A copolymer oil displacement agent containing a modified polyether amine macromonomer and a method for preparing the same

Abstract

The application provides a modified polyether amine macromonomer-containing copolymer oil displacement agent and a preparation method thereof, and belongs to the field of oil field chemistry.The preparation method comprises the following steps: adding equimolar p-chlorobenzaldehyde and polyether monoamine into ethanol, stirring at room temperature to perform Schiff base reaction to obtain an intermediate product solution; adding N-(3-dimethylaminopropyl) methacrylamide which is equimolar with the p-chlorobenzaldehyde into the intermediate product solution to perform quaternary ammonium reaction, and removing ethanol by rotary evaporation to obtain a modified polyether amine macromonomer; polymerizing the modified polyether amine macromonomer with acrylamide, and crushing, hydrolyzing and drying the polymerization product to obtain a hydrophobically modified polyacrylamide containing a polyether amine structural unit.The oil displacement agent has good temperature resistance and salt resistance, and can be used to configure a polymer solution by using seawater as a solvent.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, particularly to the field of polymer flooding technology, specifically to a copolymer flooding agent containing modified polyetheramine macromonomers and its preparation method. Background Technology

[0002] Polymer flooding is one of the important methods for enhancing oil recovery in oilfields. The main principle of polymer flooding for enhancing oil recovery is to inject a high-viscosity polymer aqueous solution into the formation, thereby reducing the mobility ratio between crude oil and injected water, expanding the sweep range, and thus improving the oil recovery rate.

[0003] Currently, freshwater resources are scarce around some offshore oil fields. If polymer flooding is to be carried out, seawater must be used as a solvent to prepare the polymer solution. Seawater has 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). Commonly used polymer flooding agents—linear partially hydrolyzed polyacrylamide (HPAM)—are unsuitable due to poor salt resistance (poor viscosity-enhancing effect). Furthermore, as offshore oil fields deepen, reservoir temperatures are increasing. Therefore, there is an urgent need to develop polymer flooding agents that can adapt to seawater characteristics and withstand higher temperatures. A common method to improve the salt and temperature resistance of linear HPAM is to introduce hydrophobic monomers. Summary of the Invention

[0004] To address at least one of the aforementioned problems, the present invention aims to provide a copolymer oil displacement agent containing modified polyetheramine macromonomers and its preparation method. The present invention synthesizes a novel hydrophobic monomer using polyether monoamine as a raw material. The hydrophobicity of this hydrophobic monomer increases with increasing temperature, which can effectively enhance the temperature resistance of its modified HPAM.

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

[0006] An oil displacement agent containing a modified polyetheramine macromonomer, comprising the following steps:

[0007] S1. Equimolar amounts of p-chlorobenzaldehyde and polyether monoamine were added to ethanol, and a Schiff base reaction was carried out under stirring at room temperature to obtain an intermediate product solution. An equimolar amount of N-(3-dimethylaminopropyl)methacrylamide was added to the intermediate product solution to carry out a quaternization reaction. The ethanol was removed by rotary evaporation to obtain the modified polyether amine macromonomer. The polyether monoamine was a block copolymer composed of propylene oxide and ethylene oxide.

[0008] S2. Dissolve the modified polyetheramine macromonomer and acrylamide in deionized water, cool to 4-6℃, and pour into an adiabatic reactor; introduce nitrogen gas into the reactor to remove oxygen, and then add sodium bisulfite, potassium persulfate, and VO44 in sequence; continue to introduce nitrogen gas until the reaction solution exhibits obvious stringing, seal the reactor, and polymerize until the system temperature no longer rises, obtaining a polymer block; crush the polymer block and add sodium hydroxide solution to mix evenly, and hydrolyze at 75-85℃ for 3.8-4.2 hours; dry and crush to obtain hydrophobic modified polyacrylamide containing polyetheramine structural units.

[0009] In one specific embodiment of the present invention, the polyether monoamine in step S1 is one of Huntsman's M-1000, M-2005, M-2070 or M3085.

[0010] In one embodiment of the present invention, the modified polyetheramine macromonomer added in step S2 accounts for 0.1%-0.4% of the mass fraction of acrylamide.

[0011] In one embodiment of the present invention, the mass fraction of acrylamide in step S2 is 18%-23%.

[0012] In one embodiment of the present invention, the amount of potassium persulfate and sodium bisulfite added in step S2 is 10 mg / L-36 mg / L.

[0013] In one embodiment of the present invention, the amount of VO44 added in step S2 is 20 mg / L-30 mg / L.

[0014] In one embodiment of the present invention, sodium hydroxide accounts for 2%-3% of the mass fraction of the polymer block in step S2.

[0015] Furthermore, this invention also discloses a hydrophobically modified polyacrylamide oil displacement agent containing polyetheramine structural units prepared according to the above embodiments. After dissolving in seawater, it exhibits good temperature resistance, and its seawater solution can effectively improve crude oil recovery rate.

[0016] Compared with existing polymer flooding agents, the technical advantages of this invention are:

[0017] In seawater, the hydrophobically modified polyacrylamide oil displacement agent containing polyetheramine structural units of the present invention exhibits better temperature resistance than linear high molecular weight partially hydrolyzed polyacrylamide and common hydrophobically modified polyacrylamide. Attached Figure Description

[0018] Figure 1 The infrared spectrum of the modified polyetheramine macromonomer in Example 2;

[0019] Figure 2A graph showing the injection pressure and crude oil recovery rate during the oil displacement experiment. Detailed Implementation

[0020] The specific embodiments of the present invention will be clearly and completely described below with reference to examples. Obviously, the described examples are only some embodiments of the present invention, and not all embodiments.

[0021] Example 1

[0022] S1) 14g (0.1mol) of p-chlorobenzaldehyde and 100g (0.1mol) of polyether monoamine M-1000 were added to 228g of ethanol and stirred at room temperature for 12h to obtain an intermediate product solution; 17g (0.1mol) of N-(3-dimethylaminopropyl)methacrylamide was added to the intermediate product solution, the temperature was raised to 70℃ and reacted for 12h, and the ethanol was removed by rotary evaporation to obtain the modified polyether amine macromonomer.

[0023] S2) Add 105g of acrylamide and 0.21g of modified polyetheramine macromonomer to a 1L beaker, add water to 500g, and after stirring and dissolving, cool to 5℃; transfer the 5℃ solution to an adiabatic reaction apparatus and purge with high-purity nitrogen for 30min, then add 30mg / L potassium persulfate, 30mg / L sodium bisulfite and 20mg / L V0-44 in sequence. After the reaction system shows obvious stringing, stop purging with nitrogen and seal the adiabatic reactor; record the reaction temperature in real time with a temperature recorder, and stop the polymerization when the reaction temperature no longer rises to obtain 500g of polymer block; grind the polymer gel into granules, add 29.6g of sodium hydroxide solution (sodium hydroxide concentration is 40%) and mix evenly, hydrolyze at 80℃ for 4h, dry and pulverize to obtain hydrophobic modified polyacrylamide powder containing polyetheramine structural units.

[0024] Example 2

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

[0026] Example 3

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

[0028] Example 4

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

[0030] Example 5

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

[0032] Example 6

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

[0034] Example 7

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

[0036] Example 8

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

[0038] Example 9

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

[0040] Example 10

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

[0042] Example 11

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

[0044] Example 12

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

[0046] Example 13

[0047] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the amount of potassium persulfate and sodium bisulfite added in S2 of this embodiment is 10 mg / L.

[0048] Example 14

[0049] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the dosage of potassium persulfate and sodium bisulfite added in S2 of this embodiment is 20 mg / L.

[0050] Example 15

[0051] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the dosage of potassium persulfate and sodium bisulfite added in S2 of this embodiment is 36 mg / L.

[0052] Example 16

[0053] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the dosage of potassium persulfate and sodium bisulfite added in S2 of this embodiment is 40 mg / L.

[0054] Example 17

[0055] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the amount of VO44 added in S2 of this embodiment is 25 mg / L.

[0056] Example 18

[0057] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the amount of VO44 added in S2 of this embodiment is 30 mg / L.

[0058] Example 19

[0059] The basic implementation method of this embodiment is the same as that of embodiment 2, except that the amount of VO44 added in S2 of this embodiment is 35 mg / L.

[0060] Example 20

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

[0062] Example 21

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

[0064] Example 22

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

[0066] To further illustrate the technical effects of the present invention, the present invention also provides relevant tests of the above embodiments in practical applications.

[0067] (1) Infrared spectra of modified polyetheramine macromonomers

[0068] The modified polyetheramine macromonomer from Example 2 was selected for infrared characterization, and the results are shown in [Figure 1]. 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 characteristic absorption peaks of -CH₃⁻, 2918 cm⁻¹, 2850 cm⁻¹ and 1468 cm⁻¹ are 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 indicate that the modified polyetheramine macromonomer has been successfully synthesized.

[0069] (2) Methods for determining the viscosity and evaluating the temperature resistance of polymer solutions

[0070] A polymer displacement agent solution with a concentration of 2000 mg / L was prepared using simulated seawater (ionic composition of seawater is shown in Table 1) as the solvent. The apparent viscosity of the polymer solution at 60℃ and 90℃ was measured using a Brookfield viscometer (0#, 6 rpm). The viscosity retention rate (Vr) of the polymer solution when the temperature rises from 60℃ to 90℃ was calculated. 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[HCO3 - ]]> <![CDATA[SO4 2- ]]> Total mineralization 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 units with other polymers

[0074] High molecular weight partially hydrolyzed polyacrylamide 3640C from SNF Corporation (comparative sample 1) and hydrophobically modified polyacrylamide from Qingdao Haibo Chemical Co., Ltd. (comparative sample 2) were used as comparative samples to compare the temperature resistance of the hydrophobically modified polyacrylamide containing polyetheramine structural units with the two other samples. The experimental results are shown in Table 2. Table 2 shows that the hydrophobically modified polyacrylamide containing polyetheramine structural units exhibits good temperature resistance; its viscosity retention rate is significantly higher than that of the comparative sample when the temperature increases by 30℃. This is because the block polyether in the polyetheramine has a certain degree of temperature sensitivity; its hydrophobicity increases with temperature, and the enhanced intermolecular association overcomes the significant decrease in viscosity caused by the coiling of molecular chains at higher temperatures.

[0075] Table 2. Performance comparison of hydrophobically modified polyacrylamide containing polyetheramine structural units with other polymers.

[0076]

[0077] (4) Effect of modified polyetheramine macromonomer dosage on the performance of copolymer oil displacement agent

[0078] The effect of modified polyetheramine macromonomer dosage on the performance of the copolymer oil displacement agent is shown in Table 3. As can be seen from the table, the viscosity of the copolymer solution increases with increasing modified polyetheramine macromonomer dosage. However, when the dosage is 0.5%, the product is difficult to dissolve in water due to excessively strong intermolecular association. Therefore, a modified polyetheramine macromonomer dosage of 0.1%-0.4% is recommended.

[0079] Table 3 Evaluation results of the effect of modified polyetheramine macromonomer dosage on the performance of copolymer oil displacement agent

[0080]

[0081] (5) Effect of acrylamide concentration on the performance of copolymer oil displacement agent

[0082] The effect of acrylamide concentration on the performance of the copolymer oil displacement agent is shown in Table 4. As the table shows, with increasing acrylamide content, the molecular weight of the product increases, and the viscosity of the copolymer solution increases. The viscosity initially increases and then remains relatively constant; however, when the acrylamide concentration is 25%, the product is difficult to dissolve in water. Therefore, an acrylamide concentration of 18%-23% is recommended.

[0083] Table 4. Evaluation results of the effect of acrylamide concentration on the performance of copolymer oil displacement agents.

[0084]

[0085] (6) Effect of redox initiator dosage on the performance of copolymer oil displacement agent

[0086] The effect of redox initiator dosage on the performance of the copolymer oil displacement agent is shown in Table 5. As the table shows, with increasing redox initiator dosage, the molecular weight of the product first increases and then decreases, resulting in a corresponding increase and decrease in the viscosity of the copolymer solution. The viscosity retention initially increases and then slightly decreases. When the redox initiator dosage is 40 / 40 mg / L, excessive initiator dosage easily leads to chain transfer between polymer molecular chains, resulting in molecular chain cross-linking and making the product difficult to dissolve in water. Therefore, a redox initiator dosage of 10 mg / L–36 mg / L is recommended.

[0087] Table 5. Evaluation results of the effect of redox initiator dosage on the performance of copolymer oil displacement agents.

[0088]

[0089] (7) Effect of azo initiator V044 dosage on the performance of copolymer oil displacement agent

[0090] The effect of azo initiator VO44 dosage on the performance of the copolymer oil displacement agent is shown in Table 6. As the table shows, with increasing VO44 dosage, the molecular weight of the product first increases and then decreases, resulting in a corresponding increase and decrease in the viscosity of the copolymer solution. The viscosity retention initially increases and then decreases. When the VO44 dosage is 35 mg / L, excessive initiator dosage easily leads to chain transfer between polymer molecular chains, resulting in molecular chain cross-linking and making the product difficult to dissolve in water. Therefore, a VO44 dosage range of 20-30 mg / L is recommended.

[0091] Table 6. Evaluation results of the effect of redox initiator dosage on the performance of copolymer oil displacement agents.

[0092]

[0093] (8) Effect of degree of hydrolysis (NaOH dosage) on the performance of copolymer oil displacement agent

[0094] The degree of hydrolysis of the copolymer can be altered by changing the amount of NaOH added. The effect of the degree of hydrolysis on the performance of the copolymer as an oil displacement agent is shown in Table 7. As the table shows, with increasing degree of hydrolysis, the viscosity of the copolymer solution first increases and then decreases, as does the viscosity retention rate. An appropriate degree of hydrolysis allows the copolymer molecular chains to remain extended in seawater, which is beneficial for intermolecular association, resulting in higher viscosity and a higher viscosity retention rate. Too low a degree of hydrolysis leads to coiled molecular chains and low viscosity, while too high a degree of hydrolysis results in poor salt resistance and low viscosity.

[0095] Furthermore, as shown in the table, 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 degree of hydrolysis on the performance of copolymer oil displacement agents

[0097]

[0098] Note: Comparative Example 1 was prepared according to the patent CN118546293A "A modified polyacrylamide containing a biodegradable hydrophobic monomer and its preparation method".

[0099] (8) Evaluation of the oil displacement performance of copolymer oil displacement agents

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

[0101] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a copolymer oil displacement agent containing modified polyetheramine macromonomers, characterized in that, Includes the following steps: S1. Equimolar amounts of p-chlorobenzaldehyde and polyether monoamine are added to ethanol, and a Schiff base reaction is carried out under stirring at room temperature to obtain an intermediate product solution. An equimolar amount of N-(3-dimethylaminopropyl)methacrylamide is added to the intermediate product solution to carry out a quaternization reaction. The ethanol is removed by rotary evaporation to obtain the modified polyether amine macromonomer. The polyether monoamine is a block copolymer composed of propylene oxide and ethylene oxide. The polyether monoamine is one of Huntsman's M-1000, M-2005, M-2070, or M3085. S2. Dissolve the modified polyetheramine macromonomer and acrylamide in deionized water, cool to 4-6 °C, and pour into an adiabatic reactor. Pour nitrogen gas into the reactor to remove oxygen, then add sodium bisulfite, potassium persulfate, and VO44 sequentially. Continue purging with nitrogen until the reaction solution exhibits obvious stringing. Seal the reactor and allow the polymerization reaction to continue until the system temperature no longer rises, yielding a polymer block. Crush the polymer block and add sodium hydroxide solution, mix thoroughly, and hydrolyze at 75-85 °C for 3.8-4.2 h. Dry and crush to obtain hydrophobically modified polyacrylamide containing polyetheramine structural units. The modified polyetheramine macromonomer is added at a mass fraction of 0.1%-0.4% of acrylamide; the acrylamide mass fraction is 18%-23%; the potassium persulfate dosage is 10 mg / L-36 mg / L; the sodium bisulfite dosage is 10 mg / L-36 mg / L; and the VO44 dosage is 20 mg / L-30 mg / L. mg / L; sodium hydroxide accounts for 2%-3% of the mass fraction of the polymer block.

2. A copolymer oil displacement agent containing modified polyetheramine macromonomers, characterized in that, It is prepared by the method for preparing the copolymer oil displacement agent containing modified polyetheramine macromonomer as described in claim 1.

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