A polyacrylamide oil displacement agent, its preparation method and application

Abstract

This invention belongs to the field of petroleum extraction technology, specifically relating to a polyacrylamide oil displacement agent, its preparation method, and its application. The preparation method is as follows: Didodecylamine, chloroform, and triethylamine are added to a first reactor, acryloyl chloride is added dropwise in an ice bath, and the reaction is maintained at a certain temperature to obtain a first functional monomer; under nitrogen protection, allyloxy polyoxyethylene ether is added to a second reactor, followed by aminosulfonic acid, and the reaction is maintained at a certain temperature to obtain a second functional monomer; in a third reactor, acrylamide, distilled water, emulsifier, the first functional monomer, the second functional monomer, 5-methylacrylamidophthalic acid, and sodium dihydrogen phosphate are added sequentially, stirred evenly, an initiator is added, the reaction is maintained at a certain temperature, and the mixture is dried to obtain the product. The oil displacement agent of this invention has the advantages of high apparent viscosity and strong emulsifying and viscosity-reducing ability.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a polyacrylamide oil displacement agent, its preparation method, and its application. Background Technology

[0002] Currently, major oilfields in China have entered the middle and late stages of oilfield development, with increasingly complex reservoir conditions and challenges such as severe formation heterogeneity and complex distribution of remaining oil. Traditional secondary oil recovery methods such as water injection and gas injection can no longer meet the demands of economical extraction, making tertiary oil recovery technology a key approach. Polyacrylamide, due to its viscosity-enhancing properties, flow control capabilities, and environmental adaptability, has become the most commonly used oil displacement agent in tertiary oil recovery.

[0003] By adding a certain amount of high-molecular-weight polyacrylamide to the injected water, the viscosity of the injected water is increased, the oil-water mobility ratio is improved, and the seepage resistance of the injected water is increased. This increases the water absorption of low-permeability layers or low-water-flooded layers, expands the contact area of ​​the injected water on the oil layer plane and the water-flooded thickness in the oil layer longitudinal direction, and then expands the swept volume to displace the crude oil that was not mobilized during waterflooding, thereby achieving the goal of improving the oil recovery rate.

[0004] The quality of polyacrylamide largely determines the effectiveness of improving oil recovery. Many researchers are dedicated to structurally modifying polyacrylamide to give it significant thickening effects, high interfacial activity, and high emulsification ability, thereby effectively increasing the viscosity of the displacement fluid, improving the sweep efficiency, and increasing the swept volume.

[0005] CN 105542073 B discloses a method for preparing polyacrylamide for polymer flooding, belonging to the field of polymer technology. The steps are as follows: cationic monomer, acrylamide, trimethylolpropionamide, surfactant, and water are mixed evenly, and nitrogen gas is introduced into the mixture; an initiator is added, the temperature is raised, the reaction is maintained, the temperature is lowered, hydroxyethyl acrylate and dimethylchlorosilane are added to the mixture, the pH value of the reaction system is adjusted, the temperature is raised, the reaction is maintained, and after completion, the resulting gel-like product is taken out, cut, dried, granulated, and sieved to obtain the polyacrylamide product. This invention, by adjusting the monomer reaction sequence during the polymerization of modified polyacrylamide, first allows the cationic monomer to partially polymerize with acrylamide, and then the hydroxyethyl acrylate and dimethylchlorosilane continue the polymerization reaction, thus enabling the prepared modified polyacrylamide to have a viscosity-increasing effect in solutions with high ion concentrations. However, the viscosity of this invention is only about 30 mPa·s, which is too low for polymer flooding, and the sweep efficiency and swept volume are unsatisfactory.

[0006] CN 104448129 B discloses a high-temperature resistant hydrolytic copolymer for oilfields, its preparation method, and its application in oil production. This invention, by employing a high-temperature resistant hydrolytic copolymer, effectively solves the problem of poor hydrolytic stability of polyacrylamide under high-temperature and high-salinity conditions, which is present in previous technologies. It can be used in oilfield production. However, this invention only has the function of ordinary polymer flooding, and its principle is to increase the swept volume. Since it lacks active groups in its molecular structure, it cannot reduce the oil-water interfacial tension, cannot emulsify and reduce viscosity, thus affecting the oil recovery rate. Summary of the Invention

[0007] This invention addresses the shortcomings of the prior art by providing a polyacrylamide oil displacement agent and its preparation method. The oil displacement agent of this invention has the advantages of high apparent viscosity and strong emulsification and viscosity reduction capabilities; at a concentration of 1500 mg / L, the apparent viscosity can reach 70 mPa·s, and the viscosity reduction rate for crude oil at 6000 mPa·s can reach 98.8%.

[0008] The first objective of this invention is to disclose a method for preparing a polyacrylamide oil displacement agent, the specific steps of which are as follows: (1) Add bis(dodecylamine), chloroform and triethylamine to the first reactor, add acryloyl chloride dropwise in an ice bath, keep the reaction warm, and after the reaction is complete, wash with acid, wash with water and distill under reduced pressure to obtain the first functional monomer.

[0009] (2) Under nitrogen protection, allyloxy polyoxyethylene ether was added to the second reactor, aminosulfonic acid was added, and the reaction was kept at a constant temperature to obtain the second functional monomer.

[0010] (3) Add acrylamide, distilled water, emulsifier, first functional monomer, second functional monomer, 5-methylacrylamidophthalic acid, and sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion. (4) Add an initiator, keep the reaction at a constant temperature, and cool down to below 40°C to obtain a viscous liquid; Ethanol was added, a solid precipitated, and dried to obtain the product, polyacrylamide oil displacement agent.

[0011] Preferably, the mass ratio of chloroform, triethylamine, acryloyl chloride and dodecylamine in step (1) is 5-10, 0.5-1:0.25-0.4:1.

[0012] Preferably, the heat preservation reaction temperature in step (1) is 0-20℃ and the time is not less than 2h.

[0013] Preferably, the mass ratio of aminosulfonic acid to allyloxy polyoxyethylene ether in step (2) is 0.1-0.12:1.

[0014] Preferably, the heat preservation reaction temperature in step (2) is 90-110℃ and the time is not less than 1 hour.

[0015] Preferably, the mass ratio of the first functional monomer, the second functional monomer, 5-methylacrylamidophthalic acid and acrylamide in step (3) is 0.05-0.1, 0.1-0.2, 0.1-0.2:1.

[0016] Preferably, the mass ratio of distilled water, emulsifier, sodium dihydrogen phosphate in step (3), initiator and acrylamide in step (4) is 10-20:0.1-0.2, 0.05-0.1:0.05-0.3:1.

[0017] Preferably, the emulsifier in step (3) is one of OP-10 (dodecylphenol polyoxyethylene ether) and TX-10 (nonylphenol polyoxyethylene ether); Preferably, the initiator is one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0018] Preferably, the heat preservation reaction in step (4) is carried out at a temperature of 60-80℃ for a time of more than 1 hour.

[0019] The second objective of this invention is to disclose the oil displacement agent prepared by the above preparation method.

[0020] The third objective of this invention is to disclose the application of the above-mentioned oil displacement agent in polymer flooding.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The polyacrylamide oil displacement agent of the present invention is obtained by modifying the molecular structure of the classic oil displacement agent polyacrylamide. The main modification is the addition of some functional monomers, which improves the original function of polyacrylamide. The first functional monomer has strong lipophilicity, and the long-chain alkanes are similar in properties to crude oil, which can easily penetrate into the crude oil and increase the oil-water binding capacity. The second functional monomer is a long-chain nonionic anion with strong hydrophilicity, which can penetrate into the aqueous phase and easily form a uniform O / W emulsion. 5-Methylacrylamide isophthalic acid can significantly reduce the interfacial tension between oil and water, enhance the emulsification and viscosity reduction performance of crude oil, and the presence of benzene rings in the molecule can increase the shear resistance of the present invention.

[0022] (1) The polyacrylamide oil displacement agent of the present invention has high apparent viscosity and emulsification viscosity reduction performance. The concentration of 1500 mg / L reaches 62 mPa·s and above, and the viscosity reduction rate of crude oil at 6000 mPa·s reaches more than 98%. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] Example 1 1. Preparation of the first functional monomer 10g of dodecylamine, 50g of chloroform, and 5g of triethylamine were added to the first reactor. 2.5g of acryloyl chloride was added dropwise in an ice bath. The reaction was maintained at 0°C for 4 hours. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0025] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2g of aminosulfonic acid. The mixture was kept at 90℃ for 2 hours to obtain the second functional monomer.

[0026] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 200g distilled water, 2g OP-10, 1g first functional monomer, 2g second functional monomer, 4g 5-methylacrylamidophthalic acid, and 1g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 1g of sodium persulfate, keep the temperature at 60℃ for 3h, and cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0027] Example 2 1. Preparation of the first functional monomer 10g of dodecylamine, 60g of chloroform, and 6g of triethylamine were added to the first reactor. 3g of acryloyl chloride was added dropwise in an ice bath. The reaction was kept at 10°C for 2 hours. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0028] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2.2g of aminosulfonic acid. The mixture was kept at 110℃ for 1 hour to obtain the second functional monomer.

[0029] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 220g distilled water, 3g OP-10, 1.5g first functional monomer, 2.5g second functional monomer, 3.5g 5-methylacrylamidophthalic acid, and 1.5g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 2g of sodium persulfate, keep the temperature at 65℃ for 2h, and cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0030] Example 3 1. Preparation of the first functional monomer 10g of dodecylamine, 80g of chloroform, and 10g of triethylamine were added to the first reactor. 3g of acryloyl chloride was added dropwise in an ice bath. The reaction was kept at 20°C for 3 hours. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0031] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2.4g of aminosulfonic acid. The mixture was kept at 90℃ for 2 hours to obtain the second functional monomer.

[0032] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 300g distilled water, 4g OP-10, 2g first functional monomer, 3g second functional monomer, 3g 5-methylacrylamidophthalic acid, and 1.5g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 3g of sodium persulfate, keep the temperature at 70℃ for 2.5h, and then cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0033] Example 4 1. Preparation of the first functional monomer 10g of dodecylamine, 100g of chloroform, and 8g of triethylamine were added to the first reactor. 3.5g of acryloyl chloride was added dropwise in an ice bath. The reaction was maintained at 10°C for 2.5h. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0034] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2.1g of aminosulfonic acid. The mixture was kept at 100℃ for 1.2h to obtain the second functional monomer.

[0035] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 400g distilled water, 3g OP-10, 2g first functional monomer, 3.5g second functional monomer, 2.5g 5-methylacrylamidophthalic acid, and 2g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 4g of potassium persulfate, keep the temperature at 75℃ for 2h, and then cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0036] Example 5 1. Preparation of the first functional monomer 10g of dodecylamine, 80g of chloroform, and 8g of triethylamine were added to the first reactor. 4g of acryloyl chloride was added dropwise in an ice bath. The reaction was carried out at 8°C for 3 hours. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0037] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2.3g of aminosulfonic acid. The mixture was kept at 100℃ for 1.5h to obtain the second functional monomer.

[0038] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 250g distilled water, 2g TX-10, 1.8g first functional monomer, 3g second functional monomer, 2.5g 5-methylacrylamidophthalic acid, and 1.8g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 5g of ammonium persulfate, keep the temperature at 80℃ for 1.5h, cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0039] Example 6 1. Preparation of the first functional monomer 10g of dodecylamine, 80g of chloroform, and 8g of triethylamine were added to the first reactor. 4g of acryloyl chloride was added dropwise in an ice bath. The reaction was maintained at 5°C for 3.2h. After the reaction was completed, the mixture was successively acid-washed, water-washed, and distilled under reduced pressure to obtain the first functional monomer.

[0040] 2. Preparation of the second functional monomer Under nitrogen protection, 20g of allyloxy polyoxyethylene ether was added to the second reactor, along with 2.2g of aminosulfonic acid. The mixture was kept at 98℃ for 2 hours to obtain the second functional monomer.

[0041] 3. Synthesis of oil displacement agents (1) Add 20g acrylamide, 300g distilled water, 4g TX-10, 1.4g first functional monomer, 4g second functional monomer, 2g 5-methylacrylamidophthalic acid, and 1.8g sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion; (2) Add 6g of potassium persulfate, keep the temperature at 70℃ for 2h, and cool down to below 40℃ to obtain a viscous liquid; (3) Add ethanol, precipitate solid, dry to obtain polyacrylamide oil displacement agent.

[0042] Example 7: Apparent viscosity test The polyacrylamide oil displacement agent of the present invention (Examples 1-6) was prepared into a 1500 mg / L solution using polyacrylamide water injection in a certain block of Shengli Oilfield, and then subjected to 60°C and 170 s... -1 Under the given conditions, the apparent viscosity μ was tested using the DV-III Brinell viscosity test.

[0043] Anionic PAM from Shandong Baomo Biochemical Co., Ltd. was used as a comparison sample, and the test results are shown in Table 1.

[0044] As can be seen from Table 1, the polyacrylamide oil displacement agent of the present invention (Examples 1-6) has a high apparent viscosity. When the concentration is 1500 mg / L, the apparent viscosity reaches 62 mPa•s or above, and the highest reaches 70 mPa•s (Example 6). In contrast, the apparent viscosity of the anionic PAM of Shandong Baomo Biochemical Co., Ltd., a comparative example, is 32 mPa•s, which is significantly lower than that of the present invention.

[0045] Example 8: Determination of viscosity reduction rate The polyacrylamide oil displacement agent of the present invention (Examples 1-6) was prepared into a 1000 mg / L solution with deionized water and preheated in a water bath at 70°C. Crude oil (viscosity 6000 mPa·s) from a block of Shengli Oilfield was also preheated in a water bath at 70°C. 30 g of each solution was placed in a 100 ml stoppered graduated cylinder and heated in a water bath at 70°C for another 0.5 h. The stopper was then pressed down and shaken up and down about 60 times by hand. The viscosity was tested, and the viscosity reduction rate was calculated.

[0046] Anionic PAM from Shandong Baomo Biochemical Co., Ltd. was used as a comparison sample, and the test results are shown in Table 1.

[0047] Table 1. Results of Apparent Viscosity and Viscosity Reduction Tests μ, mPa•s Viscosity reduction rate, % Example 1 62 98.2 Example 2 65 98.4 Example 3 63 98.5 Example 4 66 98.8 Example 5 68 98.7 Example 6 70 98.8 Comparative Example 32 Non-emulsification As can be seen from Table 1, the polyacrylamide oil displacement agent of the present invention (Examples 1-6) has high emulsification and viscosity reduction performance. When the concentration is 1500 mg / L, the viscosity reduction rate of crude oil at 6000 mPa·s reaches more than 98%, and the highest reaches 98.8%. In contrast, the anionic PAM of Shandong Baomo Biochemical Co., Ltd. in the comparative example does not emulsify the above crude oil and the viscosity reduction effect is not obvious.

[0048] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a polyacrylamide oil displacement agent, characterized in that, The specific steps of the preparation method are as follows: (1) Add dodecylamine, chloroform and triethylamine to the first reactor, add acryloyl chloride dropwise in an ice bath, keep the reaction warm, and after the reaction is complete, wash with acid, wash with water and distill under reduced pressure to obtain the first functional monomer. (2) Under nitrogen protection, allyloxy polyoxyethylene ether was added to the second reactor, aminosulfonic acid was added, and the reaction was kept at a constant temperature to obtain the second functional monomer. (3) Add acrylamide, distilled water, emulsifier, first functional monomer, second functional monomer, 5-methylacrylamidophthalic acid, and sodium dihydrogen phosphate to the third reactor in sequence, stir evenly, purge the reactor and pipeline with nitrogen, and adjust the pH to 7-8 with sodium hydroxide solution until all raw materials become a uniform emulsion. (4) Add an initiator, keep the reaction at a constant temperature, and cool down to below 40°C to obtain a viscous liquid; Ethanol was added, a solid precipitated, and dried to obtain the product polyacrylamide oil displacement agent. The mass ratio of chloroform, triethylamine, acryloyl chloride and didodecylamine mentioned in step (1) is 5-10, 0.5-1:0.25-0.4:1; The mass ratio of aminosulfonic acid to allyloxy polyoxyethylene ether mentioned in step (2) is 0.1-0.12:1; The mass ratio of the first functional monomer, the second functional monomer, 5-methylacrylamidophthalic acid and acrylamide in step (3) is 0.05-0.1, 0.1-0.2, and 0.1-0.2:

1.

2. The preparation method according to claim 1, characterized in that, The heat preservation reaction temperature in step (1) is 0-20℃ and the time is not less than 2h.

3. The preparation method according to claim 1, characterized in that, The heat preservation reaction temperature in step (2) is 90-110℃ and the time is not less than 1 hour.

4. The preparation method according to claim 1, characterized in that, The mass ratio of distilled water, emulsifier, sodium dihydrogen phosphate, initiator and acrylamide is 10-20:0.1-0.2, 0.05-0.1:0.05-0.3:

1.

5. The preparation method according to claim 1, characterized in that, The emulsifier mentioned in step (3) is one of dodecylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

6. The preparation method according to claim 1, characterized in that, The initiator is one of potassium persulfate, sodium persulfate, and ammonium persulfate.

7. The preparation method according to claim 1, characterized in that, The heat preservation reaction described in step (4) is carried out at a temperature of 60-80℃ for a time of more than 1 hour.

8. The polyacrylamide oil displacement agent prepared by the preparation method according to any one of claims 1-7.

9. The application of the polyacrylamide displacement agent according to claim 8 in polymer displacement.