Preparation method and application of synergistic oil washing agent for oil displacement

Abstract

The application belongs to the technical field of oil exploitation, and particularly relates to a preparation method and application of an oil-washing agent for oil displacement. The oil-washing agent for oil displacement is composed of the following raw materials in percentage by weight: 0.2-0.5% of fluorine surfactant, 0.1-0.2% of OP-10, and the balance of water. The structure formula of the fluorine surfactant is as follows: wherein n is a natural number of 2-8. The oil-washing agent has the advantages of no organic solvent and high oil-washing efficiency, and the oil-washing rate is up to 99.3%.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a method for preparing and applying an enhanced oil washing agent for oil displacement. Background Technology

[0002] Currently, most oilfields in my country have entered the mid-to-late stages of development. After primary and secondary oil recovery, only about 30% of the geological reserves can be extracted, with a large amount of crude oil remaining adsorbed in the tiny pores of the reservoir rocks, making it difficult to effectively extract. Improving crude oil recovery rate has become a core requirement for current oilfield development. Chemical flooding, as the mainstream technology for tertiary oil recovery, relies on using oil-washing agents to reduce the interfacial tension between oil and water and remove the oil film from the rock surface, thereby achieving efficient extraction of residual oil. The performance of the oil-washing agent directly determines the application effect of chemical flooding technology.

[0003] Existing oil reservoir cleaning agents have many drawbacks: acidic cleaning agents can only remove inorganic scale, are ineffective against oil scale, and are highly corrosive, easily damaging equipment; organic solvent-based cleaning agents can dissolve oil scale, but they are flammable, explosive, highly toxic, difficult to degrade, costly, and unsuitable for large-scale applications; conventional surfactant-based cleaning agents have poor penetration, low oil washing efficiency, weak temperature and salt resistance, are easily depleted in complex oil reservoirs, and cannot provide long-term cleaning.

[0004] An ideal oil washing agent should be able to effectively reduce the interfacial tension between oil and water, change the wettability of the rock surface, peel off and emulsify the adsorbed crude oil, thereby forming an easily flowing oil-in-water emulsion and improving the oil washing efficiency.

[0005] CN102827594B relates to a heavy oil stain cleaning agent, the composition and weight parts of which are: 60-80 parts of No. 200 solvent oil; 1-10 parts of 2-methyl-2,4-pentanediol; and 20-30 parts of alcohol ether surfactant. This invention achieves an oil removal rate of over 98% at 30℃, demonstrating excellent cleaning effect; moreover, a 5-10% aqueous solution is sufficient to achieve excellent cleaning results. However, the invention uses solvent oil, posing a safety hazard.

[0006] CN107723145B discloses a cleaning agent, its preparation method, and its application method for high-wax crude oil volumetric tubes. The technical solution comprises the following components in volume fractions: 10-20 parts solvent, 4-10 parts co-solvent, 2-8 parts surfactant, 2-8 parts emulsifier, and 50-90 parts water. This cleaning agent can effectively remove wax buildup in volumetric tubes and is characterized by safety and good stability. However, the cleaning rate of this invention is only about 80%, which is insufficient to meet actual production needs. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a method for preparing and applying an enhanced oil-displacing agent for oil displacement. The oil-displacing agent of this invention has the advantages of being solvent-free and having high oil-displacing efficiency, with a maximum oil-displacing rate of 99.3%.

[0008] The first objective of this invention discloses an oil displacement synergistic washing agent, which, by weight percentage, is composed of the following raw materials: Fluorinated surfactants 0.2-0.5%; OP-10 0.1-0.2%; Water balance; The fluorosurfactant has the following structural formula: , Where n is a natural number between 2 and 8.

[0009] The second objective of this invention is to provide a method for preparing the above-mentioned enhanced oil displacement washing agent, wherein the preparation method specifically includes the following steps: S1. Melamine and methanol / water mixed solvent (V:V=1:1) are added to the first reactor and stirred evenly. Then, 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecylfluoro-8-iodooctane is added and the reaction is kept at the temperature. S2. Cool the mixture to below 10°C, add diacyl chloride dropwise, and maintain the temperature for the reaction. S3. Add sodium 2-chloroethylsulfonate and maintain the temperature for reaction; S4. Add sodium 3-chloro-2-hydroxypropyl phosphate and maintain the temperature for reaction; S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the fluorinated surfactant.

[0010] S6. Water, fluorinated surfactant, and OP-10 are added sequentially to the second reactor and stirred until homogeneous to obtain an enhanced oil displacement washing agent.

[0011] In this invention, the molar ratio of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecylfluoro-8-iodooctane, diacyl chloride, sodium 2-chloroethylsulfonate, sodium 3-chloro-2-hydroxypropyl phosphate, and melamine is further described as 0.8-1.2:0.4-0.6:0.4-0.6:0.4-0.6:1.

[0012] Furthermore, the diacyl chloride is one of succinyl chloride, glutaryl chloride, adipyl chloride, peptiol chloride, octyl chloride, azeloyl chloride, and sebacyl chloride. Its structural formula is as follows:

[0013] Where n is a natural number between 2 and 8.

[0014] Furthermore, the structural formula of the sodium 3-chloro-2-hydroxypropyl phosphate is as follows:

[0015] The preparation method is described in "Surfactant Synthesis Technology", by Lü Tong, Chemical Industry Press, page 202.

[0016] Furthermore, the mass ratio of methanol / water mixed solvent to melamine in step S1 is 20-30:1.

[0017] Furthermore, the heat preservation reaction mentioned in step S1 refers to a temperature of 25-35℃, a time of 1-2 hours, and a pH of 7-8.

[0018] Furthermore, the heat preservation reaction mentioned in step S2 refers to a temperature of 5-10℃, a time of 1-2 hours, and a pH of 7-8.

[0019] Furthermore, the heat preservation reaction mentioned in step S3 refers to a temperature of 40-60℃, a time of 1-2 hours, and a pH of 7-8.

[0020] Furthermore, the heat preservation reaction mentioned in step S4 refers to a temperature of 60-70℃, a time of 2-4 hours, and a pH of 7-8.

[0021] A third objective of this invention is to provide the application of the above-mentioned enhanced oil recovery agent for oil displacement in tertiary oil recovery in oil fields.

[0022] The oil displacement synergistic cleaning agent of this invention belongs to the category of composite cleaning agents. Among them, the fluorosurfactant is a special surfactant that can adsorb onto the rock surface, effectively improving rock wettability, reversing the oleophilic surface to a hydrophilic one, and causing the oil film adhering to the pore walls to automatically peel off, becoming movable oil droplets. It has extremely low surface tension, which allows residual oil droplets originally bound in the rock pores by capillary forces to easily deform, overcoming resistance under external force and passing through narrow pore throats. OP-10 can effectively reduce the oil-water interfacial tension, promote crude oil emulsification to form an oil-in-water emulsion, reduce crude oil viscosity, improve the oil-water mobility ratio, and peel it off from the rock surface. It has wetting, dispersing, and solubilizing effects, enabling waxes and other substances to dissolve better in the cleaning agent. The long-chain polyether can firmly encapsulate the peeled oil droplets, forming a stable emulsion and preventing the back-adhesion of high-viscosity crude oil.

[0023] The beneficial effects and advantages of this invention compared with the prior art are as follows: (1) The cleaning agent of the present invention does not contain organic solvents and has good safety; (2) The washing agent of the present invention has a high washing rate, which can reach up to 99.3%. Attached Figure Description

[0024] Appendix Figure 1 The infrared spectrum of the fluorinated surfactant F5 in the cleaning agent of this invention is shown. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to specific embodiments: Example 1 Preparation of fluorosurfactant F1 S1. Add 0.1 mol of melamine and 252 g of methanol / water mixed solvent (V:V=1:1) to the reactor, stir evenly, add 0.08 mol of 1,1,1,2,2,3,3,4,4,5,5,6,6-tetrafluoro-8-iodooctane, keep the reaction at 25℃ for 2 h, and maintain pH 7-8 during the reaction. S2. Cool the mixture to 5℃, add 0.04mol succinyl chloride dropwise, keep the mixture at 5℃ for 2h, and maintain the pH at 7-8 during the reaction. S3. Add 0.06 mol of sodium 2-chloroethylsulfonate and keep the temperature at 40°C for 2 hours. Maintain the pH at 7-8 during the reaction. S4. Add 0.045 mol of sodium 3-chloro-2-hydroxypropyl phosphate, and keep the reaction at 60°C for 4 hours, maintaining the pH at 7-8 during the reaction. S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain fluorinated surfactant F1.

[0026] Example 2 Preparation of fluorosurfactant F2 S1. Add 0.1 mol of melamine and 378 g of methanol / water mixed solvent (V:V=1:1) to the reactor, stir well, add 0.12 mol of 1,1,1,2,2,3,3,4,4,5,5,6,6-tetrafluoro-8-iodooctane, and keep the reaction at 35℃ for 1.2 h, maintaining pH 7-8 during the reaction. S2. Cool the mixture to 5℃, add 0.06 mol sebacate, and keep it at 8℃ for 2 hours. Maintain the pH at 7-8 during the reaction. S3. Add 0.045 mol of sodium 2-chloroethylsulfonate, keep the temperature at 60℃ for 1 hour, and maintain the pH at 7-8 during the reaction. S4. Add 0.04 mol of sodium 3-chloro-2-hydroxypropyl phosphate, and keep the reaction at 65°C for 4 hours, maintaining the pH at 7-8 during the reaction. S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the fluorinated surfactant F2.

[0027] Example 3 Preparation of Fluorosurfactant F3 S1. Add 0.1 mol of melamine and 313 g of methanol / water mixed solvent (V:V=1:1) to the reactor, stir evenly, add 0.09 mol of 1,1,1,2,2,3,3,4,4,5,5,6,6-tetrafluoro-8-iodooctane, keep the reaction at 33℃ for 1 h, and maintain pH 7-8 during the reaction. S2. Cool the mixture to 8°C, add 0.045 mol adipic acid chloride dropwise, and keep the mixture at 10°C for 1 hour, maintaining the pH at 7-8 during the reaction. S3. Add 0.04 mol of sodium 2-chloroethylsulfonate and keep the reaction at 45°C for 2 hours, maintaining the pH at 7-8 during the reaction. S4. Add 0.06 mol of sodium 3-chloro-2-hydroxypropyl phosphate, and keep the reaction at 68°C for 3 hours, maintaining the pH at 7-8 during the reaction. S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain fluorinated surfactant F3.

[0028] Example 4 Preparation of fluorosurfactant F4 S1. Add 0.1 mol of melamine and 352 g of methanol / water mixed solvent (V:V=1:1) to the reactor, stir well, add 0.11 mol of 1,1,1,2,2,3,3,4,4,5,5,6,6-tetrafluoro-8-iodooctane, keep the reaction at 30℃ for 1.5 h, and maintain pH 7-8 during the reaction. S2. Cool the mixture to 8°C, add 0.055 mol octanyl chloride dropwise, and keep the reaction at 6°C for 1.5 h, maintaining the pH at 7-8 during the reaction. S3. Add 0.05 mol of sodium 2-chloroethylsulfonate and keep the reaction at 50°C for 1.5 h, maintaining the pH at 7-8 during the reaction. S4. Add 0.05 mol of sodium 3-chloro-2-hydroxypropyl phosphate, and keep the reaction at 70°C for 2 hours, maintaining the pH at 7-8 during the reaction. S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain fluorinated surfactant F4.

[0029] Example 5 Preparation of fluorosurfactant F5 S1. Add 0.1 mol of melamine and 360 g of methanol / water mixed solvent (V:V=1:1) to the reactor, stir evenly, add 0.1 mol of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecylfluoro-8-iodooctane, keep the reaction at 30℃ for 1.5 h, and maintain pH 7-8 during the reaction. S2. Cool the mixture to 6℃, add 0.05 mol pimecroyl chloride dropwise, keep the mixture at 6℃ for 2 hours, and maintain the pH at 7-8 during the reaction. S3. Add 0.055 mol of sodium 2-chloroethylsulfonate, keep the temperature at 50°C for 2 hours, and maintain the pH at 7-8 during the reaction. S4. Add 0.055 mol of sodium 3-chloro-2-hydroxypropyl phosphate, and keep the reaction at 65°C for 3 hours, maintaining the pH at 7-8 during the reaction. S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the fluorinated surfactant F5.

[0030] Example 6 Preparation of an enhanced oil displacement washing agent 997g of water, 2g of F1, and 1g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an oil displacement synergist.

[0031] Example 7 Preparation of an enhanced oil displacement washing agent 996g of water, 2g of F1, and 2g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an enhanced oil displacement washing agent.

[0032] Example 8 Preparation of an enhanced oil displacement washing agent 996g of water, 3g of F2, and 1g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an enhanced oil displacement washing agent.

[0033] Example 9 Preparation of an enhanced oil displacement washing agent 995g of water, 3.5g of F3, and 1.5g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an oil displacement synergist.

[0034] Example 10 Preparation of an enhanced oil displacement washing agent 995g of water, 4g of F3, and 1g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an oil displacement synergist.

[0035] Example 11 Preparation of an enhanced oil displacement washing agent 994g of water, 4.5g of F4, and 1.5g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an enhanced oil displacement washing agent.

[0036] Example 12 Preparation of an enhanced oil displacement washing agent 993g of water, 5g of F5, and 2g of OP-10 were added to the reactor in sequence and stirred until homogeneous to obtain an oil displacement synergist.

[0037] Comparative Example 1 The preparation method is the same as in Example 6, except that the amount of water added is 999g, the amount of OP-10 added is 1g, and F1 is not added.

[0038] Comparative Example 2 The preparation method is the same as in Example 6, except that the amount of water added is 998g, the amount of F1 added is 2g, and OP-10 is not added.

[0039] Comparative Example 3 A 1 wt% aqueous solution of sodium dodecylbenzenesulfonate.

[0040] Test Example 1: Oil Washing Efficiency Test The test method refers to Q / SHCG 11-2017 "Technical Requirements for Oil Layer Cleaning Agents", and the specific steps are as follows: (1) Prepare artificial sludge oil Mix 83g crude oil, 12g petroleum asphalt, and 5g paraffin wax in the specified proportions, and heat until homogeneous.

[0041] (2) Preparation of oil sands Weigh 4.0g of artificial oil stain into a 250mL beaker, add 10mL of 120# solvent oil to dissolve the artificial oil stain, stir with a glass rod, add 170g of quartz sand to the solution, stir evenly to fully mix the sand and oil stain, heat and stir in a water bath at (80~90)℃ for more than 0.5h, evaporate the solvent oil to obtain oil sand, the mass fraction of oil in this oil sand is K=2.3%.

[0042] (3) Determination of wash oil ratio 1) Weigh 6.0g of oil sand into a 50mL beaker, add 20mL of the present invention, place the beaker in a 60℃ constant temperature water bath, remove the beaker every 15min and gently rotate it for 10s, then place it back in the water bath, and leave it for a total of 1h. After that, remove the beaker, gently shake it, and use tweezers to hold cotton and dab away the oil stains on the liquid surface and the beaker wall. Be careful not to let the cotton touch the oil sand, and carefully pour out the washing solution.

[0043] 2) Rinse the beaker with distilled water to remove any remaining cleaning solution until the rinse solution is clear.

[0044] 3) Place the rinsed beaker containing oil sand into an oven at (105±2)℃ and dry for 4 hours. Remove it and place it in a desiccator to cool to room temperature.

[0045] 4) Take a small amount of 120# solvent oil and rinse the dried oil sand several times. Collect the rinsed 120# solvent oil in a 50mL colorimetric tube.

[0046] 5) Then pour the oil sand into a funnel containing filter paper, and rinse with 120# solvent oil until the color of the filtered solvent oil matches that of the 120# solvent oil. Collect the rinsed solvent oil into the aforementioned 50mL colorimetric tube and dilute to the mark. If the volume exceeds 50mL, dilute to 100mL.

[0047] 6) Determine the oil content of the above solution according to the provisions of 5.4 in SY / T 5329—2022.

[0048] The wash-oil ratio is calculated using the following formula: X= × 100% In the formula: X—Wash rate, % K—Oil content in oil sands, % (by mass). W0—The mass of the oil sand, in grams; W1—Residual oil content in the oil sand inside the colorimetric tube, in g.

[0049] Comparative examples 1, 2, and 3 were tested using the same method, and the results are shown in Table 1.

[0050] Table 1 Results of the wash-oil ratio test

[0051] As can be seen from Table 1: As can be seen from Example 6 and Comparative Example 1, OP-10 plays an auxiliary role in the oil washing process, but its own effect is limited. As can be seen from Example 6 and Comparative Example 2, the fluorosurfactant plays a major role in the oil washing process; even without the addition of OP-10, a 96.3% oil washing rate can still be achieved. As can be seen from Examples 6-12 and Comparative Example 3, the oil washing effect of the present invention is far superior to that of commonly used commercial oil washing agents such as sodium dodecylbenzene sulfonate. As can be seen from Examples 6-12, as the dosage of fluorosurfactant increases, the oil washing rate increases, but the rate of increase is smaller. In actual use, the dosage can be adjusted according to the actual situation to increase cost-effectiveness.

[0052] Test Example 2 The fluorosurfactant F5 in this invention was characterized by infrared spectroscopy, and the results are as follows: Figure 1 As shown.

[0053] Figure 1 Middle, 3446 cm - for Bond stretching vibration peak, 1335 cm⁻¹ - for Bond stretching vibration peak, 1222 cm⁻¹ - for Bond stretching vibration peak, 1120 cm⁻¹ - for Bond stretching vibration peak.

Claims

1. A synergistic oil displacement and washing agent, characterized in that, The aforementioned oil displacement and oil-enhancing washing agent, by weight percentage, is composed of the following raw materials: Fluorinated surfactants 0.2-0.5%; OP-10 0.1-0.2%; Water balance; The structural formula of the fluorosurfactant is as follows: ， Where n is a natural number between 2 and 8.

2. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The preparation method specifically includes the following steps: S1. Melamine and methanol / water mixed solvent (V:V=1:1) are added to the first reactor and stirred evenly. Then, 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecylfluoro-8-iodooctane is added and the reaction is kept at the temperature. S2. Cool the mixture to below 10°C, add diacyl chloride dropwise, and maintain the temperature for the reaction. S3. Add sodium 2-chloroethylsulfonate and maintain the temperature for reaction; S4. Add sodium 3-chloro-2-hydroxypropyl phosphate and maintain the temperature for reaction; S5. Remove some of the solvent by vacuum distillation, cool to crystallize, filter, and dry to obtain the fluorinated surfactant; S6. Water, fluorinated surfactant, and OP-10 are added sequentially to the second reactor and stirred until homogeneous to obtain an oil displacement synergistic washing agent. The molar ratio of 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecylfluoro-8-iodooctane, diacyl chloride, sodium 2-chloroethylsulfonate, sodium 3-chloro-2-hydroxypropyl phosphate, and melamine is 0.8-1.2:0.4-0.6:0.4-0.6:0.4-0.6:

1.

3. The preparation method of the oil displacement synergist as described in claim 2, characterized in that, The diacyl chloride is one of succinyl chloride, glutaryl chloride, adipyl chloride, heptayl chloride, octyl chloride, azelaic chloride, and sebacyl chloride.

4. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The mass ratio of methanol / water mixed solvent to melamine in step S1 is 20-30:

1.

5. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The heat preservation reaction mentioned in step S1 refers to a temperature of 25-35℃, a time of 1-2 hours, and a pH of 7-8.

6. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The heat preservation reaction mentioned in step S2 refers to a temperature of 5-10℃, a time of 1-2 hours, and a pH of 7-8.

7. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The heat preservation reaction mentioned in step S3 refers to a temperature of 40-60℃, a time of 1-2 hours, and a pH of 7-8.

8. The preparation method of the oil displacement synergist as described in claim 1, characterized in that, The heat preservation reaction mentioned in step S4 refers to a temperature of 60-70℃, a time of 2-4 hours, and a pH of 7-8.

9. The application of the enhanced oil recovery agent for oil displacement as described in claim 1 in tertiary oil recovery in oil fields.

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