Alkali-free binary surfactant, preparation and application thereof

Abstract

This invention discloses an alkali-free binary flooding surfactant, its preparation, and its application. The petroleum sulfonate surfactant disclosed in this invention is a sulfur trioxide sulfonate of a mixture of reduced-distillate oil, reduced-pentate oil, vacuum residue, and heavy alkylbenzene. The preparation process of the alkali-free binary flooding surfactant of this invention can employ batch sulfonation, requiring less equipment investment; the raw materials are reliable and inexpensive.

Description

Technical Field

[0001] This invention relates to alkali-free binary flooding surfactants, their preparation, and applications. Background Technology

[0002] Polymer flooding technology research has been basically perfected, but the average recovery rate after polymer flooding is only 50%, with half of the crude oil remaining underground. The alkali-polymer-surfactant ternary composite flooding can significantly improve the recovery rate, but large-scale industrial applications have found that the use of alkali causes a series of problems, such as formation clay dispersion and migration, decreased formation permeability, formation and wellbore scaling, shortened pump inspection cycles, and difficulty in demulsifying and dehydrating the produced fluid.

[0003] Studies have found that, under alkali-free conditions, even low concentrations of betaine surfactant can increase the interfacial tension between oil and water in different oil production plants in Daqing Oilfield to 10. -3 The ultra-low value of mN / m can meet the requirement of ultra-low oil-water interfacial tension of tertiary oil recovery surfactants. However, due to the complex production process of betaine surfactants, the raw material source needs to rely on other chemical industries, resulting in high production costs, or the high cost of betaine surfactants, their application is limited (Wang Wenquan, Liu Yi, Zhang Mengyuan, Research progress on the synthesis process of betaine surfactants, China Detergent Industry, 2020(10), 73-77); or by compounding with other auxiliaries to form new betaine compound systems, which brings new problems (Wang Yuxing, Dou Wei, Zhang Xiaolin et al., Optimization of betaine compound systems, Modern Chemical Industry, 2017, 46(3), 438-440); in addition, due to the large adsorption amount of betaine surfactants in the formation, serious adsorption loss is caused, which restricts the application of betaine surfactants in polymer-surfactant binary flooding. Summary of the Invention

[0004] The inventors made this invention in order to at least partially solve the technical drawbacks of the prior art.

[0005] As one aspect of the present invention, a petroleum sulfonate surfactant is disclosed, said surfactant being a sulfur trioxide sulfonate of a mixture of reduced-distillate oil, reduced-pentetate oil, vacuum residue, and heavy alkylbenzene. Specifically, the mixture contains 10-20% reduced-distillate oil, 30-45% reduced-pentetate oil, 30-45% vacuum residue, and 5-10% heavy alkylbenzene.

[0006] In one specific embodiment, the heavy alkylbenzene is a mixture of tetradecylbenzene and hexadecylbenzene in a weight ratio of 1-2:1-2. Preferably, the heavy alkylbenzene is a mixture of tetradecylbenzene and hexadecylbenzene in a weight ratio of 1:1.

[0007] As another aspect of the invention, a method for preparing the above-mentioned petroleum sulfonate surfactant is provided, wherein the sulfonation temperature is 40-95°C, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40 min. Furthermore, after aging the sulfonated product for 30 min, it is neutralized with a 30% sodium hydroxide solution to a pH value in the range of 8-10.

[0008] As another aspect of the present invention, a polymer-surfactant binary drive composition is provided, comprising:

[0009] The petroleum sulfonate surfactant mentioned above is 0.05wt%-0.3wt%;

[0010] Polymer 0.1wt%-0.18wt%;

[0011] The remainder is water.

[0012] In one specific embodiment, the polymer is polyacrylamide. Specifically, the polyacrylamide has an average molecular weight of 18 million.

[0013] As another aspect of the present invention, the application of the above-mentioned petroleum sulfonate surfactant in petroleum extraction is involved.

[0014] As another aspect of the present invention, there is a method for oil extraction using the aforementioned petroleum sulfonate surfactant.

[0015] This invention achieves at least the following beneficial effects:

[0016] (1) The preparation process of the alkali-free binary flooding surfactant of the present invention can adopt batch sulfonation, which requires less equipment investment;

[0017] (2) The raw materials are reliable and inexpensive, and can be mainly obtained by the oil fields themselves; moreover, the raw materials are similar in composition to Daqing crude oil and have good compatibility.

[0018] (3) The surfactant of the present invention can reduce the oil-water interfacial tension to 10 in different oil production plants of Daqing Oilfield under alkali-free conditions. -3 The ultra-low level of mN / m is of great significance for the promotion of polymer-surfactant binary flooding in Daqing Oilfield, and has broad application prospects. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific conditions are not specified in the examples, they are performed under conventional conditions or conditions recommended by the manufacturer. Reagents, instruments, or methods used in the embodiments of the present invention whose source is not specified are all conventional products that can be obtained commercially or from the applicant.

[0020] In the following examples, heavy alkylbenzenes refer to composite heavy alkylbenzenes formed by mixing tetradecylbenzene and hexadecylbenzene in a mass ratio of 50:50; wherein both tetradecylbenzene and hexadecylbenzene are commercially available.

[0021] The polymer used in this invention is polyacrylamide, which has an average molecular weight of 18 million.

[0022] Unless otherwise specified, all parts used in the embodiments of this application are parts by weight.

[0023] Example 1:

[0024] This embodiment provides a method for preparing an alkali-free binary flooding surfactant, which includes the following steps:

[0025] (1) The Daqing Oilfield reduced-distillate oil (2% saturated), reduced-distillate oil (5% saturated), vacuum residue, and heavy alkylbenzene are combined in the following weight ratios as raw materials for the preparation of surfactants. Based on the total weight of the mixed raw materials (100%), the content of each component in the mixed raw materials is: 10% reduced-distillate oil (2% saturated), 40% reduced-distillate oil (5% saturated), 45% vacuum residue, and 5% heavy alkylbenzene.

[0026] (2) The mixed raw materials are sulfonated with sulfur trioxide gas, wherein the sulfonation temperature is 40-95℃, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40 min.

[0027] (3) After aging the sulfonated product for 30 minutes, it is neutralized with 30% sodium hydroxide solution until the pH value is 8-10, thus obtaining the petroleum sulfonate surfactant. The effective content of the active ingredient is 31.8% by titration analysis.

[0028] This embodiment also provides a binary flooding composition containing the above-mentioned alkali-free binary flooding surfactant. It comprises the alkali-free binary flooding surfactant prepared above, a polymer, and water, and the weight content of each component is shown in Table 2 (the balance is water).

[0029] The interfacial tension test results of the binary flooding composition prepared in this embodiment on the oil-water interface of Daqing Oilfield No. 4 Plant are shown in Table 2. The interfacial tension was tested using a TEXAS-500C rotating drop interfacial tensiometer. The surfactant was prepared from reinjected wastewater from Daqing Oilfield No. 4 Plant at a concentration of 0.05%-0.3% (wt). The interfacial tension was the stable equilibrium value after 2 hours of testing. The test temperature was the reservoir temperature, 45℃.

[0030] Table 2. Effect of alkali-free surfactant composition on interfacial tension of crude oil / reinjection wastewater at Daqing Oilfield No. 4 Plant (where the polymer is polyacrylamide produced by Daqing Refining & Chemical, with a molecular weight of 18 million and a concentration of 0.1-0.18 wt%).

[0031] Serial Number Two-way drive formulation composition Oil-water interfacial tension (mN / m) 1 0.05% petroleum sulfonate + 0.1% polymer 0.0049 2 0.1% petroleum sulfonate + 0.12% polymer 0.0048 3 0.3% petroleum sulfonate + 0.18% polymer 0.0086

[0032] As can be seen from Table 2, when the concentration of the alkali-free binary flooding surfactant is in the range of 0.05-0.3wt%, it can make the interfacial tension of Daqing oil and water reach an ultra-low level, indicating that it can meet the interfacial tension requirements of polymer-surfactant alkali-free binary flooding.

[0033] A laboratory core flooding test was conducted on the binary flooding composition 3 (0.3% petroleum sulfonate + 0.18% polymer) prepared in this embodiment. The core size was 45mm × 45mm × 300mm. The injection method was 0.3PV (0.3% surfactant + 0.18% polymer) + 0.2PV protective slug (0.15% polymer). The test temperature was the reservoir temperature, 45℃. The results of the flooding test are shown in Table 3. As can be seen from Table 3, using the binary flooding composition 3 (0.3% surfactant + 0.18% polymer) followed by 0.2PV protective slug, the oil recovery rate increased by 18.4% for chemical flooding on the basis of water flooding, and the oil recovery rate increased by nearly 20% for polymer-surfactant binary flooding.

[0034] Table 3 Results of Indoor Core Displacement Tests

[0035]

[0036] Example 2:

[0037] This embodiment provides a method for preparing an alkali-free binary flooding surfactant, which includes the following steps:

[0038] (1) Daqing reduced-distillate oil (2% saturated), reduced-distillate oil (5% saturated), vacuum residue, and heavy alkylbenzene are combined in the following weight ratios as raw materials for the preparation of surfactants. Based on the total weight of the mixed raw materials (100%), the content of each component in the mixed raw materials is: 20% reduced-distillate oil (2% saturated), 35% reduced-distillate oil (5% saturated), 37% vacuum residue, and 8% heavy alkylbenzene;

[0039] (2) The mixed raw materials are sulfonated with sulfur trioxide gas, wherein the sulfonation temperature is 45-95℃, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40min.

[0040] (3) After aging the sulfonated product for 30 minutes, it was neutralized with 30% sodium hydroxide solution until the pH value was 8-10 to obtain the petroleum sulfonate surfactant. The effective content of the active ingredient was 32.2% by titration analysis.

[0041] This embodiment also provides a binary flooding composition containing the above-mentioned alkali-free binary flooding surfactant. It comprises the alkali-free binary flooding surfactant prepared above, a polymer, and water, and the weight content of each component is shown in Table 4 (the balance is water).

[0042] The interfacial tension test results of the binary flooding composition prepared in this embodiment on the oil-water interface of Daqing Oilfield No. 4 Plant are shown in Table 4. The interfacial tension was tested using a TEXAS-500C rotating drop interfacial tensiometer. The surfactant was prepared from reinjected wastewater from Daqing Oilfield No. 4 Plant at a concentration of 0.05%-0.3% (wt). The interfacial tension was the stable equilibrium value after 2 hours of testing. The test temperature was the reservoir temperature, 45℃.

[0043] Table 4. Effect of alkali-free surfactant composition on interfacial tension of crude oil / reinjection wastewater at Daqing Oilfield No. 4 Plant (where the polymer is polyacrylamide produced by Daqing Refining & Chemical, with a molecular weight of 18 million and a concentration of 0.1-0.18 wt%).

[0044]

[0045]

[0046] As can be seen from Table 4, when the concentration of the alkali-free binary flooding surfactant is in the range of 0.05-0.3wt%, it can make the interfacial tension of Daqing oil and water reach an ultra-low level, indicating that it can meet the interfacial tension requirements of polymer-surfactant alkali-free binary flooding.

[0047] A laboratory core flooding test was conducted on the binary flooding composition 3 (0.3% petroleum sulfonate + 0.18% polymer) prepared in this embodiment. The core size was 45mm × 45mm × 300mm. The injection method was 0.3PV (0.3% surfactant + 0.18% polymer) + 0.2PV protective slug (0.15% polymer). The test temperature was the reservoir temperature, 45℃. The results of the flooding test are shown in Table 5. As can be seen from Table 5, using the binary flooding composition 3 (0.3% surfactant + 0.18% polymer) followed by 0.2PV protective slug, the chemical flooding enhanced oil recovery reached 20.3% on the basis of water flooding. The enhanced oil recovery effect of polymer-surfactant binary flooding is close to that of conventional ternary composite flooding.

[0048] Table 5 Results of Indoor Core Displacement Tests

[0049]

[0050] Example 3:

[0051] This embodiment provides a method for preparing an alkali-free binary flooding surfactant, which includes the following steps:

[0052] (1) Daqing reduced-distillate oil (2% saturated), reduced-distillate oil (5% saturated), vacuum residue, and heavy alkylbenzene are combined in the following weight ratios as raw materials for the preparation of surfactants. Based on 100% of the total weight of the mixed raw materials, the content of each component in the mixed raw materials is: 15% reduced-distillate oil (2% saturated), 45% reduced-distillate oil (5% saturated), 30% vacuum residue, and 10% heavy alkylbenzene;

[0053] (2) The mixed raw materials are sulfonated with sulfur trioxide gas, wherein the sulfonation temperature is 40-95℃, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40 min.

[0054] (3) After aging the sulfonated product for 30 minutes, it was neutralized with 30% sodium hydroxide solution until the pH value was 8-10 to obtain the petroleum sulfonate surfactant. The effective content of the active ingredient was 33.6% by titration analysis.

[0055] This embodiment also provides a binary flooding composition containing the above-mentioned alkali-free binary flooding surfactant. It comprises the alkali-free binary flooding surfactant prepared above, a polymer, and water; the weight content of each component is shown in Table 6.

[0056] The interfacial tension test results of the binary flooding composition prepared in this embodiment on the oil-water interface of Daqing Oilfield No. 4 Plant are shown in Table 6. The interfacial tension was tested using a TEXAS-500C rotating drop interfacial tensiometer. The surfactant was prepared from reinjected wastewater from Daqing Oilfield No. 4 Plant at a concentration of 0.05%-0.3% (wt). The interfacial tension was the stable equilibrium value after 2 hours of testing. The test temperature was the reservoir temperature, 45℃.

[0057] Table 6. Effect of alkali-free surfactant composition on interfacial tension of crude oil / reinjection wastewater at Daqing Oilfield No. 4 Plant (where the polymer is polyacrylamide produced by Daqing Refining & Chemical, with a molecular weight of 18 million and a concentration of 0.1-0.18 wt%).

[0058] Serial Number Two-way drive formulation composition Oil-water interfacial tension (mN / m) 1 0.05% petroleum sulfonate + 0.1% polymer 0.0031 2 0.1% petroleum sulfonate + 0.12% polymer 0.0015 3 0.3% petroleum sulfonate + 0.18% polymer 0.0060

[0059] As can be seen from Table 6, when the concentration of the alkali-free binary flooding surfactant is in the range of 0.05-0.3wt%, it can make the interfacial tension of Daqing oil and water reach an ultra-low level, indicating that it can meet the interfacial tension requirements of polymer-surfactant alkali-free binary flooding.

[0060] A laboratory core flooding test was conducted on the binary flooding composition 3 (0.3% petroleum sulfonate + 0.18% polymer) prepared in this embodiment. The core size was 45mm × 45mm × 300mm. The injection method was 0.3PV (0.3% surfactant + 0.18% polymer) + 0.2PV protective slug (0.15% polymer). The test temperature was the reservoir temperature, 45℃. The results of the flooding test are shown in Table 7. As can be seen from Table 7, using the binary flooding composition 3 (0.3% surfactant + 0.18% polymer) followed by a 0.2PV protective slug, the chemical flooding enhanced oil recovery reached 22.7% on the basis of water flooding. The enhanced oil recovery effect of polymer-surfactant binary flooding is comparable to that of conventional ternary composite flooding.

[0061] Table 7 Results of Indoor Core Displacement Tests

[0062]

[0063] Example 4:

[0064] This embodiment provides a method for preparing an alkali-free binary flooding surfactant, which includes the following steps:

[0065] (1) Daqing reduced-distillate oil (2% saturated), reduced-distillate oil (5% saturated), vacuum residue, and heavy alkylbenzene are combined in the following weight ratios as raw materials for the preparation of surfactants. Based on the total weight of the mixed raw materials (100%), the content of each component in the mixed raw materials is: 18% reduced-distillate oil (2% saturated), 30% reduced-distillate oil (5% saturated), 43% vacuum residue, and 9% heavy alkylbenzene;

[0066] (2) The mixed raw materials are sulfonated with sulfur trioxide gas, wherein the sulfonation temperature is 40-95℃, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40 min.

[0067] (3) After aging the sulfonated product for 30 minutes, it was neutralized with 30% sodium hydroxide solution until the pH value was 8-10 to obtain the petroleum sulfonate surfactant. The effective content of the active ingredient was 32.9% by titration analysis.

[0068] This embodiment also provides a binary flooding composition containing the above-mentioned alkali-free binary flooding surfactant. It comprises the alkali-free binary flooding surfactant prepared above, a polymer, and water; the weight content of each component is shown in Table 8.

[0069] The interfacial tension test results of the binary flooding composition prepared in this embodiment on the oil-water interface of Daqing Oilfield No. 4 Plant are shown in Table 8. The interfacial tension was tested using a TEXAS-500C rotating drop interfacial tensiometer. The surfactant was prepared from reinjected wastewater from Daqing Oilfield No. 4 Plant at a concentration of 0.05%-0.3% (wt). The interfacial tension was the stable equilibrium value after 2 hours of testing. The test temperature was the reservoir temperature, 45℃.

[0070] Table 8. Effect of alkali-free surfactant composition on interfacial tension of crude oil / reinjection wastewater at Daqing Oilfield No. 4 Plant (where the polymer is polyacrylamide produced by Daqing Refining & Chemical, with a molecular weight of 18 million and a concentration of 0.1-0.18 wt%).

[0071] Serial Number Two-way drive formulation composition Oil-water interfacial tension (mN / m) 1 0.05% petroleum sulfonate + 0.1% polymer 0.0028 2 0.1% petroleum sulfonate + 0.12% polymer 0.0017 3 0.3% petroleum sulfonate + 0.18% polymer 0.0053

[0072] As can be seen from Table 8, when the concentration of the alkali-free binary flooding surfactant is in the range of 0.05-0.3wt%, it can make the interfacial tension of Daqing oil and water reach an ultra-low level, indicating that it can meet the interfacial tension requirements of polymer-surfactant alkali-free binary flooding.

[0073] A laboratory core flooding test was conducted on the binary flooding composition 3 (0.3% petroleum sulfonate + 0.18% polymer) prepared in this embodiment. The core size was 45mm × 45mm × 300mm. The injection method was 0.3PV (0.3% surfactant + 0.18% polymer) + 0.2PV protective slug (0.15% polymer). The test temperature was the reservoir temperature, 45℃. The results of the flooding test are shown in Table 9. As can be seen from Table 9, using the binary flooding composition 3 (0.3% surfactant + 0.18% polymer) followed by 0.2PV protective slug, the chemical flooding enhanced oil recovery reached 21.3% on the basis of water flooding. The enhanced oil recovery effect of polymer-surfactant binary flooding is comparable to that of conventional ternary composite flooding.

[0074] Table 9 Results of Indoor Core Displacement Tests

[0075]

[0076] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A petroleum sulfonate surfactant, characterized in that, The surfactant is a sulfur trioxide sulfonate of a mixture of reduced-distillate oil, reduced-distillate oil, vacuum residue, and heavy alkylbenzene; The mixture contains 10-20% reduced distillate oil, 30-45% reduced pent distillate oil, 30-45% vacuum residue, and 5-10% heavy alkylbenzene; The heavy alkylbenzene is composed of tetradecylbenzene and hexadecylbenzene in a weight ratio of 1-2:1-2.

2. The petroleum sulfonate surfactant according to claim 1, characterized in that, The heavy alkylbenzene is composed of tetradecylbenzene and hexadecylbenzene in a weight ratio of 1:

1.

3. A method for preparing the petroleum sulfonate surfactant according to any one of claims 1-2, characterized in that, The sulfonation temperature is 40-95℃, the sulfur trioxide gas concentration is 7-10%, and the reaction time is 40 min.

4. A method for preparing the petroleum sulfonate surfactant according to any one of claims 1-2, characterized in that, After aging the sulfonated product for 30 minutes, it was neutralized with a 30% sodium hydroxide solution until the pH value was in the range of 8-10.

5. A polymer-surfactant binary flooding composition, characterized in that, Include: The petroleum sulfonate surfactant according to any one of claims 1-2 is present in the amount of 0.05 wt% to 0.3 wt%. Polymer 0.1wt%-0.18wt%; The remainder is water.

6. The composition according to claim 5, characterized in that, The polymer is polyacrylamide.

7. The composition according to claim 6, characterized in that, The polyacrylamide has an average molecular weight of 18 million.

8. The application of the petroleum sulfonate surfactant according to any one of claims 1-2 in petroleum extraction.

9. A method for oil extraction, characterized in that, Use the petroleum sulfonate surfactant according to any one of claims 1-2.

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