A foaming agent for fracturing and a method for preparing the same

Abstract

The application provides a foaming agent for fracturing and a preparation method thereof, and belongs to the technical field of oilfield fracturing. The foaming agent is prepared from the following raw materials in parts by weight: 10-15 parts of a fluorine-containing surfactant, 2-4 parts of a hydrophilic surfactant, 4-6 parts of a lipophilic surfactant and 30-50 parts of water. The foaming agent for fracturing has good bubble effect, fine foam, excellent salt resistance and condensate oil resistance, and the fluorocarbon surfactant has good antistatic and bactericidal effects, can effectively cooperate with the liquid nitrogen assisted drainage process, and achieves the effect of protecting the reservoir and quickly returning the drainage, is safe and environmentally friendly, and can be widely applied in the field of gas fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield fracturing technology, in particular to a foaming agent for fracturing and a preparation method thereof. BACKGROUND

[0002] Hydraulic fracturing is the most mature reservoir reconstruction technology in gas fields at present. In the development of low-permeability and ultra-low-permeability gas reservoirs, due to the low formation pressure coefficient, the problem of difficult flowback of flowback fluid occurs, which causes a large amount of pollution to the reservoir by fracturing fluid. Accordingly, many gas fields have adopted liquid nitrogen assisted flowback process. However, the liquid nitrogen assisted flowback process needs to be matched with a foaming agent to effectively improve the flowback efficiency. The foaming agent is a main additive of the fracturing fluid, and the fracturing fluid is the most important liquid system in fracturing construction. The conventional foaming agent will have a sharp decline in foaming effect or even disappear after entering the formation and encountering formation water and condensate oil. Therefore, the high-efficiency foaming agent resistant to high-salinity water and condensate oil is one of the current research focuses. SUMMARY

[0003] The present application aims to provide a foaming agent for fracturing and a preparation method thereof, which has good bubble effect, fine foam, excellent salt resistance and condensate oil resistance, and fluorocarbon surfactant has good antistatic and bactericidal effects, can effectively cooperate with the liquid nitrogen assisted flowback process, achieve the effect of protecting the reservoir and rapid flowback, is safe and environmentally friendly, and can be widely applied in the field of gas fields.

[0004] The technical solution of the present application is as follows:

[0005] The present application provides a foaming agent for fracturing, which is prepared from the following raw materials by weight: fluorine-containing surfactant 10-15 parts, hydrophilic surfactant 2-4 parts, lipophilic surfactant 4-6 parts, and water 30-50 parts.

[0006] As a further improvement of the present application, the foaming agent is prepared from the following raw materials by weight: fluorine-containing surfactant 12 parts, hydrophilic surfactant 3 parts, lipophilic surfactant 5 parts, and water 40 parts.

[0007] As a further improvement of the present application, the hydrophilic surfactant is selected from at least one of Tween-20, Tween-40, Tween-60, and Tween-80.

[0008] As a further improvement of the present application, the lipophilic surfactant is selected from at least one of Span-20, Span-40, Span-60, and Span-80.

[0009] As a further improvement of the present application, the preparation method of the fluorine-containing surfactant is as follows:

[0010] S1. reacting hexafluoropropylene oxide and p-phenylenediamine to obtain an intermediate 1;

[0011] S2. Mixing intermediate 1, formic acid, formaldehyde solution and water, heating reaction to prepare intermediate 2;

[0012] S3. Reacting intermediate 2 and methyl iodide to prepare fluorine-containing surfactant.

[0013] As a further improvement of the present application, the molar ratio of hexafluoro-propylene oxide and p-phenylenediamine in step S1 is 1:1.1-1.2, and the reaction time is 1-3h.

[0014] As a further improvement of the present application, the mass ratio of intermediate 1, formic acid, formaldehyde solution, water in step S2 is 10:4-7:15-20:30-50, the concentration of the formaldehyde solution is 35-40wt%, the heating reaction temperature is 65-75℃, and the time is 24-36h.

[0015] As a further improvement of the present application, the molar ratio of intermediate 2 and methyl iodide in step S3 is 1:3-5, the reaction temperature is 40-50℃, and the time is 36-48h.

[0016] As a further improvement of the present application, the preparation method of the fluorine-containing surfactant specifically comprises the following steps:

[0017] S1. Dissolving 1 mole equivalent of hexafluoro-propylene oxide and 1.1-1.2 mole equivalent of p-phenylenediamine in dichloromethane, reacting at room temperature for 1-3h to prepare intermediate 1;

[0018] S2. Mixing 10 parts by weight of intermediate 1, 4-7 parts by weight of formic acid, 15-20 parts by weight of 35-40wt% formaldehyde solution and 30-50 parts by weight of water, heating to 65-75℃, stirring for 24-36h to prepare intermediate 2;

[0019] S3. Dissolving 1 mole equivalent of intermediate 2 and 3-5 mole equivalent of methyl iodide in N-methyl-2-pyrrolidone, stirring at 40-50℃ for 36-48h to prepare fluorine-containing surfactant.

[0020] The present application further protects a preparation method of the above-mentioned foaming agent for fracturing, which comprises the following steps: uniformly mixing fluorine-containing surfactant, hydrophilic surfactant and lipophilic surfactant, adding water, stirring to prepare foaming agent for fracturing.

[0021] The present application has the following beneficial effects:

[0022] The foaming agent for fracturing has good bubble effect, fine foam, excellent salt resistance and condensate oil resistance, fluorocarbon surfactant has good antistatic and sterilization effects, can effectively cooperate with liquid nitrogen assisted drainage process, achieves the effect of protecting the reservoir and quickly returning the drainage, is safe and environmentally friendly, and can be widely applied in the field of gas fields. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0024] Preparation method of fluorine-containing surfactant

[0025] Specifically includes the following steps:

[0026] S1. 0.1 mol of hexafluoropropylene oxide and 0.11 mol of p-phenylenediamine were dissolved in 200 mL of dichloromethane, and the reaction was carried out at room temperature for 1 h. The solvent was removed under reduced pressure, and the intermediate 1 was prepared by recrystallization with ethanol.

[0027] S2. 10 g of the intermediate 1, 4 g of formic acid, 15 g of a 35 wt% formaldehyde solution, and 30 g of water were mixed, heated to 65 DEG C, and stirred for 24 h. The solvent was removed under reduced pressure, and the intermediate 2 was prepared by recrystallization with ethyl acetate.

[0028] S3. 0.1 mol of the intermediate 2 and 0.3 mol of iodomethane were dissolved in 200 mL of N-methyl-2-pyrrolidone, and the reaction was carried out at 40 DEG C for 36 h. The fluorine-containing surfactant was prepared by recrystallization with ethanol.

[0029] Preparation method of fluorine-containing surfactant

[0030] Specifically includes the following steps:

[0031] S1. 0.1 mol of hexafluoropropylene oxide and 0.12 mol of p-phenylenediamine were dissolved in 200 mL of dichloromethane, and the reaction was carried out at room temperature for 3 h. The solvent was removed under reduced pressure, and the intermediate 1 was prepared by recrystallization with ethanol.

[0032] S2. 10 g of the intermediate 1, 7 g of formic acid, 20 g of a 40 wt% formaldehyde solution, and 50 g of water were mixed, heated to 75 DEG C, and stirred for 36 h. The solvent was removed under reduced pressure, and the intermediate 2 was prepared by recrystallization with ethyl acetate.

[0033] S3. 0.1 mol of intermediate 2 and 0.5 mol of methyl iodide were dissolved in 200 mL of N-methyl-2-pyrrolidone, and the reaction was stirred at 50°C for 48 h. Ethanol recrystallization was performed to obtain the fluorine-containing surfactant.

[0034] Preparation method of fluorine-containing surfactant of Preparation Example 3

[0035] Specifically comprising the following steps:

[0036] S1. 0.1 mol of hexafluoropropylene oxide and 0.115 mol of p-phenylenediamine were dissolved in 200 mL of dichloromethane, and the reaction was performed at room temperature for 2 h. The solvent was removed under reduced pressure, and ethanol recrystallization was performed to obtain intermediate 1.

[0037] S2. 10 g of intermediate 1, 5.5 g of formic acid, 17 g of a 37 wt% formaldehyde solution, and 40 g of water were mixed, heated to 70°C, and stirred for 30 h. The solvent was removed under reduced pressure, and ethyl acetate recrystallization was performed to obtain intermediate 2.

[0038] S3. 0.1 mol of intermediate 2 and 0.4 mol of methyl iodide were dissolved in 200 mL of N-methyl-2-pyrrolidone, and the reaction was stirred at 45°C for 42 h. Ethanol recrystallization was performed to obtain the fluorine-containing surfactant.

[0039] Example 1

[0040] This example provides a foaming agent for fracturing.

[0041] Raw material composition (parts by weight): 10 parts of the fluorine-containing surfactant obtained in Preparation Example 1, 2 parts of Tween-60, 4 parts of Span-80, and 30 parts of water.

[0042] Preparation method:

[0043] The fluorine-containing surfactant, Tween-60, and Span-80 were uniformly mixed, and then added to water. The mixture was stirred at 300 r / min for 15 min to obtain the foaming agent for fracturing.

[0044] Example 2

[0045] This example provides a foaming agent for fracturing.

[0046] Raw material composition (parts by weight): 15 parts of the fluorine-containing surfactant obtained in Preparation Example 2, 4 parts of Tween-80, 6 parts of Span-60, and 50 parts of water.

[0047] Preparation method:

[0048] The fluorine-containing surfactant, Tween-80, and Span-60 were uniformly mixed, and then added to water. The mixture was stirred at 300 r / min for 15 min to obtain the foaming agent for fracturing.

[0049] Example 3

[0050] The present embodiment provides a foaming agent for fracturing.

[0051] Raw material composition (parts by weight): fluorine-containing surfactant prepared in Preparation Example 3 12 parts, Tween-20 3 parts, Span-20 5 parts, and water 40 parts.

[0052] Preparation method:

[0053] The fluorine-containing surfactant, Tween-20, and Span-20 were mixed uniformly, added to water, and stirred at 300 r / min for 15 min to prepare a foaming agent for fracturing.

[0054] Comparative Example 1

[0055] Compared with Example 3, the difference is that Tween-20 is not added.

[0056] Raw material composition (parts by weight): fluorine-containing surfactant prepared in Preparation Example 3 12 parts, Span-20 5 parts, and water 40 parts.

[0057] Preparation method:

[0058] The fluorine-containing surfactant and Span-20 were mixed uniformly, added to water, and stirred at 300 r / min for 15 min to prepare a foaming agent for fracturing.

[0059] Comparative Example 2

[0060] Compared with Example 3, the difference is that Span-20 is not added.

[0061] Raw material composition (parts by weight): fluorine-containing surfactant prepared in Preparation Example 3 12 parts, Tween-20 3 parts, and water 40 parts.

[0062] Preparation method:

[0063] The fluorine-containing surfactant and Tween-20 were mixed uniformly, added to water, and stirred at 300 r / min for 15 min to prepare a foaming agent for fracturing.

[0064] Comparative Example 3

[0065] Compared with Example 3, the difference is that Tween-20 and Span-20 are not added.

[0066] Raw material composition (parts by weight): fluorine-containing surfactant prepared in Preparation Example 3 12 parts and water 40 parts.

[0067] Preparation method:

[0068] The fluorine-containing surfactant was added to water, and stirred at 300 r / min for 15 min to prepare a foaming agent for fracturing.

[0069] Comparative Example 4

[0070] The difference compared with Example 3 is that no fluorine-containing surfactant is added.

[0071] Raw material composition (parts by weight): Tween-20 3 parts, Span-20 5 parts and water 40 parts.

[0072] Preparation method:

[0073] Mix Tween-20 and Span-20 uniformly, add water, stir at 300 r / min for 15 min, and prepare the foaming agent for fracturing.

[0074] Test Example 1

[0075] The foaming agent for fracturing prepared by Examples 1-3 and Comparative Examples 1-4 of the application is tested.

[0076] 1. Surface tension test

[0077] The surface tension is determined by using a full-automatic surface tension meter, the test temperature is (25±0.2)℃, the experimental method is described in detail in the national standard GB / T22237-2008, and the cmc and γ cmc are obtained.

[0078] 2. Foam test

[0079] The foam is determined by using a Ross foam meter by using a solution falling method, and the foam volume V at the initial, 30s and 5min is recorded respectively, and the experimental method is described in detail in the national standard GB / T7462-1994.

[0080] The results are shown in Table 1.

[0081] Table 1

[0082]

[0083] From the above table, it can be seen that the foaming agent for fracturing prepared by Examples 1-3 of the application has good comprehensive performance.

[0084] The above only describes the preferred embodiments of the application, and is not used to limit the application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A foaming agent for fracturing, characterized by, Prepared from the following raw materials by weight: fluorine-containing surfactant 10-15 parts, hydrophilic surfactant 2-4 parts, lipophilic surfactant 4-6 parts and water 30-50 parts; The preparation method of the fluorine-containing surfactant is as follows: S1. React hexafluoropropylene oxide and p-phenylenediamine to obtain intermediate 1; S2. Mix intermediate 1, formic acid, formaldehyde solution and water, and heat to react to obtain intermediate 2; S3. React intermediate 2 and iodomethane to obtain the fluorine-containing surfactant; The hydrophilic surfactant is selected from at least one of Tween-20, Tween-40, Tween-60, Tween-80; The lipophilic surfactant is selected from at least one of Span-20, Span-40, Span-60, Span-80.

2. The foaming agent for fracturing according to claim 1, wherein Prepared from the following raw materials by weight: fluorine-containing surfactant 12 parts, hydrophilic surfactant 3 parts, lipophilic surfactant 5 parts and water 40 parts.

3. The foaming agent for fracturing according to claim 1, wherein The molar ratio of hexafluoropropylene oxide to p-phenylenediamine in step S1 is 1:1.1-1.2, and the reaction time is 1-3h.

4. The foaming agent for fracturing according to claim 1, wherein In step S2, the mass ratio of intermediate 1, formic acid, formaldehyde solution, water is 10:4-7:15-20:30-50, the concentration of the formaldehyde solution is 35-40wt%, the heating reaction temperature is 65-75℃, and the time is 24-36h.

5. The foaming agent for fracturing according to claim 1, wherein In step S3, the molar ratio of intermediate 2 to iodomethane is 1:3-5, the reaction temperature is 40-50℃, and the time is 36-48h.

6. The foaming agent for fracturing according to claim 1, wherein The preparation method of the fluorine-containing surfactant specifically includes the following steps: S1. Dissolve 1 mole equivalent of hexafluoropropylene oxide and 1.1-1.2 mole equivalent of p-phenylenediamine in dichloromethane, react at room temperature for 1-3h to obtain intermediate 1; S2. Mix 10 parts by weight of intermediate 1, 4-7 parts by weight of formic acid, 15-20 parts by weight of 35-40wt% formaldehyde solution and 30-50 parts by weight of water, heat to 65-75℃, and stir to react for 24-36h to obtain intermediate 2; S3. Dissolve 1 mole equivalent of intermediate 2 and 3-5 mole equivalent of iodomethane in N-methyl-2-pyrrolidone, stir at 40-50℃ for 36-48h to obtain the fluorine-containing surfactant.

7. A process for the preparation of a foaming agent for fracturing according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: uniformly mix the fluorine-containing surfactant, hydrophilic surfactant and lipophilic surfactant, add water, stir, and obtain the foaming agent for fracturing.

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