A surfactant for oil displacement that can be used in high-salinity oil reservoirs

Abstract

The present invention belongs to the field of oil and gas field chemical technology, and specifically discloses a surfactant for oil displacement that can be used in high-mineralization oil reservoirs. The surfactant for oil displacement provided by the present invention comprises the following components by weight percentage: deionized water 65%-70%, hexadecyl dimethyl hydroxypropyl sulfobetaine 14%-19%, coconut oil diethanolamide 6%-8%, sodium camphorsulfonate 4%-5%, α-terpineol 2%-3%, agricultural organosilicon surfactant MY20001%, silicone resin polyether emulsion 1%, and the sum of the above components is 100%. The surfactant for oil displacement has high stability, and the interfacial tension can reach within 0.01mN / m in high-mineralization oil reservoirs, with good oil displacement efficiency.

Description

Technical Field

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

[0002] Surfactant flooding is a new technology for tertiary oil recovery, and a key factor affecting the efficiency of surfactant flooding is interfacial tension. It can be said that the lower the oil-water interfacial tension, the more beneficial it is for oil recovery. In comparison, adding anionic sulfonate and carboxylate surfactants to the flooding surfactant compound system can achieve a lower interfacial tension effect. However, common anionic surfactants represented by alkyl benzene sulfonates have poor salt resistance, especially resistance to divalent salts. As a result, the surface activity of the flooding surfactant compound system is often greatly reduced in high-mineralization systems, especially high-concentration divalent salt systems, resulting in a significant increase in interfacial tension, which in turn affects the oil recovery efficiency. For carbonate oil reservoirs with high divalent salt concentrations (above 50,000 mg / L), the interfacial tension of commercially available flooding surfactant products basically cannot reach within 0.01 mN / m, making it impossible to achieve efficient oil recovery. The market is in urgent need of a low-interfacial tension flooding agent product that can resist high-concentration divalent salts. Summary of the Invention

[0003] In response to the above-mentioned shortcomings in the prior art, the present invention aims to provide an oil displacement surfactant that can be used in highly salinized oil reservoirs and a method for preparing the same. The oil displacement surfactant of the present invention has high stability, can achieve an interfacial tension of less than 0.01 mN / m in highly salinized oil reservoirs, and exhibits good oil displacement efficiency.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A surfactant for oil displacement that can be used in highly salinized oil reservoirs comprises the following components, calculated by weight: 65%-70% deionized water, 14%-19% cetearyl dimethyl hydroxypropyl sulfobetaine, 6%-8% cocoyl diethanolamide, 4%-5% sodium camphorsulfonate, 2%-3% α-terpineol, 1% MY2000, an agricultural organic silicone surfactant, and 1% silicone resin polyether emulsion, the total of which is 100%. The silicone resin polyether emulsion is preferably FM550 silicone resin polyether emulsion.

[0006] A method for preparing an oil-displacement surfactant that can be used in high-mineralization oil reservoirs comprises the following steps: weighing raw materials according to a ratio, and uniformly stirring and mixing deionized water, cetearyl dimethyl hydroxypropyl sulfobetaine, cocoyl diethanolamide, sodium camphorsulfonate, α-terpineol, agricultural organosilicon surfactant MY2000, and silicone resin polyether emulsion to obtain the oil-displacement surfactant that can be used in high-mineralization oil reservoirs.

[0007] More specifically, the following steps are included:

[0008] 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 cetostearyl dimethyl hydroxypropyl sulfobetaine to the reactor, stir to form a uniform transparent liquid, and then add sodium camphorsulfonate and cocoyl diethanolamide in sequence. Maintain 45°C-50°C and continue stirring for 1.0h-1.5h to obtain a light yellow transparent liquid;

[0009] Step 2: Lower the stirring speed to 60r / min-90r / min, add α-terpineol to the reactor, stir for 0.5h, then add agricultural silicone 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.

[0010] The use of the above-mentioned oil recovery surfactant or the oil recovery surfactant prepared by the above-mentioned method in oil recovery from a high-mineralization oil reservoir. The mass concentration of monovalent salts in the high-mineralization oil reservoir is no more than 19% and / or the mass concentration of divalent salts is no more than 6%. The oil reservoir comprises sandstone and / or carbonate rock.

[0011] The present invention's oil-displacing surfactant, which can be used in highly salinized oil reservoirs, comprises a composite combination of a zwitterionic surfactant, a nonionic surfactant, and an anionic surfactant. The oil-displacing agent comprises hexadecyldimethylhydroxypropylsulfobetaine as the main component, sodium camphorsulfonate as the key component, coconut diethanolamide and α-terpineol as auxiliary components, and a silicone resin polyether emulsion and the agricultural organosilicon surfactant MY2000 as reinforcing components. It should be noted that the present invention selects DL sodium camphorsulfonate as an anionic surfactant, which has good anti-divalent salt ability, that is, it can significantly reduce interfacial tension under high mineralization system, silicone resin polyether emulsion can enhance the salt resistance of DL sodium camphorsulfonate within a certain range, coconut oil diethanolamide and hexadecyl dimethyl hydroxypropyl sulfobetaine and DL sodium camphorsulfonate both have good compatibility, coconut oil diethanolamide and α-terpineol can further reduce interfacial tension when compounded with DL sodium camphorsulfonate, agricultural silicone surfactant MY2000 can reduce the interfacial tension of the whole system within a certain range, but DL sodium camphorsulfonate is used alone or accounts for too large an effect in the system, and it is not good, it is just the right raw material combination formula that gives the application with high stability oil displacement performance. In the present invention, DL sodium camphorsulfonate accounts for more than 5wt% in the system, the stability of the system decreases, the interfacial tension becomes larger, and the salt resistance deteriorates.

[0012] Because of the above scheme, the surfactant for oil displacement 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 is 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-salinity 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 solutions 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 intended to limit the present invention.

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

[0015] Example 1:

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

[0017] The raw materials were weighed according to the ratio, and 65 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 19 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 4 kg of sodium camphorsulfonate and 8 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 2 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

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

[0019] Interfacial tension test method: Three groups of salt solutions with different salinities of high, medium and low were prepared (the high salinity solution contained 18.4% sodium chloride, 5.0% calcium chloride, 1.0% magnesium chloride and 0.3% potassium chloride; the medium salinity solution contained 5.8% sodium chloride, 1.6% calcium chloride, 0.3% magnesium chloride and 0.2% potassium chloride; and the low salinity solution contained 0.5% sodium chloride, 0.3% calcium chloride, 0.1% magnesium chloride and 0.1% potassium chloride, all of which are expressed as percentages by mass), and 0.3% of an oil displacement surfactant was added to each solution to obtain three groups of 0.3% oil displacement surfactant salt solutions with different salinities. The experimental temperature was 54°C. Using a TX-500C rotating drop interfacial tension meter, three groups of 0.3% oil displacement surfactant salt solutions were injected into the sample test tube, and then the internal phase kerosene oil drop was injected. The test tube cap was tightened and the rotation speed was adjusted to 5000 r / min. The oil drop diameter and length were measured at 5-minute intervals. The measurement time was 120 minutes. A total of 24 interfacial tension data were collected for each sample. The average was taken to calculate the interfacial tension of the three groups of 0.3% oil displacement surfactant salt solutions with different salinities. The interfacial tension test value was accurate to 10 -6 .

[0020] The oil wash rate test was performed in accordance with the method of Q / SH 1020 2191-2013 "Technical Requirements for Selection of Surfactants for Oil Displacement". There were two types of simulated formation sand, 30-40 mesh silica sand and calcium carbonate sand. The crude oil used in the test was crude oil with an API gravity of 33.4 produced by a Middle Eastern oil company. The test temperature was 120°C. The concentration of the surfactant solution for oil displacement was 0.3%. The salinity of the surfactant solution for oil displacement was divided into two groups: one group was a surfactant solution of salt-free fresh water, and the other group was a surfactant solution with a high salinity: the sodium chloride content was 18.4%, the calcium chloride content was 5.0%, the magnesium chloride content was 1.0%, and the potassium chloride content was 0.3%. All contents are expressed in percentage by mass.

[0021] The performance indexes of the surfactant samples for oil displacement obtained in Example 1 are shown in Table 1 below:

[0022] Table 1

[0023] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 83.5 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 72.5 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 70.3 120℃ high salinity silica sand oil washing rate (%) ≥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 oil displacement surfactant is composed of the following components: 70 kg of deionized water, 14 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 100 kg, which is obtained by the following method:

[0026] The raw materials were weighed according to the ratio, and 70 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 14 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 5 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

[0027] The performance index test results of the surfactant samples for oil displacement obtained in Example 2 are shown in Table 2 below:

[0028] Table 2

[0029] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 85.0 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 75.3 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 68.8 120℃ high salinity silica sand oil washing rate (%) ≥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 oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 100 kg, which is obtained by the following method:

[0032] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 5 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

[0033] The performance indexes of the surfactant samples for oil displacement obtained in Example 3 are shown in Table 3 below:

[0034] Table 3

[0035]

[0036]

[0037] Example 4:

[0038] The oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 95 kg, and is obtained by the following method:

[0039] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 6 kg of coconut acid diethanolamide was added. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

[0040] The performance indexes of the surfactant samples for oil displacement obtained in Example 4 are shown in Table 4 below:

[0041] Table 4

[0042] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 75.1 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 65.8 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 59.4 Silica sand oil washing 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, Example 4 does not add the anionic surfactant component of sodium camphorsulfonate. As a result, the interfacial tension of the obtained oil displacement surfactant sample is significantly increased and the oil washing rate is significantly decreased.

[0044] Embodiment 5:

[0045] The oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of fatty acid methyl ester sulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 100 kg, which is obtained by the following method:

[0046] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 5 kg of fatty acid methyl ester sulfonate and 6 kg of coconut acid diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

[0047] The performance indexes of the surfactant samples for oil displacement obtained in Example 5 are shown in Table 5 below:

[0048] Table 5

[0049] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 80.3 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 73.5 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 62.1 120℃ high salinity silica sand oil washing rate (%) ≥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, Example 5 replaces the raw material DL-sodium camphorsulfonate with fatty acid methyl ester sulfonate. Fatty acid methyl ester sulfonate is a kind of anionic surfactant with strong salt resistance. The sample prepared with it does have relatively good interfacial tension and oil washing rate in medium and high salinity systems, but it is not as good as the sample prepared with DL-sodium camphorsulfonate. This may be because DL-sodium camphorsulfonate has strong salt resistance and better compatibility with the components in the system of this application.

[0051] Example 6:

[0052] The oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, and 1 kg of agricultural organic silicon surfactant MY2000, a total of 99 kg, which is obtained by the following method:

[0053] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 5 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 was added and stirring was continued for 1.0 h. The light yellow translucent microemulsion obtained was the surfactant sample for oil displacement.

[0054] The performance indexes of the surfactant samples for oil displacement obtained in Example 6 are shown in Table 6 below:

[0055] Table 6

[0056] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 82.8 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 73.5 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 63.1 Silica sand oil washing 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 3, Example 6 does not add the nonionic surfactant component 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 impact on the medium and high salinity systems, especially in the high salinity system, the sample cannot reach 10 -2 The interfacial tension is within mN / m, indicating that the FM550 silicone resin polyether emulsion can enhance the salt resistance of the system of the present application in a small range. This may be because the combination arrangement of the silicone resin polyether emulsion and the rotic sodium camphorsulfonate at the microscopic level enhances the salt resistance.

[0058] Embodiment seven:

[0059] The oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 97 kg, and is obtained by the following method:

[0060] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 5 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, and then 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence. Stirring was continued for 1.0 h. The obtained light yellow transparent liquid was the surfactant sample for oil displacement.

[0061] The performance indexes of the surfactant samples for oil displacement obtained in Example 7 are shown in Table 7 below:

[0062] Table 7

[0063] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 75.3 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 68.2 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 63.8 Silica sand oil washing 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 3, Example 7 did not add α-terpineol, a nonionic surfactant component. The results showed that the interfacial tension increased and the oil washing performance decreased. According to multiple sets of experiments, we found that this was mainly because the interfacial tension of α-terpineol and chromatic sodium camphorsulfonate was lower than that of chromatic sodium camphorsulfonate alone.

[0065] Embodiment 8:

[0066] The oil displacement surfactant is composed of the following components: 68 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 5 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, and 1 kg of FM550 silicone resin polyether emulsion, a total of 99 kg, which is obtained by the following method:

[0067] The raw materials were weighed according to the ratio, and 68 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor and stirred into a uniform transparent liquid. After that, 5 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of FM550 silicone resin polyether emulsion was added and stirring was continued for 1.0 h. The light yellow translucent microemulsion obtained was the surfactant sample for oil displacement.

[0068] The performance indexes of the surfactant samples for oil displacement obtained in Example 8 are shown in Table 8 below:

[0069] Table 8

[0070] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 74.7 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 66.9 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 69.8 Silica sand oil washing 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, Example 8 did not add the agricultural organic silicon surfactant MY2000 component. The results showed that the interfacial tension increased slightly and the oil washing rate decreased slightly, so that the sample could not reach 10 in the low salinity system. -3 Ultra-low interfacial tension within mN / m.

[0072] Embodiment 9:

[0073] The oil displacement surfactant is composed of the following components: 67 kg of deionized water, 16 kg of cetearyl dimethyl hydroxypropyl sulfobetaine, 6 kg of sodium camphorsulfonate, 6 kg of coconut oil diethanolamide, 3 kg of α-terpineol, 1 kg of agricultural organic silicon surfactant MY2000, and 1 kg of FM550 silicone resin polyether emulsion, a total of 100 kg, which is obtained by the following method:

[0074] The raw materials were weighed according to the ratio, and 67 kg of deionized water was poured into the reactor. The stirring was started at a speed of 150 r / min, and the temperature was increased. When the temperature reached 45°C, 16 kg of hexadecyl dimethyl hydroxypropyl sulfobetaine was added to the reactor. After stirring into a uniform transparent liquid, 6 kg of sodium camphorsulfonate and 6 kg of coconut diethanolamide were added in sequence. The temperature was maintained at 45°C-50°C and stirring was continued for 1.0 h to obtain a light yellow transparent liquid. The stirring speed was reduced to 90 r / min, 3 kg of α-terpineol was added to the reactor, and stirring was continued for 0.5 h. Then, 1 kg of agricultural silicone surfactant MY2000 and 1 kg of FM550 silicone resin polyether emulsion were added in sequence, and stirring was continued for 1.0 h. The obtained light yellow translucent microemulsion was the surfactant sample for oil displacement.

[0075] The performance indexes of the surfactant samples for oil displacement obtained in Example 9 are shown in Table 9 below:

[0076] Table 9

[0077] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 73.2 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 66.5 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 64.1 Silica sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 57.9 Interfacial tension of high salinity solution (mN / m) ≤0.01 0.019324 Interfacial tension of medium salinity solution (mN / m) ≤0.01 0.006952 Interfacial tension of low salinity solution (mN / m) ≤0.001 0.001753

[0078] In Example 9, we increased the proportion of DL-sodium camphorsulfonate to 6%. As a result, we found that the interfacial tension of the sample increased slightly and the oil washing performance decreased. According to our other experiments, if the DL-sodium camphorsulfonate exceeds 5%, the oil washing performance of the sample will decrease. This may be because the amount of anionic surfactants such as DL-sodium camphorsulfonate that can be accommodated in the high-performance composite system of this application is limited.

[0079] Embodiment 10:

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

[0081] 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 to the reactor, stir to form a uniform transparent liquid, then add 8kg of coconut acid diethanolamide, maintain 45°C-50°C, and continue stirring for 0.5h to obtain a light yellow transparent liquid, which is the surfactant sample for oil displacement.

[0082] The performance indexes of the surfactant samples for oil displacement obtained in Example 10 are shown in Table 10 below:

[0083] Table 10

[0084] Test items Recommended indicator requirements Test results Calcium carbonate sand oil washing rate in 120℃ fresh water system (%) ≥70.0 68.6 120℃ fresh water system silica sand oil washing rate (%) ≥70.0 61.5 Calcium carbonate sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 62.1 Silica sand oil washing rate in high salinity system at 120℃ (%) ≥60.0 56.9 Interfacial tension of high salinity solution (mN / m) ≤0.01 0.019157 Interfacial tension of medium salinity solution (mN / m) ≤0.01 0.017235 Interfacial tension of low salinity solution (mN / m) ≤0.001 0.016625

[0085] In Example 10, only 16-octadecyl dimethyl hydroxypropyl sulfobetaine and cocoyl diethanolamide were used in the active raw materials. It can be seen that the interfacial tension of this sample is not low enough in both the low salinity system and the high salinity system, but the interfacial tension in the high salinity system varies less than that in the low salinity system, indicating that the compound of 16-octadecyl dimethyl hydroxypropyl sulfobetaine and cocoyl diethanolamide in a suitable proportion has good salt resistance. Combined with the results of Example 4, it can be seen that the anionic surfactant component of sodium camphorsulfonate 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 produced by Solen Chemical (Shanghai) Co., Ltd. SOL ND15 is a surfactant oil displacement agent product with relatively good performance in the industry.

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

[0088] Table 11

[0089]

[0090]

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

[0092] The above description of the embodiments is intended to facilitate the understanding and use of the present invention by those skilled in the art. 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 having to go through creative work. 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 scope of protection of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection 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% deionized water, 14%-19% cetearyl dimethyl hydroxypropyl sulfobetaine, 6%-8% cocoyl diethanolamide, 4%-5% sodium camphorsulfonate, 2%-3% α-terpineol, 1% MY2000, an agricultural organic silicon surfactant, and 1% FM550 silicone resin polyether emulsion. The total of the above components is 100%.

2. The method for preparing the surfactant for oil displacement that can be used in high-mineralization oil reservoirs according to claim 1, 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 cetostearyl dimethyl hydroxypropyl sulfobetaine to the reactor, stir to form a uniform transparent liquid, and then add sodium camphorsulfonate and cocoyl diethanolamide in sequence. Maintain 45°C-50°C and continue stirring for 1.0h-1.5h to obtain a light yellow transparent liquid; Step 2: Lower the stirring speed to 60r / min-90r / min, add α-terpineol to the reactor, stir for 0.5h, then add agricultural silicone surfactant MY2000 and FM550 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.

3. Use of the oil displacement surfactant according to claim 1 or the oil displacement surfactant prepared by the method according to claim 2 in oil displacement from high-salinity oil reservoirs.

4. The use according to claim 3, characterized in that The mass concentration of monovalent salts in high-mineralization oil reservoir formations shall not exceed 19% and / or the mass concentration of divalent salts shall not exceed 6%.

5. The use according to claim 3, characterized in that The reservoir formation includes sandstone and / or carbonate rock.

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