Copolymer oil-displacing agent containing modified polyether amine macromonomer and preparation method of copolymer oil-displacing agent

Abstract

The invention provides a copolymer oil-displacing agent containing a modified polyether amine macromonomer and a preparation method thereof, and belongs to the field of oilfield chemistry, the preparation method comprises the following steps: adding p-chlorobenzaldehyde and polyether monoamine which are equimolar into ethanol, stirring at room temperature, and carrying out Schiff base reaction to obtain an intermediate product solution; adding N-(3-dimethylaminopropyl) methacrylamide of which the mole is equal to that of p-chlorobenzaldehyde into the intermediate product solution, carrying out quaternization reaction, and carrying out rotary evaporation on ethanol to remove the ethanol, so as to obtain a modified polyether amine macromonomer; and polymerizing the modified polyether amine macromonomer and acrylamide, and crushing, hydrolyzing and drying a polymerization product to obtain the hydrophobic modified polyacrylamide containing the polyether amine structural unit. The oil-displacing agent has good temperature resistance and salt resistance, and can be used for preparing a polymer solution by taking seawater as a solvent.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield chemistry, especially the technical field of polymer flooding, and specifically provides a copolymer flooding agent containing a modified polyetheramine macromonomer and a preparation method thereof. Background Art

[0002] Polymer flooding is one of the important methods for improving oil recovery in oilfields. The main principle of polymer flooding to improve oil recovery is to inject a high-viscosity polymer aqueous solution into the formation, reduce the mobility ratio between crude oil and injected water, expand the swept area, and thus improve the oil recovery.

[0003] At present, fresh water resources are scarce around some offshore oilfields. If polymer flooding is carried out, it is necessary to select seawater as the solvent to prepare the polymer solution. Seawater has a high salinity (greater than 30,000 mg / L) and high calcium and magnesium ion concentrations (calcium ion concentration greater than 350 mg / L, magnesium ion concentration greater than 1100 mg / L). The commonly used polymer flooding agent - linear partially hydrolyzed polyacrylamide (HPAM) - cannot be applied due to poor salt resistance (poor thickening effect). In addition, as the burial depth of offshore oilfields increases, the reservoir temperature is also getting higher. Therefore, there is an urgent need to develop a polymer flooding agent that can adapt to the characteristics of seawater and has high temperature resistance. Usually, the method to improve the salt and temperature resistance of linear HPAM is to introduce hydrophobic monomers. Summary of the Invention

[0004] In order to solve at least one of the above problems, the purpose of the present invention is to provide a copolymer flooding agent containing a modified polyetheramine macromonomer and a preparation method thereof. The present invention synthesizes a new type of hydrophobic monomer from polyether monoamine, and the hydrophobicity of this hydrophobic monomer increases with the increase of temperature, which can effectively enhance the high temperature resistance of the modified HPAM.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A copolymer flooding agent containing a modified polyetheramine macromonomer, comprising the following steps:

[0007] S1. Add equimolar p-chlorobenzaldehyde and polyether monoamine to ethanol, stir at room temperature to carry out the Schiff base reaction to obtain an intermediate product solution; add N-(3-dimethylaminopropyl) methacrylamide equimolar to p-chlorobenzaldehyde to the intermediate product solution for quaternization reaction, and remove the ethanol by rotary evaporation to obtain the modified polyetheramine macromonomer; the polyether monoamine is a block copolymer composed of propylene oxide and ethylene oxide;

[0008] S2. Dissolve the modified polyetheramine macromonomer and acrylamide in deionized water, cool down to 4 - 6 °C, and pour it into an adiabatic reactor; introduce nitrogen into the reactor to remove oxygen, then sequentially add sodium bisulfite, potassium persulfate, and V044; continuously introduce nitrogen until obvious drawing phenomenon occurs in the reaction solution, seal the reactor, and carry out polymerization reaction until the system temperature no longer rises to obtain a polymer rubber block; crush the polymer rubber block, add sodium hydroxide solution and mix evenly, and carry out hydrolysis reaction at 75 - 85 °C for 3.8 - 4.2 h; dry and crush to obtain a hydrophobic modified polyacrylamide containing polyetheramine structural units.

[0009] As a specific implementation mode of the present invention, in step S1, the polyether monoamine is one of M - 1000, M - 2005, M - 2070, or M3085 of Huntsman Corporation.

[0010] One implementation mode of the present invention lies in that in step S2, the addition amount of the modified polyetheramine macromonomer accounts for 0.1% - 0.4% of the mass of acrylamide.

[0011] One implementation mode of the present invention lies in that in step S2, the mass fraction of acrylamide is 18% - 23%.

[0012] One implementation mode of the present invention lies in that in step S2, the addition amounts of potassium persulfate and sodium bisulfite are 10 mg / L - 36 mg / L.

[0013] One implementation mode of the present invention lies in that in step S2, the addition amount of V044 is 20 mg / L - 30 mg / L.

[0014] One implementation mode of the present invention lies in that in step S2, the mass fraction of sodium hydroxide in the polymer rubber block is 2% - 3%.

[0015] In addition, the present invention also discloses that after a hydrophobic modified polyacrylamide displacing agent containing polyetheramine structural units prepared according to the above - mentioned implementation mode is dissolved in seawater, it has good temperature resistance, and its seawater solution can effectively improve the crude oil recovery rate.

[0016] Compared with the existing polymer displacing agents, the technical effects of the present invention are:

[0017] In seawater, the hydrophobic modified polyacrylamide displacing agent containing polyetheramine structural units of the present invention has better temperature resistance than linear high - molecular - weight partially hydrolyzed polyacrylamide and common hydrophobic modified polyacrylamide. Description of the Drawings

[0018] Figure 1 It is the infrared spectrum of the modified polyetheramine macromonomer for Example 2;

[0019] Figure 2It is a record chart of the injection pressure and crude oil recovery rate during the oil displacement experiment. Specific implementation mode

[0020] The following will clearly and completely describe the specific implementation mode of the present invention in combination with examples. Obviously, the described examples are only a part of the embodiments of the present invention, rather than all the embodiments.

[0021] Example 1

[0022] S1) Add 14 g (0.1 mol) of p-chlorobenzaldehyde and 100 g (0.1 mol) of polyether monoamine M-1000 to 228 g of ethanol, stir and react at room temperature for 12 h to obtain an intermediate product solution; add 17 g (0.1 mol) of N-(3-dimethylaminopropyl) methacrylamide to the intermediate product solution, heat up to 70 °C and react for 12 h, and remove the ethanol by rotary evaporation to obtain a modified polyetheramine macromonomer.

[0023] S2) Add 105 g of acrylamide and 0.21 g of the modified polyetheramine macromonomer to a 1 L beaker, make up the water to 500 g, and cool to 5 °C after stirring and dissolving; transfer the 5 °C solution to an adiabatic reaction device, pass high-purity nitrogen for 30 min, and then sequentially add 30 mg / L of potassium persulfate, 30 mg / L of sodium bisulfite and 20 mg / L of V0-44. Stop passing nitrogen after there is an obvious wire-drawing phenomenon in the reaction system, and seal the adiabatic reactor; record the reaction temperature in real time through a temperature recorder. When the reaction temperature no longer rises, end the polymerization to obtain 500 g of polymer gel blocks; crush the polymer gel into particles, add 29.6 g of sodium hydroxide solution (sodium hydroxide concentration is 40%) and mix evenly, hydrolyze at 80 °C for 4 h, dry and crush to obtain a hydrophobic modified polyacrylamide powder containing polyetheramine structural units.

[0024] Example 2

[0025] The basic implementation mode of this example is the same as that of Example 1, and the difference is that the polyether monoamine added in S1 of this example is 200 g (0.1 mol) of M-2005, and the ethanol is 428 g.

[0026] Example 3

[0027] The basic implementation mode of this example is the same as that of Example 1, and the difference is that the polyether monoamine added in S1 of this example is 200 g (0.1 mol) of M-2070, and the ethanol is 428 g.

[0028] Example 4

[0029] The basic implementation mode of this example is the same as that of Example 1, and the difference is that the polyether monoamine added in S1 of this example is 200 g (0.1 mol) of M-3085, and the ethanol is 428 g.

[0030] Example 5

[0031] The basic implementation of this example is the same as that of Example 2, except that the mass of the modified polyetheramine macromonomer added at S2 in this example is 0.105 g.

[0032] Example 6

[0033] The basic implementation of this example is the same as that of Example 2, except that the mass of the modified polyetheramine macromonomer added at S2 in this example is 0.315 g.

[0034] Example 7

[0035] The basic implementation of this example is the same as that of Example 2, except that the mass of the modified polyetheramine macromonomer added at S2 in this example is 0.420 g.

[0036] Example 8

[0037] The basic implementation of this example is the same as that of Example 2, except that the mass of the modified polyetheramine macromonomer added at S2 in this example is 0.525 g.

[0038] Example 9

[0039] The basic implementation of this example is the same as that of Example 2, except that the addition amount of acrylamide at S2 in this example is 90 g and the addition amount of the modified polyetheramine macromonomer is 0.18 g.

[0040] Example 10

[0041] The basic implementation of this example is the same as that of Example 2, except that the addition amount of acrylamide at S2 in this example is 100 g and the addition amount of the modified polyetheramine macromonomer is 0.2 g.

[0042] Example 11

[0043] The basic implementation of this example is the same as that of Example 2, except that the addition amount of acrylamide at S2 in this example is 115 g and the addition amount of the modified polyetheramine macromonomer is 0.23 g.

[0044] Example 12

[0045] The basic implementation of this example is the same as that of Example 2, except that the addition amount of acrylamide at S2 in this example is 125 g and the addition amount of the modified polyetheramine macromonomer is 0.25 g.

[0046] Example 13

[0047] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amounts of potassium persulfate and sodium bisulfite at S2 are both 10 mg / L.

[0048] Example 14

[0049] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amounts of potassium persulfate and sodium bisulfite at S2 are both 20 mg / L.

[0050] Example 15

[0051] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amounts of potassium persulfate and sodium bisulfite at S2 are both 36 mg / L.

[0052] Example 16

[0053] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amounts of potassium persulfate and sodium bisulfite at S2 are both 40 mg / L.

[0054] Example 17

[0055] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amount of V044 at S2 is 25 mg / L.

[0056] Example 18

[0057] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amount of V044 at S2 is 30 mg / L.

[0058] Example 19

[0059] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, the addition amount of V044 at S2 is 35 mg / L.

[0060] Example 20

[0061] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, 26.6 g of sodium hydroxide solution (sodium hydroxide mass concentration is 40%) is added at S2.

[0062] Example 21

[0063] The basic implementation method of this embodiment is the same as that of Embodiment 2, and the difference is that in this embodiment, 32.5 g of sodium hydroxide solution (sodium hydroxide mass concentration is 40%) is added at S2.

[0064] Example 22

[0065] The basic implementation of this example is the same as that of Example 2, except that 37.0 g of sodium hydroxide solution (sodium hydroxide mass concentration is 40%) is added at S2 in this example.

[0066] To further illustrate the technical effects of the present invention, the present invention also gives relevant tests of the above-mentioned various examples in practical applications.

[0067] (1) Infrared spectrum of modified polyetheramine macromonomer

[0068] Select the modified polyetheramine macromonomer in Example 2 for infrared characterization, and the results are shown in Figure 1 . In the figure, 3454 cm-1 is the characteristic absorption peak of imide (from N-(3-dimethylaminopropyl) methacrylamide), 2956 cm-1 and 1351 cm-1 are the characteristic absorption peaks of -CH3-, 2918 cm-1, 2850 cm-1 and 1468 cm-1 are the characteristic absorption peaks of -CH2-, 1649 cm-1 is the characteristic absorption peak of imine bond and double bond, and 1100 cm-1 is the characteristic absorption peak of ether bond (from polyetheramine). The infrared characterization results show that the modified polyetheramine macromonomer has been successfully synthesized.

[0069] (2) Viscosity measurement and temperature resistance evaluation method of polymer solution

[0070] Using simulated seawater (the ionic composition of seawater is shown in Table 1) as the solvent, prepare a polymer flooding agent solution with a concentration of 2000 mg / L. Use a Brookfield viscometer to measure the apparent viscosity of the polymer solution at 60 °C and 90 °C under the conditions of 0# and 6 rpm, and calculate the viscosity retention rate Vr of the polymer solution when rising from 60 °C to 90 °C. Vr = (h 60 -h 90 ) / h 60 ×100%.

[0071] Table 1 Ionic composition of seawater

[0072] Ions (mg / L) <![CDATA[Na + > <![CDATA[K + > <![CDATA[Ca 2+ > <![CDATA[Mg 2+ > <![CDATA[Cl - > <![CDATA[HCO 3 - > <![CDATA[SO 4 2- > Total salinity Seawater 10052.08 105.95 366.88 1172.08 17588.09 153.25 2691 32179

[0073] (3) Performance comparison of hydrophobically modified polyacrylamide containing polyetheramine structural unit with other polymers

[0074] The high molecular weight partially hydrolyzed polyacrylamide 3640C of SNF Company (comparison sample 1) and the hydrophobically modified polyacrylamide of Qingdao Haibo Chemical Co., Ltd. (comparison sample 2) were used as comparison samples to compare the temperature resistance of the hydrophobically modified polyacrylamide containing polyetheramine structural units with the two. The experimental results are shown in Table 2. It can be seen from Table 2 that the hydrophobically modified polyacrylamide containing polyetheramine structural units has good temperature resistance, and its viscosity retention rate is much higher than that of the comparison samples when the temperature rises by 30 °C. This is because the block polyether in the polyetheramine has a certain temperature sensitivity. As the temperature rises, its hydrophobicity increases and the intermolecular association is enhanced, overcoming the significant decrease in viscosity caused by the curling of the molecular chain due to the increase in temperature.

[0075] Table 2 Comparison results of the properties of the hydrophobically modified polyacrylamide containing polyetheramine structural units and other polymers

[0076]

[0077] (4) Influence of the dosage of the modified polyetheramine macromonomer on the performance of the copolymer flooding agent

[0078] The influence results of the dosage of the modified polyetheramine macromonomer on the performance of the copolymer flooding agent are shown in Table 3. It can be seen from the table that as the dosage of the modified polyetheramine macromonomer increases, the viscosity of the copolymer solution increases. However, when its dosage is 0.5%, due to the too strong intermolecular association, the product is difficult to dissolve in water. Therefore, it is recommended that the dosage of the modified polyetheramine macromonomer be 0.1% - 0.4%.

[0079] Table 3 Evaluation results of the influence of the dosage of the modified polyetheramine macromonomer on the performance of the copolymer flooding agent

[0080]

[0081] (5) Influence of the acrylamide concentration on the performance of the copolymer flooding agent

[0082] The influence results of the acrylamide concentration on the performance of the copolymer flooding agent are shown in Table 4. It can be seen from the table that as the modified acrylamide increases, the molecular weight of the product increases and the viscosity of the copolymer solution increases. The viscosity retention rate first increases and then remains basically unchanged. However, when the acrylamide concentration is 25%, the product is difficult to dissolve in water. Therefore, it is recommended that the acrylamide concentration be 18% - 23%.

[0083] Table 4 Evaluation results of the influence of the acrylamide concentration on the performance of the copolymer flooding agent

[0084]

[0085] (6) Influence of the dosage of the redox initiator on the performance of the copolymer flooding agent

[0086] The results of the effect of the dosage of redox initiator on the properties of the copolymer flooding agent are shown in Table 5. It can be seen from the table that as the dosage of redox initiator increases, the molecular weight of the product first increases and then decreases, and thus the viscosity of the copolymer solution first increases and then decreases. The viscosity retention rate first increases and then slightly decreases. When the dosage of redox initiator is 40 / 40 mg / L, chain transfer between polymer molecular chains is likely to occur when the initiator dosage is too large, resulting in cross-linking of molecular chains and making the product difficult to dissolve in water. Therefore, the recommended dosage of redox initiator is 10 mg / L - 36 mg / L.

[0087] Table 5 Evaluation results of the effect of the dosage of redox initiator on the properties of the copolymer flooding agent

[0088]

[0089] (7) Effect of the dosage of azo initiator V044 on the properties of the copolymer flooding agent

[0090] The results of the effect of the dosage of azo initiator V044 on the properties of the copolymer flooding agent are shown in Table 6. It can be seen from the table that as the dosage of V044 increases, the molecular weight of the product also first increases and then decreases, and thus the viscosity of the copolymer solution first increases and then decreases. The viscosity retention rate first increases and then decreases. When the dosage of V044 is 35 mg / L, chain transfer between polymer molecular chains is likely to occur when the initiator dosage is too large, resulting in cross-linking of molecular chains and making the product difficult to dissolve in water. Therefore, the recommended dosage of V044 is in the range of 20 - 30 mg / L.

[0091] Table 6 Evaluation results of the effect of the dosage of redox initiator on the properties of the copolymer flooding agent

[0092]

[0093] (8) Effect of hydrolysis degree (NaOH dosage) on the properties of the copolymer flooding agent

[0094] Changing the dosage of NaOH can change the hydrolysis degree of the copolymer. The results of the effect of hydrolysis degree on the properties of the copolymer flooding agent are shown in Table 7. It can be seen from the table that as the hydrolysis degree increases, the viscosity of the copolymer solution first increases and then decreases, and the viscosity retention rate also first increases and then decreases. An appropriate hydrolysis degree can keep the copolymer molecular chains in an extended state in seawater, which is beneficial to the formation of intermolecular association and thus has a higher viscosity and a higher viscosity retention rate. When the hydrolysis degree is too low, the molecular chains are curled and the viscosity is small. When the hydrolysis degree is too high, the molecular chains have poor salt resistance and the viscosity is also small.

[0095] In addition, it can be seen from the table that the temperature resistance of the polymer prepared in this patent is much higher than that of Comparative Example 1.

[0096] Table 7 Evaluation results of the effect of hydrolysis degree on the properties of the copolymer flooding agent

[0097]

[0098] Note: Comparative Example 1 was prepared by referring to Example 1 of Patent CN118546293A "A Modified Polyacrylamide Containing Degradable Hydrophobic Monomers and Its Preparation Method".

[0099] (8) Evaluation of the Oil Displacement Performance of the Copolymer Oil Displacement Agent

[0100] Using seawater (properties are shown in Table 1) as the solvent, a copolymer solution obtained in Example 2 with a concentration of 2000 mg / L was prepared. An artificial core with a gas permeability of 1200 mD at 90 °C was used to conduct an oil displacement experiment according to the experimental method described in the Petroleum and Natural Gas Industry Standard SY / T 5862 - 2020 of the People's Republic of China. The records of pressure and oil recovery rate during the experiment are shown in Figure 2 . As can be seen from the figure, the oil recovery rate of polymer flooding is 7.6%, the subsequent water flooding oil recovery rate is 20.25%, and the total enhanced oil recovery rate is 27.85%. The copolymer has good oil displacement performance.

[0101] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing a copolymer oil-displacing agent containing a modified polyetheramine macromonomer, characterized in that: The steps include: S1, adding equimolar p-chlorobenzaldehyde and polyether monoamine to ethanol, stirring at room temperature to carry out Schiff base reaction to obtain an intermediate product solution; adding N-(3-dimethylaminopropyl) methacrylamide in an amount equimolar to p-chlorobenzaldehyde to the intermediate product solution to carry out quaternization reaction, and removing ethanol by rotary evaporation to obtain a modified polyether amine macromonomer; the polyether monoamine is a block copolymer composed of propylene oxide and ethylene oxide; S2. Dissolve the modified polyetheramine macromonomer and acrylamide in deionized water, cool to 4-6°C, and pour into an adiabatic reactor; introduce nitrogen into the reactor to deoxygenate, and then add sodium bisulfite, potassium persulfate and V044 in sequence; continue to introduce nitrogen until the reaction liquid has obvious wire drawing phenomenon, seal the reactor, and carry out polymerization reaction until the system temperature no longer rises to obtain a polymer block; crush the polymer block, add sodium hydroxide solution and mix evenly, and hydrolyze at 75-85°C for 3.8-4.2h; dry and crush to obtain a hydrophobically modified polyacrylamide containing a polyetheramine structural unit.

2. The method for preparing the copolymer oil-displacing agent containing modified polyetheramine macromonomer according to claim 1, characterized in that: In step S1, the polyether monoamine is one of M-1000, M-2005, M-2070 or M3085 produced by Huntsman. The method for preparing a copolymer oil-displacing agent containing a modified polyetheramine macromonomer according to claim 1, characterized in that the mass fraction of the modified polyetheramine macromonomer added in step S2 is 0.1%-0.4% of the mass fraction of acrylamide.

3. The method for preparing the copolymer oil-displacing agent containing modified polyetheramine macromonomer according to claim 1, characterized in that: The mass fraction of acrylamide in step S2 is 18%-23%.

4. The method for preparing the copolymer oil-displacing agent containing modified polyetheramine macromonomer according to claim 1, characterized in that: In step S2, the amount of potassium persulfate and sodium bisulfite added is 10 mg / L-36 mg / L.

5. The method for preparing a copolymer oil-displacing agent containing a modified polyetheramine macromonomer according to claim 1, characterized in that: The amount of V044 added in step S2 is 20 mg / L-30 mg / L.

6. The method for preparing the copolymer oil-displacing agent containing modified polyetheramine macromonomer according to claim 1, characterized in that: In step S2, the mass fraction of sodium hydroxide in the polymer block is 2%-3%.

7. A copolymer oil-displacing agent containing a modified polyetheramine macromonomer, characterized in that: The copolymer oil-displacing agent containing modified polyetheramine macromonomer is prepared by the preparation method of any one of claims 1 to 6.

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