CN113025297B - A kind of temperature-resistant and salt-resistant low-tension foam oil-displacing agent and its preparation method and application - Google Patents

Abstract

The invention discloses a temperature-resistant, salt-resistant and low-tension foam oil-displacing agent. The foam oil-displacing agent mainly contains fatty alcohol polyoxyethylene ether carboxylate and also contains fatty alcohol polyoxyethylene ether. The product has excellent oil-water interface properties and outstanding foam performance, especially suitable for foam flooding technology in the field of tertiary oil recovery. The invention also discloses a preparation method of the foam oil-displacing agent. The entire synthesis process of the method is continuously completed in one reaction kettle, without any additional separation and purification process, and directly forms an end product, which has the advantages of simple process, economy and environmental friendliness. Etc. The invention also discloses the application of the foam oil-displacing agent.

Description

A kind of temperature-resistant and salt-resistant low-tension foam oil-displacing agent and its preparation method and application

technical field

The invention relates to the field of tertiary oil recovery. More specifically, it relates to a temperature-resistant and salt-resistant low-tension foam oil-displacing agent and its preparation method and application.

Background technique

In the development of oil and gas fields, the use of surfactants to flood oil is an important method to enhance oil recovery. However, in high temperature and high water salinity reservoirs, neither anionic nor nonionic surfactants alone can meet the requirements of oil displacement. Because the anionic surfactant itself is not salt-tolerant, the formation water mineralization is too high, which will cause the precipitation of the surfactant. Nonionic surfactants have a cloud point, and formation temperatures above the cloud point will also cause surfactant precipitation.

In some prior art, there is a carboxymethylation process to produce high-grade ether carboxylates. In the carboxylation step, sodium hydroxide solution is used, and the water in the reaction system is removed by vacuum operation at 100-130° C. to prepare ether sodium compound (one of the raw materials used is sodium hydroxide solution) to improve the reaction efficiency. The energy consumption of vacuum operation is high, and the tightness of equipment is required. Especially because chloroacetic acid is extremely corrosive, the general stainless steel material is not durable. In the high vacuum operation, the distilled water carries acid mist, which causes corrosion to the pipeline.

However, compared with the anionic surfactants commonly used in oil field tertiary oil recovery, the price of anionic-nonionic fatty alcohol polyoxyethylene ether carboxylate is high, and the oil field tertiary oil recovery amount is large, which increases the cost of production.

Therefore, there is a need to provide a low-tension foam oil-displacing agent that can be used for tertiary oil recovery in oilfields, has low production cost, and has temperature resistance and salt resistance.

SUMMARY OF THE INVENTION

Based on the above problems, the first object of the present invention is to provide a temperature-resistant and salt-resistant low-tension foam oil-displacing agent. The foam oil displacement agent is an alkali-free system and is suitable for tertiary oil recovery in oil fields.

The second object of the present invention is to provide a preparation method of a temperature-resistant and salt-resistant low-tension foam oil-displacing agent. The preparation method is simple and low in cost, and the prepared product does not need to undergo post-processing steps such as purification. It is a "one-pot" green chemical synthesis process, which can be well used in tertiary oil recovery in oil fields and has good effects .

The third object of the present invention is to provide the application of a temperature-resistant and salt-resistant low-tension foam oil-displacing agent.

For reaching above-mentioned first purpose, the present invention adopts following technical scheme:

A temperature-resistant and salt-resistant low-tension foam oil-displacing agent, the foam oil-displacing agent mainly contains fatty alcohol polyoxyethylene ether carboxylate; meanwhile, it also contains fatty alcohol polyoxyethylene ether.

In the above technical scheme of the present invention, fatty alcohol polyoxyethylene ether carboxylate has excellent temperature resistance and salt resistance, which is an anionic-nonionic surfactant, and in its same molecular structure, it contains both anionic functional groups It also contains a non-ionic functional group, which combines the advantages of both and overcomes the respective shortcomings of anionic and non-ionic surfactants; fatty alcohol polyoxyethylene ether is easily soluble in water, and has strong resistance to hard water and good emulsification. , when it is compounded with fatty alcohol polyoxyethylene ether carboxylate with good temperature resistance and salt resistance, it has obvious synergistic effect and effectively improves the foam stability of fatty alcohol polyoxyethylene ether carboxylate; both The combination is not only low cost, but also can form a stable temperature-resistant, salt-resistant and low-tension foam flooding system, which can be used for tertiary oil recovery in oil fields.

In the present invention, the foam oil displacement agent is an alkali-free system, which can generate low interfacial tension without adding alkali, which overcomes the general oil displacement surfactant system, usually adding alkali (sodium bicarbonate, sodium carbonate or Sodium hydroxide) to reduce the oil-water interfacial tension, and the alkali has a dissolving effect on the rocks and minerals in the formation, causing serious scaling in the treatment system of the combined station and affecting the normal operation of crude oil production.

Further, in the foam oil displacing agent, the total content of fatty alcohol polyoxyethylene ether carboxylate and fatty alcohol polyoxyethylene ether is greater than 55 wt%; and the fatty alcohol polyoxyethylene ether carboxylate and fatty alcohol The mass ratio of polyoxyethylene ether is 13:1 to 7:1. Under this condition, the obtained foam oil displacing agent has better stability, temperature resistance, salt resistance and low tension performance.

Further preferably, the foam oil displacing agent contains 50-65 wt % fatty alcohol polyoxyethylene ether carboxylate in terms of mass percentage.

Further preferably, the foam oil-displacing agent contains 4-7wt% fatty alcohol polyoxyethylene ether in terms of mass percentage.

Further, the foam oil-displacing agent also contains glycolate, for example, sodium glycolate and the like.

Further preferably, the foam oil-displacing agent, in terms of mass percentage, contains 15-25% by weight of glycolic acid salt.

Further, the foam oil-displacing agent also includes water, sodium chloride, and the like.

Further preferably, the foam oil-displacing agent contains 12-16 wt % sodium chloride in terms of mass percentage.

Further preferably, the foam oil displacing agent contains 6-8 wt % water in terms of mass percentage.

In the above technical solution, "mainly containing" means that the mass percentage is greater than or equal to 50% and less than 100%.

Further, the chemical formula of the fatty alcohol polyoxyethylene ether is: R ₁ O(CH ₂ CH ₂ O) _n1 H, wherein R ₁ is an alkyl group of C ₁₀ -C ₂₀ , and n1 is selected from the normal group of 1-10 Integer.

Further, in the chemical formula of the fatty alcohol polyoxyethylene ether, R is a C ₁₂ -C ₁₆ alkyl group, and n is a positive integer from 3 to 6. For example, the fatty alcohol polyoxyethylene ether includes, but is not limited to, dodecyl alcohol polyoxyethylene ether, tetradecyl alcohol polyoxyethylene ether, cetyl alcohol polyoxyethylene ether, and the like.

Further, the chemical formula of the fatty alcohol polyoxyethylene ether carboxylate is: R ₂ O(CH ₂ CH ₂ O) _{n 2} CH ₂ COOM, wherein R ₂ is an alkyl group of C ₁₀ to C ₂₀ , and n 2 is selected from 1 A positive integer in ~10, M is selected from metal potassium or sodium ion; wherein, the above-mentioned R ₁ and R ₂ are the same or different, and the above-mentioned n1 and n2 are the same or different.

Further, the R ₁ and R ₂ are the same, and both are alkyl groups described in C ₁₂ -C ₁₆ , n1 and n2 are the same, and are selected from the positive integers of 3-6. At this time, R ₁ and R ₂ are matched with n1 and n2, respectively, and the obtained foam oil displacing agent has better performance.

In order to achieve above-mentioned second purpose, the present invention adopts following technical scheme:

A preparation method of a temperature-resistant and salt-resistant low-tension foam oil-displacing agent, comprising the following steps:

Under the condition of the presence of solid alkali, the fatty alcohol polyoxyethylene ether is subjected to alkalization reaction;

The solid chloroacetic acid is added to the system obtained after the above alkalization reaction, and the carboxymethylation reaction is carried out.

And the study found that if fatty alcohol polyoxyethylene ether, solid base and chloroacetic acid were reacted under equimolar conditions, the yield of fatty alcohol polyoxyethylene ether carboxylate was lower (about 60-70%), and the In this case, the properties of the obtained product cannot meet the requirements of the present invention for the properties of the foam oil-displacing agent. Further, the gram equivalent ratio of the fatty alcohol polyoxyethylene ether to the solid base is 1:2.8-4; the molar ratio of the fatty alcohol polyoxyethylene ether to the solid chloroacetic acid is 1:1.4-2. Under this condition, in the above preparation method, in the system obtained after alkalization reaction and carboxymethylation reaction, the alkyl alcohol polyoxyethylene ether can be converted into the corresponding sodium alkoxide as much as possible (but not completely), At the same time, under strong alkaline conditions, the yield of alkyl alcohol polyoxyethylene ether carboxylate is improved; further, the excess solid alkali in the alkalization reaction is all neutralized and reacted with the generated alkyl alcohol ether carboxylic acid. Reaction with chloroacetic acid equivalents yields the corresponding sodium glycolate and water.

Therefore, the obtained foam oil displacing agent mainly contains fatty alcohol polyoxyethylene ether carboxylate; meanwhile, it also contains a small part of unreacted fatty alcohol polyoxyethylene ether. The unreacted raw material-non-fatty alcohol polyoxyethylene ether is just compatible with the product fatty alcohol polyoxyethylene ether carboxylate, and a simple and practical process preparation method and mild reaction conditions are adopted to make full use of the unreacted material to realize the At the same time, while improving the foam stability of the obtained foam oil displacing agent, it also endows it with characteristics such as stable temperature resistance, salt resistance and low tension.

Generally, in addition to chloroacetic acid, sodium chloroacetate can also be used for the carboxymethylation of fatty alcohol polyoxyethylene ether. However, sodium chloroacetate is a solid powder, and dust is generated during the addition process, which is prone to explosion. In addition, chloroacetic acid has a low melting point and can be liquefied. , and sodium chloroacetate cannot be liquefied, so it is not suitable for the preparation method in the present invention.

In addition, in the above-mentioned preparation method, the alkali and chloroacetic acid in the alkalization reaction and the carboxymethylation reaction process all adopt the mode of direct solid feeding, and the whole synthesis process is continuously completed in a reactor without any additional separation and The purification process directly forms the final product, which has the advantages of simple process, economical and environmental friendliness. At the same time, the product has excellent oil-water interface properties and outstanding foam performance, especially suitable for foam flooding technology in the field of tertiary oil recovery.

Further, the solid alkali is one or more of solid sodium hydroxide and potassium hydroxide.

Further, the condition of described alkalization reaction is:

At a temperature of 50-90°C, under stirring conditions, a solid base is added to the fatty alcohol polyoxyethylene ether, then heated to 70-80°C, and the reaction is carried out at this temperature for 1-2 hours. In this step, after the solid alkali is added, the alkalization reaction is violent at the beginning, and a lot of heat is released, so the temperature range is wide. After the alkali is added, the reaction speed is slowed down, and the heat release is slow. It is necessary to heat to keep the temperature of the reaction system stable, so Set the heating temperature at 70-80°C.

Further, the condition of described carboxymethylation reaction is:

The temperature of the system obtained after the alkalization reaction is controlled to be 50-80°C, solid chloroacetic acid is added under stirring conditions, the temperature is heated to 75-90°C, and the reaction is performed at a constant temperature for 2-5 hours.

In order to achieve the above-mentioned third purpose, the present invention adopts following technical scheme:

Application of the temperature-resistant, salt-resistant and low-tension foam oil-displacing agent described in the first object above or the temperature-resistant, salt-resistant and low-tension foam oil-displacing agent prepared by the preparation method described in the second object above in tertiary oil recovery in oilfields .

Further, the amount of the temperature-resistant and salt-resistant low-tension foam oil displacement agent is 1.0%-0.3% of the mass of the foam displacement fluid.

Further, the application conditions include: the formation temperature is lower than 100° C., the salinity is lower than 3×10 ⁴ ppm, and the calcium and magnesium ion concentrations are lower than 1000 ppm.

Unless otherwise specified, the raw materials used in the present invention can be obtained from commercial sources, or prepared by conventional methods known in the art.

The beneficial effects of the present invention are as follows:

1) The foam oil-displacing agent of the present invention has excellent oil-water interface properties and outstanding foam performance. The invention is completely aimed at the use characteristics of the oil field, and is a process formulated according to the requirement of the tertiary oil recovery on the high efficiency of the foaming agent. Pay full attention to the compatibility of unreacted raw materials and various by-products as auxiliary agents. In this process, the unreacted fatty alcohol polyoxyethylene ether is an effective cosurfactant, which remains in the reaction system to improve the foaming ability and foam stability of the foaming agent, and has a good synergistic effect. This process adopts mild reaction conditions: normal pressure operation and lower reaction temperature of 60-80°C. The properties of the synthesized products under these conditions fully meet the requirements for use.

2) In the preparation method of the present invention, the step of removing vacuum operation is changed to normal pressure operation, which reduces equipment investment, reduces energy consumption and reduces the corrosive effect on pipeline equipment.

3) in the preparation method of the present invention, the feeding method of the solid alkali is used to replace the aqueous sodium hydroxide solution, and the bulk reaction of the raw material is adopted, and the amount of water generated in the reaction is very little, and does not need to be removed in a vacuum, and it is retained to help the unreacted water. The chloroacetic acid is hydrolyzed to harmless sodium glycolate. Therefore, when the above reaction mixture is used in oil fields, it is non-toxic, harmless and pollution-free.

4) The product of the preparation method of the present invention does not contain alkali, the alkali has been fully consumed in the process, and the product will not cause formation damage when used in oil fields.

5) Use solid chloroacetic acid instead of sodium chloroacetate. The advantage of solid chloroacetic acid over sodium chloroacetate is that chloroacetic acid does not produce dust, and the chloroacetic acid dust generated during the addition process will cause harm to the body of the operator, while chloroacetic acid will not produce dust. Sodium dust is easy to cause explosion, and chloroacetic acid can overcome the above shortcomings.

6) In the whole production process, there is no need to add any solvent, and no separation and purification process is required. All raw materials are fully utilized, and real zero discharge is achieved. At the same time, the prepared product has the above-mentioned excellent properties. Oil displacement.

7) Fatty alcohol polyoxyethylene ether carboxylate is a new variety of "green" surfactants recognized internationally. OECD experiments have shown that its average degradable rate is greater than 90%. The process and the agent are non-toxic, harmless and pollution-free, and the reaction product has zero emission, realizing the concept of atomic economic reaction, environment-friendly chemical reaction and green chemistry.

Description of drawings

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

Figure 1 shows the infrared spectrum of dodecyl alcohol polyoxyethylene ether in the product system obtained in Example 1.

Figure 2 shows the infrared spectrum of sodium dodecyl alcohol polyoxyethylene ether carboxylate in the product system obtained in Example 1.

Figure 3 shows the infrared spectrum of sodium glycolate in the product system obtained in Example 1.

4 shows the ¹ H-NMR nuclear magnetic spectrum of dodecyl alcohol polyoxyethylene ether in the product system obtained in Example 1.

5 shows the ¹ H-NMR nuclear magnetic spectrum of sodium dodecyl alcohol polyoxyethylene ether carboxylate in the product system obtained in Example 1.

6 shows the ¹ H-NMR nuclear magnetic spectrum of sodium glycolate in the product system obtained in Example 1.

Figure 7 shows the oil-water interfacial tension between each product mass concentration 0.5%+5% NaCl solution and Shengli crude oil in Examples 1-4.

Detailed ways

In order to illustrate the present invention more clearly, the present invention will be further described below with reference to the preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

In each of the following examples, the numbers in parentheses of the alkyl alcohol polyoxyethylene ether represent the number of units of polyoxyethylene in the alkyl alcohol polyoxyethylene ether.

Example 1

1) the alkalizing reaction of dodecyl alcohol polyoxyethylene ether (3):

Add 318g (1mol) of dodecyl alcohol polyoxyethylene ether (3) to the reaction kettle with heating, temperature control and electric stirring device, heat up to about 70°C, stir 120g (3.0 mol) solid sodium hydroxide is slowly added in the reactor, after feeding is completed, be warming up to about 75 ℃, continue to react for about 2 hours at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system is lowered to about 55 ° C, and 141.8g (1.5mol) of solid chloroacetic acid is slowly added to the reaction kettle with a screw feeder under constant stirring, and after the feeding is completed, Heating and raising the temperature to about 80° C., and continuing the constant temperature reaction for about 4 hours to obtain a temperature-resistant, salt-resistant and low-tension foaming agent, the conversion rate of dodecyl alcohol polyoxyethylene ether (3) is 92.1%. Purified and directly used as low tension foam oil displacement agent for tertiary oil recovery.

The main components of the obtained product are: sodium lauryl alcohol polyoxyethylene ether carboxylate (3), sodium glycolate, sodium chloride, water and unreacted lauryl alcohol polyoxyethylene ether (3). The mass percentages are: 54.1%, 18.7%, 15.1%, 7.8% and 4.3%, respectively.

Note: Since the product is a mixture of several compounds, the compounds in the product cannot be characterized if the existing spectral methods are used directly, so we have specially established a method for qualitative and quantitative detection of the compounds, using high-performance liquid chromatography. Reversed-phase chromatography, the specific detection method is: the instrument is a high-performance liquid phase chromatograph, the chromatographic column is a C18 reversed-phase chromatographic separation column, the detector is an evaporative light scattering instrument, and the evaporative gas is high-pressure dry air; chromatographic conditions: flow The phase is a mixed solvent of chromatographic methanol and ultrapure water (volume ratio is 3:97 to 7:93), the mobile phase velocity is 2ml/min, the column temperature is 25°C, the injection volume is 20ul, the evaporator temperature is 60°C, and the air The flow rate is 2.5l/min; the operation process: using the known raw material of alkyl alcohol polyoxyethylene ether and the separation and purification of alkyl alcohol polyoxyethylene ether carboxylate as the standard sample, the standard sample is obtained under certain chromatographic separation conditions. The peak time is obtained, and the standard curve of the concentration of the standard sample and the peak area of the standard sample is made. Next, the foam agent synthesized in the embodiment is prepared into a sample of a certain concentration, and then the liquid chromatograph is used for separation and determination, and combined with the standard sample The standard curve of each component in the sample and the corresponding content can be obtained.

Qualitative analysis: Figures 1-6 are the spectra of each component in Example 1.

Example 2

1) Alkalization reaction of tetradecyl alcohol polyoxyethylene ether (3):

346g (1mol) of tetradecyl alcohol polyoxyethylene ether (3) was added to the reaction kettle with heating, temperature control and electric stirring device, heated to about 70°C, and 112g (2.8 mol) solid sodium hydroxide is slowly added in the reaction kettle, after feeding is completed, be warming up to about 75 ℃, continue to react 1～2 hour at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system was lowered to about 55 ° C, and 132.3g (1.4mol) of solid chloroacetic acid was slowly added to the reaction kettle with a screw feeder under constant stirring, and after the feeding was completed, Heating and raising the temperature to about 85° C., and continuing the constant temperature reaction for 2 to 5 hours to obtain a temperature-resistant and salt-resistant low-tension foaming agent. The conversion rate of tetradecyl alcohol polyoxyethylene ether (3) is 88.4%. After purification, it can be directly used in tertiary oil recovery low tension foam oil displacement agent.

The main components of the obtained product are: sodium tetradecyl alcohol polyoxyethylene ether carboxylate (3), sodium glycolate, sodium chloride, water and unreacted tetradecyl alcohol polyoxyethylene ether (3). The mass percentages are: 55.1%, 16.9%, 13.9%, 7.3% and 6.8%, respectively.

Example 3

1) Alkalization reaction of tetradecyl alcohol polyoxyethylene ether (4):

Add 390g (1mol) of tetradecyl alcohol polyoxyethylene ether to the reaction kettle with heating, temperature control and electric stirring device, (4) heat up to about 70°C, under stirring, use a screw feeder to add 112g (2.8 mol) solid sodium hydroxide is slowly added in the reaction kettle, after feeding is completed, be warming up to about 75 ℃, continue to react 1～2 hour at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system was lowered to about 55 ° C, and 132.3g (1.4mol) of solid chloroacetic acid was slowly added to the reaction kettle with a screw feeder under constant stirring, and after the feeding was completed, Heating and raising the temperature to about 85°C, and continuing the constant temperature reaction for 3 to 4 hours to obtain a temperature-resistant and salt-resistant low-tension foaming agent. The conversion rate of tetradecyl alcohol polyoxyethylene ether (4) is 89.5%. After purification, it can be directly used in tertiary oil recovery low tension foam oil displacement agent.

The main components of the obtained product are: sodium cetyl alcohol polyoxyethylene ether carboxylate (4), sodium glycolate, sodium chloride, water and unreacted cetyl alcohol polyoxyethylene ether (4). The mass percentages are: 58.1%, 15.7%, 12.9%, 6.8% and 6.5%, respectively.

Example 4

1) the alkalization reaction of cetyl alcohol polyoxyethylene ether (5):

462g (1.0mol) of cetyl alcohol polyoxyethylene ether (5) was added to the reactor with heating, temperature control and electric stirring device, heated to about 70°C, and 120g ( 3.0mol) solid sodium hydroxide is slowly added in the reactor, after the completion of the feeding, it is warming up to about 75 ℃, and continues to react for 2 hours at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system was lowered to about 65 ° C, and 141.8g (1.5mol) of solid chloroacetic acid was slowly added to the reaction kettle with a screw feeder under constant stirring, and after the addition was completed, Heating and raising the temperature to about 85° C., and continuing the constant temperature reaction for 3 to 4 hours to obtain a temperature-resistant and salt-resistant low-tension foaming agent. The conversion rate of cetyl alcohol polyoxyethylene ether (5) is 92.3%. After purification, it can be directly used in tertiary oil recovery low tension foam oil displacement agent.

The main components of the obtained product are: sodium cetyl alcohol polyoxyethylene ether carboxylate (5), sodium glycolate, sodium chloride, water and unreacted cetyl alcohol polyoxyethylene ether (5). The mass percentages are: 61.7%, 15.1%, 12.1%, 6.2% and 4.9%, respectively.

Example 5

1) the alkalization reaction of cetyl alcohol polyoxyethylene ether (5):

462g (1.0mol) of cetyl alcohol polyoxyethylene ether (5) was added to the reactor with heating, temperature control and electric stirring device, heated to about 75°C, and 160g ( 4.0mol) solid sodium hydroxide is slowly added in the reactor, after the completion of the feeding, it is warming up to about 80 ° C, and the reaction is continued for 2 hours at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system was lowered to about 70 ° C, and 189g (2.0mol) of solid chloroacetic acid was slowly added to the reaction kettle with a screw feeder under constant stirring. The temperature is raised to about 85°C, and the constant temperature reaction is continued for 3 to 4 hours to obtain a temperature-resistant and salt-resistant low-tension foaming agent. The conversion rate of cetyl alcohol polyoxyethylene ether (5) is 92.5%. Purified and directly used as low tension foam oil displacement agent for tertiary oil recovery.

The main components of the obtained product are: sodium cetyl alcohol polyoxyethylene ether carboxylate (5), sodium glycolate, sodium chloride, water and unreacted cetyl alcohol polyoxyethylene ether (5). The mass percentages are: 53.7%, 21.4%, 14.0%, 6.5% and 4.4%, respectively.

Example 6

1) the alkalizing reaction of dodecyl alcohol polyoxyethylene ether (3):

Add 318g (1mol) of dodecyl alcohol polyoxyethylene ether (3) to the reaction kettle with heating, temperature control and electric stirring device, heat up to about 60°C, stir 120g (3.0 mol) solid sodium hydroxide is slowly added in the reaction kettle, after feeding is completed, be warming up to about 70 ℃, continue to react for about 2 hours at this temperature;

2) Carboxymethylation reaction:

Step 1) in the reaction kettle after the alkalization, the temperature of the reactant system is lowered to about 55 ° C, and 141.8g (1.5mol) of solid chloroacetic acid is slowly added to the reaction kettle with a screw feeder under constant stirring, and after the feeding is completed, Heating and raising the temperature to about 75°C, and continuing the constant temperature reaction for about 5 hours to obtain a temperature-resistant, salt-resistant and low-tension foaming agent, the conversion rate of dodecyl alcohol polyoxyethylene ether (3) is 87.4%. Purified and directly used as low tension foam oil displacement agent for tertiary oil recovery.

The main components of the obtained product are: dodecyl alcohol polyoxyethylene ether (3) sodium carboxylate, sodium glycolate, sodium chloride, water and unreacted lauryl alcohol polyoxyethylene ether (3), which is The mass percentages are: 51.3%, 19.2%, 15.1%, 7.5% and 6.9%, respectively.

Comparative Example 1

Repeat Example 1, the difference is that the material amount of the reaction raw material solid sodium hydroxide is 80g (2.0mol), the material amount of the solid chloroacetic acid is 94.5g (1.0mol), and the dodecyl alcohol polyoxyethylene ether (3) The conversion rate was 67.3%, and the main components of the obtained product were: dodecyl alcohol polyoxyethylene ether (3) sodium carboxylate, sodium glycolate, sodium chloride, water and unreacted dodecyl alcohol polyoxyethylene ether Vinyl ether (3), its mass percentages are: 46.5%, 14.4%, 11.9%, 6.1% and 21.1%, respectively.

Comparative Example 2

Repeat Example 1, the difference is that the amount of reaction raw material solid sodium hydroxide is 160g (4.0mol), the amount of solid chloroacetic acid is 189g (2.0mol), and the amount of dodecyl alcohol polyoxyethylene ether (3) is 189g (2.0mol). The conversion rate is 94.7%, and the main components of the obtained product are: dodecyl alcohol polyoxyethylene ether (3) sodium carboxylate, sodium glycolate, sodium chloride, water and unreacted dodecyl alcohol polyoxyethylene Ether (3), its mass percentages are: 48.3%, 23.6%, 17.5%, 8.1% and 2.5%, respectively.

Example 7

The oil-water interfacial tension of each product with a mass concentration of 0.5% + 5% NaCl solution and Shengli crude oil in the above examples and comparative examples was measured.

The method of solution preparation in each instance: take 1000g solution as an example, take by weighing the foaming agent prepared in a certain instance of 5g and 50gNaCl respectively and pour it into the reaction flask, then weigh 945g of distilled water and pour it into the above-mentioned reaction flask, and make it by stirring or ultrasonically. The solute was fully dissolved to obtain a solution of 0.5% foaming agent + 5% NaCl.

The experimental method of interfacial tension measurement is as follows: according to "SY/T 5370-2018 Interfacial Tension Determination Method" and "SY/T6424-2014 Performance Test Method of Compound Oil Displacement System", the interfacial tension is measured. First, each synthetic product is prepared to a concentration of 0.5wt % (foam oil displacement agent) + 5wt% NaCl solution (relative to the foam oil displacement agent system), the oil-water interfacial tension of Shengli crude oil and oil displacement agent solution system was measured by the spinning drop method, and then the IFT-t relationship curve was made by computer software , the experimental temperature is 80 °C, and the rotation speed is 5000 rpm.

The measurement data of the above-mentioned Examples 1 to 4 are shown in FIG. 1 . It can be seen from the measurement results in Figure 1 that the synthesized product has excellent interfacial properties. Without any additives, it can form an ultra-low oil-water interfacial tension (10 ^-3 mN/m) with Shengli crude oil, which can be directly used for three times. in oil extraction.

The difference from Examples 5 and 6 is that the reaction raw materials and the ratio of the reaction raw materials are different, and the conversion rates of the raw materials are also different, so the content of each component in the product is different, because the physicochemical properties of surfactants with different structures are different, usually in the In the case of the same polyether unit within a certain carbon chain length, the shorter the alkyl chain length, the lower the surface tension and the stronger the foaming ability, but the worse the foam stability, but the oil-water interfacial tension is related to oil, and the non-ionic surface When the active agent and the anionic and nonionic surfactant are mixed within a certain proportion, the oil-water interfacial tension and foam stability can be enhanced, and the product obtained within the range required by the present invention has the interfacial tension, foaming ability and foam stability. It can meet the requirements of temperature resistance, salt resistance and low tension foaming agent in Shengli Oilfield.

The comparison between Comparative Example 1 and Comparative Example 2 mainly shows that under the same reaction conditions, the conversion rate of alkyl alcohol polyoxyethylene ether can be improved by adjusting the molar ratio of the reactants, alkali and chloroacetic acid and alkyl alcohol. The larger the proportion of polyoxyethylene ether, the higher the conversion rate of alkyl alcohol polyoxyethylene ether, and the better the surface tension and foaming ability of the product, but the corresponding foam stability decreases, and the content of salt in the product also increases. Therefore, taking comprehensive consideration, select appropriate reaction conditions and material ratio, so that the obtained product can meet the requirements of foaming agent directly used in Shengli Oilfield for foam flooding.

Example 8

In the above examples 1-5, each product was prepared into a solution with a mass concentration of 0.5% with the on-site formation water of Shengli Oilfield, respectively. The measured foaming ability and foam stability data are shown in Table 1 below.

The experimental method of foam performance measurement is as follows: using Bikerman air flow method, the way to generate foam is generally to pass gas with a certain flow rate and flow through the glass sand filter plate, agitate the quantitative test solution on the filter plate, and a certain amount of foam is placed on the scale container (scale graduated cylinder). ) formed. The maximum foaming ability and stability of the foaming system can be investigated by recording the foam height and liquid discharge volume at different times. Experimental steps: slowly pour 50 mL of the prepared surfactant solution into a 500 mL bubbling tube, and use a constant temperature water bath to maintain a constant temperature for a certain period of time until equilibrium; Time for 20s, then plug the upper end of the foaming tube with a rubber stopper, record the foam volume at different times, and obtain the foam volume and foam half-life of the foaming agent (the foam half-life is the time required for the initial foam volume to decay by half, which characterizes the foam stability); the experimental temperature was 50 °C.

Table 1 Foaming ability and foam performance data of synthetic foam oil-displacing agent

It can be seen from the experimental results that in the examples, when the conversion rate of the alkyl alcohol ether is within a certain range, the foaming ability and foam stability of the synthetic oil displacement foaming agent are excellent, the foaming volume reaches more than 200ml, and the foam half-life is all It can be used as tertiary oil recovery technology of temperature-resistant, salt-resistant and low-tension foam flooding for more than 85min.

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Changes or changes in other different forms cannot be exhausted here, and all obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (7)

1. The application of the temperature-resistant salt-resistant low-tension foam oil displacement agent in tertiary oil recovery in an oil field is characterized in that the foam oil displacement agent mainly comprises fatty alcohol-polyoxyethylene ether carboxylate; meanwhile, the adhesive also contains fatty alcohol-polyoxyethylene ether;

in the foam oil-displacing agent, the total content of the fatty alcohol-polyoxyethylene ether carboxylate and the fatty alcohol-polyoxyethylene ether is more than 55 wt%; and is provided with

The mass ratio of the fatty alcohol-polyoxyethylene ether carboxylate to the fatty alcohol-polyoxyethylene ether is 13: 1-7: 1;

the chemical formula of the fatty alcohol-polyoxyethylene ether is as follows: r is ₁ O(CH ₂ CH ₂ O) _n1 H, itIn R ₁ Is C ₁₀ ～C ₂₀ N1 is selected from a positive integer of 1-10;

the chemical formula of the fatty alcohol-polyoxyethylene ether carboxylate is as follows: r ₂ O(CH ₂ CH ₂ O) _n2 CH ₂ COOM wherein R ₂ Is C ₁₀ ～C ₂₀ N2 is selected from a positive integer of 1-10, and M is selected from metal potassium or sodium ions;

wherein R is as defined above ₁ And R ₂ The same or different, n1 and n2 are the same or different.

2. The application of the low-tension foam oil displacement agent as claimed in claim 1, wherein the preparation method of the low-tension foam oil displacement agent comprises the following steps:

in the presence of solid alkali, fatty alcohol-polyoxyethylene ether is subjected to an alkalization reaction;

adding solid chloroacetic acid into the system obtained after the alkalization reaction, and performing carboxymethylation reaction to obtain the whole system, namely the temperature-resistant salt-resistant low-tension foam oil displacement agent;

the gram equivalent ratio of the fatty alcohol-polyoxyethylene ether to the solid alkali is 1: 2.8-4;

the molar ratio of the fatty alcohol-polyoxyethylene ether to the solid chloroacetic acid is 1: 1.4-2.

3. The use according to claim 2, wherein the solid alkali is one or more of solid sodium hydroxide and solid potassium hydroxide.

4. Use according to claim 2 or 3, characterized in that the conditions of the basification reaction are:

adding solid alkali into fatty alcohol-polyoxyethylene ether at the temperature of 50-90 ℃ under the stirring condition, heating to 70-80 ℃, and reacting for 1-2 hours at the temperature.

5. Use according to claim 2 or 3, wherein the carboxymethylation reaction is carried out under the following conditions:

and controlling the temperature of the system obtained after the alkalization reaction to be 50-80 ℃, adding solid chloroacetic acid under the stirring condition, heating to 75-90 ℃, and reacting at constant temperature for 2-5 hours.

6. The application of claim 1, wherein the temperature-resistant salt-resistant low-tension foam oil displacement agent is used in an amount of 1.0-0.3% of the mass of the foam displacement fluid.

7. The application according to claim 1, wherein the application condition comprises:

the temperature of stratum is lower than 100 deg.C, and the degree of mineralization is lower than 3X 10 ⁴ ppm, calcium and magnesium ion concentration is less than 1000 ppm.

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