RU2122046C1 - Composition for inhibiting corrosion into hydrogen sulfide in oxygen-containing oil field media - Google Patents

Abstract

FIELD: petroleum-extractive industry, more particularly control on corrosion of oil field equipment. SUBSTANCE: claimed composition comprises 2-alkylimidazolines of stillage residues resulting from production of synthetic fatty acids; 12.0-15.0 wt. % surfactant; 3.0-5.0 wt.% cracking residue resulting from oil refining; 5.0-8.0 hydrocarbon solvent containing aromatic hydrocarbons, e. g. aromatic nephras A 120/200 or A 150/330, the balance. The degree of protection of steel in oil field media having high oxygen content in hydrogen sulfide is 85-96%. EFFECT: improved properties of the composition. 1 tbl

Description

 The invention relates to the oil industry and is intended to combat corrosion of oilfield equipment in hydrogen sulfide and oxygen-containing oilfield environments.

 Currently, a wide range of complex chemical compositions are used to combat corrosion. So, the corrosion inhibitor Neftekhim-3 is known, which is a hydrocarbon solution of the condensation product of light tall oil acids and N, N-di (cyanoethyl) ethylenediamine-1,2 aminonitrile [1]. The disadvantages of this inhibitor include the complexity of the synthesis of the corresponding aminonitrile, its high cost, low protection efficiency in oxygen-containing oilfield environments.

To prevent steel corrosion in mineralized aggressive environments with a high oxygen content, it is known to use a composition containing the salt of bottoms of synthetic fatty acids with monoethanolamine, ethoxylated alkyl phenols, the product of the condensation of phenol with tetramethylmethylene diamine, the head fraction of the production of butyl alcohols and an aromatic solvent [2]. The multicomponent composition of the composition substantially complicates the technology for its preparation. In addition, the composition has a sufficiently high pour point (minus 29 - 33 ^o C), which narrows the possibilities of its use.

 The closest to the proposed composition by technical nature (prototype) is the URAL-78 inhibitor used to combat corrosion in hydrogen sulfide-containing media, which is a mixture of salts of nitrogen-containing compounds and tall oil fatty acids with toluene, agidol, and surface-active substances [3]. The disadvantage of this inhibitor is the low effectiveness in mineralized oxygen-containing environments, low flash point, which makes it an extremely combustible reagent.

 The problem solved by the invention is to increase the efficiency of protecting oilfield equipment from corrosion in mineralized hydrogen sulfide and oxygen-containing environments.

The problem is solved by the use of a composition based on nitrogen-containing compounds, a surfactant and a solvent containing, as nitrogen-containing compounds, 2 - alkylimidazolines bottoms from the production of synthetic fatty acids (FFA), as a surfactant - OP-7 or OP-10, and as a solvent, a hydrocarbon solvent containing aromatic hydrocarbons, for example, aromatic nefras A 120/200 or A 150/330, and additionally the cracking residue of the refinery and in the following ratio of components, wt.%:
Alkylimidazolines bottoms produced by SJK - 12 - 15
Surfactant OP-7 (OP-10) - 3 - 5
Cracking residue - 5 - 8
Hydrocarbon Solvent - Else
The inventive composition is prepared by mixing at a temperature of 70 - 80 ^o C 2-alkylimidazolines bottoms production of FFA obtained by the interaction of bottoms with ethylene diamine, a surfactant, a cracking residue and a hydrocarbon solvent, for example, nefras in a mixing device for 1 to 2 hours.

The finished product has the following indicators:
Appearance - Dark brown liquid
Density at 20 ^o C, g / cm ³ - 0.89 - 0.92
Kinematic viscosity at 20 ^o C, cSt - Not more than 9.8
Pour point, ^o C - Not higher than minus 35
Flash point in a closed crucible, ^o C - Not lower than 35
The test of the protective effect of a corrosion inhibitor was carried out in laboratory conditions according to OST 39-099-79 "Corrosion inhibitors. Method for assessing the effectiveness of the protective effect of corrosion inhibitors in oilfield wastewater", VNIISPTneft, 1980.

As the corrosive media used wastewater model (MSW) composition, g / l: Na ⁺ = 43.83; Ca ²⁺ = 3.98; Mg ²⁺ = 1.51; Cl ^- = 79.04; SO $\genfrac{}{}{0ex}{}{\text{2-}}{\text{4}}$ = 0.21. Total mineralization = 128.57 g / l. The oxygen content in the MSW was 0–5 mg / L, and that of hydrogen sulfide was 100–400 mg / L and was determined by titrometric methods. The dosage of the composition is 50-100 mg / l.

As metal samples, pre-processed samples of steel 08 KP (GOST 1050-74) were tested. The test time was 6 hours. After the test time, the samples were subjected to appropriate processing and the corrosion rate (v) and degree of protection (z) were determined by the formulas
v = (mn) / (s • t),
Where
m is the mass of the metal sample before being placed in an aggressive environment, g;
n is the mass of the sample after the end of the experiment, g;
s is the area of the sample, m ² ;
t is the test time, h,
z = (v ₁ -v ₂ ) • 100 / v ₁ ,%,
where v ₁ - corrosion rate in non-inhibited environment, g / (m ² • h);
v ₂ - corrosion rate in an environment with an inhibitor, g / (m ² • h).

 The table shows the test results using the inventive composition and the selected prototype.

Based on the tests, we can conclude that the inventive composition is an effective corrosion inhibitor of carbon steels in hydrogen sulfide - and oxygen-containing environments. It is characteristic that with an increase in the hydrogen sulfide content in the MSW, the protection efficiency using the inventive composition also increases. By determining the flash point (GOST 6356-75), it was found that for the claimed composition it is 35 ^o C, which is significantly higher than that of the selected prototype. In this regard, the claimed composition is less fire and explosive than the prototype.

By determining the pour point (GOST 20287-91), it was found that the inventive composition freezes at a temperature not higher than minus 35 ^o C, which is lower than that of the prototype (not higher minus 30 ^o C) [3].

 Thus, the advantages of the claimed composition are: a higher degree of protection of steel against corrosion in environments with a high content of hydrogen sulfide and oxygen (85 - 96%), a higher flash point, lower pour point of the composition, allowing its use in winter conditions, use when obtaining the composition of non-utilizable wastes - bottoms of FFA and cracked residues of oil refining production.

List of sources used
1. Corrosion inhibitor Neftekhim-3. TU-38 of the Ukrainian SSR 201.479.89. - Drohobych.

 2. USSR author's certificate N 1826551, cl. C 3 F 11/08.

 3. Corrosion inhibitor Ural-78 TU 38.401-66-77-92.- Ufa.

Claims (1)

Composition for inhibiting corrosion in hydrogen sulfide and oxygen-containing oilfield media based on nitrogen-containing compounds, a surfactant and a solvent, characterized in that it additionally contains a cracking residue of the oil refinery, as nitrogen-containing compounds contains 2-alkylimidazolines bottoms production of synthetic fatty acids as a surfactant, OP-7 or OP-10, and as a solvent, a hydrocarbon solvent containing aroma of sul hydrocarbons, with the following component ratio, wt.%:
2-Alkylimidazolines bottoms production of synthetic fatty acids - 12 - 15
Surfactant OP-7 (OP-10) - 3 - 5
Cracking residue of oil refining - 5 - 8
Hydrocarbon Solvent - Else

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