Offshore aged oil demulsifier and aged oil treatment method

Abstract

The invention discloses an offshore aged oil demulsifier and an aged oil treatment method. The treatment method comprises the following steps: adding an aged oil demulsifier into aged oil, uniformly mixing, and transferring into a tempering buffer tank for full reaction; after reaction, aged oil is conveyed to a first-stage centrifugal machine through a buffer tank booster pump, a separated oil phase with the water content smaller than or equal to 1.0% is conveyed to a designated position of a platform, a separated slag phase enters a sludge recycling tank, and a separated water phase enters a second-stage separator; the water phase entering the second-stage separator is subjected to secondary oil removal and slag removal treatment by adding a water clarifier, the separated oil phase medium returns to the tempering buffer tank, the separated slag phase medium enters the sludge recovery tank, the water phase medium enters a third-stage water inlet buffer tank and enters a third-stage water purifier through a booster pump, and water phase deep slag removal treatment is carried out; and transferring the treated water phase with the oil content of less than or equal to 200ppm into a water tank, and separating a slag phase medium to enter a slag phase collecting tank. The process for treating the aged oil is simple, and the on-site treatment and recycling of the aged oil on the sea are realized.

Description

Technical Field

[0001] The invention relates to the technical field of aged oil treatment, and in particular to an offshore aged oil demulsifier and an aged oil treatment method. Background Art

[0002] Aged oil generally refers to a kind of crude oil that is difficult to dehydrate, which is formed under the action of many factors such as chemicals, mechanical impurities (mud), colloids, asphalt, bacteria, air, cyclic shear, electric field, etc. during the process of oilfield exploitation, gathering, transportation, and refining. Aged oil contains a large amount of colloids and asphaltene, which are similar to the heavy components of heavy oil and have a higher percentage. In addition, the aged oil contains clay, sand, FeS, cyclohexane acid substances and some mechanical impurity particles, which lead to higher viscosity, poorer fluidity, higher freezing point, greater density, and extremely difficult demulsification. It is more difficult to handle than ordinary heavy oil. In addition to ground oil fields, offshore oil fields are limited by space and time. In addition to the use of chemical demulsifiers to improve crude oil recovery during the exploitation process, in order to improve the treatment effect and efficiency, large doses of chemical agents are used in the platform crude oil gathering and transportation stage. Compared with the treatment of ground oil field crude oil, the problem of aged oil in offshore oil fields is more prominent, which brings great difficulties to the stable production of oil fields.

[0003] At present, the problem of aging oil in oil fields has become more and more serious with the annual production of oil fields, which has seriously interfered with the normal operation of the dehydration system in the main process of the oil fields, shortened the life of the equipment, or may cause the water content of the exported crude oil to exceed the standard and cause quality accidents. In order not to affect the entire production system, offshore oil fields can only transfer the aging oil out of the production system and store it for later treatment. This has led to the accumulation of a large amount of aging oil, affecting the effective tank capacity and export capacity of the oil fields. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an offshore aged oil demulsifier and an aged oil treatment method. The present invention is an on-site harmless treatment method for offshore aged oil, which relies on a chemical aged oil demulsifier to improve the oil-water interface state, accelerate the separation of oil, water and residue, and improve the oil-water separation effect; in conjunction with a physical separation device, a physical method is used to achieve rapid and efficient separation of oil, water and residue.

[0005] In a first aspect, the present invention provides an aged oil demulsifier, which is achieved by adopting the following technical solution.

[0006] An aged oil demulsifier is composed of a multi-branched polyether, a rapid dispersing aid and a solvent, wherein the mass ratio of the multi-branched polyether, the rapid dispersing aid and the solvent is 30-50:2.0-5.0:45-68; the structural formula of the multi-branched polyether demulsifier is:

[0007]

[0008] Among them, in the block polyether, y:x=1:3-5, x=5-40, and n=3.

[0009] Furthermore, the preparation method of the multi-branched polyether demulsifier is as follows: under the catalysis of tetrabutylammonium hydroxide, polyethylene polyamine and ethylene oxide and propylene oxide are subjected to addition reaction, the addition reaction temperature is 80-95°C, the reaction time is 2-5 hours, and then acetic acid is added to neutralize the pH value of the reaction product to 6.0-7.0 to obtain a multi-branched polyether; wherein the mass ratio of polyethylene polyamine, ethylene oxide and propylene oxide is 1-2:30-50:50-80; the amount of tetrabutylammonium hydroxide used is 1-2% of the mass of polyethylene polyamine.

[0010] Furthermore, the polyethylene polyamine is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentamethyldiethylenetriamine, preferably diethylenetriamine and pentamethyldiethylenetriamine, with a mass ratio of 1:1.

[0011] Furthermore, the rapid dispersing aid is selected from one or more of aminosulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and ethanesulfonic acid.

[0012] Furthermore, the solvent is a mixture of ethylene glycol monobutyl ether and methanol, and the mass ratio of ethylene glycol monobutyl ether to methanol is 1:0.5-3, preferably 1:1.

[0013] In a second aspect, the present invention provides a method for treating aged offshore oil, which is achieved by adopting the following technical solution.

[0014] A method for treating offshore aged oil comprises the following steps:

[0015] S1. According to the amount of aged oil, 1000 to 4000 mg / L of the aged oil demulsifier is added to the aged oil at 60 to 80 ° C;

[0016] S2. The mixture obtained in step S1 is transferred to a tempering buffer tank for full reaction for 2 to 10 hours; the aged oil in the tempering buffer tank is transported to the primary centrifuge via the buffer tank booster pump, and the separated oil phase with a water content of ≤1.0% is transported to the designated position of the platform, the separated slag phase is collected in the sludge recovery tank, and the separated water phase is sent to the secondary separator;

[0017] S3. The water phase entering the secondary separator undergoes secondary oil removal, and 100-200 mg / L of water purifier is added for slag removal treatment. The separated oil phase medium returns to the conditioning buffer tank, the separated slag phase medium enters the sludge recovery tank, and the water phase medium enters the tertiary water inlet buffer tank;

[0018] S4. The water phase from the tertiary water inlet buffer tank enters the tertiary water purifier through a booster pump for deep deslagging treatment. After treatment, the water phase with oil content ≤ 200ppm is transferred to the water tank, and the slag phase medium is separated and enters the slag phase collection tank.

[0019] By adopting the above technical scheme, the present invention has designed and improved a stable aged oil treatment process through a large number of studies, multiple field tests and applications. Through a combination of physical and chemical methods, the oil phase, water phase and slag phase of the aged oil are effectively separated, and the aged oil is processed as a resource. The pollution source that makes it difficult for aged oil to break emulsions and dehydrate comes from the emulsion phase substances in the aged oil. These substances contain a large number of chemical organic components and sludge generated in the production process. For this reason, it must first be chemically quenched and tempered for pretreatment, and then the oil, water and slag three-phase physical separation can achieve a better treatment effect. The aged oil of the offshore oil field is the main treatment medium. By tracking and detecting the indicators such as the water content of the oil phase and the oil content of the water phase at the outlet of the treatment device, the aged oil can be treated to meet the standards. The aged oil treatment process mainly consists of 5 parts, namely: ① quenching and tempering buffer tank; ② primary oil separator; ③ secondary separator; ④ tertiary water purifier; ⑤ slag phase collection tank. Aged oil is lifted by the platform liquid supply pump, heated by the heat exchanger, and evenly mixed with the aged oil treatment agent (if it contains more sand, it needs to be pre-separated and desanded by skid blocks), and enters the tempering buffer tank for full reaction; the aged oil that has reacted completely in the tempering buffer tank is transported to the first-level oil separator via the buffer tank booster pump, and the qualified oil phase (water content ≤1.0%) is separated and transported to the designated position of the platform, and the separated slag phase is collected in the mud recovery tank, and the separated water phase enters the secondary separator; the water phase entering the secondary separator is subjected to secondary oil removal and slag removal treatment, the separated oil phase medium returns to the tempering buffer tank, the separated slag phase medium goes to the mud recovery tank, and the water phase medium enters the third-level water inlet buffer tank; the water phase of the third-level water inlet buffer tank enters the third-level water purifier through the booster pump, and the water phase is deeply deslaged. After treatment, the water phase (oil content ≤200ppm) enters the flash tank outlet manifold O / W left and right secondary water tanks, and the separated slag phase medium enters the slag phase collection tank. The process of treating offshore aged oil by the present invention is simple and does not need to be returned to land for treatment.

[0020] Furthermore, in step S3, the water purifying agent is a cationic polyacrylamide emulsion with a molecular weight of 8 to 10 million and a degree of hydrolysis of 25%.

[0021] This application has the following beneficial effects.

[0022] The present invention relies on the aged oil demulsifier to improve the oil-water interface state, accelerate the separation of oil, water and residue, improve the oil-water separation effect, and cooperate with physical methods to achieve rapid and efficient separation of oil, water and residue. By adopting the process and reagent of the present invention, the oil-water separation of aged oil can be accelerated. The demulsifier used in the present invention has a strong demulsification and dehydration performance, and the water purifier used at the same time has a good water purification function. After the offshore aged oil is treated by the method of the present invention, the oil phase enters the crude oil production process, and the water phase meets the water requirements for reinjection of water injection wells, realizing the resource utilization of the aged oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the process flow of treating aged oil according to the present invention;

[0024] Figure 2 The crude oil and residue phase diagram after the aged oil in Bohai Oilfield is treated by the method of the present invention (the left diagram is the treated crude oil, and the right diagram is the residue phase removed from the treated crude oil). DETAILED DESCRIPTION

[0025] The present patent application is further described below in conjunction with embodiments.

[0026] Example 1

[0027] Preparation of aged oil demulsifier A: In an autoclave, add 2.5g of diethylenetriamine, 2.5g of pentamethyldiethylenetriamine and 0.05g of tetrabutylammonium hydroxide, heat the reactants to 85°C and stir, slowly add 200g of ethylene oxide and 300g of propylene oxide, keep the temperature and react for 2 hours, cool to room temperature, add acetic acid to neutralize to pH 7, and obtain a multi-branched polyether.

[0028] 30 g of multi-branched polyether, 2.0 g of benzenesulfonic acid, 20 g of ethylene glycol monobutyl ether and 20 g of methanol were mixed uniformly at room temperature to obtain an aged oil demulsifier A.

[0029] Example 2

[0030] Preparation of aged oil demulsifier B: In an autoclave, 2.5 g of diethylenetriamine, 2.5 g of pentamethyldiethylenetriamine and 0.05 g of tetrabutylammonium hydroxide were added, the reactants were heated to 85°C and stirred, 200 g of ethylene oxide and 300 g of propylene oxide were slowly added dropwise, the reaction was kept warm for 2 hours, the temperature was lowered to room temperature, acetic acid was added to neutralize to pH 7, and a multi-branched polyether was obtained.

[0031] 30 g of multi-branched polyether, 2.0 g of ethanesulfonic acid, 20 g of ethylene glycol monobutyl ether and 20 g of methanol were mixed uniformly at room temperature to obtain an aged oil demulsifier B.

[0032] Example 3

[0033] Preparation of aged oil demulsifier C: In an autoclave, 2.5 g of tetraethylene pentamine, 2.5 g of pentamethyldiethylene triamine and 0.05 g of tetrabutylammonium hydroxide were added, the reactants were heated to 85°C and stirred, 200 g of ethylene oxide and 300 g of propylene oxide were slowly added dropwise, the reaction was kept warm for 2 hours, the temperature was lowered to room temperature, acetic acid was added to neutralize to pH 7, and a multi-branched polyether was obtained.

[0034] 30 g of multi-branched polyether, 2.0 g of aminosulfonic acid, 20 g of ethylene glycol monobutyl ether and 20 g of methanol were mixed uniformly at room temperature to obtain an aged oil demulsifier C.

[0035] Performance Testing

[0036] Aged oil demulsifier A / B / C is used to treat aged oil in an FPSO aged oil storage tank in Bohai Oilfield. The demulsifier can destroy the water-in-oil emulsion and achieve oil-water separation. Specifically, the aged oil is heated to a temperature of 80°C through a heat exchanger by a liquid supply pump, and after being uniformly mixed with a 1500mg / L aged oil demulsifier, it enters a conditioning buffer tank for full reaction for 2 hours; the aged oil that has reacted completely in the conditioning buffer tank is transported to a primary centrifuge via a buffer tank liquid supply pump, and a qualified oil phase (water content ≤1.0%) is separated and transported to a designated position on the platform, and the separated slag phase is collected in a mud recovery tank, and the separated water phase enters a secondary separator; after adding 100mg / L cationic polyacrylamide emulsion water clarifier, the water phase entering the secondary separator is subjected to secondary oil removal and slag removal treatment, the separated oil phase medium returns to the conditioning buffer tank, the separated slag phase medium goes to a mud recovery tank, and the water phase medium enters a tertiary water inlet buffer tank; the water phase of the tertiary water inlet buffer tank enters a tertiary water purifier through a pump, and a deep slag removal treatment of the water phase is carried out, and the treated water phase (oil content ≤200ppm) enters a flash tank, and the separated slag phase medium enters a mud collection tank. The first-stage centrifuge, the second-stage separator and the third-stage water purifier are all commercially available horizontal screw centrifuges with a rotation speed of more than 3,000 revolutions. The schematic diagram of the process flow for treating aged oil of the present invention is as follows: Figure 1 The changes of aging oil before and after treatment are shown in Table 1 and Figure 2 shown.

[0037] Table 1 Changes of an aged oil in Bohai Oilfield before and after treatment

[0038]

[0039] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An aged oil demulsifier, characterized in that: The multi-branched polyether demulsifier is composed of a multi-branched polyether, a rapid dispersing aid and a solvent, wherein the mass ratio of the multi-branched polyether, the rapid dispersing aid and the solvent is 30-50:2.0-5.0:45-68; the structural formula of the multi-branched polyether demulsifier is: Among them, in the block polyether, y:x=1:3-5, x=5-40, and n=3.

2. The aged oil demulsifier according to claim 1, characterized in that: The preparation method of the multi-branched polyether demulsifier is as follows: under the catalysis of tetrabutylammonium hydroxide, polyethylene polyamine and ethylene oxide and propylene oxide are subjected to addition reaction, the addition reaction temperature is 80-95°C, the reaction time is 2-5 hours, and then acetic acid is added to neutralize the pH value of the reaction product to 6.0-7.0 to obtain the multi-branched polyether; wherein the mass ratio of polyethylene polyamine, ethylene oxide and propylene oxide is 1-2:30-50:50-80; and the amount of tetrabutylammonium hydroxide used is 1-2% of the mass of the polyethylene polyamine.

3. The aged oil demulsifier according to claim 2, characterized in that: The polyethylene polyamine is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentamethyldiethylenetriamine.

4. The aged oil demulsifier according to claim 1, characterized in that: The rapid dispersing aid is selected from one or more of aminosulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and ethanesulfonic acid.

5. The aged oil demulsifier according to claim 1, characterized in that: The solvent is a mixture of ethylene glycol monobutyl ether and methanol, and the mass ratio of ethylene glycol monobutyl ether to methanol is 1:0.5-3.

6. A method for treating aged oil at sea, characterized in that: The following steps are involved: S1. According to the amount of aged oil, 1000 to 4000 mg / L of the aged oil demulsifier according to any one of claims 1 to 4 is added to the aged oil at 60 to 80 ° C; S2. The mixture obtained in step S1 is transferred to a tempering buffer tank for full reaction for 2 to 10 hours; the aged oil in the tempering buffer tank is transported to the primary centrifuge via the buffer tank booster pump, and the separated oil phase with a water content of ≤1.0% is transported to the designated position of the platform, the separated slag phase is collected in the sludge recovery tank, and the separated water phase is sent to the secondary separator; S3. The water phase entering the secondary separator undergoes secondary oil removal, and 100-200 mg / L of water purifier is added for slag removal treatment. The separated oil phase medium returns to the conditioning buffer tank, the separated slag phase medium enters the sludge recovery tank, and the water phase medium enters the tertiary water inlet buffer tank; S4. The water phase from the tertiary water inlet buffer tank enters the tertiary water purifier through a booster pump for deep deslagging treatment. After treatment, the water phase with oil content ≤ 200ppm is transferred to the water tank, and the slag phase medium is separated and enters the slag phase collection tank.

7. A method for treating marine aged oil according to claim 6, characterized in that: In step S3, the water purifying agent is a cationic polyacrylamide emulsion with a molecular weight of 8 to 10 million and a degree of hydrolysis of 25%.

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