High-temperature-resistant oil displacement agent for oil fields and preparation method thereof

Abstract

The application discloses a high-temperature-resistant oil displacement agent for oil fields and a preparation method thereof, and relates to the technical field of oil field exploitation. The oil displacement agent for oil fields prepared by the application comprises the following raw materials in parts by weight: 15-25 parts of polyacrylamide, 1-5 parts of nano silicon dioxide, 25-35 parts of enhanced surfactant and 40-60 parts of water. The oil displacement agent is prepared by mixing and stirring the raw materials. The oil displacement agent has excellent oil displacement performance, low surface tension and excellent high-temperature resistance when used in the process of oil field exploitation. Compared with traditional surfactants, the introduction of the enhanced surfactant improves the high-temperature resistance and oil displacement efficiency of the oil displacement agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield exploitation, in particular to a high-temperature-resistant oil displacement agent for oilfields and a preparation method thereof. BACKGROUND

[0002] With the continuous growth of global energy demand and the increasing depletion of conventional oil resources, how to efficiently exploit the residual oil in developed oil reservoirs has become a severe challenge for the oil industry. Water flooding, as the main technology for secondary oil recovery, can maintain the formation energy, but its recovery rate is usually only 30% to 50%, and a large amount of crude oil remains in the formation pores due to capillary force. In order to improve the recovery rate of crude oil, chemical flooding, especially surfactant flooding, has become one of the core technologies for tertiary oil recovery. The basic principle is to add surfactants to the injected water to greatly reduce the interfacial tension (IFT) between oil and water and change the wettability of the reservoir rock, thereby stripping and starting the residual crude oil after water flooding, forming oil bands and driving them to the production well.

[0003] However, surfactant flooding technology faces great bottlenecks when applied to high-temperature reservoirs. There are a large number of deep reservoirs in China and around the world, and the formation temperature is often higher than 85℃, even reaching more than 120℃, with high salinity and divalent ion (such as Ca²⁺, Mg²⁺) content. Under such harsh conditions, traditional surfactants, such as conventional petroleum sulfonates, alkyl benzene sulfonates or nonionic surfactants, have inherent defects, such as poor thermal chemical stability, and the interfacial performance and wettability change ability fail at high temperatures. Therefore, developing a new type of oil displacement agent with high oil displacement efficiency and outstanding high-temperature stability has great practical significance and economic value for fully tapping the potential of deep oil and gas resources and improving the recovery rate of crude oil. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a high-temperature-resistant oil displacement agent for oilfields and a preparation method thereof.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] A high-temperature-resistant oil displacement agent for oilfields, comprising the following raw materials by weight: polyacrylamide 15-25 parts, nano-silicon dioxide 1-5 parts, enhanced surfactant 25-35 parts, and water 40-60 parts.

[0007] The enhanced surfactant is prepared by the following steps:

[0008] Step A1, uniformly mix 4-vinylphenol, sodium hydroxide and acetonitrile, slowly add trichlorocyanuric acid acetonitrile solution and stir uniformly, then stir in an ice water bath for 4h to obtain product 1 solution;

[0009] Further, the ratio of the amount of 4-vinylphenol, sodium hydroxide, acetonitrile and cyanuric chloride acetonitrile solution in step A1 is 0.01-0.03 mol:0.4-1.2 g:100 mL:100 mL;

[0010] Further, the cyanuric chloride acetonitrile solution in step A1 is prepared by mixing and stirring cyanuric chloride and acetonitrile in a ratio of 0.01-0.03 mol:100 mL;

[0011] In step A2, ethylenediamine, sodium hydroxide and acetonitrile are mixed and stirred uniformly to form a mixture 1. The product 1 solution is heated to 55°C, 1 / 2 volume of the mixture 1 is added, and the temperature is maintained for 4-6 h. The temperature is then increased to 90°C, the remaining mixture 1 is added, and the temperature is maintained for 12 h. Filtration, washing and drying yield the triazine derivative.

[0012] Further, the ratio of the amount of ethylenediamine, sodium hydroxide and acetonitrile in the mixture 1 in step A2 is 0.02-0.06 mol:0.8-2.4 g:100 mL.

[0013] In step A3, the triazine derivative and sodium 2-chloroethyl sulfonate are sequentially added to a reactor, water is added, and the temperature is increased to 90-95°C under nitrogen protection. The system is heated to reflux for 24 h while maintaining the pH at 9-10. After the reaction is completed, rotary evaporation, washing and drying yield the triazine-sodium sulfonate derivative.

[0014] Further, the molar ratio of the triazine derivative and sodium 2-chloroethyl sulfonate in step A3 is 1:2.

[0015] Further, in step A3, a 0.1 mol / L sodium hydroxide solution is used to maintain the pH of the system at 9-10.

[0016] In step A4, the triazine-sodium sulfonate derivative is mixed and stirred in water and heated to 60°C. A chloroplatinic acid solution is added and stirred for 10-20 min. Then, heptamethyltrisiloxane is added and stirred for 30 min. The temperature is increased to 100-120°C for reflux stirring for 5-7 h. Chloroform is added for dilution, and activated carbon is added to remove the remaining catalyst. Distillation under reduced pressure and drying yield the enhanced surfactant.

[0017] Further, the ratio of the amount of triazine-sodium sulfonate derivative, water, chloroplatinic acid solution, heptamethyltrisiloxane, chloroform and activated carbon in step A4 is 0.02 mol:100 mL:0.25-0.35 mL:0.02 mol:30 mL:5-10 g.

[0018] Further, the chloroplatinic acid solution in step A4 is prepared by mixing and stirring chloroplatinic acid, isopropyl alcohol and water in a ratio of 0.001 mol:3 mL:2 mL.

[0019] A preparation method of a high-temperature-resistant oil displacement agent for oil fields comprises the following steps:

[0020] The raw materials are weighed by weight parts, the enhanced surfactant is added into water and mixed and stirred for 15-25 min, the polyacrylamide is added and stirred for 30 min, and finally the nano silicon dioxide is added and stirred for 10 min, and then ultrasonic treatment is carried out for 2 h, so that the high-temperature-resistant oil displacement agent for oil fields is obtained.

[0021] The beneficial effects of the present application are:

[0022] The oil displacement agent for oil fields prepared by the present application is mixed and stirred by polyacrylamide, enhanced surfactant, nano silicon dioxide and water, and has excellent oil displacement performance, low surface tension and excellent high-temperature resistance when used in the oil field exploitation process; wherein, compared with the traditional surfactant, the introduction of the enhanced surfactant improves the high-temperature resistance and oil displacement efficiency of the oil displacement agent.

[0023] The enhanced surfactant prepared by the present application is prepared by taking triazine structure as a "bridge", and then grafting benzene ring, -Si-(CH3)3 and sodium sulfonate structure; wherein, the sodium sulfonate structure provides strong hydrophilicity, so that the molecule can be firmly anchored in the water phase, the benzene ring, -Si-(CH3)3 and sodium sulfonate structure provide strong hydrophobicity, this "one end hydrophilic and one end hydrophobic" amphiphilic structure enables it to be enriched on the oil-water interface, the hydrophobic group penetrates into the oil phase, and the hydrophilic group remains in the water phase, thereby effectively reducing the interfacial tension between oil and water, this surfactant can stabilize these oil droplets to form oil-in-water emulsion, prevent small oil droplets from re-coalescing into large oil beads to block pores again, and thus greatly improve the oil recovery. Ordinary surfactants will quickly degrade or fail in high-temperature (such as >85℃) reservoirs, while the enhanced structure in the present application endows it with excellent thermal stability, because the triazine ring structure is an aromatic heterocyclic structure with excellent thermal stability, its chemical bond energy is high, and a very high energy is required to break it, so it is very resistant to thermal decomposition, and the Si-C bond and Si-O bond contained therein both have high bond energy and good thermal stability, and the benzene ring is a classic aromatic ring structure, its resonance effect makes it very stable and not prone to ring-opening or degradation reaction at high temperature, which ensures the structural integrity of the surfactant at high temperature. In addition, the nitrogen atom on the triazine ring has a lone pair of electrons, which can form a coordination with metal ions on the surface of rocks (such as clay minerals), or form a hydrogen bond with the surface hydroxyl group, this strong adsorption effect is equivalent to "anchoring" the surfactant molecules on the surface of the rock, greatly reducing the desorption rate under the scouring of high-temperature water flow, thereby prolonging the effective period. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] Embodiment 1: The enhanced surfactant is prepared by the following steps:

[0026] Step A1, 0.01 mol of 4-vinyl phenol, 0.4 g of sodium hydroxide and 100 mL of acetonitrile are uniformly mixed and stirred, then slowly added into 100 mL of cyanuric chloride acetonitrile solution and uniformly stirred, and then placed in an ice water bath and stirred for 4 h to obtain a product 1 solution. The cyanuric chloride acetonitrile solution is prepared by mixing and stirring cyanuric chloride and acetonitrile in a ratio of 0.01 mol:100 mL;

[0027] Step A2, 0.02 mol of ethylenediamine, 0.8 g of sodium hydroxide and 100 mL of acetonitrile are uniformly mixed and stirred to obtain a mixed solution 1; the product 1 solution is heated to 55°C, then 50 mL of the mixed solution 1 is added, and the temperature is maintained for 4 h, then the temperature is increased to 90°C, the remaining 50 mL of the mixed solution 1 is added, and the temperature is maintained for 12 h, and then the product is filtered, washed and dried to obtain a triazine derivative;

[0028] Step A3, 0.1 mol of the triazine derivative and 0.2 mol of 2-chloroethyl sulfonate sodium are sequentially added into a reactor, 200 mL of water is added, and the temperature is increased to 90°C under nitrogen protection, and then heated to reflux for 24 h, and 0.1 mol / L sodium hydroxide solution is used to maintain the pH of the system at 9. After the reaction is completed, the product is rotary evaporated, washed and dried to obtain a triazine-sulfonate sodium derivative;

[0029] Step A4, 0.02 mol of the triazine-sulfonate sodium derivative is uniformly mixed and stirred in 100 mL of water, heated to 60°C, then 0.25 mL of chloroplatinic acid solution is added and stirred for 10 min, then 0.02 mol of heptamethyltrisiloxane is added and stirred for 30 min, then the temperature is increased to 100°C and refluxed for 5 h, then 30 mL of chloroform is added for dilution, 5 g of activated carbon is added to remove the remaining catalyst, and then the product is distilled under reduced pressure and dried to obtain an enhanced surfactant. The chloroplatinic acid solution is prepared by mixing and stirring chloroplatinic acid, isopropyl alcohol and water in a ratio of 0.001 mol:3 mL:2 mL.

[0030] Embodiment 2: The enhanced surfactant is prepared by the following steps:

[0031] Step Al, 0.02 mol 4-vinylphenol, 0.8 g sodium hydroxide and 100 mL acetonitrile were mixed and stirred uniformly, then slowly added into 100 mL cyanuric chloride acetonitrile solution which was stirred uniformly, and then placed in an ice water bath and stirred for 4 h to obtain a product 1 solution. The cyanuric chloride acetonitrile solution was prepared by mixing cyanuric chloride and acetonitrile in a ratio of 0.02 mol:100 mL;

[0032] Step A2, 0.04 mol ethylenediamine, 1.6 g sodium hydroxide and 100 mL acetonitrile were mixed and stirred uniformly to obtain a mixed solution 1. The product 1 solution was heated to 55°C, then 50 mL of the mixed solution 1 was added, and the temperature was maintained for 5 h. The temperature was then increased to 90°C, and the remaining 50 mL of the mixed solution 1 was added. The temperature was maintained for 12 h. After filtration, washing and drying, a triazine derivative was obtained.

[0033] Step A3, 0.1 mol triazine derivative and 0.2 mol 2-chloroethyl sodium sulfonate were sequentially added to a reactor, 200 mL water was added, and the temperature was increased to 95°C under nitrogen protection. The system was heated to reflux for 24 h, and 0.1 mol / L sodium hydroxide solution was used to maintain the pH at 9.5. After the reaction was completed, rotary evaporation, washing and drying were performed to obtain a triazine-sodium sulfonate derivative.

[0034] Step A4, 0.02 mol triazine-sodium sulfonate derivative was mixed with 100 mL water and heated to 60°C. Then 0.3 mL chloroplatinic acid solution was added and stirred for 15 min. Then 0.02 mol heptamethyltrisiloxane was added and stirred for 30 min. The temperature was increased to 110°C and refluxed for 6 h. Then 30 mL chloroform was added for dilution, and 7.5 g activated carbon was added to remove the remaining catalyst. After vacuum distillation and drying, an enhanced surfactant was obtained. The chloroplatinic acid solution was prepared by mixing chloroplatinic acid, isopropyl alcohol and water in a ratio of 0.001 mol:3 mL:2 mL.

[0035] Example 3: The enhanced surfactant was prepared by the following steps:

[0036] Step Al, 0.03 mol 4-vinylphenol, 1.2 g sodium hydroxide and 100 mL acetonitrile were mixed and stirred uniformly, then slowly added into 100 mL cyanuric chloride acetonitrile solution which was stirred uniformly, and then placed in an ice water bath and stirred for 4 h to obtain a product 1 solution. The cyanuric chloride acetonitrile solution was prepared by mixing cyanuric chloride and acetonitrile in a ratio of 0.03 mol:100 mL;

[0037] Step A2, 0.06 mol ethylenediamine, 2.4 g sodium hydroxide and 100 mL acetonitrile were mixed and stirred uniformly to form a mixture 1; the solution of product 1 was heated to 55℃, then 50 mL of mixture 1 was added, and the temperature was maintained for 6 h, then the temperature was increased to 90℃, the remaining 50 mL of mixture 1 was added, and the temperature was maintained for 12 h, then it was filtered, washed and dried to obtain a triazine derivative;

[0038] Step A3, 0.1 mol triazine derivative and 0.2 mol 2-chloroethyl sulfonate sodium were sequentially added to a reactor, 200 mL water was added, and the temperature was increased to 95℃ under nitrogen protection, and heated to reflux for 24 h, and 0.1 mol / L sodium hydroxide solution was used to maintain the pH of the system at 10, after the reaction was completed, it was rotary evaporated, washed and dried to obtain a triazine-sulfonate sodium derivative;

[0039] Step A4, 0.02 mol triazine-sulfonate sodium derivative was mixed and stirred in 100 mL water, and heated to 60℃, then 0.35 mL chloroplatinic acid solution was added and stirred for 20 min, then 0.02 mol heptamethyltrisiloxane was added and stirred for 30 min, then the temperature was increased to 120℃ and refluxed for 7 h, then it was diluted with 30 mL chloroform, 10 g activated carbon was added to remove the remaining catalyst, and then it was distilled under reduced pressure and dried to obtain an enhanced surfactant, the chloroplatinic acid solution was prepared by mixing chloroplatinic acid, isopropyl alcohol and water in a ratio of 0.001 mol:3 mL:2 mL.

[0040] Example 4: A preparation method of a high-temperature-resistant oil displacement agent for oil fields comprises the following steps:

[0041] Polyacrylamide 15 parts, nano-silicon dioxide 1 part, enhanced surfactant prepared in Example 1 25 parts, water 40 parts;

[0042] The raw materials were weighed by weight parts, the enhanced surfactant prepared in Example 1 was added to water and stirred for 15 min, then polyacrylamide was added and stirred for 30 min, and finally nano-silicon dioxide was added and stirred for 10 min, and then it was ultrasonically treated for 2 h to obtain a high-temperature-resistant oil displacement agent for oil fields.

[0043] Example 5: A preparation method of a high-temperature-resistant oil displacement agent for oil fields comprises the following steps:

[0044] Polyacrylamide 20 parts, nano-silicon dioxide 3 parts, enhanced surfactant prepared in Example 2 30 parts, water 50 parts;

[0045] The raw materials are weighed by weight parts, the enhanced surfactant prepared in Example 2 is added into water and mixed and stirred for 20 min, then polyacrylamide is added and stirred for 30 min, finally nano-silicon dioxide is added and stirred for 10 min, and then ultrasonic treatment is carried out for 2 h, thereby obtaining the high-temperature-resistant oil displacement agent for oil fields.

[0046] Example 6: A preparation method of a high-temperature-resistant oil displacement agent for oil fields comprises the following steps:

[0047] 25 parts of polyacrylamide, 5 parts of nano-silicon dioxide, 35 parts of the enhanced surfactant prepared in Example 3, and 60 parts of water;

[0048] The raw materials are weighed by weight parts, the enhanced surfactant prepared in Example 3 is added into water and mixed and stirred for 25 min, then polyacrylamide is added and stirred for 30 min, finally nano-silicon dioxide is added and stirred for 10 min, and then ultrasonic treatment is carried out for 2 h, thereby obtaining the high-temperature-resistant oil displacement agent for oil fields.

[0049] Comparative Example 1: The comparative example is an oil displacement agent for oil fields, which is different from Example 6 in that the enhanced surfactant prepared in Example 3 is replaced by fatty acid alkanolamide, and the rest are the same.

[0050] Comparative Example 2: The comparative example is an oil displacement agent for oil fields, which is different from Example 6 in that the enhanced surfactant prepared in Example 3 is replaced by dodecyl benzene sulfonic acid, and the rest are the same.

[0051] The oil displacement agents for oil fields prepared in Examples 4-6 and Comparative Examples 1-2 are subjected to performance tests:

[0052] Interface tension performance test: the oil displacement agents for oil fields in each example and comparative example are diluted to 0.3 wt% with reinjection water, and the oil-water interfacial tension of the oil displacement agent and simulated oil at 80℃ is determined by rotary drop interfacial measurement;

[0053] High-temperature resistance performance test: the oil displacement agents for oil fields in each example and comparative example are respectively aged at 90℃, 100℃, 120℃ and 140℃ for 48 h, and then the surface tension of the solution is tested after aging;

[0054] The test results are shown in Table 1:

[0055] Table 1: Performance test results

[0056]

[0057] As can be seen from Table 1, the oil displacement agent prepared in the application still has a lower surface tension at high temperature, which shows that the use of the oil displacement agent in the oil field exploitation process has better environmental adaptability compared with the use of the traditional oil displacement agent, can adapt to higher temperature, and can maintain excellent oil displacement efficiency at high temperature.

[0058] The above merely illustrates and explains the concept of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or replace them with similar ways without departing from the scope defined by the concept of the present application, and all of them shall fall within the protection scope of the present application.

Claims

1. A high-temperature resistant oil displacement agent for oil fields, characterized by comprising: The raw materials include the following components by weight: polyacrylamide 15-25 parts, nano-silicon dioxide 1-5 parts, enhanced surfactant 25-35 parts, and water 40-60 parts; The enhanced surfactant is prepared by the following steps: Step A1, 4-vinyl phenol, sodium hydroxide and acetonitrile are mixed and stirred uniformly, then slowly added into the cyanuric chloride acetonitrile solution and stirred uniformly, and then placed in an ice water bath and stirred for 4 hours to obtain product 1 solution; Step A2, ethylenediamine, sodium hydroxide and acetonitrile are mixed and stirred uniformly to obtain a mixed solution 1; the product 1 solution is heated to 55°C, then 1 / 2 volume of the mixed solution 1 is added, and the temperature is maintained for 4-6 hours, then the temperature is increased to 90°C, the remaining mixed solution 1 is added, and the temperature is maintained for 12 hours, then filtered, washed and dried to obtain a triazine derivative, wherein the amount of 4-vinyl phenol, cyanuric chloride and ethylenediamine in step A1 is 0.01-0.03 mol: 0.01-0.03 mol: 0.02-0.06 mol; Step A3, the triazine derivative and 2-chloroethyl sulfonate sodium are sequentially added into a reactor, then water is added, and the temperature is increased to 90-95°C under nitrogen protection, and heated to reflux for 24 hours, and the pH of the system is maintained at 9-10, after the reaction is completed, rotary evaporation, washing and drying are performed to obtain a triazine-sulfonate sodium derivative, wherein the molar ratio of the triazine derivative and 2-chloroethyl sulfonate sodium is 1:2; Step A4, the triazine-sulfonate sodium derivative is mixed and stirred in water, and heated to 60°C, then a chloroplatinic acid solution is added and stirred for 10-20 minutes, then heptamethyltrisiloxane is added and stirred for 30 minutes, then the temperature is increased to 100-120°C and refluxed for 5-7 hours, then diluted with chloroform, and activated carbon is added to remove the remaining catalyst, then distilled under reduced pressure, and dried to obtain the enhanced surfactant.

2. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, The amount ratio of 4-vinyl phenol, sodium hydroxide, acetonitrile and cyanuric chloride acetonitrile solution in step A1 is 0.01-0.03 mol: 0.4-1.2 g: 100 mL: 100 mL.

3. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, The cyanuric chloride acetonitrile solution in step A1 is prepared by mixing and stirring cyanuric chloride and acetonitrile in an amount ratio of 0.01-0.03 mol: 100 mL.

4. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, The amount ratio of ethylenediamine, sodium hydroxide and acetonitrile in the mixed solution 1 in step A2 is 0.02-0.06 mol: 0.8-2.4 g: 100 mL.

5. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, In step A3, a 0.1 mol / L sodium hydroxide solution is used to maintain the pH of the system at 9-10.

6. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, The amount ratio of triazine-sulfonate sodium derivative, water, chloroplatinic acid solution, heptamethyltrisiloxane, chloroform and activated carbon in step A4 is 0.02 mol: 100 mL: 0.25-0.35 mL: 0.02 mol: 30 mL: 5-10 g.

7. The high-temperature resistant oil displacement agent for oilfields according to claim 1, characterized by, The chloroplatinic acid solution in step A4 is prepared by mixing and stirring chloroplatinic acid, isopropyl alcohol and water in an amount ratio of 0.001 mol: 3 mL: 2 mL.

8. A method for preparing a high-temperature resistant oil displacement agent for oilfields according to any one of claims 1-7, characterized in that, The following steps are included: The raw materials are weighed by weight parts, the enhanced surfactant is added into water and mixed and stirred for 15-25 min, the polyacrylamide is added and stirred for 30 min, finally the nano silicon dioxide is added and stirred for 10 min, and then ultrasonic treatment is carried out for 2 h, and the high-temperature-resistant oil displacement agent for oil field is obtained.

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