A capsule solid corrosion inhibitor

Abstract

The present application relates to a kind of capsule solid corrosion inhibitor, belong to oilfield corrosion and protection technical field.The solid corrosion inhibitor capsule of the present application, including the preparation of nanocapsule corrosion inhibitor powder using the following steps: polymerization reaction of polymeric monomer is carried out in the mixed acid dispersion of halloysite nanotube, poly positive electrolyte, solid-liquid separation, wash to neutral, obtain halloysite / poly positive electrolyte composite material;After dispersion of composite material and corrosion inhibitor in good solvent of corrosion inhibitor, solid-liquid separation is carried out, and nanocomposite material is obtained;After dispersion of nanocomposite material and ionized negative charged polyacid electrolyte in good solvent of polyacid electrolyte, wash, dry.The nanocapsule corrosion inhibitor powder used in the capsule solid corrosion inhibitor is wrapped in nanotube cavity and polyelectrolyte multilayer film by layer-by-layer self-assembly of poly positive electrolyte, corrosion inhibitor and polyacid electrolyte during preparation, realizes long-acting release and stable release of corrosion inhibitor, and strengthens the slow-release effect of corrosion inhibitor.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of capsule solid corrosion inhibitor, belong to oilfield corrosion and protection technical field. BACKGROUND

[0002] Zhongyuan oilfield produced liquid has the characteristics of " four high one low ", namely Cl - High content, high salinity is (5~20) ×10 4 mg / L, HCO3 - High content, high bottom hole temperature (80~110℃), low pH (about 6.0), has strong corrosive, performance as oil well pipe string wear corrosion, pitting and other localized corrosion serious and frequent lying well, affect normal oil and gas production.In many anti-corrosion measures, the traditional solution is to add liquid corrosion inhibitor, but there are the following problems:1) intermittent injection of liquid corrosion inhibitor uneven dosing, unstable effect;2) easy to adhere to the oil pipe wall, difficult to reach near the bottom of the well, resulting in low use efficiency;3) for some wells with high water yield, high water level well, remote well and the well with packer, the use of liquid corrosion inhibitor exists some inconvenience.

[0003] In recent years, oil fields have tried to add solid corrosion inhibitors to oil production wells to solve the problem of insufficient corrosion protection effect of adding liquid corrosion inhibitors, and to achieve the purpose of effectively protecting the parts with corrosion dead angle problems such as the section below the oil pump (oil layer to the casing of the oil pump section) and the bottom of the oil well. At present, most solid corrosion inhibitors usually mix corrosion inhibitor components with synergist, weighting agent and other agents by using a binder, and are prepared by high-temperature melting, adsorption or adhesion. However, such solid corrosion inhibitors have the problems of uneven release speed, almost no release before disintegration, complete dissolution soon after disintegration, short release period and poor slow-release performance. For example, the Chinese patent application document with the application publication number CN105295880A discloses a slow-release solid corrosion inhibitor for oil wells, which is prepared by mixing main materials such as amantadine hydrochloride and auxiliary materials such as gelatinized starch according to the formula proportion, heating and stirring, compacting in a mold, and cooling. 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 is simple. Only by using a loading tool to add the solid corrosion inhibitor to the bottom of the well or other suitable positions once, the effective components of the corrosion inhibitor can be slowly released with the flowing liquid. However, the slow-release period of the solid slow-release agent is short, and it is completely released only after 60 h. For another example, the Chinese patent application document with the application publication number CN111154470A discloses a solid corrosion inhibitor for oil production wells which can effectively protect the section from the oil layer to the casing of the oil pump. In order to enhance the slow-release effect, the corrosion inhibitor is first stirred uniformly by a composite corrosion inhibitor, an organic filler, a functional weighting agent and a binder, and then a hydrophobic coating material is added to form a solid particle by an injection molding machine. The slow-release solid corrosion inhibitor is obtained by physical stirring and mixing. However, the coating property of the hydrophobic coating material on the solid particles is poor. During the process of sinking from the wellhead to the bottom of the well, the weak interaction force between the coating shell and the solid particles is small, which leads to the premature release of the corrosion inhibitor and the unsatisfactory slow-release effect.

[0004] In order to improve the corrosion inhibition effect of solid corrosion inhibitor, the corrosion inhibitor and its synergist are made into capsules or coatings by physical coating to form a drug depot type capsule, so as to effectively encapsulate the active components such as corrosion inhibitor and prevent the volatilization and oxidation of the active components, thereby improving the slow release performance of the corrosion inhibitor. In the prior art, a preparation method of a controllable release capsule corrosion inhibitor is disclosed in Chinese patent application publication No. CN110591680A, which comprises the following steps: S001: mixing a corrosion inhibitor solution and a natural halloysite nanotube carrier in a reaction kettle to obtain a mixture A; S002: mixing the mixture A in a polyvinyl alcohol (PVA) solution to obtain a mixture B; S003: extruding and cutting the mixture B in a granulator into circular granular capsules; S004: adding N,N-dimethylacetamide in a stearyl octadecyl acrylate solution, and stirring to obtain a corrosion responsive polymer; S005: uniformly spraying the emulsified corrosion responsive polymer on the surface of the capsule to form an outer shell layer, and drying the capsule in a vacuum drying box to form a final product. The capsule corrosion inhibitor can be released according to the corrosion environment, thereby prolonging 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, and when the capsule is exposed to the surrounding environment, the corrosion inhibitor may experience initial burst release and cannot be released stably for a long time. SUMMARY

[0005] The purpose of the present application is to provide a capsule solid corrosion inhibitor capable of long-term and stable release of corrosion inhibitor.

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

[0007] A capsule solid corrosion inhibitor comprises a nanocapsule corrosion inhibitor powder; and a preparation method of the nanocapsule corrosion inhibitor powder comprises the following steps:

[0008] 1) providing a mixed acid dispersion liquid of halloysite nanotubes and polymeric monomers of a positive polyelectrolyte; performing a polymerization reaction of the polymeric monomers in the mixed acid dispersion liquid, and performing solid-liquid separation after the polymerization reaction is completed, and washing the obtained solid to neutral to obtain a halloysite / polyelectrolyte composite material;

[0009] 2) dispersing the obtained halloysite / polyelectrolyte composite material and 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) dispersing the obtained nanocomposite material loaded with the corrosion inhibitor and a polyacid electrolyte with a negative charge after ionization in a good solvent of the polyacid electrolyte, and washing and drying to obtain the same.

[0011] The capsule solid corrosion inhibitor of the present application adopts nanocapsule corrosion inhibitor powder in preparation, and halloysite nanotubes with unique hollow tubular structure are used as good corrosion inhibitor slow-release carriers, in-situ polymerization reaction and electrostatic action of polymeric monomers of polypositive electrolyte form conductive polymer chains on the surface of halloysite, corrosion inhibitor molecules are filled in the lumen of halloysite and between the molecular chains and chain ends of polypositive electrolyte, and polyacid electrolyte such as polyacid electrolyte encapsulates halloysite / polypositive electrolyte composite material loaded with corrosion inhibitor through electrostatic action, the process is in the form of layer-by-layer self-assembly of polypositive electrolyte, corrosion inhibitor and polyacid electrolyte, and the corrosion inhibitor is wrapped in the nanotube lumen and polyelectrolyte multilayer film, and finally forms nanocapsules. Since a large amount of corrosion inhibitor is encapsulated in the lumen of halloysite and the interlayer shell of polypositive electrolyte and polyacid electrolyte, the problems such as easy loss of effective corrosion protection components and burst release of solid corrosion inhibitor in a corrosive environment can be overcome, thereby realizing long-acting release and stable release of the corrosion inhibitor and strengthening the slow-release effect of the corrosion inhibitor.

[0012] The nanocapsule corrosion inhibitor powder adopted in the present application adopts halloysite nanotubes (HNTs) as carriers, which have a hollow nanotube structure with open ends, and the inner and outer surfaces are respectively provided with positive and negative charges, and the nanotube has large diameter, high specific surface area and good adsorption performance, and is very suitable for being used as a carrier of corrosion inhibitor. In addition, halloysite is a natural clay mineral material, which can play the role of weighting agent, and greatly improves the settling performance of the capsule solid corrosion inhibitor adopting the nanocapsule corrosion inhibitor powder, and provides important support for the corrosion inhibitor to settle at the bottom of the oil well.

[0013] The halloysite nanotubes can be unactivated halloysite nanotubes or activated halloysite nanotubes. Further, the halloysite nanotubes are halloysite nanotubes activated by acid or alkali. The acid or alkali activated halloysite nanotubes can make the inner and outer surfaces of the halloysite nanotubes respectively present more positive and negative charges, thereby increasing the activity of the inner and outer surfaces of the halloysite nanotubes, realizing that more corrosion inhibitors are captured in the shell between the layers of polypositive electrolyte and polyacid electrolyte, and at the same time, more corrosion inhibitors enter the lumen of the halloysite nanotubes, and the loading amount of the corrosion inhibitor is increased.

[0014] It can be understood that the halloysite nanotube raw material is dispersed in acid or alkali, heated and stirred at 50-70℃, washed to neutral, dried and ground to obtain the halloysite nanotube activated by acid or alkali. The volume of the acid or alkali solution corresponding to 1g of the halloysite nanotube raw material is 10-15mL. The temperature of the heating and stirring is preferably 60℃. The time of the heating and stirring is preferably 4-8h, for example, 6h or 8h. The acid solution is preferably sulfuric acid, and the concentration is preferably 1mol / L; the alkali solution is preferably sodium hydroxide solution, and the concentration is preferably 1mol / L.

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

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

[0017] It can be understood that the polypositive electrolyte in the present application refers to the conductive polymer doped with protonic acid as a dopant and having positive charge. The polypositive electrolyte is usually obtained by initiating the chemical oxidative polymerization of the polymerization monomer in an acid medium using a water-soluble initiator. The conductive polymer is synthesized in an acid medium and doped with protonic acid at the same time, so that the polymer has high conductivity, and the nano-capsule corrosion inhibitor powder forms a conductive wireless network, which can rapidly transfer electrons, so that the electrode can rapidly generate an oxide film on the metal surface when in action, thereby improving the corrosion protection performance of the nano-capsule corrosion inhibitor powder.

[0018] Further, in step 1), the mass ratio of the halloysite nanotube to the polymerization monomer is 0.6-2:1, and preferably 0.9:1. When the mass ratio of the halloysite nanotube to the polymerization monomer is controlled within the above range, the halloysite / polypositive 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, so that the electrode can rapidly generate an oxide film on the metal surface when in action, 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 conductive polymer in the polypositive electrolyte introduced by the nano-capsule has a molecular structure containing a large conjugated π bond structure, and the oxidation-reduction potential is higher than that of metallic iron. In a corrosive environment, the polypositive electrolyte and iron are in contact with each other and react to form a dense oxide film on the metal surface, which has good corrosion inhibition effect and improves 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, the time is 8h. Polymerization at low temperature (0-5°C) is advantageous to increase the molecular weight of the polymer and make the polymer molecular weight distribution narrow, and controlling the polymerization reaction time to be 6-8h can make the synthesized conductive polymer obtain the best electrical conductivity, and beyond this time range, the electrical conductivity will be more obviously decreased. The polymerization reaction is carried out in an acidic environment. Further, the polymerization reaction is initiated by an oxidizing agent, and the oxidizing agent is preferably ammonium persulfate. The mass ratio of the polymerization monomer to the oxidizing agent 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 oxidizing agent is added dropwise into the mixed acidic dispersion liquid.

[0020] Further, the corrosion inhibitor is a benzothiazole corrosion inhibitor and / or a benzimidazole corrosion inhibitor. Both the benzothiazole corrosion inhibitor and the benzimidazole corrosion inhibitor are typical N-containing heterocyclic corrosion inhibitors, and the special molecular structure makes them have strong adsorption and form stable complexes or chelates, and it is easy for the molecules to form a large number of hydrogen bonds to make the adsorption thickened, thereby inhibiting the corrosion process of the metal. Such corrosion inhibitors have the advantages of multiple functions, high effectiveness, strong adaptability, low toxicity, etc. 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 / polyelectrolyte composite material to the corrosion inhibitor is 1:1.5-2, for example, 1:1.5. The volume of the good solvent of the corrosion inhibitor corresponding to 1g of the halloysite / polyelectrolyte composite material is 10-30mL, for example, 15-30mL. Controlling the amount of the halloysite / polyelectrolyte composite material, the corrosion inhibitor, and the good solvent of the corrosion inhibitor within the above range can make the corrosion inhibitor molecules be adsorbed and filled in the lumen of the halloysite and between and at the end of the molecular chain of the polyelectrolyte in the largest proportion. In step 2), the good solvent is ethanol and / or acetone. Ethanol and acetone are commonly used, low-toxicity, and economical organic solvents, and they can make the halloysite / polyelectrolyte composite material powder fully dispersed.

[0021] In order to further improve 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 30-60min, for example, 40min.

[0022] The encapsulation of the polycarboxylic acid electrolyte is carried out in a good solvent of the polycarboxylic acid electrolyte. Further, in step 3), the good solvent is an alcohol solvent, for example, ethanol. The alcohol solvent can make the nanocomposite material powder loaded with corrosion inhibitor molecules fully dispersed in the polycarboxylic acid electrolyte.

[0023] Further, in step 3), the polyacid electrolyte is one or any combination of polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid. The mass ratio of the polyacid electrolyte to the nano-composite material loaded with the corrosion inhibitor is 0.5-1:1, for example, 0.6:1. The polyacid electrolyte is negatively charged after ionization, and can be adsorbed by the polycation electrolyte through electrostatic adsorption, so that the corrosion inhibitor molecules are wrapped between the polycation and polyanion electrolyte layers.

[0024] Further, in step 3), the dispersion is carried out under stirring, and the stirring time is 40-60 min, for example, 60 min.

[0025] The capsule solid corrosion inhibitor of the present application has the physical barrier effect of the nano-capsule corrosion inhibitor powder in structure, the corrosion inhibition effect of the polycation electrolyte, and the release and adsorption corrosion inhibition effect of the corrosion inhibitor molecules, all of which are beneficial to the long-term release of the capsule solid corrosion inhibitor. The capsule solid corrosion inhibitor of the present application has large density and good settling performance. During the process of sinking from the wellhead to the well bottom, when corrosion occurs, the unique capsule structure of the nano-capsule corrosion inhibitor powder can make the nano-capsule solid corrosion inhibitor gradually release the corrosion inhibitor during the settling process (still able to release when reaching the bottom), effectively prevent the corrosion inhibition components from being easily lost and the burst release phenomenon from occurring, thereby realizing the long-term release of the solid corrosion inhibitor, effectively protecting the equipment from top to bottom of the oil well, and prolonging the service life of the oil well pipe material. In addition, compared with the prior art, the capsule solid corrosion inhibitor of the present application does not need to add chemical raw materials such as weighting agents during preparation, is friendly to the environment, and has high comprehensive benefits.

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

[0027] Further, the capsule solid corrosion inhibitor is obtained by granulating the mixture of the nano-capsule corrosion inhibitor powder, the synergist, the binder and the curing agent. The solid corrosion inhibitor obtained by the molding and granulation has high drug loading and encapsulation efficiency, slow dissolution, can effectively slow down the burst release phenomenon existing in the initial stage of use, and has good slow-release effect. Further, the capsule solid corrosion inhibitor prepared by granulation is a granular finished product with a length of 5-10 mm, a diameter of ≤5 mm, and a density of 1.5-1.9 g / cm 3 .

[0028] Further, the synergist is potassium iodide and / or thiourea. Potassium iodide and thiourea can enhance the anti-corrosion performance of the nano-capsule corrosion inhibitor powder by generating adsorption behavior on the metal surface. The binder is one or any combination of epoxy resin, phenolic resin, and sodium carboxymethyl cellulose. The curing agent is polyamide resin and / or hydroxyethyl ethylenediamine. Polyamide resin and hydroxyethyl ethylenediamine can form amine oxides and new covalent bonds by reacting with the epoxy groups and hydroxyl groups in the binder molecules, and this reaction is irreversible, thereby forming a cross-linked structure between the resin molecules to achieve the purpose of curing.

[0029] Further, the mixing of the nano-capsule corrosion inhibitor powder, the synergist, the binder, and the curing agent is performed at 90-120°C, for example, at 110°C.

[0030] The capsule solid corrosion inhibitor based on halloysite nanotubes is a slow-release solid corrosion inhibitor with excellent performance, which can be used for pipeline corrosion prevention and wellbore corrosion prevention, and is particularly suitable for use in oil wells with complex and harsh corrosion conditions. The solid corrosion inhibitor has the advantages of high corrosion inhibitor loading, good settling performance, uniform and slow release of corrosion inhibitor components, low dosage, long release period, high corrosion inhibition efficiency, high use value, and good application prospect. BRIEF DESCRIPTION OF DRAWINGS

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

[0032] The technical solutions of the present application are further described below in conjunction with the specific embodiments.

[0033] The halloysite nanotube raw material used in each example is a commercially available product purchased from the Lingshou County Yanbo Mineral Product Processing Co., Ltd., with a purity of more than 60% and a nanotube length of 500-1000 nm. The aniline, pyrrole, and thiophene used are all of analytical purity and are vacuum distilled before use.

[0034] Example 1

[0035] The preparation method of the nano-capsule corrosion inhibitor powder of the present example includes the following steps:

[0036] 1) 5 g of 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 washed with deionized water by centrifugation until the supernatant and HNTs particles were neutral, dried at 60°C, and ground into powder after complete drying to obtain activated HNTs for use.

[0037] 2) 2 g of the activated HNTs were added to 80 mL of 1 mol / L hydrochloric acid, after stirring evenly, aniline monomer was added, the mass ratio of the activated HNTs to aniline was 0.9:1, the mixed solution was ultrasonically treated for 30 min, then, at 0-5°C, an oxidant ammonium persulfate solution was added drop by drop, the mass ratio of the aniline monomer to ammonium persulfate was 1:2, after reaction for 8 h, the supernatant was washed to neutral with deionized water and anhydrous ethanol through centrifugation for several times, then, drying was performed at 60°C, to obtain halloysite / polyaniline composite material powder.

[0038] 3) 1.0 g of the prepared halloysite / polyaniline composite material powder was dispersed in 30 mL of ethanol, ultrasonic dispersion was performed for 25 min, an inhibitor 2-mercaptobenzothiazole (MBT) was added, the mass ratio of the halloysite / polyaniline composite material powder to the inhibitor was 1:1.5, ultrasonic treatment was continued for 40 min, and the nanocomposite material powder loaded with the inhibitor was obtained through repeated centrifugation, washing and drying with ethanol.

[0039] 4) 0.2 g of the nanocomposite material powder loaded with the inhibitor was dispersed in 30 mL of ethanol, ultrasonic treatment was performed for 30 min, 100 mL of a polyacrylic acid ethanol solution with a mass concentration of 2 mg / mL was added, stirring was continued for 60 min, then, the nanocapsules loaded with the inhibitor and taking halloysite as a carrier were obtained through centrifugation washing and drying with ethanol.

[0040] Example 2

[0041] The preparation method of the nanocapsule inhibitor powder of the present example comprises the following steps:

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

[0043] 2) 1.5 g of the activated HNTs was added to 80 mL of 1 mol / L hydrochloric acid, after stirring evenly, pyrrole monomer was added, the mass ratio of the activated HNTs to pyrrole was 0.9:1, the mixed solution was ultrasonically treated for 30 min, then, at 0-5°C, an ammonium persulfate solution was added drop by drop, the mass ratio of the pyrrole monomer to ammonium persulfate was 1:2, after reaction for 8 h, the supernatant was washed to neutral with deionized water and anhydrous ethanol through centrifugation for several times, then, drying was performed at 60°C, to obtain halloysite / poly-pyrrole composite material powder.

[0044] 3) The prepared halloysite / polyazole composite powder 1 g was dispersed in 20 mL of ethanol, ultrasonic dispersion for 25 min, and the corrosion inhibitor 2-mercaptobenzothiazole (MBT) was added, the mass ratio of halloysite / polyazole composite powder to corrosion inhibitor was 1:1.5, and the ultrasonic treatment was continued for 40 min, and the nanocomposite powder loaded with corrosion inhibitor was obtained by repeated centrifugation, washing and drying with ethanol.

[0045] 4) The nanocomposite powder loaded with corrosion inhibitor 0.3 g was dispersed in 50 mL of ethanol, ultrasonic treatment for 30 min, and 90 mL of 2 mg / mL poly-methacrylic acid ethanol solution was added, and the stirring was continued for 60 min, and then the ethanol was centrifuged, washed and dried to obtain the nanocapsule loaded with corrosion inhibitor with halloysite as the carrier.

[0046] Example 3

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

[0048] 1) 8 g of 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, and dried at 60°C. After complete drying, the powder was ground to obtain activated HNTs for use.

[0049] 2) 4 g of activated HNTs was added to 80 mL of 1 mol / L hydrochloric acid, stirred uniformly, and then thiophene monomer was added, the mass ratio of activated HNTs to thiophene was 0.9:1, the mixed solution was ultrasonically treated for 30 min, then ammonium persulfate solution was added dropwise at 0-5°C, the mass ratio of thiophene monomer to ammonium persulfate was 1:2, the reaction was carried out for 8 h, then centrifuged and washed with deionized water and anhydrous ethanol several times until the supernatant was neutral, and then dried at 60°C to obtain halloysite / polythiophene composite powder.

[0050] 3) The prepared halloysite / polythiophene composite powder 2 g was dispersed in 60 mL of ethanol, ultrasonic dispersion for 25 min, and the corrosion inhibitor 2-mercaptobenzothiazole (MBT) was added, the mass ratio of halloysite / polythiophene composite powder to corrosion inhibitor was 1:1.5, and the ultrasonic treatment was continued for 40 min, and the nanocomposite powder loaded with corrosion inhibitor was obtained by repeated centrifugation, washing and drying with ethanol.

[0051] 4) The nanocomposite powder loaded with corrosion inhibitor 0.5 g was dispersed in 75 mL of ethanol, ultrasonic treatment for 30 min, and 150 mL of 2 mg / mL poly-methacrylic acid ethanol solution was added, and the stirring was continued for 60 min, and then the ethanol was centrifuged, washed and dried to obtain the nanocapsule loaded with corrosion inhibitor with halloysite as the carrier.

[0052] Example 4

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

[0054] 1) 5 g of 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 use.

[0055] 2) 3 g of activated HNTs was added to 80 mL of 1 mol / L hydrochloric acid, and after uniform stirring, aniline monomer was added, the mass ratio of activated HNTs to aniline being 0.9:1, the mixture was ultrasonically treated for 30 min, then ammonium persulfate solution was added dropwise at 0-5°C, the mass ratio of aniline monomer to ammonium persulfate being 1:2, after 8 h of reaction, the supernatant was washed with deionized water and anhydrous ethanol several times until it was neutral, and then dried at 60°C to obtain halloysite / polyaniline composite 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 halloysite / polyaniline composite powder to corrosion inhibitor being 1:1.5, ultrasonic treatment was continued for 40 min, and repeated centrifugation, washing and drying with ethanol to obtain nanocomposite powder loaded with corrosion inhibitor.

[0057] 4) 1 g of the nanocomposite powder loaded with corrosion inhibitor was dispersed in 150 mL of ethanol, ultrasonically treated for 30 min, 250 mL of a 2 mg / mL polystyrene sulfonic acid ethanol solution was added, stirring was continued for 60 min, and then ethanol was used for centrifugal washing and drying to obtain halloysite-supported nanocapsules loaded with corrosion inhibitor.

[0058] The preparation method of the nanocapsule corrosion inhibitor powder in Examples 1-4 above is shown in the flowchart of Figure 1 .

[0059] The epoxy resin used in the following examples was purchased from Jining Sanshi Biotechnology Co., Ltd., with the model number E-51; the polyamide resin was purchased from Nanjing Erbang Chemical Co., Ltd., with the model number low molecular 650, and the phenolic resin was purchased from Henan Puren Foundry Material Co., Ltd., with the model number CK356217.

[0060] Example 5

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

[0062] The nano-capsule corrosion inhibitor powder 40 g prepared in Example 1, potassium iodide 10 g, epoxy resin 20 g and polyamide resin 15 g are stirred and uniformly dissolved at 110°C, and then granulated by an injection molding machine to prepare the nano-capsule solid corrosion inhibitor granular product, which has a length of 10-20 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 the present embodiment is made of the nano-capsule corrosion inhibitor powder prepared in Example 2, thiourea, phenolic resin and polyamide resin; the mass ratio of the nano-capsule corrosion inhibitor powder, thiourea, phenolic resin and polyamide resin is 30:8:15:10. The capsule corrosion inhibitor of the present embodiment is prepared by the method comprising the following steps:

[0065] The nano-capsule corrosion inhibitor powder 30 g prepared in Example 2, thiourea 8 g, phenolic resin 15 g and polyamide resin 10 g are stirred and uniformly dissolved at 110°C, and then granulated by an injection molding machine to prepare the nano-capsule solid corrosion inhibitor granular product, which has a length of 10-20 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 the present embodiment is made of the nano-capsule corrosion inhibitor powder prepared in Example 3, thiourea, phenolic resin and polyamide resin; the mass ratio of the nano-capsule corrosion inhibitor powder, thiourea, phenolic resin and polyamide resin is 45:15:20:20. The capsule corrosion inhibitor of the present embodiment is prepared by the method comprising the following steps:

[0068] The nano-capsule corrosion inhibitor powder 45 g prepared in Example 3, thiourea 15 g, phenolic resin 20 g and polyamide resin 20 g are stirred and uniformly dissolved at 110°C, and then granulated by an injection molding machine to prepare the nano-capsule solid corrosion inhibitor granular product, which has a length of 10-20 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 from the nano-capsule corrosion inhibitor powder obtained in Example 4, potassium iodide, sodium carboxymethyl cellulose, and polyamide resin; the mass ratio of the nano-capsule 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 including the following steps:

[0071] At 110°C, 20g of the nanocapsule corrosion inhibitor powder prepared in Example 4, 7g of potassium iodide, 10g of sodium carboxymethyl cellulose, and 6g of polyamide resin were stirred and mixed evenly. The mixture was then granulated using an injection molding machine to obtain granular nanocapsule solid corrosion inhibitor with a length of 10-20mm, a particle size ≤5mm, and a density of 1.67g / cm³. 3 .

[0072] The technical effects of the present invention will be further described below with reference to experiments.

[0073] Experimental Example: Corrosion Inhibition and Slow-Release Performance Tests

[0074] The sustained-release performance of the capsule solid corrosion inhibitors in Examples 5-8 was studied, specifically, the time (release cycle) during which the solid corrosion inhibitors maintained effective corrosion inhibition performance (corrosion inhibition rate ≥75% or corrosion rate ≤0.076 mm / a) in a corrosive medium environment was tested. The corrosion inhibition performance was evaluated according to the test methods in SY / T 5273-2014 "Performance Indicators and Evaluation Methods for Corrosion Inhibitors for Oilfield Produced Water Treatment".

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

[0076] Prepare the corrosive medium solution. Refer to Tables 1 and 2 for the ion content and formulation. The test temperature is 90℃. Following the method for determining corrosion inhibition rate in SY / T5273-2014, take two 1L wide-mouth glass bottles and test at 1... # Add 1000 mL of corrosive medium solution to the bottle as a blank test. In 2... # Add 990 mL of corrosive medium solution to the bottle, and add 10 g of the prepared granular solid corrosion inhibitor sample with regular shape.

[0077] 2 # The bottle was placed in a constant temperature incubator and heated to 90±2℃. Every 24 hours, corrosive medium was drawn into a 1L graduated cylinder using a latex tube until the graduated cylinder reading reached 950mL. Then, 950mL of fresh corrosive medium solution was added to the bottle. This process was repeated for 30, 60, 90, and 120 days. Then, on day 2... # Two treated test pieces were hung in the bottle and kept at a constant temperature for 7 days before being removed to determine the corrosion inhibition rate η and the corrosion rate r.

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

[0079]

[0080] wherein: η - corrosion inhibition rate, in percent, %;

[0081] Δm0 - mass loss of the test piece in the blank test, g;

[0082] Δm1 - mass loss of the test piece in the test with corrosion inhibitor, g.

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

[0084]

[0085] wherein: r - corrosion rate, mm per year (mm / a);

[0086] m0 - mass of the test piece before the experiment, g;

[0087] m1 - mass of the test piece after the experiment, g;

[0088] ΔS - total surface area of the test piece, cm 2 ;

[0089] ρ - density of the test piece, g / cm 3 ;

[0090] t - time, h.

[0091] Table 1. Data on the ion content of the prepared solutions

[0092]

[0093] Table 2. Dosage table for the chemical agents for 10 L of the prepared solution

[0094]

[0095]

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

[0097] Table 3. Results of the tests of the corrosion inhibition and release properties of the solid corrosion inhibitors of Examples 5-8

[0098]

[0099] The results show that the capsule solid corrosion inhibitors of Examples 5-8 have a high corrosion inhibition rate at high temperatures (90°C) and high salinity (>13 x 10 4In the severe corrosive environment of 0.5 mol / L NaCl (pH 3.5) and 0.5 mol / L H2SO4 (pH 1.2), the corrosion inhibition rate is still above 75% after 120 days of release, and the corrosion rate is far below 0.076 mm / a, the corrosion inhibition performance indexes meet the requirements of SY / T 5273-2014, indicating that the capsule solid corrosion inhibitor has good slow release and corrosion inhibition effect, and can slowly release and play a role at a relatively stable rate.

Claims

1. A capsule-shaped solid corrosion inhibitor, characterized in that: The invention includes nanocapsule corrosion inhibitor powder, and the preparation method of the nanocapsule corrosion inhibitor powder includes the following steps: 1) Provide a mixed acidic dispersion of halloysite nanotubes and polymeric monomers of polyelectrolyte; carry out the polymerization reaction of the polymeric monomers in the mixed acidic dispersion; after the polymerization reaction is completed, perform solid-liquid separation, wash the obtained solid until neutral, and obtain halloysite / polyelectrolyte composite material; the polymeric monomers are one or any combination of aniline, pyrrole, and thiophene; 2) The obtained halloysite / polyelectrolyte composite material and corrosion inhibitor were dispersed in a good solvent of the corrosion inhibitor, and then the solid and liquid were separated to obtain a nanocomposite material loaded with corrosion inhibitor; the corrosion inhibitor is a benzothiazole corrosion inhibitor and / or a benzimidazole corrosion inhibitor. 3) The obtained nanocomposite material with corrosion inhibitor and the negatively charged polyacid electrolyte after ionization are dispersed in a good solvent of polyacid electrolyte, washed and dried to obtain the final product.

2. The capsule solid corrosion inhibitor according to claim 1, characterized in that: The halloysite nanotubes are halloysite nanotubes that have been activated by acid or alkali.

3. The capsule solid corrosion inhibitor according to claim 1 or 2, characterized in that: In step 1), the mass ratio of halloysite nanotubes to polymer monomers is 0.6 to 2:

1.

4. The capsule solid corrosion inhibitor according to claim 1 or 2, characterized in that: The polymerization reaction is carried out at a temperature of 0-5°C for 6-8 hours.

5. The capsule solid corrosion inhibitor according to claim 1, characterized in that: In step 2), the mass ratio of halloysite / polyelectrolyte composite material to corrosion inhibitor is 1:1.5~2; the volume of good solvent for corrosion inhibitor used for each 1g halloysite / polyelectrolyte composite material is 10~30mL.

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

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

8. The capsule solid corrosion inhibitor according to claim 1 or 2, characterized in that: 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, synergist, binder, and curing agent is 20~50:7~20:10~25:6~20.

9. The capsule solid corrosion inhibitor according to claim 8, characterized in that: The capsule solid corrosion inhibitor is obtained by granulating a mixture of nano-capsule corrosion inhibitor powder, synergist, binder and curing agent.

Images