A kind of demulsifier for fracturing and preparation method thereof

Abstract

The invention provides an anti-emulsifier for fracturing and a preparation method thereof, and belongs to the technical field of petroleum extraction. The invention firstly mixes a composite initiator and potassium hydroxide and then heats them, then adds ethylene oxide to react, and obtains a reaction intermediate; the reaction intermediate is reacted with propylene oxide and potassium hydroxide to obtain a mixed alcohol polyether; finally, the mixed alcohol polyether, a cationic modifier and a solvent are mixed and reacted to obtain an anti-emulsifier for fracturing, wherein the composite initiator comprises decyltetradecanol and diethylene glycol. The invention adopts decyltetradecanol and diethylene glycol as initiators to obtain a mixed alcohol polyether, and then the mixed alcohol polyether is subjected to cationic modification, and the dehydration rate of the obtained anti-emulsifier can reach 99.3%, which is very suitable for use as an anti-emulsifier in oilfield acidification operations.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum extraction, and in particular to an anti-emulsifier for fracturing and a preparation method thereof. Background Art

[0002] Fracturing is a commonly used oilfield mining technology that increases oil well production. During the fracturing process, water and chemical additives are injected into the wellhead to form high pressure in the well, causing the cracks in the rock to increase, thereby increasing the fluidity of oil or natural gas. During the fracturing process, the water and a large amount of surfactants in the fracturing fluid emulsify with the oil in the underground oil layer, causing the oil and water to mix together, reducing the production of the oil well. It can be seen that preventing emulsification plays an important role in the fracturing process.

[0003] The function of the demulsifier is to reduce the surface tension, prevent the emulsification of water and surfactant with oil, avoid emulsion plugging, and ensure the fluidity and yield of oil. The demulsifiers currently used are of uneven quality, large dosage, poor demulsification effect, and low dehydration rate. Therefore, it is of great significance to study a demulsifier for fracturing and its preparation method. Summary of the invention

[0004] The object of the present invention is to provide an anti-emulsifier for fracturing and a preparation method thereof, so as to solve the problems of poor anti-emulsification effect and low dehydration rate of the anti-emulsifier in the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing an anti-emulsifier for fracturing, comprising the following steps:

[0007] (1) mixing a composite initiator and potassium hydroxide and heating them, and then adding ethylene oxide to react to obtain a reaction intermediate;

[0008] (2) reacting the reaction intermediate with propylene oxide and potassium hydroxide to obtain a mixed alcohol polyether;

[0009] (3) mixing the mixed alcohol polyether, the cationic modifier and the solvent and reacting them to obtain an anti-emulsifier for fracturing;

[0010] The composite initiator comprises decyltetradecanol and diethylene glycol.

[0011] Preferably, in the step (1), the mass ratio of the composite initiator, potassium hydroxide and ethylene oxide is 1-3:0.4-1:50-100; and the mass ratio of decyltetradecyl alcohol and diethylene glycol is 1:1-5.

[0012] Preferably, in the step (1), the heating temperature is 100-110° C.; the reaction temperature is 120-140° C., and the reaction time is 15-45 min.

[0013] Preferably, the mass ratio of the ethylene oxide in step (1), the propylene oxide in step (2), and the potassium hydroxide in step (2) is 50-100:300-500:1-3.

[0014] Preferably, in step (2), the reaction temperature is 115-125° C., and the reaction time is 15-45 min.

[0015] Preferably, in step (3), the cationic modifier comprises dimethyldiallyl ammonium chloride solution and / or glycidyltrimethylammonium chloride solution; and the solvent is one or more of methanol, ethanol, propanol and isopropanol.

[0016] Preferably, when the cationic modifier comprises dimethyldiallyl ammonium chloride solution and glycidyltrimethylammonium chloride solution, the mass ratio of the dimethyldiallyl ammonium chloride solution to the glycidyltrimethylammonium chloride solution is 1:2-4; the mass concentration of the dimethyldiallyl ammonium chloride solution is 30-40%; the mass concentration of the glycidyltrimethylammonium chloride solution is 30-40%.

[0017] Preferably, in the step (3), the mass ratio of the mixed alcohol polyether, the cationic modifier and the solvent is 70-100:3-8:100-200; the reaction temperature is 60-80°C, and the reaction time is 2-3h.

[0018] The present invention also provides an anti-emulsifier for fracturing prepared by the preparation method of the anti-emulsifier for fracturing described above.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention uses decyltetradecyl alcohol and diethylene glycol as initiators to prepare mixed alcohol polyether, and then performs cationic modification on the mixed alcohol polyether. The dehydration rate of the prepared demulsifier can reach 99.3%, and a clear interface can be ensured, which is very suitable for use as an demulsifier in oil field acidification operations.

[0021] (2) The present invention uses a cationic modifier to modify the mixed alcohol polyether and introduces cations on the main chain, which can significantly improve the demulsification performance of the demulsifier.

[0022] (3) The demulsifier prepared by the present invention does not need to be compounded with other types of demulsifiers and can be used directly. DETAILED DESCRIPTION

[0023] The present invention provides a method for preparing an anti-emulsifier for fracturing, comprising the following steps:

[0024] (1) mixing a composite initiator and potassium hydroxide and heating them, and then adding ethylene oxide to react to obtain a reaction intermediate;

[0025] (2) reacting the reaction intermediate with propylene oxide and potassium hydroxide to obtain a mixed alcohol polyether;

[0026] (3) mixing the mixed alcohol polyether, the cationic modifier and the solvent and reacting them to obtain an anti-emulsifier for fracturing;

[0027] The composite initiator comprises decyltetradecanol and diethylene glycol.

[0028] In the present invention, in the step (1), the mass ratio of the composite initiator, potassium hydroxide and ethylene oxide is 1-3:0.4-1:50-100, preferably 1.5-2.5:0.5-0.9:60-90, and more preferably 2:0.6-0.8:70-80; the mass ratio of decyltetradecyl alcohol and diethylene glycol is 1:1-5, preferably 1:2-4, and more preferably 1:3.

[0029] In the present invention, in the step (1), the heating temperature is 100-110°C, preferably 102-108°C, and more preferably 105°C; the reaction temperature is 120-140°C, preferably 125-135°C, and more preferably 130°C; the reaction time is 15-45 min, preferably 20-40 min, and more preferably 25-35 min.

[0030] In the present invention, the mass ratio of the ethylene oxide in step (1), the propylene oxide in step (2), and the potassium hydroxide in step (2) is 50-100:300-500:1-3, preferably 60-90:350-450:1.5-2.5, and more preferably 70-80:380-420:2.

[0031] In the present invention, in the step (2), the reaction temperature is 115 to 125° C., preferably 120° C.; the reaction time is 15 to 45 min, preferably 20 to 40 min, and more preferably 25 to 35 min.

[0032] In the present invention, in the step (3), the cationic modifier comprises dimethyldiallyl ammonium chloride solution and / or glycidyltrimethylammonium chloride solution; the solvent is one or more of methanol, ethanol, propanol and isopropanol, preferably one or more of methanol, ethanol and propanol, and more preferably ethanol and / or propanol.

[0033] In the present invention, when the cationic modifier comprises a dimethyldiallyl ammonium chloride solution and a glycidyl trimethyl ammonium chloride solution, the mass ratio of the dimethyldiallyl ammonium chloride solution to the glycidyl trimethyl ammonium chloride solution is 1:2-4, preferably 1:3; the mass concentration of the dimethyldiallyl ammonium chloride solution is 30-40%, preferably 35%; the mass concentration of the glycidyl trimethyl ammonium chloride solution is 30-40%, preferably 35%.

[0034] In the present invention, in the step (3), the mass ratio of the mixed alcohol polyether, the cationic modifier and the solvent is 70-100:3-8:100-200, preferably 80-90:4-7:110-190, and more preferably 85:5-6:120-180; the reaction temperature is 60-80°C, preferably 65-75°C, and more preferably 70°C; the reaction time is 2-3h, and preferably 2.5h.

[0035] The present invention also provides an anti-emulsifier for fracturing prepared by the preparation method of the anti-emulsifier for fracturing described above.

[0036] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1

[0038] 0.5 kg of decyltetradecyl alcohol, 1.5 kg of diethylene glycol and 0.5 kg of potassium hydroxide were added to the reactor, vacuumed and replaced with nitrogen. The pressure in the reactor was -0.1 MPa. Stirring was performed at 500 rpm for 20 min. After mixing evenly, heating was performed to 110° C., and then 80 kg of ethylene oxide was added and the temperature was raised to 130° C. The mixture was reacted at 130° C. for 30 min to obtain a reaction intermediate.

[0039] 350 kg of propylene oxide and 3 kg of potassium hydroxide were added into the reactor, mixed with the reaction intermediate, and reacted at 120° C. for 30 min at a rotation speed of 500 rpm to obtain a mixed alcohol polyether.

[0040] 80 kg of mixed alcohol polyether, 5 kg of epoxypropyltrimethylammonium chloride aqueous solution (mass concentration of 30%) and 150 kg of propanol were mixed evenly in a reactor, heated to 70° C., and reacted at a rotation speed of 300 rpm for 2.5 hours to obtain an anti-emulsifier for fracturing.

[0041] Example 2

[0042] 0.5 kg of decyltetradecyl alcohol, 2.5 kg of diethylene glycol and 1 kg of potassium hydroxide were added to the reactor, vacuumed and replaced with nitrogen. The pressure in the reactor was -0.2 MPa. Stirring was performed at 600 rpm for 30 min. After mixing evenly, heating was performed to 105°C. Then 100 kg of ethylene oxide was added and the temperature was raised to 120°C. The reaction was carried out at 120°C for 45 min to obtain a reaction intermediate.

[0043] 500 kg of propylene oxide and 2.5 kg of potassium hydroxide were added into the reactor, mixed with the reaction intermediate, and reacted at 115° C. for 45 minutes at a rotation speed of 600 rpm to obtain a mixed alcohol polyether.

[0044] 100 kg of mixed alcohol polyether, 3 kg of dimethyldiallylammonium chloride aqueous solution (mass concentration of 40%) and 200 kg of anhydrous ethanol were mixed evenly in a reactor, heated to 80° C., and reacted at a rotation speed of 300 rpm for 2 hours to obtain an anti-emulsifier for fracturing.

[0045] Example 3

[0046] 0.5 kg of decyltetradecyl alcohol, 0.5 kg of diethylene glycol and 0.4 kg of potassium hydroxide were added to the reactor, vacuumed and replaced with nitrogen. The pressure in the reactor was -0.5 MPa. Stirring was carried out at 400 rpm for 25 minutes. After mixing evenly, heating was carried out to 100°C. Then, 50 kg of ethylene oxide was added and the temperature was raised to 140°C. The reaction was carried out at 140°C for 15 minutes to obtain a reaction intermediate.

[0047] 300 kg of propylene oxide and 1 kg of potassium hydroxide were added into the reactor, mixed with the reaction intermediate, and reacted at 125° C. for 15 min at a rotation speed of 400 rpm to obtain a mixed alcohol polyether.

[0048] 70 kg of mixed alcohol polyether, 2 kg of epoxypropyltrimethylammonium chloride aqueous solution (mass concentration of 35%), 6 kg of dimethyldiallylammonium chloride aqueous solution (mass concentration of 35%) and 100 kg of propanol were mixed evenly in a reactor, heated to 60° C., and reacted at a rotation speed of 200 rpm for 3 hours to obtain an anti-emulsifier for fracturing.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that decyltetradecanol is not added, and other conditions are the same.

[0051] Comparative Example 2

[0052] The difference from Example 1 is that no diethylene glycol is added, the mass of decyltetradecyl alcohol is 2 kg, and other conditions are the same.

[0053] Comparative Example 3

[0054] The difference from Example 1 is that no epoxypropyltrimethylammonium chloride solution is added, and other conditions are the same.

[0055] Dehydration rate test: The dehydration rate test was performed on the demulsifiers for fracturing prepared in Examples 1 to 3 and Comparative Examples 1 to 3. The test method is as follows:

[0056] (1) Take 18 100 mL colorimetric tubes and number them from 1 to 18;

[0057] (2) Add 80 mL of crude oil emulsion (obtained from Shengli Oilfield) into each colorimetric tube, and then place the colorimetric tube in a constant temperature water bath at 40°C for 30 min.

[0058] (3) Add the anti-emulsifier of Example 1 to colorimetric tubes No. 1 to 3; add the anti-emulsifier of Example 2 to colorimetric tubes No. 4 to 6; add the anti-emulsifier of Example 3 to colorimetric tubes No. 7 to 9; add the anti-emulsifier of Comparative Example 1 to colorimetric tubes No. 10 to 12; add the anti-emulsifier of Comparative Example 2 to colorimetric tubes No. 13 to 15; add the anti-emulsifier of Comparative Example 3 to colorimetric tubes No. 16 to 18, ensuring that after the anti-emulsifier is added to each colorimetric tube, the mass concentration of the anti-emulsifier is 1%.

[0059] (4) Close the lid of the colorimetric tube tightly, press the lid with your finger and shake the tube up and down 5 times, then slowly loosen the lid of the colorimetric tube to release the air, and finally tighten the lid again.

[0060] (5) Place the colorimetric tube in a 40°C water bath oscillator and oscillate at 200 rpm for 5 minutes to mix thoroughly. Remove the colorimetric tube, loosen the lid, and then place the colorimetric tube with the lid tightened in a constant temperature water bath to settle. Record the dehydration amount at different times and calculate the arithmetic mean of the test results of the parallel samples as the final test result. The dehydration rate test results are shown in Table 1.

[0061] Table 1 Dehydration rate test results of anti-emulsifier

[0062] serial number 30min dehydration rate / % 60min dehydration rate / % water color Example 1 91.8 98.2 Clear water, clear interface Example 2 90.8 97.6 Clear water, clear interface Example 3 93.2 99.3 Clear water, clear interface Comparative Example 1 85.1 87.6 The water is turbid and the interface is fuzzy Comparative Example 2 83.6 85.9 The water is turbid and the interface is fuzzy Comparative Example 3 80.5 82.4 The water is turbid and the interface is fuzzy

[0063] It can be seen from Table 1 that the mixed alcohol polyether prepared by the composite initiator and then modified by the cationic modifier can improve the dehydration rate of the demulsifier. The demulsifier prepared by the preparation method of the present invention has excellent dehydration performance, and the dehydration rate reaches more than 97.6%.

[0064] It can be seen from the above embodiments that the present invention provides an anti-emulsifier for fracturing and a preparation method thereof, firstly, a composite initiator and potassium hydroxide are mixed and heated, and then ethylene oxide is added for reaction to obtain a reaction intermediate; the reaction intermediate is reacted with propylene oxide and potassium hydroxide to obtain a mixed alcohol polyether; finally, the mixed alcohol polyether, a cationic modifier and a solvent are mixed and reacted to obtain an anti-emulsifier for fracturing, wherein the composite initiator comprises decyltetradecanol and diethylene glycol. The present invention uses decyltetradecanol and diethylene glycol as initiators to obtain a mixed alcohol polyether, and then the mixed alcohol polyether is subjected to cationic modification, and the obtained anti-emulsifier has a dehydration rate of up to 99.3%, which is very suitable for use as an anti-emulsifier in oilfield acidification operations.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an anti-emulsifier for fracturing, characterized in that: The steps include: (1) mixing the composite initiator and potassium hydroxide and heating them, then adding ethylene oxide to react to obtain a reaction intermediate; (2) reacting the reaction intermediate with propylene oxide and potassium hydroxide to obtain a mixed alcohol polyether; (3) The mixed alcohol polyether, the cationic modifier and the solvent are mixed and reacted to obtain an anti-emulsifier for fracturing; The composite initiator comprises decyltetradecanol and diethylene glycol; The mass ratio of decyltetradecyl alcohol to diethylene glycol is 1:1-5; The cationic modifier comprises a dimethyldiallyl ammonium chloride solution and / or a glycidyltrimethylammonium chloride solution; The mass ratio of the mixed alcohol polyether, the cationic modifier and the solvent is 70-100:3-8:100-200.

2. The method for preparing an anti-emulsifier for fracturing according to claim 1, characterized in that: In the step (1), the mass ratio of the composite initiator, potassium hydroxide and ethylene oxide is 1-3:0.4-1:50-100.

3. The method for preparing the demulsifier for fracturing according to claim 1 or 2, characterized in that: In the step (1), the heating temperature is 100-110° C.; the reaction temperature is 120-140° C., and the reaction time is 15-45 min.

4. The method for preparing the demulsifier for fracturing according to claim 3, characterized in that: The mass ratio of the ethylene oxide in step (1), the propylene oxide in step (2), and the potassium hydroxide in step (2) is 50-100:300-500:1-3.

5. The method for preparing the demulsifier for fracturing according to claim 2 or 4, characterized in that: In the step (2), the reaction temperature is 115-125° C., and the reaction time is 15-45 min.

6. The method for preparing an anti-emulsifier for fracturing according to claim 5, characterized in that: In the step (3), the solvent is one or more of methanol, ethanol, propanol and isopropanol.

7. The method for preparing an anti-emulsifier for fracturing according to claim 6, characterized in that: When the cationic modifier comprises dimethyldiallyl ammonium chloride solution and glycidyltrimethylammonium chloride solution, the mass ratio of the dimethyldiallyl ammonium chloride solution to the glycidyltrimethylammonium chloride solution is 1:2-4; the mass concentration of the dimethyldiallyl ammonium chloride solution is 30-40%; the mass concentration of the glycidyltrimethylammonium chloride solution is 30-40%.

8. The method for preparing the demulsifier for fracturing according to claim 2, 4 or 6, characterized in that: In the step (3), the reaction temperature is 60-80° C. and the reaction time is 2-3 h.

9. The demulsifier for fracturing obtained by the method for preparing the demulsifier for fracturing according to any one of claims 1 to 8.