FR2774399A1 - New corrosion inhibitor compositions based on salts of mercapto acids and imidazoline(s) - Google Patents

Abstract

Corrosion inhibitor compositions for iron and ferrous metals in carbonated salt solutions comprise an active constituent based on an alkyl-poly(ethylamino)-imidazoline or 2-alkyl 3-(ethyl-amino)-1,3,diazoline of formula (I) and a mercaptoacid of formula R1-(R2CR3)-R4CR5-A (II). R = 10-22C hydrocarbyl(optionally unsaturated); n = 0-3; n = 0-3; R1 = H or SH ; R2 and R3 = 1 - 4C, CON(R6)(R7), COOR8; R4 and R5 = OH, NH2 or SH (when R1 is not SH); R6 and R7 = H, 1-4C; R8 = H, 1-8C; R2-R5 may be included in an aliphatic ring ; R3-R5 may be included in an aromatic ring when n = 1; and A = COOH, SO3H, OSO3H, PO3H or OPO3H. The molar ratio of the mercaptoacid component(s) to the imidazoline component(s) is between 1.0 to 1.5. Also claimed is a process for the inhibition of iron and ferrous metals using the new compositions as above.

Description

 The present invention relates to the inhibition of corrosion of iron and ferrous metals in carbon brines, and more particularly to the improvement of the corrosion inhibitors used for this purpose.

 By carbonic brines is meant within the meaning of the invention, aqueous solutions charged with mineral salts and saturated with carbon dioxide. It has recently been recognized (French patent application n09703286) the inhibitory efficacy in such a medium of compositions based on poly (ethyleneamino) imidazoline thioglycolates. The corrosive media encountered in petroleum exploitation are generally two-phase media, consisting of hydrocarbons and such carbonic brines.

The compositions based on poly (ethyleneamino) imidazoline thioglycolates prove to be very effective in such media when the aqueous phase is not very salty (1 g / l of NaCl). However, it has been found that their effectiveness decreases when the hydrocarbon phase is a crude oil and the aqueous phase is very salty.

 This gives, and this is the subject of the present invention, a very significant improvement in the performance of inhibitors based on mercaptocarboxylates, and more particularly mercaptoacetates or mercaptopropionates of poly (ethyleneamino) imidazolines when they are combined with cationic, amphoteric and nonionic surfactants from the group consisting of alkyltrimethyl- or alkyldimethylbenzylammonium salts, alkylaminopropionic acids and oxyethylated alkylamines, in which the alkyl chain is a saturated or unsaturated chain containing from 12 to 22 carbon atoms. This effect is unexpected; it is not impossible that it is due to the improvement in the partition of the imidazoline thioglycolates between the oily phase and the aqueous phase.

dans laquelle R est une chaîne hydrocarbonée linéaire ou ramifiée, saturée ou insaturée comportant de 10 à 22 atomes de carbone, et où n est un nombre de 0 à 3, et d'acides mercaptocarboxyliques, en particulier l'acide mercaptoacétique (acide thioglycolique) ou l'acide mercaptopropionique, pris dans un rapport molaire de 1,0 à 1,5.The imidazoline mercaptocarboxylates of the invention are the combinations of alkyl-poly (ethyleneamino) imidazolines or 2-alkyl poly (ethyleneamino) -3 diazolines-1,3, corresponding to the general formula

in which R is a linear or branched, saturated or unsaturated hydrocarbon chain containing from 10 to 22 carbon atoms, and where n is a number from 0 to 3, and mercaptocarboxylic acids, in particular mercaptoacetic acid (thioglycolic acid) or mercaptopropionic acid, taken in a molar ratio of 1.0 to 1.5.

 The alkyl poly (ethyleneamino) imidazolines used in the compositions according to the invention are obtained in known manner by condensation with cyclization of fatty acids, saturated or unsaturated, with 10-22 carbon atoms, with polyethylene polyamines ( diethylene triamine DETA and its higher counterparts, triethylene tetramine TETA, tetraethylene pentamine TEPA, pentaethylene hexamine PEHA).

These imidazolines are obtained under conditions well known to those skilled in the art (introduction of the polyamine into the molten fatty acid, in the presence of oxalic acid acting as a cyclization accelerator, temperature rise up to 2000C - 2200C and hold level until the condensate water has left completely).

 The compositions according to the invention are solutions in a water-miscible solvent, for example isobutanol, butyl glycol, monoethylene glycol, monopropylene glycol, alone, as a mixture or as a mixture with water, from 20 to 40 % by weight of imidazoline mercaptocarboxylate. They typically comprise 20 to 40 k of imidazoline mercaptocarboxylate, 2 to 5 of quaternary ammonium, 2 to 5 W of amphoteric, and 2 to 10 of oxyethylenated amine. They are easily prepared by simple cold or lukewarm mixing of their constituents.

 They are used at effective concentrations of 5 to 200 ppm, preferably around 6 ppm, counted as the imidazoline mercaptocarboxylate component of the preparation.

EXAMPLE
The effectiveness of a formula according to the invention was tested under the operating conditions which are described below.

The corrosive medium consists of 10 W of Gabonese crude oil taken on site and 90 W of site water reconstituted with the following composition
SrCl2, 6H2O 0.34 g / l
BaCl2, 2H20 0.2 g / l
MgCl2, 6H20 33.77 g / l
KCl 6.43 g / l
CaCl2, 2H20 21.5 g / l
FeCl2, 4H20 0.06 g / l
NaCl 277.5 g / l
At the time of the test, 1.8 g / l of acetic acid are added and acidified with a strong acid (HCl) to reach a pH of 5.5. It is deaerated with nitrogen for one hour, then saturated with CO2 for one hour. 0.05 g / l of NaHCO3 is added, the CO2 bubbling is started again and the temperature is raised to 800C, which takes about 1/2 hour.

 The corrosion rate of the steel in the brine is measured by polarization resistance, a measurement repeated every 1/4 hour for one hour. Gabon crude oil is then added (10 W relative to the brine) previously saturated with CO2 and brought to 800, and the corrosion rate is continued to be monitored by measuring polarization resistance every 1/4 hour for a further one hour.

20 ppm of corrosion inhibitor (counted as imidazoline mercaptocarboxylate) are then added and the evolution of the corrosion rate is monitored by measurement of polarization resistance carried out every 1/4 hour for four hours.

The inhibitor composition according to the prior art consists (percent by weight) of
Imidazoline 25
Mercaptoacetic acid 5
Butylglycol 25
Monoethylene glycol 25
Water 20
The inhibitory composition according to the invention consists (percent by weight) of
Imidazoline 20
Mercaptopropionic acid 5
Monopropylene glycol 60
Copra dimethylbenzylammonium chloride 50
5%
Copra-monoamine with 11 ethylene oxides 5k
60% copra aminopropionic acid 5 compositions in which imidazoline was obtained, according to a known process, by hot condensation of 1 mole of rapeseed fatty acid with 1.15 mole of tetraethylenepentamine (TEPA) in the presence of 1 k by weight of oxalic acid bihydrate. The dimethylbenzylammonium copra chloride used is NoramiumDAS0 from
CECA SA which is a presentation with 50% of active matter, the oxyethylenated copra-monoamine is the oxyethylenated product with on average 11 molecules of ethylene oxide, marketed by
CECA SA under the name of NoramoxCll, and copra aminopropionic acid is the AmphoramCPl of CECA SA, which is a commercial presentation with 60% active ingredient.

 The variations in the corrosion rate as a function of time in the presence of 20 ppm respectively of the formulation according to the prior art and of the formulation according to the invention are shown in FIG. 1. It is observed that the values of the corrosion rate residual after 8 hours 30 of contact is established at 0.60 mm / year with the inhibitor according to the prior art, and at 0.035 mm / year with the inhibitor according to the invention.

Claims (4)

RESELL ICATIONS  1. Inhibiting compositions comprising imidazoline mercaptocarboxylates, said imidazolines being 2-alkyl (poly (ethyleneamino) -3-diazolines-1,3 corresponding to the general formula)

 in which R is a linear or branched, saturated or unsaturated hydrocarbon chain containing from 10 to 22 carbon atoms, and where n is a number of O to 3, the mercaptocarboxylates being mercaptoacetates or mercaptopropionates, and at least one cationic surfactant of the type alkyltrimethyl- or alkyldimethylbenzylammonium salt, an amphoteric of the alkylaminopropionic acid type and a nonionic of the oxyethylenated alkylamine type, in which the alkyl chain is a saturated or unsaturated chain containing from 12 to 22 carbon atoms.  2. Inhibiting compositions according to claim 1, comprising from 20 to 40% of imidazoline mercaptocarboxylates, 2 to 5% of quaternary ammonium, 2 to 5 W of amphoteric, and 2 to 10 of oxyethylenated amine, in solution in a water-miscible solvent.  3. Composition according to claim 2, in which the water-miscible solvent is taken, alone or as a mixture or as a mixture with water in the group consisting of isobutanol, butylglycol, monoethylene glycol, monopropylene glycol.  4. Use of the compositions according to either of claims 1 to 3, for the inhibition of the corrosion of iron and ferrous metals in contact with carbon brines or two-phase hydrocarbon / carbon brine media, said compositions being taken at a rate of 5 to 200 ppm, counted as imidazoline mercaptocarboxylates relative to the corrosive medium.