Corrosion inhibitor for titanium alloy articles

Abstract

The application provides a corrosion inhibitor suitable for titanium alloy products. The corrosion inhibitor comprises: an inorganic salt, a synergist and a solvent, wherein the inorganic salt has the general formula: M x AO y wherein M is a monovalent ion, A is selected from one or more of the group consisting of chromium, silicon, tungsten, boron, manganese, iodine, bromine, tin and tellurium, x and y are dynamically adjusted according to the valence of A, and the inorganic salt can form a passivation film / deposition film on the surface of the titanium alloy. In the application process, the inorganic salt can form a passivation film / deposition film protective layer on the surface of the titanium alloy. The protective layer can effectively block the contact between the acid liquid and the substrate, thereby inhibiting the corrosion of the substrate. The synergist can promote the rapid film formation of the inorganic salt on the surface of the titanium alloy, and improve the compactness and integrity of the film. Therefore, the use of the above-mentioned corrosion inhibitor can greatly improve the corrosion resistance of the titanium alloy product in a high-temperature and high-acid environment.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction, and more specifically, to a corrosion inhibitor suitable for titanium alloy products. Background Technology

[0002] During oil and gas field development, production tubing will be exposed to high temperatures and pressures, and contain H2S, CO2, and high concentrations of Cl. - The presence of sulfur (S) in fluid media places increasingly stringent demands on the materials and protection technologies of oil and gas well tubing. Conventional carbon steel, low-alloy steel, and stainless steel are insufficient to meet the demands of increasingly harsh mining environments. While nickel-based alloys meet the requirements of high temperature, high pressure, and high-concentration corrosive media, their high cost makes them a significant candidate material for high-temperature, high-pressure acidic oil and gas wells. However, titanium alloys exhibit high corrosion rates in reducing acid environments. Downhole development in oil and gas fields requires acid fracturing, typically using HCl or a mixture of HCl and HF. The corrosion problem of titanium alloys under reducing acid conditions has consistently hindered their widespread application in oil and gas fields.

[0003] Currently, there are no reports in China of corrosion inhibitors for titanium alloys in reducing acids. International research on the acidification of titanium alloys mainly focuses on HF systems and is applicable at relatively low temperatures. For example, US010138560B2 uses boric acid and other boron-containing compounds as corrosion inhibitors for titanium alloys in HF and fluorides, which effectively suppresses corrosion of titanium and titanium alloys. At 121℃ in 1% HF, the corrosion rate is 30–63 g / (m³). 2 In US20170298266A1, a corrosion inhibitor composed of boric acid and N-(phosphonyl)iminodiacetic acid or any salt thereof is used to inhibit the corrosion of titanium and titanium alloys in a hydrofluoric acid-containing environment. In a 1.5% HF system at 93°C, the corrosion rate is 0.13 g / (m³). 2 ·h).

[0004] In view of the above problems, there is a need for a corrosion inhibitor suitable for titanium alloy products that has good corrosion inhibition performance under high temperature (≤180℃) and high acid (≤15% HCl) conditions. Summary of the Invention

[0005] The main objective of this invention is to provide a corrosion inhibitor suitable for titanium alloy products, in order to solve the problem that existing titanium alloy products have poor corrosion resistance in high temperature and acidic environments.

[0006] To achieve the above objectives, the present invention provides a corrosion inhibitor suitable for titanium alloy products, comprising: an inorganic salt, a synergist, and a solvent, wherein the inorganic salt has the following general formula: MxAOy, where M is a monovalent ion, A is selected from one or more elements in the group consisting of chromium, silicon, tungsten, boron, manganese, iodine, bromine, tin, and tellurium, and x and y are dynamically adjusted according to the valence state of A. The inorganic salt can form a passivation film / precipitate film on the surface of the titanium alloy product.

[0007] Furthermore, based on the percentage content of the corrosion inhibitor applicable to titanium alloy products, the corrosion inhibitor applicable to titanium alloy products includes: 3-5% inorganic salt, 0.5-1% synergist and the balance solvent.

[0008] Furthermore, the inorganic salt is selected from one or more of the group consisting of chromates, silicates, tungstates, borates, manganates, iodates, bromates, stannates, and tellurates.

[0009] Further, chromates are selected from sodium chromate and / or potassium chromate; silicates are selected from sodium silicate and / or potassium silicate; tungstates are selected from one or more of the group consisting of sodium tungstate, potassium tungstate, and ammonium tungstate; borates are selected from sodium borate and / or potassium borate; manganates are selected from sodium manganate and / or potassium manganate; iodates are selected from sodium iodate and / or potassium iodate; borates are selected from sodium bromate and / or potassium bromate; stannates are selected from sodium stannate and / or potassium stannate; and tellurates are selected from sodium tellurate and / or potassium tellurate.

[0010] Furthermore, the inorganic salt is a mixture of stannate and tellurate.

[0011] Furthermore, the weight ratio of stannate to tellurate is (1-4):(1-5).

[0012] Furthermore, the inorganic salt is a mixture of silicates and tungstates.

[0013] Furthermore, the weight ratio of silicate to tungstate is (1-4):(1-3).

[0014] Furthermore, the synergist is an acyl peroxide.

[0015] Furthermore, the synergist is selected from one or more of the group consisting of benzoyl peroxide, acetyl peroxide, and didecyl peroxide.

[0016] By applying the technical solution of this invention, during the application of the above-mentioned corrosion inhibitor, inorganic salts can form a passivation film / precipitation film protective layer on the surface of titanium alloys. This protective layer can effectively block the contact between acid and the substrate, thereby inhibiting the corrosion of the substrate. Titanium alloys react violently and dissolve very quickly in high-temperature, high-concentration acid systems, affecting the film-forming effect of the corrosion inhibitor. The synergist can promote the rapid film formation of inorganic salts on the surface of titanium alloys, improving the density and integrity of the film layer. Therefore, the use of the above-mentioned corrosion inhibitor can greatly improve the corrosion resistance of titanium alloy products in high-temperature, high-acid environments. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0018] As described in the background section, existing titanium alloy products exhibit poor corrosion resistance in high-temperature and acidic environments. To address this problem, this application provides a corrosion inhibitor suitable for titanium alloy products. The corrosion inhibitor comprises: an inorganic salt, a synergist, and a solvent, wherein the inorganic salt has the following general formula: M x AO y M is a monovalent ion, and A includes, but is not limited to, one or more elements in the group consisting of chromium, silicon, tungsten, boron, manganese, iodine, bromine, tin and tellurium. x and y are dynamically adjusted according to the valence state of A, and the inorganic salt can form a passivation film / precipitate film on the surface of titanium alloy products.

[0019] Under normal conditions, titanium alloys exhibit excellent corrosion resistance because a thin oxide film, ranging from several nanometers to tens of nanometers thick, can form on their surface. However, in high-temperature, high-concentration HCl environments, this passivation film is damaged, and the titanium alloy surface becomes activated. The protective film formed by common organic corrosion inhibitors on the titanium alloy surface is insufficient to prevent HCl penetration. This results in poor corrosion resistance of titanium alloy products under high-temperature, high-hydrochloric acid conditions.

[0020] During application, the inorganic salts in the aforementioned corrosion inhibitors form a passivation / precipitation film on the titanium alloy surface, preventing further dissolution of the titanium alloy substrate in corrosive environments (especially in high-temperature, high-concentration HCl, Ti + HCl → TiCl3 + H2). The synergist promotes the rapid formation of the passivation / precipitation film and improves its density and integrity. Therefore, the use of these corrosion inhibitors can significantly improve the corrosion resistance of titanium alloy products in high-temperature, high-acid environments.

[0021] To further improve the corrosion protection effect of the above-mentioned corrosion inhibitor on titanium alloy products, preferably, the corrosion inhibitor suitable for titanium alloy products comprises, based on the percentage content of the corrosion inhibitor applicable to titanium alloy products: 3-5% inorganic salt, 0.5-1.0% synergist, and the balance being solvent. The weight percentage of the inorganic salt in the corrosion inhibitor can be selected as 3%, 3.5%, 4%, 4.5%, and 5%, and the weight percentage of the synergist can be selected as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%.

[0022] Any inorganic salt capable of forming a passivation / precipitation protective film on the surface of titanium alloy products can be used as a component of a corrosion inhibitor. In a preferred embodiment, the inorganic salt includes, but is not limited to, one or more of the group consisting of chromates, silicates, tungstates, borates, manganates, iodates, bromates, stannates, and tellurates. The anions in the aforementioned inorganic salts exhibit strong cation selectivity; therefore, compared to other inorganic salts, using these inorganic salts as components of a corrosion inhibitor is beneficial for further improving the protective properties of the film, effectively preventing HCl from penetrating the film and corroding the substrate, thereby further improving the corrosion resistance of the titanium alloy products.

[0023] To improve the solubility of inorganic salts during application and thus enhance the overall effect of corrosion inhibitors, in a preferred embodiment, chromates include, but are not limited to, one or more of the group consisting of sodium chromate and potassium chromate; silicates include, but are not limited to, sodium silicate and / or potassium silicate; tungstates include, but are not limited to, one or more of the group consisting of sodium tungstate, potassium tungstate, and ammonium tungstate; borates include, but are not limited to, sodium borate and / or potassium borate; manganates include, but are not limited to, sodium manganate and / or potassium manganate; iodates include, but are not limited to, sodium iodate and / or potassium iodate; borates include, but are not limited to, sodium bromate and / or potassium bromate; stannates include, but are not limited to, sodium stannate and / or potassium stannate; and tellurates include, but are not limited to, sodium tellurate and / or potassium tellurate.

[0024] In a preferred embodiment, the inorganic salt is a mixture of stannate and tellurate. More preferably, the weight ratio of stannate to tellurate is (1-4):(1-5). Limiting the weight ratio of stannate to tellurate within the above range is beneficial to further enhance the synergistic effect of the two, thereby further improving the corrosion inhibitor's effect on the corrosion resistance of titanium alloy products.

[0025] In a preferred embodiment, the inorganic salt is a mixture of silicate and tungstate. More preferably, the weight ratio of silicate to tungstate is (1-4):(1-3). Limiting the weight ratio of silicate to tungstate within the above range is beneficial to further enhance the synergistic effect of the two, thereby further improving the corrosion inhibitor's effect on the corrosion resistance of titanium alloy products.

[0026] The aforementioned synergists can be of types commonly used in the art. In a preferred embodiment, the synergist is an acyl peroxide. Compared to other types of synergists such as zinc salts and polyphosphates, which are used as compound substances to supplement the defects in the main agent film, acyl peroxide synergists utilize their strong oxidizing properties to promote the rapid film formation of inorganic salts on the titanium alloy surface, improve the film density and integrity, and form a protective film in a short time. This effectively isolates the acid from the titanium alloy substrate, achieving the effect of corrosion prevention and inhibition, and improving the corrosion inhibition effect of inorganic salts.

[0027] In a preferred embodiment, the synergist includes, but is not limited to, one or more of the group consisting of benzoyl peroxide, acetyl peroxide, and didecyl peroxide. Compared to other synergists, the above-mentioned acyl peroxide synergists can accelerate the film formation rate of inorganic salts on the surface of titanium alloy products and improve the film density, effectively separating the acid solution from the titanium alloy substrate and providing excellent protection for the titanium alloy substrate.

[0028] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0029] All chemical reagents used in the embodiments of this invention are commercially available chemically pure reagents. The embodiments were conducted according to the test method and evaluation index of corrosion inhibitors for acidification in SY / T 5405-2019. The test samples were made of titanium alloy oil pipe material, the acidification solution was 15% (mass fraction) hydrochloric acid aqueous solution, the test temperature was 180℃, and the test time was 4h.

[0030] Example 1

[0031] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 5% sodium tungstate, 1% benzoyl peroxide synergist, and 94% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 23.7438 g / (m²). 2 ·h).

[0032] Example 2

[0033] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 3% sodium tungstate, 1% benzoyl peroxide synergist, and 96% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 27.3392 g / (m²). 2 ·h).

[0034] Example 3

[0035] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 5% sodium borate, 1% acetyl peroxide synergist, and 94% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 15.2515 g / (m²).2 ·h).

[0036] Example 4

[0037] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 3.5% sodium borate, 1% acetyl peroxide synergist, and 95.5% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 18.3396 g / (m²). 2 ·h).

[0038] Example 5

[0039] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 4.5% sodium stannate, 1% decanoyl peroxide synergist, and 94.5% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 31.3728 g / (m²). 2 ·h).

[0040] Example 6

[0041] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 3% sodium stannate, 1% decanoyl peroxide synergist, and 96% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 33.2775 g / (m²). 2 ·h).

[0042] Example 7

[0043] A corrosion inhibitor suitable for titanium alloy products, by weight percentage, comprises 5% sodium silicate, 1% decanoyl peroxide synergist, and 94% deionized water solvent. Test results show that the corrosion rate of the titanium alloy is 26.5890 g / (m²). 2 ·h).

[0044] Example 8

[0045] The difference from Example 1 is that the amount of synergist is 0.5%, and the amount of solvent is adjusted so that the sum of the weight percentages of each component in the corrosion inhibitor is 100%.

[0046] Test results show that the corrosion rate of the titanium alloy is 30.0541 g / (m²). 2 ·h).

[0047] Example 9

[0048] The difference from Example 1 is that the amount of inorganic salt used is 2%, and the amount of solvent is adjusted so that the sum of the weight percentages of each component in the corrosion inhibitor is 100%.

[0049] Test results show that the corrosion rate of the titanium alloy is 82.5326 g / (m²). 2 ·h).

[0050] Example 10

[0051] The difference from Example 1 is that the inorganic salt is ammonium tungstate.

[0052] Test results show that the corrosion rate of the titanium alloy is 24.3785 g / (m²). 2 ·h).

[0053] Example 11

[0054] The difference from Example 1 is that the inorganic salt is sodium tellurate.

[0055] Test results show that the corrosion rate of the titanium alloy is 34.3757 g / (m²). 2 ·h).

[0056] Example 12

[0057] The difference from Example 1 is that the inorganic salt is sodium tellurate, the amount added is 3%, and the amount of solvent is adjusted so that the sum of the weight percentages of each component in the corrosion inhibitor meets 100%.

[0058] Test results show that the corrosion rate of the titanium alloy is 36.9818 g / (m²). 2 ·h).

[0059] Example 13

[0060] The difference from Example 1 is that the inorganic salt is sodium chromate.

[0061] Test results show that the corrosion rate of the titanium alloy is 35.1723 g / (m²). 2 ·h).

[0062] Example 14

[0063] The difference from Example 1 is that the inorganic salt is sodium iodate.

[0064] Test results show that the corrosion rate of the titanium alloy is 43.2435 g / (m²). 2 ·h).

[0065] Example 15

[0066] The difference from Example 5 is that the weight ratio of sodium stannate to sodium tellurate is 1:1.

[0067] Test results show that the corrosion rate of the titanium alloy is 15.3118 g / (m²). 2 ·h).

[0068] Example 16

[0069] The difference from Example 5 is that the weight ratio of sodium stannate to sodium tellurate is 4:1.

[0070] Test results show that the corrosion rate of the titanium alloy is 13.3728 g / (m²). 2 ·h).

[0071] Example 17

[0072] The difference from Example 5 is that the weight ratio of sodium stannate to sodium tellurate is 4:5.

[0073] Test results show that the corrosion rate of the titanium alloy is 16.9613 g / (m²). 2 ·h).

[0074] Example 18

[0075] The difference from Example 5 is that the weight ratio of sodium stannate to sodium tellurate is 1:5.

[0076] Test results show that the corrosion rate of the titanium alloy is 20.0698 g / (m²). 2 ·h).

[0077] Example 19

[0078] The difference from Example 7 is that the weight ratio of sodium silicate to sodium tungstate is 1:1.

[0079] Test results show that the corrosion rate of the titanium alloy is 14.7358 g / (m²). 2 ·h).

[0080] Example 20

[0081] The difference from Example 7 is that the weight ratio of sodium silicate to sodium tungstate is 1:3.

[0082] Test results show that the corrosion rate of the titanium alloy is 13.3327 g / (m²). 2 ·h).

[0083] Example 21

[0084] The difference from Example 7 is that the weight ratio of sodium silicate to sodium tungstate is 4:1.

[0085] Test results show that the corrosion rate of the titanium alloy is 18.5890 g / (m²). 2 ·h).

[0086] Example 22

[0087] The difference from Example 7 is that the weight ratio of sodium silicate to sodium tungstate is 4:3.

[0088] Test results show that the corrosion rate of the titanium alloy is 16.6132 g / (m²). 2 ·h).

[0089] Example 23

[0090] The difference from Example 1 is that the amount of synergist used is 2%, and the amount of solvent is adjusted so that the sum of the weight percentages of each component in the corrosion inhibitor is 100%.

[0091] Test results show that the corrosion rate of the titanium alloy is 55.9915 g / (m²). 2 ·h).

[0092] Example 24

[0093] The difference from Example 1 is that the synergist is zinc sulfate.

[0094] Test results show that the corrosion rate of the titanium alloy is 78.7866 g / (m²). 2 ·h).

[0095] Example 25

[0096] The difference from Example 5 is that the weight ratio of sodium stannate to sodium tellurate is 4:7.

[0097] Test results show that the corrosion rate of the titanium alloy is 40.0698 g / (m²). 2 ·h).

[0098] Example 26

[0099] The difference from Example 7 is that the weight ratio of sodium silicate to sodium tungstate is 6:1.

[0100] Test results show that the corrosion rate of the titanium alloy is 30.6158 g / (m²). 2 ·h).

[0101] Comparative Example 1

[0102] The difference from Example 1 is that no synergist was added, and the amount of solvent was adjusted so that the sum of the weight percentages of each component in the corrosion inhibitor met 100%.

[0103] Test results show that the corrosion rate of the titanium alloy is 89.6458 g / (m²). 2 ·h).

[0104] Comparative Example 2

[0105] The difference from Example 1 is that no corrosion inhibitor was added.

[0106] Test results show that the corrosion rate of the titanium alloy is 1045.9175 g / (m²). 2 ·h).

[0107] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0108] Comparing Examples 1 to 26 with Comparative Examples 1 and 2, it can be seen that the corrosion resistance of titanium alloy products is greatly improved after adding the corrosion inhibitor provided in this application.

[0109] Comparative Examples 1, 8, 23 and 24 and Comparative Example 1 show that by adding a synergist and limiting its dosage to the preferred range of this application, the corrosion resistance of the titanium alloy product is greatly improved.

[0110] Comparing Examples 1, 2, and 9, it can be seen that limiting the amount of inorganic salt within the preferred range of this application is beneficial to improving the corrosion resistance of titanium alloy products.

[0111] Comparing Examples 1, 3, 7, 10, 11, 13, 14, 15 to 26, it can be seen that adjusting the inorganic salt composition is beneficial to improving the corrosion resistance of titanium alloy products.

[0112] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A corrosion inhibitor suitable for titanium alloy products, characterized in that, The corrosion inhibitor for titanium alloy products comprises, by percentage, 3-5% of the inorganic salt, 0.5-1% of the synergist and the balance of the solvent, wherein the inorganic salt is capable of forming a passivation film / precipitate film on the surface of the titanium alloy product. The inorganic salt is selected from one of the groups consisting of tungstate, bromate, stannate, and tellurate; or the inorganic salt is a mixture of stannate and tellurate; or the inorganic salt is a mixture of silicate and tungstate. The synergist is selected from one or more of the group consisting of benzoyl peroxide, acetyl peroxide, and didecyl peroxide.

2. The corrosion inhibitor for titanium alloy products according to claim 1, characterized in that, The tungstate is selected from one or more of the group consisting of sodium tungstate, potassium tungstate and ammonium tungstate; The bromate is selected from sodium bromate and / or potassium bromate; The stannate is selected from sodium stannate and / or potassium stannate; the tellurate is selected from sodium tellurate and / or potassium tellurate.

3. The corrosion inhibitor for titanium alloy products according to claim 1, characterized in that, The weight ratio of the stannate to the tellurate is (1-4): (1-5).

4. The corrosion inhibitor for titanium alloy products according to claim 1, characterized in that, The weight ratio of the silicate to the tungstate is (1-4): (1-3).