Crude oil dehydration electric field stabilizer and preparation method thereof

Abstract

The invention relates to a crude oil dehydration electric field stabilizer and a preparation method thereof. The crude oil dehydration electric field stabilizer is prepared by mixing 30-50% of an oil-soluble sulfide remover, 5-10% of a metal ion chelating agent, 2-5% of a polyelectrolyte degradation agent, 10-20% of a cross-linked polymer demulsifier and 20-40% of a phase solvent. On the starting point that the oil-soluble sulfide remover can effectively remove ferrous sulfide in an oil phase and a transition layer of a crude oil dehydration system, a plurality of functional components such as metal ion chelating, polyelectrolyte degrading and demulsifying capability strengthening are introduced, so that the oil-soluble sulfide remover can effectively remove ferrous sulfide in the oil phase and the transition layer of the crude oil dehydration system. The composite type crude oil dehydration electric field stabilizer can effectively solve the problems that in the crude oil electric dehydration process, crude oil contains harmful impurities such as ferrous sulfide, polyelectrolyte, metal ions and scale bodies thereof, asphaltene and the like, and influences of the oil-water transition layer are caused. And the dehydration efficiency is influenced by the operation fluctuation of the electric dehydrator and the like.

Description

Technical Field

[0001] The present invention belongs to oilfield chemicals, and particularly relates to an electric field stabilizer for the crude oil electro-dehydration process and a preparation method thereof. Background Art

[0002] In the crude oil gathering and transportation dehydration process of Daqing Oilfield, the electro-dehydration process is generally adopted. The basic principle of the electro-dehydration process is to utilize the physical property that water is a conductor and crude oil is an insulator. The crude oil emulsion is placed in an electric field, and the water droplets in the emulsion deform and coalesce under the action of the electric field to form large water droplets and separate from the oil. The crude oil electro-dehydration process has outstanding advantages such as large throughput and high efficiency and speed.

[0003] With the increasing changes in the oilfield exploitation degree and development means, the development of various chemical floods and the use of crude oil production-increasing chemical agents, the emulsification degree of the crude oil produced liquid has become more and more complex. At the same time, due to the needs of oilfield stable production goals, safety production and environmental protection, the recovery of aged oil has become the norm in oilfield gathering and transportation production. Many adverse factors affecting crude oil electro-dehydration, such as aged oil, ferrous sulfide, chemical agents, polyelectrolytes, metal ions and their scale bodies, colloid, fracturing flowback fluid, etc., bring many drawbacks to the stable operation of the electro-dehydration process in each joint station of Daqing Oilfield, and have an increasingly serious adverse impact on crude oil demulsification and dehydration and the quality of purified oil. The dehydration difficulty of crude oil is also increasing, resulting in the electro-dehydration process and equipment being unable to work properly, often occurring phenomena such as excessive water content in the oil after dehydration, turbid dehydrated sewage, blurred oil-water interface, frequent tripping of the electro-dehydrator and "collapse of the electric field", and even burning out the power supply equipment, seriously affecting the normal operation of the crude oil dehydration system. Furthermore, it leads to quality accidents caused by excessive water content in the exported crude oil, or equipment accidents caused by frequent tripping and burning out of the electro-dehydrator.

[0004] Due to the existence of impurities in the crude oil emulsion, the influence of the oil-water intermediate transition layer is frequently seen in the dehydration systems of each oil production plant in Daqing Oilfield, and the phenomenon of frequent tripping and "collapse of the electric field" of the electro-dehydrator is also common. At present, the main means adopted by each oil production plant to solve this problem are: after the operation of the electro-dehydrator fluctuates or "collapses the electric field", the electro-dehydrator is emptied and refilled with liquid; increasing the dosage of demulsifier in the electro-dehydrator and raising the dehydration temperature; establishing an independent aged oil recovery and treatment system (thermochemical dehydration) to avoid the impact of aged oil on the system, etc. The above methods for dealing with the frequent tripping and "collapse of the electric field" of the electro-dehydrator, because they do not essentially reduce or eliminate the fundamental problem of the frequent tripping and "collapse of the electric field" of the electro-dehydrator. Therefore, they only treat the symptoms but not the root cause, not only with a relatively high management and operation cost, but also with an unsatisfactory treatment effect.

[0005] Therefore, studying the influence of impurities in crude oil emulsions on the stable operation of electro-dehydrators and finding ways to ensure the stability of the dehydration electric field under complex emulsion conditions not only can guarantee the normal operation of dehydration equipment and the quality of exported crude oil, but also can reduce the vicious accumulation of aged oil and improve the quality of discharged water, etc., which has very urgent practical significance. Currently, the common technologies for improving the stable operation of the crude oil dehydration electric field in oilfield applications mainly include: acidification chelation demulsification composite technology, transition layer inhibition demulsifier technology, electro-neutralization regulation technology, etc.:

[0006] 1. Acidification chelation demulsification composite technology, such as the patent No. CN2013105025941 "A method for inhibiting the increase of dehydration current caused by the recovery of contaminated oil in a combined station system". It mainly uses citric acid to react with ferrous sulfide and carbonate in the contaminated oil, quickly releasing iron ions and calcium and magnesium ions. The chelating agent chelates and captures the released iron ions and calcium and magnesium ions, thereby removing the extremely conductive particulate matter adsorbed at the oil-water interface and destroying the rigid interfacial film. Then, the enhanced demulsification of the demulsifier is used to improve the dehydration efficiency. This type of method will have a certain effect on the electro-dehydration treatment of crude oil containing ferrous sulfide, alkali metals, and calcium and magnesium scale. However, due to the use of citric acid, there is a certain corrosion to the dehydration equipment. The hydrogen sulfide gas and carbon dioxide gas generated after acidification will cause the dehydration pressure to increase. The presence of hydrogen sulfide will also lead to secondary pollution of the electro-dehydration system, etc., thus forming new technical problems;

[0007] 2. Transition layer inhibition demulsifier technology, such as the patent No. CN2023104046893 "An oilfield transition layer treatment agent and its preparation method and application" and the patent No. CN2020100919280 "A preparation method of a demulsifier for inhibiting the oil-water intermediate transition layer". It mainly uses a proprietary synthesis method to prepare a demulsifier with the function of inhibiting the oil-water intermediate transition layer, so as to achieve the purpose of reducing the operating current of the electro-dehydrator and improving the crude oil dehydration efficiency. The main function of this type of method is still to strengthen demulsification and inhibit the oil-water intermediate transition layer. There are still certain limitations for the electro-dehydration process of crude oil containing impurities such as ferrous sulfide, polyelectrolytes, metal ions, and their scale;

[0008] 3. Electro-neutralization regulation technology, such as: Bai Yukun, etc. Governance of the instability of the dehydration electric field of weakly alkaline ASP flooding produced liquid based on electro-neutralization method. "Oilfield Chemistry". September 25, 2021. Vol. 38, No. 3. It mainly uses polyaluminum chloride (PAC) as an electro-neutralization regulator to play the electro-neutralization mechanism and electrostatic adsorption mechanism, reduce the electronegativity of the system, weaken the strength of the oil-water interfacial film, and improve the electric field dehydration performance. This type of method is mainly applied to the treatment of the instability of the dehydration electric field of weakly alkaline ASP flooding produced liquid. Whether it can play an effective role in dealing with the abnormal fluctuations of the dehydration electric field of crude oil containing impurities under complex conditions remains to be verified.

[0009] In summary, in order to more effectively solve the technical problems of abnormal operation status of the dehydration electric field in the oilfield gathering and transportation system and ensure the stable operation of the electric field. Through the test and analysis of the internal and external causes of the abnormal fluctuation of the dehydration electric field of crude oil containing impurities, it is of great significance to develop a stabilizer for the crude oil dehydration electric field from the perspectives of removing ferrous sulfide, degrading polyelectrolytes, chelating metal ions, strengthening demulsification and dehydration, and inhibiting the enrichment of the oil-water transition layer. Summary of the Invention

[0010] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a stabilizer for the crude oil dehydration electric field and a preparation method thereof, which are used to solve the technical problems of abnormal operation status of the dehydration electric field in the oilfield gathering and transportation system and ensure the stable operation of the electric field.

[0011] A stabilizer for the crude oil dehydration electric field of the present invention is made of the following components by weight ratio:

[0012] 30-50% of an oil-soluble sulfide remover, 5-10% of a metal ion chelating agent, 2-5% of a polyelectrolyte degrading agent, 10-20% of a crosslinked polymer demulsifier, and 20-40% of a phase solvent.

[0013] As a further improvement of the present invention, the oil-soluble sulfide remover is tetramethylolphosphonium organosulfonate prepared by reacting organic sulfonic acid with tetramethylolphosphonium sulfate or tetramethylolphosphonium hydrochloride, and the proportion is 40%.

[0014] As a further improvement of the present invention, the metal ion chelating agent is sodium glutamate diacetate, and the proportion is 10%.

[0015] As a further improvement of the present invention, the polyelectrolyte degrading agent is an oxidation type degrading agent tert-butyl hydroperoxide, and the proportion is 5%.

[0016] As a further improvement of the present invention, the polyelectrolyte degrading agent is a biological type degrading agent acidic mannanase, and the proportion is 2%.

[0017] As a further improvement of the present invention, the crosslinked polymer demulsifier is prepared by subjecting a phenolic amine resin polyether demulsifier to an end hydroxyl group alkalization reaction and then performing a Williamson etherification reaction with a chlorinated polyether to obtain the crosslinked polymer demulsifier.

[0018] As a further improvement of the present invention, the phase solvent is N,N-dimethylformamide.

[0019] For the above preparation method of the crude oil dehydration electric field stabilizer, a phase solvent and a cross-linked polymer demulsifier are sequentially added to the reaction kettle according to the formula ratio and stirred. After the solution is homogenized, a polyelectrolyte degrading agent and a metal ion chelating agent are continuously added to the reaction kettle and stirred until dissolved. After the solution is homogenized, an oil-soluble sulfide removing agent is finally added to the reaction kettle and stirred continuously to obtain the finished crude oil dehydration electric field stabilizer.

[0020] For the crude oil dehydration electric field stabilizer and its preparation method of the present application, starting from the fact that the oil-soluble sulfide removing agent has strong oil-phase permeability, dispersibility and interfacial activity and can effectively remove ferrous sulfide in the oil phase and transition layer of the crude oil dehydration system, multiple functional components such as metal ion chelation, polyelectrolyte degradation and enhanced demulsification ability are introduced to achieve maximum compression of the oil-water transition layer and effective reduction of the dehydration current, thereby forming a composite crude oil dehydration electric field stabilizer. It can effectively solve the problems that affect the dehydration efficiency such as the operation fluctuation, high current and breakdown of the electric field of the electric dehydrator caused by the harmful impurities such as ferrous sulfide, polyelectrolyte, metal ions and their scale bodies, and asphaltene in the crude oil during the electric dehydration process of the crude oil, and has significant technical significance and application prospects. Specific embodiments

[0021] The crude oil dehydration electric field stabilizer of the present application is based on the publicly disclosed technology with the publication number of "CN118515711A, titled A Preparation Method and Application of an Oil-Soluble Sulfide Removing Agent" and assisted by the publicly disclosed technology with the publication number of "CN112063413A, titled A Cross-Linked Polymer Demulsifier and Its Preparation Method". Starting from the fact that the oil-soluble sulfide removing agent has strong oil-phase permeability, dispersibility and interfacial activity and can effectively remove ferrous sulfide in the oil phase and transition layer of the crude oil dehydration system, multiple functional components such as metal ion chelation, polyelectrolyte degradation and enhanced demulsification ability are introduced to achieve maximum compression of the oil-water transition layer and effective reduction of the dehydration current, thereby forming a composite crude oil dehydration electric field stabilizer.

[0022] The crude oil dehydration electric field stabilizer of the present application is composed of the following components in percentage by weight:

[0023] 30-50% of an oil-soluble sulfide removing agent, 5-10% of a metal ion chelating agent, 2-5% of a polyelectrolyte degrading agent, 10-20% of a cross-linked polymer demulsifier, and 20-40% of a phase solvent;

[0024] Among them:

[0025] (1) The oil-soluble sulfide removing agent has the following general molecular formula:

[0026] [(CH2OH)4P]·SO3-R

[0027] wherein R is: C n H 2n+1 - The alkylbenzene group in the alkylbenzenesulfonic acid molecule with 8 ≤ n ≤ 16. In this application, when n = 12 is preferred, that is, the molecular formula of dodecylbenzenesulfonic acid is C 12 H 25 - C6H4 - SO3H. The preparation method is as follows: Add xylene, dodecylbenzenesulfonic acid and tetrabutylammonium chloride into the reaction kettle in sequence, start stirring and heat up to 40 - 50 °C, then dropwise add a 75% commercial aqueous solution of tetrakis(hydroxymethyl)phosphonium sulfate (or tetrakis(hydroxymethyl)phosphonium hydrochloride) into the reaction kettle. After the dropping is completed, continue the reaction for 2 - 4 hours. The dropping and reaction process are carried out under the condition of a temperature of 40 - 50 °C. After the reaction is completed, heat up to 70 - 80 °C, stop stirring and let it stand for sedimentation for 2 - 4 hours. After the static sedimentation is completed, drain the inorganic acid and water at the bottom, and the upper oil phase part is the oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate. The molar ratio of dodecylbenzenesulfonic acid to tetrakis(hydroxymethyl)phosphonium sulfate (or tetrakis(hydroxymethyl)phosphonium hydrochloride) is 2.5:1, and the solvent xylene in the oil-soluble sulfide remover accounts for 40% of the total mass;

[0028] For the oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate, due to the addition of the lipophilic group of organic sulfonic acid, on the premise of ensuring the complexing ability with ferrous sulfide, its oil phase permeability, dispersibility and interfacial activity are significantly enhanced. It can effectively remove ferrous sulfide in the oil phase and transition layer of the crude oil dehydration system, and the sulfide removal efficiency can reach more than 95%. At the same time, the oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate is also a highly efficient anionic surfactant, which can significantly reduce the surface tension, has excellent oil washing ability, can effectively elute the solid particles in the crude oil emulsion and the oil-water transition layer, reduce its influence on the dehydration electric field, and has great advantages in ensuring the stable operation of the electric field of the crude oil electro-dehydrator;

[0029] The oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate accounts for 30 - 50% by weight percentage in the crude oil dehydration electric field stabilizer described in this application, preferably 40%.

[0030] (2) Metal ion chelating agent disodium glutamate diacetate

[0031] The metal ion chelating agent disodium glutamate diacetate can complex metal ions in the emulsion and transition layer of the crude oil dehydration system through the chelating agent molecule, incorporate the metal ions into the interior of the chelating agent, and form a stable complex. It shows good chelating properties for calcium ions, magnesium ions, iron ions, etc. It has excellent scale inhibition effect and obvious synergistic effect;

[0032] The metal ion chelating agent disodium glutamate diacetate accounts for 5 - 10% by weight percentage in the crude oil dehydration electric field stabilizer described in this application, preferably 10%.

[0033] (3) Polyelectrolyte Degradant

[0034] The polyelectrolyte degradant described in this application is: the oxidizing degradant tert-butyl hydroperoxide or the biological degradant acidic mannanase;

[0035] Among them:

[0036] The oxidizing degradant tert-butyl hydroperoxide is a common organic peroxide. When tert-butyl hydroperoxide decomposes, reactive free radicals are generated, which have outstanding oxidation performance. It can oxidatively degrade polyelectrolytes such as polyacrylamide, colloid, and bacterial residues in the emulsion and transition layer of the crude oil dehydration system, as well as those deposited on the dehydrator electrode, destroy the stable interfacial film formed by them, make the emulsified rigid structure lose stability, release the encapsulated oil droplets, and a large number of the released tiny oil droplets aggregate and coalesce continuously, ultimately achieving the effect of oil-water separation and a stable dehydration electric field;

[0037] The biological degradant acidic mannanase is refined by liquid deep fermentation of excellent strains. It is a kind of hydrolase that can hydrolyze mannan oligosaccharides and mannopolysaccharides (including mannan, galactomannan, glucomannan, etc.) containing β-1,4-mannosidic bonds, and it is a high-quality biological gel breaker. It can effectively degrade polyelectrolytes such as biological glue, colloid, and bacterial residues in the emulsion and transition layer of the crude oil dehydration system, as well as those deposited on the dehydrator electrode;

[0038] The polyelectrolyte degradant accounts for 2-5% by weight percentage in the crude oil dehydration electric field stabilizer described in this application. Preferably, the oxidizing polyelectrolyte degradant tert-butyl hydroperoxide is preferably 5% or the biological polyelectrolyte degradant acidic mannanase is 2%.

[0039] (4) Crosslinked Polymer Demulsifier

[0040] The crosslinked polymer demulsifier described in this application is a prior art. See the published document with the publication number "CN112063413A, titled A Crosslinked Polymer Demulsifier and Its Preparation Method". It is prepared by subjecting the commercial brand PFA8311 phenolic amine resin polyether demulsifier to a terminal hydroxyl group alkalization reaction and then performing a Williamson etherification reaction with chlorinated polyether P50 (degree of polymerization 50) to obtain the crosslinked polymer demulsifier;

[0041] The phenolic amine resin polyether demulsifier with the commercial brand number PFA8311 is selected as the main body for crosslinking. The purpose is that the resin-based demulsifier can promote the movement of asphaltene micelles or aggregates with higher activity towards single molecules with lower activity. Its essence is to solubilize asphaltenes with higher activity. In addition, through the π-bond interaction between aromatic rings, it has a solubilizing effect on asphaltene / resin, reduces the film strength, resulting in a decrease in the emulsion stability and achieving the effect of oil-water separation;

[0042] A crosslinked polymer demulsifier is selected. The purpose is that through the significant increase in the spatial structure and relative molecular mass of the crosslinked polymer demulsifier, a single demulsifying agent molecule can adsorb on the surfaces of multiple droplets simultaneously, increasing the probability of droplet collision and improving the "net capture - flocculation - coalescence" ability of the agent for fine oil-water emulsions, so as to ensure the dehydration effect and the stability of the dehydration electric field of crude oil containing impurities in the electro-dehydration system;

[0043] The crosslinked polymer demulsifier accounts for 10 - 20% by weight percentage in the crude oil dehydration electric field stabilizer described in this application.

[0044] (5) Phase solvent N,N-dimethylformamide

[0045] The phase solvent N,N-dimethylformamide (DMF) has strong molecular polarity and excellent phase solubility in both water and organic solvents, with strong penetration ability. The phase solvent N,N-dimethylformamide not only improves the synergistic homogeneity of the effective components in the product of this application, but also can effectively promote the dispersion and diffusion performance of the crude oil dehydration electric field stabilizer between the water / oil phases, giving full play to the application performance and efficacy of the product of this application;

[0046] The phase solvent N,N-dimethylformamide accounts for 20 - 40% by weight percentage in the crude oil dehydration electric field stabilizer described in this application.

[0047] When preparing the crude oil dehydration electric field stabilizer described in this application: add the phase solvent N,N-dimethylformamide and the crosslinked polymer demulsifier to the reaction kettle in sequence according to the weight ratio, start stirring and dissolve for 20 - 50 minutes; after the solution is homogenized, continue to add the polyelectrolyte degrading agent tert-butyl hydroperoxide or acidic mannanase and the metal ion chelating agent sodium glutamate diacetate to the reaction kettle, continue to stir and dissolve for 20 - 50 minutes. After the solution is homogenized, finally add the oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate to the reaction kettle and continue to stir for 60 minutes to obtain the crude oil dehydration electric field stabilizer product;

[0048] Among them:

[0049] The preparation method of the oil-soluble sulfide remover tetrahydroxymethylphosphonium organic sulfonate can be found in the publicly disclosed patent of Daqing Fujie Chemical Co., Ltd., "A Preparation Method and Application of an Oil-soluble Sulfide Remover" (Publication No.: CN118515711A); the preparation method of the cross-linked polymer demulsifier can be found in the patented patent of Daqing Fujie Chemical Co., Ltd., "A Cross-linked Polymer Demulsifier and Preparation Method" (Patent No.: CN2020108462288). Preferably, the commercial brand PFA8311 phenolic amine resin polyether demulsifier undergoes a terminal hydroxyl group alkalization reaction and then a Williamson etherification reaction with chlorinated polyether P50 (degree of polymerization 50) at a molar ratio of 50:1 to obtain the cross-linked polymer demulsifier.

[0050] Example 1

[0051] Add 350 kg of the phase solvent N,N-dimethylformamide and 100 kg of the cross-linked polymer demulsifier to the stainless steel reactor in sequence, and start stirring and dissolving for 30 minutes; after the solution is homogenized, continue to add 50 kg of the oxidizing polyelectrolyte degrading agent tert-butyl hydroperoxide and 100 kg of the metal ion chelating agent sodium glutamate diacetate to the reactor, and continue stirring and dissolving for 30 minutes; after the solution is homogenized, finally add 400 kg of the oil-soluble sulfide remover tetrahydroxymethylphosphonium organic sulfonate to the reactor and continue stirring for 60 minutes to obtain the product of Example 1 of the crude oil dehydration electric field stabilizer.

[0052] Example 2

[0053] Add 250 kg of the phase solvent N,N-dimethylformamide and 200 kg of the cross-linked polymer demulsifier to the stainless steel reactor in sequence, and start stirring and dissolving for 30 minutes; after the solution is homogenized, continue to add 50 kg of the oxidizing polyelectrolyte degrading agent tert-butyl hydroperoxide and 100 kg of the metal ion chelating agent sodium glutamate diacetate to the reactor, and continue stirring and dissolving for 30 minutes; after the solution is homogenized, finally add 400 kg of the oil-soluble sulfide remover tetrahydroxymethylphosphonium organic sulfonate to the reactor and continue stirring for 60 minutes to obtain the product of Example 2 of the crude oil dehydration electric field stabilizer.

[0054] Example 3

[0055] Add 380 kg of the phase solvent N,N-dimethylformamide and 100 kg of the cross-linked polymer demulsifier to the stainless steel reactor in sequence, and start stirring and dissolving for 30 minutes; after the solution is homogenized, continue to add 20 kg of the biological polyelectrolyte degrading agent acidic mannanase and 100 kg of the metal ion chelating agent sodium glutamate diacetate to the reactor, and continue stirring and dissolving for 30 minutes; after the solution is homogenized, finally add 400 kg of the oil-soluble sulfide remover tetrahydroxymethylphosphonium organic sulfonate to the reactor and continue stirring for 60 minutes to obtain the product of Example 3 of the crude oil dehydration electric field stabilizer.

[0056] Example 4

[0057] Add 280 kg of the phase solvent N,N-dimethylformamide and 200 kg of the cross-linked polymer demulsifier to the stainless steel reactor in sequence, and start stirring and dissolving for 30 minutes; after the solution is homogenized, continue to add 20 kg of the biological polyelectrolyte degrading agent acidic mannanase and 100 kg of the metal ion chelating agent sodium glutamate diacetate to the reactor, and continue stirring and dissolving for 30 minutes; after the solution is homogenized, finally add 400 kg of the oil-soluble sulfide remover tetrakis(hydroxymethyl)phosphonium organic sulfonate to the reactor and continue stirring for 60 minutes to obtain the product of Example 4 of the crude oil dehydration electric field stabilizer.

[0058] The effects of the present invention are further described below:

[0059] 1. Removal experiment of ferrous sulfide

[0060] Prepare a 100 mg / L ferrous sulfide suspension by mixing ferrous sulfate solution and sodium sulfide solution in a chemical equivalent ratio of 1:1. Add 100 mL of the prepared ferrous sulfide suspension to a 100 mL colorimetric tube, and then add 500 ppm of the product of the crude oil dehydration electric field stabilizer of the example. Shake the sample with the drug added and the blank sample parallelly by hand 100 times, then place the colorimetric tube in a constant temperature water bath at 50 °C and let it stand. After 30 min, shake the solution in the colorimetric tube evenly, filter it under normal pressure with a quantitative medium-speed filter paper respectively, use distilled water as the reference sample, and measure the absorbance of the filtered blank sample and the sample with the drug added at a wavelength of 450 nm by a spectrophotometer respectively;

[0061] Repeat the above process to measure the ferrous sulfide removal rates of the products of Examples 1-4 respectively:

[0062] The ferrous sulfide removal rate (%) is calculated according to the following formula:

[0063]

[0064] In the formula: C0 - absorbance of the blank sample;

[0065] C1 - absorbance of the sample with the drug added;

[0066] The experimental results are as follows in the table:

[0067] Project Example 1 Example 2 Example 3 Example 4 Removal rate of ferrous sulfide, % 99.14 99.12 99.15 99.14

[0068] It can be seen from the above experiments that the crude oil dehydration electric field stabilizers in each example all show good ferrous sulfide removal ability.

[0069] 2. Chelation experiment of metal ions

[0070] Determination of calcium ion chelating value:

[0071] Weigh 1.5 g (accurate to 0.01 g) of the product of the crude oil dehydration electric field stabilizer example, place it in a 250 mL beaker, add 100 mL of water, place the beaker on a magnetic stirrer and mix and homogenize. After mixing evenly, add 10 mL of a sodium carbonate solution with a concentration of 20 g / L;

[0072] Insert the electrode into the solution, add a sodium hydroxide solution with a concentration of 40 g / L dropwise until the pH value reaches 11. Lift the electrode, add water to 150 mL, and then insert the electrode again. Titrate with a calcium standard solution, and add a sodium hydroxide solution with a concentration of 40 g / L while titrating to maintain the pH value of the solution at 11. The end point is reached when the turbidity that appears in the solution does not disappear;

[0073] Repeat the above process to measure the calcium ion chelating values of the products of Examples 1-4 respectively;

[0074] The chelating value of calcium ion (mg / g) is calculated according to the following formula:

[0075]

[0076] In the formula: ρ1 - the concentration of the calcium standard solution, mg / mL;

[0077] V1 - the consumed volume of the calcium standard solution, mL;

[0078] m - the mass of the crude oil dehydration electric field stabilizer, g;

[0079] M1 - the molar mass of calcium carbonate, g / mol, M1 = 100.09;

[0080] M2 - the molar mass of calcium, g / mol, M2 = 40.08;

[0081] Determination of the chelating value of iron ion (mg / g):

[0082] Weigh 1.5 g (accurate to 0.01 g) of the product of the crude oil dehydration electric field stabilizer example, transfer it to a 100 mL volumetric flask, add 100 mL of water to make up the volume, and set aside. Accurately pipette 20 mL of the sample solution into a 250 mL conical flask, dilute it to 100 mL with deionized water, add 2 mL of sulfosalicylic acid indicator (5%), and use Fe 3+ titrant solution (0.01 mol / L) for titration until the yellow color turns light red as the titration end point. The titration is carried out in a 60 °C constant temperature water bath;

[0083] Repeat the above process to measure the iron ion chelating values of the products of Examples 1-4 respectively;

[0084] The iron ion chelating value is calculated according to the following formula:

[0085]

[0086] Where: c - Fe 3+ Concentration of the titration solution, mol / L;

[0087] V - Volume of the Fe standard solution consumed in the titration, mL; 3+

[0088] M - Mass of the crude oil dehydration electric field stabilizer, g;

[0089] 56 - Molar mass of iron atom, g / mol;

[0090] The experimental results are as follows in the table:

[0091] Project Example 1 Example 2 Example 3 Example 4 Calcium ion chelating value, mg / g 45.21 45.20 45.22 45.22 Iron ion chelating value, mg / g 63.39 63.35 63.40 63.41

[0092] It can be seen from the above experiments that the crude oil dehydration electric field stabilizers in each example all show good metal ion chelating ability.

[0093] 3. Degradation experiment of polyelectrolyte

[0094] Measure 200 mL of polyacrylamide solution (molecular weight 25 million, concentration 5000 mg / L) with a 250 mL beaker, place the beaker in a constant temperature water bath at 50 °C and let it stand for 6 hours, then use an NDJ digital viscometer to measure the initial viscosity value of the polyacrylamide solution under the condition of 6 r / min;

[0095] Weigh 1.5 g of the product of the crude oil dehydration electric field stabilizer example with a 250 mL beaker, then add polyacrylamide solution (molecular weight 25 million, concentration 5000 mg / L) to make up to 200 mL, fully mix and homogenize, then place the beaker in a constant temperature water bath at 50 °C and let it stand for 6 hours. Then use an NDJ digital viscometer to measure the viscosity value after adding the drug of the polyacrylamide solution under the condition of 6 r / min.

[0096] Repeat the above process to measure the viscosity values after adding the drugs of the products in Examples 1 - 4 respectively;

[0097] The degradation rate (%) of the polyelectrolyte is calculated according to the following formula:

[0098]

[0099] Where: η0 - Initial viscosity value of the polyacrylamide solution;

[0100] η1 - Viscosity value after adding the drug of the polyacrylamide solution;

[0101] Project Example 1 Example 2 Example 3 Example 4 Degradation rate of polyelectrolyte, % 91.53 91.49 84.27 84.24

[0102] ​As can be seen from the above experiments, the crude oil dehydration electric field stabilizers in each example all showed good polyelectrolyte degradation ability, and among them, the oxidative polyelectrolyte degrading agent was superior to the biological polyelectrolyte degrading agent.

[0103] 4. Elution efficiency experiment

[0104] Sieve the quartz sand (80 mesh to 100 mesh, standard sieve 0.18 mm to 0.15 mm), mix it evenly with the free oil containing recovered dirty oil taken from the inlet of the electro-dehydrator of the Xin'nan No. 1-3 Joint Station of the Second Oil Production Plant of the Daqing Oilfield in a mass ratio of 7:1, and then keep it in an oven at a set temperature of 50 °C for more than 48 h for standby;

[0105] In a 100 mL graduated oil-washing bottle, weigh about 15 g of the aged oil-containing quartz sand with a balance, add about 30 mL of an aqueous solution containing 500 ppm of the crude oil dehydration electric field stabilizer, place the oil-washing bottle in a constant temperature oscillating water bath, and oscillate it for 2 h under the conditions of a temperature of 50 °C and an oscillation frequency of 90 times / min. Take out the oil-washing bottle, put it in an oven at 50 °C for 6 hours, and read the volume of the washed-out oil. At the same time, use water instead of the crude oil dehydration electric field stabilizer solution to do a blank experiment;

[0106] Repeat the above process to measure the products of Examples 1-4 respectively.

[0107] The elution efficiency (%) is calculated according to the following formula:

[0108]

[0109] In the formula: m2 - the mass of the oil-containing quartz sand in the dosing group, g;

[0110] m3 - the mass of the oil-containing quartz sand in the blank group, g;

[0111] d - the density of crude oil, 0.8742 g / cm 3 ;

[0112] V2 - the volume of the washed-out oil in the dosing group, mL;

[0113] V3 - the volume of the washed-out oil in the blank group, mL.

[0114] Project Example 1 Example 2 Example 3 Example 4 Elution efficiency, % 14.19 14.27 14.51 14.43

[0115] As can be seen from the above experiments, the crude oil dehydration electric field stabilizers in each example all showed good elution ability.

[0116] 5. Demulsification and dehydration test experiment

[0117] The experimental conditions are as follows:

[0118] Test temperature: 50 °C;

[0119] Experimental equipment: 1925-02A type 6-ounce formula bottle, constant temperature water bath, micro syringe, oil water content measuring device and common instruments;

[0120] Emulsification conditions: Mechanical oscillation with a shaker for 5 minutes;

[0121] Dosage of demulsifier: 500 ppm;

[0122] The experimental process is as follows:

[0123] Take the free oil containing recovered waste oil from the inlet of the electro-dehydrator of the Xin'nan No. 1-3 Combined Station of the Second Oil Production Plant of the Daqing Oilfield, and heat it in a water bath until the specified experimental temperature is reached. After sufficient shaking and homogenization, add 100 g of the experimental oil sample into the formula bottle, and place it in a water bath with a water temperature of 50 °C. After the oil sample temperature reaches 50 °C, immediately add 500 ppm of the crude oil dehydration electric field stabilizer prepared in each example into the formula bottle. Tighten the bottle cap and place it on the shaker for 5 min, then put it back into the constant temperature water bath for static dehydration for 120 min. Record the water separation data at 5 minutes, 15 minutes, 30 minutes, 60 minutes and 120 minutes respectively;

[0124] After 120 min, extract 50% of the upper part of the oil phase for oil water content measurement. The measurement is based on GB / T 8929-2006 Determination of Water Content in Crude Oil (Distillation Method), and at the same time, measure the blank group without adding drugs;

[0125] The experimental results are as follows in the table:

[0126]

[0127]

[0128] It can be seen from the above experiments that the crude oil dehydration electric field stabilizers in each example all show good demulsification and dehydration and transition layer compression capabilities.

[0129] 6. Experimental method for measuring the reduction rate of the transition layer

[0130] Take the free oil containing recovered waste oil from the inlet of the electro-dehydrator of the Xin'nan No. 1-3 Combined Station of the Second Oil Production Plant of the Daqing Oilfield, and heat it in a water bath until the specified experimental temperature is reached. After sufficient shaking and homogenization, add 100 g of the experimental oil sample into a 1925-02A type 6-ounce covered transparent graduated glass formula bottle, and place it in a water bath with a water temperature of 50 °C. After the oil sample temperature reaches 50 °C, immediately add 500 ppm of the crude oil dehydration electric field stabilizer prepared in each example into the formula bottle. Tighten the bottle cap and place it on the shaker for 5 min, then put it back into the constant temperature water bath and let it stand for 60 min. At the same time, measure the blank group without adding drugs.

[0131] The method for recording the volume of the oil-water transition layer is to measure the outer wall of the formula bottle from the left side to the right side of the front. Six reading points are set at intervals of 1 cm, 1.5 cm, 1.5 cm, 1.5 cm, and 1 cm. At the six reading points, the maximum thickness of the oil-water transition layer in the plane perpendicular to the outer surface of the formula bottle is read, and its average value is substituted into the following formula to calculate the volume of the oil-water transition layer after adding the drug;

[0132] The volume of the oil-water transition layer (mL) is calculated according to the following formula:

[0133] Volume of oil-water transition layer = 0.1 × 17.86 × H 平均

[0134] In the formula: 17.86 - Inner cross-sectional area of the glass formula bottle, cm 2 ;

[0135] H 平均 - Average thickness of the oil-water transition layer, mm.

[0136] The reduction rate of the transition layer (%) is calculated according to the following formula:

[0137]

[0138] In the formula: V 过1 - Volume of the transition layer after adding the drug;

[0139] V 过2 - Volume of the blank transition layer;

[0140] The experimental results are as follows in the table:

[0141] Project Example 1 Example 2 Example 3 Example 4 Reduction rate of transition layer, % 54.12 62.03 52.91 58.72

[0142] It can be seen from the above experiments that the crude oil dehydration electric field stabilizers in each example all show good ability to reduce the transition layer.

[0143] 7. Dehydration current reduction rate experiment

[0144] The free oil at the inlet of the electric dehydrator containing recycled waste oil from the Xin'nan No. 1-3 Joint Station of the Second Oil Production Plant of Daqing Oilfield is used as the experimental medium. Through experiments, it is tested that the experimental medium contains 68.86% oil, 31.14% water, and the ferrous sulfide content is 35.54 mg / L;

[0145] Add 3000 g of the experimental medium to the dehydration tank of the DWY-8 full-automatic crude oil electric dehydrator, and at the same time add 500 ppm of the product of the example of the pre-tested crude oil dehydration electric field stabilizer. Seal the dehydration tank of the DWY-8 full-automatic crude oil electric dehydrator, and turn on the power switch on the panel of the DWY-8 full-automatic crude oil electric dehydrator. Set the stirring speed to 300 revolutions per minute through the program, and set the temperature to 50 ± 1 °C. After the temperature is constant, continue to stir for 10 minutes;

[0146] After 10 minutes of stirring, stop the stirring. Set the dehydration voltage to 2000 V through the program, set the dehydration duration to 30 minutes, and start the electro-dehydration process. Record the dehydration current values at 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, and 30 minutes respectively, and calculate the arithmetic mean of the six time points as the average current value A1 after adding the drug;

[0147] Repeat the above process. Measure the average current value A1 after adding the products of Examples 1-4 respectively. And conduct a blank experiment to measure the average current value A2 of the blank sample;

[0148] The dehydration current reduction rate (%) is calculated according to the following formula:

[0149]

[0150] In the formula: A1 - the average current after adding the drug;

[0151] A2 - the average current of the blank sample;

[0152] The experimental results are as follows in the table:

[0153] Project Example 1 Example 2 Example 3 Example 4 Reduction rate of dehydration current, % 52.37 54.25 50.03 51.69

[0154] It can be seen from the above experiments that the crude oil dehydration electric field stabilizers in each example all show good dehydration current reduction ability.

Claims

1. A crude oil dehydration electric field stabilizer, characterized in that: It is made of the following components by weight: 30-50% of oil-soluble sulfide remover, 5-10% of metal ion chelating agent, 2-5% of polyelectrolyte degradation agent, 10-20% of cross-linked polymer demulsifier, and 20-40% of compatibilizing agent.

2. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The oil-soluble sulfide remover is prepared by reacting organic sulfonic acid with tetrakis hydroxymethyl phosphonium sulfate or tetrakis hydroxymethyl phosphonium hydrochloride to obtain tetrakis hydroxymethyl phosphonium organic sulfonate, which accounts for 40%.

3. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The metal ion chelating agent is glutamic acid diacetic acid sodium salt, accounting for 10%.

4. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The polyelectrolyte degradation agent is an oxidative degradation agent tert-butyl hydroperoxide, accounting for 5%.

5. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The polyelectrolyte degradation agent is a biological degradation agent acid mannanase, accounting for 2%.

6. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The cross-linked polymer demulsifier is prepared by subjecting the phenolamine resin polyether demulsifier to a terminal hydroxyl alkalization reaction and then to a Williamson etherification reaction with a chlorinated polyether.

7. The crude oil dehydration electric field stabilizer according to claim 1, characterized in that The phase solvent is N,N-dimethylformamide.

8. A method for preparing a crude oil dehydration electric field stabilizer according to any one of claims 1 to 7, characterized in that: Add the phase solvent and the cross-linked polymer demulsifier to the reactor in sequence according to the formula ratio and stir. After the solution is homogenized, continue to add the polyelectrolyte degradation agent and the metal ion chelating agent to the reactor and continue to stir and dissolve. After the solution is homogenized, finally add the oil-soluble sulfide remover to the reactor and continue to stir to obtain the finished crude oil dehydration electric field stabilizer.

Images