Temperature-resistant and salt-resistant composite oil displacement agent and preparation method thereof

Abstract

The present application relates to a kind of temperature-resistant, salt-tolerant composite oil displacement agent and its preparation method, the temperature-resistant, salt-tolerant composite oil displacement agent includes by weight percentage: zwitterionic hydrophobic association polymer 0.05-0.2%, surfactant 0.1-0.6%, surfactant additive 0.05-0.2%, the rest is water.The zwitterionic hydrophobic association polymer in the present application can significantly enhance the salt tolerance of composite oil displacement agent through the electrostatic balance effect between ions in zwitterionic structure, its rigid naphthalene ring structure can effectively improve the thermal stability of system under high temperature environment.The present application uses 5-norbornene-2-carboxylic acid as surfactant additive, which can reduce oil-water interfacial tension, improve the stripping capacity of oil displacement agent on rock surface crude oil, effectively improve oil washing efficiency.At the same time, the oil displacement agent can still maintain high viscosity under high temperature and high salt conditions, further improve the temperature resistance of oil displacement agent.

Description

Technical Field

[0001] This invention relates to the field of oil displacement agent technology, and in particular to a temperature- and salt-resistant composite oil displacement agent and its preparation method. Background Technology

[0002] The development of oil extraction technology can be divided into three main stages: the initial extraction stage (primary oil recovery), the water injection development stage (secondary oil recovery), and the enhanced oil recovery stage (tertiary oil recovery). In enhanced oil recovery (EOR), specific displacement media are injected into the reservoir. Utilizing their physicochemical interactions with crude oil, the fluidity of the crude oil is improved, and the mobility ratio of the displacement media to the crude oil is reduced, thereby effectively increasing the displacement efficiency and recovery rate. Among existing EOR technologies, chemical flooding is the most commonly used method, mainly including polymer flooding, surfactant flooding, alkali flooding, nanoparticle flooding, and composite flooding. Among these, composite flooding, by combining two or more of polymers, surfactants, nanoparticles, or alkalis to achieve a synergistic effect, demonstrates a significantly better oil displacement effect than single-technology flooding and shows remarkable advantages in practical applications.

[0003] With the continuous depletion of recoverable reserves in conventional oil reservoirs, the development of complex reservoirs with high temperature and high salinity has become a pressing technical challenge. However, the commonly used partially hydrolyzed polyacrylamide (HPAM) suffers from molecular chain coiling at high temperatures, and the carboxyl groups have a significant impact on Ca2+. 2+ Mg 2+ This type of agent is sensitive and prone to phase separation in high-salt environments, leading to a significant decrease in oil displacement efficiency and making it difficult to meet the extraction requirements of high-temperature and high-salt oil reservoirs. Therefore, it is essential to develop a composite oil displacement agent that is resistant to both temperature and salt. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a temperature- and salt-resistant composite oil displacement agent.

[0005] The second objective of this invention is to provide a method for preparing a temperature- and salt-resistant composite oil displacement agent.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a temperature- and salt-resistant composite oil displacement agent, which comprises, by weight percentage: 0.05-0.2% zwitterionic hydrophobic associative polymer, 0.1-0.6% surfactant, 0.05-0.2% surfactant auxiliaries, and the balance being water;

[0008] The preparation process of the zwitterionic hydrophobic associative polymer is as follows:

[0009] (1) Under nitrogen protection, sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate and tetra(triphenylphosphine)palladium were added to DMF. After the reaction, the mixture was cooled to room temperature, filtered, distilled under reduced pressure and purified to obtain intermediate 1.

[0010] (2) Under nitrogen protection, intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene were added to DMF. After the reaction, the mixture was filtered, washed and dried to obtain the functional monomer.

[0011] (3) Dissolve acrylamide and functional monomer in deionized water, adjust the pH of the solution, add initiator and chelating agent under nitrogen atmosphere, precipitate the product with anhydrous ethanol after reaction, and then dry and pulverize to obtain the product.

[0012] Preferably, the surfactant is a fatty alcohol polyoxyethylene ether; the surfactant additive is 5-norbornene-2-carboxylic acid.

[0013] Preferably, in step (1), the ratio of sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, tetra(triphenylphosphine)palladium, and DMF is 1g:1.8-2.0g:3.5-4.0g:0.2-0.4g:50-75mL.

[0014] Preferably, in step (1), the reaction conditions are 72-96 h at 125-135 °C.

[0015] Preferably, in step (2), the ratio of intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene, and DMF is 0.15g:0.35-0.37g:3-5mL.

[0016] Preferably, in step (2), the reaction conditions are 72-96 h at 125-135 °C.

[0017] Preferably, in step (3), the mass ratio of acrylamide, functional monomer, deionized water, initiator, and chelating agent is (12-16):(3-5):(78.3-84.5):(0.3-0.4):(0.2-0.3).

[0018] Preferably, in step (3), the pH of the solution is adjusted to 8.0-8.5; the reaction conditions are 60-75℃ for 6-12 hours.

[0019] Preferably, in step (3), the initiator is ammonium sulfate and sodium bisulfite, and the mass ratio of ammonium sulfate to sodium bisulfite is 2:1; the chelating agent is disodium ethylenediaminetetraacetate.

[0020] This invention provides a method for preparing the temperature-resistant and salt-resistant composite oil displacement agent, comprising the following steps: weighing each raw material according to the ratio, dissolving the surfactant and surfactant auxiliaries in water first, and then adding the zwitterionic hydrophobic associative polymer and stirring to dissolve, thereby obtaining the agent.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention provides a temperature- and salt-resistant composite oil displacement agent, composed of a zwitterionic hydrophobic associating polymer, a surfactant, and surfactant auxiliaries. The zwitterionic hydrophobic associating polymer is prepared by copolymerizing acrylamide with a functional monomer, which simultaneously introduces a zwitterionic structure containing pyridinium cations and sulfonate anions, as well as a naphthalene ring structure. The zwitterionic structure significantly enhances the salt resistance of the oil displacement agent through electrostatic equilibrium between ions, while the rigid naphthalene ring structure effectively improves the thermal stability of the system under high-temperature conditions.

[0023] Furthermore, using 5-norbornene-2-carboxylic acid as a surfactant adjuvant, its carboxylic acid group forms a mixed adsorption layer with the surfactant and the zwitterionic structure in the polymer. Meanwhile, its norbornene hydrophobic skeleton and the naphthalene ring structure in the polymer produce hydrophobic synergy. The synergy of the two significantly reduces the oil-water interfacial tension, greatly improves the stripping ability of the oil displacement agent on the crude oil on the rock surface, and effectively improves the oil washing efficiency. At the same time, the unique bicyclic [2.2.1]heptene skeleton of 5-norbornene-2-carboxylic acid provides rigid support, which can not only stabilize the emulsion or microemulsion through steric hindrance effect, prevent oil droplets from re-aggregating, extend the life of the emulsion or microemulsion, and ensure the deep displacement effect, but also generate π-π stacking and hydrophobic association with the naphthalene ring in the zwitterionic hydrophobic association polymer to form a denser three-dimensional network, so that the oil displacement agent can still maintain high viscosity under high temperature and high salt conditions, further improving the temperature resistance of the oil displacement agent.

[0024] This invention provides a method for preparing a temperature- and salt-resistant composite oil displacement agent. The method is simple and suitable for industrial production and application. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0026] Example 1

[0027] This embodiment relates to a temperature- and salt-resistant composite oil displacement agent, which comprises, by weight percentage: 0.15% zwitterionic hydrophobic associative polymer, 0.4% surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.1% surfactant auxiliaries (5-norbornene-2-carboxylic acid), and the balance being water.

[0028] The preparation process of the zwitterionic hydrophobic associative polymer in this embodiment is as follows:

[0029]

[0030] (1) Under nitrogen protection, sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, and tetra(triphenylphosphine)palladium were added to DMF (N,N-dimethylformamide), wherein the ratio of sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, tetra(triphenylphosphine)palladium, and DMF was 1 g: 2.0 g: 4.0 g: 0.3 g: 65 mL; the reaction was carried out at 130 °C for 84 h, cooled to room temperature, filtered to obtain the filtrate, the solvent was removed by vacuum distillation, and purified by silica gel column chromatography to obtain intermediate 1 (yield 56.8%); the obtained intermediate 1 1 HNMR: (400MHz, DMSO-d6) δ: 2.17-2.21 (m, 2H), 2.53-2.56 (t, 2H), 3.40-3.43 (t, 2H), 7.21-7.23 (d, 2H), 8.54-8.56 (d, 2H).

[0031] (2) Under nitrogen protection, intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene (CAS: 116545-04-1) were added to DMF, wherein the ratio of intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene, and DMF was 0.15 g: 0.36 g: 4 mL. After reacting at 130 °C for 84 h, the solid product was obtained by filtration, washed with DMF and diethyl ether, and dried under vacuum to obtain the functional monomer (yield 64.3%). The obtained functional monomer... 1 HNMR: (400MHz, D2O) δ: 2.16-2.20 (m, 2H), 2.53-2.56 (t, 2H), 2.61-2.65 (t, 2H), 3.66 (s, 2H), 5.0-5.4 (d, 2H), 6.92-6.94 (d, H), 7.29-7.33 (m, H), 7.49-7.53 (m, H), 7.59-7.63 (m, H), 7.94-8.03 (m, 5H), 9.26-9.28 (d, 2H).

[0032] (3) Dissolve acrylamide and functional monomer in deionized water, adjust the pH of the solution to 8.5, and add an initiator (ammonium sulfate and sodium bisulfite in a mass ratio of 2:1) and a chelating agent (disodium ethylenediaminetetraacetate) under nitrogen atmosphere. The mass ratio of acrylamide, functional monomer, deionized water, initiator and chelating agent is 15:4:80.3:0.4:0.3. After reacting at 70°C for 10 h, precipitate the product with anhydrous ethanol, vacuum dry and pulverize to obtain the final product.

[0033] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in this embodiment includes the following steps: weigh each raw material according to the ratio, dissolve the surfactant and surfactant auxiliaries in water first, and then add the zwitterionic hydrophobic associative polymer and stir to dissolve, thus obtaining the product.

[0034] Example 2

[0035] This embodiment relates to a temperature- and salt-resistant composite oil displacement agent, which comprises, by weight percentage: 0.2% zwitterionic hydrophobic associative polymer, 0.6% surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.2% surfactant auxiliaries (5-norbornene-2-carboxylic acid), and the balance being water.

[0036] The preparation process of the zwitterionic hydrophobic associative polymer in this embodiment is as follows:

[0037] (1) Under nitrogen protection, sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, and tetra(triphenylphosphine)palladium were added to DMF, wherein the ratio of sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, tetra(triphenylphosphine)palladium, and DMF was 1 g: 2.0 g: 4.0 g: 0.4 g: 75 mL; the reaction was carried out at 135 °C for 72 h, cooled to room temperature, filtered to obtain the filtrate, the solvent was removed by vacuum distillation, and purified by silica gel column chromatography to obtain intermediate 1 (yield 55.3%); the obtained intermediate 1 1 HNMR is the same as in Example 1.

[0038] (2) Under nitrogen protection, intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene were added to DMF, wherein the ratio of intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene, and DMF was 0.15 g: 0.37 g: 5 mL. After reacting at 135 °C for 72 h, the solid product was obtained by filtration, washed with DMF and diethyl ether, and dried under vacuum to obtain the functional monomer (yield 62.7%). The obtained functional monomer... 1 HNMR is the same as in Example 1.

[0039] (3) Dissolve acrylamide and functional monomer in deionized water, adjust the pH of the solution to 8.5, and add initiator (ammonium sulfate and sodium bisulfite in a mass ratio of 2:1) and chelating agent (disodium ethylenediaminetetraacetate) under nitrogen atmosphere. The mass ratio of acrylamide, functional monomer, deionized water, initiator and chelating agent is 16:5:78.3:0.4:0.3. After reacting at 75°C for 6 hours, precipitate the product with anhydrous ethanol, vacuum dry and pulverize to obtain the final product.

[0040] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in this embodiment includes the following steps: weigh each raw material according to the ratio, dissolve the surfactant and surfactant auxiliaries in water first, and then add the zwitterionic hydrophobic associative polymer and stir to dissolve, thus obtaining the product.

[0041] Example 3

[0042] This embodiment relates to a temperature- and salt-resistant composite oil displacement agent, which comprises, by weight percentage: 0.05% zwitterionic hydrophobic associative polymer, 0.1% surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.05% surfactant auxiliaries (5-norbornene-2-carboxylic acid), and the balance being water.

[0043] The preparation process of the zwitterionic hydrophobic associative polymer in this embodiment is as follows:

[0044] (1) Under nitrogen protection, sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, and tetra(triphenylphosphine)palladium were added to DMF, wherein the ratio of sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaboryl)pyridine, potassium phosphate, tetra(triphenylphosphine)palladium, and DMF was 1 g:1.8 g:3.5 g:0.2 g:50 mL; the reaction was carried out at 125 °C for 96 h, cooled to room temperature, filtered to obtain the filtrate, the solvent was removed by vacuum distillation, and purified by silica gel column chromatography to obtain intermediate 1 (yield 54.6%); the obtained intermediate 1 1 HNMR is the same as in Example 1.

[0045] (2) Under nitrogen protection, intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene were added to DMF, wherein the ratio of intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene, and DMF was 0.15 g: 0.35 g: 3 mL. After reacting at 125 °C for 96 h, the solid product was obtained by filtration, washed with DMF and diethyl ether, and dried under vacuum to obtain the functional monomer (yield 61.4%). The obtained functional monomer... 1 HNMR is the same as in Example 1.

[0046] (3) Dissolve acrylamide and functional monomer in deionized water, adjust the pH of the solution to 8.0, and add an initiator (ammonium sulfate and sodium bisulfite in a mass ratio of 2:1) and a chelating agent (disodium ethylenediaminetetraacetate) under nitrogen atmosphere. The mass ratio of acrylamide, functional monomer, deionized water, initiator and chelating agent is 12:3:84.5:0.3:0.2. After reacting at 60°C for 12 h, precipitate the product with anhydrous ethanol, vacuum dry and pulverize to obtain the final product.

[0047] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in this embodiment includes the following steps: weigh each raw material according to the ratio, dissolve the surfactant and surfactant auxiliaries in water first, and then add the zwitterionic hydrophobic associative polymer and stir to dissolve, thus obtaining the product.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that the functional monomer in step (3) of preparing zwitterionic hydrophobic associative polymer is omitted.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that the surfactant additive is omitted.

[0052] Test case

[0053] Simulated water with a mineralization of 9500 mg / L (wherein Na) was used. + +K + The concentration was 3000 mg / L, and the Ca concentration was... 2+ +Mg 2+ The composite oil displacement agents of Examples 1-3 and Comparative Examples 1-2 were prepared with a concentration of 450 mg / L. The interfacial tension and viscosity of the composite oil displacement system were measured according to SY / T6424-2014 "Performance Test Method of Composite Oil Displacement System". The results are shown in Table 1. The specific contents are as follows.

[0054] 1. The interfacial tension between the composite oil displacement agent and crude oil (reservoir temperature 40℃, viscosity 16mPa·s) was determined by the rotating drop method (45℃, interfacial tensiometer speed 5000r / min).

[0055] 2. The viscosity of the composite oil displacement agent was measured at 25℃.

[0056] 3. The composite oil displacement agent was aged at 75℃ for 90 days. The viscosity of the composite oil displacement agent before and after aging was measured, and the viscosity retention rate after aging was calculated.

[0057] 4. The composite oil displacement agent was sheared at 75℃ and a shear rate of 7000 r / min for 20 s. The viscosity of the composite oil displacement agent before and after shearing was measured, and the viscosity retention rate after shearing was calculated.

[0058] Table 1

[0059]

[0060] As shown in Table 1, the salt resistance and thermal stability of the composite oil displacement agents corresponding to Examples 1-3 of this invention are better than those of Comparative Examples 1-2. This is because the zwitterionic hydrophobic associative polymer in the composite oil displacement agent of this invention introduces a zwitterionic structure containing pyridinium cations and sulfonate anions, as well as a naphthalene ring structure. This zwitterionic structure significantly enhances the salt resistance of the oil displacement agent through electrostatic equilibrium between ions, while the rigid naphthalene ring structure effectively improves the thermal stability of the system under high-temperature conditions. This invention uses 5-norbornene-2-carboxylic acid as a surfactant adjuvant. Its carboxylic acid groups form a mixed adsorption layer with the surfactant and the zwitterionic structure in the polymer, while its norbornene hydrophobic framework and the naphthalene ring structure in the polymer produce a hydrophobic synergy. This synergy significantly reduces the oil-water interfacial tension, greatly improves the stripping ability of the oil displacement agent on the rock surface of crude oil, and effectively improves the oil washing efficiency. Meanwhile, the bicyclic [2.2.1]heptene skeleton of 5-norbornene-2-carboxylic acid provides rigid support, forming a denser three-dimensional network with zwitterionic hydrophobic associative polymers, enabling the oil displacement agent to maintain high viscosity under high temperature and high salt conditions, further improving the temperature resistance of the oil displacement agent.

[0061] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A temperature-resistant, salt-resistant composite oil displacement agent, characterized in that, The temperature-resistant and salt-resistant composite oil displacement agent comprises, by weight percentage, 0.05-0.2% of zwitterionic hydrophobic associating polymer, 0.1-0.6% of surfactant, 0.05-0.2% of surfactant aid, and the rest is water; the surfactant is fatty alcohol polyoxyethylene ether; and the surfactant aid is 5-norbornene-2-carboxylic acid. The zwitterionic hydrophobic associating polymer is prepared by the following process: (1) under nitrogen protection, 3-bromopropane sulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine, potassium phosphate and tetrakis(triphenylphosphine)palladium are added into DMF, after reaction, cooling to room temperature, filtration, reduced pressure distillation, purification, and the intermediate 1 is obtained; (2) under nitrogen protection, the intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene are added into DMF, after reaction, filtration, washing, drying, and the functional monomer is obtained; (3) acrylamide and the functional monomer are dissolved in deionized water, the solution pH is adjusted, under nitrogen environment, an initiator and a chelating agent are added, after reaction, the product is precipitated with anhydrous ethanol, drying and crushing, and the zwitterionic hydrophobic associating polymer is obtained. The chemical structural formula of the 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine is .

2. The temperature-resistant and salt-resistant composite oil displacement agent according to claim 1, characterized in that, In the step (1), the dosage ratio of 3-bromopropane sulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine, potassium phosphate, tetrakis(triphenylphosphine)palladium and DMF is 1g:1.8-2.0g:3.5-4.0g:0.2-0.4g:50-75mL. 3.The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (1), the reaction condition is 125-135℃ for 72-96h.

4. The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (2), the dosage ratio of the intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene and DMF is 0.15g:0.35-0.37g:3-5mL.

5. The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (2), the reaction condition is 125-135℃ for 72-96h. 6.The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (3), the mass ratio of acrylamide, the functional monomer, deionized water, the initiator and the chelating agent is (12-16):(3-5):(78.3-84.5):(0.3-0.4):(0.2-0.3).

7. The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (3), the solution pH is adjusted to 8.0-8.5; and the reaction condition is 60-75℃ for 6-12h. 8.The temperature-tolerant and salt-tolerant composite oil displacement agent according to claim 1, characterized in that, In the step (3), the initiator is ammonium sulfate and sodium bisulfite, and the mass ratio of ammonium sulfate and sodium bisulfite is 2:1; and the chelating agent is ethylenediaminetetraacetic acid disodium.

9. The method for preparing temperature-resistant and salt-resistant composite oil displacement agent according to any one of claims 1-8, characterized in that, The method comprises the following steps: weighing each raw material according to the proportion, dissolving the surfactant and the surfactant aid in water, and then adding the zwitterionic hydrophobic associating polymer to stir and dissolve, and the temperature-resistant and salt-resistant composite oil displacement agent is obtained.

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