a temperature of 0 - 5 °C. The reaction formula is: Step 3: React the product obtained in Step 2 with: Add EDC, and carry out the reaction in the reaction kettle. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is: Step 4: Put the product obtained in Step 3 into a closed container, add ammonium sulfide under nitrogen protection and stir to reduce the nitro group to an amino group. Add hydroquinone to prevent polymerization during the reaction. The reaction formula is: Step 5: React the product obtained in Step 4 with acryloyl chloride in a three-necked flask under the condition of a pH of 9.5 - 10.

5. The reaction formula is: Step 6: After the product obtained in Step 5 is rotary evaporated under reduced pressure at a low temperature to remove the solvent at a temperature of 35 - 45 °C, the functional monomer S is obtained.

7. A method for preparing a multifunctional polymer for enhancing oil recovery according to claim 1, characterized in that: The preparation method includes the following steps: (1) Mix the functional monomer S and NNO and set aside; (2) Dissolve AMPS with ice water and neutralize it with sodium hydroxide; (3) Add acrylamide and the monomers prepared in steps (1) and (2) to urea and water, stir and mix evenly, and adjust the pH value with 10% sodium hydroxide solution to a pH value of 6.9 - 7.1; (4) After adjusting the temperature of the solution prepared in step (3) to 9 °C - 11 °C, transfer the solution to an adiabatic reaction kettle, and then introduce nitrogen for 30 min to remove oxygen; after deoxygenation, add Initiator 1 to the reaction kettle, add Initiator 2 after 6 min, and then add Initiator 3 after another 6 min. Stop introducing nitrogen after the temperature of the system in the kettle starts to rise; when the reaction is completed and the temperature no longer rises, continue to cure for 3 h to obtain a polymer colloid; (5) Crush the polymer colloid obtained in step (4), add solid sodium hydroxide, mix well, hydrolyze at 75 °C for 6 h, then dry at 70 °C for 14 h, and then crush and screen to obtain particles with a particle size of 400 μm - 800 μm. This particle is the finished product of the multifunctional salt-resistant polymer.

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