Demulsifier for heavy oil oilfield and preparation method thereof

Abstract

The application belongs to the technical field of oil exploitation, and particularly relates to a demulsifier for heavy oil oilfield and a preparation method thereof. The demulsifier is prepared by the following method: in a high-pressure reaction kettle, trimethoxy[3-(anilino)propyl]silane and a catalyst are sequentially added, the reaction kettle is purged with nitrogen, vacuumizing and heating are simultaneously performed, when the temperature reaches 90 DEG C, the vacuumizing is stopped, ethylene oxide is introduced, the temperature is increased to 140-170 DEG C and the reaction is kept, the reaction pressure is gradually decreased, when the pressure no longer decreases, the reaction is stopped, cooling and filtering are performed, the filtrate is adjusted to pH 3-4 with sulfuric acid, is transferred into the above high-pressure reaction kettle, sulfamic acid is added, stirring and heating to 100-130 DEG C are performed, the reaction is kept for 1-4 h, the temperature is cooled to below 60 DEG C, the pH is adjusted to 7-8 with sodium hydroxide solution, 10wt% ethanolamine solution is added, and the product demulsifier is obtained by dissolving. The demulsifier has the characteristics of simple synthesis process and high oil removal rate.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, specifically relating to a demulsifier for heavy oil fields and its preparation method. Background Technology

[0002] Crude oil extracted from the ground is mostly in the form of an oil-water emulsion. Currently, the comprehensive water content of crude oil in most onshore oil fields in China is over 80%, which increases the load on pumps, pipelines and storage tanks, and causes corrosion and scaling on the surface of metal equipment. Furthermore, the crude oil contained in the discharged water also causes environmental pollution and waste of crude oil. Therefore, from both an economic and environmental protection perspective, it is necessary to demulsify and dehydrate crude oil to achieve a result of clean oil and clear water.

[0003] With the continuous advancement of new technologies, crude oil recovery rates have been significantly improved, but at the same time, water emulsification has become increasingly severe. The higher the oil content in the produced water, the more diverse the forms of the crude oil emulsion, and the greater the difficulty in demulsifying and dehydrating the crude oil.

[0004] Due to their high activity and rapid effect, chemical demulsifiers are currently the most commonly used method for crude oil dehydration. Demulsifiers are oilfield chemicals used for oil-water separation in produced fluids. Their principle is that the demulsifier penetrates and adheres to the interface of the emulsion droplets, replacing the original emulsifier and disrupting the surface film. This releases the droplets encapsulated within the film and causes them to coalesce, thereby separating the oil and water phases.

[0005] CN109575984A discloses a crude oil demulsifier for use at room temperature and low temperature. Its composition is as follows: 10-50% by mass of a siloxane polyether with a viscosity of 200-300 cSt, an HLB value of 7-10, and a closed-cup flash point greater than 60℃; and 50-90% by mass of a mixture of one or more of these as a solvent. The siloxane polyether in the crude oil demulsifier has different structures and molecular weight distributions, exhibiting highly efficient oil-water demulsification. Siloxane possesses low surface tension, low cohesive energy, and low temperature sensitivity, enabling demulsification at low temperatures up to 30℃. Furthermore, the amount added is reduced by more than 50% compared to using polyether surfactants alone, resulting in a faster dehydration rate, better demulsification effect, and lower overall cost. However, this invention's crude oil demulsifier only achieves a crude oil dehydration rate of 40% after 120 minutes, which cannot meet production needs, and the dehydration effect needs further improvement.

[0006] CN 200510130345A discloses a polyether-type crude oil demulsifier. It uses polyethylene polyamine or nonylphenol aldehyde resin as an initiator, reacting it with ethylene oxide and propylene oxide to obtain a polyether, which is then reacted with a chain extender and pyridine to obtain the final product. This invention has advantages such as simple preparation process, low dosage, good demulsification and dehydration effect, and low cost. However, this demulsifier cannot achieve the effect of low-temperature demulsification to save heat energy. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a demulsifier for heavy oil fields and its preparation method. The demulsifier of this invention features a simple synthesis process and a high oil removal rate.

[0008] One objective of this invention is to disclose a demulsifier for heavy oil fields, the molecular structural formula of which is as follows:

[0009]

[0010] Where n is a positive integer between 4 and 40.

[0011] Another object of the present invention is to provide a method for preparing a demulsifier for heavy oil fields, wherein the method for preparing the demulsifier is as follows:

[0012] (1) Trimethoxy[3-(phenylamino)propyl]silane and catalyst are added sequentially to a high-pressure reactor. The reactor is purged with nitrogen and the temperature is raised while the vacuum is drawn. When the temperature reaches 90°C, the vacuum is stopped and ethylene oxide is introduced. The temperature is raised to 140-170°C and the reaction is maintained. The reaction pressure is gradually reduced. When the pressure stops decreasing, the reaction is stopped.

[0013] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above-mentioned high-pressure reactor, add aminosulfonic acid, heat to 100-130℃ while stirring, keep the reaction at the temperature for 1-4 hours, cool to below 60℃, adjust the pH to 7-8 with sodium hydroxide solution, add 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier.

[0014] In this invention, preferably, the molar ratio of ethylene oxide, aminosulfonic acid, and trimethoxy[3-(phenylamino)propyl]silane is 4-40:0.8-1.2:1. More preferably, the molar ratio of ethylene oxide, aminosulfonic acid, and trimethoxy[3-(phenylamino)propyl]silane is 10-40:0.9-1.1:1.

[0015] In this invention, preferably, the catalyst in step (1) is one of sodium hydroxide, calcium hydroxide, and potassium hydroxide, and the mass ratio of the catalyst to trimethoxy[3-(phenylamino)propyl]silane is 0.05-0.2:1.

[0016] In this invention, preferably, the mass ratio of the 10wt% ethanolamine solution to trimethoxy[3-(phenylamino)propyl]silane in step (2) is 2-6:1.

[0017] The synthesis reaction equation for the demulsifier for heavy oil fields of the present invention is as follows:

[0018]

[0019]

[0020] The demulsifier for heavy oil fields of this invention is a silicone polyether demulsifier with excellent surface activity, achieving highly efficient demulsification under harsh conditions. The lipophilic groups are silane and benzene rings, while the hydrophilic groups are polyoxyethylene ether segments and sulfate groups. Due to its superior interfacial activity, the molecules of this invention can enter the oil-water interface, replacing strong emulsifying surfactants. This displaces surfactant molecules and other surface-active substances from oil droplets, disrupting their emulsifying ability and allowing smaller droplets to more easily aggregate. Upon entering the oil droplets, this invention compresses and disrupts the electric double layer, weakening the interfacial film strength, causing the emulsion droplets to collide and coalesce, releasing them to form larger oil droplets, thus achieving demulsification. The polyether segment in this molecule has a linear structure and high flexibility, easily undergoing internal rotation of the molecular chain, capturing tiny oil droplets, increasing the chance of droplet collisions, and forming oil droplets that easily aggregate and float, thereby achieving demulsification. The demulsifier for heavy oil fields of this invention exhibits excellent stability and heat resistance, maintaining stable performance under high temperature and high pressure conditions.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The raw materials for the demulsifier used in heavy oil fields of the present invention are widely available, inexpensive, and have a simple synthesis process;

[0023] (2) The demulsifier for heavy oil fields of the present invention has a good demulsification effect. When the concentration is 100 mg / L, the oil removal rate reaches 98.8% or more. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments and data. It should be understood that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention in any way. Example

[0025] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 1.28 g of sodium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 0.4 mol of ethylene oxide, raise the temperature to 140°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0026] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.08 mol of aminosulfonic acid, heat to 100°C while stirring, keep the reaction at 1 h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 51 g of 10 wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0027] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 2.4 g of sodium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 0.8 mol of ethylene oxide, raise the temperature to 140°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0028] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.12 mol aminosulfonic acid, heat to 100°C while stirring, keep the reaction at 1 h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 75 g 10 wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0029] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 2.8 g of sodium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature simultaneously. When the temperature reaches 90°C, stop evacuating the system, introduce 1 mol of ethylene oxide, raise the temperature to 150°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0030] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.085 mol aminosulfonic acid, heat to 110°C while stirring, keep the reaction at 2h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 90g 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0031] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 3.9 g of calcium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 1.5 mol of ethylene oxide, raise the temperature to 155°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0032] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.115 mol aminosulfonic acid, heat to 111°C while stirring, keep the reaction at 2.5 h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 102 g 10 wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0033] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 4.2 g of calcium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 2 mol of ethylene oxide, raise the temperature to 160°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0034] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.09 mol of aminosulfonic acid, heat to 120°C while stirring, keep the reaction at 3h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 115g of 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0035] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 4.5 g of potassium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 2.5 mol of ethylene oxide, raise the temperature to 160°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0036] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.11 mol aminosulfonic acid, heat to 120°C while stirring, keep the reaction at 4h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 128g 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0037] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 4.8 g of potassium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 3 mol of ethylene oxide, raise the temperature to 165°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0038] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.095 mol aminosulfonic acid, heat to 130°C while stirring, keep the reaction at 2h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 141g 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. Example

[0039] (1) Add 0.1 mol of trimethoxy[3-(phenylamino)propyl]silane and 5.1 g of potassium hydroxide sequentially to a high-pressure reactor. Purge the reactor with nitrogen gas, evacuate the system, and raise the temperature. When the temperature reaches 90°C, stop evacuating the system, introduce 4 mol of ethylene oxide, raise the temperature to 170°C, and maintain the temperature for the reaction. Gradually decrease the reaction pressure. Stop the reaction when the pressure stops decreasing.

[0040] (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add 0.1 mol aminosulfonic acid, heat to 130°C while stirring, keep the reaction at 3.5 h, cool to below 60°C, adjust the pH to 7-8 with sodium hydroxide solution, add 153 g 10 wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier.

[0041] Example 9 Evaluation of demulsification effect

[0042] After the combined oil displacement fluid from a heavy oil block in an oilfield was allowed to stand for 24 hours and the oil and water were separated, a crude oil sample from the intermediate emulsion zone was taken. The oil content was tested and found to be 28,000 mg / L.

[0043] At 65℃, the demulsifier performance of the present invention (Examples 1-8) was evaluated with reference to SY / T 5797-1993 "Evaluation Method for Performance of Demulsifiers for Oil-in-Water Emulsions", with dosages of 50 and 100 mg / L.

[0044] The evaluation results are shown in Table 1.

[0045] Table 1. Demulsifier Performance Test Results

[0046]

[0047] As can be seen from Table 1:

[0048] (1) The demulsifier for heavy oil fields of the present invention (Examples 1-7) has an oil removal rate of more than 98% when the concentration is 50 mg / L, and the highest reaches 99.6%, with good demulsification effect;

[0049] (2) The demulsifier for heavy oil fields of the present invention (Examples 1-7) has an oil removal rate of greater than or equal to 98.8% and a maximum of 99.7% when the concentration is 100 mg / L; the demulsification effect is good.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions are also considered to be within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any equivalent changes, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a demulsifier for heavy oil fields, characterized in that, The demulsifier is prepared as follows: (1) Trimethoxy[3-(phenylamino)propyl]silane and catalyst are added sequentially to a high-pressure reactor. The reactor is purged with nitrogen and the temperature is raised while the vacuum is drawn. When the temperature reaches 90°C, the vacuum is stopped and ethylene oxide is introduced. The temperature is raised to 140-170°C and the reaction is maintained. The reaction pressure is gradually reduced. When the pressure stops decreasing, the reaction is stopped. (2) Cooling and filtration: Adjust the pH of the filtrate to 3-4 with sulfuric acid, transfer it to the above high-pressure reactor, add aminosulfonic acid, heat to 100-130℃ while stirring, keep the reaction at the temperature for 1-4 hours, cool to below 60℃, adjust the pH to 7-8 with sodium hydroxide solution, add 10wt% ethanolamine solution, stir and dissolve to obtain the product demulsifier. The molecular structure of the demulsifier is as follows: ， Where n is a positive integer between 4 and 40; The molar ratio of ethylene oxide, aminosulfonic acid and trimethoxy[3-(phenylamino)propyl]silane is 4-40:0.8-1.2:

1.

2. The method for preparing a demulsifier for heavy oil fields according to claim 1, characterized in that, The molar ratio of ethylene oxide, aminosulfonic acid, and trimethoxy[3-(phenylamino)propyl]silane is 10-40. 0.9-1.1：1。 3. The method for preparing a demulsifier for heavy oil fields according to claim 1, characterized in that, The catalyst mentioned in step (1) is one of sodium hydroxide, calcium hydroxide, and potassium hydroxide, and the mass ratio of it to trimethoxy[3-(phenylamino)propyl]silane is 0.05-0.2:

1.

4. The method for preparing a demulsifier for heavy oil fields according to claim 1, characterized in that, The mass ratio of the 10wt% ethanolamine solution to trimethoxy[3-(phenylamino)propyl]silane in step (2) is 2-6:

1.

5. A demulsifier for heavy oil fields, characterized in that, The molecular structure of the demulsifier is as follows: ， Where n is a positive integer between 4 and 40.

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