Oil displacement surfactant capable of being used for hypersalinity oil reservoir

Abstract

The invention belongs to the technical field of oil and gas field chemistry, and particularly discloses an oil displacement surfactant capable of being used for hypersalinity oil reservoirs. The surfactant for oil displacement provided by the invention is prepared from the following components in percentage by weight: 65 percent to 70 percent of deionized water, 14 percent to 19 percent of hexadecyl dimethyl hydroxypropyl sulfobetaine, 6 percent to 8 percent of coco fatty acid diethanol amide, 4 percent to 5 percent of DL-camphor sodium sulfonate, 2 percent to 3 percent of alpha-terpilenol and 1 percent of an agricultural organic silicon surfactant MY20001. And 1% of silicone resin polyether emulsion, wherein the sum of the above components is 100%. The surfactant for oil displacement is high in stability, the interfacial tension in a high-salinity oil reservoir can be within 0.01 mN / m, and the surfactant has good oil displacement efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field chemistry, and particularly relates to a surfactant for enhanced oil recovery that can be used in high salinity reservoirs. Background Art

[0002] The new technology of tertiary oil recovery is represented by surfactant flooding. A key factor affecting the oil displacement efficiency of surfactant flooding is the interfacial tension. It can be said that the lower the oil-water interfacial tension, the more beneficial it is for oil displacement. Comparatively speaking, adding anionic sulfonates and carboxylates surfactants to the surfactant flooding compound system can achieve a lower interfacial tension effect. However, common anionic surfactants represented by alkyl benzene sulfonates have poor salt resistance, especially poor resistance to divalent salts, resulting in a significant reduction in surface activity in the surfactant flooding compound system in high salinity systems, especially in systems with a relatively high concentration of divalent salts, and thus a significant increase in interfacial tension, which in turn affects the oil displacement efficiency. For carbonate oil reservoirs with a relatively high divalent salt concentration (above 50000 mg / L), the interfacial tension of the surfactant products for enhanced oil recovery on the market basically cannot reach within 0.01 mN / m, so efficient oil displacement cannot be achieved. There is an urgent need for a low interfacial tension oil displacement agent product that can resist a relatively high concentration of divalent salts on the market. Summary of the Invention

[0003] Aiming at the deficiencies existing in the above-mentioned prior art, the purpose of the present invention is to provide a surfactant for enhanced oil recovery that can be used in high salinity reservoirs and its preparation method. The surfactant for enhanced oil recovery of the present invention has high stability, and the interfacial tension in high salinity reservoirs can reach within 0.01 mN / m, having good oil displacement efficiency.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A surfactant for enhanced oil recovery that can be used in high salinity reservoirs, calculated by weight percentage, includes the following components: deionized water 65%-70%, cetylstearyl dimethyl hydroxypropyl sulfobetaine 14%-19%, coconut fatty acid diethanolamide 6%-8%, racemic camphorsulfonic acid sodium 4%-5%, α-terpineol 2%-3%, agricultural organosilicon surfactant MY2000 1%, silicone polyether emulsion 1%, and the sum of the above components is 100%. Among them, the silicone polyether emulsion is preferably FM550 type silicone polyether emulsion.

[0006] A preparation method of a surfactant for enhanced oil recovery that can be used in high salinity reservoirs, includes the following steps: weighing raw materials according to the ratio, and stirring and mixing deionized water, cetylstearyl dimethyl hydroxypropyl sulfobetaine, coconut fatty acid diethanolamide, racemic camphorsulfonic acid sodium, α-terpineol, agricultural organosilicon surfactant MY2000 and silicone polyether emulsion evenly, then the surfactant for enhanced oil recovery that can be used in high salinity reservoirs is obtained.

[0007] More specifically, it includes the following steps:

[0008] Step 1: Weigh the raw materials according to the ratio. Pour all the deionized water into the reaction kettle, start stirring at a speed of 130 r / min - 170 r / min, and start heating. When the temperature reaches 45°C - 50°C, add cetylstearyl dimethyl hydroxypropyl sulfobetaine into the reaction kettle. After stirring into a uniform transparent liquid, add racemic camphorsulfonic acid sodium salt and coconut fatty acid diethanolamide in sequence. Keep the temperature at 45°C - 50°C and continue stirring for 1.0 h - 1.5 h to obtain a light yellow transparent liquid;

[0009] Step 2: Lower the stirring speed to 60 r / min - 90 r / min, add α-terpineol into the reaction kettle, stir for 0.5 h, and then add agricultural organosilicon surfactant MY2000 and silicone polyether emulsion in sequence, and continue stirring for 0.5 h - 1.0 h. The obtained light yellow translucent microemulsion is the surfactant for enhanced oil recovery.

[0010] Use of the above surfactant for enhanced oil recovery or the surfactant for enhanced oil recovery prepared by the above method in enhanced oil recovery in high salinity reservoir formations. Among them, the mass concentration of monovalent salts in the high salinity reservoir formation does not exceed 19% and / or the mass concentration of divalent salts does not exceed 6%. The reservoir formation includes sandstone and / or carbonate rock.

[0011] The surfactant for enhanced oil recovery applicable to high salinity reservoirs of the present invention adopts a compound combination of zwitterionic surfactant, non-ionic surfactant and anionic surfactant. In the present invention, cetylstearyl dimethyl hydroxypropyl sulfobetaine is used as the main component of the oil displacement agent, racemic camphorsulfonic acid sodium salt is used as the key component, coconut fatty acid diethanolamide and α-terpineol are used as auxiliary components, and silicone polyether emulsion and agricultural organosilicon surfactant MY2000 are used as enhancing components. It should be particularly noted that the present invention selects racemic camphorsulfonic acid sodium salt as the anionic surfactant, which has good ability to resist divalent salts, that is, it can significantly reduce the interfacial tension in a high salinity system. The silicone polyether emulsion can enhance the salt resistance of racemic camphorsulfonic acid sodium salt within a certain range. Coconut fatty acid diethanolamide has good compatibility with both cetylstearyl dimethyl hydroxypropyl sulfobetaine and racemic camphorsulfonic acid sodium salt. The compound use of coconut fatty acid diethanolamide and α-terpineol with racemic camphorsulfonic acid sodium salt can further reduce the interfacial tension. Agricultural organosilicon surfactant MY2000 can also reduce the interfacial tension of the whole system within a certain range. However, the effect is not good when racemic camphorsulfonic acid sodium salt is used alone or accounts for too large a proportion in the system. It is the appropriate raw material combination formula that endows this application with high-stability oil displacement performance. In the present invention, when the proportion of racemic camphorsulfonic acid sodium salt in the system exceeds 5 wt%, the stability of the system decreases, the interfacial tension becomes larger, and the salt resistance performance becomes worse.

[0012] It is precisely because of the above scheme that the oil displacement surfactant of the present invention can reach 10% in low-salinity oil reservoirs with a monovalent salt concentration of less than 5% and a divalent salt concentration of less than 1% within 120°C. -3 The interfacial tension can be controlled within 10 mN / m, and the interfacial tension can be controlled within 10 mN / m in high-salinity reservoirs with a monovalent salt concentration of 6%-19% and a divalent salt concentration of 1.9%-6%. -2 mN / m value, so it has good oil recovery efficiency in high-mineralization reservoirs, and has excellent oil recovery performance in both sandstone and carbonate rocks, effectively increasing oil well production. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0014] The present invention provides a technical solution: a surfactant for oil displacement that can be used in high-mineralization oil reservoirs.

[0015] Embodiment 1:

[0016] The surfactant for oil displacement is composed of the following components: 65kg of deionized water, 19kg of cetyl dimethyl hydroxypropyl sulfobetaine, 4kg of cyclocamphor sulfonate sodium, 8kg of coconut oil diethanolamide, 2kg of α-pinene alcohol, 1kg of agricultural organic silicon surfactant MY2000, and 1kg of FM550 silicone resin polyether emulsion, a total of 100kg, which is obtained by the following method:

[0017] Weigh the raw materials according to the ratio, pour all 65kg of deionized water into the reactor, start stirring at a speed of 150r / min, and start heating. When the temperature reaches 45°C, add 19kg of hexadecyl dimethyl hydroxypropyl sulfobetaine into the reactor, stir to form a uniform transparent liquid, then add 4kg of sodium camphorsulfonate and 8kg of coconut acid diethanolamide in sequence, maintain 45°C-50°C, continue stirring for 1.0h, and obtain a light yellow transparent liquid; reduce the stirring speed to 90r / min, add 2kg of α-pineneol into the reactor, stir for 0.5h, then add 1kg of agricultural organosilicon surfactant MY2000 and 1kg of FM550 silicone resin polyether emulsion in sequence, continue stirring for 1.0h, and the obtained light yellow translucent microemulsion is the surfactant sample for oil displacement.

[0018] Then the interfacial tension and oil washing rate of the samples were tested.

[0019] Interfacial tension test method: Prepare 3 groups of salt solutions with high, medium, and low salinities (in the high-salinity solution, the sodium chloride content is 18.4%, the calcium chloride content is 5.0%, the magnesium chloride content is 1.0%, and the potassium chloride content is 0.3%; in the medium-salinity solution, the sodium chloride content is 5.8%, the calcium chloride content is 1.6%, the magnesium chloride content is 0.3%, and the potassium chloride content is 0.2%; in the low-salinity solution, the sodium chloride content is 0.5%, the calcium chloride content is 0.3%, the magnesium chloride content is 0.1%, and the potassium chloride content is 0.1%, and each content refers to the mass percentage). Add 0.3 wt% of the surfactant for enhanced oil recovery to each group to obtain 3 groups of 0.3% surfactant salt solutions with different salinities. The experimental temperature is 54 °C. Use a TX-500C rotary drop interfacial tension meter. Inject each of the 3 groups of 0.3% surfactant salt solutions for enhanced oil recovery into the sample test tube, then inject the internal phase coal oil droplets. Tighten the test tube cap, adjust the rotation speed to 5000 r / min, measure the oil droplet diameter and length at 5-minute intervals, and the measurement time is 120 minutes. There are a total of 24 interfacial tension data for each sample. Calculate the average to obtain the interfacial tensions of the 3 groups of 0.3% surfactant salt solutions with different salinities. The interfacial tension test value is accurate to 10 -6 .

[0020] The oil washing rate test is carried out according to the method of Q / SH 1020 2191-2013 "Technical Requirements for the Selection of Surfactants for Enhanced Oil Recovery". Among them, there are two types of simulated formation sands, namely silica sand and calcium carbonate sand with particle sizes of 30-40 mesh. The crude oil used in the test is the crude oil with an API gravity of 33.4 produced by a certain oil company in the Middle East. The test temperature is 120 °C. The concentration of the surfactant solution for enhanced oil recovery is 0.3%. The salinity of the surfactant solution for enhanced oil recovery is divided into two groups. One group is the surfactant solution with fresh water without salt, and the other group is the surfactant solution with high salinity: the sodium chloride content is 18.4%, the calcium chloride content is 5.0%, the magnesium chloride content is 1.0%, and the potassium chloride content is 0.3%. Each content refers to the mass percentage).

[0021] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example 1 is as follows in Table 1:

[0022] Table 1

[0023] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 83.5 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 72.5 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 70.3 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 63.5 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.007025 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.002229 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.000397

[0024] Example 2:

[0025] The surfactant for oil displacement is composed of the following components: 70 kg of deionized water, 14 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of racemic camphorsulfonic acid sodium salt, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organosilicon surfactant MY2000, 1 kg of FM550 silicone resin polyether emulsion, with a total of 100 kg, and is obtained by the following method:

[0026] Weigh the raw materials according to the ratio. Pour all 70 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45°C, add 14 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of racemic camphorsulfonic acid sodium salt and 6 kg of coconut fatty acid diethanolamide in sequence, keep the temperature at 45°C - 50°C, and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural organosilicon surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence, and continue stirring for 1.0 h. The obtained light yellow translucent microemulsion is the surfactant sample for oil displacement.

[0027] The performance index test of the surfactant sample for oil displacement obtained in Example 2 is as shown in Table 2 below:

[0028] Table 2

[0029] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 85.0 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 75.3 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 68.8 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 61.3 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.008931 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.003426 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.000312

[0030] Example 3:

[0031] The surfactant for oil displacement is composed of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of racemic camphorsulfonic acid sodium salt, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organosilicon surfactant MY2000, 1 kg of FM550 silicone resin polyether emulsion, with a total of 100 kg, and is obtained by the following method:

[0032] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45 °C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of racemic camphorsulfonic acid sodium and 6 kg of coconut fatty acid diethanolamide in sequence. Keep the temperature at 45 °C - 50 °C and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence. Continue stirring for 1.0 h, and the obtained light yellow translucent microemulsion is the surfactant sample for enhanced oil recovery.

[0033] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example 3 is as follows in Table 3:

[0034] Table 3

[0035]

[0036]

[0037] Example 4:

[0038] The surfactant for enhanced oil recovery is composed of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural silicone surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, with a total of 95 kg. It is obtained by the following method:

[0039] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45 °C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 6 kg of coconut fatty acid diethanolamide. Keep the temperature at 45 °C - 50 °C and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence. Continue stirring for 1.0 h, and the obtained light yellow translucent microemulsion is the surfactant sample for enhanced oil recovery.

[0040] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example 4 is as follows in Table 4:

[0041] Table 4

[0042] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 75.1 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 65.8 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 59.4 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 54.3 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.032231 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.020579 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.009702

[0043] Compared with Example 3, in Example 4, the component of racemic camphorsulfonic acid sodium, an anionic surfactant, was not added. As a result, the interfacial tension of the surfactant sample for enhanced oil recovery increased significantly while the oil washing rate decreased significantly.

[0044] Example 5:

[0045] The surfactant for enhanced oil recovery consists of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of fatty acid methyl ester sulfonate, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organosilicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, totaling 100 kg, and is obtained by the following method:

[0046] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45°C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of fatty acid methyl ester sulfonate and 6 kg of coconut fatty acid diethanolamide in sequence, maintain the temperature at 45°C - 50°C, and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural organosilicon surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence, and continue stirring for 1.0 h. The obtained light yellow translucent microemulsion is the surfactant sample for enhanced oil recovery.

[0047] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example 5 is as shown in Table 5 below:

[0048] Table 5

[0049] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 80.3 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 73.5 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 62.1 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 58.7 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.017354 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.009551 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.000476

[0050] Compared with Example 3, in Example 5, racemic camphorsulfonic acid sodium in the raw materials was replaced with fatty acid methyl ester sulfonate. Fatty acid methyl ester sulfonate belongs to the type with relatively strong salt resistance among anionic surfactants. The sample prepared with it indeed has relatively better interfacial tension and oil washing rate in a medium-high salinity system, but it is not as good as the sample prepared with racemic camphorsulfonic acid sodium. This may be because racemic camphorsulfonic acid sodium has strong salt resistance and better compatibility with the components in the system of this application.

[0051] Example 6:

[0052] The surfactant for oil displacement is composed of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of racemic camphorsulfonic acid sodium, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, and 1 kg of agricultural organosilicon surfactant MY2000, with a total of 99 kg, and is obtained by the following method:

[0053] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45 °C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of racemic camphorsulfonic acid sodium and 6 kg of coconut fatty acid diethanolamide in sequence, maintain the temperature at 45 °C - 50 °C, and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural organosilicon surfactant MY2000, and continue stirring for 1.0 h. The obtained light yellow translucent microemulsion is the surfactant sample for oil displacement.

[0054] The performance index test of the surfactant sample for oil displacement obtained in Example VI is as shown in Table 6 below:

[0055] Table 6

[0056] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 82.8 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 73.5 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 63.1 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 58.8 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.016765 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.008328 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.000237

[0057] Compared with Example III, Example VI does not add the non-ionic surfactant component of FM550 silicone resin polyether emulsion. According to the test results, this has no negative impact on the interfacial tension and oil washing rate of the low salinity system, but has some negative impacts on the medium and high salinity systems. Especially in the high salinity system, the sample cannot reach an interfacial tension within 10 -2 mN / m, indicating that the FM550 silicone resin polyether emulsion can enhance the salt resistance of the system of this application within a small range. This may be because the combined arrangement of the silicone resin polyether emulsion and racemic camphorsulfonic acid sodium at the microscopic level enhances the salt resistance.

[0058] Example VII:

[0059] The surfactant for oil displacement is composed of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of racemic camphorsulfonic acid sodium, 6 kg of coconut fatty acid diethanolamide, 1 kg of agricultural organosilicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, with a total of 97 kg, and is obtained by the following method:

[0060] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating up. When the temperature reaches 45 °C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of racemic camphorsulfonic acid sodium and 6 kg of coconut fatty acid diethanolamide in sequence. Keep the temperature at 45 °C - 50 °C and continue stirring for 1.0 h to obtain a light yellow transparent liquid. Lower the stirring speed to 90 r / min, then add 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence, and continue stirring for 1.0 h. The obtained light yellow transparent liquid is the surfactant sample for enhanced oil recovery.

[0061] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example Seven is as follows in Table 7:

[0062] Table 7

[0063] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 75.3 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 68.2 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 63.8 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 58.1 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.018196 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.007963 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.001085

[0064] Compared with Example Three, in Example Seven, the component of the non-ionic surfactant α-terpineol is not added. The results show that the interfacial tension increases and the oil washing performance decreases. Also, according to multiple groups of experiments in addition, we find that this is mainly because the interfacial tension of the compound use of α-terpineol and racemic camphorsulfonic acid sodium is lower than that of the racemic camphorsulfonic acid sodium used alone.

[0065] Example Eight:

[0066] The surfactant for enhanced oil recovery is composed of the following components: 68 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of racemic camphorsulfonic acid sodium, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, and 1 kg of FM550 silicone resin polyether emulsion, with a total of 99 kg, and is obtained by the following method:

[0067] Weigh the raw materials according to the ratio. Pour all 68 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating up. When the temperature reaches 45 °C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 5 kg of racemic camphorsulfonic acid sodium and 6 kg of coconut fatty acid diethanolamide in sequence. Keep the temperature at 45 °C - 50 °C and continue stirring for 1.0 h to obtain a light yellow transparent liquid. Lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, then add 1 kg of FM550 silicone resin polyether emulsion, and continue stirring for 1.0 h. The obtained light yellow semi-transparent microemulsion is the surfactant sample for enhanced oil recovery.

[0068] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example Eight is as follows in Table 8:

[0069] Table 8

[0070] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 74.7 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 66.9 CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 69.8 SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) ≥60.0 61.6 Interfacial Tension of High-Salinity Solution (mN / m) ≤0.01 0.009682 Interfacial Tension of Medium-Salinity Solution (mN / m) ≤0.01 0.003918 Interfacial Tension of Low-Salinity Solution (mN / m) ≤0.001 0.001237

[0071] Compared with Example 3, the component of agricultural organosilicon surfactant MY2000 was not added in Example 8. It was found that the interfacial tension increased slightly and the oil washing rate decreased slightly, so that the sample could not reach an ultra-low interfacial tension within 10 -3 mN / m in the low salinity system.

[0072] Example 9:

[0073] The surfactant for enhanced oil recovery consists of the following components: 67 kg of deionized water, 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, 6 kg of racemic camphorsulfonic acid sodium, 6 kg of coconut fatty acid diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organosilicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, with a total of 100 kg. It is obtained by the following method:

[0074] Weigh the raw materials according to the ratio. Pour all 67 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45°C, add 16 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 6 kg of racemic camphorsulfonic acid sodium and 6 kg of coconut fatty acid diethanolamide in sequence, keep the temperature at 45°C - 50°C, and continue stirring for 1.0 h to obtain a light yellow transparent liquid; lower the stirring speed to 90 r / min, add 3 kg of α-terpineol to the reaction kettle, stir for 0.5 h, and then add 1 kg of agricultural organosilicon surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion in sequence, and continue stirring for 1.0 h. The obtained light yellow translucent microemulsion is the surfactant sample for enhanced oil recovery.

[0075] The performance index test of the surfactant sample for enhanced oil recovery obtained in Example 9 is as follows in Table 9:

[0076] Table 9

[0077] Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) ≥70.0 73.2 SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results CaCO₃ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in Freshwater System at 120℃ (%) CaCO₃ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) SiO₂ Sand Washing Oil Removal Rate in High-Salinity System at 120℃ (%) Interfacial Tension of High-Salinity Solution (mN / m) Interfacial Tension of Medium-Salinity Solution (mN / m) Interfacial Tension of Low-Salinity Solution (mN / m) Test Items Recommended Index Requirements Test Results ≥70.0 66.5 120℃ High-salinity System Calcium Carbonate Sand Oil Washing Rate (%) ≥60.0 64.1 120℃ High-salinity System Silicon Dioxide Sand Oil Washing Rate (%) ≥60.0 57.9 High-salinity Solution Interfacial Tension (mN / m) ≤0.01 0.019324 Medium-salinity Solution Interfacial Tension (mN / m) ≤0.01 0.006952 Low-salinity Solution Interfacial Tension (mN / m) ≤0.001 0.001753

[0078] In Example 9, we increased the proportion of racemic camphorsulfonic acid sodium to 6%. It was found that the interfacial tension of the sample increased slightly and the oil washing performance decreased. According to another experiment we did, if the racemic camphorsulfonic acid sodium exceeded 5%, the oil washing performance of the sample would decrease. This may be because the amount of anionic surfactants such as racemic camphorsulfonic acid sodium that can be accommodated in the high-performance compounding system of this application is limited.

[0079] Example 10:

[0080] The surfactant for oil displacement is composed of the following components: 65 kg of deionized water, 19 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine, and 8 kg of coconut fatty acid diethanolamide, with a total of 92 kg. It is obtained by the following method:

[0081] Weigh the raw materials according to the ratio. Pour all 65 kg of deionized water into the reaction kettle, start stirring at a speed of 150 r / min, and start heating. When the temperature reaches 45°C, add 19 kg of cetylstearyl dimethyl hydroxypropyl sulfobetaine to the reaction kettle. After stirring into a uniform transparent liquid, add 8 kg of coconut fatty acid diethanolamide, keep the temperature at 45°C - 50°C, and continue stirring for 0.5 h to obtain a light yellow transparent liquid, which is the surfactant sample for oil displacement.

[0082] The performance index test of the surfactant sample for oil displacement obtained in Example X is as shown in Table 10 below:

[0083] Table 10

[0084] Test Items Recommended Index Requirements Test Results 120℃ Freshwater System Calcium Carbonate Sand Oil Washing Rate (%) ≥70.0 68.6 120℃ Freshwater System Silicon Dioxide Sand Oil Washing Rate (%) ≥70.0 61.5 120℃ High-salinity System Calcium Carbonate Sand Oil Washing Rate (%) ≥60.0 62.1 120℃ High-salinity System Silicon Dioxide Sand Oil Washing Rate (%) ≥60.0 56.9 High-salinity Solution Interfacial Tension (mN / m) ≤0.01 0.019157 Medium-salinity Solution Interfacial Tension (mN / m) ≤0.01 0.017235 Low-salinity Solution Interfacial Tension (mN / m) ≤0.001 0.016625

[0085] In Example X, only cetylstearyl dimethyl hydroxypropyl sulfobetaine and coconut fatty acid diethanolamide are used as active raw materials. It can be seen that the interfacial tension of this sample is not low enough in both low-salinity and high-salinity systems. However, the change range of the interfacial tension in the high-salinity system is smaller than that in the low-salinity system, indicating that the compound of cetylstearyl dimethyl hydroxypropyl sulfobetaine and coconut fatty acid diethanolamide in an appropriate ratio has good salt resistance. Combining with the results of Example IV, it can also be seen that the anionic surfactant component of racemic camphorsulfonic acid sodium has a great influence on the performance of the system of this application.

[0086] In addition, we also tested the oil displacement agent SOL ND15 of Suoneng Chemical (Shanghai) Co., Ltd. SOL ND15 belongs to a surfactant oil displacement agent product with relatively good performance in the industry.

[0087] The performance index test of SOL ND15 is as shown in Table 11 below:

[0088] Table 11

[0089]

[0090]

[0091] It can be seen that the oil washing rate of the oil displacement agent SOL ND15 in the fresh water system is close to that of this application, but its interfacial tension value is significantly higher than that of this application in the medium- and high-salinity systems. Therefore, the oil washing rate in the high-salinity system is lower than that of this application.

[0092] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A surfactant for oil displacement that can be used in high-mineralization oil reservoirs, characterized in that: The invention comprises the following components by weight percentage: 65%-70% of deionized water, 14%-19% of cetearyl dimethyl hydroxypropyl sulfobetaine, 6%-8% of coconut acid diethanolamide, 4%-5% of sodium camphorsulfonate, 2%-3% of α-pineneol, 1% of agricultural organic silicon surfactant MY2000, and 1% of silicone resin polyether emulsion. The total of the above components is 100%.

2. The surfactant for oil displacement that can be used in high-mineralization oil reservoirs according to claim 1, characterized in that: The silicone resin polyether emulsion is FM550 silicone resin polyether emulsion.

3. The method for preparing a surfactant for oil displacement in a high-mineralization oil reservoir according to any one of claims 1 to 2, characterized in that: The steps include: Step 1: weigh the raw materials according to the ratio, pour all the deionized water into the reactor, start stirring at a speed of 130r / min-170r / min, and start heating. When the temperature reaches 45°C-50°C, add 16-octadecyl dimethyl hydroxypropyl sulfobetaine to the reactor, stir to form a uniform transparent liquid, then add sodium camphorsulfonate and coconut oil diethanolamide in sequence, maintain 45°C-50°C, continue stirring for 1.0h-1.5h, and obtain a light yellow transparent liquid; Step 2: Lower the stirring speed to 60r / min-90r / min, add α-pineneol to the reactor, stir for 0.5h, then add agricultural organosilicon surfactant MY2000 and silicone resin polyether emulsion in sequence, and continue stirring for 0.5h-1.0h. The light yellow translucent microemulsion obtained is the surfactant for oil displacement.

4. Use of the oil recovery surfactant according to any one of claims 1 to 2 or the oil recovery surfactant prepared by the method according to claim 3 in oil recovery from high-mineralization oil reservoir formations.

5. The use according to claim 4, characterized in that: The mass concentration of monovalent salt in the high-mineralization oil reservoir stratum does not exceed 19% and / or the mass concentration of divalent salt does not exceed 6%.

6. The use according to claim 4, characterized in that: The reservoir formation includes sandstone and / or carbonate rock.

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