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

Abstract

The invention relates to a temperature-resistant and salt-resistant composite oil-displacing agent and a preparation method thereof. The temperature-resistant and salt-resistant composite oil-displacing agent is prepared from the following components in percentage by weight: 0.05 to 0.2 percent of zwitterionic hydrophobic association polymer, 0.1 to 0.6 percent of surfactant, 0.05 to 0.2 percent of surfactant aid and the balance of water. The zwitterionic structure in the zwitterionic hydrophobic association polymer can significantly enhance the salt tolerance of the composite oil-displacing agent through the electrostatic equilibrium effect among ions, and the rigid naphthalene ring structure can effectively improve the thermal stability of the system in a high-temperature environment. According to the invention, 5-norbornene-2-carboxylic acid is taken as a surfactant auxiliary agent, so that the oil-water interfacial tension can be reduced, the stripping capability of the oil displacement agent on crude oil on the rock surface is improved, and the oil washing efficiency is effectively improved. Meanwhile, the oil-displacing agent can still keep high viscosity under high-temperature and high-salt conditions, and the temperature resistance of the oil-displacing agent is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil displacement agents, in particular to a temperature-resistant and salt-resistant composite oil displacement agent and a preparation method thereof. BACKGROUND

[0002] The development history of oil production technology can be divided into three main stages: initial production stage (primary oil recovery), water injection development stage (secondary oil recovery) and enhanced production stage (tertiary oil recovery). In the process of enhanced oil recovery (EOR), by injecting specific displacement medium into the reservoir, the physical and chemical action between the displacement medium and crude oil is utilized to improve the flowability of crude oil, reduce the mobility ratio of the displacement medium and crude oil, and thus effectively improve the displacement efficiency and recovery rate of crude oil. Among the existing EOR technologies, chemical flooding is the most commonly used method to improve recovery, mainly including polymer flooding, surfactant flooding, alkali flooding, nanoparticle flooding and composite flooding, etc. Among them, composite flooding uses two or more of polymer, surfactant, nanoparticle or alkali to play a synergistic effect, and its oil displacement effect is obviously better than that of single oil displacement technology, which shows significant advantages in practical application.

[0003] With the continuous decrease of recoverable reserves of conventional oil reservoirs, the development of complex oil reservoirs with high temperature and high salinity has become a technical problem that needs to be broken through at present. However, the commonly used partially hydrolyzed polyacrylamide (HPAM) is prone to curling at high temperature, and the carboxyl group is sensitive to Ca 2+ , Mg 2+ , which is easy to phase separate in high-salt environment, resulting in a significant decrease in oil displacement effect, and it is difficult to meet the production needs of high-temperature and high-salt oil reservoirs. Therefore, it is necessary to develop a temperature-resistant and salt-resistant composite oil displacement agent. SUMMARY

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

[0005] The second purpose of the present application is to provide a preparation method of the temperature-resistant and salt-resistant composite oil displacement agent.

[0006] To achieve the above purposes, the present application adopts the following technical solutions: The present application provides a temperature-resistant and salt-resistant composite oil displacement agent, which 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 balance of water. The preparation process of the zwitterionic hydrophobic associating polymer is as follows: (1) under the protection of nitrogen, 3-bromopropane sulfonate sodium, 4-(4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborinyl) pyridine, potassium phosphate and tetrakis (triphenylphosphine) palladium are added into DMF, after reaction, cooling to room temperature, filtering, distillation under reduced pressure, purification, to obtain intermediate 1; (2) under the protection of nitrogen, intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene are added into DMF, after reaction, filtering, washing, drying, to obtain functional monomer; (3) acrylamide and functional monomer are dissolved in deionized water, adjusting the pH of the solution, under the nitrogen environment, adding initiator, chelating agent, after reaction, the product is precipitated with anhydrous ethanol, drying, crushing, to obtain.

[0007] Preferably, the surfactant is fatty alcohol polyoxyethylene ether; the surfactant auxiliary is 5-norbornene-2-carboxylic acid.

[0008] Preferably, in step (1), the amount ratio of 3-bromopropane sulfonate sodium, 4-(4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborinyl) pyridine, potassium phosphate, tetrakis (triphenylphosphine) palladium, DMF is 1g: 1.8-2.0g: 3.5-4.0g: 0.2-0.4g: 50-75mL.

[0009] Preferably, in step (1), the reaction condition is 72-96h at 125-135℃.

[0010] Preferably, in step (2), the amount ratio of intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene, DMF is 0.15g: 0.35-0.37g: 3-5mL.

[0011] Preferably, in step (2), the reaction condition is 72-96h at 125-135℃.

[0012] Preferably, in step (3), the mass ratio of acrylamide, functional monomer, deionized water, initiator, chelating agent is (12-16): (3-5): (78.3-84.5): (0.3-0.4): (0.2-0.3).

[0013] Preferably, in step (3), the pH of the solution is adjusted to 8.0-8.5; the reaction condition is 6-12h at 60-75℃.

[0014] Preferably, in step (3), the initiator is ammonium sulfate and sodium bisulfite, the mass ratio of ammonium sulfate and sodium bisulfite is 2:1; the chelating agent is ethylenediaminetetraacetic acid disodium.

[0015] The application provides a preparation method of the temperature-resistant and salt-resistant composite oil displacement agent, which comprises the following steps: weighing raw materials according to a proportion, dissolving surfactants and surfactant auxiliaries in water, and then adding and stirring to dissolve zwitterionic hydrophobic associated polymers, and the preparation is completed.

[0016] Compared with the prior art, the application has the beneficial effects that: The application provides a temperature-resistant and salt-resistant composite oil displacement agent which is composed of zwitterionic hydrophobic associated polymers, surfactants and surfactant auxiliaries. The zwitterionic hydrophobic associated polymers are prepared by copolymerization of acrylamide and functional monomers, and the functional monomers introduce zwitterionic structures containing pyridinium cations and sulfonate anions and naphthalene ring structures. The zwitterionic structures significantly enhance the salt resistance of the oil displacement agent through the electrostatic balance between ions, and the rigid naphthalene ring structure effectively improves the thermal stability of the system in a high-temperature environment.

[0017] In addition, 5-norbornene-2-carboxylic acid is used as the surfactant auxiliary, the carboxylic acid group of which forms a mixed adsorption layer with the zwitterionic structures of the surfactants and the polymers, and the norbornene hydrophobic skeleton thereof produces hydrophobic synergy with the naphthalene ring structure in the polymers, and the synergy of the two significantly reduces the oil-water interfacial tension and greatly improves the oil stripping capacity of the oil displacement agent on the rock surface crude oil, effectively improving the oil washing efficiency; meanwhile, the double ring [2.2.1] heptene skeleton unique to 5-norbornene-2-carboxylic acid provides rigid support, which can stabilize the emulsion or microemulsion through the steric hindrance effect, prevent oil droplets from re-coalescing, prolong the life of the emulsion or microemulsion, and ensure the deep displacement effect; the rigid ring can also produce pi-pi stacking and hydrophobic association with the naphthalene ring in the zwitterionic hydrophobic associated polymers, forming a more compact 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.

[0018] The application provides a preparation method of a temperature-resistant and salt-resistant composite oil displacement agent, and the method is simple in process and suitable for industrial production and application. DETAILED DESCRIPTION

[0019] The application will be further described in combination with specific embodiments, and it should be noted that, under the premise of no conflict, the embodiments described below or the technical features can be combined in any manner to form new embodiments. The specific conditions not mentioned in the embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, such as the conventional products obtained through the market channel, are not specifically mentioned.

[0020] Example 1 The embodiment relates to a temperature-resistant and salt-resistant composite oil displacement agent, which comprises, in percentage by weight, 0.15% of a zwitterionic hydrophobic associating polymer, 0.4% of a surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.1% of a surfactant aid (5-norbornene-2-carboxylic acid), and the rest is water.

[0021] The preparation process of the zwitterionic hydrophobic associating polymer in the embodiment is as follows: (1) under the protection of nitrogen, 3-bromopropane sulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate and tetrakis (triphenylphosphine) palladium are added into DMF (N, N-dimethylformamide), wherein the ratio of the use amounts of 3-bromopropane sulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate, tetrakis (triphenylphosphine) palladium and DMF is 1g:2.0g:4.0g:0.3g:65mL; reaction is carried out at 130 DEG C for 84h, cooling to room temperature, filtration to obtain a filtrate, removal of the solvent by reduced pressure distillation, purification by a silica gel chromatographic column to obtain an intermediate 1 (the yield is 56.8%); the intermediate 1 obtained is subjected to 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).

[0022] (2) under the protection of nitrogen, the intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene (CAS: 116545-04-1) are added into DMF, wherein the ratio of the use amounts of the intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene and DMF is 0.15g:0.36g:4mL; after reaction is carried out at 130 DEG C for 84h, filtration is carried out to obtain a solid product, the solid product is washed by DMF and diethyl ether, and vacuum drying is carried out to obtain a functional monomer (the yield is 64.3%). The functional monomer obtained is subjected to 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).

[0023] (3) Acrylamide and functional monomer are dissolved in deionized water, the pH of the solution is adjusted to 8.5, under the nitrogen environment, initiator (ammonium sulfate and sodium bisulfite in a mass ratio of 2:1 mixed), chelating agent (ethylenediaminetetraacetic acid disodium), wherein the mass ratio of acrylamide, functional monomer, deionized water, initiator and chelating agent is 15:4:80.3:0.4:0.3; after 10h reaction at 70℃, the product is precipitated with anhydrous ethanol, vacuum dried, crushed, and obtained.

[0024] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in the embodiment comprises the following steps: weighing each raw material according to the proportion, dissolving the surfactant and surfactant aid in water first, then adding the zwitterionic hydrophobic associating polymer and stirring to dissolve, and obtaining.

[0025] Example 2 The embodiment relates to a temperature-resistant and salt-resistant composite oil displacement agent, which comprises, in percentage by weight, 0.2% of zwitterionic hydrophobic associating polymer, 0.6% of surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.2% of surfactant aid (5-norbornene-2-carboxylic acid), and the balance of water.

[0026] The preparation process of the zwitterionic hydrophobic associating polymer in the embodiment is as follows: (1) Under the protection of nitrogen, 3-bromopropanesulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate and tetrakis (triphenylphosphine) palladium are added into DMF, wherein the amount ratio of 3-bromopropanesulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate, tetrakis (triphenylphosphine) palladium and DMF is 1g:2.0g:4.0g:0.4g:75mL; after 72h reaction at 135℃, the solution is cooled to room temperature, the filtrate is obtained by filtration, the solvent is removed by reduced pressure distillation, and the intermediate 1 (with a yield of 55.3%) is obtained by silica gel column purification. 1 The HNMR is the same as that in Example 1.

[0027] (2) Under the protection of nitrogen, the intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene are added into DMF, wherein the amount ratio of the intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene and DMF is 0.15g:0.37g:5mL; after 72h reaction at 135℃, the solid product is obtained by filtration, washed with DMF and diethyl ether, and dried in vacuum to obtain the functional monomer (with a yield of 62.7%). The HNMR of the functional monomer is the same as that in Example 1. 1 The HNMR of the functional monomer is the same as that in Example 1.

[0028] (3) Acrylamide and functional monomer are dissolved in deionized water, the pH of the solution is adjusted to 8.5, under the nitrogen environment, initiator (ammonium sulfate and sodium bisulfite in a mass ratio of 2:1 mixed), chelating agent (ethylenediaminetetraacetic acid disodium), wherein 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℃ for 6h, the product is precipitated with anhydrous ethanol, vacuum dried and crushed to obtain the product.

[0029] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in the embodiment comprises the following steps: weighing each raw material according to the proportion, dissolving the surfactant and surfactant aid in water first, then adding the zwitterionic hydrophobic associating polymer and stirring to dissolve, and then obtaining the product.

[0030] Example 3 The embodiment relates to a temperature-resistant and salt-resistant composite oil displacement agent, which comprises, in percentage by weight, 0.05% of zwitterionic hydrophobic associating polymer, 0.1% of surfactant (fatty alcohol polyoxyethylene ether, BASF AEO-9), 0.05% of surfactant aid (5-norbornene-2-carboxylic acid), and the balance of water.

[0031] The preparation process of the zwitterionic hydrophobic associating polymer in the embodiment is as follows: (1) Under the protection of nitrogen, 3-bromopropanesulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate and tetrakis(triphenylphosphine) palladium are added into DMF, wherein the amount ratio of 3-bromopropanesulfonic acid sodium, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborinanyl) pyridine, potassium phosphate, tetrakis(triphenylphosphine) palladium and DMF is 1g:1.8g:3.5g:0.2g:50mL; after reacting at 125℃ for 96h, the mixture is cooled to room temperature, the filtrate is obtained by filtration, the solvent is removed by reduced pressure distillation, and the intermediate 1 (yield 54.6%) is obtained by silica gel column purification. 1 HNMR is the same as that in Example 1.

[0032] (2) Under the protection of nitrogen, the intermediate 1 and 2-bromo-3-(1-naphthyl)-1-propene are added into DMF, wherein the amount ratio of the intermediate 1, 2-bromo-3-(1-naphthyl)-1-propene and DMF is 0.15g:0.35g:3mL; after reacting at 125℃ for 96h, the solid product is obtained by filtration, washed with DMF and diethyl ether, and dried in vacuum to obtain the functional monomer (yield 61.4%). The functional monomer has the following properties: 1 HNMR is the same as that in Example 1.

[0033] (3) acrylamide and functional monomer are dissolved in deionized water, the pH of the solution is adjusted to 8.0, under the nitrogen environment, initiator (ammonium sulfate and sodium bisulfite with a mass ratio of 2:1 mixed), chelating agent (ethylenediaminetetraacetic acid disodium), wherein 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℃ for 12h, the product is precipitated with anhydrous ethanol, vacuum dried and crushed, and the product is obtained.

[0034] The preparation method of the temperature-resistant and salt-resistant composite oil displacement agent in the embodiment comprises the following steps: weighing each raw material according to the proportion, dissolving the surfactant and surfactant aid in water first, then adding the zwitterionic hydrophobic associating polymer and stirring to dissolve, and the product is obtained.

[0035] Comparative Example 1 The difference between the present comparative example and Example 1 is that the functional monomer in step (3) of preparing the zwitterionic hydrophobic associating polymer is omitted.

[0036] Comparative Example 2 The difference between the present comparative example and Example 1 is that the surfactant aid is omitted.

[0037] Test Example The composite oil displacement agents of Examples 1-3 and Comparative Examples 1-2 are prepared using simulated water with a salinity of 9500mg / L (wherein Na + +K + is 3000mg / L, Ca 2+ +Mg 2+ is 450mg / L), and the interfacial tension and viscosity of the composite oil displacement agents are determined according to SY / T6424-2014 “Performance Test Method of Composite Oil Displacement System”, and the results are shown in Table 1 as follows.

[0038] 1. The interfacial tension between the composite oil displacement agent and crude oil (reservoir temperature 40℃, viscosity 16mPa·s) is determined by the rotating drop method (45℃, interfacial tension instrument speed 5000r / min).

[0039] 2. The viscosity of the composite oil displacement agent is determined at 25℃.

[0040] 3. The composite oil displacement agent is aged at 75℃ for 90d, and the viscosity of the composite oil displacement agent before and after aging is determined respectively, and the viscosity retention rate after aging is calculated.

[0041] 4. The composite oil displacement agent is sheared at 75℃ at a shear rate of 7000r / min for 20s, and the viscosity of the composite oil displacement agent before and after shearing is determined respectively, and the viscosity retention rate after shearing is calculated.

[0042] Table 1 As can be seen from Table 1, the salt resistance and thermal stability of the composite oil displacement agents of Examples 1-3 of the present application are better than those of Comparative Examples 1-2. The reason is that the zwitterionic structure containing pyridinium cation and sulfonate anion and the naphthalene ring structure are introduced into the amphoteric hydrophobic associating polymer in the composite oil displacement agent of the present application, the salt resistance of the oil displacement agent is significantly enhanced by the electrostatic balance between the ions in the zwitterionic structure, and the thermal stability of the system under high temperature environment is effectively improved by the rigid naphthalene ring structure. The present application uses 5-norbornene-2-carboxylic acid as a surfactant additive, the carboxylic acid group forms a mixed adsorption layer with the surfactant and the zwitterionic structure in the polymer, and the norbornene hydrophobic skeleton produces hydrophobic synergy with the naphthalene ring structure in the polymer, both of which significantly reduce the oil-water interfacial tension and greatly improve the oil stripping capacity of the oil displacement agent on the rock surface crude oil, effectively improving the oil washing efficiency. At the same time, the bicyclo[2.2.1]heptene skeleton of 5-norbornene-2-carboxylic acid provides rigid support and forms a more compact three-dimensional network with the zwitterionic hydrophobic associating polymer, 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.

[0043] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application are within the scope of the present application.

Claims

1. A heat-resistant and salt-resistant composite oil-displacing agent, characterized in that: The heat-resistant and salt-resistant composite oil displacement agent comprises, by weight percentage, 0.05-0.2% of a zwitterionic hydrophobic associating polymer, 0.1-0.6% of a surfactant, 0.05-0.2% of a surfactant adjuvant, and the balance being water; The preparation process of the zwitterionic hydrophobically associating polymer is as follows: (1) Under nitrogen protection, sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-boryl)pyridine, potassium phosphate and tetrakis(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. (2) Under nitrogen protection, the 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 a functional monomer. (3) Dissolve acrylamide and functional monomers in deionized water, adjust the pH of the solution, add initiator and chelating agent under nitrogen environment, and after reaction, precipitate the product with anhydrous ethanol, dry and crush to obtain the product.

2. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: The surfactant is fatty alcohol polyoxyethylene ether; and the surfactant auxiliary is 5-norbornene-2-carboxylic acid.

3. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the step (1), the usage ratio of sodium 3-bromopropanesulfonate, 4-(4,4,5,5-tetramethyl-1,3,2-boryl)pyridine, potassium phosphate, tetrakis(triphenylphosphine)palladium, and DMF is 1 g: 1.8-2.0 g: 3.5-4.0 g: 0.2-0.4 g: 50-75 mL.

4. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the step (1), the reaction conditions are 125-135° C. for 72-96 hours.

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

6. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the step (2), the reaction conditions are 125-135° C. for 72-96 hours.

7. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the 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).

8. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the step (3), the pH of the solution is adjusted to 8.0-8.5; the reaction conditions are 60-75°C for 6-12 hours.

9. The heat-resistant and salt-resistant composite oil-displacing agent according to claim 1, characterized in that: In the step (3), the initiators are ammonium sulfate and sodium bisulfite, and the mass ratio of ammonium sulfate to sodium bisulfite is 2:1; and the chelating agent is disodium ethylenediaminetetraacetic acid.

10. The method for preparing the heat-resistant and salt-resistant composite oil-displacing agent according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: weighing various raw materials according to a proportion, first dissolving a surfactant and a surfactant auxiliary in water, and then adding a zwitterionic hydrophobic associating polymer and stirring to dissolve.

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