A naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and its preparation method

Abstract

A naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant of the present invention and a preparation method thereof use naphthenic acid and ethylenediamine as raw materials. At a certain temperature, water is dehydrated by a water-carrying agent to generate naphthenic acid amide; the naphthenic acid amide undergoes ring-opening polymerization with ethylene carbonate under the action of a catalyst to generate naphthenic acid amide polyether ester; the naphthenic acid amide polyether ester is then sulfonated with 3-chloro-2-hydroxypropane sulfonate to obtain the naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant. The above synthesis method has the characteristics of rich raw material resources, simple and controllable synthesis process, excellent product performance, wide adaptability, etc. The binary oil displacement system composed of this surfactant and polyacrylamide can maintain ultra-low interfacial tension within a relatively wide concentration range, and has good oil-water compatibility and stable interfacial performance. The binary system has good salt resistance, hard water resistance, high viscosity retention rate of the binary system and long-term stability performance, and strong anti-adsorption ability, and can increase the oil recovery rate by more than 20% after water flooding.

Description

Technical Field

[0001] The present invention belongs to a novel surfactant, and particularly relates to a naphthenic acid amide polyether ester sulfonate surfactant with ultra-low interfacial tension and a preparation method thereof. Background Art

[0002] Most of the domestic oilfield developments have entered the middle and late stages. The water content in the produced fluids of some oil wells has reached over 90%. All major oilfields are comprehensively carrying out enhanced oil recovery (EOR) technologies. As one of the most promising technologies for improving oil recovery, chemical flooding technology increases the viscosity of the injection system, improves the mobility ratio, and expands the swept volume; by reducing the oil-water interfacial tension and enhancing the oil washing ability of the displacement system, etc., to ultimately achieve the goal of improving oil recovery. Currently, chemical flooding technology has been widely applied in Daqing Oilfield, Liaohe Oilfield, Shengli Oilfield, Xinjiang Oilfield, etc., and has become an inevitable way for old oilfields to add development potential in the middle and late stages of oilfield development.

[0003] Chemical flooding technologies represented by the ASP ternary composite flooding technology have also been widely studied and applied in recent years. For example, the strong alkali ternary composite flooding system described in the patent with publication number CN1344776A and title "Ternary Composite Flooding System of Plant Carboxylic Acid Surfactant and Its Application", and the weak alkali ternary composite flooding system described in the patent with publication number CN105505366A and title "A Weak Alkali Ternary Composite Flooding Agent Containing a Hydroxy-Substituted Aryl Alkyl Sulfonate Surfactant", etc. The ASP ternary composite flooding technology promoted in Daqing Oilfield, although it has stabilized and increased the crude oil production to a certain extent, has not been fully promoted due to factors such as high production costs and difficult subsequent treatment. For the ASP ternary composite flooding (surfactant + polymer + alkali), the alkali in the ternary system is a double-edged sword. Although it helps to significantly improve oil recovery, it also brings many engineering problems. During the on-site test of the ternary composite flooding, it was found that the strong alkali (sodium hydroxide) in the strong alkali ternary composite flooding system can cause the dispersion and migration of formation clay, resulting in a decrease in formation permeability. The alkali reacts with the formation fluid and rock minerals to form alkali scale, such as carbonate scale and aluminosilicate scale, which damages the formation and causes corrosion scale in the wellbore; the weak alkali (sodium carbonate) in the weak alkali ternary composite flooding system is sensitive to divalent ions in the prepared sewage, easily causing scaling in the ground injection system; and the oil-water emulsification of the produced fluid in the ternary composite flooding is serious, greatly increasing the difficulty and cost of gathering, transportation, and dehydration treatment. The alkali can also significantly reduce the viscoelasticity of the polymer, and the unfavorable mobility ratio will lead to viscous fingering, greatly reducing the swept volume.

[0004] In order to eliminate these adverse factors brought by the alkali in the ternary composite flooding system, it is of great practical significance to develop an ultra-low interfacial tension surfactant required for the alkali-free binary composite flooding system. The binary composite flooding system SP (surfactant + polymer) can maximize the viscoelasticity of the polymer; weaken the corrosion and scaling phenomena caused by the presence of alkali, maintain the ultra-low interfacial tension and swept volume of the displacement system, and the oil displacement effect is close to that of the ternary composite flooding. At the same time, the environmental protection performance of the chemical flooding technology is improved. According to the properties of the crude oil in the target reservoir, by adjusting the molecular structure of the surfactant, a binary system that does not require the addition of alkali and is directly composed of polymer can achieve an ultra-low interfacial tension value of <1×10 -2 mN / m with the crude oil in the target reservoir, which has gradually become a new research direction for enhanced oil recovery.

[0005] With the continuous deepening of crude oil production, the proportion of heavy components in crude oil is increasing, and the most prominent one is the increasing content of naphthenic acid in crude oil. Among them, Liaohe Oilfield, Xinjiang Oilfield, and Shengli Oilfield are reservoirs with relatively high naphthenic acid content in China's crude oil. Naphthenic acid is an organic acid existing in petroleum and is also called petroleum acid. As a by-product and fine chemical raw material in the petroleum processing process, naphthenic acid has a wide range of applications. Using the naphthenic acid rich in crude oil as raw material to produce an ultra-low interfacial tension surfactant required for the binary composite flooding system for crude oil production has relatively prominent technical significance and application prospects. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and its preparation method.

[0007] A naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant of the present invention has the following structural formula:

[0008]

[0009] In the above structural formula: m represents the degree of polymerization of the carbonate group in the structural formula, and m is any integer from 0 to 15;

[0010] In the above structural formula: n represents the degree of polymerization of the ethoxy group in the structural formula, and n is any integer from 0 to 15;

[0011] In the above structural formula: the sum of m + n is any integer from 5 to 15;

[0012] In the above structural formula: R represents the cycloalkyl group in the structural formula.

[0013] A preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant of the present invention is achieved through the following steps:

[0014] a. Amidation reaction

[0015] The naphthenic acid amide is prepared by dehydration with the reaction of naphthenic acid and ethylenediamine at a molar ratio of 1:1 - 1.5 under the action of a water-carrying agent, petroleum ether. The acid value of the naphthenic acid is 80 - 220 mgKOH / g;

[0016] b. Ring-opening polymerization reaction

[0017] The naphthenic acid amide polyether ester is prepared by the ring-opening polymerization reaction of the naphthenic acid amide prepared in step a with ethylene carbonate under the action of a catalyst, potassium hydroxide, at a molar ratio of 1:5 - 15;

[0018] c. Sulfonation reaction

[0019] The naphthenic acid amide polyether ester sulfonate is prepared by reacting the naphthenic acid amide polyether ester prepared in step b with sodium hydroxide and 3-chloro-2-hydroxypropyl sulfonate in petroleum ether as a solvent;

[0020] As a further improvement of the present invention, the specific method of the amidation reaction in step a is as follows: Mix the naphthenic acid, ethylenediamine and the water-carrying agent petroleum ether, stir and heat up, reflux and dehydrate at a temperature of 80 - 90 °C. The reflux dehydration time is controlled at 1 - 4 hours, and the water with an equimolar amount of the naphthenic acid is refluxed and removed, indicating the completion of dehydration; then the water-carrying agent petroleum ether is removed, and the end temperature is controlled not to exceed 100 °C. After the water-carrying agent petroleum ether is completely removed, the naphthenic acid amide is obtained; the boiling range of the water-carrying agent petroleum ether is 60 - 90 °C; the addition amount of the water-carrying agent petroleum ether is twice the total mass of the naphthenic acid and ethylenediamine; the molar ratio of the naphthenic acid to ethylenediamine is 1:1.05.

[0021] As a further improvement of the present invention, the acid value of the naphthenic acid is 160 - 180 mgKOH / g.

[0022] As a further improvement of the present invention, the specific method of the ring-opening polymerization reaction in step b is as follows: Add the catalyst potassium hydroxide to the naphthenic acid amide prepared in step a, and fully displace the air in the reaction vessel with nitrogen; then heat up, and start to add ethylene carbonate when the temperature reaches 80 °C; after the feeding of ethylene carbonate is completed, raise the temperature to 145 - 150 °C for the ring-opening polymerization reaction for 8 - 10 hours; after the reaction is completed, cool down to 20 - 30 °C, and the product is the naphthenic acid amide polyether ester.

[0023] As a further improvement of the present invention, the molar ratio of the naphthenic acid amide to ethylene carbonate is 1:10; the addition amount of the catalyst potassium hydroxide is 5 - 10‰ of the total mass of the naphthenic acid amide and ethylene carbonate.

[0024] As a further improvement of the present invention, the specific method of the sulfonation reaction in step c is as follows: Add the naphthenic acid amide polyether ester prepared in step b and the solvent petroleum ether into the sulfonation reaction kettle, start stirring, then add sodium hydroxide, heat the sulfonation reaction kettle to 80-90 °C, and carry out the alkalization reaction under reflux for 1-2 hours; After the alkalization is completed, lower the temperature of the sulfonation reaction kettle to 60-70 °C, dropwise add an aqueous solution of 40% sodium 3-chloro-2-hydroxypropane sulfonate, control the dropping time within 0.5-1 hour, and continue the reaction at 60-70 °C for 4-6 hours after dropping; After the reaction is completed, remove the solvent petroleum ether under negative pressure under stirring; After the solvent petroleum ether is removed, add deionized water to the reaction kettle to prepare an aqueous solution, stir for 0.5-1 hour and take out the product to obtain a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant product;

[0025] The solvent petroleum ether has a boiling range of 60-90 °C, and the addition amount of the petroleum ether solvent is 50% of the mass of the naphthenic acid amide polyether ester; The molar ratio of naphthenic acid amide polyether ester to sodium hydroxide is 1:1-1.5; The molar ratio of naphthenic acid amide polyether ester to sodium 3-chloro-2-hydroxypropane sulfonate is 1:1-1.5; The addition amount of deionized water is twice the total mass of the naphthenic acid amide polyether ester and sodium 3-chloro-2-hydroxypropane sulfonate.

[0026] As a further improvement of the present invention, the molar ratio of the naphthenic acid amide polyether ester to sodium hydroxide is 1:1.05; The molar ratio of naphthenic acid amide polyether ester to sodium 3-chloro-2-hydroxypropane sulfonate is 1:1.05.

[0027] An ultra-low interfacial tension surfactant of naphthenic acid amide polyether ester sulfonate of the present invention, when forming a binary oil displacement system with polyacrylamide, can maintain an ultra-low interfacial tension within a relatively wide concentration range (effective concentration within 0.05%-0.5%, salinity within 1000-8000 mg / L, at 45 °C), and has good oil-water compatibility and stable interfacial performance. The binary system has good salt resistance, hard water resistance, high viscosity retention rate of the binary system and long-term stability performance, and strong anti-adsorption ability. Through the binary system oil displacement experiment on artificial cores, the oil recovery rate can be increased by more than 20% after water flooding. Specific embodiments

[0028] Example 1

[0029] A preparation method of an ultra-low interfacial tension surfactant of naphthenic acid amide polyether ester sulfonate of the present invention is achieved through the following steps:

[0030] a. Amidation reaction

[0031] Add naphthenic acid, ethylenediamine and the water-carrying agent petroleum ether into the dehydration kettle in sequence. Start stirring and heating up. Under the condition of a temperature of 80 - 90 °C, carry out reflux dehydration. Control the reflux dehydration time to be 1 - 4 hours. When the same molar amount of water as naphthenic acid is refluxed and removed, the dehydration is completed. Remove the water-carrying agent petroleum ether under negative pressure, and control the end temperature not to exceed 100 °C. After the water-carrying agent petroleum ether is completely removed, naphthenic acid amide is obtained.

[0032] The reaction formula is as follows:

[0033]

[0034] The water-carrying agent petroleum ether has a boiling range of 60 - 90 °C; the addition amount of the water-carrying agent petroleum ether is one time the total mass of naphthenic acid and ethylenediamine; the molar ratio of naphthenic acid to ethylenediamine is 1:1 - 1.5; the acid value of the naphthenic acid is (80 - 220) mgKOH / g.

[0035] b. Ring-opening polymerization reaction

[0036] After accurately measuring the naphthenic acid amide prepared in step a, transfer it into the polymerization kettle, and add the catalyst potassium hydroxide into the polymerization kettle. Start the stirring and reflux condensation system of the polymerization kettle, and fully displace the inside of the reaction kettle with nitrogen to displace the air inside the reaction system completely. Start the heating system of the polymerization kettle. When the temperature of the polymerization kettle reaches 80 °C, start adding ethylene carbonate. After the feeding of ethylene carbonate is completed, raise the temperature of the polymerization kettle to 145 - 150 °C for ring-opening polymerization reaction for 8 - 10 hours. After the reaction is completed, cool down to 20 - 30 °C, and the product is naphthenic acid amide polyether ester.

[0037] The reaction formula is as follows:

[0038]

[0039] The molar ratio of the naphthenic acid amide to ethylene carbonate is 1:5 - 15; the addition amount of the catalyst potassium hydroxide is 5 - 10‰ of the total mass of naphthenic acid amide and ethylene carbonate.

[0040] c. Sulfonation reaction

[0041] Add the naphthenic acid amide polyether ester prepared in step b and the solvent petroleum ether into the sulfonation reactor, and start stirring. Then add sodium hydroxide, heat the sulfonation reactor to 80-90 °C, and carry out the alkalization reaction for 1-2 hours under reflux. After the alkalization is completed, lower the temperature of the sulfonation reactor to 60-70 °C, and dropwise add an aqueous solution of 40% sodium 3-chloro-2-hydroxypropane sulfonate. The dropping time is controlled within 0.5-1 hour. After the dropping is completed, continue the reaction at 60-70 °C for 4-6 hours. After the reaction is completed, remove the solvent petroleum ether under negative pressure under stirring. After the solvent petroleum ether is removed, add deionized water (one time the total mass of the naphthenic acid amide polyether ester and sodium 3-chloro-2-hydroxypropane sulfonate) to the reactor to prepare an aqueous solution, stir for 0.5-1 hour, and take out the product to obtain the naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant;

[0042] The reaction formula is as follows:

[0043]

[0044] The addition amount of the petroleum ether solvent is 50% of the mass of the naphthenic acid amide polyether ester; the molar ratio of the naphthenic acid amide polyether ester to sodium hydroxide is 1:1-1.5, and the molar ratio of the naphthenic acid amide polyether ester to sodium 3-chloro-2-hydroxypropane sulfonate is 1:1-1.5.

[0045] Example 2

[0046] A preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant of the present invention is realized through the following steps:

[0047] a. Amidation reaction: Add 1 mol of naphthenic acid, 1.05 mol of ethylenediamine, and the water-carrying agent petroleum ether into the dehydration kettle in sequence. Among them, the addition amount of petroleum ether is one time the total mass of naphthenic acid and ethylenediamine. Start stirring and heating. Control the temperature at 80-90 °C for reflux dehydration. The reflux dehydration time is controlled for 4 hours. Reflux and remove water in an equimolar amount of naphthenic acid (1 mol), that is, the dehydration is completed. Remove the water-carrying agent petroleum ether under negative pressure, and control the end temperature not to exceed 100 °C. After the water-carrying agent petroleum ether is completely removed, the naphthenic acid amide is obtained; the acid value of the naphthenic acid is 160-180 mgKOH / g;

[0048] b. Ring-opening polymerization reaction: Take 1 mol of the cycloalkanoic acid amide obtained from the above amidation reaction and transfer it into a polymerization kettle. Add potassium hydroxide as a catalyst to the polymerization kettle, seal the polymerization kettle, start the stirring and reflux condensation system of the polymerization kettle, fully displace the inside of the reaction kettle with nitrogen to completely displace the air in the reaction system, start the heating system of the polymerization kettle, and start adding 10 mol of ethylene carbonate when the temperature of the polymerization kettle reaches 80 °C. After the feeding of ethylene carbonate is completed, raise the temperature of the polymerization kettle to 145 - 150 °C for a ring-opening polymerization reaction for 10 hours; after the reaction is completed, cool down to 20 - 30 °C, and the product is cycloalkanoic acid amide polyether ester. Among them, the addition amount of the catalyst potassium hydroxide is 5‰ of the total mass of cycloalkanoic acid amide and ethylene carbonate;

[0049] c. Sulfonation reaction: Take 1 mol of the cycloalkanoic acid amide polyether ester obtained from the above ring-opening polymerization reaction and petroleum ether (boiling range 60 - 90 °C) as a solvent and add them into a sulfonation reaction kettle, start stirring, and then add 1.05 mol of sodium hydroxide. Raise the temperature of the sulfonation reaction kettle to 80 - 90 °C and carry out an alkalization reaction for 2 hours under reflux. After the alkalization is completed, lower the temperature of the sulfonation reaction kettle to 60 - 70 °C, and dropwise add an aqueous solution of 3-chloro-2-hydroxypropanesulfonic acid sodium with a concentration of 40% and a volume of 1.05 mol. The dropping time is controlled within 1 hour. After the dropping is completed, continue the reaction for 6 hours at 60 - 70 °C. After the reaction is completed, remove the solvent petroleum ether under negative pressure under stirring. After the solvent petroleum ether is removed, add deionized water (one time the total mass of cycloalkanoic acid amide polyether ester and 3-chloro-2-hydroxypropanesulfonic acid sodium) to the reaction kettle to prepare an aqueous solution, stir for 1 hour and take out the product, and obtain the cycloalkanoic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant.

[0050] The performance of the cycloalkanoic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant prepared in Example 2 is further described below:

[0051] 1. Evaluation of the interfacial tension of the surfactant binary system at different concentrations

[0052] According to the measurement method in 6.3 of Q / SY1583 - 2013, using the dehydrated crude oil from the No. 9 Operating Area South 7 - 1 Joint Station of the Second Oil Production Plant of Daqing Oilfield and the 25 million molecular weight polyacrylamide for oil displacement from Daqing Refining & Chemical Company, prepare binary system solutions with the concentrations of the cycloalkanoic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant being 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% respectively and the polyacrylamide concentration being 1000 ppm using simulated brine. Use a TX-500C rotating drop interfacial tensiometer to measure the interfacial tension between the surfactant solutions at different concentrations and the crude oil at 45 °C with a rotation speed of 5000 revolutions per minute. The results are shown in the following table:

[0053]

[0054] As can be seen from the data in the above table, the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide can maintain an ultra-low interfacial tension requirement of < 1×10 -2 mN / m within a relatively wide range of effective concentrations from 0.05% to 0.5%.

[0055] 2. Evaluation of the viscosity and interfacial tension stability of the binary system

[0056] According to the determination method in 6.9 of Q / SY1583-2013, under the condition of 1000 ppm polyacrylamide concentration, a binary system solution with a concentration of 0.2% naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant was prepared and placed in an oven at 45°C under anaerobic conditions for 0 day, 1 day, 3 days, 7 days, 15 days, 30 days, and 60 days respectively. The viscosity of the binary system solution was measured, and at the same time, the interfacial tension between the binary system solution and the crude oil was measured. The results are shown in the following table:

[0057]

[0058] As can be seen from the data in the above table, for the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide, the interfacial tension still remains < 1×10 -2 mN / m within the ultra-low interfacial tension range, and the viscosity retention rate is still at a relatively high level within 60 days. It fully meets the requirements of the Q / SY1583-2013 standard that the viscosity retention rate ≥ 90% within 30 days and the interfacial tension < 1×10 -2 mN / m ultra-low interfacial tension requirement.

[0059] 3. Evaluation of the salt resistance performance of the binary system

[0060] Sodium chloride solutions with different salinities were prepared with distilled water. Under the condition of 1000 ppm polyacrylamide concentration, binary system solutions with a concentration of 0.2% naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant were prepared using waters with different salinities. At 45°C and a rotation speed of 5000 revolutions per minute, the interfacial tension between them and the crude oil was measured. The results are shown in the following table:

[0061]

[0062] As can be seen from the data in the above table, for the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide, within the salinity range of 1000 - 8000 mg / L, the interfacial tension still remains < 1×10 -2 mN / m within the ultra-low range, and it has good salt resistance performance.

[0063] 4. Hard water resistance experiment of the binary system

[0064] Prepare simulated hard aqueous solutions with different concentrations of Ca 2+ +Mg 2+ Under the condition of 1000 ppm of the polymer, prepare binary system solutions of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant with a concentration of 0.2% using solutions with different concentrations of Ca 2+ +Mg 2+ Measure the interfacial tension between it and crude oil at 45 °C with a rotation speed of 5000 revolutions per minute. The results are shown in the following table:

[0065]

[0066] As can be seen from the data in the above table, for the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide, within the range of Ca 2+ +Mg 2+ concentrations of 10 - 50 mg / L, the interfacial tension still remains in the ultra-low range of < 1×10 - 2 mN / m, showing good resistance to hard water.

[0067] 5. Multiple adsorption experiments on the binary system

[0068] Prepare a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant solution with a concentration of 0.2% according to the measurement method in 6.4 of Q / SY1583 - 2013. At a solid-liquid ratio of 1:9 of oil sand to surfactant solution, oscillate for 12 hours at 45 °C with an oscillation frequency of 90 times / min, and measure the interfacial tension after the oil sand adsorption. And according to this experimental condition, take the surfactant solution after adsorption and repeat the steps until the interfacial tension of the surfactant solution after adsorption is greater than 1×10 -2 mN / m, then stop the experiment and record the interfacial tension at different adsorption times. The results are shown in the following table:

[0069]

[0070] As can be seen from the data in the above table, for the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide, after three adsorption experiments, the interfacial tension still remains in the ultra-low range of < 1×10 -2 mN / m, fully meeting the requirements specified in the Q / SY1583 - 2013 standard, and showing good anti-adsorption ability.

[0071] 6. Oil displacement experiment on the binary system

[0072] According to the determination method in Chapter 9 of the standard SY / T 6424-2014 "Testing Methods for the Performance of Composite Flooding Systems", the oil displacement effect of the binary system (S surfactant + P polymer) on artificial cores was tested.

[0073] 6.1. Experimental Conditions

[0074] (1) Core: Homogeneous artificial physical cores were used, with a core size of 4.0 cm × 4.0 cm × 30 cm. The gas permeability and porosity of the cores are shown in the following table:

[0075]

[0076]

[0077] (2) Experimental water: The water used for water flooding and the binary system was the standard simulated brine of Daqing Oilfield. The formula of the simulated brine is shown in the following table:

[0078] Ingredients Increment (m / m), % NaCl 0.1249 <![CDATA[NaHCO3]]> 0.2929 <![CDATA[Na2CO3]]> 0.0191 <![CDATA[Na2SO4]]> 0.0006 <![CDATA[Calcium chloride]]> 0.0033 <![CDATA[MgCl2·6H2O]]> 0.0059

[0079] (3) Chemical agents used in the experiment: The polymer used was polyacrylamide for oil displacement with a molecular weight of 25 million from Daqing Refining and Chemical Company, and the surfactant used was the naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant of the present invention.

[0080] (4) Experimental oil: The dehydrated crude oil from the South 7-1 Joint Station in the Ninth Production Area of the Second Oil Production Plant of Daqing Oilfield.

[0081] (5) Experimental temperature: All experiments were carried out at 45°C.

[0082] (6) Injection rate: 20 ml / h.

[0083] 6.2. Experimental Procedures

[0084] (1) After evacuating the core for 4 hours, saturate it with simulated brine and measure the porosity;

[0085] (2) Place the core saturated with simulated brine in a thermostatic oven and keep it at a constant temperature for more than 4 hours (45°C);

[0086] (3) Saturate the core with simulated crude oil and place it in a thermostatic oven and keep it at a constant temperature for more than 12 hours (45°C), requiring the oil saturation of the core to be as close as possible to the original oil saturation of the reservoir;

[0087] (4) Carry out simulated oil displacement according to the standard procedure specified in SY / T 6424-2014 "Testing Methods for the Performance of Composite Flooding Systems" and calculate the recovery factor.

[0088] 6.3. Experimental Scheme

[0089] Scheme 1:

[0090] ①Simulate the brine flooding until the water cut reaches 98%, and calculate the water flooding recovery factor;

[0091] ②Inject 0.3 pv of the binary system: polyacrylamide with a concentration of 1500 mg / L and a molecular weight of 25 million, and the surfactant concentration is 0.3%;

[0092] ③Then inject the simulated brine and flood until the water cut reaches 98%, and calculate the total recovery factor.

[0093] Scheme 2:

[0094] ①Simulate the brine flooding until the water cut reaches 98%, and calculate the water flooding recovery factor;

[0095] ②Inject 0.3 pv of the binary system: polyacrylamide with a concentration of 1500 mg / L and a molecular weight of 25 million, and the surfactant concentration is 0.2%;

[0096] ③Then inject the simulated brine and flood until the water cut reaches 98%, and calculate the total recovery factor.

[0097] Scheme 3:

[0098] ①Simulate the brine flooding until the water cut reaches 98%, and calculate the water flooding recovery factor;

[0099] ②Inject 0.3 pv of the binary system: polyacrylamide with a concentration of 1000 mg / L and a molecular weight of 25 million, and the surfactant concentration is 0.3%;

[0100] ③Then inject the simulated brine and flood until the water cut reaches 98%, and calculate the total recovery factor.

[0101] Scheme 4:

[0102] ①Simulate the brine flooding until the water cut reaches 98%, and calculate the water flooding recovery factor;

[0103] ②Inject 0.3 pv of the binary system: polyacrylamide with a concentration of 1000 mg / L and a molecular weight of 25 million, and the surfactant concentration is 0.2%;

[0104] ③Then inject the simulated brine and flood until the water cut reaches 98%, and calculate the total recovery factor.

[0105] 6.4 Experimental results data of oil displacement

[0106]

[0107] As can be seen from the data in the above table, in the binary system oil displacement experiment of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant in artificial cores, the recovery factor can be increased by more than 20% after water flooding.

[0108] From the above experimental data, it can be seen that the binary oil displacement system composed of naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant and polyacrylamide can maintain ultra-low interfacial tension within a wide concentration range (effective concentration range of 0.05% - 0.5%, salinity of 1000 - 8000 mg / L, at 45°C), and has good oil-water compatibility and stable interfacial properties. The binary system has good salt resistance, hard water resistance, high viscosity retention rate and long-term stability, and strong anti-adsorption ability.

Claims

1. A naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant, characterized in that The structural formula is as follows: ， In the above structural formula: m represents the degree of polymerization of the carbonate group in the structural formula, and m is any integer from 1 to 15; In the above structural formula: n represents the degree of polymerization of the ethoxy group in the structural formula, and n is any integer from 0 to 15; In the above structural formula: the sum of m + n is any integer from 5 to 15; In the above structural formula: R represents the cycloalkyl group in the structural formula.

2. A method for preparing a cycloalkanoic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant as claimed in claim 1 is achieved through the following steps: a. Amidation reaction The cycloalkanoic acid and ethylenediamine are dehydrated in a molar ratio of 1:1 to 1.5 under the action of a water-carrying agent, petroleum ether, to obtain cycloalkanoic acid amide. The acid value of the cycloalkanoic acid is 80 - 220 mgKOH / g; b. Ring-opening polymerization reaction The cycloalkanoic acid amide obtained in step a is subjected to a ring-opening polymerization reaction with ethylene carbonate under the action of a catalyst, potassium hydroxide, in a molar ratio of 1:5 to 15 to obtain cycloalkanoic acid amide polyether ester; c. Sulfonation reaction The cycloalkanoic acid amide polyether ester obtained in step b is reacted with sodium hydroxide and 3-chloro-2-hydroxypropanesulfonic acid sodium in petroleum ether as a solvent to obtain cycloalkanoic acid amide polyether ester sulfonate.

3. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 2, characterized in that The specific method of the amidation reaction in step a is as follows: The cycloalkanoic acid, ethylenediamine, and the water-carrying agent petroleum ether are mixed, stirred, and heated. Under the condition of a temperature of 80 - 90 °C, reflux dehydration is carried out. The reflux dehydration time is controlled for 1 - 4 hours. When an equimolar amount of water of the cycloalkanoic acid is refluxed and removed, the dehydration is completed; then the water-carrying agent petroleum ether is removed, and the end temperature is controlled not to exceed 100 °C. After the water-carrying agent petroleum ether is completely removed, cycloalkanoic acid amide is obtained; The reaction formula is as follows: ， The water-carrying agent petroleum ether has a boiling range of 60 - 90 °C; the addition amount of the water-carrying agent petroleum ether is twice the total mass of the cycloalkanoic acid and ethylenediamine; the molar ratio of the cycloalkanoic acid to ethylenediamine is 1:1.

05.

4. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 3, characterized in that The acid value of the cycloalkanoic acid is 160 - 180 mgKOH / g.

5. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 2, characterized in that The specific method of the ring-opening polymerization reaction in step b is as follows: Catalyst potassium hydroxide is added to the cycloalkanoic acid amide obtained in step a. The reaction vessel is fully replaced with nitrogen to displace the oxygen in the reaction system completely; then the temperature is raised. When the temperature reaches 80 °C, ethylene carbonate is added; after the feeding of ethylene carbonate is completed, the temperature is raised to 145 - 150 °C for ring-opening polymerization reaction for 8 - 10 hours; after the reaction is completed, the temperature is lowered to 20 - 30 °C, and the product is cycloalkanoic acid amide polyether ester; The reaction formula is as follows: 。 6. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 5, characterized in that The molar ratio of cycloalkanoic acid amide to ethylene carbonate is 1:10; the addition amount of the catalyst potassium hydroxide is 5 - 10‰ of the total mass of cycloalkanoic acid amide and ethylene carbonate.

7. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 2, characterized in that The specific method of the sulfonation reaction in step c is as follows: Add the naphthenic acid amide polyether ester prepared in step b and solvent petroleum ether into the sulfonation reactor, start stirring, then add sodium hydroxide, heat the sulfonation reactor to 80 - 90 °C, and carry out the alkalization reaction for 1 - 2 hours under reflux; after the alkalization is completed, lower the temperature of the sulfonation reactor to 60 - 70 °C, dropwise add an aqueous solution of 40% sodium 3-chloro-2-hydroxypropane sulfonate, control the dropping time within 0.5 - 1 hour, and continue the reaction for 4 - 6 hours at 60 - 70 °C after the dropping is completed; after the reaction is completed, remove the solvent petroleum ether under negative pressure under stirring; after the solvent petroleum ether is removed, add deionized water to the reactor to prepare an aqueous solution, stir for 0.5 - 1 hour and take out the product to obtain a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant product; The reaction formula is as follows: ， The solvent petroleum ether mentioned has a boiling range of 60 - 90 °C, and the addition amount of the petroleum ether solvent is 50% of the mass of the naphthenic acid amide polyether ester; the molar ratio of the naphthenic acid amide polyether ester to sodium hydroxide is 1:1 - 1.5; the molar ratio of the naphthenic acid amide polyether ester to sodium 3-chloro-2-hydroxypropane sulfonate is 1:1 - 1.5; the addition amount of deionized water is twice the total mass of the naphthenic acid amide polyether ester and sodium 3-chloro-2-hydroxypropane sulfonate.

8. The preparation method of a naphthenic acid amide polyether ester sulfonate ultra-low interfacial tension surfactant according to claim 7, characterized in that The molar ratio of the naphthenic acid amide polyether ester to sodium hydroxide is 1:1.05; the molar ratio of the naphthenic acid amide polyether ester to sodium 3-chloro-2-hydroxypropane sulfonate is 1:1.05.

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