WO2014178738A1

WO2014178738A1 - Water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines as well as the method of its production.

Info

Publication number: WO2014178738A1
Application number: PCT/PL2014/000048
Authority: WO
Inventors: Barbara GAŹDZIK; Wojciech MAZELA; Michał PAJDA; Leszek ZIEMIAŃSKI; Iwona SKRĘT; Stefan PTAK; Ewa ZEGARMISTRZ; Mieczysław SOCHA; Zbigniew PAĆKOWSKI
Original assignee: Instytut Nafty I Gazu - Panstwowy Instytut Badawczy
Priority date: 2013-05-02
Filing date: 2014-05-05
Publication date: 2014-11-06
Also published as: RU2643006C2; UA117583C2; EP2992066A1; RU2015150547A; WO2014178738A8

Abstract

The water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines contains: - component a) obtained through neutralization from 0.1 to 50 % by weight, of the new mixture of modified imidazoline derivatives, which constitutes a mixture of substances of general formulas (1) and (2), wherein R₁: C₁₂-C₂₂whereinR₂:C₂-C₁₂ with the possible addition of a product of general formula (1') wherein R₃: C₁₂-C₂₄ with an aliphatic and/or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms per molecule, - component b) that is oxyethylenated fatty amines containing from 2 to 20 ethoxyl groups per molecule - component c) that is an alkalizing agent - optional component d) that is an aliphatic polyol - component e) that is an aliphatic alcohol containing from 1 to 6 carbon atoms per molecule, optionally with the addition of water - component f) that is an anti-foaming agent.

Description

TITLE:

Water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines as well as the method of its production.

TECHNICAL FIELD:

The invention relates to a water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines as well as to the method of its production.

BACKGROUND ART: The phenomenon of corrosion is a serious problem in the natural gas extraction industry and is the result of chemical or electrochemical reactions of metal elements with the environment.

More than one type of corrosion occurs in gas wells. Drilling fluids are usually aqueous saline solutions that perform the role of an electrolyte. Produced water, which is present during the extraction of natural gas, also contains inorganic salts such as chlorides (sodium, potassium, magnesium), sulfates (sodium, potassium, magnesium), and carbonates. Electrochemical corrosion occurs readily in aqueous systems containing salts. It is caused by the action of galvanic cells forming between the passivated metal surface and a surface that does not possess such a layer. The effect of electrochemical corrosion is mainly pitting corrosion on the surfaces of lifting casings and pipelines as well as on operational equipment. The most damage to pipe and casing surfaces occurs in saline solutions with concentrations of 7 - 13 %.

Large corrosion damage is caused by the presence of carbon dioxide in the drilled deposit. A characteristic trait of the corrosion resulting from the presence of carbon dioxide in extracted gas is the presence of smooth well edges. Corrosion caused by the presence of carbon dioxide in gas wells is often called "neutral" corrosion. Carbon dioxide, when dissolved in water, forms H₂C0₃, which then reacts with iron to form iron carbonate FeC0₃, and hydrogen gas H₂ is also formed. When carbon dioxide dissolves in water, it also reduces the pH of water, thus causing an increase of the corrosion rate. Corrosion resulting from the presence of hydrogen sulfide is just as serious and is referred to as "sour" corrosion. Hydrogen sulfide content in extracted gas generally amounts to from one to a dozens of percent, but some gas deposits contain up to several dozen percent of hydrogen sulfide. Hydrogen sulfide causes more aggressive corrosion than carbon dioxide. Similarly to carbon dioxide, hydrogen sulfide dissolves in water, reducing pH. As a result of the reaction of hydrogen sulfide with iron, iron sulfide FeS and hydrogen gas ¾ are formed. Iron sulfide forms a coating on metal surfaces, and during the first phase, it inhibits "sour" corrosion, however even slight damage to this coating causes intensive corrosion. "Sour" corrosion causes pits to form and is also often accompanied by cracking of metal coatings caused by the production of hydrogen. Some hydrogen penetrates into steel and becomes the cause of blistering, cracking, and so-called hydrogen embrittlement.

Corrosion processes in gas wells are intensified by Desulfovibrio Desulfuricans sulfate-reducing bacteria. These bacteria are most active when under the surface of scales formed as a result of sediment deposition.

The rate of corrosion induced by carbon dioxide and hydrogen sulfide increases as the oxygen content in the system increases. Oxygen penetrates into drilling fluids when they pass through machinery servicing wells and tanks. The rate of corrosion is also dependent on temperature; the greater it is, the greater the corrosion rate, which reaches its maximum at a temperature of approx. 70°C. In wells that are not protected with corrosion inhibitors, it may even reach up to several mm/year.

Gas is saturated with water vapor in deposit conditions as a result of long-term contact of natural gas with formation water. The amount of vapor in gas depends on temperature, pressure, and salt content in the water. The amount of water vapor in gas rises during exploitation of the deposit, and the older it is, the greater the amount of water vapor in the gas. Due to pressure reduction in gas pipelines, water is released, and its presence accelerates corrosion.

The effects of corrosion processes are: reduction of the thickness of lifting casing walls and pipeline walls, deep pitting that may lead to leaks, and severe reduction of their strength properties. In order to prevent corrosion in gas wells, corrosion inhibitors reducing the corrosive action of extracted natural gas on steel parts of extraction equipment and pipelines are used. Liquid corrosion inhibitors of varying chemical nature are used as corrosion inhibitors: most frequently quaternary ammonium salts, imidazoline derivatives, fatty acid salts, and protective gaseous inhibitors, usually amines. In order to be effective, an implemented corrosion inhibitor should be dissolved in water for the purpose of neutralizing the corrosive action of the salts and acidic gases dissolved in the water.

The water-soluble corrosion inhibitor for protection of natural gas lifting casings and pipelines provides corrosion protection against substances such as: hydrogen sulfide and carbon dioxide present in the extracted gas, chlorides present in the formation water and drilling fluids, as well as the oxygen present in the water.

Patents US 3629104 and US 3758493 describe water-soluble corrosion inhibitors containing a carboxylic acid of an imidazoline derivative produced by condensation of dimerized fatty acids with diethylenetriamine.

US Patent 5759485 describes the method of producing the corrosion inhibitor by neutralization of C₂₂ tricarboxylic acids and subsequent addition of imidazoline or amidoamine.

Patent application WO 2003/054251 contains a description of the good anti- corrosion properties of ethoxylated fatty alkyl amines, particularly ethoxylated alkyl ether amines.

Patent descriptions PL 61535 and PL 85729 disclose that imidazoline inhibitors are produced in a condensation reaction of diethylenetriamine with fatty acids or naphthenic acids.

Patent descriptions PL 135655 and PL 175452 present production of an inhibitor with increased activity, which is a result of condensation of diethylenetriamine with fatty acids and is then modified using urotropine introduced during the final phase of the condensation reaction.

According to patent PL 182943, the water-soluble corrosion inhibitor contains a salt of an imidazoline derivative that constitutes the product of condensation of fatty acids with diethylenetriamine and urotropine or formaldehyde as well as low molecular carboxylic acids.

Patent application US 2004/0087448 recommends the use of the product of condensation of Q₈ unsaturated fatty acids dimmers, containing 1 or 2 double bonds, and diethylenetriamine .

In turn, US Patent 6695897 contains a description of a method of producing amidoamine by condensation of N-ethylethylenediamine and fatty acid. The product of the reaction after solubilization with acetic acid may perform the role of a water-soluble corrosion inhibitor.

Patent description US 7057050 presents a method for producing a water-soluble corrosion inhibitor. The product of this reaction is N-propyl-2-heptadecenyl imidazoline. The obtained product is transformed to a water-soluble form using acrylic acid.

Patent application WO 2006/078723 contains a description of a method of producing micro-emulsions containing imidazoline derivatives and amidoamines produced in the presence of oleic acid. The micro-emulsion also contains ethoxylated nonylphenols and acetic acid.

Patent literature contains descriptions of condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms per molecule, with ratio of diethylenetriamine to fatty acids equal to 1:0.5 - 1.0. Examples of such condensation are known from, among others, American patent descriptions US 2267965, US 2355837, and Polish patent description PL 61535.

Patent description US 5322630 discloses an imidazoline corrosion inhibitor that is the product of the reaction of unsaturated monocarboxylic acids with fatty amines, aminoamides, or fatty imidazole-amines.

Patent description RU 2394941 describes a mixture of imidazoline derivatives modified with aldimines or Schiff bases. According to this patent, the imidazoline derivative is the product of the reaction of polyamines with oleic acid or monocarboxylic acids. The imidazoline derivative is then cyanoethylated with nitriles, acrylic acid, or subjected to oxyalkylation.

The water-soluble corrosion inhibitor, produced by neutralization of tricarboxylic acid with arninoethylethanolamine and subsequently with an imidazoline derivative, amidoamine derivative, or a mixture of the two, is presented in patent description US 5759485. Patent description GB 2340505 presents a method for producing imidazoline derivatives in the process of condensation of tall oil fatty acids with aminoethylethanolamine. The inhibitor is characterized by good anti-corrosion properties, and by forming complexes with mercaptanes, it neutralizes the odour of sulfur compounds.

US Patent 5723061 and US patent application 2007/0152191 describe compositions with components including salts produced in a reaction of C₁₀-Cj2 dicarboxylic acids with polyamines.

Corrosion inhibitors that include bis-amides are described in American patents. A bis-amide that is the product of the reaction of polyamines with fatty acid dimers is described in US Patent 4614600, and the product of the reaction of polyamines with dicarboxylic acids is described in US Patent 4344861. Patent application WO 2003/054251 discloses the anti-corrosion properties of ethoxylated fatty alkyl amines, particularly ethoxylated alkyl ether amines.

Patent application US 2009/181678 recommends the use of the product of condensation of C₁₈ unsaturated fatty acids dimers (containing 1 or 2 double bonds) with diethylenetriamine. Patent application US 2007/0261842 contains a description of the corrosion inhibition process in pipelines transporting crude oil/natural gas through the application of at least one amine that boils within a temperature range of 105 - 130°C or at least one amine selected from among mono-, di-, and tri-alkylpyridine, 3-methoxypropylamine (MOPA), ethyldiisopropylamine (EDIPA); the composition of the inhibitor may additionally contain at least one imidazoline or its derivative and/or phosphorus esters and/or thioacids.

Many available corrosion inhibitors for protection of natural gas lifting casings and pipelines are insufficiently effective and require high doses in order to provide corrosion protection. It has been accepted that the level of corrosion protection at a dosage of 100 mg of corrosion inhibitor per 1 kg of corrosive medium should be greater than 80% according to standard ASTM NACE 1D182.

Most offered corrosion inhibitors destined for application in natural gas wells are based on quaternary ammonium salts. These types of compounds are totally soluble in water, which is why they are readily applied by producers. The best corrosion inhibitors are those that are very well soluble in water while leaving a layer of the corrosion inhibitor on metal surfaces. A corrosion inhibitor should provide protection for a pipeline/installation for at least 24 h from an emergency stoppage of the dosing pump. A drawback of corrosion inhibitors based on quaternary ammonium salts is that they have much lower anti-corrosion properties than inhibitors containing imidazoline derivatives, specifically, they do not provide sufficient protection against pitting corrosion.

Many available corrosion inhibitors for protection of natural gas bore-holes and pipelines are insufficiently effective and require high doses in order to provide corrosion protection. Many of them form an inhomogenous liquid after being mixed with formation water, with release of sediments and precipitation of a part of the inhibitor. This results in insufficient corrosion protection and may also be the cause of the occurrence of dangerous pitting corrosion.

An additional inconvenience of available inhibitors is their tendency to form emulsions with formation water. Others exhibit significant foaming tendencies, and the presence of foam disrupts the operation of gas well equipment.

The purpose of the invention was to develop a water-soluble corrosion inhibitor for protection of natural gas lifting casings and pipelines that would provide much better anti- corrosion properties than current corrosion inhibitors.

SUMMARY OF THE INVENTION: The present invention relates to a water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines as well as to the method of its production.

One aspect of the invention is to provide a water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines.

It was stated that a composition containing the following components exhibits good anti-corrosion properties, sufficient for protection of natural gas extraction equipment and gas pipelines:

- component a) in an amount from 0.15 to 75 % by weight, preferably from 1.5 to 35 % by weight, obtained by neutralization from 0.1 to 50 % by weight, preferably from 1 to 30 % by weight, of the new mixture of modified imidazoline derivatives, which is a product of condensation of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms per molecule and aliphatic dicarboxylic acids containing from 2 to 12 carbon atoms per molecule, which constitutes a mixture of compounds of general formulae (1) and (2),

wherein Ri : C ₁₂-C₂2 (1)

with the optional addition of from 0.05 to 20 % by weight of the known product of condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms per molecule, produced by a known method at a temperature of 180-280°C, preferably 220-260°C, of general formula (1')

wherein R₃: Ci₂-C₂₄ ( ) with an aliphatic and/or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms per molecule, used in an amount from 0.05 to 25 % by weight, in which neutralization the mass ratio of the mixture of compounds of general formulae (1), (2), and optionally ( ) to monocarboxylic acid is 1: 0.15 - 0.70, with obtaining of the final product, which is a mixture of compounds of general formulae (5), (6), and optionally (5') wherein

(5)

R4: H, C!-C₆, aromatic radical (C₆H₆)

wherein R₃: C₁₂-C2₄ (5^')

R4: H, CrC₆, aromatic radical (C₆H₆) - component b) that is oxyethylenated fatty amines containing from 14 to 22 carbon atoms per molecule and from 2 to 20, preferably from 3 to 15, ethoxyl groups per molecule, in an amount from 0.01 to 10 % by weight;

- component c) that is alkalizing agent in an amount from 0.06 to 25 % by weight, preferably from 1 to 20 % by weight;

- optional component d) that is aliphatic polyols in an amount from 0.04 to 50 % by weight;

- component e) that is aliphatic alcohols containing from 1 to 6 carbon atoms per molecule, optionally with the addition of water, in an amount from 15 to 99.7 % by weight and

- component f) that is anti-foaming agent in an amount from 0.01 to 2 % by weight.

Another aspect of the present invention is to provide the method of producing the water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines, which consists of the following stages:

I) production of component a), that is neutralization carried out at room temperature in a reaction medium containing component e), that is aliphatic alcohols containing from 1 to 6 carbon atoms per molecule, optionally with the addition of water, in an amount from 15 to 99.7 % by weight, of the new mixture of modified imidazoline derivatives that is the product of condensation of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms per molecule and aliphatic dicarboxylic acids containing from 2 to 12 carbon atoms per molecule, constituting a mixture of compounds of general formulae (1) and (2),

wherein R\: C₁₂-C₂₂ (1) H₂N NH₂

wherein R₂: C₂-C₁₂ (2) used in an amount from 0.1 to 50 % by weight, preferably from 1 to 30 % by weight, with the optional addition of 0.05 to 20 % by weight of the known product of condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms per molecule, produced by a known method at a temperature of 180-280°C, preferably 220-260°C, of general formula ( ),

wherein R₃: C₁₂-C₂₄ (H with an aliphatic and/or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms per molecule, used in an amount from 0.05 to 25 % by weight, where the mass ratio of the mixture of compounds of general formulae (1), (2), and optionally ( ) to monocarboxylic acid is 1 : 0.15 - 0.70, with obtaining of the final product, which is a mixture of compounds of general formulae (5), (6), and optionally (5'),

wherein R^ C₁₂-C₂₂ ( 5)

R₄: H, CrC₆, aromatic radical (C₆H₆)

wherein R₃: C₁₂-C24 ( 5^')

R4: H, C C₆, aromatic radical (C H₆)

II) introduction to component a), in an amount from 0.15 to 75% by weight, preferably from 1.5 to 35% by weight, and to the mentioned component e), of further inhibitor components:

component b), that is oxyethylenated fatty amines containing from 14 to 22 carbon atoms and from 2 to 20, preferably from 3 to 15, ethoxyl groups per molecule, in an amount from 0.01 to 10% by weight;

component c), which is an alkalizing agent in an amount from 0.06 to 25% by weight, preferably from 1 to 20% by weight;

optionally component d), that is aliphatic polyols in an amount from 0.04 to 50% by weight,

and finally, component f), which is an anti-foaming agent in an amount from 0.01 to 2% by weight. DESCRIPTION OF THE PREFERRED EMBODIMENTS:

It was unexpectedly noted that the application of a new mixture of modified imidazoline derivatives with better anti-corrosion properties, possibly with addition of known product of condensation of diethylenetrianine with fatty acids, neutralized with an aliphatic and/or aromatic monocarboxylic acid to form a salt, and an active surfactant from the group of oxyethylenated, hydrogenated tall oil amines with a double function: corrosion inhibitor and dispersant, in combination with a volatile amine, an anti-foaming agent, optionally with addition of aliphatic polyols, dissolved in an alcohol solvent, optionally with addition of water, resulted in obtaining of a corrosion inhibitor with increased anti-corrosion properties as compared to corrosion inhibitors containing conventional imidazoline derivatives.

In this invention, a new mixture of modified imidazoline derivatives of general formulae (1) and (2) is used,

wherein Rt: Ci₂-C₂2

wherein R₂: C₂-C₁₂ which is obtainable in such a way, that condensation of diethylenetriamine is performed with fatty acids containing 12-22 carbon atoms per molecule and aliphatic dicarboxylic acids containing 2-12 carbon atoms per molecule, where the molar ratio of diethylenetriamine to fatty acids and to aliphatic dicarboxylic acids is 1 : 0,5-0,99: 0.01-0.5, at a temperature of at least 140°C, preferably 150°C, with the formation of an aminoamide mixture of general formulae (3) and (4),

wherein R_t: C₁₂-C₂₂ (3)

with acid number < 10 mg KOH/g, and next, the temperature is raised to above 180 °C, preferably to 220 °C, and the condensation reaction is performed further until a mixture of compounds of general formulae (1) and (2) is obtained

wherein R_t: C₁₂-C22 (1)

with acid number < 1 mg KOH/g.

This new mixture of modified imidazoline derivatives forms an exceptionally durable layer on metal surfaces that protects against corrosion. The application of a volatile amine as one of the inhibitor's components, completes its anti-corrosion action in the gaseous phase.

Many available corrosion inhibitors for protection of natural gas wells and pipelines contain dispersants derived from nonylphenol among their components. Phenol groups are particularly harmful to the natural environment due to their very low biodegradation. According to this invention, the application of a surfactant from the group of oxyethylenated, hydrogenated, tall oil amines in the composition of this corrosion inhibitor, which have a very high degree of biodegradation, had a favorable impact on its biocompatibility.

There can be many embodiments of the invention depending on variants of its components and the ways they are combined. The preferred embodiments of the invention concerning components a), e), d), c) and f) are listed below.

In the preferred embodiment of the invention, the corrosion inhibitor contains as component a) a product formed by neutralization with acetic acid and/or benzoic acid of the following imidazoline derivatives:

i) the new mixture of modified imidazoline derivatives, which is condensation product of diethylenetriamine with fatty acids containing 12-22 carbon atoms per molecule and aliphatic dicarboxylic acids containing 6-10 carbon atoms per molecule, where the molar ratio of diethylenetriamine to fatty acids and to aliphatic dicarboxylic acids is 1 : 0,5-0,99: 0.01-0.5, at a temperature of at least 140°C, preferably 150°C, with the formation of an aminoamide mixture of general formulae (3) and (4),

wherein R_\: C₁₂-C₂₂ (1)

wherein R₂: C6-C₁₀ (2) with acid number < 1 mg KOH/g, ii) optionally added, the known product of condensation of diethylenetriamine with fatty acids.

In the preferred embodiment of the invention, the corrosion inhibitor contains methanol, isopropanol, ethanol, or their mixtures as component e).

In the preferred embodiment of the invention, the corrosion inhibitor contains ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol, or their mixtures as component d).

In the preferred embodiment of the invention, the corrosion inhibitor contains 3- methoxypropylamine, 2-aminoethanol (monoethanolamine), diethylamine, or their mixture as component c).

In the preferred embodiment of the invention, the corrosion inhibitor contains siloxane derivative, more preferably branched siloxane polymers as component f).

The composition of the corrosion inhibitor according to the invention has been given in percentages by weight calculated in reference to the total mass of the inhibitor. In the preferred embodiment of the invention, concerning the method of production of water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines, neutralization with glacial acetic acid is carried out of the following imidazoline derivatives : i) new mixture of modified imidazoline derivatives, which is condensation product of diethylenetriamine with fatty acids containing 12-22 carbon atoms per molecule and aliphatic dicarboxylic acids containing 6-10 carbon atoms per molecule, in which condensation the molar ratio of diethylenetriamine to fatty acids and to aliphatic dicarboxylic acids is 1 : 0,5-0,99: 0.01-0.5, at a temperature of at least 140°C, preferably 150°C, with the formation of an aminoamide mixture of general formulae (3) and (4),

with acid number < 10 mg OH/g, after which the temperature of the reaction is raised to above 180 °C, preferably to 220 °C, and as a result of the reaction, a mixture of compounds of general formulae (1) and (2) is obtained

wherein Ri: C₁₂-C₂₂ (1)

with acid number < 1 mg KOH/g, ii) optionally added the known product of condensation of diethylenetriamine with fatty acids.

The percentages of components used to produce the corrosion inhibitor using the method according to the invention have been given as percentages by weight calculated in reference to the total mass of the inhibitor.

The corrosion inhibitor produced on the basis of the mixture of modified imidazoline derivatives is characterized by better anti-corrosion and hydrophilic properties as compared to inhibitors containing known imidazoline derivatives.

The inhibitor according to this invention forms homogenous fluids with formation water containing up to 30% salt, and even at a temperature of 80°C, no precipitation of the inhibitor from these fluids is observed. The exceptional compatibility of the inhibitor that is the subject of this invention with formation water of varying salinity increases its anti- corrosion properties both in an aqueous phase and gaseous phase.

In the case where high transparency of the inhibitor that is the subject of this invention is required during long-term storage under winter conditions at a temperature below -30°C, it is beneficial to introduce a known imidazoline derivative into the composition of the inhibitor, the small addition of which causes the inhibitor according to this invention to be completely transparent.

In the case where high transparency of the inhibitor according to this invention is required during long-term storage at a temperature below -40°C, aliphatic polyols, preferably ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol, or their mixtures can be applied in an amount from 0.5 to 50% by weight, and optionally aliphatic alcohols containing from 1 to 6 carbon atoms per molecule other than methanol, isopropanol, and ethanol.

The corrosion inhibitor produced according to the method of this invention forms a stable protective film on metal surfaces and also protects against corrosion in the gaseous phase, while not allowing corrosion to occur even in the most aggressive environments containing carbon dioxide, hydrogen sulfide, and chlorides. The corrosion inhibitor according to this invention is resistant to the high temperatures present in the deposit, and does not exhibit tendencies of precipitation from formation water and precipitation of sediments. The corrosion inhibitor is effective at low doses, at continuously dosing, from 10 to 80 ppm of natural gas and formation water. Its high anti-corrosion effectiveness enables protection of extraction equipment not only against uniform corrosion, but also, above all, against pitting corrosion. It protects metal surfaces against corrosion well, also in the case of a periodical failure of the dosing system. An additional advantage of the inhibitor according to this invention is that it exhibits no tendency of foaming in the formation water-inhibitor system.

One of the numerous versions of the corrosion inhibitor according to this invention contains benzoic acid, which may act as a bactericide.

In practice, water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines, according to the invention, is added to the gas - water continuously.

Corrosion inhibitor according to the invention, in general, is added to the fluid from about 0,01 to 5000 ppm, preferably from about 1 to 500 ppm, the most preferably from about 10 to 100 ppm.

The examples given below illustrate the invention while not limiting its scope.

Exemples from 1 to 5 concern the production of new mixture of modified imidazoline derivatives, and examples from 6 to 11 concern the production of the corrosion inhibitor according to the invention.

Example 1.

The following components were introduced into a reactor: 103.16 kg (1 mole) diethylenetriamine, 141.23 kg (0.5 mole) distilled olein, in which the main component is oleic acid C₁₈H₃4C>2, and 45.02 kg (0.5 mole) oxalic acid. The content was heated while being mixed constantly with a mechanical stirrer, and nitrogen barbotage was additionally applied in order to remove the water forming during the reaction. After a temperature of 150°C was achieved, it was maintained for 3 hours until an acid number of 3.51 mg KOH/g was obtained, and after that, further heating was applied until the temperature of 220°C was achieved. The reaction was performed for 4 hours while the temperature was maintained constant at 220°C and while nitrogen barbotage was applied for the purpose of removing water from the reaction. 226 kg of product with acid number 0.25 mg KOH/g were obtained.

Example 2.

The following components were introduced into a reactor: 103.16 kg (1 mole) diethylenetriamine, 279.64 kg (0.99 mole) oleic acid, and 1.88 kg (0.01 mole) azelaic acid. The content was heated while being mixed constantly with a mechanical stirrer, and nitrogen barbotage was additionally applied in order to remove the water forming during the reaction. After a temperature of 150°C was achieved, it was maintained for 3 hours (acid number 4.32 mg KOH/g was obtained), and after that, further heating was applied until the temperature of 220°C was achieved. The reaction was performed for 5 hours while the temperature was maintained constant at 220°C and while nitrogen barbotage was applied for the purpose of removing water from the reaction. 317 kg of product (mixture of modified imidazoline derivatives) with acid number = 0.38 mg KOH/g were obtained.

Example 3.

The following components were introduced into a reactor: 103.16 kg (1 mole) diethylenetriamine, 264.10 kg (0.95 mole) tall oil fatty acids, and 10.11 kg (0.05 mole) sebacic acid. The content was heated while being mixed constantly with a mechanical stirrer, and nitrogen barbotage was additionally applied in order to remove the water forming during the reaction. After a temperature of 150°C was achieved, it was maintained for 3 hours (acid number 5.1 mg KOH/g was obtained), and after that, further heating was applied until the temperature of 220°C was achieved. The reaction was performed for 5 hours while the temperature was maintained constant at 220°C and while nitrogen barbotage was applied for the purpose of removing water from the reaction. 308 kg of product (mixture of modified imidazoline derivatives) with acid number 0.7 mg KOH/g were obtained. Example 4.

The following components were introduced into a reactor: 103.16 kg (1 mole) diethylenetriamine, 268.34 kg (0.95 mole) distilled olein, in which the main component is oleic acid C₁₈H₃₄0₂, and 5.90 kg (0.05 mole) succinic acid. The content was heated while being mixed constantly with a mechanical stirrer, and nitrogen barbotage was additionally applied in order to remove the water forming during the reaction. After a temperature of 150°C was achieved, it was maintained for 3 hours (acid number 3.94 mg KOH/g was obtained), and after that, further heating was applied until the temperature of 210°C was achieved. The reaction was performed for 5 hours while the temperature was maintained constant at 210°C and while nitrogen barbotage was applied for the purpose of removing water from the reaction. 312 kg of product (mixture of modified imidazoline derivatives) with acid number 0.24 mg KOH/g were obtained.

Example 5.

The following components were introduced into a reactor: 103.16 kg (1 mole) diethylenetriamine, 268.34 kg (0.95 mole) distilled olein, in which the main component is oleic acid 0₁₈Η₃₄0₂ and 7.67 kg (0.05 mole) adipic acid. The content was heated while being mixed continuously with a mechanical stirrer and at the same time, a 100 mm Hg vacuum was applied in order to remove water from the reaction. After a temperature of 150°C was achieved, it was maintained for 3 hours (acid number = 4.72 mg KOH/g was obtained), and after that, further heating was applied until the temperature of 220°C was achieved. The reaction was performed for 5 hours while the temperature was maintained constant at 220°C and while a 100 mmHg vacuum was applied for the purpose of removing water from the reaction. 299 kg of product (mixture of modified imidazoline derivatives) with acid number 0.33 mg KOH/g were obtained. Example 6.

The following components were introduced into a reactor: 440.9 kg (44.09 % by weight) of methyl alcohol, 400 kg (40 % by weight) of isopropyl alcohol, and then 66 kg (6.6 % by weight) of the product of condensation of diethylenetriamine with distilled olein and sebacic acid, produced according to example 3, with acid number 0.7 mg KOH/g, with the difference that in the condensation process instead of tall oil fatty acids distilled olein was used in the amount of 0.95 mole for 1 mole of diethylenetriamine and 0.05 mole of sebacic acid. After complete dissolution, 33 kg (3.3 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, 10 kg (1% by weight) of oxyethylenated hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule and 20 kg (2 % by weight) of glycerin were added. After complete dissolution, 30 kg (3 % by weight) of 3-methoxypropyloamine and 0.1 kg (0.01 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732 from the Miinzing company were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear, low- viscosity liquid with a poor point below - 60 °C and a kinematic viscosity of 2.7 mm²/s at a temperature of 20°C.

Example 7.

The following components were introduced into a reactor: 405.0 kg (40.5 % by weight) of methyl alcohol, 302 kg (30.2 % by weight) of isopropyl alcohol, and then 150 kg (15.0 % by weight) of the product of condensation of diethylenetriamine with the fatty acids of tall oil and azelaic acid, produced according to example 2, with acid number 0.4 mg KOH/g, with the difference that in the condensation process instead of oleic acid tall oil fatty acids were used in the amount of 0.99 mole for 1 mole of diethylenetriamine and 0.01 mole of azelaic acid. After complete dissolution, 90 kg (9 % by weight) of benzoic acid were added. After the reaction was fully completed at room temperature to neutral pH, 7 kg (0.7 % by weight) of ethoxylated hydrogenated tall oil amine, containing 6 ethoxyl groups per molecule and 5 kg (0.5 % by weight) of ethylene glycol were added. After complete dissolution, 40 kg (4% by weight) of 3-methoxypropyloamine and then 1 kg (0.1 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732 from the Miinzing company were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear, low- viscosity liquid with a poor point of - 60 °C and a kinematic viscosity of 7.6 mm²/s at a temperature of 20°C.

Example 8.

The following components were introduced into a reactor: 79 kg (7.9 % by weight) of water, 150 kg (15 % by weight) of isopropanol, 100 kg (10 % by weight) of ethanol, and 200 kg (20 % by weight) of the product of condensation of diethylenetriamine, tall oil acids, and adipic acid, produced according to example 5, with acid number 0.3 mg KOH/g, with the difference that in the condensation process instead of distilled olein tall oil fatty acids were used in the amount of 0.95 mole for 1 mole of diethylenetriamine and 0.05 mole of adipic acid. After complete dissolution, 1 10 kg (1 1 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, 100 kg (10 % by weight) of oxyethylenated hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule were added. After complete dissolution, 50 kg (5 % by weight) of 3- methoxypropyloamine, 100 kg (10 % by weight) of monoethanolamine, 100 kg (10% by weight) of diethylamine, 10 kg (1 % by weight) of dipropylene glycol monomethyl ether, and then 1 kg (0.1 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732 from the Miinzing company, were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear liquid with a poor point of - 30 °C and a kinematic viscosity of 37 mm /s at a temperature of 20°C.

Example 9.

The following components were introduced into a reactor: 770 kg (77% by weight) methyl alcohol, 80 kg (8 % by weight) of the product of condensation of diethylenetriamine, distilled olein, in which the main component is oleic acid C₁₈H3₄0₂ and succinic acid, produced according to example 4, with acid number 0.25 mg KOH/g, and 20 kg (2 % by weight) of the known product of condensation of diethylenetriamine and oleic acid. After complete dissolution, 40 kg (4 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, 10 kg (1 % by weight) of oxyethylenated, hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule, were added, and after the temperature was lowered to room temperature, 40 kg (4 % by weight) of 3-methoxypropyloamine and 30 kg (3 % by weight) of diethylamine, and then 10 kg (1 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732, from the Miinzing company, were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear, low-viscosity liquid with a poor point below - 60 °C, a kinematic viscosity of 4.5 mm²/s at a temperature of 20°C, and high transparency during storage at a temperature of -40°C for a period of 1 year.

Example 10.

The following components were introduced into a reactor: 177.9 kg (17.79 % by weight) of isopropyl alcohol, and then 500 kg (50 % by weight) of the product of condensation of diethylenetriamine with oleic acid (oleic acid C₁₈H₃₄0₂ is the main component in distilled olein) and oxalic acid, produced according to example 1 , with acid number 0.25 mg KOH/g. After complete dissolution, 250 kg (25 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, 0.1 kg (0.01 % by weight) of oxyethylenated hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule, and 50 kg (5 % by weight) of diethylene glycol butyl ether were added. Next, 1 kg (0.1 % by weight) monoethanolamine and 1 kg (0.1 % by weight) diethylamine, and then 20 kg (2 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732, from the Miinzing company, were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear liquid with a poor point of - 45 °C and a kinematic viscosity of 57 mm²/s at a temperature of 20°C. Example 11.

The following components were introduced into a reactor: 596.72 kg (59.672 % by weight) of methyl alcohol, 400 kg (40 % by weight) of isopropyl alcohol, and then 1.32 kg (0.132 % by weight) of the product of condensation of diethylenetriamine with distilled olein (oleic acid C₁₈H3402 is the main component in distilled olein) and sebacic acid, produced according to example 3, with acid number 0.7 mg KOH/g, with the difference that in the condensation process instead of tall oil fatty acids distilled olein was used in the amount of 0.95 mole for 1 mole of diethylenetriamine and 0.05 mole of sebacic acid. After complete dissolution, 0.66 kg (0.066 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, 0.2 kg (0.02 % by weight) of oxyethylenated hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule, and 0.4 kg (0.04 % by weight) of propylene glycol were added. After complete dissolution, 0.6 kg (0.06 % by weight) of 3-methoxypropyloamine and 0.1 kg (0.01 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732 from the Miinzing company were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear, low-viscosity liquid with a poor point below - 60 °C and a kinematic viscosity of 1.2 mm²/s at a temperature of 20°C.

In gas wells equipped with high-output dosing pumps, a corrosion inhibitor with low kinematic and dynamic viscosity over a wide temperature range is required, and thus, a low content of active components is also required. Required inhibitor dosages may be 1000, 2000, or 3000 ppm for water-gas system while continuous dosing. The corrosion inhibitor according to example 11 is destined for such dosing pumps. Example 12 - comparative.

The following components were introduced into a reactor: 440.9 kg (44.09 % by weight) of methyl alcohol, 400 kg (40 % by weight) of isopropyl alcohol, and then 66 kg (6.6 % by weight) of the known product of condensation of diethylenetriamine with distilled olein according to formula (Γ), with acid number 1.1 mg KOH/g. After complete dissolution, 33 kg (3.3 % by weight) of glacial acetic acid were added. After the reaction was fully completed at room temperature to neutral pH, a product with formula (5') was obtained.

Next, 10 kg (1 % by weight) of oxyethylenated, hydrogenated tall oil amine, containing 5 ethoxyl groups per molecule, and 20 kg (2 % by weight) of glycerin were added. After complete dissolution, 30 kg (3 % by weight) of 3-methoxypropyloamine and 0.1 kg (0.01 % by weight) of a siloxane derivative with the commercial name Foam Ban HP 732 from the Miinzing company were added. After complete dissolution at room temperature, 1000 kg (100 % by weight) of corrosion inhibitor were obtained, which is a clear, low- viscosity liquid with a poor point below - 60 °C and a kinematic viscosity of 2.9 mm /s at a temperature of 20°C.

Example 13.

Tests of the anti-corrosion properties of the water-soluble corrosion inhibitor for protection of natural gas bore-holes and pipelines according to this invention were performed according to the Wheel Test in accordance with standard ASTM NACE 1 D 182 "Wheel test method used for evaluation of film-persistent corrosion inhibitors for Oilfield applications". This is a conventional method of testing mass decrement, used to evaluate the effectiveness of an inhibitor through simulation of continuous flow of a corrosive medium.

A. Preparation of corrosive water: corrosive water was prepared according to the following composition: 9.62 % by weight NaCl and 0.305 % by weight CaCl₂ and 0.186 % by weight MgCl₂-6H₂0 and 89.89 % by weight distilled water. The water was subjected to nitrogen barbotage for 30 minutes, and then to carbon dioxide barbotage for approx. 10 minutes until the achievement of corrosive water pH within the range of 4.4 to 4.8. B. Preparation of paraffin oil (mixture of isoparaffmic hydrocarbons): oil was homogenized at a temperature of 62°C, and then poured into test bottles. C. Preparation of metal samples: metal plates of„Sand blasted mild steel Shim stock" type, with dimensions of 0.13x12.7x76 mm were rinsed with acetone, dried with a dry cloth, weighed, and stored in a desiccator.

90 ml corrosive water and 10 ml paraffin oil were added into bottled with a capacity of 200 ml from which air had been removed earlier. Next, the inhibitor according to the invention from example 6, 7, 8, 9, 10 was added in the amount of 30, 50, and 80 ppm by weight, and the inhibitor according to the invention from example 11 in the amount of 1500, 2500 ppm by weight, to the corrosive medium. The metal plates described in point C) were introduced into the thus prepared bottles. Carbon dioxide was once again dosed into the bottles over a time of approx. 30 s, and bottles were hermetically closed. The bottles were placed in a thermostat at a temperature of 65.5°C, in a rotating apparatus that rotated with a speed of 15 rotations/minute. The test was performed for a period of 72 hours. After the test, metal samples were removed from bottles, rinsed with isopropyl alcohol, and subjected to the action of a 10 % hydrochloric acid solution for a period of 10 - 15 seconds. Metal samples were then rinsed with water, acetone, and alcohol, after which they were weighed with an accuracy to 0.1 mg. The mass decrement of metal samples was assessed, and the possible presence of pitting corrosion was also assessed.

The percentage of protection against corrosion was calculated from the mass decrement of the metal sample in the presence of the inhibitor W(inhib) and without the inhibitor W(0). Percentage of protection, % P = W (0) - W(inhib) / W(0) x 100%

The results of tests of the anti-corrosion properties of corrosion inhibitors according to examples 6, 7, 8, 10, and 11 containing a neutralized, new mixture of modified imidazoline derivatives according to the invention, according to formula (5) and (6), as well as the results of tests of anti-corrosion properties of the corrosion inhibitor according to example 9, containing a neutralized mixture of modified imidazoline derivatives according to the invention, according to formula (5), (6), and (5'), in comparison to the corrosion inhibitor produced according to example 12 containing a neutralized known product produced by a known method in the reaction of condensation of diethylenetriamine with oleic acid according to formula (5') in place of the neutralized mixture of modified imidazoline derivatives according to formula (5) and (6), are presented in the table below. Water-soluble corrosion inhibitor according to the invention, Neutralized known containing a neutralized mixture of modified imidazoline product produced by a derivatives, according to formulae (5), (6) in examples 6, 7, 8, 10, known method in the 11 and a neutralized mixture of modified imidazoline derivatives reaction of according to the invention according to formulae (5), (6), and (5') condensation of in example 9 diethylenetriamine with oleic acid according to formula (5')

According to 6 7 8 9 10 11 12

example

Concentration of [% protection [% protection] corrosion inhibitor

in corrosive

medium

[ppm by weight]

30 72 91 96 82 97 - 53

50 80 92 98 86 98 - 69

80 94 96 98 95 98 - 85

1500 - - - ^■ - - 71

2500 - - - - - 81

INDUSTRIAL APPLICABILITY

The above examples proved that the water-soluble corrosion inhibitor for protection of lifting casings and natural gas pipelines as well as the method of its production, according to this invention are expected to find industrial applicability.

Claims

1. The water-soluble corrosion inhibitor for protection of natural gas lifting casings and pipelines containing imidazoline derivatives, oxyethylenated fatty amines, low-boiling amines and alcohol solvents, characterized in that it contains:

- component a) in an amount from 0.15 to 75 % by weight, preferably from 1.5 to 35 % by weight, obtained by neutralization from 0.1 to 50 % by weight, preferably from 1 to 30 % by weight, of the new mixture of modified imidazoline derivatives, which is a product of condensation of diethylenetriamine with fatty acids containing from 12 to 22 carbon atoms per molecule and aliphatic dicarboxylic acids containing from 2 to 12 carbon atoms per molecule, which constitutes a mixture of substances of general formulae (1) and (2),

wherein Ri: C₁₂-C₂2 (1)

wherein R₂: C₂-C₁₂ (2),

with the optional addition of from 0.05 to 20 % by weight of the known product of condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms per molecule, produced by a known method at a temperature of 180-280°C, preferably 220-260°C, of general formula ( )

wherein R₃: C₁2-C₂₄ ( ) with an aliphatic and/or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms per molecule, used in an amount from 0.05 to 25 % by weight, where the mass ratio of the mixture of compounds of general formulae (1), (2), and optionally ( ) to monocarboxylic acid is 1 : 0.15 - 0.70, with obtaining of the final product, which is a mixture of compounds of general formulae (5), (6), and optionally (5')

wherein Ri: C₁₂-C₂2 (5)

R₄: H, Q-Cs, aromatic radical (C₆H₆)

wherein R₂: C2-Q2 (6) R4: H, C_!-C₆, aromatic radical (C₆H )

wherein R₃: C₁₂-C24 (5^')

¾: H, CrC₆, aromatic radical (C₆H₆)

- component b) that is oxyethylenated fatty amines containing from 14 to 22 carbon atoms per molecule and from 2 to 20, preferably from 3 to 15, ethoxyl groups per molecule, in an amount from 0.01 to 10 % by weight;

- optional component d) that is aliphatic polyols in an amount from 0.04 to 50 % by weight; *

2. The corrosion inhibitor according to claim 1, characterized in that it contains as component a) a product formed by neutralization with acetic acid and/or benzoic acid of the following imidazoline derivatives:

wherein Ri: C₁₂-C₂₂ ( 3)

wherein R₂: C₆-C₁₀ ( 4)

with acid number < 10 mg KOH/g, and next, the temperature is raised to above 180°C, preferably to 220°C, and the condensation reaction is performed further until a mixture of compounds of general formulae (1) and (2) is obtained

with acid number < 1 mg KOH/g, ii) optionally added, the known product of condensation of diethylenetriamine with fatty acids.

3. The corrosion inhibitor according to claim 1 or 2, characterized in that as component e) it contains methanol, isopropanol, ethanol, or their mixtures.

4. The corrosion inhibitor according to claim 1 or 2, characterized in that as component d) it contains ethylene glycol, glycerin, propylene glycol, dipropylene glycol, tripropylene glycol, or their mixtures.

5. The corrosion inhibitor according to claim 1 or 2, characterized in that as component c) it contains 3-methoxypropylamine, 2-aminoethanol (monoethanolamine), diethyloamine, or their mixtures.

6. The corrosion inhibitor according to claims 1 or 2, characterized in that as component f) it contains a siloxane derivative, preferably with branched siloxane polymers.

7. The method of production of the water-soluble corrosion inhibitor for protection of natural gas lifting casings and pipelines encompassing neutralization of the imidazoline derivative and addition of further inhibitor components, characterized in that it consists of the following stages:

wherein R_\ : Ci₂-C₂₂ (1)

wherein R₂: C₂-C₁₂ (2) used in an amount from 0.1 to 50 % by weight, preferably from 1 to 30 % by weight, with the optional addition of 0.05 to 20 % by weight of the known product of condensation of diethylenetriamine with fatty acids containing from 12 to 24 carbon atoms per molecule, produced by a known method at a temperature of 180-280°C, preferably 220-260°C, of general formula (Γ),

wherein R₃: C₁₂-C₂₄ with an aliphatic and/or aromatic monocarboxylic acid containing from 1 to 7 carbon atoms per molecule, used in an amount from 0.05 to 25 % by weight, where the mass ratio of the mixture of compounds of general formulae (1), (2), and optionally (Γ) to monocarboxylic acid is 1 : 0.15 - 0.70, with obtaining of the final product, which is a mixture of compounds of general formulae (5), (6), and optionally (5'),

wherein Rj: C₁₂-C₂₂ ( 5) R4: H, Q-Q, aromatic radical (C₆H )

wherein R₃: C₁₂-C24 ( 5^') R4: H, Ci-C , aromatic radical (C₆H₆)

II. introduction to component a), in an amount from 0.15 to 75 % by weight, preferably from 1.5 to 35 % by weight, and to the mentioned component e), of further inhibitor components:

component b), that is oxyethylenated fatty amines containing from 14 to 22 carbon atoms and from 2 to 20, preferably from 3 to 15, ethoxyl groups per molecule, in an amount from 0.01 to 10 % by weight;

component c), which is an alkalizing agent in an amount from 0.06 to 25 % by weight, preferably from 1 to 20 % by weight; optionally component d), that is aliphatic polyols in an amount from 0.04 to 50 % by weight,

and finally, component f), which is an anti-foaming agent in an amount from 0.01 to 2 % by weight.

8. The method according to claim 7, characterized in that in I stage, neutralization with glacial acetic acid is carried out of the following imidazoline derivatives:

i) the new mixture of modified imidazoline derivatives, which is condensation product of diethylenetriamine with fatty acids containing 12-22 carbon atoms per molecule and aliphatic dicarboxylic acids containing 6-10 carbon atoms per molecule, in which condensation the molar ratio of diethylenetriamine to fatty acids and to aliphatic dicarboxylic acids is 1 :0,5-0,99: 0.01-0.5, at a temperature of at least 140°C, preferably 150°C, with the formation of an aminoamide mixture of general formulas (3) and (4),

with acid number < 10 mg KOH/g, after which the temperature of the reaction is raised to above 180°C, preferably to 220°C, and as a result of the reaction, a mixture of compounds of general formulae (1) and (2) is obtained

with acid number < 1 mg KOH/g,

ii) optionally added the known product of condensation of diethylenetriamine with fatty acids.