Capsule solid corrosion inhibitor

Abstract

The invention relates to a capsule solid corrosion inhibitor, and belongs to the technical field of oil field corrosion and protection. The solid corrosion inhibitor capsule provided by the invention comprises nanocapsule corrosion inhibitor powder prepared by the following steps: carrying out polymerization reaction of polymeric monomers in a mixed acidic dispersion liquid of halloysite nanotubes and a poly-positive electrolyte, carrying out solid-liquid separation, and washing the solid to be neutral to obtain a halloysite / poly-positive electrolyte composite material; dispersing the composite material and the corrosion inhibitor in a good solvent of the corrosion inhibitor, and then carrying out solid-liquid separation to obtain a nano composite material; and dispersing the nano composite material and the ionized polyacid electrolyte with negative charges in a good solvent of the polyacid electrolyte, washing and drying. When the nanocapsule corrosion inhibitor powder adopted by the capsule solid corrosion inhibitor is prepared, the corrosion inhibitor is wrapped in a nanotube cavity and a polyelectrolyte multilayer film through layer-by-layer self-assembly of a polypositive electrolyte, the corrosion inhibitor and a polyacid electrolyte, so that long-acting release and stable release of the corrosion inhibitor are realized, and the slow release effect of the corrosion inhibitor is enhanced.

Description

Technical Field

[0001] The invention relates to a capsule solid corrosion inhibitor, belonging to the technical field of oil field corrosion and protection. Background Art

[0002] The output fluid of Zhongyuan Oilfield has the characteristics of "four highs and one low", namely, Cl - High content and high mineralization (5-20)×10 4 mg / L, HCO 3 - It has the characteristics of high content, high bottom hole temperature (80-110℃), and low pH value (about 6.0), and is highly corrosive, which is manifested as wear corrosion, pitting corrosion and other local corrosion of oil well pipes, and frequent wells, affecting normal oil and gas production. Among the many anti-corrosion measures, the traditional solution is to add liquid corrosion inhibitors, but there are the following problems: 1) The intermittent injection of liquid corrosion inhibitors is uneven and the effect is unstable; 2) It is easy to adhere to the wall of the oil pipe and it is difficult to reach the bottom of the well, resulting in low efficiency; 3) For some wells with large water production, high water level wells, remote wells and wells with packers, the use of liquid corrosion inhibitors is inconvenient.

[0003] In recent years, oil fields have tried to add solid corrosion inhibitors to oil wells to solve the shortcomings of the anti-corrosion effect of adding liquid corrosion inhibitors, and to achieve the purpose of effectively protecting the parts below the oil pump (from the oil layer to the oil pump section casing) and the bottom of the oil well where there are anti-corrosion dead corners. At present, most solid corrosion inhibitors usually use a binder to mix the corrosion inhibition component with a synergist, a weighting agent and other agents, and are prepared by high-temperature melting, adsorption or gluing. However, this type of solid corrosion inhibitor has uneven release rate, almost no release before the agent disintegrates, and it is quickly completely dissolved after disintegration, the release cycle is short, and the slow-release performance is poor. For example, the Chinese patent application document with application publication number CN105295880A discloses a method of using hydrochloric acid adamantane as the main material and gelatinized starch as the auxiliary material. The main material and the auxiliary material are heated and stirred according to the formula ratio, mixed evenly, pressed and formed in a mold, and cooled to obtain a slow-release solid corrosion inhibitor for oil wells. The various components of the corrosion inhibitor are green and environmentally friendly, non-toxic and harmless to the environment and organisms, and the preparation and delivery process are simple. It only takes one loading tool to add the solid corrosion inhibitor to the bottom of the well or other suitable locations at one time, and the effective ingredients of the corrosion inhibitor can be slowly released with the flowing liquid, but the solid slow-release agent has a short slow-release period, and is completely released in only 60 hours. For another example, the Chinese patent application document with application publication number CN111154470A discloses a solid corrosion inhibitor for oil wells that can effectively protect the oil layer to the casing of the oil pump section. In order to enhance the slow-release effect, the corrosion inhibitor is firstly mixed with a composite corrosion inhibitor, an organic filler, a functional weighting agent and an adhesive to obtain solid particles by injection molding, and then a hydrophobic coating material is added, and the mixture is physically stirred and mixed to obtain a slow-release solid corrosion inhibitor. However, the hydrophobic coating material in the corrosion inhibitor has poor coating properties on solid particles. When the solid corrosion inhibitor sinks from the wellhead to the bottom of the well, the weak interaction force between the coating shell and the solid particles is relatively small, resulting in premature release of the corrosion inhibitor, and the slow-release effect is not ideal.

[0004] In order to improve the corrosion inhibition effect of solid corrosion inhibitors, the corrosion inhibitors and their synergists are made into capsules or dressings through physical coating to form drug-depot-type capsules, so as to effectively encapsulate the corrosion inhibitors and other active components to prevent the volatilization and oxidation of the active components, thereby improving the slow release performance of the corrosion inhibitors. As in the prior art, a Chinese invention patent application with application publication number CN110591680A discloses a method for preparing a controlled release capsule corrosion inhibitor, which comprises the following steps: S001: mixing a corrosion inhibitor solution with a natural halloysite nanotube carrier in a reactor to obtain a mixture A; S002: adding the mixture A to a polyvinyl alcohol (PVA) solution to obtain a mixture B; S003: extruding and cutting the mixture B into round granular capsules in a granulator; S004: adding N,N-dimethylacetamide to an octadecyl acrylate solution, stirring to obtain a corrosion-sensitive polymer; S005: emulsifying the corrosion-sensitive polymer and spraying it evenly on the capsule surface to form an outer wall shell layer, and drying the capsule in a vacuum drying oven to form a final product. The capsule corrosion inhibitor can be selectively released according to the corrosive environment, thereby extending the protection time of the corrosion inhibitor. However, since the corrosion inhibitor molecules are only loaded in the nanotube carrier by physical adsorption, the encapsulation effect of the corrosion inhibitor is poor. When the capsule is exposed to the surrounding environment, the corrosion inhibitor may experience an initial burst release and cannot be released in a long-term and stable manner. Summary of the invention

[0005] The purpose of the present invention is to provide a capsule solid corrosion inhibitor which can release the corrosion inhibitor for a long time and stably.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A capsule solid corrosion inhibitor includes nano capsule corrosion inhibitor powder; a method for preparing the nano capsule corrosion inhibitor powder includes the following steps:

[0008] 1) providing a mixed acidic dispersion of halloysite nanotubes and polymerizable monomers of a polycationic electrolyte; carrying out a polymerization reaction of the polymerizable monomers in the mixed acidic dispersion, performing solid-liquid separation after the polymerization reaction is completed, and washing the obtained solid to neutrality to obtain a halloysite / polycationic electrolyte composite material;

[0009] 2) dispersing the obtained halloysite / polycationic electrolyte composite material and the corrosion inhibitor in a good solvent of the corrosion inhibitor, and performing solid-liquid separation to obtain a nanocomposite material loaded with the corrosion inhibitor;

[0010] 3) The obtained nanocomposite material loaded with corrosion inhibitor and the polyacid electrolyte with negative charge after ionization are dispersed in a good solvent of the polyacid electrolyte, and then washed and dried to obtain the product.

[0011] The nano-capsule corrosion inhibitor powder used in the capsule solid corrosion inhibitor of the present invention is prepared by using the halloysite nanotube with a unique hollow tubular structure as a good corrosion inhibitor slow-release carrier, the in-situ polymerization reaction of the polymerized monomer of the polypositive electrolyte and the electrostatic action form a conductive polymer chain on the surface of the halloysite, the corrosion inhibitor molecules are filled in the lumen of the halloysite and between the molecular chains and chain ends of the polypositive electrolyte by adsorption, and the polynegative electrolytes such as polyacids encapsulate the halloysite / polypositive electrolyte composite material loaded with the corrosion inhibitor by electrostatic action, and the process is through the self-assembly of the polypositive electrolyte, the corrosion inhibitor and the polyacid electrolyte layer by layer, the corrosion inhibitor is wrapped in the nanotube lumen and the polyelectrolyte multilayer film, and finally forms a nanocapsule. Since a large amount of corrosion inhibitor is encapsulated in the lumen of the halloysite and the interlayer shell of the polypositive electrolyte and the polyacid electrolyte, it is possible to overcome the difficult problems such as the easy loss of effective anti-corrosion components and the occurrence of explosive release when the solid corrosion inhibitor is in a corrosive environment, thereby achieving the long-term release and stable release of the corrosion inhibitor, and strengthening the slow-release effect of the corrosion inhibitor.

[0012] When preparing the nanocapsule corrosion inhibitor powder used in the present invention, the carrier halloysite nanotubes (HNTs) used have a hollow nanotube structure with open ends, the inner and outer surfaces are respectively positively charged and negatively charged, the tube diameter is large, the specific surface area is high, and the adsorption performance is good, which is very suitable as a corrosion inhibitor carrier. In addition, halloysite has a wide source, low price, non-toxic and harmless to the environment, and surface modifiable and other excellent properties, making it an ideal corrosion inhibitor slow-release carrier material. In addition, halloysite nanotubes are a natural clay mineral material that can play the role of a weighting agent, greatly improving the sedimentation performance of the capsule solid corrosion inhibitor using the nanocapsule corrosion inhibitor powder, and providing important support for the corrosion inhibitor to settle to the bottom of the oil well.

[0013] The halloysite nanotubes may be unactivated halloysite nanotubes or activated halloysite nanotubes. Further, the halloysite nanotubes are halloysite nanotubes activated by acid or alkali. The use of acid or alkali to activate the halloysite nanotubes can make the inner and outer surfaces of the halloysite nanotubes present more positive and negative charges, respectively, thereby increasing the activity of the inner and outer surfaces of the halloysite nanotubes, achieving a layer-by-layer self-assembly process, in which more corrosion inhibitors are captured in the shells between the polycationic electrolytes and polyacids and other polynegative electrolyte layers, while allowing more corrosion inhibitors to enter the lumen of the halloysite nanotubes, thereby increasing the loading amount of the corrosion inhibitors.

[0014] It is understandable that after dispersing the halloysite nanotube raw material in an acid solution or an alkali solution, heating and stirring at 50-70 °C, washing to neutrality, drying and grinding, the halloysite nanotubes activated by acid or alkali are obtained. The volume of the acid solution or alkali solution corresponding to each 1 g of the halloysite nanotube raw material is 10-15 mL. The temperature of the heating and stirring is preferably 60 °C. The time of the heating and stirring is preferably 4-8 h, such as 6 h or 8 h. The acid solution is preferably sulfuric acid with a concentration preferably of 1 mol / L; the alkali solution is preferably sodium hydroxide solution with a concentration preferably of 1 mol / L.

[0015] Furthermore, the length of the halloysite nanotube raw material is 500-1000 nm.

[0016] Furthermore, the mixed acidic dispersion liquid is obtained by adding the activated halloysite nanotubes into hydrochloric acid with a concentration of 1-1.5 mol / L, mixing evenly, and then adding a polymerization monomer and mixing evenly. For example, the concentration of the hydrochloric acid is 1 mol / L. The volume of the hydrochloric acid corresponding to each 1.5-4 g of the activated halloysite nanotubes is 80 mL.

[0017] It is understandable that in the present invention, the polycationic electrolyte refers to a conductive polymer with a positive charge after being doped with a protonic acid as a dopant. The polycationic electrolyte is usually synthesized by chemically oxidizing and polymerizing a polymerization monomer with a water-soluble initiator in an acidic medium. When the conductive polymer is synthesized in an acidic medium and doped with a protonic acid at the same time, the polymer can obtain a higher conductivity, so that the nano-capsule corrosion inhibitor powder forms a conductive wireless network, which can rapidly transfer electrons, enabling the electrode to rapidly form an oxide film on the metal surface during operation, thereby improving the corrosion protection performance of the nano-capsule corrosion inhibitor powder.

[0018] Furthermore, in step 1), the mass ratio of the halloysite nanotubes to the polymerization monomer is 0.6-2:1, preferably 0.9:1. When the mass ratio of the halloysite nanotubes to the polymerization monomer is controlled within the above range, the halloysite / polycationic electrolyte composite material generated by the reaction has good conductivity, so that the nano-capsule corrosion inhibitor powder forms a conductive wireless network, which can rapidly transfer electrons, enabling the electrode to rapidly form an oxide film on the metal surface during operation, thereby improving the corrosion protection performance of the nano-capsule corrosion inhibitor powder. The polymerization monomer is one or any combination of aniline, pyrrole, and thiophene. When one or any combination of aniline, pyrrole, and thiophene is used as the polymerization monomer, the molecular structure of the conductive polymer in the polycationic electrolyte introduced into the nano-capsule contains a large conjugated π-bond structure, and the redox potential is higher than that of metallic iron. In a corrosive environment, the polycationic electrolyte reacts with iron in contact with each other, forming a dense oxide film on the metal surface, having a good corrosion inhibition effect and improving the corrosion resistance of the solid corrosion inhibitor.

[0019] Further, in step 1), the temperature of the polymerization reaction is 0-5°C, and the time is 6-8h, for example, 8h. Polymerization at low temperature (0-5°C) is beneficial to increase the molecular weight of the polymer and make the molecular weight distribution of the polymer narrower. Controlling the polymerization time to 6-8h can enable the synthesized conductive polymer to obtain the best conductivity. Beyond this time range, the conductivity will decrease significantly. The polymerization reaction is carried out in an acidic environment. Further, the polymerization reaction is initiated by an oxidant, and the oxidant is preferably ammonium persulfate. The mass ratio of the polymerized monomer to the oxidant is 1:2-4, for example, 1:2. Since the polymerization reaction initiated by ammonium persulfate is an exothermic reaction, in order to control the reaction temperature, further, the oxidant is added dropwise to the mixed acidic dispersion.

[0020] Further, the corrosion inhibitor is a benzothiazole corrosion inhibitor and / or a benzimidazole corrosion inhibitor. The benzothiazole corrosion inhibitor and the benzimidazole corrosion inhibitor are both typical N-containing heterocyclic corrosion inhibitors. The special molecular structure makes them have a strong adsorption effect and form a stable complex or chelate, and it is very easy to form a large number of hydrogen bonds between molecules to thicken the adsorption and inhibit the corrosion process of the metal. This type of corrosion inhibitor has the advantages of multiple functions, high effectiveness, strong adaptability, and low toxicity. The benzothiazole corrosion inhibitor is preferably 2-mercaptobenzothiazole. The benzimidazole corrosion inhibitor is preferably 2-mercaptobenzimidazole. Further, in step 2), the mass ratio of the halloysite / polypositive electrolyte composite material and the corrosion inhibitor is 1:1.5~2, for example, 1:1.5. The volume of the good solvent of the corrosion inhibitor used for each 1g of halloysite / polypositive electrolyte composite material is 10~30mL, for example, 15~30mL. The dosage of the halloysite / polypositive electrolyte composite material, the corrosion inhibitor, and the good solvent of the corrosion inhibitor is controlled within the above range so that the corrosion inhibitor molecules can be adsorbed and filled in the lumen of the halloysite and between the molecular chains and chain ends of the polypositive electrolyte in the largest proportion. In step 2), the good solvent is ethanol and / or acetone. Ethanol and acetone are commonly used, low-toxic, and economical organic solvents, and they can fully disperse the halloysite / polypositive electrolyte composite material powder.

[0021] In order to further increase the loading amount of the corrosion inhibitor in the nanocapsule corrosion inhibitor powder, in step 2), the dispersion is carried out under ultrasonic conditions, and the ultrasonic time is preferably 30 to 60 minutes, for example, 40 minutes.

[0022] The encapsulation of the polyacid electrolyte is carried out in a good solvent of the polyacid electrolyte. Further, in step 3), the good solvent is an alcohol solvent, such as ethanol. The alcohol solvent can fully disperse the nanocomposite powder loaded with the corrosion inhibitor molecules in the polyacid electrolyte.

[0023] Furthermore, in step 3), the polyacid electrolyte is one or any combination of polyacrylic acid, polymethacrylic acid, and polystyrene sulfonic acid. The mass ratio of the polyacid electrolyte to the nanocomposite material loaded with the corrosion inhibitor is 0.5 to 1:1, for example, 0.6:1. The polyacid electrolyte carries a negative charge after ionization, and can be adsorbed by the polypositive electrolyte through electrostatic adsorption, so that the corrosion inhibitor molecules are wrapped between the polypositive and negative electrolyte layers.

[0024] Furthermore, in step 3), the dispersion is carried out under stirring conditions, and the stirring time is 40 to 60 minutes, for example, 60 minutes.

[0025] The capsule solid corrosion inhibitor of the present invention adopts the physical barrier effect of the structure of the nano-capsule corrosion inhibitor powder, the corrosion inhibition effect of the polycationic electrolyte, and the release adsorption corrosion inhibition effect of the corrosion inhibitor molecules, which are all conducive to the long-term release of the capsule solid corrosion inhibitor. The capsule solid corrosion inhibitor of the present invention has a large density and good sedimentation performance. When corrosion occurs during the process of sinking from the wellhead to the bottom of the well, the unique capsule structure of the nano-capsule corrosion inhibitor powder can gradually release the corrosion inhibitor during the sedimentation process of the nano-capsule solid corrosion inhibitor (it can still be released when it reaches the bottom), effectively preventing the corrosion inhibition components from being easily lost and the occurrence of explosive release, thereby achieving the long-term release of the solid corrosion inhibitor, thereby effectively protecting the equipment from top to bottom of the oil well and extending the service life of the oil well pipe material. In addition, compared with the prior art, the capsule solid corrosion inhibitor of the present invention does not require the addition of chemical raw materials such as weighting agents during preparation, is environmentally friendly, and has high comprehensive benefits.

[0026] In order to further improve the sustained-release performance of the capsule corrosion inhibitor, the capsule solid sustained-release agent also includes a synergist, a binder and a curing agent; the mass ratio of the nanocapsule corrosion inhibitor powder, the synergist, the binder and the curing agent is 20-50:7-20:10-25:6-20, preferably 20-45:7-15:10-20:6-20.

[0027] Furthermore, the capsule solid corrosion inhibitor is obtained by uniformly mixing nanocapsule corrosion inhibitor powder, synergist, adhesive and curing agent and then granulating. The solid corrosion inhibitor obtained by molding and granulation has high drug loading and encapsulation rate, slow dissolution, and can effectively slow down the explosive release phenomenon of the drug in the early stage of use, and has a good sustained release effect. Furthermore, the capsule solid corrosion inhibitor obtained by granulation has a length of 5 to 10 mm, a diameter of ≤5 mm, and a density of 1.5 to 1.9 g / cm 3 Granular finished product.

[0028] Furthermore, the synergist is potassium iodide and / or thiourea. Potassium iodide and thiourea can enhance the corrosion resistance of the nanocapsule corrosion inhibitor powder by producing adsorption behavior on the metal surface. The adhesive is one or any combination of epoxy resin, phenolic resin, and sodium carboxymethyl cellulose. The curing agent is polyamide resin and / or hydroxyethylethylenediamine. Polyamide resin and hydroxyethylethylenediamine react with epoxy groups and hydroxyl groups in the adhesive molecules through amines to form amine oxides and new covalent bonds. This reaction is irreversible, thereby forming a cross-linked structure between the resin molecules to achieve the purpose of curing.

[0029] Furthermore, the mixing of the nanocapsule corrosion inhibitor powder, the synergist, the binder and the curing agent is carried out at 90-120°C, for example, at 110°C.

[0030] The capsule solid corrosion inhibitor based on halloysite nanotubes of the present invention is a sustained-release solid corrosion inhibitor with excellent performance, which can be used for pipeline corrosion protection and wellbore corrosion protection, and is particularly suitable for use in oil wells with complex and harsh corrosion conditions. The solid corrosion inhibitor has a large corrosion inhibitor loading capacity, good sedimentation performance, and can sink to the bottom of the well or other suitable positions, and can release corrosion-inhibiting components evenly and slowly. It has the advantages of low dosage, long release period, and high corrosion inhibition efficiency, high use value, and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the synthesis route of the nanocapsule corrosion inhibitor powder in Examples 1 to 4. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0033] The raw materials of halloysite nanotubes used in each embodiment are commercially available products purchased from Lingshou County Yanbo Mineral Products Processing Co., Ltd., with a purity greater than 60% and a nanotube length of 500-1000nm; the aniline, pyrrole and thiophene used are all analytically pure and vacuum distilled before use.

[0034] Example 1

[0035] The preparation method of the nanocapsule corrosion inhibitor powder of this embodiment comprises the following steps:

[0036] 1) 5 g of the halloysite nanotube raw material was dispersed in 50 mL of 1 mol / L sulfuric acid, heated and stirred at 60° C. for 8 h, then centrifuged and washed with deionized water until the supernatant and HNTs particles were neutral, dried at 60° C., and ground into powder after complete drying to obtain activated HNTs for standby use.

[0037] 2) 2 g of activated HNTs were added to 80 mL of 1 mol / L hydrochloric acid, and after stirring evenly, aniline monomer was added, the mass ratio of activated HNTs to aniline was 0.9:1, and the mixed solution was ultrasonically treated for 30 minutes, and then, at 0-5°C, an oxidant ammonium persulfate solution was added dropwise, the mass ratio of aniline monomer to ammonium persulfate was 1:2. After reacting for 8 hours, the mixture was centrifuged and washed several times with deionized water and anhydrous ethanol until the supernatant was neutral, and then dried at 60°C to obtain a halloysite / polyaniline composite material powder.

[0038] 3) 1.0 g of the prepared halloysite / polyaniline composite powder was dispersed in 30 mL of ethanol, ultrasonically dispersed for 25 min, and a corrosion inhibitor, 2-mercaptobenzothiazole (MBT), was added. The mass ratio of the halloysite / polyaniline composite powder to the corrosion inhibitor was 1:1.5. The ultrasonic treatment was continued for 40 min, and the mixture was repeatedly centrifuged, washed, and dried with ethanol to obtain a nanocomposite powder loaded with a corrosion inhibitor.

[0039] 4) 0.2 g of the corrosion inhibitor-loaded nanocomposite powder was dispersed in 30 mL of ethanol, and ultrasonically treated for 30 min. 100 mL of an ethanol solution of polyacrylic acid with a mass concentration of 2 mg / mL was added, and stirring was continued for 60 min. Then, the powder was centrifuged and washed with ethanol and dried to obtain nanocapsules loaded with corrosion inhibitor using halloysite as a carrier.

[0040] Example 2

[0041] The preparation method of the nanocapsule corrosion inhibitor powder of this embodiment comprises the following steps:

[0042] 1) 3 g of halloysite nanotube raw material was dispersed in 30 mL of 1 mol / L NaOH solution, heated and stirred at 60° C. for 8 h, then centrifuged and washed with deionized water until the supernatant and HNTs particles were neutral, dried at 60° C., and ground into powder after complete drying to obtain activated HNTs for standby use.

[0043] 2) 1.5 g of activated HNTs were added to 80 mL of 1 mol / L hydrochloric acid, and after stirring evenly, pyrrole monomer was added, the mass ratio of activated HNTs to pyrrole was 0.9:1, and the mixed solution was ultrasonically treated for 30 minutes, and then, at 0-5°C, ammonium persulfate solution was added dropwise, the mass ratio of pyrrole monomer to ammonium persulfate was 1:2. After reacting for 8 hours, the mixture was centrifuged and washed several times with deionized water and anhydrous ethanol until the supernatant was neutral, and then dried at 60°C to obtain a halloysite / polypyrrole composite material powder.

[0044] 3) 1 g of the prepared halloysite / polypyrrole composite powder was dispersed in 20 mL of ethanol, ultrasonically dispersed for 25 min, and corrosion inhibitor 2-mercaptobenzothiazole (MBT) was added, the mass ratio of halloysite / polypyrrole composite powder to corrosion inhibitor was 1:1.5, and ultrasonic treatment was continued for 40 min, and repeatedly centrifuged, washed and dried with ethanol to obtain a nanocomposite powder loaded with corrosion inhibitor.

[0045] 4) 0.3 g of the corrosion inhibitor-loaded nanocomposite powder was dispersed in 50 mL of ethanol, subjected to ultrasonic treatment for 30 min, 90 mL of ethanol solution of polymethacrylic acid with a mass concentration of 2 mg / mL was added, and stirring was continued for 60 min, followed by ethanol centrifugal washing and drying to obtain nanocapsules loaded with corrosion inhibitor using halloysite as a carrier.

[0046] Example 3

[0047] The preparation method of the nanocapsule corrosion inhibitor powder of this embodiment comprises the following steps:

[0048] 1) 8 g of the halloysite nanotube raw material was dispersed in 120 mL of 1 mol / L sulfuric acid, heated and stirred at 60° C. for 8 h, then centrifuged and washed with deionized water until the supernatant and HNTs particles were neutral, dried at 60° C., and ground into powder after complete drying to obtain activated HNTs for standby use.

[0049] 2) 4 g of activated HNTs were added to 80 mL of 1 mol / L hydrochloric acid, and after stirring evenly, thiophene monomer was added, the mass ratio of activated HNTs to thiophene was 0.9:1, and the mixed solution was ultrasonically treated for 30 minutes, and then, at 0-5°C, ammonium persulfate solution was added dropwise, the mass ratio of thiophene monomer to ammonium persulfate was 1:2. After reacting for 8 hours, the mixture was centrifuged and washed several times with deionized water and anhydrous ethanol until the supernatant was neutral, and then dried at 60°C to obtain a halloysite / polythiophene composite material powder.

[0050] 3) 2 g of the prepared halloysite / polythiophene composite powder was dispersed in 60 mL of ethanol, ultrasonically dispersed for 25 min, and a corrosion inhibitor 2-mercaptobenzothiazole (MBT) was added, the mass ratio of the halloysite / polythiophene composite powder to the corrosion inhibitor was 1:1.5, and the ultrasonic treatment was continued for 40 min, and the mixture was repeatedly centrifuged, washed, and dried with ethanol to obtain a nanocomposite powder loaded with a corrosion inhibitor.

[0051] 4) 0.5 g of the corrosion inhibitor-loaded nanocomposite powder was dispersed in 75 mL of ethanol, subjected to ultrasonic treatment for 30 min, 150 mL of an ethanol solution of polymethacrylic acid with a mass concentration of 2 mg / mL was added, and stirring was continued for 60 min, followed by ethanol centrifugal washing and drying to obtain nanocapsules loaded with corrosion inhibitor using halloysite as a carrier.

[0052] Example 4

[0053] The preparation method of the nanocapsule corrosion inhibitor powder of this embodiment comprises the following steps:

[0054] 1) 5 g of the halloysite nanotube raw material was dispersed in 75 mL of 1 mol / L NaOH solution, heated and stirred at 60° C. for 8 h, then centrifuged and washed with deionized water until the supernatant and HNTs particles were neutral, dried at 60° C., and ground into powder after complete drying to obtain activated HNTs for standby use.

[0055] 2) 3 g of activated HNTs were added to 80 mL of 1 mol / L hydrochloric acid, and after stirring evenly, aniline monomer was added, the mass ratio of activated HNTs to aniline was 0.9:1, and the mixed solution was ultrasonically treated for 30 minutes, and then, at 0-5°C, ammonium persulfate solution was added dropwise, the mass ratio of aniline monomer to ammonium persulfate was 1:2. After reacting for 8 hours, the mixture was centrifuged and washed several times with deionized water and anhydrous ethanol until the supernatant was neutral, and then dried at 60°C to obtain a halloysite / polyaniline composite material powder.

[0056] 3) 2 g of the prepared halloysite / polyaniline composite powder was dispersed in 30 mL of ethanol, ultrasonically dispersed for 25 min, 2-mercaptobenzimidazole (MBI) was added, the mass ratio of the halloysite / polyaniline composite powder to the corrosion inhibitor was 1:1.5, and the ultrasonic treatment was continued for 40 min, and the mixture was repeatedly centrifuged, washed and dried with ethanol to obtain a nanocomposite powder loaded with a corrosion inhibitor.

[0057] 4) 1 g of the corrosion inhibitor-loaded nanocomposite powder was dispersed in 150 mL of ethanol, subjected to ultrasonic treatment for 30 min, 250 mL of an ethanol solution of polystyrene sulfonic acid with a mass concentration of 2 mg / mL was added, and stirring was continued for 60 min, followed by ethanol centrifugal washing and drying to obtain nanocapsules loaded with corrosion inhibitor using halloysite as a carrier.

[0058] The process of preparing the nanocapsule corrosion inhibitor powder in the above Examples 1 to 4 is as follows: Figure 1 shown.

[0059] The epoxy resin used in the following examples was purchased from Jining Sanshi Biotechnology Co., Ltd. with a brand name of E-51; the polyamide resin was purchased from Nanjing Erbang Chemical Co., Ltd. with a brand name of low molecular weight 650; and the phenolic resin was purchased from Henan Borun Casting Materials Co., Ltd. with a model name of CK356217.

[0060] Example 5

[0061] The capsule solid corrosion inhibitor of this embodiment is made of the nanocapsule corrosion inhibitor powder prepared in Example 1, potassium iodide, epoxy resin and polyamide resin; the mass ratio of the nanocapsule corrosion inhibitor powder, potassium iodide, epoxy resin and polyamide resin is 40:10:20:15. The capsule corrosion inhibitor of this embodiment is prepared by a method comprising the following steps:

[0062] At 110°C, 40 g of the nanocapsule corrosion inhibitor powder obtained in Example 1, 10 g of potassium iodide, 20 g of epoxy resin, and 15 g of polyamide resin were stirred and dissolved uniformly, and then granulated by an injection molding machine to obtain a nanocapsule solid corrosion inhibitor granular product with a length of 10 to 20 mm, a particle size of ≤5 mm, and a density of 1.72 g / cm 3 .

[0063] Example 6

[0064] The capsule solid corrosion inhibitor of this embodiment is made of the nanocapsule corrosion inhibitor powder prepared in Example 2, thiourea, phenolic resin and polyamide resin; the mass ratio of the nanocapsule corrosion inhibitor powder, thiourea, phenolic resin and polyamide resin is 30:8:15:10. The capsule corrosion inhibitor of this embodiment is prepared by a method comprising the following steps:

[0065] At 110°C, 30 g of the nanocapsule corrosion inhibitor powder prepared in Example 2, 8 g of thiourea, 15 g of phenolic resin, and 10 g of polyamide resin were stirred and dissolved uniformly, and then granulated by an injection molding machine to obtain a nanocapsule solid corrosion inhibitor granular product with a length of 10 to 20 mm, a particle size of ≤5 mm, and a density of 1.53 g / cm 3 .

[0066] Example 7

[0067] The capsule solid corrosion inhibitor of this embodiment is made of the nanocapsule corrosion inhibitor powder prepared in Example 3, thiourea, phenolic resin and polyamide resin; the mass ratio of the nanocapsule corrosion inhibitor powder, thiourea, phenolic resin and polyamide resin is 45:15:20:20. The capsule corrosion inhibitor of this embodiment is prepared by a method comprising the following steps:

[0068] At 110°C, 45 g of the nanocapsule corrosion inhibitor powder prepared in Example 3, 15 g of thiourea, 20 g of phenolic resin, and 20 g of polyamide resin were stirred and dissolved uniformly, and then granulated by an injection molding machine to obtain a nanocapsule solid corrosion inhibitor granular product with a length of 10 to 20 mm, a particle size of ≤5 mm, and a density of 1.50 g / cm 3 .

[0069] Example 8

[0070] The capsule solid corrosion inhibitor of this embodiment is made of the nanocapsule corrosion inhibitor powder prepared in Example 4, potassium iodide, sodium carboxymethyl cellulose and polyamide resin; the mass ratio of the nanocapsule corrosion inhibitor powder, potassium iodide, sodium carboxymethyl cellulose and polyamide resin is 20:7:10:6. The capsule corrosion inhibitor of this embodiment is prepared by a method comprising the following steps:

[0071] At 110°C, 20 g of the nanocapsule corrosion inhibitor powder prepared in Example 4, 7 g of potassium iodide, 10 g of sodium carboxymethyl cellulose, and 6 g of polyamide resin were stirred and dissolved uniformly, and then granulated by an injection molding machine to obtain a nanocapsule solid corrosion inhibitor granular product with a length of 10 to 20 mm, a particle size of ≤5 mm, and a density of 1.67 g / cm 3 .

[0072] The technical effects of the present invention are further described below in conjunction with experiments.

[0073] Experimental example: Corrosion inhibition and slow-release performance test

[0074] The sustained release performance of the capsule solid corrosion inhibitor of Examples 5-8 was studied, that is, the time (release period) for the solid corrosion inhibitor to maintain effective corrosion inhibition performance (corrosion inhibition rate ≥ 75% or corrosion rate ≤ 0.076 mm / a) was tested in a corrosive medium environment. The corrosion inhibition performance evaluation was based on the test method of SY / T 5273-2014 "Performance Indicators and Evaluation Methods of Corrosion Inhibitors for Oilfield Produced Water Treatment".

[0075] The specific methods for determining corrosion inhibition performance and sustained release performance are as follows:

[0076] Prepare the corrosive medium solution. The ion content and formula of the solution are shown in Table 1 and Table 2. The test temperature is 90°C. According to the determination method of corrosion inhibition rate in SY / T5273-2014, take two 1L glass jars and place them in 1 # Add 1000mL of the corrosive medium solution into the bottle as a blank test. # 990 mL of the corrosive medium solution was added into the bottle, and 10 g of the prepared regular-shaped granular solid corrosion inhibitor sample was added.

[0077] 2 # The bottle was placed in a thermostat and heated to 90±2℃. Every 24h, the corrosive medium was sucked into a 1L measuring cylinder using a latex tube until the cylinder reading was 950mL. Then 950mL of fresh corrosive medium solution was added to the bottle again. This process was repeated for 30 days, 60 days, 90 days, 120 days, and then at 2 days. # Two treated test pieces were hung in the bottle, taken out after 7 days of constant temperature, and the corrosion inhibition rate η and corrosion rate r were measured.

[0078] The corrosion inhibition rate η is calculated according to formula (1).

[0079]

[0080] Where: η——corrosion inhibition rate, expressed as percentage, %;

[0081] Δm 0 ——Mass loss of the test piece in the blank test, g;

[0082] Δm 1 ——Mass loss of the test piece in the corrosion inhibitor addition test, g.

[0083] The corrosion rate r is calculated according to formula (2).

[0084]

[0085] Where: r——corrosion rate, millimeters per year (mm / a);

[0086] m 0 ——The mass of the coupon before the experiment, g;

[0087] m 1 ——The mass of the coupon after the test, g;

[0088] ΔS——Total surface area of ​​the coupon, cm 2 ;

[0089] ρ——density of the hanging piece, g / cm 3 ;

[0090] t——time, h.

[0091] Table 1 Liquid ion content data table

[0092]

[0093] Table 2 10L liquid chemical dosage table

[0094]

[0095]

[0096] The corrosion inhibition and release performance test results of the solid corrosion inhibitors of Examples 5-8 are shown in Table 3.

[0097] Table 3 Corrosion inhibition and release performance test results of solid corrosion inhibitors of Examples 5-8

[0098]

[0099] The results show that the capsule solid corrosion inhibitors of Examples 5-8 can be used at high temperature (90°C) and high mineralization (>13×10 4In a harsh corrosion environment of 0.1% tantalum / mg / L), after 120 days of release, the corrosion inhibition rate still remained above 75%, the corrosion rate was much lower than 0.076 mm / a, and the corrosion inhibition performance indicators all met the requirements of SY / T 5273-2014, indicating that the capsule solid corrosion inhibitor of the present invention has good sustained-release and corrosion inhibition effects, and can be slowly released and exert its effect at a relatively stable rate.

Claims

1. A capsule solid corrosion inhibitor, Features: The invention comprises nanocapsule corrosion inhibitor powder, and the preparation method of the nanocapsule corrosion inhibitor powder comprises the following steps: 1) providing a mixed acidic dispersion of halloysite nanotubes and polymerizable monomers of a polycationic electrolyte; carrying out a polymerization reaction of the polymerizable monomers in the mixed acidic dispersion, performing solid-liquid separation after the polymerization reaction is completed, and washing the obtained solid to neutrality to obtain a halloysite / polycationic electrolyte composite material; 2) dispersing the obtained halloysite / polycationic electrolyte composite material and the corrosion inhibitor in a good solvent of the corrosion inhibitor, and performing solid-liquid separation to obtain a nanocomposite material loaded with the corrosion inhibitor; 3) The obtained nanocomposite material loaded with corrosion inhibitor and the polyacid electrolyte with negative charge after ionization are dispersed in a good solvent of the polyacid electrolyte, and then washed and dried to obtain the product.

2. The capsule solid corrosion inhibitor according to claim 1, Features: The halloysite nanotubes are halloysite nanotubes activated by acid or alkali.

3. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: In step 1), the mass ratio of halloysite nanotubes to polymerized monomers is 0.6-2:1; the polymerized monomers are one or any combination of aniline, pyrrole, and thiophene.

4. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: The polymerization reaction temperature is 0-5°C and the reaction time is 6-8h.

5. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: The corrosion inhibitor is a benzothiazole corrosion inhibitor and / or a benzimidazole corrosion inhibitor.

6. The capsule solid corrosion inhibitor according to claim 5, Features: In step 2), the mass ratio of the halloysite / polypositive electrolyte composite material to the corrosion inhibitor is 1:1.5-2; and the volume of the good solvent of the corrosion inhibitor used for every 1g of the halloysite / polypositive electrolyte composite material is 10-30mL.

7. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: In step 3), the polyacid electrolyte is one or any combination of polyacrylic acid, polymethacrylic acid, and polystyrene sulfonic acid.

8. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: In step 3), the good solvent is an alcohol solvent.

9. The capsule solid corrosion inhibitor according to claim 1 or 2, Features: The capsule solid sustained-release agent also includes a synergist, a binder and a curing agent; the mass ratio of the nanocapsule corrosion inhibitor powder, the synergist, the binder and the curing agent is 20-50:7-20:10-25:6-20.

10. The capsule solid corrosion inhibitor according to claim 9, Features: The capsule solid corrosion inhibitor is obtained by uniformly mixing nano capsule corrosion inhibitor powder, a synergist, a binder and a curing agent and then granulating the mixture.

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