Demulsifier for deep dehydration of crude oil in combination station settling tank, and preparation method and application thereof

Abstract

The present application relates to the field of oil chemical additives for oil field development, and discloses a demulsifier for deep dehydration of crude oil in a settling tank of a combination station, a preparation method and application thereof.The demulsifier is composed of the following components and mass fractions: polyoxyethylene polyoxypropylene block polyether 30-50 mass fractions; weight matching agent 1-10 mass fractions; pH regulator 2-10 mass fractions; acidizing corrosion inhibitor 1 mass fraction; solvent 23-62 mass fractions.The demulsifier is mainly used for the case that poor crude oil after operation enters the production system of the combination station and the settling time of crude oil in the settling tank is prolonged.After the demulsifier is added to the top of the tank, the oil-water emulsification in the settling tank can be eliminated, the deep dehydration effect can be achieved, the water content (by mass) of the crude oil in the settling tank is reduced to below 0.3%, and the settling time is shortened by more than 4 hours.

Description

Technical Field

[0001] This invention relates to the field of petrochemical additives for oilfield development, specifically to a demulsifier for deep dehydration of crude oil in settling tanks of combined stations, its preparation method, and its application. Background Technology

[0002] In recent years, to ensure national energy security, and with the nationwide development of crude oil extraction towards heavier and lower-quality products, various operational measures have been implemented to extract previously difficult-to-access reserves (such as high-viscosity oil, extra-heavy oil, and oil reservoirs with poor geological conditions). This has led to a significant increase in the production of low-quality crude oil, with a trend of increasing year by year. This type of crude oil typically exhibits the following characteristics:

[0003] (1) It has high density and high acid value, and contains various natural emulsifiers;

[0004] (2) It has a high content of gum and asphalt, and inorganic salts in crude oil are easily encapsulated within it;

[0005] (3) The use of chemical oil recovery additives during the operation resulted in severe emulsification of crude oil.

[0006] Because of the aforementioned characteristics of inferior high-acid crude oil, the difficulty of demulsification and dehydration of inferior crude oil is greatly increased. In particular, when these inferior crude oils are mixed with normal crude oil, they seriously affect the demulsification and dehydration of normal crude oil, affecting the stable production and operation of the joint station and reducing the operating efficiency of the joint station.

[0007] Currently, there are numerous types of crude oil demulsifiers available both domestically and internationally, most of which are non-ionic, each with its own advantages and disadvantages in demulsification. However, in terms of molecular composition, they are primarily copolymers of ethylene oxide and propylene oxide. These demulsifiers are effective for treating normal crude oil, but their demulsification effect is less than ideal for inferior crude oil after processing, especially when normal crude oil is mixed with some inferior crude oil. The effect is poor, settling time is prolonged, and the overall water content in the settling tank becomes difficult to decrease further after reaching about 1%, severely reducing the operating efficiency of the combined station and even causing the station to overflow. Therefore, it is necessary to add demulsifier to the top of the settling tank at specific times to shorten the demulsification and dehydration time.

[0008] Patent CN104673359A discloses a phenolic amine resin demulsifier, but it is not effective for inferior crude oil after operation; patent CN105316028A discloses an organic acid-polyether type sludge demulsifier, and patent CN102140365A discloses an acid-containing crude oil demulsifier, but neither of them is suitable for adding chemicals to the top of the settling tank of the combined station. Summary of the Invention

[0009] To overcome the shortcomings of existing technologies, this invention provides a demulsifier for deep dehydration of crude oil in settling tanks of combined dewatering stations, its preparation method, and its application. The technical solution is as follows:

[0010] A demulsifier for deep dehydration of crude oil in settling tanks of a combined demulsifier station, the demulsifier being composed of the following components and their parts by weight: 30-50 parts by weight of polyoxyethylene polyoxypropylene block polyether; 1-10 parts by weight of weighting agent; 2-10 parts by weight of pH adjuster; 1 part by weight of acidification corrosion inhibitor; and 23-62 parts by weight of solvent.

[0011] Furthermore, the polyoxyethylene polyoxypropylene block polyether is a phenolic amine resin-based polyoxyethylene polyoxypropylene block polyether. The synthesis reaction formula for the phenolic amine resin is as follows:

[0012]

[0013] Furthermore, the weighting agent is tetrahydroxymethylphosphine sulfate.

[0014] Furthermore, the pH adjuster is a mixture of citric acid and aminosulfonic acid.

[0015] Furthermore, the mass ratio of citric acid to aminosulfonic acid is 1:1.

[0016] Furthermore, the acidification corrosion inhibitor is an imidazoline-based corrosion inhibitor.

[0017] Furthermore, the solvent is a mixture of any one of the C1-C2 alcohols and water, with the mass ratio of alcohol to water being 1:(0.5-1.5).

[0018] Furthermore, the alcohol is methanol.

[0019] The preparation method of the demulsifier for deep dehydration of crude oil in the settling tank of a combined dewatering station, as described above, includes the following steps:

[0020] (1) Phenolic amine resin and propylene oxide are polymerized at a mass ratio of 1:(25-199) to obtain an intermediate polymer product; the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa and a reaction temperature of 130-140℃.

[0021] (2) The intermediate polymerization product is polymerized with ethylene oxide to obtain phenolic resin-based polyoxyethylene polyoxypropylene block polyether. The amount of ethylene oxide used is 15 to 65 times the mass of the phenolic amine resin in step (1). The polymerization reaction needs to be controlled with a reaction pressure ≤ 0.4 MPa and a reaction temperature of 130 to 140 °C. The polymerization reaction ends when the reaction pressure no longer decreases.

[0022] (3) Add the phenolic resin polyoxyethylene polyoxypropylene block polyether, weighting agent, pH adjuster, acidification corrosion inhibitor and solvent prepared in step (2) into the reactor according to their mass parts, and stir at 40-50℃ for 20-40 minutes to make it into a homogeneous mixture, which is the demulsifier.

[0023] The above describes the application of a demulsifier for deep dehydration of crude oil in settling tanks at joint stations in oilfield development.

[0024] Compared with the prior art, the present invention has the following main advantages:

[0025] 1. The demulsifier of this invention is mainly used when the crude oil in the settling tank after the operation enters the production system of the combined station and the settling tank has a long settling time. The agent is added to the top of the tank. After adding the demulsifier to the top of the tank, the oil-water emulsification in the settling tank can be eliminated, and a deep dehydration effect can be achieved, so that the water content (by mass) of the crude oil in the settling tank is reduced to below 0.3%, and the settling time is shortened by more than 4 hours.

[0026] 2. The counterweight agent used in this invention is tetramethylphosphosulfate, which can quickly carry the demulsifier from the top of the crude oil in the settling tank into the middle and lower part of the crude oil in the settling tank. During the descent, the demulsifier disrupts the charge balance of the emulsion film interface, reduces the interface strength, and achieves the purpose of dehydration.

[0027] 3. The pH adjuster used in this invention is a mixture of citric acid and aminosulfonic acid, which can quickly assist the demulsifier to enter the oil-water emulsion interface, disrupt the charge balance of the emulsion film interface, and reduce the interface strength.

[0028] 4. The demulsifier preparation process of this invention is reasonable and easy to operate, which is conducive to its widespread application. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments. Example 1

[0030] (1) Phenolic amine resin and propylene oxide are polymerized at a mass ratio of 1:25 to obtain an intermediate polymerization product; the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa and a reaction temperature of 130℃.

[0031] (2) The intermediate polymerization product is polymerized with ethylene oxide to obtain phenolic resin polyoxyethylene polyoxypropylene block polyether, wherein the amount of ethylene oxide is 15 times the mass of phenolic amine resin in step (1); the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa, the reaction temperature is maintained at 130°C, and the polymerization reaction ends when the reaction pressure no longer decreases.

[0032] (3) Add the phenolic resin polyoxyethylene polyoxypropylene block polyether, weighting agent, pH adjuster, acidification corrosion inhibitor and solvent prepared in step (2) into the reactor according to the mass parts in the following formula, and stir at 40°C for 20 minutes to make it into a homogeneous mixture, which is the demulsifier.

[0033] The demulsifier formula is as follows:

[0034] 30 parts by weight of the amine-phenol-aldehyde-amine resin-based polyoxyethylene-polyoxypropylene block polyether prepared above;

[0035] 1 part by weight of tetramethylphosphine sulfate;

[0036] 1 part by weight of citric acid;

[0037] 1 part by weight of aminosulfonic acid;

[0038] 1 part by weight of imidazoline corrosion inhibitor;

[0039] 15 parts by weight of methanol;

[0040] 8 parts by weight of water.

[0041] At Tank No. 5 of the No. 4 Joint Station of the No. 2 Oil Production Plant of Tahe Oilfield, the comprehensive water content (by mass) of the fifth grade decreased from 0.8% to 0.7% within 5 hours after production was completed, but the decrease was slow. After adding the above-mentioned demulsifier to the top of the tank, the comprehensive water content (by mass) of the fifth grade of Tank No. 5 decreased from 0.7% to 0.3% within 4 hours, and the oil was delivered in compliance with the requirements. Example 2

[0042] (1) Phenolic amine resin and propylene oxide are polymerized at a mass ratio of 1:199 to obtain an intermediate polymerization product; the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa and a reaction temperature of 140℃.

[0043] (2) The intermediate polymerization product is polymerized with ethylene oxide to obtain phenolic resin polyoxyethylene polyoxypropylene block polyether, wherein the amount of ethylene oxide is 65 times the mass of phenolic amine resin in step (1); the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa, the reaction temperature is maintained at 140°C, and the polymerization reaction ends when the reaction pressure no longer decreases.

[0044] (3) Add the phenolic resin polyoxyethylene polyoxypropylene block polyether, weighting agent, pH adjuster, acidification corrosion inhibitor and solvent prepared in step (2) into the reactor according to the mass parts in the following formula, and stir at 50°C for 40 minutes to make it into a homogeneous mixture, which is the demulsifier.

[0045] The demulsifier formula is as follows:

[0046] 50 parts by weight of the amine-phenol-aldehyde-amine resin-based polyoxyethylene-polyoxypropylene block polyether prepared above;

[0047] 10 parts by weight of tetramethylphosphine sulfate;

[0048] 5 parts by weight of citric acid;

[0049] 5 parts by weight of aminosulfonic acid;

[0050] 1 part by weight of imidazoline corrosion inhibitor;

[0051] 25 parts by weight of methanol;

[0052] 37 parts by weight of water.

[0053] At Tank No. 6 of the No. 4 Joint Station of the No. 2 Oil Production Plant of Tahe Oilfield, the comprehensive water content (by mass) of the fifth grade decreased from 0.8% to 0.6% within 6 hours after production was completed, but the decrease was slow. After adding the above-mentioned demulsifier to the top of the tank, the comprehensive water content (by mass) of the fifth grade of Tank No. 6 decreased from 0.6% to 0.25% within 3 hours, and the oil was delivered in compliance with the requirements. Example 3

[0054] (1) Phenolic amine resin and propylene oxide are polymerized at a mass ratio of 1:99 to obtain an intermediate polymer product; the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa and a reaction temperature of 135℃.

[0055] (2) The intermediate polymerization product is polymerized with ethylene oxide to obtain phenolic resin polyoxyethylene polyoxypropylene block polyether, wherein the amount of ethylene oxide is 45 times the mass of phenolic amine resin in step (1); the polymerization reaction needs to be controlled with a reaction pressure ≤0.4 MPa, the reaction temperature is maintained at 135°C, and the polymerization reaction ends when the reaction pressure no longer decreases.

[0056] (3) Add the phenolic resin polyoxyethylene polyoxypropylene block polyether, weighting agent, pH adjuster, acidification corrosion inhibitor and solvent prepared in step (2) into the reactor according to the mass parts in the following formula, and stir at 45°C for 30 minutes to make it into a homogeneous mixture, which is the demulsifier.

[0057] The demulsifier formula is as follows:

[0058] 40 parts by weight of the amine-phenol-aldehyde-amine resin-based polyoxyethylene-polyoxypropylene block polyether prepared above;

[0059] 5 parts by weight of tetramethylphosphine sulfate;

[0060] Citric acid, 3 parts by weight;

[0061] 3 parts by weight of aminosulfonic acid

[0062] 1 part by weight of imidazoline corrosion inhibitor;

[0063] 20 parts by weight of methanol;

[0064] 20 parts by weight of water.

[0065] At Tank No. 8 of the No. 4 Joint Station of the No. 2 Oil Production Plant of Tahe Oilfield, the comprehensive water content (by mass) of the fifth grade decreased from 0.9% to 0.75% within 6 hours after production was completed, but the decrease was slow. After adding the above-mentioned demulsifier to the top of the tank, the comprehensive water content (by mass) of the fifth grade of Tank No. 8 decreased from 0.75% to 0.25% within 4 hours, and the oil was delivered in compliance with the requirements.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A demulsifier for deep dehydration of crude oil in settling tanks of a combined dewatering station, characterized in that, The demulsifier comprises the following components and their weight parts: 30-40 parts by weight of polyoxyethylene polyoxypropylene block polyether; 1-10 parts by weight of a weighting agent, wherein the weighting agent is tetramethylolphosphine sulfate; 2-10 parts by weight of a pH adjuster, wherein the pH adjuster is a mixture of citric acid and aminosulfonic acid, wherein the mass ratio of citric acid to aminosulfonic acid is 1:1; 1 part by weight of an acidification corrosion inhibitor, wherein the acidification corrosion inhibitor is an imidazoline corrosion inhibitor; and 23-62 parts by weight of a solvent. The polyoxyethylene polyoxypropylene block polyether is a phenolic amine resin-based polyoxyethylene polyoxypropylene block polyether. The solvent is a mixture of methanol and water, with a mass ratio of methanol to water of 1:(0.5 to 1.5). The preparation method of the above-mentioned demulsifier for deep dehydration of crude oil in the settling tank of the combined station includes the following steps: (1) Phenolic amine resin and propylene oxide are polymerized at a mass ratio of 1:(25-199) to obtain an intermediate polymerization product; the polymerization reaction needs to be controlled with a reaction pressure ≤0.4Mpa and a reaction temperature of 130-140℃. (2) The intermediate polymerization product is polymerized with ethylene oxide to obtain phenolic amine resin polyoxyethylene polyoxypropylene block polyether, wherein the amount of ethylene oxide is 15 to 65 times the mass of phenolic amine resin in step (1); in step (2), the polymerization reaction needs to be controlled with a reaction pressure ≤ 0.4 MPa, the reaction temperature is maintained at 130 to 140 °C, and the polymerization reaction ends when the reaction pressure no longer decreases; (3) The phenolic amine resin polyoxyethylene polyoxypropylene block polyether, weighting agent, pH adjuster, acidification corrosion inhibitor and solvent prepared in step (2) are added to the reactor according to their mass parts, and stirred at 40-50℃ for 20-40 minutes to make it into a homogeneous mixture, which is the demulsifier.

2. The demulsifier of claim 1 is used for deep dehydration of crude oil in the settling tank of a combined dehydration station, characterized in that, The demulsifier is added from the top of the settling tank at the combined station.

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